EP1508010B1 - Twin reflux process and configurations for improved natural gas liquids recovery - Google Patents

Twin reflux process and configurations for improved natural gas liquids recovery Download PDF

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Publication number
EP1508010B1
EP1508010B1 EP02731911A EP02731911A EP1508010B1 EP 1508010 B1 EP1508010 B1 EP 1508010B1 EP 02731911 A EP02731911 A EP 02731911A EP 02731911 A EP02731911 A EP 02731911A EP 1508010 B1 EP1508010 B1 EP 1508010B1
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absorber
distillation column
natural gas
reflux stream
pressure
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German (de)
English (en)
French (fr)
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EP1508010A4 (en
EP1508010A1 (en
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John Fluor Corporation MAK
Curt Fluor Corporation GRAHAM
Wayne Chengwen Fluor Corporation CHUNG
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Fluor Corp
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Fluor Corp
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0238—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 2 carbon atoms or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0242—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 3 carbon atoms or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/04—Processes or apparatus using separation by rectification in a dual pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/74—Refluxing the column with at least a part of the partially condensed overhead gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/78—Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/60—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being (a mixture of) hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/02—Control in general, load changes, different modes ("runs"), measurements

Definitions

  • the field of the invention is natural gas liquids (NGL) recovery.
  • NTL natural gas liquids
  • a feed gas stream under pressure is cooled by heat exchanger and as the gas cools, liquids condense from the cooled gas.
  • the liquids are then expanded and fractionated in a distillation column (e.g. , de-deethanizer or demethanizer) to separate residual components such as methane, nitrogen and other volatile gases as overhead vapor from the desired C 2 , C 3 and heavier components.
  • a distillation column e.g. , de-deethanizer or demethanizer
  • Rambo et al. describe in U.S. Pat. No. 5,890,378 a system in which the absorber is refluxed, in which the deethanizer condenser provides the reflux for both the absorber and the deethanizer while the cooling requirements are met using a turbo expander, and in which the absorber and the deethanizer operate at substantially the same pressure.
  • Rambo's configuration advantageously reduces capital cost for equipment associated with providing reflux for the absorption section and the de-deethanizer, propane recovery significantly decreases as the operating pressure in the absorber rises, especially at a pressure above 34,47 bar (500 psig) where separation of ethane from propane in the de-deethanizer becomes increasingly difficult.
  • Rambo's system is generally limited by the upper operating limit of the de-deethanizer pressure. Increasing of the absorber pressure while maintaining desirable propane recovery becomes difficult, if not impossible in Rambo's process configuration. Moreover, operating the absorber and deethanizer at a pressure at or below 34,47 bar (500 psig) typically necessitates higher residue gas recompression, thereby incurring relatively high operating cost.
  • Sorensen describes in U.S. Pat. No. 5,953,935 a plant configuration in which the absorber reflux is produced by compressing, cooling, and Joule-Thomson expansion of a slipstream of feed gas.
  • Sorensen's configuration generally provides an improved propane recovery with substantially no increase in plant residue compression horsepower, propane recovery significantly decreases as the operating pressure in the absorber rises, especially at a pressure above about 500 psig.
  • propane recovery using such known systems designed for propane recovery is normally limited to about 20% recovery.
  • Campbell In order to improve ethane recovery with a low CO 2 content in the ethane product, Campbell describes in U.S. Pat. No. 6,182,469 a tower reboiling scheme in which one or more tower liquid distillation streams from a point higher in the absorber are employed for stripping of undesirable components (e.g ., carbon dioxide in a demethanizer). Campbell's scheme typically requires over-stripping of the ethane product, and CO 2 removal is generally limited to about 6%. Moreover, additional CO 2 removal using Campbell's process will significantly reduce ethane recovery, and increase power consumption. Furthermore, and especially where the ethane product is used for chemical production, the product in Campbell's configuration typically requires further treatment to remove CO 2 to or below a level of 500 ppmv, which often requires substantial capital and operating expenditure.
  • undesirable components e.g ., carbon dioxide in a demethanizer
  • a turbo-expander is employed to provide the cooling of the feed gas in order to achieve a high propane or ethane recovery.
  • Exemplary configurations are described, for example, in U.S. Pat. No. 4,278,457 , and U.S. Pat. No. 4,854,955, to Campbell et al ., in U.S. Pat. No. 5,953,935 to McDermott et al ., in U.S. Pat. No. 6,244,070 to Elliott et al. , or in U.S. Pat. No. 5,890,377 to Foglietta . While such configurations may provide at least some advantages over other processes, they typically require changes in existing expanders when the plant is upgraded to higher throughputs. Moreover, in such configurations the liquids separated are fed to the demethanizer operating at cryogenic temperature.
  • WO-A-01 88447 which can be considered as the closest prior art, discloses in figure 5 a plant comprising a distillation column coupled to an absorber that receives a first reflux stream and that further receives a second reflux stream, the first reflux stream comprising a cooled lean overhead product from the distillation column and the second reflux stream comprising a cooled vapour portion of a natural gas feed that is reduced in pressure via a Joule Thomson valve and wherein the absorber is further configured to receive a liquid portion of the natural gas feed and a second vapour portion of the natural gas feed wherein the second portion is reduced in pressure via a turbo expander.
  • the present invention concerns a plant and a method according to claims 1 and 6 , respectively.
  • the absorber receives a liquid portion of the natural gas feed and a second vapor portion of the natural gas feed wherein the second portion is reduced in pressure via a turbo expander.
  • the absorber further produces a bottom product that cools the first and second reflux streams, and at least a portion of the bottom product may be fed into the distillation column.
  • Contemplated absorber overhead products are employed to cool the first and second reflux streams, and further cool a vapor portion of the natural gas feed. They may further cool the natural gas feed.
  • Preferred devices other than the turbo expander include a Joule-Thomson valve, and preferred distillation columns comprise a demethanizer or deethanizer.
  • the first lean reflux stream may be fed into the absorber as a liquid feed, wherein the distillation column comprises a demethanizer.
  • Preferred configurations are especially useful in a retrofit of an existing NGL plant to improve throughput while increasing the C 2 and C 3 recovery.
  • Figure 1 is a schematic diagram of an exemplary plant configuration according to the inventive subject matter.
  • high NGL recovery e.g. , at least 99%C 3 and at least 90%C 2
  • contemplated configurations will advantageously allow change in component recovery by changing process temperature and changing the feed point of one of the reflux streams into the absorber.
  • the plant configurations include an absorber that receives a first reflux stream and a second reflux stream, the first reflux stream comprising a cooled lean overhead product from a distillation column, and the second reflux stream comprising a cooled vapor portion of a natural gas feed that is reduced in pressure via a device other than a turbo expander.
  • a plant 100 comprises an absorber 110 that is fluidly coupled to a distillation column 140.
  • a natural gas feed 101 with a typical composition by mole percent of 85% C1, 6% C2, 3% C3, 3% C4+ and 3% CO2 a 32,22°C (90°F) and 648,88°C (1200) psig, is cooled in a heat exchanger 124 to cooled natural gas feed 102 at 31,66°C (25°F).
  • the condensed liquid portion of the cooled natural gas feed is separated in the separator 170 to form cooled liquid stream 103, while the cooled vapor portion 106 is further cooled via heat exchanger 122 to typically -37,22°C (35°F) to form further cooled vapor portion 107.
  • the liquid from the further cooled vapor portion 107 are separated from the vapors in separator 180, which produces further cooled vapor stream 108 and further cooled liquid stream 104.
  • the cooled liquid stream 103 and the further cooled liquid stream 104 are combined to form combined cooled liquid stream 105 at typically -59,44°C (-75°F) and 28,26 bar (410 psig), which is subsequently introduced as feed to the lower section of absorber 110.
  • the typical temperature ranges are illustrated as follows.
  • the further cooled vapor stream 108 is split into a first portion that is expanded in a turbo-expander 150 to form expanded stream 109, typically at -73,33°C (-100°F) to -81,66°C (-115° F), which is introduced into the absorber 110, and a second portion stream 130 is still further cooled in heat exchanger 120 to typically -67,77°C (-90°F) to -92,77°C (-135°F) and reduced in pressure via a Joule-Thomson valve 132 before entering the absorber 110 as a reflux stream, typically at -87,22°C (-125°F) to -95,55°C (-140°F).
  • Absorber 110 forms an overhead product 114, typically at -73,33°C (-100°F) to -92,77°C (135°), which is employed as a refrigerant in heat exchangers 120, 122, and 124 before a residue gas re-compressor 160 recompresses the residue gas.
  • the overhead product cools the first and second absorber reflux, 146 and 130, respectively, and is further employed as refrigerant to cool at least one of the vapor portions of the natural gas feed from the first and second separators.
  • the absorber 110 further produces bottoms product 112, typically at -73,33°C (-100°F) to -81,66°C (-115°F), which also acts as a refrigerant in heat exchanger 120 to further cool the first and second reflux streams 146 and 130.
  • the heated bottoms product 112, typically at -53,88°C (-65°F) to -65°C (-85°F) is then introduced into the distillation column 140, which separates the desired bottom product 142 (e.g. , propane, or ethane/propane) from lean residue gas 144.
  • desired bottom product 142 e.g. , propane, or ethane/propane
  • the lean residue gas 144 may then be cooled with a cooler before entering separator 190 that produces a distillation column reflux 148 and the lean absorber reflux stream 146, typically at -65°C (-85°F) to -81,66°C (-115°F).
  • contemplated configurations may be employed for high propane recovery as well as for high ethane recovery.
  • the cooler for distillation column overhead stream 144 is typically not required and can be bypassed, and the lean absorber reflux stream 146 will be introduced into the bottom of absorber 110 as a bottom feed stream as indicated by the dashed lines in Figure 1.
  • suitable feed gas streams it is contemplated that various feed gas streams are appropriate, and especially suitable feed gas streams may include various hydrocarbons of different molecular weight. With respect to the molecular weight of contemplated hydrocarbons, it is generally preferred that the feed gas stream predominantly includes C 1 -C 6 hydrocarbons.
  • suitable feed gas streams may additionally comprise acid gases (e.g. , carbon dioxide, hydrogen sulfide) and other gaseous components (e.g. , hydrogen). Consequently, particularly preferred feed gas streams are natural gas and natural gas liquids.
  • the feed gas streams cooled to condense at least a portion of the heavier components in the feed gas stream and in especially preferred configurations, the feed gas stream is cooled, separated into a vapor portion and a liquid portion, wherein the vapor portion is further cooled and separated into a second vapor portion and second liquid portion.
  • the separated liquids from the feed gas stream are (combined and) fed into the absorber.
  • the second vapor portion is split into a bypass stream and a turbo-expander stream, wherein the turbo-expander stream is fed into a turbo-expander and subsequently into the absorber, and wherein the bypass stream is (a) further cooled, using the refrigerant content of the absorber overhead product and the absorber bottom product, and then (b) let down in pressure via a device other than a turbo-expander before entering the upper section of absorber as a first reflux stream.
  • suitable devices include Joule-Thomson valves, however, all other known configurations and methods to reduce pressure are also considered suitable for use herein.
  • suitable alternative devices might include power recovery turbines and expansion nozzle devices.
  • the absorber overhead and bottom products are employed as refrigerant in a heat exchanger, wherein the heat exchanger provides cooling for the first and second reflux streams.
  • the absorber overhead product may act as a refrigerant in at least one, and preferably at least two additional heat exchangers, wherein the absorber overhead product cools the separated vapor portion of the feed gas and the feed gas stream before recompression to residue gas pressure.
  • the absorber bottom product is employed (preferably in the same heat exchanger) as a refrigerant to cool at least one of the first and second reflux streams before entering the distillation column as column feed.
  • Suitable absorbers may vary depending on the particular configurations, however, it is generally preferred that the absorber is a tray or packed bed type absorber.
  • the absorber bottom product is separated in a distillation column to form the desired bottom product (e.g. , C 2 /C 3 or, C 3 and C 4 + ). Consequently, depending on the desired bottom product, appropriate distillation columns include a demethanizer and a deethanizer. Where the desired bottom product is C 3 and C 4 + , it is contemplated that the distillation column overhead product is cooled in a cooler ( e.g. , using external refrigerant) and separated into a distillation column reflux portion and a vapor portion. Thus, it should be especially appreciated that the vapor overhead product from the distillation column is employed as first reflux stream for the absorber, wherein the first reflux stream is a lean reflux stream that is fed to the top tray of the absorber
  • the distillation column overhead product bypasses the cooler and, after separation in a separator, the liquid portion is employed as reflux for the distillation column while the vapor portion is employed as a bottom feed to the absorber.
  • the vapor overhead product from the distillation column is recycled back to the absorber for re-absorption of the C 2 plus components resulting in high ethane recovery.
  • the cooling requirements for the absorber are at least partially provided by the reflux streams (via cooling by absorber bottom and overhead products), and that the C 2 /C 3 recovery significantly improves by employing a first and a second reflux stream.
  • the C 2 recovery it is contemplated that such configurations provide at least 85%, more typically at least 88%, and most typically at least 90% recovery, while it is contemplated that C 3 recovery will be at least 95%, more typically at least 98%, and most typically at least 99%.
  • contemplated configurations are especially advantageous as an upgrade into an existing natural gas treating plant, wherein the capacity of the upgraded plant significantly increases without rewheeling the expander or replacing the absorber and/or distillation column. Additional equipment for such upgrades will typically include a heat exchanger and piping.
  • a method of increasing throughput in a natural gas recovery plant having an absorber and a distillation column will include a step in which a first reflux stream is provided to the absorber, wherein the first reflux stream comprises an overhead product from the distillation column.
  • a bypass is provided upstream of a turbo expander, wherein the bypass receives a vapor portion of a cooled natural gas liquid and provides the vapor portion to the absorber.
  • pressure of the vapor portion is reduced before the vapor portion enters the absorber as a second reflux stream, and in yet another step, a heat exchanger is provided that cools at least one of the first and second reflux streams using at least one of an absorber bottom product and an absorber overhead product.
  • the method includes a step in which a second vapor portion of the cooled natural gas liquid is expanded in a turbo expander and fed into the absorber, wherein a liquid portion of the cooled natural gas liquid is fed into the absorber.
  • the absorber overhead product may further cool the natural gas liquid and/or a vapor portion of the natural gas liquid, and the reflux stream may be fed into the absorber as a liquid or vapor/liquid feed, wherein the distillation column comprises a deethanizer.
  • the distillation column can also perform as a demethanizer when liquid ethane product is preferred.
  • a method of operating a plant includes a step in which an absorber and a distillation column are provided.
  • a cooled lean overhead product from the distillation column is fed to the absorber as a first reflux stream, and the pressure of a cooled vapor portion of a natural gas feed is reduced via a device other than a turbo expander.
  • the cooled vapor portion that is reduced in pressure is fed to the absorber as a second reflux stream.
  • the method includes a step in a liquid portion of the natural gas feed and a second vapor portion of the natural gas feed are fed into the absorber, wherein the second portion is reduced in pressure via a turbo expander.
  • a heat exchanger in which a bottom product and an overhead product of the absorber cool the first and second reflux streams. Furthermore, it is generally preferred that in such methods at least part of the bottom product is fed from the absorber into the distillation column, and that the device other than the turbo expander comprises a Joule-Thomson valve. Furthermore, where C 2 recovery is desired, it is contemplated that the lean reflux stream is provided by the separator vapor and fed into the absorber as a liquid feed and the vapor overhead stream from the distillation column is fed to the bottom of the absorber, wherein the distillation column comprises a demethanizer.
  • contemplated configurations with the absorber operating at a higher pressure than the downstream distillation column prove especially advantageous.
  • Such contemplated configuration would require a compressor that raises the pressure of the vapor stream from the distillation column to a pressure required by the absorber.
  • Such a dual pressure column configuration should be recognized to provide significant overall compression horsepower savings as the compression horsepower required by the residue gas re-compressor is greatly reduced.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
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  • Oil, Petroleum & Natural Gas (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Gas Separation By Absorption (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
  • Industrial Gases (AREA)
EP02731911A 2002-05-20 2002-05-20 Twin reflux process and configurations for improved natural gas liquids recovery Expired - Lifetime EP1508010B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US2002/016311 WO2003100334A1 (en) 2002-05-20 2002-05-20 Twin reflux process and configurations for improved natural gas liquids recovery

Publications (3)

Publication Number Publication Date
EP1508010A1 EP1508010A1 (en) 2005-02-23
EP1508010A4 EP1508010A4 (en) 2006-01-11
EP1508010B1 true EP1508010B1 (en) 2008-01-09

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EP02731911A Expired - Lifetime EP1508010B1 (en) 2002-05-20 2002-05-20 Twin reflux process and configurations for improved natural gas liquids recovery

Country Status (9)

Country Link
EP (1) EP1508010B1 (ru)
AT (1) ATE383557T1 (ru)
AU (1) AU2002303849B2 (ru)
CA (1) CA2484085C (ru)
DE (1) DE60224585T2 (ru)
EA (1) EA007771B1 (ru)
MX (1) MXPA04011219A (ru)
NO (1) NO20044580L (ru)
WO (1) WO2003100334A1 (ru)

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US11112175B2 (en) 2017-10-20 2021-09-07 Fluor Technologies Corporation Phase implementation of natural gas liquid recovery plants

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FR2879729B1 (fr) * 2004-12-22 2008-11-21 Technip France Sa Procede et installation de production de gaz traite, d'une coupe riche en hydrocarbures en c3+ et d'un courant riche en ethane
AU2007269613B2 (en) * 2006-07-06 2010-07-22 Fluor Technologies Corporation Propane recovery methods and configurations
BRPI0717384A2 (pt) * 2006-10-24 2013-10-15 Shell Int Research Método e aparelho para o tratamento de uma corrente de hidrocarbonetos
US10451344B2 (en) 2010-12-23 2019-10-22 Fluor Technologies Corporation Ethane recovery and ethane rejection methods and configurations
RU2528689C1 (ru) * 2013-05-06 2014-09-20 Государственное унитарное предприятие "Институт нефтехимпереработки Республики Башкортостан" (ГУП ИНХП РБ) Способ разделения газа
US10006701B2 (en) 2016-01-05 2018-06-26 Fluor Technologies Corporation Ethane recovery or ethane rejection operation
US10330382B2 (en) 2016-05-18 2019-06-25 Fluor Technologies Corporation Systems and methods for LNG production with propane and ethane recovery
US11725879B2 (en) 2016-09-09 2023-08-15 Fluor Technologies Corporation Methods and configuration for retrofitting NGL plant for high ethane recovery
FR3072162B1 (fr) * 2017-10-10 2020-06-19 L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude <P>PROCEDE DE RECUPERATION DE PROPANE ET D'UNE QUANTITE AJUSTABLE D'ETHANE A PARTIR DE GAZ NATUREL</P>

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Also Published As

Publication number Publication date
AU2002303849B2 (en) 2006-05-25
EP1508010A4 (en) 2006-01-11
EA200401400A1 (ru) 2005-06-30
CA2484085C (en) 2008-08-05
AU2002303849A1 (en) 2003-12-12
CA2484085A1 (en) 2003-12-04
EA007771B1 (ru) 2007-02-27
DE60224585T2 (de) 2009-04-02
WO2003100334A1 (en) 2003-12-04
DE60224585D1 (de) 2008-02-21
MXPA04011219A (es) 2005-02-14
EP1508010A1 (en) 2005-02-23
NO20044580L (no) 2004-12-16
ATE383557T1 (de) 2008-01-15

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