Gypsum method
Limestone-gypsum desulfurization process is the most widely used desulfurization technology in the world.
Wet desulfurization process flow chart, about 90% of flue gas desulfurization devices used in thermal power plants in Japan, Germany and the United States adopt this process.
Its working principle is that limestone powder is added with water to make slurry, which is pumped into the absorption tower as an absorbent to fully contact and mix with flue gas. Sulfur dioxide in flue gas reacts with calcium carbonate in slurry and air blown from the lower part of the tower to generate calcium sulfate. When the calcium sulfate reaches a certain saturation, it crystallizes to form gypsum dihydrate. The gypsum slurry discharged from the absorption tower is concentrated and dehydrated to make its water content less than 10%, and then sent to the gypsum storage bin for stacking by the conveyor. The desulfurized flue gas passes through a demister to remove fog droplets, then is heated by a heat exchanger, and then is discharged into the atmosphere through a chimney. Because the absorbent slurry in the absorption tower repeatedly contacts the flue gas through the circulating pump, the utilization rate of absorbent is high, calcium and sulfur are low, and the desulfurization efficiency can be greater than 95%.
System composition:
(1) limestone storage and transportation system
(2) limestone slurry preparation and supply system
(3) Flue gas system
(4)SO2 absorption system
(5) gypsum dewatering system
(6) gypsum storage and transportation system
(7) Mud discharge system
(8) Process water system
(9) Compressed air system
(10) wastewater treatment system
(1 1) oxidation air system
(12) electrical control system
Technical features:
(1) Absorbent has a wide range of applications: various absorbents can be used in FGD devices, including limestone, lime, magnesium oxide, waste lye, etc.
⑵. Wide application range of fuel: suitable for tail gas treatment of coal-fired, heavy oil, orimulsion and petroleum coke boilers;
(3) Strong adaptability to the change range of fuel sulfur content: flue gas with fuel sulfur content as high as 8% can be treated;
(4) Strong adaptability to load change of the unit: it can ensure the stable operation of the unit within the range of 15 ~ 100% load change;
5. High desulfurization efficiency: generally greater than 95%, up to 98%;
[6], patented tray technology: effectively reduce the liquid/gas ratio, which is beneficial to uniform air distribution in the tower, save materials and energy consumption, and facilitate the maintenance of the internals of the absorption tower;
(7) High utilization rate of absorbent: the ratio of calcium to sulfur is as low as1.02 ~1.03;
(8) High purity of by-products: commercial gypsum with a purity of over 95% can be produced;
(9) High dust removal efficiency of coal-fired boilers: 80% ~ 90%;
⑽. Cross spray pipe layout technology: it is beneficial to reduce the height of absorption tower.
Recommended application scope:
(1), 200MW and above large and medium-sized new or modified units;
(2) The sulfur content of coal is 0.5 ~ 5% or above;
(3) The desulfurization efficiency should be above 95%;
(4) Areas with abundant limestone resources and comprehensive utilization of gypsum.
Its function is to keep the highest water level, and at the same time let the air in the water be discharged from here to avoid the loss of air resistance caused by being brought into the pipeline system. The lower part of the circulating water tank is provided with a cold water inlet baffle. In this way, when the cold water enters the circulating water tank, it will diffuse through the baffle and will not mix with the hot water at the upper part of the water tank.