Gas Suspension Absorber（GSA） process is a semi-dry desulphurization technology with slaked lime as a sorbent. Removing sulfur dioxide(SO2) by intimate contact between the atomizing lime slurry and the acid constituents in the flue gas and producing calcium sulfite and calcium sulfate as by-product. One of the reasons of for the high efficiency of GSA process is that the reactor has been based on gas suspension technology. This means that a very large concentration of fly ash, dust particles and lime builds up inside the reactor. The concentration is normally 50 to 100 times as high as in a conventional reactor.

　　The chemistry in the riser section leading to elimination of the acid constituents is simplified in the following reactions:
　　2HCl + Ca(OH)2 = CaCl2 + 2H2O
　　2HF + Ca(OH)2 = CaF2 + 2H2O
　　SO2 + Ca(OH)2  = CaSO3 + H2O 
　　CaSO3 + ½O2 = CaSO4   (approx. 10% of removed SO2)

　　Advantages of GSA process
　　-- High efficiency and stable operation
　　-- Low investment cost
　　-- Low operation cost (sorbent can be re-used)
　　-- Less water consumption, no waste water need to be treated
　　-- No dewatering equipment required for by-product
　　-- Less pressure loss and reduce load of ID fan
　　-- Less space requirement and low cost of civil work
　　-- No anti-corrosive treatment is required for the stack
　　-- Simple operation and easy maintenance