逐级萃取对准东煤的热解特性影响

Effect of Stepwise Extraction on Pyrolysis Characteristics of Zhundong Coal

中文关键词: 准东煤  孔结构  洗煤  热解  微晶结构  动力学

英文关键词: Zhundong coal  sodium  coal washing  pyrolysis  microcrystalline structure  dynamics

中文摘要:

      为探究洗煤对准东煤热解特性的影响机理，采用逐级萃取法对准东煤进行洗煤处理。利用热重分析仪对比研究了洗煤对准东煤热解的影响规律，结合煤样热解前后样品的微观结构分析了洗煤对准东煤热解过程的作用机理，并采用分布活化能模型对煤样的热解反应动力学参数进行了计算。结果表明：脱除与煤中有机质结合的矿物质可以使煤样中产生大量新的多孔结构；洗煤会影响煤孔隙结构与官能团结构，导致煤样在热解初始阶段与热缩聚阶段失重量与失重率减少，主热解阶段失重量与失重率增大，并有利于煤焦微晶结构向石墨化进程演化。分布活化能模型可以较好地描述煤样的热解过程，随着洗煤程度的加深，活化能的分布曲线f (E)极大值对应的活化能由265.32 kJ/mol升高至377.20 kJ/mol，说明热解反应活化能的主要分布区间向活化能较高的区域移动。

英文摘要:

      In order to investigate the effect of coal washing on pyrolysis of Zhundong coal, the coal samples were washed by sequential extraction method. The influence mechanisms of coal washing on the pyrolysis process are analyzed by thermogravimetric analyzer (TGA). The mechanism of coal washing on the pyrolysis of Zhundong coal was analyzed by the microscopic structure of samples before and after pyrolysis reaction. The pyrolysis kinetics parameters were calculated by distributed activation energy model. The results suggest that the hole channel can be dredged by the coal washing and the surface porous structure of coal sample increased significantly. Coal washing affect the pore structure and functional group structure of coal samples, resulting in the decrease of weight loss and weight loss rate during the initial stage and the thermal shrinkage stage of pyrolysis and the increase of weight loss and weight loss rate during the primary pyrolysis stage, and promote the process of graphitization during coal pyrolysis; resulting in the more ordered carbon microcrystalline structure. The distributed activation energy model can describe the feature of coal pyrolysis. With the increase of coal washing degree, the activation energy corresponding to the maximum of the activation energy distribution curve f (E) increases from 265.32 kJ/mol - 377.20 kJ/mol, which indicates that the main distribution range of pyrolysis activation energy moves to higher activation energy region.