![Typical Yield of Thermo-Chemical Processes
Process Reaction
Conditions
(Temperature [°C],
residence time)
Char
Weight %
Liquid
Weight %
Gas
Weight %
Slow pyrolysis ~400 °C h - week 35% 30% 35%
Mild pyrolysis ~500 °C 10 – 20 sec 20% 50% 30%
Fast pyrolysis ~500 °C 2 sec 12% 75% 13%
Gasification ~800 °C -1400 °C
10 - 20sec
10% 5% 85%
HTC ~180 °C - 250 °C
1-12 hour processing
time
50-80% 5-20%
Dissolved in water
2-5%](https://image.slidesharecdn.com/1ff77c05-c374-4e8a-acf4-a49a30bea905-150305094403-conversion-gate01/85/20131008-Biomass-Conversion-Technologies-13-320.jpg)
20131008 Biomass Conversion Technologies
- 1. Biomass Conversion Technologies Gasification, Pyrolysis, Hydrothermal Carbonisation Dr. Bodo Groß; gross@izes.de Mahbod Shafiei; shafiei@izes.de
- 2. Future World Energy Demand Industrialisation and population growth of emerging countries has increased the world wide energy demand to an alarming rate It is expected that energy demand surge up with app. 44 % from current total of 138,000 TWh to 198,000 TWh by the year 2030 (Ref.: Renewable and Sustainable Energy Reviews 16 (2012) 3084– 3094) World Energy Outlook Report (WEO) 2012, has cited that fossil fuel will remain the main source of energy with app. 80 % by the year 2035 Ref: http://jcwinnie.biz/wordpress/
- 3. World Energy Outlook Report 2012 (WEO) Ref: World energy outlook 2012, ISBN: 978-92-64-18084-0
- 4. Rapid increasing amount of CO2 in the atmosphere since 1900 CO2 Emission to Atmosphere World atmospheric concentration of CO2 and average global temperature change Ref: World energy outlook special report 2013
- 5. According to renewable global status report in the year 2012, app 19 % of total energy demand is produced by renewable energies Share of Global Final Energy Consumption Ref:: Renewables 2013 Global statues report ISBN 978-3-9815934-0-2
- 6. Renewable Energies in the World in 2012 Share of renewable energies in primary energy consumption in the world shows that Europe had around 40 % of share in global renewable energy consumption in 2012. Eurasia contain Europe and Azerbaijan, Belarus, Kazakestan, Turkey, Turkemenistan, and Uzbekistan Reference : BP statistical Review of World Energy June 2013. Bp.com/statistical review
- 7. Share of total energy production in Europe area in 2010 (%) Renewable energy by 26 % had the second place in total energy production in Europe area in 2010 Reference : European commission, eurostat. . www.epp.eurostat.ec.europa.eu Energy Production in Europe Area
- 8. Renewable Energy Production in Europe Primary prodcution of renewable energy in Europe area in 2010 Biomass and waste has the first place in Renewable energy Production Reference : European commission, eurostat. . www.epp.eurostat.ec.europa.eu
- 9. Biomass Biological structure derived form living or recently living organism. Biomass composed carbohydrate polymers (cellulose and hemicellulose) and aromatic polymer (lignin). Cellulose (C6H10O5) is the most important structural component of the primary cell wall of green plants and the most abundant organic polymer on earth. Hemicellulose present with cellulose in almost all plant cell walls. Cellulose is crystalline, strong and resistant to decomposition in presence of heat, but hemicellulose has a little strength in front of heat. Unique characteristics of biomass as the only renewable and carbon based resource, makes it more attractive for energy purposes. Divided into; wet and dry Biomass.
- 10. Neutral Carbon Cycle of Biomass Ref.: Center for Environmental Research and Technology, Bourns College of Engineering University of California
- 11. Future Energy Demand via Biomass In future energy trends, a major role in the energy supply has been pointed to biomass Biomass has been used widely as feedstock for thermal conversion processes such as combustion, gasification, pyrolysis, and hydrothermal carbonisation to get various phase of products (solid, liquid and gas) to get energy Ref: https://ukerc.wordpress.com/
- 12. Slow Heating of Biomass Slow heating of biomass can be categorised to five levels of temperature and pressure that end in various products in each level Conversion technologies, subdivided into these five groups, which end in different phase of products in quantity depend on nature of biomass and process condition Slow Heating of Biomass Temperature Pressure zone Gases – phase products < 200 °C 1- 5 bar Drying Mainly H2O in phase of vapour releases from biomass 180 °C – 250 °C 1- 5 bar Devolatilization Removing –OH Structures, acetic acids, organics, CO2 releases from biomass, decomposition of cellulose starts 5 - 20 bar Hydrothermal Carbonization of Biomass (HTC) Main product is char Pre-treatment for gasification 250 °C – 300 °C 1- 5 bar Torreffaction Deoxygenation, removing O2 from reaction mixture, complete decomposition of hemicelluloses, decomposition of cellulose starts 300 °C – 500 °C 1- 5 bar Pyrolysis Char coal is the main product > 500 °C 1- 5 bar gasification combustion Aromatics,H2O,syngas, higher hydrocarbons
- 13. Typical Yield of Thermo-Chemical Processes Process Reaction Conditions (Temperature [°C], residence time) Char Weight % Liquid Weight % Gas Weight % Slow pyrolysis ~400 °C h - week 35% 30% 35% Mild pyrolysis ~500 °C 10 – 20 sec 20% 50% 30% Fast pyrolysis ~500 °C 2 sec 12% 75% 13% Gasification ~800 °C -1400 °C 10 - 20sec 10% 5% 85% HTC ~180 °C - 250 °C 1-12 hour processing time 50-80% 5-20% Dissolved in water 2-5%
- 14. Conversion Technologies Wood gasification plant in Güssing/ Austria Produces 2MW of power and 4MW of heat for the local district heating network
- 15. Torrefaction Proceeds between 200 C to 300 C, under atmospheric condition In absence or very limited amount of oxygen and very low heating rate Hemicellulose deeply decomposes and cellulose and lignin partly decomposes that starts around 250 C Moisture of biomass will be removed by evaporation and some organic acids, such as acetic acid will be driven off Torrefaction removes oxygen from biomass that causes higher heating value of the product Around 70 % of mass is preserved which contain 90 % of initial energy Aslo remove hydroxyl and –OH groups in biomass and makes it more hydrophobic Torrefied biomass can be milled easily, and high porosity of biomass increases its reactivity More CO and H2 in syngas, but the same quantity of CO2 Torrefaction used as pre treatment for gasification reactor
- 16. Energy and Mass balance in Torrefaction willow wood was conducted in Toreffaction process at temperature between 250 C and 300 C with residence times of 10 and 30 minutes With increasing temperature severe decomposition of cellulose occurs at higher 300 C Torrefied product has a lower O/C and H/C ratio, so it has properties and character between wood and coal
- 17. Torrefaction Process as pre - treatment Step 1 Step 2 Step 3 Step 4 Unprocessed wood Dried wood chips Torrefied wood chips Final wood pellets Wood chips are collected and stored, so they can be used as biomass Wood chips are dried before they undergo torrefaction process The wood chips are heated using microwave technology within a rotating drum reactor, creating a charcoal like substance The torrefied wood is milled and made into pellets that produce up to 10 % to 20 % more energy than untreated one
- 18. Pyrolysis Carry out under 300 °C to 500 °C and almost atmospheric pressure with residence time between 0.5 second to 24 hour. Carry out in the absence or nearly without oxygen. Divided to four groups depend on oven temperature and residence time: Flash, fast, mild, and slow pyrolysis Under these conditions, hemicelluloses, cellulose, and lignin decomposes to char as solid phase, tar as liquid phase, and gases depend on residence time Heat transfer rate rise up, By increasing oven temperature and in short residence time ( < 2sec ), dominate product is tar (liquid phase) Char is the main product of slow and mild pyrolysis with low oven temperature and high residence time liquid fractions or condensable gaseous products are the main product of flash and fast pyrolysis with high oven temperature (app. 500 °C), high heat transfer rate ( app. 1 °C / sec) and very low residence time ( < 2 sec) Fast and Flash pyrolysis is an effort to maximize liquid products such as BIO – Oil
- 19. Typical Yield of Thermo-Chemical processes Process Oven temperature residence time pressure Particle size Heat rate Main products Heating value of products Application area Flash pyrolysis 800 °C – 1000 °C < 0.5 sec 1-5 bar < 0.2 mm Biomass supply in form of dust Very fast heating rate > 1 °C/s Tar products Bio - Oil - Power plants, diesel, boiler, resin, fertilizer, fine chemicals, transport fuels, emulsions Fast Pyrolysis 500 °C - 600 °C ~ < 2 second 1-5 bar < 1 mm High heating rate >100 °C/min Tar products Bio - oil 17 MJ/kg Power plants, diesel, boiler, resin, fertilizer, fine chemicals, transport fuels, emulsions Mild Pyrolysis 315 °C – 450 °C 10-20 second 1-5 bar 5-50 mm Controlled heating rate to control tar formation Char Bio - coal 19 – 24 MJ/kg Filtration (water and air), soil improvement, power plant, pharmaceutical s Slow Pyrolysis 200 °C - 300 °C 30 minute / days 1-5 bar 5-50 mm 0.1 – 0.2 °C/sec charcoal 25 - 37 MJ/kg Char coal (lump)
- 20. Schematic of Pyrolysis (Char and Bio-oil) Ref: http://energyfromwasteandwood.weebly.com/
- 21. Gasification Controlled partial oxidation of carbonaceous material with less oxygen than required to complete combustion ( air/fuel < 0.5). Carry out under 600 °C to 1500 °C and almost atmospheric pressure. CO2, CO, CH4, H2 and H2Og and trace of higher hydrocarbons such as ethane (C2H6) and ethene (C2H4) exists in produced gas. Generally air, steam, air/steam and oxygen are used as gasification agent. Final produced gas is a function of type of gasifier, operating condition, and gasification agent. Different gasification processes, classified by the regime of flow inside gasifier. Divided to three main groups of fixed bed, fluidized bed, and entrained flow. low cost and simple design and operation is fixed bed advantageous, but Non uniform mass and heat transfer in fixed bed gasifier causes high amount of tar and char in produced gas. Good mixing and solid contact causes, higher conversion efficiency in fluidized bed gasifiers, but higher cost of operation is its disadvantageous.
- 22. Gas Composition and Calorific Value Calorific value Numerical value Agent Application Low CV 4 - 6 MJ/Nm3 Air Steam/ Air Directly in combustion or engine fuel Medium CV 12 -19 MJ/Nm3 Oxygen/ Steam Utilizes as feedstock for subsequent conversion into basic chemicals such as methane or methanol High CV 40 MJ/Nm3 Hydrogen Mainly in chemical industry Typical gas composition in gasification process Produced gas Bio fuel gas (Vol %) Charcoal (Vol %) N2 50-54 55-65 CO 17-22 38-32 CO2 9-15 1-3 H2 6-22 15-20 CH4 2-3 0-2 LHV (MJ/M3) 5-5.9 4.5-5.6
- 23. Main Characters of Gasification Process
- 24. Gasification Process Drying the feed stock Happens in temperatures up to 200°C and only water driven off At 180°C carbon dioxide and acetic acid with –OH structure starts to decompose, which is called Devolatilization, without chemical or physical decomposing of biomass Pyrolysis to produce char Takes place between 300°C to 500°C, produces a large quantity of tar and gases containing carbon dioxide Natural structure of the fuel is broken through exothermal reactions which release steam, methanol, acetic acid and a considerable amount of heavy hydrocarbons, depend on residence time Gasification (combustion and reduction) Combustion contains both exothermic and endothermic reactions which give a theoretical oxidation temperature of 1450°C In reduction area, a number of incombustible gases are converted into combustible products through a series of reactions, depending on the temperature, pressure and concentration of the reacting species
- 26. Syngas Produced by Various Gasifiers Fuel feedstock Gasification reactor Gasification conditions CO Vol % H2 Vol % CH4 Vol % CO2 Vol % N2 Vol % LHV MJ/m3 Wood saw dust pellets Downdraft GA: air RT: 900 - 1100 °C 21.3 17.5 3.1 13.3 44.2 6.0 Wood chips Up draft 1.5 MW RT: 800-900 °C GA: air + steam 29 15.4 1.6 6.8 47.2 5.54 Wood pellet Bubbling fluidized bed BM: ofite GA: air/ oxygen/ steam BT: 755-840 °C 28.5 25.7 8.1 9.2 28.5 9.28 Wood pellets Circulating fluidised bed GA: air BM: sand 23.8 21.7 0.08 9.4 41.6 5.03 Coal Flow rate: 76.66 g/sec Entrained flow gasification GA: oxygen and steam 57.55 39.13 0.12 2.95 0.12 10.83
- 27. Gasifing Reactors Fixed Bed Gasifiers Downdraft gasifier Updraft gasifier Crossdraft gasifier Downdraft gasifier Updraft gasifier Crossdraft gasifier
- 28. Gasifing Reactors Fluidised Bed Gasifier Bubbling fluidised bed Circulating fluidised bed Circulating fluidised bed Bubbling fluidised bed
- 29. Gasifier Reactors Entrained flow gasification Entrained flow gasification
- 30. Quality of the produced gas in gasifiers Gasification technology Feed stock property Tar and particle content Quality of produced Syngas Rank Down draft Less than 55 mm in size Up to 25% moisture Low tar content Moderate particle High amount of N2, low amount of CH4, moderate amount of CO and H2 ●● Up draft Less than 55 mm in size Up to 60% moisture High tar content Moderate particle High amount of N2, low amount of CH4, moderate amount of CO and H2 ●● Cross draft 10 % to 25% moisture High tar content High particle content - ●● Bubbling fluidized bed Less than 6 mm in size < 50% moisture Depend on the bed material C2+ , tar, and particles are present High amount of CH4 in compare with other technologies, higher CO and H2 ●●● Circulating fluidized bed Less than 6 mm in size < 50% moisture High particle in circulating C2+ , tar, and particles are present High amount of N2, low amount of CO and H2 ●● Entrained flow Less than 0.15 mm in size < 15% moisture Low tar and C2+ In Syngas. Ash slagging High amount of CO and H2, low amount of N2,CO2, and CH4 ●●● • (poor quality) •••• ( good quality)
- 31. Mass Balances Increasing performance variables needs useful measures of mass and energy balances Reactor Input materials Output materials MCE* (Without tar and ash) %Feed stock Air steam Tar Char, Ash Dry gas Water H2Og Down Draft gasifier 20% Reject pellets, 80 % wood chips 3.70 (kg/hr) Air 7.39 (kg/hr) - 0.04 (Kg/hr) 0.08 (kg/hr) 9.26 (kg/hr) 0.17 (kg/hr) 83 % Up draft gasifier RDF pellets1 5.16 (kg/hr) Air 12.97 (kg/hr) 0.58 (kg/hr) 0.18 (kg/hr) 0.13 (kg/hr) 16.96 (kg/hr) 0.93 (kg/hr) 90 % Bubbling fluidised bed Wood pellets 11.5 (kg/hr) Air 20.4 (kg/hr) - < 3.46 (kg/hr) 28.44 (kg/hr) - 89 % Circulating fluidized bed Olive oil waste 60 (Kg/hr) P* Air 130 (Kg/hr) S* Air 32 (kg/hr) - < 43 (kg/hr) 179 (kg/hr) - - 80 % Entrained flow Saw dust 0.6 (kg/hr) Air 0.8 (kg/hr) - < 0.27 (kg/hr) laboratory experiment 1.13 (kg/hr) - 80 %
- 32. Carbon Conversion Carbon conversion is defined as the fraction of carbon in the feedstock converted to gaseous products Nature of biomass, air ratio, reaction temperature, pressure and present of catalyst effects the carbon conversion rate Higher (ER) leads to lower heating value of gases, but lower (ER), increases carbon conversion Steam increases gas quality and heating value of the gases, but decreases the gas yield because it doesn’t take part in gasification reactions, so a lower carbon conversion rate is attained Low operating temperature is equal to incomplete carbon conversion. High temperature favored the carbon conversion efficiency. High pressure has negative effect on carbon conversion, however the experiments show that optimum carbon conversion is reached at low pressure around 1 bar
- 33. Carbon Conversion Gasifier Input feed stock (carbon flow rate) Output carbon flow rate Feed stock (kg/hr) Carbon content Wt % Carbon flow rate (kg/hr) Carbon flow rate (kg/hr) Carbon conversion1 % Accessible carbon2 % Gas yield LHV (MJ/M3) Downdraft gasifier With air RT: 900 °C 20% paper reject pellets 80% wood chips ER: 0.36 3.70 kg/hr 48.66 Wt % 1.8 (Kg/hr) 1.49 (Kg/hr) 82 % 1.03 (kg/hr) 57 % 8.81 (m3/hr) 5.79 (MJ/M3) Updraft gasifier With air/steam RT: <1200 °C Wood chips 5.2 (kg/hr) ER: 0.36 55.72 Wt % 4.29 (kg/hr) 3.24 (kg/hr) 75 % 2.15 (kg/hr) 50 % 20.48 (m3/hr) 5 (MJ/M3) Bubbling fluidized bed With Air BM: Ni-alumina BT: 780 -830 °C Chips of pine wood FR: 0.4 -0.8 (kg/hr) ER: 0.18 -0.45 50 Wt % 0.4 (kg/hr) 0.35 (kg/hr) 87 % 0.25 (kg/hr) 62 % 1.25-2.45 (m3/kg) 3.7-8.4 (MJ/M3) Bubbling fluidized bed with Steam BM: silica sand BT: 750 -780 °C Chips of pine wood FR: 1.5 – 4 (kg/hr) ER: 0 (kg/hr) 50 Wt % 2 (kg/hr) 1.34 (kg/hr) 67 % 0.94 (kg/hr) 47 % 0.86-1.14 (m3/kg) 10.3-13.5 (MJ/M3) accessible carbons defined as flow rate of carbon in output Syngas, which have LHV value consist of CO, CH4, and CnHm to carbon flow rate of input biomass feedstock.
- 34. Carbon Conversion Gasifier Input feed stock (carbon flow rate) Output carbon flow rate Feed stock (kg/hr) Carbon content Wt % Carbon flow rate (kg/hr) Carbon flow rate (kg/hr) Carbon conversion1 % Accessible carbon2 % Gas yield LHV (MJ/M3) Circulating fluidised bed With air BM: silica sand Willow 69 (kg/hr) ER: 0.37 BT:850 °C 48.7 Wt % 33.60 (kg/hr) 27.04 (kg/hr) 81.5 % 12.43 (kg/hr) 37 % 151 (m3/hr) 3.15 (MJ/M3) Entrained flow With air and steam Wine industry waste4 0.96 kg/hr ER: NR RT: 1050 °C 52.61 Wt % 0.5 (kg/hr) 0.3 (kg/hr) 59 % 0.175 (kg/hr) 35 % 1.59 (m3/hr) 9.81 (MJ/M3) Entrained flow With air Wine industry waste4 0.96 kg/hr ER: NR RT: 1050 °C 52.61 Wt % 0.5 (kg/hr) 0.47 (kg/hr) 94 % 0.244 (kg/hr) 48 % 2.67 (m3/hr) 5.05 (MJ/M3) accessible carbons defined as flow rate of carbon in output Syngas, which have LHV value consist of CO, CH4, and CnHm to carbon flow rate of input biomass feedstock.
- 35. Hydrothermal Carbonisation (HTC) Typically HTC of biomass is achieved in water at elevated temperatures of app. 180°C to 250°C and under pressures of about app. 20 to 25 bars for several hours Very small amount of gas (1-5%) is generated, and most organics remain or are transformed into solids. Mainly water is removed from the biomass, hence energy density of the product will raise and heating value will be increased Variety of problematic wastes and continuously generated biomass streams are used such as, human waste (e.g. excrement’s and faecal sludge’s), municipal solid wastes as well as agricultural residues and algae Compared to other conversion methods low amount of energy during processing and low operation temperature is necessary. In addition to the high conversion efficiency, a low amount of tar and very high amount of H2 as well as a low CO content in the product could be achieved. Deploying the process to industrial size has been the key obstacle until now
- 36. Schematic of Hydrothermal Carbonisation (HTC) Ref: Suncoal hydrothermal carbonization process www.suncoal.de http://www.suncoal.de/en/technology/carboren-technology
- 37. Feedstock Property Characters of biomass such as moisture content, ash content, volatile compounds, and particle size has effect on gasification performance Fuel with moisture more than 30 % makes ignition difficult and reduces the CV of the produced gas Moisture content has effect on grind ability of the biomass Moisture reduces the highest temperature in oxidation zone, leads to incomplete cracking of hydrocarbons released from pyrolysis zone In fast or flash pyrolysis due to the high heating rates, fine feed stock with very low particle size is required Feed stocks with high moisture content are mostly suitable for biological conversion technologies such as fermentation, anaerobic digestion, but for hydrothermal carbonisation (HTC) too Utilisation of and special kind of pre treatment depends on the used or preferred conversion technology
- 38. Now! Which kind of feed stock do you have?