600MW燃煤发电机组的SO_3生成与排放特性

Formation and Emission Characteristic of SO_3 in 600MW Coal-fired Generating Unit

采用控制冷凝法在某600 MW燃煤发电机组选择性催化还原(selective catalytic reduction,SCR)脱硝反应器入口和出口、干式静电除尘器(dry eletrostatic precipitator,DESP)入口和出口、湿式静电除尘器(wet electrostatic precipitator,WESP)入口和出口进行现场SO_3质量浓度测试,分析了锅炉的SO_3生成特性及各烟气处理设备对其的影响。结果表明,炉内燃烧过程会产生15.2~21.6 mg/m^3的SO_3,其生成质量浓度随负荷升高有所降低;SCR脱硝过程中部分SO_2转化为SO_3,导致SO_3质量浓度升高55.4%~58.3%;DESP、WFGD装置和WESP的SO_3脱除效率分别为44.67%~44.57%、74.1%~75.6%和51.4%~57.6%;WFGD装置对SO_3的脱除效率显著低于对SO2的脱除效率,而WESP对SO_2和SO_3的脱除效率无明显差异。

Control condensation method is used for field testing on SO3 mass concentration at the inlet and outlet of selective catalytic reduction（SCR）reactor of the 600 MW coal-fired generating unit,inlet and outlet of the dry electrostatic precipitator（DESP）as well as inlet and outlet of the wet electrostatic precipitator（WESP）.This paper analyzes formation characteristic of SO3 and influence of various flue gas processing equipments.Results indicate that in process of furnace combustion,there is 15.2-21.6 mg/m^3 SO3 to be produced of which mass concentration reduces with increase of load.Some SO2 may transfer to SO3 in process of SCR DeNOxwhich may cause SO3 mass concentration rise 55.4%-58.3%.SO3 removal efficiency of DESP device,WFGD device and WESP device is respectively 44.67% -44.57%,74.1% -75.6% and51.4%-57.6.SO3 removal efficiency of WFGD device is obviously lower than SO2 removal efficiency while there are no obvious differences between removal efficiency of SO2 and SO3 of WESP device.