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WO2005090886A1 - Method for liquefying a hydrocarbon-rich flow - Google Patents

Method for liquefying a hydrocarbon-rich flow Download PDF

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Publication number
WO2005090886A1
WO2005090886A1 PCT/EP2005/002019 EP2005002019W WO2005090886A1 WO 2005090886 A1 WO2005090886 A1 WO 2005090886A1 EP 2005002019 W EP2005002019 W EP 2005002019W WO 2005090886 A1 WO2005090886 A1 WO 2005090886A1
Authority
WO
WIPO (PCT)
Prior art keywords
refrigerant mixture
hydrocarbon
circuit
liquefaction
flow
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.)
Ceased
Application number
PCT/EP2005/002019
Other languages
German (de)
French (fr)
Inventor
Heinz Bauer
Hubert Franke
Rainer Sapper
Marc Schier
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.)
Linde GmbH
Original Assignee
Linde GmbH
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 Linde GmbH filed Critical Linde GmbH
Priority to AU2005224308A priority Critical patent/AU2005224308B2/en
Publication of WO2005090886A1 publication Critical patent/WO2005090886A1/en
Priority to EGNA2006000830 priority patent/EG24721A/en
Anticipated expiration legal-status Critical
Priority to NO20064557A priority patent/NO20064557L/en
Ceased legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0032—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
    • F25J1/0042—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by liquid expansion with extraction of work
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
    • F25J1/0052—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant 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
    • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
    • F25J1/0052—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream
    • F25J1/0057—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant stream after expansion of the liquid refrigerant stream with extraction of work
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—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
    • F25J1/0214—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 as a dual level refrigeration cascade with at least one MCR 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
    • 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
    • F25J1/0237—Heat exchange integration integrating refrigeration provided for liquefaction and purification/treatment of the gas to be liquefied, e.g. heavy hydrocarbon removal from natural gas
    • F25J1/0239—Purification or treatment step being integrated between two refrigeration cycles of a refrigeration cascade, i.e. first cycle providing feed gas cooling and second cycle providing overhead gas cooling
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0281—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc. characterised by the type of prime driver, e.g. hot gas expander
    • F25J1/0283—Gas turbine as the prime mechanical driver
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0285—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
    • F25J1/0287—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings including an electrical motor
    • 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.
    • F25J1/0292—Refrigerant compression by cold or cryogenic suction of the refrigerant gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—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.
    • F25J1/0295—Shifting of the compression load between different cooling stages within a refrigerant cycle or within a cascade refrigeration system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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.
    • F25J1/0296—Removal of the heat of compression, e.g. within an inter- or afterstage-cooler against an ambient heat sink
    • 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.
    • F25J1/0298—Safety aspects and control of the refrigerant compression system, e.g. anti-surge control
    • 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
    • F25J2220/64—Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream

Definitions

  • the invention relates to a method for liquefying a hydrocarbon-rich stream, in particular a natural gas stream, the liquefaction of the hydrocarbon-rich stream against one of two
  • Refrigerant mixture circuits existing refrigerant mixture circuit cascade takes place, the first refrigerant mixture circuit for pre-cooling and the second refrigerant mixture circuit for the liquefaction and subcooling of the hydrocarbon-rich stream to be liquefied, and each
  • Refrigerant mixture circuit has at least one single-stage or multi-stage compressor driven by at least one gas turbine, starters which can be used during normal operation to support the gas turbines being assigned to the gas turbines.
  • pre-cooling is understood below to mean the cooling of the hydrocarbon-rich stream to be liquefied to a temperature at which the separation of heavy or higher-boiling hydrocarbons takes place.
  • the subsequent, further cooling of the hydrocarbon-rich stream to be liquefied subsequently falls under the term "liquefaction”.
  • Heavy hydrocarbons are contained in the natural gas stream to be liquefied, these are separated between the pre-cooling and the liquefaction and drawn off as a so-called NGL (Natural Gas Liquids) fraction and possibly further processed.
  • Heavy or higher-boiling hydrocarbons are those components of the hydrocarbon-rich stream or natural gas to be liquefied that would freeze out during the subsequent cooling and liquefaction - i.e. C 5+ hydrocarbons and aromatics. Often, those hydrocarbons are also used - this means in particular Propane and butane - which would undesirably increase the calorific value of the liquefied natural gas, are separated before liquefaction.
  • HHC heavy hydrocarbon HHC heavy hydrocarbon
  • scrub column This separation of higher-boiling hydrocarbons usually takes place by providing a so-called HHC heavy hydrocarbon) column or scrub column, which is used to separate the heavy hydrocarbons and benzene from the hydrocarbon-rich stream to be liquefied.
  • HHC heavy hydrocarbon HHC heavy hydrocarbon
  • the cycle compressors are usually driven by gas turbines. These in turn are usually put into operation by electric or steam-powered starters. Since such starters often have to provide a noteworthy power - 20 to 40% of the gas turbine power - during normal operation they are used as so-called helpers to support the gas turbines. Larger gas turbines are only available on the market in discrete power levels with comparatively large jumps in performance. The starter or helper performance is limited in relation to the gas turbine performance in order to avoid synchronization problems.
  • the first or pre-cooling circuit typically requires about 40 to 55% of the total energy.
  • the power requirement of the pre-cooling circuit is also often less than that of the second or liquefaction circuit.
  • helper This asymmetry can be compensated for by using the helper differently. For example, if the power distribution between the first and the second refrigerant mixture circuits is 45% to 55% and both refrigerant mixture circuits each have a gas turbine with an output of 70 MW and a helper with an output of 20 MW, the helper will be the first Refrigeration circuit operated only with 4 instead of the possible 20 MW. Much of this helper's investment remains unused during normal liquefaction.
  • the object of the present invention is to provide a generic method for liquefying a hydrocarbon-rich stream, in which the installed power of the gas turbines and starter / helper can be fully utilized in normal operation. Furthermore, the investment and operating costs of the gas turbines and starters / helper used should be reduced or optimized, in particular the use of identical gas turbines and starter / helper should be made possible.
  • the second refrigerant mixture circuit has a cold-suction compressor with a pressure ratio of at least 10
  • the first refrigerant mixture circuit is at least partially used for the intermediate cooling of at least a partial flow of the partially compressed refrigerant mixture flow of the second refrigerant mixture circuit.
  • the hydrocarbon-rich stream to be liquefied is fed via line a to a heat exchanger E1.
  • the hydrocarbon-rich stream to be liquefied is cooled to such an extent that the heavy or higher-boiling hydrocarbons contained therein condense and can be separated from the hydrocarbon-rich stream in the separation unit H, to which the cooled process stream is fed via line b.
  • the separated hydrocarbons are withdrawn via line c and possibly used for a further use. It should be emphasized that the process according to the invention can be combined with all known separation methods for higher-boiling hydrocarbons which are part of the prior art.
  • the hydrocarbon-rich stream which is now freed of higher-boiling hydrocarbons, is fed via line d to a second heat exchanger E2, in which it is liquefied and supercooled against the refrigerant mixture of the second refrigerant mixture circuit.
  • the liquefied and supercooled hydrocarbon-rich stream is withdrawn from the heat exchanger E2 via line e, optionally expanded in a expansion turbine T1 and then immediately fed to a further use or (intermediate) storage via valve f and line g.
  • the refrigerant mixture compressed in the compressor V1 is fed via line 10 to a condenser E3 and then via line 11 to the heat exchanger E1 and supercooled therein.
  • the heat exchanger E1 there is a separation into three refrigerant mixture partial flows 12, 15 and 18.
  • the valves 13, 16 and 19 these are expanded to different pressure levels and, after renewed passage and evaporation in the heat exchanger E1, via lines 14, 17 and 20 to the compressor V1 different pressure levels supplied.
  • the compressor V1 is driven by a gas turbine G1. Not shown in the figure are the starters required for the operation of the gas turbines G1 and G2, as already explained at the beginning.
  • the compressed refrigerant mixture of the second refrigerant mixture circuit is first fed via line 30 to an aftercooler E4 and then via line 31 to the heat exchanger E1 and is cooled and condensed therein. Then the liquefied
  • the mixed refrigerant stream is fed via line 32 to the heat exchanger E2, further subcooled in it, after passage through the heat exchanger E2 in the optional expansion turbine T2, and then fed to an expansion valve 34 via line 33 and expanded in the latter. Then the second refrigerant mixture partial flow after evaporation in the heat exchanger E2 via line 35 to the input stage of the circuit compressor V2.
  • the heat exchanger E2 can be designed as a wound heat exchanger or a plate exchanger. If the hydrocarbon-rich stream to be liquefied is liquefied and supercooled in a plate exchanger, the refrigerant mixture 28 of the second refrigerant mixture circuit can be vaporized in an increasing or decreasing manner, in accordance with an advantageous embodiment of the method according to the invention.
  • the aforementioned circuit compressor V2 which according to the invention is a cold-suction compressor which has a pressure ratio of at least 10, is also driven by a gas turbine G2, which is assigned a starter / helper (not shown in the figure).
  • a partially compressed refrigerant mixture stream is now withdrawn via line 36 from an intermediate stage of the circuit compressor V2, subjected to aftercooling E5 and then at least partially fed to the heat exchanger E1 via line 39 and intercooled in the latter against the first cooling circuit.
  • the intercooled, partially compressed refrigerant mixture stream is then fed back via line 40 to a suitable intermediate pressure stage of the compressor V2 and compressed to the desired final pressure.
  • the use of the first refrigeration circuit for the intermediate cooling of the second refrigeration circuit relieves the latter at the expense of the first refrigeration circuit, since the compressor output of the compressor V2 in its high-pressure part falls in line 40 in proportion to the now reduced suction temperature of the intercooled refrigerant flow. According to the invention, it is now possible to shift the compressor outputs up to the same output between the two compressors V1 and V2 and their associated starters / helpers.
  • the optimal choice of the above-described intermediate cooling is determined by the dew point of the refrigerant mixture selected for the second refrigeration circuit at the selected intermediate pressure at which the refrigerant mixture is drawn off. Ideally, the entire refrigerant mixture of the second refrigeration circuit is used of the first refrigeration circuit cooled until the output of both circuit drives V1 and V2 is equal.
  • the fact that the first refrigerant mixture circuit is now used for intermediate cooling of the second refrigerant mixture circuit means that the installed capacity of identical gas turbines and starters / helpers can be used in full.
  • the starter / helper of the second refrigeration circuit can now also be operated with an output of 20 MW.
  • the usable installed power increases from 164 MW to 180 MW due to the inventive method.
  • the system performance can be increased by approx. 10%.
  • the temperature of the intermediate cooling E1 of at least one partial flow of the partially compressed refrigerant mixture flow 36, 39 of the second refrigerant mixture circuit is influenced by the fact that the intermediate cooled partial flow is subtracted from the intermediate cooling E1 at different temperature levels - represented by the dotted in the figure drawn line 21 - and / or the partial flow of the partially compressed refrigerant mixture flow 37 which is not supplied to the intermediate cooling E1 and which is expanded in the valve 38 to the inlet pressure - which is fed to the subsequent compressor stages.
  • the desired suction temperature of the high-pressure part of the compressor V2 can now be set.

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

Abstract

The invention relates to a method for liquefying a hydrocarbon-rich flow, particularly a flow of natural gas, wherein liquefaction of the hydrocarbon-rich flow is carried out counter to a cascade consisting of two circuits of coolant mixtures. The first coolant mixture circuit is used for precooling (E1) and the second coolant mixture circuit is used for liquefaction and undercooling (E2) of the hydrocarbon-rich flow (a) that is to be liquefied. Each coolant mixture circuit comprises at least one single-stepped or multistepped condenser (V1,V2) which is driven by at least one gas turbine (G1, G2). Starters, which are used to assist the gas turbines, are associated with the gas turbines. According to the invention, the second coolant mixture circuit comprises a cold-suctioning condenser (V2) with a pressure ratio of at least 10 and the first coolant mixture circuit is at least partially used for intermediate cooling (E1) of at least one partial flow of the partially condensed coolant mixture flow (36, 39) of the second coolant mixture circuit.

Description

Beschreibung description

Verfahren zum Verflüssigen eines Kohlenwasserstoff-reichen StromesProcess for liquefying a hydrocarbon-rich stream

Die Erfindung betrifft ein Verfahren zum Verflüssigen eines Kohlenwasserstoff-reichen Stromes, insbesondere eines Erdgasstromes, wobei die Verflüssigung des Kohlenwasserstoff-reichen Stromes gegen eine aus zweiThe invention relates to a method for liquefying a hydrocarbon-rich stream, in particular a natural gas stream, the liquefaction of the hydrocarbon-rich stream against one of two

Kältemittelgemischkreisläufen bestehende Kältemittelgemischkreislaufkaskade erfolgt, wobei der erste Kaltemittelgemischkreislauf der Vorkühlung und der zweite Kaltemittelgemischkreislauf der Verflüssigung und Unterkühlung des zu verflüssigenden Kohlenwasserstoff-reichen Stromes dient, und wobei jederRefrigerant mixture circuits existing refrigerant mixture circuit cascade takes place, the first refrigerant mixture circuit for pre-cooling and the second refrigerant mixture circuit for the liquefaction and subcooling of the hydrocarbon-rich stream to be liquefied, and each

Kaltemittelgemischkreislauf wenigstens einen ein- oder mehrstufigen, von wenigstens einer Gasturbine angetriebenen Verdichter aufweist, wobei den Gasturbinen Starter, die während des normalen Betriebes zur Unterstützung der Gasturbinen verwendet werden können, zugeordnet sind.Refrigerant mixture circuit has at least one single-stage or multi-stage compressor driven by at least one gas turbine, starters which can be used during normal operation to support the gas turbines being assigned to the gas turbines.

Unter dem Begriff "Vorkühlung" sei nachfolgend die Abkühlung des zu verflüssigenden Kohlenwasserstoff-reichen Stromes bis zu einer Temperatur, bei der die Abtrennung schwerer bzw. höhersiedender Kohlenwasserstoffe erfolgt, zu verstehen. Die sich daran anschließende, weitere Abkühlung des zu verflüssigenden Kohlenwasserstoff- reichen Stromes fällt nachfolgend unter den Begriff "Verflüssigung".The term “pre-cooling” is understood below to mean the cooling of the hydrocarbon-rich stream to be liquefied to a temperature at which the separation of heavy or higher-boiling hydrocarbons takes place. The subsequent, further cooling of the hydrocarbon-rich stream to be liquefied subsequently falls under the term "liquefaction".

Gattungsgemäße Erdgasverflüssigungsverfahren - im allgemeinen als Dual-Flow- LNG-Prozess bezeichnet - sind dem Fachmann aus dem Stand der Technik hinlänglich bekannt; beispielhaft genannt sei das US-Patent 6,105,389.Generic natural gas liquefaction processes - generally referred to as a dual-flow LNG process - are well known to the person skilled in the art from the prior art; US Pat. No. 6,105,389 may be mentioned by way of example.

Sofern schwere Kohlenwasserstoffe in dem zu verflüssigenden Erdgasstrom enthalten sind, werden diese zwischen der Vorkühlung und Verflüssigung abgetrennt und als so genannte NGL(Natural Gas Liquids)-Fraktion abgezogen und ggf. einer Weiterverarbeitung zugeführt. Als schwere oder höhersiedende Kohlenwasserstoffe werden diejenigen Komponenten des zu verflüssigenden Kohlenwasserstoff-reichen Stromes bzw. Erdgases bezeichnet, die bei der nachfolgenden Abkühlung und Verflüssigung ausfrieren würden - also C5+-Kohlenwasserstoffe und Aromate. Oftmals werden zudem diejenigen Kohlenwasserstoffe - gemeint sind hierbei insbesondere Propan und Butan -, die den Heizwert des verflüssigten Erdgases unerwünscht erhöhen würden, vor der Verflüssigung abgetrennt.If heavy hydrocarbons are contained in the natural gas stream to be liquefied, these are separated between the pre-cooling and the liquefaction and drawn off as a so-called NGL (Natural Gas Liquids) fraction and possibly further processed. Heavy or higher-boiling hydrocarbons are those components of the hydrocarbon-rich stream or natural gas to be liquefied that would freeze out during the subsequent cooling and liquefaction - i.e. C 5+ hydrocarbons and aromatics. Often, those hydrocarbons are also used - this means in particular Propane and butane - which would undesirably increase the calorific value of the liquefied natural gas, are separated before liquefaction.

Dieses Abtrennen von höhersiedenden Kohlenwasserstoffen geschieht üblicherweise dadurch, dass eine so genannte HHC Heavy Hydrocarbon)-Kolonne bzw. Scrub- Column, die der Abtrennung der schweren Kohlenwasserstoffe sowie von Benzol aus dem zu verflüssigenden Kohlenwasserstoff-reichen Strom dient, vorgesehen wird. Eine derartige Verfahrensführung wird beispielsweise in der DE-OS 197 16 415 beschrieben.This separation of higher-boiling hydrocarbons usually takes place by providing a so-called HHC heavy hydrocarbon) column or scrub column, which is used to separate the heavy hydrocarbons and benzene from the hydrocarbon-rich stream to be liquefied. Such a procedure is described for example in DE-OS 197 16 415.

Bei Dual-Flow-LNG-Anlagen werden die Kreislaufverdichter üblicherweise von Gasturbinen angetrieben. Diese wiederum werden üblicherweise von elektrischen oder dampfgetriebenen Startern in Betrieb genommen. Da derartige Starter oftmals eine nennenswerte Leistung - 20 bis 40 % der Gasturbinenleistung - aufbringen müssen, werden sie während des normalen Betriebes als so genannte Helper zur Unterstützung der Gasturbinen herangezogen. Größere Gasturbinen sind nur in diskreten Leistungsstufen bei vergleichsweise großen Leistungssprüngen auf dem Markt verfügbar. Die Leistung der Starter bzw. Helper ist in Bezug auf die Gasturbinenleistung begrenzt, um Synchronisationsprobleme zu vermeiden.In dual-flow LNG plants, the cycle compressors are usually driven by gas turbines. These in turn are usually put into operation by electric or steam-powered starters. Since such starters often have to provide a noteworthy power - 20 to 40% of the gas turbine power - during normal operation they are used as so-called helpers to support the gas turbines. Larger gas turbines are only available on the market in discrete power levels with comparatively large jumps in performance. The starter or helper performance is limited in relation to the gas turbine performance in order to avoid synchronization problems.

Aufgrund einer Vielzahl von verfahrenstechnischen Rangbedingungen, wie beispielsweise Zusammensetzung und Druck des zu verflüssigenden Kohlenwasserstoff-reichen Stromes, Umgebungstemperatur, etc., und der Anforderungen an die ggf. vorzusehende Abtrennung schwerer Kohlenwasserstoffe ist eine optimale Leistungsaufteilung zwischen den Verdichterantrieben der beiden Kältemittelgemischkreisläufe nicht oder nur zufälligerweise zu erreichen. Typischerweise benötigt der erste bzw. Vorkühlkreislauf etwa 40 bis 55 % der Gesamtenergie. Der Leistungsbedarf des Vorkühlkreislaufes ist zudem oftmals kleiner als derjenige des zweiten bzw. Verflüssigungskreislaufes.Due to a large number of procedural ranking conditions, such as the composition and pressure of the hydrocarbon-rich stream to be liquefied, ambient temperature, etc., and the requirements for the separation of heavy hydrocarbons that may have to be provided, an optimal power distribution between the compressor drives of the two refrigerant mixture circuits is not or only by chance to reach. The first or pre-cooling circuit typically requires about 40 to 55% of the total energy. The power requirement of the pre-cooling circuit is also often less than that of the second or liquefaction circuit.

Diese Asymmetrie kann durch eine unterschiedliche Nutzung der Helper ausgeglichen werden. Beträgt beispielsweise die Leistungsverteilung zwischen dem ersten und dem zweiten Kaltemittelgemischkreislauf 45 % zu 55 % und weisen beide Kältemittelgemischkreisläufe jeweils eine Gasturbine mit einer Leistung von 70 MW sowie einen Helper mit einer Leistung von 20 MW auf, so wird der Helper des ersten Kältekreislaufes nur mit 4 anstatt der möglichen 20 MW betrieben. Ein Großteil der Investition dieses Helpers bleibt somit während des normalen Verflüssigungsbetriebes ungenutzt.This asymmetry can be compensated for by using the helper differently. For example, if the power distribution between the first and the second refrigerant mixture circuits is 45% to 55% and both refrigerant mixture circuits each have a gas turbine with an output of 70 MW and a helper with an output of 20 MW, the helper will be the first Refrigeration circuit operated only with 4 instead of the possible 20 MW. Much of this helper's investment remains unused during normal liquefaction.

Aufgabe der vorliegenden Erfindung ist es, ein gattungsgemäßen Verfahren zum Verflüssigen eines Kohlenwasserstoff-reichen Stromes anzugeben, bei dem die installierte Leistung der Gasturbinen sowie Starter/Helper im Normalbetrieb zur Gänze ausgenutzt werden kann. Des Weiteren sollen die Investitions- und Betriebskosten der verwendeten Gasturbinen sowie Starter/Helper verringert bzw. optimiert werden, insbesondere soll die Verwendung identischer Gasturbinen sowie Starter/Helper ermöglicht werden.The object of the present invention is to provide a generic method for liquefying a hydrocarbon-rich stream, in which the installed power of the gas turbines and starter / helper can be fully utilized in normal operation. Furthermore, the investment and operating costs of the gas turbines and starters / helper used should be reduced or optimized, in particular the use of identical gas turbines and starter / helper should be made possible.

Zur Lösung dieser Aufgabe wird vorgeschlagen, dass a) der zweite Kaltemittelgemischkreislauf einen kaltansaugenden Verdichter mit einem Druckverhältnis von wenigstens 10 aufweist, und b) der erste Kaltemittelgemischkreislauf zumindest teilweise für die Zwischenkühlung wenigstens eines Teilstromes des teilverdichteten Kältemittelgemischstromes des zweiten Kältemittelgemischkreislaufes herangezogen wird.To achieve this object, it is proposed that a) the second refrigerant mixture circuit has a cold-suction compressor with a pressure ratio of at least 10, and b) the first refrigerant mixture circuit is at least partially used for the intermediate cooling of at least a partial flow of the partially compressed refrigerant mixture flow of the second refrigerant mixture circuit.

Das erfindungsgemäße Verfahren sowie weitere Ausgestaltungen desselben, die Gegenstände der abhängigen Patentansprüche darstellen, seien im Folgenden anhand des in der Figur dargestellten Ausführungsbeispieles näher erläutert.The method according to the invention and further refinements of the same, which are the subject of the dependent claims, are explained in more detail below with reference to the exemplary embodiment shown in the figure.

Wie in der Figur dargestellt, wird der zu verflüssigende Kohlenwasserstoff-reiche Strom über Leitung a einem Wärmetauscher E1 zugeführt. In diesem wird der zu verflüssigende Kohlenwasserstoff-reiche Strom soweit abgekühlt, dass die in ihm enthaltenen schweren bzw. höhersiedenden Kohlenwasserstoffe kondensieren und in der Abtrenneinheit H, der der abgekühlte Verfahrensstrom über Leitung b zugeführt wird, aus dem Kohlenwasserstoff-reichen Strom abgetrennt werden können. Die abgetrennten Kohlenwasserstoffe werden über Leitung c abgezogen und ggf. einer weiteren Verwendung zugeführt. Es sei betont, dass das erfindungsgemäße Verfahren mit allen bekannten, zum Stand der Technik zählenden Abtrennmethoden für höhersiedende Kohlenwasserstoffe kombiniert werden kann.As shown in the figure, the hydrocarbon-rich stream to be liquefied is fed via line a to a heat exchanger E1. In this, the hydrocarbon-rich stream to be liquefied is cooled to such an extent that the heavy or higher-boiling hydrocarbons contained therein condense and can be separated from the hydrocarbon-rich stream in the separation unit H, to which the cooled process stream is fed via line b. The separated hydrocarbons are withdrawn via line c and possibly used for a further use. It should be emphasized that the process according to the invention can be combined with all known separation methods for higher-boiling hydrocarbons which are part of the prior art.

Über Leitung d wird der nunmehr von höhersiedenden Kohlenwasserstoffen befreite Kohlenwasserstoff-reiche Strom einem zweiten Wärmetauscher E2 zugeführt und in diesem gegen das Kältemittelgemisch des zweiten Kältemittelgemischkreislaufes verflüssigt und unterkühlt. Der verflüssigte und unterkühlte Kohlenwasserstoff-reiche Strom wird aus dem Wärmetauscher E2 über Leitung e abgezogen, optional in einer Entspannungsturbine T1 entspannt und anschließend über Ventil f und Leitung g unmittelbar einer weiteren Verwendung oder (Zwischen)Speicherung zugeführt.The hydrocarbon-rich stream, which is now freed of higher-boiling hydrocarbons, is fed via line d to a second heat exchanger E2, in which it is liquefied and supercooled against the refrigerant mixture of the second refrigerant mixture circuit. The liquefied and supercooled hydrocarbon-rich stream is withdrawn from the heat exchanger E2 via line e, optionally expanded in a expansion turbine T1 and then immediately fed to a further use or (intermediate) storage via valve f and line g.

Bei der in der Figur dargestellten Verfahrensweise wird das im Verdichter V1 verdichtete Kältemittelgemisch über Leitung 10 einem Kondensator E3 und anschließend über Leitung 11 dem Wärmetauscher E1 zugeführt und in diesem unterkühlt. Im Wärmetauscher E1 erfolgt eine Auftrennung in drei Kältemittelgemischteilströme 12,15 und 18. In den Ventilen 13, 16 und 19 werden diese auf unterschiedliche Druckniveaus entspannt und nach erneutem Durchgang und Verdampfung im Wärmetauscher E1 über die Leitungen 14, 17 und 20 dem Verdichter V1 auf unterschiedlichen Druckniveaus zugeführt.In the procedure shown in the figure, the refrigerant mixture compressed in the compressor V1 is fed via line 10 to a condenser E3 and then via line 11 to the heat exchanger E1 and supercooled therein. In the heat exchanger E1, there is a separation into three refrigerant mixture partial flows 12, 15 and 18. In the valves 13, 16 and 19, these are expanded to different pressure levels and, after renewed passage and evaporation in the heat exchanger E1, via lines 14, 17 and 20 to the compressor V1 different pressure levels supplied.

Der Verdichter V1 wird von einer Gasturbine G1 angetrieben. In der Figur nicht dargestellt sind die für den Betrieb der Gastrubinen G1 und G2 erforderlichen Starter, wie sie eingangs bereits erläutert wurden.The compressor V1 is driven by a gas turbine G1. Not shown in the figure are the starters required for the operation of the gas turbines G1 and G2, as already explained at the beginning.

Analog zu der anhand des ersten Kältemittelgemischkreislaufes beschriebenen Verfahrensweise wird das verdichtete Kältemittelgemisch des zweiten Kältemittelgemischkreislaufes über Leitung 30 zunächst einem Nachkühler E4und anschließend über Leitung 31 dem Wärmetauscher E1 zugeführt und in diesem abgekühlt und kondensiert. Anschließend wird der verflüssigteAnalogous to the procedure described on the basis of the first refrigerant mixture circuit, the compressed refrigerant mixture of the second refrigerant mixture circuit is first fed via line 30 to an aftercooler E4 and then via line 31 to the heat exchanger E1 and is cooled and condensed therein. Then the liquefied

Kältemittelgemischstrom über Leitung 32 dem Wärmetauscher E2 zugeführt, in diesem weiter unterkühlt, nach Durchgang durch den Wärmetauscher E2 in der optionalen Entspannungsturbine T2 entspannt sowie anschließend über Leitung 33 einem Entspannungsventil 34 zugeführt und in diesem entspannt. Anschließend wird der zweite Kältemittelgemischteilstrom nach Verdampfung im Wärmetauscher E2 über Leitung 35 der Eingangsstufe des Kreislaufverdichters V2 zugeführt.The mixed refrigerant stream is fed via line 32 to the heat exchanger E2, further subcooled in it, after passage through the heat exchanger E2 in the optional expansion turbine T2, and then fed to an expansion valve 34 via line 33 and expanded in the latter. Then the second refrigerant mixture partial flow after evaporation in the heat exchanger E2 via line 35 to the input stage of the circuit compressor V2.

Der Wärmetauscher E2 kann als ein gewickelter Wärmetauscher oder ein Plattenaustauscher ausgebildet sein. Erfolgt die Verflüssigung und Unterkühlung des zu verflüssigenden Kohlenwasserstoff-reichen Stromes in einem Plattenaustauscher, kann - entsprechend einer vorteilhaften Ausgestaltung des erfindungsgemäßen Verfahrens - das Kältemittelgemisch 28 des zweiten Kältemittelgemischkreislaufes steigend oder fallend verdampft werden.The heat exchanger E2 can be designed as a wound heat exchanger or a plate exchanger. If the hydrocarbon-rich stream to be liquefied is liquefied and supercooled in a plate exchanger, the refrigerant mixture 28 of the second refrigerant mixture circuit can be vaporized in an increasing or decreasing manner, in accordance with an advantageous embodiment of the method according to the invention.

Der vorerwähnte Kreislaufverdichter V2, bei dem es sich erfindungsgemäß um einen kaltansaugenden Verdichter, der ein Druckverhältnis von wenigstens 10 aufweist, handelt, wird ebenfalls von einer Gasturbine G2, der ein in der Figur nicht dargestellter Starter/Helper zugeordnet ist, angetrieben.The aforementioned circuit compressor V2, which according to the invention is a cold-suction compressor which has a pressure ratio of at least 10, is also driven by a gas turbine G2, which is assigned a starter / helper (not shown in the figure).

Erfindungsgemäß wird nunmehr ein teilverdichteter Kältemittelgemischstrom über Leitung 36 aus einer Zwischenstufe des Kreislaufverdichters V2 abgezogen, einer Nachkühlung E5 unterworfen und anschließend zumindest teilweise über Leitung 39 dem Wärmetauscher E1 zugeführt und in diesem gegen den ersten Kältekreislauf zwischengekühlt. Der zwischengekühlte, teilverdichtete Kältemittelgemischstrom wird anschließend über Leitung 40 wieder einer geeigneten Zwischendruckstufe des Verdichters V2 zugeführt und auf den gewünschten Enddruck verdichtet.According to the invention, a partially compressed refrigerant mixture stream is now withdrawn via line 36 from an intermediate stage of the circuit compressor V2, subjected to aftercooling E5 and then at least partially fed to the heat exchanger E1 via line 39 and intercooled in the latter against the first cooling circuit. The intercooled, partially compressed refrigerant mixture stream is then fed back via line 40 to a suitable intermediate pressure stage of the compressor V2 and compressed to the desired final pressure.

Das Heranziehen des ersten Kältekreislaufes für die Zwischenkühlung des zweiten Kältekreislaufes entlastet Letzteren auf Kosten des ersten Kältekreislaufes, da die Verdichterleistung des Verdichters V2 in seinem Hochdruckteil proportional zu der nunmehr erniedrigten Ansaugtemperatur des zwischengekühlten Kältemittelstromes in Leitung 40 fällt. Erfindungsgemäß lässt sich nunmehr eine Verschiebung der Verdichterleistungen bis hin zur Leistungsgleichheit zwischen den beiden Verdichtern V1 und V2 sowie deren zugeordneten Startem/Helpern realisieren.The use of the first refrigeration circuit for the intermediate cooling of the second refrigeration circuit relieves the latter at the expense of the first refrigeration circuit, since the compressor output of the compressor V2 in its high-pressure part falls in line 40 in proportion to the now reduced suction temperature of the intercooled refrigerant flow. According to the invention, it is now possible to shift the compressor outputs up to the same output between the two compressors V1 and V2 and their associated starters / helpers.

Die optimale Wahl der vorbeschriebenen Zwischenkühlung wird von dem Taupunkt des für den zweiten Kältekreislauf gewählten Kältemittelgemisches bei dem gewählten Zwischendruck, bei dem der Abzug des Kältemittelgemisches erfolgt, bestimmt. Idealerweise wird das gesamte Kältemittelgemisch des zweiten Kältekreislaufs mittels des ersten Kältekreislaufes soweit abgekühlt bis eine Leistungsgleichheit beider Kreislaufantriebe V1 und V2 erreicht ist.The optimal choice of the above-described intermediate cooling is determined by the dew point of the refrigerant mixture selected for the second refrigeration circuit at the selected intermediate pressure at which the refrigerant mixture is drawn off. Ideally, the entire refrigerant mixture of the second refrigeration circuit is used of the first refrigeration circuit cooled until the output of both circuit drives V1 and V2 is equal.

Dadurch, dass nunmehr der erste Kaltemittelgemischkreislauf zur Zwischenkühlung des zweiten Kältemittelgemischkreislaufes genutzt wird, kann die installierte Leistung von identischen Gasturbinen und Startem/Helpern zur Gänze genutzt werden.The fact that the first refrigerant mixture circuit is now used for intermediate cooling of the second refrigerant mixture circuit means that the installed capacity of identical gas turbines and starters / helpers can be used in full.

In Anbetracht der bereits erwähnten Begrenzung der Starter- bzw. Helpleistung in Bezug auf die Gasturbinenleistung ist es offensichtlich, dass die nunmehr erreichte volle Ausnutzung beider Helper zu einer Maximierung der Anlagenkapazität führt. Dies sei an dem nachfolgenden Beispiel erläutert.In view of the already mentioned limitation of the starter or helper power in relation to the gas turbine power, it is obvious that the full utilization of both helpers now achieved leads to a maximization of the system capacity. This is explained in the example below.

Wird aufgrund des erfindungsgemäßen Verfahrens nunmehr eine Leistungsverteilung zwischen dem ersten und dem zweiten Kaltemittelgemischkreislauf von 50 % zu 50 % erreicht, so können - identische Gasturbinen und Starter/Helper für beideIf a power distribution between the first and the second refrigerant mixture circuit of 50% to 50% is now achieved due to the method according to the invention, then identical gas turbines and starters / helper can be used for both

Kältekreisläufe vorausgesetzt - diese bzw. deren Investitionen zur Gänze genutzt werden. Zurückkommend auf das oben angeführte Beispiel kann nunmehr auch der Starter/Helper des zweiten Kältekreislaufes mit einer Leistung von 20 MW betrieben werden. Gegenüber dem eingangs erwähnten Ausgangszustand erhöht sich die nutzbare installierte Leistung durch das erfindungsgemäße Verfahren von 164 MW auf 180 MW. Bei einem gegebenen Antriebskonzept kann die Anlagenleistung damit um ca. 10 % gesteigert werden.Provided refrigeration cycles - these or their investments are used in full. Returning to the example given above, the starter / helper of the second refrigeration circuit can now also be operated with an output of 20 MW. Compared to the initial state mentioned at the outset, the usable installed power increases from 164 MW to 180 MW due to the inventive method. With a given drive concept, the system performance can be increased by approx. 10%.

Wie bereits erläutert, erfolgt die Vorkühlung des zu verflüssigenden Kohlenwasserstoff- reichen Stromes auf drei unterschiedlichen TemperaturniveausAs already explained, the pre-cooling of the hydrocarbon-rich stream to be liquefied takes place at three different temperature levels

(Kältemittelgemischströme 12/14, 15/17 und 18/20). Die ideale Ansaugtemperatur des Hochdruckteils des Verdichters V2 wird durch diese Diskretisierung der Temperaturniveaus der Vorkühlung jedoch höchstens zufällig getroffen.(Mixed refrigerant flows 12/14, 15/17 and 18/20). The ideal suction temperature of the high-pressure part of the compressor V2 is, however, at most accidentally reached by this discretization of the temperature levels of the pre-cooling.

Das erfindungsgemäße Verfahren weiterbildend wird daher vorgeschlagen, dass die Temperatur der Zwischenkühlung E1 wenigstens eines Teilstromes des teilverdichteten Kältemittelgemischstromes 36, 39 des zweiten Kältemittelgemischkreislaufes dadurch beeinflusst wird, dass der zwischengekühlte Teilstrom auf unterschiedlichen Temperaturniveaus aus der Zwischenkühlung E1 abgezogen - in der Figur dargestellt durch die punktiert gezeichneten Leitung 21 - und/oder der nicht der Zwischenkühlung E1 zugeführte Teilstrom des teilverdichteten Kältemittelgemischstromes 37, der im Ventil 38 auf den Eingangsdruck entspannt wird - der bzw. den nachfolgenden Verdichterstufen zugeführt wird. Mittels dieser Verfahrensweise kann nunmehr die gewünschte Saugtemperatur des Hochdruckteils des Verdichters V2 eingestellt werden. Further developing the method according to the invention is therefore proposed that the temperature of the intermediate cooling E1 of at least one partial flow of the partially compressed refrigerant mixture flow 36, 39 of the second refrigerant mixture circuit is influenced by the fact that the intermediate cooled partial flow is subtracted from the intermediate cooling E1 at different temperature levels - represented by the dotted in the figure drawn line 21 - and / or the partial flow of the partially compressed refrigerant mixture flow 37 which is not supplied to the intermediate cooling E1 and which is expanded in the valve 38 to the inlet pressure - which is fed to the subsequent compressor stages. By means of this procedure, the desired suction temperature of the high-pressure part of the compressor V2 can now be set.

Claims

Patentansprüche claims 1. Verfahren zum Verflüssigen eines Kohlenwasserstoff-reichen Stromes, insbesondere eines Erdgasstromes, wobei die Verflüssigung des Kohlenwasserstoff-reichen Stromes gegen eine aus zwei Kältemittelgemischkreisläufen bestehende Kältemittelgemischkreislaufkaskade erfolgt, wobei der erste Kaltemittelgemischkreislauf der Vorkühlung und der zweite Kaltemittelgemischkreislauf der Verflüssigung und Unterkühlung des zu verflüssigenden Kohlenwasserstoff-reichen Stromes dient, und wobei jeder Kaltemittelgemischkreislauf wenigstens einen ein- oder mehrstufigen, von wenigstens einer Gasturbine angetriebenen Verdichter aufweist, wobei den Gasturbinen Starter, die während des normalen Betriebes zur Unterstützung der Gasturbinen verwendet werden, zugeordnet sind, dadurch gekennzeichnet, dass a) der zweite Kaltemittelgemischkreislauf einen kaltansaugenden Verdichter (V2) mit einem Druckverhältnis von wenigstens 10 aufweist, und b) der erste Kaltemittelgemischkreislauf zumindest teilweise für die Zwischenkühlung (E1) wenigstens eines Teilstromes des teilverdichteten Kältemittelgemischstromes (36, 39) des zweiten Kältemittelgemischkreislaufes herangezogen wird.1. A process for liquefying a hydrocarbon-rich stream, in particular a natural gas stream, the liquefaction of the hydrocarbon-rich stream taking place against a refrigerant mixture circuit cascade consisting of two refrigerant mixture circuits, the first refrigerant mixture circuit of the pre-cooling and the second refrigerant mixture circuit of the liquefaction and subcooling of the hydrocarbon to be liquefied rich electricity is used, and wherein each refrigerant mixture circuit has at least one single-stage or multi-stage compressor driven by at least one gas turbine, the gas turbines being assigned starters which are used during normal operation to support the gas turbines, characterized in that a) the second refrigerant mixture circuit has a cold suction compressor (V2) with a pressure ratio of at least 10, and b) the first refrigerant mixture circuit at least partially for the intermediate cooling (E1) of at least one partial flow of the partially compressed mixed refrigerant flow (36, 39) of the second mixed refrigerant circuit is used. 2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, dass die Temperatur der Zwischenkühlung (E1) wenigstens eines Teilstromes des teilverdichteten Kältemittelgemischstromes (36, 39) des zweiten Kältemittelgemischkreislaufes dadurch beeinflusst wird, dass der zwischengekühlte Teilstrom auf unterschiedlichen Temperaturniveaus aus der Zwischenkühlung (E1) abgezogen und/oder der nicht der Zwischenkühlung (E1) zugeführte Teilstrom des teilverdichteten Kältemittelgemischstromes (37) der bzw. den nachfolgenden Verdichterstufen zugeführt wird.2. The method according to claim 1, characterized in that the temperature of the intermediate cooling (E1) of at least a partial flow of the partially compressed mixed refrigerant flow (36, 39) of the second mixed refrigerant circuit is influenced by the fact that the intercooled partial flow is withdrawn from the intermediate cooling (E1) at different temperature levels and / or the partial stream of the partially compressed refrigerant mixture stream (37) which is not supplied to the intermediate cooling (E1) and which is fed to the subsequent compressor stages. 3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die Verflüssigung und Unterkühlung des zu verflüssigenden Kohlenwasserstoff- reichen Stromes in einem gewickelten Wärmetauscher (E2) oder in einem Plattenaustauscher (E2) erfolgt. Verfahren nach Anspruch 3, wobei die Verflüssigung und Unterkühlung des zu verflüssigenden Kohlenwasserstoff-reichen Stromes in einem Plattenaustauscher (E2) erfolgt, dadurch gekennzeichnet, dass das Kältemittelgemisch (28) des zweiten Kältemittelgemischkreislaufes steigend oder fallend verdampft. 3. The method according to claim 1 or 2, characterized in that the liquefaction and subcooling of the hydrocarbon-rich stream to be liquefied takes place in a wound heat exchanger (E2) or in a plate exchanger (E2). The method of claim 3, wherein the liquefaction and subcooling of the hydrocarbon-rich stream to be liquefied takes place in a plate exchanger (E2), characterized in that the refrigerant mixture (28) of the second refrigerant mixture circuit evaporates as it rises or falls.
PCT/EP2005/002019 2004-03-09 2005-02-25 Method for liquefying a hydrocarbon-rich flow Ceased WO2005090886A1 (en)

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NO20064557A NO20064557L (en) 2004-03-09 2006-10-06 Process for liquefying a hydrocarbon-rich stream.

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AU2005224308A1 (en) 2005-09-29
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