A05130108

IOSR Journal of Engineering (IOSRJEN) www.iosrjen.org
ISSN (e): 2250-3021, ISSN (p): 2278-8719
Vol. 05, Issue 01 (January. 2015), ||V3|| PP 01-08
International organization of Scientific Research 1 | P a g e
New Approach of Retorting of Huadian Oil Shale in Order to
Reduce CO and CO2 Emissions
Guy Roland Nguimbi1
,Sun Youhong1
, Phiri Cryton2
1
Jilin University, No. 6 Ximinzhu Street ,Changchun 130026,China
2
College of Earth Science, Jilin University, Changchun 130061, China,
Abstract: - The combustion of oil shale can extract the kerogen and later transform the kerogen in to heavy oil
.The only drawback of this technique is the decarbonation of mineral matter in shale by high temperatures. This
process causes 60% to 70% of the CO2 and CO emissions. The decarbonation of CaCO3 and oxidation of fixed
carbon causes the formation of CO2 and CO .The aim of this study is to avoid the decarbonation by decreasing
the temperature in the retort of combustion. During this experiment we tested the impact of two parameters:
Firstly, decreasing the quantity of fixed carbon in the medium of combustion and secondly, increasing the
amount of carbonates which acts as heat dissipater. It is demonstrated that increasing the amount of carbonates
may only decrease the medium of combustion to temperatures not lower than 830°C which is still so high to
avoid decarbonation. Moreover, the temperature can be decreased to avoid decarbonation by reducing the
quantity of fixed carbon .When the medium reached the low temperatures, nearly all the fixed carbon is
oxidized. In high temperatures decarbonation of the mineral matter present in oil shale produce huge emissions
of CO2.We show, in this paper a new approach to controlling the temperature of the combustion to prevent this
decarbonation .
Keywords: - decarbonation, Electrical combustion , Huadian , Oil shale
I. INTRODUCTION
As the demand for energy is greatly increasing throughout the world, unconventional oil shale is
regarded as a potential energy source to substitute oil and natural gas. And this has attracted researchers’
attention for many years [1].The reserve for oil shale stands out as very important source of substitutes for
petroleum. [2,3] Oil obtained from shale is similar products to those obtained from petroleum. [4] The thermal
decomposition of oil shale, known as retorting or pyrolysis, converts the shale’s solid organic material into
liquid and gas. [5,6] This process on the other hand is a source of severe environmental pollutions.[7,8] During
the recent past 10 years, one of the main problems of the oil shale industry has been to find an effective method
of extracting Oil from oil shale with reduced emissions of large quantities of CO2 from decarbonation. [9]
The major problem to oil shale industry is to find a process to recover oil from shale with less or without
emission of CO2. Recently the retorting of oil shale has attracted the interest of many researchers [10,11,12]
,although most of research studies are concentrated on the method of retorting and the parameters of retorting
oil shale. [12,13] However, our study focuses on the method to reduce the quantity of CO2 and CO emission
during retorting oil shale by controlling the temperature.
Huadian Oil shale composition has been studied by many researchers [10,14].Oil shale is a sedimentary rock
consists of organic material (kerogen) [15] ,bitumen and inorganic matrix of quartz, Feldspars, clay and
different types of carbonates (calcite , dolomite), pyrite and trace elements (Fe, V, Mo, Ni, Zn).
The decomposition of carbonate minerals such as calcite (CaCO3) and dolomite (MgCO3), during oil shale
retorting are responsible for CO2 emission. In this work, we refer these carbonate minerals as CaCO3.
The combustion of carbonates has been studied by Jeremy [9] and shown below:
Calcite:
CaCO3 → CaO + CO2 (1)
CaCO3+ SiO2→ CaSiO3 + CO2 (2)
Dolomite:
CaMg(CO3)2→ CaO + MgO + 2CO2 (3)
CaMg(CO3)2 + 2SiO2 → CaMgSi2O6 +2CO2 (4)

New Approach of Retorting of Huadian Oil Shale in Order to Reduce CO and CO2 Emissions
The above reactions occur when temperatures are up to 800°C.
Our objective is to reduce the temperature during retorting of Huadian oil shale, in order to avoid
decarbonation of CaCO3 which produce CO2 and CO emissions. Controlling the temperature is necessary
because during the heating process, the high temperature decarbonates the large quantities of mineral matter
present in oil shale.
We demonstrated in this paper a new approach for controlling the temperature of the combustion to prevent this
decarbonation. We have also attempted to show the influence of the proportions of calcium carbonate and the
fixed carbon oxidization has on combustion.
We want especially to answer the following question: is it possible to extract oil in shale without
decarbonating the calcium carbonate (CaCO3)?If yes, can we consider it as an alternative to the mixture of oil
shale, calcium carbonate and sand to decrease the combustion temperature and prevent decarbonation and
facilitate the Carbonation of CaO. This research concerns a process and an apparatus for extracting the kerogen
from oil shale without negatively affecting the environment.
Martins [16,17] reported that the production of oil from oil shale by the pyrolysis process consists of
many reactions including drying, devolatilization, FC oxidation and decarbonation of CaCO3. However, Fixed
carbon (FC) oxidation and decarbonation of CaCO3 are the most important reaction for the conversion of
kerogen to bitumen and emission of CO2 and CO during combustion of oil shale. Fixed Carbon Oxidation: this
reaction has so many intermediate reactions which results in the production of CO2 and CO. This reaction have
been investigated by several researchers [18,9] it occur between 300°C and 550℃ according to the simplified
reactions below:
C + O2 → CO2 (5)
C(s)+ 1/2O2(g) → CO (g) (6)
½O2(g) + CO (g) →CO2(g) (7)
C(s) + CO2 (g) →2CO (g) (8)
CO(g) + ½O2(g) →CO2(g) (9)
Under 500℃ the combustion of oil shale generates: volatile matter,CaCO3,and inert matter and CO2.The CO2
produced under this temperature represents 30% of the total CO2 produced compared to the normal combustion.
Less than 500°C the pyrolysis of oil shale is done without decarbonation.
Based on mass and flue-gas analysis it is possible to determine the the proportion of FC oxidized to CO, and the
fraction of CaCO3 that is decarbonated.
Decarbonation of CaCO3 and carbonation of CaO;This reaction plays a major role during combustion of oil
shale. Furthermore the decarbonation of CaO undergoes carbonation to CaCO3.The carbonation of CaO
consumes CO2.[19]
In this work we demonstrate the decarbonation of CaCO3 to produce CaO that in inturn undergoes carbonation
to CaCO3 .This theory is only proposed here for the interpretation of our experimental results. By reducing the
temperature when the temperature is decreased we can totally avoid the decarbonation reaction and remain with
the FC oxidation.
The decarbonation reaction of CaCO3 is written as:
CaCO3(s) → CaO(s) + CO2 (g) (10)
The carbonation reaction has been studied for a long time [20] according of the following reaction:
CaO(s) + CO2 (g) → CaCO3(s) (11)
This reaction of decarbonation of CaCO3 occur above 750°C [21].

0.01
0.1
1
10
500 600 700 800 900 1000
Pressure(atm)
Temperature (ºC)
CaCO3 → CaO + CO2
CaO + CO2 → CaCO3
Figure 3. Equilibrium pressure in the temperature of CO2 over CaCO3.Modified after [21]
This invention concerns a process and an apparatus for extracting the oil and gas from oil shale without negative
environmental effects.
II. EXPERIMENTAL
1. Materials
The investigated Oil shale samples were obtained from Huadian area located in Jilin province,
northeast, China, Results of the proximate analysis and ultimate analysis of the sample are shown in table 1.
The oil shale blocks pass through crushing and grinding operations to reduce the particle sizes. In the crushing
stage the rocks are reduced to about 0.5-2 cm .After grinding, the particles are equal or inferior to 2 mm. The
Fischer assay oil yield of Huadian oil shale is between 8 to 18 %. [22, 23, 14]
Table 1. Analysis result of Huadian oil shale by weight %
Proximate analysis Ultimate analysis
Vad Mad FCad Aad Cad Had Oad Nad Sad
31.75 12.62 4.86 50.79 64.57 8.33 14.74 1.49 1.84
Proximate analysis was carried out was according to (GB/T 212-2008): the National Standard method of China
for coal and analysis ultimate analysis was made by the element analyzer (CE440, EAI).
2. Experimental device
Figure 2. Is a schematic block diagram of the experimental apparatus. The experiments were conducted
with a setup that consists of an iron-steel cylindrical body with an inner diameter of 25 cm and height of 35 cm
that houses the samples. In the top of the cylindrical body, inserted one stem of heaters (1000 W), and this
heater was connected to a temperature controller to increase the temperature of the system. The temperatures
were controlled to obtain the desired retorting temperature and monitored by digital temperature controller.
The two thermocouples are placed from the center of the tube heater T1 and T2 located at the top r=0 cm and
r=12cm (Fig .2), making it possible to measure the temperature around the cell at different distance .This reveals
whether the combustion front progresses or not as a vertical surface., and connected to the temperature
controller to continuously record temperature values. Then, the sample holder was placed in another cylindrical
cell, which has a 45 cm height and 35cm inner diameter. To minimize the heat losses, the space between two
cylinders was filled by crushed perlite (low thermal conductivity). This installation is capable to control the
temperature. The cylindrical body is pierced with one pipe on the underside that can recover the oil, water and
gas by simple steam oil in graduated test tube. The products are cooled at the exit of the reactor with a direct
water quench and flow to a container where the first gas-liquid separation takes place.

Figure 2.Schematic diagram of the fixed bed reactor
III. PROCEDURE
We used the electrical heating to heat oil shale during whole experiment. . The heating rate and final
temperature were controlled. During our experiments the gas was collected using gas bags during pyrolysis time
.The pyrolysis gas composition was analyzed. Oil shale sample was placed in four drawers.
Both the gas analyzer and the temperature controller were connected to the computer. Two experiments in the
same conditions were carried out all the time .the experimental work follows the detail below. All detail about
composition of mixture is in (Fig.3) and the experimental results are in (Table 2).
We used reference experiment in (Fig 3) to make Thermogravimetric Analysis (TGA).
Figure 3. The composition of the mix in different experiment

Table 2. Experimental conditions and results for all experiments
No.
Experimental conditions Results
Oil
Shale %
Sand %
Added
CaCO3 %
T/°C FC
Oxidation
%
CaCO3
decarbonation
% CO % CO2 %
reference 100 0 0 1100 98.6. 98.2 6.25 18.4
1 50 50 0 1017 97.8 93 6 18
2 50 40 10 1037 97.0 95.0 7.94 18.6
3 50 25 25 900 96.4 69.0 6.20 22.0
4 50 00 50 820 96.6 61.4 5.97 25.2
5 44 53 03 750 96.4 58.1 4.01 15.6
6 39 56 05 720 95.9 21.4 3.7 12.4
7 30 61 09 640 95.6 8.20 3.6 7.8
8 25 64 11 590 95.2 7.6 3.2 6.2
Measurements before start out: Mass of the medium .Measures after the experiment: Final mass of the medium,
color of the bed and quantities of oil recovered and gas (CO2 and CO).The gases collected from micro-sampling
device were analyzed using a Peak Performer 1 FID [24] .Two species were chosen to be separated: CO, which
represents one gas formed only by oil shale devolatilization and oxidation of Fixed Carbon .CO2 that is formed
during oil shale devolatilization, by decarbonation of CaCO3.
IV. EXPERIMENTAL RESULTS AND DISCUSSION
1. TGA Analysis
Thermogravimetric Analysis (TGA) (Fig 4).is used as reference to monitor the weight of oil shale sample when
exposed to an increase in temperature. By exploiting the results we can characterize the kinetics of chemical
reactions of materials. TGA experiments were carried out with a heating ramp of 5°C /min up to 1100°C. The
several steps of decomposition of the shale sample are shown in (Fig. 4).
Figure 4. Thermogravimetric Analysis (TGA).

Subsequently both decarbonization and FC oxidation zone were estimated according to the transition period and
the speed of layer considered, as determined before (Fig 4.)Particular attention is paid to the fraction of CaCO3
that is decarbonated at the front passage and the fraction of carbon that is oxidized to CO and not CO2.
Two parameters influence the temperature during Huadian oil shale combustion namely: the fraction of fixed
carbon oxidized to CO and CO2 and the fraction of CaCO3 carbonate to CO2 .Thermocouple T1, a peak close to
1050°C.all the experimental result is reported in Table 2.
2. Influence of the fraction of calcium carbonate on the temperature
On the experiment 1,2,3 and 4 we study the influence of the fraction of calcium carbonate on the temperature.
And the (Fig 5) show the evolution of temperature during combustion as a function of the total mass of
CaCO3.By keeping the amount of FC to 4.86% we vary the amount of CaCO3 by adding CaCO3 from 12.62% to
63%.
The result for Table 3 showed that increasing the fraction of CaCO3 from 12.62% to 63% decreases the
temperature inside from 1100°C to 820°C . The temperature remained stable at 800°C even with the increase in
the quantity of CaCO3. At this temperature, only 29% of initially present carbonates are decarbonated. Indeed
when the temperature is above 800°C , the CaCO3 is decarbonated rapidly , whereas when the temperature is
less than or equal to 820°C it decarbonated slowly and behaves like an inert medium. At the temperature of
820°C or lower, the decarbonation of CaCO3 is not significant and the CaCO3 no longer acts as a heat sink but
instead, acts as an inert medium.
For these experiments, it is interesting to calculate the absolute quantity of CaCO3 that is decarbonated. The
values obtained for the whole experiment vary between 22 and 60% initial CaCO3 were nearly the same. It can
be concluded that the temperature can decarbonate up to 28% CaCO3. In the reference case, only 22% was
present, all of it was decarbonated, while in the other cases where CaCO3 was present in quantities larger than
28% mass, only this later quantity was converted. The remaining carbonates behaved as inert materials.
Figure 5.Variation of CaCO3 in different temperatures.
3. Influence of the temperature on decarbonation of carbonate
Fig.5 gives the effect of the temperature on the on decarbonation of CaCO3as a function of the total mass of
CaCO3.During experimental 1, 2,3 and 4 we vary the amount of CaCO3from 22% to 66% by added
CaCO3.The result for (Table 2). showed that increasing the fraction of CaCO3from 22% to 66% while the
amount of FC remains at 4.86%.decreases the temperature inside from 1100°C to 975°C .The temperature

remained stable at 900°C even with the increase in the quantity of CaCO3.This temperature is not low to avoid
the decarbonation .Indeed, when the temperature of the mixture is above 800 ° C, the CaCO3 decarbonate to
CO2 and fixed carbon oxidized to CO and CO2
If we describe the fraction of the decarbonatation according to the temperature,as shown in Figure 3, it can
observed that it gradually increases with temperature. At about 590 ° C, only 8% CaCO3 are decarbonated.
Table 3 shows the main result of this work. It is therefore possible to avoid CaCO3 decarbonation by keeping the
temperature lower to 590°C (Table 2).
4. Influence of the fixed carbon (FC) on the temperature.
Based on the experimental results 5,6,7 and 8 as reported in (Table 2 , Fig 6)we study the influence of the FC
on the temperature by changing the quantity and composition of the fixed carbon in mixture while the amount
of CaCO3 remains at 12.62%.
By decreasing fixed carbon from 4.86 to 1.86 % ,the temperature of the combustion was decreased from 820°C
to 562 °C .As a the temperature decreased, the FC oxidation kinetics slowed down and at 562°C only 12% of
the carbonates are decarbonated when almost all FC is oxidized., The temperature falls to 562°C , and only
12 % of the CaCO3 is decarbonated so It is therefore possible to avoid the decarbonation
Figure 6. Decarbonated fraction at different temperatures
Whatever the experimental conditions, even at the lower temperatures, no fixed Carbon left in the mixture after
combustion. It was found that 19% to 35% of fixed carbon was oxidized into CO and in CO2 .
V. CONCLUSION
These results provide the approach of pyrolysis oil shale without the decarbonate mineral and less CO2
emission. Its been clearly found that the composition (oil shale, sand and Carbonates) of the mixture influenced
the temperature during combustion of oil shale. Increasing the fraction of CaCO3 allow to reduce the
temperature of 1100℃ to 820°C but not low . The temperature is been decreased from 900°C to 562°C by
reducing the fraction of Fixed Carbon at 4.86% to 1.8%. At 590°C , the temperature combustion decarbonate
only 12% carbonate initially present and Fixed Carbon is oxidized .The percentage of Fixed Carbon oxidized
increased with temperature .During this work we show how to avoid CO2 by limiting the decarbonation of
CaCO3.
This work presents a promising method to extracting oil contained in oil shale without decarbonation of
minerals. These results provide one of the approaches to control a combustion temperature in the case of oil
shale.

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