基于DOC+SCR的船用柴油机尾气污染物脱除实验

Removal of marine diesel engine exhaust pollutants with DOC+SCR technologies

在发电柴油机台架上,通过SMG 100颗粒分析仪、Testo 350烟气分析仪等设备测试了加装DOC和SCR后柴油机在额定转速时6个工况点的排放特性,分析了DOC对CO、NOx和PM的影响,以及不同功率和喷氨量时SCR的脱硝率。结果表明,温度对DOC影响很大,当温度高于250℃,CO的脱除率在96%以上。在中低负荷时,DOC对PM的质量浓度脱除率在76%以上,但在满负荷时,由于柴油机燃烧快速恶化,PM浓度快速增大,此时的PM脱除率仅为36%。DOC能将NO转化为NO_2,但对NO_x的总浓度几乎不产生影响。SCR受温度和氨氮比的影响比较大,当温度高于250℃,氨氮比为1时,脱硝率几乎达到100%。通过与多篇文献的对比分析,采用功率与催化剂体积之比作为钒基SCR的初期选型参数可能更加合适。

The emission characteristics of DOC and SCR were tested by SMG 100 particle analyzer and Testo 350 flue gas analyzer on a diesel generator bench. Six working points were tested at rated speed. The effects of DOC on CO, NOx and PM were analyzed. The denitrification rates of SCR at different power points and urea injection were investigated. The results showed that DOC was greatly affected by temperature. CO removal rate was above 96% when the temperature was higher than 250℃. PM removal rate was above 76% at low or medium load. However, the PM removal rate was only 36% at full load because the PM concentration increased rapidly due to the rapid deterioration of diesel combustion. DOC could convert NO to NO2, but it had little effect on the total concentration of NOx. The denitrification rate of SCR was closely related to temperature and NH3/NOx ratio. It was almost 100% when the temperature was higher than 250℃ and NH3/NOx=1. Through the comparison with many articles, it may be more appropriate to use power/catalyst volume as the initial selection parameter for the vanadium-based SCR.