Hydrogen reliquefaction system

Abstract

To provide a hydrogen re-liquefaction system capable of re-liquefying boil-off gas with higher efficiency.SOLUTION: A hydrogen re-liquefaction system re-liquefies boil-off gas generated in a liquefied hydrogen tank, and returns the same to the liquefied hydrogen tank. The hydrogen re-liquefaction system comprises: a dispensation passage in which hydrogen to be dispensed from the liquefied hydrogen tank to a supply destination flows; a re-liquefaction passage in which the boil-off gas flows; and a re-liquefaction apparatus that condenses the boil-off gas by cooling the boil-off gas flowing in the re-liquefaction passage. The re-liquefaction apparatus includes a condensation part provided in the re-liquefaction passage, and a heat dissipation part provided in the dispensation passage, and serves as a magnetic refrigerator that cools the boil-off gas via the condensation part by demagnetization and discharges heat at the time of magnetization to hydrogen via the heat dissipation part.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hydrogen reliquefaction system that reliquefies boil-off gas generated in a liquefied hydrogen tank and returns the gas to the liquefied hydrogen tank. [Background technology]

[0002] There is a reliquefaction system that reliquefies boil-off gas generated in a liquefied hydrogen tank that stores low-temperature liquefied gas. One example of a reliquefaction system is the low-temperature liquefied gas storage system described in Patent Document 1. In the low-temperature liquefied gas storage system described in Patent Document 1, the boil-off gas is first compressed. Then, heat is exchanged between the compressed boil-off gas and discharged gas. Furthermore, the compressed boil-off gas is expanded by an expansion valve, thereby reliquefying the boil-off gas. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-273681 Summary of the Invention [Problem to be solved by the invention]

[0004] In the low-temperature liquefied gas storage system of Patent Document 1, boil-off gas is compressed and cooled. The compressed and cooled boil-off gas is then expanded to liquefy the boil-off gas. Therefore, the efficiency of re-liquefying boil-off gas using the low-temperature liquefied gas storage system is low.

[0005] Therefore, an object of the present invention is to provide a hydrogen reliquefaction system that can reliquefy boil-off gas with higher efficiency. [Means for solving the problem]

[0006] The hydrogen reliquefaction system of the present invention is a hydrogen reliquefaction system that reliquefies boil-off gas generated in a liquefied hydrogen tank and returns it to the liquefied hydrogen tank, and is equipped with a discharge passage through which hydrogen flows to be discharged from the liquefied hydrogen tank to a supply destination, a reliquefaction passage through which the boil-off gas flows, and a reliquefaction device that condenses the boil-off gas by cooling the boil-off gas flowing through the reliquefaction passage, and the reliquefaction device is a magnetic refrigerator that includes a condensation section provided in the reliquefaction passage and a heat dissipation section provided in the discharge passage, and that cools the boil-off gas via the condensation section by demagnetizing it and releases the heat generated when magnetizing it to hydrogen via the heat dissipation section.

[0007] According to the present invention, a condenser section is provided in the reliquefaction passage and a heat dissipation section is provided in the discharge passage. Therefore, by dissipating heat to the discharge passage, which is much cooler than the atmosphere, a magnetic refrigerator with a narrow operating temperature range can be applied to the reliquefaction device. The magnetic refrigerator can cool the boil-off gas and dissipate heat to the hydrogen by switching between demagnetization and excitation. Using such a magnetic refrigerator in a reliquefaction device eliminates the need for devices such as compressors included in gas-type refrigerators. Therefore, the reliquefaction device does not need to drive compressors. This allows the reliquefaction device to perform reliquefaction more efficiently than a gas-refrigeration type reliquefaction device. [Effects of the Invention]

[0008] According to the present invention, boil-off gas can be reliquefied with higher efficiency. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a circuit diagram showing a hydrogen reliquefaction system according to a first embodiment of the present invention. [Figure 2] FIG. 4 is a circuit diagram showing a hydrogen reliquefaction system according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, hydrogen reliquefaction systems 1, 1A according to first and second embodiments of the present invention (hereinafter simply referred to as "reliquefaction systems") will be described with reference to the drawings. Note that the concept of direction used in the following description is used for convenience of explanation and does not limit the orientation of the configuration of the invention to that direction. Furthermore, the reliquefaction systems 1, 1A described below are merely one embodiment of the present invention. Therefore, the present invention is not limited to the embodiments, and additions, deletions, and modifications are possible within the scope of the invention.

[0011] [First embodiment] <Reliquefaction system> The reliquefaction system 1 shown in FIG. 1 is provided in a liquefied hydrogen storage facility that stores liquefied hydrogen. The reliquefaction system 1 includes a liquefied hydrogen tank 11. The liquefied hydrogen tank 11 stores liquefied hydrogen. In the liquefied hydrogen tank 11, boil-off gas is generated when a portion of the liquefied hydrogen evaporates. The reliquefaction system 1 reliquefies the boil-off gas generated in the liquefied hydrogen tank 11. The reliquefaction system 1 then returns the liquefied hydrogen generated by reliquefaction to the liquefied hydrogen tank 11. More specifically, the reliquefaction system 1 includes, in addition to the liquefied hydrogen tank 11 described above, a gas discharge passage 12, a reliquefaction passage 13, and a reliquefaction device 14.

[0012] <Liquefied hydrogen tank> As described above, the liquefied hydrogen tank 11 is a container for storing liquefied hydrogen. The liquefied hydrogen tank 11 also includes a vacuum insulation structure. However, the liquefied hydrogen tank 11 does not necessarily have to include a vacuum insulation structure. The inside of the liquefied hydrogen tank 11 is maintained at or below the saturation temperature of hydrogen by the vacuum insulation structure. Meanwhile, inside the liquefied hydrogen tank 11, boil-off gas is generated by evaporation of part of the liquefied hydrogen as described above. Therefore, inside the liquefied hydrogen tank 11, liquefied hydrogen is stored in the lower space 11a, and boil-off gas accumulates in the upper space 11b.

[0013] <Payment aisle> The gas discharge passage 12 is a passage through which hydrogen flows to be discharged from the liquefied hydrogen tank 11 to a supply destination. In this embodiment, the hydrogen discharged is boil-off gas (hereinafter referred to as "discharge gas"). Explaining in more detail, one end of the gas discharge passage 12 is connected to the liquefied hydrogen tank 11. In this embodiment, one end of the gas discharge passage 12 is connected to the upper space 11b of the liquefied hydrogen tank 11. On the other hand, the other end of the gas discharge passage 12 is connected to a supply destination. The supply destination is a hydrogen-consuming device such as a power generation device or a hydrogen engine, or an equipment equipped with them. However, the supply destination is not limited to a hydrogen-consuming device or an equipment equipped with them.

[0014] The gas discharge passage 12 also includes a heat insulating structure 12a and a compressor 12b. The heat insulating structure 12a, which is an example of a first heat insulating structure, blocks heat input to the boil-off gas flowing through the gas discharge passage 12. The boil-off gas flowing through the gas discharge passage 12 is maintained at an extremely low temperature (near the saturation temperature of hydrogen in this embodiment) that is the same as the temperature inside the liquefied hydrogen tank. The heat insulating structure 12a is, for example, a vacuum double-pipe structure. The compressor 12b compresses the discharge gas. More specifically, the compressor 12b compresses the boil-off gas at a pressure required by the supply destination. The compressor 12b then sends the discharge gas to the destination.

[0015] <Reliquefaction passage> The reliquefaction passage 13 allows the boil-off gas to flow. More specifically, the reliquefaction passage 13 allows the boil-off gas to be reliquefied to flow. The reliquefaction passage 13 then returns the reliquefied liquefied hydrogen to the liquefied hydrogen tank 11. More specifically, both ends of the reliquefaction passage 13 are connected to the liquefied hydrogen tank 11. More specifically, both ends of the reliquefaction passage 13 are connected to the upper space 11b of the liquefied hydrogen tank 11. In this embodiment, one end of the reliquefaction passage 13 is connected to the gas discharge passage 12. One end of the reliquefaction passage 13 is then connected to the upper space 11b of the liquefied hydrogen tank 11 via the gas discharge passage 12.

[0016] The reliquefaction passage 13 also includes a heat insulating structure 13a and a blower 13b. The heat insulating structure 13a, which is an example of a second heat insulating structure, blocks heat input to the boil-off gas flowing through the reliquefaction passage 13. The boil-off gas flowing through the reliquefaction passage 13 is maintained at the same cryogenic temperature (near the saturation temperature of hydrogen in this embodiment) as the temperature inside the liquefied hydrogen tank. The heat insulating structure 13a is, for example, a vacuum double-pipe structure. The blower 13b sucks the boil-off gas from the liquefied hydrogen tank 11. More specifically, the blower 13b sucks a portion of the boil-off gas guided from the upper space 11b of the liquefied hydrogen tank 11 to the gas discharge passage 12 into the reliquefaction passage 13. The blower 13b then sends the boil-off gas downstream of the blower 13b in the reliquefaction passage 13.

[0017] <Reliquefaction equipment> The reliquefaction device 14 cools the boil-off gas flowing through the reliquefaction passage 13. The reliquefaction device 14 then condenses the boil-off gas into liquefied hydrogen by cooling. More specifically, the reliquefaction device 14 cools the boil-off gas flowing through the reliquefaction passage 13 to a temperature equal to or lower than the saturation temperature of hydrogen. As a result, at least a portion of the boil-off gas flowing through the reliquefaction passage 13 is condensed into liquefied hydrogen. The reliquefaction device 14 having such a function is a magnetic refrigerator. The reliquefaction device 14, which is a magnetic refrigerator, will be described in more detail below.

[0018] The reliquefaction device 14 includes a condenser 14a and a heat radiator 14b. The condenser 14a is provided in the reliquefaction passage 13. More specifically, the condenser 14a is arranged downstream of the blower 13b in the reliquefaction passage 13. The reliquefaction device 14 cools the boil-off gas via the condenser 14a by demagnetizing it. The heat radiator 14b is provided in the gas discharge passage 12. More specifically, the heat radiator 14b is arranged on the supply destination side of the reliquefaction passage 13 in the gas discharge passage 12. The reliquefaction device 14 releases heat generated when magnetized to the hydrogen via the heat radiator 14b.

[0019] More specifically, the reliquefaction device 14 may be configured as follows. Note that the following example is one example of the configuration of the reliquefaction device 14. Therefore, the reliquefaction device 14 is not limited to the following configuration. That is, the reliquefaction device 14 may be configured in any manner as long as it can cool the boil-off gas by demagnetization as described above and release the heat generated during magnetization into the discharge gas. The reliquefaction device 14 further includes, for example, a heat medium 14c and a magnetic field generator 14d. The heat medium 14c is made of a magnetic material. The heat medium 14c is cooled by being demagnetized and generates heat by being magnetized. The magnetic field generator 14d magnetizes the heat medium 14c by generating a magnetic field around the heat medium 14c. The magnetic field generator 14d also demagnetizes the heat medium 14c by eliminating the magnetic field around the heat medium 14c. The magnetic field generator 14d is, for example, a coil or a permanent magnet. When the magnetic field generating unit 14d is a coil, the magnetic field generating unit 14d generates and cancels a magnetic field around the heat medium 14c by turning on and off a current flowing through the coil. When the magnetic field is canceled, the heat medium 14c is cooled, and the condenser unit 14a absorbs heat from the boil-off gas. When the magnetic field is generated, the heat medium 14c is heated, and the heat is released from the heat dissipation unit 14b to the discharge gas along with the previously absorbed heat. This allows heat to be transported from the condenser unit 14a to the heat dissipation unit 14b via the heat medium 14c. When the magnetic field generating unit 14d is a permanent magnet, the magnetic field generating unit 14d can generate and cancel a magnetic field around the heat medium 14c by moving the permanent magnet closer to or further away from the heat medium 14c. This cools the heat medium 14c. This allows heat to be transported from the condenser unit 14a to the heat dissipation unit 14b via the heat medium 14c.

[0020] In the reliquefaction device 14, the heat medium 14c is thermally connected to the condenser section 14a when demagnetizing. As a result, the reliquefaction device 14 cools the boil-off gas flowing through the reliquefaction passage 13 via the condenser section 14a. On the other hand, when magnetizing the reliquefaction device 14, the heat medium 14c is thermally connected to the heat radiator section 14b. As a result, the reliquefaction device 14 can radiate heat generated during magnetization from the heat radiator section 14b to the boil-off gas in the gas discharge passage 12. The heat medium 14c can then be cooled via the heat radiator section 14b. By demagnetizing the cooled heat medium 14c again, the heat medium 14c is further cooled. Then, by thermally connecting the further cooled heat medium 14c to the condenser section 14a, the boil-off gas can be cooled via the condenser section 14a. As a result, the boil-off gas is cooled by the condenser section 14a. In this way, the re-liquefaction device 14 can continue to cool the boil-off gas flowing through the re-liquefaction passage 13 by repeatedly demagnetizing and energizing.

[0021] Furthermore, the reliquefaction device 14 maintains the temperature of the condenser 14a below the saturation temperature of hydrogen. More specifically, the condenser 14a is kept at a cryogenic temperature by, for example, being thermally connected to cryogenic boil-off gas. Furthermore, the temperature of the condenser 14a is kept below the saturation temperature of hydrogen because the condenser 14a is cooled by the demagnetization effect of the reliquefaction device 14. Therefore, the temperature of the condenser 14a is below the saturation temperature of hydrogen corresponding to the internal pressure of the liquefied hydrogen tank 11, i.e., the pressure of the boil-off gas. This allows the condenser 14a to condense at least a portion of the boil-off gas flowing through the reliquefaction passage 13 into liquefied hydrogen. The temperature of the condenser 14a is merely an example and is not limited to this temperature range.

[0022] Furthermore, in the reliquefaction device 14, the temperature of the heat radiating section 14b is higher than the temperature of the condensing section 14a. More specifically, because heat generated during magnetization is radiated from the heat radiating section 14b, the temperature of the heat radiating section 14b is higher than the temperature of the condensing section 14a. On the other hand, the discharge gas from which the heat radiating section 14b radiates heat is maintained at an extremely low temperature because the gas discharge passage 12 in which the heat radiating section 14b is provided includes the thermal insulating structure 12a. For example, in this embodiment, the heat radiating section 14b is maintained at an extremely low temperature of 20 K or higher and 70 K or lower. Therefore, in the reliquefaction device 14, the temperature difference between the heat radiating section 14b and the condensing section 14a can be kept at 50 K or less. As a result, when the condensing section 14a is cooled by demagnetization after the heat of the heat radiating section 14b is radiated to the discharge gas, the temperature of the condensing section 14a can be lowered to below the saturation temperature. That is, the temperature difference between the heat radiating section 14b and the condensing section 14a can be kept within the operating range of the magnetic refrigerator.

[0023] <Operation of the reliquefaction system> In the reliquefaction system 1, when the compressor 12b of the gas discharge passage 12 is operated, discharge gas is discharged from the liquefied hydrogen tank 11 to the supply destination (see arrow A in FIG. 1). In addition, in the reliquefaction system 1, the blower 13b of the reliquefaction passage 13 is also operated. As a result, the boil-off gas from the liquefied hydrogen tank 11 also flows into the reliquefaction passage 13. More specifically, a portion of the boil-off gas flowing through the gas discharge passage 12 is sucked into the reliquefaction passage 13 by the blower 13b. Furthermore, the blower 13b sends the sucked boil-off gas to the reliquefaction device 14 located downstream (see arrow B in FIG. 1).

[0024] The reliquefaction device 14 cools the condenser section 14a by demagnetizing. The reliquefaction device 14 then releases the heat generated during magnetization to the discharge gas via the heat dissipation section 14b. This maintains the temperature of the condenser section 14a at or below the saturation temperature of hydrogen, which in this embodiment is 30 K. At least a portion of the boil-off gas passing through the reliquefaction device 14 is condensed into liquefied hydrogen. The condensed liquefied hydrogen is returned to the liquefied hydrogen tank 11 together with the remaining boil-off gas through the reliquefaction passage 13. In this way, the reliquefaction system 1 reliquefies the boil-off gas generated in the liquefied hydrogen tank 11 and returns it to the liquefied hydrogen tank 11 (see arrow C in FIG. 1).

[0025] The reliquefaction system 1 of this embodiment includes a condenser 14a provided in the reliquefaction passage 13 and a heat dissipation section 14b provided in the gas discharge passage 12. Therefore, by dissipating heat to the gas discharge passage 12, which is significantly lower in temperature than the atmosphere, a magnetic refrigerator with a narrow operating temperature range can be applied to the reliquefaction device 14. The magnetic refrigerator can cool the boil-off gas and dissipate heat to the discharge gas by switching between demagnetization and excitation. By using such a magnetic refrigerator in the reliquefaction device 14, it is possible to eliminate equipment such as a compressor included in a gas-type refrigerator. Therefore, since the reliquefaction device 14 does not require the operation of a compressor, the reliquefaction device 14 can perform reliquefaction more efficiently than a gas-refrigeration type reliquefaction device. Furthermore, because equipment such as a compressor can be eliminated, the reliquefaction device 14 can be made more compact.

[0026] Furthermore, in the reliquefaction system 1, the heat radiating section 14b radiates heat to the discharge gas discharged from the liquefied hydrogen tank 11, as well as to the boil-off gas to be reliquefied. Therefore, the temperature difference between the condensing section 14a and the heat radiating section 14b can be reduced. This prevents the reliquefaction device 14 from becoming complicated. More specifically, if the temperature difference between the condensing section 14a and the heat radiating section 14b is large, multiple refrigerators must be provided between the condensing section 14a and the heat radiating section 14b, which complicates the configuration of the reliquefaction device. If the temperature difference between the condensing section 14a and the heat radiating section 14b is small, the reliquefaction device 14 can be configured with, for example, a single magnetic refrigerator. This further prevents the configuration of the reliquefaction device 14 from becoming complicated. However, the reliquefaction device 14 may include multiple magnetic refrigerators.

[0027] Furthermore, in the reliquefaction system 1, the reliquefaction passage 13 is formed so as to branch off from the gas discharge passage 12. In the gas discharge passage 12, the heat radiating section 14b is disposed on the supply destination side (i.e., downstream side) of the portion where the reliquefaction passage 13 is connected to the gas discharge passage 12. Therefore, the boil-off gas to be reliquefied can be guided to the reliquefaction passage 13 without passing through the heat radiating section 14b. Therefore, the boil-off gas to be reliquefied does not absorb the heat radiated by the heat radiating section 14b. Therefore, boil-off gas at a lower temperature can be flowed into the reliquefaction passage 13 compared to when the heat radiating section 14b is disposed upstream of the reliquefaction passage 13. Therefore, the temperature of the boil-off gas flowing into the reliquefaction passage 13 can be kept low. This allows the temperature to be reduced by a smaller amount during reliquefaction.

[0028] Furthermore, in the reliquefaction system 1, the gas discharge passage 12 and the reliquefaction passage 13 have thermal insulating structures 12a and 13a, respectively, so that hydrogen and boil-off gas can be maintained at extremely low temperatures and guided to the heat dissipation section 14b and the condensation section 14a. The boil-off gas can be reliquefied by keeping the temperature of the condensation section 14a below the saturation temperature of hydrogen. Furthermore, by making the heat dissipation section 14b higher than the condensation section 14a and keeping the temperature difference between the heat dissipation section 14b and the condensation section 14a at 40 K or less, the temperature difference can be kept within the operating range of a magnetic refrigerator. This prevents the configuration of the reliquefaction device 14 from becoming too complicated.

[0029] Second Embodiment The reliquefaction system 1A of the second embodiment has a similar configuration to the reliquefaction system 1 of the first embodiment. Therefore, the configuration of the reliquefaction system 1A of the second embodiment will be mainly described in terms of differences from the reliquefaction system 1 of the first embodiment, and the same components will be assigned the same reference numerals and descriptions thereof will be omitted.

[0030] The reliquefaction system 1A of the second embodiment includes a liquefied hydrogen tank 11, a liquid discharge passage 12A, a reliquefaction passage 13, and a reliquefaction device 14. The liquid discharge passage 12A is a passage through which hydrogen flows to be discharged from the liquefied hydrogen tank 11 to a supply destination. In this embodiment, the hydrogen discharged is liquefied hydrogen (hereinafter referred to as "discharge liquid").

[0031] More specifically, one end of the liquid dispensing passage 12A is connected to the liquefied hydrogen tank 11. In this embodiment, one end of the liquid dispensing passage 12A is connected to the lower space 11a of the liquefied hydrogen tank 11. On the other hand, the other end of the liquid dispensing passage 12A is connected to the supply destination. The liquid dispensing passage 12A also includes a heat insulating structure 12a and a pump 12c. The pump 12c sends the dispensing liquid guided from the liquefied hydrogen tank 11 through the liquid dispensing passage 12A to the supply destination side. The liquid dispensing passage 12A also has a heat exchanger (not shown). The liquid dispensing passage 12A vaporizes the dispensing liquid by applying heat to the dispensing liquid using the heat exchanger. The facility equipped with the reliquefaction system 1A then supplies the vaporized hydrogen gas to the supply destination (see arrow D in FIG. 2).

[0032] In the reliquefaction passage 13A, both ends of the reliquefaction passage 13A are connected to the liquefied hydrogen tank 11. Specifically, both ends of the reliquefaction passage 13A are connected to the upper space 11b of the liquefied hydrogen tank 11. In FIG. 2, the reliquefaction passage 13A is directly connected to the upper space 11b of the liquefied hydrogen tank 11, but it may also be connected to the liquefied hydrogen tank 11 via a gas discharge passage 12 (not shown), similar to the reliquefaction passage 13 of the first embodiment. The reliquefaction passage 13A also includes a blower 13b.

[0033] In the reliquefaction device 14, a condensation section 14a is provided in the reliquefaction passage 13A, and a heat radiating section 14b is provided in the liquid dispensing passage 12A. The heat radiating section 14b is arranged on the supply destination side of the pump 12c in the liquid dispensing passage 12A. More specifically, the heat radiating section 14b is arranged upstream of a heat exchanger (not shown) in the liquid dispensing passage 12A.

[0034] In the reliquefaction system 1A, when the pump 12c of the liquid discharge passage 12A is operated, the discharge liquid is discharged from the liquefied hydrogen tank 11 to the liquid discharge passage 12A (see arrow D in FIG. 2). In the reliquefaction passage 13A, the blower 13b sends boil-off gas to the reliquefaction device 14 (see arrow E in FIG. 2). In the reliquefaction device 14, the condensation section 14a is cooled by demagnetization, and heat generated during magnetization is released into the discharge liquid via the heat dissipation section 14b. As a result, at least a portion of the boil-off gas passing through the reliquefaction device 14 is condensed into liquefied hydrogen. The condensed liquefied hydrogen is then returned to the liquefied hydrogen tank 11 along with the remaining boil-off gas through the reliquefaction passage 13A. In this way, in the reliquefaction system 1A, the boil-off gas generated in the liquefied hydrogen tank 11 is reliquefied and returned to the liquefied hydrogen tank 11 (see arrow F in FIG. 2).

[0035] In the reliquefaction system 1A of this embodiment, the heat dissipation section 14b dissipates heat to the liquefied hydrogen, which has a lower temperature than the boil-off gas. This reduces the temperature difference between the condensation section 14a and the heat dissipation section 14b, and prevents the magnetic refrigerator from becoming complicated in configuration.

[0036] In addition, the reliquefaction system 1A of the second embodiment has the same effects as the reliquefaction system 1 of the first embodiment.

[0037] <Other embodiments> Although the reliquefaction systems 1, 1A of the first and second embodiments are installed in a liquefied hydrogen storage facility, the installation of the reliquefaction systems 1, 1A is not necessarily limited to a liquefied hydrogen storage facility. For example, the reliquefaction systems 1, 1A may be installed in a vehicle such as a ship or a vehicle, or in other equipment.

[0038] Furthermore, in the reliquefaction system 1 of the first embodiment, the heat radiating section 14b is arranged on the supply destination side of the reliquefaction passage 13 in the gas discharge passage 12. However, the heat radiating section 14b may also be arranged on the liquefied hydrogen tank 11 side of the reliquefaction passage 13 in the gas discharge passage 12. Furthermore, in the reliquefaction system 1A of the second embodiment, the heat radiating section 14b is arranged on the liquid discharge passage 12A downstream of the pump 12c and upstream of the heat exchanger (not shown). However, the heat radiating section 14b may also be arranged upstream of the pump 12c.

[0039] In the reliquefaction systems 1 and 1A of the first and second embodiments, the reliquefaction device 14, which is a magnetic refrigerator, does not necessarily have to be configured as described above. That is, the reliquefaction device 14 may be configured to cool the boil-off gas through the condensation section 14a by demagnetizing and to radiate the heat generated when magnetizing to the dispensing gas or the dispensing liquid through the heat radiating section 14b. [Explanation of symbols]

[0040] 1,1A Hydrogen Reliquefaction System 11 Liquefied hydrogen tank 12 Gas outlet passage 12A Liquid dispensing passage 12a Insulation structure 13,13A Reliquefaction passage 13a Insulated structure 14 Reliquefaction equipment 14a Condenser section 14b Heat dissipation part

Claims

1. A hydrogen reliquefaction system that reliquefies boil-off gas generated in a liquefied hydrogen tank and returns the boil-off gas to the liquefied hydrogen tank, a delivery passage through which hydrogen flows to be delivered from the liquefied hydrogen tank to a supply destination; a reliquefaction passage through which the boil-off gas flows; a re-liquefaction device that condenses the boil-off gas by cooling the boil-off gas flowing through the re-liquefaction passage, The reliquefaction device is a magnetic refrigerator including a condensation section provided in the reliquefaction passage and a heat dissipation section provided in the discharge passage, and the magnetic refrigerator is demagnetized to cool the boil-off gas through the condensation section and release the heat generated when the magnetic refrigerator is magnetized to hydrogen through the heat dissipation section.

2. The discharge passage allows the flow of boil-off gas, which is hydrogen discharged from the liquefied hydrogen tank to the supply destination, 2. The hydrogen reliquefaction system according to claim 1, wherein the magnetic refrigerator radiates heat to the boil-off gas flowing through the discharge passage via the heat radiating portion.

3. the discharge passage is connected to the liquefied hydrogen tank, The reliquefaction passage is connected to the liquefied hydrogen tank via the discharge passage.

3. The hydrogen reliquefaction system according to claim 2, wherein the heat dissipation section of the reliquefaction device is disposed on the supply destination side of the reliquefaction passage in the discharge passage.

4. The discharge passage allows liquefied hydrogen, which is hydrogen discharged from the liquefied hydrogen tank to the supply destination, to flow through the discharge passage.

2. The hydrogen reliquefaction system according to claim 1, wherein the reliquefaction device dissipates heat to the liquefied hydrogen flowing through the discharge passage via the heat dissipation section.

5. the discharge passage has a first heat insulating structure that blocks heat input to the hydrogen, the reliquefaction passage has a second heat insulating structure that blocks heat input to the boil-off gas, 5. The hydrogen reliquefaction system according to claim 1, wherein the reliquefaction device has a temperature of the condensation section that is 30 K or less, which is lower than the saturation temperature of hydrogen, a temperature of the heat dissipation section that is 20 K or more, which is higher than the temperature of the condensation section, and a temperature difference between the heat dissipation section and the condensation section that is 50 K or less.

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