Patent ID: 6919059

Claim:
A method of treating a feed gas stream comprising hydrogen sulphide, comprising the steps of: a) in at least two furnaces in series oxidising to sulphur dioxide a part of the hydrogen sulphide content of at least one feed gas stream comprising hydrogen sulphide and reacting thus formed sulphur dioxide with residual hydrogen sulphide to form sulphur vapour and water vapour; b) withdrawing from the downstream furnace a partially reacted gas stream including sulphur vapour, water vapour, residual hydrogen sulphide and residual sulphur dioxide; c) extracting in a sulphur condenser, sulphur vapour from the partially reacted gas stream so as to form a sulphur vapour depleted gas stream; d) catalytically reducing with hydrogen to hydrogen sulphide the sulphur dioxide and any sulphur vapour content of the sulphur vapour depleted gas stream so as to form a reduced gas stream; e) extracting water vapour by condensation from the reduced gas stream so as to form a water vapour depleted gas stream; and f) feeding without recycle the water vapour depleted gas stream to at least one Claus plant for recovering sulphur from hydrogen sulphide comprising at least one further furnace for the oxidation of hydrogen sulphide to sulphur dioxide and reaction of resulting sulphur dioxide with residual hydrogen sulphide, a first further sulphur condenser, and a plurality of stages of catalytic reaction, there being a second further sulphur condenser downstream of each stage of said catalytic reaction, and thereby extracting further sulphur vapour wherein: a gas containing at least 80% by volume of oxygen molecules is employed to support combustion in step a), the water vapour depleted gas stream contains at least 40% by volume of hydrogen sulphide, and in step f) the catalytic reaction is a Claus reaction between hydrogen sulphide and sulphur dioxide or a selective oxidation of hydrogen sulphide to sulphur, or both reactions.