Method and apparatus for treating a hydrocarbon stream

Abstract

A method of treating a hydrocarbon stream such as natural gas from a feed stream ( 10 ) comprising at least the steps of: a) passing the feed stream ( 10 ) through a distillation column ( 12 ) to provide a gaseous stream ( 20 ) and a C 2+ liquid stream ( 30 ); b) compressing at least part of the gaseous stream ( 20 ) through one or more feed compressors ( 14, 16 ) to provide a compressed stream ( 40 ); and c) commonly driving ( 28 ) at least one of the feed compressors with one or more separate refrigerant compressors for one or more separate refrigerant circuits, by mechanically interconnecting said compressors.

1 . A method of treating a hydrocarbon stream from a feed stream comprising at least the steps of:
 (a) passing the feed stream through a distillation column to provide a gaseous stream and a C2+ liquid stream;   (b) compressing at least part of the gaseous stream through one or more feed compressors to provide a compressed stream; and   (c) commonly driving at least one of the feed compressors with one or more separate refrigerant compressors for one or more separate refrigerant circuits, by mechanically interconnecting said compressors.   
   
   
       2 . A method as claimed in  claim 1  wherein the distillation column is a natural gas liquid recovery column. 
   
   
       3 . A method as claimed in  claim 1  wherein the feed stream is expanded prior to passing through the distillation column. 
   
   
       4 . A method as claimed in  claim 1  wherein the compressing of step (b) involves first and second feed compressors. 
   
   
       5 . A method as claimed in  claim 1  further comprising the step of:
 cooling the compressed stream by passing the compressed stream against one or more refrigerants being in one or more of the refrigerant circuits.   
   
   
       6 . A method as claimed in  claim 5  wherein the second feed compressor is mechanically interconnected with a refrigerant compressor of one or more of the refrigerant circuits cooling the compressed stream. 
   
   
       7 . A method as claimed in  claim 5 , wherein the cooling of the compressed stream involves at least two cooling stages, each stage including at least one refrigerant circuit. 
   
   
       8 . A method as claimed in  claim 7  wherein the cooling of the compressed stream involves one pre-cooling stage and one main cooling stage, and the or a feed compressor of step (b) is mechanically interconnected with a refrigerant compressor of the pre-cooling refrigerant circuit. 
   
   
       9 . A method as claimed in  claim 5  wherein the cooling of the compressed stream involves liquefying the compressed stream thereby obtaining a liquefied hydrocarbon stream. 
   
   
       10 . A method as claimed in  claim 1  further comprising the step of:
 cooling the feed stream upstream of step (a) by passing the feed stream against one or more refrigerants being in one or more of the refrigerant circuits.   
   
   
       11 . A method as claimed in  claim 10  wherein the or a feed compressor of step (b) is mechanically interconnected with a refrigerant compressor of the refrigerant circuit cooling the feed stream. 
   
   
       12 . A method as claimed in  claim 1  further comprising the step of: cooling the feed stream upstream of step (a) against at least part of the gaseous stream. 
   
   
       13 . Apparatus for treating a hydrocarbon stream from a feed stream, the apparatus at least comprising:
 a distillation column having an inlet for the feed stream and a first outlet for a gaseous stream and a second outlet for a C2+ liquid stream;   one or more feed compressors for compressing at least a part of the gaseous stream; and   a common driver for driving one or more of the feed compressors with one or more separate refrigerant compressors for one or more separate refrigerant circuits.   
   
   
       14 . Apparatus as claimed in  claim 13 , wherein the commonly driven compressors are mechanically interconnected and arranged on a common drive shaft of the driver. 
   
   
       15 . Apparatus as claimed in  claim 13 , wherein the apparatus includes an expander to expand the feed stream upstream of the distillation column. 
   
   
       16 . Apparatus as claimed in  claim 15  wherein the expander is mechanically interconnected to one or more of the feed compressors and is partly, substantially or wholly driven thereby. 
   
   
       17 . Apparatus as claimed in  claim 13 , wherein the apparatus further includes a cooling system for cooling the gaseous stream, which cooling system involves at least one pre-cooling stage and at least one main cooling stage, each stage including at least one refrigerant circuit and at least one refrigerant compressor. 
   
   
       18 . Apparatus as claimed in  claim 15 , wherein one feed compressor of step (b) is mechanically interconnected with a refrigerant compressor of a pre-cooling refrigerant circuit. 
   
   
       19 . Apparatus as claimed in  claim 15 , wherein at least one refrigerant compressor of both the pre-cooling and main cooling refrigerant circuits are mechanically interconnected and are arranged to be driven by said common driver. 
   
   
       20 . Apparatus as claimed in  claim 13 , wherein the cooling system includes a liquefying system to obtain a liquefied hydrocarbon stream.