Process of heat integrating feed and compressor discharge streams with heavies removal system in a liquefied natural gas facility

Abstract

An LNG facility employing an optimized heavies removal system. The heavies removal system can comprise at least one distillation column and at least two separate heat exchangers. Feed and/or compressor discharge streams can be used to provide heat duty to the heat exchangers in a thermally efficient manner to facilitate the removal of heavy components from an overall LNG facility.

1 . A process for liquefying a natural gas stream in a liquefied natural gas (LNG) facility, the process comprising:
 (a) cooling at least a portion of the natural gas stream in an upstream refrigeration cycle to thereby produce a cooled natural gas stream;   (b) introducing at least a portion of the cooled natural gas stream into an inlet of a first distillation column;   (c) introducing at least a portion of the natural gas stream to provide heat duty to a first reboiler associated with the first distillation column to produce a first heated vapor fraction and a first heated liquid fraction from a first reboiler inlet stream while cooling the portion of the natural gas stream and returning the cooled portion of the natural gas stream to the LNG facility;   (d) using the first distillation column and the first reboiler and associated first heated vapor fraction from the reboiler inlet stream to separate all incoming streams into a first column vapor stream, a first column liquid bottoms stream, wherein the first column vapor stream exits through an overhead outlet, wherein the first column liquid bottoms stream exits through a bottoms outlet;   (e) introducing at least a portion of the first column vapor stream exiting the first distillation column through the overhead outlet into the LNG facility;   (f) introducing at least a portion of the first column liquid bottoms stream from the first distillation column into a second heat exchanger;   (g) introducing at least a portion of the natural gas stream or at least a portion of a compressor discharge stream to provide heat duty to the second heat exchanger to thereby produce a second heated stream while cooling the portion of the natural gas stream or the portion of the compressor discharge stream; and   (h) introducing at least a portion of the second heated stream into a second distillation column.   
     
     
         2 . The process according to  claim 1 , wherein the cooled natural gas stream or at least a portion of the cooled natural gas stream from step (a) is expanded across a valve or expander to thereby produce a lower pressure stream before step (b). 
     
     
         3 . The process according to  claim 1 , wherein the cooled natural gas or at least a portion of the natural gas stream is separated into a liquid fraction and a vapor fraction prior to step (b). 
     
     
         4 . The process according to  claim 3 , wherein the liquid and the vapor fraction are introduced into the first distillation column in separate locations. 
     
     
         5 . The process according to  claim 4 , wherein the vapor fraction is combined with the first column vapor stream of step (d). 
     
     
         6 . The process according to  claim 2 , wherein the lower pressure stream is separated into a liquid fraction and a vapor fraction prior to step (b). 
     
     
         7 . The process according to  claim 6 , wherein the liquid and the vapor fraction are introduced into the first distillation column in separate locations. 
     
     
         8 . The process according to  claim 1 , wherein the first distillation column includes one or more side reboilers. 
     
     
         9 . The process according to  claim 1 , wherein the first distillation column includes one or more pumparounds. 
     
     
         10 . The process according to  claim 1 , wherein the first distillation column includes one or more reboilers and one or more pumparounds. 
     
     
         11 . The process according to  claim 1 , wherein the first distillation column includes an internal condenser. 
     
     
         12 . The process according to  claim 1 , wherein one or more side product streams are taken from the first distillation column; 
     
     
         13 . The process according to  claim 1 , wherein a gas stream introduced directly into the first distillation column provides heat duty to replace the heat duty supplied by the first reboiler of step (c). 
     
     
         14 . The process according to  claim 1 , wherein a gas stream introduced directly into the first distillation column provides heat duty to the first distillation column to supplement the heat duty supplied by the first reboiler according to step (c). 
     
     
         15 . The process according to  claim 1 , wherein at least a portion of the natural gas stream of step (g) includes any recycled stream or compressor discharge stream. 
     
     
         16 . The process according to  claim 1 , wherein the heat duty supplied to the second heat exchanger of step (g) is supplied by any compressor discharge stream. 
     
     
         17 . The process according to  claim 1 , wherein reflux provided to the first distillation column is liquefied natural gas or a portion of the overhead stream from the second distillation column of step (h).