Liquefied natural gas processing

A process for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components wherein

• (a) said liquefied natural gas is heated sufficiently to at least partially vaporize said liquefied natural gas, thereby forming a vapor stream and a liquid stream;
• (b) said vapor stream, which is undivided, and said liquid stream are supplied to a fractionation column at upper and lower mid-column feed positions, respectively, wherein said vapor stream and said liquid stream are fractionated into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (c) a vapor distillation stream is withdrawn from a region of said fractionation column below said vapor stream and, in the absence of further compression, is cooled sufficiently to at least partially condense said vapor distillation stream, forming thereby a condensed stream and any residual vapor stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (d) at least a portion of said condensed stream is supplied to said fractionation column at a top column feed position;
• (e) at least a portion of said overhead vapor stream and said residual vapor stream are discharged as said volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components;
• and
• (f) the quantities and temperatures of said feeds to said fractionation column are effective to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

A process for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components wherein

• (a) said liquefied natural gas is heated sufficiently to at least partially vaporize said liquefied natural gas, thereby forming a vapor-containing stream;
• (b) said vapor-containing stream is undivided and is expanded to lower pressure and is supplied to a fractionation column at a mid-column feed position wherein said expanded vapor-containing stream is fractionated into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (c) a vapor distillation stream is withdrawn from a region of said fractionation column below said expanded vapor-containing stream and, in the absence of further compression, is cooled sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (d) said partially condensed vapor distillation stream is combined with said overhead vapor stream, forming thereby a condensed stream and a residual vapor stream;
• (e) at least a portion of said condensed stream is supplied to said fractionation column at a top column feed position;
• (f) said residual vapor stream is compressed to higher pressure and is thereafter cooled sufficiently to at least partially condense said residual vapor stream, forming thereby said volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• and
• (g) the quantities and temperatures of said feeds to said fractionation column are effective to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

A process for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components wherein

• (a) said liquefied natural gas is heated sufficiently to at least partially vaporize said liquefied natural gas, thereby forming a vapor stream and a liquid stream;
• (b) said vapor stream, which is undivided, and said liquid stream are expanded to lower pressure and are supplied to a fractionation column at upper and lower mid-column feed positions, respectively, wherein said expanded vapor stream and said expanded liquid stream are fractionated into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (c) a vapor distillation stream is withdrawn from a region of said fractionation column below said expanded vapor stream and, in the absence of further compression, is cooled sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (d) said partially condensed vapor distillation stream is combined with said overhead vapor stream, forming thereby a condensed stream and a residual vapor stream;
• (e) at least a portion of said condensed stream is supplied to said fractionation column at a top column feed position;
• (f) said residual vapor stream is compressed to higher pressure and is thereafter cooled sufficiently to at least partially condense said residual vapor stream, forming thereby said volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• and
• (g) the quantities and temperatures of said feeds to said fractionation column are effective to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

An apparatus for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components comprising

• (a) heat exchange means connected to receive said liquefied natural gas and heat said liquefied natural gas sufficiently to partially vaporize said liquefied natural gas, thereby forming a vapor-containing stream;
• (b) said heat exchange means further connected to a fractionation column to supply said vapor-containing stream, which is undivided, at a mid-column feed position, said fractionation column being adapted to fractionate said vapor-containing stream into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (c) vapor withdrawing means connected to said fractionation column to receive a vapor distillation stream from a region of said fractionation column below said vapor-containing stream;
• (d) said heat exchange means further connected to said withdrawing means to receive said vapor distillation stream and, in the absence of further compression, to cool said vapor distillation stream sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (e) separation means connected to said heat exchange means to receive said at least partially condensed vapor distillation stream and separate said at least partially condensed vapor distillation stream into a condensed steam and any residual vapor stream;
• (f) said separation means further connected to said fractionation column to supply at least a portion of said condensed stream to said fractionation column at a top column feed position;
• (g) combining means connected to said fractionation column and said separation means to receive said overhead vapor stream and said residual vapor stream, thereby forming said volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components;
• and
• (h) control means adapted to regulate the quantities and temperatures of said feed streams to said fractionation column to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

An apparatus for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components comprising

• (a) heat exchange means connected to receive said liquefied natural gas and heat said liquefied natural gas sufficiently to partially vaporize said liquefied natural gas;
• (b) first separation means connected to said heat exchange means to receive said heated partially vaporized liquefied natural gas and separate said heated partially vaporized liquefied natural gas into a vapor stream and a liquid stream;
• (c) said first separation means further connected to a fractionation column to supply said vapor stream, which is undivided, and said liquid stream at upper and lower mid-column feed positions, respectively, said fractionation column being adapted to fractionate said vapor stream and said liquid stream into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (d) vapor withdrawing means connected to said fractionation column to receive a vapor distillation stream from a region of said fractionation column below said vapor stream;
• (e) said heat exchange means further connected to said withdrawing means to receive said vapor distillation stream and, in the absence of further compression, to cool said vapor distillation stream sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (f) second separation means connected to said heat exchange means to receive said at least partially condensed vapor distillation stream and separate said at least partially condensed vapor distillation stream into a condensed steam and any residual vapor stream;
• (g) said second separation means further connected to said fractionation column to supply at least a portion of said condensed stream to said fractionation column at a top column feed position;
• (h) combining means connected to said fractionation column and said second separation means to receive said overhead vapor stream and said residual vapor stream, thereby forming said volatile vapor fraction containing a major portion of said methane and a major portion of said C2 components;
• and
• (i) control means adapted to regulate the quantities and temperatures of said feed streams to said fractionation column to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

An apparatus for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components comprising

• (a) heat exchange means connected to receive said liquefied natural gas and heat said liquefied natural gas sufficiently to partially vaporize said liquefied natural gas, thereby forming a vapor-containing stream;
• (b) expansion means connected to said heat exchange means to receive said vapor-containing stream and expand said vapor-containing stream to lower pressure;
• (c) said expansion means further connected to a fractionation column to supply said expanded vapor-containing stream, which is undivided, at a mid-column feed position, said fractionation column being adapted to fractionate said expanded vapor-containing stream into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (d) vapor withdrawing means connected to said fractionation column to receive a vapor distillation stream from a region of said fractionation column below said expanded vapor-containing stream;
• (e) said heat exchange means further connected to said withdrawing means to receive said vapor distillation stream and, in the absence of further compression, to cool said vapor distillation stream sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (f) combining means connected to said fractionation column and said heat exchange means to receive said overhead vapor stream and said at least partially condensed vapor distillation stream, thereby forming a combined stream;
• (g) separation means connected to said combining means to receive said combined stream and separate said combined stream into a condensed steam and a residual vapor stream;
• (h) said separation means further connected to said fractionation column to supply at least a portion of said condensed stream to said fractionation column at a top column feed position;
• (i) compressing means connected to said separation means to receive said residual vapor stream and compress said residual vapor stream to higher pressure;
• (j) said heat exchange means further connected to said compressing means to receive said compressed residual vapor stream and cool said compressed residual vapor stream sufficiently to at least partially condense said compressed residual vapor stream, thereby forming said volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• and
• (k) control means adapted to regulate the quantities and temperatures of said feed streams to said fractionation column to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.

An apparatus for the separation of liquefied natural gas containing methane, C2 components, and heavier hydrocarbon components into a volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components and a relatively less volatile liquid fraction containing any remaining C2 components and a major portion of said heavier hydrocarbon components comprising

• (a) heat exchange means connected to receive said liquefied natural gas and heat said liquefied natural gas sufficiently to partially vaporize said liquefied natural gas;
• (b) first separation means connected to said heat exchange means to receive said heated partially vaporized liquefied natural gas and separate said heated partially vaporized liquefied natural gas into a vapor stream and a liquid stream;
• (c) first expansion means connected to said first separation means to receive said vapor stream and expand said vapor stream to lower pressure;
• (d) second expansion means connected to said first separation means to receive said liquid stream and expand said liquid stream to lower pressure;
• (e) said first expansion means and said second expansion means further connected to a fractionation column to supply said expanded vapor stream, which is undivided, and said expanded liquid stream at upper and lower mid-column feed positions, respectively, said fractionation column being adapted to fractionate said expanded vapor stream and said expanded liquid stream into an overhead vapor stream and said relatively less volatile fraction containing the major portion of said heavier hydrocarbon components;
• (f) vapor withdrawing means connected to said fractionation column to receive a vapor distillation stream from a region of said fractionation column below said expanded vapor stream;
• (g) said heat exchange means further connected to said withdrawing means to receive said vapor distillation stream and, in the absence of further compression, to cool said vapor distillation stream sufficiently to at least partially condense said vapor distillation stream, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• (h) combining means connected to said fractionation column and said heat exchange means to receive said overhead vapor stream and said at least partially condensed vapor distillation stream, thereby forming a combined stream;
• (i) second separation means connected to said combining means to receive said combined stream and separate said combined stream into a condensed steam and a residual vapor stream;
• (j) said second separation means further connected to said fractionation column to supply at least a portion of said condensed stream to said fractionation column at a top column feed position;
• (k) compressing means connected to said second separation means to receive said residual vapor stream and compress said residual vapor stream to higher pressure;
• (l) said heat exchange means further connected to said compressing means to receive said compressed residual vapor stream and cool said compressed residual vapor stream sufficiently to at least partially condense said compressed residual vapor stream, thereby forming said volatile liquid fraction containing a major portion of said methane and a major portion of said C2 components, with said cooling supplying at least a portion of said heating of said liquefied natural gas;
• and
• (m) control means adapted to regulate the quantities and temperatures of said feed streams to said fractionation column to maintain the overhead temperature of said fractionation column at a temperature whereby the major portion of said heavier hydrocarbon components is recovered in said relatively less volatile liquid fraction.