Natural gas liquefaction processes with feed gas refrigerant cooling loops
First Claim
1. A process for liquefying a gas stream, said process comprising:
- (a) providing said gas stream at a pressure of from 600 to 1,000 psia (4,137-6,895 kPa) as a feed gas stream;
(b) providing a refrigerant at a pressure of less than 1,000 psia (6,895 kPa) by withdrawing a portion of said gas stream for use as said refrigerant;
(c) compressing said refrigerant in a closed loop to a pressure greater than or equal to 1,600 to less than or equal to 5,000 psia (11,032 to 34,474 kPa) to produce a compressed refrigerant;
(d) cooling said compressed refrigerant by indirect heat exchange with a cooling fluid;
(e) expanding the compressed refrigerant of (d) to cool said compressed refrigerant, to produce an expanded, cooled refrigerant at a pressure of from greater than or equal to 100 psia (689 kPa) to less than or equal to 1,000 psia (6895 kPa);
(f) passing said expanded, cooled refrigerant to a first heat exchange area;
(g) compressing the feed gas stream of (a) to a pressure of from greater than or equal to 2,500 psia (17,237 kPa) to less than or equal to 3,500 psia (24,132 kPa) to produce a compressed feed gas stream;
(h) cooling said compressed feed gas stream by indirect heat exchange with an air or water refrigerant cooler;
(i) passing said compressed feed gas stream through the first heat exchange area to cool at least a part thereof by indirect heat exchange, to produce a compressed, further cooled feed gas stream, wherein the feed gas is used as the only refrigerant such that no external refrigerants are used, except for water or air;
(j) passing the compressed, further cooled feed gas stream of (i) through a second heat exchange area for extra cooling; and
(k) expanding said compressed, further cooled feed gas stream of (j) to reduce the pressure of said compressed, further cooled feed gas stream to a pressure of from greater than or equal to 50 psia (345 kPa) to less than or equal to 450 psia (3103 kPa) to produce an expanded, cooled gas stream; and
(l) withdrawing a portion not to exceed 50% of said expanded, cooled gas stream of (k) and reducing its pressure in a reduction valve to a range of about 30-200 psia (207-1379 kPa) to produce a reduced pressure gas stream and passing the reduced pressure gas stream through the second heat exchange area of (j) as a cooling gas stream.
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Accused Products
Abstract
The described invention relates to processes and systems for treating a gas stream, particularly one rich in methane for forming liquefied natural gas (LNG), the process including: (a) providing a gas stream; (b) providing a refrigerant; (c) compressing the refrigerant to provide a compressed refrigerant; (d) cooling the compressed refrigerant by indirect heat exchange with a cooling fluid; (e) expanding the refrigerant of (d) to cool the refrigerant, thereby producing an expanded, cooled refrigerant; (f) passing the expanded, cooled refrigerant to a first heat exchange area; (g) compressing the gas stream of (a) to a pressure of from greater than or equal to 1,000 psia to less than or equal to 4,500 psia; (h) cooling the compressed gas stream by indirect heat exchange with an external cooling fluid; and heat exchanging the compressed gas stream with the expanded, cooled refrigerant stream.
64 Citations
8 Claims
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1. A process for liquefying a gas stream, said process comprising:
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(a) providing said gas stream at a pressure of from 600 to 1,000 psia (4,137-6,895 kPa) as a feed gas stream; (b) providing a refrigerant at a pressure of less than 1,000 psia (6,895 kPa) by withdrawing a portion of said gas stream for use as said refrigerant; (c) compressing said refrigerant in a closed loop to a pressure greater than or equal to 1,600 to less than or equal to 5,000 psia (11,032 to 34,474 kPa) to produce a compressed refrigerant; (d) cooling said compressed refrigerant by indirect heat exchange with a cooling fluid; (e) expanding the compressed refrigerant of (d) to cool said compressed refrigerant, to produce an expanded, cooled refrigerant at a pressure of from greater than or equal to 100 psia (689 kPa) to less than or equal to 1,000 psia (6895 kPa); (f) passing said expanded, cooled refrigerant to a first heat exchange area; (g) compressing the feed gas stream of (a) to a pressure of from greater than or equal to 2,500 psia (17,237 kPa) to less than or equal to 3,500 psia (24,132 kPa) to produce a compressed feed gas stream; (h) cooling said compressed feed gas stream by indirect heat exchange with an air or water refrigerant cooler; (i) passing said compressed feed gas stream through the first heat exchange area to cool at least a part thereof by indirect heat exchange, to produce a compressed, further cooled feed gas stream, wherein the feed gas is used as the only refrigerant such that no external refrigerants are used, except for water or air; (j) passing the compressed, further cooled feed gas stream of (i) through a second heat exchange area for extra cooling; and (k) expanding said compressed, further cooled feed gas stream of (j) to reduce the pressure of said compressed, further cooled feed gas stream to a pressure of from greater than or equal to 50 psia (345 kPa) to less than or equal to 450 psia (3103 kPa) to produce an expanded, cooled gas stream; and (l) withdrawing a portion not to exceed 50% of said expanded, cooled gas stream of (k) and reducing its pressure in a reduction valve to a range of about 30-200 psia (207-1379 kPa) to produce a reduced pressure gas stream and passing the reduced pressure gas stream through the second heat exchange area of (j) as a cooling gas stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification