镁法脱硫废水提浓及循环利用

Concentration and Recycling Technology of Magnesium Flue Gas Desulfurization Wastewater

针对镁法烟气脱硫系统存在的工艺用水量大、废水排放量大、亚硫酸根含量高、硫酸镁无法直接回收等问题,提出脱硫废水提浓及循环利用工艺,通过在脱硫塔循环管路上增配射流器、更换氧化槽催化剂、增设废水回流系统的措施,强化亚硫酸镁的氧化进程,提高其转化效率,在废水循环利用过程中实现硫酸镁浓度的大幅提升,为后续副产物的资源回收做好准备。实际运行情况显示,浓缩工况下脱硫废水中硫酸镁的浓度可由原系统的1%提升至20%,此时催化剂的用量是原系统的1/4,脱硫废水日排放量可减少90%以上,脱硫工艺日耗水量也可大幅减少(>85%),从而使得脱硫系统日运行成本大幅降低。

To solve a series of problems of magnesium flue gas desulfurization system, such as large process water consumption, large wastewater discharge, high sulfite concentration and unable direct magnesium sulfate recycle, an improved process for concentration and recycling of desulfurization wastewater was proposed. Several measures including equipping ejector on the spray line, replacing the catalyst and adding wastewater return pipe to the desulfurization system, were taken to strengthen the magnesium sulfite oxidation process and improve the conversion efficiency, thus the concentration of magnesium sulfate could be greatly increased during recycling, which was in favor of subsequent by-product recycling. According to the operational results, the concentration of magnesium sulfate could be increased from 1% to 20% when decreasing catalyst amount to a quarter of that in the original system. The daily wastewater discharge and water consumption could reduce by more than 90% and 85% respectively, thus the operating cost was significantly reduced.