Abstract: A process is shown for separating a relatively hot feed gas containing methane, ethane and heavier hydrocarbon constituents into a volatile residue gas and a primarily liquid bottoms. The feed gas is cooled to partially condense the feed gas to form a liquid portion which is expanded and fed to a fractionating column. The expanded liquid portion flows down the column in countercurrent fashion to vapors flowing up the column to separate the relatively less volatile fraction as column bottoms. A side reboiler heats and vaporizes a portion of the liquids flowing down the fractionating column to provide stripping vapors which flow up the column. A portion of the relatively hot, methane rich feed gas entering the process is routed to the column at a selected location in order to raise the relative volatility of liquids near the bottom of the column, resulting in ethane rejection.

Abstract: A process for separating the components of a feed gas containing methane and heavier hydrocarbons is shown in which a recycle stream is used to satisfy the heat requirements of the process while at the same time providing a reflux to a demethanizer column to improve product recovery. The inlet gas stream is fed to a separator without first splitting the stream. A first vapor portion and a first liquid portion are produced by the separator with the first vapor portion being supplied, after expansion, to the demethanizer column at an intermediate feed position. The first liquid portion from the separator is expanded and supplied to the demethanizer column at a relatively lower feed position. Overhead vapor is removed from the column and compressed to a higher pressure. The resulting compressed recycle stream is cooled sufficiently to substantially condense it and is supplied as reflux to the demethanizer column at a top feed position.

Abstract: A process is shown for producing liquefied natural gas from a pressurized natural feed stream. The feed stream is introduced into heat exchange contact with a mechanical refrigeration cycle to cool the feed stream to a first cooling temperature. At least a portion of the feed stream is passed through a turboexpander cycle to provide auxiliary refrigeration for the mechanical refrigeration cycle to thereby cool the feed stream to a second, relatively lower cooling temperature.