WO2022207055A2 - Production de gnl par réfrigération en cascade d'éthylène, de propane et d'ammoniac - Google Patents

Production de gnl par réfrigération en cascade d'éthylène, de propane et d'ammoniac Download PDF

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Publication number
WO2022207055A2
WO2022207055A2 PCT/EG2021/000010 EG2021000010W WO2022207055A2 WO 2022207055 A2 WO2022207055 A2 WO 2022207055A2 EG 2021000010 W EG2021000010 W EG 2021000010W WO 2022207055 A2 WO2022207055 A2 WO 2022207055A2
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stream
ethylene
gas
propane
gas stream
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PCT/EG2021/000010
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WO2022207055A3 (fr
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Amr Ahmed Amin EL KHASHAB
Mohamed Ibrahim El Sayed FARAG
Mahmoud Mohamed Farag MORGAN
Ahmed Abdel Hamid ABDEL GELIL
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Engineering For The Petroleum And Process Industries (Enppi)
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Priority to PCT/EG2021/000010 priority Critical patent/WO2022207055A2/fr
Publication of WO2022207055A2 publication Critical patent/WO2022207055A2/fr
Publication of WO2022207055A3 publication Critical patent/WO2022207055A3/fr

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/004—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
    • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
    • F25J1/008—Hydrocarbons
    • F25J1/0085—Ethane; Ethylene
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
    • F25J1/008—Hydrocarbons
    • F25J1/0087—Propane; Propylene
    • 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
    • F25J1/0209—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 as at least a three level refrigeration cascade
    • F25J1/021—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 as at least a three level refrigeration cascade 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
    • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
    • F25J1/0235—Heat exchange integration
    • F25J1/0242—Waste heat recovery, e.g. from heat of compression
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0257—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
    • F25J1/0265—Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams comprising cores associated exclusively with the cooling of a refrigerant stream, e.g. for auto-refrigeration or economizer
    • F25J1/0268—Arrangement of heat exchanger cores in parallel with different functions, e.g. different cooling streams comprising cores associated exclusively with the cooling of a refrigerant stream, e.g. for auto-refrigeration or economizer using a dedicated refrigeration means
    • 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
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0281—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc. characterised by the type of prime driver, e.g. hot gas expander
    • F25J1/0283—Gas turbine as the prime mechanical driver
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0294—Multiple compressor casings/strings in parallel, e.g. split arrangement
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/80—Hot exhaust gas turbine combustion engine
    • F25J2240/82—Hot exhaust gas turbine combustion engine with waste heat recovery, e.g. in a combined cycle, i.e. for generating steam used in a Rankine cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/906—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by heat driven absorption chillers

Definitions

  • Liquefied natural gas is natural gas (predominantly methane, CH4, with some mixture of ethane, C2H6) that has been cooled down to liquid form for ease and safety of non-pressurized storage or transport. It takes up about 1 /600 th the volume of natural gas in the gaseous state at standard conditions for temperature and pressure.
  • Natural gas markets are transitioning from local to regional and global markets, with increasing competition and diversity among suppliers and customers. LNG is the driving force to further enhance competition and market integration in international natural gas markets. Its development is favored by the state of the well-supplied market that is assumed to continue over the coming years.
  • FIG. 1 is a process flow diagram showing the design of a processing plant to produce LNG using prior art according to U.S. Pat. No. 4,157,904 and 7,415,840 B2
  • the feed stream is directed to sweeting unit to remove C02 to certain limit to prevent C02 freezing under cryogenic conditions. Then the gas is dehydrated to prevent hydrate (ice) formation under cryogenic conditions
  • the gas is liquified using different techniques using cascade refrigerant of propane and ethylene to cool the gas inlet stream and decreasing the gas pressure to decrease the temperature and hence produce gas liquid.
  • cascade refrigerant of propane and ethylene to cool the gas inlet stream and decreasing the gas pressure to decrease the temperature and hence produce gas liquid.
  • Propane refrigeration chills the feed Gas prior to liquefaction, condenses (is cascaded to) ethylene compressor discharge, and de-superheats methane compressor discharge.
  • the compressors are single case units with two side stream inlets. Each of the compressors is driven by a gas turbine.
  • Propane Refrigerant Condenser A- 101.
  • Propane liquid flows into the shell sides of the H.S. Propane - Methane/Ethylene Chiller (E- 101).
  • Propane liquid from E-101 flows into the shell side of the I.S. Propane - Ethylene/Feed Methane Chiller (E-102) on level control. Vapor from the shell side flows to the intermediate stage side inlet of the compressors.
  • Propane liquid from E-102 flows via the Ethylene Propane Economizer (E-104) into the shell sides of the L.S. Propane - Ethylene Condenser Feed Chiller (E-103) on individual level controls. Vapor from E-103 flows to both compressor suctions via the L.S. Propane Suction Drums.
  • Level controls in the H.S. and I.S. Suction Drums send any recovered liquid to the shell sides of the L.S. Propane - Ethylene Condenser Feed Chiller (E-103).
  • the L.S. Suction Drums are provided with a gravity drain system to allow any accumulated liquids to flow directly into the shell sides of the L.S. Propane - Ethylene Condenser Feed Chiller (E-103).
  • Ethylene refrigeration cools, condenses, and slightly subcools feed gas, and cools and condenses (is cascaded to) methane compressor discharge. Two (2) fifty percent compressors are used in parallel.
  • the Ethylene compressors are two stage units, in single cases, with individual intercooling and discharge cooling by air. Both compressors (after their individual discharge cooler) share a common discharge desuperheat and condensing system, and use common evaporators.
  • Ethylene refrigeration is provided in core-in-shell evaporators at two levels:
  • Compressor discharge is de-superheated against air via the Ethylene Compressor Discharge Coolers (A-102) and cooled against both H.S. and I.S. propane in E-101 and E-102, then totally condensed against the L.S. propane refrigerant in E- 103.
  • the liquid is first subcooled in the Ethylene Propane Economizer (E-104), then flows into the shell side of the H.S. Ethylene- Feed Methane Chiller (E-105).
  • Liquid ethylene refrigerant flows from E-105 through E-104 into the shell sides of the L.S. Ethylene Feed Condenser (E-107) and the Feed Gas Chiller (E-106) on level control.
  • Feed gas flows through E-105 and then E-106, where it is partially condensed to drop out aromatics and heavy hydrocarbons into the liquid phase.
  • the partially condensed feed gas enters the Heavies Removal Column (V -100) where the liquids are separated for further processing.
  • the vapor from V -100 is combined with the methane recycle from E-108 and sent to E-107 where it is totally condensed and slightly sub-cooled. This liquid then flows to a series of flashes, which are part of the methane compression system.
  • E-108 The methane side draw from E-108 is cooled in E-105 and then condensed in E- 107, after which it is sent to V- 100 as reflux. Vapor from E-107 and E-106 flows through the Economizer to the compressor. Exchangers E-105, E-107, E-104, and E-106 are installed in a cold box.
  • These units comprise liquefaction and methane refrigeration compression.
  • the condensed feed gas is flashed to three (3) pressure levels in succession, with the liquid from the last (low stage, or L.S.) being pumped via LNG Transfer Pumps to the LNG Storage Tanks as the LNG product. Vapor from each flash is re compressed and recycled to points upstream of the feed gas condensing operations, which utilize propane and ethylene refrigeration.
  • methane vapor streams flow through an economizer, where they cool the Methane Compressor discharge on its way to condensing. All compressor suction streams are warmed via this economizer to about -8.4°C.
  • Compressors (after their individual discharge cooler) share a common discharge de-superheat and condensing system, and share the flash drums and economizer.
  • Liquid from the condensing step along with reflux from E-107 is first subcooled in the Methane Economizer (E-108) against returning vapors from all three (3) flash drums and flashed into the High Stage Flash Drum operated.
  • Liquid from the H.S. flash drum is subcooled against returning I.S. and L.S. flash vapor in the Interstage Methane Economizer (E-109), and flashed via level control valve to the Inter Stage Flash Drum operated at 3.97 Barg.
  • the CAPEX and OPEX will be the main item which will encourage the profitability of schemes compared to others.
  • the present invention offers significant efficiency advantages over the prior art processes, as in this invention utilizing idea which will significantly reduce LNG plant CAPEX and OPEX as reflected in plant installed & operating power.
  • a typical analysis of a gas stream to be processed in accordance with this invention would be 97.95% methane, 2 % ethane and 0.05 C02.
  • FIG. 2 is a process flow diagram showing the design of a processing plant to produce LNG using liquid expander process.
  • 654 MMSCFD of the inlet gas enters the plant at 30° C and 60 kg/cm 2 _g as stream 1.
  • the feed stream is directed to sweeting unit to remove C02 to certain limit to prevent C02 freezing under cryogenic conditions.
  • the gas is dehydrated to prevent hydrate (ice) formation under cryogenic conditions.
  • Solid desiccant has typically been used for this purpose.
  • the feed stream 1 is mixed with the recycle gas stream 17 then compressed to 90 kg/cm 2 _g through the inlet gas compressor 101 then cooled in air cooler 102.
  • the outlet stream 3 from air cooler 102 is cooled in cold box 103 from 32 C to -36.5 C by heat exchange with cold propane stream 53 at -39 C and cold recycle gas stream.
  • the cooled gas stream 4 cooled in cold box 104 by heat exchange with two ethylene streams 34, 38 and cold recycle gas stream 11.
  • the outlet stream from cold box 104 stream 5 is totally condensed and divided into two identical parallel liquid expander trains; each have liquid expander.
  • the condensed gas is expanded from 89.3 kg/cm 2 _g to 3 kg/cm 2 _g in the liquid expanders 105 and 107.
  • the cooled expanded combined stream 6 is separated to liquid stream 7 and gas stream 8 in the HP flash drum 109.
  • the liquid stream 7 is flashed to atm pressure then introduced to LP flash drum 110; since the separated cooled liquid is the LNG product stream 9.
  • Around 508 ton/hr. of the LNG is pumped through pump 111 to the LNG storage facilities.
  • 43 MMSCFD of the flashed gases from the LNG storage facilities at - 113 C is compressed and recycled to the LP flash drum 110.
  • the separated gas stream 10 from LP flash drum 110 is compressed from atm. to 3 kg/cm 2 _g and mixed with the separated gas stream 8 from HP flash drum 109.
  • the mixed gas stream 11 is recycled to the cooled boxes 103 and 104 to cool the feed gas stream.
  • the cold recycles gas stream 11 is heated in the cold box then heated in the cold box 103 to 30 C.
  • the heated recycle gas stream 12 is divided into two identical parallel compression trains; each is compressed in re-compressor 113 and 115 from 2.6 kg/cm 2 _g to 4.7 kg/cm 2 _g where each re-compressor’s shaft is connected with liquid expander’s shaft to use the work generated from the liquid expander to compress the gas through the re-compressors.
  • the gas streams 13 and 14 are cooled in the air coolers 117 and 118 to 32 C.
  • the cooled gas streams 15 and 16 are compressed in the LP recycle gas compressors 119 and 120 to 19.4 kg/cm 2 _g.
  • the outlet gas from LP recycle gas compressor 119 and 120 is cooled in the WHR from 150 C to 90 C then cooled in the air coolers 123 from 124 to 32 C.
  • a fuel gas is drawn at 19.2 kg/cm 2 _g for power generation, gas drive of compressors and any other usages.
  • the remain recycle gas is divided to two identical HP compression trains; each is compressed in HP recycle gas compressors 125 and 126 from 19.2 kg/cm 2 _g to 60.2 kg/cm 2 _g then cooled in the WHR from 133 C to 90 C afterward cooled in the air coolers 129 and 130 to 32 C.
  • 434 MMSCFD of recycle gas stream 17 is mixed with the inlet feed gas stream 1.
  • the main purpose of ethylene cycle to cool the feed gas stream to low temperatures to convert which enhance in the LNG production.
  • the ethylene cycle is closed loop cycle.
  • the ethylene gas stream 30 is cooled in the cold box 201 from 32 C to -37 C by heat exchange with cold propane stream 54 at -39 C and cold recycle gas ethylene streams 40 and 42.
  • the cooled ethylene gas stream 31 is divided into two streams 32 and 33.
  • Stream 32 is cooled in the cold box 203 from -37 C to -62.5 C by heat exchange with cold recycle gas ethylene stream.
  • the cooled ethylene gas pressure is decreased from 17.6 kg/cm 2 _g to 6.1 kg/cm 2 _g by control valve to decrease the temperature.
  • This cold ethylene stream 34 is directed to the cooled box 104 to cool the feed gas stream and hence the ethylene is vaporized at the same temperature.
  • the other ethylene stream 33 is cooled in the cold box 202 by heat exchange with cold recycle ethylene gas stream 41 separated from the ethylene flash drum 204. Then the cooled ethylene gas pressure is decreased from 17.6 kg/cm 2 _g to 6.0 kg/cm 2 _g by control valve then mixed with the vaporized ethylene stream 35 outlet from the cold box 104. The mixed stream 36 is directed to ethylene flash drum 204.
  • the separated ethylene liquid stream 37 is cooled in the cold box 205 from -62 AC to -76.3 C then then throttled from 5.8 kg/cm 2 _g to 1.2 kg/cm 2 _g by control valve to decrease the temperature to -89 C.
  • This cold ethylene stream 38 is directed to the cooled box 104 to cool the feed gas stream and hence the ethylene is vaporized at the same temperature.
  • the outlet vaporizes ethylene stream 39 from cold box 104 is heated in the cold box 205 by heat exchange with the liquid ethylene stream 37 separated from ethylene flash drum 204 then heated in the cold box 202 by heat exchange with ethylene stream 33.
  • the outlet stream 40 is heated in the cold box 201 to 30 by heat exchange with the ethylene gas stream 30.
  • the vapor ethylene stream 41 separated from ethylene flash drum 204 is heated in the cold box 203 from -64.5 C to -39 by heat exchange with ethylene stream 32.
  • the outlet stream 42 is heated in the cold box 201 from -39 C to 11.5 by heat exchange with the ethylene gas stream 30.
  • the ethylene stream 43 is compressed from 0.5 kg/cm 2 _g to 6.0 kg/cm 2 _g through first stage ethylene gas compressor 206. Then cool in the WHR from 129 C to 90 C then cooled in the air coolers 209 from 90 to 32 C. Then mixed with outlet ethylene stream 44 from cold box 201. The mixed stream is compressed in the second stage ethylene gas compressor 208 from 5.8 kg/cm 2 _g to 18.2 kg/cm 2 _g; then cooled in the air cooler 209 from 105 C to 32 C.
  • propane cycle The main purpose of propane cycle to cool the ethylene stream in the ethylene cycle in addition to the feed gas stream to low temperatures which enhance in the LNG production.
  • the propane cycle is closed loop cycle.
  • the pressure of the propane liquid stream 50 is decreased from 4.7 kg/cm 2 _g to 1.4 kg/cm 2 _g by control valve to decrease the temperature to -20.3 C. Then the propane stream 51 is directed to propane flush drum 302.
  • the separated propane liquid stream 52 is throttled from 1.4 kg/cm 2 _g to 0.15 kg/cm 2 _g by control valve to decrease the temperature to -39 C.
  • This cold propane stream 52 is divided into two streams.
  • the propane stream 53 is directed to the cooled box 103 to cool the feed gas stream and hence the propane is vaporized at the same temperature.
  • the other propane stream 54 is directed to the cold box 201 to cool the ethylene gas stream 30 in the ethylene cycle hence the propane is vaporized at the same temperature.
  • the two outlet vapor propane streams 55 and 56 from cold box 103 and cold box 201 respectively is mixed then compressed in the first propane gas compressor 303 from atm to 1.4 kg/cm 2 _g; then mixed with the separated vapor propane stream 57 from propane flash drum 302.
  • the two mixed stream is compressed in the second stage of the propane gas compressor 304 from 1.4 kg/cm 2 _g to 4.9 kg/cm 2 _g then cooled in the ammonia cooler 301 from 24.7 C
  • a liquid ammonia streams (100) evaporate in the propane condenser (401). Evaporation of the liquid ammonia (100) produces ammonia vapors stream (101) and cool stream (50) causing sub cooling of the propane through the refrigeration effect.
  • the gaseous mixed ammonia (101) is cooled and absorbed in a lean aqueous solution of ammonia, in the absorber 406.
  • the mixture of gaseous ammonia and lean solution releases heat to a cooling water 102 into the absorber 406.
  • a rich ammonia solution (103) is withdrawn from the absorber 406. This rich solution is cooled in heat exchanger 405, air cooler 404 then pumped by the ammonia solution pump 403 to be heated in heat exchanger 407,407 and 408 and then to the desorber 410.
  • the desorber 410 extracts gaseous ammonia (104) from the rich solution and regenerates a lean aqueous solution of ammonia (105).
  • the desorption process requires a heat input given by a heating medium extracted from waste heat recovery unit which recovers heat on recycle gas compressors.
  • the desorber 410 can be a fractionation column in a preferred embodiment, wherein the gaseous ammonia emerges from top of the column and the regenerated lean solution is recovered from bottom.
  • the lean aqueous solution of ammonia (105) preheats the incoming rich solution in the heat exchanger 408 and, after de-pressurization in the letdown valve, it directed to the absorber 406.
  • the gaseous ammonia (104) taken from the desorber 410 is condensed in the condenser 411, which is an air condenser.
  • the so obtained high-pressure liquid ammonia (106) is de-pressurized through the letdown valve and forms the liquid ammonia stream (100) directed to the propane condenser 401.
  • Sales gas outlet from LNG plant is used after compressing the sales gas in heating of part of rich aqua stream.
  • Figure 3 LNG production using the ammonia absorption refrigeration cascaded with propane and ethylene mechanical refrigeration.

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Abstract

La production de GNL est une industrie à haute consommation d'énergie du fait qu'elle dépend globalement du refroidissement du gaz d'alimentation pour liquéfier le flux de gaz, la réduction de l'énergie consommée dans cette industrie demeure un défi qui concerne directement une augmentation du profit. Une usine de production de GNL classique fait habituellement appel à différentes techniques utilisant un réfrigérant en cascade de propane et d'éthylène pour refroidir le flux d'entrée de gaz et pour baisser la pression de gaz à l'aide d'une soupape de commande de refroidissement profond pour abaisser la température et pour produire ainsi un liquide gazeux. La présente invention offre des avantages de rendement importants par rapport à la centrale de production de GNL classique, dans la mesure où la présente invention utilise l'idée qui réduit significativement les CAPEX et OPEX d'usine de production de GNL inhérentes à une usine installée et à la puissance d'exploitation. La présente invention montre que la façon d'utiliser la réfrigération par absorption d'ammoniac intégrée avec une récupération de chaleur perdue de turbines à gaz de compresseur (WHRU) et le flux chaud de décharge de compresseur en cascade avec une réfrigération mécanique au propane améliore l'optimisation de production de chaleur de l'usine de production de GNL et fournit un réfrigérant nécessaire au refroidissement du GNL. De plus, l'utilisation d'un dispositif d'expansion de liquide sous haute pression d'entrée à un étage pour produire un pourcentage élevé de GNL à une haute pression de gaz d'entrée supérieure à 80 bars permet de réduire le débit de gaz de recyclage. La présente invention peut être appliquée à de nouvelles usines de production de GNL et à la valorisation des usines de production de GNL existantes.
PCT/EG2021/000010 2021-04-01 2021-04-01 Production de gnl par réfrigération en cascade d'éthylène, de propane et d'ammoniac WO2022207055A2 (fr)

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US8020406B2 (en) * 2007-11-05 2011-09-20 David Vandor Method and system for the small-scale production of liquified natural gas (LNG) from low-pressure gas
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