燃煤电站烟气中汞脱除与减排技术

对现有环保设施的脱汞效果进行评价,简介燃烧前脱汞处理方法、烟气脱汞方法和涉及脱汞的多污染物脱除技术。已有的测试数据表明,SCR系统可将烟气中的元素态汞氧化为氧化态汞,使下游设备的脱汞能力提高;静电除尘器和布袋除尘器均能捕集烟气中的颗粒态汞和氧化态汞,后者效果更好;飞灰中的碳含量对除尘器脱汞效率有很大影响,碳含量越高,除尘器脱汞效率越高;现有的湿法烟气脱硫系统能够捕集烟气中的氧化态汞,但也能将氧化态汞还原成元素态汞。采用燃煤中添加溴化物的方法可以有效提高烟气中氧化态汞的比率,因此可提升现有设施的脱汞效率;多污染物控制技术能够实现SO_x、NO_x和汞等多污染物的联合脱除,将具有广阔的发展前景。

Technology of Mercury Removal and Reduction for Flue Gas of Coal-Fired Power Plants

The effect of mercury removal in the existing air pollutant control devices in coal-fired power plants is evaluated and the mercury control technologies, which could be classified as pre-combustion control and flue gas mercury removal technology and mercury removal related multi-pollutant removal technologies are presented. According to the data collected, the SCR system can convert Hg⁰ to Hg²⁺, which could be removed more easily by downstream equipment. Both the electrostatic precipitator (ESP) and the fabric filter can remove Hgp and Hg²⁺ from the flue gas, while the latter shows better performance. The carbon content of the flue gas has great effect on the removal efficiency of dust collectors, that is, more carbon content leads to better efficiency. The existing flue gas desulphurization (FGD) systems can collect Hg²⁺, but can also convert Hg²⁺ to Hg⁰. The method of adding bromides to coal can raise the Hg²⁺ content of flue gas, which could enhance the performance of mercury removal for the existing air pollutant control devices. Some multi-pollutant control technologies with promising prospect are also introduced, which could achieve the goal of removing SO_x, NO_x, Hg and fine particulate matter.