WO2022221154A1 - Système et procédé de production de gaz naturel liquéfié à l'aide de deux cycles de réfrigération distincts avec une machine à engrenage intégrée - Google Patents

Système et procédé de production de gaz naturel liquéfié à l'aide de deux cycles de réfrigération distincts avec une machine à engrenage intégrée Download PDF

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Publication number
WO2022221154A1
WO2022221154A1 PCT/US2022/024184 US2022024184W WO2022221154A1 WO 2022221154 A1 WO2022221154 A1 WO 2022221154A1 US 2022024184 W US2022024184 W US 2022024184W WO 2022221154 A1 WO2022221154 A1 WO 2022221154A1
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WIPO (PCT)
Prior art keywords
natural gas
stream
refrigerant
compression stage
turbine
Prior art date
Application number
PCT/US2022/024184
Other languages
English (en)
Inventor
Henry Edward Howard
Original Assignee
Praxair Technology, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Praxair Technology, Inc. filed Critical Praxair Technology, Inc.
Priority to CA3215185A priority Critical patent/CA3215185A1/fr
Priority to EP22720191.0A priority patent/EP4323704A1/fr
Priority to AU2022256372A priority patent/AU2022256372A1/en
Publication of WO2022221154A1 publication Critical patent/WO2022221154A1/fr

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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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0042—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by liquid expansion with extraction of work
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
    • F25J1/005—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by expansion of a gaseous refrigerant stream with extraction of work
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
    • F25J1/007—Primary atmospheric gases, mixtures thereof
    • F25J1/0072—Nitrogen
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0203—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle
    • F25J1/0208—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. with deep flash recycle loop
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
    • F25J1/0229—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock
    • F25J1/0231—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock for the working-up of the hydrocarbon feed, e.g. reinjection of heavier hydrocarbons into the liquefied 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
    • F25J1/0235—Heat exchange integration
    • F25J1/0242—Waste heat recovery, e.g. from heat of compression
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0285—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
    • F25J1/0288—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/029—Mechanically coupling of different refrigerant compressors in a cascade refrigeration system to a common driver
    • 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
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0294—Multiple compressor casings/strings in parallel, e.g. split arrangement
    • 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
    • F25J3/0247—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 4 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
    • F25J2200/02—Processes or apparatus using separation by rectification in a single 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
    • F25J2200/40—Features relating to the provision of boil-up in the bottom of a 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • 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
    • F25J2200/76—Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
    • 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
    • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
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    • 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
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/04—Recovery of liquid products
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    • 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
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/64—Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
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    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/20—Integrated compressor and process expander; Gear box arrangement; Multiple compressors on a common shaft
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    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression of the feed stream
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    • 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
    • F25J2270/14—External refrigeration with work-producing gas expansion loop
    • F25J2270/16—External refrigeration with work-producing gas expansion loop with mutliple gas expansion loops of the same refrigerant
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
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    • 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
    • F25J2270/42—Quasi-closed internal or closed external nitrogen refrigeration cycle
    • 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
    • F25J2270/88—Quasi-closed internal refrigeration or heat pump cycle, if not otherwise provided

Definitions

  • the present invention relates to production of liquefied natural gas (LNG), and more particularly, to a small or mid-scale liquefied natural gas production system that employs at least two distinct refrigeration cycles with a single integral gear machine.
  • LNG liquefied natural gas
  • Small-scale to mid-scale liquified natural gas opportunities include various energy applications such as oil well seeding or boil-off gas re-liquefaction, integrated CO2 extraction and natural gas liquefaction, utility sector applications such as peak shaving or emergency reserves, liquified natural gas supply at compressed natural gas filling stations, and transportation applications including marine transportation applications, off-road transportation applications, and even on-road fleet transportation uses.
  • Other small-scale or mid-scale liquified natural gas opportunities might include liquified natural gas production from biogas sources such as landfills, farms, industrial/municipal waste and wastewater operations.
  • Most conventional small-scale or mid-scale liquified natural gas production systems target a production of between 100 mtpd and 500 mtpd of liquified natural gas (e.g. small-scale plants) and higher, up to about 5000 mtpd of liquified natural gas for mid-scale plant operations.
  • Many of these liquefaction systems employ mechanical refrigeration or a nitrogen-based gas expansion refrigeration cycle to cool to the natural gas feed to subzero temperatures required for natural gas liquefaction.
  • Use of a nitrogen-based gas expansion refrigeration cycle is quickly becoming preferred technology due to its simplicity, safety and ease of operation and maintenance as well as good turn-down characteristics.
  • FIG. 1 A and IB A generic example of a conventional natural gas liquefaction system employing nitrogen-based gas expansion refrigeration cycle with dual expansion is schematically shown in Figs 1 A and IB.
  • Such systems have been in use for many years and are well known in the art.
  • Air Products and Chemicals, Inc. offers multiple variants of liquefaction systems including: a single expander and dual expander nitrogen recycle liquefaction system (AP-NTM); a single mixed refrigerant liquefaction systems (AP-SMRTM); and a methane expander based liquefaction systems (AP-ClTM).
  • A-NTM single expander and dual expander nitrogen recycle liquefaction system
  • AP-SMRTM single mixed refrigerant liquefaction systems
  • API-ClTM methane expander based liquefaction systems
  • Another natural gas liquefaction system that discloses a three turbine natural gas liquefaction cycle is disclosed in United States Patent No. 5,768,912 (Dubar), specifically employs
  • FIG. 1A shows a generalized schematic of the process flow diagram for a conventional natural gas liquefaction process known in the prior art
  • Fig. IB shows a generalized schematic illustration of a conventional integral gear machine with three pinions and coupled to two turbines;
  • FIG. 2A shows a schematic of the process flow diagram for the present system and method for liquefied natural gas production using two distinct refrigeration circuits and an integral gear machine with three pinions and three turbines;
  • FIG. 2B shows a schematic illustration of the integral gear machine with three pinions of Fig. 2A depicting the optimized pairing of turbomachines;
  • FIG. 3 A shows a more detailed schematic of the process flow diagram for an alternate embodiment of the present system and method for liquefied natural gas production using two distinct refrigeration circuits and a smaller frame integral gear machine with three pinions and including three turbines;
  • FIG. 3B shows a schematic illustration of the integral gear machine with three pinions of Fig. 3 A depicting the optimized pairing of turbomachines;
  • FIG. 4A shows a generalized schematic of the process flow diagram for the present system and method for liquefied natural gas production using two distinct refrigeration circuits and an integral gear machine with four pinions;
  • Fig. 4B shows a schematic illustration of the integral gear machine with four pinions of Fig. 4A depicting the optimized pairing of turbomachines
  • FIG. 5A shows a generalized schematic of the process flow diagram for the present system and method for liquefied natural gas production showing an alternative embodiment using two distinct refrigeration circuits and an integral gear machine with four pinions;
  • Fig. 5B shows a schematic illustration of the integral gear machine with four pinions of Fig. 5 A
  • Fig. 6A shows a generalized schematic of the process flow diagram for the present system and method for liquefied natural gas production using two distinct refrigeration circuits and an integral gear machine with three pinions and including two turbines;
  • Fig. 6B shows a schematic illustration of the integral gear machine with three pinions of Fig. 6A depicting the optimized pairing of turbomachines
  • FIG. 7A shows a generalized schematic of the process flow diagram for the present system and method for liquefied natural gas production using two distinct refrigeration circuits and an integral gear machine with three pinions and a separate high speed, high efficiency booster loaded turbine driving a natural gas compression stage;
  • Fig. 7B shows a schematic illustration of the integral gear machine with three pinions of Fig. 7A depicting the optimized pairing of turbomachines.
  • one of the distinct features of the present system and method to produce liquefied natural gas is that the liquefaction cycle that uses two distinct refrigeration circuits having compositionally different working fluids operating at different temperature levels. Details of this feature and the advantages it provides are discussed later in this application.
  • a conditioning circuit is employed that receives a natural gas containing feed stream, such as natural gas derived from a biogas source, and produces a purified, compressed natural gas stream at a pressure equal to or above the critical pressure of natural gas.
  • the preferred conditioning circuit includes a natural gas compression stage and optionally a phase separator and/or scrubbing column configured to remove impurities such as heavy hydrocarbons from the natural gas feed stream.
  • the scrubbing column may employ bypass vapor feed or indirect heating as a means of generating stripping vapor.
  • Indirect heating may be accomplished by cooling any one of the warm constituent fluids (e.g. compressed nitrogen or natural gas).
  • water and carbon dioxide may be also removed within the conditioning circuit, preferably upstream of the phase separator or scrubbing column through the use of an adsorbent-based temperature swing adsorption (TSA) unit.
  • TSA temperature swing adsorption
  • the natural gas feed stream may be cooled and then directed to a scrubbing column or phase separator configured to strip out impurities and produce an overhead stream of purified natural gas vapor and an impure bottoms liquid stream.
  • the overhead stream of purified natural gas vapor is then directed to a natural gas compression stage.
  • the present system and method details an approach where the natural gas feed stream is first pretreated by way of partial condensation, phase separation and/or rectification (i.e. scrubbing) before the natural gas feed stream is compressed.
  • Such pre-treatment operations naturally must be conducted at conditions that are substantially removed from the critical point of the natural gas mixture.
  • direct phase separation becomes impractical at pressures greater than about 75% of critical pressure. This fact creates a heat transfer inefficiency in conventional natural gas liquefaction plants.
  • the subsequent and direct liquefaction of a sub-critical gas stream results in a composite curve divergence near the dewpoint of the mixture.
  • the lower pressure of liquefaction generally results in a colder level of warm turbine operation.
  • the colder operation of the primary refrigeration turbine creates a meaningful penalty in terms of unit power consumption.
  • Yet another advantageous feature of the present system and method to produce liquefied natural gas is the use of a mixed service integral gear machine having at least three pinions and configured for driving the one or more recycle compression stages of the refrigeration circuits while also receiving work produced by at least one of the one or more high efficiency radial inflow turbines of the refrigeration circuits.
  • An important aspect of this advantageous feature relates to the pairings of turbomachinery on the different pinions in a manner that optimizes the performance of the present system and method. (00031)
  • the optimization of the turbomachinery starts with a consideration of turbine efficiency. Any given process definition (e.g.
  • optimal centrifugal compression stage efficiency can be attained for specific speed (Ns) values ranging from about 80 to about 130.
  • Ns specific speed
  • process definition dictates compression stage head and the associated turbine on the same pinion dictates rotational speed which in turn results in a specific speed.
  • the above calculation form one part of the overall process optimization. More specifically, the optimization is an iterative process involving process definition, turbomachine pairing based upon the above calculation and finally a consideration of the integral gear machine pinion power and overall input power limitations.
  • a conventional two-turbine nitrogen expansion-based liquefier can follow a more or less sequential design approach.
  • the present system and method was developed by approaching this problem from the standpoint that high efficiency liquefaction must be maintained (i.e. the process definition minimizes heat transfer irreversibility).
  • the use of a mixed service integral gear ‘bridge’ machine servicing dual refrigeration circuits, each having gas compression stages and gas expansion is critical to that end.
  • the turbomachinery is then defined so as to satisfy the conditions for optimal turbine performance (outlined above) as well as the constraints imparted by the need to consolidate compression-expansion service into a single integral gear ‘bridge’ machine.
  • the hardware constraints and limitations of the bridge machine are typically a function of bull gear and primary driver size.
  • the ‘bridge’ machine drivers pertinent for the present system and method spans the range of about 4 MW to 20 MW with associated maximum pinion speeds in the range of 20,000 to 50,000 rpm.
  • the maximum power imparted to any given pinion or any given turbine-compression stage pairing is generally limited to less than 50% and in some cases to about 35% (of the total bridge machine driver power).
  • Linde Inc. has also developed a portfolio of integral gear machines combining compression stages and high efficiency radial inflow expanders on a single machine having up to four pinions in what is referred to as an integral gear ‘bridge’ machine.
  • Linde’s bridge machines are conventionally used in hydrogen/syngas plants as well as air separation plants and typically come in different frame sizes.
  • the Linde ‘bridge’ machines can be used to operatively couple a plurality of radially inflow turbines and centrifugal compression stages.
  • the Linde ‘bridge’ machines come fully packaged or integrated with appropriate PLC controllers, control valves, safety valves, intercoolers, aftercoolers, oil system, etc.
  • the nitrogen expander in the disclosed Foglietta system and process also requires at least two stages of nitrogen compression requiring two additional pinions, for a minimum of four pinions on the integral gear machine in the disclosed Foglietta system. The process and would likely require use of a larger frame bull gear.
  • the Foglietta reference also discloses a closed loop hydrocarbon based refrigerant circuit. With the methane in the refrigeration loop, the expander exhausts at about 200 psia and -119°F and subsequently compressed in at least two or more stages of recompression up to 1400 psia. In contrast, the natural gas feed in Foglietta is delivered to the heat exchanger at about 900 psia, which admittedly is above the critical pressure but would require either a different machine to drive the compression stages of the natural gas feed or yet additional pinions on the single mixed service machine.
  • a natural gas vapor feed 200 at a nominal feed pressure of between about 20 bar(a) and 40 bar(a), and by way of example at a pressure of about 34 bar(a), is received and thereafter conditioned in a conditioning circuit to remove the heavy hydrocarbons and other impurities from the feed stream and pressurize the purified natural gas containing stream to a pressure equal to or above the critical pressure of natural gas.
  • the conditioning circuit preferably includes partial cooling of the natural gas feed 200A in the heat exchanger E4 and then purifying the cooled natural gas feed 201 and/or natural gas vapor stream 200B in a scrubbing column D1 to remove the heavy hydrocarbons and other impurities from the natural gas feed stream.
  • An overhead vapor stream 202 of purified natural gas exits the top of the scrubbing column D1 while a liquid bottoms stream 220 containing the heavy hydrocarbons and impurities is removed from the column.
  • the conditioning circuit may use a phase separator or both a phase separator and a scrubbing column to strip out the heavy hydrocarbons and other impurities from the natural gas feed stream.
  • the purification of the natural gas feed stream may also include removal of water and carbon dioxide via purification techniques well known in the art, such additional purification techniques preferably conducted upstream of the scrubbing column.
  • the purification techniques may include solvent based absorption systems, adsorptive purification as well as adsorptive gettering.
  • the purified natural gas vapor stream 202 is directed to a natural gas compression stage C3 operatively coupled to the integral gear machine (see Fig. 2B), preferably a Linde-type ‘bridge’ machine, where it is further compressed to a pressure equal to or above the critical pressure of natural gas, or above 46 bar(a).
  • the purified natural gas containing stream is further compressed to a pressure preferably between about 50 bar(a) and 80 bar(a), and more preferably to a pressure between about 60 bar(a) and 75 bar(a) and then cooled in aftercooler E3.
  • a first portion of the purified, further compressed super-critical natural gas stream 204 is directed to the cooling passages in the heat exchange ⁇ s) E4 where it is liquefied and subcooled via indirect heat exchange with two or more different refrigerant streams traversing the warming passages of the heat exchanger(s) E4.
  • a second portion of the purified, further compressed super-critical natural gas stream 210 is partially cooled in heat exchanger E4 and the partially cooled stream 211 is then expanded in a natural gas expander T3 to produce a natural gas exhaust stream 212 having a pressure less than or equal to the pressure of the natural gas feed stream 200.
  • the flow of second portion of the purified, compressed natural gas stream 210 is at least 2.0 times greater, and more preferably greater than 2.5 times greater, than the flow of first portion of the purified, compressed natural gas stream 204.
  • the natural gas exhaust stream 212 is directed to heat exchanger(s) E4 to cool the first portion of the purified, compressed natural gas stream 204 or other natural gas streams and is then recycled back to the natural gas compression stage together with the purified natural gas stream 202 as recycle stream 203.
  • the natural gas expander T3 is preferably a high speed, high efficiency radial inflow turbo-expander operatively coupled to the integral gear machine and configured with an expansion ratio approximately equal to or comparable to a compression ratio of the natural gas compression stage C3, which is typically below about 3.0.
  • the high speed, high efficiency radial inflow turbo-expander is also operatively coupled to the same pinion of the integral gear machine as the natural gas compression stage. Exactly what constitutes a high-speed expander very much depends on the size and capacity of the integral gear machine.
  • one skilled in the art would characterize a natural gas expander configured to operate at about 50,000 rpm when associated with a small integral gear machine frame (2 ⁇ 4 MW of absorbed power) as high speed whereas a natural gas expander configured to operate at about 30,000 rpm would be considered a high speed expander if associated with a large integral gear machine frame.
  • the first portion of the purified, further compressed super-critical natural gas stream 204 is cooled within the heat exchanger(s) E4 via indirect heat exchange against the combined recycle stream 202, 212, 203 as well as a primary nitrogen-based refrigerant streams 104, 105 and yields a subcooled liquified natural gas stream 205.
  • a portion of the subcooled liquified natural gas stream 209 may optionally be directed as a reflux stream to the scrubbing column as depicted in Figs. 2A, 4A, and 5A.
  • the remaining portion of subcooled liquified natural gas stream or the entire subcooled liquified natural gas stream is thereafter reduced in pressure via a valve 208 or a liquid turbine and phase separated in a phase separator D2 yielding a vapor stream 207 and liquid natural gas stream 206 constituting the liquefied natural gas product. It should be noted that in some instances it may be advantageous to employ a small portion of the liquefied natural gas as a recycle and reflux stream to the scrubbing column.
  • the primary refrigeration used in the illustrated liquefied natural gas production system that uses two distinct refrigeration circuits and an integral gear machine is preferably a nitrogen-based gas expansion refrigeration circuit.
  • the primary refrigerant 106, 107 is compressed in a plurality of serially arranged compression stages Cl, C2 with appropriate intercooling and aftercooling by aftercoolers El and E2 used to remove the heat of compression.
  • Such aftercooling may be accomplished by way of indirect contact with air, cooling water, chilled water or other refrigerating medium or combinations thereof.
  • the compressed primary refrigerant 100 is then further cooled in the heat exchange ⁇ s) E4 and directed to one or more turbines Tl, T2 configured to expand the compressed refrigerant streams to generate refrigeration.
  • the compressed primary refrigerant stream 100 is partially cooled in the heat exchanger E4 and the resulting cooled stream 101 is split.
  • a first portion of the cooled, compressed refrigerant stream 100 is directed to a warm turbine T1 while a second portion of the cooled, compressed primary refrigerant stream 102 is further cooled in the heat exchanger E4 to produce a cold stream portion 103 which is then directed to a cold turbine T2.
  • the cold turbine T2 is configured to expand the cold stream portion 103 of the primary refrigerant stream to produce a cold turbine exhaust stream 104 that is recycled back to the primary refrigerant compression stages as recycle stream 105 via one or more of the plurality of warming passages in the heat exchanger(s) E4.
  • the partially cooled first portion is a warm stream portion 110 of the compressed primary refrigerant stream that exits the heat exchanger E4 at a location and temperature that is warmer than the cold portion.
  • the warm stream portion 110 of the compressed refrigerant stream is then expanded in the warm turbine T1 to produce a warm turbine exhaust stream 111 that is also recycled to the one or more primary refrigerant compression stages as recycle stream 105, 106 via one or more of the plurality of warming passages in the heat exchanger(s).
  • the primary refrigerant streams may be warmed in independent passages and conceivably at independent pressures.
  • the warmed primary refrigerant streams could be directed to differing introduction points in the recycle compression train.
  • multi-pass brazed aluminum heat exchangers are capable of processing multiple stream wherein internal redistribution point may be configured.
  • the first portion of the conditioned natural gas stream may be subjected to redistribution into increasing numbers of passages as the fluid cools.
  • the cold turbine exhaust stream from the primary refrigeration circuit may be extracted at an intermediary point and combined with the warm turbine exhaust stream before or after partial warming within the multi-pass heat exchanger.
  • Both the warm turbine T1 and the cold turbine T2 as well as the serially arranged compression stages Cl and C2 are operatively coupled to the integral gear machine (See Figs 2B and 3B).
  • one of the primary refrigerant compression stages C2 and the cold turbine T2 are operatively coupled to the same pinion of the integral gear compressor machine.
  • the other primary refrigerant compression stage Cl and the warm turbine T1 are operatively coupled to the same pinion of the integral gear compressor machine.
  • Figs. 2B and 3B as well as Tables 1 A, IB, and 1C, embodiments of the three pinion and three turbine integral gear machine is schematically depicted in Figs. 2B and 3B showing a bull gear driven by a motor and comprised of a plurality of compression stages and turbines.
  • Tables 1 A, IB, and 1C the power consumption of the three pinion and three turbine integral gear machine has been normalized to the nominal liquefied natural gas product flow.
  • the bull gear accommodates three pinions and is sized to deliver roughly 280 metric tonnes per day (mptd) to about 320 mptd of liquefied natural gas.
  • the first pinion couples the bull gear to a first recycle compression stage and the warm turbine and absorbs about 35% of the input power to the integral gear machine.
  • the second pinion operatively couples the bull gear to the second recycle compression stage and the cold turbine and absorbs about 42% of the integral gear machine power.
  • the second pinion operates near the maximum fractional power for any given pinion relative to total integral gear machine absorbed power.
  • the warm turbine provides more than 4 times the power than that of the cold turbine, the warm turbine provides the largest source of refrigeration, and more particularly in this example about 4.5 times more power than the cold turbine.
  • the third pinion arrangement is dedicated to the natural gas service, namely the natural gas compression stage requiring and natural gas turbine expansion and absorbs the remaining 23% of the integral gear machine power.
  • Table IB compares the simulated performance of the baseline liquefied natural gas system and process generically depicted in Fig. 1 A with the three-pinion, three-turbine arrangement shown in Figs. 2A and 3 A using the above-described arrangement of the turbines and compression stages on the three pinions of the integral gear machine.
  • the energy usage per metric tonne of liquefied natural gas produced is about 10 percent lower.
  • any given machine frame size will likely deliver a liquefied natural gas product flow increase of about 12% to 15%.
  • the increased liquefied natural gas production rate resulting from the present system and method is dependent upon the maximum absorbable pinion power and the total potential power consumption of the integral gear machine.
  • This third primary refrigerant compression stage C2B is arranged in a parallel arrangement with the second primary refrigerant compression stage C2A where both the second and third primary refrigerant compression stages are disposed downstream of the first primary refrigerant compression stage Cl.
  • the third primary refrigerant compression stage C2B is also operatively coupled to the integral gear machine by a fourth pinion (see Fig. 4B).
  • Note reference numerals 400, 400A, 400B 401, 402, 403, 404, 405, 406, 407, 410, 411, 412, and 420 in Fig. 4A generally correspond to the same streams 300, 300A, 300B, 301,
  • the reference numerals 450, 451, 452, 453, 454, 455, 456, 457 and 460, in Fig. 4A generally correspond to the same streams 100, 101, 102, 103, 104, 105, 106,
  • the main difference is the presence of a third compression stage in the primary refrigeration circuit and a liquid turbine LT disposed downstream of the heat exchanger(s) configured to expand the subcooled, liquified natural gas stream 505 to produce stream 505B.
  • the third primary refrigerant compression stage C2B is arranged in a parallel arrangement with the second primary refrigerant compression stage C2Awhere both the second and third primary refrigerant compression stages C2A and C2B are disposed downstream of the first primary refrigerant compression stage Cl.
  • the third primary refrigerant compression stage C2B is operatively coupled to the integral gear machine by means of a fourth pinion (see Fig. 5B).
  • Note reference numerals 500, 500A, 500B 501, 502, 503, 504, 505, 506, 507, 510, 511, 512, and 520 in Fig. 5A generally correspond to the same streams 300, 300A, 300B, 301, 302, 303, 304, 305, 306, 307,
  • the reference numerals 550, 551, 552, 553, 554, 555, 556, 557 and 560, in Fig. 5A generally correspond to the same streams 100, 101, 102, 103, 104, 105, 106, 107 and 110, in Fig. 3A, respectively.
  • the cold turbine supplies only about 10% to 20% of the total refrigeration required for the liquefaction of supercritical natural gas.
  • the nitrogen-based warm turbine may provide in excess of 50% of the required refrigeration.
  • the associated pinion will consume a disproportionate amount of power relative to the pinion associated with the warm turbine.
  • the power associated with the cold turbine pinion compression stage
  • the additional pinion is to reduce the power consumed by the booster compression stage associated with the cold turbine.
  • the utilization of the integral gear machine can be maximized (from the perspective of total power consumption).
  • the quantity of liquefied natural gas produced from a fixed machine frame size is maximized. This is advantageous from the standpoint of capital utilization.
  • the degree to which the high pressure natural gas is subcooled at the cold end of the liquefaction heat exchanger will dictate the quantity of gas that is ultimately flashed off (i.e. that liquid which is converted to gas upon depressurization).
  • a simple isenthalpic expansion via a valve is less efficient than a dense phase expander or liquid turbine.
  • Natural gas that is not maintained as a liquid represents a loss or inefficiency of the liquefaction process.
  • the synergy afforded to the process by way of liquid turbine is accentuated. It has been found that the unit power consumption of the process can be further reduced by about 5% through the addition of a dense phase LNG expander. As noted, the total power draw of the integral gear machine is often the limiting aspect for small-scale and mid-scale liquefied natural gas production systems. Since the introduction of a dense phase LNG expander or liquid turbine reduces the net unit power consumption, additional throughput can be achieved given the same integral gear machine frame-driver size. A further, secondary benefit of the dense phase LNG expander or liquid turbine is the capture of mechanical power generated by the dense phase expansion by way of a generator. This secondary benefit can further reduce total cycle power consumption by about 0.5% to 1.0 %.
  • the first pinion couples the bull gear to first recycle compression stage and the warm turbine and preferably absorbs between about 0.10 and 0.2 kw*hr per kg of liquified natural gas, and in the example depicted in Table 2A about 0.125 kw*hr per kg of liquified natural gas while the fourth pinion arrangement is dedicated to the natural gas service and absorbs between about 0.05 and 0.20 kw*hr per kg of liquified natural gas, and in the example depicted in Table 2A about 0.072 kw*hr per kg of liquified natural gas which is roughly half of the power adsorbed by the first pinion.
  • the remaining power from the integral gear ‘bridge’ machine is to be adsorbed by the second pinion and third pinion.
  • the second pinion operatively couples the bull gear to the cold turbine and a first of two recycle split compression stages arranged in parallel while the third pinion operatively couples the bull gear to the second of two recycle split compression stages arranged in parallel.
  • Table 2B compares the simulated performance of the baseline liquefied natural gas system and process generically depicted in Fig. 1 A with the three-pinion, three-turbine arrangement shown in Figs. 4A and 5A using the above-described arrangement of the turbines and compression states on the three pinions of the integral gear machine.
  • the reduction in energy usage per metric tonne of liquefied natural gas produced in the embodiment depicted in Fig. 4A compared to the baseline configuration is 10.2% while the reduction in energy usage per metric tonne of liquefied natural gas produced in the embodiment depicted in Fig. 5A compared to the baseline configuration is 14.8% percent.
  • the embodiments of Figs. 4A and 5 A can also be effectively applied over a broad range of liquefied natural gas production rates from about 150 mtpd to over 1000 mtpd by simply changing the frame size of the integral gear ‘bridge’ machine and relative sizes of the associated turbomachinery.
  • frame sizes suitable for larger production rates, for example, greater than 300 mtpd of liquified natural gas capacity.
  • the integral gear machine is a ‘bridge’ type machine with a bull gear driven by motor is and a plurality of compression stages and turbines.
  • the bull gear size in this example is again the medium size machine and includes three pinions.
  • the first pinion arrangement couples the bull gear to first recycle compression stage.
  • the second pinion arrangement and third pinion arrangement are dedicated to the natural gas service.
  • the second pinion arrangement couples the bull gear to the first natural gas compression stage and the second natural gas compression stage for a net power requirement which is near the maximum power limit for any pinion arrangement on the integral gear machine.
  • the third pinion arrangement couples the bull gear to the third natural gas compression stage and the natural gas expansion.
  • the cold turbine is a booster loaded turbine that drives the third recycle compression stage. Note that the warm turbine provides about 2.8 times the work than that of the cold turbine suggesting the warm turbine is again providing the largest refrigeration source.
  • Tables 3A and 3B compare the simulated performance of the baseline or conventional liquefied natural gas system and process generically depicted in Fig. 1 with the three-pinion arrangement shown in Fig. 6A using an integral gear machine having a medium frame size. As seen therein, the energy usage per metric tonne of liquefied natural gas produced is about 13.8 percent lower.
  • FIG. 7 A The process flow diagram depicted in Fig. 7 A is in many regards similar to the process flow diagrams described above and for sake of brevity, much of the following discussion will focus on the differences in the process flow diagram depicted in Fig. 7A when compared to the process flow diagram depicted in Fig. 2A.
  • the main differences can be seen in Fig 7A and summarized as follows: (1) the nitrogen-based refrigerant compression are done using a series of compression stages, with all of the compression stages operatively coupled to the integral gear machine via the three pinions, as detailed in Fig.
  • the integral gear machine includes a bull gear driven by a motor and includes a plurality of compression stages and turbines/expanders coupled thereto.
  • the bull gear size in this example is again a medium size and includes three pinions.
  • the first pinion couples the bull gear to first recycle compression stage (CB1) and the cold turbine (CT) while the second pinion operatively couples the bull gear to the second recycle compression stage (CB2) and the warm turbine (WT2).
  • the third pinion arrangement operatively couples the bull gear to the third recycle compression stage (CB3).
  • the natural gas compression stage is driven by an auxiliary booster loaded warm turbine (WT1) and drives a natural gas compression stage (WB3).
  • Tables 4A and 4B also compares the simulated performance of the baseline or conventional liquefied natural gas system and process generically depicted in Fig. 1 with the three-pinion, three-turbine arrangement shown in Fig. 7A using an integral gear machine having a medium frame size.
  • the energy usage per metric tonne of liquefied natural gas produced is about 11.7% lower but generally produces more liquefied natural gas product than the baseline system in a comparable frame size.
  • the relative power savings associated with this embodiment expressed as kw*hr per kg of liquified natural gas produced is partially offset by the additional capital costs associated with the high speed, booster loaded natural gas expander driving the natural gas compression stage.
  • a possible strategy to reduce the capital costs for the present system and method involves standardizing a portion of the integral gear machine.
  • many of the embodiments can be modified to standardize the first and second pinion arrangements of integral gear machine while allowing customization of the third and optionally fourth pinion arrangements.
  • dedicating the first and second pinions of integral gear machine to adsorb the energy on each pinion required for the base refrigeration circuit, namely the nitrogen-based gas expansion refrigeration one can design an LNG platform and potentially reduce the capital costs required for such solutions.
  • the design of the third (and optional fourth) pinion arrangements would be customizable to meet the natural gas refrigeration service requirements or auxiliary refrigeration requirements for any given application or customer.
  • the third and fourth pinion arrangements would also accommodate other liquefaction process customizations, such as distributing compression power.
  • Such platform customizations would foreseeably be tailored to specific liquefaction applications, the quality (e.g. rich or lean) and pressure of the natural gas feed stream, the availability of auxiliary refrigerants, etc.
  • the third and fourth pinion arrangements are preferably dedicated to natural gas compression and expansion and/or other warm level refrigeration (i.e. >-50°C).
  • this LNG platform approach using a mixed service integral gear machine provides more design flexibility and more options for liquefied natural gas production, particularly for small to medium-scale liquefied natural gas production applications.

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Abstract

L'invention concerne un système et un procédé de liquéfaction de gaz naturel à l'aide de deux circuits de réfrigération distincts ayant des fluides actifs à composition différente et fonctionnant à différents niveaux de température. Les turbomachines associées au système de liquéfaction sont entraînées par une seule machine à engrenage intégrale à trois ou quatre pignons avec des agencements d'appariement personnalisés. Le système et le procédé de liquéfaction de gaz naturel comprennent en outre le conditionnement d'un courant d'alimentation contenant du gaz naturel à basse pression pour produire un gaz purifié, de gaz naturel comprimé à une pression égale ou supérieure à la pression critique du gaz naturel et sensiblement exempt d'hydrocarbures lourds à liquéfier.
PCT/US2022/024184 2021-04-15 2022-04-11 Système et procédé de production de gaz naturel liquéfié à l'aide de deux cycles de réfrigération distincts avec une machine à engrenage intégrée WO2022221154A1 (fr)

Priority Applications (3)

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CA3215185A CA3215185A1 (fr) 2021-04-15 2022-04-11 Systeme et procede de production de gaz naturel liquefie a l'aide de deux cycles de refrigeration distincts avec une machine a engrenage integree
EP22720191.0A EP4323704A1 (fr) 2021-04-15 2022-04-11 Système et procédé de production de gaz naturel liquéfié à l'aide de deux cycles de réfrigération distincts avec une machine à engrenage intégrée
AU2022256372A AU2022256372A1 (en) 2021-04-15 2022-04-11 System and method to produce liquefied natural gas using two distinct refrigeration cycles with an integral gear machine

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US5768912A (en) 1994-04-05 1998-06-23 Dubar; Christopher Alfred Liquefaction process
US6412302B1 (en) 2001-03-06 2002-07-02 Abb Lummus Global, Inc. - Randall Division LNG production using dual independent expander refrigeration cycles
EP2336677A1 (fr) * 2009-12-15 2011-06-22 Siemens Aktiengesellschaft Système et procédé de réfrigération
US20210088275A1 (en) * 2019-09-19 2021-03-25 Exxonmobil Upstream Research Company Pretreatment and Pre-Cooling of Natural Gas by High Pressure Compression and Expansion

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US5768912A (en) 1994-04-05 1998-06-23 Dubar; Christopher Alfred Liquefaction process
US6412302B1 (en) 2001-03-06 2002-07-02 Abb Lummus Global, Inc. - Randall Division LNG production using dual independent expander refrigeration cycles
EP2336677A1 (fr) * 2009-12-15 2011-06-22 Siemens Aktiengesellschaft Système et procédé de réfrigération
US20210088275A1 (en) * 2019-09-19 2021-03-25 Exxonmobil Upstream Research Company Pretreatment and Pre-Cooling of Natural Gas by High Pressure Compression and Expansion

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