Ethylene Recovery by Absorption

A polyethylene production process, comprising:

• contacting ethylene and a polymerization catalyst in a polymerization reactor under suitable reaction conditions to yield a polymerization product stream;
• separating a light gas stream from the polymerization product stream, wherein the light gas stream comprises unreacted ethylene;
• contacting the light gas stream with an absorption solvent system in an absorption reactor at a temperature in a range of from about 40° F. to about 110° F., wherein at least a portion of the unreacted ethylene from the light gas stream is absorbed by the absorption solvent system to yield a composition comprising a complex of the absorption solvent system and unreacted ethylene;
• removing unabsorbed gases of the light gas stream from contact with the absorption solvent system;
• recovering unreacted ethylene from the absorption solvent system;
• and
• contacting the recovered ethylene and the polymerization catalyst.

A polyethylene production system, comprising:

• a feed stream comprising ethylene, wherein the feed stream is characterized by introduction into a polymerization reactor;
• a polymerization product stream, wherein the polymerization product stream is characterized by emission from the polymerization reactor and introduction into a separator;
• a light gas stream comprising unreacted ethylene, wherein the light gas stream is characterized by emission from the separator, the light gas stream having been separated from the polymerization product stream, wherein the light gas stream is characterized by introduction into an absorption solvent system, wherein the absorption solvent system has a temperature in a range of from about 40° F. to about 110° F.;
• an absorbent-ethylene conjugant, wherein the absorbent-ethylene conjugant is characterized by formation within the absorption solvent system by absorption of at least a portion of the unreacted ethylene by the absorption solvent system;
• and
• a waste gas stream comprising ethane, wherein the waste gas stream is characterized by emission from the absorption reactor, wherein the waste gas stream comprises components of the light gas stream that are not absorbed by the absorption solvent system;
• and
• a recovered unreacted ethylene stream, wherein the recovered unreacted ethylene stream is characterized by emission from the absorption reactor and reintroduction into the polymerization reactor.

A polyethylene production system, comprising:

• a polymerization reactor, wherein the polymerization reactor is configured to receive a feed stream comprising ethylene, and wherein the polymerization reactor is configured to emit a polymerization product stream;
• a separator, wherein the separator is configured to receive the polymerization product stream and to emit a light gas stream comprising unreacted ethylene, wherein the light gas stream has been separated from the polymerization product stream;
• and
• an absorption reactor comprising an absorption solvent system, wherein the absorption reactor is configured to receive the light gas stream, to absorb at least a portion of the unreacted ethylene with the absorption solvent system at a temperature in a range of from about 40° F. to about 110° F., and to emit a waste gas stream comprising components of the light gas stream that are not absorbed by the absorption solvent system, and wherein the absorption reactor is further configured to emit a recovered unreacted ethylene stream, and wherein the polymerization reactor is further configured to receive the recovered unreacted ethylene stream.

A polyethylene production system, comprising:

• a polymerization reactor, wherein the polymerization reactor is configured to receive a feed stream comprising ethylene, and wherein the polymerization reactor is configured to emit a polymerization product stream;
• a separator, wherein the separator is configured to receive the polymerization product stream and to emit a light gas stream comprising unreacted ethylene, wherein the light gas stream has been separated from the polymerization product stream;
• an absorption reactor comprising an absorption solvent system, wherein the absorption reactor is configured to receive the light gas stream, to absorb at least a portion of the unreacted ethylene with the absorption solvent system at a temperature in a range of from about 40° F. to about 110° F. and to emit a waste gas stream comprising components of the light gas stream that are not absorbed by the absorption solvent system, wherein the absorption reactor is further configured to emit a complexed stream comprising ethylene absorbed in the absorbent solvent system;
• and
• a solvent regenerator to regenerate the absorption solvent system, and to emit a recovered unreacted ethylene stream, wherein the polymerization reactor is further configured to receive the recovered unreacted ethylene stream.