Use

Lime/limestone – FGD gypsum is the basicprinciple of using lime and limestone slurry to absorb the SO2 in flue gas, reaction calciumsulfite, then put the oxidation of calcium sulfite to calcium sulfate. The by-product gypsum can abandon alsocan be recycled.

Reaction principle

1.Theabsorption process in the absorption tower, main reactions are as follows:

Lime slurry withabsorbent: Ca(OH)2+SO2-CaSO3▪1/2H2O

The limestone slurry sorbent: Ca(OH)2+1/2SO2-CaSO3▪1/2H2O+CO2

CaSO3▪1/2H2O+CO2+1/2HO2-Ca(HSO3)2

Because the smoke contains oxygen, butalso the following side effectsoccur:

2CaSO3▪1/2H2O+O2+3H2O-2CaSO4▪2H2O

2.Oxidation process in the oxidation tower, main reactions are as follows:

2CaSO3▪1/2H2O+O2+3H2O-2CaSO4▪2H2O

Ca(HSO3)2+1/2O2+H2O-CaSO4▪H2O+SO2

Advantages

Technology is mature, higherreliability, wide application.Carbondesulfurization rate can reach more than 95%, able to adapt to the largecapacity units, high concentration of sulfur dioxide flue gas desulfurization,absorbent is cheap, and can produce has the commercial value of comprehensiveutilization of by-product gypsum.