Gas absorption treatment system: high temperature flue gas often contains H2S, SO2, HF and HCl Generally, the air content accounts for a large proportion, and the pressure drop required for the system is low. The exhaust gas discharged from the system should meet the environmental protection emission index. Under such conditions, the above process configuration is usually used, which is generally three-stage absorption, and the fourth stage water or alkali absorption can be increased to lower the harmful components in the tail gas. Under certain circumstances, we can make the flue gas containing HCl absorb and generate This process has been widely used. The typical project is Changshu sanaifu's stable cold absorption of flue gas containing fluorine at 1100 ° C to produce hydrofluoric acid of more than 30%.