Lean reflux-high hydrocarbon recovery process

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. preheating at least a portion of the first liquid and then sending the portion of the first liquid stream to a distillation tower, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• c. cooling and partially condensing the tower overhead stream thereby producing a second vapor stream and a liquid hydrocarbon stream;
• d. sending the liquid hydrocarbon stream to the distillation tower;
• e. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone as a bottom feed stream thereby producing an absorber overhead stream containing essentially all methane, C2, and lighter components of the gas stream and an absorber bottoms stream;
• f. preheating at least a portion of the absorber bottoms stream and directing the portion of the absorber bottoms stream into the distillation tower;
• g. condensing at least a portion of the second vapor stream thereby forming a first lean reflux stream and sending the first lean reflux stream to the absorber;
• h. heating and compressing the absorber overhead stream to produce a residue gas stream;
• and
• i. wherein the improvement comprises cooling and at least partially condensing a portion of the first vapor stream thereby producing a second lean reflux stream and then sending the second lean reflux stream to the absorber column.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone as a bottom feed stream thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and an absorber bottoms stream;
• c. expanding at least the first liquid stream and feeding the first liquid stream to the absorber column 32;
• d. preheating at least a portion of the absorber bottoms stream and sending the portion of the absorber bottoms stream to a distillation tower the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• e. cooling and partially condensing the tower overhead stream thereby producing a second vapor stream and a liquid hydrocarbon stream, the liquid hydrocarbon stream being directed to the distillation tower as a top feed;
• f. condensing at least a portion of second vapor stream thereby forming a first lean reflux stream and sending the first lean reflux stream to the absorber column;
• g. heating the absorber overhead stream, compressing, and discharging the absorber overhead stream as residue gas;
• and
• h. wherein the improvement comprises cooling and at least partially condensing the portion of the residue gas thereby producing a second lean reflux stream and then sending the second lean reflux stream to the absorber column. Make sending to top of the absorber a dependent claim.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream;
• b. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and an absorber bottoms stream;
• c. expanding at least the first liquid stream and feeding the first liquid stream to the absorber;
• d. preheating at least a portion of the absorber bottoms stream and sending the portion of the absorber bottoms stream to a distillation tower, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• e. cooling and partially condensing the tower overhead stream thereby producing a second vapor stream and a liquid hydrocarbon stream;
• f. sending the liquid hydrocarbon stream to the distillation tower;
• g. condensing at least a portion of the second vapor stream thereby forming a first lean reflux stream and sending the first lean reflux stream to the absorber column;
• h. heating and compressing the absorber overhead stream to produce a residue gas stream;
• and
• i. wherein an improvement comprises cooling and at least partially condensing a portion of the first vapor stream thereby producing a second lean reflux stream and then sending the second lean reflux stream to the absorber column.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. preheating at least a portion of the first liquid and then sending the portion of the first liquid into a distillation tower as a lower tower feed stream, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• c. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and an absorber bottoms stream;
• d. sending at least a portion of the tower overhead stream to the absorber column as a first lean reflux stream;
• e. heating and compressing the absorber overhead stream to produce a residue gas stream;
• and
• f. wherein an improvement comprises preheating a first portion of the absorber bottoms stream and sending the first portion of the absorber bottoms stream to the distillation tower, and sending a second portion of the absorber bottoms stream to the distillation tower.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and an absorber bottoms stream;
• c. expanding at least the first liquid stream and feeding the first liquid stream to the absorber column;
• d. preheating at least a portion of the absorber bottoms stream and sending the portion of the absorber bottoms stream to a distillation tower, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• e. condensing at least a portion of a tower overhead stream and sending it to the absorber column as a first lean reflux stream;
• f. heating the absorber overhead stream, compressing, and discharging the absorber overhead stream as a residue gas;
• and
• g. wherein an improvement comprises preheating a first portion of the absorber bottoms stream and sending the portion of the absorber bottoms stream to the distillation tower, and sending a second portion of the absorber bottoms stream to the distillation tower.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large, portion of C3 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. expanding the first vapor stream and sending the first vapor stream to an absorber column having at least one mass transfer zone thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and an absorber bottoms stream;
• c. expanding at least the first liquid stream and feeding the first liquid stream to the absorber column;
• d. preheating at least a portion of the absorber bottoms stream and sending the portion of the absorber bottoms stream to a distillation tower, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• e. condensing at least a portion of the tower overhead stream and sending it to the absorber column as a first lean reflux stream;
• f. heating and compressing the absorber overhead stream to produce a residue gas stream;
• and
• g. wherein an improvement comprises cooling and at least partially condensing a portion of the first vapor stream thereby producing a second lean reflux stream and then sending the second lean reflux stream to the absorber column.

A process for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane components and a less volatile fraction containing a large portion of C2 components and heavier hydrocarbons, the process comprising the steps of:

• a. supplying and cooling a gas stream to partially condense at least a portion of the gas stream to produce a first vapor stream and at least a first liquid stream containing some lighter components;
• b. sending the first liquid stream to a distillation tower, the distillation tower producing a tower overhead stream containing mainly methane components and a tower bottoms stream containing a majority of the C2 components and heavier hydrocarbons;
• c. splitting the first vapor stream into a first separator overhead stream and a second overhead stream;
• d. expanding and sending the first separator overhead stream to an absorber column having at least one mass transfer zone thereby producing an absorber overhead stream containing essentially all methane and lighter components of the gas stream and an absorber bottoms stream;
• e. cooling the second separator overhead stream and sending the second separator overhead stream to the absorber column;
• f. heating and compressing the absorber overhead stream to produce a residue gas stream;
• and
• g. wherein an improvement comprises condensing at least a portion of the tower overhead stream thereby producing a first lean reflux stream and sending the first lean reflux stream to the absorber.

An apparatus for separating a gas stream containing methane, C2 and C3 components and heavier hydrocarbons into a volatile gas fraction containing substantially all of the methane and C2 components and a less volatile fraction containing a large portion of C3 components and heavier hydrocarbons, the apparatus comprising:

• a. a first exchanger for performing a process step selected from the group consisting of cooling a gas stream to partially condense at least a portion of the gas stream, preheating at least a portion of a first liquid stream, preheating at least a portion of an absorber bottoms stream, heating the absorber overhead stream, cooling and at least partially condensing the portion of the residue gas stream thereby producing a second lean reflux stream, and combinations thereof;
• b. a first separator for separating the gas stream into a first vapor stream and at least the first liquid stream;
• c. a distillation tower for receiving the portion of the first liquid stream as a lower tower feed stream and for receiving a portion of an absorber bottoms stream as a middle tower feed stream, the distillation tower producing a tower overhead stream containing mainly methane and C2 components and a tower bottoms stream containing a majority of the C3 components and heavier hydrocarbons;
• d. a second exchanger for performing a process step selected from the group consisting of cooling the tower overhead stream thereby producing a second vapor stream and a liquid hydrocarbon stream, cooling and condensing at least a portion of the second vapor stream thereby forming a first lean reflux stream, heating the absorber overhead stream, cooling and at least partially condensing the portion of the residue gas stream thereby producing a second lean reflux stream
• e. an expander for expanding the first vapor stream;
• f. an absorber column having at least one mass transfer zone for receiving the first vapor stream as a bottom absorber feed the stream the first lean reflux stream as an absorber top feed stream, and the second lean reflux stream, the absorber column thereby producing an absorber overhead stream containing essentially all methane, C2 and lighter components of the gas stream and the absorber bottoms stream;
• and
• g. a compressor for compressing the absorber overhead stream to produce a residue gas stream.