Abstract: The invention provides a process for the separation of a heavier hydrocarbon fraction from a gaseous feed comprising a mixture of hydrocarbons, which process comprises subjecting the feed to a first fractionation to form a condensed product; subjecting the condensed product to a second fractionation, at a lower pressure than the first fractionation pressure, to provide the heavier hydrocarbon fraction and distillate fraction; and withdrawing the produced heavier fraction wherein the distillate from the second fractionation is partially condensed to provide reflux streams for both the first and second fractionations. Running the second fractionation at a lower pressure than the first means that there is phased let-down of pressure in two stages, leading to an increased pressure at the suction of the residue gas compressor and reduces power consumption.

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: In the process for the recovery of e.g. LPG or NGL and sales gas from a gaseous hydrocarbon feed 11 by partially condensing the feed in heat exchanger 1 at superatmospheric pressure, separating the condensate from the uncondensed gas in gas/liquid separator 2, rectifying the uncondensed gas to produce the sales gas and stripping the condensate to produce the LPG or NGL, substantially power savings are obtained if the rectification is effected in a reflux exchanger 103 and the stripping is effected in a separate distillation column 203.

Abstract: In a process for the recovery of hydrogen from compressed purge gas withdrawn from a recyling gas stream of an ammonia synthesis wherein the hydrogen is separated from the purge gas by partial condensation at cryogenic temperatures, refrigeration is provided by expanding and evaporating the condensate so formed, and the partial pressure of the expanded condensate is lowered by withdrawing a bleed stream from said uncondensed gas, expanding said bleed stream and injecting it into said expanded condensate, condensation of nitrogen employed to purge the cold box for the cryogenic process is avoided by either injecting into the bleed stream a warmer gas provided from the uncondensed gas and/or the purge gas or expanding the condensate and bleed stream in stages with separate expansion thereof in an initial stage and injection of the bleed stream into the condensate prior to the final stage.

Abstract: A method of synthesizing ammonia by reacting a synthesis gas comprising nitrogen and hydrogen at superatmospheric pressure in a synthesis reaction zone with recycling of unreacting gas to the reacting zone is disclosed in which a purge gas stream is withdrawn at superatmospheric pressure and subjected to the steps of: (a) work expansion, (b) separation of methane and argon to form a gaseous product stream comprising nitrogen and hydrogen, (c) recompression of at least a portion of the gaseous product stream from step (b) using work generated in step (a), and (d) recycling of at least a portion of the recompressed product from step (c) to the reaction zone.Apparatus for effecting said process is also claimed.

Abstract: A process is disclosed for recovering hydrogen from an ammonia synthesis plant comprising(a) cooling a high pressure stream of said purge gas to a sub-ambient temperature at which substantially all of the methane and argon contained in said purge gas stream and a portion of the nitrogen condense,(b) expanding liquid and vapor components of the cooled high pressure stream to an intermediate pressure,(c) phase separating liquid and vapor components of the cooled and expanded purge gas stream,(d) expanding separated liquid component from step (c), and(e) heating expanded separated liquid component from step (d) and separated vapor component from step (c) in heat exchange with said high pressure stream of purge gas to cool the latter.