Propane recovery methods

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a first distillation column at one or more feed trays;
• providing heat to a portion of said first distillation column below said feed trays to substantially strip off methane and ethane from said gas feed;
• separating said gas/condensate feed in said first column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2+ hydrocarbons;
• introducing said first liquid phase into a second distillation column at one or more feed trays;
• separating said first liquid phase in said second distillation column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3+ hydrocarbons;
• cooling and condensing said second gas phase primarily comprising ethane;
• introducing into said first distillation column as an overhead reflux at least a portion of said cooled and condensed second gas phase primarily comprising ethane;
• and
• recovering from the bottom of said second distillation column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cold gas/condensate feed into a first distillation column at one or more feed trays;
• separating said gas/condensate feed in said first distillation column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2+ hydrocarbons;
• heating and compressing said first gas phase to produce a residue gas for delivery to a pipeline;
• introducing said first liquid phase into a second distillation column at one or more feed trays;
• separating said first liquid phase in said second distillation column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3+ hydrocarbons;
• cooling said second gas phase by countercurrent heat exchange with a condensed liquid withdrawn from said first distillation column at a tray located below said feed trays;
• separating said cooled second gas phase into a first fraction primarily comprising ethane and a second fraction primarily comprising C.sub.3+ hydrocarbons;
• introducing into said first distillation column an overhead reflux comprising said first fraction and up to about five percent-by-weight of said residue gas;
• introducing into said second distillation column said second fraction;
• and
• recovering from the bottom of said second distillation column substantially pure C.sub.3+ hydrocarbons comprising at least about 94 percent-by-weight of the C.sub.3+ hydrocarbons in said gas/condensate feed.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a de-methanizer column at one or more feed trays;
• separating said gas/condensate feed in said de-methanizer column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2+ hydrocarbons;
• introducing said first liquid phase into a de-ethanizer column at one or more feed trays;
• separating said first liquid phase in said de-ethanizer column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3+ hydrocarbons;
• cooling said second gas phase by countercurrent heat exchange with a mixture comprising condensed liquid withdrawn from said de-methanizer column at a tray located below said feed trays and a portion of liquid separated from said gas/condensate feed before its introduction into said de-methanizer column;
• separating said cooled second gas phase into a first gaseous fraction primarily comprising ethane and a second liquid fraction;
• heating said first gas phase by countercurrent heat exchange with at least one of said first gaseous fraction and said gas feed and thereafter compressing said heated gas phase to produce a residue gas;
• cooling and condensing said first gaseous fraction primarily comprising ethane;
• introducing into said de-methanizer column as an overhead reflux said cooled and condensed first gaseous fraction primarily comprising ethane;
• introducing into said de-ethanizer column said second liquid fraction;
• and
• recovering from the bottom of said de-ethanizer column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a de-methanizer column at one or more feed trays;
• separating said gas/condensate feed in said de-methanizer column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2 + hydrocarbons;
• using a portion of said first liquid phase as a refrigerant stream to cool said gas feed resulting in partial vaporization of said refrigerant stream;
• introducing another portion of said first liquid phase into a de-ethanizer column at one or more feed trays;
• separating said first liquid phase in said de-ethanizer column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3+ hydrocarbons;
• cooling said second gas phase by countercurrent heat exchange with a mixture comprising condensed liquid withdrawn from said de-methanizer column at a tray located below said feed trays and a portion of liquid separated from said gas/condensate feed before its introduction into said de-methanizer column;
• separating said cooled second gas phase into a first gaseous fraction primarily comprising ethane and a second liquid fraction;
• separating said partially vaporized refrigerant stream into a third liquid phase which is introduced into said de-ethanizer column and a third gas phase which is introduced into said de-methanizer column as a stripping gas;
• cooling and condensing said first gaseous fraction primarily comprising ethane;
• introducing into said de-methanizer column as an overhead reflux said cooled and condensed first gaseous fraction primarily comprising ethane;
• introducing into said de-ethanizer column said second liquid fraction;
• and
• recovering from the bottom of said de-ethanizer column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a de-methanizer column at one or more feed trays;
• separating said gas/condensate feed in said de-methanizer column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2 + hydrocarbons;
• introducing said first liquid phase into a de-ethanizer column at one or more feed trays;
• separating said first liquid phase in said de-ethanizer column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3 + hydrocarbons;
• cooling said second gas phase by countercurrent heat exchange with a mixture comprising condensed liquid withdrawn from said de-methanizer column at a tray located below said feed trays and a portion of liquid separated from said gas/condensate feed before its introduction into said de-methanizer column;
• introducing said heated mixture back into said de-methanizer column at a location below the tray from which said condensed liquid was withdrawn;
• separating said cooled second gas phase into a first gaseous fraction primarily comprising ethane and a second liquid fraction;
• cooling and condensing said first gaseous fraction primarily comprising ethane;
• introducing into said de-methanizer column as an overhead reflux said cooled and condensed first gaseous fraction primarily comprising ethane;
• introducing into said de-ethanizer column said second liquid fraction;
• and
• recovering from the bottom of said de-ethanizer column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a first distillation column at one or more feed trays;
• separating said gas/condensate feed in said first column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2 + hydrocarbons;
• introducing said first liquid phase into a second distillation column at one or more feed trays;
• separating said first liquid phase in said second distillation column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3 + hydrocarbons;
• cooling and condensing said second gas phase primarily comprising ethane;
• introducing into said first distillation column as an overhead reflux at least a portion of said cooled and condensed second gas phase primarily comprising ethane and up to about 5 percent-by-volume of a residue gas recovered from said first gas phase;
• and
• recovering from the bottom of said second distillation column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a first distillation column at one or more feed trays;
• separating said gas/condensate feed in said first column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2 + hydrocarbons;
• introducing said first liquid phase into a second distillation column at one or more feed trays;
• separating said first liquid phase in said second distillation column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3 + hydrocarbons;
• cooling and condensing said second gas phase primarily comprising ethane;
• introducing into said first distillation column as an overhead reflux at least a portion of said cooled and condensed second gas phase primarily comprising ethane and up to about 10 percent-by-volume of a residue gas recovered from said first gas phase to prevent the formation in said overhead reflux of solids comprising ice, hydrates and mixtures thereof;
• and
• recovering from the bottom of said second distillation column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.

A process for the separation of C.sub.3+ hydrocarbons from a hydrocarbon-containing gas feed under pressure, comprising:

• introducing a cooled gas/condensate feed into a first distillation column at one or more feed trays;
• separating said gas/condensate feed in said first column into a first gas phase primarily comprising methane and ethane and into a first liquid phase primarily comprising C.sub.2 + hydrocarbons;
• using a portion of said first liquid phase as a refrigerant stream to cool said gas feed resulting in partial vaporization of said refrigerant stream;
• introducing another portion of said first liquid phase into a second distillation column at one or more feed trays;
• separating said first liquid phase in said second distillation column into a second gas phase primarily comprising ethane and a second liquid phase primarily comprising C.sub.3 + hydrocarbons;
• separating said partially vaporized refrigerant stream into a third liquid phase which is introduced into said second distillation column and a third gas phase which is introduced into said first distillation column as a stripping gas;
• cooling and condensing said second gas phase primarily comprising ethane;
• introducing into said first distillation column as an overhead reflux at least a portion of said cooled and condensed second gas phase primarily comprising ethane;
• and
• recovering from the bottom of said second distillation column said second liquid phase primarily comprising C.sub.3+ hydrocarbons.