NGL Extraction From Natural Gas

Abstract

A process of extraction of natural gas liquids from a hydrocarbon stream is disclosed. The recovered natural gas liquids are flashed to a vapor to provide refrigeration to the process.

1 . A process for the separation of C 2 + or C 3 + hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:
 providing a first stream of hydrocarbon gas;   cooling at least a portion of the first stream of hydrocarbon gas in a first heat exchanger to form a second stream;   introducing the second stream into a distillation column;   withdrawing a third stream of vapor hydrocarbon from an upper portion of said column having a reduced content of C 2 + or C 3 + hydrocarbons as compared to the first stream;   withdrawing a fourth stream of liquid natural gas liquid (NGL) hydrocarbon from as compared to the first stream;   reducing the pressure of the fourth stream to vaporize at least a portion of the fourth stream to form a fifth stream;   passing the fifth stream through the first heat exchanger to cool the first stream of hydrocarbon gas.   
   
   
       2 . The process of  claim 1 , further comprising:
 passing at least a portion of the third stream through the first heat exchanger to form a sixth stream.   
   
   
       3 . The process of  claim 1 , further comprising:
 diverting a portion of the first stream through a second heat exchanger to provide reboiler duty to the distillation column.   
   
   
       4 . The process of  claim 1 , wherein the first heat exchanger provides heat duty to a side reboiler of the distillation column. 
   
   
       5 . The process of  claim 1 , wherein the distillation column is operated with a bottom temperature of 0° F. to 350° F. and a top temperature of −160° F. to 0° F. 
   
   
       6 . The process of  claim 1 , wherein the distillation column is operated at a pressure of 150 psia to 700 psia. 
   
   
       7 . The process of  claim 1 , wherein a portion of the sixth stream is diverted to an upper region of the distillation column as a reflux stream. 
   
   
       8 . The process of  claim 1 , wherein the process does not include a turboexpander. 
   
   
       9 . The process of  claim 1 , wherein the process includes a turboexpander that expands at least a portion of the first stream. 
   
   
       10 . The process of  claim 1 , wherein the vaporization of at least a portion of the fourth stream provides at least 50% of the required cooling of the process. 
   
   
       11 . The process of  claim 1 , wherein the vaporization of at least a portion of the fourth stream provides at least 75% of the required cooling of the process. 
   
   
       12 . The process of  claim 1 , wherein the vaporization of at least a portion of the fourth stream provides 100% of the required cooling of the process. 
   
   
       13 . The process of  claim 1 , wherein the process is capable of operating at a turndown of less than 60% of plant capacity, while at least 50% of the ethane in the first stream is recovered in the fourth stream. 
   
   
       14 . The process of  claim 1 , wherein the process is capable of operating at a turndown of 10% of plant capacity, while at least 50% of the ethane in the first stream is recovered in the fourth stream. 
   
   
       15 . The process of  claim 1 , wherein the process is capable of operating from 5% to 100% of plant capacity, while recovering at least 60% of the ethane and at least 90% of C 3 + from the first stream in the fourth stream. 
   
   
       16 . The process of  claim 1 , wherein the process is capable of operating from 10% to 100% of plant capacity, while recovering at least 85% of the ethane and at least 95% of C 3 + from the first stream in the fourth stream. 
   
   
       17 . The process of  claim 1 , wherein the process operates with a reduced compression of at least 10% as compared to a comparable turboexpander process. 
   
   
       18 . A process for the separation of natural gas liquids from a hydrocarbon-containing gas feed comprising:
 providing a first stream of hydrocarbon gas;   cooling at least a portion of the first stream of hydrocarbon gas in a first heat exchanger to form a second stream;   introducing the second stream into a distillation column;   diverting a portion of the first stream through a second heat exchanger to provide reboiler duty to the distillation column;   wherein the distillation column includes a middle reboiler stream and a lower reboiler stream that are warmed by heat exchange with the second heat exchanger to provide heat duty to the distillation column;   wherein the distillation column includes a side stream that is warmed by heat exchange with the first heat exchanger to provide heat duty to the distillation column;   withdrawing a third stream of vapor hydrocarbon from an upper portion of said column having a reduced content of C 2 + or C 3 + hydrocarbons as compared to the first stream;   passing at least a portion of the third stream through the first heat exchanger to form a sixth stream;   withdrawing a fourth stream of liquid natural gas liquid (NGL) hydrocarbon from a lower portion of said column having an increased content of C 2 + or C 3 + hydrocarbons as compared to the first stream;   reducing the pressure of the fourth stream to vaporize at least a portion of the fourth stream to form a fifth stream;   passing the fifth stream through the first heat exchanger to cool the first stream of hydrocarbon gas;   wherein the process does not include a turboexpander and the distillation column is operated with a bottom temperature of 0° F. to 350° F., a top temperature of −160° F. to 0° F. and a pressure of 150 psia to 700 psia;   wherein the vaporization of at least a portion of the fourth stream provides at least 75% of the required cooling of the process; and   wherein the process is capable of operating from 5% to 100% of plant capacity, while recovering at least 85% of the ethane and at least 95% of C 3 + from the first stream in the fourth stream.   
   
   
       19 . The process of  claim 18 , wherein a portion of the sixth stream is diverted to an upper region of the distillation column as a reflux stream. 
   
   
       20 . The process of  claim 18 , wherein the process operates with a reduced compression of at least 10% as compared to a comparable turboexpander process.