Abb Lummus Crest, Inc.

Lummus Technology Inc.

Frank D McCarthy

Stephen J Stanley

Peter Robert Ponzi

David M Wadsworth

Paul Chapman

Robert John Gartside

Erwin M J Platvoet

A low pressure cryogenic process is disclosed for recovering C.sub.2 and heavier hydrocarbons and particularly olefins from a refinery offgas containing hydrogen, methane, nitrogen oxide in addition to the C.sub.2 and heavier hydrocarbons. The conventional high pressures are eliminated and the temperatures are maintained higher than the temperature at which nitrated gums can form while still maintaining high olefin recovery. The feed is deethanized or depropanized to remove the C.sub.4 and heavier hydrocarbons at a temperature above the nitrated gum formation temperature. The overhead is then demethanized in a column using an enriching zone above the rectifying zone with a feed of C.sub.2 or heavier paraffins between these two zones.

Low pressure recovery of olefins from refinery offgases

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Wayne, NJ, United States of America

Frank D McCarthy