碳酸钠对选择性非催化还原反应影响的研究
Investigation on effects of Na2CO3 on selective non-catalytic reduction of NOx
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摘要: 在管式石英反应器中研究了Na2CO3对氨水-SNCR以及尿素-SNCR的影响。结果表明，添加少量的Na2CO3可以明显提高低温区域的脱硝效率，同时使NH3泄漏曲线明显往低温方向偏移，尿素-SNCR过程尾部HNCO泄漏明显降低；添加少量的Na2CO3可以明显降低N2O排放，这在尿素-SNCR过程中尤为明显；Na2CO3的添加明显提高了尿素热解气中HNCO向NH3的转化率，这是尿素-SNCR过程中HNCO泄漏可以显著降低，N2O排放得以大量减少的主要原因；Na2CO3添加量相同时，较低氨氮比工况的脱硝效率促进作用相对更为明显，较高氨氮比工况脱硝温度窗口宽度的扩展作用相对更为有效，而较低氧含量工况的脱硝效率促进效果也相对更为显著。Abstract: The effects of Na2CO3 addition on the selective non-catalytic reduction (SNCR) using ammonia solution or urea solution were investigated in a quartz tube reactor. The experimental results show that the addition of a little amount of Na2CO3 can improve the NOx reduction efficiency effectively in the low-temperature region, shift the NH3 slip curves to a lower temperature, and reduce the HNCO slip largely in the process of urea-SNCR. Also, the addition of a little amount of Na2CO3 can reduce N2O emission remarkably, especially for the course of urea-SNCR. It is found that the addition of Na2CO3 increases the conversion efficiency of HNCO to NH3 markedly in the thermal decomposition gases of urea, which is the main reason leading to the large reduction of HNCO slip and N2O emission in the process of urea-SNCR. Under the same Na2CO3 addition amount, the promoting effect on NOx reduction efficiency is more evident at lower ammonia-NOx ratio, and the promotion to the width of NOx reduction temperature window is more effective at higher ammonia-NOx ratio, and also the promoting effect on DeNOx efficiency is more obvious at lower oxygen content.
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