脱硫废水烟道蒸发工艺协同脱汞效率研究

燃煤电厂脱硫废水成分复杂，处理难度大。以某燃煤电厂600 MW机组为研究对象，进行了脱硫废水（人工配制）烟道蒸发试验，探索了协同脱汞的可行性，并讨论了脱硫废水氯离子质量浓度与机组运行负荷等对脱汞效率的影响。研究结果表明，将脱硫废水喷射至烟道进行雾化干燥的协同工艺，不仅有效提高了烟气中HCl含量，而且能促使更多Hg⁰转化为较易被飞灰吸附的Hg²⁺，可实现脱硫废水零排放和烟气汞的减排；废水中的氯离子对脱汞效率有较大的影响，当废水中氯离子质量浓度由21 250 mg/L增加至36 500 mg/L时，烟气中气态汞的协同脱除效率由95%降至58%；与机组低负荷运行时协同脱汞效率相比，高负荷条件下协同脱汞效率有所降低。

Enhanced Mercury Removal Technology in Coal-Fired Power Plants Through Desulfurization Wastewater Evaporation

It is difficult to treat Wet Flue Gas Desulfurization (WFGD) wastewater of coal-fired power plant due to its complex compositions. In this paper, take a 600 MW supercritical unit as the research object, desulfurization wastewater evaporation technology is used to enhance the removal of gaseous mercury (Hg) for coal-fired power plants and the feasibility of synergistic mercury removal is explored. Effects of desulfurization wastewater chlorine ion concentration and unit load on Hg removal were studied as well. The results show that WFGD wastewater evaporation is beneficial to improve the efficiency of Hg oxidation and removal because Hg enriched with chlorine ions is easier to be removed. Hence this method realizes WFGD wastewater zero discharge and simultaneously enhances Hg removal efficiency. In addition, the mercury removal efficiency is greatly affected by chlorine ion concentration in desulfurization wastewater. When the chlorine ion concentration was increased from 21 250 mg/L to 36 500 mg/L, the mercury removal efficiency dropped from 95% to 58%. The synergistic mercury removal performance is slightly lower compared with the high loading conditions.