燃煤电厂协同脱汞研究进展及强化措施

Research on synergistic mercury removal of coal-fired power plants

燃煤电厂是大气汞排放的重要源头,但是我国目前尚无完善的烟气汞控制方案。本文简要综述了国内外烟气脱汞技术研究现状,统计了国内污控设备(包括脱硝设备、除尘设备和脱硫设备)的装机容量。指出污控设备对烟气汞具有一定的协同脱除作用,但是受到我国煤质及运行条件等因素的制约,效果并不理想。本文结合国内某燃煤电厂的实测情况,提出了以下强化措施:①通过添加溴盐溶液,提高选择性催化还原(SCR)对烟气汞的氧化效率;②通过粉末活性炭与溴盐联合使用,强化静电除尘器(ESP)对烟气汞的协同脱除效率,脱汞效率可达90%以上;③通过精确控制脱硫浆液的pH值以及定期外排脱硫浆液,以降低其中汞的再释放率,维持湿法脱硫工艺(WFGD)稳定的烟气汞协同脱除效率;④通过优化和调整锅炉运行条件,提高现有污控设备体系的协同脱汞能力。

Coal-fired power plants (CFPPs) are major contributors of atmospheric mercury emissions;however,mercury removal from coal combustion flue gas is not mature in China. This paper briefly introduced current research progresses of mercury removal from flue gas of CFPPs and provided statistics data on installed capacity of domestic air pollution control devices (APCDs) including de-NOx equipment,de-dust equipment and desulfurization equipment. APCDs have synergistic effects on flue gas mercury removal,but the results are unsatisfactory due to the restrictions of coal quality,operating conditions,etc. Considering experiment results and operating conditions in a domestic CFPP,the following solutions were suggested:①adding oxides,which can enhance the oxidation efficiency of flue gas mercury in selective catalytic reduction (SCR) reactor;②spraying powdery activated carbon in combination with bromines to strengthen synergistic removal effect of flue gas mercury in electrostatic precipitator (ESP),which may mercury removal efficiency more than 90%;③precise control of the pH value of desulfurization slurry and regularly discharging desulfurization slurry to reduce re-release rate of mercury,which can stabilize synergistic mercury removal effect in wet flue gas desulfurization (FGD);④adjusting and optimizing the boiler operating parameters to improve synergistic mercury removal capacity in APCDs system.