钙基颗粒对分解炉内选择性非催化还原法脱硝影响的研究进展

水泥生产产生大量氮氧化物,对空气污染排放治理有很大的影响。在中国水泥生产线普遍采用选择性非催化还原脱销技术(selective non-catalytic reduction,SNCR),可以用氨水、尿素等其他还原剂,NO_x被SNCR脱硝技术还原成N_2和H_2O。SNCR在电站锅炉已运用成熟,可是在水泥窑炉运用效果一般,脱硝率较低,液体还原剂大量消耗,并出现氨水逃逸等问题,表明在水泥窑炉SNCR烟气脱硝过程比电站锅炉更加复杂。因此,为了将SNCR脱硝技术更好地应用到水泥窑的分解炉,使其NO_x的排放得到有效的控制,对近年来中外水泥生料的主要成分高浓度的钙基颗粒对水泥窑分解炉中SNCR脱硝技术的影响,以及NH_3在分解炉内氧化还原NO_x的作用途径进行总结,为SNCR在水泥窑的有效发挥提供新的改进思路。

A Review on Effect of Calcium Based Particles on SNCR Denitrification in Precalciner

Cement production produces a large amount of nitrogen oxides, which has a great impact on the treatment of air pollution emissions. Selective non-catalytic reduction (SNCR) is commonly used in domestic cement production lines. Reducing agents such as ammonia water and urea can be used and NOx is reduced to N2 and H2O by SNCR denitrification technology. SNCR has been used in power station boilers and some industries, but it has not been effectively used in cement kilns, with low denitrification rate, large consumption of liquid reducing agent and escape of ammonia water, indicating that the denitrification process of SNCR flue gas used in cement kilns is more complicated than that of power station boilers. Therefore, in order to better apply SNCR denitrification technology to the precalciner of cement kiln and effectively control its NOx emission, this paper summarizes recent researches at home and abroad on high concentration calcium-based particles in cement raw materials. Some conclusions, including the effect of high concentration of calcium-based particles on the denitrification efficiency of SNCR, and the way of action of NH3 in redox NOx in the precalciner, provide new improvement ideas for the effective play of SNCR in cement kiln.