在管式石英反应器上实验研究了碳酸钠对使用尿素溶液作为还原剂、甲烷作为再燃燃料的先进再燃过程的影响。结果表明:先进再燃的最佳脱硝温度与最佳脱硝效率都要比选择性非催化还原(selective non-catalytic reduction,SNCR)要高,而先进再燃区域相对更低的氧含量以及相对更高的反应温度可以显著抑制N2O的生成;弱氧化性气氛下,碳酸钠在整个反应温度区域都可以有效促进脱硝效率的提高,使得脱硝温度窗口宽度得以扩大,存在碳酸钠时最佳脱硝效率可高达95%以上,而在过量空气系数为1.15、反应温度为1200℃时碳酸钠可以将脱硝效率提高2倍多;碳酸钠的添加可能促使了HNCO向NH3转化的反应,使得先进再燃过程整个温度范围内的HNCO泄漏量大幅降低,而低温区域的NH3泄漏量则明显增大,尤其N2O排放进一步降至接近于零的水平。
Experimental study on effects of sodium carbonate during advanced methane reburning using urea solution as nitrogen reductant was carried out in a quartz tube reactor.The results show that the optimum DeNOx temperature and the optimal DeNOx efficiency of advanced methane reburning(AR) are both higher than the ones of selective non-catalytic reduction(SNCR) process,and AR process's relatively lower oxygen content and higher reaction temperature could restrain N2O's production notably.Under weak oxidizing atmosphere,sodium carbonate promotes DeNOx efficiency effectively in whole AR reaction temperature region,thus the width of DeNOx temperature window is widened and the optimal DeNOx efficiency could be up to 95%,and the DeNOx efficiency is improved as high as two times or more when methane reburning zone excessive air coefficient is 1.15 and SNCR reaction zone temperature is 1 200 ℃.Sodium carbonate's addition might improve the conversion reaction of HNCO to NH3,thus the HNCO slip in whole AR reaction temperature region decreases notably and it's NH3 slip increases evidently in low temperature region at the same time,especially the N2O emission decreases almost to be zero.