Process for modifying the sulphur yield of a plant producing sulphur from an acid gas containing hydrogen sulphide, whereby a sulphur production plant is followed by a purification unit

摘要

The sulphur plant (1), in which the acid gas (8) and a gas containing free oxygen (9) are introduced, produces sulphur by controlled oxidation of the H2S in the acid gas and also supplies the residual gas (17b) containing H2O, H2S, SO2 and at least one of the derivatives COS and CS2. Said residual gas is contacted with a catalytic (2) for hydrolysing the COS and CS2 derivatives into H2S operating between 180 DEG C and 400 DEG C in order to produce a hydrolysed residual gas containing H2S and SO2 and essentially free from COS and CS2. The hydrolysed residual gas (38) is introduced into a purification unit (3) into which are fed H2S and SO2 in order to be reacted to form sulphur, by operating at a temperature below the dew point of the sulphur formed and to obtain in addition, as an output (29) of said unit, a purified residual gas which is then incinerated (4). The H2S resulting from the hydrolysis of COS and CS2 is almost entirely recovered in the form of sulphur in the purification unit, which enables an improved sulphur output of the overall installation.