燃煤电厂真实烟气条件下SCR催化剂脱硝性能

制备了具有工业应用价值的V₂O₅/TiO₂负载WO₃与MoO₃的蜂窝状SCR催化剂,并在某燃煤电厂烟气环境下,对其催化性能进行了测试,结果表明:增大催化剂体积能够提高脱硝效率,但活性增量逐步下降,当脱硝效率达到80%以上时,继续增大催化剂体积其活性提高不显著。催化剂的脱硝活性随着积灰时间的延长而降低,脱硝系统运行4 h后,催化剂脱硝活性减少9.4%。在燃煤电厂尾气飞灰浓度约为0.031 kg·m^-3环境下,为满足尾气中NO_x浓度排放要求(<200 mg·m^-3),每连续运行6 h需进行一次吹灰。催化剂的脱硝性能随着运行时间的延长,先急剧下降,后缓慢降低。在连续运行48~168 h范围内,脱硝活性下降值小于1%,SO₂氧化率下降值小于0.1%。在12个月内,平均每连续运行700 h,脱硝活性降低1%。

DeNOx performance of SCR catalyst for exhaust gas from coal-fired power plant

A honeycomb SCR catalyst of V₂O₅/TiO₂ with WO₃ and MoO₃ was prepared and its deNO_x performance was investigated in a pilot plant test using flue gas of a coal-fired power plant.The results show that the larger catalyst volume is,the higher deNO_x efficiency,and SO₂ oxidation increases too,but increase ratio becomes smaller.When deNO_x efficiency is above 80%,the outlet NO_x concentration met the emission standards,and the efficiency improvement is not significant by further enlarging catalyst volume which led to higher construct cost.In order to obtain the best ratio of deNO_x efficiency to catalyst volume and avoid resources waste for single requirement of higher deNO_x efficiency,SCR catalyst volume should be adjusted for different boiler types,according to flue gas component of coal-fired power plant and national emission standards.The deNO_x efficiency reduces with soot increase deposited,and drops about 9.4% within 4 h of soot depositing.The outlet NO_x concentration can be at 198 mg·m^-3 after 8 h of soot depositing.At 0.031 kg·m^-3 of fly ash concentration,the soot deposited needed to be blown each 6 h to obtain a satisfied deNO_x efficiency (>80%).When run time prolongs,the deNO_x efficiency falls sharply first,and then reaches a relative stable level.Within 48—168 h,the deNO_x efficiency and SO₂ oxidation decline less than 1% and 0.1%,respectively.After continuous run for 3 months (2160 h),the NO_x concentration at outlet of SCR tower is 196 mg·m^-3.The deNO_x efficiency declines at a rate of 1% per 700 h for continuous 12 month run.