Forestcluster EffTech programme report

Intelligent and Resource-Efficient
Production Technologies
Programme Report 2008–2010

Programme Report 2008-2010

“Intelligent and
Resource-Efficient
Production Technologies”
(EffTech) Programme

Antti Asikainen
Jari Hynynen
Teemu Teeri
Tapani Vuorinen
Marjo Määttänen
Risto Ritala
Heikki Kälviäinen
Lasse Lensu
Erkki Hellén
Juha Lipponen
Janne Poranen
Pauliina Tukiainen

Content

5 Foreword

6 Introduction

12 Less is more
– intelligent and economical wood supply

26 New value chains of Finnish forest industry
utilizing domestic wood

40 Functional genomics of wood formation
Towards knowledge-based breeding of wood

52 Virtual pulp bleaching (VIP)

66 Short pulping

76 New process design methodology to reduce capital employed
and to improve flexibility (POJo)

96 Image-based measurement methods for quality in pulping
and papermaking (QVision)

114 Re-engineering paper (REP)

130 Drainage and web formation

138 Future paper and board making technologies (TuPaKat)

Copyright Forestcluster Ltd 2011. All rights reserved.
This publication includes materials protected under copyright law, the copyright for which is held by
Forestcluster Ltd or a third party. The materials appearing in publications may not be used for commercial
purposes. The contents of publications are the opinion of the writers and do not represent the official position
of Forestcluster Ltd.Forestcluster Ltd bears no responsibility for any possible damages arising from their use.
The original source must be mentioned when quoting from the materials.

ISBN 978-952-92-9269-1 (paperback)
ISBN 978-952-92-9270-7 (PDF)

4

Foreword

The forest industry has experienced one of the biggest structural market changes in
its history in the past decade, and nowhere more so than in Finland. A number of
the forest sector’s key paper products have reached a stage of permanent decline in
their life cycle, and the paper sector is facing strong pressure to both come up with
new products and applications and to improve the cost and capital efficiency of its
existing products and assets.

These external pressures have widened and opened the industry’s research
strategy, research processes, and resource structures. One of the key structural
shifts has been the creation of Forestcluster Ltd – the Strategic Centre for Science,
Technology and Innovation for the Finnish forest cluster. The preparation and
implementation of research programmes within Forestcluster Ltd has focused on the
entire value chain. The EffTech programme is a prime example of this approach as
it was drawn up jointly by players representing the whole value chain, from forest
to printing house. This has had a refreshing and revitalising influence on the
programme’s content and on the work of the research community.

EffTech was the first programme launched by Forestcluster Ltd. The goal of the
EffTech programme was to produce knowledge for radically new solutions. This sets
the bar high regarding the usability of research results, yet the rewards of success
are all the richer for it. The programme received strong support from all Forestcluster
shareholders, including funding. In addition, Tekes the Finnish Funding Agency for
Technology and Innovation is a major funding party of the programme. Tekes has al-
so been active in steering and inspiring the programme participants towards setting
and attaining its high goals.

The fruits of these efforts will only be materialized when the results are directly
utilized by the industry or further developed in application projects. I therefore urge
all parties to explore the obtained and reported results carefully and to leave no stone
unturned in the search for innovative uses and applications.

Raino Kauppinen
Stora Enso Oyj
Chairperson of Programme Management Group

5

Introduction

Abstract
The Intelligent and Resource-Efficient Production Technologies (EffTech) Programme was
launched by Forestcluster Ltd (the Strategic Centre for Science, Technology and Innovation
for the Finnish forest industry cluster) in 2008. The goals of the programme are to improve
the competitiveness of the Finnish forest cluster by developing radically new energy- and re-
source-efficient production technologies and by finding ways to reduce the capital intensiveness
of the cluster. EffTech is divided across three work packages (WPs) based on focal areas of the
programme: Raw material availability, Modelling and measurements, and Processes and
processing. The programme portfolio for the first two years included ten research projects
with a total budget of EUR 11 million, as well as three consortium projects with a total budget
of EUR 8 million.

6

1. Background 2. Management of
The Finnish forest cluster published its
the programme
research strategy (‘Finland – the leading
forest cluster by 2030’) in October, 2006. The first phase of the EffTech programme
The strategy outlined the future R&D was led by a Management Group (MG)
priorities for promoting profitable de- comprising representatives from both in-
velopment of the industry as a whole. dustry and academia. The EffTech proj-
In 2007, Forestcluster Ltd was founded ects were divided into three Work Pack-
with the main task of implementing the ages (WPs) and WP Managers were ap-
national research strategy. Forestcluster pointed to coordinate work between the
focused the cluster’s research activity in projects and WPs. The research tasks
three key areas based on their strategic within the projects were performed un-
impact and on the potential for added value der the leadership of Project Managers,
generation through cooperation between and projects were reported to the MG by
Forestcluster owner companies. The cho- Work Package Managers. The execution
sen areas were: Intelligent and resource- of EffTech was coordinated by Programme
efficient production technologies, Future Manager Pauliina Tukiainen of VTT.
biorefinery, and Future customer solutions. The main tasks of the Management
The EffTech programme was the first Group have been to supervise the prog-
research programme launched by Forest- ress of the programme with respect to
cluster. The Forestcluster owners, togeth- the objectives of the national forest clus-
er with representatives from research or- ter research strategy and the EffTech pro-
ganizations, defined the research themes gramme plan, and to assess the scien-
and key targets of the programme as well tific progress and techno-economic fea-
as the evaluation criteria for project pro- sibility of the results. In 2009, the MG’s
posals at the workshop. Based on the main tasks included mid-term evaluation
outcomes of the workshop, Forestcluster of the programme, organization of the
issued a call for research projects for the EffTech Workshop and discussions with
EffTech programme in spring 2008 and the shareholder companies of Forestclus-
over 30 project proposals were submit- ter Ltd in order to harmonize the EffTech
ted to Forestcluster as a result. The For- programme with the companies’ research
estcluster Research Committee prepared strategies and to define the most impor-
the structure, contents and targets of the tant focus areas for the coming three-
programme, and ten projects were finally year period. In 2010, the MG re-focussed
selected for inclusion in the EffTech pro- the EffTech programme and the prepara-
gramme portfolio. tion of programme proposals for the pe-
riod 2010–2013.

7

The EffTech Management Group had divided into three work packages (WPs)
the following members: based on the focal areas of the pro-
• Raino Kauppinen, Stora Enso, gramme: Raw material availability, Mod-
Chairman elling and measurements, and Processes
• Lars Gädda, Forestcluster Ltd and processing (Figure 1).
• Jyrki Huovila, Metso Paper The objective of WP1 (Raw material
• Erkki Hellen, VTT, WP3 Manager availability) was to increase the availabil-
• Jari Hynynen, Metla, WP1 Manager ity and supply of high quality raw materi-
• Mika Hyrylä, UPM-Kymmene al from Finnish forests. WP1 consisted of
(Timo Koskinen until June 2009) three projects, each focusing on raw ma-
• Jukka Kejonen, Myllykoski terial availability but addressing the prob-
• Juha Mettälä, Tamfelt lem from different perspectives, applying
• Olavi Pikka, Andritz different methods and addressing differ-
• Ismo Reilama, Metsä-Botnia ent time horizons. The Less is More proj-
• Risto Ritala, TUT, WP2 Manager ect aimed at resolving wood supply issues
• Petri Silenius, Kemira through more efficient use of existing la-
• Kenneth Sundberg, Ciba bour and machine resources. The focus
• Pauliina Tukiainen, VTT, Programme of the New value chains project was on
Manager finding new end-product oriented, profi-
• Mikko Ylhäisi, Tekes table and environmental friendly forest
industry value chains based on domestic
wood supply. The Functional genomics of
wood formation II project objective was
3. Programme portfolio to identify the key genetic determinants
and goals responsible for wood development in for-
est trees with the aim of utilising them
The goals of the of the first phase of the in forest tree breeding to control wood
EffTech programme were to improve the growth and wood quality.
competitiveness of the Finnish forest clus- The goal of WP2 (Modelling and mea-
ter as a whole by developing radically new surements) was to achieve marked im-
energy and resource efficient production provements in the use of modelling and
technologies and by finding means to re- simulation in order to increase the pace
duce the capital intensiveness of the clus- of development of new process concepts.
ter. The objective was to reinforce the WP2 consisted of four projects. Of these,
Finnish forest cluster’s leading position in Virtual pulp bleaching (VIP) and New pro-
the field of large-scale fibre-based paper cess design methodology to reduce capital
and board production technology by devel- employed and to improve flexibility (POJo)
oping more sustainable solutions. Produc- concentrated on production system model-
tive domestic forest resources and compet- ling. The POJo project was tasked with de-
itive wood supply are crucial to the vitality veloping an industrially applicable first ver-
of the Finnish forest cluster. Increasing the sion of the multiobjective and bi-level de-
availability and supply of high quality raw sign methodology and demonstrating its
material from Finnish forests in a sustain- applicability by means of a case study.
able and cost-efficient manner has there- The VIP project was focused on modelling
fore been one of the main strategic targets chemical pulp bleaching at the molecu-
of the EffTech programme. lar level using phenomenon models. QVi-
The EffTech programme portfolio for sion focused on image-based measure-
phase one included ten research projects ment and characterization methods relat-

8

Figure 1. EffTech programme portfolio.

Intelligent and Resource-Efficient Production Technologies
Programme Portfolio

Workpackage 1 Workpackage 2 Workpackage 3
Raw material availability Modelling and measurements Processes and processing

Less is more Virtual pulp bleaching Re-engineering paper

Future paper and board
New value chains Short pulping
making technologies

Functional genomics New process design
Drainage and
of wood formation concept for capital
web formation
efficiency and flexibility

Qvision

ed to quality in pulping and papermaking, 4. International
while the Short pulping project developed
new methods for chemical pulp quality. cooperation
The goal of WP3 (Processes and pro- International co-operation is built into
cessing) was to develop new resource- the EffTech programme and plays an im-
efficient production technologies which portant role in the development of nov-
are profitable, support sustainability goals el resource-efficient production technolo-
and enable a range of new products. The gies. Research organizations are encour-
projects approached the paradigm of cur- aged to pursue international collabora-
rent papermaking from different direction for this purpose and with the aim of
tions. The Re-engineering paper project strengthening the position of Finnish re-
sought new resource-efficient production search groups in international commu-
technologies for sheet production using nities and opening up new co-operation
cellulose nanofibres, and developed ad- opportunities. The programme has par-
vanced modelling tools to speed up prod- ticipated in cooperation with 7 countries
uct and process development. The TuPaK- in total (Canada, Germany, the UK, Isra-
at project took a broader view by draw- el, Sweden, Turkey and the USA). Close
ing up projected scenarios and technolo- links with the international scientific com-
gy roadmaps for 2030 as well as propos- munity are maintained, in particular, in
als for new radical production technolo- the areas of functional genomics of wood
gies for forest-based businesses. In the formation, forestry, wood procurement,
SUORA project, a unique new convertible chemical pulping, multi-parameter op-
papermaking research environment uti- timization, image analysis and nanocel-
lizing the latest papermaking technology lulose research. The cooperation initiat-
was developed for the needs of the Finn- ed during EffTech phase one will be con-
ish forest cluster. tinued in the second phase of the pro-
gramme.

9

The EffTech programme is designed programme’s current research activities
in the way that overlapping research ac- and results. Approximately 100–150 at-
tivities with related projects are mini- tendees participated in each seminar. The
mized and the synergy between other re- EffTech Workshop was held on 7th Octo-
search activities is maximized. Many of ber 2009. The workshop provided a cur-
the researchers working within the pro- rent overview of the EffTech programme
gramme also contribute to other related and generated new ideas and discussion
projects, which ensures active informa- regarding the key targets for the pro-
tion exchange and rapid application of re- gramme’s second phase. The outcome of
sults. EffTech research groups have, for the workshop provided the basis for build-
instance, participated in the European ing phase two of the programme.
Community’s 7th Framework Programme
projects and several COST actions.
The EffTech programme’s core re-
search also supports several industry-
6. Future plans
driven projects aimed at developing in- The second phase of the EffTech pro-
dustrial applications. While these projects gramme will continue as two separate yet
are confidential, active participation of in- strongly interlinked programmes: efficient
dustrial partners within the programme networking towards novel products and
ensures active information flow, which in processes (EffNet) and value through in-
turn speeds development. tensive and efficient fibre supply (EffFi-
bre). The division into two separate pro-
grammes sharpens the programme focus
and enables more flexible incorporation of
5. Dissemination of new participants into the programme. The
results EffFibre and EffNet programmes together
cover the whole value chain - from for-
The dissemination of the EffTech pro- est to print houses.
gramme information is carried out using The programmes have a combined
a number of different tools, the most im- budget of EUR 26 million for 2010–2013,
portant being the Forestcluster research and involve a large number of forest clus-
portal, which is accessible to EffTech pro- ter companies and leading research insti-
gramme participants (http://www.forest- tutes. Tekes, the Finnish Funding Agency
clusterportal.fi/index.php/Project_Por- for Technology and Innovation, provides
tal), and the Forestcluster Ltd website. 60 percent of the programme budget.
Detailed project reports and publications The EffFibre programme focuses on
are available through the Forestcluster improving the availability and supply of
portal. In addition, the programme’s re- high-quality raw material from Finnish
search projects have held workshops, re- forests and developing novel production
searcher training events and meetings for technologies for chemical pulping. The tar-
industry and researchers. EffTech semi- gets of the EffFibre programme are to in-
nars have also been held on the 18th De- crease the availability of wood biomass, to
cember 2008, 6th October 2009 and 16th improve the efficiency of the wood supply
December 2010. The aim of the seminars value chain, and to enhance the utility
was to bring together experts from aca- value of Finnish wood. Research is aimed
demic and industrial fields and to provide at generating concepts for improving the
a comprehensive overview of the EffTech value creation potential of Finnish wood,

10

a raw material with special quality charac-
teristics. At the same time, the goal is to
improve efficiency by increasing pulping
yield and reducing the energy consump-
tion and capital intensiveness of pulp pro-
duction.
The goal of the EffNet programme is
to improve the competitiveness of the
entire forest cluster by developing radi-
cally new energy- and resource-efficient
production technologies and by finding
means to reduce the cluster’s capital in-
tensiveness. Alongside new energy- and
resource-efficient production techno-
logies for web products, the EffNet pro-
gramme focuses on designing nanocellu-
lose-based production concepts and nov-
el, innovative products. The successful re-
search and promising results achieved to
date by the EffTech programme have cre-
ated good prospects, and continuation of
the programme’s research is expected to
lead to commercial nanocellulose break-
throughs in the near future. As a parallel
goal, the EffNet programme aims to con-
solidate the Finnish forest cluster’s lead
position in the field of large-scale fibre-
based paper and board production tech-
nology through the development of more
sustainable solutions.

11

Less is more
– intelligent and economical
wood supply

Project Manager Antti Asikainen, antti.asikainen@metla.fi

Duration of the project 1.6.2008–30.8.2010

Project budget EUR 630,000

Project partners Role of participating organization

Finnish Forest Research Discrete-event simulation of wood harvesting fleet,
Institute (Metla), Joensuu Unit logistical setup of harvesting systems

Terramechanics, forest machine technology for soft soils,
Metla, Vantaa Unit
harvesting methods for young forests

Technology and logistics of silviculture and regeneration
Metla, Suonenjoki Unit
works in forestry

VTT Technical Research Raw material quality, storage trials, processing (pulping)
Centre of Finland technology for stored material

12

Abstract
The Less is more project aimed at more efficient use of existing labour and machine resources
in wood supply. Soil sensing forest machinery and new models for optimizing machine resource
allocation in forest operations on soft soils were developed. In addition, the impacts of pro-
longed wood storage on pulp quality and energy consumption of pulping were studied. The re-
sults showed that Finland’s current harvesting fleet can be used more efficiently by equipping a
proportion of machines for year-round harvesting on sensitive soils. It was also found that wood
supply can be based on larger buffer stocks and longer storage periods than at present without
endangering pulp quality or the cost efficiency of wood supply.
A soil torque based device and a soil layer scanner were developed and tested to measure
and predict the bearing capacity of soils. The torque based measurement system and the sonar
scanning system provided good estimates of overall trafficability and point load bearing capaci-
ty, respectively. Simulation studies showed that it is profitable for a forest machine entrepreneur
to invest in equipment enabling year-round soft soil harvesting in harvesting districts, where the
share of peatland forest is remarkable in Finland. Long-term storage of spruce pulpwood caused
some deterioration of pulp colour in mechanical pulping, but this could be compensated for with
appropriate bleaching treatments. In addition, the savings in transport costs were higher than
those of additional chemicals or other treatments in the pulping process.
Soil trafficability assessment can be used for more effective timing of wood harvesting on
soft soils. More efficient spot assessment of soil bearing capacity enables avoidance of deep rut
formation and machine sinkage. The pulping trials with stored wood showed that long-term buf-
fer storage can be used to even out wood supply and to lower transport costs. The quality as-
surance and processing of wood should be based on wood supply models that enable soil sensi-
tivity estimation in order to ensure cost efficient harvesting and transport and optimal end prod-
uct value.
Keywords: wood harvesting, wood quality, sensitive soils, harvesting fleet management,
TMP pulping

13

1. Project background by reducing the amount of water trans-
Strong seasonal and market-driven fluc- ported to mills within the wood raw mate-
tuations in wood demand as well as an in- rial, for example by allowing wood to dry
creasing supply of wood from forests on prior to long-distance road transportation.
sensitive soils are challenging wood supp-
ly in Finland. To smoothen supply, wood
storage is needed at different stages of
the wood procurement chain as the har-
2. Project objectives
vestability of forest stands and the wood The long-term goal is to find means of
demand of mills vary independently. reducing fibre costs for mills through im-
In addition, reduced wood imports proved forest operations and through bet-
and shortening winters call for more ef- ter understanding of the effects of wood
ficient use of the existing domestic wood storage and drying on wood properties
harvesting fleet and its manpower. The and TMP processing. The key objectives
low bearing capacity of peat soils low- are to:
ers the productivity of peatland for- • Develop methods for collecting data
est harvesting and can cause signifi- on the mechanical properties of
cant ground damage. Forest machines soils, particularly peatland soils
can be equipped with wider tracks or ex- • Validate methods of assessing the
tra wheels for improved trafficability, al- impact of harvesting machinery on
though these investments swell oper- soils
ational costs. Forest operations on soft • Identify and quantify the most
soils can also be improved by more pre- cost-effective options with regard
cise advance estimation of soil bearing to machine modifications and
capacity. This could be done by measur- operating methods when the share
ing soil properties and using, for example, of peatland logging is high, taking
weather data to estimate the moisture silvicultural operations also into
and strength of soil layers. In addition, consideration
machines could measure the depth of the • Investigate the impact of different
peat layer as they move on site. The da- productivity factors on the loading
ta collected could then be further pro- sequence of forwarder work. A
cessed for use in tutoring machine ope- special focus area was clarification
rators in efficient machine driving. of the influence of loading point
It is commonly understood that wood positioning for operator assisting
needs to be as fresh as possible when system
used for pulping. Freshness is ensured • Assess the differences between
either through rapid wood procurement fresh and over-summer, land-stored
operations or by special wood storage ar- spruce logs
rangements. Maintaining wood procure- • Investigate the plate gap
ment resources at a level that ensures phenomena of these different wood
seamless year-round delivery of fresh qualities during TMP refining
wood from stump to mill requires exten- • Analyse the brightness and
sive machinery investments, thus increas- bleachability of the studied wood
ing the unit costs of all delivered wood. qualities
Special wood storage arrangements such • Investigate possibilities for
as sprinkling or cold storage also increase improving brightness and
wood costs. Considerably lower wood pro- bleachability through chip or TMP
curement costs can, however, be achieved pulp washing.

14

3. Research approach dination and conception of the 3D envi-
The machine mobility study was based ronment were achieved in the boom han-
on an experimental approach. The test dling tests. Detailed studies of forwarder
tracks were located on both mineral and work were carried out in three virtual log-
peat soils and were passed over first by ging environments including one final fell-
a 6-wheeled John Deere 1070D harvesting and two first thinning sites.
er and then by an 8-wheeled John Deere An experimental approach was used
1110D forwarder. The soil shear modulus to quantify the differences between fresh
was measured manually using a spiked and stored spruce logs, and their refin-
shear vane developed by the Finnish For- ing and bleaching behaviour in TMP pro-
est Research Institute (Metla). duction. Both raw material types were
A method for continuous ultrasound handled in the same way: logs were de-
measurement of wheel sinkage was debarked, chipped and refined at a pilot
veloped and tested. The system measures scale. The material quality was tested at
the distance between the soil surface and numbered stages (Figure 1):
a specified position on the vehicle. The development of brightness from
Based on the assumption of harvest- wood to pulp was closely investigated.
er motion resistance being capable of pre- The formation of coloured structures was
dicting forwarder motion resistance on monitored by UV-Vis reflectance mea-
the same site, a CAN bus based measure- surements. The reflectance spectra were
ment of harvester motion resistance for recorded by a Perkin Elmer Lambda 900
mobility mapping was developed. spectrometer equipped with an integrat-
A numeric logging simulation mod- ing sphere. The entire spectral region
el was compiled using WITNESS process (200–800 nm) was measured from thick
simulation software. Genuine logging Bühner sheets (pH 5.0–5.2). The chro-
sites and logging contractors were se- mophore reactions responsible for the
lected for the simulations from extensive brightness changes were investigated by
and accurate logging history data con- difference reflectance (ΔR) spectra.
tributed by major forest companies. The The refining conditions were varied in
simulation model consisted of three har- order to achieve different heat treatments
vester-forwarder units and one low-bed (Figure 2):
truck for machine relocations. One of the Chip washing and pressing were car-
three harvester-forwarder units was used ried out prior to the laboratory-scale re-
for soft soil harvesting during summer. In fining in order to assess the effects of
order to increase the trafficability of the chip washing on pulp brightness and
machines, the logging unit was modified bleaching response (Figure 3). A Frex pis-
with purpose built band tracks for use on ton press was used to carry out the test-
soft soils in non-frozen ground conditions. ing programme using ion-exchanged wa-
Four modification classes in terms of the ter, DTPA and sulphuric acid solutions. A
maximum ground pressures of the ma- wing refiner located at VTT Jyväskylä was
chine concepts were created for the soft used for refining the treated chips. Sim-
soil logging unit. Three contractors (A, B, ilar washing treatments were performed
C) were modelled. on TMP pulp samples using a Perti tester
A virtual forwarder simulator was cho- at VTT Otaniemi to compare whether the
sen for work pattern and feedback as- washing treatment is more effective prior
sessment. Five experienced operators and to or after refining.
five students participated in the trials. Af-
ter 15 minutes of training, motor coor-

15

Figure 1. Quality testing of material in Figure 2. Experimental setup of refining.
the refining process.

Preheating 300 kPa
Logs Debarking Chips Preheating 1st stage 2nd stage Refined
& chipping refining refining Fresh or
to 3
dry chips No 300 kPa SEC
preheating levels
1 2 3 4
500 kPa

Figure 3. Processing steps in chip pressing and washing experiments with fresh
and stored chips. Samples were taken at numbered stages: 1. condensed steam,
2. squeezed filtrate, 3. fresh impregnation liquor, 4. squeezed impregnation liquor,
5. squeezed washing water.

Fresh or No Deionized Washing with Wing
FREX Pressing

FREX Pressing

FREX Pressing
Stored chips steaming water ionized water refining
of chips
Steaming H2SO4
pH 1.5

0.3 % DTPA

1 2 3 4 5

4. Results mance where high rear wheel sinkage
can be noted. Occasional negative read-
4.1 New methods for assessing ings were caused either by vehicle pitch
trafficability on sensitive soils or surface irregularities. Rebound of the
The spiked shear vane proved capable of rut bottom after the vehicle pass was con-
measuring peatland surface strength and siderable: rut depth had very little corre-
predicting rut depth (Figure 4). Measure- lation with wheel sinkage.
ment of stony mineral soils was, however, The technique opened up new pos-
problematic due to insufficient spike pen- sibilities for examining vehicle perfor-
etration depth. mance. The true sinkage of the vehicle
The results of continuous ultrason- wheels is presented in Figures 6 and 7.
ic measurement of wheel sinkage were The correlation between harvester and
difficult to interpret with stony mineral forwarder average front and rear wheel
soils as the position of the vehicle chas- true sinkage was 0.79, and the suit-
sis affected the measurement. Reason- ability of mobility mapping by harvester
able measurement results were, how- was thus found to be good. The studied
ever, achieved on peatland sites. Figure 6-wheeled harvester was found to per-
5 gives an example of harvester perfor- form unfavourably in peatland operations,

16

Figure 4. Rut depth vs. shear modulus for
the studied mineral and peat soils.

Figure 5. Ultrasound sinkage and manual rut
measurement results on peatland.

17

Figures 6 and 7. True wheel sinkage of the studied harvester and
forwarder measured with the ultrasound technique.

since the true sinkage of its rear wheels creasing machine down-time and lowering
was 3.1 times that of the front wheels, as unit costs for the whole year. In the con-
compared to the corresponding figure of tractor A scenario (peatland logging com-
1.7 for the forwarder. Placement of the ul- prising 25% of the total removal), for in-
trasonic transducers was critical to avoid- stance, in which peatland forest was har-
ing damage and erroneous readings. vestable either only during winter or year
round, the most economical approach was
to purchase soft soil equipment and mod-
4.2 Operational efficiency in year- ify one logging unit for summertime peat-
round CTL harvesting on sensitive land logging (Figure 8). Depending on the
soils and differences between modification class for peatland loggings,
operators in forwarder work the decrease in unit costs was 1.2 to 3.8%
Unit costs varied from 9.5 to 11.9 €/m³ for year-round logging compared to peat-
with contractor A, from 12.6 to 15.8 €/ land logging only during wintertime.
m³ with contractor B and from 15.2 to When the share of peatland logging in-
18.7 €/m³ with contractor C depending creased to 30% or more, there was a def-
on the study scenario. The mean pro- inite need to modify one logging unit for
ductivity of peatland loggings during the soft soil logging during summertime.
winter period was 12.0 m³/h, where- On general comparison, none of the
as the productivities of year-round peat- modification classes clearly outperformed
land logging with the modification class- the others in monetary terms. Analysis of
es of “improved bearing”, “high bearing” the study cases of all contractors indicat-
and “extreme bearing” were 10.5, 10.7, ed that when the share of lowest bearing
and 10.9 m³/h, respectively. Regardless capacity peatland sites is high and peat-
of the higher logging productivity during land loggings are carried out throughout
wintertime for peatland sites, the limited the summer period, the most economical
number of logging sites during the non- approach is to invest in achieving the “ex-
frozen period favoured the harvesting of treme bearing” modification class. Addi-
some peatland sites during summertime, tionally, the smaller the ground pressure
thus increasing logging opportunities, de- of the machine, the less rutting problems

18

and work interruptions occurred, and the nificantly if the base machine was used
more the machine was capable of driving year round. This is an essential factor in
itself free after sticking in peaty soil improving cost-competitiveness in com-
One significant cost saving method is parison to manual planting. One of the
to schedule an optimal cutting order for three logging units could be dedicated to
peatland sites according to their ground planting seedlings and extracting logging
bearing capacity class. Sites classed with residues and stumps during the summer.
the lowest ground bearing capacity should In the virtual simulator study, exten-
be harvested during winter when the sive variation was found between opera-
ground is frozen and the highest bearing tors in both the velocity and the length of
site classes should be summer harvested. trajectory of the boom tip. The most pro-
According to the simulation results, ductive operator performed at the highest
use of excavator-based forest machines velocity and the shortest length of trajec-
for peatland harvesting during autumn tory per average grapple load cycle. Re-
and winter and for seedling planting dur- spectively, the slowest operator had the
ing summer was a feasible and cost-effi- second longest boom tip trajectory. Min-
cient option. Planting costs decreased sig- imal difference was found in the perpen-

Figure 8. Logging costs of contractor A per study scenario. With the modification
class “basic”, peatland loggings were carried out only during winter, whereas
the other modification classes enabled year-round peatland logging.

Share of peatlands,% ~10 ~10 ~10 ~10 ~25 ~25 ~25 ~25 ~40 ~40
Length of winter, mth 3.5 3.5 2 2 3.5 3.5 2 2 3.5 3.5
Summer loggings, m³ 50,500 41,300 50,500 41,300 50,500 41,300 50,500 41,300 50,500 41,300
Down time/chain, h 107 356 415 661 8-111 202-366 ~15 ~230 0 ~50
Peatland loggings, m³ 9,326 9,326 9,369 9,326 ~24,000 ~24,000 ~24,100 ~24,100 ~40,500 ~40,600
Total removal, m³ 116,180 106,320 92,900 84,010 109,000 100,000 ~103,200 ~95,350 ~105,800 ~104,000
-112,500 -106,500

19

dicular distance (x-component) to the Figure 9. Difference reflectance spectra
pile, whereas the difference between op- showing the difference between fresh
and dry wood chromophores and the
erators in the roadwise distance (y-com-
difference between the pulps produced
ponent) to the pile was larger.
from these irrespective of the refining
conditions

4.3 Quality control with
procurement chains relying on
buffer ood stocks
w

4.3.1 Differences between fresh
and stored spruce logs and TMP
pulps derived from them
Over-summer land-stored spruce pulp-
wood had clearly higher dry matter con-
tent (72% vs. 43%) and about 4 percent-
age units lower brightness than otherwise
similar fresh spruce pulpwood. The UV-Vis
spectra of wood pellets of the raw mate-
rials (Figure 9) reveal that the content of
structures absorbing at 460 and 490 nm,
and to some extent also >600 nm, is high-
er in dry wood. These structures tend to
be formed during wood storage, whereas
structures absorbing ~400 and 600 nm are
formed mainly during refining.
Chromophores formed during wood Figure 10. Difference reflectance spectra
storage or during pulp refining can be re- showing coloured structures remaining
moved more efficiently from fresh wood to a higher extent in dry pulp after
than from dry wood during peroxide peroxide bleaching (1.5, 3 and 4.5%
bleaching (Figure 10). H2O2).

4.3.2 Plate gap phenomena
The dryness of wood does not influ-
ence thermo-mechanical pulping unless
the moisture content remains above fi-
bre saturation point. With the exception
of optical properties, pulp properties be-
tween fresh and stored wood were rel-
atively similar. The similar shape of the
temperature profiles at the plate gap in-
dicates similar pulp flow between fresh
and stored raw materials. Stored wood
caused slightly higher temperature levels
(Figure 11), possibly due to higher pulp
consistency during refining. The lower
pulp freeness level obtained for dry chips

20

Figure 11. The temperature and shear forces distribution at the plate gap
at first stage refining of fresh and dry chips with SEC 1.54 MWh/t.

Figure 12. Effect of chip washing treatments on pulp brightness.
Comparison with pilot TMP pulps (TMP 13 fresh and TMP 26 dry) prepared
from unwashed chips, although the pulps prepared from washed chips
were prepared with a wing refiner. TMP-Q indicates the pulp brightness
after chelation.

21

Figure 13. Effect of chip pretreatment on final brightness after peroxide bleaching
(3% H2O2, 2.25% NaOH, 2% silicate, 15% consistency, 70°C, 120 min).

Figure 14. Effect of efficient pulp washing aimed at metals removal and high final
brightness after peroxide bleaching (3% H2O2, 2.25% NaOH, 2% silicate, 15%
consistency, 70°C, 120 min).

22

(391 ml vs. 459 ml) may be related to the fective as DTPA or acid washing, suggest-
greater shear forces measured at the out- ing that metals do not play a significant
er parts of the plate gap. role in this brightness increase.
After pulp washing, the bleachability
4.3.3 Chip washing results are similar to those after chip pre-
treatments (Figure 14). The final bright-
The effect of chip pretreatments on pulp ness of the bleached dry pulp remains
brightness after refining is shown in lower regardless of the pretreatments,
Figure 12. Normal pulp chelation with- and pulp washing with water seems to be
out chip pretreatment results in similar as efficient as DTPA or acid washing. In
brightness increase levels to chip pre- this case, the brightness difference bet-
treatments, especially in the case of fresh ween bleached fresh and dry pulp re-
wood. After chip pretreatment, pulp che- mains similar after pulp washing. In this
lation has no additional effect on pulp respect, chip washing can be more bene-
brightness. Unexpectedly, water treat- ficial and may be related to lower for-
ment is as efficient as DTPA or acid wash- mation of coloured structures during re-
ing, suggesting that the brightness in- fining.
crease is due to the washing/extraction
of other wood components than metals.
The effect of chip pretreatments on
pulp bleachability was evaluated by small-
5. Future plans and key
scale bleaching experiments (3% H2O2, development needs
2.25% NaOH, 2% silicate, 15% consis-
tency, 70°C, 120 min). Before bleach- In silvicultural practices such as the tend-
ing, all of the pulps were chelated using and clearing of young stands, a pro-
ing 0.25% DTPA at 2% consistency, pH ductivity increase of 15% is attainable
6, and 70° for 20 min. The final bright- through full mechanization. In wood har-
ness of the bleached dry pulps remained vesting from intensively managed forests,
lower despite the pretreatments (Figure a productivity increase of 15–20 % has
13). Chip pretreatment with water seems been estimated to result from improved
again to be as efficient as DTPA or ac- material handling, use of semi-automa-
id pretreatment. However, after chip pre- tion with operator tutoring, and higher ca-
treatments the difference between the pacity utilization rate.
final brightness of fresh and dry pulps Finnish logging technology is inter-
seems to be less. nationally regarded as being of the high-
est level. A major bottleneck for larger
4.3.4 Pulp washing market penetration by Nordic forest ma-
Pulp washing experiments gave simi- chines, however, has been the poor avail-
lar results to the chip pretreatment ex- ability of operators sufficiently trained to
periments (results are not shown). Pulp operate the machines economically and
chelation results in similar brightness in- efficiently. A technological leap has been
creases in fresh and dry pulp than the achieved in the driving and manoeuvring
pulp washing treatments tested. After of forest machines through the innova-
washing, pulp chelation has no significant tive fusion of data collected by forest ma-
effect on brightness, as could be expect- chines, machine perception (i.e. machine
ed. Again, pure water treatment is as ef- vision and laser scanners) and ground

23

sensors. These data are integrated and in harvesting machinery are made. For-
interpreted into meaningful feedback and est machine manufacturers see high po-
guidance for the machine operator, en- tential in adding intelligence to machines
abling the operator to improve their per- to support driving and operating in ways
formance to match the machine’s capabil- that minimise sinkage and soil damage.
ities. In addition, tree mapping data mea- The comparative findings regarding
sured during cutting using SLAM (Simul- the processing of stored and dried pulp-
taneous (machine) Localization and (tree) wood could serve as a starting point for
Mapping principles is used in the updat- more efficient wood procurement opera-
ing and quality monitoring of stand data- tions. The proposed efficiency enhance-
bases for future stand management pur- ment would be based on the delivery of
poses. A radical innovation is to apply fibre, instead of water, to the mill. The re-
the latest findings and solutions of ma- sulting change in one of the key operat-
chine- and AI-assisted feedback, advising ing parameters, i.e. mass of wood per cu-
and tutoring of pilots/operators of moving bic meter, would have consequences for
machines such as military and aviation all wood procurement operations, from
equipment to the forest operations envi- harvester operations (actions to promote
ronment. Modern forest machines provide debarking) to all transportation vehicles
an excellent platform for studying and de- (change in size of cargo space, or total
veloping this concept. Research in this mass, or demand for trucks), and wood
area, which began under the Less is more storage operations (new storing methods,
project, is being continued within Forest- wood terminals).
cluster Ltd’s EffFibre programme.

6. Exploitation plan and
impact of results
The project results revealed strategic de-
velopment needs as well as practical so-
lutions for achieving cost efficient wood
supply. The studies concerning technolog-
ical solutions for harvesting on soft soils
are directly applicable when investments

24

7. Publications and Väätäinen, K., Lamminen, S., Sirén,
M., Ala-Ilomäki, J. and Asikainen,
reports A., Ympärivuotisen puunkorjuun kustan-
Hallongren, H., Use of track-based ex- nusvaikutukset ojitetuilla turvemailla
cavators in year-round forest operations − korjuuyrittäjätason simulointitutkimus
– A simulation study of mechanical for- (Cost effects of year-round harvesting of
est planting and peatland forest harvest- drained peatland forests). Working Papers
ing). University of Eastern Finland, Facul- of the Finnish Forest Research Institute
ty of Science and Forestry, Master’s the- 184, 2010, 57 p. ISBN 978-951-40-2276-
sis in Forest and wood technology, 2010 0 (PDF). (In Finnish)
(In Finnish).

Lamminen, S., Väätäinen, K., & Asi-
kainen, A. Operational efficiency of the
year-round CTL-harvesting on sensitive
sites in Finland – A simulation study. Pre-
cision Forestry Symposium. Stellebosch.
South-Africa. 1.3.2010. (presentation)

Lamminen, S., Väätäinen, K. & Asi-
kainen, A. 2010. Operational efficien-
cy of the year-round CTL-harvesting on
sensitive sites in Finland – A simulation
study In: Ackerman, P.A., Ham, H. & Lu,
C. (eds) Developments in Precision For-
estry since 2006. Proceedings of the In-
ternational Precision Forestry Symposium,
Stellenbosch, South Africa, 1–3 March
2010. Stellenbosch University, p. 18–21.
(extended abstract)

Sirviö, J., Särkilahti, A., Liitiä, L.,
Fredrikson, A., Salminen, L.I. & Nur-
minen, I., Prolonged wood storage
causes mainly brightness problems for
TMP. International mechanical pulping
conference, June 27–29, 2011, Xi’an, Chi-
na. Accepted.

Väätäinen, K., Discrete event simula-
tion - an advanced method for analyzing
complex logging operations In: Acker-
man, P.A., Ham, H. & Lu, C. (eds.) Devel-
opments in Precision Forestry since 2006.
Proceedings of the International Precision
Forestry Symposium, Stellenbosch, South
Africa, 1–3 March 2010. Stellenbosch Uni-
versity, p. 17. (extended abstract)

25

New value chains of Finnish
forest industry
utilizing domestic wood

Project Manager Jari Hynynen, jari.hynynen@metla.fi




Finnish Forest Research Project coordination. Analysis of the wood supply chain
Institute (Metla) (forest management, harvesting and logging, carbon
sequestration): modelling, simulation and decision
support systems, wood properties.

VTT Technical Research VTT was responsible for carbon footprint calculation.
Centre of Finland VTT and Metla co-developed a link between the MOTTI
and KCL-ECO programs, thus providing a tool for carbon
footprint analysis of the value chain.

VTT (Jyväskylä) was responsible for dense media
fractionation studies.

26

Abstract
The New value chains of Finnish forest industry utilizing domestic wood project aimed at finding
research-based solutions for cost efficiently and sustainably increasing and improving the pro-
duction and availability of high quality domestic wood. The project also aimed at improving the
energy and resource efficiency as well as environmental-friendliness of current and future forest
industry value chains. Intensive forest management was found to be justifiable for cost-efficient
and sustainable production of high quality raw material for the forest industry. Carbon footprint
analysis (LCA approach) of the production value chain for super-calendered (SC) paper showed
that the most important source of CO2 eq. was the production of the electrical power consumed
by integrated SC paper mills. Adopting a forest management strategy which combines pulp-
wood, timber and energy wood production, and the use of energy wood as an energy source
at the mill can notably decrease the carbon footprint of the value chain. Wood properties were
found to be affected by management practices, and have a notable effect on the resource and
energy efficiency of pulping processes.
The project provides new research-based information on the potential of alternative forest
management strategies to produce high quality wood and biomass for the forest industry. Fur-
thermore, new information is produced and methods developed for assessing the energy and
resource efficiency and environmental friendliness of the alternative value chains of the forest
cluster. The results of the carbon footprint analysis can be applied in assessing the environmen-
tal friendliness of alternative wood supply and wood processing chains, and in assessing their
effects on emission trading. The results are applicable in the decision making and planning of
new practices in different parts of forest cluster value chains.
Keywords: forest management, growth and yield, wood properties, carbon sequestration,
carbon footprint, LCA analysis, pulp and paper making processes, SC paper, dense media frac-
tionation, value chain

27

1. Project background • Improving the quality of domestic
wood as raw material for the forest
The aim of the Finnish forest cluster is to industry
double the value of its forest-based prod- • Improving the energy and resource
ucts and services, and to increase the efficiency of wood processing in
use of domestic wood by 25%. The whole a cost efficient and sustainable
value chain from forest to end products manner.
should be accomplished in a sustainable,
environmentally-friendly and responsible Carbon footprint analysis was used
manner. To meet this goal, the entire for- to calculate the energy and resource ef-
est cluster value chain needs to be de- ficiency of value chains. Regarding wood
veloped. In order to do this, all practices supply, the effects of alternative wood
within the value chain must be thorough- production chains on carbon sequestra-
ly analyzed and evaluated, and the most tion were assessed, as well as the car-
critical practices identified. bon footprint of practices applied in forest
Increasing the value of forest-based management, logging and the transpor-
products requires new methods in wood tation of wood. In wood processing, the
production in order to ensure the avail- energy efficiency of alternative production
ability of high quality raw material, and processes was emphasized.
new methods in wood processing in order
to ensure high quality end products. Fur-
thermore, the energy, resource and cost
efficiency of all parts of the value chain
3. Research approach
need to be improved. Life cycle and car- The research approach was based on ho-
bon footprint analyses have proved to be listic analysis of the entire value chain.
applicable methods for assessing the de- Critical parts and activities within the val-
gree of sustainability and environmen- ue chain requiring improvement in order
tal-friendliness of activities and process- to meet the project objectives were iden-
es within the value chain. tified and emphasized.
Value chains were assessed using
model-based scenario analyses. The case
study approach was regarded as a via-
2. Project objectives ble method of performing the value chain
The project addressed the energy and re- analysis. Wood supply scenarios were
source efficiency of the forest industry’s created for a set of typical Finnish for-
current and future domestic raw materi- est types which, on one hand, represent
al based value chains. The current val- the most important forest areas for wood
ue chain covers forest management for production in Finland and, on the other
wood production, logging and transporta- hand, are challenging in terms of domes-
tion of wood from the forest to the mill/ tic wood supply. The forest types includ-
plant, and the processing of wood into ed in the analyses were:
end products. 1. Norway spruce stands on high
The main objectives of the project are productive mineral soil sites in
to find research-based solutions for: southern Finland
• Improving the availability of 2. Scots pine stands on mineral soil
domestic wood sites in central Finland
• Increasing domestic wood 3. Scots pine stands on drained
production peatland sites in central Finland.

28

The objective of the analysis was product (cradle-to-gate) was analyzed for
to asses the impact of management on the SC paper production chain (Figure 1).
wood supply. We therefore applied a sim- We analyzed the carbon footprint of the
plifying assumption regarding the forest value chain, describing the greenhouse
structure. We assumed that for each for- gases emitted throughout the life cycle
est type, the forest area constitutes a uni- of the product or system. This was ac-
form “normal forest” in which stands of all complished by applying LCA calculations,
age classes from regeneration to end of taking greenhouse gas emissions into ac-
rotation are represented in equal propor- count.
tion. For this type of forest area, the an- For calculating the carbon footprint
nual wood and biomass production, car- of the value chain we integrated models
bon sequestration level, and management describing:
operation volumes are constant. • Development of forest stand
For each case study, four alternative dynamics and the effects of forest
management scenarios were created: management on stand development
1. Management according to current and wood quality
management recommendations for • Time and energy consumption of
commercial forests (‘business as wood procurement (logging, storage
usual’): combined pulp and timber and transportation)
production • Practices and processes in the wood
2. Extensive management: no processing industry
management practices in addition
to obligatory forest regeneration In the analysis, two advanced simula-
operations tion tools were combined and applied: the
3. Pulpwood production chain applying MOTTI simulator for wood supply analy-
short rotations without commercial sis, and KCL-ECO for industrial processes
thinnings and LCA calculations.
4. Management adapted to climate The results of this project are applica-
change: combined production of ble in the development of greenhouse gas
pulp, timber and biomass aiming at inventory methods. The most favourable
high levels of carbon sequestration production chains were identified with re-
in the growing stock and soil, spect to their carbon footprint.
and production of renewable raw The potential for influencing wood
material and energy to replace properties through forest management
fossil fuels. methods was investigated by collecting
and analyzing wood samples from long-
The wood supply scenarios were ana- term experimental stands with varying
lyzed with respect to the quantity and treatment intensity (thinning and fertil-
quality of raw material produced, the cost ization trials of Metla). This data was uti-
and energy efficiency of wood supply, and lized in statistical analysis and modelling
their carbon sequestration potential. The of wood properties and their response to
MOTTI stand simulation software of the alternative management methods. In ad-
Finnish Forest Research Institute (Metla) dition, the same sample tree data were
was applied in this analysis augmented utilized in fractionation (VTT, Jyväskylä)
with the Yasso model for prediction of soil and pulping studies (VTT, Espoo). The aim
carbon dynamics. of the fractionation studies was to deter-
The energy and resource efficiency of mine the potential of dense media frac-
the whole value chain from forest to end tionation of wood prior to pulping in nar-

29

Figure 1. Alternative wood supply chains from
spruce stands in southern Finland
(adapted from Hynynen, 2009).

rowing the variation of raw material prop- energy wood comprised a notable share
erties and in reducing the energy con- of total yield, resulting in the highest to-
sumption and costs of fibre production. tal yields for mineral soil sites.
Pulping experiments were carried out The net annual carbon sequestration,
to show the effect of the wood proper- average carbon storage in the growing
ties of spruce and pine, as influenced by stock and soil, and emissions from man-
growth rate, on process efficiency and agement practices were calculated for
pulp quality. spruce stands, the main results of which
are presented in Table 1.
Harvestable carbon content is propor-
tional to harvestable yield. The average
4. Results carbon storage of forest is, as expected,
highest in unmanaged stands with high
4.1 Forest industry value chains stocking densities. Despite their high car-
Mean annual wood and biomass produc- bon storage, their net sequestration ca-
tion was notably affected by management pacity is proportional to their net biomass
strategy (Figure 2). Intensive manage- yield. Ultimately, the impact of alternative
ment scenarios aiming at combined pro- wood supply scenarios on the atmospher-
duction of pulpwood and timber result- ic CO2 balance depends on how the har-
ed in the highest harvestable yields. On vested wood and biomass yield is utilized.
the other hand, extensive management The proportion of emissions related
lead to poor saw timber production and to management practices, including sil-
increased natural mortality. In climate vicultural operations, logging and sec-
change adjusted management, recovered ondary haulage, are marginal compared

30

Figure 2. Mean annual wood and biomass yields of
different forest types treated according to alternative
management scenarios (preliminary results).

31

to the carbon content of harvesting re- mill, were assumed to be the same in all
movals. Although biomass recovery in- other scenarios.
volves fairly intensive harvesting opera- Data on the different forest manage-
tions, emissions account for only a few ment scenarios and operations performed
percent of the CO2 content of the recov- was produced using the Motti software de-
ered biomass, which can be used to sub- veloped by Metla, including data on emis-
stitute fossil fuels in energy production. sions and fuel use. The received data in-
The carbon footprint calculations were cluded emissions of CO2, CO, HC, NOX, PM
made for typical Finnish SC paper, which and SO2. In addition, it contained data on
was assumed to be produced in an inte- the consumption of petrol, diesel and other
grated mill. The unit processes of the life oils, the latter of which were assumed to be
cycle are presented in Figure 3, where the lubricating oils. Emissions from the extrac-
different colours represent the different tion and processing of these fuels were tak-
life cycle stages. The other unit process- en into account using data received from
es, excluding forestry and the integrated public databases. Land use was also tak-

Table 1. Carbon statistics for the wood supply chain
in Norway spruce stands, expressed in CO2 equivalent units
(preliminary results).

Traditional
Short
rotation
Management
Extensive

management
management
adjusted
to
management

climate
change

Carbon
content
of
6 880 5 560 6 620 4 700
annually
harvested

commercial
stemwood

(kg
CO2e
year-‐1
ha-‐1)

Carbon
content
of
- - 3 630 -
annually
harvested

energy
wood

-‐1
-‐1
(kg
CO2e
year ha )

Average
carbon
189 570 136 770 210 680 487 300
storage
in
growing

stock

-‐1
(kg
CO2e
ha )

Average
carbon
221 280 225 870 158 770 325 230
storage
in
soil

(kg
CO2e
ha-‐1)

Mean
annual
emissions
115 115 138 63
of
forest
operations

(kg
CO2e
year-‐1
ha-‐1)

32

Figure 3. System boundaries and unit processes in
the carbon footprint calculations for SC paper.

en into account. The amount of wood har- sions, the impact of forest management
vested in the different scenarios was given actions are visible in the end results.
in kg dry matter (including bark) per hect- The main conclusions of the carbon
are. The amount of wood harvested and the footprint calculations were as follows:
emissions from each harvesting operation • The most important source of
varied between the scenarios. CO2 eq. was the production of the
Other data used in the calculations electricity used by the integrated SC
was derived from the KCL EcoData and mill
Ecoinvent databases. The consumption of • The TMP/kraft ratio affects the
energy, wood and chemicals by the inte- results: the bigger the share of TMP,
grated SC mill vs. depending on the TMP/ the bigger the footprint
kraft ratio as described below (4.2.1, • The biggest decrease in the carbon
Wood properties and carbon footprint of footprint of SC paper came from
the SC paper value chain, and Table 2). the use of energy wood for heat
The functional unit of the calculations production in the “FAST, climate,
was chosen to be 1,000 kg SC paper. The wood as fuel” case
results of the different scenarios are pre- • Direct emissions from forest
sented in Figure 4. The main differenc- management operations had only
es are caused by changes in energy con- a minor impact on the results
sumption by the integrated paper mill. Al- • The transport and manufacture of
though forestry operations account for on- chemicals and fillers had only
ly a small proportion of overall GHG emis- a minor impact on the results.

33

Table 2. Estimated changes in pulp and paper making processes
due to changes in wood raw material properties.

Forestry management Extensive Tapio Climate change Fibre wood
recomm. adjusted production
Growth rate of wood Slow Normal Fast Very fast
SEC , MWh/t TMP 2.9 3.2 3.5 3.8
TMP

Heat from TMP process,
3.7 4.1 4.5 4.9
GJ / t TMP

TMP, %/ t paper
55.5 48 40.5 33
Spruce, kg / t paper 509 440 371 303

Pine kraft, %/ t paper 12.5 20 27.5 35

Pine kraft, kg/ t paper 137.5 220 303 385

4.2 Effect of wood • The type of forest management
properties on pulp and paper affects the stem growth rate (slow
making processes to very fast)
• TMP refining of fast-grown wood
4.2.1 Wood properties and carbon to desired freeness requires more
footprint of the SC paper value energy per pulp tonne than refining
chain slow-grown wood
The effect of different wood production • The kraft content of the furnish has
scenarios on the carbon footprint of the to be increased due to the lower
SC paper value chain was evaluated. With strength properties of TMP made
respect to mechanical pulping and paper- from fast-grown wood raw material
making, wood and fibre properties such • The percentage increase in
as fibre dimensions or wood density are steam heat recovery (heat
significant and were affected by the dif- energy production) is assumed
ferent growth rates in the different forest to correspond to the increase in
management scenarios. energy consumption of refining
If the fibre properties change, the • For the evaluated wood production
paper properties also change. Since the scenarios, the estimated growth
quality of the end product needed to be rates, energy consumptions,
kept constant, certain modifications to the required increase in kraft content,
furnish were required (Table 2). and the change in heat energy
For the calculations, the following as- production are presented in the
sumptions were made: Table 2.

34

4.2.2 Fractionation prior to pulping ed according to the desired basic density
Pine logs representing three different of the fractions. Concentrated sodium sul-
growth rates were delivered for fraction- phate solution was used as the fractionat-
ation and pulping studies from Metla’s ex- ing medium. Continuously operating pro-
perimental plot. The logs were debarked totype fractionation equipment was used
and chipped at VTT and their average ba- for the fractionation trials.
sic densities were determined. The max- According to the results, dense media
imum density and coarseness difference fractionation can be used to increase the
of the samples were 33 kg m-3 and 15 basic density and coarseness difference
µg m-1. Some sample logs were also an- of pin chips. The maximum basic densi-
alyzed at STFI Packforsk using the Sil- ty and coarseness difference were 150 kg
viscan method. m-3 and 50 µg m-1, respectively. The me-
The chip size was reduced to less than chanical pulping trials showed density to
2 mm thickness in order to separate the be a critical raw material parameter with
earlywood and latewood using a method respect to energy consumption and pulp
developed by VTT. The resulting pin chips quality. The energy consumption differ-
were then steamed and impregnated with ence of the fractions was 47%. The frac-
water to remove air and to fill the fibre tions also showed clear differences in pa-
lumens and pores with water. Chip frac- per sample surface roughness and den-
tionation was performed using the dense sity values.
media fractionation method. The density Standard cooking trials were also car-
of the fractionating medium was adjust- ried out, but only for medium growth rate
fractions. Yield and brightness differences
between these fractions were measured,
Figure 4. Carbon footprint results for SC but further studies are required to verify
paper with different forestry scenarios. them conclusively. Use of optimized cook-
ing conditions should reveal larger fibre
level differences between fractions.

4.2.3 Pulping trials
The aim of the pulping experiments was
to show the effect of the wood properties
of spruce and pine, as affected by growth
rate, on process efficiency and pulp qual-
ity.
Compared to the corresponding slow-
grown raw material, the spruce and pine
samples with higher growth rate had low-
er fibre length, fibre wall thickness and
density, and higher fibre width. Pine
samples had lower fibre length and fibre
width, but higher fibre wall thickness and
density than the corresponding spruce
samples.
In the kraft pulping experiments,
a shorter cooking time (lower H-factor)

35

Figure 5. Total yield of the cooking experiments (left) and specific
energy consumption of the TMP refining trials (right) for spruce
and pine samples with lower and higher growth rates.

was needed for cooking fast-grown pine energy for refining to a given drainabili-
to a given kappa than for slow-grown ty than slow-grown materials (Figure 5).
pine. The alkali consumption was lower Fibre length was lower, but in the case
and the yield was one unit higher. How- of pine, the difference diminished during
ever, the situation was the reverse in the refining. The growth rate did not affect
case of spruce. The pulps made from the tensile index but, in the case of pine,
fast-grown raw materials had lower fi- tear was lower for fast-grown wood. Light
bre length than those made from slow- scattering was higher for fast-grown wood
ly grown raw materials, and also had a samples.
lower tear index at a given refining en- Pine pulps had lower fibre length, ten-
ergy level. Bulk was also lower, while air sile and tear, but higher bulk and better
resistance, internal bonding strength and light scattering than spruce pulps.
light-scattering were higher. Tensile in-
dex was higher in the case of fast-grown
spruce, although no effect was seen with
pine.
5. Future plans and
Compared to spruce, pine needed a key development needs
longer cooking time to reach the speci-
fied kappa, and had higher chemical con- The project revealed the potential of in-
sumption and lower yield (Figure 5). Pine tensive forest management to cost-ef-
pulps had lower average fibre length, low- ficiently and sustainably ensure a high
er bulk, better internal bonding strength quality raw material supply for the Finn-
and higher light scattering. Slow-grown ish forest and energy industries. These
spruce had the lowest tensile strength results, together with advanced analysis
and fast-grown pine had the lowest tear methods developed in this project, en-
strength. courage further research to extend the
In the TMP refining experiments fast- wood supply scenarios and calculations
grown wood raw materials required more from a case-study level to the practical

36

level. This work is continuing in the Eff- area for demonstrating intensive man-
Fibre programme. The goal is to produce agement is therefore being proposed by
forest management scenarios at the na- Metsähallitus and Metla to serve as a cru-
tional level, applying up-to-date informa- cial element of the EffFibre programme.
tion from the latest National Forest In- There is a clear need to improve and
ventory as the starting point. The defi- develop means of environmental com-
nition of the scenarios will be carried out munication and to produce scientifically
as close cooperation between industri- grounded solutions for evaluating the cur-
al and research partners of the EffFibre rent most important environmental indi-
programme. Scenarios will be calculated cators for forest-based industry: biogen-
applying the methods developed in this ic carbon balance (in growing stock and
project (such as the extended version of soil), water footprint, land use change,
the Motti software). and biodiversity. The EffFibre programme
In order to be widely applied, practi- will take into account these research
cal-scale demonstration areas of intensive questions and use the knowledge gained
forest management are needed. In these not only in the New Value Chains project
areas, practical feasibility can be evalu- but also other VTT projects relevant to
ated and practical methods for intensive this area. Cooperation will be carried out
forest management can be further devel- with Metla, VTT and the Finnish Environ-
oped and modified. An extensive forest mental Research Institute.

Figure 6. Integration of dense media fractionation and potential
uses of the fractions (Hakala Juha, Kaijaluoto Sakari, Kalliola Anna
and Simons Magnus).

37

The studies on the influence of raw management recommendations on indus-
material properties on the efficiency of trial wood production for forest owners.
pulp and papermaking processes will be The project produces new information and
continued in EffFibre WP2. The defibra- develops new methods for assessing the
tion phenomena of fast-grown wood in energy and resource efficiency and envi-
the TMP refiner plate gap and the effect ronmental friendliness of alternative for-
of raw material/TMP quality on the be- est cluster value chains. The results of the
haviour of furnish in the papermaking carbon footprint analysis can be applied
process will be examined in realistic pro- in assessing the environmental friendli-
cess conditions. Increased knowledge of ness of alternative wood supplies and
these mechanisms can be utilized in the wood processing chains, and in assessing
development of energy efficient defibra- their effects on emission trading. The re-
tion techniques for fast-grown wood from sults are applicable in the decision making
intensively managed forests. The effect of and planning of new practices for different
growth rate on the yield-saving potential parts of the forest cluster value chains.
of uniform and selective cooking and ox- The results regarding wood proper-
ygen delignification will be clarified in co- ties can be applied in developing new
operation with EffFibre WP4. The quali- measures in industrial wood processing.
ty of wood, pulp and end products will For example, chemical pulp mills are ide-
be linked to carbon footprint calculations. al facilities for fractionation as the frac-
Regarding fractionation prior to pulping, tionation medium can be produced from
as the next step, larger scale fractionation fly ash or green liquor, both of which are
trials with commercial equipment followed readily available at the kraft pulp mill.
by pilot-scale mechanical and chemical Pulping concepts and some potential us-
pulping are proposed. es of fractions are illustrated in Figure 6.

6. Exploitation plan
and impact of results
The project provides new research-based
information regarding the potential of al-
ternative forest management strategies
to produce high quality wood and bio-
mass for the forest industry. The results
regarding the wood supply alternatives
are applicable in practice, for example,
as a support at different levels of deci-
sion making concerning forest manage-
ment or in forest policy making. The re-
sults can also be applied in the form of

38

7. Publications and
reports
Behm, K., Liukkonen, S., Sokka, L.,
Wessman, H. Carbon footprint for dif-
ferent forest management options. VTT
Research Report. VTT-R-06769-10. 18 p.

Edelmann K., Seppänen V., Heikki-
nen J., New value chains – Wood frac-
tionation, VTT Research Report VTT-
R-04772-09, 35 p+ appendix 24 p.

Edelmann K., Seppänen V., Heik-
kinen J., New fiber properties through
dense media fractionation prior to pulp-
ing. http://www.vtt.fi/inf/pdf/sympo-
siums/2010/S263.pdf. 2009 Wood and Fi-
ber Product Seminar. VTT and USDA Joint
Activity. Harlin, Ali; Vikman, Minna (eds.).
VTT Symposium 263. VTT. Espoo (2010),
pp. 89–94

Hynynen, J. 2008. Possibilities and
methods to increase biomass production
in Finland. Presentation at KCL’s Science
Evening “Sustainability starts from the
forest” 3.9.2008.

Hynynen, J. 2010. Comprehensive car-
bon footprint analysis of the value chains
of forest industry. Presentation. SHOK
Summit 2010. Helsinki 20.4.2010.

Seppänen V., Heikkinen J. and Edel-
mann K., Pine wood fractionation into
early wood and latewood rich fractions,
Poster at the 2010 International Work-
shop on Wood Biorefinery and Tree Bio-
technology, 21–23 June 2010, Örnskölds-
vik, Sweden

39

Functional genomics of wood
formation towards knowledge-
based breeding of wood

Project Manager Teemu Teeri, teemu.teeri@helsinki.fi


Project budget EUR 1,126,000


University of Helsinki, Populus trichocarpa genome mining, gene model analy-
Department of Biological and sis, molecular biology, gene expression analysis, vector
Environmental Sciences, Plant construction for plant transformations. Gene expression
Biology (Ykä Helariutta, Jaak- analysis of transgenic overexpression lines. Growing and
ko Kangasjärvi, Kurt Fager- phenotyping transgenic lines.
stedt)

University of Helsinki, Detection of natural variation in the pine PST-1 gene,
Department of Agricultural correlations between phenotypic variation in decay re-
Sciences (Teemu Teeri) sistance and molecular variation in the PST-1 gene (to-
gether with Metla), second level candidate genes for stil-
bene biosynthesis using DNA microarrays.

Metla, Muhos Research Unit, High throughput screening of stilbenes, natural genet-
Punkaharju Research Unit ic variation in heartwood extractives, certified pedigree
(Katri Kärkkäinen) seed for orchards.

40

Abstract
The Functional genomics of wood formation II project aims at uncovering key genetic determi-
nants responsible for wood development in forest trees with the aim of using them to control
both wood quality and growth in forest tree breeding. The approach is to use several species of
forest trees (birch, poplar, spruce and pine) and to utilize the special advantages of each species.
In order to find ways to improve both wood growth and quality and to provide applicable bio-
technology tools, transgenic poplar lines and phenotypes overexpressing various ERFs (Ethylene
Response Factors), and cytokinin signalling enhancer genes were generated and screened. In
addition, natural variation in total phenolics causing differences in decay resistance of pine was
studied, and was found to be highly inherited. New methodologies for early selection of this nat-
urally late expressing trait were developed.
Furthermore, lignin biosynthesis addressing the transport of monolignols in plant cells was
studied. This knowledge can be used in the breeding of trees for altered lignin content and qual-
ity in wood.
Keywords: birch, poplar, spruce, pine, ethylene, cytokinins, lignin, stilbenes, extractives,
growth, heartwood

41

1. Project background In the Fagerstedt research group, lig-
nin biosynthesis and especially the po-
Kangasjärvi’s research group has ear- lymerisation of lignin mainly by class III
lier shown, together with our Swedish peroxidases has been previously studied.
partner (Prof. Björn Sundberg’s research This has lead to the present investigation
group at the Umeå Plant Science Cen- of the mechanism of how monolignols are
tre, UPSC), that ethylene regulates the transported from the cell cytoplasm in-
formation of tension wood and that it is to the apoplastic space where they are
a stimulator of cambial growth when di- polymerised into lignin. There are three
rectly applied to the stem (Love et al., possibilities: Golgi mediated transport,
2009). Ethylene responses are mediat- ABC transporter mediated transport or,
ed through a large family of ERFs (Eth- very hypothetically, transport through the
ylene Response Factors) characterized by plasma membrane through hydrophobic-
their highly conserved ERF domain. We hydrophilic interactions. In 2008 our col-
were able to identify 173 putative ERFs laborator Prof. Lacey Samuels and co-
in the black cottonwood (Populus tricho- workers published an article in which they
carpa) genome (assembly version1.1) very plausibly excluded the Golgi mediat-
carrying the ERF domain. The diversity ed transport of monolignols from the pos-
of ERFs explains the multifunctional role sible mechanisms. Hence, we are concen-
of ethylene in plants, and thus they are trating on the other two transport possi-
the key players in understanding the ulti- bilities.
mate function of ethylene in wood devel- In Scots pine, we have found in pre-
opment. With the specific primers against vious studies ample genetic variation in
all ERF genes we used real-time quanti- the decay resistance of heartwood (Har-
tative PCR to screen for those that were ju and Venäläinen 2002), which was to
induced by ethylene in poplar stem tis- a large degree explained by heartwood
sues and during TW formation. To mod- extractives (total phenolics, mainly stil-
ify wood formation, the most prominent benes; Venäläinen et al. 2003). Further-
candidate ERFs (20 genes) were select- more, pilot studies suggest that fami-
ed and gene constructs were made under lies with high production of stilbenes af-
a cambium/xylem specific promoter and ter seedling damage also have a high
successfully transformed (at UPSC, Prof. concentration of the same extractives in
Björn Sundberg’s research group) to gen- the heartwood of adult trees. Structural
erate poplar lines overexpressing the se- genes encoding enzymes of the stilbene
lected ERF genes. pathway will be the first candidate genes
Helariutta’s group has shown (in col- for extractives. Of these, we have made
laboration with Rishikesh Bhalerao, UPSC) a moderate sampling of the pine stilbene
that cytokinin plant hormone is required synthase gene PST-1 and identified seve-
for normal wood development (Nieminen ral SNP or small indel polymorphisms on
et al. 2008) and trees with reduced cy- the structural gene and its promoter se-
tokinin signalling are thinner and shorter quence. Association mapping of the poly-
than regular trees. To investigate whether morphisms on the candidate genes utilis-
enhanced cytokinin signalling reciprocally es linkage disequilibrium created through
increases plant biomass production, He- the history of the natural population and
lariutta’s group has constructed 25 cyto- forms the molecular basis for breeding of
kinin signalling overexpressor lines. These heartwood quality traits in forest trees.
lines over-express the Arabidopsis CKI1 Association of wood property traits with
gene, which constitutively activates the polymorphisms can be used as a first step
cytokinin signalling pathway. in selecting parental trees for seed pro-

42

duction. Metla has invaluable pedigree In the decay resistance and heart-
material for several forest tree species wood extractives task, the key objectives
important in boreal forestry. are to:
• Explore the natural variation in the
pine PST-1 gene
• Identify second level candidate
2. Project objectives genes for stilbene biosynthesis
The main objectives of the growth rate of • Develop high throughput non-
wood tasks are to: destructive analysis methods for
• Generate and screen for transgenic heartwood extractives (stilbenes)
poplar lines and phenotypes by • Investigate natural genetic variation
overexpressing various ERF genes in heartwood extractives in tree
with modified wood formation breeding populations of Scots pine
(Kangasjärvi) and with enhanced • Produce certified pedigree seed for
cytokinin signalling or its orchards.
downstream genes (Helariutta)
• Study the detailed function of
various cytokinin signalling genes
or downstream genes and ERFs in
wood formation A full understanding of the factors regu-
• Obtain trees overexpressing ERFs lating wood formation is essential in or-
or cytokinin signalling genes with der to pursue the aim of modifying wood
enhanced wood formation properties. We have previously shown
• Study the hormonal interactions that both ethylene and cytokinin are im-
crucial to wood formation. portant hormonal mediators of xylogen-
esis and that tree biotechnology offers
In the genetic components of lignin vast potential for xylogenesis stimula-
formation in wood task, the main objec- tion. We therefore generated transgen-
tive is to find out how we can alter the ic poplar trees with enhanced hormonal
lignin content and composition in the cell function to further study, dissect and con-
walls, especially in Norway spruce. Hence, firm the precise genes that control and
we are studying what are the possible modify wood formation in these hormon-
monolignol transporter genes with the al pathways. This enables us to also pro-
use of bioinformatics and by: vide tools that can be transferred to oth-
• Using specific-ABC-type transporter er tree species as required.
inhibitors in Norway spruce to find In our study of lignin biosynthesis
out the mode of transport and its regulation, we are aiming to gain
• Isolating plasma membranes from a fundamental knowledge on how the
Norway spruce xylem to identify the amount and quality of lignin could be al-
transport proteins tered in wood. Previously, we have con-
• Synthesizing activatable monolignols centrated on lignin polymerisation by per-
for use in ‘click chemistry’ oxidases. In this current project, we are
experiments to label the transport focussing on the transport of monolignols
proteins in the isolated plasma into the cell wall space. If this step can
membranes be altered, we could also change the lig-
• Testing the affect of free nin content and composition in the xylem
monolignols on the mortality and by applying the findings from the Norway
growth of plant cells. spruce breeding programme.
Natural variation in the pine stilbene

43

biosynthesis and regulatory genes are the until they reached an average height of
causative reasons for inherited differenc- 150 cm. Height growth and stem diam-
es in stilbene content and decay resis- eter from four positions were measured
tance of pine heartwood. In this part of weekly. As a result, we have observed
the project, analyses of genetic variation approximately 30 ERF lines under vari-
in the induction of stilbene biosynthesis ous over-expressed ERF genes that show
due to artificial abiotic stress (mechani- enhanced growth rate measured in stem
cal wounding) is conducted. The goal is volume. The increase in stem volume of
to find markers for pine heartwood quality these 30 ERF lines is typically between
that could be used in early selection. Wide 25 and 50% after a 14-week growth peri-
genetic variation found in stilbene con- od. Additionally, the height growth of the
centration between mechanically injured ERF lines is usually also slightly stimu-
seedlings offers a possibility for early se- lated when compared to wild type trees.
lection of naturally late expressing trait. In general, over-expression of ERF genes
did not result in phenotypes with aber-
rant stem growth habit or leaf morphol-
ogy. We have also observed one ERF
4. Results gene which resulted in stunted growth
but which also contributes to very dense
4.1 Growth rate of wood xylem structure when over-expressed in
(ethylene) poplar. In the other ERF lines we have not
Kangasjärvi’s research group has mined observed any striking anatomical chang-
and screened the expression profile for es (e.g. in cell density of xylem) to date.
all the ERF genes in response to ethyl- Almost all of the lines were also analyzed
ene in woody tissues. To modify and en- using stem samples for possible mod-
hance wood formation, the most promi- ifications in wood chemistry using Fou-
nent candidate ERFs (20 genes) were se- rier Transform Infrared Spectroscopy
lected to be over-expressed under a cam- (FTIR) at UPSC (Prof. Björn Sundberg’s
bium/xylem specific promoter, and suc- research group). We were able to con-
cessfully transformed at the Umeå Plant firm for five ERF genes that, when over-
Science Centre (UPSC) (Prof. Björn Sund- expressed, they cause very clear and
berg’s research group) to generate over- consistent changes in wood chemistry.
expression lines. Additionally, we made For some of these ERF genes FTIR analy-
an antisense gene construct encoding sis showed significant enrichment of sug-
CTR (a negative regulator of the ethyl- ars and/or increased glycosidic linkage.
ene signalling pathway) and transformed In addition, we have also detected sig-
to poplar to enhance ethylene responses. nificant alterations in lignin composition
By summer 2008, approximately 140 in- or deprived amounts of lignin as a result
dividual lines over-expressing 20 different of certain over-expressed ERF genes. On
ERF genes were generated, after the lines the other hand, we have also observed
were in vitro propagated at UPSC and lat- ERF-lines under certain overexpressed
er also at the University of Helsinki. The ERF genes which have enhanced growth
rate of over-expression for each individual rate without any obvious changes in wood
ERF line was determined by quantitative chemistry. In conclusion, it appears that
real-time PCR; almost all of the lines suc- there are many very interesting pheno-
cessfully over-expressed the target ERF types with enhanced (and one depressed)
gene. All of the 140 ERF lines were grown growth rate and modified wood chemistry.
under controlled greenhouse conditions
during autumn 2009 and winter 2010

44

4.2 Growth rate of wood ing a variety of small molecules and sec-
(cytokinin) ondary metabolites in plants, it is there-
Helariutta’s group has shown (in collabo- fore plausible that they also transport
ration with Rishikesh Bhalerao, UPSC) that monolignols. Approximately 300 puta-
the plant hormone cytokinin is required tive ABC transporter genes are found in
for normal wood development (Nieminen the spruce EST database (http://comp-
et al., 2008) and that trees displaying re- bio.dfci.harvard.edu/tgi/cgi-bin/tgi/gi-
duced cytokinin signalling are thinner and main.pl?gudb=spruce), a few of which
shorter than regular trees. Helariutta’s are specifically upregulated in differenti-
group has constructed 25 transgenic Pop- ating xylem, where lignification starts, in
ulus lines with enhanced cytokinin signal- comparison to young needles or phloem
ling. These lines over-express an Arabidop- in white spruce (Picea glauca). TC31887
sis CKI1 gene, which activates the cytoki- and CO482045 have a closest homolog in
nin signalling pathway. Based on prelimi- Arabidopsis, AtABCB15, which is coordi-
nary results from 14-week-old trees; vol- nately expressed with monolignol biosyn-
ume and biomass has increased by about thetic genes. A homolog of TC15686 is al-
50% in the best CKI1 over-expressing lines so found to be upregulated in developing
in greenhouse conditions. Stem diame- xylem in another coniferous tree species,
ter has increased and stem height has re- loblolly pine (Pinus taeda). In addition,
mained the same as the wild type in the the compression wood library, produced
best CKI1 over-expressing lines. The best from reaction wood which is characterized
lines are being selected for further, more by higher lignin content in the pine EST
detailed, analysis. database (http://compbio.dfci.harvard.
edu/cgi-bin/tgi/gimain.pl?gudb=pine),
has one ABC transporter gene, TC83625.
4.3 Genetic components of lignin In order to find the monolignol trans-
formation in wood port proteins in plasma membranes, we
Lignin, the second most abundant bio- are using a novel ‘click chemistry’ ap-
polymer on earth, plays a crucial role in proach with purified plasma membrane
the structural integrity of cell walls and proteins from Norway spruce developing
the stiffness and strength of the plant wood or lignin-forming cell culture, and
body. Monolignol biosynthesis and the azide-conjugated monolignols or adenine
lignin polymerization process in the cell nucleotides. Click chemistry (photoaffin-
walls have been well-studied in recent ity labelling) is an approach used to en-
years. However, the monolignol trans- able the specific detection of proteins in-
port mechanism from living cells to cell teracting with target small molecules. We
walls is still unclear. In this project we are are presently in the process of synthesiz-
concentrating on this mechanism and fo- ing monolignol azides which will then be
cusing especially on the involvement of activated as reactive compounds under
transporter proteins located at the plasma UV-radiation, and which then make co-
membrane and identifying them, if any, valent bonds with any plasma membrane
using mainly Norway spruce (Picea abies) proteins in their surroundings in order to
and its lignin-forming cell culture. fish out transporters. Their partial amino
We have drawn on the bioinformatics acid sequences will be used to identify the
of the spruce EST database and available corresponding genes. In order to conduct
microarray data in public domains in or- this experiment successfully, it is essen-
der to find possible monolignol transport- tial to obtain pure plasma membranes. Al-
er genes. As ATP-binding cassette (ABC) though a general method of preparation
transporters are involved in transport- of a microsomal fraction (including plas-

45

ma membranes) and two phase-partition tion between the heartwood quality (=
system is available, the optimal condi- concentration of stilbenes, concentration
tions for developing Norway spruce wood of total phenolics) of the progeny growing
have not been suggested. We have been in a field test and the heartwood quality
optimizing the technique to find the best of the seed orchard grafts (= their moth-
concentrations with dextran (Dex) and ers). The high positive correlation found
polyethylene glycol (PEG) and potassium between the concentration of total pheno-
chloride for the two-phase partition sys- lics and stilbenes as well as in wood den-
tem. We have tested Dex/PEG concentra- sity between the mothers and their prog-
tions ranging from 5.9 to 6.5% together enies indicates that selective clonal col-
with 3, 4 or 5 mM potassium chloride. In lection of Scots pine seed is a promising
addition, we have also analyzed the in- means of obtaining seedlings with genet-
fluence of water soluble polyvinylpyrrol- ic potential to produce high quality heart-
idone (PVP) and water-insoluble polyvi- wood as mature trees.
nylpolypyrrolidone (PVPP) on the prepara- High throughput screening of stil-
tion of the microsomal fraction. We have benes: from wet chemistry to optical
come to the conclusion that microsome analyses.
preparation with PVPP, followed by a two- High throughput screening of stil-
phase partition system with 6.4% Dex/ benes is needed for different kinds of
PEG 3mM potassium chloride gives the wood samples. Scots pine stilbenes PS
best yield and purity of plasma membrane and PSM exhibit unique Raman spectral
proteins, as judged by the Bradford pro- features, which enables the measure-
tein assay and glucan synthase and cyto- ment of stilbene content in wood opti-
chrome-c oxidization assays. This condi- cally. The aim is to replace laborious wet
tion will be used to perform click chemis- chemistry with optical analyses in stilbene
try with monolignol azides and activated quantification. In the initial stage, howev-
adenine nucleotides. er, both methods are needed for model-
In another set of experiments we ling. A quantification model has been per-
have tested the effect of ABC-type transformed at Aalto University (Dr. Jääske-
porter inhibitors on radioactively labelled läinen) for a single Scots pine progeny tri-
monolignol transport in a lignin-produc- al. This task has been carried out jointly
ing Norway spruce tissue culture line, and with the “Tannins and stilbenes for wood
have concluded that ABC-type transport- protection” project belonging to the Fu-
ers do not seem to take part in this trans- Bio programme launched by Forest clus-
port. This makes the ‘click chemistry’ ap- ter Ltd., too.
proach even more important. The Metla Central Laboratory in Van-
taa has developed a fast GC-MS analy-
sis method for the quantification of PS
4.4 Decay resistance and and PSM stilbenes. Concurrently, a meth-
heartwood extractives od for optical UVRRaman analysis of stil-
Trees with a genetic capability for high benes in increment cores was also devel-
stilbene production could be of consid- oped at the Aalto University School of Sci-
erable value to forestry. In order to ob- ence and Technology (A!). The results of
tain seedlings with this genetic potential, GC-MS and UVRRaman have been used
screening of the stilbene production of to formulate a preliminary quantification
the genotypes currently used to produce model for stilbenes (Dr. Jääskeläinen at
commercial seed for forest tree nurser- A!) for a single Scots pine progeny tri-
ies would be beneficial. To enable such al. According to the preliminary results,
screening, we have studied the correla- there is a clear positive correlation be-

46

tween stilbene concentration measured lings under ultraviolet induction. 24 hours
by chemical (GC-MS) and optical (UVRR) after induction pinosylvin and pinosylvin
methods. Accordingly, UVRR spectrosco- monomethyl ether could be extracted
py on solid Scots pine heartwood samples from needles of the plantlets (analysed
could provide a rapid method for stilbene on TLC plates). Induction of stilbene syn-
content measurement to replace labori- thase gene PST-1 transcription appears
ous wet chemistry. to be very fast, taking place within a few
hours after induction. In addition, this in-
4.4.1 Natural genetic variation in duction is independent of translation, in-
heartwood extractives dicating that the factors needed for PST-1
Analysis of stilbenes by GC-MS (at the gene transcription are preformed in pine
Metla Central Lab) and total phenolics (at cells. PST-1 and its possible isoenzyme
Metla’s Punkaharju Research Unit) of in- variants belong to the plant polyketide
crement cores obtained from adult Scots synthase (PKS) superfamily and they
pine breeding material from a 44-year- share considerable sequence and antigen-
old field trial (half-sib progeny trial) have ic similarities. Using an antibody raised in
been finished and preliminary estimates rabbits against the Gerbera 2PS enzyme,
of the genetic parameters have been de- another member of the PKS family, we
termined. According to the preliminary re- have been able to monitor the pine PST
sults, in the subset of breeding material protein directly. The protein becomes de-
from the progeny trials, variation in stil- tectable between 6 and 24 hours after in-
bene concentration and in total pheno- duction.
lics is wide and highly inherited. Another In order to identify genes that are
progeny trial with identical families was transcribed differentially (and possibly
sampled in April 2010. Analysis of stil- correlated with PST-1 transcription) in
benes and total phenolics of the incre- seedlings with different genetic capabili-
ment cores from this trial enables estima- ty of stilbene biosynthesis under induction
tion of the interaction between the geno- and heartwood formation, we have pre-
type and the environment. pared samples for transcriptome analy-
In young seedlings, mechanical sis. High and low reacting seedlings were
wounding induces production of heart- either wounded or induced with UV and
wood stilbenes. According to the pilot tissue samples were collected at different
study (Harju et al. 2009), there is wide time points. So as to find a suitable win-
phenotypic and genetic variation in the dow for investigating genes induced dur-
wounding response between seedlings. ing heartwood formation, sampling of in-
This offers a possibility for early selection crement cores through the growing sea-
of naturally late expressing traits. The re- son is underway to measure expression
sponse to mechanical wounding is stud- of the PST-1 gene and the presence of
ied in four-year-old seedlings. As regards PST protein.
the wounded seedlings sample, analysis
of stilbenes has been conducted for 1/5 of 4.4.3 Certified pedigree seed for
the material at the Metla Central Lab. Ac- orchards
cording to the preliminary results, there The analysis of stilbenes (at the Metla
is wide variation in stilbene concentration Central Lab) and total phenolics (at Met-
between the seedlings. la’s Punkaharju Research Unit) of the in-
crement cores from the seed orchard
4.4.2 Stilbene biosynthesis clones has been completed. According to
Induction of stilbene (pinosylvin) synthe- this pilot-scale study, there is highly sig-
sis was tested in 6-week-old pine seed- nificant correlation in the concentration of

47

stilbenes PS (r=0.83) and PSM (r=0.60) ing of the factors regulating wood forma-
and total phenolics (r=0.50) between the tion is essential to the aim of modifying
heartwood of the grafts and their proge- wood properties. Kangasjärvi’s and Helar-
nies growing in the progeny trial. More- iutta’s research groups have shown that
over, the clonal repeatability in the con- both ethylene and cytokinin are hormon-
centration of stilbenes and total pheno- al mediators of wood formation. Further-
lics between the clones is remarkable. more, they are possibly strongly connect-
Accordingly, selective clonal collection of ed to each other. In addition, we plan to
Scots pine seed offers a promising means study potential downstream genes, which
of obtaining seedlings with the genetic are regulated by ERFs.
potential to produce high quality heart- Among the extractives of Scots pine,
wood as mature trees. However, for fi- the stilbenes pinosylvin (PS) and its
nal conclusions to be made regarding the monomethyl ether (PSM) provide decay
certified pedigree seed for orchards, new resistance in timber as well as defence for
larger sampling covering several seed or- living trees against pathogens and pests.
chards is required. The long-term aim is to enhance the sup-
ply of high quality and sustainable materi-
als for the mechanical wood industry. Nat-
urally durable heartwood timber is a re-
5. Future plans and key alistic alternative to impregnated timber.
development needs
We selected the best 15 to 20 ERF lines
(out of 20 ERF genes and 140 lines) to
be re-grown under greenhouse conditions impact of results
during summer 2010 to verify enhanced
growth rate and wood chemistry. Know- Ethylene and cytokinin responsive wood
ledge of the fitness of trees over-express- traits are achieved in the tree by the spe-
ing ERF genes under natural environmen- cific expression of genes during wood de-
tal conditions is of great value, since it velopment. We have identified several
is possible to apply this biotechnology genes that regulate various hormone re-
also to other plant species that may be sponsive wood properties, and the perfor-
more appropriate for forest plantations. mance of these genes is being systemati-
Thus, our goal is to establish field trials cally tested in transgenic trees. Our main
to study the fitness of ERF lines under aim is to establish novel tools for tree
natural growth conditions, but only after breeding and to improve the future com-
transformation of selected ERF genes in- petitiveness of the Finnish forest industry.
to a Finnish hybrid aspen genotype. This This knowledge can also be transferred
will be done due to fact that the current from poplar to more widely used planta-
hybrid aspen genotype for our ERF lines tion species such as Eucalyptus through
originates from former Czechoslovakia marker assisted breeding programmes or
and is not able to acclimate and survive transgenic technology. Over-expression of
the Finnish winter. The tree transforma- ERF genes or a cytokinin signalling en-
tion will be conducted according to pub- hancer gene (such as CKI1), for instance,
lished protocols. Extensive understand- has the potential to result in permanent

48

stimulation of wood formation. Utilization 7. Publications and
of these tree biotechnologies could offer a
valuable means of providing an enhanced
reports
supply of material for the paper industry
and for bioenergy production. Additional- Scientific journals
ly, these biotechnologies could facilitate
higher wood productivity per land area, Elo, A., Immanen, J., Nieminen, K.,
potentially reducing the need to exploit Helariutta, Y. 2009. Stem cell function
further natural forest areas. during plant vascular development, Se-
As lignin forms a major proportion min Cell Dev Biol. 9:1097-106, Review.
of wood in our forest trees and affects,
for example, the strength of sawn tim- Fagerstedt, K.V., Kukkola, E.M.,
ber products and the pulping character- Koistinen, V.V.T., Takahashi ,J. and
istics of wood, it is important to know Marjamaa, K. 2010. Cell wall lignin is
how lignin biosynthesis is regulated in polymerised by class iii secretable plant
developing xylem cells. Once this is de- peroxidases in Norway spruce. Journal of
termined, we can apply this knowledge Integrative Plant Biology 52: 186–194.
in tree breeding programmes to develop
trees with modified wood properties. Harju, A., Venäläinen, M., Laakso, T.,
Trees with a genetic capability for high Saranpää, P. 2009. Wounding response
stilbene production could be of high prac- in xylem of Scots pine seedlings show
tical value to forestry. Genotypes having wide genetic variation and connection
the capability for high stilbene production with the constitutive defence of heart-
are expected to be resistant against pests wood. Tree Physiology 29(1): 19–25.
and pathogens as living trees, and at ma-
turity to produce heartwood for durable Kukkola, E., Saranpää, P. and Fa-
timber. It would therefore be important gerstedt, K.V. 2008. Juvenile and com-
to screen the stilbene production of geno- pression wood cell wall layers differ in lig-
types that produce commercial seed for nin structure in Norway spruce and Scots
forest tree nurseries. pine. IAWA journal 29: 47–54.

Love, J., Björklund, S., Vahala, J.,
Hertzberg, M., Kangasjärvi, J., Sun-
dberg, B. 2009. Ethylene is an endog-
enous stimulator of cell division in the
cambial meristem of Populus. PNAS
106:5984-5989.

Marjamaa, K., Kukkola, E.M. and
Fagerstedt, K.V. 2009: The role of xy-
lem class III peroxidases in lignification.
Journal of Experimental Botany 60 (2):
367–376.

49

Nieminen, K., Immanen, J., Laxell, M., Harju, A., Venäläinen, M., Partanen,
Kauppinen, L., Tarkowski, P., Karel J., Jääskeläinen, A.-S., Hatakka, R.,
Dolezal, K., Tähtiharju, S., Elo, A., Kivioja, A., Tapanila, T., Tanner, J. &
Decourteix, M., Ljung, K., Bhalerao, Kilpeläinen, P., Cost-effective analysis
R., Keinonen, K., Albert, VA., Helar- of Scots pine stilbenes. Sixth WSE meet-
iutta, Y., 2008. Cytokinin signaling reg- ing, October 21–22, 2010, Tallinn, Esto-
ulates cambial development in poplar. nia. (poster)
PNAS 105:20032-20037.
Immanen, J., Elo, A., Zhang, J., Hela-
Conference presentations and riutta, Y., Academy of Finland SusEn An-
posters nual Seminar 31.5.2010, Helsinki , poster

Elo, A. , Nieminen, K., Immanen, J., Immanen, J., Nieminen, K., Elo, A.,
Helariutta, Y., Cytokinin signaling regu- Helariutta, Y., Cytokinin signalling in the
lates cambial development. Auxin 2008, regulation of cambial development in Pop-
October 2008, Marrakech, Morocco (post- ulus. 2nd Poplar Symposium March 2009
er). Göttingen, Germany (poster)

Elo, A., Functional Genomis of Tree Bio- Immanen, J., Nieminen, K., Elo, A.,
mass – (CONICYT) Academy of Finland, Helariutta, Y., Cytokinin signalling in the
SusEn Programme, Annual Seminar Oc- regulation of cambial development in Pop-
tober 2009, Helsinki (oral presentation) ulus. IV Seminario de Biologia Vegetal,
October 2009 La Serena, Chile (poster)
Fagerstedt, K.V., Marjamaa, K. and
Kukkola, E., Peroxidases and lignifica- Immanen, J., Nieminen, K., Elo, A.,
tion during xylem development in Norway Helariutta, Y., Cytokinin signalling in
spruce: Combination of substrate speci- the regulation of cambial development in
ficity and location. Gordon conference on Populus. International Workshop on Wood
Plant Cell Walls, Boston, 2–7.8.2009. Biorefinery and Tree Biotechnology, June
2010, Örnsköldsvik, Sweden (poster)
Fagerstedt, K.V., Marjamaa, K. and
Kukkola, E.M, Lignification and the role Jääskeläinen, A.–S., Hatakka, R.,
of class III plant peroxidases in its poly- Kivioja, A., Harju, A., Partanen, J.,
merisation in Norway spruce. Final sym- Venäläinen, M. A rapid method to de-
posium of COST Action E50, Wageningen, termine pinosylvin content in pine heart-
Holland, 8–11–7.2009. wood by UV resonance Raman spectros-
copy. COST FP0901 Meeting in Vienna,
Felten, J., Vahala, J., Love, J., 4–5 February 2010.
Gorzsás, A., Kangasjärvi, J., Sund-
berg, B., Ethylene signaling via Ethylene Jääskeläinen, A.–S., Hatakka, R.,
Response Factors (ERFs) modifies wood Kivioja, A., Harju, A., Partanen, J. &
development in hybrid aspen. Interna- Venäläinen, M., Pinosylvin distribution
tional Workshop on Wood Biorefinery and in wood as studied by UV resonance Ra-
Tree Biotechnology, June 21st–23rd, 2010, man spectroscopy. EWLP 2010 – 11th Eu-
Örnsköldsvik, Sweden (poster) ropean Workshop on Lignocellulosics and
Pulp, August 16, 2010, University of Ham-
burg. (poster)

50

Nieminen, K., Immanen, J., Elo, A., Vahala, J., Love, J., Rao, S., Kumar,
Helariutta, Y., Cytokinin signalling in the M., Felten. J., Sundberg, B., Kangas-
regulation of cambial development in Pop- järvi, J., Ethylene stimulates cambial cell
ulus. XVI Congress of the Federation of division and enhances wood formation in
European Societies of Plant Biology (FES- Populus. IX Finnish Symposium on Plant
PB 2008), August 2008, Tampere, Finland Science, May 17th–19th, 2010, Joensuu,
(oral presentation) Finland (oral presentation)

Nieminen, K., Immanen, J., Elo, A., Vahala, J., Love, J., Rao, S., Kumar,
Helariutta, Y., Cytokinin signaling reg- M., Sundberg, B., Kangasjärvi, J., Eth-
ulates cambial activity, 19th International ylene regulates cambial cell division and
Conference on Arabidopsis Research July wood formation in Populus. 20th Interna-
2008 Montreal, Canada (poster) tional Conference on Plant Growth Sub-
stances, June 28th–July 2nd, 2010, Tarra-
Nieminen, K., Immanen, J., Elo, A., gona, Spain (poster)
Helariutta, Y., Cytokinin signaling regu-
lates cambial activity. Plant Vascular De- Doctoral theses
velopment May 2009 Banff, Canada (oral
presentation) Love, J. (2009) New insights into et-
hylene signalling and wood development.
Paasela, T., Lim, K.-J, Teeri, T.H., In- Acta Universitatis Agriculturae Sueciae.
duction of pinosylvin synthesis in Pinus Doctoral thesis No. 2009:88.
sylvestris, XVI Congress of the Federa-
tion of European Societies of Plant Biol- Nieminen, K. (2009) Cytokinin signalling
ogy (FESPB 2008), August 17–22 2008, in the regulation of cambial development.
Tampere, Finland (poster) Dissertationes bioscientiarum molecula-
rium Universitatis Helsingiensis in Viikki.
Partanen, J., Harju, A., Venäläinen, Doctoral thesis 22/2009.
M. & Kärkkäinen, K., Towards exploita-
tion of the quantitative variation in Scots
pine heartwood extractives. Wood Struc-
ture and Properties, September 6, 2010,
Slovakia (poster)

Takahashi, J., Wingsle, G., Kärkönen,
A. and Fagerstedt., K.V., Exploring the
monolignol transport mechanisms in Nor-
way spruce (Picea abies). Cell Wall meet-
ing in Porto, Portugal, August, 2010

Vahala, J., Love, J., Björklund, S.,
Kangasjärvi, J., Sundberg, B., Ethylene
is an endogenous stimulator of cell divi-
sion in the vascular cambium. XVI Con-
gress of the Federation of European Soci-
eties of Plant Biology (FESPB 2008), Au-
gust 17–22 2008, Tampere, Finland (oral
presentation)

51

Virtual pulp bleaching
(VIP)

Project Manager Tapani Vuorinen, tapani.vuorinen@aalto.fi




Aalto University/Chemical Unit operation, mass transfer and thermodynamic
Engineering modelling; reaction kinetics modelling and brightness
model development; simulator programming

Aalto University/Forest Evaluation of the relevant reactions involved, role of
Products phenolic hydroxyl groups in oxygen delignification, UV
Chemistry Raman measurements, assistance in validation of the
model

VTT Technical research centre Chromophore chemistry for the brightness model via
of Finland (KCL 1.6.2008– model compound analyses and pulp bleaching
14.6.2009) experiments; complementing chemical analyses for the
oxygen delignification and intrinsic viscosity model

VTT Technical research centre Oxygen delignification chemistry, bleaching chemistry,
of Finland analytical methods

Lappeenranta University of Mill trials planning and implementation together with
Technology (LUT) Fibera Oy

52

Abstract
A package of computer models was developed to enable simulation of pulp bleaching with-
out experimental limitations. The models are based on detailed descriptions of actual elemen-
tary chemical reactions, thermodynamics and transport phenomena. The simulation was vali-
dated as giving realistic outputs (kappa number, brightness, AOX, OX, etc.) for commonly used
bleaching stages and their combinations. The simulation model enables testing of theories and
new bleaching concepts (chemistry, chemicals and processes) and thus provides a new, eco-
nomic means of increasing knowledge of bleaching processes. The model can also be used for
guiding/focusing laboratory experiments. In the future, the tool will be applied to the develop-
ment of new industrial bleaching concepts. The approach will also be expanded to cover phe-
nomena-based simulation of wood chip cooking and biorefining.
Keywords: chemical pulp, bleaching, chromophore, oxygen, chlorine dioxide, alkaline, hy-
drogen peroxide, modelling, simulation, chemical engineering

53

1. Project background documented and combined into an effec-
tive computational tool.
VIP (Virtual Pulp Bleaching) was a follow- Reaction kinetic models for all bleach-
up project of the ABLE (Advanced Bleach- ing stages of interest could not be devel-
ing Plant) project. The purpose of ABLE oped under ABLE, as the amount of work
was to gather fundamental theoretical required exceeded available resources.
knowledge on bleaching chemistry and The VIP project was therefore tasked with
related physicochemical phenomena (ki- completing the work initiated by the ABLE
netics of bleaching reactions, mass trans- project.
fer, and thermodynamics) and to develop
computer models based on that knowl-
edge. Bleaching chemistry was described
at the micro-scale level (molecular reac-
tions and mass transfer), and micro-scale The objectives of the project were to:
models were combined with macro-scale • Compile a library of oxygen and
models describing the flow of pulp sus- peroxide reactions
pensions and liquors in mixers, reactors • Complete the current chlorine
and washers. In ABLE, the project team dioxide reaction library to enable
managed to develop models for D0 and simulation of the alkaline extraction
EOP stage chemistries as well as for pulp and final brightening stages
washing. These models were validated • Develop a brightness model, i.e.
against data collected from an industrial specify the relevant chromophoric
process and from laboratory experiments. structures and their relative
Models for the O and A stages were de- contribution to pulp colour
veloped in part, but not validated. • Develop an intrinsic viscosity /
ABLE proved that fundamental infor- polymer chain degradation model
mation from a range of sources can be • Validate the developed models with
gathered and used to produce models that literature/laboratory/industrial data
describe bleaching chemistry at a highly • Train project partners to use the
detailed level. The developed tool could developed simulation model.
distinguish the effects of mass transfer,
thermodynamics and chemical reactions.
ABLE models gave valuable information
on different chemical phenomena that
could not be directly measured by ana- The goal was to develop mechanistic
lytical means. General bulk parameters models for reactions of oxygen chemi-
used in the industry, such as kappa num- cals with fibre wall structures, includ-
ber, viscosity, TOC, COD and AOX, were ing chromophores. The reaction routes
computed from molecular level informa- and, where available, kinetic parameters
tion during the simulations. The models were drawn mainly from literature. Ac-
can be considered as a virtual bleaching tual compounds were favoured, but lig-
laboratory that can be utilized in a variety nin and some of its degradation prod-
of ways. The development of ABLE mod- ucts needed to be modelled as pseudo-
els can be regarded as a considerable ac- compounds closely resembling the actu-
ademic achievement; fragments of theo- al structures detected directly from the
retical knowledge from numerous sourc- lignin polymer, or from lignin model com-
es of literature were collected, assessed, pound studies. In addition, the aim was

54

to build the reaction chemistry library pounds in aqueous solutions. Sheet im-
from elementary reactions, even though, pregnation studies were conducted to val-
in order to keep the reaction library suf- idate the link between liquid absorptivity
ficiently simple, some of the implement- and sheet brightness.
ed reactions consist of numerous reac-
tion steps. In order to enable the com-
putation of brightness, the Kubelka-Munk
parameters needed to be determined for
4. Results
each compound.
The reaction library for oxygen chem- 4.1 Oxygen chemical reaction
icals was intended to be general enough library
to enable it to be used for simulation of For the development of schemes for lig-
the O, E (with no enforcement or with ox- nin reactions with oxygen in alkaline
ygen and/or peroxide enforcement) and conditions, a vast set of laboratory ex-
P stages. Lignin oxidation experiments in periments and analyses were conduct-
alkaline conditions under oxygen pressure ed. Softwood and hardwood kraft lignins
were conducted to obtain validation data (from MeadWestvaco) were used as the
for lignin reaction mechanisms. Alkali ex- starting materials. Experiments were con-
traction laboratory experiments (with or ducted at varying temperatures (90 and
without oxygen and/or peroxide enforce- 110°C) and initial oxygen pressures (5
ments) were conducted for D0 pulp to val- and 8 bar) with a constant alkali charge
idate the selected chromophore formation and a reaction time of 240 minutes. Sam-
and degradation reaction scheme. Intrin- ples were taken as a function of time (5,
sic viscosity measurements conducted 10, 20, 30, 60, 120, 180 and 240 min)
for the alkali extraction stage pulps vali- to reveal the reaction kinetics. Sever-
dated also the carbohydrate degradation al compounds/structures were analyzed
scheme. Reactions involving only inorgan- from the samples. The formation of acid-
ic compounds (oxygen chemical and sul- ic products was followed by pH, conduc-
phur compounds) were taken from litera- tometric titration (total acids) and cap-
ture. The reactions of extractives were al- illary electrophoresis (CE giving small
so included. Literature data was used for molecular weight acids). The CE meth-
further validation of the overall oxygen od was partly developed in this project.
chemical library. COD (Cr and Mn), TIC and TOC were al-
The chromophore chemistry in the so determined in order to monitor overall
chlorine dioxide stages was also defined changes in the sample composition. The
based on laboratory D0 and D1 experi- dried samples were analyzed by 31P NMR,
ments. With a set of experiments, the which gave information on the structur-
role of chlorite was elucidated and the al changes of the lignin, particularly dif-
findings entered in the chlorine dioxide ferent types of hydroxyl groups. Kraft lig-
reaction library. The reactivity of chlorine nins were also analyzed for metals, sul-
dioxide with the hydroxylated quinone phur, elementary composition (C, H, N)
structures formed at the alkaline extrac- and methoxyl group content. The degree
tion stage was verified. of demethylation was monitored based
Kubelka-Munk parameters (k457) of on released methanol. In addition, lignin
potential chromophoric structural units degradation was monitored using molar
were obtained from the UV-VIS mea- mass and UV-VIS measurements. A de-
surements of corresponding model com- crease in phenolic units and an increase

55

in conjugated phenols were detected ac- bound to the polymeric lignin. Oxalic acid
cording to the ionization UV-VIS spectra. was the most abundant non-volatile ac-
Decreasing oxygen pressure was recorded id component; other identified acids were
during the entire reaction period. This en- glycolic, fumaric, succinic, malonic, malic,
abled the estimation of oxygen consump- and maleic acids.
tion in the reactions. The 31P NMR results for HW lignin
In general, the analysis results were showed a progressive decrease in syrin-
logical. When the temperature and ini- gyl and guaiacyl units, while the number
tial pressure in the delignification stage of COOH groups increased similarly to the
were increased, the lignin reactions be- SW case. Comparison with the starting
came faster and the effects on the lignin material showed that the total amount of
structure were more emphasized. During aromatic units fell below that of HW lig-
the first 60 min the reactions were rapid. nin after 20 minutes of oxidation. Dur-
This was evident from the degradation of ing oxygen delignification, the amount of
phenolic lignin, formation of organic ac- α-carbonyl structures was increased and,
ids, and increase in total charge and ox- simultaneously, the proportion of conju-
ygen consumption. After the first 60 min gated structures (Cα=Cβ) was decreased,
period the reactions slowed. when analyzed by pyrolysis-GC/MS.
Both volatile and non-volatile carboxy- Peculiar behaviour was observed in
lic acids were detected in the reaction the development of conjugated pheno-
mixtures. Of these, the former group in- lic lignin: during the first 20 to 30 min-
cludes formic and acetic acids and the utes more conjugated phenolic lignin
latter includes dicarboxylic acids and hy- was formed, after which its amount de-
droxy acids. The dominating acids were creased. In milder conditions, the amount
the formic, oxalic, acetic, and glycolic ac- of conjugated phenols was slightly high-
ids. The concentrations of these four ac- er at the end of the reaction period (240
ids corresponded to almost 90% of all ac- min) than at the beginning, but in harsh-
ids content. The general trends in SW de- er conditions a lower level was attained.
lignification experiments, detected by 31P Based on literature sources, a high-
NMR, were the increase in COOH and the ly detailed lignin degradation scheme ac-
decrease in guaiacyl OH units in respect counting for most of the experimental ob-
to oxidation time. Condensed phenolic hy- servations could be developed. The re-
droxyl units were found to be stable un- actions start when phenolates, i.e. dis-
der oxygen delignification conditions. No sociated phenolic lignin units, react with
clear trends were observed in the case molecular oxygen. The resulting phenoxy
of catechols or p-hydroxyphenylpropane radical reacts with superoxide anion (an
units. The overall carboxylic acid group electron reduction product of oxygen)
formation followed a similar progressive through paths which result in the release
trend as the small aliphatic carboxylic ac- of methanol and the formation of formic
ids in the reaction solution, as quantified acid, oxalic acid, malonic acid, carbon di-
by CE, in respect to reaction time. Anal- oxide, hydrogen ions, hydrogen peroxide
ysis of non-volatile acids, co-precipitat- and acids, which are still attached to the
ed with lignin, revealed that 30% (5 min lignin macromolecule. The production of
of delignification time) – 60% (10 min) – hydrogen ions decreases pH. Decreas-
95% (20 - 240 min) of COOH units con- ing pH in turn lowers the degree of dis-
sisted of these non-volatile small molec- sociation of phenols (phenolate concen-
ular acids and only a minor portion was tration) retarding the first reaction step.

56

Oxygen is consumed in the first reaction tion of carbohydrates lowers yield and in-
step (phenolate + oxygen), but also lat- trinsic viscosity.
er when the partly oxidized lignin struc- The effect of COD load (consisting of
tures are further degraded. The hydrogen lignin, extractives and inorganic sulphur
peroxide formed as a side product under- compounds) on carbohydrate degradation
goes, to a major part, catalytic decompo- can currently be well predicted, but more
sition into hydroxyl radicals and superox- work is required to validate the modelling
ide. The dissociated counterparts of hy- of the effect of alkali charge on carbohy-
droxyl radicals, oxyl anion radicals, are drate degradation.
responsible for forming conjugated phe- Work was carried out to determine
nols. These structures have a lower re- the antioxidant efficiency of phenols in
activity than non-conjugated phenols, the oxidation of sugar enediols by oxy-
and it seems that at the end of the oxi- gen. Phenols are converted to phenoxy
dation process the majority of non-con- radicals upon reaction with the initially
densed phenols are conjugated. Degra- formed sugar enedioxy radicals, thus pre-
dation of the conjugated structures leads venting the oxidation of sugars. The phe-
to formation of glycolic acid and acetic ac- noxy radicals convert part of the initially
id. The condensed phenol concentration formed superoxide back to oxygen while
did not change significantly during the ex- they are reduced to phenols. Another part
periments. In the model, the degradation of the phenoxy radicals is oxidized per-
rate for condensed phenol is lower than manently by superoxide and/or oxygen.
that of non-condensed phenol, and dur- Measuring the antioxidant efficiency pro-
ing the course of the experiments its for- vides information on the relative reaction
mation (via phenoxy radical coupling) ex- rates of the alternative routes involved.
ceeds the effect of degradation. The antioxidant efficiency was evaluated
In addition to lignin degradation re- by measuring the oxygen consumption for
actions, reactions were defined for car- the oxidation of model compounds (glu-
bohydrates, extractives, inorganic sul- cose and dihydroxyacetone). Measure-
phur compounds and inorganic oxygen ments were conducted with varied sugar
species. The reaction stoichiometries and and phenol concentrations at two temper-
kinetic parameters of the inorganic reac- atures (25°C and 35°C). Reaction rates
tions were adopted from literature. The were calculated based on the oxygen con-
rate parameters for transition metal cat- sumption and ratios between approximat-
alyzed hydrogen peroxide decomposition ed reaction rate constants. The oxidation
were obtained experimentally. The kinet- rate for glucose remained close to con-
ics of extractives degradation was based stant until the oxygen was consumed,
on the observation that roughly half of whereas the oxidation of dihydroxyace-
the extractives react during oxygen del- tone slowed. It was discovered that ox-
ignification. Carbohydrate degradation idation of dihydroxyacetone was propor-
schemes (also discussed in 4.3) were al- tional to the square of sugar concentra-
so based on literature. Parameter tun- tion. The proposed reaction scheme was
ing was carried out based on literature in accordance with the experimental re-
data and the alkaline extraction results sults.
obtained in this project. Reactions of in-
organic sulphur compounds, extractives
and carbohydrates consume alkali, thus
retarding the lignin reactions. Degrada-

57

4.2 Brightness model ible effect on lignin colour. A higher de-
development gree of conjugation is probably possible
The main tasks in developing the pulp in lignin due to its macromolecular struc-
brightness model were to: ture. With polyphenol model compounds
1. Identify the most important (catechol, hydroquinone, pyrogallol), the
chromophoric structures in pulp and effect of ionization could not be distin-
their contribution to pulp colour guished from the other alkali induced re-
2. Define a reaction scheme for the actions. In alkaline conditions, several
proposed chromophoric structures reactions (ionization, oxidation, hydrox-
in the O, D, EXX stages, and their ylation, polymerization) take place with
effect on brightness development these compounds, leading to formation of
• Distinguish between the more coloured structures. In acidic con-
brightness increase achieved ditions only p-quinones were found to re-
through actual chromophore act further to form more coloured struc-
reactions and through tures, although the conversion was mi-
delignification nor compared to that occurring in alka-
• Evaluate the role of line conditions.
carbohydrate chromophores on Impregnation studies were performed
pulp brightness to convert the molar absorptivities (ε) of
3. Characterize the main fibre wall quinones into structure-specific light ab-
chromophores and, if necessary, sorption coefficients (k457), which is the
develop analytical tools for parameter used in the brightness mod-
quantitative detection of specific el. The impregnation studies also showed
chromophoric structural units that the brightness drop caused by 10
mmol/kg of o-quinone was over 30 per-
Throughout the project, a substan- centage units when a base paper with a
tial amount of experimental work was scattering coefficient of 40 m2/kg was
conducted to identify the most impor- used. A similar amount of p-quinone re-
tant chromophoric structures. An exten- sulted in a brightness loss of only 2 per-
sive literature study was also conduct- centage units. Thereby, in softwood pulp
ed. Aqueous solutions of various quino- with a typically lower scattering coeffi-
noid structures (o-quinones, hydroxylated cient (~30 m2/kg), reaching the max-
quinones, stilbene quinones) were found imum brightness close to 89–90% re-
to produce very high molar absorptivities quires an o-quinone content of 0.1 mmol/
at λ = 457 nm (UV-VIS measurements). kg or less (assuming there are no other
Catechols and hydroquinones are colour- chromophoric structures present, which
less at neutral pH, but emit intense colour is not the case in actual pulp). To reach
under alkaline conditions (in the presence brightness levels of over 80%, the o-qui-
of atmospheric oxygen). The same ap- none content must be lower than 1 mmol/
plies to p-quinones which in neutral con- kg, whereas p-quinone contents as high
ditions have only a pale yellow colour. as 20 mmol/kg are tolerated in fully
Model compound studies of simple bleached pulps.
phenolic model compounds showed no The model compound results were
effect of ionization on lignin colour, al- used as the basis for defining the chro-
though UV-VIS measurements with kraft mophoric structures for the model.
lignin suggested that ionization of some O-quinone and hydroxyquinone structures
(phenolic) lignin structures has a revers- were defined as the main chromophores.

58

Hydro-quinones, catechols, p-quinones, curred rapidly and the majority of new
and benzenetriols (polyphenols) are the chromophoric structures were formed
main leuco-chromophores, i.e. colourless during first 5 minutes. The formation of
structures, which can react to form co- coloured chromophores was enhanced
lourful products. Information from lite- by temperature and alkali charge, al-
rature was used to define the reaction though no additional chromophore for-
paths that generate and destroy these mation was observed with excess alkali
structures. charges. Surprisingly, less new chromo-
To evaluate the possible role of car- phores were formed in the presence of
bohydrate chromophores on pulp bright- oxygen, and the alkaline darkening re-
ness, lignin-free cotton linter was treat- tarding effect of oxygen became clear-
ed in typical kraft cooking conditions. This er with increasing retention times. This
resulted in a brightness decrease of 3 to could be related to the in situ formation
4 percentage units, confirming that co- of peroxide in the presence of oxygen.
loured structures were formed also in As expected, the lignin became bright-
polysaccharides. However, compared to er with increasing peroxide charge and
lignin, the effect was minor. According to retention time.
the bleaching experiments, the carbohy- In the following D1 stage, pulp bright-
drate chromophores could not be com- ness increases due to lignin removal but
pletely removed by chlorine dioxide, but also as a result of the lignin chromophore
were effectively destroyed by peroxide. It reactions. With model compound experi-
was considered unlikely that the carbo- ments is was confirmed that the coloured
hydrate chromophores generated during hydroxylated quinonoid structures formed
kraft cooking could survive bleaching, and in the alkaline conditions are reactive with
hence only lignin derived chromophores chlorine dioxide, and thus contribute to
were included in the model. brightening in the D1 stage. The forma-
A series of pulp bleaching experi- tion of new reactive phenolic units in qui-
ments was conducted to produce valida- nones through hydroxylation in alkaline
tion material for the chromophore reac- conditions has also been suggested pre-
tion scheme (and at a more general level viously in literature for enhancing reactiv-
for the brightness model). The aim was to ity in the following D stage, but this has
distinguish between brightening through not been confirmed until now. The high-
delignification and brightening through est bleaching response was achieved in
actual chromophore reactions. The main experiments with final pH of 4, which was
emphasis was on determining the effect optimal both in respect to the delignifica-
of alkali, peroxide and oxygen at the E, tion and chromophore reactions.
EP, EO and EOP stages. The role of pH, re- Throughout the project, analytical
tention time, chemical charge and tem- methods were developed to quantitative-
perature were also considered. For the ly analyze and follow the reactions of spe-
bleaching experiments, mill pulps from cific chromophoric structures in different
several stages (O, D0, EOP and D1) of a bleaching conditions. This was the great-
4-stage bleaching line were taken. est challenge in the brightness model de-
The results of the E stage experi- velopment. Due to the very low amounts
ments confirmed that lignin darkening of chromophoric structures, most meth-
takes place during alkaline extraction, ods tested are not sufficiently sensitive
even though pulp brightness increases (pyrolysis, 31P NMR), and those having
due to lignin removal. The darkening oc- high sensitivity (UV-VIS) are not specific

59

enough for detailed structures. lic structures were detected in different
A new method for quantitative deter- proportions for both model compounds.
mination of quinones in pulp was devel- Besides quinones, all of the above are
oped. Phenazine derivatization was per- also found in pulps. It is, however, very
formed to increase the sensitivity of the difficult to distinguish their actual ori-
method by increasing absorptivity and gin. A 31P NMR spectroscopic method
shifting the absorption maxima to high- for the detection of quinonoid structures
er wavelengths. The UV-VIS reflectance was also implemented, but no quinones
spectra were recorded from the phen- could be detected from isolated lignins
azine-derived pulp handsheets and Kubel- with this method either.
ka-Munk equation was applied to the con-
version of the spectrum into an absor- 4.2.1 Brightness model principles
bance (k/s) spectrum, which is linearly and validation
proportional to concentration. The qui- The molecular level chromophore
none determination method was applied chemistry is linked to pulp brightness in
to a series of unbleached, semi- and ful- the following way:
ly bleached softwood kraft pulp samples. • Lignin structures are divided into
The results were logical with respect to three categories according to their
existing knowledge regarding the reac- light absorption properties:
tions of quinones in bleaching. 1. Chromophores, i.e.
On the basis of the known effect of structures with high molar
quinone structures on pulp brightness, absorption coefficient (k457,i),
the UV-VIS reflectance measurements absorption coefficient values
showed that, besides o-quinones, oth- defined according to model
er chromophores also contribute to the compound experiments.
brightness of E stage pulps. This may Structures in this category:
be due to yet unidentified chromophoric hydroxyquinone, o-quinone
structures formed in the alkaline stages. 2. General lignin structures
Pyrolysis was also tested as a meth- with relatively low molar
od for detecting chromophoric struc- light absorption coefficient
tures directly from the pulp. Unfortu- value; the absorption coefficient
nately, no quinonoid structures could value is optimized during
be detected from pulps or from isolated the model validation process.
residual lignin. Only hydroquinones and Structures in this category:
catechols were detected. Even though phenolic lignin, non-phenolic
being non-coloured as such, they have lignin, leuco-chromophoric
been shown to react further in alkaline 3. Highly fragmented lignin
conditions, forming new unidentified derivatives with no contribution
chromophoric structures, and thus are to pulp colour
important structures to monitor. In or- • The colour contribution of each
der to be able to identify alkali-induced lignin species is proportional to its
chromophoric structures, hydroqui- molar light absorption coefficient
none and p-quinone model compounds (k457,i) and its concentration in the
were treated with alkali and the reac- fibre wall (ci). The pulp absorption
tion products were analyzed by pyroly- coefficient (k457) is obtained by
sis. After alkaline treatment, hydroqui- summing up the colour contribution
nones, p-quinones, and various pheno- of each species k457=Σ (k457,i· ci).

60

Pulp brightness is computed from kappa number analysis, but contribute to
the pulp absorption coefficient TOC and COD when released in the liquor.
(k457) and light scattering The reinforcing effect of oxygen in EO
coefficient (s457) using the Kubelka- bleaching was underestimated. The pre-
Munk equation. dicted improvements in brightness gain
and kappa reduction, as compared to a
Pulp brightness develops as a result plain E stage, fell severely short. It was
of delignification as well as through chro- hypothesized that oxygen would degrade
mophore generation and destruction. a significant proportion of the phenols/
Both processes take place according to phenolates created in lignin under alka-
the molecular level chemistry models im- line conditions and thereby cause the im-
plemented in the simulator. proved decrease in kappa number. The
The brightness model, and the chro- reactions of molecular oxygen would lead
mophore reaction schemes it is based on, to formation of hydrogen peroxide as a
was validated with the experimental re- product, which would promote chromo-
sults obtained in bleaching experiments. phore destruction. These reactions were
The aqueous lignin oxidation results ob- implemented in the model, but the pa-
tained (4.1) were also exploited in the rameters could not be adjusted to a level
validation procedure. Although the main that would have achieved the experimen-
target was to optimize the chromophore tally observed kappa reduction or bright-
reaction parameters, it was just as es- ness gain. An apparent conclusion is that
sential to validate and optimize the mod- the alkaline treatment did not produce
el parameters with respect to predicting enough substrates for oxygen. The devel-
the other main attributes (kappa num- opment of liquid absorbance in the aque-
ber, AOX, OX, residual chemicals, visco- ous lignin oxidation simulations was, how-
sity, etc.). ever, rather well line with the results ob-
The model was found to be capable tained in the lignin oxidation experiments.
of effectively reproducing the experimen- Resolving the EO stage incoherence re-
tal brightness development in the E, EP, quires better understanding of the struc-
and EOP stages. The extent of delignifi- tural changes taking place in lignin dur-
cation (kappa number reduction), perox- ing alkaline extraction.
ide consumption, residual alkali, and AOX The brightness gain achieved in the
release were also rather well predicted. D0 and D1 stages was predicted ade-
The release of organic material (moni- quately. The experimentally observed ef-
tored as COD and TOC of the liquor) was fect of (final) pH on D1 brightness and
consistently underestimated. This may kappa reduction could also be repro-
result from the fact that the model as- duced. The brightness increase obtained
sumes the delignification process to dis- with chlorine dioxide is a complex result
solve only lignin. Experimental work, in of chromophore chemistry as well as del-
contrast, suggests that the dissolved high ignification.
molecular weight material is not pure lig- The individual bleaching stage valida-
nin but contains a fair degree of carbohy- tions proved that the simulator predicts
drates. The use of kappa number as the the pulp brightness behaviour within a
measure for fibre lignin content may also single stage reasonably well. The perfor-
contribute to the inaccuracy of predicted mance in predicting brightness develop-
TOC and COD. Highly oxidized (fully sat- ment in a multi-stage sequence was eval-
urated) lignin structures are ‘invisible’ in uated by simulating the following three

61

bleaching series: O-D0-E (SW), D0-EOP- middle of chains into carbonyl groups.
D1 (HW), and D1-N-D2 (HW). The O-D0- Under alkaline conditions the glycosid-
E simulations could be evaluated with a ic bond next to the carbonyl containing
concise set of experimental results (D.Sc. unit cleaves. As a result, two new chain
thesis of Janne Laine, TKK, 1996). Over- ends are formed: a reducing end and a
all, the results were credible. A major dif- non-reducing carbonyl group containing
ficulty occurred in defining the initial com- end. Under alkaline conditions the re-
position of the fibre wall constituents. The ducing end enolizes, which leads to a se-
simulation outcome is, obviously, quite quence of reactions involving alkali, oxy-
sensitive to the chemical composition of gen and hydroperoxide anion consump-
the fibre wall. Exploiting non-structure- tion. The reducing end units degrade in-
specific variables such as pulp kappa to various soluble acids (formic, glycolic,
number, brightness, or liquor COD in de- 3,4-dihydroxybutyric, isosaccharinic, xy-
fining molecular scale composition is pre- loisosaccharinic, 2-deoxyglyceric acid and
carious. Future efforts should therefore carbonate) until the reducing end unit is
be focused on developing reliable analyt- oxidized into a carboxylic acid form. Ex-
ical methods for characterization of the periments conducted with chlorous acid
fibre wall. showed that chlorous acid can also oxi-
The chromophore reaction scheme is dize the reducing ends in carbohydrates
presently fairly simple, which may be con- into carboxylic acids.
sidered both an advantage and a weak- The reaction parameters for this re-
ness. More elaborate schemes could pro- action were determined and incorporated
vide better coherence between the pre- into the chlorine dioxide chemistry library.
dictions and experimental results, but de- The average degree of polymerization is
fining new structures and reactions with computed from the concentration data of
no means of validation goes against the the various end and middle group units
modelling philosophy used in this project. in the carbohydrate chains. This value is
converted into intrinsic viscosity with the
model obtained from literature.
4.3 Intrinsic viscosity The viscosity model was tested along
model development with validation of the carbohydrate degra-
Intrinsic viscosity is an indirect indicator dation scheme using literature data from
of average cellulose chain length. A mod- oxygen delignification experiments as well
el correlating the intrinsic viscosity mea- as with the alkaline extractions results
surement and degree of polymerization of obtained in this project. As discussed in
cellulose chains was adapted from litera- 4.1, the validation work regarding carbo-
ture. The model also takes into account hydrate chemistry could not be complet-
the fact that hemicelluloses, which gen- ed during this project.
erally have a much shorter polymer chain
than cellulose, decrease the average de-
gree of polymerization. 4.4 Completing
Cellulose and xylan chains were mod- the chlorine dioxide
elled as consisting of various units with chemistry library
different reactivities. Hypochlorous acid The previous chlorine dioxide model un-
as well as hydroxyl and oxyl anion radi- derestimated chlorous acid (Cl(III)) con-
cals are capable of oxidizing the hydrox- sumption. It was found that aldehydes are
yl groups in glucose/xylose units in the oxidized by chlorous acid. The reaction

62

rates of several small molecular weight • Water cycles can be closed further
aldehydes with Cl(III) were determined • Less chlorine dioxide is consumed
and they were found to be high enough • Less AOX is formed
to compete with other reactions known to • Chlorate content of treated effluent
consume Cl(III) during bleaching. It was is reduced.
also discovered that during chlorine diox-
ide bleaching new aldehyde groups are Conducting simulations prior to the
formed in carbohydrates and in lignin. experiments helps to focus laboratory
These reactions were implemented in the work. Further simulations reveal areas
reaction library to increase the accuracy that are insufficiently known and require
of the model. Efforts were also allocated more research.
to refining the theory of chlorate forma- The simulation model has been uti-
tion. The hypothesized reaction was found lized in seven Master’s thesis studies to
not to occur during bleaching. date.
The model will also be utilized in the
industrial consortium project Minimum
Impact Hardwood Pulp Bleaching (2010–
5. Future plans and 2013).
key development needs
The models will be applied and developed
further under the EffFibre programme
(2010-2013) of Forestcluster Ltd. Besides
the bleaching simulation, new models will
be created to simulate the cooking/biore-
fining of wood chips. There are also plans
to develop a graphical user interface for
the simulation tool.

impact of results
The end product of the project is a simu-
lation tool that can be used in fast and
cost effective development of next-gen-
eration bleaching processes that are
characterized by low capital investments
(compact sequences), low operation costs
(reduced use of chemicals, water and en-
ergy) and low environmental load (BOD,
AOX, chlorate). Examples of successful
utilization of the first version of the tool
already exist. A new three-stage bleach-
ing sequence was developed with the fol-
lowing additional advantages:

63

7. Publications and Lehtimaa, T., Tarvo, V., Kuitunen, S.,
Jääskeläinen, A.-S., Vuorinen, T., The
reports effect of process variables in chlorine di-
Björk, C., Antioxidant effects of phenols oxide prebleaching of birch kraft pulp.
in the oxidation of reducing sugars by ox- Part 2. AOX and OX formation, J. Wood
ygen, Master’s thesis 2010, Aalto Univer- Chem. Technol. (2010), 30(1), 19–30.
sity.
Lehtimaa, T., Kuitunen, S., Tarvo, V.,
Kalliola, A., Kuitunen, S., Liitiä, T., Vuo-rinen, T., Kinetics of aldehyde ox-
Rovio, S., Ohra-aho, T., Tamminen, idation by chlorous acid, Industrial and
T., Vuorinen, T., Lignin oxidation mech- Engineering Chemistry Research (2010),
anisms under oxygen delignification con- 49(6), 2688–2693.
ditions - Results from direct analyses,
EWLP 2010, 16.-19.8.2010 Hamburg, Lehtimaa, T., Kuitunen, S., Tarvo, V.,
Germany. Vuo-rinen, T., Reactions of aldehydes
with Cl(III) in Chlorine Dioxide Bleaching,
Kuitunen, S., Kalliola, A., Tarvo, V., Holzforschung (2010), 64(5), 555–561.
Tamminen, T., Rovio, S., Liitiä, T.,
Ohra-aho, T., Lehtimaa, T., Vuorinen, Lehtimaa, T., Reactions of chlorine(III)
T., Alopaeus, V., Lignin oxidation mech- and their kinetics in the chlorine dioxide
anisms under oxygen delignification con- bleaching of kraft pulps, Doctoral disser-
ditions - Reaction pathways and model- tation 2010, Aalto University.
ing, EWLP 2010, 16.–19.8.2010 Ham-
burg, Germany. Pääkkönen, T., Jääskeläinen, A.-S.,
Tamminen, T., Liitiä, T., Determination
Lehtimaa, T., Tarvo, V., Kuitunen, S., of quinones in pulp by UV/VIS reflectance
Jääskeläinen, A.-S., Vuorinen, T., The spectroscopy, EWLP 2010, 16.–19.8.2010
effect of process variables in chlorine di- Hamburg, Germany.
oxide prebleaching of birch kraft pulp.
Part 1. Inorganic chlorine compounds,
kappa number, lignin and hexenuron-
ic acid content, J. Wood Chem. Technol.
(2010), 30(1), 1–18.

64

Pääkkönen, T., Quantification of qui- Tarvo, V., Lehtimaa, T., Kuitunen, S.,
nones in wood pulps, Master’s thesis Alopaeus, V., Vuorinen, T., Aittamaa,
2010, Aalto University. J., A model for chlorine dioxide deligni-
fication of chemical pulp, Accepted for
Rovio, S., Kalliola, A., Sirén, H., Tam- publication in J. Wood Chem. Technol.
minen, T., Determination of the carboxylic
acids in acidic and basic process samples Tarvo, V., Modeling chlorine dioxide
by capillary zone electrophoresis, Journal bleaching of chemical pulp, Doctoral dis-
of Chromatography A (2010), 1217(8), sertation 2010, Aalto University.
1407–1413.
Warsta, E., Vuorinen, T., Pitkanen, M.,
Rovio, S., Kuitunen, S., Ohra-aho, T., Addition of bisulphite to lignin α-carbonyl
Ala-kurtti, S., Kalliola, A., Liitiä, T., groups: a study on model compounds and
Tamminen, T., Lignin oxidation mech- lignin-rich pulp, Holzforschung (2009),
anisms under oxygen delignification con- 63(2), 232–239.
ditions – Detailed characterization of the
lignin, EWLP 2010, 16.-19.8.2010 Ham-
burg, Germany.

Rovio, S., Kalliola, A., Tamminen, T.,
Advanced methods to interpret lignin 31P
NMR spectra, COST Action FP0901, 19.–
21.2010, Hamburg, Germany.

Tarvo, V., Lehtimaa, T., Kuitunen, S.,
Alopaeus, V., Vuorinen, T., Aittamaa,
J., The Kinetics and Stoichiometry of the
Reaction between Hypochlorous Acid and
Chlorous Acid in Mildly Acidic Solutions,
Industrial and Engineering Chemistry Re-
search (2009), 48(13), 6280–6286.

65

Short pulping

Project Manager Marjo Määttänen, marjo.maattanen@vtt.fi




VTT Technical Research Centre Enhanced cooking efficiency, shortening the bleaching
of Finland process, development of fibre kappa analysis method,
techno-economical and sustainability evaluation of new
fibre line.

University of Helsinki (UH) Novel measurement methods development and instru-
Department of Physics mentation, ultrasound processing and characterization
Electronics Research Laboratory of pulp and fibres.

66

Abstract
The main objective of the Short pulping project was to investigate whether partial removal
of hemicelluloses by prehydrolysis improves impregnation and decreases the formation of co-
loured groups in pulp, thus enabling improved pulping efficiency. In order to predict and moni-
tor the effect of process changes on pulp quality, characterization methods for pulp uniformity
and strength properties were developed. The study found that the use of prehydrolysis for the
efficiency enhancement of kraft pulping is not advantageous unless the considerable value po-
tential of utilising the prehydrolysate components (hemicelluloses) is realised. The most valu-
able result of the prehydrolysis study was the understanding that connecting biorefinery stages
to kraft processes requires extensive exploitation of the whole process chain. The kappa num-
ber variation of the samples can be reliably measured and the pulps can be compared using the
developed sheet measurement based fibre kappa method. The speed of ultrasonic shear waves
in a pulp sheet offers potential as an in-line process analysis measurement for elastic modulus/
tensile index of chemical pulp in pulp and paper mills.
Keywords: prehydrolysis, impregnation, uniformity, ultrasound

67

1. Project background It is affected by the elastic properties
and bonding ability of the furnish com-
During chemical pulping, fibres are ex- ponents and the web draws of the paper
posed to numerous chemical and physical machine. The elastic properties of chemi-
treatments under severe conditions. The cal pulp are affected by changes in the fi-
large number of unit processes involved bre wall ultrastructure (e.g. level of hor-
generates high equipment and ope- nification), degree of fibre deformation
rational costs. The forest industry needs (e.g. curl and kinks) and fibre chemistry
to improve its profitability and reduce its (e.g. hemicellulose content). Any sudden
capital intensiveness. Although the in- process change at the pulp mill (chemical
dustry’s unit processes have been con- dosage, pH, change in raw material etc.)
tinuously modernised more radical inno- can cause unwanted variation in the elas-
vations and improvements are needed. tic properties of the pulp. There are cur-
Significant production process simplifica- rently no measurement methods capable
tion offers great potential to improve both of rapidly determining the elastic proper-
the ecological and economical competi- ties of pulp in order to control the chem-
tiveness of the industry. ical pulping process. Modern ultrasound
After kraft cooking, pulp is inhomo- analysis has shown potential in measur-
geneous and dark and requires several ing pulp and single fibre strength prop-
bleaching stages. This is a crucial rea- erties both quickly and accurately. Fibre-
son for the long length of the fibre line. level analysis will enhance understanding
Improved brown stock homogeneity and of the mechanisms behind sheet strength
bleachability are therefore key to achiev- formation (paper and pulp). Such a sheet-
ing more cost effective pulping. The main level measurement method would provide
aim of pulp bleaching is to remove the pulp mills with a valuable tool for fast-
pulp colour, i.e. the chromophoric struc- er pulp quality control and development.
tures formed mainly during alkaline cook-
ing. Process modifications aimed at mini-
mizing colour formation during cooking
are therefore also beneficial in respect to
final bleaching. The overall objective was to develop
In order to predict and monitor the ef- pulping technology for a compact, flex-
fects of process changes on pulp quality, ible and economically efficient fibre line
characterization methods for pulp unifor- by improving the efficiency of kraft cook-
mity and strength properties will be need- ing and bleaching. Intensified kraft cook-
ed. The fibre kappa number method will ing was carried out by removing chemi-
increase knowledge of the impact of pro- cal (hemicelluloses) and/or physical (pit
cess changes on kappa number variation. membranes) obstacles from the chips be-
Gustafson et al. have developed the Fi- fore cooking by means of prehydrolysis,
bre Kappa Analysis (FKA) method, which different impregnation aids and ultrasonic
is based on acridine orange staining and treatment. These pretreatment methods
fluorescence detection of single fibres us- were believed to improve impregnation
ing a special device. The goal was to de- and decrease energy and chemical con-
velop a method of measuring kappa vari- sumption during cooking. Improved pulp
ation from pulp handsheets using fluores- homogeneity and decreased formation
cence microscopy. of coloured substances, enabling shorter
The elastic modulus of the wet and bleaching sequences (2-3 stages) as a re-
dry paper web is a major factor affect- sult, were also to be expected. The proj-
ing the runnability of a paper machine. ect also aimed at high kappa level cook-

68

ing in order to achieve a more economical ing based prehydrolysis with a white li-
process with higher pulp yield and low- quor neutralization stage gave the high-
er energy consumption during pulp re- est chemical savings.
fining when prehydrolysis was used pri- An evaluation was made of the pos-
or cooking. sibilities for minimizing the drawbacks of
In order to better understand the ef- the prehydrolysis stage on pulping. Pos-
fect of process changes on pulp quality, sibilities investigated included controlling
pulp characterization methods were de- yield loss and energy consumption during
veloped. These included a fibre kappa pulp refining by increasing the cooking
analysis method using pulp handsheets to kappa number and partly replacing oxy-
measure pulp uniformity, as well as an ul- gen with ozone and hydrogen peroxide in
trasonic pulp quality testing method used the post cooking delignification stage. The
to evaluate the strength of single fibres outcome was that a higher kappa num-
and fibre bundles. ber and the use of ozone best counteract-
ed the disadvantages of the prehydroly-
sis stage.
The enhanced impregnation study fo-
3. Research approach cused on pre-evaluating how the use of
The basic idea in the pulping efficiency microwave and ultrasound treatments
improvement study was to use a relative- improve the impregnation of wood chips
ly mild prehydrolysis treatment in order compared to the traditional pre-steaming
to retain a higher hemicellulose content method. Treatments were carried out with
in the pulp than in traditional prehydroly- conventional equipment (microwave ov-
sis cooks for the production of dissolving en and ultrasound bath) not specially tai-
pulp. The prehydrolysis research can be lored for the experiments. The research
divided into three parts: consisted of impregnation and cooking tri-
Evaluation of alternative hydrolysis als and the evaluation of the reject con-
treatments and the strength of hydroly- tent and fibre kappa distribution of the
sis. The alternatives were water hydroly- pulps, which are key indicators of pulp
sis, acid hydrolysis and alkaline extrac- homogeneity. The outcome of the study
tion, and the strengths were 4, 8 and was that microwave treatment is an inter-
12% yield loss after the hydrolysis stage. esting alternative to pre-steaming, but is
The evaluation was carried out by cooking not economically feasible due to its high
and DEDED bleaching experiments. The energy consumption.
outcome was that 12% yield loss was se- The development of a fibre kappa dis-
lected for the strength of the prehydroly- tribution method consisted of experimen-
sis stage, as this had the clearest effect tal work aimed at developing a repeat-
on bleachability. able and accurate method for the analy-
In the selection of cooking modifica- sis of pulp homogeneity. Research was fo-
tion, alternatives for prehydrolysis (steam cused on repeatable staining, sheet form-
hydrolysis, water hydrolysis, acid hydro- ing with minimum overlapping, and im-
lysis or alkaline extraction) and neutral- age/data analyses. The outcome of the
ization stages (no neutralization or neu- study was a repeatable method for mea-
tralization with black liquor, white liquor suring the relative kappa number varia-
or green liquor) and possibilities to main- tion.
tain pulp yield with additives were eval- The development of a method for ul-
uated by displacement cooking, ODED trasound based measurement of strength
bleaching and testing of papermaking properties consisted of experiments to
properties. The outcome was that steam- show the potential of ultrasonic pulp

69

Figure 1. Specific alkali consumption of so focussed on evaluating possibilities for
conventional and prehydrolysis pulps in minimizing the observed drawbacks of the
oxygen delignification. prehydrolysis stage on pulping. The find-
ings were recognized as being valuable
for future biorefinery processes.

4.4.1 Effect on cooking
Many of the anticipated benefits of pre-
hydrolysis were not realized. Firstly, on-
ly the pre-steaming based prehydrolysis
stage offered the possibility to improve
the impregnation of cooking chemicals
through improved penetration. Liquid pre-

hydrolysis methods (acid and water) filled
the fibre cavities with water, and cook-
ing chemicals could therefore impregnate
the fibre only by diffusion. The reject con-
sheet measurement as a fast and accu- tent of the prehydrolysis pulps was high-
rate method of determining the elastic/ er across the entire kappa number range
tensile properties of chemical pulp. The compared to the reference pulps, indicat-
aim was also to show the potential of ul- ing poorer impregnation and lower uni-
trasonic measurement of fibre bundles for formity. It should be noted that the de-
detecting changes in the elastic properties gree of impregnation for the reference
of fibres. The effect of inter-fibre bonding cook was assumed to be as high as pos-
on the results can be reduced by mea- sible based on present knowledge, al-
suring fibre bundles. The outcome of the though such a level is rarely achievable
study was that ultrasonic techniques show in mill conditions. Secondly, the pH af-
potential for both applications. ter the prehydrolysis stages was acidic,
typically 3.5, leading to partial consump-
tion of the alkali charge for neutraliza-
tion. The prehydrolysis stage shortened
4. Results the cooking time at cooking temperature
(165 °C), but the total processing time in-
4.1 Hemicellulose removal by cluding prehydrolysis time at prehydroly-
prehydrolysis sis temperature (160°C) was typically
The efficiency enhancement of kraft pulp- longer. Only when cooking to below kap-
ing was investigated by implementing a pa 25 was the prehydrolysis stage advan-
mild prehydrolysis stage prior to cook- tageous. The yield of prehydrolysis pulps
ing. The basic idea was that by remov- was lower over the entire kappa num-
ing hemicelluloses (chemical obstacles) ber range. Increasing the cooking kappa
from the chips before the impregnation and the use of carbohydrate stabilization
stage, consumption of cooking chemicals (polysulphide cooking, borohydride treat-
and cooking time could be reduced and ment) improved the cooking yield by 1 to
chip impregnation would be easier and 2 percentage points.
more homogenous due to a more perme-
able structure. Improved pulp homogene- 4.1.2 Bleachability
ity and decreased formation of coloured The most promising results were achieved
substances, thus enabling shorter bleach- with oxygen delignification and bleaching.
ing, was also expected. Research was al- Prehydrolysis pulps (S88 Kappa 30, S88

70

Figure 2. Yield and chlorine dioxide to kappa 20 (S88 Kappa 19 O), similar fi-
saving potential with prehydrolysis nal brightness was reached with 15 kg/t
pulps. lower chlorine dioxide consumption com-
pared to the prehydrolysis pulp cooked
to kappa 30 (S88 Kappa 30). This was
obtained without any additional yield re-
duction (Figure 2). Compared to the ref-
erence pulp cooked to kappa 30 (REF
Kappa 30), chlorine dioxide consumption
was 24 kg/t lower but the yield of the
bleached pulp was 5 percentage points
lower than that of the reference. Howev-

er, in the case of the prehydrolysis pulp
there is the possibility of attaining a high-
er value potential through the utilization
of the hemicelluloses component of the
prehydrolysate.
Kappa 60, S88PS Kappa 30) showed bet-
ter reactivity towards oxygen. They had 4.1.3 Beatability and papermaking
a lower specific alkali consumption than properties
the reference pulps in oxygen delignifica- Reduced pulp beatability was one of the
tion (Figure 1). The final brightness was main effects of prehydrolysis on kraft
reached with 5 to 10% lower chlorine di- pulping. The phenomenon is readily ex-
oxide consumption in the DED sequence plained by the low hemicellulose content
when cooked to kappa 30. A lower hexe- of pulps produced by the prehydrolysis
nuronic acid content of the prehydrolysis kraft process. The type of prehydrolysis
pulps explains about 2 kg of ClO2 as aCl/t (auto or acid hydrolysis) had little effect
of this reduction. on beatability, but the extent of the pre-
The effect of the cooking kappa num- hydrolysis stage (yield) was crucial. Var-
ber of the prehydrolysis pulp on yield and ious means of carbohydrate stabilization
chemical consumption in bleaching was (polysulphide cooking, borohydride treat-
studied. The results showed that by cook- ment) improved pulp beatability only rel-
ing the prehydrolysis pulp to kappa 60 ative to their ability to increase the yield
(S88 Kappa 60), a 2 percentage point of bleached pulp. The beating revolutions
higher yield was obtained than by cook- needed to reach a constant tensile index
ing the prehydrolysis pulp to kappa 30 in PFI beating were thus closely related
(S88 Kappa 30). The saving potential in to the yield of bleached pulp (Figure 3).
chlorine dioxide consumption was similar
for both pulps (Figure 2). By using poly- 4.2 Enhanced impregnation
sulphide in the prehydrolysis cook (S88PS Impregnation and cooking experiments
Kappa 30), the yield gain was the same were carried out using different impreg-
as in cooking the prehydrolysis pulp to nation methods. The impregnation aids
kappa 60 (S88 Kappa 60) (Figure 2). The used were ultrasonic (US), microwave
final brightness was reached with 10 kg/t (1.5 or 4 min MW), surfactant (Surf),
lower chlorine dioxide consumption and a over pressure (5 bar) and pre-steam-
3 percentage point lower yield compared ing (S). The most effective methods
to the reference pulp cooked to kappa 30 were pre-steaming and microwave treat-
(REF Kappa 30). ments. The use of ultrasound treatment
When cooking the prehydrolysis pulp gave no benefits over the traditional pre-

71

Figure 3. Beating demand of bleached pulps vs. yield.
Reference and prehydrolysis kraft pulps cooked to kappa
30 and ECF bleached to brightness level 88% ISO.

steaming method. With the same H-facing, part of the air inside the chips was
tor, 4 minutes of microwave pretreatment removed along with the water vapour.
gave a 10–15 lower kappa number than The longer treatment time, the lower re-
other treatments (Figure 4). The H-fac- sidual air content. A 5 bar overpressure
tor required for a constant kappa num- compressed the residual air to one sixth,
ber was about 200 to 400 units lower with which improved impregnation.
screened and knotty chips, respectively. The methods used to assess pulp ho-
The lower H-factor is probably due to the mogeneity (fibre kappa distribution) and
chemical reactions occurring in wood dur- strength properties (elasticity based on
ing lengthy microwave treatment due to ultrasound velocity in paper sheet and
elevated temperature. Based on the re- handsheet properties) detected no dif-
ject contents, microwave treatment is ference in pulp quality. Microwave treat-
competitive with pre-steaming. The draw- ed pulps were as good as the reference
back of microwave treatment is its high pulps.
electrical energy consumption. With the
used treatment times, 1.5 to 4 min, en-
ergy consumption was 150 to 600 kWh/t 4.3 Development of fibre kappa
correspondingly, making the process ec- distribution method
onomically unattractive. A new measurement method for pulp ho-
The positive effect of overpressure mogeneity was developed and tested,
on impregnation was seen at high kap- based on the same detection principle as
pa numbers (Figure 4) as reduced reject in single fibre measurement by the Fiber
content and reduced kappa number. The Kappa Analyzer FKA (Gustafson et al.).
effect was not, however, seen together The method is based on fluorescence mi-
with the pre-steamed reference pulps. croscopy of acridine orange stained fibres
Clearly, the pre-steaming time used was and image analysis directly from hand-
sufficient to remove the majority of air sheets (Figure 5). Depending on the fi-
and, therefore, the influence of overpres- bre’s lignin content, individual fibres flu-
sure was not evident. During microwav- oresce at specific intensities of green and

72

Figure 4. The influence of impregnation with staining carried out by dipping a
method on rejects content with screened piece of handsheet into the staining liq-
chips and 10% over-thick chips.
uid. This caused surface roughening due
Chip pretreatments: S=steaming,
to fibre swelling, which resulted in micro-
US= ultrasound, MW= microwave,
surf= surfactant, 5 bar = 5 bars N2 scope focusing problems. To eliminate this
pressure. problem, fibre staining was subsequent-
ly performed prior to making the hand-
sheets. Using this method, 8 to 12 sam-
ples could be prepared during a work day.
Thick 60 g/m2 handsheets were initially
used for testing, but thinner handsheets
(20 g/m2) were subsequently introduced
in order to avoid problems caused by
overlapping fibres. Fibre overlap increas-
es the proportion of middle kappa number
fibres, because the test gives an average

g/m2) were made on a glass substrate to
value for the overlapping fibres.
Finally, very thin sheets (1, 2 and 5

avoid the effect of overlapping fibres. How-
ever, the very thin sheets exhibited a high
proportion of empty spaces between fibres.
Image analysis software was used to elim-
inate these gaps and to exclusively mea-
sure the fibres. As the number of fibres per
image is significantly reduced in very thin
sheets, this had to be compensated for by
taking more images in order to maintain
measurement accuracy. The time-consum-

benefit of this method compared to the FKA
ing imaging process involved reduces the

method. The final tests showed, however,
that thin sheets reduced the effect of fi-
bre overlap, enabling measurement using
this technique, and the thin sheets on glass
red wavelength. Fibres with a low lignin method ultimately proved to be ideal for
content show a high intensity peak in the microscope analysis.
green wavelength region, thus appearing The staining procedure occasional-
green in the fluorescence image. High lig- ly caused reddish discolouration of the
nin content fibres have a high intensity handsheets. The chemistry of staining
peak in the red wavelength region, thus with acridine orange (AO) is not known.
showing as red. The red to green ratio However, the discolouration problem was
is calculated, and an image analysis pro- identified as being caused by the pres-
gram gives a “kappa number” image ac- ence of hypochlorite, which was used to
cordingly. The image analysis procedure counteract the autofluorescence of lig-
is written as a macro which enables im- nin. The final tests were performed with-
ages series to be automatically analyzed. out hypochlorite based on the assumption
At the beginning of the project analy- that the effect of lignin autofluorescence
ses were conducted on thick handsheets, is negligible.

73

Figure 5. “Kappa” images showing high kappa number fibres as brighter than low
kappa number fibres. The left image shows a 20 g/m2 sheet, the right image
a 5 g/m2 sheet. The empty spaces between fibres are removed by image analysis.

The repeatability and reproducibility pulps can be compared with this meth-
of the method’s results proved to be rel- od, the calibration of red to green ratio to
atively good. However, it was found that kappa number values is still uncertain and
fresh colorant should be used and that requires further testing.
the fluorescence imaging should be car-
ried out within a few days after staining.
Single point calibration using the pulp’s
average kappa number and the average
5. Future plans and
red/green fluorescence ratio did not work key development needs
reliably with the histogram data. The res-
caling of the red to green ratio with re- The most valuable result of the prehy-
spect to kappa values needs to be based drolysis study was the understanding that
on at least two-point calibration with the connecting biorefinery stages to kraft pro-
measured kappa numbers of the studied cesses requires extensive exploitation of
pulps (Figure 6). However, different wood the whole process chain. The kappa num-
species and cooking liquors can result in ber variation of the samples can be reli-
different responses to staining in terms of ably measured and the pulps can be com-
red/green fluorescence ratio.” Thus, dif- pared using the developed sheet mea-
ferent calibration curves are needed for surement based fibre kappa method. The
different kinds of pulps. fibre kappa analysis method requires fur-
The outcome of the study was a re- ther testing with respect to the calibration
peatable method for measuring kappa of the red to green ratio to kappa num-
number variation. The developed method ber. The results of the Short pulping proj-
has, however, certain limitations. While ect have been used in preparation of the
the kappa number variation of the sam- continuation of EffTech program.
ples can be reliably measured and the

74

Figure 6. Fibre kappa distribution curves for three pulps with different kappa
numbers (18, 30 and 46) and for one sample with mixed pulps (kappa 32),
sheet grammage 20 g/m2. The dashed line shows the calculated curve for mixed
kappa 18 and 46. The sample with mixed pulp showed a wide kappa number
distribution curve. The X-axis values are calibrated using a three-point scaling
method based on the measured kappa numbers of the used pulps. However,
the correlation with the kappa numbers is not validated.

6. Exploitation plan and 7. Publications and
impact of results reports
The value of the prehydrolysis studies de- Montonen, R., Mustonen, K., Karppin-
rives mainly from increased knowledge of en, T., Salmi, A., and Hæggström, E.,
the ways in which possible future biorefin- “Stiffness measurements of Single Plant
ery pulp mills would influence pulp mak- Fibers with Ultrasound under Humidi-
ing and how the drawbacks of prehydroly- ty Cycling”, IEEE International Ultrason-
sis can be decreased or even eliminated. ics Symposium 2009, Rome, Italy, 23–
The fibre kappa analysis method increas- 26.9.2009
es knowledge of the influence of process
changes on pulp homogeneity, thus lead- Mustonen, K., Quantifying the effect of
ing the pulping process towards better Fibre damage on pulp sheet strength by
and more uniform pulp quality. ultrasound, 2009, Pro gradu, Department
of physics, UH.

Hanhikoski, S., Bleachability of pre-
hydrolysed softwood kraft pulps, Puu-
23.4030 Pulping Technology Research
Project, 2010, Department of Forest Prod-
ucts Technology, Aalto University

75

New process design methodology
to reduce capital employed and
to improve flexibility (POJo)

Project Manager Risto Ritala, risto.ritala@tut.fi




Tampere University of Coordinator; measurements, control and decision sup-
Technology, Measurement port as degrees of freedom in production systems de-
information (TUT) sign; operational and design optimization

Aalto University, Present and future IT infrastructure in process industries
department of Automation and as enabling technologies
Systems Technology

University of Jyväskylä, Multiobjective optimization, formulation and solvers
Industrial optimization (UJY)

University of Kuopio, Process modelling and model-based optimal operation
Paper physics (UKU) and design of production systems

VTT, Technical Research Centre Dynamic process modelling of pulp and paper making
of Finland, Process modelling processes, APROS dynamic simulator

76

Abstract
A general model-based multiobjective and bi-level production system design methodology has
been developed. All process structures and dimensioning are compared (upper level) when
each design is operated optimally (lower level). Three levels of modelling are required: simple
models for operational optimization to predict system behaviour over the short term; models of
intermediate complexity for assessing design performance over the long term (including oper-
ational optimization); and detailed process models for design validation. Multiple objectives at
both the operational and design levels are taken into account. At present, the design provides
the structure and dimensioning of process equipment and the operational policy as scalarization
parameters for operational optimization. The methodology has been tested for the design of fur-
nish management system (tower volumes and operational policies) in SC paper production. The
methods provide a solid basis for production concept development within EffNet programme.
Further development of the methodology will concentrate on expanding the multiobjectiveness
of operation and on dealing with more complex design tasks.
Keywords: design, operation, optimization, multiobjective, furnish preparation, SC paper,
work flow

77

1. Project background pable of fully utilizing the degrees of free-
dom provided by measurements, control
Heavy capital investment and inflexibility and operational decision support systems
of production systems are the key busi- and which thus reduces capital employed
ness challenges of the chemical forest and enhances production flexibility. The
industry. In this industry, the design of methodology is based on dynamic model-
production systems has been considered ling and multiobjective optimization.
from the point of view of material equilib- The technical goals of the project are to:
ria at operating points. The design of pro- 1. Formulate the design as a
duction system dynamics has been based multiobjective optimization problem
on rather coarse studies of production on a dynamically modelled “super-
disturbances. The buffering volumes be- structure”
tween production departments and mech- • Using approximate solution
anisms for attenuating disturbances have methods
been designed accordingly, but only after • Accounting for the role of
the main structures of the production sys- uncertainty
tems have been determined. The control 2. Collect and develop a library of unit
system and operational decision support operations to be used in model-
systems have thus had rather few de- based analysis of production system
grees of freedom in the design and, as a concepts
result, both dynamic behaviour and capi- • Using cross-disciplinary models,
tal efficiency are suboptimal. Many oper- models of information
ations that could otherwise be carried out operations
using information, computational meth- 3. Understand the opportunities of
ods and control are instead implement- IT and current best practices and,
ed with additional process equipment that within the next 5–10 years, to
carries high investment costs. Further- transform actions made by unit
more, implementing the management of process equipment into information-
disturbances using separate devices and based actions
equipment has led to lengthy transition
times between operating points, i.e. poor The methodology developed will be
flexibility. demonstrated by a large-scale design
Chemical engineering methods for case study. The chosen case is the SC pa-
integrated control and process structure per production system, in particular its
design have been developed as best prac- functions in furnish preparation and wa-
tices in the chemical process industries, ter management.
but have not been applied in pulp and pa-
per production. Furthermore, the recent
ideas on biorefineries and its integration
to conventional pulping and papermaking
has opened up opportunities to radically The research hypothesis of the POJo proj-
rethink material flows and to seek com- ect is that production system design can
pletely different process structures. be specified as a bi-level multiobjective
optimization problem where an lower lev-
el optimizes the operation of the produc-
tion system and an upper level optimiz-
2. Project objectives es the structure. Furthermore, it was hy-
The main goal of the project is to develop pothesized that such an approach to pro-
a process design methodology that is ca- duction system design can be implement-

78

ed in practical production system design and grade changes
at the conceptual stage by using appro- • Stage 3: Relatively limited scope
priately modified working practices. The design problems related to
approach is expected to be generic, but papermaking; e.g. design of broke
its practical implementation requires a systems volume, design of buffer
domain-specific unit process model li- volumes, design of TMP plant
brary. capacity and buffer volume.
In order to analyze the validity of the • Stage 4: Wider scope design
hypotheses, the following research ques- problems related to papermaking:
tions have been addressed: design of volumes of furnish/water
• Given a production system design towers for a single-grade SC paper
task, which are the general machine (main case)
guidelines for formulating it as a bi-
level multiobjective optimization In the EffNet programme, which con-
problem? tinues the work of EffTech/POJo, the
• Given a typical optimization stage 5 problems cover the design of the
formulation corresponding to a entire production system, with quality and
pulp and paper production system resource efficiency as the main objectives
design, how can it be solved at both the operational and design levels.
within the time frame allowed for Analysis of the solvability of the de-
conceptual design? sign optimization problems led early on
• How radically must working to the study of the unit process models
practices in production system at three levels of detail:
design be re-engineered in order • Operational optimization models
to take full benefit of the bi-level that are simple and fast to execute
multiobjective approach to design? and are evaluated analytically
rather than simulated
POJo was initially designed for the en- • Design optimization models
tire duration of the Efftech problem, i.e. 4 that are dynamic mass balance
to 5 years, and the research approach has models in which quality models
been chosen accordingly. In order to un- are based on furnish composition.
derstand the essentials of bi-level multi- The models include operational
objective formulation and how it is solved, dynamic optimization. The design
a series of design/operational problems of optimization models are fast enough
increasing complexity have been specified to enable hundreds of designs to be
and analyzed as follows: assessed in hundreds of operational
• Stage 1: Extremely simple generic tasks, which is achieved by simple
systems which nevertheless contain simulation methods
the basic ingredients of the design • Design verification models that
(operational level: dynamic, consist of detailed simulator
stochastic, partially observable, models, most notably APROS.
multiobjective; design level:
multiobjective, some objective(s) The research approach regarding
derived from operational level working practices in design included in-
performance); e.g. the three-level terviews and analysis of current design
system software tools, on the basis of which plan-
• Stage 2: Multiobjective operational ning of working practices using bi-level
problems related to papermaking; multiobjective design is being developed
e.g. multiobjective quality control in the EffNet project.

79

4. Results the optimization point of view, the design
problem is then to find optimal values for
This chapter is organized as follows: Sec- the design variables with respect to the
tions 4.1 to 4.4 discuss the generic PO- objectives and subject them to the con-
Jo approach to model-based multiobjec- straints. In the bi-level problem, the up-
tive optimal design. 4.1 discusses the for- per-level objectives typically model strict-
mulation for the design task, and 4.2 the ly design-related aspects, such as invest-
implications for work flow in design. 4.3 ment costs or the type of technology
outlines the required models, and 4.4 dis- used, while the lower-level objectives are
cusses the software aspects. Sections 4.5 likely to quantify the operational perfor-
and 6 present the results from the case mance of the design. In particular, evalu-
studies. In 4.5, the methodology is illus- ation of the lower-level design objectives
trated with the main case study on a fur- requires an optimal control strategy to
nish preparation system for SC paper pro- be available for each design considered,
duction. Although the main case is an in- which justifies the bi-level formulation in
dustrially relevant design task, its analy- which the optimal performance of alter-
sis here is mostly from the point of view native designs cannot be evaluated unless
of testing the generic methodology. 4.6
presents some smaller cases analyzed
during the project which have industri-
al relevance.

4.1 Design as a bi-level Figure 1. Structure of bi-level design
optimization, the lower level. The
multiobjective optimization
design is modified based on the
problem performance metrics achieved, i.e. the
The design of production systems re- box below. The variables referred to
quires the comparison of mathematically are from the main case study, see 4.5.
modelled design alternatives while each
of them operates in the best possible way.
The comparison of alternative designs
and their optimal performance gives rise
to a bi-level optimization problem, (Figure
1). Additionally, the comparison of de-
signs and the assessment of their perfor-
mance are both carried out with respect
to multiple conflicting objectives, making
the optimization problem multiobjective
at each level. To address production sys-
tem design, it is therefore necessary to
utilize the bi-level multiobjective optimi-
zation framework in order to develop a
methodology to determine the best pos-
sible design.
With respect to modelling, optimal
design of a production system involves
choosing appropriate design variables,
objectives and constraints representing
the design problem at each level. From

80

the optimal control strategies are known. representative of the full range of possi-
The two optimization problems, the ble events and is provided by means of
design optimization at the upper level and explicit scenario-dependent design crite-
the operational optimization at the lower ria rather than probabilities that might be
level, are combined into a bi-level optimi- difficult to quantify. At the lower level, un-
zation problem. The upper-level problem certainties are related to the behaviour of
is solved for the optimal design structure, production subsystems and components
while the lower-level problem is a con- for which probabilities are assumed to be
trol problem seeking an optimal control known.
to guarantee optimal design performance. Furthermore, the system under de-
The operational optimization problem at sign faces various production tasks that
the lower level is then parameterized by are accounted for in the problem formu-
the values of the design variables, and lation in the same way as scenarios. That
in the design problem at the upper level is, the upper-level design objectives are
optimal control strategies are known for evaluated separately for each production
each design as a result of solving the low- task and the designer’s preferences are
er-level problem. used in place of relative frequencies of oc-
While bi-level optimization problems currence. A distinction between produc-
have been thoroughly studied in recent tion tasks and scenarios is, however, nec-
decades, their multiobjective counterparts essary because quite often each produc-
with multiple objectives at one or both tion task has to be considered in the con-
levels have, for the most part, been de- text of all scenarios.
veloped only in the last decade. Bi-level The multiobjective component of the
multiobjective optimization problems are overall model enables a flexible scenar-
much more complicated than bi-level sin- io-based approach to handling uncertain-
gle objective problems because the so- ties at the upper-level, and also allows
lution set of the lower-level multiobjec- the designer to learn about the interre-
tive problem generally consists of infinite- lations and tradeoffs among the optimi-
ly many elements. Since this solution set zation objectives during the design pro-
is needed to solve the upper-level multi- cess at each level in order to make knowl-
objective problem, the overall problem is edgeable decisions about the preferred fi-
highly complex and computationally very nal design.
costly. However, an integrated design and The research project proceeded along
operational optimization problem has cer- several lines. During the initial stage, the
tain special features that set it apart from project performed a thorough study of the
a general bi-level multiobjective optimi- state of the art in the subject areas relat-
zation problem, and therefore it is likely ed to the project including bi-level multi-
that increased computational efficiency in objective optimization, parametric multi-
solving the problem can be achieved with objective optimization, dynamic multiob-
a tailored solution method. jective optimization, multi-scenario mul-
In the design of a production system tiobjective optimization, and multiobjec-
with a life span of several decades, un- tive control. We also gained knowledge
certainty obviously plays a major role due about the properties of the integrated de-
to its presence at each level. At the up- sign and operational optimization prob-
per level, uncertainties include parame- lem associated with optimal design of a
ters of the business environment such as paper mill.
changes in economic conditions or cus- In the second stage, we proposed two
tomer demands and are taken into ac- solution approaches to the overall prob-
count as scenarios. A set of scenarios is lem, each addressing different aspects of

81

the problem. We developed a solution ap- signers. If an optimizing process design
proach for a special class of bi-level mul- business process is adopted, an addition-
tiobjective optimization problem which is al actor, a process optimizer, will be need-
encountered in the production systems ed. The process optimizer may be one or
design and which addresses the specif- more persons who are able to support op-
ic needs of the project. We also devel- timization of process designs. The process
oped a method to coordinate the solution optimizer needs to cooperate particular-
of a (single level) multiobjective optimi- ly with the process designer and possibly
zation problem involving multiple scenari- also with other actors.
os, which allows the decision maker to as- The core processes of process design,
sess the extent to which each objective is as it is nowadays, can be broken down in-
impaired in any particular scenario due to to three core activities: design task defini-
the performance requirements of the oth- tion, actual process design and design ac-
er scenarios. ceptance. The first activity in the process
In the third stage of our research we design work flow is to specify the struc-
started computational work on solving the tural design of the process. The designed
lower-level operational optimization prob- aspects of the process include the com-
lem. Being a control problem, the lower- ponents of the process and their proper-
level problem is solved with model pre- ties and connections. The design evolves
dictive control (MPC). Being also a mul- from initial and draft designs to the final
tiobjective problem, it should be solved design, with the resulting design typical-
with special consideration given to the ob- ly having a P&I diagram level of accura-
jectives. During the current stage of our cy. During the design process, designs are
work, the multiple objectives have been created and evaluated. The nature of pro-
scalarized into one, and the tradition- cess structure design is usually iterative
al (single objective) MPC computations to some extent and the structural design
have been performed. Once the results activity is complemented with operation-
of these computations are validated, the al design. A particular feature of process
next step will involve using a multiobjec- operation design is that it is dependent
tive MPC approach to assess the tradeoffs on structural design and provides feed-
between the operational objectives and back for it. The structural and operation-
provide more insight into optimal control al design activities are usually concurrent
at the lower level. and progressive, proceeding from aggre-
gate designs to detailed designs.
If optimizing process design is adopt-
4.2 Work flow of model-based ed, both the new process optimization
multiobjective design activity and some developments to the
The essential aspects of the business pro- existing process design activities are re-
cess of model-based multiobjective pro- quired. The optimization activity is a con-
cess design include the actors, process- sulting type of activity. It starts with re-
es, data and supporting IT systems, and quirements and an existing process de-
the relations between them. sign, and produces suggestions for how
The business process of process de- to make the design more optimal. At the
sign takes place as a networked activity same time, the multiobjective nature of
combining actions of several actors with the design problem needs to be noted al-
different roles, organizations and physical so in the other design activities. The main
locations. Nowadays, the main actors in- difference to current work practice is that
volved in the process design are the pro- the design objectives are specified mathe-
cess designer, the customer and other de- matically in order to be suitable for math-

82

Figure 2. The three levels of model used
in design and operational optimization.

ematical optimization. During the design systems. In addition to these, other types
activities, the relations between structur- of IT systems are also used, such as doc-
al and operational designs must be stud- ument management systems, spread-
ied carefully, and during the design evalu- sheet calculators and word processors. If
ations, both the structural and operational optimizing process design is adopted, cer-
aspects of the design will need to be com- tain modifications to the IT-systems used
bined. Acceptance of the design should, for process design will be needed. The op-
again, be based on the best balance be- timization activity will require new calcu-
tween the design objectives. lation tools or, at least, new models to be
The most important sets of data ma- used with the existing tools. Furthermore,
nipulated during process design can be data transfer between the tools used by
divided into requirements, design, evalu- the process designer and optimizer will
ation and resource data. The design da- be required.
ta includes two components covering the
structure and operation of the process be-
ing designed. If optimizing process de- 4.3 Three levels of modelling to
sign is adopted, this needs to be taken support design optimization
into account also in the usage of design Models of the studied process play a cen-
data. The multiobjective nature of pref- tral role in the development of the PO-
erence-type requirements must also be Jo methodology. During the project it has
noted. The same issue obviously concerns become evident that different types of
the design evaluations based on these re- models are needed for different tasks of
quirements. However, the effect of the the methodology. We have currently iden-
new design process on the other process tified three levels of model to be applied.
design data sets is less obvious. These are referred to as prediction, nomi-
The most essential IT systems used nal and validation models. All of the mod-
during the process design include engi- els are dynamic, as the goal of the meth-
neering design systems and calculation odology is to optimize process dimension-

83

ing and operation. The following figure il- advances, the control of the process is
lustrates how these models fit into the optimized (Figure 1).
methodology framework. To address the validity of the solution
Figure 2 divides the design – including a specific validation model is used, as il-
operational optimization – into two phas- lustrated on the right-hand side of Figure
es: the optimization itself and the vali- 2. The validation model is used to com-
dation of the optimal design. In the fig- pare how the selected optimization prob-
ure, y is the information that the optimiz- lem formulation and solution perform in
er receives from a model, i.e. the mea- a more realistic setting. The prediction
surement, and u is the control vector that model remains the same, but the nominal
drives the model. model is replaced by the validation mod-
Operational optimization applies the el. This model describes the same process
prediction model. The optimization of the area as the nominal model, but is more
operation of the process uses an MPC- detailed and thus more realistic. For ex-
type approach. In this approach, vari- ample, in the POJo main case the valida-
ables are projected into the future at tion model’s additional details were im-
each time instant of the optimization. To plemented in such a way that they con-
do this in practice, the prediction mod- stitute a super-structure. Each additional
els must be computationally efficient as detail has a parameter indicating wheth-
numerous calls are made. For example, er it is taken into account or not. In the
in the main case of the POJo project, the first modification, the filler retention at
prediction model used was a k-step-ahead the PM is allowed to vary. The filler reten-
linear multiple-input, multiple-output tion variation was modelled simply as ad-
transfer function that was derived from ditive, filtered random noise. The second
a more detailed model by analytic meth- modification was made by allowing quali-
ods and step response tests. The model ty variation in the flow line from the TMP
predicts how paper quality variables and mill, and random two-state switching be-
tower volumes evolve as the control vari- tween normal and poor quality TMP. The
ables are manipulated. third modification added a new tank to
The nominal model which is used the water system denoting white water
during the design phase is more detailed tank in addition to the white water tower.
than the prediction model and slightly less To conduct a validation of optimal de-
efficient. The model focuses on the major sign and operation, a set of comparison
dynamic features of the process at hand. variables that describes the key features
This allows the model to be simulated of the process must first be defined. The
with a large time step (e.g. 10 min in the comparison proceeds as follows:
main case). In the POJo main case, the 1. Run simulation experiments to
process encompasses the paper machine, obtain optimal time series of the
stock preparation, broke system and wa- comparison variables (denoted by
ter system in an SC production line. The xi,j,nom(t), i = 1,…,Ncomparison
main flows and levels of the largest tow- variables and j = 1,…,Nreplications)
ers are simulated with the nominal mod- with the nominal model and the
el. The optimizer uses the nominal mod- selected optimization method.
el to evaluate its objective functions us- 2. Run simulation experiments to
ing the process measurement variable y. obtain optimal time series of the
As a result, the optimizer solves the opti- comparison variables (xi,j,val(t),
mal control vector u* that is used to con- i = 1,…, Ncomparison variables and
trol the nominal model for the next time j = 1,…,Nreplications) with the
step. By repeating this procedure as time validation model and the selected

84

optimization method. to achieve a reasonable design optimiza-
3. Perform a qualitative analysis tion computation time, whereas the vali-
(i.e. visual evaluation of the data) dation model was simulated with APROS,
for all time series pairs (variable either as standalone or as communicat-
xi,j,nom(t), variable xi,j,val(t)). ing with Matlab for operational optimiza-
4. Perform time-mean value tion. As the number of validation simula-
distribution testing. tions is much less than in design optimi-
5. Perform coefficient of variation zation, the validation response time is ac-
distribution testing. ceptable with this arrangement.
6. Summarise the results of the The connection between APROS and
comparisons. Matlab was realized in two different ways.
The first and simplest way involved trans-
In steps 1 and 2, several simulation ferring data between the two softwares
replications with both models are realized. using ASCII text files. Matlab wrote the
This is done because the process contains control actions into a text file which AR-
stochastic elements (web breaks) and POS read and simulated over a predefined
thus a single simulation is not represen- time period. During this period APROS
tative. This is also reflected in steps 4 and logged the selected variables in anoth-
5 where statistical comparisons are made. er text file that was read by Matlab as
The purpose of step 4 is to see whether the input for the optimization. Although
the average behaviour of the systems is far from efficient, the approach proved
similar, and step 5 assesses the similari- to function reliably. Later in the project
ties of the systems in terms of their vari- a more advanced means of connecting
ation. Step 6 involves producing an anal- Matlab and APROS was implemented us-
ysis of the previous steps, including eval- ing the OPC communication protocol. In
uation of a set of indices quantifying the this setup, an external OPC client appli-
similarities of the systems. cation was installed in Matlab. This client
was used to connect Matlab to the APROS
OPC Server. All data and commands were
4.4 Implementing the approach transferred through the OPC channel and
with pre-existing software no text files were used. The efficiency of
The simulation-based design and opera- this approach was evident.
tional optimization has been implement- In both setups Matlab acted as a
ed using pre-existing software packag- “master” controlling the flow of informa-
es. The software packages applied were tion. APROS received from Matlab new
Matlab and APROS®. The main software- control actions and the command to simu-
related challenges include the fact that late. After this, Matlab requested the val-
Matlab is not well-suited to implementing ues of the selected variable from APROS
the detailed process models required in and used them in the optimization.
the validation stage, whereas implement-
ing advanced dynamic optimization with-
in APROS is rather difficult without com- 4.5 Main case: Design optimization
municating with external software such as applied to paper machine furnish
Matlab. The required communication adds management
to the computation time, which in turn
slows the design optimization. For this 4.5.1 Definition of the main case
reason, in the typical setup, the optimiza- and its variations
tion algorithm, the nominal model and the The design task is to specify the volumes
prediction model were run in Matlab only of broke, 0-water, clean water, TMP and

85

Figure 3. The main case: furnish and water management
system of an SC paper production system.

chemical pulp towers (and optionally the • rate of pulping of dry broke (A, B)
storage volume of dry broke) and the • fresh water intake (A,B)
corresponding operational policy when • recirculation of disc filter output
a web break statistic is given. The goals back to 0-water tower (A, B)
are to minimize investment costs (tow- • TMP-to-chemical pulp ratio (B)
er volumes), long-term averages of qual- • rate of TMP production (B)
ity fluctuations (filler content and basis • rate of chemical pulp production
weight), time spent in breaks, and the (pulping of bales) (B)
probability of tower overflows. Three ver- • TMP tower inflow consistency (B)
sions of the design were considered: de- • chemical pulp tower inflow
sign of broke tower volume (case 0), de- consistency (B)
sign of broke tower, 0-water tower and
clean water tower volumes (case A) and In the following, the operational op-
the overall case (case B). The operation- timization of case A will be presented
al policy consists of defining the operation and the design optimization of case 0 will
of the following variables (letters in pa- be presented with comments on case A.
rentheses indicate the cases in which the Case B is a relatively straightforward ex-
variable was considered): tension of case A, as the optimization of
• broke dosage (0, A, B) virgin towers is coupled to optimization in
• disc filter feed flow (A, B) case A only through the usage of dilution

86

Figure 4. Case A with operational optimization. Time step 10 min, horizontal axis:
number of time steps. Two leftmost columns, three rows from top: six volumes
(broke, 0-water and clean water towers limited to 3500 m3). Two leftmost columns,
two rows from bottom: paper composition (breaks seen as intervals with zero
values). Third column: manipulated variables. Fourth column deviation of quality
from target (filler target: 0.22, basis weight 6 units, corresponding to a basis weight
of 60 g/m2, strength 0.95 units).

water. See also 4.6.1 for TMP tower opti- nonlinear function of “strength”. The ro-
mization and 4.6.2 for chemical pulp tow- bustness of optimal design with respect
er optimization. to the break model was studied in case
Web breaks cause large fluctuations in 0 (4.5.3).
broke tower and 0-water volumes. There- The nominal model implemented in
fore modelling of breaks is crucial for the Matlab was a simple dynamic mass trans-
success of design. In all cases the breaks fer model evaluated at 10 minute time
were considered stochastic. In case 0 the steps.
onset of a break was directly made a non-
linear function of broke dosage, mimick- 4.5.2 Operational optimization
ing the fact that “vicious circles” of breaks Figure 4 shows a result of operational op-
and the need to increase broke dosage timization. A nominal model has been run
are often experienced at mills. In cases A with a fixed design with operational opti-
and B a “strength” model was implement- mization on. Operational optimization is a
ed and the break probability was made a constrained MPC-type problem looking 50

87

time steps ahead. The goal of the oper- Figure 5. Performance of design options
ational optimization is to keep the quali- in case 0. Top: investment cost and
ty parameters (filler, basis weight and inverse of time till overflow. Bottom:
filler variation and proportion of time
strength) at their target values while pre-
spent in breaks (note: for illustration
venting the broke tower, 0-water tower
purposes, an exceptionally high break
and clean water tower from overflowing tendency has been used). The point
or running empty. These objectives form circled is Pareto optimal and thus the
a multiobjective problem that has been potential design.
scalarized by defining an objective func-
tion that is a weighted sum of squared
deviations from quality set points and
by constraining the probabilities of over-
flows/running empty respectively. The
scalarization parameters are the degrees
of freedom of the design together with
the process structure (tower volumes).

4.5.3 Design optimization
The design optimization considers long-
term averages of performance indices in
simulations such as depicted in Figure 4,
as a function of design degrees of free-
dom. Let us consider case 0, in which we
have only one design degree of freedom
related to the process equipment, i.e. the
broke tower volume. The design seeks to
• minimize investment cost (tower
volume)
• maximize the time till tower
overflow (running the broke tower
empty can always be prevented by
setting broke dosage to zero)
• minimize long-term average quality
variations (filler variations)
• minimize time spent in breaks

The degrees of freedom are the broke
tower volume and the operational poli-
cy. The operational policy addresses the
probability of overflow, filler variations rather by brute force. Figure 5 presents
and risk of breaks during the time ho- the combinations of investment cost and
rizon of operational optimization and is overflow frequency, and filler variation
thus multiobjective. The policy has been and proportion of time spent in breaks.
scalarized with one parameter related to As dealing with numerous objectives
the relative importance of breaks and fill- is laborious for the designer, the follow-
er variations and with a parameter related ing approach has been chosen. Firstly,
to overflow probability. Thus, the design a design candidate was chosen from
must find values for these parameters. among the Pareto optimal solutions by
The design optimization was done considering only the first two objectives.

88

Figure 6. Left: further refinement of designs around the point chosen in Figure 5.
Right: close-up of the figure below left showing the Pareto optimal designs in the
break/filler plane. The final design is chosen from amongst these.

Its performance with respect to the other fore be assessed. Table 1 shows the re-
objectives was then assessed (point cir- sults of such an assessment: three break
cled in Figure 5). To improve the design models have been compared so that the
with respect to the latter two objectives, design has assumed one model and the
designs around the chosen point have performance has been evaluated with an-
been further refined until a good compro- other model. According to these results
mise has been achieved (Figure 6). This the design is quite robust with respect to
compromise is characterized by a combi- overestimation of the break tendency but
nation of broke tower volume and opera- somewhat sensitive to underestimation.
tional policy, which are then implement- The design scalarizes the operation-
ed as a result of the design. al optimization and can thus be criticized
The performance characteristics de- of not leaving operational degrees of f
pend on the chosen break model. Clear- reedom once the design has been
ly, such break models cannot be very ac- implemented. In this sense, the multiob-
curate. The robustness of the design with jective nature at the inner level is lost.
respect to the break model must there- One potential way of dealing with this

89

problem is to design a set of operation- be much more time consuming and, thus,
al policies, each Pareto optimal, and al- the brute force solution applied in case 0
low the process operators to choose from must be refined.
amongst them. However, this is an out- The detailed POJo report will present
standing issue in the methodology devel- the preliminary results on the case A de-
opment rather than an issue for the main sign optimization. Analysis of the main
case. case, versions A and B, will continue un-
Case A can be solved in a similar way der the EffNet WP 9 programme as a test
to that presented above for case 0. For bench for methodology development.
each design, including the three tow-
er volumes and scalarization parameters
of operational optimization, a few tens of 4.6 Further case studies
simulations, such as the one in Figure 4,
are to be carried out in order to assess 4.6.1 TMP plant design
the performance of a design with respect At a highly conceptual level, the TMP de-
to tower volume management, time spent sign problem combines the selection of
in breaks and quality variations. This data the number of refiners and the size of
combined with investment cost data then storage volume between the TMP plant
leads to a similar analysis to that pre- and the paper machine. Electricity is an
sented in Figures 5 and 6. As the design- important operational cost factor in TMP
er chooses between performance alterna- production. The electricity pricing princi-
tives rather than design degree of free- ples for large TMP producers in Finland
dom alternatives, the complexity of the can be fairly complicated as it is in the in-
design is not increased radically although terest of power producers for paper pro-
the process scope is much wider. Howev- ducers to maintain steady consumption.
er, producing the performance data will However, in this conceptual design case

Table 1. Robustness analysis of a selected design for three break probability
functions. The first model is the model with which the performance has been
assessed, and the second model is the model assumed in the design.

Break
probability
(Sr/So)
Overflow
time
Filler
variation
Time
in
breaks

High/
High
491.64
0.1335
0.2981

High/
Med

467.78
0.1547
0.2931

High/
Low

427.94
0.1800
0.2866

Med/
High

895.44
0.1175
0.2323

Med/
Med
900.94
0.1359
0.2250

Med/
Low

896.40
0.1518
0.2199

Low/
High

3327.9
0.0737
0.1056

Low/
Med

3225.1
0.0840
0.0997

Low/
Low
2650.2
0.0962
0.0989

90

it is assumed that the energy cost of TMP Figure 7. Combinations of investment
production at a given moment is inde- and operational cost achievable for a set
pendent of consumption at other time in- of designs (number of refiners, storage
volume). For each design, the operation
stances, and that the instantaneous cost
is optimized for a given variation of
varies over time. Furthermore, it is as-
electricity price and TMP demand. The
sumed that both the price of electricity optimal design is chosen from between
and demand for TMP are known without the Pareto optimal points.
uncertainty 48 hours ahead.
TMP should, naturally, be produced
and its storage increased when electrici-
ty is at its cheapest and, correspondingly,
storage should be decreased and produc-
tion reduced or terminated when electric-
ity prices peak. This combinatorial optimi-
zation problem can be readily solved, for
example by applying the Simulated An-
nealing algorithm.
The higher the number of refiners
and the higher the volume of storage,
the more degrees of freedom there are to
schedule TMP production. However, these
degrees of freedom entail an investment
cost. Figure 7 shows the combinations
of production and investment costs for a vestment cost. Failure statistics are de-
number of designs. For each design oper- termined by the mean time between fail-
ation has been optimized for given short- ures and the probability density distribu-
term price/demand variations. The final tion of duration of failure.
selection in conceptual design can be con- Figure 8 presents the size of the op-
sidered as a multiobjective optimization timal buffer volume as a function of ex-
problem between operational and invest- pected time to recovery for a case in
ment costs in a set of price/demand vari- which failures are rare enough to be able
ations, or the objectives can be accumu- to disregard the risk of double failures.
lated as an average net present value to The time between failures is exponen-
be optimized. tially distributed and the duration of fail-
ure is Gaussian distributed. It is notewor-
4.6.2 Aspects of buffer volume thy that when the recovery from failure is
design fast, there is a discontinuous jump from
Towers are used as buffers: if equipment having a finite size buffer volume to hav-
upstream of a buffer comes off stream, ing no buffer at all. This results from that
production can be continued with the ma- the buffering capacity is prportional to
terial in the buffer. For example, in the volume, but the cost of volume typical-
main case (4.5) the chemical pulp tow- ly scales as Va, with a roughly 0.6..0.8.
er can be seen as a buffer against pulp- Where this discontinuity occurs is a some-
er failure. what complex function of the mean time
The optimal dimension of the buffer between failure, the investment cost co-
is determined by the failure statistics, the efficient and the value of lost production
value of lost production time and the in- time.

91

Figure 8. Optimal buffer size as a the receding horizon prediction principle
function of expected time to recovery (model predictive control).
(arbitrary units). The different Depending on the solution approach,
curves represent varying uncertainty
different optimization methods and mod-
regarding the recovery time (red curve:
elling tools can be used. The main case
deterministic recovery time; other
curves: standard deviation proportional describes the dynamics of the clean wa-
to expected time). The stepwise ter tower, 0-water tower, wet broke tow-
behaviour derives from the points at er, and dry broke storage, see 4.5. In this
which the optimal buffer size has been case study, the modelling is carried out
evaluated. with the aim of obtaining an efficient so-
lution process. The computational time
is therefore minimised to only a couple
of minutes. The aim is to optimize broke
system management, and the optimiza-
tion problem has been defined in three
different ways: as a stochastic optimiza-
tion problem, a linear-quadratic-Gauss-
ian problem and a deterministic problem.
The operational optimization prob-
lems can also be solved using a dynam-
ic process simulator. Even though the to-
tal computational time is shorter com-
pared to the entire bi-level problem, com-
putation for this type of study still takes
hours. Two case studies have been con-
ducted using the dynamic process simu-
4.6.3 Operational optimization case lator developed by Apros and a differen-
studies tial evolution algorithm. The studies cover
At the operational level, the bi-level mul- retention disturbance and grade change,
tiobjective optimization problem contains respectively. In both cases, multiobjective
an optimizer and a mathematical model. optimization was exploited to improve the
In this study, different solution approach- performance of PI controllers. The results
es have been utilized. When results are obtained show that this approach was
required in real time, an efficient solv- able to produce smaller disturbance and
er as well as a simplified model is need- thereby better stability of paper quality
ed. On the other hand, if a longer com- parameters compared to reference simu-
putational time can be accepted, a more lations, as shown in Figure 9.
complex mathematical model can be pre- Based on the promising results of
sented using a dynamic simulator, for ex- the previous case studies, the next step
ample. The basic idea of the solution pro- is to broaden research interest towards
cess is that for the given design (and de- handling bi-level optimization problems
sign level) the corresponding operation- using a similar approach. This would en-
al tasks are solved using multiobjective sure more thorough studies of the de-
optimization. Because the mathematical sign, operation, economy and profitabili-
models are usually dynamic, this has to ty of the paper mill. The most recent case
be taken into account in the optimization study includes the design and operation-
procedure also. In the case studies of the al levels as well as the use of a dynamic
POJo project, dynamics are handled using process simulator. Both levels contain a

92

Figure 9. Results from the retention
disturbance and grade change case studies.

multiobjective optimization problem and task. The opportunity of designing
each solution at the design level requires a Pareto optimal region of
a multiobjective optimization process at scalarization parameters and then
the operational level. The solution pro- allowing the operating personnel to
cess is, consequently, time-consuming choose among these is one avenue
with a computational time measured in to explore.
days. The case study presents the opti- • How to efficiently solve the
mization of broke towers using optimal problems related to increasing
broke handling. complexity? As discussed above
with respect to cases 0 to A of the
main case, the main computational
issue is the efficient generation
5. Future plans and of Pareto optimal solutions. The
key development needs brute force approach used in case
0 can be extended to case A with
The project will continue as work pack- marginally acceptable computation
age 9 of the EffNet programme. The work times, but increasing the complexity
is divided into three parts: methodolog- further calls for a more structured
ical development, solving the most rele- approach.
vant application cases as specified by Ef-
fNet work package 5, and further analyz- The cases to be solved under the Eff-
ing the changes in design work flow re- Net programme will no longer be chosen
quired by the POJo methodology. from the point of view of methodology de-
The main methodological issues to be velopment, but will be based on industri-
tackled are: al relevance and the production concept
• How to retain operational degrees development of the entire EffNet pro-
of freedom in design? The current gramme.
approach designs the operational The work flow analysis has as its
optimization by setting universal goal the drafting of a business plan for
scalarization parameters for the the provision of a design service based
initially multiobjective operational on POJo methodology. The organization

93

of such a service amongst the owners of sults of the project, in particular, can al-
Forestcluster Ltd and consultancy compa- so be readily applied to existing produc-
nies, and the need for setting up start-up tion systems. One such industry-led proj-
companies will be tackled. ect, PäTeVä, has already been carried out
The POJo methodology is expected to (11/08-6/10). In addition, an industry-led
provide short-term benefits, in particu- project closely linked to POJo was con-
lar in the area of operational optimiza- ducted by one of the owners of Forest-
tion. For example, the operation of mate- cluster Ltd resulting, for example, in four
rial flows, studied in conjunction with the MSc theses being carried out at Tampere
main case, is a task today carried out by University of Technology (TUT) totalling
process operators without assistance by one man year of MSc researcher work.
computational tools. Although operators Under the EffNet programme, the in-
are highly skilled in these tasks, in com- tegration of POJo ideas with the Qvision
plex operational situations and in the face project’s groundbreaking work in the area
of dwindling manpower at mills, opera- of future unit processes looks extremely
tional optimization, such as that present- promising. POJo will provide tools for un-
ed in 4.5.2, is expected to be of high po- derstanding and optimizing the mill-wide
tential. The implementation of such tools benefits of new unit process technologies.
will be predominantly carried out by com- The main approach of the project, re-
panies subcontracted by POJo partners. placing process equipment with informa-
tion-based tools, will also change ways
of working in the industry. The transition
towards more knowledge-intensive work
6. Exploitation plan and tasks in such production systems will en-
impact of results hance the industry’s attractiveness and
its ability to employ a more highly skilled
The project addresses the key econom- workforce.
ic challenge of the chemical forest indus-
try – capital intensiveness – and the re-
sults of the project are, as such, essential
with respect to the renewal of the indus-
try. Furthermore, the design methodology
is highly generic and can be applied not
only to the design of papermaking sys-
tems but also to that of biointegrates. The
flexibility and capital intensiveness of bio-
integrates is expected to become a major
issue as investment in this business area
increases. The opportunities provided by
POJo will play a central role in develop-
ing novel paper production system con-
cepts in the EffNet programme, and may
also be drawn on in the conceptual design
of pulp mills in the EffFibre programme.
Uptake of the project results re-
quires active industrial participation and
the generation of industry-led application
projects. The operational optimization re-

94

7. Publications and Ropponen, A., Ritala, R., Pistikopou-
los, E.N., “Optimization issues of the
reports broke management system – the value of
Eskelinen, P., Miettinen, K., “Trade-off the filler content measurement”, Control
analysis approach for interactive nonlin- Systems 2010, September 2010, Stock-
ear multiobjective optimization”, submit- holm
ted to OR Spectrum.
Ropponen, A., Ritala, R., Pistikopou-
Eskelinen, P., Ruuska, S., Miettinen, los, E.N., “Optimization issues of the
K., Wiecek, M., Mustajoki, J., “A Scena- broke management system in papermak-
rioBased Interactive Multiobjective Optimi- ing”, submitted to Computers and Chemi-
zation Method for Decision Making under cal Engineering
Uncertainty”, Proceedings of the 25th Mini
EURO Conference on Uncertainty and Ro- Ruuska, S., Miettinen, K., Wiecek,
bustness in Planning and Decision Making M.M., “Solution Concepts for Some Bi-
(URPDM2010), C.H. Antunes, D.R. Insua, level Multiobjective Optimization Prob-
L.C. Dias (Eds.), Coimbra, April 2010. lems” , 9th International Conference on
Multiple Objective Programming and Goal
Linnala, M., “Optimization and simula- Programming (MOPGP’10’), May 24–26,
tion tools in paper machine concept de- 2010, Sousse, Tunisia
sign”, in Yearbook 2010 in the Interna-
tional Doctoral Programme in Pulp and Sindhya, K., Haanpää, T., Ruuska, S.,
Paper Science and Technology (PaPSaT), Miettinen, K., “Ne“ Mutation Approach
Järvelä, H. (Ed.), Espoo, Finland, in press for Multiobjective Optimization with Dif-
ferential Evolution”, submitted to IEEE
Linnala, M., Madetoja, E., Ruotsalainen, Transactions on Evolutionary Computing
H., Hämäläinen, J., “Operational optimi-
zation as a part of a bi-level optimization Tuomi, A., Application Integration for
problem”, abstract accepted to 24th Euro- Condition-Based Maintenance, MSc the-
pean Conference on Operational Research sis, Aalto University School of Science and
(EURO XXIV), July 11–14, 2010, Lisbon, Technology, Faculty of Electronics, Com-
Portugal munications and Automation, 2010, 51 p.

Linnala, M., Ruotsalainen, H., Ma- Virta, J., Application Integration for Pro-
detoja, E., Savolainen, J., Hämäläin- duction Operations Management Using
en, J., “ Dynamic simulation and optimi- OPC Unified Architecture, MSc thesis, Aal-
zation of an SC papermaking line – illus- to University School of Science and Tech-
trated with case studies”, Nordic Pulp & nology, Faculty of Electronics, Communi-
Paper Research Journal, 25(2), 2010 cations and Automation, 2010, 59 p.

Lintunen, J., Optimal operation of a broke Virta, J., Seilonen, I., Tuomi, A.,
system supported with integrated process Koskinen, K., “SO“-Based Integration for
and control design, MSc Thesis, TUT 2009. Batch Process Management with OPC UA
and ISA-88/95”, 15th IEEE Internation-
Ropponen, A., Ritala, R., Pistikopou- al Conference on Emerging Technologies
los, E. N., “Broke management optimi- and Factory Automation (ETFA 2010),
zation in design of paper production sys- September 13–16, 2010, Bilbao, Spain
tems”, submitted to ESCAPE-20, June
6–9,2010, Ischia, Italy

95

Image-based measurement
methods for quality in pulping
and papermaking (QVision)
Project Manager Heikki Kälviäinen, heikki.kalviainen@lut.fi




University of Helsinki, Inverse Inversion mathematics, prior information.
Problems Research Group

University of Eastern Finland, Surface chemistry application topics
Color Research Laboratory

University of Jyväskylä, Information processing hardware and software to
Department of Mathematical produce image maps, 2-D variability analyser platform
Information Technology specification, prototyping and feasibility analysis.

University of Jyväskylä, Production of prior information on paper structure based
Department of Physics on x-ray tomography, and development of image analysis
methods for characterization of paper structure from 3-D
tomographic reconstructions.

Lappeenranta University of Expertise in fibre technology, processing equipment,
Technology, FiberLaboratory imaging equipment.

Lappeenranta University of Imaging and characterization of paper and print with
Technology, Department of laboratory measurements. Image processing and analysis
Information Technology methods for process measurements.

Numerola Oy Development of optimization algorithms, implementation
of (pre-existing) quality models.

University of Oulu, Control Process control and diagnostics.
Engineering Laboratory

University of Oulu, Testing a polarization microscopic method for measuring
Measurement and Sensor dirt particles and fibre deformations from pulp.
Laboratory

University of Oulu, Opto- Optical coherence tomography of paper.
electronics and Measurement
Techniques Laboratory

Tampere University of Measurement and control of MD and CD variations. Trans-
Technology, Institute of mittance as indirect measure of basis weight in control.
Measurement and Information 2-D adaptive estimation. Imaging measurements of paper
Technology structure in laboratory conditions. Roadmap analysis.

96

Abstract
The QVision project investigates image-based quality measurement methods for pulping and
papermaking. Digital imaging has long been applied in the paper industry for defect detection,
but only recently have bit and position resolutions and the storage of images been technically
developed to enable 10 m wide web imaging and the storage of images at a spatial resolution of
0.1 mm over hundreds of meters of web running at 30 m/s. However, as yet, such image data
has not been used as a means of managing quality or quality uniformity. The QVision project has
proposed and developed image-based measurement methods capable of developing the func-
tional properties of fibre-based products and also controlling them during production at a radi-
cally improved degree of specificity and scope. The methods are a necessity in the development
and production of new high added-value products. The research focused on the development
of a 2-D web-wide variability analyser, high-resolution and rough-resolution structural scanning
measurements, dirt (and other) particle analysis, 2-D control methods and surface chemistry.
Keywords: papermaking, pulping, paper web, image processing and analysis, machine vi-
sion, control, overall quality

97

1. Project background an adequate picture of a product’s quality
at the resolution that is used in the actual
This report presents the content and re- final assessment of the product, such as
sults of the QVision project, which oper- during visual assessment by the end us-
ates under the EffTech programme led by er. Current quality management will thus
Forestcluster Ltd. The aim of the proj- prove inadequate in most cases in the fu-
ect is to investigate image-based quali- ture, thus making it a limiting factor in
ty measurement methods for pulping and the regeneration process.
papermaking. The project contains 11 re- Digital imaging and illumination tech-
search partners and the involvement of nology have been two of the most rapid-
several industrial partners from Forest- ly developing sectors of electronics during
cluster. the last decade. Digital photography and
Wood is among the few Finnish raw the emergence of mobile phone and dig-
materials with reserves large enough ital camera hybrids have been the driv-
for large-scale production. Despite this ing forces within the consumer market,
wealth and a diversity of end products and scientific imaging, for example in the
the forest industry is, due to a number health sector, is always hungry for more
of reasons, in a state of transition. The sensitive technology. Technological ad-
capability of the Finnish chemical indus- vancements in imaging and illumination
try to produce fibre-based products at a have also enabled more profound labo-
large scale is an important advantage. Al- ratory research, development, and qual-
so, the necessary production plants are ity control of products, as well as indus-
available and functional, and the industry trial applications in the control, diagnos-
has the knowledge to use these resourc- tics, and quality management of manu-
es to convert and refine the raw materi- facturing processes. Machine vision has
al into fibre-based products and raw ma- been applied in the paper industry for a
terial for other processes. To adapt to the long time, but imaging and image pro-
current challenges related to the raw ma- cessing technology has only recently de-
terial, energy, environment, and global- veloped to enable image data capture at a
ization, the forest industry has to reorga- 0.1 mm resolution across an entire paper
nize. One of the central goals of the in- web moving at 30 m/s. When calibrated
dustry’s regeneration is to increase the and controlled with appropriate laborato-
proportion of high-value-added products. ry measurements, such information en-
From the business viewpoint, prod- ables a radically new view of the product
ucts that are demanding to produce will in terms of both representation and cov-
play a key role in this regeneration. In erage, and can also be used for diagnosis
this scenario, it is reasonable to assume and control of the product itself.
that the requirements for these products The development of image-based on-
and their functionality should be consider- line solutions is the ultimate goal of the
ably higher than those applied today. This QVision project. To reach this goal, de-
implies that the measurement technolo- velopments in off-line and laboratory lev-
gy currently used as the basis of qual- el measurement are also investigated,
ity management poses a potential ma- including new types of enhanced imag-
jor limitation. Current quality control is ing such as nanotomography. Such mea-
based on a combination of scanning on- surement techniques enable better un-
line measurements and automated and derstanding of the structure of paper and
manual laboratory measurement of sam- related phenomena.
ples. These existing practices do not give

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2. Project objectives • Methods for image registration and
image combinations.
This chapter considers the objectives and • Characterization of paper properties
restrictions of the project. The content of and other properties related to
the project is described, including rele- quality.
vant research tasks and development • Tools for combining image-based
steps during the research. measurements and modelling for
QVision focuses on image-based mea- innovation of paper structure.
surement and characterization methods • Framework for overall management
related to quality in pulping and paper- of quality.
making. The project develops methods
enabling the development of functional The scientific objectives of QVision are
properties of fibre-based products, and as follows:
also the management of relevant proper- • To apply modern digital imaging and
ties in production, at a radically improved illumination technology.
degree of specificity and scope. The proj- • To analyze large data sets real-time.
ect develops entirely new measurements • To understand image-based
characterizing structures and quality, and characterization.
a procedure for transferring image-based • To apply inversion methods.
research and off-line methods to on-line • To combine the quality control
use and for quality management. concept to data analysis and control
The technical objectives of QVision methods.
are as follows:
• Solutions for imaging measurement To obtain the set objective, the con-
of paper web and processes. tent of the project is organized as shown

Figure 1. Content of the QVision project.

Design of Measurement of Web-wide on-line Diagnostics

product structure structure measurement and control

T4. Forming informative
T2. Combining images
paper structure images
for diagnostics
T1. Overall
T5. Innovation of
and control quality
paper structure T3. Characterisation
management

with present
T6. Applying prior information actuators

actuators

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in Figure 1. The research has been divid- new features using (multimodal/
ed into 6 research tasks. sensor) imaging and pattern
The project’s research work consists recognition.
of the following task combinations: • T5&T6: Applying prior information
• T1&T2: Combining images for and optimizing paper structure,
diagnostics and control together with a research question of what
with overall management of quality, new tools could be available; using
with a research question of how to simulation tools for innovating and
produce/use real-time 2-D web- (inverse) mathematical tools for
wide image data for on-line control modelling.
using suitable image resolutions.
• T3&T4: Imaging and One of the main objectives is to pro-
characterization of particles and duce new kinds of data for enhanced un-
structure, with a research question derstanding and analysis of the phenom-
of how to go from current/new data ena influencing papermaking quality. An
by current/new measurements to example is shown in Figure 2, which gives

Figure 2. Paper web variations in MD (machine direction) and CD (cross
direction): (a) Model of actual variation; (b) Scanner-based 2-D estimate;
(c) Real 2-D data from a multi-camera imaging system.

(a)
(b)

(c)

100

Figure 3. Different imaging modalities.

alternative views of the “natural” varia- plication templates. The application tem-
tions on a paper web due to the paper plates were grouped, and the applications
structure and the manufacturing process. with highest potential were chosen either
The real 2-D data are produced using a as an application development task or
multi-camera imaging system. The task a feasibility study depending on the re-
involves highly demanding on-line mea- quired stage of research. Each applica-
surement, since the web runs at 30 me- tion development task was led by one re-
ters per second and the 2-D web image search and one industry partner, and each
consists of several images taken over a feasibility study by one industry partner.
large area. Another area of interest is the Further development focused on the
use of other imaging techniques such as following application development tasks:
spectral imaging, fluorescence, polarized a) 2-D web-wide variability analyser, b)
light microscopy, nanotomography, etc. high-resolution structural measurements,
(Figure 3). It is also important to under- c) rough-resolution structural measure-
stand the relationships between reflec- ments, and d) particle and fibre analy-
tance and transmittance images. This en- sis, and on the following feasibility stud-
ables both the paper surface and internal ies: i) 2-D control methods and ii) sur-
structure, which are both crucial to print- face chemistry.
ability, to be analyzed.
The results of the research tasks were
then considered from the point of view of
possible future application requirements.
The goal was to identify key areas for fu- The work was initiated by technical stud-
ture research. A ‘from research to appli- ies in the six task areas defined in Sec-
cations’ roadmap was then drawn up to- tion 2. Parallel to this work, the application
gether with the project’s industrial part- roadmap was developed and the applica-
ners, during which each research and in- tions with highest potential were identified.
dustrial partner was asked to propose ap- These were further divided into applications

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for which technical development could be the QVision paper samples and Testaa 1
formulated as clear tasks (application cas- process data (SUORA environment).
es) and those for which development re- Particle and fibre analysis: Current
quired further specification (application fea- image analysis systems for particle de-
sibility studies). Roughly at the mid-project tection are not as reliable as is needed.
stage, the organization and goal setting of With new imaging and lighting techniques
the project was transformed from research combined with more efficient image anal-
tasks into applications. ysis, particle detection could be improved.
2-D web-wide variability analys- The same techniques could also be used
er: The goal was to acquire image se- for fibre analysis and could also enable
quences from full-scale paper machines particle and fibre analysis directly from
and to develop methods to correct geo- flowing pulp. The research focused on 1)
metric and illumination variations, stitch development of imaging systems for pulp
them together, and analyze them with suspensions, 2) image analysis methods
statistical signal analysis methods. More- for particle detection and 3) implementa-
over, quality data has been collected ei- tion of spectral and/or fluorescence imag-
ther on-line (Quality Control System, ing in particle detection, by using differ-
QCS) or off-line with the paper web anal- ent types of dry sample sheets and vari-
yser. The quality data was compared with ous types of pulp suspensions.
the image data to enable the information 2-D control methods: Using simu-
on quality contained in the images to be lated data, different algorithms were pro-
assessed. Meaningful comparison is based grammed in Matlab and connected to the
on the average cross-directional variation simulation program. The starting point
as the image, QCS and web analyser data was the existing actuator technology and
sets cannot be aligned point-wise. actuator-to-measurement delay. Simula-
High-resolution structural mea- tions covered different measurement and
surement: Measurements such as 1) sur- disturbance scenarios, and comparison
face topography measurement, 2) orienta- was based mainly on disturbance rejec-
tion analysis of surface fibres, and 3) pre- tion properties.
dicting mottling intensity, demand a high Surface chemistry: The research
image resolution (approx. 10 um pixel approach involved spectral measure-
size). The developed measurements can be ment of samples and statistical analysis
applied with scanning devices and in labo- of measurement results. A principal com-
ratories, but not yet with full web images. ponent analysis classifier was applied.
Rough-resolution structural mea- PCA based classifiers have shown their
surement: Formation, as the spatial ba- strength in classifying spectral type data
sis weight distribution of paper, affects a in many studies. The main objective and
variety of paper characteristics such as outcome was the ability to classify differ-
paper strength and printability. It can be ent ASA dosages into different classes.
partially controlled with available mea- Innovation of paper structure:
surements and actuators, but the present The goal was to search for new meth-
on-line formation measurements are lim- ods, tools, and practices for paper prod-
ited and current control methods do not uct design. The long-term results are in-
allow 2-D control. The research focused tended to improve the cost efficiency of
on 1) approaches for laboratory and on- product design and to offer new perspec-
line optical formation measurement, 2) tives for product development, which has
image-based characterization methods, been restricted by the current technolog-
and 3) possibilities for formation control. ical limitations of paper production pro-
The experiments were carried out using cesses. Computational methods and vir-

102

tual design environments could consider- data consisted of three elements:
ably help in customizing products with re- • Raw images at full resolution
spect to customer needs. Although cur- (0.83x0.83 mm) over 3 s (10 bit)
rent papermaking technology is not yet • Jpg images at full resolution
advanced enough to produce such cus- over 20 s
tomized papers, the setting of well-de- • Raw line images with resolution
fined targets for future production ma- 0.83 (CD) x 105 mm (MD) over 120 s;
chinery is of valuable benefit in itself. the line images were constructed
individually at each image processing
card as MD averages of single images.
The defect detection system has not
4. Results been designed for accessing web-wide
4.1 2-D web-wide variability transmittance maps. In order to produce
analyser the digital “illuminated table” application,
the following image correction operations
The 2-DVarA application study consists need to be carried out:
of the following three application compo- • Geometry and perspective
nents: correction to compensate for non-
• Digital “illuminated table” providing ideal camera alignment and lens
a digital web-wide image extending distortion: obtained by using
tens of meters in the machine machine directional streaks to
direction (MD) at submillimetre identify the correcting homography.
pixel resolution, enabling the user • Positioning the images: obtained
to freely choose the area of interest by first using information on the
and the magnification. camera arrangement to get a rough
• Medium-scale analyser of web order and then determining the
transmittance with a “pixel” image overlap with correlation.
resolution of less than 1 mm • Illumination affects: several
in the cross direction (CD) and approaches; illumination models,
approximately 100 mm in the subtracting the long-term average
machine direction (MD), and a image. None of these is fully
transmittance analysis range satisfactory for the intended
extending several kilometres in MD. application range. The illumination
• Continuous basis weight estimator models are not very accurate and
(servicing 2-D control) based on subtracting long-term images
transmittance measurement at removes stable streaks. The
millimetre resolution in CD, and 100 proper means of correcting for
to 5000 mm resolution in MD. illumination non-uniformity is with
an illumination calibration image,
As a basis for method development, which is straightforward to obtain
data was collected from a full-scale news- during a production break, but was
print machine. The data consisted of scan- not available during this study.
ner data from the quality control system • Stitching the images to a single
(QCS), paper samples cut across the ma- transmittance map: obtained with
chine reel and measured with an off-line multiresolution splining.
web analyser (Tapio), and transmittance
data collected from a commercial defect The current version of the digital “il-
detection system (Viconsys, 18 cameras luminated table” is available on the In-
across the machine). The transmittance ternet. The user chooses between the

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methods for illumination correction ac- newsprint there are several disturbanc-
cording to the features of interest. Pro- es to the basis weight vs. transmittance
ducing the application computationally dependency, most notably moisture and
is rather slow. filler content variations. To assess the
The medium-scale transmittance opportunities for fast basis weight esti-
variability analyser is based on line im- mation based on defect detection cam-
ages over several kilometres. Such im- eras and a scanner, the long-term aver-
ages provide novel information about age profiles from the scanner data, line
residual variations in the web and, thus, scan images and paper samples were
the new analysis methods concentrat- compared. The correlation is rather
ed on finding features with assignable poor; with proper CD filtering, a corre-
causes in residual variation. The imag- lation coefficient of 0.4 was found. How-
es revealed strong tilted waves that are ever, the following observations were
most probably due to fast consistency made:
variations entering the headbox; these • Within paper samples the
variations contributed over 70% of the correlation between transmittance
total transmittance variance. A method and basis weight was up to 0.9,
based on the directed antenna principle which means that filler content is
was constructed to extract tilted wave not the main cause of disturbance.
amplitude as a function of tilt angle and • The basis weight in the paper
to reconstruct the signal shape of the samples and in the QCS scanner
cause. The analysis revealed that more had a correlation of 0.72. The
than half of the MD variation estimated difference is expected to be at least
was actually an alias of the tilted waves. partly due to moisture variations,
Currently, methods based on feature de- and hence the basis weight
tection, 2-D spectral analysis and prin- estimator to be constructed should
ciple component analysis are being con- have moisture compensation based
structed in order to break residual varia- on the QCS scanner.
tion down into further components with • The QCS profiles were heavily
assignable causes. Variance component filtered and not accurately aligned
analysis has shown that there are fur- time-wise with the defect detection
ther structures in the residual variation, data or paper samples. The QCS
i.e. once the tilted waves have been re- profiles featured somewhat unstable
moved, and that the remaining compo- areas close to the edges, perhaps
nent is not white noise. Routine meth- due to the tilted waves.
ods for CD and MD analysis can be ap- • The correction for illumination
plied to the data as well. Studying the variations in images needs to be
CD profile of residual variance reveals improved. There appears to be
the camera structure: the method is larger deviation between basis
limited by the deficiencies of the meth- weight profiles and line image data
ods for compensation illumination varia- at the edges of individual camera
tion. The calibration image for illumina- areas.
tion is also expected to further enhance
opportunities in this area. On the basis of these observations,
If the transmittance map could be the development of a basis weight esti-
converted into a basis weight estimate mator that combines scanner measure-
at line image resolution, basis weight ments and transmittance maps should
control would no longer be limited by be pursued further. Correcting the illumi-
QCS scanner speed. However, even in nation and using scanner data to adapt

104

the model between transmittance, basis been applied to the computation of gradi-
weight, and moisture are the next devel- ents. The surface is interpreted from the
opment steps. Estimation is of particu- gradients. With the device, samples have
lar interest when identifying the CD actu- been measured and different combina-
ator responses: the shape identification tions of lights have been compared. Initial
is rather uncertain with scanner data on- data analysis results confirm that more
ly, but could be radically improved with lights produce a better surface estimate,
transmittance data, whereas the gain es- but the overall difference is small. The re-
timation can be carried out reliably based sult is positive for on-line measurement
on the scanner. development where the number of lights
will always be limited. The data analysis
is still in the initial stages, but numerous
4.2 High-resolution structural possibilities lay ahead for method devel-
measurement opment and for comparison of the results
The application topic QFine is developing with different paper types.
the following three measurement meth- As regards orientation measurement,
ods: different approaches to surface fibre ori-
• Surface topography measurement. entation analysis using different types of
• Orientation measurement of surface images have been investigated: 1) the
fibres. traditional image gradients method has
• Optical mottling analysis. been studied and applied, 2) the 2-D
spectrum method has been tested, 3) a
Paper samples have been collected in new method that uses wavelets to char-
order to compare different methods of pa- acterize surface orientation has been de-
per surface measurement and to compare veloped (a description of this innovation
the samples with the surface achieved by has been submitted by Matti Lassas, Jou-
tomography. The samples are kept for ni Takalo, Jouni Sampo, Samuli Siltanen,
future measurements and all data mea- and Jussi Timonen), and 4) a new meth-
sured from the samples is archived to- od for orientation measurement using
gether with the samples. scale invariant feature transform (SIFT)
In the area of surface topography, the has been tested. It has become clear that
intention has been to develop the photo- the lighting arrangement for imaging is a
metric stereo based method (also called crucial factor when measuring surface ori-
shape from shading). A new testing ap- entation. Different lighting arrangements
paratus for laboratory measurements has have therefore also been tested along
been built. The device is based on a ro- with different computational methods. We
tating stand with led lights and a DSLR have used: 1) transmittance images, 2)
camera. The device enables testing and dark field lighting, and 3) light series as
analysis of a large number of images with used in topography measurement. All of
known lighting angles. The surface gradi- these methods have given similar results
ents and albedo can be computed from with the same paper samples, although
multi-light measurements. When the sur- some lighting-dependent computational
face is Lambertian (totally mat), the for- tricks can be used. The results indicate
mula simplifies, fitting three parametric that, when used within reason, there is
linear models to each image pixel . Al- virtually no difference between the light-
though it is expected that surface gra- ing methods.
dients can be computed more accurate- Work has also been carried out to pro-
ly with more images, three images is suf- duce a reliable map of surface orientation
ficient in principle. Some new ideas have distribution. Here, the axial distribution

105

of the fibre orientation requires conver- • Laboratory imaging experiments of
sion into a standard-type distribution by different paper samples with front
doubling the angles. This is because the (reflection) and back illumination
orientation and anisotropy parameters of (transmission): Experiments with
standard distributions are compatible with different illumination options
simple filtering analysis, which is need- showed that frontal dark-field
ed for the formation of orientation maps. illumination emphasizes the
The mottling printing defect is caused surface details and, depending
by either inconsistent raster dot ink on the spatial resolution, makes
spread or dot gain variation. The latter is surface orientation analysis
an optical phenomenon explained by the possible. The future of rough-
distribution of light at the borders of the resolution characterization of paper
raster dots where variation can be caused lies in combining reflection and
by variation in the paper structure. A pat- transmission data.
ented method exists for the measurement • Image pre-processing methods for
of optical mottling without the use of ink. formation images for laboratory
The patent describes a 50x50µm chess- and on-line use: To use camera-
board image on a transparency. We have based transmission images with
tested the printed transparency, but so global image analysis methods,
far no reliable results have been obtained uneven image illumination has to
because the method requires very close be corrected. Several methods are
contact between the transparency and available to model the illumination
the entire paper surface, which has so field and correct the uneven
far not been achieved. We have also de- illumination. Similarly, the periodic
vised a projector that is able to produce a structure of the wire affects the
30x30µm chessboard image which should analysis of the transmission images.
show similar variation effects on the un- The periodic signal is commonly
even paper structure. The projector has removed by using frequency-
yet to be tested. domain filtering (cf. de-screening of
raster print images).
• Image restoration method for
4.3 Rough-resolution structural optical transmission images: X-ray
measurement transmission maps are thought
The QRough application development to reveal the true mass density
task focused on providing 1) ideal opti- variation in paper. However,
cal formation measurement for on-line x-ray measurements can not be
use, 2) knowledge of the connections performed on-line, or even off-
between optical formation and control- line for large paper samples. In the
lable variables, 3) profiles of selected study, prior information in the form
characteristics for early warnings for of an edge spread function was
raw materials and process chemistry, used as the basis for deconvolving
and 4) improved possibilities to con- the actual variation based on optical
trol and handle problems related to fi- measurements.
bre raw material and/or chemical state • Feature-based image registration
of the process. method: To combine image
The research work during QVision information from multiple sources
(EffTech) concerning rough-resolution with possibly different modalities,
structural measurement produced the fol- image alignment is needed. A
lowing results: registration method based on image

106

features was developed for coarse tion camera much better images could be
and fine image alignment, and it obtained. Better images are needed for
was tested with pulp sheet images automated particle and fibre detection
with dirt particles. and analysis.
• Implementations of standard The image analysis of the polarized
formation characterization light method for dirt counting was devel-
methods: The standard ways to oped and largely automated. The meth-
characterize the variation include od’s remaining bottleneck is image acqui-
1st-order statistics such as standard sition. The samples presently used con-
deviation, specific formation, and sist of conventional microscope slides. The
the coefficient of variation. In method needs to be implemented in a flow
addition, the methods arising from cell arrangement to make it fast enough to
image processing, starting from gather statistically significant data.
specific perimeter and micro scale, One part of this study focussed on
were implemented as the baseline dirt counting and characterization of dirt
methods for further development. particles in pulp sheets. Two segmenta-
• Initial experiments with Testaa tion methods, which can adapt to differ-
1 data (SUORA, 25.-29.8.2008, ent backgrounds and uniformity, are pro-
VTT Jyväskylä): The data consists posed to overcome the majority of im-
of process data from Metso DNA age analysis problems of current systems
and transmission images from a (Panjeh Fouladgaran 2010b). Future work
single Viconsys camera. Despite its includes field testing of the methods with
limitations (averaging of process a more representative set of pulp sam-
data and limited synchronization ples, and the combined use of reflection
accuracy), the data was used for and transmissions images for feature ex-
method development, particularly traction.
methods for data synchronization The initial tests show that spec-
and pre-processing of images. tral and fluorescent imaging could have
• Possible approaches to formation high potential in particle and fibre analy-
control: One direction for the sis. Samples from different stages of the
development of formation (and pulp mill have significance differences in
orientation) control is to imitate the first three principal components. It
present scanner-based controls should be studied whether these differ-
using headbox jet flow and ences have any correlation, for example,
flocculation chemical addition as with the progress of pulp bleaching in the
manipulated variables. Faster different bleaching stages. If so, this in-
variations would be identified using formation could be utilized in bleaching
diagnostics methods. More research control. It was also shown that different
on using image data and actuator types of particles can be distinguished by
studies are still needed. their spectra. This could be a major ben-
efit in particle classification.

4.4 Particle and fibre analysis
It was shown that with a simple imaging 4.5 2-D control methods
system, consisting of a CCD camera and This feasibility study aims at evaluating
stroboscope light source, fairly good im- the technical feasibility and studying the
ages can be obtained from flowing pulp potential of 2-D control of the paper web
even at high consistencies. It is clear that based on improved resolution transmit-
with better lighting and a higher resolu- tance measurement and combining this

107

with existing scanner measurements. The 2-D controller worked well in all
This analysis of improvement potential simulated disturbance scenarios, includ-
starts from the existing actuator technol- ing tilted CD profiles and sharp chang-
ogy and actuator-to-measurement delay. es in cross direction. The 2-D controller
The work reported here covers the test- performed at least as well in attenuating
ing of different 2-D control schemes com- steady-state disturbances. In the distur-
bined with different measurement scenar- bance scenario with dynamically changing
ios using simulation. Comparison is based CD profiles, the 2-D controller performed
mainly on disturbance rejection properties better than the reference controller. The
(minimum variance control). difference between the performances is
New measurement capabilities based modest, but statistically significant. The
on paper machine fault detection sys- disturbances simulated in this compara-
tem images provide virtually continuous tive study are slowly generating. The dif-
estimates also of quality variables such ference is emphasized when faster vari-
as basis weight. The new measurement ations are simulated. The simulations
technologies also enable observation of show that even with nominal tuning, the
cross-direction (CD) actuator dynamics 2-D controller can attenuate disturbanc-
and the control interval to be decreased es over a wide frequency range.
to seconds. Predictive controllers are re- The 2-D controller seems usable, at
quired to deal with the dead time. The least in the simulation environment. Fur-
challenge is to perform control calcula- ther simulations with more comprehen-
tions fast enough to meet real-time re- sive disturbance scenarios should, how-
quirements. ever, be made. Most web forming con-
In this case, the CD process, i.e. the trollers use filtering methods that reduce
actuator input-output relationship, is de- the dimensions of the problem. Such fil-
scribed with a non-square interaction ma- ters will be applied and tested later with
trix. The number of measurement loca- the 2-D controller.
tions is much higher than the number
of actuators. The scanner is assumed to
move at a constant speed of 25 cm/s and 4.6 Surface chemistry
it takes one additional second to complete The main focus of the surface chemistry
the turn at the edge of the web. As the task was to study a Kemira case to find a
simulated web dimensions in CD and MD reliable and quick off-line method for ASA
are 400 cm and 1000 s, respectively, the application using IR spectroscopy. For
total scan time is thus 17 s. There are 67 these purposes, a sample set of 75 lab-
CD actuators, which are assumed to be oratory-made handsheets were obtained
dilution valves. The dynamic responses of by Kemira. The sample set contained
these actuators are described by a first three different pulp groups of varying fur-
order plus delay model, in which each ac- nish and filler content, these were: 100%
tuator is assumed to have the same dy- chemical pulp (50% birch + 50% pine),
namic response. In the chosen 2-D con- 30% chemical pulp (50% birch + 50%
troller, a linear optimal controller is used pine) + 70% mechanical pulp, and 30%
to calculate the steady-state control ac- chemical pulp (50% birch + 50% pine)
tions and a predictive controller controls a + 70% mechanical pulp + PCC. Each of
part of the residual variation. The perfor- the three groups contained 5 different
mance of the 2-D controller is compared ASA dosages: 0 kg/t, 0.5 kg/t, 1 kg/t,
to a conventional model predictive con- 3 kg/t and 5 kg/t. Five parallel sheets of
troller. The implementation is made with each type were used (total sheet number
Matlab’s Model Predictive Toolbox®. 3 x 5 x 5 = 75). Spectral measurements

108

were made with a scanning type spectro- Good sizing is essential for certain pa-
photometer equipped with an integrating per and board grades (e.g. liquid pack-
sphere. The measurements were made aging board). If sizing is not successful,
with 0/d geometry in the wavelength the product may be rendered useless
range 200 nm to 2500 nm with a 5 nm with respect to the intended end prod-
interval. All samples were measured on uct. The current off-line and laboratory
both sides. The results showed the spec- test methods are slow, and thus distur-
tral shapes to differ between different fur- bances in sizing are not observed early
nish and filler groups, so groups are easi- enough. This results in wasted produc-
ly classified with a few wavelengths. Con- tion and – in the worst cases – custom-
versely, the spectral shapes within each er claims. A reliable on-line method for
furnish and filler class were highly simi- measurement of sizing would thus be
lar irrespective of the ASA dosage. Sta- of great value. One essential publication
tistical classification methods are there- was found: Martorana E., Fischer S., Kl-
fore needed. The PCA classification meth- eemann S., Quantitative analysis of syn-
od was also tested at a number of dif- thetic sizing agents (ASA/AKD) using
ferent wavelength ranges. The results of NIR spectroscopy,” Nordic Pulp and Pa-
the classification using PCA with subspace per Research Journal 24, 2009.
dimension 7 are shown in Table 1. Each
group was classified separately. A wave-
length range from 1600 nm to 2300 nm 4.7 Innovation of paper structure
with a 5 nm interval was used for the Our research goal was to explore novel
classification. Due to the small number methods for the design of tailored paper
of spectra in each class, the classification products. During the course of the QVi-
was made using the leave one out meth- sion programme we have completed the
od. According to the method, one spec- specification and demonstration phas-
trum is classified and the other spectra es of our long-term project. We have re-
are used for training the classifier. The re- searched and developed design meth-
sults are very promising. ods which help create new tailored pa-
However, further study related to per products optimized with respect to
PCA analysis is needed to confirm the material costs and paper quality. These
optimal dimension of the basis vec- conflicting demands lead to formulation
tors and the best wavelength ranges. of multiobjective optimization problems,

Table 1. Classification results using PCA, subspace dimension 7. C1 to C5
corresponds to ASA dosages 0kg/t, 0.5kg/t, 1kg/t, 3kg/t and 5kg/t, respectively.

Chemical
pulp
Chemical
pulp
+
Chemical
pulp
+

mechanical
pulp
mechanical
pulp
+
PCC

C1
C2
C3
C4
C5

C1
C2
C3
C4
C5

C1
C2
C3
C4
C5

C1

10

10
1

10
1

C2

9
1

9

9

C3

1
8

10

10

C4

1
10

10

10

C5

10

10

10

109

which primarily draw upon such paper objectives and constraints for the
quality measures as spatial basis weight optimization procedure,
distribution, tensile strength, bending 3. Checking the physical model
stiffness, brightness and opacity, which parameters,
are described by mechanical and optical 4. Performing the optimization,
models as well as by statistical distribu- 5. Evaluating and displaying the
tions and simulation models. results, and
We report the project’s results in the 6. Altering the optimization settings
form of the Paperrin 1.0 demonstration and repeating the optimization
tool. The tool enables the optimization of process until the desired paper
paper structures with respect to materi- structure is achieved.
al costs while maintaining desired quality We have devised three real-life prac-
measures. We have specifically pledged tical scenarios of paper structure de-
in-programme support for a multitude of sign in cooperation with paper industry
essential physical paper characteristics professionals. The scenarios are intend-
to be used for multiobjective optimiza- ed to provide us with guidance through
tion purposes. The Paperrin tool produc- the planning, implementation and testing
es plausible optimization results which are phases of our research.
still to be verified physically.
All models used in Paperrin are im-
plemented with the Numerrin 4 model-
ling language developed by Numero-
la. Multiobjective optimization problems development needs
are solved using an SQP solver and the
weighted sum method. The EffNet WP 7 project will continue the
The Paperrin tool allows the user to work initiated in the QVision project un-
set optimization problem objectives and der EffTech. The objective of WP 7 is to
constraints as inputs. The problem solu- provide means for managing the unifor-
tion output resembles a composition of mity of web material at the macro scale,
paper layers and their constituents. Users in particular the continuous over-time and
are encouraged to experiment with avail- machine-wide development of bulk and
able inputs and settings to see their result- surface microstructure. Until very recent-
ing impact on the paper quality properties. ly, wide ranges of variability have been
The Paperrin tool’s main tab con- wholly unobservable in production. These
tains parameter input fields, certain pa- are now accounted for, largely due to QVi-
per composite property fields and output sion. The goal is to characterize and man-
fields for physical magnitudes character- age the web at the following scales:
izing the paper structure as a whole as • Sub-formation scales of surfaces
well as its individual layers. Certain other affecting printing; mottling effects,
input parameters (such as elastic modu- deep surface pores in uncoated
lus dependency) are presented on a sep- surfaces
arate ‘Model properties’ tab. The tool’s in- • Fast web-wide temporal structures
put fields are used to launch the simula- (residual variation at a resolution of
tion, which produces outputs in either nu- 10 cm to 1 m in machine direction
merical or graphical format. and 1 mm in cross direction)
The application’s default work flow in- • Web-wide structures at high
cludes the following operational phases: resolution (sub mm)
1. Understanding the requirements of • Formation scale structure, including
the new paper product, 2. Defining fibre orientation

110

• Slow web-wide temporal structures al distribution of paper based on its opti-
(MD and CD profiles) cal transmission.
The characterization will be based on Rough-resolution structural mea-
digital imaging, which has been the most surement: The produced results will be
rapidly developing area of electronics over used in EffNet. The available measure-
the last decade. Inference based on imag- ment, processing, analysis, and control
es will be supported by advanced use of methods, as well as experiences with the
structural models and other prior informa- Testaa 1 data will be used to plan and im-
tion according to the principle of inverse plement future experiments in order to
and Bayesian methods. The management obtain appropriate data.
of uniformity will consist of a combination Particle and fibre analysis: The re-
of feedback control and diagnostics. search started in QVision will be contin-
2-D web-wide variability analyser: ued in the PulpVision project, which con-
work will be continued under the EffNet sists of four parallel Tekes ERDF projects.
programme as indicated above. Further- The next development steps will include:
more, outside the programme, the inte- 1) Field tests of image analysis methods
gration of the Viconsys defect detection with a more representative set of pulp
imaging system and QCS systems so that samples, and combined use of reflection
the functionalities developed can be com- and transmissions images for feature ex-
mercialized on an appropriate platform. traction. 2) Implementation of spectral
It is also assumed that commercialization and fluorescent imaging results in image
of some functionalities will be carried out analysis. 3) Testing image analysis meth-
by SMEs. ods with images obtained from pulp sus-
High-resolution structural mea- pensions. 4) Further development of im-
surement: The produced data will be aging systems for pulp suspensions.
further analyzed in EffNet. 1) Surface to- 2-D control methods: The research
pology and 2) Surface fibre orientation: continues as a doctorate thesis and in the
the developed multi-light measurement EffNet programme. New algorithms and
device will be extensively used to test, disturbance scenarios will be tested with
analyze and further develop the lighting simulations. The performance of 2-D con-
setup, imaging methods, computational trol of residual variations, integrated with
methods and image noise suppression. 3) current CD and MD controls, will be ana-
Optical dot-gain variation: testing of the lyzed with current actuator systems (e.g.
printed transparent method will contin- dilution headbox) and possibilities for
ue, as will testing of projected patterned faster actuators will be studied. The ben-
light for printability analysis. The compar- efits of continuous full-web imaging, such
ison of tomographic data (from x-ray and as accurate actuator response identifica-
optical coherence) against measured sur- tion, web shrinkage estimation, and re-
face topography and surface fibre orien- duced uncertainty in variation estimates,
tation will continue. Methods and setups will be integrated into the 2-D control
will be further arranged for multi-spec- concept.
tral imaging for high resolution structural Innovation of paper structure: Fur-
measurements. ther steps of the project include devel-
As a collaboration between high and opment of the optical model in cooper-
rough-resolution structural measurement, ation with optics research groups par-
the development of methods to compute ticipating in the EffNet programme. The
fibre orientation from optical transmission model needs to be improved with regard
and reflectance images is being contin- to physical practicality while maintaining
ued. The aim is to determine the materi- current computational efficiency. Also, the

111

mechanical model is to be enhanced via out by defect detection system vendors.
utilization of our recently developed two- High-resolution structural mea-
dimensional treatment instead of point- surement: The produced data will be fur-
wise simulations. The specifications pro- ther analyzed in EffNet. Methods related
duced within the framework of the QVi- to surface topology, surface fibre orien-
sion project will be utilized as guidelines tation, and optical dot gain variation will
for further practical development work. be developed further. Tomographic data
Our featured modelling methods can be (from x-ray and optical coherence) will
also used for modelling and testing fibre- be used as the reference for optical mea-
based materials developed by other Eff- surements. Spectral imaging will also be
Tech participants. evaluated further.
Rough-resolution structural mea-
surement: The produced results will
be used in EffNet. The available mea-
6. Exploitation plan and surement, processing, analysis and con-
impact of results trol methods will be used to plan and im-
plement future test runs to collect ap-
2-D web-wide variability analyser: Of propriate process data and test control
the three sub-applications of the 2-D vari- schemes. In their current stage, the re-
ability analyser, the digital illuminated ta- sults are not directly applicable to indus-
ble has been demonstrated and is ready trial processes. The feature-based image
for the product development phase. The registration method will be further devel-
analysis of 2-D transmittance variation oped and applied at least to dirt counting
over several kilometres in the machine di- and classification.
rection needs further refinement as well Particle and fibre analysis: The
as test cases, such as identification of the project involves co-operation between
shape of CD actuator response. This will four research groups in testing, imaging
be included in the research tasks of the and machine vision techniques in differ-
EffNet programme. Estimation of 2-D ba- ent practical cases using different pulp
sis weight variation based on transmit- and paper samples. The studies will be
tance maps and scanning basis weight continued under the large-scale four-year
measurement requires further research. Tekes/ERDF project PulpVision. The Pulp-
This research, also included in the Eff- Vision project works to develop new im-
Net programme, is strongly connected to aging and machine vision based measure-
developing 2-D control applications (see ments for use in the analysis and control
below) which addresses the questions of of wet-end pulp and paper making pro-
which variables should be controlled and cesses. The project involves eight partic-
whether different target variables should ipating companies, mainly SMEs.
be applied at different frequency rang- 2-D control methods: The research
es. Essential to all exploitation avenues continues under the EffNet programme.
is the need for more uniform illumination The benefits of continuous full-web imag-
in defect detection systems or an effec- ing, such as accurate actuator response
tive way of compensating computational- identification, web shrinkage estimation,
ly for variations in illumination. The latter and reduced uncertainty in variation es-
is expected to be relatively straightfor- timates, will be integrated with the 2-D
ward with appropriate calibration imaging control concept.
which, however, was not available during Surface chemistry: Industrial inter-
QVision. The former is a more long-term est is focused on ASA dosage measure-
development issue and should be carried ment and analysis. The results closely

112

meet the objectives of the QVision proj- Panjeh Foulagaran M. (2010a). “Imag-
ect’s surface chemistry task. ing and Characterisation of Dirt Particles
Innovation of paper structure: The in Pulp and Paper,” M.Sc. thesis, Lappeen-
produced results are directly exploitable ranta University of Technology.
in the production of design and research
tools for new optimized multilayer paper Panjeh Fouladgaran M., Mankki A.,
products. The end users of the results are Lensu L., Käyhkö J., Kälviäinen H.
R&D personnel in the paper and board in- (2010b). “Automated Counting and Char-
dustry and their equipment and raw ma- acterization of Dirt Particles in Pulp,” In-
terial suppliers. ternational Conference on Computer Vi-
sion and Graphics (ICCVG 2010), 20–22
Sep 2010, Warsaw, Poland.

7. Publications and Raunio J.-P., Tirronen V., Ritala R.,
reports Nironen I., Rossi R., Kärkkäinen T.
(2010a). “Web-Wide Diagnostics of Paper
Kälviäinen H. (2010a). “Image Print Properties based on Fault Detector System
Quality Assessment by Machine Vision”, Images”, TAPPI PaperCon 2010, 23rd Pro-
Sino-foreign-interchange Workshop on cess Industry Reliability and Maintenance
Intelligence Science and Intelligent Da- Conference, 2–5 May 2010, Atlanta, GA.
ta Engineering (IScIDE 2010), 3–6 Jun
2010, Harbin, China. Invited talk. Raunio J.-P., Tirronen V., Ritala R.,
Nironen I. (2010b). “Web-wide diagnos-
Kälviäinen H. (2010b). “Machine vision tic of paper: utilization of light transmit-
based quality control from pulping to pa- tance images in analysis of paper proper-
permaking for printing”, 10th Internation- ties”, Control Systems 2010, September
al Conference on Pattern Recognition and 2010, Stockholm, Sweden.
Image Analysis (PRIA-20-2010), St. Pe-
tersburg, Russian Federation. Invited talk. Takalo J., Timonen J., Sampo J., Silt-
anen S., Lassas M. (2010a). “Wavelet-
Ohenoja M. (2010a). “Application feasi- based inverse method as a tool in paper
bility study of 2D control methods”, Re- quality assessment”, Physics Days 2010,
port series A, Control Engineering Labo- 11–13 March 2010, Jyväskylä, Finland.
ratory, University of Oulu. Poster presentation.

Ohenoja M., Isokangas A., Leiviskä K. Takalo J., Timonen J., Sampo J., Silt-
(2010b). “Simulation studies of paper anen S., Lassas M. (2010b). “Wavelet-
machine basis weight control”, Report based inverse method as a tool in paper
series A, Control Engineering Laboratory, quality assessment”, Inverse Problems:
University of Oulu. Modeling & Simulation, 24–29 May 2010,
Antalya, Turkey. Invited talk.
Ohenoja M., Ylisaari J., Leiviskä K.,
Ritala, R. (2010c). “Analyzing 2-Dimen- Ylisaari J., Ritala R. (2010). “Web-wide
sional Variation Based on Scanning and transmittance imaging measurement vari-
Imaging Measurements”, TAPPI Paper- ability analysis”, Control Systems 2010,
Con 2010, 23rd Process Industry Reliabil- September 2010, Stockholm, Sweden
ity and Maintenance Conference, 2–5 May
2010, Atlanta, GA.

113

Re-engineering paper
(REP)

Project Manager Erkki Hellén, Erkki.Hellen@vtt.fi

Duration of the project 1.6.2008-30.8.2010



Biosafe – Special Laboratory Safety assessment of materials and products used and
Services Ltd, (Atte von Wright) generated in the project using in vitro toxicity tests.

FPInnovations, Canada Development of numerical tools to simulate the forma-
(Tetsu Uesaka) tion of nano-scale network structures under different
process conditions.

Aalto University, Complex Simulation of aggregation dynamics of filler particles in
Systems and Materials group liquid or nanofibre suspension. Calculation of mechanical
(Mikko Alava) properties of structures formed from aggregates.

University of Helsinki, Structural characterization of materials and products
Department of Physics using X-ray methods.
(Ritva Serimaa)

University of Helsinki, Development of methods to estimate the optical
Observatory (Kari Lumme) properties of simulated structures including cellulose
nanofibrils. Packing simulations of filler aggregates.

Tampere University of Development of atomic, molecular and coarse-grained
Technology, Biological models for nanocellulose and studying its interactions
Physics and Soft Matter group with inorganic particles.
(Ilpo Vattulainen)

VTT Technical Research Centre Coordination of the project and 1) production and
of Finland (Erkki Hellén); also characterization of materials and structures, 2)
includes the former KCL role coordination of modelling efforts and modelling of
strength and rheological properties of fibre networks
with nanocellulose, 3) significant experimental
contribution, especially providing data for modelling
purposes and demonstration of new product and process
concepts, 4) analysis of sustainability and safety of new
materials, process concepts and products.

114

Abstract
The Re-engineering paper (REP) project studies technologies to enable resource-efficient and
sustainable renewal of fibre-based products. The focus is on the potential of nanofibrillated
cellulose (NFC) in 1) pure NFC, 2) filler-NFC, and 3) fibre-NFC structures. The project has iden-
tified and demonstrated several product and process concepts which utilize cellulose nano-
fibres and show new combinations of characteristics, and screened their environmental as-
pects. New laboratory-scale facilities have been established (manufacturing, fractionation and
safety of nanocelluloses; production of controlled sheet structures; characterization of nano-
celluloses and structures). The importance of both nanocellulose quality and process condi-
tions with respect to sheet structures has been shown. State-of-the-art simulation tools for
multi-scale modelling have been developed in a network of five top research teams and inte-
grated in the Simantics modelling and simulation environment. The safety of nanocelluloses
has been assessed using in vitro toxicity tests.
Keywords: nanocellulose, papermaking, simulation, process concept, resource efficiency

115

1. Project background o enables radical reductions in
the consumption of raw
Cellulose nanofibres show great poten- materials, water and energy in
tial in expanding the use of sustainable the production process
raw materials in the forest products in- o leads to new product.
dustry. They allow paper and board prod- • advanced multi-scale models, which
ucts to be produced with much lower con- o help in identifying the potential
sumption of raw materials, water and en- of new materials
ergy. They can also be used to develop o enhance product development
completely new fibre-based products with o guide process development
characteristics that cannot be achieved
with present-day raw materials. Short term goals (2 years, till
Making optimal use of nanomateri- 06/2010):
als requires an overall picture of how the • To select and test the most feasible
characteristics of the end product are in- new materials and production
fluenced by the formation and dewatering technologies with respect to
mechanisms containing these new mate- resource efficiency
rials. Finding ways to engineer products • Demonstrate paper-like structures,
based on novel raw materials demands which
a profound understanding of the interac- o are based on new nano- and
tions between them. In order to speed up biomaterials,
product and process development and to o offer completely new
reduce costs and risks, we need virtual combinations of characteristics
product models which take into account • Identify techniques required to
the properties of new nanomaterials and characterize nanomaterials and the
other essential structural components. structures containing them
Measurements of material properties and • Produce structures containing
well-controlled laboratory and pilot trials nanoparticles in a controlled way
represent an important part of this chain. • Demonstrate a multi-scale model
Sustainability and product safety are oth- for paper-like structures containing
er important considerations when choos- nanocellulose and apply it to
ing between the available options. solving a case problem defined by
experiments
• Screen for environmental and safety
effects of promising new materials
2. Project objectives and production technologies to
The REP project aims at the renewal of guide the project in a sustainable
paper and board making with cellulose direction
nanofibres. The long-term target of the
project is to develop
• a resource-efficient technology for
nanofibre-based sheet production
that is
o economically profitable
o complies with sustainability
requirements

116

3. Research approach been on new products and processes,
particularly on forming structures with
The Re-engineering paper (REP) project novel physical properties. Coating appli-
is built around the belief that a very im- cations and applications of cellulose nano-
portant category of future forest products fibres in current papermaking processes
will be produced from renewable wood- have been excluded.
based raw materials in reel-to-reel oper- REP has concentrated on laboratory-
ations. These future “paper” products will scale demonstrations of products contain-
have a greatly expanded property space ing nano-fibrillated cellulose, screening of
compared to today’s products and will potential resource-efficient technologies,
thus compete in entirely new markets. and starting the development of a virtu-
This transformation is driven by the rapid al product modelling environment. Sever-
developments in renewable material sci- al potential product concepts and efficient
ence and will require a completely new processes have been identified and dem-
manufacturing platform to draw on. onstrated. A demo of the virtual product
To meet these targets, the REP proj- environment has been carried out. Envi-
ect has explored the possibilities offered ronmental and safety screening indicat-
by cellulose nanofibres. Figure 1 illus- ed no major concerns. The next step is
trates the main ideology of the project. to continue up-scaling of the most po-
The project has concentrated on web- tential technologies and show how nano-
based products and processes. Experi- celluloses together with these technolo-
ments have been intentionally limited to gies lead to extended properties for fibre-
the laboratory scale. The emphasis has based products.

Figure 1. The Re-engineering paper (REP) project aims at the renewal of paper
and board making using cellulose nanofibres. This requires rethinking of existing
production processes but offers possibilities for new, high-value products.

117

4. Results size fractions. The largest fibre fragments
were removed during fractionation and
the fibril size, both length and width, de-
4.1 Facilities to make and creased as the fractionation proceeded.
fractionate nanofibrillated
celluloses
Controlled production of NFC at the lab- 4.2 Characterization of
oratory scale has been established. The nanocelluloses requires advanced
nanofibrillated materials were produced methods
with a Masuko grinder. The effect of dif- Nanocellulose is a novel raw material re-
ferent process parameters on nanofibril quiring different characterization meth-
production was evaluated and the repro- ods than ordinary wood fibres. Figure 2
ducibility of the process was verified in illustrates the methods used to charac-
terms of energy consumption and end terize nanocelluloses and structures con-
product quality. The production rate of taining them. Table 1 summarizes the sta-
the grinder is about 640 g/h (dry materi- tus of the characterizations methods. In
al) for 1 pass of NFC and about 145 g/h conclusion, several methods need to be
(dry material) for 6 passes of NFC. used to characterize NFC. Aspect ratio,
Mechanical fractionation devices were degree of fibrillation, fibril size and the
constructed at VTT. They can be used for amount of unfibrillated material can be
fractionation of different fibre/particle evaluated with a combination of viscosi-
suspensions in the particle size range of ty, transmittance (or turbidity) and SEM
0.1–150 micrometers. The devices were measurements. Viscosity measurement is
used to fractionate VTT Masuko ground sensitive to small fibrils, whereas trans-
1-pass and 6-pass suspensions to five mittance/turbidity gives an estimation of

Figure 2. Main characterization methods tested.

118

the amount of larger particles. The phys- tion on nanocellulose quality, they can-
ical properties of NFC sheets also provid- not be used to calculate actual NFC prop-
ed additional information. The crystalline erties such as length or thickness. More-
structure, nano-porosity and specific sur- over, methods capable of rapidly deter-
face area of NFC materials can be ana- mining NFC quality in process conditions
lyzed with delicate measuring techniques are needed.
such as x-ray microtomography, x-ray dif-
fraction, and wide-angle and small-angle
x-ray scattering techniques. 4.3 Safety of nanocelluloses
However, there are still challenges, Nanocelluloses have many potential appli-
mainly due to the intrinsic nature of NFC. cations but are subject to the same safe-
The very wide size range together with ty concerns as other nanomaterials. As
the fibrillated shape makes it difficult to with other nanomaterials, the eventual bi-
determine the actual particle size. This ological effects cannot be predicted sole-
is further complicated by the branching ly from the chemical nature of cellulose.
of fibrils. Nanofibrillated celluloses also The size, shape, aggregation properties,
flocculate very readily and dispersing of among others, still poorly understood fac-
NFC material prior to measurement is es- tors, may affect the interaction of nano-
sential. Although indirect measurements cellulose particles with cells and living or-
(such as viscosity) give valuable informa- ganisms. A literature review showed that

Table 1. Preferable measurement techniques for NFC characterization.
Red indicates methods that are important for NFC quality control and blue
indicates methods still under development.

Property Method
Preferable Best alternative Second alternative
Fibril width AFM, image analysis TEM, image analysis
Fibril length SEM
Hydrodynamic radius SEM, image analysis Nanosight Photon correlation
spectroscopy
Aspect ratio Viscosity Microscopy methods
Amount of unfibrillated Transmittance, Light microscopy, Luukko method,
fibres Turbidity image analysis Fractionator analysis
Size of fines and fibre Fractionator analysis Light microscopy SEM, Fractionator
fragments analysis
Crystallinity % WAXS XRD
Crystallinity size WAXS/ width, length XRD/ width, length
Porosity SAXS/ nano scale
Specific surface area SAXS Fysisorption / BET
Gel point Viscosity
Water retention Sedimentation volume WRV
Stability in dispersion Sedimentation volume Settling rate
Surface characterization AFM / nano-scale SEM / qualitative
roughness

119

only a few studies on the safety of nano- and to identify the actual cause of mor-
celluloses have been published. phological changes.
The safety of nanocelluloses was as-
sessed using in vitro bioassays. A new
testing procedure for analyzing cyto- and 4.4 Nanocellulose characteristics
genotoxicological properties of nanocellu- determine product properties
loses was developed. Immediate cytotox- The effect of NFC on sheet properties was
icity of nanocelluloses and their sub-lethal demonstrated by mixing various amounts
effects on cultured human cells as well as of nanocelluloses with two types of fibre
their ability to damage DNA or chromo- commonly used in papermaking (birch
somes were studied. kraft and TMP). NFC clearly increases the
The NFC samples tested can be con- tensile index, the maximum of which is
sidered non-toxic (see Table 2). The pure generally a function of NFC content. There
nanocelluloses did not show any cytotox- are clear differences between different
ic or genotoxic effects. The only indica- nanocelluloses. The most dramatic prop-
tions of toxicity were found for the small- erty change was measured for air perme-
est size fractions, which showed an indi- ability, which decreased by two orders of
cation of transient morphological chang- magnitude at less than 15% NFC content.
es in human cervix carcinoma (HeLa229) As Figure 3 shows, the mechanical
cells in Highest Tolerated Dose (HTD) properties of films made exclusively of
testing. These samples were highly con- NFC depend strongly on the NFC type:
centrated and even in this case the mor- it is possible to simultaneously increase
phological changes were not severe. More both stretch and strength with the right
tests will be needed if the finest particles selection of NFC. The tensile index val-
are to be applied in high concentrations ues for the Daicel G NFC material are al-

Table 2. Summary of the results from the cytotoxicity and genotoxicity
tests. Some of the samples (marked as –) were not tested or they were
not microbially clean enough for reliable testing.

120

Figure 3. Mechanical properties of NFC films depend strongly on NFC
quality. Blue diamonds indicate tensile index values.

Table 3. Main characteristics of nanocelluloses.

121

Figure 4. Roughness and dimensional stability of filler-nanocellulose
composites is significantly better than for paper and comparable to
plastic substrates used in electronic printing.

most twice as high as for films made of aqueous solutions. Paper-like, opaque
NFC 100-5. The stretch (over 20% for the structures result when nanocellulose films
best case) and TEA index values are al- are treated with ethanol.
so high. The mechanical properties of VTT The solvent also affects the struc-
NFC materials are close to those of Dai- ture of nanocelluloses. For example, the
cel NFC materials. When comparing these specific surface area of commercial NFC
results with the properties of nanocellu- MF40-100 was 6.4 m2/g in dry powder,
loses (Table 3), the best strength values 180 m2/g in ethanol and 660 m2/g in wa-
are obtained with long fibrils with high ter. Surprisingly, the NFC films showed
enough aspect ratio and high enough nanometre range porosity only when
branched structure. formed in an ethanol suspension. Ethanol
also increased the micrometer and nano-
metre scale porosity of dry sheets.
4.5 Product properties influenced
strongly by process conditions
and solvent 4.6 The most potential product
The achievable property space of pure concepts utilizing cellulose
nanocellulose sheets is far beyond what nanofibres
can be obtained with ordinary fibres. It A product survey was carried out to in-
is possible to generate dense translucent dentify the most profitable product con-
films as well as fully opaque plastic-like cepts. The following potential products
tough material just by altering the drying were identified in which the utilization of
speed, temperature and suspension con- NFC material seems technically and eco-
centration. Similar effects can be obtained nomically promising:
by using different solvents. Film-like, 1) Strong board/paper with good
translucent structures are gained when barrier and printing properties for
nanocellulose structures are formed from packaging applications

122

2) Label papers 4.7 Filler-nanocellulose
3) High collecting efficiency filters composites as substrates for
4) Packaging applications with thin printed electronics
insulation layer Mechanically stable and flexible filler-
5) Polymer films NFC sheets provide new property com-
6) Transparent barrier films for binations such as excellent optical prop-
packaging applications erties, smooth surface, and good dimen-
7) Thin, strong, thermally stable and sional stability. These are essential prop-
smooth structures for electronic erties for substrates of printed electron-
applications ics. The filler content of a sheet can be as
8) Laminated papers high as 90%.
9) Insulation materials. Figure 4 shows that filler-NFC com-
posites have smoother surfaces than the
To demonstrate the usability of NFC smoothest paper on the market (photopa-
in different kinds of products, the follow- per) and dimensional stability compara-
ing demonstrations were made at the ble to plastic substrates used in electron-
laboratory scale: 1) Filler-NFC composite ic printing. The smoothness level of fill-
(>80% fillers) for printed electronics ap- er-NFC substrates is similar to that of the
plications, 2) Nanocellulose film as a bar- reference plastic film Mylar A (PET), which
rier, and 3) 50% filler containing SC pa- is a commonly used substrate for print-
per. These demo products span a wide ed electronics. In addition, the filler-NFC
range of structural properties and each substrates gave promising results in pre-
of them also has considerable market po- liminary inkjet printing trials. The resis-
tential. The following chapters discuss the tances measured for various line widths
main outcomes of these demonstrations. were lower for the kaolin-based substrate

Figure 5. Nanocellulose films are good oxygen barriers at low humidity.

Polylac-c
acid,
PLA

100

10

OP,
(cm3
μm/m2
day
kPa)

Masuko
NFC

MFC

1

Carboxymethylated

Cellophane

Poly
vinyl
alcohol,
PVOH
cellulose

Daicel
NFC

0,1

Masuko
NFC

Ethylene
vinyl

alcohol,
EVOH

0,01

Masuko
NFC

TEMPO-‐oxidized

NFC

0,001

Carboxymethylated

cellulose

0,0001

0
50
75

RH,
%

123

Table 4. Differences between high filler content and reference SC papers.

than for the reference PET film. Hence, erties of nanocellulose films.
filler-NFC composites have potential for Figure 5 shows that films made of
printed electronic applications. nanocellulose (~60 g/m2) have very low
oxygen permeability at low humidity. The
measured permeability values are in the
4.8 Nanocellulose films: potential same range as those recently reported for
biobarriers for packaging cellulose-based films as well as synthet-
applications ic films such as EVOH and PVOH. Nano-
A common approach to developing more celluloses thus have the potential for use
sustainable packaging materials is to re- in multilayer packages as oxygen barrier
place synthetic materials with renewable layers in dry conditions. The major chal-
ones. Here we address the barrier prop- lenges are the sensitivity to moisture and

Figure 6. Vision of the virtual product model environment and the first steps towards
it. Parts completed in Phase 1 of the EffTech programme are shown in green.

124

development of a cost-efficient manufac- lenge to the traditional development ap-
turing technology. proach, which is based almost solely on
laboratory experiments and pilot- and
full-scale testing. Virtual product model-
4.9 Increasing the filler content of ling offers a way to significantly speed up
SC paper to 50% product development.
For some grades, one of the most effec- Figure 6 presents the long-term vi-
tive ways to reduce energy consump- sion: to build a virtual product model-
tion in papermaking is to increase the ling environment in which different sim-
filler content. Here, we tested the ef- ulation solvers can becombined to make
fect of increasing the filler content of SC predictions on product properties based
paper from 24% to 48% by simultane- on materials, microscopic structure and
ously adding NFC using a standard lab- production processes. When such an en-
oratory sheet former. The main findings vironment is combined with material da-
were (Table 4): 2–4% NFC was sufficient tabases, the net result is a powerful tool
for wet strength; optical properties were for product development.
clearly better than the reference case;
and dry strength dropped about 40%.
Interestingly, the limiting factor seems 4.11 State-of-the-art simulation of
to be the dry and not the wet strength. materials, processes and products
We also estimated that the carbon foot- In REP, several models and simulation tools
print would be around 15% lower for the were developed as a joint effort between
high filler case. five research groups. The models describe
structural, mechanical and optical proper-
ties of paper-like structures based on par-
4.10 Towards virtual product ticle-level models covering materials and
modelling structures from the nano to macro scale,
Engineering products containing novel i.e., from atomistic simulations to macro-
raw materials will present a major chal- scopic product properties (Figure 7). In ad-

Figure 7. Combining several models enables multi-scale analysis ranging
from atomistic simulations to macroscopic product properties.

125

dition to the detailed description of mate- the elastic properties of single fibrils
rial characteristics, physical and chemical and the interaction force between
process conditions also can be varied dur- fibrils.
ing the formation of structures. • The theoretical minimum energy
The work has concentrated on ad- required for nanocellulose
vanced material modelling, which pre- production is less than 2% of
pares the way for process and product current energy consumption in pure
applications in the EffNet program. The mechanical grinding.
simulation models currently developed • Structures created from NFC are
describe: extremely sensitive to 1) the type
• Cellulose nanofibres and their of interactions, 2) the intensity and
material interactions at the spatial distance of the interactions,
atomistic and molecular levels 3) consistency, and 4) morphology
• Nanocellulose-water dispersion and of fibrils.
forming of nanocellulose network • Aggregation simulations, which
structures combine physical flow conditions
• Particle aggregation in varied flow with the chemical environment,
and chemical conditions were shown to be effective at
• Structure formation at the micro- producing the experimentally
particle level measured aggregate size
• Fibre networks with nanocellulose distributions for various shear rates.
reinforcement • The stiffness of filler-NFC
• Strength, elastic and optical composites can be changed 50%
properties of sheet structures by controlling the aggregate
Although the emphasis has been on size distribution only. The best
nanocellulose applications, the adapted reflectance is obtained for loosely
generic modelling approach can be ap- packed aggregates with the most
plied in many other industrial areas. narrow aggregate size distribution.
Although each simulation tool can be • For wet fibre networks, stretch is
used independently, maximum advantage strongly affected by the disordered
is gained by combining several solvers to- structure whereas strength and
gether into a multi-scale and multi-phys- stiffness were only slightly affected.
ics approach. The simulation tools are This has an important implication
integrated with the help of the Siman- for paper machine runnability.
tics platform developed recently at VTT • Bond stiffness controls the stiffness
(https://www.simantics.org). It serves as of a wet fibre network and the
an open high-level application platform adhesion properties of the bonds
where different computational tools can control the network strength.
be easily integrated to form a common
environment for modelling and simula-
tion. In this project, the synergy achieved
by combining different structural simula-
tions was demonstrated in the case of fill- development needs
er-NFC substrate for printed electronics.
The main results from the simulations Although the potential of cellulose nano-
are: fibres has been demonstrated in this and
• The amorphous regions of several other projects, there are still sev-
nanoscale fibrils strongly affect both eral challenges to overcome before nano-

126

cellulose-based products will be on mar- materials. The LCA and safety screenings
ket. A central challenge is to develop a indicate that we are moving in a sustain-
sustainable web production technology, able direction. From the industry perspec-
the main technical bottlenecks of which tive, this will create direct potential for
will be forming and dewatering. Thus, new fibre-based products and opportuni-
the next step is to continue up-scaling ties for resource savings within current
the most potential technologies and to technologies and products.
show how a new material basis together A direct impact of the research has
with these technologies leads to extended been seen in the introduction of devel-
properties for fibre-based products. oped or applied techniques in company-
From the modelling point of view, the specific projects. The research experi-
idea is to continue model development ments have also indicated the need for
by applying models in solving industrial- new processes and generated potential
ly relevant problems. Integration of the technologies. These technologies show
tools in the virtual product modelling en- substantial potential for saving energy
vironment will not only enable multi-scale and water in current papermaking pro-
analysis but will provide easy access to cesses, but they are also well suited to
combined tools. It will also ensure the us- the manufacture of novel products. They
ability of the models in the long run. have also led to invention notifications
Finally, one crucial issue will be to en- and patent applications.
sure the economical feasibility and sus- The exploitation of the results has
tainability of new technologies and prod- been activated through intensive dialogue
ucts. Thus far, LCA screenings of potential with industrial partners. This has helped
technologies have been made but these to steer the project while also ensuring
need to be refined once the technologi- fast technology transfer to companies.
cal alternatives have been finally deter- Several manuscripts related to the model-
mined. Another essential point is to en- ling activities have been written. We hope
sure the safety of nanocelluloses, which that the modelling platform will transform
is of utmost importance when considering the way new products are developed in
both end users and those handling nano- the future paper industry.
materials on the production line. Crucial- To conclude, the work started in this
ly, thorough understanding is needed of project supports the renewal of the Finn-
nanocellulose characteristics that are of ish forest products industry, the econom-
relevance to product safety. This calls for ic implications of which will be immense.
efficient networking at the European lev- New production equipment will be re-
el in the field of safety and characteriza- quired, new process chemistries will need
tion of cellulose nanofibres. to be developed and a range of new prod-
ucts will be produced that meet various
consumer needs. The ripple effect will be
felt throughout the Finnish economy for
6. Impact of results and many years. In the short term, the re-
industrial relevance sults will increase the competitiveness of
existing assets and grades against geo-
The experimental results achieved thus graphic regions that enjoy intrinsic mate-
far have already shown that the range of rial advantages.
products made from materials containing
nanocellulose is much wider than can be
achieved with current papermaking raw

127

7. Publications and Leppänen, K., Peura, M., Kallonen, A.,
Penttilä, P., Lucenius, J., Sievänen, J.,
reports Sneck, A., Serimaa, R., Characterization
Hellén, E.K.O., Maloney, T. C., Re-en- of nanofibrillated cellulose samples using
gineering paper – renewal from a mate- x-ray scattering, microtomography, scan-
rial perspective, Forest Tech Europe 2008 ning and transmission electron microsco-
conference 6.11.2008, Helsinki, Finland. py, 2010 TAPPI International Conference
on Nanotechnology for the Forest Prod-
Hellén, E.K.O., Re-engineering paper us- ucts Industry, 27–29.9. 2010, Espoo, Fin-
ing nanocellulose and multiscale model- land.
ing, Papermaking Research Symposium
2009, 1–4.6.2009, Kuopio, Finland. Leppänen, K., Pirkkalainen, K., Pent-
tilä, P.A., Sievänen, J., Kotelnikova,
Hellén, E.K.O., Re-engineering paper us- N., Serimaa, R., Small-angle x-ray scat-
ing nanocellulose and multiscale model- tering study on the structure of micro-
ing, 2009 Intl Conf on Nanotechnology for crystalline and nanofibrillated cellulose,
the Forest Products Ind, 23–26.6.2009, Journal of Physics: Conference Series.
Edmonton, Canada. 247, p. 012030. 11 p., 2010.

Illa,X. , Mohtaschemi, M., Puisto, A., Madani, A., Kiiskinen, H., Olson, J.,
Alava, M. J., Rheological Model for Un- Martinez, M., Fractionation of micro-
stable Colloidal Suspensions in Pipe Flow, fibrilated cellulose and its effect on the
2010 TAPPI International Conference on physical properties of paper composites,
Nanotechnology for the Forest Products 2010 TAPPI International Conference on
Industry, 27–29.9. 2010, Espoo, Finland. Nanotechnology for the Forest Products
Industry, 27–29.9. 2010, Espoo, Finland.
Ketoja, J., Hellén, E., Lappalainen, J.,
Kulachenko, A., Puisto, A., Alava, M., McWhirter, J.L., Paavilainen, S.,
Penttilä, A., Lumme, K., Paavilainen, Järvinen, J., Róg, T., Vattulainen, I.,
S., Róg, T., Vattulainen, I., Vidal, D., Atomistic modeling of cellulose nanofi-
Uesaka, T., Multi-scale modeling envi- brils: Elastic Properties, 2010 TAPPI In-
ronment for nanocellulose applications, ternational Conference on Nanotechnolo-
2010 TAPPI International Conference on gy for the Forest Products Industry, 27–
Nanotechnology for the Forest Products 29.9. 2010, Espoo, Finland.
Industry, 27–29.9. 2010, Espoo, Finland.
Paavilainen, S., McWhirter, J.L., Róg,
Kulachenko, A., Uesaka, T., Simula- T., Vattulainen, I., Atomistic modeling
tions of wet fibre network deformation, of cellulose nanofibrils and their interac-
Progress in Paper Physics Seminar, June tions, 2010 TAPPI International Confer-
7-10, 2010, Montréal, QC, Canada. ence on Nanotechnology for the Forest
Products Industry, 27–29.9. 2010, Es-
poo, Finland.

128

Paavilainen, S., McWhirter, J.L., Or- Puisto, A., Alava, M. J., Aggregation of
lowski, A., Róg, T., Vattulainen, I., calcite particles in water suspension, Pa-
Computational perspective to cellulose permaking Research Symposium 2009,
nanofibrils through atomistic simulations, 1–4.6.2009, Kuopio, Finland.
2010 TAPPI International Conference on
Nanotechnology for the Forest Products Puisto, A., Alava, M. J., Aggregation of
Industry, 27–29.9. 2010, Espoo, Finland. calcite particles in water suspension, Fy-
siikan Päivät 2009, 12–14.3.2009, Otani-
Paavilainen, S., Róg, T., Vattulainen, emi, Finland.
I., Analysis of twisting in cellulose nano-
fibrils during molecular dynamics simu- Vidal, D., Uesaka, T., Smoothed Dissi-
lations, 2010 TAPPI International Con- pative Particle Dynamics Model for Pre-
ference on Nanotechnology for the For- dicting Self-Assembled Nano-Cellulose Fi-
est Products Industry, 27–29.9. 2010, Es- bre Structures, 2010 TAPPI Internation-
poo, Finland. al Conference on Nanotechnology for the
Forest Products Industry, 27–29.9. 2010,
Paavilainen, S., Róg, T., Järvinen, J., Espoo, Finland.
Vattulainen, I., Modeling cellulose nano-
fibrils with non-crystalline parts, Fysiikan
Päivät 2010, 16–17.3.2010, Jyväskylä,
Finland.

Pitkänen, M., Honkalampi, U., von
Wright, A., Sneck, A., Hentze, H.-P.,
Sievänen, J.,Hiltunen, J., Hellén, E.,
Nanofibrillar cellulose - in vitro study of
cytotoxic and genotoxic properties, 2010
TAPPI International Conference on Nano-
technology for the Forest Products Indus-
try, 27–29.9. 2010, Espoo, Finland.

Puisto, A., Mohtaschemi, M., Illa, X.,
Alava, M. J., Modeling the Rheology of
Nanocellulose Suspensions, 2010 TAPPI
International Conference on Nanotechnol-
ogy for the Forest Products Industry, 27–
29.9. 2010, Espoo, Finland.

Puisto, A., Mohtaschemi, M., Alava,
M. J., Rheology changes in aggregating
suspensions, Workshop on Chemo-hydro-
dynamic patterns and instabilities, 28–
30.10.2009, Brussels, Belgium.

129

Drainage and
web formation

Project Manager Janne Poranen, janne.poranen@vtt.fi




VTT Technical Research Centre Project management and equipment construction.
of Finland

Betamet Assembly together with VTT.

Etteplan Oy Mechanical design of the press section.

Kemira Design of retention chemical system.

Metso Automation Process automation.

Metso Paper Process design; planning and designing of press
section layout.

Senatti kiinteistöt Oy Modification of main distribution room.

Tamfelt Design and supply of press felts and fabrics.

130

Abstract
The focus of the Drainage and web formation (SUORA) project was the development of a novel
papermaking research environment to serve the development needs of the Finnish forest clus-
ter. The research environment provides new opportunities to form networks between leading
expertise and to develop new competence. This, in turn, serves to support the generation of in-
novations and to boost the development of new products. The environment dramatically im-
proves possibilities to test new products, process concepts and new types of equipment in real-
istic papermaking conditions. Since the environment is smaller and more flexible than industrial
pilot machines, it enables cost-efficient and rapid development of new products and processes
for the Finnish forest cluster. SUORA gathers and combines knowledge from different sectors,
providing a fertile environment for creating new products and innovations. The SUORA environ-
ment is equipped with advanced on-line sensors for process monitoring and different research
needs. Detailed information, such as the behaviour of individual drainage components, can be
obtained using special measurements developed in-house. The SUORA research environment is
designed to be as flexible as possible: the short circulation set-up can be varied, different head-
boxes can be used, three different forming concepts are possible, and concepts for small (500 kg
dry pulp) and large (3000 kg dry pulp) raw material volumes are available ready to use.
Keywords: Drainage, web forming, pressing, research environment, papermaking, prod-
uct properties

131

1. Project background from different sectors, providing a fertile
environment for creating new products
The focus of the Drainage and web for- and innovations.
mation (SUORA) project was the devel-
opment of a novel papermaking research
environment to serve the development
needs of the Finnish forest cluster. The re-
search environment provides new oppor- The main objective of the project was to
tunities to form networks between lead- develop a unique and convertible paper-
ing expertise and to develop new compe- making research environment which uti-
tence. This, in turn, serves to support the lizes latest papermaking technology. The
generation of innovations and to boost environment provides flexible and cost-
the development of new products. effective research with close operation
The environment dramatically im- between companies and research orga-
proves possibilities to test new prod- nizations. The goals of the project are to
ucts, process concepts and new types of accelerate and intensify the development
equipment in realistic papermaking con- work of companies and to pilot new ideas
ditions. Since the environment is small- towards industrial solutions. During the
er and more flexible than industrial pi- project, a wet pressing and sampling unit
lot machines, it enables cost-efficient and was developed and integrated as part of
rapid development of new products and the existing research infrastructure, and
processes for the Finnish forest cluster. research work was started.
SUORA gathers and combines knowledge

Figure 1. Position of the SUORA
environment in the development chain
of new products and processes.

132

3. Research approach ed and extensive process modifications
were carried out. The research environ-
SUORA was implemented as an investment was started up and its first sample
ment project and was separated into four paper rolls produced in May 2010. Sever-
tasks: al training sessions have been held joint-
Tasks 1 & 2 ly with the machine supplier and special
• Unit and sampler design emphasis has been placed on work safe-
• Mechanics, automation, ty issues.
control
Task 3
• Implementation
• Materials purchasing
4. Results
• Production of parts
• Installation 4.1 Process layout
Task 4 The process layout of SUORA is present-
• Start-up ed in Figure 2. There are three different
process options for trials:
The press and sampling unit invest- • Once-through (no circulation)
ments were implemented between sum- • Small volume circulation (15 m3)–
mer 2009 and spring 2010. To meet the 500 kg dry pulp
needs of newer and much larger process- • Large volume circulation (100 m3)–
es, a new monitoring room, pump room 3000 kg dry pulp
and electricity room were also construct-

Figure 2. Process layout.

133

Figure 3. Gap and hybrid forming setups.

GAP FORMER HYBRID FORMER

Either small or large volume circula- 4.2 Forming and press section
tion is typically used. The circulation time layouts
for small volume circulation is in the order Three different forming geometries
of 5 min and in large circulation 30 min (Figure 3) can be studied in the SUORA
(based on 120 l/s/m headbox flow). environment: gap, hybrid and fourdrinier.
Two 100 m3 tanks are currently avail- The gap former is a shoe-blade type with
able, one for process water and one for no forming roll.
pulp. The tank capacity will be more than Key technical specifications for the
doubled during 2011, enabling multicom- forming section:
ponent raw material systems to be run. • Web speed 2500 m/min
Stock preparation from dry rolls is • Max. headbox flow 240 l/s/m
possible using the facilities at the Met- • Web width 300 mm
so Jyväskylä plant. For pulp refining, • Fabric width 500 mm
KCL’s facilities in Otaniemi are available
for use. The press section (Figure 4) consists
A4 paper samples from SUORA can be of a 1-nip press with a 350 mm extended
dried at the laboratory scale at VTT. Roll nip and a sampling unit. Technical spec-
samples can be currently dried at KCL, ifications:
or after VTT’s new drying environment is • Press
commissioned in 2011, also at the Jyväs- o 1-nip geometry
kylä plant. Surface treatments for dry pa- o Nip length 350 mm (options
per samples can be performed at various 250 & 450 mm)
facilities throughout Finland, such as KCL o Max line load 2000 kN/m
or the Forest Pilot Center (FPC). VTT’s o Web width ~250 mm
new cutting-edge laboratory-scale sur- o Belt width 700 mm
face treatment environment at Otaniemi • Sampling
enables the development of radically new o Core diameter 6”
kinds of fibre-based products. o Vacuum-equipped sampling

134

Figure 4. Press section layout.

rolls, d=300 mm process water sampling: Each
and d=640 mm dewatering element in the former
o Roll samples can be achieved and press section is equipped
up to 1500 m/min with 50% with flow rate measurement via
dry content (depending on a measurement weir. The total
press conditions and paper number of weirs is 22. Process
grade) water sampling units have also been
developed.
• Wet-end analyses: Basic
4.3 Special measurements measurements such as pH,
When studying the fundamentals of web temperature and conductivity are
forming and drainage, various special continuously measured at multiple
measurements are essential. The SUORA locations, and the following can also
environment is equipped with several on- be measured on-line:
line sensors and special measurement in- o Dissolved calcium and other
struments to provide a close-up view of multivalent cations
process conditions and web characteris- o Various titrated quantities such
tics. Key measurements include: as alkalinity, dithionite, sulphur
• Forming geometry: The dioxide and dissolved starch
environment is equipped with a o Gas content and dissolved
customised camera system which oxygen content
records the exact location of the o Charge
headbox and the jet coming out of o COD
the headbox. With the help of image o Redox potential
analysis software the jet length and o Volatile compounds in process
impingement angle can be precisely waters using electronic nose
determined. • Fractionator: FracOn analyser
• On-line dewatering rate and developed by Metso Automation,

135

Figure 5. Press section and sampler.

measures the fractionation of fibres
in a pulp sample impact of results
• Friction between vacuum box
and fabric: friction force acting A joint research project has been
between the wire and suction box launched with an industrial consortium
lid can be measured using three using the current papermaking research
force sensors environment. The Fundamentals of Web
• On-line formation: optical Forming project (SUORA-KH) was a con-
formation of the web can be sortium project between VTT and five For-
analyzed estcluster Ltd owner companies: UPM-
Kymmene, Kemira, Tamfelt, Metso Pa-
When running trials, on-line tools for per and Metso Automation. Project time
data acquisition and reporting are essen- frame: 1.8. 2008–30.9.2010. The objec-
tial. A Savcor Wedge process diagnos- tive of the project is to develop a unique
tics system was installed in the SUORA papermaking research environment and
environment in spring 2010. The Wedge efficient technologies for papermaking in
system enables plotting of on-line trends co-operation between the project part-
and calculation of trial point specific infor- ners.
mation, including paper-laboratory data, Results from laboratory-scale studies
during the trial. carried out in the EffNet programme will

136

be verified in the SUORA environment. 6. Publications and
Example of SUORA’s role as a test envi-
ronment prior to production-scale work: reports
Verification of project results Poranen, J., VTT:n paperinvalmistuksen
• QVision results => New tutkimusympäristö edistää yritysten no-
measurement and control systems peaa ja kustannustehokasta tuotekehit-
• POJO ideas => Advanced process ystä, VTT:n media-aamiainen 18.11.2008
solutions
Potential of new products Poranen, J., VTT’s new research infra to
• REP => scale-up of NFC based develop fibre processes (SUORA), PulPa-
products per 1.6.2010
High consistency papermaking
• To save energy, raw materials and
water

137

Future paper and
board making technologies
(TuPaKat)

Project Manager Juha Lipponen, juha.lipponen@innotiimi.fi




Metso Project management / Juha Lipponen

VTT Technical Research Centre Project coordination and proposal preparation work
of Finland

Futura Marketing Oy Scenario work
(Henrikki Tikkanen, HSE;
Juha-Antti Lamberg, HUT;
Tomi Nokelainen, TUT)

Innovaatiopalvelu Pekka Innovation work
Koivukunnas Oy

SW-Development Technology and business development simulation
platform

TRIZ Oy (Kalevi Rantanen) A vision of the forest industry and their product

University of Oulu Ideation session with Paper Machinery and
Process students

138

Abstract
The TuPaKat project has made three alternative paper and board consumption scenarios un-
til 2050 and three roadmaps until 2030. The roadmaps focused on reduction of energy and
raw material use, ideal papermaking and fiber-based products for printed electronics. In addi-
tion, the project group proposed four most influential technology concepts for future papermak-
ing (open base sheet + functional finishing; foam line; agile and modular papermaking; press-
less papermaking) and eight miscellaneous technology and/or business development proposals.
The TuPaKat project has been active in gathering project ideas and developing them to proj-
ect proposals. The work has been widely utilized in the planning of the second phase of the Eff-
Tech program.
Keywords: New technology, radical innovation, paper making, board making, scenario,
ideation.

139

1. Project background Concerning paper and board mak-
ing technologies in particular, the goal
Starting point of the project is to devel- is to think the papermaking process as
op ideas for new radical production tech- a whole, instead of more traditional ap-
nologies for forest based businesses. The proach of developing papermaking with-
task divides in two: 1) Radical innovation in its subprocesses. Figure1 describes the
of “traditional” paper and board making traditional thinking.
processes, and 2) through scenario work, Paper and board making processes
draft technology needs for future fiber- consist of dozens of consecutive sub pro-
based new products. cesses. Due to several reasons (such as
the sub processes requiring detailed and
profound special expertise) the develop-
ment in companies as well as in univer-
2. Project objectives sities has been divided to different (and
Concerning paper and board making tech- isolated) branches of expertise. In turn,
nologies in particular, the goal is to think this has led to very stiff boundary condi-
the papermaking process as a whole, in- tions between these sub processes tech-
stead of more traditional approach of de- nology wise. This has resulted in low free-
veloping papermaking within its sub pro- dom in innovating whole new papermak-
cesses. The Project produces technolo- ing processes. The development has then
gy needs for future development through reduced into incremental sub-optimiza-
scenario and innovation work. tion.
Figure 2 presents different approach-
es on process industry. Left side repre-
sents declining prices/cost hunting race
3. Research approach and its variables. Cost reduction in forest
Starting point of the project is to devel- industry consists of both everyday opera-
op ideas for new radical production tech- tion optimization work and periodical im-
nologies for forest based businesses. The provements in technology – sometimes
task divides in two: 1) Radical innovation even revolutionary. The sum effect, how-
of “traditional” paper and board making ever, is the declining profitability develop-
processes, and 2) through scenario work, ment we see in forest industry today. Ba-
draft technology needs for future fiber- sically there is no reason why the funnel
based new products. would not continue tightening in the future.

Figure 1. Separate subproces oriented development approach

140

Figure 2. Business approaches on process industry for existing
business (left) and new value added businesses (right).

The right side presents the effect of thousands of computers in their disposal,
new value added product and service con- of which most are made of paper. Cellu-
cepts forest industry may introduce in the lose based e-paper products flourish, but
future. The project produces technology also on traditional printing paper – con-
needs for future development through trary to many futurologists – text infor-
scenario and innovation work. These mation is still printed and it is consumed.
needs are then converted to actual proj- Intelligent paper – or e-paper – talks,
ect proposals for Forestcluster’s ongoing hears, illuminates, communicates and
and upcoming research projects. collects its own energy from the environ-
ment. Intelligent and biodegradable sen-
sors are distributed to forests and trees.
Then, a wood (and the forest together)
4. Results will determine autonomously to be ready
to be harvested and calls wirelessly a ro-
4.1 Visions of 2030 Finnish Forest bot to do the harvesting.
Industry Cellulose molecules and the chemis-
Kalevi Rantanen studied according to pat- try of wood is generally learned to un-
terns in technological development the derstand and control in a way to gener-
possibilities for year 2030 forest prod- ate whole new forest economy branches.
ucts, and what kind of forest industry and Cellulose electronics, forest biopolymers
economy can exist in Finland in 2030. In and cellulose composites change our ev-
this work, future laws of future scholar eryday life. New kind of wood biomasses
Prof. Emeritus Osmo A. Wiio and technol- are used to produce (fully automatized
ogy development laws of Genrih S. Alt- and mass production) very inexpensive
shuller were utilized. mass-tailored houses. Intelligent cellulose
In year 2030 in Finland, everyone has textiles replace cotton. Genetic modified

141

trees produce tailor-made industrial ma- minute and think if a given paper
terial, food supplements and medicine. consumption level per capita
Forest tourism has expanded in a way is actually already reached in
that Everyman’s Right has been forced to the countries of Western living
be controlled. A debate of controlling the standards. The additional growth
wandering of wolves with microchips is would then be due to increase in
going on. population only – which also is not
great in Western Europe.
• North America consumption
4.2. Forest Industry Scenarios for increase rate was expected to
2050 be somewhere between 0.5 and
Starting from the widely used classical 1.8%. If, again, the assumption of
consumption forest products forecasting maximum consumption per capita
i.e. correlating the consumption forecast is applied also here, the potential
as a function to GNP/product price/popu- growth rate will be close the bottom
lation, three alternative scenarios for the limit. Both scenarios 1 and 2 expect
mentioned regions were proposed: also North America consumption to
• Scenario 1: Here, paper and start declining in the future.
board consumption forecast are
made based on GNP and earlier
consumption development 4.3 Roadmaps
• Scenario 2: Country-by-country TuPaKat-project had one goal of pro-
GNP was expected to grow only ducing some roadmaps on reduction of
1/3 what was predicted, and long- energy and raw material use, ideal pa-
term demand flexibility was set as permaking and fiber-based products for
maximum of one. printed electronics. Timeframe selected
• Scenario 3: Here, paper and board for the work was 2010 to 2030.
consumption are expected to follow Science, technology and applications
population at a point of certain GNP needs joint vision, In order to be capa-
and paper consumption has been ble of building applications needed at a
reached. given time with proper price. These ef-
forts require communication, where road-
The results can be used to draw the mapping-process can be used as one tool.
following conclusions: Linkage between science and applications
• Despite of the different consumption is therefore required, but at the same
scenarios give varied results in time some flexibility is needed, to find
paper and board products demand, the potential applications and new ways
in every scenario Asia – especially to solve given problems.
South and East regions – show the The three roadmaps made in this
fastest growth rates. project serve as an example of the link-
• In Europe, the fastest growing age and flexibility. First roadmap was
region is the East Europe; the rest made for existing products with a view-
of the Europe growth is highly point of technology, science and applica-
dependent on the assumption tions existed, having flexibility in options
whether or not the future growth to fulfil the energy savings needs using dif-
will continue to follow the GNP ferent technological solutions. Second road-
development. map had flexibility also in technology, but
• Here, it can be good to stop for a solutions needed were faced from needs,

142

not technologies available today. Of course, in each technology can be combined in a
there were already some solutions avail- way found later suitable. Potential of each
able to fulfil the requirements. Third road- technology by grade varies greatly.
map had highest freedom, and pace of de- Second roadmap showed the ideal pa-
velopment in the area is very rapid. Market permaking process and ideal unit process-
growth potential is highest there. Growth es (Figure 3). For some unit processes a
potential in the first and to some extent concept was also proposed
second roadmap is more moderate, but Third roadmap showed the printed
substantial market already exists. electronics potential and applicability in
First roadmap showed that halving fibre based substrates. OLED & memory
energy costs requires combination of ma- market was has extremely high growth
ny technological solutions, but it showed rates which in combination with fast de-
that it is possible. The possible savings velopment is a challenging, and desirable.

Figure 3. Development paths from state of the art towards statuses of ideal
papermaking world, with research actions described in between at the path
to ideal papermaking.

143

4.4. Concept recommendaations 4.4.2 Foam line
The project group proposed four most in- This technique offers flexible tailoring of
fluential technology concepts for future layers in web forming by enabling po-
papermaking :open base sheet + func- rous structures or very thin layers. It al-
tional finishing; foam line; agile and mod- so enables the utilization of nanomate-
ular papermaking; pressless papermak- rials in web forming. The benefits of the
ing. techniques are layer purity and excellent
sheet uniformity, as well as, the possi-
4.4.1 Open base sheet + functional bility to engineer product properties with
properties through finishing smaller amount of raw material and less
Using today’s vacuum roll parameters energy use in production.
(vacuum levels and dwell times using Future action will include research on
commercial vacuum rolls), it is possible to (e.g.)
fully impregnate liquids (fillers, binders, • Tailoring of foam chemistry
various fiber fractions etc.) thoughout pa- o Screening of surfactants
per and board products. The technology o Characterization of foams;
opens new possibilities for utilizing high measurement techniques
consistency and waterless forming tech- o Evaluation of the process;
nologies (open and weak base sheets) for foaming of material/mixing of
adjusting the final product properties, as material into foam
well as utilizing various Non-Woven prod- • Foam rheology
ucts and Fiber-based composites impreg- o Rheological properties of
nation. One important aspect of the tech- different kinds of foam-fiber
nology is its potential in introducing whole suspensions.
new business and product possibilities on o Foam handling in processes.
fiber-based base paper and impregna- • Multi-layer products: demonstration
tion of different functional chemicals, ad- of product properties in laboratory
ditives and fillers. These businesses can scale
then utilize the infrastucture of forest in- • Multi-layer foam forming: scale-up
dustry and a great deal of its existing web of the new concept
forming technologies. • Sustainability calculations for
The following items should be ad- specified products
dressed in order to approach the defined
goal: 4.4.3 Agile and modular
• Studying less-water, pressless press papermaking
(low density) base sheet and other The objective is to renew value creation
open sheet techniques by reducing investments per plant and
• Impregnation studies: more detailed driving flexibility and reuse with new ar-
sheet scale testing, planning for chitecture for forest industry
dynamic impregnation testing • Reduce investments per plant
facilities for SUORA environment, o Standardisation and the use
paper and board quality evaluations of same delivery chains with
based on low-density base sheet + other industries
impregnation treated papers and o Reuse of plant modules
boards • Promote Flexibility&reusability:
• Plasma treatments studies o Smaller plants with shorter
• Light surface treatment studies lifetime at one site

144

o One plant is capable of out pressing, the final paper bulk before
producing wide range of calendering can be increased from 1.5 to
products: 2.5…4.0. In other words, the base paper
o Reusable plant modules for bulk can potentially be doubled. if final
new sites paper bulk would be able to be e.g. dou-
o Innovations are enabled via bled, this would mean the following:
open modularity • E.g. 80 g/m2 copy paper would be
reduced to 40 g/m2 with essentially
Objective of the research is the following: the same functional properties
• a paper mill concept defined in this (thickness, roughness etc. )
project has shorter time span from • Reducing BW by 50% will also
capital cost to start of production, reduce the needed drying energy
total investment cost will be lower, accordingly
and the investment will be more • More bulky and compressive sheet
secure with reusability in future may be calendered more easily to
projects. required roughness => more bulk
• To define new business concepts savings
related to agile manufacturing of
fibre based products. How could one then remove the wa-
• Development of operating models ter without wet pressing? Capillary forces
for forest industry which utilize should be able to remove the free water.
resource efficient processes. A ”press” dryness of 40 to 50% should
be reachable (a practical press dryness!).
The main actions include developing Note: there should be less rewetting in
a new mode of operations and introduc- pressless capillary pressing!
tion of architecture with key technologies The following items should be ad-
and standardization. Here, the succesful dressed in order to approach the defined
modularization development work done at goal:
other brands of industries (such as mari- • Research on pressless press concept
time industry and power plants) is intro- o Capillary and electro osmotic
duced to the forest industry. transport studies
o Process modeling
4.4.4 Pressless Papermaking o Strength development /
In many paper and board grades, paper improvement at low density
bulk is one of the key properties of the • Product research
paper. Bulk (or thickness) is often pur- o Research how ultra-low density
sued due to need of paper stiffness and (compressible) papers behave
rigidity. Wet pressing and calendering, in printing processes
however, are responsible for essentially o Other paper and board
destroying the bulk of paper. properties analyses and studies
If water removal after forming and for new ultra-low density grades
before evaporation (20–50%) could be
able to do essentially without wet press-
ing, paper bulk should be doubled. Here,
if water removal from dry content of 22%
to D.C. of 45–50% (typical wet press-
ing dying amount) would be done with-

145

5. Future plans
The results of the TuPaKat project have
been used in preparation of the continu-
ation of EffTech program. The results in-
clude project preparation and roadmap
work. Concerning paper and board mak-
ing technologies in particular, the results
help the industry to think the papermak-
ing process as a whole, instead of more
traditional sub-process approach of de-
veloping papermaking. Therefore, sever-
al line scale proposals for new technolo-
gy platforms were introduced.

146

Forestcluster EffTech programme report

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