Process for liquefaction of natural gas
First Claim
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1. A process for liquefying a gas stream rich in methane which comprises the steps of:
- (a) providing the gas stream at a pressure above about 3103 kPa (450 psia);
(b) expanding the gas stream to a lower pressure to produce a gas phase and a liquid product having a temperature above about -112°
C. (-170°
F.) and a pressure sufficient for the liquid product to be at or below its bubble point;
(c) phase separating the gas phase and the liquid product; and
(d) introducing the liquid product to a storage means for storage at a temperature above about -112°
C. (-170°
F.).
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Abstract
This invention relates to a process for liquefying a gas stream rich in methane and having a pressure above about 3103 kPa (450 psia). The gas stream is expanded to a lower pressure to produce a gas phase and a liquid product having a temperature above about -112° C. (-170° F.) and a pressure sufficient for the liquid product to be at or below its bubble point. The gas phase and the liquid product are then phase separated in a suitable separator, and the liquid product is introduced to a storage means for storage at a temperature above about -112° C. (-170° F.).
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Citations
29 Claims
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1. A process for liquefying a gas stream rich in methane which comprises the steps of:
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(a) providing the gas stream at a pressure above about 3103 kPa (450 psia); (b) expanding the gas stream to a lower pressure to produce a gas phase and a liquid product having a temperature above about -112°
C. (-170°
F.) and a pressure sufficient for the liquid product to be at or below its bubble point;(c) phase separating the gas phase and the liquid product; and (d) introducing the liquid product to a storage means for storage at a temperature above about -112°
C. (-170°
F.). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A process for liquefing a gas stream rich in methane and having a pressure above about 3103 kPa (450 psia) which comprises the steps of
(a) phase separating the gas stream into a first gas stream and a first liquid stream; -
(b) passing the first liquid stream to a demethanizer column; (c) compressing and cooling the first gas stream, thereby producing gas and liquid phases; (d) phase separating the gas and liquid phases of step (c) to produce a second gas stream and a second liquid stream; (e) expanding at least a portion of the second gas stream to a lower pressure whereby the second gas stream is further cooled; (f) supplying the second liquid stream and the expanded second gas stream to the demethanizer column; (g) removing from the upper region of the demethanizer column a third gas stream, the third gas stream comprising predominantly methane, and passing the third gas stream through a heat exchanger to warm the third gas stream; (h) removing from the demethanizer a third liquid stream and passing the third liquid stream to a fractionation system having at least one fractionation column and having at least one overhead vapor stream; (i) combining the warmed third gas stream of step (g) and the overhead vapor stream of step (h) and compressing the combined stream; (j) cooling the compressed combined stream; (k) dividing the cooled compressed stream of step (j) into a first cooled stream and a second cooled stream and passing the first cooled stream through the heat exchanger of step (g) to further cool the first cooled stream; (l) expanding the first cooled stream to produce gas and liquid phases; (m) phase separating the gas and liquid phases of step (l) in a phase separator, thereby producing a methane-rich liquefied natural gas at a temperature above about -112°
C. (-170°
F.) and a pressure sufficient for the methane-rich liquefied natural gas to be at or below its bubble point;(n) expanding the second cooled stream of step (k) to a lower pressure whereby it is further cooled, producing gas and liquid phases; (o) phase separating the gas and liquid phases produced in step (n); and (p) passing the liquid phase of step (o) to the phase separator of step (m). - View Dependent Claims (14, 15, 16, 17, 18)
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19. A process for liquefying a gas stream rich in methane which comprises the steps of:
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(a) compressing the gas stream to a pressure greater than 3103 kPa (450 psia); (b) phase separating the gas stream into a first gas stream and a first liquid stream; (c) passing the first liquid stream to a demethanizer column; (d) compressing and cooling the first gas stream without use of a closed-loop refrigeration system, thereby producing gas and liquid phases; (e) phase separating the gas and liquid phases of step (d) to produce a second gas stream and a second liquid stream; (f) expanding at least a portion of the second gas stream to a lower pressure whereby it is further cooled; (g) supplying the second liquid stream and the expanded second gas stream to the demethanizer column; (h) removing from the upper region of the demethanizer column a vapor stream, the vapor stream comprising predominantly methane, and passing the vapor stream through a heat exchanger to warm the vapor stream; (i) removing from the demethanizer a liquid stream and passing the liquid stream to a fractionation system having at least one fractionation column and having at least one overhead vapor stream; (j) combining the warmed vapor stream of step (h) and the overhead vapor stream of step (i) and compressing the combined stream; (k) cooling the compressed combined stream of step (j) without use of a closed-loop refrigeration system; (l) dividing the cooled compressed stream of step (k) into a first cooled stream and a second cooled stream and passing the first cooled stream through the heat exchanger of step (h) to further cool the first cooled stream; (m) expanding the first cooled stream to produce gas and liquid phases; (n) phase separating the gas and liquid phases of step (m) in a phase separator, thereby producing a methane-rich liquefied natural gas having a temperature above about -112°
C. (-170°
F.) and a pressure sufficient for the methane-rich liquefied natural gas to be at or below its bubble point;(o) expanding the second cooled stream of step (l) to a lower pressure whereby it is further cooled, producing gas and liquid phases; (p) phase separating the gas and liquid phases produced in step (o); and (q) passing the liquid phase of step (o) to the phase separator of step (n). - View Dependent Claims (20, 21, 22, 23)
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24. A process for liquefying a gas stream rich in methane and having a pressure above about 3103 kPa (450 psia) which comprises the steps of:
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(a) cooling the gas stream; (b) passing the cooled gas stream through a heat exchanger to warm the gas stream; (c) compressing the warmed gas stream and after-cooling the compressed gas stream; (d) dividing the cooled compressed stream of step (c) into a first cooled stream and a second cooled stream and passing the first cooled stream through the heat exchanger of step (b) to further cool the first cooled stream; (e) expanding the first cooled stream to produce gas and liquid phases; (f) phase separating the gas and liquid phases of step (e) in a phase separator, thereby producing a gas phase and a methane-rich liquefied gas at a temperature above about -112°
C. (-170°
F.) and a pressure sufficient for the methane-rich liquefied gas to be at or below its bubble point;(g) expanding the second cooled stream of step (d) to a lower pressure whereby it is further cooled, producing gas and liquid phases; (h) phase separating the gas and liquid phases of step (g); and (i) passing the liquid phase of step (h) to the phase separator of step (f). - View Dependent Claims (25, 26, 27, 28, 29)
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Specification