湿法烟气脱硫系统的脱汞性能现场实验

分析湿法烟气脱硫系统的脱汞性能,对控制燃煤电厂的汞污染具有重要意义。利用安大略水法和吸附管法分别对某600 MW电厂湿法脱硫系统的进出口的烟气进行了采样,测量了烟气中各形态汞浓度,并分析了该系统对烟气总汞、气态氧化态汞的脱除效果以及对气态单质汞的影响。研究结果表明,安大略水法和吸附管法均能较为准确地测定湿法脱硫系统进出口烟气中的汞含量,测得入口和出口的氧化汞与平均值的相对误差的绝对值分别为3.5%和1.3%;入口和出口的单质汞与平均值相对误差的绝对值分别为16.6%和3.3%。其中吸附管法操作相对简单。通过湿法烟气脱硫系统后,烟气中氧化态汞的浓度可下降87.5%,其中约67.5%的氧化态汞被湿法脱硫系统脱除,约20%的氧化态汞在脱硫浆液的还原作用下被还原为单质汞,导致脱硫系统出口的单质汞浓度高于入口。

Mercury removal performance of wet flue gas desulfurization system in field test

It is of great significance to investigate the mercury removal performance of the wet flue gas desulfurization(WFGD) systems for mercury emission control of coal-fired power plants. The flue gases of a 600MW unit boiler were sampled at the entrance and exit of the WFGD system with Ontario Hydro method and sorbent tube method. The mercury concentration and speciation of the flue gas were analyzed. The mercury removal effects and the impact on gaseous elemental mercury of the WFGD system were discussed. The results indicate that the mercury concentration and speciation can be accurately determined by using both the two methods. The operation of the sorbent tube method is relatively simpler than the Ontario Hydro method. The absolute values of relative measurement errors, at the entrance and exit of the WFGD system, are 3.5% and 1.3% for the oxidized mercury, and are 16.6% and 3.3% for the elemental mercury, respectively. Passing through the WFGD system, oxidized mercury concentration in the flue gas decreases 87.5%, including 67.5% get removed and 20% converts to elemental mercury. As the result, the concentration of elemental mercury of the flue gas at the exit of the WFGD system is higher than that at the entrance.