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US 5,916,260 AGranted
Liquefaction process
AssigneeBHP Petroleum Pty Ltd.
InventorChristopher A. T. Dubar
Life of this patent
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AssigneeBHP Petroleum Pty Ltd.
InventorChristopher A. T. Dubar
Estimating the term…
A natural gas liquefaction process comprises passing natural gas through a series of heat exchangers in countercurrent relationship with a gaseous refrigerant circulated through a work expansion cycle. The work expansion cycle comprises compressing the refrigerant, dividing and cooling the refrigerant to produce at least first and second cooled refrigerant streams, substantially isentropically expanding the first refrigerant stream to a coolest refrigerant temperature, substantially isentropically expanding the second refrigerant stream to an intermediate refrigerant temperature warmer than said coolest refrigerant temperature, and delivering the refrigerant in the first and second refrigerant streams to a respective heat exchanger for cooling the natural gas through corresponding temperature ranges. The refrigerant in the first stream is isentropically expanded to a pressure at least 10 times greater than the total pressure drop of the first refrigerant stream across said series of heat exchangers, said pressure being in the range of 1.2 to 2.5 MPa.
A natural gas liquefaction process comprising passing natural gas through a series of heat exchangers in countercurrent relationship with a gaseous refrigerant circulated through a work expansion cycle, said work expansion cycle comprising compressing the refrigerant, dividing and cooling the refrigerant to produce at least first and second cooled refrigerant streams, substantially isentropically expanding the first refrigerant stream to a coolest refrigerant temperature, substantially isentropically expanding the second refrigerant stream to an intermediate refrigerant temperature warmer than said coolest refrigerant temperature, and delivering the refrigerant in the first and second refrigerant streams to a respective heat exchanger for cooling the natural gas through corresponding temperature ranges, wherein the refrigerant of the first stream is isentropically expanded to a pressure at least 10 times greater than the total pressure drop of the refrigerant of the first refrigerant stream across said series of heat exchangers, said pressure being in the range 1.2 to 2.5 MPa.
A process according to any preceding claim, wherein the series of heat exchangers includes a final heat exchanger that receives refrigerant from the first refrigerant stream, the relative flowrates of the first and second refrigerant streams are such that the warming curve for the refrigerant comprises a plurality of segments of different gradient, the refrigerant is warmed in said final heat exchanger to a temperature below -80.degree. C., and the coolest refrigerant temperature and the flowrate of refrigerant in said first refrigerant stream are such that a part of the refrigerant warming curve relating to the final heat exchanger is at all times within 1 to 10.degree. C. of the corresponding part of the cooling curve for the natural gas.
Dependencies are inferred from the claim text.