Abstract: 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.

Key words: SNCR, temperature window, NSR, NH₃ slip, CFD

摘要： 对某台使用尿素为还原剂的100 t·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30 μl·L^-1。

关键词: 选择性非催化还原, 温度窗口, 氨氮比, 氨逃逸, CFD