燃煤电厂污染控制设备脱汞效果及汞排放特性试验

为了解燃煤电厂汞的排放规律以及现有的污染控制设备对烟气中汞的协同脱除效果,采用安大略法对江西省内4台机组进行汞排放及控制试验研究,得到现阶段燃煤电厂配置条件下汞的排放特性。研究结果表明:未投入汞氧化剂的机组污染控制设备协同脱汞效率在69.01%~75.63%,投入汞氧化剂的机组脱汞效率可达89.69%;SCR脱硝装置对烟气总汞的减排效果不明显,但能促使Hg0成为易于脱除的Hg~(2+)和颗粒态汞,机组投入汞氧化剂后可大幅提高Hg~0氧化为Hg~(2+)的比率;除尘器可以脱除全部的颗粒态汞,其协同脱汞效率平均值为24.37%;湿式脱硫系统对Hg~(2+)的脱除效率为88.39%;烟气经过脱硝、除尘、湿式脱硫装置后,最终排放气体中汞的质量浓度在3.91~8.89μg/m~3,远小于国家排放标准限值。

Experimental Study on Mercury Removal Effect and Mercury Emission Characteristics of Pollution Control Equipment in Coal-Fired Power Plants

In order to better understand the mechanism of mercury emission from coal-fired power plants and the effects of existing pollution control equipment on synergistic mercury removal, the test study on the mercury emission from four thermal power units in Jiangxi Province is carried out by using Ontario Hydro Method, thus the current mercury emission characteristics of power plants are obtained. The results show that the mercury removal efficiency of the units without mercury oxidant is between 69.01% and 75.63%, while that with mercury oxidant can reach as high as 89.69%. The SCR denitration does not seem to take significant impact on total mercury reduction. However it can promote the oxidation of Hg⁰ to Hg²⁺ and Hg_p. The oxidation ratio of Hg⁰ to Hg²⁺ can be increased drastically with the mercury oxidants being put into use. The electro-static precipitator(ESP) can remove almost all Hg_p, and its average total synergistic mercury removal efficiency is 24.37%. The removal efficiency of Hg²⁺ by wet flue gas desulphurization (WFGD) is 88.39%. After processed through SCR, ESP and WFGD, the mass concentration of mercury in the exhaust gas is limited within the range between 3.91 and 8.89 μg/m³, which is far below what is specified in the national emission standard.