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

摘要

A wet flue gas desulfurization process and apparatus (10) for removing sulfu r dioxide from flue gases. The process utilizes an ammonium sulfate scrubbing solution (22) into which is injected ammonia diluted with water and oxygen, which react with sulfur dioxide absorbed in the solution (22) to produce ammonium sulfate as a valuable byproduct. The scrubbing solution contacts th e flue gases and absorbs sulfur dioxide within an absorber (12) of a flue gas scrubbing apparatus (10), and is then accumulated in a vessel (18) having a bottom wall (36) and a side wall that defines a cross section of the vessel (18). Localized high pH and ammonium sulfite levels within the scrubbing solution (22) are avoided by introducing the dilute ammonia at the bottom wa ll (36) of the vessel (18) so that the fluid is uniformly dispersed across the cross section of the vessel (18) prior to becoming intermixed with the remainder of the scrubbing solution (22) in the vessel (18) and prior to the scrubbing solution (22) being recirculated to the absorber (12) of the apparatus (10). The dilute ammonia is preferably formed by mixing air with ammonia and water, which are then simultaneously dispersed near the bottom wall (36) of the vessel (18) through a plurality of conduits (34) that exten d across the cross section of the vessel (18) and inject the mixture toward th e bottom wall (36).