Thermal behavior and kinetics of the pyrolysis of the coal used in the COREX process

Thermal behavior and kinetics of the pyrolysis of the coal used in the COREX process

Journal of Analytical and Applied Pyrolysis 104 (2013) 660–666 Contents lists available at ScienceDirect Journal of Analytical and Applied Pyrolysis...

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Journal of Analytical and Applied Pyrolysis 104 (2013) 660–666

Contents lists available at ScienceDirect

Journal of Analytical and Applied Pyrolysis journal homepage: www.elsevier.com/locate/jaap

Thermal behavior and kinetics of the pyrolysis of the coal used in the COREX process Shengfu Zhang ∗ , Feng Zhu, Chenguang Bai, Liangying Wen, Chong Zou College of Materials Science and Engineering, Chongqing University, Chongqing 400044, PR China

a r t i c l e

i n f o

Article history: Received 19 November 2012 Accepted 27 April 2013 Available online 6 May 2013 Keywords: Coal Pyrolysis Thermal behavior Evolved gas species Kinetics

a b s t r a c t The pyrolysis characteristics of the coal used in the COREX process were investigated by thermogravimetric–mass spectrometric analytical technology. Firstly, thermal behavior of Xinglongzhuang coal and Datong coal was studied under an argon atmosphere at a heating rate of 20 ◦ C/min. Then, the effect of heating rate on pyrolysis of Xinglongzhuang coal was analyzed. In addition, the kinetics of the pyrolysis process was calculated for two coal samples. Results show that the pyrolysis process of the two coal samples has similar characteristics which could be divided into four stages, and the main pyrolysis temperature range of this coal type is from 300 ◦ C to 800 ◦ C. The heating rate mainly influences the primary pyrolysis stage of the coal, while the maximum weight loss rate and corresponding temperature change with increasing of heating rate. The evolved gas species vary as the heating rate increases, and the evolution of CO below 800 ◦ C is similar to that of CO2 which can be attributed to the decomposition of the same functional groups. The second order reaction and third order reaction can give a better representation of the main pyrolysis process with the apparent activation energy ranging from 100 kJ/mol to 200 kJ/mol. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved.

1. Introduction The COREX process is developed as an alternative to the traditional blast furnace due to the scarcity of coking coal and the soar of coke price, as well as the environmental pressure [1,2]. It can use non-coking coal directly and less pollutants are produced compared with traditional blast furnace process. The present operation status shows that the coal consumption in the COREX process is comparatively high with a fuel rate (noncoking coal and coke) of 700–1000 kg/THM (tone of hot metal) [3,4]. In the COREX process, lump coal is charged from the top of the melting gasifier furnace with temperature of 1050 ◦ C, after rapid drying and devolatilization, the produced semicoke descends to form the fixed bed where the final reduction of iron occurs. The accompanying evolved reducing gases are used for the pre-reduction of the iron ore in the shaft furnace. So, the properties and pyrolysis behavior of the coal have considerable effect on the energy consumption and the operating status of the COREX process [5,6]. The pyrolysis of coal is the first step in most coal conversion processes, such as carbonization, gasification, or combustion of coal [7–11]. However, because of the complexity of structure and the heterogeneity of components, the determination of the pyrolysis

∗ Corresponding author. Tel.: +86 023 65112631; fax: +86 023 65112631. E-mail address: [email protected] (S. Zhang).

process of coal is very difficult, which consists of a lot of physical changes and chemical reactions. In general, two processes occur competitively when coal is heated. One is the depolymerization process through which gas, water vapor, and tar are formed. The other is the condensation or repolymerization process, which leads to char/coke formation [12]. Pyrolysis process of coal is greatly impacted by various factors, which includes intrinsic factors of coal and external factors. Generally speaking, the intrinsic factors covers structure, composition, particle size [13] and rank of coal [14], while the external factors include temperature [15], pressure [16], heating rate [17] and reaction atmosphere, et al. [18]. Many researchers studied the affecting factors on the coal pyrolysis [19–22]. Mae et al. studied the relationship of the yield of pyrolysis products with coal structure [19]. It was observed that tar yield correlated well with the fraction of aliphatic carbon and the amount of hydrogen bonding determined from Fourier transform infrared spectra. Morris carried out pyrolysis runs on different particle sizes, and the empirical correlations have been established for the evolution rates of hydrogen, carbon monoxide, and methane as a function of particle size and instantaneous temperature [20]. Kök also researched the effect of particle size on coal pyrolysis by thermogravimetry method [21]. Chen et al. studied the pyrolysis and gasification behavior of different Chinese coal samples at ambient pressure and 3 MPa, respectively. The results showed that increasing pressure suppressed the primary pyrolysis, while the secondary pyrolysis of coal particles was promoted [22]. Although a lot of research on coal pyrolysis was accomplished, systematic and theoretical analyses

0165-2370/$ – see front matter. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jaap.2013.04.014

S. Zhang et al. / Journal of Analytical and Applied Pyrolysis 104 (2013) 660–666

on the thermal behavior and kinetics of coal used in the COREX process are seldom reported, and pyrolysis characteristics of coal is of great importance to the COREX process. In this work, two Chinese coals, Xinglongzhuang coal and Datong coal, from the COREX industry, were chosen as samples. Thermogravimetric (TG) and mass spectrometry (MS) were used to investigate the weight loss behavior and evolution of gas species. The effect of heating rate on the coal pyrolysis was studied, as well as the kinetics of the pyrolysis was calculated for the coal samples. 2. Experimental

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Table 1 Characteristics of the coal samples. Parameters Proximate analysis (%, air-dried basis) Moisture Volatile matter Fixed carbon Ash Ultimate analysis (%, dry basis) Carbon Hydrogen Nitrogen Sulfur Oxygen

XLZ

DT

4.0 33.6 53.9 8.5

8.3 28.8 49.7 13.2

76.0 4.7 1.1 8.8 0.6

69.6 4.1 0.8 10.7 0.3

2.1. Sample preparation Two Chinese coals, Xinglongzhuang coal (XLZ) and Datong coal (DT), from a COREX industry, were chosen for this study. Both of the coal samples were prepared by grinding and sieving (<0.075 mm). The proximate analysis and ultimate analysis are shown in Table 1. 2.2. Experimental apparatus and procedures Pyrolysis experiments were performed using a thermogravimetric analyzer (TG, SETARAM SETSYS Evolution 16/18, France). In this study, ±10 mg of coal sample was placed in a ceramic crucible and heated from room temperature to 1100 ◦ C at a heating rate of 10, 20 and 30 ◦ C/min using argon as carrier gas at a constant flow rate of 50 ml/min. The argon flow rate could ensure an inert atmosphere around the sample during the experiment, while the small amount of sample and the slow heating rate ensured that heat transfer limitations could be ignored. Therefore, the weight loss of

coal samples could be recorded in different pyrolysis time intervals with increasing of temperature. A quadruple mass spectrometer (MS, PFEIFFER VACUUM OMNI star, QMA 200M, Germany), linked to the above thermogravimetric analyzer with a stainless steel tube capillary, was used to measure the evolved gases. The MS operated on a 100 eV ionization energy and used a Channeltron detector (1000 V). The evolved gas is ionized by electron impact, and the ion current data for a specific m/z (the mass-to-charge ratio) species was analyzed. The number of m/z signals selected gave a temporal resolution of 20 s. Although a qualitative analysis was performed in this work, the intensities recorded by the MS had to be repetitive in order that the intensity of the peaks of the different samples could be compared. In this work, the measured gases included H2 O, CH4 , CO, CO2 , H2 , and their signals were normalized to that from 1 mg of the samples because the sample mass of each experiment was different.

Fig. 1. Weight loss and released gas species of the coals at a heating rate of 20 ◦ C/min: (a) XLZ coal and (b) DT coal.

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Table 2 Weight loss of XLZ coal and DT coal at different stages (%). Sample

XLZ DT

Temperature range (◦ C)

Total

∼300

300–600

600–800

800–1100

1.66 1.62

27.64 21

5.13 6.07

1.65 2.73

36.08 31.42

3. Results and discussion 3.1. Thermal behavior of two coal samples In order to compare the differences of the pyrolysis characteristics of XLZ coal and DT coal, pyrolysis of the two coals were conducted under an argon atmosphere at a heating rate of 20 ◦ C/min. The weight loss of coal and released gas species are shown in Fig. 1. The pyrolysis of these two coals could be divided into four stages according to the weight loss rate and released gas species. The initial decrease in weight is due to water release where temperature is below 300 ◦ C, which occurs in all kinds of coals [12,14]. The second stage is the primary pyrolysis of coal, as the temperature increases from 300 ◦ C to 600 ◦ C, the weight decreases fastly with the maximum weight loss rate of −0.27%/◦ C for XLZ coal and −0.17%/◦ C for DT coal. The temperature corresponding to the maximum weight loss of these two coals is nearly the same with value about 440 ◦ C. A large amount of gas species such as H2 O, CO and CO2 are released in this stage, which indicate that they come from the same reaction process [23]. The evolution of CH4 mainly occurs at temperature from 400 ◦ C to 800 ◦ C, which is quite similar to the results researched by Arenillas [14]. The third stage is the secondary pyrolysis during which CO, CO2 and H2 are released, the gas species are mainly from the cracking of heavy hydrocarbons [24]. As the temperature continues increasing, the weight variation is very small and less amount of gas species are released. It can also be seen from Fig. 1(a) and (b) that the pyrolysis process of XLZ coal and DT coal has similar characteristics. The weight loss of these two coals at different stages is shown in Table 2 which shows that the total weight loss of XLZ coal is higher than DT coal, because XLZ coal has a higher volatile content as shown in Table 1. 3.2. Effect of heating rate on thermal behavior of XLZ coal Studies conducted on the influence of heating rate indicated an increase in thermal lag occurs on the pyrolysis of coal as the heating rate increases [12,25]. As the pyrolysis process of XLZ coal and DT coal has similar characteristics, the influence of heating rate on this type of coal is studied on XLZ coal. The weight loss and weight loss rate of the XLZ coal at different heating rates are shown in Fig. 2. Although the pyrolysis process of this coal type with increase of temperature is less influenced by heating rate, yet small differences can be seen from the details of the primary pyrolysis ranging from 400 ◦ C to 500 ◦ C, which indicate that heating rate mainly influences on the primary pyrolysis stage. Both of the curves of weight loss and weight loss rate versus temperature shift toward the right as the heating rate increases. The maximum weight loss rate increases and the corresponding temperature rises with the increase of temperature. It can also be seen from Fig. 2 that the final weight is about 64%, which does not change with the heating rate. This is due to the fact that the mechanism of cleavage-bond breaking and repolymerization are in equilibrium, which is not relevant with the pyrolysis conditions [25]. The influence of heating rate on the tar and volatile yields has already been reported [26,27]. In this study, the relation between heating rate and evolution of gas species is investigated. Fig. 3 shows the gas species released from XLZ coal at different heating

Fig. 2. Weight loss and weight loss rate of the XLZ coal at different heating rates.

rates. It is obvious that the gas releasing rate increases with the increase of heating rate. However, the gas evolution temperature range and peak temperature are not changing significantly which is different from the results of Seo [12,28]. It indicates that the thermal lag effect is not evident on the gas evolution on this kind of coal. The evolution of H2 O at lower temperatures is due to water release, which reaches the first peak at 100 ◦ C. While at higher temperatures, H2 O is mainly from the hydroxyl groups, which reaches the second peak at 440 ◦ C. The evolution of CH4 commences at 320 ◦ C and reaches a peak at 500 ◦ C. CH4 mainly forms from the hydroaromatic and hydroxyl groups [29]. The evolution of H2 occurs at 300 ◦ C, and reaches the peak at 730 ◦ C. H2 mainly comes from the condensation of aromatic structures and the decomposition of heterocyclic compounds [30]. The evolution of CO and CO2 is similar below 800 ◦ C as shown in Fig. 3(d) and (e). The evolution of these two gases at lower temperatures is mainly from carboxyl and carboxylate groups, at high temperatures, are mainly formed from ether structures, quinones and oxygen-bearing heterocycles, and also carbonates decompose at this temperature range [14]. It can be seen that the first peak temperature shifts to the left as the heating rate increases, however, the second peak shifts to the right with the increase of heating rate. From the evolution of CO and CO2 at temperatures from 500 ◦ C to 600 ◦ C, the shoulder peak of CO becomes larger as the heating rate increases. On the contrary, the shoulder peak of CO2 becomes unapparent. It suggests that the products of coal pyrolysis may change with the increase in heating rate.

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Fig. 3. Evolution of gas species of the XLZ coal at different heating rates.

3.3. Kinetic analysis for the pyrolysis process of two coal samples As the pyrolysis of coal is complex, the apparent activation energy is obtained according to the weight loss of coal. In addition, previous studies indicated that the primary pyrolysis temperature range of XLZ coal and DT coal is from 300 ◦ C to 600 ◦ C, while the secondary pyrolysis occurs at temperature from 600 ◦ C to 800 ◦ C. So the kinetic study is focused on the primary pyrolysis and the

secondary pyrolysis of the coal. The conversion rate is defined as the mass ratio of pyrolyzed coal at time t to the initial coal as follows: x=

W0 − Wt × 100% W0 − Wf

(1)

where W0 is the original mass of the coal sample, Wt is the mass at time t and Wf is the final mass at the end of pyrolysis.

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The reaction rate of coal pyrolysis can be described as follows: dx = k(T )f (x) dt

(2)

where t is the pyrolysis time, k(T) is the rate constant and f(x) is a kinetic model-dependent function. The rate constant k(T) is expressed using the Arrhenius equation as follows:



k(T ) = A exp −



E RT

(3)

where A, E, R and T are the pre-exponential factor, apparent activation energy, universal gas constant, and gas temperature, respectively. In non-isothermal conditions, the constant heating rate ˇ is as follows: ˇ=

dT dt

(4)

So, in non-isothermal and heterogeneous conditions, the kinetic equation of coal pyrolysis is transformed into the following expression,



E dx A = exp − RT dT ˇ



f (x)

(5)

The integral method is adopted to solve the kinetic equation, and the integral form of the kinetics equation for pyrolysis of coal is as follows:



x

G(x) = 0

dx A = f (x) ˇ





T

exp − T0

E RT

 dT

(6)

By application of Coats–Redfern’s approximation [31], the following equation is obtained: ln

 G(x)  T2

= ln

 AR  ˇE



E RT

(7)

Then, by assuming G(x), a plot of ln[G(x)/T2 ] versus 1/T is obtained. The activation energy is obtained from the slop of the fitted plot, the pre-exponential factor is determined from the intercept of the plot. The kinetic model-dependent function used in this work is as follows: f (x) = (1 − x)n

(8)

Different reaction orders are considered (n = 1, 2, 3) for comparing the kinetic parameters, thus Eq. (7) can be described as follows:

 ln(1 − x) 

ln −



T2

= ln

1 − (1 − x)1−n ln − T2

 AR 



ˇE = ln



E RT

 AR  ˇE

(n = 1) E − RT

Fig. 4. Plots of ln[G(x)/T2 ] versus 1/T for the primary pyrolysis of XLZ coal and DT coal.

is higher than that obtained by Arenillas with a value between 70 kJ/mol and 100 kJ/mol. The figures also show that the apparent activation energy of the secondary pyrolysis is higher than the primary pyrolysis. For the pyrolysis of coal, high activation energy

(9) Table 3 Kinetic parameters for the primary pyrolysis of XLZ coal and DT coal.

(n = / 1)

(10)

Figs. 4 and 5 show the plots of ln[G(x)/T2 ] versus 1/T of the XLZ coal and DT coal pyrolysis at heating rate of 20 ◦ C/min. Liu et al. found that the reaction of coal pyrolysis cannot be described by one consecutive first order reaction [32]. In this work, the kinetic parameters of the two stages are obtained individually with the conversion x calculated from each stage. It can be seen that the second order reaction and third order reaction give a better representation of the main pyrolysis process of XLZ coal and DT coal with the R2 greater than 0.99, the result is consistent with the report of Arenillas [33]. Kinetic parameters for pyrolysis of the XLZ coal and the DT coal at a heating rate of 20 ◦ C/min obtained from different reaction orders are shown in Tables 3 and 4. The activation energy of different coal ranks and calculated by different methods have been compared [34,35]. It can be seen that the activation energy and pre-exponential factor increase with the increase of reaction order, and the value varies between the XLZ coal and DT coal. The apparent activation energy ranges from 100 kJ/mol to 200 kJ/mol, which

Sample XLZ

DT

a

Reaction order n=1 n=2 n=3 n=1 n=2 n=3

E (kJ/mol)

A (min−1 )

R2 a

86.29 127.34 178.29 73.07 108.57 152.59

4.03 × 10 8.48 × 108 9.41 × 1012 3.34 × 104 2.66 × 107 8.80 × 1010

0.956 0.992 0.994 0.961 0.996 0.997

5

R2 ,correlation coefficient.

Table 4 Kinetic parameters for the secondary pyrolysis of XLZ coal and DT coal. Sample

Reaction order

E (kJ/mol)

A (min−1 )

R2 a

XLZ

n=1 n=2 n=3 n=1 n=2 n=3

126.64 184.87 256.89 121.60 178.91 249.93

1.84 × 106 6.62 × 109 1.39 × 1014 9.09 × 105 2.90 × 106 5.32 × 1013

0.973 0.992 0.984 0.956 0.991 0.992

DT

a

R2 , correlation coefficient.

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activation energy of secondary pyrolysis is higher compared to the primary pyrolysis. Acknowledgement This work was supported by the National Natural Science Foundation of China (Grant No. 51104193). References

Fig. 5. Plots of ln[G(x)/T2 ] versus 1/T for the secondary pyrolysis of XLZ coal and DT coal.

implies that the reaction needs more energy from the surroundings [36]. 4. Conclusions The pyrolysis characteristics of the coal used in the COREX process were investigated by thermogravimetric–mass spectrometric analytical technology. The obtained conclusions are as follows: (1) The pyrolysis process of the XLZ coal and DT coal has similar characteristics which could be divided into four stages according to the weight loss rate and released gas species. The main pyrolysis temperature range of the XLZ coal and the DT coal is from 300 ◦ C to 800 ◦ C with the primary pyrolysis occurs from 300 ◦ C to 600 ◦ C and secondary pyrolysis from 600 ◦ C to 800 ◦ C.In addition, the total weight loss of the XLZ coal is higher than that of the DT coal. (2) Heating rate mainly influences the primary pyrolysis stage, and both of the curves of weight loss and weight loss rate versus temperature shift toward the right as the heating rate increases, while the final weights are all about 64%, which do not change with heating rate. The gas release rate increases with increasing of heating rate. The evolution of CO and CO2 is similar below 800 ◦ C, which can be attributed to the decomposition of the same functional groups. (3) The second order reaction and third order reaction can give a better representation of the main pyrolysis process for the XLZ coal and the DT coal, and the apparent activation energy ranges from 100 kJ/mol to 200 kJ/mol. It is also found that the apparent

[1] A.B. Usachev, V.A. Romenets, V.E. Lekherzak, A.V. Balasanov, Modern processes for the coke-less production of iron, Metallurgy 46 (2002) 117–130. [2] A.G. Shalimov, Corex process for making high-quality steels at mini-mills, Metallurgy 44 (2000) 35–39. [3] W.G. Li, Analysis on operation status and technical problems of COREX3000, Baosteel Technology 1 (2008) 11–18. [4] P.P. Kumar, D. Gupta, T.K. Naha, S.S. Gupta, Factors affecting fuel rate in Corex process, Ironmaking & Steelmaking 33 (2006) 293–298. [5] P.P. Kumar, B. Raju, M. Ranjan, Characteristics of coal required for superior performance of Corex ironmaking, Ironmaking & Steelmaking 38 (2011) 412–416. [6] P.P. Kumar, S.C. Barman, B.M. Reddy, V.R. Sekhar, Raw materials for Corex and their influence on furnace performance, Ironmaking & Steelmaking 36 (2009) 87–90. [7] M.D. Casal, C.S. Canga, M.A. Díez, R. Alvarez, C. Barriocanal, Low temperature pyrolysis of coals with different coking pressure characteristics, Journal of Analytical and Applied Pyrolysis 74 (2005) 96–103. [8] T.K. Das, Evolution characteristics of gases during pyrolysis of maceral concentrates of Russian coking coals, Fuel 80 (2001) 489–500. [9] K.H. Van Heek, Progress of coal science in the 20th century, Fuel 79 (2000) 1–26. [10] D.G. Osborne, J.M. Graham, L.K. Elliott, New coal utilization technologies, Minerals Engineering 9 (1996) 215–233. [11] P.R. Solomon, T.H. Fletcher, R.J. Pugmire, Progress in coal pyrolysis, Fuel 72 (1993) 587–597. [12] D.K. Seo, S.S. Park, Y.T. Kim, J.H. Wang, T.U. Yu, Study of coal pyrolysis by thermogravimetric analysis (TGA) and concentration measurements of the evolved species, Journal of Analytical and Applied Pyrolysis 92 (2011) 209–216. [13] L. Cui, W. Lin, J. Yao, Influences of temperature and coal particle size on the flash pyrolysis of coal in a fast-entrained bed, Chemical Research in Chinese Universities 22 (2006) 103–110. [14] A. Arenillas, F. Rubiera, J.J. Pis, Simultaneous thermogravimetric–mass spectrometric study on the pyrolysis behaviour of different rank coals, Journal of Analytical and Applied Pyrolysis 50 (1999) 31–46. [15] N. Qiu, H. Li, Z. Jin, Y. Zhu, Temperature and time effect on the concentrations of free radicals in coal: evidence from laboratory pyrolysis experiments, International Journal of Coal Geology 69 (2007) 220–228. [16] M.D. Casal, C.S. Canga, M.A. Díez, Low-temperature pyrolysis of coals with different coking pressure characteristics, Journal of Analytical and Applied Pyrolysis 74 (2005) 96–103. [17] L.P. Wiktorsson, W. Wanzl, Kinetic parameters for coal pyrolysis at low and high heating rates—a comparison of data from different laboratory equipment, Fuel 79 (2000) 701–716. [18] Q. Zhou, H. Hu, Q. Liu, S. Zhu, R. Zhao, Effect of atmosphere on evolution of sulfur-containing gases during coal pyrolysis, Energy Fuels 19 (2005) 892–897. [19] K. Mae, T. Maki, H. Okutsu, K. Miura, Examination of relationship between coal structure and pyrolysis yields using oxidized brown coals having different macromolecular networks, Fuel 79 (2000) 417–425. [20] R.M. Morris, Effect of particle size and temperature on volatiles produced from coal by slow pyrolysis, Fuel 69 (1990) 776–779. [21] M.V. Kök, E. Özbas, O. Karacan, C. Hicyilmaz, Effect of particle size on coal pyrolysis, Journal of Analytical and Applied Pyrolysis 45 (1998) 103–110. [22] H. Chen, Z. Luo, H. Yang, F. Ju, S. Zhang, Pressurized pyrolysis and gasification of Chinese typical coal samples, Energy Fuels 22 (2008) 1136–1141. [23] S. Niksa, Theory for rapid coal devolatilization kinetics. 7. Predicting the release of oxygen species from various coals, Energy Fuels 10 (1996) 173–187. [24] M.A. Serio, D.G. Hamblen, J.R. Markham, P.R. Solomon, Kinetics of volatile product evolution in coal pyrolysis: experiment and theory, Energy Fuels 1 (1987) 138–152. [25] G. Di Nola, W. De Jong, H. Spliethoff, TG-FTIR characterization of coal and biomass single fuels and blends under slow heating rate conditions: partitioning of the fuel-bound nitrogen, Fuel Processing Technology 91 (2010) 103–115. [26] J. Gibbins-Matham, R. Kandiyoti, Coal pyrolysis yields from fast and slow heating in a wire-mesh apparatus with a gas sweep, Energy Fuels 2 (1988) 505–511. [27] C. Sathe, Y. Pang, C.Z. Li, Effects of heating rate and ion-exchangeable cations on the pyrolysis yields from a Victorian brown coal, Energy Fuels 13 (1999) 748–755. [28] D.K. Seo, S.S. Park, J.H. Wang, T.U. Yu, Study of the pyrolysis of biomass using thermo-gravimetric analysis (TGA) and concentration measurements of the evolved species, Journal of Analytical and Applied Pyrolysis 89 (2010) 66–73. [29] S. Charpenay, M.A. Serio, R. Bassilakis, P.R. Solomon, P. Landais, Influence of maturation on the pyrolysis products from coals and kerogens. 2. Modeling, Energy fuels 10 (1996) 26–38. [30] K.H. Van Heek, W. Hodek, Structure and pyrolysis behaviour of different coals and relevant model substances, Fuel 73 (1994) 886–896.

666

S. Zhang et al. / Journal of Analytical and Applied Pyrolysis 104 (2013) 660–666

[31] A.W. Coats, J.P. Redfern, Kinetic parameters from thermogravimetric data, Nature 68 (1964) 201. [32] Q. Liu, H. Hu, Q. Zhou, S. Zhu, G. Chen, Effect of inorganic matter on reactivity and kinetics of coal pyrolysis, Fuel 83 (2004) 713–718. [33] A. Arenillas, F. Rubiera, C. Pevida, J.J. Pis, A comparison of different methods for predicting coal devolatilization kinetics, Journal of Analytical and Applied Pyrolysis 58 (2001) 685–701.

[34] A. Sarwar, M. Nasiruddin Khan, K.F. Azhar, Kinetic studies of pyrolysis and combustion of thar coal by thermogravimetry and chemometric data analysis, Journal of Thermal Analysis and Calorimetry 109 (2012) 97–103. [35] S. Sharma, A.K. Ghoshal, Study of kinetics of co-pyrolysis of coal and waste LDPE blends under argon atmosphere, Fuel 89 (2010) 3943–3951. [36] L. Zhou, T. Luo, Q. Huang, Co-pyrolysis characteristics and kinetics of coal and plastic blends, Energy Conversion and Management 50 (2009) 705–710.