Sodium-enhanced lime scrubbing method for removing sulfur dioxide from gaseous streams
AssigneesSouthern Indiana Gas and Electric Company, Dravo Lime Company
InventorsDennis L. Glancy, John W. College, Jim Wilhelm
Life of this patent
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Abstract
Sulfur dioxide is removed from a gaseous stream by contact with a lime slurry which contains sulfur to produce thiosulfate ions and 2,000-10,000 ppm of effective sodium ions to effect removal of the sulfur dioxide A bleed stream, removed from the scrubbing loop has calcium sulfite solids removed therefrom while separated liquor is returned to the scrubbing loop.
Claims12
In a method of removing sulfur dioxide gases from a gaseous stream where the gaseous stream is contacted with an aqueous slurry of calcium hydroxide in a wet scrubbing unit, with formation of calcium sulfite that is removed from a bleed stream from the wet scrubbing unit, the improvement comprising:
- adding sulfur to said aqueous slurry of calcium hydroxide in an amount to provide sufficient thiosulfate ions to to inhabit oxidation in said wet scrubbing unit;
- and
- adding to said aqueous slurry of calcium hydroxide a sodium compound in an amount sufficient to provide between about 2,000 to 10,000 parts per million of effective sodium ions in said aqueous slurry in said wet scrubbing unit.
In a method of removing sulfur dioxide gases from a gaseous stream where the gaseous stream is contacted with an aqueous slurry of calcium hydroxide in a wet scrubbing unit, with formation of calcium sulfite that is removed from a bleed stream from the wet scrubbing unit, the improvement comprising:
- maintaining the pH of the scrubbing slurry in said scrubbing unit between 6.0 to 7.5;
- adding sulfur to said aqueous slurry of calcium hydroxide in an amount to provide a thiosulfate ion concentration of between about 0.02 to 0.15 molar concentration to inhabit oxidation in said wet scrubbing unit;
- and
- adding to said aqueous slurry of calcium hydroxide a sodium compound in an amount sufficient to provide between about 2,000 to 10,000 parts per million of effective sodium ions in said aqueous slurry in said wet scrubbing unit.
Dependencies are inferred from the claim text.