Methods and systems for separating hydrocarbons

Abstract

Methods and systems for separating hydrocarbons are disclosed. In one example, a method for separating hydrocarbons includes separating a feed gas stream that includes methane, ethane, and propane and heavier hydrocarbons into a residue gas stream including the methane and the ethane and a natural gas liquids (NGL) stream include the propane and heavier hydrocarbons, compressing the residue gas stream to produce a hot and compressed residue gas stream, and heating a portion of the NGL stream with the hot and compressed residue gas stream.

What is claimed is: 
     
         1 . A method for separating hydrocarbons comprising the steps of:
 separating a feed gas stream that comprises methane, ethane, propane, and heavier hydrocarbons into a residue gas stream comprising the methane and the ethane and a natural gas liquids (NGL) stream comprising the propane and heavier hydrocarbons;   compressing the residue gas stream to produce a hot and compressed residue gas stream; and   heating a portion of the NGL stream with the hot and compressed residue gas stream.   
     
     
         2 . The method of  claim 1 , further comprising separating the NGL stream into a first portion and a second portion, and wherein heating the portion of the NGL stream comprises heating the second portion with the compressed residue gas stream. 
     
     
         3 . The method of  claim 1 , wherein heating the portion of the NGL stream comprises heating a heating oil with the hot and compressed residue gas stream to form a heated heating oil and heating the portion of the NGL stream with the heated heating oil. 
     
     
         4 . The method of  claim 3 , further comprising providing addition heat to the heating oil using an external energy input. 
     
     
         5 . The method of  claim 1 , wherein heating the portion of the NGL stream comprises directly exchanging heat between the hot and compressed residue gas stream and the portion of the NGL stream. 
     
     
         6 . The method of  claim 1 , further comprising expanding a first portion of the feed gas stream prior to separating the feed gas stream. 
     
     
         7 . The method of  claim 1 , wherein separating the feed gas stream comprises cooling a second portion of the feed gas stream. 
     
     
         8 . The method of  claim 1 , wherein separating the feed gas stream comprises combining the first and second portions of the feed gas stream to form a combined gas stream and contacting the combined gas stream with a mass transfer contacting device. 
     
     
         9 . The method of  claim 8 , further comprising contacting the portion of the NGL stream with the mass transfer contacting device. 
     
     
         10 . The method of  claim 1 , further comprising air cooling the hot and compressed residue gas stream subsequent to heating the portion of the NGL stream with the hot and compressed residue gas stream. 
     
     
         11 . A method for separating hydrocarbons comprising the steps of:
 passing a feed gas stream to a distillation column, the feed gas stream comprising methane, ethane, and propane and heavier hydrocarbons;   in the distillation column, separating the methane and the ethane from the propane and heavier hydrocarbons, thereby producing a residue gas stream comprising the methane and the ethane at an upper section of the distillation column and a natural gas liquids (NGL) stream comprising the propane and heavier hydrocarbons at a lower section of the distillation column;   separating the NGL stream into a first portion and a second portion, withdrawing the first portion from the distillation column as a product NGL stream, heating the second portion in a reboiler of the distillation column, and returning the heated second portion from the reboiler to the distillation column;   passing the residue gas stream to a compressor to produce a hot and compressed residue gas stream; and   directing heat from the hot and compressed residue gas stream to the reboiler to perform the step of heating the second portion of the product NGL stream.   
     
     
         12 . The method of  claim 11 , wherein directing heat from the hot and compressed residue gas stream to the reboiler comprises heating a heating oil with the hot and compressed residue gas stream to form a heated heating oil and heating the second portion of the NGL stream with the heated heating oil. 
     
     
         13 . The method of  claim 12 , further comprising providing addition heat to the heating oil using an external energy input. 
     
     
         14 . The method of  claim 11 , wherein directing heat from the hot and compressed residue gas stream to the reboiler comprises directly exchanging heat between the hot and compressed residue gas stream and the second portion of the NGL stream. 
     
     
         15 . The method of  claim 11 , further comprising, prior to passing the feed gas stream to the distillation column, passing a first portion of the feed gas stream to an expander/compressor to expand and cool the first portion of the feed gas stream. 
     
     
         16 . The method of  claim 15 , further comprising, prior to passing the feed gas stream to the distillation column, passing a second portion of the feed gas stream to a heat exchanger to cool the second portion of the feed gas stream. 
     
     
         17 . The method of  claim 16 , further comprising exchanging heat between the residue gas stream with the second portion of the feed gas stream, prior to passing the residue gas stream to a compressor. 
     
     
         18 . The method of  claim 17 , further comprising combining the first and second portions of the feed gas stream prior to passing the feed gas stream to the distillation column. 
     
     
         19 . The method of  claim 1 , further comprising air cooling the hot and compressed residue gas stream subsequent to directing heat from the hot and compressed residue gas stream to the reboiler. 
     
     
         20 . A system for separating hydrocarbons comprising:
 a distillation column that a) receives a feed gas stream comprising methane, ethane, and propane and heavier hydrocarbons and b) separates the methane and the ethane from the propane and heavier hydrocarbons to produce a residue gas stream comprising the methane and the ethane at an upper section of the distillation column and a natural gas liquids (NGL) stream comprising the propane and heavier hydrocarbons at a lower section of the distillation column;   a reboiler associated with the distillation column that a) receives a portion of the NGL stream from the distillation column, b) heats the portion of the NGL stream to form a heated NGL stream, and c) returns the heated portion of the NGL stream to the distillation column;   a compressor that compresses the residue gas stream to produce a hot and compressed residue gas stream; and   a heat exchange apparatus that directs heat from the hot and compressed residue gas stream to the reboiler to provide heat to the reboiler to accomplish the function (b) of heating the portion of the NGL stream.