Gas processing methodology utilizing reflux and additionally synthesized stream optimization

Abstract

Gas processing methodology for high efficiency recovery of propane and/or ethane from a natural gas feed stream. The method is conducted without turboexpansion. A natural gas stream is processed to have gas and liquid portions. The gas portion is cooled and flows to a refluxed absorber column and the liquid portion flows to a lower pressure distillation column. Bottoms of the absorber column are depressurized directly into a lower pressure distillation column and the overhead vapor stream is used to cool the feed and/or reflux streams. The overhead vapour stream from the lower pressure distillation column split into at least two streams with one being depressurized into the absorber to provide reflux and the second passed into the absorber column to provide further reflux.

1 . A method of processing natural gas to recover selected hydrocarbons contained therein, comprising:
 cooling and partially condensing a natural gas feed stream;   separating said natural gas stream into a liquid stream and a gas stream;   cooling and depressurizing said gas stream;   passing said gas stream into a fractionator column and said liquid stream into a distillation column;   recovering an overheads stream from said distillation column;   treating said overheads stream to first recover cooling energy and then compress said overheads stream to form a plurality of overhead streams as reflux streams at different pressures;   passing at least one of said overhead streams into said fractionator column as reflux and a second stream at a second point in said fractionator column to liquify hydrocarbon components present in said natural gas feed stream in said fractionator;   depressurizing and passing a bottoms stream from said fractionator column stream directly into said distillation column; and   collecting selected hydrocarbon components from said bottoms stream.   
     
     
         2 . The method as set forth in  claim 1 , wherein said method is entirely conducted absent turboexpansion. 
     
     
         3 . (canceled) 
     
     
         4 . The method as set forth in  claim 1 , wherein said depressurizing and feeding said bottoms stream directly into said distillation column. 
     
     
         5 . The method as set forth in  claim 1 , further including the step of varying fluid flow rate a at least between said fractionator column and said distillation column. 
     
     
         6 . (canceled) 
     
     
         7 . The method as set forth in  claim 1 , wherein said plurality of overheads streams comprise at least one liquid stream and at least one gas stream. 
     
     
         8 . The method as set forth in  claim 7 , wherein said at least one gas stream is passed into said fractionator column at said second point. 
     
     
         9 . A gas processing plant, comprising:
 a separator for receiving a cooled and partially condensed natural gas feed stream to separate said feed stream into a liquid stream and a gas stream;   a fractionator column for receiving said gas stream and reflux streams produced from a distillation column; and   a distillation column in fluid communication with said fractionator for producing an overheads stream, said overheads stream being utilized in said fractionator column as reflux streams to liquify hydrocarbons present in said feed stream, said fractionator column producing a bottoms stream which is depressurized into said distillation column to recover selected hydrocarbons in the absence of further unit operations.   
     
     
         10 . The gas processing plant as set forth in  claim 9 , further including a network of heat exchangers positioned to recover and distribute heat from all streams of said streams during processing. 
     
     
         11 . The gas processing plant as set forth in  claim 9 , wherein said overheads stream is compressed, cooled and divided into a plurality of overhead streams. 
     
     
         12 . The gas processing plant as set forth in  claim 11 , wherein at least one of said overhead streams is compressed, cooled and depressurized for use in said fractionator column as a reflux stream. 
     
     
         13 . The gas processing plant as set forth in  claim 11 , wherein said overhead streams are pressurized at a different pressure relative to one another. 
     
     
         14 . The gas processing plant as set forth in  claim 13 , wherein said overhead streams may exist in a gas, partially condensed, or liquid state. 
     
     
         15 . A method of processing natural gas with a fractionator column and distillation column in fluid communication to recover selected hydrocarbons contained therein, comprising a plurality of operations, comprising:
 a separation operation where a natural gas stream is processed to form a liquid stream and a gas stream which are separated;   an overheads processing and distribution operation where an overheads stream is recovered from said distillation column and processed into a plurality of overhead streams distributed into predetermined locations in said fractionator column;   a distillation operation in said fractionator column where said natural gas feed stream contacts said overhead streams to liquify hydrocarbon components present in said natural gas stream; and   a bottoms recovery and processing operation where a bottoms stream is recovered from said fractionator column and processed by depressurization directly in said distillation column in the absence of turboexpansion to recover selected hydrocarbons.   
     
     
         16 . The method as set forth in  claim 15 , wherein said method further includes heat exchange operations between each of the separation, overheads processing and distribution, refrigeration and bottoms recovery operations to recover and distribute heat between all streams associated with said operations. 
     
     
         17 . The method as set forth in  claim 15 , wherein said distillation column is operated as a deethanizer. 
     
     
         18 . The method as set forth in  claim 15 , wherein said distillation column is operated as a demethanizer. 
     
     
         19 . The method as set forth in  claim 15 , wherein said operations are modifiable to recover ethane, propane, hydrocarbons, or a combination thereof. 
     
     
         20 . The method as set forth in  claim 15 , wherein said separation operation includes cooling and partially condensing said natural gas feed stream. 
     
     
         21 . The method as set forth in  claim 15 , wherein said bottoms recovery and processing operation includes introducing said bottoms stream at a pressure of between 500 kPag and 2000 kPag into said distillation column relative to the pressure of between 2000 and 7000 kPag prior to introduction.