Addition of organophosphonates for size control of wet calcium-based FGD byproduct solids under inhibited oxidation conditions
AssigneeElectric Power Research Institute, Inc.
InventorsRobert E. Moser, Frank B. Meserole, Gordon Maller
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Abstract
A process for producing large, regularly-shaped crystalline calcium sulfite solids in a wet calcium-based flue gas desulfurization system is provided. A chemical crystal modifier, preferably an organophosphonate, is added to the calcium sulfite-containing solids slurry produced by the FGD process under inhibited oxidation conditions at an addition level which promotes the formation of large, regular calcium sulfite crystals that are easily dewatered.
Claims11
A method for improving the properties of calcium sulfite solids produced as a byproduct of a wet calcium-based flue gas desulfurization process conducted under inhibited oxidation conditions to favor the formation of calcium sulfite over calcium sulfate, consisting essentially of contacting a sulfur oxide-containing gas with calcium to produce calcium sulfite solids;
- adding to said calcium sulfite solids an amount of a crystal growth habit modifier selected from the group consisting of organophosphonates and polyphosphates which inhibits nucleation of a greater extent than crystal growth sufficient to produce substantially regularly-shaped calcium sulfite crystals greater than 50 microns in size;
- and recovering substantially regularly-shaped calcium sulfite crystals greater than 50 microns in size.
A method for improving the properties of calcium sulfite solids produced as a byproduct of a wet calcium-based flue gas desulfurization process wherein the oxidation of calcium sulfite to calcium sulfate is inhibited by the addition of thiosulfate, comprising contacting a sulfur oxide-containing gas with calcium to produce calcium sulfite solids and adding 20-200 ppm of aminotri (methylene phosphonic acid) to a slurry of said calcium sulfite solids to produce substantially regularly shaped calcium sulfite crystals greater than 50 microns in size.
Dependencies are inferred from the claim text.