JP3908881B2 - Boil-off gas reliquefaction method - Google Patents

Boil-off gas reliquefaction method Download PDF

Info

Publication number
JP3908881B2
JP3908881B2 JP31717499A JP31717499A JP3908881B2 JP 3908881 B2 JP3908881 B2 JP 3908881B2 JP 31717499 A JP31717499 A JP 31717499A JP 31717499 A JP31717499 A JP 31717499A JP 3908881 B2 JP3908881 B2 JP 3908881B2
Authority
JP
Japan
Prior art keywords
gas
boil
bog
storage tank
liquid
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
JP31717499A
Other languages
Japanese (ja)
Other versions
JP2001132899A (en
Inventor
俊和 入江
宣夫 幡中
孝司 三橋
栄治 富永
和彦 大竹
勝 岡
守孝 中村
元裕 大森
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Chiyoda Corp
Mitsubishi Heavy Industries Ltd
Nippon Yusen KK
Osaka Gas Co Ltd
Original Assignee
Chiyoda Corp
Mitsubishi Heavy Industries Ltd
Nippon Yusen KK
Osaka Gas Co Ltd
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 Chiyoda Corp, Mitsubishi Heavy Industries Ltd, Nippon Yusen KK, Osaka Gas Co Ltd filed Critical Chiyoda Corp
Priority to JP31717499A priority Critical patent/JP3908881B2/en
Publication of JP2001132899A publication Critical patent/JP2001132899A/en
Application granted granted Critical
Publication of JP3908881B2 publication Critical patent/JP3908881B2/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
    • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
    • F25J1/0285—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings
    • F25J1/0288—Combination of different types of drivers mechanically coupled to the same refrigerant compressor, possibly split on multiple compressor casings using work extraction by mechanical coupling of compression and expansion of the refrigerant, so-called companders
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
    • F25J1/0022—Hydrocarbons, e.g. natural gas
    • F25J1/0025—Boil-off gases "BOG" from storages
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
    • F25J1/0047—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
    • F25J1/005—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 expansion of a gaseous refrigerant stream with extraction of work
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
    • F25J1/007—Primary atmospheric gases, mixtures thereof
    • F25J1/0072—Nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
    • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
    • F25J1/0203—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle
    • F25J1/0204—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a single-component refrigerant [SCR] fluid in a closed vapor compression cycle as a single flow SCR 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
    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/08—Cold compressor, i.e. suction of the gas at cryogenic temperature and generally without afterstage-cooler
    • 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
    • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
    • F25J2230/30—Compression 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/34—Details about subcooling of liquids
    • 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
    • F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
    • F25J2290/62—Details of storing a fluid in a tank

Landscapes

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

Description

【０００１】
【発明の属する技術分野】
本発明は、液化ガスの貯槽から発生するボイルオフガスを再液化するための方法に関するものである。
【０００２】
【従来の技術】
ＬＮＧの貯槽から発生するボイルオフガス（以下、ＢＯＧと呼称する）の再液化を行うにあたり、従来、ＢＯＧを熱交換器にて飽和状態まで冷却した後、一旦気液分離ドラムに導き、ここでガス体を分離した上で貯槽に戻すようにした方法が知られている。この方法では、気液分離ドラムで得られたガス体を廃ガスとしてボイラーで燃焼することになるが、ＢＯＧを全量液化する方法に比較して、液化動力を削減すると共に、不純物としての窒素を主体とする非凝縮性分がガス体として除去されるため、炭化水素が濃縮された状態で貯槽に戻すことができる。
【０００３】
【発明が解決しようとする課題】
ところが、前記のごとく気液分離ドラムでガス体を分離しても、液を貯槽に戻した際の減圧によるフラッシュガスの発生は避けられない。このフラッシュガスは、ＢＯＧ量、すなわち再液化装置で処理すべきガス量を増加させると共に、非凝縮性分がガス相に濃縮されるので、再液化装置の容量を大きくする要因となる。
【０００４】
本発明は、このような従来技術の問題点を解消するべく案出されたものであり、その主な目的は、液化ガスの貯槽から発生するＢＯＧを再液化して貯槽に戻す際に発生するフラッシュガス量を低減し得るように構成されたＢＯＧの再液化方法を提供することにある。
【０００５】
【課題を解決するための手段】
このような目的を果たすために、本発明においては、不純物としての窒素を主体とする非凝縮性分を含む液化ガスとしてのＬＮＧの貯槽から発生するＢＯＧを再液化するにあたり、ＢＯＧの冷却により得られた飽和状態にある液を、一旦気液分離により非凝縮性分を分離した後に再度冷却し、過冷却状態にした上で前記貯槽に戻すことにより、気液分離後の液中に残存する非凝縮性分が前記貯槽に戻した際の減圧によってガス相に移行濃縮されることを抑制するようにしたものとした。なお、ここでいう過冷却とは、飽和温度より低い温度とすること、いわゆるサブクールをさす。
【０００６】
これによると、気液分離により、不純物としての窒素を主体とする非凝縮性分をガス体として分離除去すると同時に、気液分離した後の液を過冷却することにより、液中に残存する非凝縮性分が貯槽に戻した際の減圧によってガス相に移行濃縮されることを抑制し、これにより貯槽で発生するフラッシュガス量を大幅に低減することができる。
【０００７】
【発明の実施の形態】
以下に添付の図面を参照して本発明の構成を詳細に説明する。
【０００８】
図１は、本発明が適用されたＢＯＧの再液化を行う冷却システムの概略構成を示している。ここでは、液化ガスとしてのＬＮＧの貯蔵・運搬においてＬＮＧタンク１から発生するＢＯＧが、ＢＯＧコンプレッサ２により圧縮された後、熱交換器３により冷却されて再液化するようになっている。
【０００９】
熱交換器３の液化部５では、ＢＯＧが飽和状態まで冷却され、その下流側に設けられた気液分離ドラム６で、飽和状態にある液から非凝縮性分が分離される。これにより得られた窒素リッチガスは適宜に抜き出されて、ボイラーで処理される。他方、気液分離ドラム６内の飽和状態の液は、熱交換器３のサブクール部７に導かれ、再び窒素冷媒にて冷却されて過冷却状態となり、ＬＮＧタンク１に戻される。
【００１０】
このＢＯＧの液化過程においては、例えば、ＢＯＧコンプレッサ２によりＢＯＧを４５０ｋＰａＡまで圧縮した上で、熱交換器３の液化部５でＢＯＧを約−１５０℃まで冷却することにより炭化水素成分がほぼ完全に液化し、この液をサブクール部７で−１６７．５℃まで冷却することにより過冷却状態とすることができる。
【００１１】
熱交換器３においてＢＯＧを液化するための冷熱は、窒素を冷媒としたクローズドエキスパンダサイクルによる窒素冷凍サイクル９により供給される。この窒素冷凍サイクル９では、熱交換器３を出た冷媒窒素が、窒素コンプレッサ１０・１１、並びにインタクーラ１２及びアフタクーラ１３により冷却されながら圧縮される。
【００１２】
アフタクーラ１３を出た冷媒窒素は、さらにブースタコンプレッサ１４で圧縮され、ついでアフタクーラ１５で冷却された後、熱交換器３へ送られる。熱交換器３では、窒素冷却部１６において冷媒窒素が低温窒素との熱交換により冷却される。熱交換器３を出た冷媒窒素は、エキスパンダ１７に送られ、ここで減圧により膨張してＢＯＧ再液化に要する冷熱を生成し、熱交換器３に送られる。エキスパンダ１７での冷媒窒素を減圧する際の仕事でブースタコンプレッサ１４が駆動される。
【００１３】
【実施例】
以下に、本発明による方法をＬＮＧのボイルオフガスの再液化に適用した際の過冷却による冷凍設備負荷の削減状況に関する算出結果を示す。ここでは、ボイルオフガスの組成、すなわち窒素及びメタンの比率の異なる２例を表１並びに表２に示している。なお、表中の過冷却温度は、飽和温度からの温度降下量を示し、過冷却温度０℃は飽和状態のままで貯槽に戻す従来方法による場合を表す。フラッシュＢＯＧ率は、貯槽に戻したＢＯＧの全量に対するフラッシュ量の割合を示し、液化負荷は、所要の過冷却温度まで降温させるのに要する冷熱量及び処理ガス量から求められる冷凍設備にかかる負荷を示す。またＢＯＧコンプレッサ容量並びに液化負荷は、過冷却温度０℃（飽和状態）の場合に対する割合で示している。
【００１４】
【表１】

Figure 0003908881
【００１５】
【表２】
Figure 0003908881
【００１６】
これらの例により明らかなように、過冷却温度、すなわち飽和温度からの温度降下が大きくなるのに従ってフラッシュＢＯＧ率が低減し、さらに液化負荷も低減しており、本発明の有効性が確認された。
【００１７】
【発明の効果】
このように本発明によれば、ＢＯＧの冷却により得られる液を過冷却状態にした上で貯槽に戻すため、貯槽での減圧により発生するフラッシュガス量を低減することができ、これにより再液化装置の容量を削減することが可能となるので、効率的な装置設計を行う上で極めて顕著な効果が得られる。
【図面の簡単な説明】
【図１】本発明が適用されたボイルオフガスの再液化システムの概略構成を示すブロック図である。
【符号の説明】
１ ＬＮＧタンク
２ ＢＯＧコンプレッサ
３ 熱交換器
５ 液化部
６ 気液分離ドラム
７ サブクール部
９ 窒素冷凍サイクル
１０・１１ 窒素コンプレッサ
１２・１３ クーラ
１４ ブースタコンプレッサ
１５ アフタクーラ
１６ 窒素冷却部
１７ エキスパンダ[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for reliquefying a boil-off gas generated from a liquefied gas storage tank.
[0002]
[Prior art]
In re-liquefaction of boil-off gas (hereinafter referred to as BOG) generated from an LNG storage tank, conventionally, after cooling the BOG to a saturated state with a heat exchanger, the gas is once guided to a gas-liquid separation drum. A method of separating the body and returning it to the storage tank is known. In this method, the gas body obtained in the gas-liquid separation drum is burned in a boiler as waste gas. However, compared with the method of liquefying the entire amount of BOG, liquefaction power is reduced and nitrogen as an impurity is reduced. Since the main non-condensable component is removed as a gas body, the hydrocarbon can be returned to the storage tank in a concentrated state.
[0003]
[Problems to be solved by the invention]
However, even if the gas body is separated by the gas-liquid separation drum as described above, generation of flash gas due to decompression when the liquid is returned to the storage tank is unavoidable. This flash gas increases the amount of BOG, that is, the amount of gas to be processed by the reliquefaction device, and the non-condensable component is concentrated in the gas phase, thereby increasing the capacity of the reliquefaction device.
[0004]
The present invention has been devised to solve such problems of the prior art, and its main purpose is to re-liquefy BOG generated from a liquefied gas storage tank and return it to the storage tank. An object of the present invention is to provide a BOG reliquefaction method configured to reduce the amount of flash gas.
[0005]
[Means for Solving the Problems]
In order to achieve such an object, in the present invention, BOG generated from a storage tank of LNG as a liquefied gas containing a non-condensable component mainly composed of nitrogen as an impurity is obtained by cooling BOG. The liquid in the saturated state once separated by non-condensable components by gas-liquid separation is cooled again, and after being brought to a supercooled state, it is returned to the storage tank to remain in the liquid after gas-liquid separation. The non-condensable component was prevented from being transferred and concentrated to the gas phase due to the reduced pressure when returning to the storage tank . In addition, the supercooling referred to here refers to a so-called subcool, that is, a temperature lower than the saturation temperature.
[0006]
According to this, by gas-liquid separation, non-condensable components mainly composed of nitrogen as an impurity are separated and removed as a gas body, and at the same time, the liquid after gas-liquid separation is supercooled, thereby remaining in the liquid. It is possible to suppress the condensable component from being transferred to and concentrated in the gas phase due to the reduced pressure when returning to the storage tank, thereby greatly reducing the amount of flash gas generated in the storage tank .
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
[0008]
FIG. 1 shows a schematic configuration of a cooling system for reliquefying BOG to which the present invention is applied. Here, BOG generated from the LNG tank 1 in storing and transporting LNG as liquefied gas is compressed by the BOG compressor 2 and then cooled by the heat exchanger 3 to be liquefied again.
[0009]
In the liquefaction section 5 of the heat exchanger 3, the BOG is cooled to the saturated state, and the non-condensable component is separated from the saturated liquid by the gas-liquid separation drum 6 provided downstream thereof. The nitrogen-rich gas thus obtained is appropriately extracted and treated with a boiler. On the other hand, the saturated liquid in the gas-liquid separation drum 6 is guided to the subcooling section 7 of the heat exchanger 3, is again cooled with nitrogen refrigerant, becomes supercooled, and is returned to the LNG tank 1.
[0010]
In this BOG liquefaction process, for example, the BOG is compressed to 450 kPaA by the BOG compressor 2, and then the BOG is cooled to about −150 ° C. by the liquefaction unit 5 of the heat exchanger 3. By liquefying and cooling this liquid to −167.5 ° C. in the subcool section 7, it can be brought into a supercooled state.
[0011]
Cold heat for liquefying BOG in the heat exchanger 3 is supplied by a nitrogen refrigeration cycle 9 by a closed expander cycle using nitrogen as a refrigerant. In the nitrogen refrigeration cycle 9, the refrigerant nitrogen exiting the heat exchanger 3 is compressed while being cooled by the nitrogen compressors 10, 11, the intercooler 12 and the aftercooler 13.
[0012]
The refrigerant nitrogen that has exited the aftercooler 13 is further compressed by the booster compressor 14, then cooled by the aftercooler 15, and then sent to the heat exchanger 3. In the heat exchanger 3, the refrigerant nitrogen is cooled by heat exchange with the low-temperature nitrogen in the nitrogen cooling unit 16. The refrigerant nitrogen exiting the heat exchanger 3 is sent to the expander 17, where it expands due to decompression to generate cold heat required for BOG reliquefaction, and is sent to the heat exchanger 3. The booster compressor 14 is driven by the work when decompressing the refrigerant nitrogen in the expander 17.
[0013]
【Example】
Below, the calculation result regarding the reduction condition of the refrigerating equipment load by supercooling at the time of applying the method by this invention to reliquefaction of the boil-off gas of LNG is shown. Here, Table 1 and Table 2 show two examples in which the composition of the boil-off gas, that is, the ratio of nitrogen and methane is different. In addition, the supercooling temperature in a table | surface shows the amount of temperature fall from saturation temperature, and the supercooling temperature 0 degreeC represents the case by the conventional method which returns to a storage tank in a saturated state. The flash BOG rate indicates the ratio of the flash amount to the total amount of BOG returned to the storage tank, and the liquefaction load indicates the load on the refrigeration equipment determined from the amount of cooling and processing gas required to lower the temperature to the required supercooling temperature. Show. Further, the BOG compressor capacity and the liquefaction load are shown as ratios relative to the case of the supercooling temperature 0 ° C. (saturated state).
[0014]
[Table 1]
Figure 0003908881
[0015]
[Table 2]
Figure 0003908881
[0016]
As is clear from these examples, the flash BOG rate decreased as the temperature drop from the supercooling temperature, that is, the saturation temperature, and the liquefaction load decreased, confirming the effectiveness of the present invention. .
[0017]
【The invention's effect】
As described above, according to the present invention, the liquid obtained by cooling the BOG is brought into a supercooled state and then returned to the storage tank, so that the amount of flash gas generated by the pressure reduction in the storage tank can be reduced, thereby re-liquefaction. Since the capacity of the apparatus can be reduced, a very remarkable effect can be obtained in the efficient apparatus design.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of a boil-off gas reliquefaction system to which the present invention is applied.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 LNG tank 2 BOG compressor 3 Heat exchanger 5 Liquefaction part 6 Gas-liquid separation drum 7 Subcool part 9 Nitrogen refrigeration cycle 10 * 11 Nitrogen compressor 12 * 13 Cooler 14 Booster compressor 15 After cooler 16 Nitrogen cooling part 17 Expander

Claims (1)

不純物としての窒素を主体とする非凝縮性分を含む液化ガスとしてのＬＮＧの貯槽から発生するボイルオフガスを再液化するためのボイルオフガスの再液化方法であって、
ボイルオフガスを冷却して得られた飽和状態にある液を、一旦気液分離により非凝縮性分を分離した後に再度冷却し、過冷却状態にした上で前記貯槽に戻すことにより、気液分離後の液中に残存する非凝縮性分が前記貯槽に戻した際の減圧によってガス相に移行濃縮されることを抑制するようにしたことを特徴とする再液化方法。A re-liquefaction method of boil-off gas for re-liquefying boil-off gas generated from a storage tank of LNG as a liquefied gas containing a non-condensable component mainly composed of nitrogen as an impurity ,
The liquid in the boil-off gas saturation obtained by cooling once again cooled after separation of the non-condensable nature by gas-liquid separation, by returning to the reservoir on which the supercooled state, the gas-liquid separator A reliquefaction method characterized in that a non-condensable component remaining in a later liquid is prevented from being transferred and concentrated to a gas phase due to reduced pressure when returning to the storage tank .
JP31717499A 1999-11-08 1999-11-08 Boil-off gas reliquefaction method Expired - Lifetime JP3908881B2 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP31717499A JP3908881B2 (en) 1999-11-08 1999-11-08 Boil-off gas reliquefaction method

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP31717499A JP3908881B2 (en) 1999-11-08 1999-11-08 Boil-off gas reliquefaction method

Publications (2)

Publication Number Publication Date
JP2001132899A JP2001132899A (en) 2001-05-18
JP3908881B2 true JP3908881B2 (en) 2007-04-25

Family

ID=18085287

Family Applications (1)

Application Number Title Priority Date Filing Date
JP31717499A Expired - Lifetime JP3908881B2 (en) 1999-11-08 1999-11-08 Boil-off gas reliquefaction method

Country Status (1)

Country Link
JP (1) JP3908881B2 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106287219A (en) * 2016-09-26 2017-01-04 湖北和远气体股份有限公司 A kind of natural gas liquefaction plant BOG recycling system
EP3514466A2 (en) 2018-01-17 2019-07-24 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Boil off gas reliquefying apparatus and lng supply system provided with the same
KR20210118140A (en) 2019-02-27 2021-09-29 미쓰비시주코마린마시나리 가부시키가이샤 Boil-off gas treatment systems and vessels

Families Citing this family (25)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4588990B2 (en) * 2003-10-20 2010-12-01 川崎重工業株式会社 Apparatus and method for boil-off gas reliquefaction of liquefied natural gas
JP4408211B2 (en) * 2003-11-04 2010-02-03 株式会社神戸製鋼所 Pressure adjusting device for liquefied natural gas tank and pressure adjusting method thereof
GB0400986D0 (en) * 2004-01-16 2004-02-18 Cryostar France Sa Compressor
JP4544885B2 (en) * 2004-03-22 2010-09-15 三菱重工業株式会社 Gas reliquefaction apparatus and gas reliquefaction method
EP1860393B1 (en) * 2006-05-23 2009-02-18 Cryostar SAS Method and apparatus for the reliquefaction of a vapour
KR100777560B1 (en) 2007-02-13 2007-11-20 대우조선해양 주식회사 Apparatus and method for reliquefying boil-off gas capable of pre-performance test
ES2744821T3 (en) * 2007-07-09 2020-02-26 Lng Tech Llc Liquid natural gas production system and procedure
JP5132452B2 (en) * 2008-07-07 2013-01-30 東京瓦斯株式会社 BOG reliquefaction equipment
NO332551B1 (en) * 2009-06-30 2012-10-22 Hamworthy Gas Systems As Method and apparatus for storing and transporting liquefied petroleum gas
KR20110018181A (en) * 2009-08-17 2011-02-23 삼성중공업 주식회사 Fuel gas supply system
CN104321581B (en) 2011-12-02 2016-10-19 氟石科技公司 LNG boil-off gas condenses arrangements and methods again
KR101616406B1 (en) * 2014-02-27 2016-04-28 삼성중공업 주식회사 Natural gas liquefaction apparatus
JP6345965B2 (en) * 2014-03-28 2018-06-20 千代田化工建設株式会社 Vaporized gas reliquefaction facility and vaporized gas reliquefaction method
JP6516430B2 (en) * 2014-09-19 2019-05-22 大阪瓦斯株式会社 Boil-off gas reliquefaction plant
KR101681727B1 (en) * 2015-07-03 2016-12-01 대우조선해양 주식회사 Boil Off Gas Treatment System
KR101681726B1 (en) * 2015-07-03 2016-12-01 대우조선해양 주식회사 Boil Off Gas Treatment System
KR101686514B1 (en) * 2015-07-03 2016-12-14 대우조선해양 주식회사 Boil Off Gas Treatment System
KR101681728B1 (en) * 2015-07-03 2016-12-01 대우조선해양 주식회사 Boil Off Gas Treatment System
FR3038964B1 (en) 2015-07-13 2017-08-18 Technip France METHOD FOR RELAXING AND STORING A LIQUEFIED NATURAL GAS CURRENT FROM A NATURAL GAS LIQUEFACTION SYSTEM, AND ASSOCIATED INSTALLATION
KR101876974B1 (en) 2016-09-29 2018-07-10 대우조선해양 주식회사 BOG Re-liquefaction Apparatus and Method for Vessel
JP6341523B2 (en) * 2017-06-07 2018-06-13 株式会社三井Ｅ＆Ｓホールディングス Boil-off gas recovery system
JP6429159B2 (en) * 2017-11-21 2018-11-28 三井Ｅ＆Ｓ造船株式会社 Boil-off gas recovery system
KR102584159B1 (en) * 2019-07-11 2023-10-05 삼성중공업 주식회사 Fuel gas treating system in ships
CN110749159B (en) * 2019-10-22 2021-05-11 中海石油气电集团有限责任公司 Device and method for refrigerating and liquefying natural gas
KR102542651B1 (en) * 2021-05-11 2023-06-14 에이치디현대중공업 주식회사 Boil-off gas re-liquefaction system and ship having the same

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106287219A (en) * 2016-09-26 2017-01-04 湖北和远气体股份有限公司 A kind of natural gas liquefaction plant BOG recycling system
EP3514466A2 (en) 2018-01-17 2019-07-24 L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude Boil off gas reliquefying apparatus and lng supply system provided with the same
KR20190088007A (en) 2018-01-17 2019-07-25 레르 리키드 쏘시에떼 아노님 뿌르 레？드 에렉스뿔라따시옹 데 프로세데 조르즈 클로드 Boil off gas reliquefying apparatus and lng supply system provided with the same
KR20210118140A (en) 2019-02-27 2021-09-29 미쓰비시주코마린마시나리 가부시키가이샤 Boil-off gas treatment systems and vessels

Also Published As

Publication number Publication date
JP2001132899A (en) 2001-05-18

Similar Documents

Publication Publication Date Title
JP3908881B2 (en) Boil-off gas reliquefaction method
JP6718498B2 (en) Ship with engine
RU2144649C1 (en) Process and device for liquefaction of natural gas
US5755114A (en) Use of a turboexpander cycle in liquefied natural gas process
US6253574B1 (en) Method for liquefying a stream rich in hydrocarbons
US11774173B2 (en) Arctic cascade method for natural gas liquefaction in a high-pressure cycle with pre-cooling by ethane and sub-cooling by nitrogen, and a plant for its implementation
JPH05149678A (en) Method of liquefying nitrogen flow formed by cryogenic air separation
JP2019505755A (en) Inflator-based LNG production process reinforced with liquid nitrogen
JP2013506105A (en) Control of refrigerant composition
US20110113825A1 (en) Dual nitrogen expansion process
GB2147984A (en) A process for the liquefaction of natural gas
WO2000025061A1 (en) Reliquefaction of boil-off from pressure lng
CA2676177A1 (en) Method and apparatus for cooling a hydrocarbon stream
JP2012514050A (en) Method and apparatus for providing a fuel gas stream by eliminating nitrogen from a hydrocarbon stream
EP2650631A2 (en) Natural gas liquefaction with feed water removal
JP3673127B2 (en) Boil-off gas reliquefaction method
KR101167148B1 (en) Boil-off gas reliquefying apparatus
KR20090025514A (en) A bog re-liquefaction system for lng carrier
KR101940259B1 (en) Reliquefaction system
JP2010507771A (en) Method and apparatus for liquefying a hydrocarbon stream
WO2010080198A1 (en) Improved process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles
KR20170112947A (en) Vessel
US20230375261A1 (en) Closed loop lng process for a feed gas with nitrogen
KR101675879B1 (en) Device and method for re-liquefying BOG
EP3914869A1 (en) Gas liquefaction method and gas liquefaction device

Legal Events

Date Code Title Description
A977 Report on retrieval

Free format text: JAPANESE INTERMEDIATE CODE: A971007

Effective date: 20041021

A131 Notification of reasons for refusal

Free format text: JAPANESE INTERMEDIATE CODE: A131

Effective date: 20041026

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20041224

A02 Decision of refusal

Free format text: JAPANESE INTERMEDIATE CODE: A02

Effective date: 20050628

A521 Written amendment

Free format text: JAPANESE INTERMEDIATE CODE: A523

Effective date: 20050829

A911 Transfer to examiner for re-examination before appeal (zenchi)

Free format text: JAPANESE INTERMEDIATE CODE: A911

Effective date: 20050901

A912 Re-examination (zenchi) completed and case transferred to appeal board

Free format text: JAPANESE INTERMEDIATE CODE: A912

Effective date: 20051014

A61 First payment of annual fees (during grant procedure)

Free format text: JAPANESE INTERMEDIATE CODE: A61

Effective date: 20070119

R150 Certificate of patent or registration of utility model

Ref document number: 3908881

Country of ref document: JP

Free format text: JAPANESE INTERMEDIATE CODE: R150

Free format text: JAPANESE INTERMEDIATE CODE: R150

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20110126

Year of fee payment: 4

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20120126

Year of fee payment: 5

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20130126

Year of fee payment: 6

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

FPAY Renewal fee payment (event date is renewal date of database)

Free format text: PAYMENT UNTIL: 20140126

Year of fee payment: 7

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313117

S531 Written request for registration of change of domicile

Free format text: JAPANESE INTERMEDIATE CODE: R313531

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

S111 Request for change of ownership or part of ownership

Free format text: JAPANESE INTERMEDIATE CODE: R313115

R350 Written notification of registration of transfer

Free format text: JAPANESE INTERMEDIATE CODE: R350

R250 Receipt of annual fees

Free format text: JAPANESE INTERMEDIATE CODE: R250

EXPY Cancellation because of completion of term