煤粉再燃过程对煤焦异相还原NO的影响

Effect of NO Heterogeneous Reduction by Coal Char During Pulverized Coal Reburning

利用高温携带流反应装置,研究了煤种(包括褐煤、烟煤和贫煤)、再燃区内反应温度、煤粉粒径、一次燃烧区空气过量系数SR1和再燃区空气过量系数SR2对煤焦异相还原NO作用的影响,探讨了煤焦异相还原NO的机理.结果表明:随着SR2和煤粉粒径的减小以及再燃区反应温度的提高,煤粉NO还原效率增加;在相同的SR2下,随着煤中挥发分含量的提高,煤粉粒径的增加和再燃区反应温度的降低,煤焦异相还原NO贡献上升;对于相同再燃燃料份额:SR1=1.0和SR1=1.2时煤焦异相还原NO的贡献均大于SR1=1.1时的异相还原NO的贡献.

The influence of some factors on NO heterogeneous reduction by coal char has been investigated in an entrained high temperature flow reactor. These factors include coal type such as lignite, bituminous coal and lean coal, reaction temperature in the reburning zone, size of coal particle, stoichiometric ratio in the primary combustion zone （SR1）, and stoichiometric ratio in the reburning zone （SR2）. The mechanism of NO heterogeneous reduction by coal char is being discussed as well. Results show that the NO reduction efficiency of pulverized coal increases with decreasing SR2 and coal particle size, as well as with rising reaction temperature in the reburning zone. For the same SR2, the increase of contribution of coal char to NO reduction efficiency is ascribed to the increase of proximate volatile matter content and pulverized coal size, and the decrease of reaction temperature in the reburning zone. For a fixed reburning fraction, the contribution of coal char to NO reduction efficiency with SR1 = 1.0 or SR1 = 1.2 is significantly larger than that with SRI=I. 1.