Abstract: In the separation of a compressed multi-component hydrocarbon stream containing liquid and gas phases to produce a liquid product stream having a specified maximum vapor pressure and a gas product stream having a specified maximum cricondenbar, gas flaring can be reduced and other advantages obtained by the method of(i) separating the liquid and gas phases in one or more separation stages at progressively reduced pressures to produce said liquid product stream, and(ii) treating the recovered gas phase to obtain the gas product stream by partial condensation of the recovered gas phase and separation of the condensate so formed; wherein(iii) step (ii) includes the step of rectifying the recovered gas phase in a refluxing exchanger and separating the condensate so formed.

Abstract: 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.

Abstract: Helium contaminated with minor amounts of air, water vapor and carbon dioxide and from an envelope (10) is compressed in a compressor (12) and thereafter cooled in cooler (18) and fed via water separator (20) to a first of two substantially helium-permeable, oxygen/nitrogen-impermeable membranes (28,34), the permeate from which is substantially pure helium. The impermeate still containing helium is fed to the second membrane (34), the permeate from which is recycled to the first membrane while the impermeate is rejected with little loss of helium. The method is useful in purifying helium in an airship or balloon.