Properties and Combustion Kinetics of Coalchar through High-Temperature Internals-Regulated Pyrolysis

Shuai XU , Hong ZHANG , Xue-jing LIU

Science Technology and Engineering ›› 2025, Vol. 25 ›› Issue (14) : 5976 -5982.

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Science Technology and Engineering ›› 2025, Vol. 25 ›› Issue (14) : 5976-5982 DOI: 10.12404/j.issn.1671-1815.2404485
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Properties and Combustion Kinetics of Coalchar through High-Temperature Internals-Regulated Pyrolysis
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Abstract

In order to understand the properties of char which is the main byproduct of coal pyrolysis in the reactor with internals, especially the char prepared at high temperatures, the char samples were prepared by pyrolysis of Yulin bituminous coal under vacuum condition between 1 000 ℃ and 1 500 ℃ in the fixed-bed reactor with internals. The variations of pore structure, composition, calorific value, and carbon structure of chars with pyrolysis temperature were studied. The isothermal combustion characteristic and kinetics were investigated by MFBRA(micro fluidized bed reaction analyzer). The results show that the increase in pyrolysis temperature leads to a deeper degree of pyrolysis. As the pyrolysis temperature increases, the C content and C/H molar ratio of chars gradually increase, H and O contents of chars gradually decreases, and the calorific value increases slightly. The specific surface area and pore volume of chars firstly decrease with the increase of pyrolysis temperature, and then remain essentially constant after the pyrolysis temperature exceeds 1 300 ℃, which is consistent with the trend of graphitization degree. The three-dimensional diffusion model G(x) = [1 - (1-x)1/2]2 can well describe the combustion process of chars. The activation energy and pre-exponential factor increase with the increase of pyrolysis temperature, and vary in the range of 30.49 ~ 90.17 kJ/mol and 0.69 ~ 352.25 s-1, respectively. The significant decrease in combustion reactivity of char prepared above 1400 ℃ is mainly due to the sharp increase of C/H.

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char / combustion / internals / kinetics / micro fluidized bed

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Shuai XU, Hong ZHANG, Xue-jing LIU. Properties and Combustion Kinetics of Coalchar through High-Temperature Internals-Regulated Pyrolysis. Science Technology and Engineering, 2025, 25(14): 5976-5982 DOI:10.12404/j.issn.1671-1815.2404485

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