WO2022099233A1 - Procédés et systèmes de liquéfaction de gaz naturel comprenant une compression, une détente et un recyclage de charge - Google Patents

Procédés et systèmes de liquéfaction de gaz naturel comprenant une compression, une détente et un recyclage de charge Download PDF

Info

Publication number
WO2022099233A1
WO2022099233A1 PCT/US2021/071526 US2021071526W WO2022099233A1 WO 2022099233 A1 WO2022099233 A1 WO 2022099233A1 US 2021071526 W US2021071526 W US 2021071526W WO 2022099233 A1 WO2022099233 A1 WO 2022099233A1
Authority
WO
WIPO (PCT)
Prior art keywords
compressor
natural gas
heat exchange
gas stream
stream
Prior art date
Application number
PCT/US2021/071526
Other languages
English (en)
Inventor
Yijun Liu
Douglas K. Priedeman
Fritz Pierre, Jr.
Original Assignee
Exxonmobil Upstream Research Company
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.)
Filing date
Publication date
Application filed by Exxonmobil Upstream Research Company filed Critical Exxonmobil Upstream Research Company
Publication of WO2022099233A1 publication Critical patent/WO2022099233A1/fr

Links

Classifications

    • 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"
    • F25J1/0035—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 gas 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
    • F25J1/0032—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"
    • F25J1/0035—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 gas expansion with extraction of work
    • F25J1/0037—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 gas expansion with extraction of work of a return 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
    • 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
    • F25J1/0211—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 multi-component refrigerant [MCR] fluid in a closed vapor compression cycle
    • F25J1/0219—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 multi-component refrigerant [MCR] fluid in a closed vapor compression cycle in combination with an internal quasi-closed refrigeration loop, e.g. using a 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
    • F25J1/0221—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 the cold stored in an external cryogenic component in an open refrigeration loop
    • F25J1/0224—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 the cold stored in an external cryogenic component in an open refrigeration loop in combination with an internal quasi-closed refrigeration 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
    • F25J1/0243—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.
    • F25J1/0281—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc. characterised by the type of prime driver, e.g. hot gas expander
    • F25J1/0282—Steam turbine as the prime mechanical 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.
    • F25J1/0281—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc. characterised by the type of prime driver, e.g. hot gas expander
    • F25J1/0283—Gas turbine as the prime mechanical 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.
    • F25J1/0285—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.
    • F25J1/0289—Use of different types of prime drivers of at least two refrigerant compressors in a cascade refrigeration 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
    • 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
    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • 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
    • F25J2240/80—Hot exhaust gas turbine combustion engine
    • F25J2240/82—Hot exhaust gas turbine combustion engine with waste heat recovery, e.g. in a combined cycle, i.e. for generating steam used in a Rankine 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
    • 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
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
    • F25J2270/06—Internal refrigeration with work-producing gas expansion loop with multiple gas expansion loops

Definitions

  • the present disclosure relates to natural gas liquefaction processes.
  • Natural gas a hydrocarbon resource comprising predominantly methane, has become an increasingly important energy source in recent years. Natural gas is often processed into liquefied natural gas (LNG) to facilitate transport from production fields to a locale having a strong commercial or consumer need for natural gas.
  • LNG liquefied natural gas
  • Conventional LNG processing techniques may include: (a) initial treatments of the natural gas to remove contaminants such as water, sulfur compounds and carbon dioxide; (b) separation of heavier hydrocarbon gases (e.g., propane, butane, pentane, and the like), such as through self-refrigeration, external refrigeration, lean oil, and the like; (c) refrigeration of the natural gas, such as through external refrigeration to form LNG at near atmospheric pressure and about -160°C; (d) transportation of the LNG to a market location in specially designed ships or tankers; and (e) conversion of the LNG into pressurized natural gas at a site for processing or distribution to consumers.
  • Refrigeration to produce LNG may employ large refrigeration compressors, often powered by gas turbine drivers that may emit substantial carbon and other emissions.
  • Nitrogen or other cryogenic liquids may alternately be employed to promote formation of LNG, as described in U.S. Patents 3,878,689 and 5,139,547.
  • Conversion of LNG into pressurized natural gas following delivery to a desired location may include repressurizing the LNG to a specified pressure using cryogenic pumps and then vaporizing the LNG through heat exchange with an intermediary fluid or combusting a portion of the natural gas to produce heat.
  • One approach for facilitating production of LNG is to expand the natural gas prior to liquefaction, thereby cooling the natural gas below its initial temperature and lessening the refrigeration burden for promoting liquefaction. Expansion follows processing steps a) and b) from above and initial compression thereafter to a pressure well above that obtained after such processing steps. Ambient cooling of the compressed natural gas places the natural gas in a lower entropic state better suited for undergoing subsequent liquefaction.
  • U.S. Patent 6,412,302 describes an expander-based process in which two independent closed refrigeration loops are used to promote natural gas cooling during production of LNG.
  • U.S. Patent 8,616,021 describes an expander-based process in which a natural gas feed is employed as a refrigerant in a closed refrigeration loop.
  • a related LNG production technique employs a compression-expansion cycle prior to liquefaction, as described in U.S. Patent Application Publication 2017/0167787.
  • compression-expansion liquefaction techniques may be restricted further by pressure limitations of the metal grades commonly used for piping, turbines, and other parts commonly employed during compression of a natural gas stream. These limitations may further constrain the turbine power that may be applied during compression, again limiting throughput.
  • more robust metal grades may be utilized during compression-expansion techniques for producing LNG, doing so can significantly add to LNG production costs.
  • such LNG production techniques may be excessively influenced by outside environmental factors, particularly temperature, especially in terms of the turbine power needed to promote initial compression.
  • the turbine power for promoting initial expansion may not be easily modified.
  • Other factors that may not be easily accounted for in such conventional compression-expansion processes include, for example, pressure variation of an incoming natural gas stream, and variation in equipment operating conditions (e.g. , due to process upsets and sub-optimal operation resulting from unclean conditions).
  • the present disclosure provides pre-boost natural gas liquefaction methods comprising: providing a natural gas stream at a first temperature and a first pressure to a first compressor, optionally in series fluid communication with a second compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor and optionally the second compressor, thereby forming a compressed natural gas stream having a second temperature; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the first compressor and the second compressor, if present, thereby forming a cooled, compressed natural gas stream having a third pressure and a third temperature lower than the second temperature; performing a second heat exchange upon the cooled, compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fourth pressure and a fourth temperature lower than the third temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using a first expander from about the fourth pressure to a fifth pressure lower than the fourth pressure,
  • pre-boost natural gas liquefaction systems may comprise: a natural gas feed connected to a first compressor and a second compressor that are fluidly coupled in series; an optional first heat exchange location fluidly coupled to an output of the second compressor; a second heat exchange location downstream from the second compressor and fluidly coupled to an output of the first heat exchange location, if present; a first expander fluidly coupled to an output of the second heat exchange location; and an output line from the first expander that is subdivided into a main line and recycle line; wherein the recycle line is in thermal communication with the second heat exchange location, and the recycle line is in fluid communication with the natural gas feed.
  • the present disclosure provides post-boost natural gas liquefaction methods comprising: providing a natural gas stream at a first temperature and first pressure to a first compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor, thereby forming a compressed natural gas stream having a second temperature; optionally compressing the compressed natural gas stream to a third pressure higher than the second pressure using a second compressor in fluid communication with the first compressor, the compressed natural gas stream having a third temperature after being compressed to the third pressure; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the second compressor, thereby forming a cooled, compressed natural gas stream having a fourth pressure and a fourth temperature lower than the third temperature; performing a second heat exchange upon the compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fifth pressure and a fifth temperature lower than the fourth temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using an expand
  • post-boost natural gas liquefaction systems may comprise: a natural gas feed connected to a first compressor; a second compressor fluidly coupled to an output of the first compressor; an optional first heat exchange location fluidly coupled to an output of the second compressor; a second heat exchange location downstream from the second compressor and fluidly coupled to an output of the first heat exchange location, if present; an expander fluidly coupled to an output of the second heat exchange location; and an output line from the expander that is subdivided into a main line and recycle line; wherein the recycle line is in thermal communication with the second heat exchange location, and the recycle line is in fluid communication with a location upstream from the first heat exchange location.
  • FIG. 1 A is a diagram of aportion of afirst configuration of anatural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas.
  • FIG. IB is a diagram of a portion of a second configuration of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas.
  • FIG. 2 A is a diagram of a portion of a first configuration of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using an expander.
  • FIG. 2B is a diagram of a portion of a second configuration of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using an expander, in which the natural gas feed compressor is driven by steam and integrated via a Heat Recovery Steam Generator (HRSG) with a gas turbine used to drive compressor(s) in a liquefaction process.
  • HRSG Heat Recovery Steam Generator
  • FIG. 3 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using a Joule-Thompson valve.
  • FIG. 4 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been formed and further expanded using a compander.
  • FIG. 5 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas, in which initial compression and expansion are conducted using a compressor-expander.
  • the present disclosure relates to natural gas liquefaction methods and systems and, more particularly, natural gas liquefaction methods and systems featuring compression, expansion, and recycling of a portion of a natural gas stream.
  • Liquefied natural gas is a convenient form for transportation of natural gas from a production location to a distribution or processing location.
  • Natural gas liquefaction processes usually utilize large-scale refrigeration and/or heat exchange with one or more cryogenic liquids to lower the natural gas below its boiling point. Since large volumes of natural gas are usually processed into LNG, it may be desirable to lessen the heat exchange burden during liquefaction to improve energy efficiency. Even incremental improvements in energy efficiency and throughput may afford significant cost savings for supplying LNG.
  • Throughput may be improved by incorporating auxiliary power (e.g., from a gas or electric turbine, or through supplying waste heat from refrigeration) during initial compression of a natural gas stream, wherein the auxiliary power is separate from refrigerant power subsequently employed to promote liquefaction.
  • auxiliary power e.g., from a gas or electric turbine, or through supplying waste heat from refrigeration
  • natural gas liquefaction processes featuring compression or compression-expansion of a natural gas stream prior to liquefaction have been developed.
  • the main cryogenic heat exchanger (MCHX) for promoting liquefaction following expansion may have a maximum use pressure in the range of about 110 bar to about 150 bar, which also may limit throughput. These factors collectively decrease the amount of natural gas available to undergo liquefaction and lead to a potentially large temperature differential that must be overcome to promote liquefaction following compression and expansion (i.e., during a refrigerant cycle to form the LNG). Although higher pressures may be achieved by employing materials with higher pressure tolerances, doing so may significantly increase the cost of forming LNG.
  • natural gas liquefaction processes may be heavily influenced by outside environmental factors (e.g, temperature, natural gas stream pressure, and the like), which may result in highly variable processing conditions depending on season. These factors may also impact the available auxiliary power that may be supplied during compression or compression-expansion processing of a natural gas stream.
  • outside environmental factors e.g, temperature, natural gas stream pressure, and the like
  • auxiliary power may be supplied during compression or compression-expansion processing of a natural gas stream.
  • compression or compression-expansion liquefaction processes may afford some process flexibility to account for outside environmental factors, there are still constraints on the initial compression that may be limiting.
  • a recycle stream of expanded natural gas may be returned upstream to promote indirect heat exchange of an incoming natural gas stream immediately prior to expansion and/or at one or more intermediate stages of expansion.
  • the recycle stream of expanded natural gas may be returned upstream from an expander, either being provided directly to an incoming natural gas stream or to one or more compressor stages in order to reject heat to the environment.
  • recycling of a portion of an expanded natural gas stream may promote further cooling of an incoming natural gas stream and lower downstream heat exchange burdens, particularly during liquefaction.
  • higher throughput may be achieved prior to reaching a pressure ceiling of materials in turbines and piping, thereby avoiding use of more expensive material grades.
  • disclosure herein allows greater and more efficient operational flexibility to be realized by redistributing power from expansion (refrigeration cycle) into the compression stages of natural gas processing. By controlling the temperature of the incoming natural gas stream, the amount of power applied during compression may allow the production rate of LNG to be altered dynamically.
  • the recycle stream having already been expanded, has a lower temperature than the compressed natural gas stream from which it was produced.
  • the recycle stream may undergo heat exchange with the compressed natural gas stream just prior to expansion to lower the temperature of the compressed natural gas stream. Expansion of the compressed natural gas stream from a lower starting temperature accordingly affords a lower temperature of the natural gas following expansion.
  • the main stream of natural gas diverted toward forming LNG may then undergo liquefaction more readily, since it is at a lower entropic state than is the incoming natural gas stream.
  • the lower entropic state of the main stream used for forming LNG may arise as a direct consequence of its rejection of entropy made possible by recycling of a portion of the expanded natural gas and the transfer of heat between the main stream and the recycle stream.
  • the methods and systems described herein may further employ an optional secondary expansion of the recycle stream to allow for a greater temperature differential between the main stream and the recycle stream, thus promoting additional heat exchange with the compressed natural gas stream before being returned further upstream.
  • the methods and systems described herein may convert an incoming natural gas stream into a lower entropic state capable of undergoing liquefaction more readily through input of auxiliary power according to the disclosure herein, specifically by providing, in an efficient manner, natural gas having a combination of a temperature that is as low as possible and a pressure that is as high as possible.
  • considerable flexibility may be realized for cooling the incoming natural gas stream, particularly to compensate for seasonal variation in environmental temperatures and other process variables.
  • the extent of cooling of the incoming natural gas stream may be regulated by changing the flow rate of the recycle stream and/or cooling the recycle stream through further expansion.
  • the temperature of the recycle stream may be further varied by the amount of heat exchange that takes place with the compressed natural gas stream (e.g., by varying the flow rate of the recycle stream), thereby facilitating additional temperature regulation of the incoming natural gas stream to improve processing throughput.
  • natural gas refers to a multi-component gas obtained from a crude oil well (associated gas) or from a subterranean gas-bearing formation (nonassociated gas).
  • the composition and pressure of natural gas can vary significantly.
  • a typical natural gas stream contains methane as a significant component, sometimes as a primary component.
  • a natural gas stream may also contain ethane, higher molecular weight hydrocarbons (e.g., propane), and/or one or more acid gases. Minor amounts of contaminants such as water, nitrogen, iron sulfide, wax, and crude oil, for example, may also be present.
  • One or more of these components may be removed and/or lessened in concentration prior to processing a natural gas stream according to the disclosure herein.
  • compressor refers to a machine, unit, device, or apparatus that increases the pressure of a gas stream by the application of work.
  • Compressors may feature a single compression process or step, or compressors may feature multi-stage compressions or steps, more particularly multi-stage compressors located within a single casing or shell.
  • Gas streams to be compressed may be provided to a compressor at different pressures.
  • Some stages or steps of a cooling process may involve two or more compressors in parallel, series, or both.
  • cooling refers to lowering and/or dropping a temperature and/or internal energy of a substance by any suitable, desired, or required amount.
  • Cooling may include a temperature drop of at least about 1°C, at least about 5°C, at least about 10°C, at least about 15°C, at least about 25°C, at least about 35°C, at least about 50°C, at least about 75°C, at least about 85°C, at least about 95°C, or at least about 100°C.
  • the cooling may use any suitable heat sink, such as steam generation, hot water heating, cooling water, air, refrigerant, other process streams (integration), and combinations thereof.
  • One or more sources of cooling or heat sinks may be combined and/or cascaded to reach a desired temperature.
  • the cooling step may use a cooling unit with any suitable device and/or equipment. Cooling may include indirect heat exchange, such as with one or more heat exchangers. Alternately, cooling may use evaporative (heat of vaporization) cooling and/or direct heat exchange, such as a cooling liquid sprayed directly into a gas stream. More preferably, heat exchange may occur indirectly in the embodiments disclosed here
  • an expander refers to one or more devices suitable for reducing the pressure of a fluid in a line (e.g , a liquid stream, a gas stream, or a multiphase stream containing both liquid and gas).
  • a fluid in a line e.g , a liquid stream, a gas stream, or a multiphase stream containing both liquid and gas.
  • an expander suitable for use in the disclosure herein may operate by (1) at least partially by isenthalpic means, or (2) at least partially by isentropic means, or (3) a combination of both isentropic means and isenthalpic means.
  • Suitable devices for isenthalpic expansion of natural gas may include, but are not limited to, manually or automatically, actuated throttling devices such as, for example, valves, control valves, Joule-Thomson (J-T) valves, or Venturi devices.
  • Suitable devices for isentropic expansion of natural gas may include equipment such as expanders or compressor-expanders, including turboexpanders, that extract or derive work from such expansion.
  • Suitable devices for isentropic expansion of liquid streams may include equipment such as expanders, hydraulic expanders, liquid turbines, or compressor-expanders that extract or derive work from such expansion.
  • heat exchanger refers to any device capable of transferring heat energy or cold energy from one medium to another medium, such as between at least two distinct fluids.
  • Heat exchangers may include “direct heat exchangers” and "indirect heat exchangers.”
  • a heat exchanger may be of any suitable design, such as a co-current or counter-current heat exchanger, an indirect heat exchanger (e.g, a spiral wound heat exchanger or a plate-fin heat exchanger such as a brazed aluminum plate fin type), direct contact heat exchanger, shell-and-tube heat exchanger, spiral, hairpin, core, core-and-kettle, printed-circuit, double-pipe or any other type of heat exchanger.
  • Heat exchangers may also refer to any column, tower, unit or other arrangement adapted to allow the passage of one or more streams for promoting direct or indirect heat exchange between one or more lines of refrigerant.
  • compressor-expander refers to a machine in which an expander provides shaft power to drive a compressor.
  • a “turboexpander” is a type of compressor-expander coupled together on a single (common) shaft.
  • a “compander” is a type of compressor-expander in which the compressor and expander are coupled by separate gear- driven shafts.
  • FIGS. 1A, IB and 2-4 compression of a natural gas stream takes place in a compressor and compressor-expander placed sequentially in series prior to forming a recycle stream, thereby defining a pre-boost configuration, as explained in further detail below.
  • FIGS. 1A and IB the recycle stream is not expanded further, whereas additional recycle stream expansion takes place in FIGS. 2-4.
  • FIG. 5 shows compression of a natural gas stream using a compressor-expander and a compressor placed sequentially in series prior to forming a recycle stream, thereby defining a post-boost configuration, as explained in further detail below.
  • Post-boost compression-expansion configurations may present certain advantages over comparable pre-boost compression-expansion configurations.
  • FIG. 1A is a diagram of a first configuration of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas. No additional expansion of a recycle stream comprising the expanded natural gas takes place in FIG. 1A, nor in the related system and method configuration in FIG. IB.
  • system and method 100 provides natural gas stream 102 to first compressor 104 via feed line 101.
  • Natural gas stream 102 is provided in feed line 101 at a first temperature (Tl) and a first pressure (Pl).
  • first compressor 104 natural gas stream 102 is pressurized to form a compressed natural gas stream.
  • the first compressor 104 may be driven by a drive shaft comprising a motor drive, a gas turbine drive, and/or steam turbine drive, among others. Rejection of excess heat from the compressed natural gas stream then takes place in intermediate heat exchanger 108, which may be optionally omitted in some system and method configurations.
  • the compressed natural gas stream is at an intermediate pressure and temperature state at this juncture, wherein the intermediate pressure state comprises a higher pressure than the first pressure (Pl).
  • the compressed natural gas stream exiting intermediate heat exchanger 108 may then be further compressed.
  • second compressor 110 and first heat exchanger 112 are fluidly coupled in series with intermediate heat exchanger 108.
  • Second compressor 110 and/or first heat exchanger 112 may also be optionally omitted in some system and method configurations.
  • the compressed natural gas stream Prior to entering first heat exchanger 112 following further compression with second compressor 110, the compressed natural gas stream may have a second temperature (T2) and a second pressure (P2) higher than the first pressure (Pl).
  • first compressor 104, second compressor 110, intermediate heat exchanger 108 and first heat exchanger 112 may collectively achieve the third pressure (P3) and the third temperature (T3) in the cooled, compressed natural gas stream.
  • Intermediate heat exchanger 108 and first heat exchanger 112, if present, may function through indirect heat exchange, such as through air and/or water cooling of the compressed natural gas stream.
  • intermediate heat exchanger 108 may be optionally omitted, intermediate cooling of natural gas stream 102 may be particularly desirable.
  • Intermediate cooling may lower the power needed to cool the natural gas stream to the second pressure (P2), afford greater thermodynamic efficiency, and decrease volumetric flow. Decreased volumetric flow may allow a decreased casing size for second compressor 110 to be realized. Second compressor 110 may be omitted if first compressor 104 is sufficient to achieve satisfactory pressurization prior to expansion.
  • first expander 116 is operatively coupled to second compressor 110 by common drive shaft 117, thereby defining a compressor-expander, specifically a turboexpander-compressor.
  • drive shaft 117 attached to second compressor 110 may comprise a motor drive, a gas turbine drive, and/or steam turbine drive, among others.
  • drive shaft 117 attached to first expander 116 may be replaced with an electric generator, oil break, or other commonly used power generating/dissipating drive or device.
  • the gas pressure decreases and thereby forms a chilled, expanded natural gas stream having a fifth pressure (P5) lower than the fourth pressure (P4) and a fifth temperature (T5) lower than the fourth temperature (T4).
  • the fifth pressure (P5) is not greater than about 140 bar.
  • the 140 bar pressure limit may be chosen to protect downstream equipment and piping and may be increased if more robust materials are used. More preferably, the fifth pressure (P5) may be about 65 bar or above, or about 70 bar or above, and below about 140 bar, such that liquefaction takes place in a dense, single-phase system.
  • Branch line 120 may be optionally present to divert at least a portion of the cooled, compressed natural gas stream from interacting with second heat exchanger 140.
  • process flexibility may be introduced to account for environmental factors, such as seasonal variation of ambient temperature, gas source variability, process and equipment variability, and the like. Additional approaches to account for seasonal temperature variation and other factors include, for example, increasing or decreasing the volumetric flow of recycle gas in recycle line 150, as discussed hereinafter.
  • the chilled, expanded natural gas stream exiting first expander 116 via outlet line 121 may then be split into a main stream in line 122 and a recycle stream in line 124, each of which is at the fifth pressure (P5) and the fifth temperature (T5).
  • the main stream in line 122 may undergo liquefaction to produce LNG 130, such as through conventional refrigeration processes and/or interaction of the main stream with a cryogenic liquid.
  • the fifth pressure (P5) represents the liquefaction pressure.
  • the recycle stream in line 124 may be directly conveyed to second heat exchanger 140 or undergo further expansion, as described further herein in reference to FIGS. 2-4.
  • the recycle stream in line 124 is conveyed to second heat exchanger 140 at the fifth temperature (T5) and the fifth pressure (P5). Since the fifth temperature (T5) is lower than the fourth temperature (T4) and the fourth temperature (T4) is lower than the third temperature (T3), the recycle stream may be employed to promote further cooling of the cooled, compressed natural gas stream in second heat exchanger 140.
  • the cooled, compressed natural gas stream and the recycle stream may undergo heat exchange within second heat exchanger 140 to afford the cooled, compressed natural gas stream at a lower fourth temperature (T4), thereby providing the chilled, expanded natural gas stream at a commensurately lower fifth temperature (T5) following expansion in first expander 116 (i.e., a fourth temperature (T4) of the cooled, compressed natural gas stream beyond that attainable with just intermediate heat exchanger 108 and first heat exchanger 112 alone) and decreasing the energy burden required when forming LNG 130 from the chilled, expanded natural gas stream.
  • Second heat exchanger 140 may be a printed circuit heat exchanger (PCHE) in various embodiments of the present disclosure, but other heat exchanger configurations that bring the cooled, compressed natural gas stream and the recycle stream into close proximity to facilitate heat exchange may also be suitable.
  • PCHE printed circuit heat exchanger
  • recycle stream 150 After undergoing heat exchange at second heat exchanger 140, the recycle stream is returned to a location upstream from first heat exchanger 112 via recycle line 150. As depicted in FIG. 1A, recycle line 150 reconnects with feed line 101 prior to delivery of natural gas stream 102 to first compressor 104. Other locations upstream or downstream from first compressor 104 may also be suitable. For example, the recycle stream may be returned to the natural gas stream upstream from first compressor 104, downstream from first compressor 104 and upstream of second compressor 110 (either upstream or downstream from intermediate heat exchanger 108, if present), and/or downstream from second compressor 110 but upstream from first heat exchanger 112.
  • the recycle stream may decrease the temperature of natural gas stream 102 depending on the fifth temperature (T5) and the extent of heat exchange taking place at second heat exchanger 140, thereby lessening the energy input needed to afford the intermediate pressure state.
  • T5 fifth temperature
  • second heat exchanger 140 second heat exchanger 140
  • first compressor 104 may comprise multiple compressor stages and/or comprise multiple compressor casings and that are driven by separate drive shafts, and the recycle stream may be returned to any of these multiple compressor stages or at an interstage location of compression, as shown in an alternative configuration in FIG. IB. That is, certain system and method configurations may feature first compressor 104 being operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • FIG. IB is a diagram of a second configuration of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas.
  • Identical reference characters are utilized in FIG. IB, as well as in the remaining FIGS., for in-common elements having similar features to those described above in FIG. 1 A. Accordingly, in the interest of brevity, features in the remaining FIGS, having similar operational characteristics to those described above in FIG. 1 A are not described again in detail.
  • the configuration shown in FIG. IB differs from the configuration shown in FIG. 1A in that first compressor 104 is multi-stage in FIG. IB and the return location of recycle line 150 is at an interstage location downstream from first compressor 104.
  • system and method 103 provides natural gas stream 102 via feed line 101 to first compressor 104, which provides multi-stage compression in the depicted configuration.
  • first compressor 104 Before exiting first compressor 104, the resulting compressed natural gas stream may undergo inter-stage cooling in inter-stage heat exchanger 106.
  • processing of the natural gas may then take place in a largely similar manner to that described above in reference to FIG. 1 A, with the exception of the location where recycle line 150 is returned.
  • recycle line 150 provides the recycle stream to the lines allowing inter-stage cooling to take place, preferably upon the return line connecting inter-stage heat exchanger 106 to first compressor 104.
  • recycle line 150 may provide the recycle stream to feed line 101, to the line fluidly connecting first compressor 104 and second compressor 110, either upstream or downstream of intermediate heat exchanger 108, if present, or even downstream from second compressor 110 and upstream from first heat exchanger 112.
  • the recycle stream may be returned upstream from first compressor 104, downstream from first compressor 104 and upstream from second compressor 110, including at an inter-stage location, downstream from second compressor 110 and upstream from first heat exchanger 112, or any combination thereof.
  • second compressor 110 and first heat exchanger 112 may be optionally omitted in some system and method configurations.
  • Inter-stage heat exchanger 106, intermediate heat exchanger 108, and first heat exchanger 112, if present, may function through indirect heat exchange, such as through air or water cooling of the compressed natural gas stream.
  • FIG. 2A and 2B are diagrams of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using an expander.
  • FIG. 3 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using a Joule-Thompson valve.
  • FIGS. 2A, 2B, and 3 are largely identical to FIG. 1A and may be better understood by reference thereto. Although not shown, it is to be appreciated that the configuration of FIG. IB may similarly incorporate additional expansion capabilities in the recycle line.
  • system and method 200 conveys the recycle stream in line 124 to second expander 131, whereupon the recycle stream exiting second expander 131 has a sixth pressure (P6) lower than the fifth pressure (P5) and a sixth temperature (T6) lower than the fifth temperature (T5).
  • the recycle stream exiting second expander 131 is again at a lower temperature than the cooled, compressed natural gas stream exiting first heat exchanger 112.
  • the recycle stream may be utilized to promote further cooling of the cooled, compressed natural gas stream within second heat exchanger 140, thereby producing a more favorable entropic state for liquefaction.
  • FIG. 2B differs from the configuration shown in FIG. 2A in that the configuration of FIG. 2B employs integration of waste heat derived from the liquefaction of stream 122 to provide the power to drive first compressor 104.
  • a system and method 201 liquefies stream 122 in a liquefaction process 132 using refrigerant streams 133, 134 to produce liquefied natural gas (LNG) stream 130.
  • Liquefaction process 132 additionally uses refrigerant compressor(s) 135 to provide heating and cooling cycles of refrigerant streams 133, 134.
  • the power source to drive refrigerant compressor(s) 135 is gas turbine 136.
  • Exhaust heat 137 is recovered from gas turbine 136 via Heat Recovery Steam Generator (HRSG) 138. At least a portion of the resulting stream of pressurized steam generated by HRSG 138 is conveyed through line 139 to power first compressor 104, such as via a steam turbine (not shown). In additional aspects (not depicted by FIG. 2B), at least a portion of the stream of pressurized steam generated by HRSG 138 may be used to power second compressor 110, either in addition to or in lieu of being used to power first compressor 104.
  • HRSG Heat Recovery Steam Generator
  • first compressor 104 and second compressor 110 may be operatively coupled to one another via a drive shaft driven by at least a portion of the stream of pressurized steam generated by HRSG 138.
  • Additional heat 141 may optionally be supplied to HRSG 138 via supplementary firing.
  • an additional steam stream 142 may optionally be withdrawn and employed in various aspects (not shown) of a facility in which system and method 201 is located, such as for process heating, generating electricity, among others.
  • a variable flow rate of the recycle stream in line 124 is returned (after passage through second expander 131 and second heat exchanger 140) to the inlet of first compressor 104.
  • the variation in the flow rate of the returned recycle stream to first compressor 104 in turn results in a variation in the amount of power required to drive compressor 104.
  • the heat integration afforded by the configuration depicted in FIG. 2B advantageously provides an additional degree of freedom in rebalancing the power distribution between first compressor 104 and refrigerant compressor(s) 135 via recycle stream 124 to optimize overall energy demand of the system and method 201.
  • FIG. 3 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been further expanded using a Joule-Thompson valve.
  • Natural gas liquefaction system and method 300 depicted in FIG. 3 is substantially similar to that depicted in FIG. 2A, except for replacement of second expander 131 with Joule-Thompson valve 330. Suitable Joule-Thompson valves and their operation will be familiar to one having ordinary skill in the art.
  • branch line 120 may be omitted when employing Joule- Thompson valve 330 to expand the recycle stream.
  • Joule-Thompson valve 330 may provide less efficient cooling of the recycle stream than does second expander 131, there is less risk of overcooling the cooled, compressed natural gas stream exiting second heat exchanger 140 than when second expander 131 (FIG. 2A) is used.
  • Joule-Thompson valve 330 is the primary mechanism for promoting expansion within the recycle stream.
  • a bypass Joule-Thompson valve (not shown) may be present to bypass second expander 131.
  • the bypass Joule-Thompson valve may allow natural gas processing to continue even when second expander 131 needs maintenance or otherwise becomes inoperable.
  • FIG. 4 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas that has been formed and further expanded using a compander. Natural gas liquefaction system and method 400 in FIG. 4 differs that shown in FIG.
  • second compressor 110, first expander 116 and second expander 131 are incorporated within shared casing 350.
  • Second compressor 110 and first expander 116 may again be operatively coupled to one another via drive shaft 352, and drive shaft 352 may be operatively coupled to drive shaft 354 of second expander 131 via bull gear 360.
  • shared casing 350, second compressor 110, first expander 116, second expander 131, shafts 352 and 354, and bull gear 360 define compander 370.
  • natural gas stream 102 is exposed sequentially to first compressor 104 and second compressor 110.
  • second compressor 110 comprises a portion of a compressor-expander, particularly a turboexpander
  • natural gas stream 102 is exposed to second compressor 110 of the compressor-expander following an initial compression of the natural gas stream with first compressor 104 to reach an intermediate pressure state.
  • Such process configurations may be referred to a providing “pre-boost” compression, since natural gas stream 102 is compressed prior to being further compressed using second compressor 110 of the compressor-expander.
  • pre-boost compression may be suitable for use in the disclosure herein.
  • the compressor-expander is downstream from a main compressor in such configurations, the compressor-expander may need to be resistant to higher pressures than would otherwise be necessary than if the compressor- expander were to provide the initial compression of the natural gas stream.
  • the intolerance to excessive pressures may lead to higher design costs and manufacturing challenges.
  • lower compression efficiencies with the compressor-expander may occur in such configurations, and additional heat exchange between the first compressor and the compressorexpander may be highly desirable.
  • the foregoing difficulties may be at least partially alleviated by providing the natural gas stream to the compressor-expander (turboexpander) first, followed by additional compression thereafter, if needed, as described further below in reference to FIG. 5. Since such method and system configurations provide additional compression after initial compression with a compressor-expander, the processes may be referred to as providing “postboost” compression.
  • the post-boost configuration of FIG. 5 may utilize similar parts to those utilized for the pre-boost configurations of FIGS. 1A, IB and 2-4.
  • post-boost” configurations may be implemented without conducting a secondary expansion of the recycle stream and may also allow the compressor side of the compressor-expander to be smaller than would otherwise be necessary. It is to be appreciated that secondary expansion of the recycle stream using an expander or Joule-Thompson valve may be incorporated in post-boost systems and methods as well, if needed.
  • FIG. 5 is a diagram of a portion of a natural gas liquefaction system and method employing compression-expansion of a natural gas stream and recycling of expanded natural gas, in which initial compression and expansion are conducted with a compressor-expander.
  • natural gas liquefaction system and method 500 provides natural gas stream 402 to first compressor 404 via feed line 401.
  • Natural gas stream 402 is provided in feed line 401 at a first temperature (Tl) and a first pressure (Pl).
  • First compressor 404 is operatively coupled to expander 430 via drive shaft 452, thereby defining a compressorexpander.
  • first compressor 404 natural gas stream 402 is pressurized to form a compressed natural gas stream having a second temperature (T2) and a second pressure (P2) higher than the first pressure (Pl).
  • the compressed natural gas stream is then provided to second compressor 410, in which the compressed natural gas stream reaches a third temperature (T3) and a third temperature (P3) higher than the second pressure (P2).
  • the natural gas stream may be provided directly from first compressor 404 to second compressor 410 without undergoing intermediate cooling in between.
  • an intermediate heat exchange may take place between first compressor 404 and second compressor 410 using an intermediate heat exchanger (not shown) to achieve an intermediate temperature and pressure state.
  • the compressed natural gas stream Before exiting second compressor 410, the compressed natural gas stream may undergo inter-stage cooling in inter- stage heat exchanger 408.
  • the compressed natural gas stream may undergo additional heat exchange at first heat exchanger 412 to form a cooled, compressed natural gas stream having a fourth pressure (P4) and a fourth temperature (T4) lower than the third temperature (T3).
  • first heat exchanger 412 may be omitted. If present, inter-stage heat exchanger 408 and first heat exchanger 412 may function through indirect heat exchange, such as through air or water cooling of the compressed natural gas stream.
  • the cooled, compressed natural gas stream may be conveyed to expander 430 after interacting with second heat exchanger 440, in a manner described in further detail hereinafter.
  • the cooled, compressed natural gas stream may then have a fifth pressure (P5) and a fifth temperature (T5) lower than the fourth temperature (T4).
  • the gas pressure decreases and thereby forms a chilled, expanded natural gas stream having a sixth pressure (P6) lower than the fifth pressure (P5) and a sixth temperature (T6) lower than the fifth temperature (T5).
  • the sixth pressure (P6) is not greater than about 140 bar.
  • the chilled, expanded natural gas stream exiting expander 430 may then be split into a main stream in line 422 and a recycle stream in line 424, each at the sixth pressure (P6) and the sixth temperature (T6).
  • the main stream in line 422 may undergo liquefaction to produce LNG 432, such as through conventional refrigeration processes and/or interaction of the main stream with a cryogenic liquid.
  • the sixth pressure (P6) represents the liquefaction pressure.
  • the recycle stream in line 424 at the sixth pressure (P6) and the sixth temperature (T6) is at a lower temperature than the cooled, compressed natural gas stream exiting first heat exchanger 412.
  • the postboost configuration of FIG. 5 may similarly allow the recycle stream to promote further cooling of the cooled, compressed natural gas stream in second heat exchanger 440.
  • the cooled, compressed natural gas stream and the recycle stream may undergo heat exchange within second heat exchanger 440 to afford the cooled, compressed natural gas stream at the fifth temperature (T5) and form a more favorable entropic state.
  • Second heat exchanger 440 may be a printed circuit heat exchanger (PCHE) in various embodiments of the present disclosure, but other heat exchanger configurations that bring the cooled, compressed natural gas stream and the recycle stream into close proximity to facilitate heat exchange may also be suitable. It is to be appreciated, however, additional expansion of the recycle stream may be conducted in some instances.
  • PCHE printed circuit heat exchanger
  • recycle line 450 provides the recycle stream to the lines allowing inter-stage cooling to take place, preferably upon the return line to second compressor 410.
  • recycle line 450 may provide the recycle stream to feed line 401 or to the line fluidly connecting first compressor 404 and second compressor 410, preferably the line returning to first compressor 404. That is, the recycle stream may be returned to the natural gas stream upstream from first compressor 404, downstream from first compressor 404 and upstream from second compressor 410, downstream from second compressor 410 and upstream from first heat exchanger 412, or any combination thereof.
  • the recycle stream may decrease the natural gas temperature at any of these locations, thereby allowing higher throughput to take place for forming LNG 432.
  • pre-boost methods for promoting liquefaction of a natural gas stream may comprise: providing a natural gas stream at a first temperature and a first pressure to a first compressor, optionally in series fluid communication with a second compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor and the second compressor, thereby forming a compressed natural gas stream having a second temperature; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the first compressor and the second compressor, if present, thereby forming a cooled, compressed natural gas stream having a third pressure and a third temperature lower than the second temperature; performing a second heat exchange upon the cooled, compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fourth pressure and a fourth temperature lower than the third temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using a first expander from about the fourth pressure to a fifth pressure lower than the fourth pressure,
  • the methods may further comprise: expanding the recycle stream to a sixth pressure lower than the fifth pressure, thereby cooling the recycle stream to a sixth temperature lower than the fifth temperature.
  • the recycle stream may undergo the second heat exchange with the cooled, compressed natural gas stream at the second heat exchange location.
  • Expansion of the recycle stream may take place using a second expander or a Joule-Thompson valve.
  • expansion of the recycle stream may take place using a compander, in which the first expander, the second expander, and the second compressor are located within a shared casing.
  • the pressure of the natural gas stream may vary depending on its origin.
  • the natural gas stream may be provided to the first compressor at a first pressure of about 85 bar or less.
  • the first pressure (Pl) may be about 60 bar or less, or about 50 bar or less, more preferably a first pressure ranging from about 20 bar to about 85 bar, or about 40 bar to about 80 bar, or about 50 bar to about 85 bar, or about 20 bar to about 60 bar.
  • the second pressure (P2) may be about 100 bar or more following compression with the first compressor and the second compressor.
  • the second pressure (P2) may be about 105 bar or more, about 110 bar or more, about 120 bar or more, or about 130 bar or more, more preferably a second pressure (P2) ranging from about 100 bar to about 200 bar.
  • up to about 60% of the natural gas stream by volume may be returned upstream via the recycle stream, depending on particular cooling needs for the natural gas stream or the cooled, compressed natural gas stream.
  • about 1% to about 60% of the natural gas stream by volume may be returned via the recycle stream, or about 10% to about 50% of the natural gas stream by volume, or about 20% to about 40% of the natural gas stream by volume.
  • Up to about 10% of the natural gas stream by volume may be returned upstream in other particular instances.
  • the fifth pressure (P5) may be about 65 bar to about 130 bar or about 85 bar to about 140 bar
  • the fifth temperature (T5) may range from about -30°C to about 10°C.
  • the sixth pressure (P6) and sixth temperature (T6) may also reside within similar ranges, but remain at lower values than the corresponding fifth pressure (P5) and fifth temperature (T5).
  • the methods may further comprise performing one or more intermediate heat exchanges of the natural gas stream between the first compressor and the second compressor.
  • the one or more intermediate heat exchanges may take place using air cooling, water cooling, or any combination thereof.
  • the first compressor may be operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • systems for promoting liquefaction of a natural gas stream through preboost compression and expansion may comprise: a natural gas feed connected to a first compressor and an optional second compressor that are fluidly coupled in series; a first heat exchange location downstream from the second compressor and fluidly coupled to an output of the second compressor; a second heat exchange location fluidly coupled to an output of the first heat exchange location, if present; a first expander fluidly coupled to an output of the second heat exchange location; and an output line from the first expander that is subdivided into a main line and recycle line.
  • the recycle line is in thermal communication with the second heat exchange, and the recycle line is in fluid communication with the natural gas feed.
  • the second compressor and the first expander may be operatively coupled by a common drive shaft, thereby defining a turboexpander.
  • the first heat exchange location may comprise a heat exchanger functioning by air cooling, water cooling, or any combination thereof.
  • the systems may further comprise one or more intermediate heat exchange locations between the first compressor and the second compressor, wherein the one or more intermediate heat exchange locations comprise a heat exchanger functioning by air cooling, water cooling, or any combination thereof.
  • the first compressor may be operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • the interstage cooling may take place by air cooling, water cooling, or any combination thereof.
  • the systems for promoting pre-boost compression and expansion may further comprise a second expander or a Joule-Thompson valve located within the recycle line.
  • the recycle line may be in thermal communication with the second heat exchange location downstream from the second expander or the Joule-Thompson valve.
  • a second expander may be located within the recycle line.
  • the first compressor, the first expander and the second expander may collectively define a compander.
  • System configurations employing a second expander but not configured within a compander also reside within the scope of the present disclosure.
  • post-boost configurations for promoting liquefaction of a natural gas stream may comprise: providing a natural gas stream at a first temperature and first pressure to a first compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor, thereby forming a compressed natural gas stream having a second temperature; compressing the compressed natural gas stream to a third pressure higher than the second pressure using a second compressor in fluid communication with the first compressor, the compressed natural gas stream having a third temperature after being compressed to the third pressure; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the second compressor, thereby forming a cooled, compressed natural gas stream having a fourth pressure and a fourth temperature lower than the third temperature; performing a second heat exchange upon the compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fifth pressure and a fifth temperature lower than the fourth temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using an
  • the recycle stream may be returned to the natural gas stream upstream from the first compressor, downstream from the first compressor and upstream from the second compressor, downstream from the second compressor and upstream from the first heat exchange location, if present, or any combination thereof.
  • the recycle stream may also be returned to a location of inter-stage cooling in certain system and method configurations.
  • the pressure of the natural gas stream may vary depending on its origin.
  • the natural gas stream may be provided to the first compressor at a first pressure of about 85 bar or less.
  • the first pressure (Pl) may be about 60 bar or less, or about 50 bar or less, more preferably a first pressure ranging from about 20 bar to about 85 bar, or about 40 bar to about 80 bar, or about 50 bar to about 85 bar, or about 20 bar to about 60 bar.
  • the second pressure (P2) may be about 80 bar or more, about 90 bar or more, or about 100 bar or more, more preferably a second pressure (P2) ranging from about 80 bar to about 200 bar, or about 80 bar to about 140 bar, or about 80 bar to about 120 bar.
  • the third pressure (P3) may be about 100 bar or more following compression with the first compressor and the second compressor.
  • the third pressure (P3) may be about 105 bar or more, about 110 bar or more, about 120 bar or more, or about 130 bar or more, more preferably a third pressure (P3) ranging from about 100 bar to about 200 bar.
  • the sixth pressure (P6) may be about 65 bar to about 130 bar or about 85 bar to about 140 bar, and the sixth temperature (T6) may range from about -30°C to about 10°C.
  • up to about 60% of the natural gas stream by volume may be returned upstream via the recycle stream, depending on particular cooling needs for the natural gas stream or the cooled, compressed natural gas stream.
  • about 1% to about 60% of the natural gas stream by volume may be returned via the recycle stream, or about 10% to about 50% of the natural gas stream by volume, or about 20% to about 40% of the natural gas stream by volume.
  • Up to about 10% of the natural gas stream by volume may be returned upstream in other particular instances.
  • Compressing to the third pressure (P3) may take place in the second compressor in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • the inter-stage cooling may take place using air cooling, water cooling, or any combination thereof.
  • the first compressor and the expander are operatively coupled by a common drive shaft, thereby defining a turboexpander.
  • systems for promoting liquefaction of a natural gas stream through postboost compression and expansion may comprise: a natural gas feed connected to a first compressor; a second compressor fluidly coupled to an output of the first compressor; an optional first heat exchange location fluidly coupled to an output of the second compressor; a second heat exchange location downstream from the second compressor and fluidly coupled to an output of the first heat exchange location; an expander fluidly coupled to an output of the second heat exchange location; and an output line from the expander that is subdivided into a main line and recycle line.
  • the recycle line is in thermal communication with the second heat exchange location, and the recycle line is in fluid communication with a location upstream from the first heat exchange location.
  • the recycle line may be in fluid communication with the natural gas stream upstream from the first compressor, upstream from the first compressor and downstream from the second compressor, downstream from the second compressor and upstream from the first heat exchange location, if present, or any combination thereof.
  • the first compressor and the expander are operatively coupled by a common drive shaft, thereby defining a turboexpander.
  • the second compressor may be operable to compress the natural gas feed in at least two stages, with inter-stage cooling takes place between the at least two stages.
  • the inter-stage cooling may take place using air cooling, water, cooling, or any combination thereof.
  • Embodiments disclosed herein include:
  • A. Methods for forming LNG using pre-boost compression and expansion comprise: providing a natural gas stream at a first temperature and a first pressure to a first compressor, optionally in series fluid communication with a second compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor and optionally the second compressor, thereby forming a compressed natural gas stream having a second temperature; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the first compressor and the second compressor, if present, thereby forming a cooled, compressed natural gas stream having a third pressure and a third temperature lower than the second temperature; performing a second heat exchange upon the cooled, compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fourth pressure and a fourth temperature lower than the third temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using a first expander from about the fourth pressure to a fifth pressure lower than the fourth pressure,
  • A. Systems for forming LNG using pre-boost compression and expansion comprise: a natural gas feed connected to a first compressor and a second compressor that are fluidly coupled in series; an optional first heat exchange location fluidly coupled to an output of the second compressor; a second heat exchange location downstream from the second compressor and fluidly coupled to an output of the first heat exchange location, if present; a first expander fluidly coupled to an output of the second heat exchange location; and an output line from the first expander that is subdivided into a main line and recycle line; wherein the recycle line is in thermal communication with the second heat exchange location, and the recycle line is in fluid communication with the natural gas feed.
  • C. Methods for forming LNG using post-boost compression and expansion comprise: providing a natural gas stream at a first temperature and first pressure to a first compressor; compressing the natural gas stream to a second pressure higher than the first pressure using the first compressor, thereby forming a compressed natural gas stream having a second temperature; compressing the compressed natural gas stream to a third pressure higher than the second pressure using a second compressor in fluid communication with the first compressor, the compressed natural gas stream having a third temperature after being compressed to the third pressure; performing an optional first heat exchange upon the compressed natural gas stream at a first heat exchange location downstream from the second compressor, thereby forming a cooled, compressed natural gas stream having a fourth pressure and a fourth temperature lower than the third temperature; performing a second heat exchange upon the compressed natural gas stream at a second heat exchange location downstream from the first heat exchange location, thereby affording a fifth pressure and a fifth temperature lower than the fourth temperature to the cooled, compressed natural gas stream; expanding the cooled, compressed natural gas stream using an expander from about
  • Systems for forming LNG using post-boost compression and expansion comprise: a natural gas feed connected to a first compressor; a second compressor fluidly coupled to an output of the first compressor; an optional first heat exchange location fluidly coupled to an output of the second compressor; a second heat exchange location downstream from the second compressor and fluidly coupled to an output of the first heat exchange location, if present; an expander fluidly coupled to an output of the second heat exchange location; and an output line from the expander that is subdivided into a main line and recycle line; wherein the recycle line is in thermal communication with the second heat exchange location, and the recycle line is in fluid communication with a location upstream from the first heat exchange location.
  • Embodiments A and B may have one or more of the following additional elements in any combination:
  • Element 1 wherein the recycle stream is returned to the natural gas stream upstream from the first compressor, downstream from the first compressor and upstream from the second compressor and one or more intermediate heat exchange locations, downstream from the second compressor, or any combination thereof.
  • Element 2 wherein the first pressure is about 85 bar or less.
  • Element 3 wherein the second pressure is about 100 bar or more.
  • Element 4 wherein the first heat exchange is performed and takes place by air cooling, water cooling, or any combination thereof.
  • Element 5 wherein the method further comprises performing one or more intermediate heat exchanges of the natural gas stream between the first compressor and the second compressor.
  • Element 6 wherein the one or more intermediate heat exchanges take place using air cooling, water cooling, or any combination thereof.
  • Element 7 wherein the first compressor is operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • Element 8 wherein the method further comprises expanding the recycle stream to a sixth pressure lower than the fifth pressure, thereby cooling the recycle stream to a sixth temperature lower than the fifth temperature before returning the recycle stream to the natural gas stream; wherein the second heat exchange with the recycle stream takes place after expanding to the sixth pressure and the sixth temperature.
  • Element 9 wherein expanding the recycle stream takes place using a Joule- Thompson valve or a second expander downstream from the first expander.
  • Element 10 wherein expanding the recycle stream takes place using a second expander, and the second compressor, the first expander, and the second expander collectively define a compander.
  • Element 11 wherein the second compressor is present.
  • Element 12 wherein the second compressor and the first expander are operatively coupled by a common drive shaft.
  • Element 13 wherein up to about 60% of the natural gas stream by volume is returned via the recycle stream.
  • Element 14 wherein the first compressor is driven by a drive shaft comprising a steam turbine drive.
  • Element 15 further comprising: liquefying the main stream in a liquefaction process, the liquefaction process using a refrigerant compressor; recovering heat from a power source of the refrigerant compressor; generating a stream of pressurized steam from the recovered heat; and powering the first compressor using at least part of the stream of pressurized steam.
  • Element 16 wherein the recycle line is in fluid communication with the natural gas feed upstream from the first compressor, downstream from the first compressor and upstream from the second compressor and one or more intermediate heat exchange locations, downstream from the second compressor, or any combination thereof.
  • Element 17 wherein the first heat exchange location is present and comprises a heat exchanger functioning by air cooling, water cooling, or any combination thereof.
  • Element 18 wherein the system further comprises one or more intermediate heat exchange locations between the first compressor and the second compressor, the one or more intermediate heat exchange locations comprising a heat exchanger functioning by air cooling, water cooling, or any combination thereof.
  • Element 19 wherein the second compressor and the first expander are operatively coupled by a common drive shaft.
  • Element 20 wherein the first compressor is operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • Element 21 wherein the system further comprises a second expander or a Joule- Thompson valve located within the recycle line; wherein the recycle line is in thermal communication with the second heat exchange location downstream from the second expander or the Joule-Thompson valve.
  • Element 22 wherein a second expander is located within the recycle line.
  • Element 23 wherein the second compressor, the first expander, and the second expander collectively define a compander.
  • Embodiments C and D may have one or more of the following additional elements in any combination:
  • Element 1 wherein the recycle stream is returned to the natural gas stream upstream from the first compressor, downstream from the first compressor and upstream from the second compressor, downstream from the second compressor and upstream from the first heat exchange location, or any combination thereof.
  • Element 2’ wherein the first pressure is about 85 bar or less.
  • Element 3’ wherein the third pressure is about 100 bar or more.
  • Element 4’ wherein the first heat exchange is performed and takes place by air cooling, water cooling, or any combination thereof.
  • Element 5’ wherein the sixth pressure is not greater than about 140 bar.
  • Element 6’ wherein compressing to the third pressure in the second compressor takes place in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • Element 7’ wherein the inter-stage cooling takes place by air cooling, water cooling, or any combination thereof.
  • Element 8 wherein the first compressor and the expander are operatively coupled by a common drive shaft.
  • Element 9’ wherein up to about 60% of the natural gas stream by volume is returned via the recycle stream.
  • Element 10’ wherein the recycle line is returned to the natural gas stream upstream from the first compressor, downstream from the first compressor and upstream from the second compressor, downstream from the second compressor and upstream from the first heat exchange location, or any combination thereof.
  • Element 11 wherein the first heat exchange location is present and comprises a heat exchanger functioning by air cooling, water cooling, or any combination thereof.
  • Element 12’ wherein the second compressor is operable to compress the natural gas feed in at least two stages, with inter-stage cooling taking place between the at least two stages.
  • Element 13’ wherein the inter-stage cooling takes place using air cooling, water cooling, or any combination thereof.
  • Element 14’ wherein the first compressor and the expander are operatively coupled by a common drive shaft.
  • Illustrative combinations applicable to A and B may include, but are not limited to, 1 and 2; 1 and 3; 1 and 4; 1 and 5; 1, 5 and 6; 1 and 7; 1 and 8; 1, 8 and 9; 1, 8 and 10; 1 and 11; 1, 11 and 12; 1 and 13; 2 and 3; 2 and 4; 2 and 5; 2, 5 and 6; 2 and 7; 2 and 8; 2, 8 and 9; 2, 8 and 10; 2 and 11; 2, 11 and 12; 2 and 13; 3 and 4; 3 and 5; 3, 5 and 6; 3 and 7; 3 and 8; 3, 8 and 9; 3, 8 and 10; 3 and 11; 3, 11 and 12; 3 and 13; 4 and 5; 4, 5 and 6; 4 and 7; 4 and 8; 4, 8 and 9; 4, 8 and 10; 4 and 11; 4, 11 and 12; 4 and 13; 5 and 7; 5 and 8; 5, 8 and 9; 5, 8 and 10; 5 and 11; 5, 11 and 12; 5 and 13; 7 and 8; 7, 8 and 9; 7, 8 and 10; 7 and 11; 1 and
  • Illustrative combinations applicable to C and D may include, but are not limited to,l’ and 2’; 1 ’ and 3’; 1’ and 4’; 1’ and 5’; 1’ and 6’; 1’ and 7’; 1 ’ and 8’; 1’ and 9’; 2’ and 3’; 2’ and 4’; 2’ and 5’; 2’ and 6’; 2’ and 7’; 2’ and 8’; 2’ and 9’; 3’ and 4’; 3’ and 5’; 3’ and 6’;
  • Table 1 As shown in Table 1, expansion in the recycle stream produced more efficient operation relative to the comparative system.
  • compositions described herein may be free of any component, or composition not expressly recited or disclosed herein. Any method may lack any step not recited or disclosed herein.
  • compositions, element or group of elements are preceded with the transitional phrase “comprising,” it is understood that we also contemplate the same composition or group of elements with transitional phrases “consisting essentially of,” “consisting of,” “selected from the group of consisting of,” or “is” preceding the recitation of the composition, element, or elements and vice versa.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

Les procédés de liquéfaction de gaz naturel peuvent utiliser beaucoup d'énergie. Des augmentations même graduelles de l'efficacité énergétique peuvent être très avantageuses. Un traitement par compression-détente d'un flux de gaz naturel et un retour d'un flux de recyclage suite à la détente du gaz naturel peuvent abaisser la température du gaz naturel et faciliter la liquéfaction. Un compresseur-détendeur peut être utilisé en combinaison avec un autre compresseur pour fournir un flux de gaz naturel comprimé refroidi, le flux de recyclage pouvant être éventuellement détendu et soumis à un échange de chaleur avec le flux de gaz naturel comprimé refroidi avant la détente. Le compresseur-détendeur peut favoriser la compression du gaz naturel en amont ou en aval d'un autre compresseur dans diverses configurations de systèmes et de procédés.
PCT/US2021/071526 2020-11-03 2021-09-21 Procédés et systèmes de liquéfaction de gaz naturel comprenant une compression, une détente et un recyclage de charge WO2022099233A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US202063109063P 2020-11-03 2020-11-03
US63/109,063 2020-11-03

Publications (1)

Publication Number Publication Date
WO2022099233A1 true WO2022099233A1 (fr) 2022-05-12

Family

ID=77693646

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2021/071526 WO2022099233A1 (fr) 2020-11-03 2021-09-21 Procédés et systèmes de liquéfaction de gaz naturel comprenant une compression, une détente et un recyclage de charge

Country Status (1)

Country Link
WO (1) WO2022099233A1 (fr)

Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878689A (en) 1970-07-27 1975-04-22 Carl A Grenci Liquefaction of natural gas by liquid nitrogen in a dual-compartmented dewar
US5139547A (en) 1991-04-26 1992-08-18 Air Products And Chemicals, Inc. Production of liquid nitrogen using liquefied natural gas as sole refrigerant
US6412302B1 (en) 2001-03-06 2002-07-02 Abb Lummus Global, Inc. - Randall Division LNG production using dual independent expander refrigeration cycles
US20090217701A1 (en) * 2005-08-09 2009-09-03 Moses Minta Natural Gas Liquefaction Process for Ling
WO2010053375A2 (fr) * 2008-11-04 2010-05-14 Hamworthy Gas Systems As Système pour entraînement mécanique à cycle combiné dans des procédés de liquéfaction cryogénique
US8616021B2 (en) 2007-05-03 2013-12-31 Exxonmobil Upstream Research Company Natural gas liquefaction process
US20160003529A1 (en) * 2007-08-24 2016-01-07 Moses Minta Natural Gas Liquefaction Process
US20170167787A1 (en) 2015-12-14 2017-06-15 Fritz Pierre, JR. Method of Natural Gas Liquefaction on LNG Carriers Storing Liquid Nitrogen
US20170167786A1 (en) * 2015-12-14 2017-06-15 Fritz Pierre, JR. Pre-Cooling of Natural Gas by High Pressure Compression and Expansion
US20180231303A1 (en) * 2017-02-13 2018-08-16 Fritz Pierre, JR. Pre-Cooling of Natural Gas by High Pressure Compression and Expansion
US20200064061A1 (en) * 2018-08-22 2020-02-27 Yijun Liu Managing Make-Up Gas Composition Variation for a High Pressure Expander Process

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3878689A (en) 1970-07-27 1975-04-22 Carl A Grenci Liquefaction of natural gas by liquid nitrogen in a dual-compartmented dewar
US5139547A (en) 1991-04-26 1992-08-18 Air Products And Chemicals, Inc. Production of liquid nitrogen using liquefied natural gas as sole refrigerant
US6412302B1 (en) 2001-03-06 2002-07-02 Abb Lummus Global, Inc. - Randall Division LNG production using dual independent expander refrigeration cycles
US20090217701A1 (en) * 2005-08-09 2009-09-03 Moses Minta Natural Gas Liquefaction Process for Ling
US8616021B2 (en) 2007-05-03 2013-12-31 Exxonmobil Upstream Research Company Natural gas liquefaction process
US20160003529A1 (en) * 2007-08-24 2016-01-07 Moses Minta Natural Gas Liquefaction Process
WO2010053375A2 (fr) * 2008-11-04 2010-05-14 Hamworthy Gas Systems As Système pour entraînement mécanique à cycle combiné dans des procédés de liquéfaction cryogénique
US20170167787A1 (en) 2015-12-14 2017-06-15 Fritz Pierre, JR. Method of Natural Gas Liquefaction on LNG Carriers Storing Liquid Nitrogen
US20170167786A1 (en) * 2015-12-14 2017-06-15 Fritz Pierre, JR. Pre-Cooling of Natural Gas by High Pressure Compression and Expansion
US20180231303A1 (en) * 2017-02-13 2018-08-16 Fritz Pierre, JR. Pre-Cooling of Natural Gas by High Pressure Compression and Expansion
US20200064061A1 (en) * 2018-08-22 2020-02-27 Yijun Liu Managing Make-Up Gas Composition Variation for a High Pressure Expander Process

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
OLVE SKJEGGEDAL ET AL: "Optimising and Scaling Up the Brayton Nitrogen Refrigeration Cycle for Offshore and Onshore LNG Applications", GASTECH 2009. THE 24TH INTERNATIONAL CONFERENCE AND EXHIBITION FOR THE LNG, LPG AND NATURAL GAS INDUSTRIES, 25-28 MAY 2009, ABU DHABI,, 25 May 2009 (2009-05-25), pages 18pp, XP009144463 *

Similar Documents

Publication Publication Date Title
US9140490B2 (en) Natural gas liquefaction processes with feed gas refrigerant cooling loops
CA3005327C (fr) Prerefroidissement de gaz naturel par compression et dilatation haute pression
AU2018218196B2 (en) Pre-cooling of natural gas by high pressure compression and expansion
AU2018354587B2 (en) Natural gas liquefaction by a high pressure expansion process using multiple turboexpander compressors
US10077937B2 (en) Method to produce LNG
WO2015069138A2 (fr) Procédé et unité de liquéfaction de gaz naturel
US11815308B2 (en) Pretreatment and pre-cooling of natural gas by high pressure compression and expansion
EP3561421B1 (fr) Procédé et système améliorés pour le refroidissement d'un flux d'hydrocarbures à l'aide d'un réfrigérant en phase gazeuse
EP3561420A1 (fr) Procédé et système améliorés pour le refroidissement d'un flux d'hydrocarbures à l'aide d'un réfrigérant en phase gazeuse
US20150211788A1 (en) Modified Claude Process for Producing Liquefied Gas
US11806639B2 (en) Pretreatment and pre-cooling of natural gas by high pressure compression and expansion
WO2022099233A1 (fr) Procédés et systèmes de liquéfaction de gaz naturel comprenant une compression, une détente et un recyclage de charge
US10571187B2 (en) Temperature controlled method to liquefy gas and a production plant using the method
WO2023063991A1 (fr) Système et procédé de production de gaz naturel liquéfié
AU2008294046B2 (en) Natural gas liquefaction process
WO2023063992A1 (fr) Système et procédé de production de gaz naturel liquéfié
WO2023063993A1 (fr) Système et procédé de production de gaz naturel liquéfié
WO2023069139A1 (fr) Système et procédé de production de gaz naturel liquéfié
WO2023161705A1 (fr) Procédé de production de gnl réfrigérant mélangé unique

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21790053

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21790053

Country of ref document: EP

Kind code of ref document: A1