耦合热解-气化过程的两段气流床工艺模拟研究

Simulation of two-stage entrained flow process in coupling pyrolysis and gasification

提出了一种新型的两段循环气流床工艺,其一段炉内煤焦充分气化生产的高温合成气,为二段炉内煤的热解供热,二段炉内产生的煤焦循环再回一段炉。使用Aspen Plus模拟软件开发了两段气流床气化模型,考察了一段给氧量和二段炉膛停留时间对两段循环气流床工艺和焦油质量分数的影响。提高一段给氧量,可以降低合成气中焦油的质量分数,但是系统冷煤气效率及甲烷的产量也在减少;增加二段炉膛反应停留时间能够有效降低合成气中焦油的质量分数。调节一段炉温为1 400℃,二段炉膛停留时间为6 s,合成气中焦油的质量分数可降至93.21×10^(-3) kg/kg(以单位煤基计),系统的冷煤气效率可达86.21%,甲烷的产率可达76.80×10^(-3) m^3/kg(以单位煤基计)。

A new two-stage circulating entrained flow process has been proposed.The char produced from 2 nd furnace is completely gasified in the 1 st furnace to produce the high-temperature syngas,which is used for heating the pyrolysis process of the pulverized coal in the 2 nd furnace,then the produced char is recycled back to the 1 st furnace.The Aspen Plus simulation software was used to develop the two-stage entrained gasification model.Meanwhile,the effects of the 1 st stage oxygen mass flow and the 2 nd stage residence time on the two-stage circulating entrained bed process and tar yield have been investigated.Increasing the 1 st stage oxygen supply can reduce the tar yield,but the cold gas efficiency and the methane yield are also reduced.Increasing the 2 nd stage residence time can effectively reduce the tar yield.Adjusting the 1 st stage furnace temperature to 1 400℃and the 2 nd stage residence time to 6 s,the tar yield can be reduced to 93.21×10^-3 kg/kg(received coal),and the cold gas efficiency can reach 86.21%and the yield of methane can reach 76.80×10^-3m^3/kg(received coal).