WO2020021633A1 - Natural gas treatment device and natural gas treatment method - Google Patents

Natural gas treatment device and natural gas treatment method Download PDF

Info

Publication number
WO2020021633A1
WO2020021633A1 PCT/JP2018/027710 JP2018027710W WO2020021633A1 WO 2020021633 A1 WO2020021633 A1 WO 2020021633A1 JP 2018027710 W JP2018027710 W JP 2018027710W WO 2020021633 A1 WO2020021633 A1 WO 2020021633A1
Authority
WO
WIPO (PCT)
Prior art keywords
natural gas
condensate
methane
gas
supply line
Prior art date
Application number
PCT/JP2018/027710
Other languages
French (fr)
Japanese (ja)
Inventor
徹 中山
Original Assignee
日揮グローバル株式会社
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 日揮グローバル株式会社 filed Critical 日揮グローバル株式会社
Priority to KR1020207016933A priority Critical patent/KR102642311B1/en
Priority to CN201880077980.1A priority patent/CN111433329A/en
Priority to PCT/JP2018/027710 priority patent/WO2020021633A1/en
Publication of WO2020021633A1 publication Critical patent/WO2020021633A1/en

Links

Images

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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
    • C10L3/00—Gaseous fuels; Natural gas; Synthetic natural gas obtained by processes not covered by subclass C10G, C10K; Liquefied petroleum gas
    • C10L3/06—Natural gas; Synthetic natural gas obtained by processes not covered by C10G, C10K3/02 or C10K3/04
    • C10L3/10—Working-up natural gas or synthetic 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
    • F25J1/02—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
    • F25J1/0244—Operation; Control and regulation; Instrumentation
    • F25J1/0245—Different modes, i.e. 'runs', of operation; Process 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
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0238—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 2 carbon atoms or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/04—Mixing or blending of fluids with the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
    • F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • 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
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2260/00—Coupling of processes or apparatus to other units; Integrated schemes
    • F25J2260/20—Integration in an installation for liquefying or solidifying a fluid 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
    • F25J2280/00—Control of the process or apparatus
    • F25J2280/02—Control in general, load changes, different modes ("runs"), measurements

Definitions

  • the present invention relates to a natural gas processing apparatus for processing natural gas.
  • Natural gas processing equipment for processing natural gas which is a hydrocarbon gas produced from a wellhead, includes a pretreatment facility that performs pretreatment to remove various impurities from natural gas before liquefaction, and a pretreatment And a liquefaction facility for liquefying natural gas to obtain LNG (Liquidized Natural Gas).
  • a pretreatment facility moisture and carbon dioxide are removed to prevent clogging of the natural gas cooled to -150 ° C or less in the liquefaction facility, and impurities such as hydrogen sulfide are removed. Done.
  • Patent Literature 1 discloses that when liquefied natural gas (LNG) is produced from natural gas or CSG (coal seam gas), natural gas before liquefaction is brought into contact with MDEA (N-methyldiethanolamine).
  • LNG liquefied natural gas
  • MDEA N-methyldiethanolamine
  • An absorption facility that absorbs and removes hydrogen sulfide and carbon dioxide, and a natural gas that flows through a dehydration plant (adsorption tower) equipped with a molecular sieve (adsorbent) container to adsorb and remove moisture.
  • the facilities are listed.
  • the gas output from development to depletion gradually increases after the start of natural gas output, and shifts to a period (plateau period) in which the output is stable at a high output. Then, following the plateau period, a decline period in which the output gradually decreases, and the production of natural gas ends soon.
  • the supply amount of the natural gas supplied to each facility changes with the change in the production amount of the natural gas.
  • the pretreatment equipment for removing impurities including the above-mentioned absorption equipment and adsorption equipment is generally designed to increase the processing efficiency when processing the supply amount of natural gas during the plateau period. For this reason, there has been a problem that the processing efficiency deteriorates in the decline period in which the output gradually decreases.
  • the present invention has been made under such a background, and provides a technique for stably removing impurities contained in natural gas even when the supply amount of natural gas is reduced. Is to do.
  • the natural gas processing apparatus of the present invention includes an adsorption facility for adsorbing and removing impurities contained in natural gas using an adsorbent, and an absorption facility for bringing natural gas into contact with an absorbent to remove impurities contained in natural gas.
  • an impurity removal equipment group that removes impurities contained in natural gas supplied via the supply line
  • a natural gas treated in the impurity removal equipment group is separated by distillation into methane and heavy hydrocarbons having 2 or more carbon atoms, and a distillation equipment for sending the methane through an air supply line,
  • a recycle gas line for dividing a part of the supplied methane and merging with natural gas supplied from the supply line to the impurity removal equipment group.
  • the natural gas processing device may have the following features.
  • a liquefaction facility for liquefying methane sent from the distillation facility is provided.
  • the air supply line includes a compressor that pressurizes the methane, and the recycle gas line is provided at a position where a part of the methane is diverted from an outlet side of the compressor. thing.
  • C After separating the condensate which is a liquid component contained in the natural gas before being supplied to the impurity removing equipment group, the natural gas after the condensate separation is supplied to the impurity removing equipment group via the supply line.
  • the condensate is supplied via a condensate supply line, a vapor pressure adjusting device for adjusting the vapor pressure of the condensate by distilling and separating light hydrocarbons contained in the condensate, A condensate recycle line that separates a part of the condensate after the light hydrocarbons are separated by the vapor pressure adjusting equipment, and merges with the condensate supplied to the steam pressure adjusting node equipment from the condensate supply line. .
  • the condensate recycle line is detachably provided between a condensate extraction line for extracting condensate from the vapor pressure adjusting node equipment and the condensate supply line.
  • the impurity removal equipment group and the distillation equipment are provided on a floating body floating on the sea.
  • a liquefaction facility for liquefying methane sent from the distillation facility is provided on the floating body.
  • a plurality of pretreatment facilities when processing natural gas, prior to liquefaction of natural gas, a plurality of pretreatment facilities perform impurity removal treatment, and then separate into methane and heavy hydrocarbons. It is recycled at the entrance of the removal process. Therefore, even when the processing amount of natural gas decreases, the processing amount of natural gas in each pretreatment facility can be maintained, and efficient and stable processing can be performed.
  • the natural gas processing apparatus of this example is configured as a natural gas liquefaction apparatus that separates and liquefies methane contained in natural gas (also indicated as NG in each figure).
  • NG processed by the natural gas liquefaction apparatus of this example contains at least hydrogen sulfide or carbon dioxide, and further contains moisture, mercury, and oxygen.
  • the natural gas from which the liquid has been separated is first subjected to removal of carbon dioxide, hydrogen sulfide, and the like (these may be collectively referred to as “acid gas”) in an acid gas removal step 22.
  • the equipment in the acid gas removal step 22 is constituted by, for example, an absorption equipment provided with an absorption tower for bringing an absorption liquid that absorbs an acid gas into contact with natural gas in a countercurrent direction, and an acid that may be solidified in LNG during liquefaction. Gases such as carbon dioxide and hydrogen sulfide are absorbed and removed from natural gas into the absorbing solution.
  • the natural gas treated in the acid gas removing step 22 is further removed in a water removing step 23. Further, in the natural gas treated in the water removing step 23, mercury is removed in the mercury removing step 24.
  • the equipment for performing the water removal step 23 and the mercury removal step 24 includes, for example, an adsorption tower which is an adsorption apparatus filled with an adsorbent for adsorbing moisture and a mercury adsorbent for adsorbing mercury, respectively. These adsorption towers allow natural gas to pass through the adsorption tower, thereby allowing natural gas to pass through gaps between the adsorbents filled in the adsorption tower, thereby bringing the natural gas into contact with the adsorbent.
  • This mercury removal step 24 can be placed before the acid gas removal step 22.
  • the equipment group including the pretreatment equipment for performing the acid gas removal step 22, the water removal step 23, and the mercury removal step 24 is referred to as an impurity removal equipment group 20.
  • the natural gas from which the impurities have been removed is separated into methane and heavy hydrocarbons having 2 or more carbon atoms in a hydrocarbon separation step 25.
  • a hydrocarbon separation step for example, a distillation facility (demethanizer) is used.
  • the detailed description of the hydrocarbon separation equipment including the demethanizer will be described later.
  • the methane separated in the hydrocarbon separation step 25 is liquefied in the liquefaction step 26 to become liquefied natural gas (LNG).
  • the LNG is then vaporized (end-flashed) by partially vaporizing (end-flashing) the LNG, thereby performing an end-flash gas step 27 for adjusting the temperature of the LNG, a step 28 for storing the LNG, and the like, and is shipped to an LNG tanker, for example.
  • a part of the liquid component (condensate) gas-liquid separated from the natural gas in the gas-liquid separation step 21 is stored as a condensate 32 and shipped after a vapor pressure adjustment step 31 for removing light hydrocarbons is performed. You. Furthermore, the antifreeze containing water is phase-separated from the gas-liquid separated condensate, and the antifreeze regeneration process 30 is performed on the antifreeze. Monoethylene glycol (MEG) or the like is used as the antifreeze, and the regenerated antifreeze is supplied to the natural gas well. Further, the end flash gas and the boil-off gas (BOG) evaporated from the LNG in the LNG storage step 28 are subjected to a pressure increasing process 29 and are mainly used as combustion gas. It can be liquefied again by returning to the previous stage.
  • MEG Monoethylene glycol
  • BOG boil-off gas
  • the methane separated in the hydrocarbon separation step 25 is returned to the supply line 100 that supplies the natural gas to the acid gas removal step 22, and is converted into the natural gas supplied from the gas-liquid separation step 21 side.
  • a recycle gas line 10 for merging is provided. The recycle gas line 10 will be described together with the description of the equipment for performing the hydrocarbon separation step 25.
  • FIG. 2 is a configuration example of a hydrocarbon separation facility constituting a natural gas processing apparatus.
  • the hydrocarbon separation equipment includes a natural gas supply line 101 to which the natural gas processed in the mercury removal step 24 is supplied, cold boxes 11 and 12 for cooling the natural gas supplied from the natural gas supply line 101, A feed separator 13 that performs gas-liquid separation of natural gas that has been cooled and partially liquefied in boxes 11 and 12, and a natural gas is distilled to separate methane and heavy hydrocarbons having 2 or more carbon atoms.
  • a demethanizer 17 A demethanizer 17.
  • Natural gas supplied from the natural gas supply line 101 is cooled by the cold boxes 11 and 12 and is separated into gas and liquid by the feed separator 13. Then, a part of the gas component is decompressed and expanded by the expander 14 and supplied to the demethanizer 17 as a gas-liquid mixture at ⁇ 50 to ⁇ 80 ° C.
  • Reference numeral 15 in FIG. 2 denotes a JT (Joule-Thomson) valve 15. Further, the remaining gas component of the natural gas separated into gas and liquid by the feed separator 13 is cooled in the cold box 16 and then decompressed and expanded by the decompression valve 104 to obtain a gas-liquid mixture at -70 to -100 ° C. Is supplied to the demethanizer 17.
  • the liquid component gas-liquid separated by the feed separator 13 is used as a refrigerant for the cold box 12 and then supplied to the demethanizer 17.
  • the demethanizer 17 separates methane by distilling the supplied gas-liquid mixture of natural gas, and discharges the methane through an air supply line 105 provided at the top of the tower. Also, heavy hydrocarbons (C2 +), which are heavier than ethane, are allowed to flow out of the bottom of the tower. Note that reference numeral 171 in FIG. 2 indicates a reboiler. Further, the hydrocarbon separation equipment according to the present embodiment uses methane discharged from the demethanizer 17 and liquid components of natural gas separated by the feed separator 13 as refrigerant for the cold boxes 11 and 12. That is, the demethanizer 17 according to the present embodiment is configured as a distillation apparatus of a self-refrigerant type.
  • the methane flowing out of the demethanizer 17 is used as a refrigerant for the cold box 11, is pressurized by the compressor 311 and the booster compressor 312, is further cooled by the air cooler 320, and is sent to equipment for performing the liquefaction step 26. .
  • One end of the recycle gas line 10 is connected to a downstream side of the compressor 311 in the air supply line 105.
  • the other end of the recycle gas line 10 is connected to a supply line 100 on the inlet side of the impurity removing equipment group 20, in this example, on the inlet side of the acid gas removing step 22, as shown in FIG.
  • the recycle gas line 10 may be provided with a pressure control valve V10.
  • the amount of natural gas produced varies depending on the time elapsed since the development of the well.
  • the facilities in the natural gas processing apparatus for example, in the liquefaction facility for performing the liquefaction step 26 and the subsequent steps 27 and 28, even if the supply amount of the natural gas changes, the processing efficiency is hardly affected. .
  • the energy required to liquefy methane gas per unit weight and end-flash or store LNG does not change significantly.
  • the acid gas removal step 22 uses an absorption tower, and the moisture removal step 23 and the mercury removal step 24 use an adsorption tower.
  • the amount of supplied natural gas is less than the design flow rate
  • the amount of absorbing liquid also decreases in accordance with the amount of natural gas, so that both the steam load and the liquid load make the appropriate operation range.
  • the absorption tower cannot exhibit predetermined performance, and as a result, it may be difficult to continue the operation of the absorption tower.
  • the natural gas supplied to the adsorption tower in the water removal step 23 and the mercury removal step 24 becomes smaller than a fluctuation range suitable for operation
  • the natural gas supplied to the adsorption tower becomes a part of the filled adsorbent.
  • a drift channeling
  • natural gas comes into contact with only a part of the filled adsorbent, and the adsorption efficiency of components to be adsorbed (moisture and mercury) contained in the gas deteriorates.
  • the short circuit path may be fixed.
  • the life of the adsorbent may be extremely shorter than the design life on the premise of the entire adsorbent.
  • the demethanizer 17 in the hydrocarbon separation step 25 is a distillation column.
  • this demethanizer is a process of separating heavy hydrocarbons by performing self-cooling by introducing cold gas generated by the expander 14 into the cold boxes 11, 12, and 16 by supplying supplied natural gas to the cold boxes 11, 12, and 16.
  • the amount of supplied gas decreases, the cooling heat obtained by the expander 14 also decreases, and the efficiency of separating heavy hydrocarbons decreases.
  • the influence of the natural gas supply from the well base being lower than the design flow rate is mainly manifested in the impurity removing equipment group 20 and the demethanizer 17 which is the distillation equipment in the hydrocarbon separation step 25. .
  • the design flow rate of natural gas in each facility is often set based on the supply flow rate of natural gas during the plateau period.
  • small and medium-sized gas fields have a relatively short plateau period, and may transition to a decline period in a short period of several years to 10 years. For this reason, the period during which the natural gas processing device exhibits the performance according to the design flow rate is shortened, and the production efficiency may be reduced.
  • the natural gas processing apparatus when the gas field at the base of the well enters the decline period and the supply of natural gas decreases, a part of the methane gas is removed through the recycle gas line 10 into the impurity removal equipment group. Recycle to the entrance side of 20. For example, when the supply flow rate of the natural gas supplied to the acid gas removal step 22 via the supply line 100 becomes lower than a preset flow rate, the recycle gas line 10 is brought online. Then, the amount of methane gas recycled is adjusted by the control valve V10 shown in FIG. 2 so that the supply flow rate of the natural gas supplied to the acid gas removal step 22 is substantially equal to, for example, the plateau period.
  • the natural gas supplied to the impurity removing equipment group 20 is supplied to the impurity removing equipment group 20.
  • natural gas is supplied to the absorption tower in the acid gas removal step 22 at a flow rate similar to that during the plateau period.
  • the supply flow rate of the natural gas supplied to the impurity removing equipment group 20 and the hydrocarbon separation equipment that is, the flow rate of the natural gas flowing in each equipment can be maintained at about the same as the plateau period.
  • the steam load due to the shortage of the natural gas flow rate can be maintained at an operable flow rate, and the state in which the acid gas can be efficiently absorbed can be maintained.
  • each of the adsorption towers in the subsequent water removal step 23 and the mercury removal step 24 the occurrence of channeling due to a shortage of the flow rate of natural gas can be suppressed, and the state in which moisture and mercury can be adsorbed efficiently can be maintained.
  • the demethanizer (distillation equipment) 17 in the hydrocarbon separation equipment a reduction in the amount of cold heat generated due to a shortage of the supply flow rate of the liquefied natural gas and a reduction in the steam load in the distillation column are suppressed, and the distillation and separation of methane gas is efficiently performed. It can be carried out.
  • the natural gas flow rate can be maintained.
  • the amount of methane gas recycled is not limited to the case where the pressure on the inlet side of the impurity removing equipment group 20 is adjusted to an amount that can be maintained at the same level as the plateau period. For example, in consideration of the flow rate that can be supplied to the recycle gas line 10, even if the pressure is set to be maintained at a value equal to or more than 80% of the plateau period, an appropriate value according to the facility capacity or the like may be set. Good.
  • the impurity removal treatment is performed before the natural gas is liquefied, and then the hydrocarbon separation step 25 is performed. It is recycled at the entrance. Therefore, the output of the natural gas at the well base is reduced, and even when the supply of the natural gas is reduced, the amount of the natural gas supplied to the impurity removing equipment group 20 can be maintained at the same level as the plateau period. . Therefore, the pretreatment equipment (acid gas absorption tower or moisture and mercury adsorption tower) provided in the impurity removal equipment group 20 and the demethanizer 17 provided in the hydrocarbon separation equipment reduce the supply amount of natural gas. It is possible to suppress a decrease in the processing efficiency and perform a stable processing.
  • the equipment for performing the vapor pressure adjustment step 31 includes a distillation column (stabilizer) 131 for condensate, and the condensate separated in the gas-liquid separation step 21 described above is supplied via the condensate supply line 106. Is done.
  • an extraction line 108 for extracting the light gas separated by distillation of the condensate is connected to the top of the stabilizer 131, and the extracted light gas is compressed by, for example, the compressor 41 and then to the acid gas removal step 22. Merges with the supply line 100.
  • a condensate extraction line 107 for extracting condensate from which light gas accumulated at the bottom of the stabilizer 131 has been separated is connected to the bottom of the stabilizer 131, and the extracted condensate is discharged to the condensate storage step 32.
  • Reference numeral 43 provided on the condensate extraction line 107 indicates a cooler.
  • a branch line 109 branches off from the condensate extraction line 107.
  • the reboiler 42 is interposed in the branch line 109, and heats the condensate containing the extracted heavy component and returns the condensate to the stabilizer 131.
  • One end of a condensate recycle line 110 is connected to the condensate extraction line 107 downstream of the cooler 43, and the other end is connected to a condensate supply line 106.
  • Reference numeral 44 in FIG. 3 indicates a pump.
  • the vapor pressure adjusting step 31 when the amount of condensate supplied to the stabilizer 131 decreases with the decrease in the amount of natural gas produced from the well base, the liquid load decreases and the processing efficiency decreases. Then, by returning the condensate containing heavy components to the inlet side through the condensate recycle line 110, the supply amount of the condensate to the stabilizer 131 can be maintained at the same level as the plateau period. Accordingly, even when the production amount of natural gas at the base of the well decreases during the decline period, the stabilizer 131 can suppress the decrease in the processing efficiency due to the decrease in the amount of condensate.
  • a condensate recycle line 110 may be detachably provided to the condensate supply line 106 and the condensate extraction line 107.
  • the condensate recycle line 110 can be installed when the well enters a decline period in which the production amount of natural gas decreases.
  • the stabilizer 131 can be installed from the beginning of construction.
  • the above-mentioned recycle gas line 10 for methane gas shown in FIG. 2 has a large diameter and a long drawing distance, it is difficult to make it detachable. Therefore, it is possible to exemplify a case where a natural gas liquefaction apparatus is installed at the time of construction, and the use of the natural gas liquefaction apparatus is started at the timing when the output of natural gas decreases.
  • each of the above embodiments is not limited to the case where the present invention is applied to a natural gas liquefaction apparatus provided with a natural gas liquefaction facility.
  • a recycled gas line for recycling part of the methane gas to the inlet side of the impurity removing equipment group 20 10 may be provided.
  • the natural gas processing device provided with the recycled gas line 10 may be provided on a floating body floating on the ocean.
  • Reference Signs List 10 supply line 17 demethanizer 22 acid gas removal step 23 moisture removal step 24 mercury removal step 25 hydrocarbon removal step 26 liquefaction step 31 vapor pressure adjustment step 100 recycle gas line 101 pretreatment equipment 102 liquefaction equipment 131 condensate distillation tower 311 compressor

Landscapes

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

Abstract

[Problem] To provide a technique for achieving the removal of impurities contained in natural gas stably even when the supply amount of the natural gas is decreased. [Solution] In a natural gas treatment device, an impurity removal treatment is carried out prior to the liquefaction of natural gas, and then a hydrocarbon separation step 25 is carried out, so that a portion of methane obtained after the separation can be recycled on an inlet port side of an impurity removal facility group 20. As a result, even when the production amount of natural gas in a wellhead is decreased and the supply amount of the natural gas is decreased, the amount of a gas to be supplied to the impurity removal facility group 20 can be increased. Consequently, the reduction in efficiency of the treatment in the impurity removal facility group 20 with the decrease in the amount of a gas to be treated in the impurity removal facility group 20 can be prevented.

Description

天然ガス処理装置及び天然ガス処理方法Natural gas processing apparatus and natural gas processing method
　本発明は、天然ガスの処理を行う天然ガス処理装置に関する。 (4) The present invention relates to a natural gas processing apparatus for processing natural gas.
　井戸元より産出された炭化水素ガスである天然ガスを処理するための天然ガス処理装置には、液化する前の天然ガスから各種の不純物を除去する前処理を行う前処理設備と、前処理後の天然ガスを液化してＬＮＧ（Liquidized Natural Gas）を得る液化設備とが設けられている。前処理設備においては、－１５０℃以下にまで冷却される天然ガスの液化設備内での閉塞などを防止するため、水分や二酸化炭素の除去が行われる他、硫化水素の除去などの不純物除去が行われる。 Natural gas processing equipment for processing natural gas, which is a hydrocarbon gas produced from a wellhead, includes a pretreatment facility that performs pretreatment to remove various impurities from natural gas before liquefaction, and a pretreatment And a liquefaction facility for liquefying natural gas to obtain LNG (Liquidized Natural Gas). In the pretreatment facility, moisture and carbon dioxide are removed to prevent clogging of the natural gas cooled to -150 ° C or less in the liquefaction facility, and impurities such as hydrogen sulfide are removed. Done.
　前処理設備の例として、特許文献１には、天然ガスまたはＣＳＧ（炭層ガス）から液化天然ガス（ＬＮＧ）を生成するにあたって、液化前の天然ガスをＭＤＥＡ（Ｎ-メチルジエタノールアミン）と接触させて、硫化水素や二酸化炭素を吸収して除去する吸収設備や、分子ふるい（吸着剤）容器を備えた脱水プラント（吸着塔）に天然ガスを通流させて、水分などを吸着させて除去する吸着設備が記載されている。 As an example of a pretreatment facility, Patent Literature 1 discloses that when liquefied natural gas (LNG) is produced from natural gas or CSG (coal seam gas), natural gas before liquefaction is brought into contact with MDEA (N-methyldiethanolamine). An absorption facility that absorbs and removes hydrogen sulfide and carbon dioxide, and a natural gas that flows through a dehydration plant (adsorption tower) equipped with a molecular sieve (adsorbent) container to adsorb and remove moisture. The facilities are listed.
　ところで天然ガス田において、開発から枯渇までのガスの産出量は、天然ガスの産出開始後、徐々に上昇し、産出量が高い状態で安定する期間（plateau期間）に移行する。その後plateau期間に続いて産出量が徐々に減少する減退期に入り、やがて天然ガスの産出が終了する。
　このような天然ガスの産出量の経過変化に伴って、天然ガス処理装置においては、各設備に供給される天然ガスの供給量が変化することになる。一方で、上述の吸収設備や吸着設備を含む不純物を除去する前処理設備においては、一般的にplateau期間における供給量の天然ガスを処理する際に、処理効率が高くなるように設計される。そのため産出量が徐々に減少する減退期に入ると処理効率が悪化してしまう問題があった。 By the way, in a natural gas field, the gas output from development to depletion gradually increases after the start of natural gas output, and shifts to a period (plateau period) in which the output is stable at a high output. Then, following the plateau period, a decline period in which the output gradually decreases, and the production of natural gas ends soon.
In the natural gas processing apparatus, the supply amount of the natural gas supplied to each facility changes with the change in the production amount of the natural gas. On the other hand, the pretreatment equipment for removing impurities including the above-mentioned absorption equipment and adsorption equipment is generally designed to increase the processing efficiency when processing the supply amount of natural gas during the plateau period. For this reason, there has been a problem that the processing efficiency deteriorates in the decline period in which the output gradually decreases.
特表２０１０－５３２７９６号公報Japanese Unexamined Patent Publication No. 2010-532796
　本発明は、このような背景の下になされたものであり、天然ガスの供給量が減少した場合であっても、天然ガスに含有される不純物の除去を安定して行うための技術を提供することにある。 The present invention has been made under such a background, and provides a technique for stably removing impurities contained in natural gas even when the supply amount of natural gas is reduced. Is to do.
　本発明の天然ガス処理装置は、吸着剤を用いて天然ガスに含まれる不純物を吸着除去する吸着設備と、天然ガスと吸収液とを接触させて天然ガスに含まれる不純物を除去する吸収設備とから少なくとも一つ選択された前処理設備を備え、供給ラインを介して供給される天然ガスに含まれる不純物を除去する不純物除去設備群と、
　前記不純物除去設備群にて処理された天然ガスを、メタンと炭素数２以上の重質炭化水素とに蒸留分離し、送気ラインを介して前記メタンを送気する蒸留設備と、
　前記送気されるメタンの一部を分流し、前記供給ラインから不純物除去設備群に供給される天然ガスと合流させるリサイクルガスラインと、を備えることを特徴とする。 The natural gas processing apparatus of the present invention includes an adsorption facility for adsorbing and removing impurities contained in natural gas using an adsorbent, and an absorption facility for bringing natural gas into contact with an absorbent to remove impurities contained in natural gas. With at least one pretreatment equipment selected from, an impurity removal equipment group that removes impurities contained in natural gas supplied via the supply line,
A natural gas treated in the impurity removal equipment group is separated by distillation into methane and heavy hydrocarbons having 2 or more carbon atoms, and a distillation equipment for sending the methane through an air supply line,
And a recycle gas line for dividing a part of the supplied methane and merging with natural gas supplied from the supply line to the impurity removal equipment group.
　前記天然ガス処理装置は以下の特徴を備えていてもよい。
（ａ）前記蒸留設備から送気されたメタンを液化するための液化設備を備えたこと。
（ｂ）前記蒸留設備は、前記天然ガスを減圧膨張させることにより温度低下させて得られた気液混合体に対して前記蒸留分離を行うことと、
　前記送気ラインは、前記メタンを昇圧する圧縮機を備え、前記リサイクルガスラインは、前記圧縮機の出口側から前記メタンの一部を分流する位置に設けられていることと、を特徴とすること。
（ｃ）前記不純物除去設備群に供給される前の天然ガスに含まれる液体分であるコンデンセートを分離した後、前記供給ラインを介して、前記コンデンセート分離後の天然ガスを前記不純物除去設備群に供給する気液分離設備と、
　コンデンセート供給ラインを介して前記コンデンセートが供給され、前記コンデンセートに含まれる軽質炭化水素を蒸留分離してコンデンセートの蒸気圧を調整する蒸気圧調整設備と、
　前記蒸気圧調整設備にて軽質炭化水素が分離された後のコンデンセートの一部を分流し、前記コンデンセート供給ラインから蒸気圧調整節設備に供給されるコンデンセートと合流させるコンデンセートリサイクルラインと、を備えること。
（ｄ）前記コンデンセートリサイクルラインは、前記蒸気圧調整節設備からコンデンセートを抜き出すコンデンセート抜出ラインと前記コンデンセート供給ラインとの間に着脱自在に設けられること。
（ｅ）前記不純物除去設備群及び前記蒸留設備は、洋上に浮かぶ浮体上に設けられたこと。
（ｆ）前記浮体上には、前記蒸留設備から送気されたメタンを液化するための液化設備が設けられていること。 The natural gas processing device may have the following features.
(A) A liquefaction facility for liquefying methane sent from the distillation facility is provided.
(B) performing the distillation separation on the gas-liquid mixture obtained by lowering the temperature by expanding the natural gas under reduced pressure,
The air supply line includes a compressor that pressurizes the methane, and the recycle gas line is provided at a position where a part of the methane is diverted from an outlet side of the compressor. thing.
(C) After separating the condensate which is a liquid component contained in the natural gas before being supplied to the impurity removing equipment group, the natural gas after the condensate separation is supplied to the impurity removing equipment group via the supply line. Gas-liquid separation equipment to supply,
The condensate is supplied via a condensate supply line, a vapor pressure adjusting device for adjusting the vapor pressure of the condensate by distilling and separating light hydrocarbons contained in the condensate,
A condensate recycle line that separates a part of the condensate after the light hydrocarbons are separated by the vapor pressure adjusting equipment, and merges with the condensate supplied to the steam pressure adjusting node equipment from the condensate supply line. .
(D) The condensate recycle line is detachably provided between a condensate extraction line for extracting condensate from the vapor pressure adjusting node equipment and the condensate supply line.
(E) The impurity removal equipment group and the distillation equipment are provided on a floating body floating on the sea.
(F) A liquefaction facility for liquefying methane sent from the distillation facility is provided on the floating body.
　本発明は、天然ガスを処理するにあたって、天然ガスの液化前に複数の前処理設備にて不純物除去処理を行い、次いでメタンと重質炭化水素に分離し、分離後のメタンの一部を不純物除去処理の入口側にリサイクルさせるようにしている。そのため天然ガスの処理量が少なくなったときにも各前処理設備における天然ガスの処理量を維持し、効率がよく安定した処理を行うことができる。 In the present invention, when processing natural gas, prior to liquefaction of natural gas, a plurality of pretreatment facilities perform impurity removal treatment, and then separate into methane and heavy hydrocarbons. It is recycled at the entrance of the removal process. Therefore, even when the processing amount of natural gas decreases, the processing amount of natural gas in each pretreatment facility can be maintained, and efficient and stable processing can be performed.
天然ガス処理装置にて実施される各種処理工程を示す工程図である。It is a process figure showing various processing steps performed by a natural gas processing unit. 前記天然ガス処理装置に設けられている炭化水素分離設備の構成図である。It is a block diagram of the hydrocarbon separation equipment provided in the said natural gas processing apparatus. 前記天然ガス処理装置に設けられているコンデンセートの蒸気圧調整設備の構成図である。It is a block diagram of the vapor pressure adjustment equipment of the condensate provided in the said natural gas processing apparatus.
　初めに、図１を参照しながら本例の天然ガス処理装置における天然ガスの処理の流れについて説明する。本例の天然ガス処理装置は、天然ガス（各図中にはＮＧとも記してある）に含まれるメタンを分離して液化する天然ガス液化装置として構成されている。　
　本例の天然ガス液化装置にて処理されるＮＧには、少なくとも硫化水素または二酸化炭素が含まれ、さらに、水分、水銀や酸素が含まれている。 First, the flow of natural gas processing in the natural gas processing apparatus of the present embodiment will be described with reference to FIG. The natural gas processing apparatus of this example is configured as a natural gas liquefaction apparatus that separates and liquefies methane contained in natural gas (also indicated as NG in each figure).
NG processed by the natural gas liquefaction apparatus of this example contains at least hydrogen sulfide or carbon dioxide, and further contains moisture, mercury, and oxygen.
　図１に示すように、天然ガスは、気液分離工程２１にて天然ガス中に含まれる液体が分離された後、液化前の前処理として不純物の除去が行われる。液体が分離された天然ガスは、まず酸性ガス除去工程２２にて、二酸化炭素や硫化水素など（これらをまとめて「酸性ガス」と呼ぶ場合がある）の除去が行われる。酸性ガス除去工程２２の設備は、例えば酸性ガスを吸収する吸収液と天然ガスとを向流接触させる吸収塔を備えた吸収設備で構成され、液化の際にＬＮＧ中で固化するおそれのある酸性ガスである二酸化炭素や硫化水素が、天然ガスから吸収液へと吸収、除去される。 は As shown in FIG. 1, after the natural gas is separated from the liquid contained in the natural gas in the gas-liquid separation step 21, impurities are removed as pretreatment before liquefaction. The natural gas from which the liquid has been separated is first subjected to removal of carbon dioxide, hydrogen sulfide, and the like (these may be collectively referred to as “acid gas”) in an acid gas removal step 22. The equipment in the acid gas removal step 22 is constituted by, for example, an absorption equipment provided with an absorption tower for bringing an absorption liquid that absorbs an acid gas into contact with natural gas in a countercurrent direction, and an acid that may be solidified in LNG during liquefaction. Gases such as carbon dioxide and hydrogen sulfide are absorbed and removed from natural gas into the absorbing solution.
　酸性ガス除去工程２２にて処理された天然ガスは、さらに、水分除去工程２３にて水分が除去される。さらに水分除去工程２３にて処理された天然ガスは、水銀除去工程２４にて水銀が除去される。
　これら水分除去工程２３、水銀除去工程２４を行う設備は、例えば夫々水分を吸着する吸着剤、水銀を吸着する水銀吸着剤が充填された吸着設備である吸着塔を備えている。これらの吸着塔は、吸着塔に天然ガスを通過させることで、天然ガスを吸着塔内に充填された吸着剤の間の隙間を通過させて天然ガスと吸着剤とを接触させる。このとき天然ガスと吸着剤とが接触することにより、吸着対象物である水や水銀が吸着剤に吸着され、天然ガス中の水や水銀が除去される。この水銀除去工程２４は酸性ガス除去工程２２の前段に置くこともできる。これら酸性ガス除去工程２２、水分除去工程２３及び水銀除去工程２４を行う前処理設備を含む設備群を不純物除去設備群２０と呼ぶものとする。 The natural gas treated in the acid gas removing step 22 is further removed in a water removing step 23. Further, in the natural gas treated in the water removing step 23, mercury is removed in the mercury removing step 24.
The equipment for performing the water removal step 23 and the mercury removal step 24 includes, for example, an adsorption tower which is an adsorption apparatus filled with an adsorbent for adsorbing moisture and a mercury adsorbent for adsorbing mercury, respectively. These adsorption towers allow natural gas to pass through the adsorption tower, thereby allowing natural gas to pass through gaps between the adsorbents filled in the adsorption tower, thereby bringing the natural gas into contact with the adsorbent. At this time, when the natural gas and the adsorbent come into contact with each other, water and mercury, which are the objects to be adsorbed, are adsorbed by the adsorbent, and water and mercury in the natural gas are removed. This mercury removal step 24 can be placed before the acid gas removal step 22. The equipment group including the pretreatment equipment for performing the acid gas removal step 22, the water removal step 23, and the mercury removal step 24 is referred to as an impurity removal equipment group 20.
　次いで不純物が除去された天然ガスは炭化水素分離工程２５にて、メタンと炭素数２以上の重質炭化水素とに分離される。炭化水素分離工程には、例えば蒸留設備（デメタナイザー）が用いられる。デメタナイザーを含む炭化水素分離設備の詳細な説明については、後述する。
　炭化水素分離工程２５にて分離されたメタンは、液化工程２６にて液化されて液化天然ガス（ＬＮＧ）となる。ＬＮＧは、その後、ＬＮＧの一部を気化（エンドフラッシュ）させることにより、ＬＮＧの温度調整を行うエンドフラッシュガス工程２７、ＬＮＧを貯蔵する工程２８などの工程が行われ、例えばＬＮＧタンカーに出荷される。 Next, the natural gas from which the impurities have been removed is separated into methane and heavy hydrocarbons having 2 or more carbon atoms in a hydrocarbon separation step 25. In the hydrocarbon separation step, for example, a distillation facility (demethanizer) is used. The detailed description of the hydrocarbon separation equipment including the demethanizer will be described later.
The methane separated in the hydrocarbon separation step 25 is liquefied in the liquefaction step 26 to become liquefied natural gas (LNG). The LNG is then vaporized (end-flashed) by partially vaporizing (end-flashing) the LNG, thereby performing an end-flash gas step 27 for adjusting the temperature of the LNG, a step 28 for storing the LNG, and the like, and is shipped to an LNG tanker, for example. You.
　また気液分離工程２１にて天然ガスから気液分離された液体成分（コンデンセート）の一部は、軽質炭化水素を除去する蒸気圧調整工程３１が行われた後、コンデンセートとして貯蔵３２、出荷される。さらに気液分離されたコンデンセートからは、水分を含む不凍液が相分離され、当該不凍液に対して不凍液再生処理３０が実施される。不凍液にはモノエチレングリコール（ＭＥＧ）などが用いられ、再生された不凍液は天然ガスの井戸元に再供給される。またエンドフラッシュガスやＬＮＧ貯蔵工程２８にてＬＮＧから蒸発したボイルオフガス（ＢＯＧ）は、昇圧処理２９が行われ、主に燃焼ガスとして使用され、余剰が生じた場合には残りは液化工程２６の前段に戻すことで再度液化することもできる。 A part of the liquid component (condensate) gas-liquid separated from the natural gas in the gas-liquid separation step 21 is stored as a condensate 32 and shipped after a vapor pressure adjustment step 31 for removing light hydrocarbons is performed. You. Furthermore, the antifreeze containing water is phase-separated from the gas-liquid separated condensate, and the antifreeze regeneration process 30 is performed on the antifreeze. Monoethylene glycol (MEG) or the like is used as the antifreeze, and the regenerated antifreeze is supplied to the natural gas well. Further, the end flash gas and the boil-off gas (BOG) evaporated from the LNG in the LNG storage step 28 are subjected to a pressure increasing process 29 and are mainly used as combustion gas. It can be liquefied again by returning to the previous stage.
　また本実施の形態は、炭化水素分離工程２５にて分離されたメタンを、酸性ガス除去工程２２に天然ガスを供給する供給ライン１００に戻して気液分離工程２１側から供給される天然ガスに合流させるリサイクルガスライン１０を備えている。リサイクルガスライン１０については、炭化水素分離工程２５を行う設備の説明と併せて説明する。 Further, in the present embodiment, the methane separated in the hydrocarbon separation step 25 is returned to the supply line 100 that supplies the natural gas to the acid gas removal step 22, and is converted into the natural gas supplied from the gas-liquid separation step 21 side. A recycle gas line 10 for merging is provided. The recycle gas line 10 will be described together with the description of the equipment for performing the hydrocarbon separation step 25.
　続いて、上述の天然ガス処理装置に含まれ、炭化水素分離工程２５を実施する炭化水素分離設備について説明する。
　図２は、天然ガス処理装置を構成する炭化水素分離設備の構成例である。炭化水素分離設備は、水銀除去工程２４にて処理された天然ガスが供給される天然ガス供給ライン１０１と、天然ガス供給ライン１０１から供給された天然ガスを冷却するコールドボックス１１、１２と、コールドボックス１１、１２にて冷却され、一部が液化した天然ガスの気液分離を行うフィード・セパレータ１３と、天然ガスの蒸留を行い、メタンと炭素数２以上の重質炭化水素とに分離するデメタナイザー１７と、を備えている。 Next, a hydrocarbon separation facility that is included in the above-described natural gas processing apparatus and performs the hydrocarbon separation step 25 will be described.
FIG. 2 is a configuration example of a hydrocarbon separation facility constituting a natural gas processing apparatus. The hydrocarbon separation equipment includes a natural gas supply line 101 to which the natural gas processed in the mercury removal step 24 is supplied, cold boxes 11 and 12 for cooling the natural gas supplied from the natural gas supply line 101, A feed separator 13 that performs gas-liquid separation of natural gas that has been cooled and partially liquefied in boxes 11 and 12, and a natural gas is distilled to separate methane and heavy hydrocarbons having 2 or more carbon atoms. A demethanizer 17.
　天然ガス供給ライン１０１から供給された天然ガスは、コールドボックス１１、１２により冷却され、フィード・セパレータ１３により気液分離される。そして気体分の内の一部がエキスパンダー１４により減圧膨張され、－５０～－８０℃の気液混合体として、デメタナイザー１７に供給される。図２中の１５は、ＪＴ(Joule-Thomson)バルブ１５である。またフィード・セパレータ１３により気液分離された天然ガスのうちの残りの気体分は、コールドボックス１６にて冷却後、減圧バルブ１０４にて減圧膨張され、－７０～－１００℃の気液混合体としてデメタナイザー１７に供給される。フィード・セパレータ１３により気液分離された液体分は、コールドボックス１２の冷媒として用いられた後、デメタナイザー１７に供給される。 天然 Natural gas supplied from the natural gas supply line 101 is cooled by the cold boxes 11 and 12 and is separated into gas and liquid by the feed separator 13. Then, a part of the gas component is decompressed and expanded by the expander 14 and supplied to the demethanizer 17 as a gas-liquid mixture at −50 to −80 ° C. Reference numeral 15 in FIG. 2 denotes a JT (Joule-Thomson) valve 15. Further, the remaining gas component of the natural gas separated into gas and liquid by the feed separator 13 is cooled in the cold box 16 and then decompressed and expanded by the decompression valve 104 to obtain a gas-liquid mixture at -70 to -100 ° C. Is supplied to the demethanizer 17. The liquid component gas-liquid separated by the feed separator 13 is used as a refrigerant for the cold box 12 and then supplied to the demethanizer 17.
　そしてデメタナイザー１７は、供給された天然ガスの気液混合体を蒸留することでメタンを分離し、塔頂部に設けられた送気ライン１０５を介して払い出す。また塔底部からエタンより重質の重質炭化水素（Ｃ２＋）を流出させる。なお図２中の符号１７１は、リボイラーを示している。
　また本実施の形態に係る炭化水素分離設備は、デメタナイザー１７から払い出したメタンや、フィード・セパレータ１３によって分離された天然ガスのうちの液体分をコールドボックス１１、１２の冷媒として用いている。即ち本実施の形態に係るデメタナイザー１７は、自己冷媒タイプの蒸留設備として構成されている。 The demethanizer 17 separates methane by distilling the supplied gas-liquid mixture of natural gas, and discharges the methane through an air supply line 105 provided at the top of the tower. Also, heavy hydrocarbons (C2 +), which are heavier than ethane, are allowed to flow out of the bottom of the tower. Note that reference numeral 171 in FIG. 2 indicates a reboiler.
Further, the hydrocarbon separation equipment according to the present embodiment uses methane discharged from the demethanizer 17 and liquid components of natural gas separated by the feed separator 13 as refrigerant for the cold boxes 11 and 12. That is, the demethanizer 17 according to the present embodiment is configured as a distillation apparatus of a self-refrigerant type.
　そしてデメタナイザー１７から流出したメタンは、コールドボックス１１の冷媒として用いられ、コンプレッサー３１１、ブースターコンプレッサー３１２にて昇圧され、さらに空冷器３２０により冷却された後、液化工程２６を行う設備に送気される。
　送気ライン１０５における、コンプレッサー３１１の下流側には、リサイクルガスライン１０の一端が接続されている。リサイクルガスライン１０の他端側は、図１に示すように不純物除去設備群２０の入口側、この例では、酸性ガス除去工程２２の入口側の供給ライン１００に接続されている。なお図２に示すように、リサイクルガスライン１０には圧力調節弁Ｖ１０が設けられてもよい。 The methane flowing out of the demethanizer 17 is used as a refrigerant for the cold box 11, is pressurized by the compressor 311 and the booster compressor 312, is further cooled by the air cooler 320, and is sent to equipment for performing the liquefaction step 26. .
One end of the recycle gas line 10 is connected to a downstream side of the compressor 311 in the air supply line 105. The other end of the recycle gas line 10 is connected to a supply line 100 on the inlet side of the impurity removing equipment group 20, in this example, on the inlet side of the acid gas removing step 22, as shown in FIG. As shown in FIG. 2, the recycle gas line 10 may be provided with a pressure control valve V10.
　ここで天然ガス田の開発から枯渇までの間の産出量の変化と、産出量の変化に伴う天然ガス処理装置への影響について説明する。既述のように天然ガス田においては、ガス田からの天然ガスの産出を開始した後、徐々に産出量が増加し、しばらくの間、産出量が高い状態が維持される期間（plateau期間）となる。さらに年月がたつと、やがて天然ガスの産出量が徐々に低下する減退期に入る。 (4) Here, the change in output from the development of natural gas fields to depletion and the effect of the change in output on natural gas processing equipment will be described. As described above, in a natural gas field, after natural gas production from the gas field starts, the output gradually increases, and for a while the output is maintained at a high level (plateau period). Becomes As time goes on, the country will enter a period of decline where natural gas production will gradually decline.
　このように天然ガスの産出量は、井戸元の開発からの経過時間によって変化する。一方で、天然ガス処理装置における各設備のうち、例えば液化工程２６を行う液化設備や、それ以降の工程２７、２８においては、天然ガスの供給量が変化したとしても処理効率にはほとんど影響しない。言い替えると、例えば減退期において、処理量が低下したとしても、単位重量当たりのメタンガスの液化、ＬＮＧのエンドフラッシュや貯蔵を行うのに必要なエネルギーは大きく変化しない。 As described above, the amount of natural gas produced varies depending on the time elapsed since the development of the well. On the other hand, among the facilities in the natural gas processing apparatus, for example, in the liquefaction facility for performing the liquefaction step 26 and the subsequent steps 27 and 28, even if the supply amount of the natural gas changes, the processing efficiency is hardly affected. . In other words, for example, in the decline period, even if the throughput decreases, the energy required to liquefy methane gas per unit weight and end-flash or store LNG does not change significantly.
　一方で、不純物除去設備群２０側では、既述のように酸性ガス除去工程２２は、吸収塔を用い、水分除去工程２３及び水銀除去工程２４においては、吸着塔を用いている。　
　例えば酸性ガス除去工程２２の吸収塔においては、供給される天然ガスの量が設計流量よりも少なくなると天然ガス量に応じて吸収液量も低下することで蒸気負荷、液負荷ともに適正運転領域を下回り、吸収液と天然ガスとが十分に接触することができず、吸収塔は所定性能を発揮できなくなることで、結果として吸収塔の運転継続が困難となる場合がある。 On the other hand, on the impurity removal equipment group 20 side, as described above, the acid gas removal step 22 uses an absorption tower, and the moisture removal step 23 and the mercury removal step 24 use an adsorption tower.
For example, in the absorption tower of the acid gas removal step 22, when the amount of supplied natural gas is less than the design flow rate, the amount of absorbing liquid also decreases in accordance with the amount of natural gas, so that both the steam load and the liquid load make the appropriate operation range. As the absorption liquid and the natural gas cannot come into contact sufficiently, the absorption tower cannot exhibit predetermined performance, and as a result, it may be difficult to continue the operation of the absorption tower.
　また水分除去工程２３及び水銀除去工程２４の吸着塔に供給される天然ガスの量が運転に適する変動範囲よりも少なくなると、吸着塔に供給された天然ガスが、充填された吸着剤の内の比較的通過しやすい部位のみを通過するようになってしまう偏流（チャネリング）が起こる場合がある。このようなチャネリングが起こると、充填された吸着剤のうちの一部としか天然ガスが接触しなくなってしまい、ガス中に含まれる被吸着成分（水分や水銀）の吸着効率が悪くなる。また、チャネリングが発生するような低流量の運転を定常的に行うと短絡経路が固定化される場合がある。この結果、天然ガス流量が適正流量へと戻ったとしても、天然ガスは吸着材全体と均一な接触をせず、短絡経路を優先的に流れてしまうことで、吸着効率が悪くなるのみならず短絡経路近傍部分の吸着材しか吸着に寄与しないことから、吸着材の寿命は吸着材全体を前提とした設計寿命よりも極端に短くなることが起こりえる。 Further, when the amount of the natural gas supplied to the adsorption tower in the water removal step 23 and the mercury removal step 24 becomes smaller than a fluctuation range suitable for operation, the natural gas supplied to the adsorption tower becomes a part of the filled adsorbent. There may be a case where a drift (channeling) occurs in which only a portion that is relatively easy to pass is passed. When such channeling occurs, natural gas comes into contact with only a part of the filled adsorbent, and the adsorption efficiency of components to be adsorbed (moisture and mercury) contained in the gas deteriorates. In addition, when a low flow rate operation that causes channeling is performed constantly, the short circuit path may be fixed. As a result, even if the natural gas flow rate returns to the appropriate flow rate, the natural gas does not make uniform contact with the entire adsorbent and flows preferentially through the short-circuit path, so that not only does the adsorption efficiency deteriorate, but also Since only the adsorbent near the short-circuit path contributes to the adsorption, the life of the adsorbent may be extremely shorter than the design life on the premise of the entire adsorbent.
　さらに炭化水素分離工程２５のデメタナイザー１７は、蒸留塔であり、蒸留塔においても、供給されるガスの量が少なくなると、それに応じて蒸気負荷、液負荷が小さくなることから蒸留効率が低下する。また当デメタナイザーは、供給される天然ガスを、エキスパンダー１４で生成する冷熱をコールドボックス１１、１２、１６へ導入することで自己冷却を行って、重質炭化水素を分離するプロセスであることから、供給するガス量が減少するとエキスパンダー１４で得られる冷熱も減少することで、重質炭化水素の分離効率が低下する。
　以上に例示したように井戸元からの天然ガスの供給量が設計流量を下回ることに伴う影響は、主として不純物除去設備群２０や炭化水素分離工程２５の蒸留設備であるデメタナイザー１７にて顕在化する。 Further, the demethanizer 17 in the hydrocarbon separation step 25 is a distillation column. In the distillation column, when the amount of supplied gas is reduced, the vapor load and the liquid load are correspondingly reduced, so that the distillation efficiency is reduced. In addition, this demethanizer is a process of separating heavy hydrocarbons by performing self-cooling by introducing cold gas generated by the expander 14 into the cold boxes 11, 12, and 16 by supplying supplied natural gas to the cold boxes 11, 12, and 16. When the amount of supplied gas decreases, the cooling heat obtained by the expander 14 also decreases, and the efficiency of separating heavy hydrocarbons decreases.
As exemplified above, the influence of the natural gas supply from the well base being lower than the design flow rate is mainly manifested in the impurity removing equipment group 20 and the demethanizer 17 which is the distillation equipment in the hydrocarbon separation step 25. .
　この点、天然ガス処理装置内の各設備を設計するにあたっては、産出量が多く、産出開始期やの減退期よりも長い、plateau期間に効率的な処理ができるよう設計することが好ましい。そのため天然ガス処理装置の各処理設備においては、plateau期間における天然ガスの供給流量に基づいて各設備における天然ガスの設計流量を設定している場合が多い。
　しかしながら、中小型のガス田は比較的plateau期間が短く、数年～１０年程度の短い期間で減退期に移行してしまうこともある。このため、天然ガス処理装置が設計流量通りの性能を発揮する期間が短くなり、生産効率が悪くなる場合がある。 In this regard, when designing each facility in the natural gas processing apparatus, it is preferable to design such that efficient production can be performed during the plateau period, which has a large output and is longer than the production start period or the decline period. Therefore, in each processing facility of the natural gas processing apparatus, the design flow rate of natural gas in each facility is often set based on the supply flow rate of natural gas during the plateau period.
However, small and medium-sized gas fields have a relatively short plateau period, and may transition to a decline period in a short period of several years to 10 years. For this reason, the period during which the natural gas processing device exhibits the performance according to the design flow rate is shortened, and the production efficiency may be reduced.
　そこで本実施の形態に係る天然ガス処理装置においては、井戸元のガス田が減退期に入り天然ガスの供給量が減ったとき、リサイクルガスライン１０を介してメタンガスの一部を不純物除去設備群２０の入口側にリサイクルする。例えば供給ライン１００を介して酸性ガス除去工程２２に供給される天然ガスの供給流量が予め設定された流量を下回る状態となったら、リサイクルガスライン１０をオンラインの状態とする。そして、図２に示す調節弁Ｖ１０により、メタンガスのリサイクル量を調整して、酸性ガス除去工程２２に供給される天然ガスの供給流量が、例えばplateau期間と同程度となるようにする。 Therefore, in the natural gas processing apparatus according to the present embodiment, when the gas field at the base of the well enters the decline period and the supply of natural gas decreases, a part of the methane gas is removed through the recycle gas line 10 into the impurity removal equipment group. Recycle to the entrance side of 20. For example, when the supply flow rate of the natural gas supplied to the acid gas removal step 22 via the supply line 100 becomes lower than a preset flow rate, the recycle gas line 10 is brought online. Then, the amount of methane gas recycled is adjusted by the control valve V10 shown in FIG. 2 so that the supply flow rate of the natural gas supplied to the acid gas removal step 22 is substantially equal to, for example, the plateau period.
　上述の構成により、不純物除去設備群２０の入口側においては、井戸元側から供給される天然ガスと、デメタナイザー１７から払い出されるメタンガスの一部とが合流した後、不純物除去設備群２０に供給される。この結果、例えば酸性ガス除去工程２２内の吸収塔には、plateau期間と同様の流量で天然ガスが供給される。 With the above-described configuration, at the inlet side of the impurity removing equipment group 20, after natural gas supplied from the well base side and a part of the methane gas discharged from the demethanizer 17 merge, the natural gas supplied to the impurity removing equipment group 20 is supplied to the impurity removing equipment group 20. You. As a result, for example, natural gas is supplied to the absorption tower in the acid gas removal step 22 at a flow rate similar to that during the plateau period.
　上述のメタンガスのリサイクルにより、不純物除去設備群２０及び炭化水素分離設備に供給される天然ガスの供給流量、即ち、各設備内を流れる天然ガスの流量をplateau期間と同程度に維持することができる。　
　この結果、酸性ガス除去工程２２内の吸収塔では天然ガスの流量の不足による蒸気負荷を運転可能な流量に保つことができ、効率的に酸性ガスを吸収可能な状態を維持することができる。 By the above-mentioned methane gas recycling, the supply flow rate of the natural gas supplied to the impurity removing equipment group 20 and the hydrocarbon separation equipment, that is, the flow rate of the natural gas flowing in each equipment can be maintained at about the same as the plateau period. .
As a result, in the absorption tower in the acid gas removal step 22, the steam load due to the shortage of the natural gas flow rate can be maintained at an operable flow rate, and the state in which the acid gas can be efficiently absorbed can be maintained.
　また後段の水分除去工程２３、水銀除去工程２４内の各吸着塔においても天然ガスの流量の不足によるチャネチングの発生を抑え、効率的に水分や水銀を吸着可能な状態を維持することができる。 Also, in each of the adsorption towers in the subsequent water removal step 23 and the mercury removal step 24, the occurrence of channeling due to a shortage of the flow rate of natural gas can be suppressed, and the state in which moisture and mercury can be adsorbed efficiently can be maintained.
さらに炭化水素分離設備内のデメタナイザー（蒸留設備）１７においても液化した天然ガスの供給流量の不足による冷熱生成量の減少、蒸留塔内の蒸気負荷の低下を抑え、効率的にメタンガスの蒸留分離を行うことができる。 Furthermore, in the demethanizer (distillation equipment) 17 in the hydrocarbon separation equipment, a reduction in the amount of cold heat generated due to a shortage of the supply flow rate of the liquefied natural gas and a reduction in the steam load in the distillation column are suppressed, and the distillation and separation of methane gas is efficiently performed. It can be carried out.
　そして減退期における天然ガスの産出量の低下が進行し、天然ガスの供給量がさらに減っていったとしても、リサイクルされるメタンガスを増やすことで、不純物除去設備群２０及び炭化水素分離設備に供給される天然ガスの流量を維持することができる。　
　なお、メタンガスのリサイクル量は、不純物除去設備群２０の入口側の圧力をplateau期間と同程度に維持可能な量に調整する場合に限定されない。例えばリサイクルガスライン１０の送気化可能流量を考慮して、前記圧力がplateau期間の８割以上の値に維持されるように設定するなど、設備能力などに応じた適切な値を設定してもよい。 And even if the output of natural gas declines during the decline period and the supply of natural gas further decreases, by increasing the amount of methane gas recycled, it is supplied to the impurity removal equipment group 20 and the hydrocarbon separation equipment. The natural gas flow rate can be maintained.
The amount of methane gas recycled is not limited to the case where the pressure on the inlet side of the impurity removing equipment group 20 is adjusted to an amount that can be maintained at the same level as the plateau period. For example, in consideration of the flow rate that can be supplied to the recycle gas line 10, even if the pressure is set to be maintained at a value equal to or more than 80% of the plateau period, an appropriate value according to the facility capacity or the like may be set. Good.
　また、リサイクルガスライン１０をメタンガスの送気ライン１０５におけるコンプレッサー３１２の下流側に接続することで、高圧のメタンガスをリサイクルすることができる。この結果、不純物除去設備群２０の入口側の流量調整が容易となるとともに、昇圧に必要なコンプレッサー設備の低減を図ることができる。 Also, by connecting the recycle gas line 10 to the methane gas supply line 105 on the downstream side of the compressor 312, high-pressure methane gas can be recycled. As a result, it becomes easy to adjust the flow rate on the inlet side of the impurity removing equipment group 20, and it is possible to reduce the number of compressor equipment required for increasing the pressure.
　上述の実施の形態によれば、天然ガス液化装置において、天然ガスの液化前に不純物除去処理を行い、次いで炭化水素分離工程２５を行い、分離後のメタンの一部を不純物除去設備群２０の入口側にリサイクルさせるようにしている。そのため井戸元の天然ガスの産出量が少なくなり、天然ガスの供給量が少なくなったときにも不純物除去設備群２０に供給される天然ガスの量をplateau期間と同程度に維持することができる。そのため不純物除去設備群２０内に設けられた前処理設備（酸性ガスの吸収塔や水分、水銀の吸着塔）、炭化水素分離設備内に設けられたデメタナイザー１７において、天然ガスの供給量の減少に伴う処理効率の低下を抑制し、安定した処理を行うことができる。 According to the above-described embodiment, in the natural gas liquefaction apparatus, the impurity removal treatment is performed before the natural gas is liquefied, and then the hydrocarbon separation step 25 is performed. It is recycled at the entrance. Therefore, the output of the natural gas at the well base is reduced, and even when the supply of the natural gas is reduced, the amount of the natural gas supplied to the impurity removing equipment group 20 can be maintained at the same level as the plateau period. . Therefore, the pretreatment equipment (acid gas absorption tower or moisture and mercury adsorption tower) provided in the impurity removal equipment group 20 and the demethanizer 17 provided in the hydrocarbon separation equipment reduce the supply amount of natural gas. It is possible to suppress a decrease in the processing efficiency and perform a stable processing.
　次いで、コンデンセートの蒸気圧調整工程３１を行う設備にリサイクルラインを設ける実施の形態について説明する。
　図３に示すように蒸気圧調整工程３１を行う設備は、コンデンセート用の蒸留塔（スタビライザー）１３１を備え、既述の気液分離工程２１において分離されたコンデンセートがコンデンセート供給ライン１０６を介して供給される。 Next, an embodiment in which a recycling line is provided in equipment for performing the condensate vapor pressure adjusting step 31 will be described.
As shown in FIG. 3, the equipment for performing the vapor pressure adjustment step 31 includes a distillation column (stabilizer) 131 for condensate, and the condensate separated in the gas-liquid separation step 21 described above is supplied via the condensate supply line 106. Is done.
　またスタビライザー１３１の塔頂部には、コンデンセートの蒸留により分離された軽質ガスを抜き出すための抜き出しライン１０８が接続され、抜き出した軽質ガスは、例えばコンプレッサー４１で圧縮された後、酸性ガス除去工程２２への供給ライン１００と合流する。
　さらにスタビライザー１３１の塔底部には、塔底にたまる軽質ガスが分離されたコンデンセートを抜き出すためのコンデンセート抜き出しライン１０７が接続され、抜き出されたコンデンセートは、コンデンセート貯蔵工程３２に払い出される。なおコンデンセート抜き出しライン１０７に設けられた符号４３は、冷却器を示す。 Further, an extraction line 108 for extracting the light gas separated by distillation of the condensate is connected to the top of the stabilizer 131, and the extracted light gas is compressed by, for example, the compressor 41 and then to the acid gas removal step 22. Merges with the supply line 100.
Further, a condensate extraction line 107 for extracting condensate from which light gas accumulated at the bottom of the stabilizer 131 has been separated is connected to the bottom of the stabilizer 131, and the extracted condensate is discharged to the condensate storage step 32. Reference numeral 43 provided on the condensate extraction line 107 indicates a cooler.
　またコンデンセート抜き出しライン１０７からは、分岐ライン１０９が分岐している。分岐ライン１０９には、リボイラー４２が介設され、抜き出した重質分を含むコンデンセートを加熱してスタビライザー１３１に戻す。
　コンデンセート抜き出しライン１０７における冷却器４３の下流側には、コンデンセートリサイクルライン１１０の一端が接続され、その他端側は、コンデンセート供給ライン１０６に接続されている。なお図３中の符号４４は、ポンプを示す。 A branch line 109 branches off from the condensate extraction line 107. The reboiler 42 is interposed in the branch line 109, and heats the condensate containing the extracted heavy component and returns the condensate to the stabilizer 131.
One end of a condensate recycle line 110 is connected to the condensate extraction line 107 downstream of the cooler 43, and the other end is connected to a condensate supply line 106. Reference numeral 44 in FIG. 3 indicates a pump.
　蒸気圧調整工程３１においても井戸元からの天然ガスの産出量の減少に伴い、スタビライザー１３１へのコンデンセートの供給量が少なくなると液負荷が小さくなり処理効率が低下する。そこでコンデンセートリサイクルライン１１０を介して重質分を含むコンデンセートを入口側に戻すことにより、スタビライザー１３１へのコンデンセートの供給量をplateau期間と同程度に維持することができる。これにより減退期に入り井戸元の天然ガスの産出量が少なくなったときにも、スタビライザー１３１において、コンデンセートの量の低下による処理効率の低下を抑制することができる。 (4) Also in the vapor pressure adjusting step 31, when the amount of condensate supplied to the stabilizer 131 decreases with the decrease in the amount of natural gas produced from the well base, the liquid load decreases and the processing efficiency decreases. Then, by returning the condensate containing heavy components to the inlet side through the condensate recycle line 110, the supply amount of the condensate to the stabilizer 131 can be maintained at the same level as the plateau period. Accordingly, even when the production amount of natural gas at the base of the well decreases during the decline period, the stabilizer 131 can suppress the decrease in the processing efficiency due to the decrease in the amount of condensate.
　また井戸元からの天然ガスの供給量が十分に多いときには、コンデンセートリサイクルライン１１０を用いる必要はない。 When the supply of natural gas from the well is sufficiently large, it is not necessary to use the condensate recycle line 110.
　そこで、コンデンセート供給ライン１０６、及びコンデンセート抜き出しライン１０７に対しコンデンセートリサイクルライン１１０を着脱自在に設けてもよい。この構成によると、井戸元の天然ガスの産出量が低下する減退期に入るときにコンデンセートリサイクルライン１１０を装着することが可能となる。なお、スタビライザー１３１の起動を迅速に行うために、建設当初より設置することもできる。
　なお、図２に示した既述のメタンガス用のリサイクルガスライン１０は、大径で引き回し距離も長いため、着脱自在に構成することは困難である。従って、天然ガス液化装置の建設時に設置しておき、天然ガスの産出量が低下するタイミングに合わせて使用を開始する場合を例示できる。 Therefore, a condensate recycle line 110 may be detachably provided to the condensate supply line 106 and the condensate extraction line 107. According to this configuration, the condensate recycle line 110 can be installed when the well enters a decline period in which the production amount of natural gas decreases. In order to quickly start the stabilizer 131, the stabilizer 131 can be installed from the beginning of construction.
In addition, since the above-mentioned recycle gas line 10 for methane gas shown in FIG. 2 has a large diameter and a long drawing distance, it is difficult to make it detachable. Therefore, it is possible to exemplify a case where a natural gas liquefaction apparatus is installed at the time of construction, and the use of the natural gas liquefaction apparatus is started at the timing when the output of natural gas decreases.
　上述の各実施形態は、天然ガスの液化設備を備えた天然ガス液化装置に適用する場合に限定されるものではない。例えば、炭化水素分離工程２５にて得られたメタンガスを気体の状態のままパイプライン出荷する天然ガス処理装置においても、当該メタンガスの一部を不純物除去設備群２０の入口側にリサイクルするリサイクルガスライン１０を設けてもよい。
　また近年海底における中小ガス田の開発が進んでいるが、リサイクルガスライン１０を備えた天然ガス処理装置は、洋上に浮かぶ浮体上に設けられていてもよい。 Each of the above embodiments is not limited to the case where the present invention is applied to a natural gas liquefaction apparatus provided with a natural gas liquefaction facility. For example, even in a natural gas processing apparatus in which methane gas obtained in the hydrocarbon separation step 25 is shipped in a gaseous state through a pipeline, a recycled gas line for recycling part of the methane gas to the inlet side of the impurity removing equipment group 20 10 may be provided.
In recent years, the development of small and medium gas fields on the seabed has been progressing, but the natural gas processing device provided with the recycled gas line 10 may be provided on a floating body floating on the ocean.
１０　　　　供給ライン
１７　　　　デメタナイザー
２２　　　　酸性ガス除去工程
２３　　　　水分除去工程
２４　　　　水銀除去工程
２５　　　　炭化水素除去工程
２６　　　　液化工程
３１　　　　蒸気圧調整工程
１００　　　リサイクルガスライン
１０１　　　前処理設備
１０２　　　液化設備
１３１　　　コンデンセート用蒸留塔
３１１　　　コンプレッサー

  Reference Signs List 10 supply line 17 demethanizer 22 acid gas removal step 23 moisture removal step 24 mercury removal step 25 hydrocarbon removal step 26 liquefaction step 31 vapor pressure adjustment step 100 recycle gas line 101 pretreatment equipment 102 liquefaction equipment 131 condensate distillation tower 311 compressor

Claims (8)

  1. 　吸着剤を用いて天然ガスに含まれる不純物を吸着除去する吸着設備と、天然ガスと吸収液とを接触させて天然ガスに含まれる不純物を除去する吸収設備とから少なくとも一つ選択された前処理設備を備え、供給ラインを介して供給される天然ガスに含まれる不純物を除去する不純物除去設備群と、
    　前記不純物除去設備群にて処理された天然ガスを、メタンと炭素数２以上の重質炭化水素とに蒸留分離し、送気ラインを介して前記メタンを送気する蒸留設備と、
    　前記送気されるメタンの一部を分流し、前記供給ラインから不純物除去設備群に供給される天然ガスと合流させるリサイクルガスラインと、を備えることを特徴とする天然ガス処理装置。     At least one pretreatment selected from an adsorption facility for adsorbing and removing impurities contained in natural gas using an adsorbent, and an absorption facility for removing impurities contained in natural gas by bringing natural gas into contact with an absorbing solution. Equipped with equipment, an impurity removal equipment group for removing impurities contained in the natural gas supplied via the supply line,
    A natural gas treated in the impurity removal equipment group is separated by distillation into methane and heavy hydrocarbons having 2 or more carbon atoms, and a distillation equipment for sending the methane through an air supply line,
    A natural gas processing device, comprising: a recycle gas line that diverges a part of the supplied methane and joins the natural gas supplied from the supply line to the impurity removal equipment group.
  2. 　前記蒸留設備から送気されたメタンを液化するための液化設備を備えたことを特徴とする天然ガス処理装置。 (4) A natural gas processing apparatus comprising a liquefaction facility for liquefying methane sent from the distillation facility.
  3. 　前記蒸留設備は、前記天然ガスを減圧膨張させることにより温度低下させて得られた気液混合体に対して前記蒸留分離を行うことと、
    　前記送気ラインは、前記メタンを昇圧する圧縮機を備え、前記リサイクルガスラインは、前記圧縮機の出口側から前記メタンの一部を分流する位置に設けられていることと、を特徴とする請求項１に記載の天然ガス処理装置。     The distillation facility performs the distillation separation on the gas-liquid mixture obtained by lowering the temperature by expanding the natural gas under reduced pressure,
    The air supply line includes a compressor that pressurizes the methane, and the recycle gas line is provided at a position where a part of the methane is diverted from an outlet side of the compressor. The natural gas processing device according to claim 1.
  4. 　前記不純物除去設備群に供給される前の天然ガスに含まれる液体分であるコンデンセートを分離した後、前記供給ラインを介して、前記コンデンセート分離後の天然ガスを前記不純物除去設備群に供給する気液分離設備と、
    　コンデンセート供給ラインを介して前記コンデンセートが供給され、前記コンデンセートに含まれる軽質炭化水素を蒸留分離してコンデンセートの蒸気圧を調整する蒸気圧調整設備と、
    　前記蒸気圧調整設備にて軽質炭化水素が分離された後のコンデンセートの一部を分流し、前記コンデンセート供給ラインから蒸気圧調整節設備に供給されるコンデンセートと合流させるコンデンセートリサイクルラインと、を備えることを特徴とする請求項１に記載の天然ガス処理装置。     After separating the condensate which is a liquid component contained in the natural gas before being supplied to the impurity removal equipment group, the natural gas after the condensate separation is supplied to the impurity removal equipment group via the supply line. Liquid separation equipment,
    The condensate is supplied via a condensate supply line, a vapor pressure adjusting device for adjusting the vapor pressure of the condensate by distilling and separating light hydrocarbons contained in the condensate,
    A condensate cycle line that separates a part of the condensate after the light hydrocarbons are separated by the vapor pressure adjusting equipment, and merges with the condensate supplied to the steam pressure adjusting node equipment from the condensate supply line. The natural gas processing apparatus according to claim 1, wherein:
  5. 　前記コンデンセートリサイクルラインは、前記蒸気圧調整節設備からコンデンセートを抜き出すコンデンセート抜出ラインと前記コンデンセート供給ラインとの間に着脱自在に設けられることを特徴とする請求項４に記載の天然ガス処理装置。 The natural gas processing apparatus according to claim 4, wherein the condensate recycle line is detachably provided between a condensate extraction line for extracting condensate from the steam pressure adjusting node equipment and the condensate supply line.
  6. 　前記不純物除去設備群及び前記蒸留設備は、洋上に浮かぶ浮体上に設けられたことを特徴とする請求項１に記載の天然ガスの前処理装置。 The natural gas pretreatment apparatus according to claim 1, wherein the impurity removal equipment group and the distillation equipment are provided on a floating body floating on the sea.
  7. 　前記浮体上には、前記蒸留設備から送気されたメタンを液化するための液化設備が設けられていることを特徴とする請求項６に記載の天然ガス処理装置。 7. The natural gas processing apparatus according to claim 6, wherein a liquefaction facility for liquefying the methane sent from the distillation facility is provided on the floating body.
  8. 　吸着剤を用いて天然ガスに含まれる不純物を吸着除去する吸着設備と、天然ガスと吸収液とを接触させて天然ガスに含まれる不純物を除去する吸収設備とから少なくとも一つ選択された前処理設備を備えた不純物除去設備群用い、供給ラインを介して供給される天然ガスに含まれる不純物を除去する工程と、
    　前記不純物除去設備群にて処理された天然ガスを、メタンと炭素数２以上の重質炭化水素とに蒸留分離し、送気ラインを介して前記メタンを送気する工程と、
    　前記送気ラインを介して送気されるメタンの一部を分流して、前記供給ラインから前記不純物除去設備群に供給される天然ガスと合流させる工程と、を含むことを特徴とする天然ガス処理方法。     At least one pretreatment selected from an adsorption facility for adsorbing and removing impurities contained in natural gas using an adsorbent, and an absorption facility for removing impurities contained in natural gas by bringing natural gas into contact with an absorbing solution. A step of removing impurities contained in natural gas supplied through a supply line, using a group of impurity removal equipment provided with equipment,
    The natural gas treated in the impurity removal equipment group is separated by distillation into methane and heavy hydrocarbons having 2 or more carbon atoms, and a step of sending the methane through an air supply line,
    Diverting a part of the methane supplied through the air supply line, and merging with the natural gas supplied from the supply line to the impurity removal equipment group, the natural gas characterized in that Processing method.
PCT/JP2018/027710 2018-07-24 2018-07-24 Natural gas treatment device and natural gas treatment method WO2020021633A1 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
KR1020207016933A KR102642311B1 (en) 2018-07-24 2018-07-24 Natural gas processing device and natural gas processing method
CN201880077980.1A CN111433329A (en) 2018-07-24 2018-07-24 Natural gas processing device and natural gas processing method
PCT/JP2018/027710 WO2020021633A1 (en) 2018-07-24 2018-07-24 Natural gas treatment device and natural gas treatment method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/JP2018/027710 WO2020021633A1 (en) 2018-07-24 2018-07-24 Natural gas treatment device and natural gas treatment method

Publications (1)

Publication Number Publication Date
WO2020021633A1 true WO2020021633A1 (en) 2020-01-30

Family

ID=69182321

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2018/027710 WO2020021633A1 (en) 2018-07-24 2018-07-24 Natural gas treatment device and natural gas treatment method

Country Status (3)

Country Link
KR (1) KR102642311B1 (en)
CN (1) CN111433329A (en)
WO (1) WO2020021633A1 (en)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2939814B2 (en) * 1990-03-05 1999-08-25 日本酸素株式会社 Methane separation device and method
JP4230956B2 (en) * 2003-04-16 2009-02-25 エア プロダクツ アンド ケミカルズ インコーポレイテッド Method and apparatus for recovery of components heavier than methane from natural gas
JP5041650B2 (en) * 2001-06-08 2012-10-03 オートロフ・エンジニアーズ・リミテッド Natural gas liquefaction
WO2015155818A1 (en) * 2014-04-07 2015-10-15 三菱重工コンプレッサ株式会社 Floating liquefied-gas production facility

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20110067439A1 (en) 2007-07-09 2011-03-24 Lng Technology Pty Ltd. Method and system for production of liquid natural gas
EP2892631B1 (en) * 2012-09-07 2018-11-14 Chevron U.S.A., Inc. Method for removing mercury from natural gas
US9816754B2 (en) * 2014-04-24 2017-11-14 Air Products And Chemicals, Inc. Integrated nitrogen removal in the production of liquefied natural gas using dedicated reinjection circuit
EP2977430A1 (en) * 2014-07-24 2016-01-27 Shell Internationale Research Maatschappij B.V. A hydrocarbon condensate stabilizer and a method for producing a stabilized hydrocarbon condenstate stream

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2939814B2 (en) * 1990-03-05 1999-08-25 日本酸素株式会社 Methane separation device and method
JP5041650B2 (en) * 2001-06-08 2012-10-03 オートロフ・エンジニアーズ・リミテッド Natural gas liquefaction
JP4230956B2 (en) * 2003-04-16 2009-02-25 エア プロダクツ アンド ケミカルズ インコーポレイテッド Method and apparatus for recovery of components heavier than methane from natural gas
WO2015155818A1 (en) * 2014-04-07 2015-10-15 三菱重工コンプレッサ株式会社 Floating liquefied-gas production facility

Also Published As

Publication number Publication date
KR20210031632A (en) 2021-03-22
CN111433329A (en) 2020-07-17
KR102642311B1 (en) 2024-03-05

Similar Documents

Publication Publication Date Title
EP1569740B1 (en) Methods of acid gas removal
RU2194930C2 (en) Method for liquefaction of natural gas containing at least one freezable component
EP2452140B1 (en) Method for producing methane-rich stream and c2+ hydrocarbon-rich stream, and related facility
CA2482159C (en) Configurations and methods for improved acid gas removal
TWI577954B (en) Gas processing facility and process for natural gas liquefaction
US7192468B2 (en) Configurations and method for improved gas removal
AU2009272889B2 (en) Two stage process for producing purified gas
RU2730344C1 (en) Extraction of helium from natural gas
US20120073441A1 (en) Configurations And Methods For High Pressure Acid Gas Removal
WO2013095828A1 (en) Method of separating carbon dioxide from liquid acid gas streams
JP5636036B2 (en) Method and associated apparatus for treating feed natural gas to obtain treated natural gas and C5 + hydrocarbon fractions
US20240019205A1 (en) Facility for producing gaseous methane by purifying biogas from landfill, combining membranes and cryogenic distillation for landfill biogas upgrading
JP2019529853A (en) Pretreatment of natural gas prior to liquefaction
FR2969745A1 (en) PROCESS FOR PRODUCING METHANE - RICH CURRENT AND CURRENT HYDROCARBON - RICH CURRENT AND ASSOCIATED PLANT.
WO2016150827A1 (en) Process for producing a purified gas stream from natural gas wells
CN111004657B (en) Method for comprehensively utilizing oilfield associated gas
WO2020021633A1 (en) Natural gas treatment device and natural gas treatment method
US20170350648A1 (en) Process for liquefying carbon dioxide resulting from a natural gas stream
CN111447986A (en) Pretreatment equipment for natural gas
KR102376275B1 (en) The System and Method for Carbon Dioxide Separation from Natural Gas before Gas Liquefaction Process
WO2015159546A1 (en) System and method for liquefying natural gas
WO2019193740A1 (en) Natural gas treatment method, and natural gas treatment device
AU2007201677A1 (en) Configurations and methods for improved acid gas removal
AU2016363566A1 (en) Method of liquefying a contaminated hydrocarbon-containing gas stream

Legal Events

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

Ref document number: 18927328

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 18927328

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: JP