Patent ID: 6066304
Filing Date: 2000-05-23
Classification: B01D

Abstract:
A method for reducing the concentration of sulfur dioxide in a flue gas, comprising contacting the flue gas with a scrubbing liquid comprising diammonium phosphate and ammonium sulfite at a pH so that the sulfur dioxide is sorbed into the scrubbing liquid and reacts with the diammonium phosphate to produce a scrubbing liquid comprising monoammonium phosphate and ammonium bisulfite and a gas having a diminished concentration of sulfur dioxide;reacting a portion of the scrubbing liquid with ammonia to form a scrubbing liquid comprising ammonium sulfite and diammonium phosphate;contacting said portion of the scrubbing liquid with oxygen to produce a scrubbing liquid comprising ammonium sulfate and diammonium phosphate; andthen returning said portion of the scrubbing liquid for further scrubbing of flue gas, in order to maintain the total concentration of phosphates and the total concentration of sulfites in the scrubbing liquid contacting the flue gas in a balance so as to minimize the formation of plumes of ammonium sulfite.