煤拔头中低温快速热解烟煤半焦的孔隙结构

利用喷动载流床模拟煤拔头工艺,在550, 650, 750和850℃热解温度下对大同烟煤进行热解得到拔头半焦. 采用氮吸附法对该烟煤及其半焦的孔隙结构进行了研究. 结果表明,拔头半焦的孔隙发达度都弱于原煤;由低到高4个热解温度下挥发分析出率(Y)依次为7.89%, 21.79%, 22.12%, 39.33%,中孔尺寸随Y增加而减小,微孔和大孔尺寸及总孔体积和总孔比表面积基本随Y增加而增加;550℃时挥发分的析出对孔隙结构的发展无明显有利影响. 从原煤到半焦(热解温度由低到高),样品满足BET吸附等温式的相对压力范围依次为0.101~0.351, 0.093~0.201, 0.072~0.152, 0.032~0.053, 0.058~0.108,BET比表面积与NLDFT总孔比表面积变化趋势一致.

Pore Structure of Low Temperature and Fast Pyrolysis Bituminous Semi-char from Coal Topping Process

The pore structure of char derived from Datong bituminous coal after mild pyrolysis at 550, 650, 750 and 850℃ in a spout entrained reactor was studied using N2 adsorption. The results show that pore structure of all char samples is inferior to that of the parent coal. Yield of volatiles (Y) at four pyrolysis temperatures, 550, 650, 750 and 850℃, are 7.89%, 21.79%, 22.12% and 39.33% respectively. With increasing of Y, mesopore size decreases, micropore and macropore size, as well as total pore volume (Vtotal) and total pore specific area (Stotal), basically increase. At 550℃, volatile release has little contribution to pore structure evolution of char. Relative pressure ranges obtained are used to calculate BET specific surface area (SBET) for parent coal and four chars (derived at 550, 650, 750 and 850℃), are 0.101~0.351, 0.093~0.201, 0.072~0.152, 0.032~0.053, 0.058~0.108 respectively. The change of SBET with pyrolysis temperature is the same as that of Stotal.