Sulphur di:oxide removal from waste gas by wet scrubbing - using spent wash liquor contg. sulphite for softening regenerated soln. to reduce scale formation

摘要

Removal of SO2 from waste gas involves scrubbing with an alkaline soln. contg. Na, J and/or ammonium hydroxide and sulphate, which is (partly) regenerated by addn. of Ca (OH)2 and pptn. of CaSO4, then recycled. The improvement is that the regenerated soln. is mixed with spent wash liquor contg. (H) sulphite in a softening zone, before the mixt. of solns. is returned to wet scrubbing. The formation of scale to a troublesome extent is avoided simply and economically, without addn. of a foreign substance as softener.