EP3322948A1 - Process for expansion and storage of a flow of liquefied natural gas from a natural gas liquefaction plant, and associated plant - Google Patents

Process for expansion and storage of a flow of liquefied natural gas from a natural gas liquefaction plant, and associated plant

Info

Publication number
EP3322948A1
EP3322948A1 EP16741582.7A EP16741582A EP3322948A1 EP 3322948 A1 EP3322948 A1 EP 3322948A1 EP 16741582 A EP16741582 A EP 16741582A EP 3322948 A1 EP3322948 A1 EP 3322948A1
Authority
EP
European Patent Office
Prior art keywords
stream
gas
natural gas
flash
bypass
Prior art date
Legal status (The legal status 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 status listed.)
Pending
Application number
EP16741582.7A
Other languages
German (de)
French (fr)
Inventor
Sylvain Vovard
Vincent TIRILLY
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Technip Energies France SAS
Original Assignee
Technip France SAS
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 Technip France SAS filed Critical Technip France SAS
Publication of EP3322948A1 publication Critical patent/EP3322948A1/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C9/00—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure
    • F17C9/02—Methods or apparatus for discharging liquefied or solidified gases from vessels not under pressure with change of state, e.g. vaporisation
    • F17C9/04—Recovery of thermal energy
    • 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
    • F25J1/0002—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
    • F25J1/0025—Boil-off gases "BOG" from storages
    • 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
    • F25J1/003—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"
    • F25J1/004—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 flash gas recovery
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0042—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by liquid expansion with extraction of work
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—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
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0262—Details of the cold heat exchange system
    • F25J1/0264—Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams
    • 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
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0269—Arrangement of liquefaction units or equipments fulfilling the same process step, e.g. multiple "trains" concept
    • F25J1/0271—Inter-connecting multiple cold equipments within or downstream of the cold box
    • 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
    • F25J1/0257—Construction and layout of liquefaction equipments, e.g. valves, machines
    • F25J1/0275—Construction and layout of liquefaction equipments, e.g. valves, machines adapted for special use of the liquefaction unit, e.g. portable or transportable devices
    • F25J1/0277—Offshore use, e.g. during shipping
    • F25J1/0278—Unit being stationary, e.g. on floating barge or fixed platform
    • 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F25J3/0214—Liquefied natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2221/00—Handled fluid, in particular type of fluid
    • F17C2221/03—Mixtures
    • F17C2221/032—Hydrocarbons
    • F17C2221/033—Methane, e.g. natural gas, CNG, LNG, GNL, GNC, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/01—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the phase
    • F17C2223/0146—Two-phase
    • F17C2223/0153—Liquefied gas, e.g. LPG, GPL
    • F17C2223/0161—Liquefied gas, e.g. LPG, GPL cryogenic, e.g. LNG, GNL, PLNG
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2223/00—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel
    • F17C2223/03—Handled fluid before transfer, i.e. state of fluid when stored in the vessel or before transfer from the vessel characterised by the pressure level
    • F17C2223/033—Small pressure, e.g. for liquefied gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/02—Mixing fluids
    • F17C2265/022—Mixing fluids identical fluid
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2265/00—Effects achieved by gas storage or gas handling
    • F17C2265/03—Treating the boil-off
    • F17C2265/032—Treating the boil-off by recovery
    • F17C2265/033—Treating the boil-off by recovery with cooling
    • F17C2265/034—Treating the boil-off by recovery with cooling with condensing the gas phase
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C2270/00—Applications
    • F17C2270/01—Applications for fluid transport or storage
    • F17C2270/0134—Applications for fluid transport or storage placed above the ground
    • F17C2270/0136—Terminals
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/76—Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/04—Recovery of liquid products
    • 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
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • 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
    • F25J2240/30—Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
    • 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
    • F25J2245/90—Processes or apparatus involving steps for recycling of process streams the recycled stream being boil-off gas from storage
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/88—Quasi-closed internal refrigeration or heat pump cycle, if not otherwise provided

Definitions

  • the present invention relates to a method for expanding and storing a stream of liquefied natural gas from a natural gas liquefaction plant, comprising the following steps:
  • Such a method is intended in particular to be implemented in floating facilities for producing liquefied natural gas, or in liquefaction facilities on land, having a small footprint.
  • liquefied natural gas production plants currently in operation, natural gas is condensed and subcooled under high pressure, before being flashed to atmospheric pressure.
  • the liquefied natural gas thus obtained can be stored at atmospheric pressure and at a cryogenic temperature, typically of the order of -160 ° C.
  • the expansion is performed either directly at the liquefied natural gas storage tank, or in a dedicated unit, for example a flash gas recovery unit.
  • the steam generated by the expansion is recovered, then compressed in a dedicated compressor to form a fuel gas stream, or to be recycled within the liquefaction train.
  • another stream of steam is generated in the liquefied natural gas storage tank, because of the pressure difference between the liquid directly from the expansion and that present in the storage tank and / or because of the reheating liquefied natural gas during transportation to the tank.
  • a gaseous flow of evaporation gas from the tank is thus recovered and is compressed in another dedicated compressor, to form a fuel gas stream or to be recycled within the unit, especially when the unit is a floating unit. .
  • DE102010062050 discloses a method in which flash gas gas stream and evaporation gas gas stream are mixed and then compressed together in a common compressor to form the fuel gas stream.
  • An object of the invention is therefore to obtain a particularly compact and economical method for recovering flash gases and evaporation gases from a natural gas liquefaction plant by the use of one or more dedicated compressors. (s) both functions.
  • the subject of the invention is a process of the aforementioned type comprising the following steps:
  • the method according to the invention comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:
  • the at least partially liquid expanded bypass stream is introduced into a downstream separator tank, the process comprising the following steps:
  • the flow of evaporation gas is introduced into the downstream heat exchanger to be placed in heat exchange relation with the first flow;
  • the flash end capacity is a flash end balloon or flash end distillation column
  • the expansion device comprises a dynamic expansion turbine
  • the molar flow rate of the first part of the treated natural gas stream is less than 10% of the molar flow rate of the expanded liquefied natural gas stream coming from the expansion device.
  • the invention also relates to a facility for expanding and storing a stream of liquefied natural gas from a natural gas liquefaction plant, comprising:
  • an expansion device capable of flashing off the stream of liquefied natural gas to form a stream of liquefied natural gas expanded
  • a flash end capacity capable of receiving the stream of liquefied natural gas expanded from the expansion device
  • a recovery assembly at the top of the liquefied natural gas reservoir, of a gaseous flow of evaporation gas
  • At least one compressing apparatus capable of compressing the mixing gas stream to form a stream of compressed fuel gas
  • At least one downstream compressor for compressing the bypass stream and forming a compressed bypass stream
  • a downstream heat exchanger for cooling the compressed bypass stream to form a relaxed bypass stream
  • the installation according to the invention comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:
  • the first flow consists of the entire relaxed bypass stream
  • a collection assembly at the top of the downstream separator flask, of the first stream in gaseous form, and of reintroduction of the first stream into the gaseous mixing stream and / or into at least one of the evaporation gas gas stream and a gaseous flow of flash gas upstream of the compression apparatus;
  • a recovery assembly at the bottom of the downstream separator balloon, of a second liquid bypass flow, and of introduction of the bypass liquid flow into the expanded liquefied natural gas stream, upstream of the flash end balloon;
  • the downstream heat exchanger is adapted to put in heat exchange relationship the first stream, and at least a portion of a treated gas stream to be liquefied;
  • FIG. 1 is a block diagram of a first installation intended for the implementation of a first method according to the invention
  • FIGS. 2 to 6 are block diagrams of plant variants for the implementation of process variants according to the invention.
  • upstream and downstream generally extend with respect to the normal direction of flow of a fluid.
  • the additional turbines which are described drive compressors, but may also lead to variable frequency electric generators whose electricity produced can be used in the network via a frequency converter.
  • the ambient temperature prevailing around the installation is not significant under the invention and may be in particular between 15 ° C and 35 ° C.
  • a first facility 10 for relaxing and storing liquefied natural gas from a natural gas liquefaction plant 12 is illustrated schematically in FIG.
  • the installations 10, 12 are advantageously carried by a support 14 located on the surface of a body of water, such as a sea, a lake, an ocean or a river.
  • the support 14 is for example a floating barge and is a floating unit for liquefaction of natural gas (FLNG).
  • the liquefaction plant 12 comprises, in a known manner, a unit 16 for treating natural gas, capable of producing a treated gas devoid of compounds capable of solidifying during liquefaction, and a liquefaction unit 18 for the treated gas, comprising at least one system (not shown). ) of cooling, liquefying, and subcooling the treated gas 20, capable of producing a stream 22 of liquefied natural gas under pressure.
  • the expansion and storage installation 10 comprises an expansion device 24 of the pressurized liquefied natural gas stream 22, here comprising a dynamic expansion turbine 25 and a flash end capacity, in this particular example a end balloon 26. of flash. It also comprises at least one tank 28 for recovering liquefied natural gas, and a compression apparatus 30, able to recover and compress both the flash gas from the balloon 26 and the evaporation gas from the each reservoir 28, to form a compressed fuel gas stream 32.
  • the installation 10 further comprises a downstream compressor 34, intended to compress a bypass stream 36 taken from the stream of compressed fuel gas 32, and at least one dynamic expansion turbine 38, suitable for relaxing the bypass current 36.
  • the installation 10 further comprises a downstream heat exchanger 40 and an additional heat exchanger 41 intended for the liquefaction of at least a portion of the treated gas 20, using the cold produced during the dynamic expansion of the bypass current 36 in the turbine 38.
  • the exchangers 40 and 41 are intended for cooling and at least partial liquefaction of a part of the bypass stream 36, when an excess of flash gas and or evaporation gas is present in the stream of compressed fuel gas 32.
  • the stream of liquefied natural gas 22 has a pressure for example greater than 60 bar, and may be between 40 bar and 80 bar.
  • Stream 22 is subcooled.
  • the temperature of the liquefied natural gas stream 22 is typically less than -150 ° C but may be between -140 ° C and -160 ° C.
  • Stream 22 preferably has a methane molar content greater than 80%, and a molar content of C 4 + less than 5%.
  • the molar flow rate of the liquefied natural gas stream 22 is, for example, greater than 10,000 kmol / h.
  • the liquefied natural gas stream 22 is conveyed to the dynamic expansion turbine 25 of the expansion device 24 to undergo flash expansion and form a stream 42 of expanded liquefied natural gas.
  • the pressure of the expanded liquefied natural gas stream 42 is for example less than 7 bar, in particular between 6 bar and 12 bar.
  • the expansion of the current 22 generates formation in the stream 42 of a residual flash gas downstream of the final expansion valve.
  • the molar content of flash gas in stream 42 is for example greater than 5% and is especially between 4% and 10%.
  • the current 42 is then introduced into the end flash balloon 26, to recover at the foot of the balloon 26, a liquid flow 46 of liquefied natural gas, and at the head of the balloon 26, a gas flow 48 flash gas.
  • the liquid flow 46 is then conveyed to a storage tank 28.
  • the flow 46 is pumped through a pump 50. In a variant, it flows by gravity into the reservoir 28, without to be pumped.
  • a residual evaporation gas (“boil off gas” in English) is formed from the liquid stream 46, in particular by heating the liquid flow 46 in the transport pipes by the heat inputs of the tank or tanks 28 and / or under the effect of a pressure difference between the tank 26 and the tank 28.
  • a gaseous stream 52 of evaporation gas is recovered at the top of the tank 28.
  • the gaseous evaporation gas stream 52 is heated in the downstream heat exchanger 40, for example to a temperature above -60 ° C.
  • the gas stream 48 of flash gas is heated in the additional heat exchanger 41, for example to a temperature above -60 ° C.
  • the gas flow 48 represents between 30 mol% and 80 mol% of the mixing gas stream 54.
  • the mixture gas stream 54 is then introduced into the compression apparatus 30 to form a compressed fuel gas stream 32.
  • the stream 54 passes successively through a first compressor 56, a first air-cooling exchanger or a water exchanger 58 to be cooled to ambient temperature, a second compressor 60, then a second exchanger 62 to be cooled again to room temperature or the water temperature.
  • the pressure of the stream of compressed fuel gas 32 is for example greater than 25 bar and is in particular between 5 bar and 70 bar.
  • the composition of stream 32 typically consists of 15 mol% of nitrogen and 85 mol% of methane.
  • the stream of compressed fuel gas 32 is then recovered for use as a fuel in the installation 12, or as a make-up fluid in this installation 12.
  • a bypass stream 36 is withdrawn from the fuel gas stream 32.
  • the molar flow rate of the bypass stream 36 is, for example, greater than 10% of the molar flow rate of the fuel gas stream 32 coming from the compression apparatus 30, and is in particular between 10% and 100% of this flow.
  • bypass stream 36 and then compressed in the compressor 34, and is then cooled to room temperature in the air-cooled exchanger or water exchanger 64, to form a compressed bypass stream 66.
  • the pressure of the compressed bypass stream 66 is, for example, 30 bars higher than the pressure of the stream 32.
  • the stream 66 is then introduced into the downstream heat exchanger 40 to be cooled to a temperature advantageously below -50 ° C.
  • the temperature of the stream 68 is preferably below -150 ° C. and is in particular between -140 ° C. and -160 ° C.
  • the expanded bypass stream 68 is optionally at least partially liquid.
  • the molar content of liquid in stream 68 is typically less than 15 mol%.
  • the stream 68 remains completely gaseous.
  • all of the expanded bypass stream 68 forms a first stream 70 which is then introduced into the downstream heat exchanger 40 for reheating.
  • the temperature of the first heated stream 71 is preferably greater than -60 ° C.
  • the first heated stream 71 is then reintroduced into the mixing stream 54, downstream of the flash end balloon 26, and upstream of the compression apparatus 30.
  • At least one gaseous stream of treated gas 72 from the plant 12 is diverted to the plant 10.
  • the gas stream 72 has a pressure for example greater than 60 bar, and especially between 40 bar and 90 bar.
  • the temperature of the gas stream typically equal to room temperature or pre-cooled.
  • the gas stream 72 has a molar methane content greater than 80%, and a molar content of C 4 + less than 5%.
  • the molar flow rate of the gas stream 72 may represent up to 10% of the flow rate of the initial charge of natural gas introduced into the liquefaction plant 12.
  • the gas stream 72 is then separated into a first portion 74 and a second portion 76.
  • the molar flow rate of the first portion 74 of the gas stream 72 constitutes, for example, between 20% and 50 mol% of the gaseous stream 72 and the molar flow rate of the second portion 76 of the gaseous stream 72 constitutes, for example, between 50% and 80% of the flow rate. molar of the gas stream 72.
  • the first portion 74 of the gas stream 72 is then introduced into the downstream heat exchanger 40 to be cooled and liquefied by heat exchange including the expanded bypass stream 68, to a temperature advantageously below -150 ° C.
  • the first part 74 then passes through a control valve 78, before being mixed with the stream of liquefied natural gas 42 expanded from the expansion device 24.
  • the second portion 76 of the gas stream 72 is introduced into the additional heat exchanger 41 to be cooled and liquefied by heat exchange with the gaseous flow flash gas 48, to a temperature advantageously below-150 ° C.
  • the second part 76 then passes through a control valve 80, before being mixed with the expanded liquefied natural gas stream 42 coming from the expansion device 24.
  • the implementation of the method according to the invention is therefore particularly simple since it reduces the number of equipment necessary to flash liquefied natural gas for storage, and to advantageously recover the flash gases and evaporation gas products.
  • a single compression apparatus 30 is used to compress a blending stream 54 formed from flash gases and evaporation gases.
  • bypass current 36 taken from the fuel stream 32 formed at the outlet of the compression apparatus 30 makes it possible to obtain a very efficient thermal integration, and to take advantage of the frigories available to liquefy at least partially the treated gas in the installation 12.
  • the thermal integration of the bypass current 36 makes it possible to adjust the frigories between the various operating modes of the installation 10, between the filling phases of the tanks, and the loading phases of a LNG carrier.
  • the method according to the invention and the installation 10 allowing its implementation are therefore particularly suitable for a floating unit such as FLNG.
  • a portion 90 of the gaseous evaporation gas stream is sent to other liquefaction trains.
  • a stream of liquefied natural gas 92 from other liquefaction trains is introduced into the tank 28.
  • a second installation 1 10 according to the invention is illustrated in Figure 2.
  • the second installation 1 10 differs from the first installation 10 in the sense that it comprises a downstream flask 1 12, placed at the outlet of the dynamic expansion turbine 38 .
  • the expanded bypass stream 68 is introduced into the downstream tank 1 12 to recover, at the head, the first stream 70 in gaseous form, and at the bottom, a second liquid stream 1 14.
  • the molar flow rate of the second stream 1 14 is, for example, between 10% and 15% of the molar flow rate of the expanded bypass stream 68.
  • the first stream 70 is introduced into the downstream heat exchanger 40 to be heated by heat exchange in particular with the first portion 74 of the gaseous stream 72 of treated gas.
  • the second stream 1 14 is reintroduced into the stream of liquefied natural gas 42 expanded from the expansion device 24, upstream of the flash end balloon 26.
  • the second method according to the invention optimizes the distribution of the liquid in the downstream heat exchanger 40.
  • FIG. 120 A third installation 120, intended for the implementation of a third method according to the invention, is illustrated in FIG.
  • a recirculation stream 122 is taken from the compressed bypass stream 66.
  • the recirculation stream 122 represents, for example, between 30% and 80 mol% of the compressed bypass stream 66 coming from the compressor 34.
  • the recirculation stream 122 is then separated into a first portion 124 and a second portion 126.
  • the molar flow rate of the first portion 124 of the recirculation stream 122 constitutes, for example, between 20% and 50 mol% of the recirculation stream 122 and the The molar flow rate of the second portion 126 of the recirculation stream 122 constitutes, for example, between 50% and 80% of the molar flow rate of the recirculation stream 122.
  • the first part 124 of the recirculation stream 122 is introduced into the downstream heat exchanger 40 to be cooled, and possibly at least partially liquefied, by heat exchange, in particular with the expanded bypass stream 68, to a temperature advantageously lower than -150 ° C.
  • the first portion 124 then passes through a control valve 128, before being mixed with the expanded liquefied natural gas stream 42 from the expansion device 24.
  • the second portion 126 of the bypass stream 122 is introduced into the additional heat exchanger 41, to be cooled and optionally at least partially liquefied by heat exchange with the flash gas gas flow 48, to a temperature advantageously less than -150 ° C.
  • the second portion 126 then passes through a control valve 130, before being mixed with the expanded liquefied natural gas stream 42 from the expansion device 24.
  • bypass stream 36 taken from the fuel stream 32 formed at the outlet of the compression apparatus 30 makes it possible to obtain a very efficient thermal integration, and to take advantage of the frigories available to liquefy at least partially a recirculation current 122 from the bypass current, when an excess of flash gas and / or evaporation gas occurs.
  • At least a portion 76 of the treated gas gas stream 72 coming from the installation 12 is also introduced into the additional heat exchanger 41, as described above for FIG. 2.
  • FIG. 4 A fourth installation 130, intended for the implementation of a fourth method according to the invention, is illustrated in FIG. 4.
  • This installation 130 differs from the installation 10 shown in FIG. 1 in that the flash end balloon 26 is replaced by a flash end distillation column 132.
  • a reboiler exchanger 134 is arranged upstream of the expansion device 24 to put the liquefied natural gas stream 22 in heat exchange relation with a reboilage stream 136 coming from the column 132.
  • FIG. 140 A fifth installation 140, intended for the implementation of a fifth method according to the invention, is illustrated in FIG. This installation 140 differs from the installation 120 shown in FIG. 3 in that the flash end balloon 26 is replaced by a flash end distillation column 132.
  • the implementation of the fifth method according to the invention is moreover analogous to that of the third method according to the invention.
  • FIG. 150 A sixth installation 150, intended for the implementation of a sixth method according to the invention, is illustrated in FIG.
  • the sixth installation 150 differs from the fourth installation 130 by the insertion of an intermediate balloon 152 between the outlet of the expansion device 24 and the inlet of the distillation column 132.
  • the intermediate balloon 152 receives the expanded liquefied natural gas stream 42 and separates it into a head stream 154, mixed with the flash gas gas stream 48, and a foot stream 156, introduced into the reboiler exchanger 134 beforehand. to reach the distillation column 132.
  • This installation 150 is beneficial for the recovery of helium in the case where the gas stream 154 is rich in helium, typically consisting of at least 25% helium, and can therefore be advantageously sent to a helium purification plant .
  • a downstream flask 1 12 is provided for separating the expanded bypass stream 68, as described in the second method according to the invention.
  • the dynamic expansion turbine 25 of the expansion device 24 is replaced by a static expansion valve.
  • the stream of liquefied natural gas then undergoes a static and non-dynamic expansion in the expansion device 24.
  • the method according to the invention and the corresponding installation are therefore particularly suitable for managing the large variations in temperature and flow rate of the evaporation gas stream 52 coming from the tank 28 between the loading phases of a tanker by emptying the tank. and the filling phases of the tank.
  • the thermal integration of the bypass current 36 with the evaporation gas stream 52 is used to adjust the required frigories, and to vary the relative flow rates of the fuel gas stream 32 and the bypass stream 36.

Abstract

The process comprises the following steps: - mixing a gaseous stream of flash gas (48) and a gaseous stream of evaporation gas (52) in order to form a mixed gaseous flow (54); - compression of the mixed gaseous flow (54) in at least one compression apparatus (30) in order to form a compressed fuel gas flow (32); - withdrawal of a bypass flow (36) in the compressed fuel gas flow (32); - compression of the bypass flow (36) in at least one downstream compressor (34); - cooling and expansion of the compressed bypass flow (66); - reheating of at least one first stream (68; 70) derived from the expanded bypass flow (68) in at least one downstream heat exchanger (40); - reintroduction of the reheated first stream (68; 70) into the mixed gaseous flow (54) upstream of the compression apparatus (30).

Description

Procédé de détente et de stockage d'un courant de gaz naturel liquéfié issu d'une installation de liquéfaction de gaz naturel, et installation associée Method for expanding and storing a stream of liquefied natural gas from a natural gas liquefaction plant, and associated facility
La présente invention concerne un procédé de détente et de stockage d'un courant de gaz naturel liquéfié issu d'une installation de liquéfaction de gaz naturel, comprenant les étapes suivantes : The present invention relates to a method for expanding and storing a stream of liquefied natural gas from a natural gas liquefaction plant, comprising the following steps:
- détente flash du courant de gaz naturel liquéfié dans un dispositif de détente pour former un courant de gaz naturel liquéfié détendu ;  flash relaxation of the stream of liquefied natural gas in an expansion device to form a stream of liquefied natural gas expanded;
- amenée du courant de gaz naturel liquéfié détendu dans une capacité de fin de flash ;  supply of the stream of liquefied natural gas expanded in a flash end capacity;
- récupération, en pied de la capacité de fin de flash, d'un flux liquide de gaz naturel liquéfié ;  recovering, at the end of the end flash capacity, a liquid stream of liquefied natural gas;
- convoyage du flux liquide de gaz naturel liquéfié dans au moins un réservoir de gaz naturel liquéfié ;  conveying the liquid flow of liquefied natural gas into at least one liquefied natural gas reservoir;
- prélèvement, en tête de la capacité de fin de flash, d'un flux gazeux de gaz de flash ;  - taking, at the end of the flash end capacity, a gas flow of flash gas;
- récupération, en tête du réservoir de gaz naturel liquéfié, d'un flux gazeux de gaz d'évaporation ;  recovering, at the head of the liquefied natural gas reservoir, a gaseous flow of evaporation gas;
- mélange du flux gazeux de gaz de flash et du flux gazeux de gaz d'évaporation pour former un courant gazeux de mélange ;  mixing the flash gas gas stream and the evaporation gas gas stream to form a mixture gas stream;
- compression du courant gazeux de mélange dans au moins un appareil de compression pour former un courant de gaz combustible comprimé.  compressing the mixture gas stream in at least one compression apparatus to form a compressed fuel gas stream.
Un tel procédé est destiné notamment à être mis en œuvre dans des installations flottantes de production de gaz naturel liquéfié, ou dans des installations de liquéfaction à terre, présentant un encombrement réduit.  Such a method is intended in particular to be implemented in floating facilities for producing liquefied natural gas, or in liquefaction facilities on land, having a small footprint.
Dans les usines de production de gaz naturel liquéfié actuellement en opération, le gaz naturel est condensé et sous-refroidi à haute pression, avant de subir une détente flash jusqu'à la pression atmosphérique. Le gaz naturel liquéfié ainsi obtenu peut être stocké à pression atmosphérique et à une température cryogénique, typiquement de l'ordre de -160 °C.  In liquefied natural gas production plants currently in operation, natural gas is condensed and subcooled under high pressure, before being flashed to atmospheric pressure. The liquefied natural gas thus obtained can be stored at atmospheric pressure and at a cryogenic temperature, typically of the order of -160 ° C.
La détente est effectuée soit directement au niveau du réservoir de stockage de gaz naturel liquéfié, soit dans une unité dédiée, par exemple une unité de récupération des gaz de flash.  The expansion is performed either directly at the liquefied natural gas storage tank, or in a dedicated unit, for example a flash gas recovery unit.
Dans une telle unité, la vapeur générée par la détente est récupérée, puis est comprimée dans un compresseur dédié pour former un courant de gaz combustible, ou pour être recyclée au sein du train de liquéfaction. Par ailleurs, un autre courant de vapeur est généré dans le réservoir de stockage de gaz naturel liquéfié, en raison de la différence de pression entre le liquide directement issu de la détente et celui présent dans le réservoir de stockage et/ou en raison du réchauffage du gaz naturel liquéfié lors de son transport vers le réservoir. In such a unit, the steam generated by the expansion is recovered, then compressed in a dedicated compressor to form a fuel gas stream, or to be recycled within the liquefaction train. Moreover, another stream of steam is generated in the liquefied natural gas storage tank, because of the pressure difference between the liquid directly from the expansion and that present in the storage tank and / or because of the reheating liquefied natural gas during transportation to the tank.
Un flux gazeux de gaz d'évaporation issu du réservoir est donc récupéré et est comprimé dans un autre compresseur dédié, pour former un courant de gaz combustible ou pour être recyclé au sein de l'unité, notamment lorsque l'unité est une unité flottante.  A gaseous flow of evaporation gas from the tank is thus recovered and is compressed in another dedicated compressor, to form a fuel gas stream or to be recycled within the unit, especially when the unit is a floating unit. .
Un tel procédé ne donne pas entière satisfaction, notamment dans un environnement flottant. En effet, la mise en œuvre du procédé nécessite plusieurs compresseurs distincts, souvent au moins trois compresseurs, ce qui est particulièrement encombrant, pesant, et ce qui augmente les coûts fixes et variables de l'installation.  Such a method is not entirely satisfactory, especially in a floating environment. Indeed, the implementation of the process requires several separate compressors, often at least three compressors, which is particularly bulky, weighing, and increasing the fixed and variable costs of the installation.
Pour pallier ce problème, DE102010062050 décrit un procédé dans lequel le flux gazeux de gaz de flash et le flux gazeux de gaz d'évaporation sont mélangés, puis sont comprimés conjointement dans un compresseur commun, pour former le courant de gaz combustible.  To overcome this problem, DE102010062050 discloses a method in which flash gas gas stream and evaporation gas gas stream are mixed and then compressed together in a common compressor to form the fuel gas stream.
Un tel procédé diminue l'encombrement de l'installation et réduit les coûts de mise en œuvre. Toutefois, le procédé n'est pas totalement optimisé en termes de rendement et de récupération du gaz naturel liquéfié.  Such a method reduces the overall size of the installation and reduces the costs of implementation. However, the process is not fully optimized in terms of efficiency and recovery of liquefied natural gas.
Un but de l'invention est donc d'obtenir un procédé particulièrement compact et économique de récupération des gaz de flash et des gaz d'évaporation issus d'une installation de liquéfaction de gaz naturel par l'usage d'un ou plusieurs compresseurs dédié(s) aux deux fonctions.  An object of the invention is therefore to obtain a particularly compact and economical method for recovering flash gases and evaporation gases from a natural gas liquefaction plant by the use of one or more dedicated compressors. (s) both functions.
A cet effet, l'invention a pour objet un procédé du type précité comprenant les étapes suivantes :  For this purpose, the subject of the invention is a process of the aforementioned type comprising the following steps:
- prélèvement d'un courant de dérivation dans le courant de gaz combustible comprimé ;  - taking a bypass current in the stream of compressed fuel gas;
- compression du courant de dérivation dans au moins un compresseur aval pour former un courant de dérivation comprimé ;  compressing the bypass current in at least one downstream compressor to form a compressed bypass stream;
- refroidissement du courant de dérivation comprimé ;  - cooling of the compressed bypass current;
- détente du courant de dérivation comprimé pour former un courant de dérivation détendu ;  - Relaxing the compressed bypass current to form a relaxed bypass current;
- réchauffage d'au moins un premier flux issu du courant de dérivation détendu dans au moins un échangeur thermique aval,  reheating of at least a first stream coming from the bypass stream expanded in at least one downstream heat exchanger,
- réintroduction du premier flux réchauffé dans le courant gazeux de mélange et/ou dans l'un au moins du flux gazeux de gaz d'évaporation et du flux gazeux de gaz de flash, en amont de l'appareil de compression. Suivant des modes particuliers de réalisation, le procédé selon l'invention comprend l'une ou plusieurs des caractéristiques suivantes, prise(s) isolément ou suivant toute combinaison techniquement possible : - Reintroduction of the first heated stream in the mixing gas stream and / or in at least one of the gaseous flow of evaporation gas and the gaseous flash gas stream, upstream of the compression apparatus. According to particular embodiments, the method according to the invention comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:
- le courant de dérivation détendu au moins partiellement liquide est introduit dans un ballon séparateur aval, le procédé comprenant les étapes suivantes :  the at least partially liquid expanded bypass stream is introduced into a downstream separator tank, the process comprising the following steps:
- prélèvement, en tête du ballon séparateur aval, du premier flux sous forme gazeuse, et réintroduction du premier flux dans le courant gazeux de mélange et/ou dans l'un au moins du flux gazeux de gaz d'évaporation et du flux gazeux de gaz de flash, en amont de l'appareil de compression ;  sampling, at the top of the downstream separator flask, of the first stream in gaseous form, and reintroduction of the first stream into the gaseous mixing stream and / or into at least one of the gas stream of evaporation gas and the gaseous stream of flash gas upstream of the compression apparatus;
- récupération, en pied du ballon séparateur aval, d'un deuxième flux liquide de dérivation, et introduction du flux liquide de dérivation dans le courant de gaz naturel liquéfié détendu, en amont de la capacité de fin de flash ;  recovering, at the bottom of the downstream separator balloon, a second liquid bypass flow, and introducing the bypass liquid flow into the expanded liquefied natural gas stream, upstream of the end flash capacity;
- la totalité du courant de dérivation détendu constitue le premier flux ;  the entire relaxed bypass current constitutes the first flow;
- le courant de dérivation comprimé issu du compresseur aval est introduit dans l'échangeur thermique aval pour être mis en relation d'échange thermique avec le premier flux ;  - The compressed bypass stream from the downstream compressor is introduced into the downstream heat exchanger to be placed in heat exchange relationship with the first flow;
- le flux de gaz d'évaporation est introduit dans l'échangeur thermique aval pour être mis en relation d'échange thermique avec le premier flux ;  the flow of evaporation gas is introduced into the downstream heat exchanger to be placed in heat exchange relation with the first flow;
- il comprend les étapes suivantes :  - it includes the following steps:
- fourniture d'un courant de gaz naturel traité destiné à être liquéfié ;  - supply of a stream of treated natural gas to be liquefied;
- introduction d'au moins une première partie du courant de gaz naturel traité dans l'échangeur thermique aval pour être mis en relation d'échange thermique avec le premier flux ;  - Introducing at least a first portion of the natural gas stream treated in the downstream heat exchanger to be in heat exchange relationship with the first flow;
- liquéfaction au moins partielle de la première partie du courant de gaz naturel traité dans l'échangeur thermique aval par échange thermique avec le premier flux ;  at least partial liquefaction of the first part of the treated natural gas stream in the downstream heat exchanger by heat exchange with the first stream;
- il comprend l'introduction de la première partie du courant de gaz naturel traité liquéfié dans le courant de gaz naturel liquéfié détendu issu du dispositif de détente, en amont d'une capacité de fin de flash ;  it comprises the introduction of the first part of the liquefied treated natural gas stream into the expanded liquefied natural gas stream coming from the expansion device, upstream of a flash end capacity;
- il comprend les étapes suivantes :  - it includes the following steps:
- séparation du courant de gaz naturel traité en la première partie du courant de gaz naturel traité et une deuxième partie du courant de gaz naturel traité ;  separating the treated natural gas stream into the first portion of the treated natural gas stream and a second portion of the treated natural gas stream;
- introduction de la deuxième partie du courant de gaz naturel traité dans un échangeur thermique additionnel, pour être mis en relation d'échange thermique avec le flux de gaz de flash ; - liquéfaction de la deuxième partie du courant de gaz naturel traité dans l'échangeur thermique additionnel par réchauffage du flux de gaz de flash ; - Introducing the second part of the treated natural gas stream into an additional heat exchanger, to be placed in heat exchange relation with the flash gas flow; - liquefaction of the second part of the treated natural gas stream in the additional heat exchanger by heating the flash gas flow;
- introduction de la deuxième partie du courant de gaz naturel traité liquéfiée dans le courant de gaz naturel liquéfié détendu issu du dispositif de détente, en amont de la capacité de fin de flash ;  introducing the second part of the liquefied treated natural gas stream into the expanded liquefied natural gas stream coming from the expansion device, upstream of the end flash capacity;
- il comprend également les étapes suivantes :  - it also includes the following steps:
- dérivation d'un courant de recirculation dans le courant de dérivation comprimé ; deriving a recirculation current in the compressed bypass stream;
- liquéfaction d'au moins une partie du courant de recirculation dans l'échangeur thermique aval par échange thermique avec le premier flux ; - Liquefaction of at least a portion of the recirculation stream in the downstream heat exchanger by heat exchange with the first flow;
- la capacité de fin de flash est un ballon de fin de flash ou une colonne de distillation de fin de flash ;  - the flash end capacity is a flash end balloon or flash end distillation column;
- le dispositif de détente comprend une turbine de détente dynamique ;  the expansion device comprises a dynamic expansion turbine;
- le débit molaire de la première partie du courant de gaz naturel traité est inférieur à 10% du débit molaire du courant de gaz naturel liquéfié détendu issu du dispositif de détente.  the molar flow rate of the first part of the treated natural gas stream is less than 10% of the molar flow rate of the expanded liquefied natural gas stream coming from the expansion device.
L'invention a également pour objet une installation de détente et de stockage d'un courant de gaz naturel liquéfié issu d'une installation de liquéfaction de gaz naturel, comprenant :  The invention also relates to a facility for expanding and storing a stream of liquefied natural gas from a natural gas liquefaction plant, comprising:
- un dispositif de détente propre à effectuer une détente flash du courant de gaz naturel liquéfié pour former un courant de gaz naturel liquéfié détendu ;  an expansion device capable of flashing off the stream of liquefied natural gas to form a stream of liquefied natural gas expanded;
- une capacité de fin de flash propre à recevoir le courant de gaz naturel liquéfié détendu provenant du dispositif de détente ;  a flash end capacity capable of receiving the stream of liquefied natural gas expanded from the expansion device;
- un ensemble de récupération, en pied de la capacité de fin de flash, d'un flux liquide de gaz naturel liquéfié ;  a recovery assembly, at the end of the flash end capacity, of a liquid stream of liquefied natural gas;
- au moins un réservoir de gaz naturel liquéfié et un ensemble de convoyage du flux liquide de gaz naturel liquéfié dans le réservoir de gaz naturel liquéfié ;  at least one liquefied natural gas reservoir and a conveying assembly for the liquid liquefied natural gas stream in the liquefied natural gas reservoir;
- un ensemble de prélèvement, en tête de la capacité de fin de flash, d'un flux gazeux de gaz de flash ;  a sampling assembly, at the end of the end-of-flash capacity, of a gas flow of flash gas;
- un ensemble de récupération, en tête du réservoir de gaz naturel liquéfié, d'un flux gazeux de gaz d'évaporation ;  a recovery assembly, at the top of the liquefied natural gas reservoir, of a gaseous flow of evaporation gas;
- un ensemble de mélange du flux gazeux de gaz de flash et du flux gazeux de gaz d'évaporation pour former un courant gazeux de mélange ;  a mixing assembly of the flash gas gas stream and the evaporation gas gas stream to form a mixture gas stream;
- au moins un appareil de compression propre à comprimer le courant gazeux de mélange pour former un courant de gaz combustible comprimé,  at least one compressing apparatus capable of compressing the mixing gas stream to form a stream of compressed fuel gas,
caractérisée par : - un ensemble de prélèvement d'un courant de dérivation dans le courant de gaz combustible comprimé ; characterized by: - a set of sampling a bypass current in the stream of compressed fuel gas;
- au moins un compresseur aval pour comprimer le courant de dérivation et former un courant de dérivation comprimé ;  at least one downstream compressor for compressing the bypass stream and forming a compressed bypass stream;
- un échangeur thermique aval de refroidissement du courant de dérivation comprimé pour former un courant de dérivation détendu ;  a downstream heat exchanger for cooling the compressed bypass stream to form a relaxed bypass stream;
- un dispositif de détente et de liquéfaction au moins partielle du courant de dérivation comprimée ;  a device for at least partial expansion and liquefaction of the compressed bypass stream;
- un ensemble d'introduction d'au moins un premier flux issu du courant de dérivation détendu dans l'échangeur thermique aval, pour permettre le réchauffage du premier flux,  a set of introduction of at least a first stream coming from the bypass stream expanded in the downstream heat exchanger, to allow the heating of the first stream,
- un ensemble de réintroduction du premier flux dans le courant gazeux de mélange et/ou dans l'un au moins du flux gazeux de gaz d'évaporation et du flux gazeux de gaz de flash, en amont de l'appareil de compression.  - A set of reintroduction of the first stream in the mixing gas stream and / or in at least one of the gas stream of evaporation gas and the flash gas gas stream, upstream of the compression apparatus.
Suivant des modes particuliers de réalisation, l'installation selon l'invention comprend l'une ou plusieurs des caractéristiques suivantes, prise(s) isolément ou suivant toute combinaison techniquement possible :  According to particular embodiments, the installation according to the invention comprises one or more of the following characteristics, taken in isolation or in any technically possible combination:
- le premier flux est constitué par la totalité du courant de dérivation détendu ; the first flow consists of the entire relaxed bypass stream;
- elle comprend : - she understands :
- un ballon séparateur aval,  a downstream separator tank,
- un ensemble de prélèvement, en tête du ballon séparateur aval, du premier flux sous forme gazeuse, et de réintroduction du premier flux dans le courant gazeux de mélange et/ou dans l'un au moins du flux gazeux de gaz d'évaporation et du flux gazeux de gaz de flash, en amont de l'appareil de compression ;  a collection assembly, at the top of the downstream separator flask, of the first stream in gaseous form, and of reintroduction of the first stream into the gaseous mixing stream and / or into at least one of the evaporation gas gas stream and a gaseous flow of flash gas upstream of the compression apparatus;
- un ensemble de récupération, en pied du ballon séparateur aval, d'un deuxième flux liquide de dérivation, et d'introduction du flux liquide de dérivation dans le courant de gaz naturel liquéfié détendu, en amont du ballon de fin de flash ;  a recovery assembly, at the bottom of the downstream separator balloon, of a second liquid bypass flow, and of introduction of the bypass liquid flow into the expanded liquefied natural gas stream, upstream of the flash end balloon;
- l'échangeur thermique aval est propre à mettre en relation d'échange thermique le premier flux, et au moins une partie d'un courant de gaz traité destiné à être liquéfié ;  - The downstream heat exchanger is adapted to put in heat exchange relationship the first stream, and at least a portion of a treated gas stream to be liquefied;
- elle comprend :  - she understands :
- un ensemble de dérivation d'un courant de recirculation à partir du courant de dérivation comprimé ; - un ensemble d'introduction d'au moins une partie du courant de recirculation dans l'échangeur thermique aval pour le liquéfier au moins partiellement dans l'échangeur thermique aval. - a set of derivation of a recirculation current from the compressed bypass stream; - A set of introduction of at least a portion of the recirculation stream in the downstream heat exchanger to liquefy at least partially in the downstream heat exchanger.
L'invention sera mieux comprise à la lecture de la description qui va suivre, donnée uniquement à titre d'exemple, et faite en se référant aux dessins annexés, sur lesquels :  The invention will be better understood on reading the description which follows, given solely by way of example, and with reference to the appended drawings, in which:
- la figure 1 est un schéma synoptique d'une première installation destinée à la mise en œuvre d'un premier procédé selon l'invention ;  FIG. 1 is a block diagram of a first installation intended for the implementation of a first method according to the invention;
- les figures 2 à 6 sont des schémas synoptiques de variantes d'installations destinées à la mise en œuvre de variantes de procédés selon l'invention.  - Figures 2 to 6 are block diagrams of plant variants for the implementation of process variants according to the invention.
Dans tout ce qui suit, on désignera par les mêmes références un courant circulant dans une conduite et la conduite qui le transporte. Les termes « amont » et «aval » s'étendent généralement par rapport au sens normal de circulation d'un fluide.  In all that follows, we will designate by the same references a current flowing in a pipe and the pipe that carries it. The terms "upstream" and "downstream" generally extend with respect to the normal direction of flow of a fluid.
En outre, sauf indication contraire, les pourcentages cités sont des pourcentages molaires, et les pressions sont données en bars absolus.  In addition, unless otherwise indicated, the percentages mentioned are molar percentages, and the pressures are given in absolute bar.
Les turbines additionnelles qui sont décrites entraînent des compresseurs, mais peuvent également entraîner des générateurs électriques à fréquence variable dont l'électricité produite peut être utilisée dans le réseau par l'intermédiaire d'un convertisseur de fréquence.  The additional turbines which are described drive compressors, but may also lead to variable frequency electric generators whose electricity produced can be used in the network via a frequency converter.
Les courants dont la température est supérieure à l'ambiante sont décrits comme étant refroidis par des aéro-réfrigérants. En variante, il est possible d'utiliser des échangeurs à eau, par exemple à eau douce ou à eau de mer.  Currents with a temperature above ambient are described as being cooled by aero-refrigerants. Alternatively, it is possible to use water exchangers, for example freshwater or seawater.
La température ambiante régnant autour de l'installation n'est pas significative au titre de l'invention et peut être comprise notamment entre 15°C et 35°C.  The ambient temperature prevailing around the installation is not significant under the invention and may be in particular between 15 ° C and 35 ° C.
Une première installation 10 de détente et de stockage de gaz naturel liquéfié issu d'une installation 12 de liquéfaction de gaz naturel est illustrée schématiquement par la figure 1 .  A first facility 10 for relaxing and storing liquefied natural gas from a natural gas liquefaction plant 12 is illustrated schematically in FIG.
Les installations 10, 12 sont avantageusement portées par un support 14 situé à la surface d'une étendue d'eau, tel qu'une mer, un lac, un océan ou une rivière. Le support 14 est par exemple une barge flottante et constitue une unité flottante de liquéfaction de gaz naturel (FLNG).  The installations 10, 12 are advantageously carried by a support 14 located on the surface of a body of water, such as a sea, a lake, an ocean or a river. The support 14 is for example a floating barge and is a floating unit for liquefaction of natural gas (FLNG).
L'installation de liquéfaction 12 n'est pas décrite ici en détail. Elle comporte de manière connue une unité 16 de traitement du gaz naturel, propre à produire un gaz traité dépourvu de composés propres à se solidifier lors de la liquéfaction, et une unité 18 de liquéfaction du gaz traité, comprenant au moins un système (non représenté) de refroidissement, de liquéfaction, et de sous-refroidissement du gaz traité 20, propre à produire un courant 22 de gaz naturel liquéfié sous pression. The liquefaction plant 12 is not described here in detail. It comprises, in a known manner, a unit 16 for treating natural gas, capable of producing a treated gas devoid of compounds capable of solidifying during liquefaction, and a liquefaction unit 18 for the treated gas, comprising at least one system (not shown). ) of cooling, liquefying, and subcooling the treated gas 20, capable of producing a stream 22 of liquefied natural gas under pressure.
L'installation 10 de détente et de stockage comporte un dispositif de détente 24 du courant de gaz naturel liquéfié sous pression 22, comprenant ici une turbine de détente dynamique 25 et une capacité de fin de flash, dans cet exemple particulier un ballon 26 de fin de flash. Elle comporte par ailleurs au moins un réservoir 28 de récupération de gaz naturel liquéfié, et un appareil de compression 30, propre à récupérer et à comprimer à la fois le gaz de flash issu du ballon 26 et le gaz d'évaporation issu du ou de chaque réservoir 28, pour former un courant de gaz combustible 32 comprimé.  The expansion and storage installation 10 comprises an expansion device 24 of the pressurized liquefied natural gas stream 22, here comprising a dynamic expansion turbine 25 and a flash end capacity, in this particular example a end balloon 26. of flash. It also comprises at least one tank 28 for recovering liquefied natural gas, and a compression apparatus 30, able to recover and compress both the flash gas from the balloon 26 and the evaporation gas from the each reservoir 28, to form a compressed fuel gas stream 32.
Selon l'invention, l'installation 10 comporte en outre, un compresseur aval 34, destiné à comprimer un courant de dérivation 36 prélevé dans le courant de gaz combustible comprimé 32, et au moins une turbine de détente dynamique 38, propre à détendre le courant de dérivation 36.  According to the invention, the installation 10 further comprises a downstream compressor 34, intended to compress a bypass stream 36 taken from the stream of compressed fuel gas 32, and at least one dynamic expansion turbine 38, suitable for relaxing the bypass current 36.
Dans l'exemple représenté sur la figure 1 , l'installation 10 comporte en outre un échangeur thermique aval 40 et un échangeur thermique additionnel 41 destinés à la liquéfaction d'au moins une partie du gaz traité 20, à l'aide du froid produit lors de la détente dynamique du courant de dérivation 36 dans la turbine 38.  In the example shown in FIG. 1, the installation 10 further comprises a downstream heat exchanger 40 and an additional heat exchanger 41 intended for the liquefaction of at least a portion of the treated gas 20, using the cold produced during the dynamic expansion of the bypass current 36 in the turbine 38.
En variante ou en complément, comme décrit plus bas sur la figure 3, les échangeurs 40 et 41 sont destinés au refroidissement et à la liquéfaction au moins partielle d'une partie du courant de dérivation 36, lorsqu'un excédent de gaz de flash et/ou de gaz d'évaporation est présent dans le courant de gaz combustible comprimé 32.  Alternatively or in addition, as described below in FIG. 3, the exchangers 40 and 41 are intended for cooling and at least partial liquefaction of a part of the bypass stream 36, when an excess of flash gas and or evaporation gas is present in the stream of compressed fuel gas 32.
Un premier procédé selon l'invention de détente et de stockage du courant de gaz naturel liquéfié 22, mis en œuvre dans l'installation 10, va maintenant être décrit.  A first method according to the invention for expanding and storing the liquefied natural gas stream 22, implemented in the installation 10, will now be described.
Initialement, un courant de gaz naturel liquéfié 22 sous pression est produit par l'installation 12.  Initially, a stream of liquefied natural gas 22 under pressure is produced by the plant 12.
Le courant de gaz naturel liquéfié 22 présente une pression par exemple supérieure à 60 bar, et peut être compris entre 40 bar et 80 bar.  The stream of liquefied natural gas 22 has a pressure for example greater than 60 bar, and may be between 40 bar and 80 bar.
Le courant 22 est sous-refroidi. La température du courant de gaz naturel liquéfié 22 est typiquement inférieure à -150 °C mais peut être comprise entre -140° C et -160° C.  Stream 22 is subcooled. The temperature of the liquefied natural gas stream 22 is typically less than -150 ° C but may be between -140 ° C and -160 ° C.
Le courant 22 possède avantageusement une teneur molaire en méthane supérieure à 80 %, et une teneur molaire en C4 + inférieure à 5 %. Stream 22 preferably has a methane molar content greater than 80%, and a molar content of C 4 + less than 5%.
Le débit molaire du courant de gaz naturel liquéfié 22 est par exemple supérieur à 10000 kmol/h.  The molar flow rate of the liquefied natural gas stream 22 is, for example, greater than 10,000 kmol / h.
Le courant de gaz naturel liquéfié 22 est convoyé jusqu'à la turbine de détente dynamique 25 du dispositif de détente 24 pour y subir une détente flash et former un courant 42 de gaz naturel liquéfié détendu. La pression du courant de gaz naturel liquéfié détendu 42 est par exemple inférieure à 7 bar, notamment comprise entre 6 bar et 12 bar. The liquefied natural gas stream 22 is conveyed to the dynamic expansion turbine 25 of the expansion device 24 to undergo flash expansion and form a stream 42 of expanded liquefied natural gas. The pressure of the expanded liquefied natural gas stream 42 is for example less than 7 bar, in particular between 6 bar and 12 bar.
La détente du courant 22 engendre la formation dans le courant 42 d'un gaz de flash résiduel en aval de la vanne de détente finale. La teneur molaire en gaz de flash dans le courant 42 est par exemple supérieure à 5 % et est notamment comprise entre 4 % et 10 %.  The expansion of the current 22 generates formation in the stream 42 of a residual flash gas downstream of the final expansion valve. The molar content of flash gas in stream 42 is for example greater than 5% and is especially between 4% and 10%.
Le courant 42 est ensuite introduit dans le ballon 26 de fin de flash, pour récupérer, au pied du ballon 26, un flux liquide 46 de gaz naturel liquéfié, et en tête du ballon 26, un flux gazeux 48 de gaz de flash.  The current 42 is then introduced into the end flash balloon 26, to recover at the foot of the balloon 26, a liquid flow 46 of liquefied natural gas, and at the head of the balloon 26, a gas flow 48 flash gas.
Le flux liquide 46 est alors convoyé vers un réservoir de stockage 28. Dans l'exemple présenté sur la figure 1 , le flux 46 est pompé à travers une pompe 50. En variante, il s'écoule par gravité dans le réservoir 28, sans être pompé.  The liquid flow 46 is then conveyed to a storage tank 28. In the example shown in FIG. 1, the flow 46 is pumped through a pump 50. In a variant, it flows by gravity into the reservoir 28, without to be pumped.
Lors de son transport, et de son introduction dans le réservoir 28, un gaz d'évaporation résiduel (« boil off gas » en anglais) se forme à partir du flux liquide 46, notamment par réchauffage du flux liquide 46 dans les conduites de transport, par les entrées de chaleurs du ou des réservoirs 28 et/ou sous l'effet d'une différence de pression entre le ballon 26 et le réservoir 28.  During its transport, and its introduction into the tank 28, a residual evaporation gas ("boil off gas" in English) is formed from the liquid stream 46, in particular by heating the liquid flow 46 in the transport pipes by the heat inputs of the tank or tanks 28 and / or under the effect of a pressure difference between the tank 26 and the tank 28.
Un flux gazeux 52 de gaz d'évaporation est récupéré en tête du réservoir 28. Le flux gazeux de gaz évaporation 52 est réchauffé dans l'échangeur thermique aval 40, par exemple jusqu'à une température supérieure à -60 °C.  A gaseous stream 52 of evaporation gas is recovered at the top of the tank 28. The gaseous evaporation gas stream 52 is heated in the downstream heat exchanger 40, for example to a temperature above -60 ° C.
Le flux gazeux 48 de gaz de flash est réchauffé dans l'échangeur thermique additionnel 41 , par exemple jusqu'à une température supérieure à -60°C.  The gas stream 48 of flash gas is heated in the additional heat exchanger 41, for example to a temperature above -60 ° C.
Il est ensuite mélangé avec le flux gazeux 52 de gaz d'évaporation pour former un courant de gaz de mélange 54.  It is then mixed with the gas stream 52 of evaporation gas to form a mixture gas stream 54.
Le flux gazeux 48 représente entre 30% molaire et 80% molaire du courant de gaz de mélange 54.  The gas flow 48 represents between 30 mol% and 80 mol% of the mixing gas stream 54.
Le courant de gaz de mélange 54 est ensuite introduit dans l'appareil de compression 30 pour former un courant de gaz combustible comprimé 32.  The mixture gas stream 54 is then introduced into the compression apparatus 30 to form a compressed fuel gas stream 32.
Dans l'exemple représenté sur la figure 1 , le courant 54 passe successivement à travers un premier compresseur 56, un premier échangeur aéroréfrigérant ou un échangeur à eau 58 pour être refroidi jusqu'à la température ambiante, un deuxième compresseur 60, puis un deuxième échangeur 62 pour être refroidi à nouveau jusqu'à la température ambiante ou la température de l'eau.  In the example shown in FIG. 1, the stream 54 passes successively through a first compressor 56, a first air-cooling exchanger or a water exchanger 58 to be cooled to ambient temperature, a second compressor 60, then a second exchanger 62 to be cooled again to room temperature or the water temperature.
La pression du courant de gaz combustible comprimé 32 est par exemple supérieure à 25 bar et est notamment comprise entre 5 bar et 70 bar. Dans un exemple particulier, la composition du courant 32 est typiquement constituée de 15% molaire d'azote et de 85% molaire de méthane. The pressure of the stream of compressed fuel gas 32 is for example greater than 25 bar and is in particular between 5 bar and 70 bar. In a particular example, the composition of stream 32 typically consists of 15 mol% of nitrogen and 85 mol% of methane.
Le courant de gaz combustible comprimé 32 est alors récupéré pour être utilisé comme combustible dans l'installation 12, ou encore comme fluide d'appoint dans cette installation 12.  The stream of compressed fuel gas 32 is then recovered for use as a fuel in the installation 12, or as a make-up fluid in this installation 12.
Un courant de dérivation 36 est prélevé dans le courant de gaz combustible 32. Le débit molaire du courant de dérivation 36 est par exemple supérieur à 10 % du débit molaire du courant de gaz combustible 32 issu de l'appareil de compression 30, et est notamment compris entre 10 % et 100 % de ce débit.  A bypass stream 36 is withdrawn from the fuel gas stream 32. The molar flow rate of the bypass stream 36 is, for example, greater than 10% of the molar flow rate of the fuel gas stream 32 coming from the compression apparatus 30, and is in particular between 10% and 100% of this flow.
Le courant de dérivation 36 et ensuite comprimé dans le compresseur 34, puis est refroidi jusqu'à la température ambiante dans l'échangeur aéro-réfrigérant ou l'échangeur à eau 64, pour former un courant de dérivation comprimé 66.  The bypass stream 36 and then compressed in the compressor 34, and is then cooled to room temperature in the air-cooled exchanger or water exchanger 64, to form a compressed bypass stream 66.
La pression du courant de dérivation comprimé 66 est par exemple supérieure de 30 bar à la pression du courant 32.  The pressure of the compressed bypass stream 66 is, for example, 30 bars higher than the pressure of the stream 32.
Le courant 66 est ensuite introduit dans l'échangeur thermique aval 40 pour y être refroidi jusqu'à une température avantageusement inférieure à -50 °C.  The stream 66 is then introduced into the downstream heat exchanger 40 to be cooled to a temperature advantageously below -50 ° C.
Il est ensuite détendu dans la turbine de détente dynamique 38, jusqu'à une pression inférieure à 2 bar et est notamment comprise entre 1 ,1 bar et 3 bar, pour former un courant de dérivation détendu 68.  It is then expanded in the dynamic expansion turbine 38 to a pressure of less than 2 bar and is in particular between 1.1 bar and 3 bar to form a relaxed bypass stream 68.
La température du courant 68 est de préférence inférieure à -150 °C et est notamment comprise entre -140° C et -160° C.  The temperature of the stream 68 is preferably below -150 ° C. and is in particular between -140 ° C. and -160 ° C.
Le courant de dérivation détendu 68 est éventuellement au moins partiellement liquide. Dans ce cas, la teneur molaire en liquide dans le courant 68 est typiquement inférieure à 15 % molaire. En variante, le courant 68 reste totalement gazeux.  The expanded bypass stream 68 is optionally at least partially liquid. In this case, the molar content of liquid in stream 68 is typically less than 15 mol%. Alternatively, the stream 68 remains completely gaseous.
Dans cet exemple, la totalité du courant de dérivation détendu 68 forme un premier flux 70 qui est ensuite introduit dans l'échangeur thermique aval 40 pour y être réchauffé. La température du premier flux réchauffé 71 est avantageusement supérieure à à -60 °C.  In this example, all of the expanded bypass stream 68 forms a first stream 70 which is then introduced into the downstream heat exchanger 40 for reheating. The temperature of the first heated stream 71 is preferably greater than -60 ° C.
Le premier flux réchauffé 71 est ensuite réintroduit dans le courant de mélange 54, en aval du ballon de fin de flash 26, et en amont de l'appareil de compression 30.  The first heated stream 71 is then reintroduced into the mixing stream 54, downstream of the flash end balloon 26, and upstream of the compression apparatus 30.
Dans ce mode de réalisation, au moins un courant gazeux de gaz traité 72 issu de l'installation 12 est dérivé vers l'installation 10.  In this embodiment, at least one gaseous stream of treated gas 72 from the plant 12 is diverted to the plant 10.
Le courant gazeux 72 présente une pression par exemple supérieure à 60 bar, et notamment comprise entre 40 bar et 90 bar. La température du courant gazeux typiquement égale à la température ambiante ou pré-refroidie. Le courant gazeux 72 possède une teneur molaire en méthane supérieure à 80 %, et une teneur molaire en C4 + inférieure à 5 %. The gas stream 72 has a pressure for example greater than 60 bar, and especially between 40 bar and 90 bar. The temperature of the gas stream typically equal to room temperature or pre-cooled. The gas stream 72 has a molar methane content greater than 80%, and a molar content of C 4 + less than 5%.
Le débit molaire du courant gazeux 72 peut représenter jusqu'à 10 % du débit de la charge initiale de gaz naturel introduite dans l'installation de liquéfaction 12.  The molar flow rate of the gas stream 72 may represent up to 10% of the flow rate of the initial charge of natural gas introduced into the liquefaction plant 12.
Le courant gazeux 72 est ensuite séparé en une première partie 74 et en une deuxième partie 76.  The gas stream 72 is then separated into a first portion 74 and a second portion 76.
Le débit molaire de la première partie 74 du courant gazeux 72 constitue par exemple entre 20 % et 50 % molaire du courant gazeux 72 et le débit molaire de la deuxième partie 76 du courant gazeux 72 constitue par exemple entre 50 % et 80 % du débit molaire du courant gazeux 72.  The molar flow rate of the first portion 74 of the gas stream 72 constitutes, for example, between 20% and 50 mol% of the gaseous stream 72 and the molar flow rate of the second portion 76 of the gaseous stream 72 constitutes, for example, between 50% and 80% of the flow rate. molar of the gas stream 72.
La première partie 74 du courant gazeux 72 est ensuite introduite dans l'échangeur thermique aval 40 pour y être refroidie et liquéfiée par échange thermique notamment avec le courant de dérivation détendu 68, jusqu'à une température avantageusement inférieure à -150 °C.  The first portion 74 of the gas stream 72 is then introduced into the downstream heat exchanger 40 to be cooled and liquefied by heat exchange including the expanded bypass stream 68, to a temperature advantageously below -150 ° C.
La première partie 74 passe ensuite à travers une vanne de contrôle 78, avant d'être mélangée au courant de gaz naturel liquéfié détendu 42 issu du dispositif de détente 24.  The first part 74 then passes through a control valve 78, before being mixed with the stream of liquefied natural gas 42 expanded from the expansion device 24.
La deuxième partie 76 du courant gazeux 72 est introduite dans l'échangeur thermique additionnel 41 pour y être refroidie et liquéfiée par échange thermique avec le flux gazeux de gaz de flash 48, jusqu'à une température avantageusement inférieure à - 150 °C.  The second portion 76 of the gas stream 72 is introduced into the additional heat exchanger 41 to be cooled and liquefied by heat exchange with the gaseous flow flash gas 48, to a temperature advantageously below-150 ° C.
La deuxième partie 76 passe ensuite à travers une vanne de contrôle 80, avant d'être mélangée au courant de gaz naturel liquéfié détendu 42 issu du dispositif de détente 24.  The second part 76 then passes through a control valve 80, before being mixed with the expanded liquefied natural gas stream 42 coming from the expansion device 24.
La mise en œuvre du procédé selon l'invention est donc particulièrement simple puisqu'elle diminue le nombre d'équipements nécessaires pour effectuer un flash du gaz naturel liquéfié en vue de son stockage, et pour récupérer de manière avantageuse les gaz de flash et les gaz d'évaporation produits.  The implementation of the method according to the invention is therefore particularly simple since it reduces the number of equipment necessary to flash liquefied natural gas for storage, and to advantageously recover the flash gases and evaporation gas products.
En particulier, un appareil de compression unique 30 est utilisé pour comprimer un courant de mélange 54 formé à partir des gaz de flash et des gaz d'évaporation.  In particular, a single compression apparatus 30 is used to compress a blending stream 54 formed from flash gases and evaporation gases.
L'utilisation d'un courant de dérivation 36 prélevé dans le courant de combustible 32 formé à la sortie de l'appareil de compression 30 permet d'obtenir une intégration thermique très efficace, et de profiter des frigories disponibles pour liquéfier au moins partiellement le gaz traité dans l'installation 12. L'intégration thermique du courant de dérivation 36 permet d'ajuster les frigories entre les différents modes de fonctionnement de l'installation 10, entre les phases de remplissage des bacs, et les phases de chargement d'un méthanier The use of a bypass current 36 taken from the fuel stream 32 formed at the outlet of the compression apparatus 30 makes it possible to obtain a very efficient thermal integration, and to take advantage of the frigories available to liquefy at least partially the treated gas in the installation 12. The thermal integration of the bypass current 36 makes it possible to adjust the frigories between the various operating modes of the installation 10, between the filling phases of the tanks, and the loading phases of a LNG carrier.
Le procédé selon l'invention et l'installation 10 permettant sa mise en œuvre sont donc particulièrement adaptés pour une unité flottante telle qu'une FLNG.  The method according to the invention and the installation 10 allowing its implementation are therefore particularly suitable for a floating unit such as FLNG.
Dans une variante, représentée schématiquement sur la figure 1 , une partie 90 du flux gazeux de gaz évaporation est envoyée vers d'autres trains de liquéfaction. À l'inverse, un courant de gaz naturel liquéfié 92 provenant d'autres trains de liquéfaction est introduit dans le réservoir 28.  In a variant, shown schematically in FIG. 1, a portion 90 of the gaseous evaporation gas stream is sent to other liquefaction trains. In contrast, a stream of liquefied natural gas 92 from other liquefaction trains is introduced into the tank 28.
Une deuxième installation 1 10 selon l'invention est illustrée par la figure 2. La deuxième installation 1 10 diffère de la première installation 10 dans le sens où elle comprend un ballon aval 1 12, placé à la sortie de la turbine de détente dynamique 38.  A second installation 1 10 according to the invention is illustrated in Figure 2. The second installation 1 10 differs from the first installation 10 in the sense that it comprises a downstream flask 1 12, placed at the outlet of the dynamic expansion turbine 38 .
Le courant de dérivation détendu 68 est introduit dans le ballon aval 1 12 pour récupérer, en tête, le premier flux 70 sous forme gazeuse, et en pied, un deuxième flux 1 14 liquide.  The expanded bypass stream 68 is introduced into the downstream tank 1 12 to recover, at the head, the first stream 70 in gaseous form, and at the bottom, a second liquid stream 1 14.
Le débit molaire du deuxième flux 1 14 constitue par exemple entre 10% et 15% du débit molaire du courant de dérivation détendu 68.  The molar flow rate of the second stream 1 14 is, for example, between 10% and 15% of the molar flow rate of the expanded bypass stream 68.
Comme précédemment, le premier flux 70 est introduit dans l'échangeur thermique aval 40 pour être réchauffé par échange thermique notamment avec la première partie 74 du courant gazeux 72 de gaz traité.  As previously, the first stream 70 is introduced into the downstream heat exchanger 40 to be heated by heat exchange in particular with the first portion 74 of the gaseous stream 72 of treated gas.
Le deuxième flux 1 14 est réintroduit dans le courant de gaz naturel liquéfié détendu 42 issu de l'appareil de détente 24, en amont du ballon de fin de flash 26.  The second stream 1 14 is reintroduced into the stream of liquefied natural gas 42 expanded from the expansion device 24, upstream of the flash end balloon 26.
Le deuxième procédé selon l'invention optimise la distribution du liquide dans l'échangeur thermique aval 40.  The second method according to the invention optimizes the distribution of the liquid in the downstream heat exchanger 40.
Une troisième installation 120, destinée à la mise en œuvre d'un troisième procédé selon l'invention, est illustrée par la figure 3.  A third installation 120, intended for the implementation of a third method according to the invention, is illustrated in FIG.
À la différence du premier procédé mis en œuvre dans l'installation 10 décrite sur la figure 1 , un courant 122 de recirculation est prélevé dans le courant de dérivation comprimé 66.  Unlike the first method implemented in the installation 10 described in FIG. 1, a recirculation stream 122 is taken from the compressed bypass stream 66.
Le courant de recirculation 122 représente par exemple entre 30% et 80% molaire du courant de dérivation comprimé 66 issu du compresseur 34.  The recirculation stream 122 represents, for example, between 30% and 80 mol% of the compressed bypass stream 66 coming from the compressor 34.
Le courant de recirculation 122 est ensuite séparé en une première partie 124 et en une deuxième partie 126.  The recirculation stream 122 is then separated into a first portion 124 and a second portion 126.
Le débit molaire de la première partie 124 du courant de recirculation 122 constitue par exemple entre 20% et 50 % molaire du courant de recirculation 122 et le débit molaire de la deuxième partie 126 du courant de recirculation 122 constitue par exemple entre 50% et 80% du débit molaire du courant de recirculation 122. The molar flow rate of the first portion 124 of the recirculation stream 122 constitutes, for example, between 20% and 50 mol% of the recirculation stream 122 and the The molar flow rate of the second portion 126 of the recirculation stream 122 constitutes, for example, between 50% and 80% of the molar flow rate of the recirculation stream 122.
La première partie 124 du courant de recirculation 122 est introduite dans l'échangeur thermique aval 40 pour y être refroidie, et éventuellement au moins partiellement liquéfiée, par échange thermique notamment avec le courant de dérivation détendu 68, jusqu'à une température avantageusement inférieure à -150°C.  The first part 124 of the recirculation stream 122 is introduced into the downstream heat exchanger 40 to be cooled, and possibly at least partially liquefied, by heat exchange, in particular with the expanded bypass stream 68, to a temperature advantageously lower than -150 ° C.
La première partie 124 passe ensuite à travers une vanne de contrôle 128, avant d'être mélangée au courant de gaz naturel liquéfié détendu 42 issu du dispositif de détente 24.  The first portion 124 then passes through a control valve 128, before being mixed with the expanded liquefied natural gas stream 42 from the expansion device 24.
La deuxième partie 126 du courant de dérivation 122 est introduite dans l'échangeur thermique additionnel 41 , pour y être refroidie et éventuellement au moins partiellement liquéfiée par échange thermique avec le flux gazeux de gaz de flash 48, jusqu'à une température avantageusement inférieure à -150°C.  The second portion 126 of the bypass stream 122 is introduced into the additional heat exchanger 41, to be cooled and optionally at least partially liquefied by heat exchange with the flash gas gas flow 48, to a temperature advantageously less than -150 ° C.
La deuxième partie 126 passe ensuite à travers une vanne de contrôle 130, avant d'être mélangée au courant de gaz naturel liquéfié détendu 42 issu du dispositif de détente 24.  The second portion 126 then passes through a control valve 130, before being mixed with the expanded liquefied natural gas stream 42 from the expansion device 24.
L'utilisation d'un courant de dérivation 36 prélevé dans le courant de combustible 32 formé à la sortie de l'appareil de compression 30 permet d'obtenir une intégration thermique très efficace, et de profiter des frigories disponibles pour liquéfier au moins partiellement un courant de recirculation 122 issu du courant de dérivation, lorsqu'un excès de gaz de flash et/ou de gaz d'évaporation se produit.  The use of a bypass stream 36 taken from the fuel stream 32 formed at the outlet of the compression apparatus 30 makes it possible to obtain a very efficient thermal integration, and to take advantage of the frigories available to liquefy at least partially a recirculation current 122 from the bypass current, when an excess of flash gas and / or evaporation gas occurs.
Dans une variante représentée en pointillés sur la figure 3, au moins une partie 76 du courant gazeux de gaz traité 72 issu de l'installation 12 est également introduite dans l'échangeur thermique additionnel 41 , comme décrit plus haut pour la figure 2.  In a variant shown in dashed lines in FIG. 3, at least a portion 76 of the treated gas gas stream 72 coming from the installation 12 is also introduced into the additional heat exchanger 41, as described above for FIG. 2.
Une quatrième installation 130, destinée à la mise en œuvre d'un quatrième procédé selon l'invention, est illustrée par la figure 4.  A fourth installation 130, intended for the implementation of a fourth method according to the invention, is illustrated in FIG. 4.
Cette installation 130 diffère de l'installation 10 représentée sur la figure 1 en ce que le ballon de fin de flash 26 est remplacé par une colonne de distillation 132 de fin de flash.  This installation 130 differs from the installation 10 shown in FIG. 1 in that the flash end balloon 26 is replaced by a flash end distillation column 132.
Un échangeur de rebouillage 134 est disposé en amont du dispositif de détente 24 pour mettre en relation d'échange thermique le courant de gaz naturel liquéfié 22 avec un courant de rebouillage 136 issu de la colonne 132.  A reboiler exchanger 134 is arranged upstream of the expansion device 24 to put the liquefied natural gas stream 22 in heat exchange relation with a reboilage stream 136 coming from the column 132.
La mise en œuvre du quatrième procédé selon l'invention est par ailleurs analogue à celle du premier procédé selon l'invention.  The implementation of the fourth method according to the invention is moreover analogous to that of the first method according to the invention.
Une cinquième installation 140, destinée à la mise en œuvre d'un cinquième procédé selon l'invention, est illustrée par la figure 5. Cette installation 140 diffère de l'installation 120 représentée sur la figure 3 en ce que le ballon de fin de flash 26 est remplacé par une colonne de distillation 132 de fin de flash. A fifth installation 140, intended for the implementation of a fifth method according to the invention, is illustrated in FIG. This installation 140 differs from the installation 120 shown in FIG. 3 in that the flash end balloon 26 is replaced by a flash end distillation column 132.
La mise en œuvre du cinquième procédé selon l'invention est par ailleurs analogue à celle du troisième procédé selon l'invention.  The implementation of the fifth method according to the invention is moreover analogous to that of the third method according to the invention.
Une sixième installation 150, destinée à la mise en œuvre d'un sixième procédé selon l'invention, est illustrée par la figure 6.  A sixth installation 150, intended for the implementation of a sixth method according to the invention, is illustrated in FIG.
La sixième installation 150 diffère de la quatrième installation 130 par l'insertion d'un ballon intermédiaire 152 entre la sortie du dispositif de détente 24 et l'entrée de la colonne de distillation 132.  The sixth installation 150 differs from the fourth installation 130 by the insertion of an intermediate balloon 152 between the outlet of the expansion device 24 and the inlet of the distillation column 132.
Le ballon intermédiaire 152 reçoit le courant de gaz naturel liquéfié détendu 42 et le sépare en un flux de tête 154, mélangé au flux gazeux 48 de gaz de flash, et en un flux de pied 156, introduit dans l'échangeur de rebouillage 134 avant d'atteindre la colonne de distillation 132.  The intermediate balloon 152 receives the expanded liquefied natural gas stream 42 and separates it into a head stream 154, mixed with the flash gas gas stream 48, and a foot stream 156, introduced into the reboiler exchanger 134 beforehand. to reach the distillation column 132.
Cette installation 150 est bénéfique pour la récupération d'hélium dans le cas où le courant gazeux 154 est riche en hélium, typiquement constitué d'au moins 25% d'hélium, et peut donc être avantageusement envoyé dans une installation de purification d'hélium.  This installation 150 is beneficial for the recovery of helium in the case where the gas stream 154 is rich in helium, typically consisting of at least 25% helium, and can therefore be advantageously sent to a helium purification plant .
Dans des variantes de chacune des installations 120 à 150, un ballon aval 1 12 est prévu pour séparer le courant de dérivation détendu 68, comme décrit dans le deuxième procédé selon l'invention.  In variants of each of the installations 120 to 150, a downstream flask 1 12 is provided for separating the expanded bypass stream 68, as described in the second method according to the invention.
Dans une variante des installations décrites plus haut, la turbine de détente dynamique 25 du dispositif de détente 24 est remplacée par une vanne de détente statique. Le courant de gaz naturel liquéfié subit alors une détente statique et non dynamique dans le dispositif de détente 24.  In a variant of the installations described above, the dynamic expansion turbine 25 of the expansion device 24 is replaced by a static expansion valve. The stream of liquefied natural gas then undergoes a static and non-dynamic expansion in the expansion device 24.
Le procédé selon l'invention et l'installation correspondante sont donc particulièrement adaptés pour gérer les variations importantes de température et de débit du flux de gaz d'évaporation 52 provenant du réservoir 28 entre les phases de chargement d'un méthanier par vidange du réservoir et les phases de remplissage du réservoir.  The method according to the invention and the corresponding installation are therefore particularly suitable for managing the large variations in temperature and flow rate of the evaporation gas stream 52 coming from the tank 28 between the loading phases of a tanker by emptying the tank. and the filling phases of the tank.
Comme indiqué plus haut, l'intégration thermique du courant de dérivation 36 avec le courant de gaz d'évaporation 52 est utilisée pour ajuster les frigories nécessaires, et faire varier les débits relatifs du courant de gaz combustible 32 et du courant de dérivation 36.  As indicated above, the thermal integration of the bypass current 36 with the evaporation gas stream 52 is used to adjust the required frigories, and to vary the relative flow rates of the fuel gas stream 32 and the bypass stream 36.
Ceci est obtenu sans avoir à modifier de paramètres opératoires pour la liquéfaction du gaz naturel, notamment au niveau des cycles principaux de liquéfaction.  This is achieved without having to modify operating parameters for the liquefaction of natural gas, especially at the level of the main liquefaction cycles.

Claims

REVENDICATIONS
1 .- Procédé de détente et de stockage d'un courant de gaz naturel liquéfié (22) issu d'une installation (12) de liquéfaction de gaz naturel, comprenant les étapes suivantes : 1 .- A method of relaxing and storing a stream of liquefied natural gas (22) from a facility (12) for liquefying natural gas, comprising the following steps:
- détente flash du courant de gaz naturel liquéfié (22) dans un dispositif de détente (24) pour former un courant de gaz naturel liquéfié détendu (42) ;  flashing the liquefied natural gas stream (22) into an expansion device (24) to form a expanded liquefied natural gas stream (42);
- amenée du courant de gaz naturel liquéfié détendu (42) dans une capacité de fin de flash (26 ; 132) ;  supplying the expanded liquefied natural gas stream (42) into a flash end capacity (26; 132);
- récupération, en pied de la capacité de fin de flash (26 ; 132), d'un flux liquide de gaz naturel liquéfié (46) ;  recovering, at the foot of the flash end capacitance (26; 132), a liquid stream of liquefied natural gas (46);
- convoyage du flux liquide de gaz naturel liquéfié (46) dans au moins un réservoir de gaz naturel liquéfié (28) ;  conveying the liquefied natural gas liquid stream (46) into at least one liquefied natural gas tank (28);
- prélèvement, en tête de la capacité de fin de flash (26 ; 132), d'un flux gazeux de gaz de flash (48) ;  - taking, at the top of the end flash capacity (26; 132), a gaseous flow of flash gas (48);
- récupération, en tête du réservoir de gaz naturel liquéfié (28), d'un flux gazeux de gaz d'évaporation (52) ;  recovering, at the head of the liquefied natural gas reservoir (28), a gaseous flow of evaporation gas (52);
- mélange du flux gazeux de gaz de flash (48) et du flux gazeux de gaz d'évaporation (52) pour former un courant gazeux de mélange (54);  mixing the flash gas gas stream (48) and the evaporation gas gas stream (52) to form a mixture gas stream (54);
- compression du courant gazeux de mélange (54) dans au moins un appareil de compression (30) pour former un courant de gaz combustible comprimé (32) ;  compressing the mixing gas stream (54) into at least one compression apparatus (30) to form a compressed fuel gas stream (32);
caractérisé par les étapes suivantes :  characterized by the following steps:
- prélèvement d'un courant de dérivation (36) dans le courant de gaz combustible comprimé (32) ;  - withdrawing a bypass current (36) in the stream of compressed fuel gas (32);
- compression du courant de dérivation (36) dans au moins un compresseur aval - compression of the bypass current (36) in at least one downstream compressor
(34) pour former un courant de dérivation comprimé (66) ; (34) to form a compressed bypass stream (66);
- refroidissement du courant de dérivation comprimé (66) ;  - cooling the compressed bypass current (66);
- détente du courant de dérivation comprimé (66) pour former un courant de dérivation détendu (68);  - Relaxing the compressed bypass current (66) to form a relaxed bypass stream (68);
- réchauffage d'au moins un premier flux (68 ; 70) issu du courant de dérivation détendu (68) dans au moins un échangeur thermique aval (40),  - heating at least a first stream (68; 70) from the expanded bypass stream (68) into at least one downstream heat exchanger (40),
- réintroduction du premier flux (68 ; 70) réchauffé dans le courant gazeux de mélange (54) et/ou dans l'un au moins du flux gazeux de gaz d'évaporation (52) et du flux gazeux de gaz de flash (48), en amont de l'appareil de compression (30). reintroduction of the first stream (68; 70) heated in the mixing gas stream (54) and / or in at least one of the gaseous evaporation gas stream (52) and the gaseous flash gas stream (48); ), upstream of the compression apparatus (30).
2. - Procédé selon la revendication 1 , dans lequel le courant de dérivation détendu (68) au moins partiellement liquide est introduit dans un ballon séparateur aval (1 12), le procédé comprenant les étapes suivantes : 2. - The method of claim 1, wherein the at least partially liquid expanded bypass stream (68) is introduced into a downstream separator tank (1 12), the method comprising the following steps:
- prélèvement, en tête du ballon séparateur aval (1 12), du premier flux (70) sous forme gazeuse, et réintroduction du premier flux (70) dans le courant gazeux de mélange - sampling, at the top of the downstream separator tank (1 12), the first stream (70) in gaseous form, and reintroduction of the first stream (70) in the mixing gas stream
(54) et/ou dans l'un au moins du flux gazeux de gaz d'évaporation (52) et du flux gazeux de gaz de flash (48), en amont de l'appareil de compression (30) ; (54) and / or in at least one of the evaporation gas gas stream (52) and the flash gas gas stream (48), upstream of the compression apparatus (30);
- récupération, en pied du ballon séparateur aval (1 12), d'un deuxième flux liquide (1 14) de dérivation, et introduction du flux liquide de dérivation (1 14) dans le courant (42) de gaz naturel liquéfié détendu, en amont de la capacité de fin de flash (26 ; 132).  recovering, at the bottom of the downstream separator tank (1 12), a second liquid bypass flow (1 14), and introducing the bypass liquid flow (1 14) into the stream (42) of expanded liquefied natural gas, upstream of the flash end capacity (26; 132).
3. - Procédé selon la revendication 1 , dans lequel la totalité du courant de dérivation détendu (68) constitue le premier flux (70).  The method of claim 1, wherein the entire relaxed bypass stream (68) constitutes the first stream (70).
4. - Procédé selon l'une quelconque des revendications précédentes, dans lequel le courant de dérivation comprimé (66) issu du compresseur aval (34) est introduit dans l'échangeur thermique aval (40) pour être mis en relation d'échange thermique avec le premier flux (70).  4. - Method according to any one of the preceding claims, wherein the compressed bypass stream (66) from the downstream compressor (34) is introduced into the downstream heat exchanger (40) to be placed in heat exchange relationship with the first stream (70).
5. - Procédé selon l'une quelconque des revendications précédentes, dans lequel le flux de gaz d'évaporation (52) est introduit dans l'échangeur thermique aval (40) pour être mis en relation d'échange thermique avec le premier flux (70).  5. - Process according to any one of the preceding claims, wherein the flow of evaporation gas (52) is introduced into the downstream heat exchanger (40) to be placed in heat exchange relationship with the first flow ( 70).
6. - Procédé selon l'une quelconque des revendications précédentes, comprenant les étapes suivantes :  6. - Method according to any one of the preceding claims, comprising the following steps:
- fourniture d'un courant de gaz naturel traité (72) destiné à être liquéfié ;  supplying a stream of treated natural gas (72) to be liquefied;
- introduction d'au moins une première partie (74) du courant de gaz naturel traité (72) dans l'échangeur thermique aval (40) pour être mis en relation d'échange thermique avec le premier flux (70) ;  - Introducing at least a first portion (74) of the treated natural gas stream (72) into the downstream heat exchanger (40) to be in heat exchange relationship with the first stream (70);
- liquéfaction au moins partielle de la première partie (74) du courant de gaz naturel traité (72) dans l'échangeur thermique aval (40) par échange thermique avec le premier flux (68 ; 70).  - At least partial liquefaction of the first portion (74) of the treated natural gas stream (72) in the downstream heat exchanger (40) by heat exchange with the first stream (68; 70).
7. - Procédé selon la revendication 6, comprenant l'introduction de la première partie (74) du courant de gaz naturel traité (72) liquéfié dans le courant de gaz naturel liquéfié détendu (42) issu du dispositif de détente (24), en amont d'une capacité de fin de flash (26 ; 132).  The method of claim 6 comprising introducing the first portion (74) of the liquefied treated natural gas stream (72) into the expanded liquefied natural gas stream (42) from the expansion device (24), upstream of a flash end capacitance (26; 132).
8. - Procédé selon la revendication 6 ou 7, comprenant les étapes suivantes : 8. - Method according to claim 6 or 7, comprising the following steps:
- séparation du courant de gaz naturel traité en la première partie (74) du courant de gaz naturel traité (72) et une deuxième partie (76) du courant de gaz naturel traité (72) - introduction de la deuxième partie (76) du courant de gaz naturel traité (72) dans un échangeur thermique additionnel (41 ), pour être mis en relation d'échange thermique avec le flux de gaz de flash (48) ; - separation of the treated natural gas stream into the first portion (74) of the treated natural gas stream (72) and a second portion (76) of the treated natural gas stream (72) - introducing the second portion (76) of the treated natural gas stream (72) into an additional heat exchanger (41) to be in heat exchange relationship with the flash gas flow (48);
- liquéfaction de la deuxième partie (76) du courant de gaz naturel traité (72) dans l'échangeur thermique additionnel (41 ) par réchauffage du flux de gaz de flash (48) ;  - liquefying the second portion (76) of the treated natural gas stream (72) in the additional heat exchanger (41) by reheating the flash gas flow (48);
- introduction de la deuxième partie (76) du courant de gaz naturel traité (72) liquéfiée dans le courant de gaz naturel liquéfié détendu (42) issu du dispositif de détente (24), en amont de la capacité de fin de flash (26 ; 132).  - Introducing the second portion (76) of the liquefied treated natural gas stream (72) into the expanded liquefied natural gas stream (42) from the expansion device (24), upstream of the flash end capacity (26). 132).
9.- Procédé selon l'une quelconque des revendications précédentes, comprenant les étapes suivantes :  The method of any one of the preceding claims, comprising the steps of:
- dérivation d'un courant de recirculation (122) dans le courant de dérivation comprimé (66) ;  deriving a recirculation current (122) in the compressed bypass stream (66);
- liquéfaction d'au moins une partie (124) du courant de recirculation (122) dans l'échangeur thermique aval (40) par échange thermique avec le premier flux (68 ; 70).  - liquefying at least a portion (124) of the recirculation stream (122) in the downstream heat exchanger (40) by heat exchange with the first stream (68; 70).
10. - Procédé selon l'une quelconque des revendications précédentes, dans lequel la capacité de fin de flash (26 ; 132) est un ballon de fin de flash (26) ou une colonne de distillation de fin de flash (132).  The method of any of the preceding claims, wherein the flash end capacitance (26; 132) is a flash end balloon (26) or a flash end distillation column (132).
1 1 . - Procédé selon l'une quelconque des revendications précédentes, dans lequel le dispositif de détente (24) comprend une turbine de détente dynamique (25).  1 1. - Method according to any one of the preceding claims, wherein the expansion device (24) comprises a dynamic expansion turbine (25).
12. - Installation de détente et de stockage d'un courant de gaz naturel liquéfié issu d'une installation (12) de liquéfaction de gaz naturel, comprenant  12. - Installation for expansion and storage of a stream of liquefied natural gas from a facility (12) for liquefying natural gas, comprising
- un dispositif de détente (24) propre à effectuer une détente flash du courant de gaz naturel liquéfié (22) pour former un courant de gaz naturel liquéfié détendu (42);  - an expansion device (24) adapted to flash a flash of the liquefied natural gas stream (22) to form a expanded liquefied natural gas stream (42);
- une capacité de fin de flash (26 ; 132) propre à recevoir le courant de gaz naturel liquéfié détendu (42) provenant du dispositif de détente (24) ;  a flash end capacitance (26; 132) adapted to receive the expanded liquefied natural gas stream (42) from the flash device (24);
- un ensemble de récupération, en pied de la capacité de fin de flash (26 ; 132), d'un flux liquide de gaz naturel liquéfié (46) ;  - a recovery unit, at the foot of the end flash capacity (26; 132), a liquid flow of liquefied natural gas (46);
- au moins un réservoir de gaz naturel liquéfié (28) et un ensemble de convoyage du flux liquide de gaz naturel liquéfié (46) dans le réservoir de gaz naturel liquéfié (28) ;  at least one liquefied natural gas reservoir (28) and a liquefied natural gas liquid stream conveying assembly (46) in the liquefied natural gas reservoir (28);
- un ensemble de prélèvement, en tête de la capacité de fin de flash (26 ; 132), d'un flux gazeux de gaz de flash (48) ;  a sampling assembly, at the top of the flash end capacitance (26; 132), of a gaseous flow of flash gas (48);
- un ensemble de récupération, en tête du réservoir de gaz naturel liquéfié (28), d'un flux gazeux de gaz d'évaporation (52) ;  a recovery assembly, at the top of the liquefied natural gas reservoir (28), of a gaseous flow of evaporation gas (52);
- un ensemble de mélange du flux gazeux de gaz de flash (48) et du flux gazeux de gaz d'évaporation (52) pour former un courant gazeux de mélange (54) ; - au moins un appareil de compression (30) propre à comprimer le courant gazeux de mélange (54) pour former un courant de gaz combustible comprimé (32) ; - a mixture of flash gas gas flow (48) and evaporative gas gas flow (52) to form a mixture gas stream (54); at least one compression apparatus (30) adapted to compress the mixing gas stream (54) to form a compressed fuel gas stream (32);
caractérisée par :  characterized by:
- un ensemble de prélèvement d'un courant de dérivation (36) dans le courant de gaz combustible comprimé (32) ;  - a collection set of a bypass current (36) in the stream of compressed fuel gas (32);
- au moins un compresseur aval (34) pour comprimer le courant de dérivation (36) et former un courant de dérivation comprimé (66) ;  at least one downstream compressor (34) for compressing the bypass stream (36) and forming a compressed bypass stream (66);
- un échangeur thermique aval (40) de refroidissement du courant de dérivation comprimé (66) pour former un courant de dérivation détendu (68) ;  - a downstream heat exchanger (40) for cooling the compressed bypass stream (66) to form a relaxed bypass stream (68);
- un dispositif de détente et de liquéfaction au moins partielle du courant de dérivation comprimée (66) ;  a device for at least partial expansion and liquefaction of the compressed bypass stream (66);
- un ensemble d'introduction d'au moins un premier flux (68 ; 70) issu du courant de dérivation détendu (68) dans l'échangeur thermique aval (40), pour permettre le réchauffage du premier flux (68 ; 70),  - an introduction assembly of at least a first stream (68; 70) from the expanded bypass stream (68) in the downstream heat exchanger (40), to allow heating of the first stream (68; 70),
- un ensemble de réintroduction du premier flux (68 ; 70) dans le courant gazeux de mélange (54) et/ou dans l'un au moins du flux gazeux de gaz d'évaporation (52) et du flux gazeux de gaz de flash (48), en amont de l'appareil de compression (30) ;  a set of reintroduction of the first stream (68; 70) in the mixing gas stream (54) and / or in at least one of the evaporation gas gas stream (52) and the flash gas gas stream (48) upstream of the compression apparatus (30);
13. - Installation selon la revendication 12, dans laquelle le premier flux (68) est constitué par la totalité du courant de dérivation détendu (68).  13. - Installation according to claim 12, wherein the first stream (68) is constituted by all of the expanded bypass stream (68).
14. - Installation selon la revendication 12, comprenant :  14. - Installation according to claim 12, comprising:
- un ballon séparateur aval (1 12),  a downstream separator tank (1 12),
- un ensemble de prélèvement, en tête du ballon séparateur aval (1 12), du premier flux (70) sous forme gazeuse, et de réintroduction du premier flux (70) dans le courant gazeux de mélange (54) et/ou dans l'un au moins du flux gazeux de gaz d'évaporation (52) et du flux gazeux de gaz de flash (48), en amont de l'appareil de compression (30) ;  a collection assembly, at the top of the downstream separator tank (1 12), of the first stream (70) in gaseous form, and of reintroduction of the first stream (70) in the mixing gas stream (54) and / or in the at least one of the evaporation gas gas stream (52) and the flash gas gas stream (48) upstream of the compression apparatus (30);
- un ensemble de récupération, en pied du ballon séparateur aval (1 12), d'un deuxième flux liquide (1 14) de dérivation, et d'introduction du flux liquide de dérivation (1 14) dans le courant (42) de gaz naturel liquéfié détendu, en amont du ballon de fin de flash (26 ; 132).  - a recovery assembly, at the bottom of the downstream separator tank (1 12), a second liquid flow (1 14) bypass, and introduction of the liquid bypass flow (1 14) in the stream (42) of liquefied natural gas expanded upstream of the end flash balloon (26; 132).
15. - Installation selon l'une quelconque des revendications 12 à 14, dans laquelle l'échangeur thermique aval (40) est propre à mettre en relation d'échange thermique le premier flux (68 ; 70), et au moins une partie (74) d'un courant de gaz traité (72) destiné à être liquéfié.  15. - Installation according to any one of claims 12 to 14, wherein the downstream heat exchanger (40) is adapted to put in heat exchange relationship the first stream (68; 70), and at least a part ( 74) of a treated gas stream (72) to be liquefied.
16. - Installation selon l'une quelconque des revendications 12 à 14, comprenant : - un ensemble de dérivation d'un courant de recirculation (122) à partir du courant de dérivation comprimé (66) ; - un ensemble d'introduction d'au moins une partie (124) du courant de recirculation (122) dans l'échangeur thermique aval (40) pour le liquéfier au moins partiellement dans l'échangeur thermique aval (40). 16. - Installation according to any one of claims 12 to 14, comprising: - a set of derivation of a recirculation current (122) from the compressed bypass stream (66); - A set of introduction of at least a portion (124) of the recirculation stream (122) in the downstream heat exchanger (40) to liquefy at least partially in the downstream heat exchanger (40).
EP16741582.7A 2015-07-13 2016-07-12 Process for expansion and storage of a flow of liquefied natural gas from a natural gas liquefaction plant, and associated plant Pending EP3322948A1 (en)

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FR1556656A FR3038964B1 (en) 2015-07-13 2015-07-13 METHOD FOR RELAXING AND STORING A LIQUEFIED NATURAL GAS CURRENT FROM A NATURAL GAS LIQUEFACTION SYSTEM, AND ASSOCIATED INSTALLATION
PCT/EP2016/066544 WO2017009341A1 (en) 2015-07-13 2016-07-12 Process for expansion and storage of a flow of liquefied natural gas from a natural gas liquefaction plant, and associated plant

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US20180202610A1 (en) 2018-07-19
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