Liquefied natural gas and hydrocarbon gas processing
First Claim
1. A process for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components and a gas stream containing methane, C2 components, and heavier hydrocarbon components into a volatile residue gas fraction containing a major portion of said methane and said C2 components and a relatively less volatile liquid fraction containing a major portion of said heavier hydrocarbon components wherein(a) said liquefied natural gas is heated sufficiently to vaporize it, thereby forming a vapor stream;
- (b) said vapor stream is expanded to lower pressure and is thereafter supplied to a distillation column at a first mid-column feed position;
(c) said gas stream is expanded to said lower pressure, is cooled, and is thereafter supplied to said distillation column at a second mid-column feed position;
(d) a distillation vapor stream is withdrawn from a region of said distillation column below said expanded vapor stream and said expanded cooled gas stream, whereupon said distillation vapor stream is cooled sufficiently to at least partially condense it, forming thereby a condensed stream and a stream containing any remaining vapor, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
(e) at least a portion of said condensed stream is supplied to said distillation column as a reflux stream at a top column feed position;
(f) an overhead vapor stream is withdrawn from an upper region of said distillation column and divided into at least a first portion and a second portion, whereupon said second portion is compressed to higher pressure;
(g) said compressed second portion is cooled sufficiently to at least partially condense it and form thereby a volatile liquid stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
(h) said volatile liquid stream is heated sufficiently to vaporize it, with said heating supplying at least a portion of said cooling of said expanded gas stream;
(i) said first portion is heated, with said heating supplying at least a portion of said cooling of said distillation vapor stream;
(j) said any remaining vapor stream and said heated first portion are combined to form a residue vapor stream, and said residue vapor stream is heated, with said heating supplying at least a portion of said cooling of said expanded gas stream;
(k) said heated residue vapor stream is thereafter combined with said vaporized volatile liquid stream to form said volatile residue gas fraction containing a major portion of said methane and said C2 components; and
(l) the quantity and temperature of said reflux stream and the temperatures of said feeds to said distillation column are effective to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction by fractionation in said distillation column.
2 Assignments
0 Petitions
Accused Products
Abstract
A process for the recovery of heavier hydrocarbons from a liquefied natural gas (LNG) stream and a hydrocarbon gas stream is disclosed. The LNG feed stream is heated to vaporize at least part of it, then expanded and supplied to a fractionation column at a first mid-column feed position. The gas stream is expanded and cooled, then supplied to the column at a second mid-column feed position. A distillation vapor stream is withdrawn from the fractionation column below the mid-column feed positions and directed in heat exchange relation with the LNG feed stream, cooling the distillation vapor stream as it supplies at least part of the heating of the LNG feed stream. The distillation vapor stream is cooled sufficiently to condense at least a part of it, forming a condensed stream. At least a portion of the condensed stream is directed to the fractionation column as its top feed. A portion of the column overhead stream is also directed in heat exchange relation with the LNG feed stream, so that it also supplies at least part of the heating of the LNG feed stream as it is condensed to form a “lean” LNG stream. The quantities and temperatures of the feeds to the column are effective to maintain the column overhead temperature at a temperature whereby the major portion of the desired components is recovered in the bottom liquid product from the column.
146 Citations
34 Claims
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1. A process for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components and a gas stream containing methane, C2 components, and heavier hydrocarbon components into a volatile residue gas fraction containing a major portion of said methane and said C2 components and a relatively less volatile liquid fraction containing a major portion of said heavier hydrocarbon components wherein
(a) said liquefied natural gas is heated sufficiently to vaporize it, thereby forming a vapor stream; -
(b) said vapor stream is expanded to lower pressure and is thereafter supplied to a distillation column at a first mid-column feed position; (c) said gas stream is expanded to said lower pressure, is cooled, and is thereafter supplied to said distillation column at a second mid-column feed position; (d) a distillation vapor stream is withdrawn from a region of said distillation column below said expanded vapor stream and said expanded cooled gas stream, whereupon said distillation vapor stream is cooled sufficiently to at least partially condense it, forming thereby a condensed stream and a stream containing any remaining vapor, with said cooling supplying at least a portion of said heating of said liquefied natural gas; (e) at least a portion of said condensed stream is supplied to said distillation column as a reflux stream at a top column feed position; (f) an overhead vapor stream is withdrawn from an upper region of said distillation column and divided into at least a first portion and a second portion, whereupon said second portion is compressed to higher pressure; (g) said compressed second portion is cooled sufficiently to at least partially condense it and form thereby a volatile liquid stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas; (h) said volatile liquid stream is heated sufficiently to vaporize it, with said heating supplying at least a portion of said cooling of said expanded gas stream; (i) said first portion is heated, with said heating supplying at least a portion of said cooling of said distillation vapor stream; (j) said any remaining vapor stream and said heated first portion are combined to form a residue vapor stream, and said residue vapor stream is heated, with said heating supplying at least a portion of said cooling of said expanded gas stream; (k) said heated residue vapor stream is thereafter combined with said vaporized volatile liquid stream to form said volatile residue gas fraction containing a major portion of said methane and said C2 components; and (l) the quantity and temperature of said reflux stream and the temperatures of said feeds to said distillation column are effective to maintain the overhead temperature of said distillation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction by fractionation in said distillation column. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification