The typical flow of this process is as following: the flue gas from the boiler induced draft fan is boosted by the booster fan and then enters the lower part of the absorption tower. The absorbent, i.e., limestone slurry in the absorption tower is sprayed downward from the upper part of the tower and mixed with the upward flowing flue gas in countercurrent. Sulfur dioxide (SO2) in the flue gas reacts with the absorbent slurry to generate calcium sulfite, which is oxidized into calcium sulfate dihydrate (CaSO4•2H2O), i.e., gypsum, in the slurry pool of the absorption tower. The desulfurized clean saturated flue gas is purified by demister and WESP in turn, and then discharged into the atmosphere through chimney.
The absorbent limestone slurry can be ground by wet ball mill or directly prepared by limestone powder and water. Gypsum slurry produced by desulfurization reaction is sent to hydrocyclone station, after primary dehydration of gypsum, it is sent to vacuum belt filter for further dehydration to produce gypsum.