METHODS FOR SEPARATING HYDROCARBON GASES Russian patent published in 2018 - IPC C07C7/04 C07C9/04 C07C9/06 C07C9/08 C07C11/06 

FIELD: liquefaction or curing of gases.

SUBSTANCE: invention relates to a process for separating a hydrocarbon gas comprising at least ethane and C₃ and heavier components per fraction containing a predominant portion of ethane and lighter components, and a fraction containing a predominant portion of C₃ and heavier components, in which (a) feed gas is treated in one or more heat exchangers, and expansion steps to provide at least one partly condensed hydrocarbon gas, providing thereby at least one first residue vapour and at least one C₂ or C₃-containing liquid, which liquid also contains lighter hydrocarbons; and (b) at least one of the C₂ or C₃-containing liquids is directed into a distillation column wherein said liquid is separated into a second residue containing lighter hydrocarbons and a C₂ or C₃-containing product. Method is characterised in that, it comprises (1) cooling the second residue to partially condense it; (2) directly contacting at least part of one of said first residue vapours with at least part of the liquid portion of the partially condensed second residue in at least one contacting stage and thereafter separating the vapours and liquids from said contacting stage; (3) supplying the liquids thereby recovered to the distillation column as a liquid feed thereto; (4) directing the vapours thereby recovered into heat exchange relation with said second residue from the distillation column, thereby to supply the cooling of step (1), and thereafter discharging said residue gases. Method further comprises (5) recovering a recycle gas stream from an expander-compressor or residue gas compressor; (6) cooling and partially condensing the recycle stream in said one or more heat exchangers; (7) expanding the recycle stream thereby further condensing a portion of and cooling the recycle stream; (8) feeding the expanded recycle stream to a subcooler, whereby the expanded recycle stream is heat exchanged in the subcooler with gases from top of a light-ends fractionation column; thereby providing colder temperatures to the vapours from the heavy ends fractionation column.

EFFECT: use of the proposed method enables to extract C₃ in an improved manner.

12 cl, 2 dwg