SNCR脱硝特性的模拟及优化

Simulation and optimization of SNCR process

对某台使用尿素为还原剂的100t.h-1循环流化床锅炉的SNCR性能进行了CFD数值模拟,分析了温度、氨氮摩尔比等影响因素对SNCR脱硝效率、氨泄漏以及N2O浓度的影响规律。结果表明,SNCR最佳温度窗口的范围为850～1050℃,且随着氨氮比的增大,温度窗口范围变宽;随着温度的升高,氨逃逸量明显下降,当温度超过940℃后,氨逃逸量基本可以忽略不计,而N2O的生成量则呈现出先增大后减少的趋势。随着氨氮摩尔比的增加,脱硝效率逐渐增大,980℃左右达到峰值;氨泄漏随氨氮摩尔比的增加而增大;N2O浓度与脱硝效率呈正比关系,最大生成量约为30μl.L-1。

Using computational fluid dynamics（CFD）method,the urea-based selective non-catalytic reduction（SNCR）process in a 100 t·h^-1 circulating fluidized bed（CFB）boiler was numerically simulated to study effect of temperature and normalized stoichiometric ratio（NSR）on SNCR denitration efficiency,NH3 slip and N2O formation.The results show that the window of optimized temperature for SNCR process is in a range of 850—1050℃ and becomes wider with increasing NSR;when temperature rises,NH3 slip decreases obviously and can be ignored if temperature is higher than 940℃.With increase of temperature,amount of N2O formation increases first and then decreases.With increasing NSR,the denitration efficiency and NH3 slip increase.The denitration efficiency is the maximum at 980℃.Formation of N2O is in proportion to denitration efficiency and the maximum about 30 μl·L-1.