Metallgesellschaft Aktiengesellschaft

Anton Hude

Manfred Kriebel

Alexander Doerges

Johann Schlauer

The gas which contains sulfur compounds consisting of H.sub.2 S and/or COS is scrubbed with an absorbent solution which contains at least one amine. The gas to be desulfurized which enters the scrubbing zone is at a temperature in the range of 25.degree. to 100.degree. C. and rises in the scrubbing zone in a countercurrent to the scrubbing solution. The gas leaving the absorbent solution is indirectly cooled to a temperature which is at least 20.degree. C. below the entrance temperature of the gas and is not below 5.degree. C. The indirect cooling results in a condensate, which contains at least one secondary amine. That condensate is passed through the scrubbing zone as an absorbent solution. The condensate leaving the scrubbing zone contains at least 10 moles secondary amine and preferably at least 100 moles secondary amine per mole H.sub.2 S and COS in the gas to be desulfurized. The gas to be desulfurized suitably contains secondary amine used in the absorbent solution as well as an organic solvent, such as methanol, ethanol or isopropanol.

Process of desulfurizing gases with an amine-containing absorbent

In a process of regenerating laden absorbent solutions used to desulfurize gases which contain H.sub.2 S and CO.sub.2 and possibly COS, which solutions contain at least one highly volatile secondary amine in an organic solvent, the laden absorbent solution is flashed and stripped with its own vapor. The overhead vapors from the regenerator, which consists of an indirectly heated plate column, are cooled to approximately ambient temperature. The resulting condensate is separated and fed to the top of the regenerator. The cooled gas is withdrawn. A partial stream of the vapor is withdrawn from the regenerator 1 to 10 plates below the outlet for the overhead vapors and the inlet for the condensate and is cooled to ambient temperature. The resulting condensate is fed to the regenerator 1 to 10 plates above the inlet for the absorbent solution. The remaining gas is fed to a re-absorber, in which it is scrubbed in a counter-current operation with at least one partial stream of the absorbent solution, preferably with the effluent from the desulfurization COS. The exhaust gas is withdrawn from the top of the re-absorber. The absorbent solution drained from the re-absorber is fed to the upper portion of the regenerator. The regenerated absorbent solution is withdrawn and used to desulfurize gases which contain H.sub.2 S and CO.sub.2 and possibly COS.

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Frankfurt am Main, Germany

Anton Hude