Method and apparatus for cooling a gaseous hydrocarbon stream

Abstract

A method of cooling a gaseous hydrocarbon stream ( 10 ) such as natural gas comprising at least the steps of: (a) sourcing the gaseous hydrocarbon stream ( 10 ) in an underwater pipeline ( 12 ) to a hydrocarbon facility at sea ( 18 ); (b) cooling the gaseous hydrocarbon stream ( 10 ) against one or more cooling streams ( 40 ) to remove heat from the gaseous hydrocarbon stream ( 10 ), and so provide a cooler hydrocarbon stream ( 20 ) and one or more warmer cooling streams ( 30 ); (c) using the heat of at least one warmer cooling stream ( 30 ) to heat the gaseous hydrocarbon stream ( 10 ) being sourced in the pipeline ( 12 ).

1 . A method of cooling a gaseous hydrocarbon stream, comprising at least the steps of:
 (a) sourcing the gaseous hydrocarbon stream in an underwater pipeline to a hydrocarbon facility at sea, the underwater pipeline extending between at least one well head on or near a seabed and the hydrocarbon facility at sea;   (b) cooling the gaseous hydrocarbon stream against one or more cooling streams by removing heat from the gaseous hydrocarbon stream, and so to provide a cooler hydrocarbon stream and one or more warmer cooling streams comprising a compressed refrigerant, wherein the cooling includes compressing the one or more cooling streams in at least one compressor and passing the compressors outflow stream through at least one downstream heat exchanger, removing heat from the one or more cooling streams in the at least one downstream heat exchanger, and passing the one or more cooling streams through an expander;   (c) using the heat of at least one of the warmer cooling stream(s) to heat the gaseous hydrocarbon stream being sourced in the pipeline;   
     wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is at least partly provided by at least one of the downstream heat exchanger(s), and wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is supplied to the pipeline in the form of a heated water stream carrying at least a fraction of the heat removed from the at least one of the warmer cooling stream(s). 
   
   
       2 . The method as claimed in  claim 1 , wherein the cooling in step (b) includes a cooling stage to cool the hydrocarbon stream to below 0° C. 
   
   
       3 . The method as claimed in  claim 1 , wherein the cooling in step (b) includes a liquefaction stage to liquefy the hydrocarbon stream, and to provide a liquefied hydrocarbon stream. 
   
   
       4 . (canceled) 
   
   
       5 . (canceled) 
   
   
       6 . The method as claimed in  claim 1 , wherein the gaseous hydrocarbon stream is pre-treated downstream of step (a) and prior to step (b), which treatment includes acid gas removal, and wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is at least partly provided by the acid gas removal process. 
   
   
       7 . (canceled) 
   
   
       8 . The method as claimed in  claim 1 , wherein at least part of the heated water stream is provided by heat exchange of at least a fraction of a water stream with at least one of the warmer cooling stream(s). 
   
   
       9 . The method as claimed in  claim 1 , wherein at least part of the heated water stream is provided by heat exchange between at least a fraction of a water stream and a heat transfer fluid, the heat transfer fluid carrying at least a fraction of the heat removed from the at least one of the warmer cooling stream(s). 
   
   
       10 . (canceled) 
   
   
       11 . The method as claimed in  claim 1 , wherein the hydrocarbon facility at sea is a floating vessel. 
   
   
       12 . An apparatus for cooling a gaseous hydrocarbon stream, the apparatus at least comprising:
 an underwater pipeline to a hydrocarbon facility at sea for sourcing the gaseous hydrocarbon stream to the hydrocarbon facility, the underwater pipeline extending between at least one well head on or near a seabed and the hydrocarbon facility at sea;   a cooling system to cool the gaseous hydrocarbon stream against one or more cooling streams, and so provide a cooler hydrocarbon stream and one or more warmer cooling streams comprising a compressed refrigerant, wherein the cooling system includes at least one compressor outflowing through at least one downstream heat exchanger removing heat from the one or more cooling streams, and an expander; and   a heating line to pass the heat of at least one of the warmer cooling stream(s) to the gaseous hydrocarbon stream in the pipeline wherein the heat for the heating line is at least partly provided by at least one of the downstream heat exchanger(s), and wherein the heat for the heating line is supplied to the pipeline in the form of a heated water stream carrying at least a fraction of the heat removed from the at least one of the warmer cooling stream(s).   
   
   
       13 . The apparatus as claimed in  claim 12 , wherein the cooling system includes a cooling stage and a liquefaction stage for liquefying the gaseous hydrocarbon stream. 
   
   
       14 . The apparatus as claimed in  claim 12 , wherein the hydrocarbon facility at sea is a floating vessel. 
   
   
       15 . The method as claimed in  claim 1 , further comprising a driver driving the at least one compressor, which driver generates a hot exhaust stream, the method further comprising using heat from the hot exhaust stream to heat the gaseous hydrocarbon stream being sourced in the pipeline. 
   
   
       16 . The method as claimed in  claim 1 , wherein the gaseous hydrocarbon stream is a natural gas stream. 
   
   
       17 . A method of cooling a gaseous hydrocarbon stream, comprising at least the steps of:
 (a) sourcing the gaseous hydrocarbon stream in an underwater pipeline to hydrocarbon facility at sea;   (b) cooling the gaseous hydrocarbon stream against one or more cooling streams by removing heat from the gaseous hydrocarbon stream, and so to provide a cooler hydrocarbon stream and one or more warmer cooling streams;   (c) using the heat of at least one of the warmer cooling stream(s) to heat the gaseous hydrocarbon stream being sourced in the pipeline.   
   
   
       18 . The method as claimed in  claim 17 , wherein the cooling in step (b) includes a cooling stage to cool the hydrocarbon stream to below 0° C. 
   
   
       19 . The method as claimed in  claim 17 , wherein the cooling in step (b) includes a liquefaction stage to liquefy the hydrocarbon stream, and to provide a liquefied hydrocarbon stream. 
   
   
       20 . The method as claimed in  claim 17 , wherein the cooling includes compressing the one or more cooling streams in at least one compressor and removing heat from the one or more cooling streams in at least one downstream heat exchanger, wherein the heat in step (c) for the gaseous hydrocarbon stream being sourced in the pipeline is at least partly provided by at least one of the downstream heat exchanger(s). 
   
   
       21 . The method as claimed in  claim 17 , wherein the gaseous hydrocarbon stream is pre-treated downstream of step (a) and prior to step (b), which treatment includes acid gas removal, and wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is at least partly provided by the acid gas removal process. 
   
   
       22 . The method as claimed in  claim 17 , wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is supplied to the pipeline in the form of a heated water stream carrying at least a fraction of the heat removed from the at least one of the warmer cooling streams. 
   
   
       23 . The method as claimed in  claim 22 , wherein at least part of the heated water stream is provided by heat exchange of at least a fraction of a water stream with at least one of the warmer cooling stream(s). 
   
   
       24 . The method as claimed in  claim 22 , wherein at least part of the heated water stream is provided by heat exchange between a fraction of a water stream and a heat transfer fluid, the heat transfer fluid carrying at least a fraction of the heat removed from the at least one of the warmer cooling stream(s). 
   
   
       25 . The method as claimed in  claim 17 , wherein the pipeline extends between one or more wellheads on or near a seabed and the hydrocarbon facility at sea. 
   
   
       26 . The method as claimed in  claim 17 , wherein the hydrocarbon facility at sea is a floating vessel. 
   
   
       27 . The method as claimed in  claim 17 , wherein the one or more warmer cooling streams comprises a compressed refrigerant. 
   
   
       28 . The method as claimed in  claim 17 , wherein the cooling includes compressing the one or more cooling streams in at least one compressor and passing the compressors outflow stream through at least one downstream heat exchanger, removing heat from the one or more cooling streams in the at least one downstream heat exchanger, and passing the one or more cooling streams through an expander, and wherein the heat for the gaseous hydrocarbon stream being sourced in the pipeline is at least partly provided by at least one of the downstream heat exchanger(s). 
   
   
       29 . The method as claimed in  claim 17 , further comprising a driver driving the at least one compressor, which driver generates a hot exhaust stream, the method further comprising using heat from the hot exhaust stream to heat the gaseous hydrocarbon stream being sourced in the pipeline. 
   
   
       30 . The method as claimed in  claim 17 , wherein the gaseous hydrocarbon stream is a natural gas stream. 
   
   
       31 . An apparatus for cooling a gaseous hydrocarbon stream, the apparatus at least comprising:
 an underwater pipeline to a hydrocarbon facility at sea for sourcing the gaseous hydrocarbon stream to the hydrocarbon facility;   a cooling system to cool the gaseous hydrocarbon stream against one or more cooling streams, and so provide a cooler hydrocarbon stream and one or more warmer cooling streams; and   a heating line to pass the heat of at least one of the warmer cooling stream(s) to the gaseous hydrocarbon stream in the pipeline.   
   
   
       32 . The apparatus as claimed in  claim 31 , wherein the cooling system includes a cooling stage and a liquefaction stage for liquefying the gaseous hydrocarbon stream. 
   
   
       33 . The apparatus as claimed in  claim 31 , wherein the hydrocarbon facility at sea is a floating vessel. 
   
   
       34 . The apparatus as claimed in  claim 31 , wherein the underwater pipeline extends between at least one well head on or near a seabed and the hydrocarbon facility at sea. 
   
   
       35 . The apparatus as claimed in  claim 31 , wherein the one or more warmer cooling streams comprises a compressed refrigerant. 
   
   
       36 . The apparatus as claimed in  claim 31 , wherein the cooling system includes at least one compressor outflowing through at least one downstream heat exchanger removing heat from the one or more cooling streams, and an expander, and wherein the heat for the heating line is at least partly provided by at least one of the downstream heat exchanger(s). 
   
   
       37 . The apparatus as claimed in  claim 31 , wherein the heat for the heating line is supplied to the pipeline in the form of a heated water stream carrying at least a fraction of the heat removed from the at least one of the warmer cooling stream(s).