电站锅炉选择性非催化还原脱硝实验研究——还原区温度、尿素溶液喷射体积流量的影响

Experimental research on SNCR applied in power plant boiler:impact of temperature and urea solution injection volume flow rate

对一台HG410／9．8-YW15型煤粉锅炉，在常规煤粉再燃技术改造的基础上进一步结合了使用尿素溶液喷射的选择性非催化还原（SNcR）技术．实验主要在280、345、410t／h 3个负荷下进行．实验结果表明，各个负荷下，SNCR技术可以将NOx排放降至低于200mg／m^3（标准状态、6％O2体积分数、干态），达到40％～60％的脱硝效率．应选择950℃左右的喷射层进行喷射为宜，温度过高或过低均会导致脱硝效率的降低，过低的温度还会使得尾部NH3排放大量增加．通过增加层喷射体积流量可以提高脱硝效率，在实验范围内得到的层最佳喷射体积流量为1．0～1．6m^3／h．同时，增加层喷射体积流量对NH3及N2O的减排也是有益的，而喷人的水量会对锅炉效率造成约0．5％的损失．

Selective non-catalytic reduction （SNCR） using urea solution injection was applied to a HG-410/ 9.8-YW15 boiler on the base of conventional pulverized-coal reburning process. Experiments were mainly conducted under 280, 345 and 410 t/h. Results showed that NOx emission was below 200 mg/m^3 （standard condition,6% O2 volume fraction, dry gas） when SNCR was operating, namely a NOx reduction of 40%- 60%. It was favorable to injecting urea solution using the injection layer where the hearth temperature was about 950 ℃, higher or lower might be disadvantageous to NOx reduction, and the lower temperature also resulted in more ammonia slip. The increase of layer＇s injection volume flow rate could improve NOx reduction efficiency, the economical injection volume flow rate in the experimental range was 1.0--1.6 m3 · h^-1 , and the larger injection volume flow rate also led to lower emission of NH3 and N2O. But the water injected into the hearth resulted in a decrease of boiler efficiency by almost 0.5 %.