PROCESS FOR CONTROLLING AMMONIA SLIP IN THE REDUCTION OF SULFUR DIOXIDE EMISSION

A wet flue gas desulfurization process for removing sulfur dioxide from flue gases. The process utilizes an ammonium sulfate scrubbing solution containing free dissolved ammonia as the reagent for the desulfurization process to produce ammonium sulfate as a valuable byproduct. The scrubbing solution contacts the flue gases and absorbs sulfur dioxide within an absorber of a flue gas scrubbing apparatus, and is then accumulated in a tank where the absorbed sulfur dioxide is reacted with oxygen and ammonia to produce ammonium sulfate. The scrubbing solution has a concentration of greater than 46% ammonium sulfate so as to have suspended solids of ammonium sulfate precipitate, preferably 1% to 20% suspended solids.