Patent ID: 6915662

Claim:
In a process for the separation of a gas stream containing methane, C 2 components, C 3 components and heavier hydrocarbon components into a volatile residue gas fraction containing a major portion of said methane and a relatively less volatile fraction containing a major portion of said C 2 components, C 3 components and heavier hydrocarbon components, in which process (a) said gas stream is treated in one or more heat exchange steps to produce at least a first feed stream that has been cooled under pressure; (b) said cooled first feed stream is expanded to a lower pressure, and thereafter supplied to a fractionation tower at a top feed point; and (c) said cooled expanded first feed stream is fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered; the improvement wherein (1) a liquid distillation stream is withdrawn from said fractionation tower and heated; (2) said heated distillation stream is returned to a lower point on said fractionation tower that is separated from said withdrawal point by at least one theoretical stage; and (3) the quantities and temperatures of said feed streams to said fractionation tower are effective to maintain the overhead temperature of said fractionation tower at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered.