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US 10,480,854 B2Granted
Liquefied natural gas production system and method with greenhouse gas removal
AssigneeExxonMobil Upstream Research Company
InventorsRichard A. Huntington, Parag A. Gupte, Fritz Pierre, Jr., Robert D. Denton
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Abstract
Described herein are systems and processes to produce liquefied natural gas (LNG) using liquefied nitrogen (LIN) as the refrigerant. Greenhouse gas contaminants are removed from the LIN using a greenhouse gas removal unit.
Claims23
A liquefied natural gas production system using liquid nitrogen as a primary refrigerant, the system comprising:
- a natural gas stream from a supply of natural gas;
- a liquefied nitrogen stream from a supply of liquefied nitrogen;
- at least one heat exchanger that exchanges heat between the liquefied nitrogen stream and the natural gas stream to at least partially vaporize the liquefied nitrogen stream and at least partially condense the natural gas stream;
- and
- a greenhouse gas removal unit comprising a distillation column having a heat pump condenser and reboiler system, the greenhouse gas removal unit configured to remove greenhouse gas from the at least partially vaporized nitrogen stream, wherein the heat pump condenser and reboiler system further comprises
- a compressor that increases a pressure and condensing temperature of an overhead stream of the distillation column,
- a heat pump heat exchanger to cross-exchange the overhead stream of the distillation column and a bottom stream of the distillation column to affect both an overhead condenser duty and a bottom reboiler duty of the distillation column,
- a pressure reduction device, connected to an output of the heat pump heat exchanger, and configured to reduce a pressure of the distillation column overhead stream after the distillation column overhead stream has passed through the heat pump heat exchanger, and
- a separator, connected to an output of the pressure reduction device, and configured to produce a first separator overhead stream, wherein the first separator overhead stream is gaseous nitrogen that exits the greenhouse gas removal unit having greenhouse gases removed therefrom;
- at least one expander service that reduces the pressure of the at least partially vaporized nitrogen stream;
- and
- a controller that adjusts an inlet temperature of a first of the at least one expander service to affect an overhead condenser duty and a bottom reboiler duty of the distillation column.
9 more elements
A method of producing liquefied natural gas (LNG) using liquid nitrogen as a primary refrigerant, the method comprising:
- providing a natural gas stream from a supply of natural gas;
- providing a liquefied nitrogen stream from a supply of liquefied nitrogen;
- passing the natural gas stream and the liquefied nitrogen stream through a first heat exchanger that exchanges heat between the liquefied nitrogen stream and the natural gas stream to at least partially vaporize the liquefied nitrogen stream and at least partially condense the natural gas stream;
- and
- removing greenhouse gas from the at least partially vaporized nitrogen stream using a greenhouse gas removal unit, wherein the greenhouse gas removal unit comprises a distillation column and a heat pump condenser and reboiler system;
- increasing a pressure and condensing temperature of an overhead stream of the distillation column;
- cross-exchanging the overhead stream of the distillation column and a bottoms stream of the distillation column to affect both an overhead condenser duty and a bottom reboiler duty of the distillation column;
- reducing a pressure of the distillation column overhead stream after the cross-exchanging step to produce a reduced-pressure distillation column overhead stream;
- and
- separating the reduced-pressure distillation column overhead stream to produce a first separator overhead stream, wherein the first separator overhead stream is gaseous nitrogen that exits the greenhouse gas removal unit having greenhouse gases removed therefrom;
- providing a second heat exchanger in which the first separator overhead stream exchanges heat with the natural gas stream to increase a temperature of the first separator overhead stream to at least ambient temperature prior to the first separator overhead stream being vented to atmosphere;
- reducing a pressure of the at least partially vaporized nitrogen stream using at least one expander service;
- and
- controlling an inlet temperature of the at least one expander service to affect the overhead condenser duty and the bottom reboiler duty of the distillation column.
11 more elements
Dependencies are inferred from the claim text.