350MW燃煤电站Se、As、Pb迁移转化规律

The migration and transformation laws of Se,As and Pb in 350 MW coal-fired power plants

本文基于国内某350 MW燃煤电站开展了重金属排放控制研究,系统分析了燃煤烟气尾部净化不同位置重金属的浓度分布,揭示了Se、As、Pb等重金属的迁移转化规律。研究表明,ESP出口,1μm以下、1~2.5μm、2.5~10μm的细颗粒态Se、As、Pb浓度均低于0.80μg/m^(3),ESP对细颗粒态重金属的脱除效率均超过95%。在ESP和WFGD联合作用下,气态Se、As、Pb的综合脱除效率分别为75.62%、87.48%、40.20%,排放至大气中的气态重金属浓度显著降低。此外,由于石灰石浆液和工艺水中As含量较高,导致该机组脱硫废水和石膏中As含量分别达到199.19μg/L和22.25 mg/kg,需要引起重视。考虑到燃煤副产物利用和堆积可能引发环境累积效应,若不经处理直接排放将对周围环境的安全造成潜在风险。

This paper conducts a research on heavy metal emission control based on a 350 MW coal-fired power plant in China,systematically analyzing the concentration distribution of heavy metals at different locations of coal-fired flue gas purification,and revealing the migration and transformation laws of heavy metals such as Se,As,and Pb.Research has shown that the concentrations of fine particulate Se,As,and Pb below 1μm,1~2.5μm,and 2.5~10μm at the ESP outlet are all below 0.80μg/m^(3),and the removal efficiency of fine particulate heavy metals by ESP exceeds 95%.Under the combined action of ESP and WFGD,the comprehensive removal efficiency of gaseous Se,As,and Pb is 75.62%,87.48%,and 40.20%,respectively.The concentration of gaseous heavy metals discharged into the atmosphere is significantly reduced.In addition,due to the high As content in the limestone slurry and process water,the As content in the desulfurization wastewater and gypsum of the unit reached 199.19μg/L and 22.25 mg/kg,respectively,which needs to be taken seriously.Considering that the utilization and accumulation of coal by-products may cause environmental accumulation effects,if discharged directly without treatment,it will pose potential risks to the safety of the surrounding environment.