Abstract: An ammonia-based double-alkali process for removing sulfur oxides from stack gases. In this process, usually continuous, stack gases are contacted with an aqueous wash liquid containing ammonium sulfite as a sulfur oxide reactive compound to form a spent absorbent liquor containing bisulfite, sulfite and sulfate salts of ammonia. A portion of the reactive compound is regenerated by reacting the spent scrubbing liquor with a source of calcium ions, usually limestone. During the regeneration, calcium sulfite solids are precipitated as a by-product, any gypsum solids precipitation during the process being tolerated for a time insufficient to degrade substantially process performance. The resultant calcium solids are separated from the regenerated liquor which is returned for further contact with the stack gases, a portion of these solids being recycled to the regeneration stage.
Type:
Grant
Filed:
September 22, 1978
Date of Patent:
November 4, 1980
Assignee:
Smelter Control Research Association, Inc.
Inventors:
Ivor E. Campbell, James M. Henderson, Walter Johnson, William H. Wetherill