Limestone/lime–gypsum desulphurisation process
Product Details
I. Technical Principles
Flue gas enters the wet absorption tower of the desulphurisation unit, where it comes into counter-current contact with droplets of alkaline limestone slurry sprayed from top to bottom. The acidic oxide SO₂ and other pollutants, such as HCl and HF, are absorbed, thereby purifying the flue gas; Following the absorption of SO₂, the slurry reacts to form CaSO₃, which undergoes forced oxidation and crystallisation on-site to produce CaSO₄·2H₂O. After dehydration, this yields a commercial-grade by-product of desulphurisation—gypsum—thereby achieving comprehensive treatment of sulphur-containing flue gas.
II. Technical Features
(1) Wide range of suitable absorbents: A variety of absorbents can be used in FGD units, including limestone, lime, magnesite and spent soda solution;
(2) Wide range of suitable fuels: Suitable for flue gas treatment in boilers burning fuels such as coal, heavy oil, ory oil and petroleum coke;
(3) Strong adaptability to variations in fuel sulphur content: Capable of treating flue gas with fuel sulphur content as high as 8%;
(4) Strong adaptability to variations in unit load: Capable of ensuring stable operation across a unit load range of 15% to 99%;
(5) High desulphurisation efficiency: Generally greater than 95%;
⑹ Patented tray technology: Effectively reduces the liquid-to-gas ratio, promotes uniform gas distribution within the tower, reduces material and energy consumption, and facilitates maintenance of internal tower components;
⑺ High absorbent utilisation: Calcium-to-sulphur ratio as low as 1.02–1.03;
⑻ High purity of by-products: Capable of producing commercial-grade gypsum with a purity of over 95%;
⑼ High dust removal efficiency for flue gas from coal-fired boilers: 80%–90%;
⑽ Cross-flow spray pipe arrangement technology: helps reduce the height of the absorption tower.
III. Scope of Application
⑴ Medium-to-large new or retrofitted units of 200 MW and above;
⑵ Coal with a sulphur content of 0.5–5% or higher;
⑶ Required desulphurisation efficiency of 95% or higher;
⑷ Regions with abundant limestone resources and widespread comprehensive utilisation of gypsum.
