酸洗脱矿对胜利褐煤热解过程中N迁移转化的影响

在石英管流化床反应器中对胜利褐煤进行快速热解实验,考察了773~1 173 K下酸洗脱矿对胜利褐煤热解过程中N迁移转化规律的影响。通过比较原煤和酸洗后煤中N的不同逸出规律可以得出,影响酸洗前后胜利褐煤热解过程中N迁移转化规律的主要是碱金属Na及碱土金属Ca;热解过程中,煤中的Na和Ca促使煤中的N向NH3转化并有效抑制了HCN的生成,金属离子的存在对催化焦油N转化为NH3的作用较为明显;原煤中的碱金属和碱土金属的赋存使半焦裂解反应加剧,降低了固体半焦的产率,半焦N的产率也随之减少;与原煤相比,酸洗煤热解半焦中的吡啶型N(N-6)含量较多,而吡咯型N(N-5)和季N(N-Q)相对较少。

Influence of demineralization using acid wash on N migration and transformation during pyrolysis of Shengli brown coal

This paper is to examine effects of inherent minerals in coal on N migration and transformation during the fast pyrolysis of Shengli brown coal at the temperatures of 773~1 173 K in a bench-scale fluidized-bed quartz reactor. Based on the comparison between raw coal and acid-washed coal, we can find that the alkali Na and alkaline Ca were the key reasons for the difference in N evolutions from raw coal and demineralized coal during the pyrolysis. The Na and Ca could efficiently facilitate the formation of NH₃ and inhibit the production of HCN. The metallic species had obvious catalytic effects for the conversion from tar-N to NH₃. Meantime, the existence of alkali and alkaline metals has enhanced the cracking reactions of coal char, thus reducing the yields of char and char-N. In addition, the relative amount of pyridinic(N-6) in demineralized coal char was higher than that in raw coal, while less quternary type nitrogen (N-Q) and pyrrolic nitrogen(N-5) were found in the demineralized coal char.