Patent ID: 8919148
Filing Date: 2014-12-30
Classification: F25J

Abstract:
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 cooled under pressure to provide a cooled stream; (b) said cooled stream is expanded to a lower pressure whereby it is further cooled; and (c) said further cooled stream is directed into a distillation column and fractionated at said lower pressure whereby the components of said relatively less volatile fraction are recovered; the improvement wherein following cooling, said cooled stream is divided into first and second streams; and (1) said first stream is cooled to condense substantially all of it and is thereafter expanded to said lower pressure whereby it is further cooled; (2) said expanded cooled first stream is thereafter supplied to said distillation column at a first mid-column feed position; (3) said second stream is expanded to said lower pressure and is supplied to said distillation column at a second mid-column feed position; (4) a vapor distillation stream is withdrawn from a region of said distillation column above said expanded second stream and is cooled sufficiently to condense at least a part of it, thereby forming a residual vapor stream and a condensed stream; (5) at least a portion of said condensed stream is supplied to said distillation column at a top feed position; (6) an overhead vapor stream is withdrawn from an upper region of said distillation column and is directed into heat exchange relation with said vapor distillation stream and heated, thereby to supply at least a portion of the cooling of step (4), and thereafter discharging at least a portion of said heated overhead vapor stream as said volatile residue gas fraction; and (7) the quantities and temperatures of said feed streams 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.