Abstract: The invention relates to a method for resolving a hydrocarbon-rich, nitrogen-containing feed fraction (1, 1?), preferably natural gas, is described, wherein the feed fraction (1, 1?) is separated by rectification (T1, T2) into a nitrogen-enriched fraction (5) and a hydrocarbon-rich, nitrogen-depleted fraction (10), and wherein the separation by rectification proceeds in a rectification column consisting of a preseparation column (T1) and a main separation column (T2). A liquid fraction (6) is taken off from the main separation column (T2) above the feed-in site(s) of the fraction (7, 7?, 7?) that is taken off from the preseparation column (T1) and fed to the main separation column (T2), and the liquid fraction (6) is applied to the preseparation column (T1) as reflux.

Abstract: A process is described for removing a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is partially condensed and fractionated by rectification into a nitrogen-rich fraction and a methane-rich fraction. According to the invention during an interruption in the supply of the feed fraction, the separation column(s) (T1/T2) used for the fractionation by rectification and also the heat exchangers used for the partial condensation (E1) of the feed fraction and the cooling and warming of process streams occurring in the fractionation by rectification (E2) are kept by means of one or more differing cooling media (6-11) at temperature levels which correspond essentially to the temperature levels during standard operation of the separation column(s) (T1/T2) and the heat exchangers (E1, E2).

Abstract: The invention relates to a method for resolving a hydrocarbon-rich, nitrogen-containing feed fraction (1, 1?), preferably natural gas, is described, wherein the feed fraction (1, 1?) is separated by rectification (T1, T2) into a nitrogen-enriched fraction (5) and a hydrocarbon-rich, nitrogen-depleted fraction (10), and wherein the separation by rectification proceeds in a rectification column consisting of a preseparation column (T1) and a main separation column (T2). A liquid fraction (6) is taken off from the main separation column (T2) above the feed-in site(s) of the fraction (7, 7?, 7?) that is taken off from the preseparation column (T1) and fed to the main separation column (T2), and the liquid fraction (6) is applied to the preseparation column (T1) as reflux.

Abstract: A process is described for removing a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is partially condensed and fractionated by rectification into a nitrogen-rich fraction and a methane-rich fraction. According to the invention during an interruption in the supply of the feed fraction, the separation column(s) (T1/T2) used for the fractionation by rectification and also the heat exchangers used for the partial condensation (E1) of the feed fraction and the cooling and warming of process streams occurring in the fractionation by rectification (E2) are kept by means of one or more differing cooling media (6-11) at temperature levels which correspond essentially to the temperature levels during standard operation of the separation column(s) (T1/T2) and the heat exchangers (E1, E2).

Abstract: A process for separating off a nitrogen-rich fraction from a feed fraction containing essentially nitrogen and hydrocarbons, wherein the feed fraction is separated by rectification a nitrogen-rich fraction and a methane-rich fraction, is described. According to the invention, during an interruption of the supply of the feed fraction, at least temporarily, the nitrogen-rich fraction (4?) and the methane-rich fraction (5?) are compressed and jointly supplied to the process as feed fraction, wherein the compression of the nitrogen-rich fraction (4?) and the methane-rich fraction (5?) can be performed separately and/or jointly.

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).