Application Research of White Mud in 660 MW Unit FGD System

摘要

White mud is generally known as the residue of soda ash production by ammonia-soda process. The treatment of it has been one problem in soda ash industry due to the large amount of production, strong alkalinity and corrosiveness. In China, the treatment of white mud is stacking currently, which not only occupying land but also causing environment pollution. The main composition of it is the calcium carbonate. If white mud replaces the limestone as the desulfurization agent in wet Flue Gas Desulfurization (W-FGD) system, it can attain the goal of treating the waste with another, achieve the circular economy between enterprises, and reduce the desulfurization cost significantly. In this paper, the research of white mud in 660 MW Unit W-FGD systems was investigated. Study shows that the properties of white mud and limestone are significantly different. Because of smaller particle size and active MgO, the alkaline and reaction activity of white mud are better than that of limestone, results to higher desulfurization rate and lower running cost. However, the purity of white mud is lower because of CaSO_4, Cl~-, and other impurities, so the dewatering system of gypsum needs to increase output by about 17%; the output of the slurry feed system needs to be increased by about 30%; the discharge capacity of wastewater needs to be increased by about 23 t/h.