Conrad F Cornell

US Patent:

39894649, Nov 2, 1976

Filed:

Feb 24, 1975

Appl. No.:

5/552407

Inventors:

Donald A. Dahlstrom - Salt Lake City UT
Conrad F. Cornell - Salt Lake City UT

Assignee:

Envirotech Corporation - Menlo Park CA

International Classification:

B01J 100
B01J 800

US Classification:

23260

Abstract:

Sulfur dioxide is scrubbed from stack gases in an absorption device by a sodium-based aqueous scrubbing solution, a portion of which is subsequently and continuously regenerated outside the absorption apparatus by a causticizing reaction with slaked lime. The causticized solution is routed through a settling device wherefrom a portion of the aqueous sediment is returned to the causticizing zone to provide seed crystals which encourage the formation of larger sized solid particles; also, a portion of the aqueous sediment from the settling device is continuously mechanically dewatered and then removed from the system. The liquid effluent solution from the settling device is passed to a solids-contacting and reaction device for mixing with sodium carbonate in order to reduce the calcium ion concentration and the solids content of the solution. The underflow of the solids-contacting device is conveyed back to the causticizing zone and the clarified overflow, i. e. , the regenerated scrubbing liquor, is conveyed to the absorption apparatus.