烟煤煤粉及热解产物对NO的还原特性实验研究

Experimental Research on Characteristics of NO Reduction Using Pulverized Coal and Pyrolysis Production of Bituminous Coal

在固定床反应器中,不同温度下将烟煤煤粉及其热解产物分别对NO进行还原性实验,研究了热解气体、焦炭以及煤粉的还原作用。结果表明,煤粉在不同温度下析出的热解气体因组成不同而具有不同的还原性。随温度升高,热解气体和焦炭的还原效果均越好。同温度下,在反应前期热解气体对NO的还原作用优于焦炭对NO的还原作用,后期则后者优于前者。煤粉对NO的还原效果均比同温度下的热解气体或焦炭的单独还原效果好,但比各自单独还原的效果总和要差,这是因为同时存在同相还原和异相还原以及二者相互竞争的影响。煤粉还原反应的前期同相还原起主要作用,后期则异相还原起主要作用。加速煤粉热解气体和焦炭的分离有利于煤粉对NO的还原。在煤粉再燃区,没有燃烧的煤粉对NO的还原贡献更大。

The experiments on characteristics of NO reduction using pulverized coal and pyrolysis production of bituminous coal were carried out separately at different temperatures in a fixed-bed reactor, through which the NO reduction characteristics of pyrolysis gas, char, and pulverized coal were studied. It is found out that the pyrolysis gas produced from coal at different temperatures has different components and thus takes on different reduction characteristics The reductions of pyrolysis gas and char get more effective as temperature rises. At the same temperature, the NO reduction using pyrolysis gas is more effective than that using char in the early reaction stage, but afterwards the NO reduction using char is more effective than that using pyrolysis gas. The NO reduction using pulverized coal is more effective than that using pyrolysis gas or char at the same temperature but less effective than the combined effect of the two separate NO reductions using pyrolysis gas and char as homogenous reduction and heterogenous reduction and their interaction effect take place at the same time. The homogenous reduction dominates the early reaction stage of NO reduction using coal, but afterwards heterogenous reduction dominates. The fast separation of pyrolysis gas and char is in favor of NO reduction. The unburned coal contributes more to NO reduction in the coal reburning zone.