Thermogravimetric analysis of gasification reactivity of coal chars with steam and CO2 at moderate temperatures

Fan, Daiming; Zhu, Zhengwang; Na, Yongjie; Qi, Lu

doi:10.1007/s10973-012-2838-9

Cited by 48 publications

(23 citation statements)

References 38 publications

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“…It can be calculated that the Hdaf/ Cdaf is 0.048. Zhundong coal was pyrolyzed in an electric heated horizontal tube furnace [11]. A continuous flow of pure N 2 was injected to the furnace during the heating process.…”

Section: Sample Preparationmentioning

confidence: 99%

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Zhang¹,

Zhu²

2015

Procedia Engineering

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Pyrolysis is the first stage reaction in the processes of coal thermochemical conversion. In this study, Zhundong coal is pyrolyzed in an electric heated horizontal tube furnace. The combustion and gasification of coal and char are affected by the surface area, pore structure and chemical factors. The structure properties of Zhundong coal and chars are characterized with X-ray diffraction (XRD), CO 2 adsorption isotherm, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM). XRD results indicate that, with pyrolysis temperature and time increasing, the stacking height (L c ) increases and then decreases, and the size of aromatic layer (L a ) of chars increases while the lattice plane spacing (d 002 ) almost stays unchanged. The specific surface area, pore volume, and average pore width are calculated, and the results show that the chars present more developed pore structure. FT-IR study reveals the presence of -OH, C=O, -CH, and C=C. The intensity of band of -OH group (3100-3600 cm -1 ), C=O group (1700 cm -1 ), C=C group (1600 cm -1 ), and C-H group (2800-3100 cm -1 ) decreases with the increase in the pyrolysis temperature and time. The above results indicate that the structure properties of chars are strongly dependent on heat treatment conditions, which is essential for the utilization of Zhundong coal.

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Section: Sample Preparationmentioning

confidence: 99%

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Zhang¹,

Zhu²

2015

Procedia Engineering

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“…The effect of temperature, partial and absolute pressure, and particle size on the reaction kinetics has been widely studied. [2][3][4][5][6][7][8][9][10][11][12] Main kinetic parameters such as an activation energy (E a ) and pre-exponential factor (A 0 ) are often determined by means of kinetic models. Widely-used models are the random pore model (RPM), [13] the volume reaction model (VM), [14] and the shrinking core model (SCM).…”

Section: Introductionmentioning

confidence: 99%

Brown coal char CO₂‐gasification kinetics with respect to the char structure part II: Kinetics and correlations

et al. 2018

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Coal's physical structure is known to affect high‐temperature coal conversion processes such as gasification or combustion. This paper is Part II of the study of brown coal char structural changes during gasification. Firstly, German Lusatian brown coal was gasified in a laboratory‐scale fluidized bed reactor in CO2 within a temperature range of 800–950 °C at atmospheric pressure. Then, physical structure properties were extensively evaluated by means of various techniques. Char specific surface area and its changes during gasification reaction were evaluated using N2 and CO2 physical adsorption techniques. Adsorption isotherms were also interpreted employing unconventional methods in order to obtain the specific surface areas of pores of different sizes. Gasification kinetics were evaluated employing three widely applied kinetic models: the random pore model (RPM), the volume reaction model (VM), and the shrinking core model (SCM). Finally, the instantaneous gasification reaction rate was correlated with the char structural properties at the corresponding conversion degrees. The closest linear correlation appeared between the gasification reaction rate and the specific surface area of mesopores (as determined by N2 adsorption). Furthermore, correlations of the other structural properties with char conversion are provided. Observed structural changes were compared with the assumptions of the kinetic models.

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“…Hou et al [25] reported the gasification reactivity of the Hailar lignite and the catalytic effects of the present ash using thermogravimetric analysis under N 2 /CO 2 ambience. Fan et al [26] studied the gasification reactivity of coal chars with steam and CO 2 at medium temperature ranges using thermogravimetric analysis. Everson et al [27] investigated high inertinite coals using equilibrium concentrations of reagents during mixed gas experiments.…”

Section: Introductionmentioning

confidence: 99%

Thermogravimetric and evolved gas analyses of high ash Indian and Turkish coal pyrolysis and gasification

Jayaraman

Gökalp

2015

J Therm Anal Calorim

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High ash coals from India and Turkey are investigated in this study. A coupled thermogravimetric analyzer and mass spectrometer system is used for the thermal decomposition characterization of the coal samples and the identification of the volatiles evolved during the various reaction regions. Coal samples are heated in argon, air, oxygen, steam and blended gas mixtures at the temperature range from 25 to 1250°C. The experiments are performed to study the pyrolysis, combustion and gasification characteristics of typical Indian and Turkish high ash coals. Thermogravimetry and derivative thermogravimetry studies are applied to measure the conversion level and half-life time of the coals/chars during and after pyrolysis. The maximum mass loss occurs during the devolatilization stage of coals at the temperatures from 350 to 700°C, where O 2 , CO 2 , CO, H 2 and a small amount of CH 4 are released. Coal particles start to react with steam and produce CO 2 , CO and H 2 when the temperature is increased above 750°C. The gasification reactions are completed around 950°C in steam and steam blended ambience. The reactivity of high ash coal chars mainly depends on reagents' and surrounding gases concentration and also the reaction temperature. The results indicate that the size effect of the char particles is minimal at high gasification temperatures. Char gasification rates determined by TG techniques under isothermal conditions in different reagent flow rates and size effect contribute to enhance the knowledge on high ash coal thermal characterization and gasification and, therefore, to establish the optimum operational conditions for syngas production from high ash coals.

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Thermogravimetric analysis of gasification reactivity of coal chars with steam and CO2 at moderate temperatures

Cited by 48 publications

References 38 publications

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Brown coal char CO₂‐gasification kinetics with respect to the char structure part II: Kinetics and correlations

Thermogravimetric and evolved gas analyses of high ash Indian and Turkish coal pyrolysis and gasification

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Thermogravimetric analysis of gasification reactivity of coal chars with steam and CO2 at moderate temperatures

Cited by 48 publications

References 38 publications

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Evolution of Structure Properties during Zhundong Coal Pyrolysis

Brown coal char CO2‐gasification kinetics with respect to the char structure part II: Kinetics and correlations

Thermogravimetric and evolved gas analyses of high ash Indian and Turkish coal pyrolysis and gasification

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Product

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Brown coal char CO₂‐gasification kinetics with respect to the char structure part II: Kinetics and correlations