Patent ID: 9637428
Date: 2017-05-02
CPC Classifications: C07C,F25J

Claim:
1. 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 and a relatively less volatile fraction containing a major portion of said C 2 components, C 3 components, and heavier hydrocarbon components or said C 3 components and heavier hydrocarbon components, in which process (a) said gas stream is treated in one or more heat exchange steps and at least one division step to produce at least a first stream that has been cooled under pressure to condense substantially all of it, and at least a second stream that has been cooled under pressure; (b) said substantially condensed first stream is expanded to a lower pressure whereby it is further cooled, and thereafter supplied at a top feed position on a distillation column that produces at least an overhead vapor stream and a bottom liquid stream; (c) said cooled second stream is expanded to said lower pressure, and thereafter supplied to said distillation column at a mid-column feed position; and (d) at least said expanded further cooled first stream and said expanded second stream are fractionated in said distillation column at said lower pressure whereby the components of said relatively less volatile fraction are recovered in said bottom liquid stream and said volatile residue gas fraction is discharged as said overhead vapor stream; the improvement wherein (1) said expanded further cooled first stream is heated in a heat and mass transfer means housed in a processing assembly and thereafter discharged as a vapor fraction and a liquid fraction; (2) said overhead vapor stream is combined with said vapor fraction to form a combined vapor stream; (3) said combined vapor stream is cooled in said heat and mass transfer means, thereby to supply at least a portion of the heating of step (1) while simultaneously condensing the less volatile components from said combined vapor stream, thereby forming a condensed stream and a residual vapor stream, and thereafter discharging said residual vapor stream from said processing assembly as said volatile residue gas fraction; (4) said condensed stream is combined with said liquid fraction to form a combined liquid stream; (5) said combined liquid stream is supplied to said top feed position of said distillation column; and (6) the quantity and temperature of said combined liquid stream to said distillation column are effective to maintain the overhead temperature of said distillation column at a temperature whereby the major portions of the components in said relatively less volatile fraction are recovered in said bottom liquid stream.