Patent ID: 8434326
Filing Date: 2013-05-07
Classification: F25J

Abstract:
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.