Ships and liquefied hydrogen tanks

Abstract

To suppress condensation of oxygen on a surface of an outer tank, in a liquefied hydrogen tank that does not have a vacuum insulating structure between the outer tank and an inner tank.SOLUTION: A liquefied hydrogen tank comprises an inner tank storing liquefied hydrogen, an outer tank surrounding the inner tank, an outer shell surrounding the outer tank, a first heat insulating layer arranged in a first region between the inner tank and the outer tank, and a second insulating layer arranged in a second region between the outer tank and the outer shell. The first region is substantially atmospheric pressure or low vacuum filled with first gas that is hydrogen gas or helium gas, and the second region is filled with second gas containing at least one of inert gas and dry air. With the liquefied hydrogen stored in the inner tank, a temperature of the outer tank is a predetermined outer tank control temperature that is higher than a condensation point of oxygen and equal to or lower than the atmospheric temperature.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a liquefied hydrogen tank and a ship equipped with the liquefied hydrogen tank. [Background technology]

[0002] Liquefied hydrogen tanks with vacuum insulation structures have been known for some time. For example, the liquefied gas holding tank disclosed in Patent Document 1 comprises an inner vessel for storing cryogenic liquefied gas such as liquefied hydrogen, an outer vessel covering the inner vessel, a vacuum region insulation layer between the inner vessel and the outer vessel, and an emergency insulation layer covering the outer surface of the outer vessel, and a high vacuum is created between the inner vessel and the outer vessel. The high vacuum is generally 10 -1 Pa to 10 -5 It refers to atmospheric pressure up to Pa. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-194166 Summary of the Invention [Problem to be solved by the invention]

[0004] The liquefied gas holding tank of Patent Document 1 has a high vacuum between the inner and outer vessels, and a vacuum insulation layer between the inner and outer vessels. This suppresses heat convection, radiation, and conduction between the inner and outer vessels, providing high thermal insulation performance. However, it takes time to evacuate the large volume of the vessels, which can be one of the factors that lengthen the time required for manufacturing and maintenance. Furthermore, the vessel walls must be thick enough to be vacuum-resistant, which can be one of the factors that increase the tank weight.

[0005] On the other hand, if the tank does not have a vacuum insulation structure, the thermal insulation performance between the inner and outer vessels will be poor, and the surface temperature of the outer vessel may constantly become extremely low. If the surface temperature of the outer vessel becomes extremely low, there is a risk that oxygen will condense and liquefy on the surface of the outer vessel.

[0006] The present disclosure has been made in consideration of the above circumstances, and its purpose is to tank The present invention aims to suppress condensation of oxygen on the surface of an outer tank in a liquefied hydrogen tank that does not have a vacuum insulation structure therebetween. [Means for solving the problem]

[0007] A liquefied hydrogen tank according to one aspect of the present disclosure includes: an inner tank that contains liquefied hydrogen; an outer tank surrounding the inner tank; an outer shell surrounding the outer vessel; a first insulating layer disposed in a first region between the inner vessel and the outer vessel; a second insulating layer disposed in a second region between the outer vessel and the outer shell; the first region is filled with a first gas, which is hydrogen gas or helium gas, and is at substantially atmospheric pressure or low vacuum; the second region is filled with a second gas containing at least one of an inert gas and dry air; When the temperature of the outer vessel is higher than the condensation point of oxygen, liquefied hydrogen is stored in the inner vessel. stomach It is characterized by the following.

[0008] A ship according to one aspect of the present disclosure is equipped with the above-described liquefied hydrogen tank. [Effects of the Invention]

[0009] According to the present disclosure, the inner tank and the outer tank tank In a liquefied hydrogen tank that does not have a vacuum insulation structure between the outer tank and the tank, condensation of oxygen on the surface of the outer tank can be suppressed. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a ship equipped with a liquefied hydrogen tank according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a diagram showing a cross section of a ship. [Figure 3] FIG. 3 shows the temperature distribution on the wall of a liquefied hydrogen tank. [Figure 4] FIG. 4 is a block diagram showing the configuration of an inspection device for the temperature of the outer tank of a liquefied hydrogen tank. DETAILED DESCRIPTION OF THE INVENTION

[0011] FIG. 1 is a schematic configuration diagram of a ship 1 equipped with a liquefied hydrogen tank 3 according to one embodiment of the present disclosure. The ship 1 shown in FIG. 1 comprises a hull 2 ​​and four liquefied hydrogen tanks 3 mounted on the hull 2. The liquefied hydrogen tanks 3 are cargo tanks for transporting liquefied hydrogen. In this embodiment, the liquefied hydrogen tanks 3 are aligned along the length of the ship, but may also be aligned along the width of the ship if the ship is wide. Furthermore, the number of liquefied hydrogen tanks 3 mounted on the hull 2 ​​may be one, or two or more.

[0012] In this embodiment, the four liquefied hydrogen tanks 3 have substantially the same structure. In this embodiment, the liquefied hydrogen tanks 3 are configured as multi-layer tanks. However, if the ship 1 is equipped with multiple liquefied hydrogen tanks 3, the multiple liquefied hydrogen tanks 3 may each have a different structure.

[0013] As shown in Figure 2, the liquefied hydrogen tank 3 comprises an inner tank 4 in which liquefied hydrogen is stored, an outer tank 5 surrounding the inner tank 4, and an outer shell 6 surrounding the outer tank 5. The inner tank 4 and the outer tank 5 are spaced apart in the thickness direction of the tank. The space between the inner tank 4 and the outer tank 5 is referred to as a "first region 31." The outer tank 5 and the outer shell 6 are spaced apart in the thickness direction of the tank. The space between the outer tank 5 and the outer shell 6 is referred to as a "second region 32."

[0014] The first region 31 is filled with a first gas and is substantially at atmospheric pressure or in a low vacuum state. The first gas is hydrogen gas or helium gas. Atmospheric pressure is approximately 10 5 However, since the pressure in the first region 31 may fluctuate due to temperature and the motion of the hull 2, the "substantially atmospheric pressure" in this specification and claims is defined as approximately 10 5 Pa and approximately 10 5Atmospheric pressures higher than Pa (e.g., 1.0 × 10 5 Pa higher than 1.5×10 5 The low vacuum state may include a pressure lower than atmospheric pressure, such as 10 Pa or less. 5 Pa to 10 2 The pressure in the range from 0 to 10 Pa. When the first gas is hydrogen gas, the gas phase of the inner tank 4 may be connected to the first zone 31 so that the vaporized gas generated in the inner tank 4 flows into the first zone 31. The second zone 32 is filled with the second gas and is substantially at atmospheric pressure. Although not particularly limited, the second zone 32 may be at a higher pressure than the first zone 31. The second gas includes at least one of an inert gas such as nitrogen and dry air. For example, the second zone 32 may be filled with dry air, and an inert gas may be held in the second insulating layer 62 described below.

[0015] The inner tank 4 includes a substantially spherical inner tank body 41. The inner tank 4 may be provided with an inner tank dome that protrudes upward from the inner tank body 41.

[0016] The outer tank 5 includes a substantially spherical outer tank body 51. The outer tank 5 may be provided with an outer tank dome that protrudes upward from the outer tank body 51. The outer tank body 51 surrounds the inner tank body 41. However, the inner tank body 41 and the outer tank body 51 do not necessarily have to be spherical, and may be cylindrical in shape elongated in the horizontal direction or vertical direction. Alternatively, the inner tank body 41 and the outer tank body 51 may be cubic or rectangular.

[0017] The hull 2 ​​has two cargo holds 21 that open upward. The two cargo holds 21 are lined up in the longitudinal direction of the ship and are separated by a wall 22. The lower parts of the inner tub 4 and the outer tub 5 are housed inside each cargo hold 21.

[0018] A pair of skirts 25 spaced apart in the longitudinal direction of the ship are provided inside each cargo hold 21. The skirts 25 support the outer tub 5. A pair of support members 35 supporting the inner tub body 41 are provided between the inner tub 4 and the outer tub 5. In this embodiment, the skirts 25 are arranged on the extension of the support members 35, but the arrangement of the support members 35 and the skirts 25 is not limited to this embodiment.

[0019] A tank cover 60 is disposed above the outer tub 5. The tank cover 60 covers the upper part of the corresponding outer tub 5. However, the upper part of the outer tub 5 may be covered by a component of the hull 2. In this embodiment, the outer hull 6 is composed of the tank cover 60 and a wall 22, which is a component of the hull 2 ​​that forms the cargo hold 21.

[0020] [Liquefied hydrogen tank 3 heat insulation structure] Here, we will explain the thermal insulation structure provided in the liquefied hydrogen tank 3 configured as described above. The liquefied hydrogen tank 3 has a first insulating layer 61 in the first region 31 between the inner vessel 4 and the outer vessel 5, and a second insulating layer 62 in the second region 32 between the outer vessel 5 and the outer shell 6.

[0021] In this embodiment, the first insulation layer 61 is composed of a sheet insulation material that covers the outer surface of the inner tank 4. The sheet insulation material is a film-, panel-, or sheet-shaped insulation material, and examples thereof include foamed urethane panels, foamed phenolic resin panels, aerogel sheets, and sheet-shaped glass wool. Particulate insulation material may be filled in the space in the first region 31 where no sheet insulation material is located. The insulating performance of the first insulation layer 61 can be adjusted by selecting the material of the sheet insulation material, changing the thickness of the sheet insulation material in the wall thickness direction, or adding particulate insulation material.

[0022] In this embodiment, the second insulation layer 62 is composed of a sheet insulation material that covers the outer surface of the outer tank 5. The insulation performance of the second insulation layer 62 can be adjusted by selecting the material of the sheet insulation material or by changing the thickness of the sheet insulation material in the wall thickness direction. Note that the configurations of the first insulation layer 61 and the second insulation layer 62 are not limited to this embodiment.

[0023] In the liquefied hydrogen tank 3 configured as described above, it is desirable to suppress condensation of the first gas on the outer surface of the inner tank 4 and the inner surface of the outer tank 5. For this reason, a first gas with a low condensation point, such as hydrogen gas or helium gas, is filled between the inner tank 4 and the outer tank 5. However, because hydrogen gas or helium gas has a significantly higher thermal conductivity than air or nitrogen, the thermal insulation performance of the insulating material is lower when the insulating material is placed in the first region 31 than when the insulating material is placed in the second region 32. In other words, under the condition that the total amount of insulating material placed in the first region 31 and the second region 32 is constant, the thermal insulation performance of the liquefied hydrogen tank 3 as a whole improves as the proportion of insulating material placed in the second region 32 increases. On the other hand, increasing the proportion of insulating material placed in the second region 32 to improve thermal insulation performance or reducing the amount of insulating material placed in the first region 31 from a cost-effectiveness perspective increases the temperature of the outer tank 5. If the temperature of the outer vessel 5 drops too low, the gas contained in the insulating material or the gas that has flowed in through the gaps in the insulating material will condense. If this gas contains oxygen, liquid oxygen will form on the surface of the outer vessel 5. Since a flammable high-concentration oxygen gas region exists around the generated liquid oxygen, condensation of oxygen gas on the surface of the outer vessel 5 is undesirable.

[0024] FIG. 3 is a schematic diagram of the temperature distribution in the wall thickness direction of the liquefied hydrogen tank 3 from the inner vessel 4 to the outer shell 6. The temperature of the inner vessel 4 is inner vessel temperature T4, the temperature of the inner surface of the first insulating layer 61 is T4, and the temperature of the outer surface of the first insulating layer 61 is T61. The temperature of the first insulating layer 61 transitions from T4 to T61 so that it becomes higher toward the outside. The temperature of the outer vessel 5 is outer vessel temperature T5, and T5 is the same as or higher than T61. Because the temperature difference between T5 and T61 is sufficiently small, T5 and T61 may be calculated to be substantially the same temperature. The inner surface of the second insulating layer 62 is in contact with the outer surface of the outer vessel 5 or faces it with a small gap. The temperature of the inner surface of the second insulating layer 62 is T5, and the temperature of the outer surface of the second insulating layer 62 is T62. The temperature of the second insulating layer 62 transitions from T5 to T62 so that it becomes higher toward the outside. The temperature of the outer shell 6 is the outer shell temperature T6, which is equal to or higher than T62. Since the temperature difference between T6 and T62 is sufficiently small, T6 and T61 may be considered to be substantially the same temperature in calculations.

[0025] The inner vessel temperature T4 is maintained at a temperature at which the liquefied hydrogen stored in the inner vessel 4 does not vaporize, i.e., below the boiling point of hydrogen. The normal boiling point of hydrogen is -253°C, and the boiling point of hydrogen varies depending on the internal pressure of the inner vessel 4. The outer vessel 6 is exposed, and the outer vessel temperature T6 is approximately equal to the ambient temperature. The ambient temperature used in the calculation may be approximately 27°C. To prevent oxygen present in the second region 32 from condensing on the surface of the outer vessel 5, it is desirable that the outer vessel temperature T5 be higher than the condensation point of oxygen. The temperature T61 of the outer surface of the first insulating layer 61 may also be higher than the condensation point of oxygen. Here, the condensation point of oxygen refers to the condensation point of oxygen under the pressure of the second region 32. The condensation point is the temperature at which a gas transitions to a liquid, and the condensation point and boiling point of oxygen are the same temperature. The condensation point of oxygen at atmospheric pressure, i.e., the normal condensation point, is -183°C. The temperature T62 of the outer surface of the second insulating layer 62 is desirably higher than the dew-point temperature of the moisture present in the second region 32 so that the moisture present in the second region 32 does not condense on the outer surface of the second insulating layer 62. The dew-point temperature varies depending on the humidity of the second region 32, etc.

[0026] The combination of the first insulating layer 61 and the second insulating layer 62 has the insulating performance to achieve the above-mentioned temperature distribution. Specifically, the combination of the first insulating layer 61 and the second insulating layer 62 has the insulating performance to maintain the temperature of the outer tank 5 at a predetermined outer tank control temperature when liquefied hydrogen is contained in the inner tank 4. Note that, since the temperature of the outer tank 5 steadily fluctuates due to changes in the liquid level of liquefied hydrogen in the inner tank 4 and changes in heat input due to fluctuations in the outside air temperature, the outer tank control temperature may be a temperature range with a temperature width. In general, the temperature of the outer tank 5 is lower in the lower half than in the upper half. Therefore, it is desirable to design the insulating performance of the first insulating layer 61 and the second insulating layer 62 so that the temperature of the outer tank 5 in the lower half of the outer tank 5 is the outer tank control temperature.

[0027] The outer vessel control temperature is set to a temperature at which oxygen gas does not condense on the surface of the outer vessel 5. The outer vessel control temperature is higher than the oxygen condensation point and lower than atmospheric temperature. The outer vessel control temperature may be higher than the oxygen condensation point and lower than the intermediate temperature between the temperature of the inner vessel 4 and the temperature of the outer shell 6. However, if the temperature of the outer vessel 5 is high, the first insulation layer 61, which has many restrictions, will be required to have high insulation performance, or the amount of vaporized gas generated from liquefied hydrogen in the inner vessel 4 will increase. Therefore, it is desirable that the outer vessel control temperature be higher than the oxygen condensation point but as low as possible. Furthermore, since the temperature of the outer vessel 5 also fluctuates due to fluctuations in atmospheric temperature and the temperature of the inner vessel 4, it is desirable to set the outer vessel control temperature taking such fluctuations into consideration. From this perspective, the outer vessel control temperature may be higher than the oxygen condensation point by 1°C to 40°C, or may be higher by 5°C to 25°C. Specific numerical examples are given below. However, the present disclosure is not limited to these.

[0028] In the first example, the temperature of the inner vessel 4 is -253°C, the temperature of the outer shell 6 is 27°C, and the outer vessel control temperature is -182°C, which is 1°C higher than the normal condensation point of oxygen. In the first example, the first insulating layer 61 has an insulating performance in which the temperature transitions in the layer thickness direction at approximately 70°C from -253°C to -182°C, and the second insulating layer 62 has an insulating performance in which the temperature transitions in the layer thickness direction at approximately 210°C from -182°C to 27°C. Strictly speaking, there are influences such as heat input from the skirt 25 and the support member 35, but when the insulating performance of the first insulating layer 61 and the second insulating layer 62 is compared excluding elements other than the first insulating layer 61 and the second insulating layer 62 of the thermal insulation structure of the liquefied hydrogen tank 3, in the first example, the ratio of the insulating performance of the first insulating layer 61 to the insulating performance of the second insulating layer 62 is approximately 1:3. The thermal insulation performance of the first insulating layer 61 and the second insulating layer 62 can be expressed, for example, by the thermal resistance in the wall thickness direction.

[0029] In the second example, the temperature of the inner tank 4 is -253°C, the temperature of the outer shell 6 is 27°C, and the outer tank control temperature is -159°C. In the second example, the first insulating layer 61 has an insulating performance in which the temperature transitions in the layer thickness direction at approximately 94°C from -253°C to -159°C, and the second insulating layer 62 has an insulating performance in which the temperature transitions in the layer thickness direction at approximately 186°C from -159°C to 27°C. In the second example, the ratio of the insulating performance of the first insulating layer 61 to the insulating performance of the second insulating layer 62 is approximately 1:2.

[0030] In a third example, the temperature of the inner tank 4 is -253°C, the temperature of the outer shell 6 is 27°C, and the outer tank control temperature is -113°C, which is the intermediate temperature between the temperature of the inner tank 4 and the temperature of the outer shell 6. In the third example, the first insulating layer 61 has insulating performance in which the temperature transitions in the layer thickness direction at approximately 140°C from -253°C to -113°C, and the second insulating layer 62 has insulating performance in which the temperature transitions in the layer thickness direction at approximately 140°C from -113°C to 27°C. In the third example, the ratio of the insulating performance of the first insulating layer 61 to the insulating performance of the second insulating layer 62 is approximately 1:1.

[0031] It is desirable that the insulating performance of the second insulating layer 62 be at least one time that of the first insulating layer 61. It is possible to make the insulating performance of the first insulating layer 61 higher than that of the second insulating layer 62, but in this case, it is inefficient and costs more, making it uneconomical.

[0032] The liquefied hydrogen tank 3 is equipped with an inspection device 8 for inspecting whether the temperature of the outer vessel 5 of the liquefied hydrogen tank 3 is properly controlled. As shown in FIG. 4 , the inspection device 8 includes a processor 801 and a memory 802. The processor 801 executes a predetermined program stored in the memory 802 to function as the inspection device 8. However, the configuration of the inspection device 8 is not limited to the above. The functions of the inspection device 8 can be performed using a circuit or processing circuit, including a general-purpose processor, a dedicated processor, an integrated circuit, an ASIC (Application Specific Integrated Circuit), a conventional circuit, and / or a combination thereof, configured or programmed to perform the disclosed functions. A processor includes transistors and other circuits, and therefore is considered a processing circuit or circuit. In this disclosure, a circuit, unit, or means is hardware that performs the enumerated functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the enumerated functions. When the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0033] The inspection device 8 is communicatively connected to a temperature sensor 81. The temperature sensor 81 detects the temperature of the outer bath 5. The temperature of the lower half of the outer bath 5 is generally lower than that of the upper half. Therefore, it is preferable that the temperature sensor 81 detects the temperature of the lower half of the outer bath 5. Even more preferably, if a portion of the outer bath 5 that is lower in temperature compared to the other portions is known, the temperature sensor 81 detects the temperature of that portion.

[0034] The processor 801 of the inspection device 8 acquires the detected temperature value of the outer tank 5 from the temperature sensor 81 and compares the detected value with a pre-stored oxygen condensation point. Because the second region 32 is at atmospheric pressure, the oxygen condensation point may be the normal condensation point, but the oxygen condensation point to be compared may be adjusted depending on the pressure of the second region 32. If the temperature of the outer tank 5 is below the oxygen condensation point, a defect in the inner tank 4 of the liquefied hydrogen tank 3 can be inferred. Examples of defects in the inner tank 4 include a leak of liquefied hydrogen and damage to the thermal insulation structure. If the detected temperature of the outer tank 5 is below the oxygen condensation point, the processor 801 determines that the temperature of the outer tank 5 of the liquefied hydrogen tank 3 is not properly managed, and if the detected temperature of the outer tank 5 is higher than the oxygen condensation point, it determines that the temperature is properly managed. The inspection device 8 may be configured to compare the detected temperature of the outer bath 5 with the outer bath control temperature, and determine that the temperature of the outer bath 5 is not properly controlled if the detected temperature of the outer bath 5 is equal to or lower than the outer bath control temperature, and determine that the temperature of the outer bath 5 is properly controlled if the detected temperature of the outer bath 5 is higher than the outer bath control temperature.If the outer bath control temperature is within a temperature range, the lower limit of the outer bath control temperature is compared with the detected temperature of the outer bath 5.

[0035] The inspection device 8 is communicatively connected to an output device 82. Examples of the output device 82 include an alarm and a monitor display. The processor 801 outputs the above-mentioned determination result to the output device 82. The processor 801 may output the determination result to the output device 82 only when it determines that the product is defective. Based on the information output by the output device 82, an operator can take measures to address the fact that the temperature of the outer tank 5 of the liquefied hydrogen tank 3 is not being properly managed.

[0036] As described above, the ship 1 according to an embodiment of the present disclosure includes a liquefied hydrogen tank 3. The liquefied hydrogen tank 3 includes an inner tank 4 that contains liquefied hydrogen, an outer tank 5 that surrounds the inner tank 4, an outer shell 6 that surrounds the outer tank 5, a first insulating layer 61 disposed in a first region 31 between the inner tank 4 and the outer tank 5, and a second insulating layer 62 disposed in a second region 32 between the outer tank 5 and the outer shell 6. The first region 31 is filled with a first gas, which is hydrogen gas or helium gas, and is at substantially atmospheric pressure or a low vacuum, while the second region 32 is filled with a second gas containing at least one of an inert gas and dry air. When liquefied hydrogen is contained in the inner tank 4 of the liquefied hydrogen tank 3, the temperature of the outer tank 5 is at a predetermined outer tank control temperature that is higher than the condensation point of oxygen and lower than atmospheric temperature. In other words, the combination of the first insulating layer 61 and the second insulating layer 62 has insulating performance such that, when liquefied hydrogen is contained in the inner tank 4 of the liquefied hydrogen tank 3, the temperature of the outer tank 5 becomes a predetermined outer tank control temperature that is higher than the condensation point of oxygen and lower than atmospheric temperature.

[0037] In the liquefied hydrogen tank 3, the outer vessel control temperature may be higher than the condensation point of oxygen and lower than the intermediate temperature between the temperature of the inner vessel 4 and the temperature of the outer shell 6. Alternatively, in the liquefied hydrogen tank 3, the outer vessel control temperature may be 1 to 30°C higher than the condensation point of oxygen.

[0038] In the liquefied hydrogen tank 3 and ship 1 configured as described above, the temperature of the outer tank 5 is maintained at the outer tank control temperature by utilizing the second insulating layer 62 disposed in the second region 32 outside the outer tank 5 and also disposing the first insulating layer 61 in the first region 31 between the inner tank 4 and the outer tank 5. The second region 32 contains oxygen that has entered the second insulating layer 62, oxygen that remains after replacement with the second gas, or oxygen contained in dry air. Although oxygen is present in the second region 32, the outer tank control temperature is higher than the condensation point of oxygen, so condensation of oxygen on the surface of the outer tank 5 is suppressed, preventing the generation of liquefied oxygen. Furthermore, by raising the outer tank control temperature above the condensation point of the second gas, condensation of the second gas on the surface of the outer tank 5 can also be suppressed.

[0039] In the above-described liquefied hydrogen tank 3, the heat insulating performance of the second heat insulating layer 62 may be from one to three times the heat insulating performance of the first heat insulating layer 61.

[0040] Compared to the first insulating layer 61 arranged in the first region 31 filled with the first gas, the second insulating layer 62 arranged in the second region 32 filled with the second gas having a lower thermal conductivity than the first gas has a higher insulating efficiency. Therefore, by setting the ratio of the insulating performance of the first insulating layer 61 to the second insulating layer 62 as described above, the insulating performance is efficiently and economically allocated to the first insulating layer 61 and the second insulating layer 62.

[0041] In the above-mentioned liquefied hydrogen tank 3, the second insulating layer 62 has an inner surface facing the outer tank 5 and an outer surface spaced apart from the inner surface in the wall thickness direction, and when liquefied hydrogen is contained in the inner tank 4, the temperature of the outer surface of the second insulating layer 62 may be higher than the dew point temperature of the moisture present in the second region 32 and lower than the atmospheric temperature.

[0042] The second region 32 contains moisture contained in the air that has entered the second insulating layer 62, moisture contained in the air that remains after replacement with the second gas, or moisture contained in the dry air. Although moisture is present in the second region 32 in this manner, condensation on the outer surface of the second insulating layer 62 can be prevented because the temperature of the outer surface of the second insulating layer 62 is higher than the dew point temperature.

[0043] The liquefied hydrogen tank 3 may further include a temperature sensor 81 that detects the temperature of the outer tank 5, and an inspection device 8 that acquires the detected value of the temperature sensor 81 and outputs a warning if the detected value is below the condensation point of oxygen or below the outer tank control temperature.

[0044] In a liquefied hydrogen tank 3 configured so that the temperature of the outer tank 5 exceeds the condensation point of oxygen, it is possible to inspect whether the temperature of the outer tank 5 of the liquefied hydrogen tank 3 is being properly controlled based on whether the temperature of the outer tank 5 is below the condensation point of oxygen. If it is determined that the temperature of the outer tank 5 is not being properly controlled, a defect in the inner tank 4 of the liquefied hydrogen tank 3 can be inferred. In this way, the inspection device 8 described above makes it possible to infer a defect in the inner tank 4 of the liquefied hydrogen tank 3 without opening the liquefied hydrogen tank 3.

[0045] While the preferred embodiment has been described above, the scope of the present disclosure also includes modifications to the specific structural and functional details of the above embodiment without departing from the spirit of the present disclosure. The configuration of the liquefied hydrogen tank 3 described above can be modified as follows.

[0046] For example, the liquefied hydrogen tank 3 according to the above embodiment includes two tanks, the inner tank 4 and the outer tank 5, but may include three or more tanks. In this case, the present disclosure can be applied by regarding the innermost tank as the inner tank 4 and the outermost tank as the outer tank 5.

[0047] For example, the liquefied hydrogen tank 3 in the above embodiment is a spherical (or rectangular) tank independent of the hull 2, but it may also be a membrane-type tank that utilizes the hull 2. In this case, the present disclosure can be applied to a membrane-type tank by replacing the inner tank 4 in the above embodiment with the membrane, the outer tank 5 with the inner shell, and the outer shell 6 with the outer shell (hull).

[0048] For example, although the liquefied hydrogen tank 3 in the above embodiment is a cargo tank, the liquefied hydrogen tank 3 does not necessarily have to be mounted as a cargo tank on the ship 1, and may be mounted as a fuel tank. Furthermore, the number of liquefied hydrogen tanks 3 mounted on the ship 1 is not specified.

[0049] For example, in the liquefied hydrogen tank 3 according to the above embodiment, the second region 32 is at the same pressure as or higher than the first region 31, but the second region 32 is at a lower pressure than the first region 31, and the first region 31 is at a lower pressure than the inside of the inner tank 4, so the present disclosure may be applied to such a so-called pressure accumulator tank. [Explanation of symbols]

[0050] 1: Ship 3: Liquefied hydrogen tank 4: Inner tank 5: Outer tank 6: Outer shell 8: Inspection equipment 22: Wall 31: 1st area 32:Second area 61: First insulation layer 62: Second insulation layer 81: Temperature sensor 801: Processor

Claims

1. an inner tank that contains liquefied hydrogen; an outer tank surrounding the inner tank; an outer shell surrounding the outer vessel; a first insulating layer disposed in a first region between the inner vessel and the outer vessel; a second insulating layer disposed in a second region between the outer vessel and the outer shell; the first region is filled with a first gas, which is hydrogen gas or helium gas, and is at atmospheric pressure or a low vacuum of 1.0×10 2 Pa to atmospheric pressure; the second region is filled with a second gas containing at least one of an inert gas and dry air; With liquefied hydrogen contained in the inner vessel, the temperature of the outer vessel is higher than the condensation point of oxygen. Liquefied hydrogen tank.

2. When liquefied hydrogen is contained in the inner tank, the temperature of the outer tank is higher than the condensation point of oxygen and is equal to or lower than an intermediate temperature between the temperature of the inner tank and the temperature of the outer shell. The liquefied hydrogen tank according to claim 1.

3. With liquefied hydrogen contained in the inner tank, the temperature of the outer tank is 1°C to 40°C higher than the condensation point of oxygen. The liquefied hydrogen tank according to claim 1.

4. 4. The liquefied hydrogen tank according to claim 1, wherein the insulating performance of the second insulating layer is from 1 to 3 times the insulating performance of the first insulating layer.

5. the second insulating layer has an inner surface facing the outer vessel and an outer surface spaced apart from the inner surface in a wall thickness direction, and when liquefied hydrogen is contained in the inner vessel, the temperature of the outer surface of the second insulating layer is higher than the dew point temperature of moisture present in the second region. The liquefied hydrogen tank according to any one of claims 1 to 4.

6. a temperature sensor for detecting the temperature of the outer tank; and an inspection device that acquires a detection value of the temperature sensor and outputs a warning if the detection value is equal to or lower than the condensation point of oxygen or equal to or lower than a predetermined outer tank control temperature that is higher than the condensation point of oxygen. The liquefied hydrogen tank according to any one of claims 1 to 5.

7. A ship comprising the liquefied hydrogen tank according to any one of claims 1 to 6.

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