煤的结构对化学链燃烧系统反应性能的影响

Effect of Coal Structure on the Reaction Performance of Coal-fueled Chemical Looping Combustion System

以我国典型煤种为原料,从'结构与反应性'的角度研究了不同热解条件下制得的煤焦的化学链燃烧反应特性,考察了煤阶、热解温度和热解速率对煤焦反应性能、孔隙结构和微晶结构的影响。结果表明,煤阶越低,煤焦孔隙结构越发达,使得煤焦的反应性能更佳;热解温度对3种煤的影响行为不同,褐煤煤焦随热解温度的升高孔隙结构变差,微晶结构有序化程度升高,煤焦反应性能下降,而烟煤和无烟煤煤焦在热解温度为900℃时获得最佳的反应性能,其中煤焦孔隙结构是影响其反应性能的主要因素;3种快速热解煤焦具有更发达的孔隙结构,微晶结构有序化程度较低,反应性能明显优于慢速热解煤焦。

The coal chars derived from the Chinese typical coals treated under different pyrolysis conditions were evaluated from the perspective of structure and reactivity in chemical looping combustion(CLC)process.The effects of coal rank,pyrolysis temperature and pyrolysis rate on the reactivity performance,pore structure and microcrystalline structure of coal chars were investigated.The results indicated that the lower the coal rank,the pore structure of coal char was better and its reactivity was higher.These three types of coals showed different pyrolysis behaviors with respect to the effect of pyrolysis temperature,lignite char showed worse pore structure and higher degree of microcrystalline structure ordering under higher temperature,resulting in lower reactivity of lignite char,whereas the bituminous coal char and anthracite coal char showed their best reactivity performance at 900℃,in which pore structure property was the major factor influencing the reactivity of these two coal chars.Fast pyrolysis condition could significantly improve the pore structure of coal char and lower the degree of microcrystalline structure ordering,making the reactivity of three fast pyrolyzed coal chars obviously higher than that of three slow pyrolyzed coal chars.