Chemical absorption process for recovering olefins from cracked gases
AssigneeStone & Webster Engineering Corp.
InventorsRichard Barchas, Richard McCue, Jr., Christopher Wallsgrove, Mark Whitney
Life of this patent
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Abstract
The present invention provides an improved method for recovering high purity olefins from cracked gas effluents or other parafin/olefin gaseous mixtures by use of a chemical absorption process.
Claims19
A process for the recovery of olefins from a cracked gas stream comprising ethylene, propylene, hydrogen, methane, ethane, acetylenes, dienes and heavier hydrocarbons, said process comprising the steps of:
- (a) partially demethanizing said cracked gas stream to remove substantially all of said hydrogen from said cracked gas stream to produce a gaseous stream comprising hydrogen and from 15 to 90% of the methane contained in said cracked gas stream and a partially demethanized stream comprising the residual methane and heavier components;
- (b) contacting said partially demethanized gas stream comprising said residual methane and heavier components with a solution of a metallic salt capable of selectively chemically absorbing the ethylene and propylene to produce a scrubbed paraffin-rich gaseous stream and a chemically absorbed olefin-rich liquid stream;
- and
- (c) recovering said olefins from said metallic chemical absorbent solution.
A process for debottlenecking and/or retrofitting an existing conventional olefins recovery process comprising removing at least a portion of a dried, essentially acid gas free and compressed cracked gas stream comprising ethylene, propylene, methane, ethane, acetylenes, dienes and heavier hydrocarbons, and processing said removed gas stream in a debottlenecking and/or retrofitting olefin recovery process comprising the steps of:
- (i) depropanizing said removed gas stream to at least substantially remove all of the C.sub.4 and heavier hydrocarbons from said removed gas stream to produce a depropanized removed gas stream;
- (ii) selectively hydrogenating substantially all of the acetylene, methyl acetylene and propadiene in the removed depropanized gas stream to produce a hydrogenated removed gas stream;
- (iii) partially demethanizing said hydrogenated removed gas stream to remove substantially all of said hydrogen from said cracked gas stream to produce a gaseous stream comprising hydrogen and from 15 to 90% of the methane contained in said hydrogenated removed gas stream and a partially demethanized stream comprising the residual methane and heavier components;
- (iv) contacting said partially demethanized stream with a solution of a metallic salt capable of selectively chemically absorbing the ethylene and propylene to produce a scrubbed paraffin-rich gaseous stream and a chemically absorbed olefin-rich liquid stream;
- and
- (v) recovering said olefins from said metallic chemical absorbent solution.
Dependencies are inferred from the claim text.