Process for recovering alkenes from cracked hydrocarbon streams
AssigneeThe BOC Group, Inc.
InventorsRamakrishnan Ramachandran, Loc H. Dao
Life of this patent
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Abstract
A hydrocarbon stream is cracked to produce a hot gaseous stream which is compressed and cooled to condense almost all of the hydrocarbons contained in the stream. A noncondensed stream remaining after the condensation step, comprised predominantly of hydrogen and C.sub.1 to C.sub.3 hydrocarbons, is subjected to pressure swing adsorption or temperature swing adsorption at an adsorption temperature of about 0.degree. to about 250.degree. C. in a bed of adsorbent which selectively adsorbs ethylene and propylene, thereby adsorbing substantially all of the ethylene and propylene from the gas stream. The ethylene and/or propylene is recovered upon bed regeneration.
Claims24
A process for the recovery of alkene selected from ethylene, propylene and mixtures of these from a cracked hydrocarbon stream comprising the steps:
- (a) separating a gaseous stream from the cracked hydrocarbon stream;
- (b) cooling the gaseous stream, thereby producing a condensed hydrocarbon stream and a gas stream comprised predominantly of hydrogen and methane and containing small amounts of alkene and alkane selected from ethane, propane and mixtures of these;
- (c) subjecting said gas stream to adsorption at a temperature above about 50.degree. C. in an adsorption vessel containing an adsorbent which selectively adsorbs alkenes, selected from the group consisting of 4A-zeolite, 5A zeolite, 13X-zeolite and mixtures of these, thereby producing a nonadsorbed hydrogen- and alkane-enriched component and an adsorbed alkene-enriched component;
- and
- (d) desorbing said alkene-enriched component from said adsorbent by reducing the pressure in said adsorption vessel, by raising the temperature in said adsorption vessel or by reducing the pressure and raising the temperature in said adsorption vessel.
Dependencies are inferred from the claim text.