SNCR脱硝及添加CO对其特性的影响

Experimental study on SNCR process of the effect of CO additive on denitration performance

在管式炉上模拟烟气气氛下实验研究了650～950℃范围内选择性非催化还原（SNCR）技术的脱硝特性及添加CO对其脱硝特性的影响,分析了相关反应机理。结果表明：不添加CO时,SNCR最佳脱硝温度为900℃;反应器尾部N_2O和NO_2排放质量浓度均随反应温度的增加,先增大后减小,在850℃时N_2O和NO_2排放质量浓度达到峰值,高温可降低氨逃逸量;反应温度低于700℃,增大氨氮摩尔比对脱硝效率、N_2O与NO_2排放质量浓度没有影响,而氨逃逸显著增大;反应温度高于800℃,增大氨氮摩尔比,脱硝效率与N_2O排放质量浓度均增大,而NO_2排放质量浓度减小。添加微量CO时,最佳脱硝效率略有增大,最佳脱硝温度、脱硝温度窗口及氨逃逸曲线向低温移动,脱硝温度窗口的下限降低至750℃;N_2O排放温度范围变宽且峰值增大,NO_2排放质量浓度接近于零。增加CO添加量易引起低温下反应器尾部CO逃逸量的增大,应尽量减少CO的添加量。实际应用中,可通过加入微量的CO降低SNCR脱硝温度,减少NO2排放质量浓度及低温时的氨逃逸量等。

Experimental study on selective non-catalytic reduction（SNCR）process and the effect of adding CO on the denitration efficiency were performed on a tubular flow reactor in simulated flue gas atmosphere,at temperature ranging from 650 ℃to 950 ℃.The relative reaction mechanisms were investigated.The results show that,with no CO added,the optimum temperature for SNCR denitration was 900℃.With an increase in reaction temperature,the emission concentrations of both N_2O and NO_2 increased first and then decreased,which were similar to the denitration efficiency curves.At high temperature the ammonia escape reduced.At temperatures below 700℃,increasing the ammonia nitrogen mole ratio had no apparent effect on the denitration efficiency.While at temperatures higher than 800 ℃,with an increase in ammonia nitrogen mole ratio,the denitration efficiency and N_2OO emission concentration both increased,but the NO_2 emissions concentration decreased.With trace CO added,the optimum temperature for denitration and the curve of ammonia escape shifted to a lower temperature and the maximum denitration efficiency increased slightly.The temperature window of N_2O emission was broadened and its peak increased.The NO_2 emission concentration was close to zero.In addition,increasing the CO addition amount can lead to an increase in CO escape at low temperatures.Therefore,in practical application,trace amount of CO can be added to decrease the SNCR denitration temperature and reduce the NO_2 emission concentration and ammonia escape at low temperatures.