METHOD FOR REMOVING VIRTUALLY ALL THE SULPHUR COMPOUNDS H2S, SO2, COS AND/OR CS2 FROM SULPHUR PLANT WASTE GASES, AND RECOVERING SUCH COMPOUNDS AS SULPHUR

摘要

A waste gas is contacted with a hydrolysis catalyst for converting COS and CS2 into H2S in a unit (1) and optionally, in the presence of an air flow, with an H2S oxidation catalyst to give a hydrolysed gas (17) containing H2S and SO2 but no COS or CS2, while controlling the volume concentrations of (H2S) and (SO2) in the gas (17) in such a way that (H2S)-2(SO2) is greater than 0.2 % but does not exceed 0.5 %. Said gas (17) is fed into a Claus unit (3a) in which H2S and SO2 react to give sulphur and produce a substantially purified gas (25a) containing H2S as the only sulphur compound. The gas (25a) is injected at 80-100 °C with excess air into a catalytic unit (4a) in which the H2S is totally oxidised to sulphur. The sulphur compounds in the waste gas are virtually all recovered as sulphur.