超低排放改造后燃煤烟气净化设备协同脱汞潜力分析

燃煤机组完成超低排放改造后，原有的烟气净化设备在设备容量、装备水平上有较大提升。为了给汞排放治理提供决策依据，分析了超低排放改造后烟气净化设备的汞脱除潜力。研究结果表明：SCR烟气脱硝系统改造能够增大Hg⁰的氧化效率，因而能促进后续烟气净化设备的脱汞效率；低低温电除尘和电袋复合除尘技术的协同脱汞效率显著，可达40%；安装高效除尘除雾器的脱硫塔对汞的协同脱除效率可达96%。然而，由于超低排放改造后除尘器出口Hg²⁺含量低，且粉尘浓度低、粒径小，脱硫系统单塔提效增容改造及湿式电除尘器对烟气中汞的脱除效率影响有限；还有可能出现单塔提效增容改造后脱硫系统出口汞的排放浓度较入口略有增加的情况。

Potential Analysis of Synergetic Mercury Removal from Coal-Fired Flue Gas on Purification Equipment after Retrofitting of Ultra-low Emission

The ultra-low emissions retrofitting improves the flue gas purification equipment in the coal-fired power plant greatly in terms of the equipment capacity and quality. In order to provide the basis for decision-making on the control of mercury emission, the synergistic mercury removal efficiency of the purification equipment is analyzed. The results show that the SCR system retrofitting can increase the oxidation efficiency of Hg⁰ and promote the mercury removal efficiency of the dust removal equipment and the desulfurization equipment. The mercury removal effect of the low-temperature electrostatic precipitator and the electrical fabric filter can reach up to 40%. The desulfurization equipment with a high efficient demister can remove mercury in a synergistic manner with an efficiency of 96%. However, due to the low Hg²⁺ concentration at the outlet of the dust collector as well as the low dust concentration and the small particle size, the influence on mercury removal efficiency in flue gas is limited from the single tower retrofitting and the wet electrostatic precipitator in the desulphurization system. It is also possible that the mercury emission concentration at the outlet of the desulphurization system is slightly higher than that at the inlet after the single tower retrofitting.