WO2023079683A1 - Liquefied hydrogen storage method and liquefied hydrogen storage system - Google Patents

Liquefied hydrogen storage method and liquefied hydrogen storage system Download PDF

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Publication number
WO2023079683A1
WO2023079683A1 PCT/JP2021/040788 JP2021040788W WO2023079683A1 WO 2023079683 A1 WO2023079683 A1 WO 2023079683A1 JP 2021040788 W JP2021040788 W JP 2021040788W WO 2023079683 A1 WO2023079683 A1 WO 2023079683A1
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Prior art keywords
liquefied hydrogen
liquefied
tank
nitrogen
temperature
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PCT/JP2021/040788
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French (fr)
Japanese (ja)
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拓摩 上地
貴裕 山口
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川崎重工業株式会社
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Priority to PCT/JP2021/040788 priority Critical patent/WO2023079683A1/en
Publication of WO2023079683A1 publication Critical patent/WO2023079683A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C6/00—Methods and apparatus for filling vessels not under pressure with liquefied or solidified gases
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/32—Hydrogen storage

Definitions

  • the present disclosure relates to a liquefied hydrogen storage method and a liquefied hydrogen storage system for storing liquefied hydrogen in a liquefied hydrogen tank.
  • Patent Literature 1 describes a process of cooling the cryogenic tank with the heat of vaporization of liquefied gas and discharging the vaporized gas as a method of cooling down the cryogenic tank. It is disclosed to provide
  • the liquefied hydrogen cannot be stored in the liquefied hydrogen tank until the liquefied hydrogen tank is sufficiently cooled after the introduction of liquefied hydrogen has started. It cannot be stored and is discharged to the outside and consumed.
  • the amount of liquefied hydrogen consumed for cooling inside the liquefied hydrogen tank will increase. Since liquefied hydrogen has a low distribution volume and a high unit price, the conventional mode of cooling the liquefied hydrogen tank with liquefied hydrogen cannot reduce costs. Moreover, since such liquefied hydrogen is combustible, it is desirable to suppress the amount released into the atmosphere.
  • the present disclosure provides a liquefied hydrogen storage method and a liquefied hydrogen storage system that can reduce the amount of liquefied hydrogen consumed by vaporization when cooling the inside of the liquefied hydrogen tank to the temperature at which the liquefied hydrogen is stored. for the purpose.
  • a liquefied hydrogen storage method is a liquefied hydrogen storage method for storing liquefied hydrogen in a liquefied hydrogen tank, wherein nitrogen is used to remove oxygen in the liquefied hydrogen tank, and the oxygen is removed.
  • the liquefied hydrogen is introduced into the liquefied hydrogen tank, and the inside of the liquefied hydrogen tank is pre-cooled before introducing the liquefied hydrogen into the liquefied hydrogen tank.
  • a liquefied hydrogen storage method and a liquefied hydrogen storage system capable of appropriately introducing liquefied hydrogen into a liquefied hydrogen tank while suppressing consumption of liquefied hydrogen.
  • FIG. 1 is a diagram showing a schematic configuration of a liquefied hydrogen storage system according to an embodiment of the present disclosure.
  • FIG. 2 is a flow chart showing a method of introducing liquefied hydrogen in the system of FIG.
  • FIG. 3 is a diagram showing flows of refrigerant introduced into the liquefied hydrogen tank and gas discharged from the liquefied hydrogen tank according to the flowchart of FIG.
  • FIG. 1 is a diagram showing a schematic configuration of a liquefied hydrogen storage system according to an embodiment of the present disclosure.
  • the liquefied hydrogen storage system 100 is a system that stores liquefied hydrogen in the internal space 13 of the liquefied hydrogen tank 1 .
  • the liquefied hydrogen storage system may be abbreviated as storage system 100 .
  • liquefied hydrogen may be described as LH2 below.
  • the storage system 100 has a function of removing oxygen and moisture present in the internal space 13 of the liquefied hydrogen tank 1 and cooling the internal space 13 before filling the internal space 13 with liquefied hydrogen.
  • the liquefied hydrogen tank 1 has a double shell structure in order to improve heat insulation.
  • the liquefied hydrogen tank 1 has an outer tank 11 and an inner tank 12 that is housed in the outer tank 11 and forms an inner space 13 .
  • the outer tank 11 of the liquefied hydrogen tank 1 is formed in a spherical shape
  • the inner tank 12 is also formed in a spherical shape.
  • An inter-tank space 14 is formed between the inner surface of the outer tank 11 and the outer surface of the inner tank 12 .
  • the inter-tank space 14 is maintained in a vacuum state, and vacuum-insulates the internal space 13 from the outside of the liquefied hydrogen tank 1 .
  • Both the outer tank 11 and the inner tank 12 are constructed of pressure-resistant walls.
  • the outer tank 11 is configured to have a higher pressure resistance than the inner tank 12 in order to withstand the differential pressure between the atmospheric pressure and the pressure in the inter-tank space 14 .
  • the inner tank 12 may be configured to have a higher pressure resistance than the outer tank 11 .
  • a plurality of rods bridging between the inner surface of the outer tank 11 and the outer surface of the inner tank 12 may be provided in the inter-tank space 14 .
  • the storage system 100 includes a liquefied hydrogen introduction section 2 that introduces liquefied hydrogen LH 2 into the liquefied hydrogen tank 1 .
  • the liquefied hydrogen introduction unit 2 includes a first inlet 21 for drawing in liquefied hydrogen from the outside, a first outlet 22 for discharging the drawn liquefied hydrogen in the liquefied hydrogen tank 1, and a liquefied hydrogen introduction pipe 23 connecting them. I have.
  • the first discharge port 22 is provided in the upper portion of the internal space 13 of the liquefied hydrogen tank 1 .
  • the liquefied hydrogen introduction pipe 23 is provided with a first on-off valve 24 for switching between flow and non-flow of liquefied hydrogen.
  • the storage system 100 includes a low-temperature gas introduction section 3 that introduces low-temperature hydrogen gas obtained by vaporizing liquefied hydrogen into the liquefied hydrogen tank 1 .
  • low-temperature hydrogen gas may be described as GH2 .
  • the low-temperature gas introduction section 3 includes a vaporizer 25 that vaporizes the liquefied hydrogen drawn from the first inlet 21 .
  • the low-temperature hydrogen gas produced by the vaporizer 25 is discharged into the liquefied hydrogen tank 1 from the first discharge port 22 .
  • a discharge port dedicated to low-temperature hydrogen gas may be provided.
  • the vaporizer 25 and the first outlet 22 are connected by a low-temperature gas introduction pipe 26 .
  • the low-temperature gas introduction pipe 26 is provided with a second on-off valve 27 for switching between flow and non-flow of the low-temperature hydrogen gas.
  • the storage system 100 includes a liquefied nitrogen introduction section 4 that introduces liquefied nitrogen into the liquefied hydrogen tank 1 .
  • liquefied nitrogen may be described as LN2 .
  • the liquefied nitrogen introduction part 4 includes a second intake port 28 for drawing in liquefied nitrogen from the outside, a second discharge port 29 for discharging the drawn liquefied nitrogen in the liquefied hydrogen tank 1, and a liquefied nitrogen introduction pipe 30 connecting them. It has The second outlet 29 is provided in the lower portion of the internal space 13 of the liquefied hydrogen tank 1 .
  • the liquefied nitrogen introduction pipe 30 is provided with a third on-off valve 31 for switching between flow and non-flow of liquefied nitrogen.
  • the storage system 100 is provided with a first discharge pipe 32 for discharging oxygen and nitrogen gas GN2 from the liquefied hydrogen tank 1 in the oxygen removal process described later.
  • the first discharge pipe 32 is arranged such that one end is positioned above the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside.
  • the first discharge pipe 32 is provided with a first measuring device 33 for measuring the oxygen concentration in the first discharge pipe 32 .
  • the first measuring device 33 is, for example, an O2 sensor.
  • the storage system 100 is provided with a second discharge pipe 34 for discharging the nitrogen gas GN2 from the liquefied hydrogen tank 1 in the low-temperature hydrogen gas introduction step, which will be described later.
  • the second discharge pipe 34 is arranged so that one end is positioned below the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside.
  • the second discharge pipe 34 is provided with a second measuring device 35 for measuring the hydrogen gas concentration inside the second discharge pipe 34 .
  • the second measuring device 35 is, for example, an H2 sensor.
  • the storage system 100 includes a third discharge pipe 36 for discharging the hydrogen gas GH2 from the liquefied hydrogen tank 1 in the liquefied hydrogen introduction step described later.
  • the third discharge pipe 36 is arranged such that one end is positioned below the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside.
  • each of the discharge pipes 32, 34, and 36 is also provided with an on-off valve.
  • the second discharge pipe 34 and the third discharge pipe 36 may have a pipe structure in which a part of the route is a common route, or may be pipes common to each other.
  • the storage system 100 includes a controller 5.
  • the controller 5 acquires measurement results from the measuring instruments 33 and 35, and based on the results, controls the opening and closing of the on-off valves 24, 27 and 31 and the on-off valves of the discharge pipes 32, 34 and 36.
  • the controller 5 is configured as a processing circuit having a processor, volatile memory, non-volatile memory, I/O interface, and the like.
  • a circuit, unit, or means is hardware that performs or is programmed to perform the recited functions.
  • the hardware may be the hardware disclosed herein, or other known hardware programmed or configured to perform the recited functions.
  • a circuit, unit or means is a combination of hardware and software where the hardware is a processor which is considered a type of circuit, the software being used to configure the hardware or the processor.
  • FIG. 2 is a flow chart showing the liquefied hydrogen introduction method in the system of FIG.
  • FIG. 3 is a diagram showing flows of refrigerant introduced into the liquefied hydrogen tank and gas discharged from the liquefied hydrogen tank according to the flowchart of FIG.
  • the components other than the circulation points of the refrigerant introduced in steps S1, S3, and S5 described later and the exhaust gas are omitted.
  • the internal space 13 of the liquefied hydrogen tank 1 contains air, that is, oxygen, nitrogen, water vapor, etc. at room temperature. Moreover, the pressure of the internal space 13 is adjusted in advance so that the dew point temperature of the internal space 13 becomes a predetermined value.
  • an oxygen removal step is performed to remove oxygen in the liquefied hydrogen tank 1 using nitrogen (step S1).
  • the oxygen removing step the oxygen O 2 and moisture in the liquefied hydrogen tank 1 are removed by introducing the liquefied nitrogen LN 2 from the liquefied nitrogen inlet 4 .
  • the controller 5 opens the third on-off valve 31 to introduce liquefied nitrogen into the internal space 13 of the liquefied hydrogen tank 1 from the liquefied nitrogen introduction pipe 30 .
  • oxygen in the internal space 13 of the liquefied hydrogen tank 1 is removed while cooling the internal space 13 of the liquefied hydrogen tank 1 with liquefied nitrogen.
  • the liquefied nitrogen introduced from the lower part of the internal space 13 and the low-temperature nitrogen gas vaporized by cooling the internal space 13 have a higher specific gravity than the residual air in the internal space 13, that is, normal temperature oxygen and nitrogen. It accumulates from the bottom of the space 13 and pushes the remaining air upwards. Therefore, residual air is discharged from the first discharge pipe 32 provided in the upper part of the internal space 13, and oxygen is efficiently removed.
  • the internal space 13 When the removal of oxygen has been completed, that is, when the oxygen concentration is less than the predetermined first reference value, the internal space 13 is filled with the introduced liquefied nitrogen through heat exchange with the internal space 13 to vaporize The resulting low-temperature nitrogen gas GN2 atmosphere. At this time, the temperature of the internal space 13 becomes the first precooling temperature which is somewhat higher than the boiling point of nitrogen. For example, the first precooling temperature is about -180°C.
  • the controller 5 determines whether the oxygen concentration measured by the first measuring device 33 is less than the first reference value (step S2).
  • the first reference value is set to a value when the oxygen concentration in the internal space 13 is sufficiently lower than the liquefied hydrogen combustion conditions.
  • the combustion condition for setting the first reference value is determined according to the dew point temperature preset in the internal space 13 .
  • the next step is a nitrogen removal step for removing low-temperature nitrogen gas in the internal space 13 of the liquefied hydrogen tank 1 .
  • the nitrogen removal step the low-temperature hydrogen gas GH 2 obtained by vaporizing the liquefied hydrogen LH 2 is introduced into the liquefied hydrogen tank 1 from the low-temperature gas introduction part 3, thereby reducing the nitrogen gas GN in the internal space 13 of the liquefied hydrogen tank 1. 2 is removed (step S3).
  • the controller 5 closes the third on-off valve 31 from the state of the oxygen removal step, and opens the second on-off valve 27 to introduce the low-temperature hydrogen gas from the low-temperature gas introduction pipe 26 into the internal space 13 of the liquefied hydrogen tank 1. to introduce The vaporizer 25 vaporizes the liquefied hydrogen LH 2 introduced from the first intake port 21 to generate low-temperature hydrogen gas GH 2 at a predetermined temperature.
  • the temperature of the low-temperature hydrogen gas is within a predetermined range including the temperature at the end of the oxygen removal process. For example, if the temperature at the end of the oxygen removal step is -180°C, the temperature of the cold hydrogen gas is set to -180 ⁇ 10°C. As a result, the difference between the temperature at the time of oxygen removal and the temperature at the time of subsequent nitrogen removal is reduced, so that the liquefied or solidified nitrogen can be prevented while maintaining the cooling state inside the liquefied hydrogen tank 1 .
  • Low-temperature hydrogen gas is sprayed from a first outlet 22 provided in the upper portion of the internal space 13 . Since the low-temperature hydrogen gas GH2 introduced from the upper part of the internal space 13 has a lower specific gravity than the residual nitrogen GN2 in the internal space 13, it accumulates in the upper part of the internal space 13 and pushes the residual nitrogen downward. Therefore, residual nitrogen is discharged from the second discharge pipe 34 provided in the lower part of the internal space 13, and efficient nitrogen removal is performed.
  • the internal space 13 becomes the atmosphere of the low-temperature hydrogen gas GH 2 introduced into the internal space 13 .
  • the temperature of the internal space 13 becomes the second precooling temperature equal to or somewhat higher than the introduction temperature of the low-temperature hydrogen gas.
  • the second precooling temperature is, for example, about -180°C to -160°C.
  • the controller 5 determines whether the hydrogen concentration measured by the second measuring device 35 has become higher than the second reference value (step S4).
  • the second reference value is set to a value when the nitrogen concentration in the internal space 13 is sufficiently low.
  • the next step is the liquefied hydrogen introduction step of introducing the liquefied hydrogen LH2 into the internal space 13 of the liquefied hydrogen tank 1 from which oxygen and nitrogen have been removed.
  • the liquefied hydrogen introduction step the liquefied hydrogen LH 2 is introduced into the liquefied hydrogen tank 1 from the liquefied hydrogen introduction part 2, thereby removing the low-temperature hydrogen gas GH 2 in the internal space 13 of the liquefied hydrogen tank 1, and Liquefied hydrogen is stored in the space 13 (step S5).
  • the controller 5 closes the second on-off valve 27 from the state of the nitrogen removal process, and opens the first on-off valve 24 to introduce the liquefied hydrogen LH into the internal space 13 of the liquefied hydrogen tank 1 from the liquefied hydrogen introduction pipe 23 . 2 .
  • Liquefied hydrogen is sprayed from the first outlet 22 provided in the upper part of the internal space 13 .
  • the liquefied hydrogen LH 2 introduced from the upper portion of the internal space 13 further cools the inside of the internal space 13 to a liquefied hydrogen storage temperature near the temperature at which liquefied hydrogen can be stored.
  • the temperature at which liquefied hydrogen can be stored is the temperature of the boiling point of liquefied hydrogen, that is, -252.6°C.
  • the low-temperature hydrogen gas GH 2 which is the residual gas from the previous process, is discharged from the third discharge pipe 36 .
  • the liquefied hydrogen is stored in the internal space 13 without being vaporized.
  • the inside of the liquefied hydrogen tank 1 is pre-cooled. Therefore, when introducing liquefied hydrogen into the liquefied hydrogen tank 1, the amount of liquefied hydrogen consumed for cooling the liquefied hydrogen tank 1 is reduced. Therefore, when cooling the inside of the liquefied hydrogen tank 1 to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced.
  • the inside of the liquefied hydrogen tank 1 is cooled step by step, so that localized thermal shrinkage of the liquefied hydrogen tank 1 can be made more difficult to occur.
  • the inside of the liquefied hydrogen tank 1 is pre-cooled with liquefied nitrogen in the oxygen removal step, so consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced.
  • liquefied nitrogen to cool the inside of the liquefied hydrogen tank 1 from normal temperature to the first precooling temperature close to the boiling point of liquefied nitrogen, liquefied hydrogen or low-temperature hydrogen gas is used for cooling from normal temperature to the first precooling temperature.
  • the cooling efficiency including the manufacturing cost of the refrigerant can be made higher.
  • the nitrogen vaporized during the oxygen removal is further removed with low-temperature hydrogen gas. Since the low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen is introduced before the liquefied hydrogen is introduced, the process of separately removing the coolant in the liquefied hydrogen tank 1 after cooling with the low-temperature hydrogen gas is not required. Also, by introducing the low-temperature hydrogen gas, the nitrogen used for removing oxygen in the oxygen removal step can be removed by the low-temperature hydrogen gas. This eliminates the need to use liquefied hydrogen to remove nitrogen, thereby reducing the consumption of liquefied hydrogen.
  • nitrogen at normal temperature is introduced to remove oxygen in the liquefied hydrogen tank 1, and then liquefied hydrogen is introduced to remove nitrogen.
  • Some of the nitrogen in the tank may cool rapidly causing the nitrogen to locally solidify or liquefy.
  • local thermal contraction of the liquefied hydrogen tank 1 tends to occur at the location where the solidified or liquefied nitrogen occurs.
  • liquid nitrogen is introduced to remove oxygen in the liquefied hydrogen tank 1
  • low-temperature nitrogen gas is present in the liquefied hydrogen tank 1 at the stage where the low-temperature hydrogen gas is introduced. It means that it is full. Therefore, rapid cooling of nitrogen caused by the introduction of low-temperature hydrogen gas can be suppressed, and local solidification or liquefaction of nitrogen can be prevented.
  • the amount of liquefied hydrogen required to cool the internal space 13 to the liquefied hydrogen storage temperature is It increases as the volume increases.
  • the amount of liquefied hydrogen required for cooling to the liquefied hydrogen storage temperature can be suppressed to, for example, about 1/5 of that in the conventional method.
  • the required amount of nitrogen increases compared to the conventional method, but compared to the production cost and maintenance cost of liquefied hydrogen LH2 , the introduction cost of nitrogen, especially liquefied nitrogen, is lower. , it is possible to reduce the cost of the entire system.
  • the liquefied hydrogen tank 1 becomes larger, the amount of liquefied hydrogen GH 2 released into the atmosphere increases in the conventional method, and cannot be ignored.
  • the problem of solidification or liquefaction of nitrogen described above becomes apparent in the conventional method.
  • the introduction mode of the present embodiment even if the liquefied hydrogen tank 1 is increased in size, it is possible to effectively suppress the increase in the amount of hydrogen released into the atmosphere, and to prevent the solidification or liquefaction of nitrogen. can do. Therefore, even if the size of the liquefied hydrogen tank 1 is increased, an increase in consumption of liquefied hydrogen can be suppressed and the inside of the liquefied hydrogen tank 1 can be cooled appropriately.
  • the liquefied nitrogen introduction pipe 30, the second discharge pipe 34, and the third discharge pipe 36 are provided separately, but at least any two of them may be shared. good.
  • the low-temperature hydrogen gas GH2 introduced in the nitrogen removal step is generated by vaporizing the liquefied hydrogen LH2 in the vaporizer 25, but the present invention is not limited to this.
  • low-temperature hydrogen gas generated by heat exchange between liquefied hydrogen and an object to be cooled in that facility is introduced into the internal space 13 of the liquefied hydrogen tank 1 from the low-temperature gas introduction pipe 26. may be introduced into
  • the first measuring device 33 for measuring the oxygen concentration is provided inside the first discharge pipe 32, but the first measuring device 33 may be provided inside the internal space 13. .
  • the second measuring device 35 for measuring the hydrogen gas concentration is provided inside the second discharge pipe 34, but the second measuring device 35 is provided inside the internal space 13. good too.
  • both introducing the liquefied nitrogen LN 2 in the oxygen removing step and introducing the low-temperature hydrogen gas GH 2 before the liquefied hydrogen introducing step in the nitrogen removing step are performed.
  • the implementation mode has been exemplified, only one of the introduction of liquefied nitrogen and the introduction of low-temperature hydrogen gas may be implemented.
  • the spherical liquefied hydrogen tank 1 was exemplified, but the shape of the liquefied hydrogen tank 1 is not particularly limited, and may be cylindrical, square, or the like. Also, the type of the liquefied hydrogen tank 1 is not particularly limited, and may be, for example, a membrane system, a self-supporting sphere system, or the like.
  • a liquefied hydrogen storage method is a liquefied hydrogen storage method for storing liquefied hydrogen in a liquefied hydrogen tank, wherein nitrogen is used to remove oxygen in the liquefied hydrogen tank, and the oxygen is removed.
  • the liquefied hydrogen is introduced into the liquefied hydrogen tank, and the inside of the liquefied hydrogen tank is pre-cooled before introducing the liquefied hydrogen into the liquefied hydrogen tank.
  • the inside of the liquefied hydrogen tank is pre-cooled before the liquefied hydrogen is introduced into the liquefied hydrogen tank. Therefore, when introducing liquefied hydrogen into the liquefied hydrogen tank, the amount of liquefied hydrogen consumed for cooling the liquefied hydrogen tank is reduced. Therefore, when cooling the inside of the liquefied hydrogen tank to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced.
  • a low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen may be introduced before the liquefied hydrogen is introduced. According to this, after the liquefied nitrogen is introduced, the nitrogen vaporized during oxygen removal is further removed with the low-temperature hydrogen gas. Since the low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen is introduced before the liquefied hydrogen is introduced, there is no need to separately remove the refrigerant in the liquefied hydrogen tank after cooling with the low-temperature hydrogen gas. Also, by introducing the low-temperature hydrogen gas, the nitrogen used for removing oxygen can be removed by the low-temperature hydrogen gas. Since this eliminates the need to use liquefied hydrogen for removing nitrogen, the consumption of liquefied hydrogen can be suppressed.
  • the oxygen in the liquefied hydrogen tank may be removed by introducing liquefied nitrogen. According to this, since the inside of the liquefied hydrogen tank is pre-cooled by the liquefied nitrogen, consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced.
  • liquefied nitrogen to cool the inside of the liquefied hydrogen tank from room temperature to a temperature close to the boiling point of liquefied nitrogen, compared to using liquefied hydrogen or low-temperature hydrogen gas for cooling from room temperature to the temperature, refrigerant The cooling efficiency including the manufacturing cost of can be made higher.
  • nitrogen in the liquefied hydrogen tank may be removed by introducing low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen. According to this, since liquid nitrogen is introduced to remove oxygen in the liquefied hydrogen tank, the liquefied hydrogen tank is filled with low temperature nitrogen gas at the stage where the low temperature hydrogen gas is introduced. . Therefore, rapid cooling of nitrogen caused by the introduction of low-temperature hydrogen gas can be suppressed, and local solidification or liquefaction of nitrogen can be prevented.
  • the temperature of the low-temperature hydrogen gas may be a temperature within a predetermined range including the temperature at the end of the removal of oxygen.
  • the liquefied nitrogen may be introduced from the bottom of the liquefied hydrogen tank. According to this, the liquefied nitrogen introduced from the lower part of the liquefied hydrogen tank and the low-temperature nitrogen gas vaporized by cooling the inside of the liquefied hydrogen tank are mixed with the remaining air in the liquefied hydrogen tank, that is, normal temperature oxygen and nitrogen. Since it has a higher specific gravity, it accumulates from the bottom of the liquefied hydrogen tank and pushes the remaining air upwards. Therefore, by discharging residual air from the upper portion of the liquefied hydrogen tank, oxygen can be removed efficiently.
  • a liquefied hydrogen storage system is a liquefied hydrogen storage system for storing liquefied hydrogen in a liquefied hydrogen tank, comprising: a liquefied nitrogen introduction pipe for introducing liquefied nitrogen into the liquefied hydrogen tank; An introduction pipe and a liquefied hydrogen introduction pipe for introducing the liquefied hydrogen are provided.
  • the liquefied nitrogen is introduced to remove the oxygen in the liquefied hydrogen tank, thereby removing the oxygen in the liquefied hydrogen tank while cooling the inside of the liquefied hydrogen tank with the liquefied nitrogen. Therefore, since the inside of the liquefied hydrogen tank is pre-cooled before the liquefied hydrogen is introduced, consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced. Further, after oxygen is removed by introducing liquefied nitrogen, and before introducing liquefied hydrogen, the nitrogen vaporized during oxygen removal is removed with low temperature hydrogen gas. Since this eliminates the need to use liquefied hydrogen for removing nitrogen, the consumption of liquefied hydrogen can be suppressed. Therefore, when cooling the inside of the liquefied hydrogen tank to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced.

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  • General Engineering & Computer Science (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

A liquefied hydrogen storage method is for storing liquefied hydrogen in a liquefied hydrogen tank. Oxygen in the liquefied hydrogen tank is removed using nitrogen, liquefied hydrogen is introduced into the liquefied hydrogen tank from which oxygen has been removed, and before liquefied hydrogen is introduced into the liquefied hydrogen tank, the inside of the liquefied hydrogen tank is precooled.

Description

液化水素貯留方法および液化水素貯留システムLiquefied hydrogen storage method and liquefied hydrogen storage system
　本開示は、液化水素タンクに液化水素を貯留するための液化水素貯留方法および液化水素貯留システムに関する。 The present disclosure relates to a liquefied hydrogen storage method and a liquefied hydrogen storage system for storing liquefied hydrogen in a liquefied hydrogen tank.
　液化水素タンクに液化水素を導入する場合には、まず、液化水素タンク内の酸素および水分を除去する工程が必要である。この工程は、液化水素タンク内の酸素濃度を、可燃性の液化水素の燃焼条件よりも十分に下げること、および、液化水素タンク内が、液化水素が導入されることにより低温になった際、液化水素タンクに設けられる各種バルブ、または計器類等に残留水蒸気が凝結し、機能不全を生じないように、液化水素タンク内の露点を十分下げることを目的としている。 When introducing liquefied hydrogen into a liquefied hydrogen tank, it is first necessary to remove the oxygen and moisture in the liquefied hydrogen tank. This process is to lower the oxygen concentration in the liquefied hydrogen tank sufficiently below the combustion condition of combustible liquefied hydrogen, and when the temperature inside the liquefied hydrogen tank becomes low due to the introduction of liquefied hydrogen, The purpose is to sufficiently lower the dew point in the liquefied hydrogen tank so that residual water vapor does not condense on various valves or instruments installed in the liquefied hydrogen tank, causing malfunction.
　従来は、酸素および水分除去の工程の後、液化水素タンクに液化水素を導入しているが、液化水素の導入時において、液化水素タンク内は常温であるため、常温の液化水素タンク内に直接液化水素を導入すると、液化水素の貯留時に液化水素タンクに局部的な熱収縮による亀裂または変形等が生じる恐れがある。このような低温タンクの亀裂または変形等の問題に関し、例えば下記特許文献１には、低温タンクのクールダウン方法として、液化ガスの気化熱で低温タンクを冷却し、気化したガスを排出する工程を設けることが開示されている。 Conventionally, liquefied hydrogen is introduced into the liquefied hydrogen tank after the process of removing oxygen and water. When liquefied hydrogen is introduced, the liquefied hydrogen tank may crack or deform due to local thermal contraction during storage of liquefied hydrogen. Regarding such problems such as cracks or deformation of the cryogenic tank, for example, Patent Literature 1 below describes a process of cooling the cryogenic tank with the heat of vaporization of liquefied gas and discharging the vaporized gas as a method of cooling down the cryogenic tank. It is disclosed to provide
特開昭５４－４０３２７号公報JP-A-54-40327
　しかし、上記のような方法を液化水素タンクへの液化水素の導入に適用しても、液化水素の導入開始後も液化水素タンクが十分に冷却されるまでは、液化水素を液化水素タンク内に貯留することができず、外部に排出され、消費されてしまう。 However, even if the method described above is applied to the introduction of liquefied hydrogen into the liquefied hydrogen tank, the liquefied hydrogen cannot be stored in the liquefied hydrogen tank until the liquefied hydrogen tank is sufficiently cooled after the introduction of liquefied hydrogen has started. It cannot be stored and is discharged to the outside and consumed.
　特に、液化水素タンクの容量を大きくしようとすると、液化水素タンク内の冷却のために消費される液化水素の量が増大する。液化水素は、流通量が少なく、単価が高いため、液化水素によって液化水素タンクを冷却する従来の態様は、コストの低減を図ることができない。また、このような液化水素は、可燃性であるため、大気放出量を抑制することが望ましい。 In particular, if you try to increase the capacity of the liquefied hydrogen tank, the amount of liquefied hydrogen consumed for cooling inside the liquefied hydrogen tank will increase. Since liquefied hydrogen has a low distribution volume and a high unit price, the conventional mode of cooling the liquefied hydrogen tank with liquefied hydrogen cannot reduce costs. Moreover, since such liquefied hydrogen is combustible, it is desirable to suppress the amount released into the atmosphere.
　そこで本開示は、液化水素タンク内を液化水素が貯留される温度まで冷却する際に、液化水素が気化により消費される量を低減することができる液化水素貯留方法および液化水素貯留システムを提供することを目的とする。 Therefore, the present disclosure provides a liquefied hydrogen storage method and a liquefied hydrogen storage system that can reduce the amount of liquefied hydrogen consumed by vaporization when cooling the inside of the liquefied hydrogen tank to the temperature at which the liquefied hydrogen is stored. for the purpose.
　本開示の一形態に係る液化水素貯留方法は、液化水素タンクに液化水素を貯留するための液化水素貯留方法であって、窒素を用いて前記液化水素タンク内の酸素を除去し、酸素が除去された前記液化水素タンクに前記液化水素を導入し、前記液化水素タンクに前記液化水素を導入する前に、前記液化水素タンク内を予め冷却する。 A liquefied hydrogen storage method according to one aspect of the present disclosure is a liquefied hydrogen storage method for storing liquefied hydrogen in a liquefied hydrogen tank, wherein nitrogen is used to remove oxygen in the liquefied hydrogen tank, and the oxygen is removed. The liquefied hydrogen is introduced into the liquefied hydrogen tank, and the inside of the liquefied hydrogen tank is pre-cooled before introducing the liquefied hydrogen into the liquefied hydrogen tank.
　本開示によれば、液化水素の消費を抑制しつつ液化水素タンクに液化水素を適切に導入することができる液化水素貯留方法および液化水素貯留システムを提供できる。 According to the present disclosure, it is possible to provide a liquefied hydrogen storage method and a liquefied hydrogen storage system capable of appropriately introducing liquefied hydrogen into a liquefied hydrogen tank while suppressing consumption of liquefied hydrogen.
図１は、本開示の一実施の形態に係る液化水素貯留システムの概略構成を示す図である。FIG. 1 is a diagram showing a schematic configuration of a liquefied hydrogen storage system according to an embodiment of the present disclosure. 図２は、図１のシステムにおける液化水素導入方法を示すフローチャートである。FIG. 2 is a flow chart showing a method of introducing liquefied hydrogen in the system of FIG. 図３は、図２のフローチャートに従って液化水素タンクに導入される冷媒および液化水素タンクから排出されるガスの流れを示す図である。FIG. 3 is a diagram showing flows of refrigerant introduced into the liquefied hydrogen tank and gas discharged from the liquefied hydrogen tank according to the flowchart of FIG.
　以下、図面を参照しながら一実施の形態について説明する。なお、全ての図を通じて、同一のまたは対応する要素には同一の符号を付して重複する詳細な説明を省略する。 An embodiment will be described below with reference to the drawings. The same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and overlapping detailed descriptions are omitted.
　図１は、本開示の一実施の形態に係る液化水素貯留システムの概略構成を示す図である。図１に示すように、液化水素貯留システム１００は、液化水素タンク１の内部空間１３に液化水素を貯留するシステムである。以下では、液化水素貯留システムは、貯留システム１００と略記する場合がある。また、以下では、液化水素は、ＬＨ２と表記する場合がある。貯留システム１００は、液化水素を内部空間１３に充填する前に、液化水素タンク１の内部空間１３に存在する酸素および水分を除去し、内部空間１３を冷却する機能を有している。 FIG. 1 is a diagram showing a schematic configuration of a liquefied hydrogen storage system according to an embodiment of the present disclosure. As shown in FIG. 1 , the liquefied hydrogen storage system 100 is a system that stores liquefied hydrogen in the internal space 13 of the liquefied hydrogen tank 1 . Below, the liquefied hydrogen storage system may be abbreviated as storage system 100 . Moreover, liquefied hydrogen may be described as LH2 below. The storage system 100 has a function of removing oxygen and moisture present in the internal space 13 of the liquefied hydrogen tank 1 and cooling the internal space 13 before filling the internal space 13 with liquefied hydrogen.
　液化水素タンク１は、断熱性を高めるため、二重殻構造を有している。液化水素タンク１は、外槽１１と、外槽１１に収容されて内部空間１３を形成する内槽１２とを有している。一例として、液化水素タンク１の外槽１１は球状に形成され、内槽１２も球状に形成される。外槽１１の内面と内槽１２の外面との間には、槽間空間１４が形成される。槽間空間１４は、真空状態に維持され、内部空間１３を液化水素タンク１の外部に対して真空断熱する。 The liquefied hydrogen tank 1 has a double shell structure in order to improve heat insulation. The liquefied hydrogen tank 1 has an outer tank 11 and an inner tank 12 that is housed in the outer tank 11 and forms an inner space 13 . As an example, the outer tank 11 of the liquefied hydrogen tank 1 is formed in a spherical shape, and the inner tank 12 is also formed in a spherical shape. An inter-tank space 14 is formed between the inner surface of the outer tank 11 and the outer surface of the inner tank 12 . The inter-tank space 14 is maintained in a vacuum state, and vacuum-insulates the internal space 13 from the outside of the liquefied hydrogen tank 1 .
　外槽１１および内槽１２は、いずれも耐圧壁で構成されている。例えば、外槽１１は、大気圧と槽間空間１４の圧力との間の差圧に耐えるために内槽１２よりも耐圧性能が高く構成されている。ただし、内槽１２が外槽１１よりも耐圧性能が高く構成されていてもよい。槽間空間１４には、外槽１１の内面と内槽１２の外面とに架け渡される複数のロッドが設けられていてもよい。 Both the outer tank 11 and the inner tank 12 are constructed of pressure-resistant walls. For example, the outer tank 11 is configured to have a higher pressure resistance than the inner tank 12 in order to withstand the differential pressure between the atmospheric pressure and the pressure in the inter-tank space 14 . However, the inner tank 12 may be configured to have a higher pressure resistance than the outer tank 11 . A plurality of rods bridging between the inner surface of the outer tank 11 and the outer surface of the inner tank 12 may be provided in the inter-tank space 14 .
　貯留システム１００は、液化水素タンク１に液化水素ＬＨ２を導入する液化水素導入部２を備えている。液化水素導入部２は、外部から液化水素を引き込む第１引込口２１と、液化水素タンク１内において、引き込んだ液化水素を吐出する第１吐出口２２と、それらを繋ぐ液化水素導入配管２３を備えている。第１吐出口２２は、液化水素タンク１の内部空間１３の上部に設けられる。液化水素導入配管２３には、液化水素の流通または不通を切り替える第１開閉弁２４が設けられる。 The storage system 100 includes a liquefied hydrogen introduction section 2 that introduces liquefied hydrogen LH 2 into the liquefied hydrogen tank 1 . The liquefied hydrogen introduction unit 2 includes a first inlet 21 for drawing in liquefied hydrogen from the outside, a first outlet 22 for discharging the drawn liquefied hydrogen in the liquefied hydrogen tank 1, and a liquefied hydrogen introduction pipe 23 connecting them. I have. The first discharge port 22 is provided in the upper portion of the internal space 13 of the liquefied hydrogen tank 1 . The liquefied hydrogen introduction pipe 23 is provided with a first on-off valve 24 for switching between flow and non-flow of liquefied hydrogen.
　さらに、貯留システム１００は、液化水素タンク１に液化水素を気化させた低温水素ガスを導入する低温ガス導入部３を備えている。以下では、低温水素ガスは、ＧＨ２と表記する場合がある。低温ガス導入部３は、第１引込口２１から引き込んだ液化水素を気化させる気化器２５を備えている。本実施の形態において、気化器２５で生成された低温水素ガスは、第１吐出口２２から液化水素タンク１内に吐出される。これに代えて、低温水素ガス専用の吐出口が設けられてもよい。気化器２５と第１吐出口２２とは、低温ガス導入配管２６により接続されている。低温ガス導入配管２６には、低温水素ガスの流通または不通を切り替える第２開閉弁２７が設けられる。 Furthermore, the storage system 100 includes a low-temperature gas introduction section 3 that introduces low-temperature hydrogen gas obtained by vaporizing liquefied hydrogen into the liquefied hydrogen tank 1 . Below, low-temperature hydrogen gas may be described as GH2 . The low-temperature gas introduction section 3 includes a vaporizer 25 that vaporizes the liquefied hydrogen drawn from the first inlet 21 . In this embodiment, the low-temperature hydrogen gas produced by the vaporizer 25 is discharged into the liquefied hydrogen tank 1 from the first discharge port 22 . Alternatively, a discharge port dedicated to low-temperature hydrogen gas may be provided. The vaporizer 25 and the first outlet 22 are connected by a low-temperature gas introduction pipe 26 . The low-temperature gas introduction pipe 26 is provided with a second on-off valve 27 for switching between flow and non-flow of the low-temperature hydrogen gas.
　さらに、貯留システム１００は、液化水素タンク１に液化窒素を導入する液化窒素導入部４を備えている。以下では、液化窒素は、ＬＮ２と表記する場合がある。液化窒素導入部４は、外部から液化窒素を引き込む第２引込口２８と、液化水素タンク１内において、引き込んだ液化窒素を吐出する第２吐出口２９と、それらを繋ぐ液化窒素導入配管３０とを備えている。第２吐出口２９は、液化水素タンク１の内部空間１３の下部に設けられる。液化窒素導入配管３０には、液化窒素の流通または不通を切り替える第３開閉弁３１が設けられる。 Furthermore, the storage system 100 includes a liquefied nitrogen introduction section 4 that introduces liquefied nitrogen into the liquefied hydrogen tank 1 . Below, liquefied nitrogen may be described as LN2 . The liquefied nitrogen introduction part 4 includes a second intake port 28 for drawing in liquefied nitrogen from the outside, a second discharge port 29 for discharging the drawn liquefied nitrogen in the liquefied hydrogen tank 1, and a liquefied nitrogen introduction pipe 30 connecting them. It has The second outlet 29 is provided in the lower portion of the internal space 13 of the liquefied hydrogen tank 1 . The liquefied nitrogen introduction pipe 30 is provided with a third on-off valve 31 for switching between flow and non-flow of liquefied nitrogen.
　さらに、貯留システム１００は、後述する酸素除去工程において、液化水素タンク１から酸素および窒素ガスＧＮ２を排出するための第１排出配管３２を備えている。第１排出配管３２は、一端部が液化水素タンク１の内部空間１３の上部に位置し、他端部が外部に位置するように、配設される。第１排出配管３２には、第１排出配管３２内の酸素濃度を計測する第１計測器３３が設けられる。第１計測器３３は、例えばＯ２センサである。 Further, the storage system 100 is provided with a first discharge pipe 32 for discharging oxygen and nitrogen gas GN2 from the liquefied hydrogen tank 1 in the oxygen removal process described later. The first discharge pipe 32 is arranged such that one end is positioned above the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside. The first discharge pipe 32 is provided with a first measuring device 33 for measuring the oxygen concentration in the first discharge pipe 32 . The first measuring device 33 is, for example, an O2 sensor.
　さらに、貯留システム１００は、後述する低温水素ガス導入工程において、液化水素タンク１から窒素ガスＧＮ２を排出するための第２排出配管３４を備えている。第２排出配管３４は、一端部が液化水素タンク１の内部空間１３の下部に位置し、他端部が外部に位置するように、配設される。第２排出配管３４には、第２排出配管３４内の水素ガス濃度を計測する第２計測器３５が設けられる。第２計測器３５は、例えばＨ２センサである。 Furthermore, the storage system 100 is provided with a second discharge pipe 34 for discharging the nitrogen gas GN2 from the liquefied hydrogen tank 1 in the low-temperature hydrogen gas introduction step, which will be described later. The second discharge pipe 34 is arranged so that one end is positioned below the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside. The second discharge pipe 34 is provided with a second measuring device 35 for measuring the hydrogen gas concentration inside the second discharge pipe 34 . The second measuring device 35 is, for example, an H2 sensor.
　さらに、貯留システム１００は、後述する液化水素導入工程において、液化水素タンク１から水素ガスＧＨ２を排出するための第３排出配管３６を備えている。第３排出配管３６は、一端部が液化水素タンク１の内部空間１３の下部に位置し、他端部が外部に位置するように、配設される。なお、図示していないが、各排出配管３２，３４，３６のそれぞれにも開閉弁が設けられる。また、第２排出配管３４と第３排出配管３６とは、一部の経路が共通の経路となる配管構造としてもよいし、互いに共通の配管としてもよい。 Further, the storage system 100 includes a third discharge pipe 36 for discharging the hydrogen gas GH2 from the liquefied hydrogen tank 1 in the liquefied hydrogen introduction step described later. The third discharge pipe 36 is arranged such that one end is positioned below the internal space 13 of the liquefied hydrogen tank 1 and the other end is positioned outside. Although not shown, each of the discharge pipes 32, 34, and 36 is also provided with an on-off valve. Further, the second discharge pipe 34 and the third discharge pipe 36 may have a pipe structure in which a part of the route is a common route, or may be pipes common to each other.
　さらに、貯留システム１００は、制御器５を備えている。制御器５は、各計測器３３，３５における計測結果を取得し、その結果に基づいて、各開閉弁２４，２７，３１および各排出配管３２，３４，３６の各開閉弁の開閉制御を行う。制御器５は、プロセッサ、揮発性メモリ、不揮発性メモリおよびＩ／Ｏインターフェース等を有する処理回路として構成される。 Furthermore, the storage system 100 includes a controller 5. The controller 5 acquires measurement results from the measuring instruments 33 and 35, and based on the results, controls the opening and closing of the on-off valves 24, 27 and 31 and the on-off valves of the discharge pipes 32, 34 and 36. . The controller 5 is configured as a processing circuit having a processor, volatile memory, non-volatile memory, I/O interface, and the like.
　なお、本明細書で開示する要素の機能は、開示された機能を実行するよう構成またはプログラムされた汎用プロセッサ、専用プロセッサ、集積回路、ASIC（Application Specific Integrated Circuits）、従来の回路、または、それらの組み合わせを含む回路または処理回路を使用して実行できる。プロセッサは、トランジスタやその他の回路を含むため、処理回路または回路と見なされる。本明細書において、回路、ユニット、または手段は、列挙された機能を実行するハードウェアであるか、または、列挙された機能を実行するようにプログラムされたハードウェアである。ハードウェアは、本明細書に開示されているハードウェアであってもよいし、あるいは、列挙された機能を実行するようにプログラムまたは構成されているその他の既知のハードウェアであってもよい。ハードウェアが回路の一種と考えられるプロセッサである場合、回路、ユニット、または手段はハードウェアとソフトウェアとの組み合わせであり、ソフトウェアはハードウェアまたはプロセッサの構成に使用される。 It should be noted that the functionality of the elements disclosed herein may be achieved by general purpose processors, special purpose processors, integrated circuits, Application Specific Integrated Circuits (ASICs), conventional circuits, or any combination thereof configured or programmed to perform the disclosed functions. can be implemented using a circuit or processing circuit that includes a combination of A processor is considered a processing circuit or circuit because it includes transistors and other circuits. As used herein, a circuit, unit, or means is hardware that performs or is programmed to perform the recited functions. The hardware may be the hardware disclosed herein, or other known hardware programmed or configured to perform the recited functions. A circuit, unit or means is a combination of hardware and software where the hardware is a processor which is considered a type of circuit, the software being used to configure the hardware or the processor.
　図２は、図１のシステムにおける液化水素導入方法を示すフローチャートである。また、図３は、図２のフローチャートに従って液化水素タンクに導入される冷媒および液化水素タンクから排出されるガスの流れを示す図である。図３においては、図１に示す貯留システム１００の各構成のうち、後述するステップＳ１，Ｓ３，Ｓ５において導入される冷媒および排出ガスの流通箇所以外の構成は図示を省略している。 FIG. 2 is a flow chart showing the liquefied hydrogen introduction method in the system of FIG. FIG. 3 is a diagram showing flows of refrigerant introduced into the liquefied hydrogen tank and gas discharged from the liquefied hydrogen tank according to the flowchart of FIG. In FIG. 3, among the components of the storage system 100 shown in FIG. 1, the components other than the circulation points of the refrigerant introduced in steps S1, S3, and S5 described later and the exhaust gas are omitted.
　本実施の形態における液化水素の貯留方法の開始時点において、液化水素タンク１の内部空間１３は、常温で、空気、すなわち、酸素、窒素および水蒸気等が存在している。また、事前に、内部空間１３の露点温度が所定値になるように、内部空間１３の圧力が調整される。 At the start of the method for storing liquefied hydrogen in the present embodiment, the internal space 13 of the liquefied hydrogen tank 1 contains air, that is, oxygen, nitrogen, water vapor, etc. at room temperature. Moreover, the pressure of the internal space 13 is adjusted in advance so that the dew point temperature of the internal space 13 becomes a predetermined value.
　まず、窒素を用いて液化水素タンク１内の酸素を除去する酸素除去工程が行われる（ステップＳ１）。酸素除去工程においては、液化窒素導入部４から液化窒素ＬＮ２が導入されることにより、液化水素タンク１内の酸素Ｏ２および水分が除去される。制御器５は、第１開閉弁２４および第２開閉弁２７を閉弁した状態で、第３開閉弁３１を開弁し、液化窒素導入配管３０から液化水素タンク１の内部空間１３に液化窒素を導入する。 First, an oxygen removal step is performed to remove oxygen in the liquefied hydrogen tank 1 using nitrogen (step S1). In the oxygen removing step, the oxygen O 2 and moisture in the liquefied hydrogen tank 1 are removed by introducing the liquefied nitrogen LN 2 from the liquefied nitrogen inlet 4 . With the first on-off valve 24 and the second on-off valve 27 closed, the controller 5 opens the third on-off valve 31 to introduce liquefied nitrogen into the internal space 13 of the liquefied hydrogen tank 1 from the liquefied nitrogen introduction pipe 30 . to introduce
　酸素除去ステップにおいて液化窒素が導入されることにより、液化水素タンク１の内部空間１３を液化窒素で冷却しながら、液化水素タンク１の内部空間１３の酸素が除去される。内部空間１３の下部から導入された液化窒素および内部空間１３を冷却することにより気化した低温の窒素ガスは、内部空間１３内の残存空気、すなわち、常温の酸素および窒素より比重が大きいため、内部空間１３の底部から溜まっていき、残存空気を上方へ押し上げる。そのため、内部空間１３の上部に設けられた第１排出配管３２から残存空気が排出され、効率的な酸素除去が行われる。 By introducing liquefied nitrogen in the oxygen removing step, oxygen in the internal space 13 of the liquefied hydrogen tank 1 is removed while cooling the internal space 13 of the liquefied hydrogen tank 1 with liquefied nitrogen. The liquefied nitrogen introduced from the lower part of the internal space 13 and the low-temperature nitrogen gas vaporized by cooling the internal space 13 have a higher specific gravity than the residual air in the internal space 13, that is, normal temperature oxygen and nitrogen. It accumulates from the bottom of the space 13 and pushes the remaining air upwards. Therefore, residual air is discharged from the first discharge pipe 32 provided in the upper part of the internal space 13, and oxygen is efficiently removed.
　酸素の除去が完了した状態、すなわち、酸素濃度が所定の第１基準値未満となった状態で、内部空間１３は、導入された液化窒素がその内部空間１３との熱交換によって気化することによって生じた低温の窒素ガスＧＮ２雰囲気となる。この際、内部空間１３の温度は、窒素の沸点よりある程度高い第１予冷温度となる。例えば第１予冷温度は、約－１８０℃である。 When the removal of oxygen has been completed, that is, when the oxygen concentration is less than the predetermined first reference value, the internal space 13 is filled with the introduced liquefied nitrogen through heat exchange with the internal space 13 to vaporize The resulting low-temperature nitrogen gas GN2 atmosphere. At this time, the temperature of the internal space 13 becomes the first precooling temperature which is somewhat higher than the boiling point of nitrogen. For example, the first precooling temperature is about -180°C.
　制御器５は、第１計測器３３で計測される酸素濃度が第１基準値未満となったかどうかを判定する（ステップＳ２）。第１基準値は、内部空間１３における酸素濃度が液化水素の燃焼条件よりも十分に低いときの値に設定される。なお、第１基準値を設定するための燃焼条件は、内部空間１３において予め設定された露点温度に応じて定められる。 The controller 5 determines whether the oxygen concentration measured by the first measuring device 33 is less than the first reference value (step S2). The first reference value is set to a value when the oxygen concentration in the internal space 13 is sufficiently lower than the liquefied hydrogen combustion conditions. The combustion condition for setting the first reference value is determined according to the dew point temperature preset in the internal space 13 .
　第１計測器３３で計測される酸素濃度が第１基準値未満となった場合（ステップＳ２でＹｅｓ）、次の工程に遷移する。次の工程は、液化水素タンク１の内部空間１３における低温の窒素ガスを除去する窒素除去工程である。窒素除去工程においては、液化水素ＬＨ２を気化させた低温水素ガスＧＨ２が低温ガス導入部３から液化水素タンク１内に導入されることにより、液化水素タンク１の内部空間１３の窒素ガスＧＮ２が除去される（ステップＳ３）。 When the oxygen concentration measured by the first measuring device 33 is less than the first reference value (Yes in step S2), the process proceeds to the next step. The next step is a nitrogen removal step for removing low-temperature nitrogen gas in the internal space 13 of the liquefied hydrogen tank 1 . In the nitrogen removal step, the low-temperature hydrogen gas GH 2 obtained by vaporizing the liquefied hydrogen LH 2 is introduced into the liquefied hydrogen tank 1 from the low-temperature gas introduction part 3, thereby reducing the nitrogen gas GN in the internal space 13 of the liquefied hydrogen tank 1. 2 is removed (step S3).
　制御器５は、酸素除去工程における状態から第３開閉弁３１を閉弁する一方、第２開閉弁２７を開弁し、低温ガス導入配管２６から液化水素タンク１の内部空間１３に低温水素ガスを導入する。気化器２５は、第１引込口２１から導入された液化水素ＬＨ２を気化し、所定温度の低温水素ガスＧＨ２として生成する。 The controller 5 closes the third on-off valve 31 from the state of the oxygen removal step, and opens the second on-off valve 27 to introduce the low-temperature hydrogen gas from the low-temperature gas introduction pipe 26 into the internal space 13 of the liquefied hydrogen tank 1. to introduce The vaporizer 25 vaporizes the liquefied hydrogen LH 2 introduced from the first intake port 21 to generate low-temperature hydrogen gas GH 2 at a predetermined temperature.
　低温水素ガスの温度は、酸素除去工程終了時の温度を含む所定範囲内の温度である。例えば、酸素除去工程終了時の温度が－１８０℃である場合、低温水素ガスの温度は、－１８０±１０℃に設定される。これにより、酸素除去時の温度とその後の窒素除去時の温度との差が小さくなるため、液化水素タンク１内の冷却状態を維持しつつ窒素の液化または固化を防止することができる。 The temperature of the low-temperature hydrogen gas is within a predetermined range including the temperature at the end of the oxygen removal process. For example, if the temperature at the end of the oxygen removal step is -180°C, the temperature of the cold hydrogen gas is set to -180±10°C. As a result, the difference between the temperature at the time of oxygen removal and the temperature at the time of subsequent nitrogen removal is reduced, so that the liquefied or solidified nitrogen can be prevented while maintaining the cooling state inside the liquefied hydrogen tank 1 .
　低温水素ガスは、内部空間１３の上部に設けられた第１吐出口２２から噴霧される。内部空間１３の上部から導入された低温水素ガスＧＨ２は、内部空間１３内の残存窒素ＧＮ２より比重が小さいため、内部空間１３の上部に溜まっていき、残存窒素を下方へ押し下げる。そのため、内部空間１３の下部に設けられた第２排出配管３４から残存窒素が排出され、効率的な窒素除去が行われる。 Low-temperature hydrogen gas is sprayed from a first outlet 22 provided in the upper portion of the internal space 13 . Since the low-temperature hydrogen gas GH2 introduced from the upper part of the internal space 13 has a lower specific gravity than the residual nitrogen GN2 in the internal space 13, it accumulates in the upper part of the internal space 13 and pushes the residual nitrogen downward. Therefore, residual nitrogen is discharged from the second discharge pipe 34 provided in the lower part of the internal space 13, and efficient nitrogen removal is performed.
　窒素の除去が完了した状態、すなわち、水素濃度が所定の第２基準値より高くなった状態で、内部空間１３は、その内部空間１３に導入された低温水素ガスＧＨ２雰囲気となる。この際、内部空間１３の温度は、低温水素ガスの導入温度と同等あるいはこれよりある程度高い第２予冷温度となる。第２予冷温度は、例えば約－１８０℃～－１６０℃である。 In the state in which the removal of nitrogen is completed, that is, the state in which the hydrogen concentration is higher than the predetermined second reference value, the internal space 13 becomes the atmosphere of the low-temperature hydrogen gas GH 2 introduced into the internal space 13 . At this time, the temperature of the internal space 13 becomes the second precooling temperature equal to or somewhat higher than the introduction temperature of the low-temperature hydrogen gas. The second precooling temperature is, for example, about -180°C to -160°C.
　制御器５は、第２計測器３５で計測される水素濃度が第２基準値より高くなったかどうかを判定する（ステップＳ４）。第２基準値は、内部空間１３における窒素濃度が十分に低いときの値に設定される。 The controller 5 determines whether the hydrogen concentration measured by the second measuring device 35 has become higher than the second reference value (step S4). The second reference value is set to a value when the nitrogen concentration in the internal space 13 is sufficiently low.
　第２計測器３５で計測される水素濃度が第２基準値より高くなった場合（ステップＳ４でＹｅｓ）、次の工程に遷移する。次の工程は、酸素および窒素が除去された液化水素タンク１の内部空間１３に液化水素ＬＨ２を導入する液化水素導入工程である。液化水素導入工程においては、液化水素ＬＨ２が液化水素導入部２から液化水素タンク１内に導入されることにより、液化水素タンク１の内部空間１３の低温水素ガスＧＨ２を除去しつつ、内部空間１３に液化水素が貯留される（ステップＳ５）。 When the hydrogen concentration measured by the second measuring device 35 is higher than the second reference value (Yes in step S4), the process proceeds to the next step. The next step is the liquefied hydrogen introduction step of introducing the liquefied hydrogen LH2 into the internal space 13 of the liquefied hydrogen tank 1 from which oxygen and nitrogen have been removed. In the liquefied hydrogen introduction step, the liquefied hydrogen LH 2 is introduced into the liquefied hydrogen tank 1 from the liquefied hydrogen introduction part 2, thereby removing the low-temperature hydrogen gas GH 2 in the internal space 13 of the liquefied hydrogen tank 1, and Liquefied hydrogen is stored in the space 13 (step S5).
　制御器５は、窒素除去工程における状態から第２開閉弁２７を閉弁する一方、第１開閉弁２４を開弁し、液化水素導入配管２３から液化水素タンク１の内部空間１３に液化水素ＬＨ２を導入する。 The controller 5 closes the second on-off valve 27 from the state of the nitrogen removal process, and opens the first on-off valve 24 to introduce the liquefied hydrogen LH into the internal space 13 of the liquefied hydrogen tank 1 from the liquefied hydrogen introduction pipe 23 . 2 .
　液化水素は、内部空間１３の上部に設けられた第１吐出口２２から噴霧される。内部空間１３の上部から導入された液化水素ＬＨ２は、内部空間１３内を、液化水素が貯留可能な温度近傍の液化水素貯留温度までさらに冷却する。液化水素が貯留可能な温度は、液化水素の沸点の温度、すなわち、－２５２．６℃である。前工程の残存ガスである低温水素ガスＧＨ２は、第３排出配管３６から排出される。 Liquefied hydrogen is sprayed from the first outlet 22 provided in the upper part of the internal space 13 . The liquefied hydrogen LH 2 introduced from the upper portion of the internal space 13 further cools the inside of the internal space 13 to a liquefied hydrogen storage temperature near the temperature at which liquefied hydrogen can be stored. The temperature at which liquefied hydrogen can be stored is the temperature of the boiling point of liquefied hydrogen, that is, -252.6°C. The low-temperature hydrogen gas GH 2 , which is the residual gas from the previous process, is discharged from the third discharge pipe 36 .
　内部空間１３が、液化水素が貯留可能な温度近傍まで冷却されることにより、液化水素が気化することなく内部空間１３内に貯留される。 By cooling the internal space 13 to a temperature close to the temperature at which liquefied hydrogen can be stored, the liquefied hydrogen is stored in the internal space 13 without being vaporized.
　上記方法によれば、液化水素タンク１に液化水素を導入する前に、液化水素タンク１内が予め冷却される。このため、液化水素タンク１に液化水素を導入する際、液化水素タンク１を冷却するために消費される液化水素の量が低減する。したがって、液化水素タンク１内を液化水素が貯留される温度まで冷却する際に、液化水素が気化により消費される量を低減することができる。また、上記方法によれば、液化水素タンク１内が段階的に冷却されるため、液化水素タンク１の局部的な熱収縮をより生じ難くさせることができる。 According to the above method, before the liquefied hydrogen is introduced into the liquefied hydrogen tank 1, the inside of the liquefied hydrogen tank 1 is pre-cooled. Therefore, when introducing liquefied hydrogen into the liquefied hydrogen tank 1, the amount of liquefied hydrogen consumed for cooling the liquefied hydrogen tank 1 is reduced. Therefore, when cooling the inside of the liquefied hydrogen tank 1 to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced. In addition, according to the above method, the inside of the liquefied hydrogen tank 1 is cooled step by step, so that localized thermal shrinkage of the liquefied hydrogen tank 1 can be made more difficult to occur.
　また、上記方法によれば、酸素除去工程において、液化窒素により液化水素タンク１内が予め冷却されるため、液化水素を導入する際に、液化水素が気化により消費されることが抑制される。液化水素タンク１内を、常温から液化窒素の沸点に近い第１予冷温度まで冷却するために、液化窒素を用いることで、常温から第１予冷温度までの冷却に液化水素または低温水素ガスを用いる場合に比べて、冷媒の製造コストを含む冷却効率をより高くすることができる。 In addition, according to the above method, the inside of the liquefied hydrogen tank 1 is pre-cooled with liquefied nitrogen in the oxygen removal step, so consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced. By using liquefied nitrogen to cool the inside of the liquefied hydrogen tank 1 from normal temperature to the first precooling temperature close to the boiling point of liquefied nitrogen, liquefied hydrogen or low-temperature hydrogen gas is used for cooling from normal temperature to the first precooling temperature. Compared to the case, the cooling efficiency including the manufacturing cost of the refrigerant can be made higher.
　さらに、上記方法によれば、酸素除去工程において液化窒素が導入された後、さらに、酸素除去の際に気化した窒素が低温水素ガスで除去される。液化水素を導入する前に、液化水素を気化させた低温水素ガスを導入するため、低温水素ガスによる冷却後、液化水素タンク１内の冷却剤を別途除去する工程は不要となる。また、低温水素ガスを導入することにより、酸素除去工程で酸素を除去するために用いられる窒素を低温水素ガスにより除去することができる。これにより、窒素の除去に液化水素を使用する必要がなくなるため、液化水素の消費を抑えることができる。 Furthermore, according to the above method, after the liquefied nitrogen is introduced in the oxygen removal step, the nitrogen vaporized during the oxygen removal is further removed with low-temperature hydrogen gas. Since the low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen is introduced before the liquefied hydrogen is introduced, the process of separately removing the coolant in the liquefied hydrogen tank 1 after cooling with the low-temperature hydrogen gas is not required. Also, by introducing the low-temperature hydrogen gas, the nitrogen used for removing oxygen in the oxygen removal step can be removed by the low-temperature hydrogen gas. This eliminates the need to use liquefied hydrogen to remove nitrogen, thereby reducing the consumption of liquefied hydrogen.
　さらに、従来のように、液化水素タンク１内の酸素を除去するために常温の窒素を導入し、その後、液化水素を導入して窒素を除去する場合では、液化水素タンク１内に充満している窒素の一部が急速に冷却されて窒素が局部的に固化または液化する恐れがある。窒素が液化水素タンク１内で固化または液化すると、固化または液化した窒素が生じた箇所で液化水素タンク１の局部的な熱収縮が生じ易くなる。これに対し、上記方法によれば、液化水素タンク１内の酸素を除去するために液体窒素を導入するため、低温水素ガスが導入される段階の液化水素タンク１内には低温の窒素ガスが充満していることになる。このため、低温水素ガスの導入による窒素の急冷を抑制し、窒素が局部的に固化または液化することを防止することができる。 Furthermore, as in the conventional case, nitrogen at normal temperature is introduced to remove oxygen in the liquefied hydrogen tank 1, and then liquefied hydrogen is introduced to remove nitrogen. Some of the nitrogen in the tank may cool rapidly causing the nitrogen to locally solidify or liquefy. When nitrogen solidifies or liquefies in the liquefied hydrogen tank 1, local thermal contraction of the liquefied hydrogen tank 1 tends to occur at the location where the solidified or liquefied nitrogen occurs. On the other hand, according to the above method, since liquid nitrogen is introduced to remove oxygen in the liquefied hydrogen tank 1, low-temperature nitrogen gas is present in the liquefied hydrogen tank 1 at the stage where the low-temperature hydrogen gas is introduced. It means that it is full. Therefore, rapid cooling of nitrogen caused by the introduction of low-temperature hydrogen gas can be suppressed, and local solidification or liquefaction of nitrogen can be prevented.
　従来方法のように、液化水素ＬＨ２を用いて液化水素タンク１の内部空間１３を常温の状態から冷却する場合、液化水素貯留温度まで冷却するのに必要な液化水素量は、内部空間１３の容積が大きくなるほど増大する。一方、本実施の形態によれば、液化水素貯留温度まで冷却するのに必要な液化水素量は、例えば従来方法の１／５程度に抑えられると考えられる。 When the internal space 13 of the liquefied hydrogen tank 1 is cooled from the normal temperature state using the liquefied hydrogen LH 2 as in the conventional method, the amount of liquefied hydrogen required to cool the internal space 13 to the liquefied hydrogen storage temperature is It increases as the volume increases. On the other hand, according to the present embodiment, the amount of liquefied hydrogen required for cooling to the liquefied hydrogen storage temperature can be suppressed to, for example, about 1/5 of that in the conventional method.
　なお、本実施の形態においては、窒素の必要量が従来方法に対して増大するが、液化水素ＬＨ２の製造コストおよび維持管理コストに比べれば、窒素、特に液化窒素の導入コストの方が低く、システム全体として低コスト化を実現することができる。 In the present embodiment, the required amount of nitrogen increases compared to the conventional method, but compared to the production cost and maintenance cost of liquefied hydrogen LH2 , the introduction cost of nitrogen, especially liquefied nitrogen, is lower. , it is possible to reduce the cost of the entire system.
　また、液化水素タンク１が大型化すればするほど、従来方法では液化水素ＧＨ２の大気放出量が増大し、無視できなくなる。また、液化水素タンク１が大型化すればするほど、従来方法では上述した窒素の固化または液化の問題が顕在化する。これに対し、本実施の形態における導入態様であれば、液化水素タンク１が大型化しても、水素の大気放出量の増大を有効に抑制することができ、また、窒素の固化または液化を防止することができる。したがって、液化水素タンク１を大型化しても、液化水素の消費量の増大を抑制し、かつ、液化水素タンク１内を適切に冷却することができる。 Further, as the liquefied hydrogen tank 1 becomes larger, the amount of liquefied hydrogen GH 2 released into the atmosphere increases in the conventional method, and cannot be ignored. In addition, as the liquefied hydrogen tank 1 becomes larger, the problem of solidification or liquefaction of nitrogen described above becomes apparent in the conventional method. On the other hand, with the introduction mode of the present embodiment, even if the liquefied hydrogen tank 1 is increased in size, it is possible to effectively suppress the increase in the amount of hydrogen released into the atmosphere, and to prevent the solidification or liquefaction of nitrogen. can do. Therefore, even if the size of the liquefied hydrogen tank 1 is increased, an increase in consumption of liquefied hydrogen can be suppressed and the inside of the liquefied hydrogen tank 1 can be cooled appropriately.
　以上、本開示の実施の形態について説明したが、本開示は上記実施の形態に限定されるものではなく、その趣旨を逸脱しない範囲内で種々の改良、変更、修正が可能である。 Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above embodiments, and various improvements, changes, and modifications are possible without departing from the scope of the present disclosure.
　例えば、上記実施の形態においては、液化窒素導入配管３０、第２排出配管３４および第３排出配管３６がそれぞれ別に設けられているが、これらのうちの少なくとも何れか２つを、共通化してもよい。 For example, in the above embodiment, the liquefied nitrogen introduction pipe 30, the second discharge pipe 34, and the third discharge pipe 36 are provided separately, but at least any two of them may be shared. good.
　また、上記実施の形態においては、窒素除去工程で導入される低温水素ガスＧＨ２を、液化水素ＬＨ２を気化器２５で気化して生成しているが、これに限られない。例えば、別の設備等において液化水素を冷媒として使用する場合、その設備において液化水素と冷却対象との熱交換によって生じた低温水素ガスを、低温ガス導入配管２６から液化水素タンク１の内部空間１３に導入してもよい。 Further, in the above embodiment, the low-temperature hydrogen gas GH2 introduced in the nitrogen removal step is generated by vaporizing the liquefied hydrogen LH2 in the vaporizer 25, but the present invention is not limited to this. For example, when liquefied hydrogen is used as a refrigerant in another facility or the like, low-temperature hydrogen gas generated by heat exchange between liquefied hydrogen and an object to be cooled in that facility is introduced into the internal space 13 of the liquefied hydrogen tank 1 from the low-temperature gas introduction pipe 26. may be introduced into
　また、上記実施の形態においては、酸素濃度を計測する第１計測器３３が第１排出配管３２内に設けられているが、第１計測器３３は、内部空間１３内に設けられてもよい。同様に、上記実施の形態においては、水素ガス濃度を計測する第２計測器３５が第２排出配管３４内に設けられているが、第２計測器３５は、内部空間１３内に設けられてもよい。 Further, in the above embodiment, the first measuring device 33 for measuring the oxygen concentration is provided inside the first discharge pipe 32, but the first measuring device 33 may be provided inside the internal space 13. . Similarly, in the above embodiment, the second measuring device 35 for measuring the hydrogen gas concentration is provided inside the second discharge pipe 34, but the second measuring device 35 is provided inside the internal space 13. good too.
　また、上記実施の形態においては、酸素除去工程において、液化窒素ＬＮ２を導入すること、および、窒素除去工程において、液化水素導入工程の前に、低温水素ガスＧＨ２を導入することの両方を実施している態様を例示したが、液化窒素の導入または低温水素ガスの導入の何れか一方のみを実施してもよい。 Further, in the above embodiment, both introducing the liquefied nitrogen LN 2 in the oxygen removing step and introducing the low-temperature hydrogen gas GH 2 before the liquefied hydrogen introducing step in the nitrogen removing step are performed. Although the implementation mode has been exemplified, only one of the introduction of liquefied nitrogen and the introduction of low-temperature hydrogen gas may be implemented.
　また、上記実施の形態においては、球状の液化水素タンク１を例示したが、液化水素タンク１の形状は、円筒状、角型状等、特に限定されない。また、液化水素タンク１のタイプも、例えば、メンブレン方式、自立球方式等、特に限定されない。 Also, in the above embodiment, the spherical liquefied hydrogen tank 1 was exemplified, but the shape of the liquefied hydrogen tank 1 is not particularly limited, and may be cylindrical, square, or the like. Also, the type of the liquefied hydrogen tank 1 is not particularly limited, and may be, for example, a membrane system, a self-supporting sphere system, or the like.
　［本開示のまとめ］
　本発明の一形態に係る液化水素貯留方法は、液化水素タンクに液化水素を貯留するための液化水素貯留方法であって、窒素を用いて前記液化水素タンク内の酸素を除去し、酸素が除去された前記液化水素タンクに前記液化水素を導入し、前記液化水素タンクに前記液化水素を導入する前に、前記液化水素タンク内を予め冷却する。 [Summary of this disclosure]
A liquefied hydrogen storage method according to one aspect of the present invention is a liquefied hydrogen storage method for storing liquefied hydrogen in a liquefied hydrogen tank, wherein nitrogen is used to remove oxygen in the liquefied hydrogen tank, and the oxygen is removed. The liquefied hydrogen is introduced into the liquefied hydrogen tank, and the inside of the liquefied hydrogen tank is pre-cooled before introducing the liquefied hydrogen into the liquefied hydrogen tank.
　上記方法によれば、液化水素タンクに液化水素を導入する前に液化水素タンク内が予め冷却される。このため、液化水素タンクに液化水素を導入する際、液化水素タンクを冷却するために消費される液化水素の量が低減する。したがって、液化水素タンク内を液化水素が貯留される温度まで冷却する際に、液化水素が気化により消費される量を低減することができる。 According to the above method, the inside of the liquefied hydrogen tank is pre-cooled before the liquefied hydrogen is introduced into the liquefied hydrogen tank. Therefore, when introducing liquefied hydrogen into the liquefied hydrogen tank, the amount of liquefied hydrogen consumed for cooling the liquefied hydrogen tank is reduced. Therefore, when cooling the inside of the liquefied hydrogen tank to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced.
　前記液化水素を導入する前に、前記液化水素を気化させた低温水素ガスを導入してもよい。これによれば、液化窒素が導入された後、さらに、酸素除去の際に気化した窒素が低温水素ガスで除去される。液化水素を導入する前に、液化水素を気化させた低温水素ガスを導入するため、低温水素ガスによる冷却後、液化水素タンク内の冷媒を別途除去する工程は不要となる。また、低温水素ガスを導入することにより、酸素を除去するために用いられる窒素を低温水素ガスにより除去することができる。これにより、窒素の除去に液化水素を使用する必要がなくなるため、液化水素の消費を抑えることができる。 A low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen may be introduced before the liquefied hydrogen is introduced. According to this, after the liquefied nitrogen is introduced, the nitrogen vaporized during oxygen removal is further removed with the low-temperature hydrogen gas. Since the low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen is introduced before the liquefied hydrogen is introduced, there is no need to separately remove the refrigerant in the liquefied hydrogen tank after cooling with the low-temperature hydrogen gas. Also, by introducing the low-temperature hydrogen gas, the nitrogen used for removing oxygen can be removed by the low-temperature hydrogen gas. Since this eliminates the need to use liquefied hydrogen for removing nitrogen, the consumption of liquefied hydrogen can be suppressed.
　液化窒素を導入して前記液化水素タンク内の酸素を除去してもよい。これによれば、液化窒素により液化水素タンク内が予め冷却されるため、液化水素を導入する際に、液化水素が気化により消費されることが抑制される。液化水素タンク内を、常温から液化窒素の沸点に近い温度まで冷却するために、液化窒素を用いることで、常温から当該温度までの冷却に液化水素または低温水素ガスを用いる場合に比べて、冷媒の製造コストを含む冷却効率をより高くすることができる。 The oxygen in the liquefied hydrogen tank may be removed by introducing liquefied nitrogen. According to this, since the inside of the liquefied hydrogen tank is pre-cooled by the liquefied nitrogen, consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced. By using liquefied nitrogen to cool the inside of the liquefied hydrogen tank from room temperature to a temperature close to the boiling point of liquefied nitrogen, compared to using liquefied hydrogen or low-temperature hydrogen gas for cooling from room temperature to the temperature, refrigerant The cooling efficiency including the manufacturing cost of can be made higher.
　前記液化水素を導入する前に、前記液化水素を気化させた低温水素ガスを導入することにより、前記液化水素タンク内の窒素を除去してもよい。これによれば、液化水素タンク内の酸素を除去するために液体窒素を導入するため、低温水素ガスが導入される段階の液化水素タンク内には低温の窒素ガスが充満していることになる。このため、低温水素ガスの導入による窒素の急冷を抑制し、窒素が局部的に固化または液化することを防止することができる。 Before introducing the liquefied hydrogen, nitrogen in the liquefied hydrogen tank may be removed by introducing low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen. According to this, since liquid nitrogen is introduced to remove oxygen in the liquefied hydrogen tank, the liquefied hydrogen tank is filled with low temperature nitrogen gas at the stage where the low temperature hydrogen gas is introduced. . Therefore, rapid cooling of nitrogen caused by the introduction of low-temperature hydrogen gas can be suppressed, and local solidification or liquefaction of nitrogen can be prevented.
　前記低温水素ガスの温度は、前記酸素の除去の終了時の温度を含む所定範囲内の温度であってもよい。 The temperature of the low-temperature hydrogen gas may be a temperature within a predetermined range including the temperature at the end of the removal of oxygen.
　前記液化窒素は、前記液化水素タンクの下部から導入してもよい。これによれば、液化水素タンクの下部から導入された液化窒素および液化水素タンクの内部を冷却することにより気化した低温の窒素ガスは、液化水素タンク内の残存空気、すなわち、常温の酸素および窒素より比重が大きいため、液化水素タンクの底部から溜まっていき、残存空気を上方へ押し上げる。そのため、液化水素タンクの上部から残存空気を排出することにより、効率的な酸素除去を行うことができる。 The liquefied nitrogen may be introduced from the bottom of the liquefied hydrogen tank. According to this, the liquefied nitrogen introduced from the lower part of the liquefied hydrogen tank and the low-temperature nitrogen gas vaporized by cooling the inside of the liquefied hydrogen tank are mixed with the remaining air in the liquefied hydrogen tank, that is, normal temperature oxygen and nitrogen. Since it has a higher specific gravity, it accumulates from the bottom of the liquefied hydrogen tank and pushes the remaining air upwards. Therefore, by discharging residual air from the upper portion of the liquefied hydrogen tank, oxygen can be removed efficiently.
　本発明の他の態様に係る液化水素貯留システムは、液化水素タンクに液化水素を貯留するための液化水素貯留システムであって、前記液化水素タンク内の酸素を除去するために前記液化水素タンク内に液化窒素を導入する液化窒素導入配管と、前記液化水素タンク内に導入された前記液化窒素を除去するために前記液化水素タンク内に前記液化水素を気化させた低温水素ガスを導入する低温ガス導入配管と、前記液化水素を導入する液化水素導入配管と、を備えている。 A liquefied hydrogen storage system according to another aspect of the present invention is a liquefied hydrogen storage system for storing liquefied hydrogen in a liquefied hydrogen tank, comprising: a liquefied nitrogen introduction pipe for introducing liquefied nitrogen into the liquefied hydrogen tank; An introduction pipe and a liquefied hydrogen introduction pipe for introducing the liquefied hydrogen are provided.
　上記構成によれば、液化水素タンク内の酸素を除去するために液化窒素が導入されることにより、液化水素タンク内を液化窒素で冷却しながら、液化水素タンク内の酸素が除去される。したがって、液化水素を導入する前に、液化水素タンク内が予め冷却されるため、液化水素を導入する際に、液化水素が気化により消費されることが抑制される。さらに、液化窒素を導入することにより酸素が除去された後、液化水素を導入する前に、酸素除去の際に気化した窒素が、低温水素ガスで除去される。これにより、窒素の除去に液化水素を使用する必要がなくなるため、液化水素の消費を抑えることができる。したがって、液化水素タンク内を液化水素が貯留される温度まで冷却する際に、液化水素が気化により消費される量を低減することができる。 According to the above configuration, the liquefied nitrogen is introduced to remove the oxygen in the liquefied hydrogen tank, thereby removing the oxygen in the liquefied hydrogen tank while cooling the inside of the liquefied hydrogen tank with the liquefied nitrogen. Therefore, since the inside of the liquefied hydrogen tank is pre-cooled before the liquefied hydrogen is introduced, consumption of the liquefied hydrogen by vaporization is suppressed when the liquefied hydrogen is introduced. Further, after oxygen is removed by introducing liquefied nitrogen, and before introducing liquefied hydrogen, the nitrogen vaporized during oxygen removal is removed with low temperature hydrogen gas. Since this eliminates the need to use liquefied hydrogen for removing nitrogen, the consumption of liquefied hydrogen can be suppressed. Therefore, when cooling the inside of the liquefied hydrogen tank to a temperature at which liquefied hydrogen is stored, the amount of liquefied hydrogen consumed by vaporization can be reduced.
１　液化水素タンク
２３　液化水素導入配管
２６　低温ガス導入配管
３０　液化窒素導入配管
１００　液化水素貯留システム 1 liquefied hydrogen tank 23 liquefied hydrogen introduction pipe 26 low temperature gas introduction pipe 30 liquefied nitrogen introduction pipe 100 liquefied hydrogen storage system

Claims (7)

  1. 　液化水素タンクに液化水素を貯留するための液化水素貯留方法であって、
    　窒素を用いて前記液化水素タンク内の酸素を除去し、
    　酸素が除去された前記液化水素タンクに前記液化水素を導入し、
    　前記液化水素タンクに前記液化水素を導入する前に、前記液化水素タンク内を予め冷却する、液化水素貯留方法。     A liquefied hydrogen storage method for storing liquefied hydrogen in a liquefied hydrogen tank,
    removing oxygen in the liquefied hydrogen tank using nitrogen;
    introducing the liquefied hydrogen into the liquefied hydrogen tank from which oxygen has been removed;
    A method of storing liquefied hydrogen, comprising pre-cooling the inside of the liquefied hydrogen tank before introducing the liquefied hydrogen into the liquefied hydrogen tank.
  2. 　前記液化水素を導入する前に、前記液化水素を気化させた低温水素ガスを導入する、請求項１に記載の液化水素貯留方法。 The liquefied hydrogen storage method according to claim 1, wherein low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen is introduced before introducing the liquefied hydrogen.
  3. 　液化窒素を導入して前記液化水素タンク内の酸素を除去する、請求項１に記載の液化水素貯留方法。 The liquefied hydrogen storage method according to claim 1, wherein liquefied nitrogen is introduced to remove oxygen in the liquefied hydrogen tank.
  4. 　前記液化水素を導入する前に、前記液化水素を気化させた低温水素ガスを導入することにより、前記液化水素タンク内の窒素を除去する、請求項３に記載の液化水素貯留方法。 The liquefied hydrogen storage method according to claim 3, wherein nitrogen in the liquefied hydrogen tank is removed by introducing low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen before introducing the liquefied hydrogen.
  5. 　前記低温水素ガスの温度は、前記酸素の除去の終了時の温度を含む所定範囲内の温度である、請求項４に記載の液化水素貯留方法。 The liquefied hydrogen storage method according to claim 4, wherein the temperature of said low-temperature hydrogen gas is within a predetermined range including the temperature at the end of said oxygen removal.
  6. 　前記液化窒素は、前記液化水素タンクの下部から導入する、請求項３から５の何れかに記載の液化水素貯留方法。 The liquefied hydrogen storage method according to any one of claims 3 to 5, wherein the liquefied nitrogen is introduced from the bottom of the liquefied hydrogen tank.
  7. 　液化水素タンクに液化水素を貯留するための液化水素貯留システムであって、
    　前記液化水素タンク内の酸素を除去するために前記液化水素タンク内に液化窒素を導入する液化窒素導入配管と、
    　前記液化水素タンク内に導入された前記液化窒素を除去するために前記液化水素タンク内に前記液化水素を気化させた低温水素ガスを導入する低温ガス導入配管と、
    　前記液化水素を導入する液化水素導入配管と、を備えた、液化水素貯留システム。     A liquefied hydrogen storage system for storing liquefied hydrogen in a liquefied hydrogen tank,
    A liquefied nitrogen introduction pipe for introducing liquefied nitrogen into the liquefied hydrogen tank to remove oxygen in the liquefied hydrogen tank;
    a low-temperature gas introduction pipe for introducing low-temperature hydrogen gas obtained by vaporizing the liquefied hydrogen into the liquefied hydrogen tank in order to remove the liquefied nitrogen introduced into the liquefied hydrogen tank;
    and a liquefied hydrogen introduction pipe for introducing the liquefied hydrogen.
PCT/JP2021/040788 2021-11-05 2021-11-05 Liquefied hydrogen storage method and liquefied hydrogen storage system WO2023079683A1 (en)

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