The Technology of Limestone Flue GAS Desulfurization
2CaCO3+H2O+2SO2＝2CaSO3·1/2H2O+2CO2↑
2CaSO3·1/2H2O+O2+3H2O＝2CaSO4·2H2O
Limestone or lime is used as desulfurization absorbent, limestone is broken and mixed with water, then ground into powder to form absorbent slurry (when lime is used as absorbent, lime powder is digested and mixed with water to make absorbent slurry).
In the absorber, SO2 in flue gas reacts with CaCO3 in slurry and oxidized air to form gypsum dihydrate, and SO2 is removed. The gypsum slurry discharged from the absorption tower is recovered after dehydration by dehydration device.
After desulphurization, the flue gas is removed from water by the mist remover, and the heat exchanger heats up and enters the chimney into the atmosphere.
The Engineering System of Limestone flue gas desulfurization
It is composed of slurry preparation system, flue gas system, absorption and oxidation system, gypsum dehydration system and discharge system.
Special Topics on Desulfurization Process Selection
Wet desulphurization is the most widely used desulphurization method, accounting for 90% of the total amount of desulfurization. According to the different raw materials of desulphurization, the common wet desulphurization process can be divided into limestone method and calcium-sodium dual-alkali method, among which limestone-gypsum method is widely used because of its strong system buffering capacity, long-term stable operation of desulphurization facilities and wide sources of desulfurizer. At present, large domestic power plants all adopt this process.
The following table mainly focuses on the comparison of several desulfurization processes that are widely used.
As can be seen from the table above, all the above methods can achieve more than 95% desulfurization efficiency. The lime/ gypsum method is the leading desulphurization technology in the world, accounting for more than 90% of all flue gas desulphurization devices. It is characterized by mature technology, high system reliability, high absorption efficiency, wide sources of absorbent and wide application scope.
Analysis of Operating Cost
1. The amount of SO2 removed annually
2. Power consumption of desulfurization system
3. Consumption calculation
3.1 Consumption and costs of desulfurizer
3.2 Electricity charges
3.3 Labor costs
3.4 Water consumption costs
The design data, specific parameters related to the list, operation cost and implementation plan need to be calculated according to the actual situation.
