Systems, apparatuses and methods of utilizing a Fischer-Tropsch (FT) tail gas purge stream for recycling are disclosed. One or more methods include removing an FT tail gas purge stream from an FT tail gas produced by an FT reactor, treating the FT tail gas purge stream with steam in a water gas shift (WGS) reactor, having a WGS catalyst, to produce a shifted FT purge stream including carbon dioxide and hydrogen, and removing at least a portion of the carbon dioxide from the shifted FT purge stream, producing a carbon dioxide stream and a treated purge stream. Other embodiments are also disclosed.

The present invention relates to an aqueous alkanolamine solution demonstrating low volatility comprising 2-di-methylamino-2-hydroxymethyl-1, 3-propanediol useful for removing acid gases from gaseous mixtures. Said aqueous alkanolamine solution may further comprise one or more of an acid or acid-forming compound, another amino compound, an activator, a physical solvent, or one or more other compounds used in gal-liquid treatment practices. Further, the present invention relates to a process for removing acid gases from a gaseous mixture, preferably hydrogen sulfide, comprising the step of contacting the gaseous mixture with said aqueous alkanolamine solution. Examples of the gaseous mixtures include natural gas, synthesis gas, tail gas, and refinery gas.

The invention relates to a process for removal of unwanted, in particular acidic, gas constituents, for example carbon dioxide and hydrogen sulfide, from a crude synthesis gas containing metal carbonyls by gas scrubbing with a scrubbing medium. According to the invention water is added directly into the feed conduit of the methanol water mixture containing metal sulfides before the introduction thereof into the methanol-water separating column and/or water is injected directly into the methanol-water separating column at at least one point. This avoids deposits or encrustations of metal sulfide particles in the methanol-water separating column.

The invention relates to a process for removal of unwanted, in particular acidic gas constituents, for example carbon dioxide and hydrogen sulfide, from a crude synthesis gas by gas scrubbing with a scrubbing medium. According to the invention the flash gases obtained during the decompression of the laden scrubbing medium are supplied to a recompressor in order to recycle these to the crude synthesis gas and thus utilize them materially after the recompression. Alternatively or in addition the flash gases may also be supplied to a decompression turbine to recover refrigeration and mechanical work. If the recompressor and/or the decompression turbine are/is designed to have multiple stages, the flash gases obtained at different pressure levels are preferably supplied to a corresponding pressure level of the recompressor and/or of the decompression turbine.

The invention relates to a process for removal of unwanted, in particular acidic gas constituents, for example carbon dioxide and hydrogen sulfide, from a crude synthesis gas by gas scrubbing with a scrubbing medium. According to the invention the flash gases obtained during the decompression of the laden scrubbing medium are supplied to a recompressor in order to recycle these to the crude synthesis gas and thus utilize them materially after the recompression. Alternatively or in addition the flash gases may also be supplied to a decompression turbine to recover refrigeration and mechanical work. If the recompressor and/or the decompression turbine are/is designed to have multiple stages, the flash gases obtained at different pressure levels are preferably supplied to a corresponding pressure level of the recompressor and/or of the decompression turbine.

The invention relates to novel nitrogen compounds belonging to the family of tertiary diamines of general formula (I) below, wherein R is an alkanediyl radical (CH.sub.2)n with n=2, 3, 4, 5 or 6.

##STR00001##

The compound according to the invention is for example N,N,N,N-(tetramethyl)-1,6-diamino-2,5-hexanediol or N,N,N,N-(tetramethyl)-1,8-diamino-2,7-octanediol. The invention also relates to the method for preparing them and to their use for removing acid compounds contained in a gaseous effluent.

The present invention relates to an aqueous alkanolamine solution for the removal of hydrogen sulfide from gaseous mixtures containing hydrogen sulfide. The aqueous alkanolamine solution comprises (i) an amino compound with the formula:
R.sup.1R.sup.2NCH.sub.2CH(OH)CH.sub.2OH
wherein R.sup.1 and R.sup.2 independently represent lower alkyl groups of 1 to 3 carbon atoms, (ii) piperazine, and (iii) optionally a physical solvent, wherein said solution does not contain a strong acid. Further, the present invention relates to a process for removing hydrogen sulfide from a gaseous mixture containing hydrogen sulfide, and additionally other acid gases, if present, for example carbon dioxide, comprising the step of contacting the gaseous mixture contain hydrogen sulfide with the aqueous alkanolamine solution, preferably wherein the temperature of the aqueous alkanolamine solution is equal to or greater than 140 F. Examples of the gaseous mixtures include natural gas, synthesis gas, tail gas, and refinery gas.

An absorbent solution is provided for removing acid compounds contained in a gaseous effluent and a method of removing acid compounds contained in a gaseous effluent contacts the gaseous effluent with the absorbent solution. The absorbent solution includes at least one of the following two nitrogen compounds belonging to the family of tertiary diamines: 1-dimethylamino-3-(2-dimethylaminoethoxy)-2-propanol ##STR00001## 1,1-oxybis[3-(dimethylamino)-2-propanol] ##STR00002##
and water.

The present invention relates to an aqueous alkanolamine solution for the removal of hydrogen sulfide from gaseous mixtures containing hydrogen sulfide. The aqueous alkanolamine solution comprises (i) an amino compound with the formula:

R.sup.1R.sup.2NCH.sub.2CH(OH)CH.sub.2OH

wherein R.sup.1 and R.sup.2 independently represent lower alkyl groups of 1 to 3 carbon atoms, (ii) piperazine, and (iii) optionally a physical solvent, wherein said solution does not contain a strong acid. Further, the present invention relates to a process for removing hydrogen sulfide from a gaseous mixture containing hydrogen sulfide, and additionally other acid gases, if present, for example carbon dioxide, comprising the step of contacting the gaseous mixture contain hydrogen sulfide with the aqueous alkanolamine solution, preferably wherein the temperature of the aqueous alkanolamine solution is equal to or greater than 140 F. Examples of the gaseous mixtures include natural gas, synthesis gas, tail gas, and refinery gas.

The invention relates to a process for separation or purification of gaseous streams by removal of acid gases using a liquid amine solution. The process involves the steps of contacting the gaseous stream with liquid lean amine solution in at least one continuous flow stirred-tank reactor (10; 10a, 10b; 10c); removing a sweetened gaseous flow from said continuous flow stirred-tank reactor (10); removing rich amine from said continuous flow stirred-tank reactor (10; 10a, 10b; 10c) for regeneration; passing rich amine solution through at least one flash tank stripper 20; 20a, 20b; 20c; removing acid gases and vapor from said flash tank stripper 20; 20a, 20b; 20c; removing lean amine from said flash tank stripper for recirculation to said continuous flow stirred-tank reactor (10; 10a, 10b; 10c).