燃煤电站静电除尘器前后汞的形态分布特性

探讨燃煤电站静电除尘器(ESP)前后汞的形态分布特性.采用美国测量燃煤烟气中汞浓度的标准方法——安大略法,对某220 MW“W”型煤粉锅炉系统中烟气经过ESP前后的汞浓度进行现场测试和分析.给出了烟气中氧化汞、元素汞、颗粒汞的分布,得到了煤粉炉系统的汞平衡.烟气在经过ESP前后,汞的分布形态发生了较大的变化,其中氧化汞的浓度下降,元素汞的浓度上升,ESP对汞的综合脱除效率约为36.28%.试验表明,ESP对汞的吸附和脱除作用除与飞灰中的碳含量和颗粒粒径有关外,还可能与吸附于其表面的其他元素的物理化学特性有关.

The Distribution Characteristic of Mercury Speciation Around ESP in a Coal Fired Power Plant

The mercury speciation distribution characteristic around electrostatic precipitato(ESP) in a coal-fired power plant is discussed.The Ontario Hydro Method(OHM)was used for the in-situ mercury measurement and analysis of the mercury concentration in the flue gas flowing through the ESP in a 220 MW W-type pulverized coal furnace.The distribution of mercury speciation of Hg0,Hg2 and HgP was detected.The mercury balance of this pulverized coal furnace was derived from the measured data based on samples of coal,bottom ash,fly ash and flue gas.Results show that the mercury speciation distribution varies greatly when the flue gas flows through the ESP.The concentration of the oxidized mercury decreases and that of the elemental mercury increases,resulting in an overall mercury removal efficiency of 36.28%.Tests reveal that the absorption and removal of mercury strongly depends on the carbon content and the particle sizes in fly ashes.The physical and chemical features of other substances on fly ash surfaces may also have influence to the mercury absorption.