Ethylene Expansion for Low Temperature Refrigeration in Polyethylene Vent Recovery
AssigneeUnivation Technologies, LLC
InventorsRandall L. Force, Donald A. Fischer
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Abstract
Provided are processes and systems for recovering hydrocarbons in a vent stream from a polymerization process. The methods and systems may include the recovery of an olefin monomer from a polymerization vent gas using ethylene refrigeration to condense and recover the olefin monomers from the vent gas. In some embodiments, the methods and systems may also include compression and condensation of polymerization vent gas, recompression of ethylene refrigerant, and use of an expander compressor turbine device for ethylene refrigeration.
Claims13
A process for recovery of hydrocarbons from a polymerization vent gas, the process comprising:
- (a) reducing a pressure of an ethylene stream from a pressure of greater than or equal to 3.4 MPa to a pressure of less than or equal to about 1.4 MPa to form a reduced pressure ethylene stream;
- (b) cooling a vent gas comprising a monomer via heat exchange with the reduced pressure ethylene stream to form a first condensate comprising at least a portion of the monomer entrained in a first light gas;
- (c) recovering the first condensate and the first light gas;
- (d) separating the first condensate from the first light gas;
- (e) compressing the reduced pressure ethylene stream to a pressure of greater than or equal to 2.4 MPa;
- (f) passing the compressed ethylene stream to a polymerization reactor.
A system for recovery of hydrocarbons from a polymerization vent gas, the system comprising:
- an ethylene expander;
- a first vent gas recovery system in fluid communication with the ethylene expander comprising:
- a heat exchanger in fluid communication with a vent gas line and the ethylene expander and configured to provide heat exchange between an incoming vent gas and ethylene from the ethylene expander, whereby incoming ethylene from the ethylene expander is condensed into a first condensate comprising ethylene monomers in a first light gas;
- a separator in fluid communication with the heat exchanger having an inlet configured to receive the first condensate, and configured to separate the first condensate from the first light gas;
- and
- a compressor in fluid communication with the separator having an inlet configured to receive the first light gas from the separator.
Dependencies are inferred from the claim text.