水热提质煤的CO2气化特性研究

戴亚雄 平晓东 邱家用

摘   要：采用高壓反应釜对低变质煤进行不同温度（100℃～250℃）的水热提质，采用非等温热重分析法对不同提质煤进行CO2气化特性分析。结果表明：水热提质煤样表面形貌发生较大变化，整体结构收缩，表面致密化，并产生裂缝和断裂。250℃的水热煤样表面光滑，且表面裂缝和断裂明显。原煤和提质煤在气化过程中均经历了热解和碳气化两个主反应段。随水热温度增加，提质煤由于挥发分含量减小使其热解段的反应速率下降明显，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水热温度升高而稍增加，煤焦气化活性指数整体上略呈增大趋势。

关键词：煤  水热提质  CO2气化特性  热重分析

中图分类号：TQ536.1                             文献标识码：A                        文章编号：1674-098X（2020）06（a）-0081-05

Abstract： The low metamorphic coal is hydrothermal upgraded at 100℃～250℃ in an autoclave， and then the CO2 gasification characteristics of the different upgraded coals are analyzed using the non isothermal thermogravimetric analysis method. It is shown that the surface morphology of the upgraded coal samples changes greatly. The structure of coal is contracted and densified with cracks and fractures. When the hydrothermal temperature reaches 250℃， the surface of the coal becomes smooth， but the cracks and fractures on the surface become intensified. Both the raw coal and the upgraded coal experience two main reaction stages of pyrolysis and carbon gasification during gasification. With increasing the hydrothermal temperature， the reaction rate in the pyrolysis stage of the upgraded coal decreases obviously due to the decrease of volatile content， while the reaction rate in the carbon gasification stage increases not obviously. In the carbon gasification phase， the carbon conversion of the upgraded coal is slightly increased with increasing the hydrothermal temperature， meanwhile， the gasification activity index of the coal shows a slight increase as a whole.

Key Words： Coal; Hydrothermal upgrading; CO2 gasification; Thermogravimetric analysis

近年来，随着煤炭的大量消耗，使低变质煤受到了广泛关注。低变质煤是指煤化程度较低的煤[1]，具有碳含量低、挥发分高、水分高、强亲水性等特点[2]，燃烧时消耗热量使内部水分蒸发，造成能源浪费[3]，而且脱水后极易发生水分复吸[4]，这极大地降低了利用效率[5]。

水热处理是一种低变质煤脱水改性的方法[6]，煤样处于高温及饱和蒸汽压条件下，煤中的水以液态形式排出，从而降低了汽化潜热[7]。Liao[8]等对褐煤用水热脱水技术进行提质，结果表明，水热提质后其自燃倾向性均有所提高，且随着水热提质温度的升高，自燃倾向性却有所下降。王智化[9]发现改性后煤质结构深度及煤阶的改变使得褐煤的气化特性曲线向高温区移动，并且气化反应活化能呈上升趋势。……