Abstract: A method for recovering a helium product fraction (6) from a nitrogen- and helium-containing feed fraction (3) is described, wherein the nitrogen- and helium-containing feed fraction (3) is partially condensed (E1), separated into a first helium-enriched fraction (5) and a first nitrogen-enriched fraction (8) and the former is cleaned again in an adsorptive manner. According to the invention, the separation is carried out in a separation column (T), which is supplied with the first nitrogen-enriched fraction (8) as return flow and with a sub-flow of the second nitrogen-enriched fraction as stripping gas (12), wherein the stripping gas quantity (12) is set such that a third nitrogen-enriched fraction (20), which contains at least 30% of the nitrogen contained in the first nitrogen-enriched fraction (8), can be recovered in the separation column (T).

Abstract: The invention relates to a method for the separation of a hydrocarbon-rich, nitrogen-containing feed fraction (1, 101), preferably natural gas, wherein the feed fraction (1, 101) is at least in part liquefied (E1, E2) and divided by rectification (T1) into a nitrogen-enriched fraction (14, 110) and a hydrocarbon-rich, nitrogen-depleted fraction (11, 111) and wherein, in the upper region of the rectification (T1), a nitrogen-enriched stream (14) is taken off, cooled (E3) and applied (20) at least in part to the rectification (T1) as reflux and/or the nitrogen-enriched fraction (110) is cooled and partially condensed (E3), applied at least in part to the rectification (T1) as reflux (115) and the remaining stream (116) of the nitrogen-enriched fraction (110) is subjected to a double-column process (T3).

Abstract: A method for liquefying a hydrocarbon-rich fraction, in particular natural gas, by indirect heat exchange with the refrigerant blend of a refrigerant blend circuit is described, wherein the refrigerant blend is compressed, separated into a liquid phase which is rich in higher-boiling components (HMR) of the refrigerant blend and a gas phase which is rich in lower-boiling components (LMR) of the refrigerant blend, and said phases are mixed before the indirect heat exchange.

Abstract: Described herein is a process for liquefying a hydrocarbon-rich fraction, in particular natural gas, is described, in which the hydrocarbon-rich fraction that is to be liquefied is cooled in indirect heat exchange against a multistage precooling circuit, the refrigerant of the precooling circuit is at least 95% by volume carbon dioxide, the cooled hydrocarbon-rich fraction is liquefied and subcooled in indirect heat exchange against a mixed cycle, and the mixed refrigerant of the mixed cycle comprises exclusively the component(s) nitrogen, methane and/or ethane.

Abstract: The invention relates to a method for the separation of a hydrocarbon-rich, nitrogen-containing feed fraction (1, 101), preferably natural gas, wherein the feed fraction (1, 101) is at least in part liquefied (E1, E2) and divided by rectification (T1) into a nitrogen-enriched fraction (14, 110) and a hydrocarbon-rich, nitrogen-depleted fraction (11, 111) and wherein, in the upper region of the rectification (T1), a nitrogen-enriched stream (14) is taken off, cooled (E3) and applied (20) at least in part to the rectification (T1) as reflux and/or the nitrogen-enriched fraction (110) is cooled and partially condensed (E3), applied at least in part to the rectification (T1) as reflux (115) and the remaining stream (116) of the nitrogen-enriched fraction (110) is subjected to a double-column process (T3).

Abstract: A process is described for separating off a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is separated by rectification into a nitrogen-rich fraction and a methane-rich fraction and wherein the methane-rich fraction for the purpose of cold generation is vaporized and superheated at a pressure as high as possible against the feed fraction which is to be cooled. According to the invention the still liquid or partially vaporized methane-rich fraction (5?) is fed to a circulation vessel (D), only the liquid fraction of the methane-rich fraction (5?) occurring in the circulation vessel (D) is completely vaporized, preferably in natural circulation, and the top product (7) of the circulation vessel (D) is superheated (E1).

Abstract: A process is described for separating off a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is separated by rectification into a nitrogen-rich fraction and a methane-rich fraction, the methane-rich fraction, for the purpose of cold generation at a pressure as high as possible, is vaporized against the feed fraction which is to be cooled and superheated and the nitrogen-rich fraction is compressed at least occasionally and/or at least in part and is fed to the rectification as reflux stream. According to the invention at least occasionally at least a substream (16) of the compressed (C) nitrogen-rich fraction (9?) is expanded (f) after condensation (E1) thereof and, for the purpose of cold generation, is at least in part, preferably completely, vaporized (E1).

Abstract: A process for liquefying a flow of natural gas with simultaneous recovery of a C3/C4-rich fraction is described, whereby the liquefaction of the flow of natural gas is carried out in heat exchange for at least one refrigerant and/or mixed refrigerant flow, and the flow of natural gas that is to be liquefied, after precooling, is subjected to a rectifying column, in which higher hydrocarbons are separated from the flow of natural gas, and then is subjected to further cooling and liquefaction, whereby a C2+-rich fraction that is recovered in the subsequent cooling of the flow of natural gas is fed to the rectifying column as a reflux liquid. According to the invention, a C4/C5-rich fraction (20, 35) is fed directly and/or indirectly to rectifying column (T1) as an additional reflux liquid, whereby the feed point of the C4/C5-rich [fraction (20, 35) is located at the top of rectifying column (T1) or is identical to the feed point of the C2+-rich fraction (5).

Abstract: This invention is a method for the recovery of elemental sulfur from a gas mixture containing H.sub.2 S. The gas mixture is first subjected to desulfurization in a Claus installation which has a thermal part and a catalytic part resulting in the recovery of elemental sulfur. Sulfur compounds still contained in the Claus tail gas are then transformed into H.sub.2 S by means of hydrogenation and, if necessary, by means of hydrolysis and the hydrogenated Claus tail gas is subjected to catalytic direct oxidation of the H.sub.2 S to elemental sulfur. The Claus installation comprises exactly one catalytic stage and the catalytic direct oxidation also takes place in exactly one reactor. Sulfur recovery rates of 99.3% to 99.6% are achieved by the method of the invention.