Removing hydrogen sulphide from a gas mixture.

摘要

Removing hydrogen sulphide from a gas mixture comprises contacting in absorber (3) the gas mixture with absorbent to obtain loaded absorbent; introducing loaded absorbent into separation vessel (13) at a reduced pressure to obtain flash-off gas and partially regenerated absorbent; contacting in absorber (19) flash-off gas with absorbent to obtain a lean gas and loaded absorbent; regenerating loaded absorbent and partially regenerated absorbent to regenerator (30) to obtain lean absorbent and regenerator off-gas; supplying the regenerator off-gas to sulphur recovery plant (49) to obtain elemental sulphur and off-gas which includes sulphur dioxide; treating the plant off-gas in convertor (55) to convert sulphur dioxide to hydrogen sulphide to obtain reduced off-gas; mixing the lean gas from absorber (19) with the plant off-gas or with the reduced plant off-gas; and contacting the mixture of reduced off-gas and lean gas in contactor (61) with absorbent to obtain a substantially hydrogen sulphide free off-gas and loaded absorbent which is regenerated in the regenerator (30).