SNCR的喷雾与混合过程及其对脱硝效率的影响

Spray and mixing processes of SNCR and its influence on denitration efficiency

研究了SNCR(选择性无催化还原)工艺过程中还原剂液滴向炉内的喷射轨迹、以及还原剂在炉内高温空间的蒸发和混合扩散问题,得到了循环流化床锅炉不同截面的还原剂浓度分布。由研究结果可知,随着雾炬的扩散,还原剂浓度分布更加均匀,有效覆盖区域增加。根据还原剂有效覆盖范围,可以预测在合适的温度窗口处烟气的有效脱硝效率,在此基础上对喷枪喷射的液滴参数进行了优化分析。研究了不同液滴粒径分布对还原剂喷射和扩散的影响,结果表明:液滴雾化粒径的适当增大可以使蒸发时间延长,从而使得炉内还原剂与烟气中NO_x更好地混合、增加还原剂的有效覆盖面积;此外,根据还原剂覆盖浓度也可对还原剂的使用量进行预测。

The subjects of reductant droplet ejection trajectory and the evaporation,mixing,and diffusion of a reductant under high temperature in the boiler space during the process of selective non-catalytic reduction were studied. The distribution of reductant concentration in different cross-sections of a circulating fluidized bed boiler was obtained,and the research results showed that the reductant concentration distribution is more uniform with the spreading of atomization bunch,and the effective coverage area of the reductant increases accordingly. The effective denitration efficiency at an appropriate temperature window was predicted as the effective coverage area of the reductant was provided. On this basis,the droplet parameters of the spray nozzles were analyzed and optimized. In addition,the influence of different droplet size distributions on the ejection and diffusion of the reductant was analyzed. The results indicated that the evaporation time can be extended by increasing the droplet atomization particle size appropriately. The flue gas and the reductant are thereby mixed better,and the effective coverage area of the reductant increases. In addition,the amount of reductant to be used can be predicted according to the concentration of the reductant.