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344 results on '"Xie, Kechang"'

53. Reactions related with hydroxyl, carboxyl and alkyl side chain at different temperature stages and the effects on low-rank coal ignition

Author

Ma Shengyue, Xiong Jie, Xiao Jing, Zhang Yueling, Zhang Ruihong, Tian Yajun, and Xie Kechang

Subjects
Environmental sciences, GE1-350
Abstract

Low-rank coal contains abundant hydroxyl, carboxyl and alkyl side chains, and reactions related to these groups are the main reason for the spontaneous combustion of low-rank coal. Here, two different low-rank coals (BRXL, YJL52) are selected. Firstly, the ignition temperatures of the coals are determined by thermogravimetric method. Secondly, the coals are heated at 100°C temperature intervals before the ignition temperature in the thermogravimetry, and infrared measurement is performed to explore the changes of these groups. Combining previous studies in the literatures with infrared analysis, it is found that reactions related are as follows: phenolic hydroxyl converting into alcoholic hydroxyl, alcoholic hydroxyl further oxidizing to carboxyl, and carboxyl decarboxylating into alkyl side chains. After that, the changes of phenolic hydroxyl and carboxyl on the surface of the coal at 100°C temperature intervals are determined by titration, which further reveal the main reactions occurred in every temperature interval. Additionally, the actual heat release in different temperature ranges is discussed with the reaction enthalpies of the above-mentioned main reactions. As a result, the key temperature stage that causes spontaneous combustion is found. The screening study in this paper on the reaction of low-rank coal before spontaneous combustion provides a theoretical basis for the control of spontaneous combustion of low-rank coal.

Published
2020
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57. The effect of mass transfer conditions during plastic stage on sulfur removal from high organic-sulfur coal

Author

National Natural Science Foundation of China, Natural Science Foundation of Shanxi Province, China Scholarship Council, Barriocanal Rueda, Carmen [0000-0001-5156-0970], Guo, Jiang, Wang, Meijun, Barriocanal Rueda, Carmen, Kong, Jiao, Chang, Liping, Bao, Weiren, Xie, Kechang, National Natural Science Foundation of China, Natural Science Foundation of Shanxi Province, China Scholarship Council, Barriocanal Rueda, Carmen [0000-0001-5156-0970], Guo, Jiang, Wang, Meijun, Barriocanal Rueda, Carmen, Kong, Jiao, Chang, Liping, Bao, Weiren, and Xie, Kechang

Abstract

A gas coal (B) was used to study the effect of volatiles on sulfur removal from a high organic-sulfur coking coal (A) from the perspective of mass transfer conditions. The mass transfer driving force and resistance of volatiles were analyzed in terms of fluidity development, permeability of coal plastic stage to gas flow, and volatile matter release. Carbonization using vertical and horizontal stacking modes of two coals were designed according to the release directions of volatiles during pyrolysis. Three pyrolysis temperatures (450, 475 and 510 ºC) were used to study mass transfer conditions. The semicokes were cut into pieces at fixed intervals along vertical and horizontal directions to determine the spatial sulfur distribution in semicoke. The gas coal volatiles helped the removal of sulfur within a limited distance that was related to the mass transfer conditions of volatiles, whereas permeability determined the mass transfer resistance of volatiles and their driving force was controlled by the amount and rate of volatile matter release.

Published
2022

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