Method and apparatus for liquefying a hydrocarbon stream
First Claim
1. A method of liquefying a hydrocarbon stream comprising the steps of:
- (a) supplying a partly condensed feed stream having a pressure above 60 bar to a first gas/liquid separator;
(b) separating the feed stream in the first gas/liquid separator into a first gaseous stream, which first gaseous stream is removed from the first gas/liquid separator at a first outlet, and a first liquid stream;
(c) expanding the first liquid stream obtained in step (b) thereby forming an expanded first liquid stream, and feeding the expanded first liquid stream into a distillation column at a first feeding point;
(d) expanding all of the first gaseous stream removed at the first outlet of the first gas/liquid separator in step (b), thereby obtaining an expanded gaseous stream which is at least partially condensed, and subsequently feeding all of the expanded gaseous stream into the distillation column at a second feeding point, the second feeding point being at a higher level than the first feeding point;
(e) removing from the top of the distillation column a second gaseous stream, partially condensing the second gaseous stream thereby forming a partially condensed second gaseous stream, and feeding the partially condensed second gaseous stream into a second gas/liquid separator;
(f) separating the stream fed in the second gas/liquid separator in step (e) thereby obtaining a second liquid stream and a third gaseous stream;
(g) feeding the second liquid stream obtained in step (f) into the distillation column at a third feeding point, the third feeding point being at a higher level than the second feeding point; and
(h) liquefying the third gaseous stream obtained in step (f) thereby obtaining a liquefied stream;
wherein the second gaseous stream removed from the distillation column in step (e) is partially condensed by heat exchanging against all of the expanded gaseous stream before the expanded gaseous stream is fed into the distillation column at the second feeding point; and
wherein the third gaseous stream obtained in step (f) is heat exchanged against the feed stream of step (a) before the third gaseous stream is liquefied in step (h), thereby partially condensing the feed stream.
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Accused Products
Abstract
The present invention relates to a method of liquefying a hydrocarbon stream such as a natural gas stream, the method at least comprising the steps of: supplying a partly condensed feed stream (10) having a pressure above 60 bar to a first separator (2) wherein it is separated into a gaseous stream (20) and a liquid stream (30); expanding the liquid stream (30) and the gaseous stream (20) and subsequently feeding them into the distillation column (3); removing from the distillation column (3) a gaseous overhead stream (80), partially condensing it, feeding it (90) into a second separator (8) thereby obtaining a liquid stream (100) and a gaseous stream (110), feeding the liquid stream (100) into the distillation column (3) and liquefying the gaseous stream (110) thereby obtaining a liquefied stream (200); wherein the gaseous overhead stream (80) is partially condensed by heat exchanging against the expanded gaseous stream (60) before it (70) is fed into the distillation column (3); and wherein the gaseous stream (110) is removed from the second separator but before it (160) is liquefied, is heat exchanged against the feed stream (10a), thereby partially condensing the feed stream (10a).
12 Citations
22 Claims
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1. A method of liquefying a hydrocarbon stream comprising the steps of:
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(a) supplying a partly condensed feed stream having a pressure above 60 bar to a first gas/liquid separator; (b) separating the feed stream in the first gas/liquid separator into a first gaseous stream, which first gaseous stream is removed from the first gas/liquid separator at a first outlet, and a first liquid stream; (c) expanding the first liquid stream obtained in step (b) thereby forming an expanded first liquid stream, and feeding the expanded first liquid stream into a distillation column at a first feeding point; (d) expanding all of the first gaseous stream removed at the first outlet of the first gas/liquid separator in step (b), thereby obtaining an expanded gaseous stream which is at least partially condensed, and subsequently feeding all of the expanded gaseous stream into the distillation column at a second feeding point, the second feeding point being at a higher level than the first feeding point; (e) removing from the top of the distillation column a second gaseous stream, partially condensing the second gaseous stream thereby forming a partially condensed second gaseous stream, and feeding the partially condensed second gaseous stream into a second gas/liquid separator; (f) separating the stream fed in the second gas/liquid separator in step (e) thereby obtaining a second liquid stream and a third gaseous stream; (g) feeding the second liquid stream obtained in step (f) into the distillation column at a third feeding point, the third feeding point being at a higher level than the second feeding point; and (h) liquefying the third gaseous stream obtained in step (f) thereby obtaining a liquefied stream; wherein the second gaseous stream removed from the distillation column in step (e) is partially condensed by heat exchanging against all of the expanded gaseous stream before the expanded gaseous stream is fed into the distillation column at the second feeding point; and wherein the third gaseous stream obtained in step (f) is heat exchanged against the feed stream of step (a) before the third gaseous stream is liquefied in step (h), thereby partially condensing the feed stream. - View Dependent Claims (2, 3, 4, 5, 6, 7, 15, 16, 17, 18, 21, 22)
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8. An apparatus for liquefying a hydrocarbon stream comprising:
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a first gas/liquid separator having an inlet for a partly condensed feed stream having a pressure above 60 bar, a first outlet for a first gaseous stream and a second outlet for a first liquid stream; a distillation column having at least a first outlet for a second gaseous stream and a second outlet for a second liquid stream and first, second and third feeding points, the third feeding point being at a higher level than the second feeding point and the second feeding point being at a higher level than the first feeding point; a first expander for expanding all of the first gaseous stream obtained from the first outlet of the first gas/liquid separator; a second expander between the second outlet of the first gas/liquid separator and the first feeding point of the distillation column, for expanding the first liquid stream obtained from the second outlet of the first gas/liquid separator; a first heat exchanger between the first expander and the second feeding point of the distillation column, arranged to receive all of the expanded gaseous stream from the first expander; a second gas/liquid separator having an inlet for the second gaseous stream obtained at the first outlet of the distillation column, a first outlet for a third gaseous stream and a second outlet for a third liquid stream, the second outlet being connected to the third feeding point of the distillation column; a liquefaction unit for liquefying the third gaseous stream obtained at the first outlet of the second gas/liquid separator, the liquefaction unit comprising at least one cryogenic heat exchanger; and a further heat exchanger for heat exchanging the third gaseous stream obtained at the first outlet of the second gas/liquid separator against the feed stream, before the third gaseous stream is liquefied in the liquefaction unit; wherein the first heat exchanger is placed between the first outlet of the distillation column and the inlet of the second gas/liquid separator. - View Dependent Claims (9, 10, 11, 12, 13, 14, 19, 20)
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Specification