WO2015159546A1 - Système et procédé de liquéfaction du gaz naturel - Google Patents

Système et procédé de liquéfaction du gaz naturel Download PDF

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WO2015159546A1
WO2015159546A1 PCT/JP2015/002089 JP2015002089W WO2015159546A1 WO 2015159546 A1 WO2015159546 A1 WO 2015159546A1 JP 2015002089 W JP2015002089 W JP 2015002089W WO 2015159546 A1 WO2015159546 A1 WO 2015159546A1
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gas
absorbent
raw material
natural gas
liquefaction
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PCT/JP2015/002089
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English (en)
Japanese (ja)
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純一郎 田中
恒男 渡辺
俊也 百瀬
泰宏 井上
順哉 小畑
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千代田化工建設株式会社
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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
    • F25J1/02—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
    • F25J1/0215—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 with one SCR cycle
    • F25J1/0216—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 with one SCR cycle using a C3 pre-cooling 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
    • F25J1/0002—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
    • F25J1/0047—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
    • F25J1/0055—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 originating from an incorporated cascade
    • 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
    • F25J1/0228—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
    • F25J1/0238—Purification or treatment step is integrated within one refrigeration cycle only, i.e. the same or single refrigeration cycle provides feed gas cooling (if present) and 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/50—Processes or apparatus using other separation and/or other processing means using absorption, i.e. with selective solvents or lean oil, heavier CnHm and including generally a regeneration step for the solvent or lean oil
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
    • 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
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/66—Separating acid gases, e.g. CO2, SO2, H2S or RSH
    • 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
    • F25J2220/68—Separating water or hydrates

Definitions

  • the present invention relates to a natural gas liquefaction system and a liquefaction method for cooling natural gas to produce liquefied natural gas, and more particularly to a technique for removing heavy components contained in liquefied natural gas.
  • Natural gas collected from gas fields and the like is stored and transported as LNG (liquefied natural gas) by being liquefied at a liquefaction base or the like.
  • LNG cooled to about -162 ° C has advantages such as a significantly reduced volume compared to natural gas (gas), and no need to store at high pressure.
  • impurities such as moisture, acid gas components, and mercury contained in the raw material gas (natural gas that is the subject of liquefaction treatment) are removed in advance, and further, blockage prevention of piping and equipment, etc.
  • the raw material gas is liquefied.
  • the natural gas stream is expanded by an expander and then supplied to the distillation tower, so that the heavy component in the natural gas is supplied from the bottom of the column.
  • a natural gas liquefaction system is known in which a natural gas stream is liquefied by a main heat exchanger after the gas is removed and the distillate gas from the distillation column is compressed by a compressor (Patent Document 1). 2).
  • the inventors of the present application as a result of intensive studies on a method for removing a heavy component in a raw material gas, used a physical adsorbent when processing a raw material gas having a relatively low concentration of the heavy component. It has been found that the concentration of the heavy component in the raw material gas can be reduced to a target concentration (that is, a concentration capable of preventing clogging of pipes due to the solidification of the heavy component) or less by the treatment.
  • the present invention has been devised in view of such problems of the prior art, and does not require a dedicated device for removing heavy components in the raw material gas.
  • the main object of the present invention is to provide a natural gas liquefaction system and a liquefaction method capable of removing water.
  • a natural gas liquefaction system (1) for cooling a natural gas supplied as a raw material gas to produce a liquefied natural gas, wherein the acidic gas contained in the raw material gas is removed.
  • the sum of the concentrations of toluene and xylene is 0.1 mol% or less
  • the acidic gas removal device is a mixture in which a chemical absorbent that absorbs the acidic gas and a physical absorbent that absorbs the heavy hydrocarbon are mixed. An absorbent is used.
  • a raw material gas having a relatively low concentration of heavy hydrocarbons (heavy content) that is, the sum of concentrations of benzene, toluene and xylene is 0.1 mol% or less
  • the acidic gas removal device is configured to remove heavy hydrocarbons together with acidic gas using a mixed absorbent containing a physical absorbent that absorbs heavy hydrocarbons. It is possible to remove heavy components in the raw material gas without requiring a dedicated device for removal.
  • the second aspect of the present invention relates to the first aspect, wherein the physical absorbent comprises at least one of sulfolane, fatty acid amide, N-methylpyrrolidone, and N-alkylated pyrrolidone or a derivative thereof. It is characterized by.
  • the mixed absorbent contains 10 wt% to 40 wt% of sulfolane as the physical absorbent.
  • the acidic gas and the other components such as the chemical absorbent are not affected. It becomes possible to remove heavy hydrocarbons more effectively.
  • an absorbent regeneration device (3) for regenerating the mixed absorbent circulated with the acidic gas removal device, with respect to the third aspect.
  • the apparatus is characterized in that the acidic gas and the heavy hydrocarbon are separated from the mixed absorbent by heating the mixed absorbent under a predetermined pressure.
  • the mixed absorbent is regenerated by the absorbent regenerator so that heavy hydrocarbons are easily recovered and the mixed absorbent is reused in the acid gas removal apparatus. It becomes possible.
  • the acid gas removal device according to any one of the second to fourth aspects, wherein the acid gas removal device is configured to operate under the conditions of a pressure of 60 barA to 70 barA and a temperature of 25 ° C to 40 ° C.
  • the heavy hydrocarbon is treated.
  • acidic gas and heavy hydrocarbons are more effectively removed by using a mixed absorbent under conditions of appropriate pressure and temperature in the acidic gas removal device. Is possible.
  • the natural gas liquefaction method is a natural gas liquefaction method in which natural gas supplied as a raw material gas is cooled to produce liquefied natural gas, and the acid contained in the raw material gas An acid gas removal step for removing gas; and a liquefaction step for liquefying the raw material gas from which the acidic gas has been removed by heat exchange with a refrigerant, wherein the raw material gas is benzene, toluene as a heavy hydrocarbon, and The xylene concentration is 0.1 mol% or less, and in the acidic gas removal step, a mixed absorbent in which the chemical absorbent that absorbs the acidic gas and the physical absorbent that absorbs the heavy hydrocarbons are mixed.
  • the raw material gas is processed.
  • FIG. 1 is a schematic configuration diagram of a natural gas liquefaction system 1 according to an embodiment of the present invention.
  • the liquefaction system 1 generates liquefied natural gas (LNG) by cooling a raw material gas (natural gas to be liquefied).
  • the liquefaction system 1 includes an absorption tower (acid gas removal device) 2 that removes the acidic gas contained in the raw material gas, a regeneration tower (absorbent regeneration device) 3 that regenerates the absorption liquid used in the absorption tower 2, and a raw material.
  • Gas-liquid separation device 4 for gas-liquid separation of moisture contained in gas, moisture removal devices 5A-5C for removing moisture contained in source gas, and unnecessary components (acid gas, heavy component, moisture, mercury, etc.) And the liquefying device 6 for liquefying the raw material gas from which the gas is removed.
  • the raw material gas processed in the liquefaction system 1 is not particularly limited.
  • natural gas obtained from a pressurized state collected from shale gas, tight sand gas, coal bed methane, or the like is used as the raw material gas.
  • Can do Further, as a method for supplying the raw material gas to the liquefaction system 1, not only supply from a gas field or the like through a pipe but also gas once stored in a storage tank or the like may be supplied.
  • a heavy component here, a heavy hydrocarbon composed of at least one of benzene, toluene, and xylene
  • source gas in the present specification does not mean that the gas is strictly in a gas state, but refers to an object (including during the process) to be liquefied by the liquefaction system 1.
  • the absorption tower 2 is a tray tower provided with shelves at regular intervals inside the tower, and the component to be removed is brought into countercurrent contact with the raw material gas supplied via the transport line L1. (Here, the acid gas and heavy components) are absorbed by the absorption liquid (acid gas removal step).
  • the source gas from which the component to be removed has been removed in the absorption tower 2 is sent from the top of the tower to the gas-liquid separator 4 via the transport line L2.
  • the absorbing liquid that has absorbed the component to be removed is sent to the regeneration tower 3.
  • the regeneration tower 3 is provided with a shelf, and the absorption liquid is treated at a predetermined pressure (here, 1 to 2 barA) and temperature (here, 130 ° C. to 140 ° C.). Thus, the component to be removed is separated from the absorbing liquid.
  • the absorption liquid from the absorption tower 2 is supplied from the upper part of the tower via the transport line L3 and falls in the tower.
  • a reboiler 11 serving as a heat source for the regeneration tower 3 is provided in the circulation line L4 connected to the bottom of the regeneration tower 3.
  • the absorption liquid from which the component to be removed has been separated in the regeneration tower 3 is supplied again to the upper part of the absorption tower 2 via the transport line L7.
  • a heat exchanger 12 is provided between the transportation line L3 and the transportation line L7, so that the absorption liquid at a lower temperature (here, 25 ° C. to 40 ° C.) flowing through the transportation line L3 is higher than flowing through the transportation line L7. (Here, 130 ° C. to 140 ° C.) After being heated by heat exchange with the absorption liquid, it is supplied to the regeneration tower 3, while the absorption liquid flowing through the transport line L7 is cooled by the heat exchange and then the absorption tower 2 is supplied.
  • the absorption liquid includes a chemical absorbent that absorbs acidic gas components such as carbon dioxide, hydrogen sulfide, mercaptan, and carbonyl sulfide based on a chemical reaction, and heavy carbonization such as benzene, toluene, and xylene contained in the raw material gas. It is a mixed absorbent containing a physical absorbent that physically absorbs hydrogen (heavy content) in a predetermined ratio. Further, the absorbing liquid contains water at a predetermined ratio.
  • the chemical absorbent is a basic compound that reacts with an acid gas, and in this embodiment, it is composed of methyldiethanolamine (MDEA) and piperazine (DEDA), but is not limited to this, diisopropanolamine (DIPA), diethanolamine (DEA). Secondary amines, tertiary amines, alkanolamines or heterocyclic amines, or a mixture of two or more thereof, including methyl monoethanolamine (MMEA) and diethyl monoethanolamine (DEMEA) .
  • MDEA methyldiethanolamine
  • DEDA diisopropanolamine
  • DEDA diethanolamine
  • the physical absorbent is a solvent that physically absorbs heavy hydrocarbons, and in the present embodiment, it is composed of sulfolane.
  • the physical absorbent is not limited to this, but fatty acid amide, N-methylpyrrolidone, and N-alkylated pyrrolidone or theirs. Derivatives, or mixtures of two or more thereof can be used.
  • the raw material gas removed in the absorption tower 2 until the removal target component becomes a predetermined concentration or less is cooled by the cooler 15 provided on the transport line L2, and then sent to the gas-liquid separation device 4.
  • Propane refrigerant is used for cooling in the cooler 15, whereby moisture in the raw material gas is condensed and discharged to the outside as a liquid phase component in the gas-liquid separator 4 from the transport line L 8.
  • the raw material gas separated as the gas phase component in the gas-liquid separation device 4 is supplied to each of the three water removal devices 5A to 5C via the transport line L9.
  • the liquefaction system 1 is provided with a known refrigeration cycle facility including a compressor for propane refrigerant, a condenser, and the like, and the cooler 15 includes the cooler 21 described later. Part of refrigeration cycle equipment.
  • the water removing devices 5A to 5C are composed of a dehydrating tower filled with a moisture absorbent (here, molecular sieve) that physically adsorbs moisture.
  • the dehydration treatment may be performed so that the moisture in the raw material gas is preferably less than 0.1 ppmv (parts per million by volume). Thereby, the water
  • the moisture removing devices 5A to 5C other known devices can be adopted as long as moisture in the raw material gas can be removed to a desired ratio or less.
  • the raw material gas from which moisture has been removed in the moisture removing devices 5A to 5C is supplied to the liquefying device 6 via the transport line L10.
  • an expander, a distillation tower, a compressor, and the like are provided upstream of this type of liquefaction apparatus in order to remove heavy components (that is, a distillation operation involving decompression and pressurization of a raw material gas is performed).
  • a distillation operation involving decompression and pressurization of a raw material gas is performed.
  • the liquefaction system 1 is not limited to the above-described apparatus, and the source gas is used to remove unnecessary components in the source gas before the source gas is supplied to the liquefier 6. It is possible to further provide other known equipment such as a mercury removing device for removing mercury in the inside (for example, a fixed bed type adsorption tower filled with activated carbon).
  • the liquefying device 6 (main heat exchanger) liquefies the raw material gas from which unnecessary components such as acid gas and heavy components are removed by heat exchange with the mixed refrigerant (liquefaction step).
  • the liquefying device 6 includes a spool-type heat exchanger in which a heat transfer tube (tube bundle) for flowing a raw material gas and a mixed refrigerant is wound in a coil shape, and is housed in a shell, but is not limited thereto.
  • Other known configurations such as plate fin heat exchange can be used as long as liquefaction of the source gas is possible.
  • the liquefaction treatment by the liquefaction system 1 adopts a C3-MR (C3-MR: Propane (C3) pre-cooled Mixed Refrigerant) method, and is upstream of the liquefaction device 6 (on the transportation line L10).
  • C3-MR Propane (C3) pre-cooled Mixed Refrigerant
  • the raw material gas supplied to the liquefying device 6 may be boosted by a known compressor or the like.
  • a mixed refrigerant obtained by adding nitrogen to a hydrocarbon mixture containing methane, ethane, and propane is used, but not limited to this, as long as a desired cooling capacity can be ensured, other known ones can be used. Ingredients can be employed.
  • the liquefying device 6 is provided with a compressor, a condenser, and the like constituting a known refrigeration cycle for the mixed refrigerant.
  • the low-temperature (about ⁇ 162 ° C.) raw material gas liquefied by cooling in the liquefying device 6 is sent to a storage LNG tank (not shown) via the transport line L12.
  • the liquefaction treatment by the liquefaction device 6 is not limited to the C3-MR method, but is a cascade method in which individual refrigeration cycles are constituted by a plurality of refrigerants (methane, ethane, propane, etc.) having different boiling points, and mixed refrigerants such as ethane and propane.
  • DMR Double Mixed Refrigerant
  • MFC Mated Fluid Fluid Cascade
  • Table 1 shows examples of processing conditions (Case 1 to Case 4) applicable to the natural gas liquefaction system 1 shown in FIG.
  • the conditions are common except for the concentration of benzene and xylene contained in the raw material gas, the concentration of toluene, and the circulation amount of the absorbing liquid between the absorption tower 2 and the regeneration tower 3. Yes.
  • the flow rate of the source gas in the liquefaction system 1 (amount supplied to the absorption tower 2) is not particularly limited, but here, as shown in Table 1, 1000 t / hr corresponding to the throughput of a relatively large-scale liquefaction system. Intended for degree.
  • the temperature of the supplied raw material gas is 25 ° C., but it may be adjusted in the range of 25 ° C. to 40 ° C. in the absorption tower 2.
  • the temperature of the raw material gas in the absorption tower 2 is 25 ° C. or lower, there is a problem that the absorption capacity of the acidic gas is lowered.
  • the pressure of the raw material gas in the absorption tower 2 (treatment pressure in the absorption tower 2) is 66 barA, the pressure is not limited to this and can be changed. However, the pressure of the raw material gas in the absorption tower 2 may be adjusted in the range of 60 barA to 70 barA in order to reduce the processing load of the subsequent liquefaction apparatus 6. Further, when the pressure of the raw material gas supplied to the liquefying device 6 is lower than a desired value, the pressure of the raw material gas can be increased by introducing a compressor as described above.
  • the acid gas contained in the raw material gas supplied to the liquefaction system 1 has a carbon dioxide (CO 2 ) concentration of 0.2 vol% and a hydrogen sulfide (H 2 S) concentration of 0.001 ppmv.
  • CO 2 carbon dioxide
  • H 2 S hydrogen sulfide
  • the carbon dioxide concentration in the raw material gas supplied to the liquefying device 6 is set to be less than 50 ppmv, more preferably less than 25 ppmv.
  • the hydrogen sulfide concentration in the raw material gas supplied to the liquefying device 6 is less than 3 ppmv.
  • the total of benzene (BZ) concentration and xylene (XY) concentration is 16ppmv, 55ppmv, 550ppmv, 1100ppmv for Case 1 to Case 4, respectively.
  • the toluene (TOL) concentration is 5 ppmv, 20 ppmv, 200 ppmv, and 400 ppmv for Case 1 to Case 4, respectively.
  • the target concentrations of benzene, xylene, and toluene (BTX) in the raw material gas sent through the transport line L2 after being treated in the absorption tower 2 are determined by the solidification of heavy components in the subsequent liquefaction treatment or the like.
  • the BTX as a whole is made 16 ppmv or less, preferably the benzene concentration is 1 ppmv or less, the xylene concentration is 1.6 ppmpv or less, and the toluene concentration is 15 ppmv or less.
  • the target concentration can be achieved even in case 4 (benzene concentration and xylene concentration are 1100ppmv, toluene concentration is 400ppmv) in cases 1 to 4 above. .
  • the increase in the circulation flow rate of the absorbing liquid leads to an increase in the size of the absorption tower 2 and the regeneration tower 3, preferably the total of the benzene (BZ) concentration and the xylene (XY) concentration as in cases 1 to 3. 550ppmv or less, toluene (TOL) concentration should be 200ppmv or less, and circulation flow rate must be maintained in the proper range (here, 4500t / hr or less).
  • each of benzene, xylene, and toluene is used as long as the concentration of the entire BTX is 1000 ppmv (0.1 mol%) or less, more preferably 750 ppmv (0.075 mol%) or less.
  • the concentration can be increased or decreased.
  • the absorption liquid used in the absorption tower 2 is 38 wt% methyldiethanolamine (MDEA) and 7 wt% piperazine (DEDA) as a chemical absorbent, 40 wt% sulfolane as a physical adsorbent, Composed of 15wt% water.
  • MDEA methyldiethanolamine
  • DEDA piperazine
  • the concentration of the chemical absorbent in the absorbent is preferably in the range of 40 wt% to 50 wt%.
  • the concentration of sulfolane in the absorbing solution is preferably in the range of 10 wt% to 40 wt%, more preferably in the range of 35 wt% to 40 wt%.
  • the concentration of sulfolane is less than 10 wt%, it is difficult to reduce BTX in the absorption tower 2 to the target concentration.
  • the concentration of sulfolane exceeds 40 wt%, the amount of methane absorbed along with the heavy components (that is, the amount of methane loss) increases.
  • the absorbent preferably contains a certain amount of water for viscosity adjustment, etc., and a chemical absorbent (in this case, methyldiethanolamine (MDEA) and piperazine (DEDA)) so that the sulfolane concentration exceeds 40 wt%. If the concentration of is decreased, there arises a problem that it becomes difficult to remove the acid gas.
  • MDEA methyldiethanolamine
  • DEDA piperazine
  • the raw material gas having a relatively low concentration of heavy hydrocarbons (the sum of the concentrations of benzene, toluene and xylene as heavy components is 1000 ppmv (0.1 mol%) or less, more preferably 750 ppmv (
  • the absorption liquid containing a physical absorbent that absorbs heavy hydrocarbons in the absorption tower 2 is used to remove heavy hydrocarbons together with acid gas. Removes heavy components in raw gas to a level (target concentration) that can prevent clogging of piping, etc. without the need for dedicated equipment (distillation equipment, etc.) to remove heavy components in raw material gas It becomes possible to do.
  • the absorption liquid contains 10 to 40 wt% of sulfolane as a physical absorbent, and benzene without affecting other components (chemical absorbent, water, etc.) by such an appropriate proportion of physical absorbent. It is possible to more effectively remove heavy hydrocarbons such as xylene and toluene.

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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)
  • Gas Separation By Absorption (AREA)

Abstract

[Problème] Eliminer les matières lourdes contenues dans un gaz d'alimentation dans un système de liquéfaction dans laquelle le gaz d'alimentation est refroidi pour produire un gaz naturel liquéfié, sans qu'un quelconque dispositif ne soit utilisé exclusivement pour éliminer les matières lourdes du gaz d'alimentation. [Solution] Un système de liquéfaction (1) équipé : d'une colonne d'absorption (2) dans laquelle les gaz acides contenus dans un gaz d'alimentation sont éliminés ; et d'un dispositif de liquéfaction (6) dans lequel le gaz d'alimentation duquel les gaz acides ont été éliminés est soumis à un échange thermique avec un réfrigérant afin de liquéfier le gaz d'alimentation. Le gaz d'alimentation présente une concentration totale en benzène, en toluène et en xylène, en tant qu'hydrocarbures lourds, inférieure ou égale à 0,1 % en mole. Dans le dispositif d'élimination de gaz acides, on utilise un mélange de matières absorbantes obtenu par le mélange d'un absorbant chimique servant à absorber les gaz acides et d'un absorbant physique servant à absorber les hydrocarbures lourds.
PCT/JP2015/002089 2014-04-16 2015-04-15 Système et procédé de liquéfaction du gaz naturel WO2015159546A1 (fr)

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CN106310691B (zh) * 2016-10-11 2018-06-22 成都深冷液化设备股份有限公司 一种提纯化工尾气中h2s的工艺和装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09194851A (ja) * 1995-12-28 1997-07-29 Inst Fr Petrole 溶媒混合物を用いる天然ガスからの脱水および液体炭化水素の分離方法
JP2005164235A (ja) * 1999-10-12 2005-06-23 Air Products & Chemicals Inc ガス液化装置
WO2011071150A1 (fr) * 2009-12-11 2011-06-16 財団法人地球環境産業技術研究機構 Absorbant de dioxyde de carbone destiné à être utilisé sous pression élevée, et procédé d'absorption et de collecte du dioxyde de carbone sous pression élevée
JP2012143760A (ja) * 2006-05-18 2012-08-02 Basf Se 再生のためのエネルギー必要量が低減された、二酸化炭素吸収剤および気体流から二酸化炭素を除去するための方法
JP2014036933A (ja) * 2012-08-17 2014-02-27 Research Institute Of Innovative Technology For The Earth 高圧二酸化炭素含有ガス流から二酸化炭素を分離回収するための液状吸収剤及び分離回収方法

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09194851A (ja) * 1995-12-28 1997-07-29 Inst Fr Petrole 溶媒混合物を用いる天然ガスからの脱水および液体炭化水素の分離方法
JP2005164235A (ja) * 1999-10-12 2005-06-23 Air Products & Chemicals Inc ガス液化装置
JP2012143760A (ja) * 2006-05-18 2012-08-02 Basf Se 再生のためのエネルギー必要量が低減された、二酸化炭素吸収剤および気体流から二酸化炭素を除去するための方法
WO2011071150A1 (fr) * 2009-12-11 2011-06-16 財団法人地球環境産業技術研究機構 Absorbant de dioxyde de carbone destiné à être utilisé sous pression élevée, et procédé d'absorption et de collecte du dioxyde de carbone sous pression élevée
JP2014036933A (ja) * 2012-08-17 2014-02-27 Research Institute Of Innovative Technology For The Earth 高圧二酸化炭素含有ガス流から二酸化炭素を分離回収するための液状吸収剤及び分離回収方法

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