Combustion Equipment Associates, Inc.

James E Oberholtzer

James R Valentine

Edwin L Field

Richard R Lunt

Charles R Lamantia

Method and apparatus for removing sulfur dioxide from stack gases. The stack gases are scrubbed with an aqueous wash liquid containing one or more alkali metal compounds which react to form the bisulfite, sulfite and sulfate salts of the alkali metal. The spent absorbent liquid effluent is then treated with calcium compounds in at least two separate reaction stages, the conditions of ion concentration and pH of the first stage being maintained to favor the precipitation of calcium sulfate in the presence of SO.sub.3.sup.= ions. In the succeeding reaction stages the precipitation of the desired amount of SO.sub.3.sup.= ions is carried out to form calcium sulfite. The resulting compound of calcium with sulfite and sulfate (which may in part be in the form of mixed crystals) are removed and the regenerated liquid is recycled.

Apparatus for removing sulfur dioxide from stack gases

Method and apparatus for removing sulfur dioxide from stack gases. The stack gases are scrubbed with an aqueous wash liquid containing one or more alkali metal compounds which react to form the bisulfite, sulfite and sulfate salts of the alkali metal. The spent absorbent liquid effluent is then treated with calcium compounds in at least two separate reaction stages, the conditions of ion concentration and pH of the first stage being maintained to favor the precipitation of calcium sulfate in the presence of SO.sub.3.sup.= ions. In the succeeding reaction stages the precipitation of the desired amount of SO.sub.3.sup.= ions is carried out to form calcium sulfite. The resulting compounds of calcium with sulfite and sulfate (which may in part be in the form of mixed crystals) are removed and the regenerated liquid is recycled.

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Lexington, MA, United States of America

James E Oberholtzer