Hydrogen sulphide, ammonia and hydrogen cyanide absorption from process gas - by using circulating wash contg. aq. ammonium soln. and clean water and working up loaded absorption soln. obtd. from hydrogen sulphide absorber by reverse osmosis

摘要

Absorption comprises using A) a known NH3/H2S circulating wash comprising an aq. NH4OH soln. and clean water to final deg. of cleaning of 0.2g H2S/Nm3 and B) working up loaded absorption soln. emerging from the H2S absorber using a reverse osmosis membrane. The permeate with the low H2S content is recirculated directly as NH3/aq. soln. to the H2S absorber, Absorbed NH3 and H2S is sepd. from the retentate contg. the high H2S concn. using a thermal regeneration system and is partially recirculated as low H2S, NH3/aq. soln. to the H2S absorber. The wt. ratio is a single step reverse osmosis system of NH3:H2S in the loaded absorption soln. is 3-4, in the retentate is 2-3 and in the permeate is 10-14 for an NH3 content above 9g/ltr. The sepn. membrane is made of a polyamide polyamide or polyurea. ADVANTAGE - Significant saving of energy