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L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des

Air Liquide America, L.p.

Gerard Dupuis

Bao V Ha

Paul Kong

Yves Engler

A process for recovering olefins from a gas stream containing olefins and hydrogen. The process comprises compressing the gas stream in at least one compression stage to form a compressed gas stream, contacting the compressed gas stream with a membrane at conditions effective to obtain a permeate stream rich in hydrogen and a retentate stream depleted in hydrogen, and introducing the permeate stream into a pressure swing adsorption system at conditions effective to obtain a nonadsorbed stream rich in hydrogen and a desorbed stream comprising olefins.

Process for recovering olefins

A process for recovering olefins from a cracking effluent containing olefins and hydrogen. The process comprises compressing the cracking effluent in at least one compression stage to form a compressed cracking effluent, contacting the compressed cracking effluent with a membrane at conditions effective to obtain a permeate stream rich in hydrogen and a retentate stream depleted in hydrogen, and introducing the permeate stream into a pressure swing adsorption system at conditions effective to obtain a nonadsorbed stream rich in hydrogen and a desorbed stream comprising olefins.

Process for recovering olefins from cracked gases

C.sub.4 hydrocarbons are separated from a gaseous mixture containing the same and lower hydrocarbons and hydrogen, by cooling such a gaseous mixture (45) to a temperature between -60.degree. F. and +32.degree. F. until a portion of the C.sub.4 hydrocarbons is condensed. The mixture of gas and liquid C.sub.4 hydrocarbons thus produced is phase separated in a first phase separation (53), and the liquid from this first phase separation is withdrawn as C.sub.4 hydrocarbons product (69). Gas from the first phase separation (53) is further cooled (47) until substantially all of the remaining C.sub.4 hydrocarbons are condensed but not the hydrogen. The latter material is subjected to a second phase separation (75), and liquid from the second phase separation (77) is withdrawn as liquid C.sub.4 hydrocarbons product (69). Vapor from the second phase separation (75) is withdrawn and expanded isentropically in a first expansion engine (81) to produce a mixture of liquid and vapor, which is subjected to a third phase separation (85 ), and liquid from the third phase separation (85) is withdrawn as liquid C.sub.4 hydrocarbons product (69). A portion of vapor separated in the third phase separation (85) is expanded isentropically in a second expansion engine (137), and refrigeration from vapor from the second expansion engine (137) is recovered by indirect heat exchange (47) with the first-mentioned mixture (45). Gas separated in the third separation (85) is cooled to produce a mixture of gas and liquid, which is phase separated (103 or 123). Gas from the latter phase separation is expanded isentropically in the second expansion engine (137), and refrigeration from material from second expansion engine (137) is also recovered by indirect heat exchange (99) with gas separated in the third phase separation (85).

Method and apparatus for the separation of C.sub.4 hydrocarbons from

C.sub.4 hydrocarbons are separated from a gaseous mixture containing the same and lower hydrocarbons and hydrogen, by cooling such a gaseous mixture (45) to a temperature between -60.degree. F. and +32.degree. F. until a portion of the C.sub.4 hydrocarbons is condensed. The mixture of gas and liquid C.sub.4 hydrocarbons thus produced is phase separated in a first phase separation (53), and the liquid from this first phase separation is withdrawn as C.sub.4 hydrocarbons product (69). Gas from the first phase separation (53) is further cooled(47) until substantially all of the remaining C.sub.4 hydrocarbons are condensed but not the hydrogen. The latter material is subjected to a second phase separation (75), and liquid from the second phase separation (77) is withdrawn as liquid C.sub.4 hydrocarbons product (69). Vapor from the second phase separation (75) is withdrawn and expanded isentropically in a first expansion engine (81) to produce a mixture of liquid and vapor, which is subjected to a third phase separation (85), and liquid from the third phase separation (85) is withdrawn as liquid C.sub.4 hydrocarbons product (69). A portion of vapor separated in the third phase separation (85) is expanded isentropically in a second expansion engine (137), and refrigeration from vapor from the second expansion engine (137) is recovered by indirect heat exchange (47) with the first-mentioned mixture (45). Gas separated in the third separation (85) is cooled to produce a mixture of gas and liquid, which is phase separated (103 or 123). Gas from the latter phase separation is expanded isentropically in the second expansion engine (137), and refrigeration from material from second expansion engine (137) is also recovered by indirect heat exchange (99) with gas separated in the third phase separation (85).

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Walnut Creek, CA, United States of America

Gerard Dupuis