Dowa Dual Alkali process

The Dowa Dual Alkali Process uses a solution of basic aluminum sulfate to absorb SO2, air injection to oxidize sulfite to sulfate, and limestone to precipitate the resulting excess sulfate in the form of gypsum. 

Dowa Also called Dowa Dual Alkali A flue-gas desulfurization process in which the sulfur dioxide is absorbed in a basic aluminum sulfate solution. The product solution is oxidized with air and reacted with limestone to produce gypsum. Developed by the Dowa Mining Company, Japan, in the early 1980s. In 1986, the process was in use in nine plants in Japan and the United States. 

Dowa process Similar to dual alkali except J.A12(S04)3 solution used in scrubber. 

The Dowa process is claimed to offer sevoal advantages in comparison with both conventional limestone/lime and sodium dual alkali systems (Nolan and Seaward, 1983). These include... 

Nolan, P. S., and Seaward, D. O., 1983, The Dowa Process Dual-Alkali Flue Gas Desulfurization with a Gypsum Product, Proceedings of Seminar on Flue Gas Desulfurization sponsored by the Canadian Electrical Association, Ottowa, Ontario, Canada, September. 

The Dowa process is another dual alkali system. It uses basic aluminum sulfate solution for SO2 removal and low-cost limestone to regenerate the aluminum sulfate. A gypsum by-product is produced. The process is common in Japan. 

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