Natural Gas Liquefaction Process for Ling
First Claim
1. A process for liquefying a gas stream rich in methane, said process comprising:
- providing said gas stream at a pressure less than 1,000 psia;
providing a refrigerant at a pressure of less than 1,000 psia;
compressing said refrigerant to a pressure greater than or equal to 1500 psia to provide a compressed refrigerant;
cooling said compressed refrigerant by indirect heat exchange with a cooling fluid;
expanding said compressed refrigerant to further cool said compressed refrigerant, thereby producing an expanded, cooled refrigerant;
passing said expanded, cooled refrigerant to a heat exchange area; and
passing said gas stream through said heat exchange area to cool at least part of said gas stream by indirect heat exchange with said expanded, cooled refrigerant, thereby forming a cooled gas stream.
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Abstract
Embodiments of this invention relate to a process for liquefaction of natural gas and other methane-rich gas streams, and more particularly to a process for producing liquefied natural gas (LNG). In a first step of the process, a first fraction of the feed gas is withdrawn, compressed to a pressure greater than or equal to 1500 psia, cooled and expanded to a lower pressure to cool the withdrawn first fraction. The remaining fraction of the feed stream is cooled by indirect heat exchange with the expanded first fraction in a first heat exchange process. In a second step a separate stream comprising flash vapor is compressed, cooled and expanded to a lower pressure providing another cold stream. This cold stream is used to cool the remaining feed gas stream in a second indirect heat exchange process. The expanded stream exiting from the second heat exchange process is used for supplemental cooling in the first indirect heat exchange step. The remaining feed gas is subsequently expanded to a lower pressure, thereby partially liquefying this feed gas stream. The liquefied fraction of this stream is withdrawn from the process as LNG having a temperature corresponding to the bubble point pressure.
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Citations
22 Claims
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1. A process for liquefying a gas stream rich in methane, said process comprising:
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providing said gas stream at a pressure less than 1,000 psia; providing a refrigerant at a pressure of less than 1,000 psia; compressing said refrigerant to a pressure greater than or equal to 1500 psia to provide a compressed refrigerant; cooling said compressed refrigerant by indirect heat exchange with a cooling fluid; expanding said compressed refrigerant to further cool said compressed refrigerant, thereby producing an expanded, cooled refrigerant; passing said expanded, cooled refrigerant to a heat exchange area; and passing said gas stream through said heat exchange area to cool at least part of said gas stream by indirect heat exchange with said expanded, cooled refrigerant, thereby forming a cooled gas stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A process for liquefying a gas stream rich in methane, said process comprising:
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providing said gas stream at a pressure less than 1,000 psia; providing a refrigerant in a closed loop; compressing said refrigerant to a pressure greater than or equal to 1500 psia to provide a compressed refrigerant; cooling said compressed refrigerant by indirect heat exchange with a cooling fluid; expanding said compressed refrigerant to further cool said compressed refrigerant, thereby producing an expanded, cooled refrigerant; passing said expanded, cooled refrigerant to a heat exchange area; and passing said gas stream through said heat exchange area to cool at least part of said gas stream by indirect heat exchange with said expanded, cooled refrigerant.
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Specification