Sodium-limestone double alkali flue gas desulfurization process with improved limestone utilization

Abstract From the Canadian patent

A method for improving utilization of limestone in a sodium-limestone double alkali flue gas desulfurization process. Spent alkaline absorber solution con-, taining sodium sulfite and sodium bisulfite is, diverted for regeneration treatment in a series of stirred tank reactors, where it is contacted with the limestone regenerating agent. Dilute slurry from the last reactor is concentrated in a thickener and the, concentrated underflow slurry from the thickener is then treated further in an after-reactor circuit. Since the thickener underflow slurry contains residual unreacted limestone, the slurry is contacted with a side stream of spent alkaline absorber solution in the after-reactor …