Steam cracker gas separation process
AssigneeMembrane Technology and Research, Inc.
InventorRichard W. Baker
Life of this patent
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Abstract
The invention is a process for treating a gas stream from ethylene or propylene production, or any other stream containing low molecular weight olefin gases and other hydrocarbons, to separate hydrogen and methane from the C.sub.2+ hydrocarbons. The invention involves three separation steps: condensation, flash evaporation and membrane separation. The steps are integrated together in such a way as to provide a good separation between the components, and to avoid creation of secondary streams that need additional treatment.
Claims16
A process for treating a gas stream comprising hydrogen, methane, an olefin and at least one other C.sub.2+ hydrocarbon, to separate said olefin and said C.sub.2+ hydrocarbon from hydrogen and methane, said process comprising the following steps:
- (a) compressing said gas stream to a pressure no greater than about 1,000 psig;
- (b) cooling said gas stream to a temperature no lower than about -100.degree. C.;
- said steps (a) and (b) resulting in partial condensation of said gas stream, thereby dividing said gas stream into a condensed portion enriched in said olefin and said C.sub.2+ hydrocarbon and an uncondensed portion enriched in hydrogen and methane;
- (c) flash evaporating said condensed portion to at least partially remove additional amounts of hydrogen and methane from said condensed portion as a gaseous flash stream, thereby creating a more-enriched olefin and C.sub.2+ hydrocarbon product stream;
- (d) membrane treating said uncondensed portion in a membrane separation unit, to further divide said uncondensed portion into a more-enriched hydrogen and methane stream and a mixed stream;
- (e) recirculating said gaseous flash stream to said compressing step;
- (f) recirculating said mixed stream to said compressing step.
Dependencies are inferred from the claim text.