煤种及煤粉细度对炉内再燃过程脱硝和燃尽特性的影响

煤粉再燃技术是目前电站锅炉降低Nx排放的一种有效技术。本文在一维沉降炉上进行了不同煤种、不同煤粉细度的煤粉再燃脱硝降低NOx排放的试验研究。试验结果表明:高挥发分的煤种在再燃降低NOx时的效果更显著。对于同一煤种,采用细度更细的煤,合适的再燃区停留时间,可以获得高的降低NOx排放效果,并可使煤粉的燃尽率达到90%左右。本文还采用最小燃尽高度的方法探讨了再燃过程中煤粉细度的选择方法,分析得出,为使再燃区的煤粉能完全燃烧,充分发挥还原NOx的效果,必须采用细粉或者超细粉。

STUDY OF COAL RANK AND FINENESS ON NOx REDUCTION WITH COAL REBURNING TECHNOLOGY

Coal reburning is a successful advanced technology for reducing NO_x emissions from utility coal-fired boilers. In this work, various rank coals were employed as reburning fuel, the effects of reburning fuel ratio, reacting zone temperature, excess air, residual time and coal fineness on NO_x reduction efficiency were experimentally investigated by using an one-dimension drop-tube furnace. The experimental results show that the coal with high volatile content can reduce NO_x more effectively. For the same coal, in order to achieve high NO_x reduction efficiency, the finer coal finess and suitable residence time of the reburning zone are required. The minimum burn-out height has been put forward to evaluate the right location of the reburning coal injection ports to get a higher carbon burn-out and higher NO_x reduction efficiency.