Patent ID: 7625537

Claim:
A process for removing sulfur oxides, other acid gases, and particulate from a flue gas, said process comprising: treating the flue gas utilizing a slurry formed from water, lime, and a purge stream from a wet scrubber in a spray dryer, wherein a portion of the acid gases is removed from the flue gas and a dry by-product is produced and said purge stream is evaporated; filtering the flue gas to remove fly ash and at least a portion of said dry by-product and causing further reduction of the acid gases; wet scrubbing the flue gas exiting said spray dryer in a wet scrubber as a polishing step for removal of acid gases and particulate; adding a limestone reagent to said wet scrubber, wherein said limestone reagent reacts with at least a portion of the remaining acid gases present in said wet scrubber to produce a wet scrubber by-product; discharging said purge stream from said wet scrubber to said spray dryer; and producing gypsum from said wet scrubber by-product.