Wet process for flue gas desulphurisation - by two stage absorption with recirculation of lime suspension giving efficient absorption and low lime loss

摘要

Wet process for desulphurisation of flue gas uses lime as absorbent. The gas contg. sulphur oxides is washed with a liq. absorbent contg. calcium hydroxide or calcium carbonate. The feature of the invention is use of two different absorption stages. The first stage is operated in a pH range of 3.5-4.5 and the second stage in a pH range of 6.5-7.5. The content of unreacted lime finally passing to the gypsum recovery plant is very low.