低变质煤水热提质及气化特性研究

将低变质煤在高压反应釜中进行不同温度(100℃~250℃)的水热提质试验,然后采用非等温热重分析法对不同提质煤进行CO2气氛下的气化特性分析。分析结果表明,水热提质后煤样表面形貌发生较大变化,煤整体结构发生收缩,表面结构致密化并产生裂缝和断裂。原煤和提质煤在气化过程中均经历了热解和碳气化这2个主反应段。随着水热温度增加,提质煤由于挥发分含量减小使其热解段的反应速率明显下降,而碳气化段反应速率增加不明显;在碳气化段,提质煤的碳转化率随着水热温度的升高而有所增加,煤焦气化活性指数整体上略呈增大趋势。研究表明,该低变质煤提质后的气化活性受物理孔隙结构变化的影响可能超过煤阶和化学微晶结构等因素的影响。

Study on hydrothermal upgrading and gasification characteristics of low metamorphic coal

The hydrothermal upgrading test of low metamorphic coal was conducted in a high-pressure reactor at 100℃~250℃,then the gasification characteristics of different improved coal in CO2 atmosphere were analyzed by non-isothermal thermogravimetric analysis.The results showed that the surface morphology of coal sample changed greatly after hydrothermal upgrading,the overall structure of coal shrank,the surface structure densified and cracks and fractures occurred.Both raw coal and improved coal had experienced two main reaction of pyrolysis and carbon gasification.With the increase of the hydrothermal temperature,the reaction rate of the pyrolysis section of the improved coal decreased obviously due to the decrease of the volatile content,while the reaction rate of the carbon gasification section did not increase obviously;in the carbon gasification section,the carbon conversion rate of the improved coal increased slightly with the increase of the hydrothermal temperature,and the gasification activity index of the coal char increased slightly as a whole.The results showed that the gasification activity of the low metamorphic coal after upgrading might be affected by the change of physical pore structure more than that of coal rank and chemical microcrystalline structure.