Linde Aktiengesellschaft

Rainer Sapper

Heinz Bauer

Jurgen Witte

Martin Gwinner

Daniel Garthe

Georg Schopfer

Helmut Kick

Arndt Erik Schael

Hubert Franke

Described herein is a method for separating C-hydrocarbons or C-hydrocarbons from a hydrocarbon-rich fraction is described, whereby the separation is carried out in a rectification fractionation. The rectification fractionation is provided with at least three heating circuits via which intermediate fractions are drawn off from rectification fractionation, partially evaporated and fed back again to rectification fractionation. In the method, removal of the intermediate fraction circulating in the heating circuit located at the highest temperature level is at least temporarily interrupted. During this interruption, a partial stream of a bottom fraction from the rectification fractionation is partially evaporated against an external medium and is fed as a bottom heating to the rectification fractionation. Also during this interruption, the two additional intermediate fractions, in each case at the temperature level at which the intermediate fraction circulating in the heating circuit located at the next-higher temperature level was partially evaporated, are partially evaporated.

Method for separating C2+-hydrocarbons or C3+-hydrocarbons from a hydrocarbon-rich fraction

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) (T/T) used for the fractionation by rectification and also the heat exchangers used for the partial condensation (E) of the feed fraction and the cooling and warming of process streams occurring in the fractionation by rectification (E) are kept by means of one or more differing cooling media (-) at temperature levels which correspond essentially to the temperature levels during standard operation of the separation column(s) (T/T) and the heat exchangers (E, E).

Process for removing nitrogen

A process for the separation of C.sub.2+ hydrocarbons from natural gas under pressure wherein the natural gas is cooled (2, 6), partially condensed, and separated (9) into a liquid fraction and a gaseous fraction. The liquid fraction (10) is subcooled (11) and then expanded into the upper zone of a rectifying column (7). The gaseous fraction (23), after engine expansion (25), is also introduced into the rectifying column (7). During rectification, a product stream (37) containing essentially C.sub.2+ hydrocarbons and a residual gas stream (22) containing predominantly lower-boiling components are obtained. The residual gas stream (22) is initially heated by heat exchange (11) with the liquid fraction (10) and then heated by heat exchange (21) with the gaseous fraction obtained after partial condensation. The residual gas stream is then further heated (6, 2) by heat exchange with the feed stream of natural gas to be partially condensed. The heated residual gas is then engine expanded (28) and reheated again by heat exchange with the feed stream of natural gas to be partially condensed (2).

Process for the separation of C.sub.2+  hydrocarbons from natural gas

A process for the separation of CO.sub.2 from gases containing light hydrocarbons and a relatively high proportion of CO.sub.2 comprises a two stage fractionation procedure. In a first fractionating stage, the entire amount of C.sub.1 and C.sub.2 hydrocarbons are separated from the gaseous mixture; the resultant bottoms fraction, which contains the C.sub.3+ hydrocarbons and CO.sub.2, is pumped to a higher pressure and further distilled in a second fractionating stage. During this process, the head cooling of the second fractionating stage is coupled with the bottoms heating of the first fractionating stage.

Process for separating CO.sub.2 from a gaseous mixture

The separation of C.sub.3+ hydrocarbons from natural gas and the like comprises subjecting the gas under pressure to partial condensation under cooling, separating the uncondensed gaseous phase and engine expanding same while the condensed liquid fraction is subjected to rectification. Additional C.sub.3+ hydrocarbons are separated from the engine expanded gaseous fraction by scrubbing and then fed to the rectification column. The resultant scrubbed gaseous fraction, whose pressure preferably is above the rectification pressure, can be delivered as C.sub.2- product stream.

Separation of C.sub.3+  hydrocarbons by absorption and rectification

For the separation of CO.sub.2 from a gaseous mixture containing CO.sub.2 and C.sub.1 -C.sub.6 hydrocarbons, the gaseous mixture to be fractionated is separated in a first fractionating stage into an overhead fraction containing substantially all of the C.sub.1 and C.sub.2 hydrocarbons as well as CO.sub.2 in a molar ratio CO.sub.2 /C.sub.2 of 2:1 to 3.5:1, and into a bottoms fraction containing the remainder of CO.sub.2 and the C.sub.3+ hydrocarbons. The fraction containing CO.sub.2 /C.sub.3+ hydrocarbons is further fractionated, preferably in two serially connected rectification columns, into CO.sub.2 and C.sub.3+ hydrocarbon fractions.

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Neuried, Germany

Rainer Sapper