Separation of hydrocarbon mixtures

摘要

In the method of separating a methane-containing light gas from a feed gas containing heavier hydrocarbons by (i) cooling the feed gas at superatmospheric pressure to partially condense it, (ii) separating a first condensate from the uncondensed gas, (iii) rectifying the uncondensed gas to produce the light gas and a second condensate (preferably by further cooling the uncondensed gas in a refluxing heat exchanger), and (iv) stripping at least one of the condensates in a distillation column to obtain an overhead stream and a liquid product stream, the power requirement is reduced by providing at least part of the cooling for step (i) by expanding at least a part of the feed gas in a turbo-expander which provides energy for compression of product gas comprising said light gas and/or uncondensed gas from the overhead from the distillation column.