Enhanced NGL recovery utilizing refrigeration and reflux from LNG plants

A process for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• introducing said gas feed into an NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• cooling said second gas stream and thereafter introducing said cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• liquefying said first gas stream to produce a pressurized LNG stream;
• expanding said pressurized LNG stream in one or more expanding stages to produce an LNG stream suitable for storage;
• and
• producing a portion of said overhead reflux from a portion of the flashed vapor generated in one or more of said expanding stages.

A process for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• introducing said gas feed into an NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• compressing and then cooling said second gas stream;
• introducing said compressed, cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• and
• liquefying said first gas stream to produce a pressurized LNG stream.

A process for recovering the relatively less volatile components from a methane-rich gas feed to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• further cooling a portion of said cooled gas feed with mechanical refrigeration to substantial condensation and thereafter introducing said substantially condensed gas feed into the top of an NGL recovery column as an overhead reflux;
• introducing the remaining portion of said cooled gas feed into said NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components rich in methane and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• and
• liquefying said first gas stream utilizing at least one mechanical refrigeration cycle to produce a pressurized LNG stream.

A process for recovering the relatively less volatile components from a methane-rich gas feed to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• separating said cooled gas feed into a cooled vapor portion and a cooled liquid portion comprising condensed components, if any;
• dividing said cooled vapor portion into a first vapor portion and a second vapor portion;
• further cooling said first vapor portion with mechanical refrigeration to substantial condensation and thereafter introducing said substantially condensed first vapor portion into an NGL recovery column as a reflux;
• introducing the remaining portion of said cooled gas feed comprising said second vapor portion and said cooled liquid portion into said NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components rich in methane and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• liquefying said first gas stream utilizing at least one mechanical refrigeration cycle to produce a pressurized LNG stream;
• and
• introducing at least a portion of said pressurized LNG stream to the top of said NGL recovery column as an overhead reflux to enhance recovery of relatively less volatile components.

A process for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• introducing said cooled gas feed into an NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• liquefying said first gas stream to produce a pressurized LNG stream;
• expanding said pressurized LNG stream in one or more stages to a lower pressure to produce an LNG stream suitable for storage and at least one flashed vapor stream;
• and
• compressing and cooling at least a portion of said flashed vapor stream to substantial condensation and thereafter introducing said substantially condensed, flashed vapor stream to a top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• a heat exchanger for cooling at least a portion of a gas feed by means of a mechanical refrigeration cycle;
• an NGL recovery column for receiving said cooled gas feed at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• a heat exchanger for cooling said second gas stream with mechanical refrigeration;
• means for introducing said cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• and
• means for liquefying said first gas stream utilizing at least one mechanical refrigeration cycle to produce a pressurized LNG stream, wherein said heat exchangers can be the same or different.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• a heat exchanger for cooling at least a portion of a gas feed by means of a mechanical refrigeration cycle;
• an NGL recovery column for receiving said cooled gas feed at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• a compressor for compressing said second gas stream prior to cooling to substantial condensation;
• a heat exchanger for cooling said second gas stream;
• means for introducing said cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• and
• means for liquefying said first gas stream to produce a pressurized LNG stream, wherein said heat exchangers can be the same or different.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• a heat exchanger for cooling at least a portion of a gas feed by means of a mechanical refrigeration cycle;
• means for further cooling a portion of said cooled gas feed with mechanical refrigeration to substantial condensation;
• an NGL recovery column;
• means for introducing said condensed gas feed into the top of said NGL recovery column as an overhead reflux;
• means for introducing the remaining portion of said cooled gas feed into said NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components rich in methane and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• and
• means for liquefying said first gas stream utilizing at least one mechanical refrigeration cycle to produce a pressurized LNG stream.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• one or more heat exchangers for cooling at least a portion of a gas feed by means of mechanical refrigeration cycle;
• an NGL recovery column for receiving said cooled gas feed at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• means for liquifying said first gas stream to produce a pressurized LNG stream;
• and
• means for introducing at least a portion of said pressurized LNG stream to the top of said NGL recovery column as an overhead reflux to enhance recovery of relatively less volatile components.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• a first heat exchanger for cooling at least a portion of a gas feed by means of a mechanical refrigeration cycle;
• an NGL recovery column for receiving said cooled gas feed at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• means for liquifying said first gas stream to produce a pressurized LNG stream;
• means for expanding said pressurized LNG stream in one or more stages to a lower pressure to produce an LNG stream suitable for storage and at least one flashed vapor stream;
• means for compressing and cooling at least a portion of said flashed vapor stream to substantial condensation;
• and
• means for introducing said substantially condensed, flashed vapor stream to a top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components.

A process for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising the steps of:

• cooling at least a portion of a gas feed in one or more heat exchangers by means of a mechanical refrigeration cycle;
• introducing said gas feed into an NGL recovery column at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• introducing said first liquid stream into an NGL purifying column at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• cooling said second gas stream and thereafter introducing said cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• and
• introducing said first gas stream directly to a next cooling step for liquefying said first gas stream to produce a pressurized LNG stream.

Apparatus for recovering the relatively less volatile components from a methane-rich gas feed under pressure to produce an NGL product while rejecting the relatively more volatile components which are subsequently liquified to produce LNG, comprising:

• a heat exchanger for cooling at least a portion of a gas feed by means of a mechanical refrigeration cycle;
• an NGL recovery column for receiving said cooled gas feed at one or more feed stages for separation into a first gas stream primarily comprising relatively more volatile components and a first liquid stream primarily comprising relatively less volatile components;
• an NGL purifying column for receiving said first liquid stream at one or more feed stages to produce an NGL product stream comprising desirable less volatile components from the bottom and a second gas stream comprising more volatile components from the overhead of said NGL purifying column;
• a heat exchanger for cooling said second gas stream;
• means for introducing said cooled, second gas stream to the top portion of said NGL recovery column as an overhead reflux to enhance recovery of desirable less volatile components;
• and
• a heat exchanger for liquefying said first gas stream to produce a pressurized LNG stream, said first gas stream being directly received by said heat exchanger without prior heating and wherein said heat exchangers can be the same or different.