Gypsum method

Air is pumped into the slurry of the absorber, forcing CaSO3 to oxidize to CaSO4(gypsum), a by-product of desulfurization. At the same time, the injected air produces a more uniform slurry, which is easy to reach the desulfurization rate of 90%, and easy to control scaling and blockage.

Main advantage of limestone/gypsum method is: the applicable range, high desulfurization efficiency of coal (some devices the Ca/S = 1, the desulfurization efficiency is more than 90%), high utilization rate of absorbent (can be greater than 90%), high operation rate (up to more than 90%), high reliability of the work (the most mature of flue gas desulfurization process), desulfurizer, the limestone source is rich and cheap. However, the disadvantages of the limestone/gypsum method are also obvious: the initial investment cost is too high, the operation cost is high, the area is large, the system management operation is complex, the wear and corrosion phenomenon is more serious, the by-product - gypsum is difficult to deal with (because of the sales problem can only pile up), the waste water is difficult to deal with.

2. Magnesium oxide method

MgO was used as desulfurization absorber in magnesium oxide wet desulfurization process. Will MgO style made by sorbent slurry preparation system of Mg (OH) 2 supersaturated liquid, supersaturated fluid through the pump into the absorption tower and a good contact with flue gas, make the two sulfur nitride in flue gas and slurry of Mg (OH) 2 to generate MgSO3 reaction, from absorption tower of eduction and magnesium sulfate slurry concentration, dehydration, make its moisture content is less than 10%, with the conveyor to the magnesium sulfate tanks, the temporary storage according to the usage of by-product in sealed tank car away.

The process is suitable for flue gas desulfurization of any kind of coal with sulfur content, and the desulfurization efficiency can reach more than 95%.

3. Seawater method

Seawater desulfurization process is a desulfurization method to remove SO2 from flue gas by using the alkalinity of seawater. In the desulfurization absorption tower, a large amount of seawater is sprayed to wash the coal-fired flue gas entering the absorption tower. The SO2 in the flue gas is absorbed by seawater and removed. After absorbing SO2, the seawater is aerated by an aeration tank, and the SO32- is oxidized into a stable SO42- and then discharged into the sea.

Seawater desulfurization is generally applicable to the flue gas desulfurization of power plants near the sea with good diffusion conditions, using seawater as cooling water and burning low-sulfur coal.

4. Double-base method

The double-base flue gas desulfurization technology USES sodium hydroxide solution as the starting desulfurizer, and the prepared sodium hydroxide solution is directly driven into the desulfurization tower to wash and remove the SO2 in flue gas to achieve the goal of flue gas desulfurization, and then the desulfurization product is reduced to sodium hydroxide through the desulfurizer regeneration pool and then returned to the desulfurization tower for recycling.

Advantages of double-base desulfurization technology:

The desulfurization efficiency is over 90%.

The desulfurizer adopts sodium alkali and lime, the clear liquid in the tower is absorbed, and scale formation in the tower is avoided effectively.

Liquid gas ratio is small. Integration of desulfurization and dust removal.

A provincial investment, low operating costs, high degree of domestic.

Wide range of adaptation.

5. Ammonia desulfurization

Ammonia method is an efficient and low energy consumption wet method. Ammonia method is a gas - liquid phase reaction, the reaction rate is fast, the absorber utilization rate is high, can maintain the desulfurization efficiency of 95-99%. Ammonia is more than 20% soluble in water.

The most important characteristic of the ammonia method is the resourceability of SO2, which can recover the pollutant SO2 into a commercial product with high added value. Ammonium sulfide, a by-product, is a kind of nitrogen fertilizer with excellent performance and has a good market prospect in China.