煤加氢热解及热解焦气化特性试验研究

Experimental study of coal pyrolysis in hydrogen atmosphere and coal char gasification characters

为给输运床气化试验提供基础数据,采用加压滴管炉反应装置,以次烟煤为研究对象,研究了不同温度、不同压力、不同反应气氛下煤的热解产物特性,并分析了不同热解条件对煤焦结构、基础物化性质及其CO_2气化反应性的影响。结果表明:氢气气氛热解产物中CH_4、C_2H_4的产率超过氮气气氛条件下的3倍,且对煤焦剩余挥发分的影响不大,反应气氛对于失重率的影响因温度而异,600~800℃下常压加氢工况煤的热解失重率相比惰性气氛下更小,总压0.5 MPa含氢气氛则比惰性气氛下的失重率更大。对于热解焦的气化活性,常压加氢工况制得的热解焦,其气化活性高于氮气气氛热解焦,而加压工况的气氛是否含氢对气化活性的影响不显著,氢气与煤的反应主要表现为甲烷化反应,加氢工况提高了热解焦的孔比表面积和孔体积,但对煤焦的化学结构影响很小。

In order to provide basis data for entrained bed gasification experiment, taking the sub-bituminous coal as an object, the pres- surized drop-tube furnace was used to study the gas characteristics after coal pyrolysis under the different temperatures, pressure and dif- ferent atmosphere. The effects of different pyrolysis conditions on char＇ s structure ,basic physical and chemical properties and CO2 gasifi- cation reactivity were also studied. The results showed that hydrogen atmosphere obviously improve the yield of pyrolysis gas of CH4, C2H4, and the yeild was over 3 times in nitrogen atmosphere, but had little effect on char residual volatile.The effect of reaction atmos- phere on weight loss rate varied with temperature, under the temperature of 600-800 ℃, constant pressure and hydrogen atmosphere ,the weight loss was smaller compared to inert atmosphere, under the pressure of 0.5 MPa and hydrogen atmosphere condition, coal pyrolysis had greater weight loss rate than inert atmosphere. As for gasification reactivity, gasification activity of the pyrolysis char prepared under the hydrogen atmosphere and constant pressure conditon, were higher than that of the nitrogen atmosphere pyrolysis char, but for the pres- surized conditions, the effect of hydrogen on the gasification activity was not significant. The reaction with coal and hydrogen was mainly methanization, the pressurize could increase surface and pore volume of the char, but changed little on the chemical structure of coal char.