Method and apparatus for liquefaction of natural gas
First Claim
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1. An apparatus comprising:
- pretreater means;
means for introducing a lean natural gas stream at a pressure above about 800 psig and at about ambient temperature to said pretreater means;
closed cycle refrigeration means for cryogenically liquefying said natural gas stream by indirect heat exchange with at least one refrigerant; and
an expander operatively connected between said pretreater means and said refrigeration means for reducing the pressure of said natural gas stream and extracting useful work from said natural gas stream during the pressure reduction wherein said expander is in fluid flow communication with said pretreater and said refrigeration means such that said expander receives said natural gas stream from said pretreater and after pressure reduction, introduces said natural gas stream to said refrigeration means.
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Abstract
A process and apparatus for liquefying a natural gas, having a pressure above about 800 psig, in which the natural gas is introduced into an expander which operates to reduce the pressure of the natural gas and extract work from the expansion of the natural gas during the pressure reduction so that the resulting effluent from the expander can be cooled to sequentially lower temperatures by passing the gas through a plurality of cooling stages, in indirect heat exchange with at least one refrigerant, until the gas is substantially completely condensed in the last of the cooling stages.
62 Citations
12 Claims
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1. An apparatus comprising:
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pretreater means; means for introducing a lean natural gas stream at a pressure above about 800 psig and at about ambient temperature to said pretreater means; closed cycle refrigeration means for cryogenically liquefying said natural gas stream by indirect heat exchange with at least one refrigerant; and an expander operatively connected between said pretreater means and said refrigeration means for reducing the pressure of said natural gas stream and extracting useful work from said natural gas stream during the pressure reduction wherein said expander is in fluid flow communication with said pretreater and said refrigeration means such that said expander receives said natural gas stream from said pretreater and after pressure reduction, introduces said natural gas stream to said refrigeration means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. In a process for producing liquefied natural gas, a method of improving liquid natural gas production and conserving energy, comprising:
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feeding a pressurized natural gas feed stream, at a pressure above about 800 psig and at about ambient temperature, to an expander means, prior to refrigeration of said feed stream; conducting said feed stream through said expander to reduce the pressure of the stream to a pressure below about 650 psig and to cool the stream to a temperature below about 0°
F.;extracting work from the feed stream during the reduction of pressure by means of said expander; and feeding said feed stream from an outlet of said expander to a refrigeration cycle of said process to produce a liquefied natural gas stream at about atmospheric pressure and at a temperature below about -258°
F. - View Dependent Claims (9, 10, 11, 12)
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Specification