Deep flash LNG cycle
AssigneeAir Products and Chemicals, Inc.
InventorsCharles L. Newton, Wayne G. Stuber, Michael A. Patterson
Life of this patent
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Abstract
A system for liquefying and subcooling natural gas wherein compression power is shifted off the closed cycle refrigerant by subcooling the liquid natural gas to a relatively warm exit temperature and subsequently reducing the pressure and flashing the liquefied natural gas to recover a gaseous phase natural gas in excess of plant fuel requirements, the excess being recompressed and recycled to the feed to the process.
Claims13
In a process for the production of liquefied natural gas wherein a feed natural gas is liquefied and subcooled by heat exchange against at least one closed cycle refrigerant, the improvement comprising overcoming the problems of mismatched compressor drivers, inefficient liquefaction operation or high equipment capital costs by subcooling the liquefied natural gas to a relatively warm temperature, reducing the pressure of the subcooled liquefied natural gas and flashing the same in a phase separation in at least one stage wherein a gaseous phase natural gas stream is recovered in excess of that necessary for plant fuel and the excess gaseous phase natural gas is recompressed and recycled to the feed natural gas upstream of the liquefaction and subcooling in order to shift compression power requirements from the closed cycle refrigerant to the compression requirements of the gaseous phase natural gas recycle stream.
In a system for the production of liquefied natural gas wherein a feed natural gas stream is liquefied and subcooled against at least one closed cycle refrigerant in a multiple bundle heat exchanger, the improvement comprising means for overcoming the problems of mismatched compressor drivers, inefficient liquefaction operation or high equipment capital costs including:
- (a) means for reducing the pressure of the liquefied and subcooled natural gas including at least one phase separation vessel for removing a gaseous phase natural gas recycle stream;
- (b) compression means for recompressing the gaseous phase natural gas from said separation vessel;
- (c) means for removing a portion of the recompressed natural gas as plant fuel;
- and
- (d) means for introducing the remaining recompressed natural gas into the feed natural gas stream.
Dependencies are inferred from the claim text.