Treatment of a gas stream containing hydrogen sulphide

A method of treating a sour gas containing hydrogen sulphide, comprising the steps of:

• a) selectively absorbing hydrogen sulphide from the sour gas and from a recycle gas in a selective absorbent of hydrogen sulphide;
• b) generating a feed gas stream containing hydrogen sulphide by stripping absorbed gas from the selective absorbent;
• c) burning in a furnace part of the hydrogen sulphide content of the feed gas stream so as to form sulphur dioxide and water vapour, supplying oxygen-enriched air or oxygen to the furnace to support combustion of the-said part of the feed gas, and reacting in the furnace resulting sulphur dioxide with hydrogen sulphide so as to form an effluent gas stream containing sulphur vapour, water vapour, hydrogen sulphide, and sulphur dioxide;
• d) extracting the sulphur vapour from the effluent gas stream so as to form a sulphur-depleted gas stream and subjecting said sulphur-depleted gas stream to a catalytic reaction between sulphur dioxide and hydrogen sulphide to form sulphur;
• e) reducing to hydrogen sulphide essentially the entire content of sulphur dioxide and sulphur vapour in the sulphur-depleted gas stream so as to form a reduced gas stream wherein said sulphur from said step (d) is allowed to pass to step (e);
• f) removing most of the water vapour from the reduced gas stream so as to form a water vapour depleted gas stream;
• and
• g) returning at least part of the water vapour depleted gas stream to said step (a) as the recycle gas.