Separation of hydrocarbon mixtures

Claim 1

In a process for the separation of a light gas which contains methane and/or hydrogen, and which forms a major part (by volume) of the feed gas mixture, from a heavier stream containing C 3 hydrocarbon, optionally together with C 2 hydrocarbon and/or hydrocarbon containing 4 or more carbon atoms, which process comprises: (i) cooling the feed gas mixture at superatmospheric pressure to partially condense it, (ii) separating the condensate from the uncondensed gas, (iii) rectifying the uncondensed gas to produce said light gas, and (iv) stripping the condensate to produce said heaver portion, the improvement by which the light gas is obtained at a pressure close to that of the feed gas, comprising: effecting said rectification of said uncondensed gas in step (iii) by passing uncondensed gas upwards, at substantially the same pressure as that at which it is obtained from step (ii), while further cooling the uncondensed gas to partially condense it, whereby the liquid condensed out of said gas flows downwards in counter-current fashion in contact with the rising gas and forms a mixture with condensate formed by the partial condensation; prior to said stripping step (iv), warming said condensate by indirect heat exchange with the feed gas mixture; and effecting said step (iv) by stripping of said condensate in a stripping column to produce said heavier portion.