Integrated Nitrogen Removal in the Production of Liquefied Natural Gas Using Refrigerated Heat Pump
AssigneeAir Products and Chemicals, Inc.
InventorsChristopher Michael Ott, Gowri Krishnamurthy, Fei Chen, Yang Liu, Mark Julian Roberts
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Abstract
A method for liquefying a natural gas feed stream and removing nitrogen therefrom, the method comprising passing a natural gas feed stream through a main heat exchanger to produce a first LNG stream, and separating a liquefied or partially liquefied natural gas stream in a distillation column to form nitrogen-rich vapor product, wherein a closed loop refrigeration system provides refrigeration to the main heat exchanger and to a condenser heat exchanger that provides reflux to the distillation column.
Claims21
A method for liquefying a natural gas feed stream and removing nitrogen therefrom, the method comprising:
- (a) passing a natural gas feed stream through a main heat exchanger to cool the natural gas stream and liquefy all or a portion of said stream, thereby producing a first LNG stream;
- (b) withdrawing the first LNG stream from the main heat exchanger;
- (c) expanding and partially vaporizing a liquefied or partially liquefied natural gas stream, and introducing said stream into a distillation column in which the stream is separated into vapor and liquid phases, wherein the liquefied or partially liquefied natural gas stream is the first LNG stream, or is an at least partially liquefied nitrogen-enriched natural gas stream formed from separating a nitrogen-enriched natural gas stream from the first LNG stream or from the natural gas feed stream and at least partially liquefying said stream in the main heat exchanger;
- (d) forming a nitrogen-rich vapor product from overhead vapor withdrawn from the distillation column;
- (e) providing reflux to the distillation column by condensing a portion of the overhead vapor from the distillation column in a condenser heat exchanger;
- and
- (f) forming a second LNG stream from bottoms liquid withdrawn from the distillation column;
- wherein refrigeration for the main heat exchanger and for the condenser heat exchanger is provided by a closed loop refrigeration system, refrigerant circulated by the closed loop refrigeration system passing through and being warmed in the main heat exchanger and passing through and being warmed in the condenser heat exchanger.
An apparatus for liquefying a natural gas feed stream and removing nitrogen therefrom, the apparatus comprising:
- a main heat exchanger having a cooling passage for receiving a natural gas feed stream and passing the natural gas feed stream through the heat exchanger to cool the stream and liquefy all or a portion of the stream, so as to produce a first LNG stream;
- an expansion device and distillation column, in fluid flow communication with the main heat exchanger, for receiving, expanding and partially vaporizing a liquefied or partially liquefied natural gas stream and separating said stream in the distillation column into vapor and liquid phases, wherein the liquefied or partially liquefied natural gas stream is the first LNG stream, or is an at least partially liquefied nitrogen-enriched natural gas stream formed from separating a nitrogen-enriched natural gas stream from the first LNG stream or from the natural gas feed stream and at least partially liquefying said stream in the main heat exchanger;
- a condenser heat exchanger for providing reflux to the distillation column by condensing a portion of the overhead vapor obtained from the distillation column;
- and
- a closed loop refrigeration system for providing refrigeration to the main heat exchanger and condenser heat exchanger, refrigerant circulated by the closed loop refrigeration system passing through and being warmed in the main heat exchanger and passing through and being warmed in the condenser heat exchanger.
Dependencies are inferred from the claim text.