Method and apparatus for treating a hydrocarbon stream

Abstract

The present invention relates to a method of treating a hydrocarbon stream such as a natural gas stream, the method at least comprising the steps of: (a) supplying a partially condensed feed stream ( 10 ) to a first gas/liquid separator ( 2 ), the feed stream ( 10 ) having a pressure >50 bar; (b) separating the feed stream ( 10 ) in the first gas/liquid separator ( 2 ) into a first vaporous stream ( 20 ) and a first liquid stream ( 70 ); (c) expanding the first vaporous stream ( 20 ), thereby obtaining an at least partially condensed first vaporous stream ( 30 ); (d) supplying the at least partially condensed first vaporous stream ( 30 ) to a second gas/liquid separator (4); (e) separating the stream ( 30 ) as supplied in step (d) in the second gas/liquid separator ( 4 ) into a second vaporous stream ( 60 ) and a second liquid stream ( 40 ); (f) increasing the pressure of the second liquid stream ( 40 ) to a pressure of at least 50 bar, thereby obtaining a pressurized second liquid stream ( 50 ); and (g) returning the pressurized second liquid stream ( 50 ) to the first gas/liquid separator ( 2 ).

1 . A method of treating a hydrocarbon stream, the method at least comprising the steps of:
 (a) supplying a partially condensed feed stream to a first gas/liquid separator, the feed stream having a pressure >50 bar;   (b) separating the feed stream in the first gas/liquid separator into a first vaporous stream and a first liquid stream;   (c) expanding the first vaporous stream obtained in step (b), thereby obtaining an at least partially condensed first vaporous stream;   (d) supplying the at least partially condensed first vaporous stream obtained in step (c) to a second gas/liquid separator;   (e) separating the stream as supplied in step (d) in the second gas/liquid separator into a second vaporous stream and a second liquid stream;   (f) increasing the pressure of the second liquid stream obtained in step (e) to a pressure of at least 50 bar, thereby obtaining a pressurized second liquid stream; and   (g) returning the pressurized second liquid stream obtained in step (f) to the first gas/liquid separator.   
   
   
       2 . The method according to  claim 1 , wherein in step (a) the feed stream is supplied as at least two different streams to the first gas/liquid separator, the feed stream comprising a higher feed stream and a lower feed stream. 
   
   
       3 . The method according to  claim 2 , wherein the higher feed stream is cooled before it is supplied to the first gas/liquid separator. 
   
   
       4 . The method according to  claim 3 , wherein the higher feed stream is cooled against the second vaporous stream obtained in step (e). 
   
   
       5 . The method according to  claim 1 , wherein the first liquid stream obtained in step (b) is supplied to a third gas/liquid separator thereby obtaining a third vaporous stream and a third liquid stream. 
   
   
       6 . The method according to  claim 5 , wherein the third vaporous stream is combined with the second vaporous stream. 
   
   
       7 . The method according to  claim 5 , wherein the third liquid stream is heat exchanged against the first liquid stream, before it is supplied to the third gas/liquid separator. 
   
   
       8 . The method according to  claim 5 , wherein the third liquid stream is heat exchanged against the lower feed stream. 
   
   
       9 . The method according to  claim 5 , wherein the third column is a debutanizer, thereby obtaining a third vaporous stream being enriched in butane and lower hydrocarbons relative to the third liquid stream. 
   
   
       10 . The method according to  claim 1 , wherein the second vaporous stream, is liquefied, thereby obtaining a liquefied hydrocarbon stream. 
   
   
       11 . An apparatus for treating a hydrocarbon stream, the apparatus at least comprising:
 a first gas/liquid separator for separating a partially condensed feed stream O into a first vaporous stream and a first liquid stream;   an expander for expanding the first vaporous stream;   a second gas/liquid separator for separating the expanded first vaporous stream into a second vaporous stream and a second liquid stream; and   a pressurizing unit for increasing the pressure of the second liquid stream to a pressure of at least 50 bar before being returned to the first gas/liquid separator.   
   
   
       12 . The apparatus according to  claim 11 , wherein the first gas/liquid separator comprises at least two inlets for the feed stream, including a first inlet for a higher feed stream and a second inlet for a lower feed stream. 
   
   
       13 . The apparatus according to  claim 12 , wherein the apparatus further comprises a heat exchanger for cooling the higher feed stream against the second vaporous stream. 
   
   
       14 . The apparatus according to  claim 11 , wherein the apparatus further comprises a third gas/liquid separator for separating the first liquid stream into a third vaporous stream and a third liquid stream. 
   
   
       15 . The apparatus according to  claim 14 , wherein the third vaporous stream can be combined with the second vaporous stream. 
   
   
       16 . The method according to  claim 2 , wherein the first liquid stream obtained in step (b) is supplied to a third gas/liquid separator thereby obtaining a third vaporous stream and a third liquid stream. 
   
   
       17 . The method according to  claim 3 , wherein the first liquid stream obtained in step (b) is supplied to a third gas/liquid separator thereby obtaining a third vaporous stream and a third liquid stream. 
   
   
       18 . The method according to  claim 4 , wherein the first liquid stream obtained in step (b) is supplied to a third gas/liquid separator thereby obtaining a third vaporous stream and a third liquid stream. 
   
   
       19 . The method according to  claim 6 , wherein the third liquid stream is heat exchanged against the first liquid stream, before it is supplied to the third gas/liquid separator. 
   
   
       20 . The method according to  claim 6 , wherein the third liquid stream is heat exchanged against the lower feed stream.