Removal of sulfur oxides from gas streams with ammonium sulfite

Claim 1

A process for removal of sulfur oxides from sulfur oxide containing flue gases comprising scrubbing the flue gases in the first stage scrubber with an ammomium sulfite solution to remove most of the sulfur oxides and producing a liquor comprising ammonium sulfite, bisulfite and sulfate salts; recycling the liquor in the first stage scrubber and producing a 40% to 50% solution of dissolved ammonium sulfite, bisulfite and sulfate salts in a first stage reservoir while maintaining the pH between about 5 and 5.8; maintaining the ratio of bisulfite to sulfite between approximately 2.3 to 1 and 1 to 1 without liberating ammonia; removing portions of the 40% to 50% solution of dissolved salts from the first stage reservoir; scrubbing the flue gases in a second stage scrubber with an ammonium sulfite solution of pH between 6.2 and 6.8 to remove additional sulfur oxides and producing a dilute liquor of 1% to 10% solids comprising ammonium sulfite, bisulfite and sulfate salts in a second stage reservoir; and pumping the dilute liquor from the second stage reservoir to the first stage reservoir in amounts sufficient to replace the said removed portions.