Sulphur recovery from gas contg. hydrogen sulphide in low concn. - by Claus process using absorption and desorption for concn. of sulphur di:oxide stream

摘要

Recovery of S from gases contg. 1-10 vol.% H2S involves oxidn. of the H2S in one side stream, to SO2 and combination with the other side stream for catalytic Claus reaction and deposition of the S formed. Improvement is that the SO2 is scrubbed from the oxidised stream and the scrubbing liquor is regenerated, forming a conc. SO2 gas stream, which is combined with the other stream contg. H2S, whilst the waste gas from the Claus process is passed to the oxidn. stage. The SO2 is adsorbed in an aq. basic soln., esp. Na or ammonium sulphite soln., which is regenerated thermally. The Claus reaction is carried out in several (2) stages at 180-300 degrees C. The H2S can also be absorbed and the liquor regenerated to give a relatively large stream with a low H2S content (1-3 vol.%), which passes to oxidn., and a smaller stream with a higher H2S content (6-10 vol.%), which passes directly to the Claus process. S yields of 98.5-99% or over can be obtd. from gases with alow H2S content or min. investment.