DUAL NITROGEN EXPANSION PROCESS
First Claim
1. A method of natural gas liquefaction comprising first and second nitrogen refrigerant streams, each stream undergoing a cycle of compression, cooling, expansion and heating, during which the first nitrogen stream is expanded to a first, intermediate pressure and the second nitrogen stream is expanded to a second, lower pressure, and the heating occurs in one or more heat exchangers in which at least one of the expanded nitrogen streams—
- is in heat exchanging relationship with natural gas, wherein, in at least one of said one or more heat exchangers, the first and second expanded nitrogen streams are in a heat exchanging relationship with the natural gas and both the first and second compressed nitrogen streams.
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Accused Products
Abstract
A method of natural gas liquefaction comprising first and second nitrogen refrigerant streams, each stream under-going a cycle of compression, cooling, expansion and heating, during which the first nitrogen stream is expanded to a first, intermediate pressure and the second nitrogen stream is expanded to a second, lower pressure, and the heating occurs in one or more heat exchangers in which at least one of the expanded nitrogen streams is in heat exchanging relationship with natural gas, wherein, in at least one of said one or more heat exchangers, the first and second expanded nitrogen streams are in a heat exchanging relationship with the natural gas and both the first and second compressed nitrogen streams. The liquefaction can occur in three stages: in an initial stage the heated, expanded first nitrogen stream and the heated, expanded second nitrogen stream are used to cool the natural gas; in an intermediate stage the compressed first nitrogen stream is expanded to an intermediate pressure and used to cool the natural gas; and in a final stage the compressed, second nitrogen stream is expanded to a low pressure and used to cool the natural gas.
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Citations
20 Claims
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1. A method of natural gas liquefaction comprising first and second nitrogen refrigerant streams, each stream undergoing a cycle of compression, cooling, expansion and heating, during which the first nitrogen stream is expanded to a first, intermediate pressure and the second nitrogen stream is expanded to a second, lower pressure, and the heating occurs in one or more heat exchangers in which at least one of the expanded nitrogen streams—
- is in heat exchanging relationship with natural gas, wherein, in at least one of said one or more heat exchangers, the first and second expanded nitrogen streams are in a heat exchanging relationship with the natural gas and both the first and second compressed nitrogen streams.
- View Dependent Claims (2, 3, 4, 10, 11, 12, 13, 15, 17)
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5. A natural gas liquefaction method in which natural gas is cooled by first and second nitrogen refrigerant streams, each stream undergoing a cycle of compression, cooling, expansion and heating, the method comprising three stages in which:
- in an initial stage the heated, expanded first nitrogen stream and the heated, expanded second nitrogen stream are used to cool the natural gas;
in an intermediate stage the compressed first nitrogen stream is expanded to an intermediate pressure and used to cool the natural gas; and
in a final stage the compressed, second nitrogen stream is expanded to a low pressure and used to cool the natural gas. - View Dependent Claims (6, 7, 8, 9, 18, 19, 20)
- in an initial stage the heated, expanded first nitrogen stream and the heated, expanded second nitrogen stream are used to cool the natural gas;
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14. A natural gas liquefaction apparatus comprising one or more heat exchangers for placing the natural gas in a heat exchanging relationship with first and second nitrogen refrigerant streams;
- one or more compressors for compressing the first and second nitrogen refrigerant streams;
a first expander for expanding the first nitrogen stream to a first pressure and a second expander for expanding the second nitrogen stream to a second, lower pressure;
wherein the apparatus is arranged such that, in at least one of said one or more heat exchangers, the first and second expanded nitrogen streams are in heat exchanging relationship with the natural gas and both the first and second compressed nitrogen streams. - View Dependent Claims (16)
- one or more compressors for compressing the first and second nitrogen refrigerant streams;
Specification