Metallgesellschaft Aktiengesellschaft

Johann Schlauer

Alexander Doerges

Manfred Kriebel

Georg Kempf

Paul Rudolph

Karl Bratzler

Anton Hude

Nikola Anastasijevic

Hans-Martin Stonner

Herbert Fischer

Gert Ungar

Heinz Hiller

Eilhard Hillrichs

Volker Brucken

Winfried Zeschmar

Alexander Dorges

Ernst Stoldt

Vaclav Svoboda

An aqueous solution which contains ammonium polysulfide is proportionally added to the sour water, which contains cyanide ions, ammonium ions, and sulfide ions. At least part of the cyanide ions contained in the sour water is converted to thiocyanate ions by the ammonium polysulfide. The solution which contains ammonium polysulfide is prepared from an aqueous solution by oxidation in an electrochemical cell. That aqueous solution may consist entirely or in part of sour water.

Process for decreasing the corrosiveness of a sour water

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.

Process of regenerating absorbent solutions for sulfur-containing gases

In a process of decreasing the sulfur content of exhaust gases obtained during the recovery of sulfur from acid gases containing H.sub.2 S and other S-containing compounds in the Claus process, the acid gases which contain H.sub.2 S and other S-containing compounds are reacted in a Claus plant to form elemental sulfur. A gas which contains H.sub.2 S or SO.sub.2 is subsequently added at a controlled rate to maintain a stoichiometric ratio of 2:1 of H.sub.2 S to SO.sub.2 in the tail gas from the Claus plant. The gas which contains H.sub.2 S or SO.sub.2 may be added to the tail gas from the Claus plant or before the last contacting stage of a multistage Claus plant. During the addition of a gas which contains H.sub.2 S, the Claus plant can be operated at an H.sub.2 S to SO.sub.2 ratio of or below 2:1. During the addition of a gas which contains SO.sub.2 the Claus plant can be operated at an H.sub.2 S to SO.sub.2 ratio of or above 2:1. The H.sub.2 S and SO.sub.2 contained in the tail gas are chemically reacted to form elementary sulfur in a tail gas-desulfurizing plant and the sulfur is withdrawn.

Process of decreasing the sulfur content of exhaust gases obtained

The process of removing H.sub.2 S, CO.sub.2, COS and mercaptans from gases by absorption in an absorbent solution, which is circulated between the absorbing zone and a regenerating zone and which contains at least one organic base dissolved in methanol, has been improved. In accordance with the invention, the absorbent solution contains one or more secondary or tertiary amines general formula R.sub.1 --NH--R.sub.2 or (R.sub.1).sub.2 --N--CH.sub.2 --N--(R.sub.2).sub.2, wherein R.sub.1 and R.sub.2 means CH.sub.2 -- or --CH.sub.2 --CH.sub.3 or CH.sub.3 --CH--CH.sub.3 in a total amount of at least 0.5 to 5.0 moles per liter, and the amine has or the amines have a boiling point between 40.degree. and 110.degree. C. at 1 bar. This improvement permits a selective removal of H.sub.2 S from CO.sub.2 -containing gases.

Process of removing H.sub.2 S, CO.sub.2, COS and mercaptans from gases

An improvement in a process of regenerating a hydrocarbon laden water miscible high boiling organic solvent obtained by scrubbing a hydrocarbon-containing gas with said water miscible high boiling organic solvent at normal temperature and super atmospheric pressure, wherein the laden solvent is regenerated by flashing, heating and/or stripping, cooled and recycled to the scrubbing step, the improvement comprising:

Process of regenerating laden absorbents

In a process of selectively desulfurizing gases which contain hydrogen sulfide and carbon dioxide comprising scrubbing the gases with an aqueous potassium carbonate solution under superatmospheric pressure and at temperatures of about 100.degree. C., regenerating the laden scrubbing solution and recycling the regenerated scrubbing solution, the improvement wherein the gases to be purified are scrubbed with an aqueous potassium carbonate solution so as to maintain a mass ratio of 1.0 to 3.0 vals (gram equivalents) of alkali in the solution per mole of CO.sub.2 and H.sub.2 S in the gases to be purified, the laden scrubbing liquor is subsequently regenerated by being stripped with a gas in which a CO.sub.2 partial pressure above 0.2 bar is maintained, and the so regenerated scrubbing solution is recycled.

Process of selectively desulfurizing gases

A process for the selective removal of hydrogen sulfide from a gas containing hydrogen sulfide and carbon dioxide wherein said gas is contacted at superatmospheric pressure with an alkali metal carbonate solution, the resultant solution which contains hydrosulfide and bicarbonate is subjected to pressure reduction, the total alkali metal bicarbonate content of the resultant solution is adjusted so that it is at least 55% of the total alkali content of the solution and the said solution is then stripped and recycled to the hydrogen sulfide absorption step.

Process of regenerating alkali carbonate solutions formed by the

Gases produced by reacting fuels with oxygen containing gases and water vapor under pressure are desulfurized by scrubbing with a concentrated solution of one or more alkali salts of weak inorganic acids at a temperature near the atmospheric-pressure boiling point of the solution in a column while maintaining an exchange ratio of from 0.2 to 2.0 cubic meters of the concentrated solution per standard cubic meter hydrogen sulfide in the gas to be purified.

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Frankfurt am Main, Germany

Johann Schlauer