Limestone (Lime) Gypsum Flue Gas Desulfurization

Working principle:

Use lime or limestone slurry absorb SO2 in flue gas, react to generate calcium sulfite, then oxidize calcium sulfite to annaline. Co-Product gypsum can be recyclable.

Chemical reaction:

1. Absorption process is in the absorption tower, the main reaction is as follows:

lime slurry as absorber: 

Ca(OH)2+SO2→CaSO3·1/2H2O

limestone slurry as absorber： 

Ca(OH)2+1/2SO2→CaSO3·1/2H2O+CO2

CaSO3·1/2H2O+CO2+1/2HO2→Ca(HSO3)

Due to contain oxygen in the flue gas, the following reaction will occur:

2CaSO3·1/2H2O+O2+3H2O→2CaSO4·2H2O

2. Oxidation process carry out in the oxidation zone, the main reaction is as follows:

2CaSO3·1/2H2O+O2+3H2O→2CaSO4·2H2O

Ca(HSO3)2+1/2O2+H2O→CaSO4·H2O+SO2

Advantages:

Mature technology, high reliability running, wide range of applications. Sulfur dioxide removal efficiency up to 95%, can adapt to large capacity unit and high concentrations of sulfur dioxide in flue gas esulfurization. Absorber is cheap, and can be produced by-product - gypsum with a commercial value of complex utilization.