Method for producing liquefied natural gas from natural gas, and corresponding plant
AssigneeTechnip France
InventorsSylvain Vovard, Dominique Claude Jean Gadelle
Life of this patent
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Abstract
A method for producing an LNG from natural gas, comprising liquefaction of at least a first part of the natural gas in a first heat exchanger by heat exchange with a first mixed refrigerant fluid in a closed cycle, sub-cooling of liquefied natural gas in a second heat exchanger by heat exchange with a second refrigerant fluid of a second refrigeration cycle, expansion of the sub-cooled liquefied natural gas stream and admission into a flash gas separator, withdrawal of liquefied natural gas at the bottom of the separator, and withdrawal, at the head, of a gas flow, and supply of the second refrigeration cycle by at least a part of said gas flow.
Claims10
A method for producing liquefied natural gas from natural gas, comprising:
- cooling at least a first part of the natural gas in a first heat exchanger by heat exchange with a first refrigerant and obtaining a first stream of liquefied natural gas, the first refrigerant being a mixed refrigerant,
- circulating the first refrigerant fluid in a first closed refrigeration cycle,
- sub-cooling the first stream of liquefied natural gas in a second heat exchanger by heat exchange with a second refrigerant distinct from the first refrigerant, and obtaining a second stream of sub-cooled liquefied natural gas,
- expanding the second stream of sub-cooled liquefied natural gas for forming a third stream of liquefied natural gas, and conveying the third stream of liquefied natural gas to a flash gas separator,
- withdrawing, at the bottom of the flash gas separator, the liquefied natural gas produced,
- circulating the second refrigerant fluid in a second refrigeration cycle, said circulating comprising at least:
- cooling the second refrigerant fluid at least in the first heat exchanger by heat exchange with the first refrigerant fluid for obtaining a stream of cooled second refrigerant fluid;
- expanding at least a part of the stream of cooled second refrigerant;
- obtaining a stream of cooled and expanded second refrigerant;
- and receiving the stream of cooled and expanded second refrigerant fluid into the second heat exchanger for cooling the first stream of liquefied natural gas, and
- withdrawing, at the head of the flash gas separator, a gas flow, and feeding the second refrigeration cycle with at least a part of said gas flow.
A plant for producing liquefied natural gas from natural gas, comprising:
- a first heat exchanger suitable for cooling at least a first part of the natural gas by heat exchange with a first refrigerant and for obtaining a first stream of liquefied natural gas, the first refrigerant being a mixed refrigerant,
- a first closed refrigeration cycle suitable for circulating the first refrigerant fluid,
- a second heat exchanger suitable for sub-cooling the first stream of liquefied natural gas by heat exchange with a second refrigerant distinct from the first refrigerant, and for obtaining a second stream of sub-cooled liquefied natural gas,
- an expansion component suitable for expanding the second stream of sub-cooled liquefied natural gas and for forming a third stream of liquefied natural gas,
- a flash gas separator suitable for receiving the third stream of liquefied natural gas,
- a withdrawal system, at the bottom of the flash gas separator, suitable for withdrawing the liquefied natural gas produced,
- a second refrigeration cycle suitable for circulating the second refrigerant fluid, and for:
- cooling the second refrigerant fluid at least in the first heat exchanger by heat exchange with the first refrigerant fluid and obtaining a stream of cooled second refrigerant fluid;
- expanding at least a portion of the stream of cooled second refrigerant;
- obtaining a stream of cooled and expanded second refrigerant;
- and taking the stream of cooled and expanded second refrigerant into the second heat exchanger for cooling the first stream of liquefied natural gas;
- and
- a withdrawal system, at the head of the flash gas separator, suitable for withdrawing a gas flow, and for feeding the second refrigeration cycle with at least a part of said gas flow.
Dependencies are inferred from the claim text.