Liquefied hydrogen loading system and boil-off gas transfer system

Abstract

This liquid hydrogen loading / unloading system comprises: a hydrogen tank for storing liquid hydrogen; loading / unloading equipment with which the loading / unloading of liquid hydrogen to / from the hydrogen tank is carried out; a sealing device that is provided to the loading / unloading equipment and that, using a first sealing gas, creates a seal between the inside of the loading / unloading equipment and atmospheric air; and a sealing gas supply system that supplies, to the sealing device as the first sealing gas, a boil-off gas which was vaporized in the hydrogen tank.

Description

[Technical Field]

[0001] The present disclosure relates to a liquefied hydrogen loading system that loads and unloads liquefied hydrogen, and a boil-off gas transfer system that transfers boil-off gas. [Background technology]

[0002] There are loading and unloading systems for loading and unloading liquefied gas, and one known example is the loading and unloading system described in Patent Document 1. The loading and unloading system of Patent Document 1 is installed, for example, at an LNG receiving terminal. The loading and unloading system includes loading and unloading equipment. LNG is unloaded from a delivery tank (for example, a tank on an LNG carrier) to a receiving tank (for example, a tank at the terminal) by the loading and unloading equipment. Meanwhile, when LNG is unloaded, boil-off gas from the receiving tank is returned to the delivery tank as return gas. This prevents the delivery tank from becoming negative pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-99500 A Summary of the Invention [Problem to be solved by the invention]

[0004] The cargo handling equipment in the cargo handling system of Patent Document 1 has various components. Each component is provided with a sealing device to prevent gas leakage between parts. The sealing device uses a mechanical seal such as a gasket and a sealing gas. Nitrogen is used as the sealing gas.

[0005] The liquefied gas handled by the loading and unloading system of Patent Document 1 is LNG, but hydrogen is also handled as a liquefied gas. The liquefaction temperature of hydrogen is lower than the solidification temperature of nitrogen. Therefore, if hydrogen is unloaded using the same loading and unloading system as LNG, the nitrogen used as the seal gas will solidify. This could cause the sealing device to malfunction. Similarly, in a boil-off gas transfer system equipped with transfer equipment for transferring boil-off gas, the sealing device of the transfer equipment could malfunction.

[0006] Therefore, an object of the present disclosure is to provide a liquefied hydrogen loading system and a boil-off gas transfer system that can prevent the seal gas from solidifying and causing the seal device to stop functioning. [Means for solving the problem]

[0007] The liquefied hydrogen loading and unloading system of the present disclosure comprises a hydrogen tank for storing liquefied hydrogen, loading and unloading equipment for loading and unloading the liquefied hydrogen into the hydrogen tank, a sealing device provided in the loading and unloading equipment for sealing the space between the inside of the loading and unloading equipment and the atmosphere using a first sealing gas, and a sealing gas supply system for supplying boil-off gas vaporized in the hydrogen tank to the sealing device as the first sealing gas.

[0008] According to the liquefied hydrogen loading system of the present disclosure, hydrogen, which is boil-off gas, is used as the seal gas for the sealing device, thereby preventing the seal gas from liquefying, thereby preventing the seal gas from solidifying and causing the sealing device to malfunction.

[0009] The boil-off gas transfer system of the present disclosure comprises a hydrogen tank for storing liquefied hydrogen, a transfer facility for transferring the boil-off gas vaporized in the hydrogen tank, and a sealing device provided in the transfer facility for sealing the space between the interior of the transfer facility and the atmosphere using a first sealing gas, and the boil-off gas is supplied to the sealing device as the first sealing gas.

[0010] According to the boil-off gas transfer system of the present disclosure, hydrogen, which is a boil-off gas, is used as the seal gas for the sealing device, thereby preventing the seal gas from liquefying, thereby preventing the seal gas from solidifying and causing the sealing device to malfunction. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to prevent the sealing gas from solidifying and causing the sealing device to fail.

[0012] The above and other objects, features, and advantages of the present disclosure will become apparent from the following detailed description of preferred embodiments, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a configuration diagram showing a liquefied hydrogen loading and unloading system according to a first embodiment of the present disclosure. FIG. [Figure 2] FIG. 2 is a cross-sectional view showing a sealing device of the liquefied hydrogen loading and unloading system of FIG. 1. [Figure 3] FIG. 2 is a configuration diagram showing the flow of boil-off gas outside the loading period in the liquefied hydrogen loading system of FIG. 1. [Figure 4] FIG. 2 is a configuration diagram showing the flow of boil-off gas during the loading period in the liquefied hydrogen loading system of FIG. 1. [Figure 5] FIG. 10 is a configuration diagram showing a liquefied hydrogen loading and unloading system according to a second embodiment of the present disclosure. [Figure 6] FIG. 10 is a configuration diagram showing a liquefied hydrogen loading and unloading system according to a third embodiment of the present disclosure. [Figure 7] FIG. 10 is a configuration diagram showing a boil-off gas transfer system according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0014] The liquefied hydrogen loading systems 1, 1A, and 1B of the first to third embodiments and the boil-off gas transfer system 1C of the fourth embodiment according to the present disclosure will be described below with reference to the drawings. The concepts of directions used in the following description are used for convenience of explanation and do not limit the orientation of the disclosed configurations to those directions. The liquefied hydrogen loading systems 1, 1A, and 1B and the boil-off gas transfer system 1C described below are merely one embodiment of the present disclosure. Therefore, the present disclosure is not limited to the embodiments, and additions, deletions, and modifications are possible within the scope of the disclosure.

[0015] [First embodiment] <Liquefied hydrogen cargo handling system> The liquefied hydrogen loading system 1 shown in FIG. 1 loads and unloads liquefied hydrogen between a tank 2 provided on a ship or onshore facility. In this embodiment, the liquefied hydrogen loading system 1 is provided on land, such as at a port. The tank 2 is provided on a ship (e.g., a tanker) and can store liquefied hydrogen. The liquefied hydrogen loading system 1 loads and unloads liquefied hydrogen between the tank 2 on the ship. However, the liquefied hydrogen loading system 1 does not necessarily have to be provided on land. For example, the liquefied hydrogen loading system 1 may be provided on a ship. Describing the liquefied hydrogen loading system 1 in more detail, the liquefied hydrogen loading system 1 includes a hydrogen tank 11, loading equipment 12, a sealing device 13, a seal gas supply system 14, and discharge equipment 15.

[0016] <Hydrogen tank> The hydrogen tank 11 can store liquefied hydrogen. The hydrogen tank 11 has an insulating structure such as a vacuum insulating structure. The hydrogen tank 11 maintains the temperature of the liquefied hydrogen stored therein below the boiling point of the liquefied hydrogen 11a. In the hydrogen tank 11, some of the liquefied hydrogen is vaporized. The remaining part of the hydrogen tank 11 excluding the liquefied hydrogen is filled with boil-off gas 11b. Tank 2 is also configured in the same manner as the hydrogen tank 11.

[0017] <Loading equipment> The loading and unloading equipment 12 loads and unloads liquefied hydrogen between the hydrogen tank 11 and tank 2. That is, the liquefied hydrogen stored in the hydrogen tank 11 is transported to tank 2, or the liquefied hydrogen stored in tank 2 is transported to the hydrogen tank 11. More specifically, the loading and unloading equipment 12 has a piping 21 for liquefied hydrogen, a piping 22 for return gas, a hydraulic pump 23, and a return gas blower 24.

[0018] The liquefied hydrogen pipe 21 is a pipe that connects the hydrogen tank 11 and tank 2. To explain in more detail, the liquefied hydrogen pipe 21 is connected to the hydrogen tank 11. The liquefied hydrogen pipe 21 can also be connected to tank 2 via a joint (not shown). When the liquefied hydrogen pipe 21 is connected to tank 2, it can allow liquefied hydrogen to flow from the hydrogen tank 11 to tank 2 or in the opposite direction.

[0019] The return gas pipe 22 is a pipe that connects the hydrogen tank 11 and the tank 2. To explain in more detail, the return gas pipe 22 is connected to, for example, the hydrogen tank 11. The return gas pipe 22 can be connected to the tank 2 via a joint (not shown) in the same way as the liquefied hydrogen pipe 21. Furthermore, the return gas pipe 22 can allow boil-off gas (return gas) to flow from the hydrogen tank 11 to the tank 2 or in the opposite direction.

[0020] The hydraulic pump 23 is interposed in the liquefied hydrogen piping 21. The hydraulic pump 23 can send liquefied hydrogen from the delivery-side tank (tank 2 in this embodiment) to the receiving-side tank (hydrogen tank 11 in this embodiment). This allows liquefied hydrogen to be loaded and unloaded between the hydrogen tank 11 and tank 2. When the delivery-side tank is the hydrogen tank 11, the hydraulic pump 23 sends the liquefied hydrogen in the direction opposite to the direction described above. The hydraulic pump 23 does not necessarily have to be provided in the loading and unloading facility 12, and may be provided on the loading and unloading ship. The hydraulic pump 23 may also be provided inside the tank 2 or the hydrogen tank 11.

[0021] The return gas blower 24 is disposed in the return gas piping 22. The return gas blower 24 can send return gas from the receiving tank (hydrogen tank 11 in this embodiment) to the delivery tank (tank 2 in this embodiment). When the delivery tank is the hydrogen tank 11, the return gas blower 24 sends the return gas in the direction opposite to the direction described above. Explaining the return gas blower 24 in more detail, the return gas blower 24 is, for example, a compressor. That is, the return gas blower 24 compresses the return gas before sending it. Explaining in further detail, the return gas blower 24 has a casing 31 and an impeller 32, as shown in FIG. 2.

[0022] The casing 31 is interposed in the return gas piping 22. More specifically, the casing 31 has a flow path 31a and a shaft insertion hole 31b formed therein. The flow path 31a is interposed in the return gas piping 22. That is, one side and the other side of the flow path 31a are connected to the hydrogen tank 11 and the tank 2 via the return gas piping 22. The shaft insertion hole 31b is a hole formed in the casing 31. One side of the shaft insertion hole 31b opens to the flow path 31a, and the other side opens to the atmosphere.

[0023] The impeller 32 has a shaft portion 32a and an impeller portion 32b. The shaft portion 32a is inserted into a shaft portion insertion hole 31b of the casing 31 and is rotatably supported therein. One axial end of the shaft portion 32a is connected to a prime mover such as an engine or electric motor (not shown) that is provided outside the casing 31. The other axial end of the shaft portion 32a is provided with an impeller portion 32b. The impeller portion 32b is disposed in the flow path 31a. When the shaft portion 32a is rotated by the prime mover, the impeller portion 32b compresses the return gas in the flow path 31a. The impeller portion 32b sends the return gas to either the hydrogen tank 11 or the tank 2 depending on the direction of rotation of the shaft portion 32a.

[0024] The loading and unloading equipment 12 configured as described above operates as follows during the loading and unloading period when liquefied hydrogen is loaded and unloaded between the hydrogen tank 11 and tank 2. That is, when loading and unloading liquefied hydrogen in the loading and unloading equipment 12, the hydraulic pump 23 is operated in accordance with the transport direction of the liquefied hydrogen. Here, the transport direction is the direction from the delivery tank to the receiving tank. For example, if the delivery tank is tank 2, the receiving tank is hydrogen tank 11. Also, if the delivery tank is hydrogen tank 11, the receiving tank is tank 2. Then, by operating the hydraulic pump 23, liquefied hydrogen is transported from the delivery tank to the receiving tank. Furthermore, when transporting liquefied hydrogen, the loading and unloading equipment 12 operates the return gas blower 24 together with the hydraulic pump 23 in accordance with the transport direction. That is, the return gas blower 24 sends return gas in the direction opposite to the transport direction. This prevents an excessive pressure drop from occurring in the dispensing tank, and also prevents an excessive pressure rise from occurring in the receiving tank.

[0025] <Sealing device> The sealing device 13 is provided in the loading and unloading equipment 12. The sealing device 13 seals the interior of the loading and unloading equipment 12, through which cryogenic hydrogen flows, from the atmosphere using a seal gas. In this specification, "sealing" means that the gas flowing through the loading and unloading equipment 12, i.e., boil-off gas, is not released into the atmosphere. In this specification, "cryogenic temperature" refers to a temperature below the temperature at which nitrogen solidifies. In this embodiment, the sealing device 13 is provided in the return gas blower 24 of the loading and unloading equipment 12. The sealing device 13 seals the interior of the return gas blower 24 from the atmosphere using a seal gas. The return gas blower 24 is one example of an object on which the sealing device 13 is provided, and the sealing device 13 may be provided in piping or other equipment in the loading and unloading equipment 12. The sealing device 13 is particularly suitable for sealing between two components that move relative to each other. However, the sealing device 13 may also be used when sealing between two members that do not move relative to each other. The sealing device 13, together with the hydrogen tank 11 and a return gas blower 24, which is an example of transfer equipment, constitutes a boil-off gas transfer system 60. In this embodiment, the boil-off gas transfer system 60 also includes a seal gas supply system 14, which will be described later. To explain the sealing device 13 in more detail, the sealing device 13 has three seal members 13a to 13c, a first seal gas space 34, and a second seal gas space 35.

[0026] The three seal members 13a to 13c are provided between the casing 31 and the shaft 32a of the return gas blower 24. More specifically, the seal members 13a to 13c are formed in an annular shape. Each of the seal members 13a to 13c is composed of one or more seals. The first seal member 13a, the second seal member 13b, and the third seal member 13c are arranged in this order from inside the return gas blower 24 and fitted to the shaft 32a at intervals. The seal members 13a to 13c are interposed between the shaft insertion hole 31b of the casing 31 and the shaft 32a, and seal the gap between the shaft insertion hole 31b and the shaft 32a.

[0027] The first seal gas space 34 and the second seal gas space 35 are disposed between the inside of the return gas blower 24 and the atmosphere. The first seal gas space 34 is supplied with boil-off gas, which is a first seal gas. The second seal gas space 35 is disposed closer to the atmosphere than the first seal gas space 34. The second seal gas space 35 is supplied with a second seal gas, which is nitrogen gas, from a nitrogen supply device 16. The sealing device 13 seals the inside of the return gas blower 24 from the atmosphere by the first seal gas and the second seal gas supplied to the two seal gas spaces 34, 35, respectively. The second seal gas is not limited to nitrogen gas, and may be another gas such as argon gas.

[0028] More specifically, the first seal gas space 34 and the second seal gas space 35 are formed in the shaft portion insertion hole 31b of the casing 31. The first seal gas space 34 is formed between the first seal member 13a and the second seal member 13b, and the second seal gas space 35 is formed between the second seal member 13b and the third seal member 13c. More specifically, the first seal gas space 34 and the second seal gas space 35 are formed around the entire circumferential circumference of the shaft portion insertion hole 31b and are recessed radially outward. That is, the first seal gas space 34 and the second seal gas space 35 are formed in an annular shape so as to surround the entire circumferential circumference of the shaft portion 32a.

[0029] In the sealing device 13 configured as described above, the sealing members 13a to 13c prevent the return gas in the return gas blower 24 from being released into the atmosphere. Furthermore, the sealing device 13 captures the slight amount of return gas leaking through the sealing member 13a using the first sealing gas space 34. In this way, the sealing device 13 prevents the return gas from leaking into the atmosphere. Furthermore, the second sealing gas space 35 captures the first sealing gas leaking from the first sealing gas space 34 through the second sealing member 13b. In this way, the sealing device 13 prevents the first sealing gas from leaking out. In this way, the sealing device 13 seals the return gas blower 24 from the atmosphere using the first sealing gas and the second sealing gas.

[0030] <Seal gas supply system> The seal gas supply system 14 supplies the boil-off gas vaporized in the hydrogen tank 11 to the sealing device 13 as a first seal gas. More specifically, the seal gas supply system 14 has a boil-off gas recovery line 41, a compressor 42, a boil-off gas storage tank 43, and a supply line 44. The boil-off gas recovery line 41 is connected to the hydrogen tank 11. The boil-off gas from the hydrogen tank 11 is introduced into the boil-off gas recovery line 41. In this embodiment, the boil-off gas recovery line 41 is connected so as to branch off from the return gas piping 22.

[0031] The compressor 42 is disposed in the boil-off gas recovery line 41. The compressor 42 sucks in and compresses the boil-off gas introduced into the boil-off gas recovery line 41. The compressor 42 then sends the boil-off gas to the downstream side of the boil-off gas recovery line 41.

[0032] The boil-off gas storage tank 43 stores the boil-off gas transferred by the compressor 42. More specifically, the boil-off gas storage tank 43 is connected to the boil-off gas recovery line 41. The boil-off gas compressed by the compressor 42 (i.e., compressed gas) is sent to the boil-off gas storage tank 43 via the boil-off gas recovery line 41. The boil-off gas storage tank 43 stores the sent compressed gas therein. The boil-off gas storage tank 43 also holds the compressed gas at room temperature.

[0033] The supply line 44 is connected to the boil-off gas storage tank 43. The supply line 44 is also connected to the sealing device 13. That is, the boil-off gas storage tank 43 is connected to the sealing device 13 via the supply line 44. More specifically, the supply line 44 is connected to the first sealing gas space 34 in the sealing device 13.

[0034] In the seal gas supply system 14 configured as described above, the boil-off gas in the hydrogen tank 11 is stored in the boil-off gas storage tank 43. More specifically, in the seal gas supply system 14, the boil-off gas in the hydrogen tank 11 is stored in the boil-off gas storage tank 43 outside of the loading and unloading period when no loading and unloading work is being performed at the loading and unloading equipment 12. That is, in the seal gas supply system 14, the compressor 42 is driven outside of the loading and unloading period. As a result, the boil-off gas in the hydrogen tank 11 is sucked into the compressor 42 via the boil-off gas recovery line 41. Furthermore, the boil-off gas is compressed by the compressor 42 and sent to the boil-off gas storage tank 43. As a result, the compressed gas is stored in the boil-off gas storage tank 43.

[0035] On the other hand, in the seal gas supply system 14, during the loading and unloading period, the boil-off gas stored in the boil-off gas storage tank 43 is sent to the sealing device 13 as the first seal gas. More specifically, in the seal gas supply system 14, the first seal gas is supplied from the boil-off gas storage tank 43 to the first seal gas space 34 of the sealing device 13. Also, the second seal gas is supplied from the nitrogen supply device 16 to the second seal gas space 35. That is, the first seal gas and the second seal gas are supplied to the sealing device 13. In this way, the sealing device 13 seals the inside of the return gas blower 24 from the atmosphere.

[0036] <Discharge equipment> The discharge equipment 15 discharges the first seal gas supplied to the first seal gas space 34. More specifically, the discharge equipment 15 is connected to the first seal gas space 34 and the atmosphere. The discharge equipment 15 discharges the first seal gas supplied to the first seal gas space 34 to the atmosphere. The discharge equipment 15 is also connected to the second seal gas space 35 in addition to the first seal gas space 34. The discharge equipment 15 also discharges the second seal gas space 35 to the atmosphere. More specifically, the discharge equipment 15 discharges a mixed gas containing the first seal gas and the second seal gas to the atmosphere.

[0037] In this embodiment, the discharge equipment 15 has a vent line 51 and a valve 52. The vent line 51 is connected to the first seal gas space 34 and the second seal gas space 35, and is connected to the atmosphere. The vent line 51 is provided with a valve 52. The discharge equipment 15 opens the valve 52 while the return gas blower 24 is operating. As a result, the mixed gas containing the two seal gases supplied to each of the seal gas spaces 34 and 35 is discharged to the atmosphere via the vent line 51.

[0038] <Effects of the liquefied hydrogen loading system> In the liquefied hydrogen loading system 1, the compressor 42 operates outside of loading and unloading periods. As a result, the boil-off gas vaporizing in the hydrogen tank 11 is sucked in and compressed by the compressor 42 via the boil-off gas recovery line 41, as shown by the bold line in Figure 3. The boil-off gas is then sent as compressed gas to the boil-off gas storage tank 43. As a result, the compressed gas is stored in the boil-off gas storage tank 43.

[0039] Furthermore, the liquefied hydrogen loading system 1 operates as follows during the loading and unloading period. That is, in the liquefied hydrogen loading system 1, the loading and unloading of liquefied hydrogen begins when tank 2 is connected to the loading and unloading equipment 12. The following explanation will be given taking as an example a case where the delivery tank is tank 2 and the receiving tank is hydrogen tank 11, as shown by the bold line in Figure 4. That is, in the liquefied hydrogen loading and unloading system 1, the hydraulic pump 23 operates during the loading and unloading period. This transports liquefied hydrogen from tank 2 to hydrogen tank 11. Meanwhile, in the liquefied hydrogen loading and unloading system 1, the return gas blower 24 also operates during the loading and unloading period. The return gas blower 24 sends boil-off gas from the hydrogen tank 11 to tank 2 as return gas. Note that when the delivery tank is hydrogen tank 11 and the receiving tank is tank 2, the liquefied hydrogen and return gas are each sent in the opposite direction to the directions described above.

[0040] In the liquefied hydrogen loading system 1, while the return gas blower 24 is operating, the compressed gas stored in the boil-off gas storage tank 43 is supplied as a seal gas from the seal gas supply system 14 to the sealing device 13 (see the thick double-dotted line in FIG. 4). More specifically, while the return gas blower 24 is operating, the valve 52 in the discharge equipment 15 is opened. This causes the compressed gas in the boil-off gas storage tank 43 to be supplied as a seal gas to the supply line 44 of the seal gas supply system 14. The seal gas then flows through the supply line 44 into the first seal gas space 34 of the sealing device 13. In the first seal gas space 34, the slight amount of return gas leaking through the sealing member 13a is captured by the first seal gas. This prevents the return gas from leaking directly into the atmosphere. A second seal gas (nitrogen gas) is supplied to the second seal gas space 35 from a supply device (not shown). The second seal gas space 35 captures the first seal gas leaking from the first seal gas space 34 via the second seal member 13b. This prevents the first seal gas from leaking directly into the atmosphere. In this way, the seal device 13 seals the return gas blower 24 from the atmosphere by the first seal gas and the second seal gas.

[0041] Furthermore, the first seal gas in the first seal gas space 34 is discharged to the atmosphere via the vent line 51. This allows the first seal gas to be constantly supplied to the first seal gas space 34, thereby preventing a decrease in the temperature of the first seal gas. Furthermore, the second seal gas is discharged to the atmosphere via the vent line 51 together with the first seal gas. This allows the second seal gas to be constantly supplied to and discharged from the second seal gas space 35, thereby preventing a decrease in the temperature of the second seal gas. In other words, solidification of nitrogen, which is the second seal gas, is further prevented.

[0042] In the liquefied hydrogen loading system 1 of this embodiment, hydrogen, which is a boil-off gas, is used as the first seal gas for the sealing device 13, thereby preventing the first seal gas from liquefying. This prevents the first seal gas from solidifying and causing the sealing device 13 to stop functioning.

[0043] Furthermore, in the liquefied hydrogen loading system 1, the second sealed gas space 35 through which the nitrogen gas flows is disposed closer to the atmosphere than the first sealed gas space 34, and therefore solidification of the nitrogen gas in the second sealed gas space 35 can be suppressed. This prevents the nitrogen gas serving as the seal gas from solidifying and causing the sealing device 13 to malfunction. Furthermore, by interposing nitrogen gas between the boil-off gas and the atmosphere, it is possible to suppress the first sealed gas from being released into the atmosphere as is.

[0044] Furthermore, in the liquefied hydrogen loading system 1, boil-off gas is stored in the boil-off gas storage tank 43 outside of the loading and unloading period. Then, during the loading and unloading period, the stored boil-off gas can be supplied as seal gas to the sealing device 13. This allows a large amount of seal gas to be supplied to the sealing device 13.

[0045] Furthermore, in the liquefied hydrogen loading system 1, the boil-off gas is compressed and supplied to the boil-off gas storage tank 43, so that a larger amount of boil-off gas can be stored in the boil-off gas storage tank 43. This allows a larger amount of seal gas to be supplied to the sealing device 13 during a period of time.

[0046] Furthermore, in the liquefied hydrogen loading and unloading system 1, the first seal gas in the first seal gas space 34 is discharged from the discharge equipment 15. This allows the first seal gas to be continuously supplied from the seal gas supply system 14 to the first seal gas space 34, thereby preventing the first seal gas from accumulating in the first seal gas space 34 and being cooled by the return gas. In other words, a decrease in the temperature of the first seal gas can be suppressed. This also prevents a decrease in the temperature of the second seal gas, further preventing the nitrogen gas from solidifying and causing the sealing device 13 to malfunction.

[0047] In the liquefied hydrogen loading system 1, the sealing device 13 is provided in the return gas blower 24 included in the loading facility 12. This prevents the return gas blower 24 from becoming stuck due to the solidification of the sealing gas.

[0048] In the boil-off gas transfer system 60, hydrogen, which is a boil-off gas, is used as the first seal gas for the sealing device 13, thereby preventing the first seal gas from liquefying. This prevents the first seal gas from solidifying and causing the sealing device 13 to stop functioning.

[0049] [Second embodiment] The liquefied hydrogen loading system 1A of the second embodiment is similar in configuration to the liquefied hydrogen loading system 1 of the first embodiment. Therefore, the configuration of the liquefied hydrogen loading system 1A of the second embodiment will be mainly described in terms of differences from the liquefied hydrogen loading system 1 of the first embodiment, and the same components will be assigned the same reference numerals and descriptions thereof will be omitted.

[0050] As shown in Fig. 5, the liquefied hydrogen loading and unloading system 1A of the second embodiment includes a hydrogen tank 11, loading and unloading equipment 12, a sealing device 13, a sealing gas supply system 14, and a discharge equipment 15A. The discharge equipment 15A returns the discharged first sealing gas to the sealing gas supply system 14. More specifically, the first sealing gas is discharged from the first sealing gas space 34 to the discharge equipment 15A. The discharge equipment 15A then returns the discharged first sealing gas to the sealing gas supply system 14. More specifically, the discharge equipment 15A includes a mixed gas recovery line 53, a mixed gas blower 54, a hydrogen regeneration device 55, a hydrogen recovery line 56, a vent line 51A, and a valve 52.

[0051] The mixed gas recovery line 53 is connected to the first seal gas space 34 and the second seal gas space 35. The seal gas is discharged from each of the first seal gas space 34 and the second seal gas space 35 to the mixed gas recovery line 53. A mixed gas obtained by mixing the two seal gases flows through the mixed gas recovery line 53. The mixed gas blower 54 is disposed in the mixed gas recovery line 53. The mixed gas blower 54 sends the mixed gas flowing through the mixed gas recovery line 53 downstream (to a hydrogen regeneration device 55, which will be described in detail later).

[0052] The hydrogen regeneration device 55 is connected to the first seal gas space 34 and the second seal gas space 35. More specifically, the hydrogen regeneration device 55 is connected to the first seal gas space 34 and the second seal gas space 35 via the mixed gas recovery line 53. The hydrogen regeneration device 55 separates the first seal gas and the second seal gas from the mixed gas. The hydrogen regeneration device 55 then separates the first seal gas (i.e., hydrogen) from the mixed gas and returns it to the seal gas supply system 14.

[0053] In this embodiment, the hydrogen reclamation device 55 separates the first seal gas and the second seal gas from the mixed gas, for example, as follows. That is, the return gas piping 22 passes through the hydrogen reclamation device 55. Then, in the hydrogen reclamation device 55, heat exchange occurs between the return gas flowing through the return gas piping 22 and the mixed gas. As a result, the hydrogen reclamation device 55 liquefies or solidifies the second seal gas (i.e., nitrogen) of the mixed gas. On the other hand, the first seal gas, which is hydrogen, is maintained in a gaseous state. Therefore, the first seal gas and the second seal gas are separated from the mixed gas in the hydrogen reclamation device 55. Note that the separation method is not limited to the method using cold heat described above, and other methods (e.g., pressure swing adsorption (PSA)) may also be used.

[0054] The hydrogen regeneration device 55 also re-vaporizes the nitrogen, which is the second seal gas that has been liquefied or solidified outside the loading / unloading period. More specifically, nitrogen is liquefied or solidified by the return gas, as described above. Therefore, when the flow of return gas through the return gas piping 22 stops, such as outside the loading / unloading period, the liquefied or solidified nitrogen re-vaporizes.

[0055] The hydrogen recovery line 56 returns the first seal gas, i.e., hydrogen, separated in the hydrogen reclamation device 55 to the seal gas supply system 14. More specifically, the hydrogen recovery line 56 is connected to the hydrogen reclamation device 55 and the compressor 42. The hydrogen separated in the hydrogen reclamation device 55 is guided to the hydrogen recovery line 56. The hydrogen guided to the hydrogen recovery line 56 is sucked into the compressor 42 and compressed. The compressed gas is then sent to the boil-off gas storage tank 43 via the boil-off gas recovery line 41. In this way, the hydrogen separated in the hydrogen reclamation device 55 is stored as compressed gas in the boil-off gas storage tank 43. An open / close valve 56a is provided in the hydrogen recovery line 56. The open / close valve 56a closes the hydrogen recovery line 56 during the loading / unloading period. This prevents the boil-off gas from flowing back into the hydrogen reclamation device 55.

[0056] The vent line 51A discharges the gas flowing into the hydrogen recovery line 56. More specifically, the vent line 51A is connected to the hydrogen recovery line 56 and the atmosphere. The vent line 51A is also provided with a valve 52. The valve 52 is opened when discharging vaporized nitrogen outside of the loading period, and is closed during the loading period. This allows the second seal gas separated in the hydrogen regeneration device 55 to be discharged to the atmosphere.

[0057] <Effects of the liquefied hydrogen loading system> In the liquefied hydrogen loading system 1A, during the loading period, loading is carried out between the hydrogen tank 11 and the tank 2, similar to the liquefied hydrogen loading system 1 of the first embodiment. Also, in the liquefied hydrogen loading system 1A, a first seal gas is supplied from the seal gas supply system 14 to the seal device 13 (see the thick double-dotted line in Figure 5).

[0058] On the other hand, in the liquefied hydrogen loading system 1A, a mixed gas containing a seal gas discharged from each of the first seal gas space 34 and the second seal gas space 35 is introduced into a mixed gas recovery line 53. The mixed gas is then sent to a hydrogen regeneration device 55 by a mixed gas blower 54. The hydrogen regeneration device 55 separates the mixed gas into a first seal gas and a second seal gas. The separated first seal gas, i.e., hydrogen, is drawn into the compressor 42 via a hydrogen recovery line 56 and compressed. The compressed hydrogen is then stored in the boil-off gas storage tank 43. The hydrogen stored in the boil-off gas storage device is supplied again to the first seal gas space 34 via the seal gas supply system 14 as the first seal gas. That is, the separated first seal gas is regenerated as the first seal gas.

[0059] In the liquefied hydrogen loading system 1A of this embodiment, the discharge equipment 15A returns the discharged first seal gas to the seal gas supply system 14, so the first seal gas can be reused. Furthermore, in the liquefied hydrogen loading system 1A, hydrogen can be regenerated from the mixed gas discharged from the sealing device 13.

[0060] In addition, the liquefied hydrogen loading and unloading system 1A of the second embodiment has the same functions and effects as the liquefied hydrogen loading and unloading system 1 of the first embodiment.

[0061] [Third embodiment] As shown in FIG. 6, the liquefied hydrogen loading and unloading system 1B includes a hydrogen tank 11, loading and unloading equipment 12, sealing devices 13 and 13B, a seal gas supply system 14, and a discharge facility 15. The sealing device 13B is provided in a compressor 42, which is an example of a transfer facility in this embodiment. The sealing device 13B is connected to a supply line 44 of the seal gas supply system 14 and to the discharge facility 15 in parallel with the sealing device 13. The sealing device 13B may be connected to a discharge facility 15 separate from the discharge facility 15 connected to the sealing device 13. Boil-off gas is supplied to the sealing device 13B from the seal gas supply system 14 as a first seal gas. The sealing device 13B seals the interior of the compressor 42 from the atmosphere using the first seal gas.

[0062] The structure of the sealing device 13B is similar to that of the sealing device 13. More specifically, the compressor 42 of this embodiment transfers the boil-off gas 11b by an impeller, similar to the return gas blower 24. Therefore, the structure of the sealing device 13B is similar to that of the sealing device 13. Therefore, for the sealing device 13B, refer to the description of the sealing device 13, and a detailed description of the sealing device 13B will be omitted. Furthermore, in the liquefied hydrogen loading system 1B, the sealing device 13B, together with the hydrogen tank 11 and the compressor 42 (more specifically, the seal gas supply system 14), constitute a boil-off gas transfer system 60B.

[0063] In the boil-off gas transfer system 60B, hydrogen, which is the boil-off gas 11b, is used as the first seal gas of the sealing device 13B, thereby preventing the first seal gas from liquefying, which prevents the first seal gas from solidifying and causing the sealing device 13B to malfunction.

[0064] In the boil-off gas transfer system 60B, a seal device 13B is provided in the compressor 42 that sends the boil-off gas 11b to the boil-off gas storage tank 43. This prevents the seal gas from solidifying and causing the compressor 42 to stop working. This allows the boil-off gas 11b to continue being sent to the boil-off gas storage tank 43.

[0065] In addition, the liquefied hydrogen loading system 1B and the boil-off gas transfer system 60B have the same effects as the liquefied hydrogen loading system 1 and the boil-off gas transfer system 60 of the first embodiment.

[0066] [Fourth embodiment] <Boil-off gas transfer system> The boil-off gas transfer system 60C shown in FIG. 7 transfers the boil-off gas 11b from the tank 2 to the onshore facility 3. The onshore facility 3 is a facility that uses the boil-off gas 11b as fuel, raw material, or the like, and is a power plant, factory, or the like. In this embodiment, the onshore facility 3 is a power generation plant that generates power using hydrogen. Note that the onshore facility 3 does not necessarily need to be equipped with the tank 2 described above. The boil-off gas transfer system 60C includes a hydrogen tank 11, transfer equipment 12C, a sealing device 13C, a sealing gas supply system 14, and discharge equipment 15.

[0067] The transfer equipment 12C transfers the boil-off gas 11b vaporized in the hydrogen tank 11. More specifically, the transfer equipment 12C is connected to the hydrogen tank 11 and the onshore facility 3. In this embodiment, the transfer equipment 12C is connected to the hydrogen tank 11 in parallel with the seal gas supply system 14. The transfer equipment 12C also compresses the boil-off gas 11b vaporized in the hydrogen tank 11 and transfers it to the onshore facility 3. In this embodiment, the transfer equipment 12C is a compressor. The transfer equipment 12C is similar in structure to the compressor 42 and the return gas blower 24. Therefore, the structure of the sealing device 13C is also similar to that of the sealing device 13. Therefore, for the structures of the transfer equipment 12C and the sealing device 13C, refer to the explanations of the structures of the return gas blower 24 and the sealing device 13, and detailed explanations thereof will be omitted.

[0068] In the boil-off gas transfer system 60C, the transfer equipment 12C is a compressor that compresses the boil-off gas 11b and transfers it to the onshore facility 3. This prevents the seal gas from solidifying and causing the transfer equipment 12C to stop working. This allows the boil-off gas 11b to continue being sent to the onshore facility 3.

[0069] In addition, the boil-off gas transfer system 60C has the same effects as the boil-off gas transfer system 60 of the first embodiment.

[0070] [Other embodiments] In the first to third embodiments, the liquefied hydrogen loading and unloading systems 1, 1A, 1B are facilities for loading and unloading liquefied hydrogen to and from a loading ship (not shown), but they may also be facilities mounted on the loading ship and for loading and unloading liquefied hydrogen between onshore facilities. In this case, the tank mounted on the loading ship serves as the hydrogen tank. The liquefied hydrogen loading and unloading systems 1, 1A, 1B may also be systems for loading and unloading between onshore facilities and transport vehicles. In the liquefied hydrogen loading and unloading systems 1, 1A, 1B, the object that the sealing device 13 seals is the return gas blower 24, but it may also be piping or other equipment included in the loading and unloading facility 12.

[0071] Furthermore, the above-described structures of the sealing devices 13, 13B of the liquefied hydrogen loading and unloading systems 1, 1A, 1B in the first to third embodiments and the sealing device 13C of the boil-off gas transfer system 60C in the fourth embodiment are merely examples, and other structures may also be used. For example, the sealing device 13 may have only the first seal gas space 34 without the second seal gas space 35, as long as it seals the inside of the loading and unloading facility 12 from the atmosphere using at least the first seal gas.

[0072] Furthermore, in the first to fourth embodiments, the seal gas supply system 14 includes the boil-off gas storage tank 43, but this is not necessarily required. For example, part of the boil-off gas may be supplied to the sealing device 13 as the first seal gas during the loading and unloading period. Furthermore, in the first to third embodiments, the boil-off gas stored in the boil-off gas storage tank 43 does not necessarily need to be supplied only to the sealing devices 13, 13B, and 13C, but may also be supplied to the onshore facility 3.

[0073] Although the return gas blower 24 and the compressor 42 are given as examples of the transfer equipment in the boil-off gas transfer systems 60, 60B, and 60C of the first to fourth embodiments, a pump may also be used. The transfer equipment may be any other equipment capable of transferring the boil-off gas 11b, particularly capable of pressurizing the transferred boil-off gas 11b. Although the boil-off gas transfer system 60C of the fourth embodiment includes one transfer equipment 12C, it may also include multiple transfer equipment 12C. A sealing device 13C is provided in all or at least one of the multiple transfer equipment 12C. The compressor of the transfer equipment 12C is not limited to a centrifugal compressor having an impeller, but may be another type of compressor, such as a reciprocating compressor.

[0074] From the above description, many modifications and other embodiments of the present invention will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and is provided for the purpose of teaching those skilled in the art the best mode for carrying out the present invention. Details of the structure and / or function thereof may be substantially changed without departing from the spirit of the present invention.

Claims

1. a hydrogen tank for storing liquefied hydrogen; loading and unloading equipment for loading and unloading liquefied hydrogen into the hydrogen tank; a sealing device provided in the cargo handling facility and configured to seal between the inside of the cargo handling facility and the atmosphere using a first seal gas; a seal gas supply system that supplies boil-off gas vaporized in the hydrogen tank to the seal device as a first seal gas.

2. the sealing device has a first sealing gas space and a second sealing gas space arranged between the inside of the cargo handling facility and the atmosphere side, the first seal gas space is supplied with a first seal gas from the seal gas supply system, 2. The liquefied hydrogen loading and unloading system according to claim 1, wherein the second seal gas space is disposed on the atmospheric side relative to the first seal gas space, and a second seal gas flows through the second seal gas space.

3. the seal gas supply system has a boil-off gas storage tank, 3. The liquefied hydrogen loading system according to claim 1, wherein the boil-off gas storage tank stores boil-off gas and is connected to the sealing device.

4. the seal gas supply system has a compressor, The liquefied hydrogen loading system according to claim 3, wherein the compressor compresses the boil-off gas supplied to the boil-off gas storage tank.

5. Further provided with a discharge facility, the sealing device has a first sealing gas space arranged between the inside of the cargo handling facility and the atmosphere side, the first seal gas space is supplied with a first seal gas from the seal gas supply system, 5. The liquefied hydrogen loading and unloading system according to claim 1, wherein the discharge facility is connected to the first seal gas space and discharges the first seal gas supplied to the first seal gas space.

6. The liquefied hydrogen loading and unloading system according to claim 5 , wherein the discharge facility returns the discharged first seal gas to the seal gas supply system.

7. the sealing device has the first seal gas space and the second seal gas space arranged between the inside of the cargo handling facility and the atmosphere side, the first seal gas space is supplied with a first seal gas from the seal gas supply system, the second seal gas space is disposed on the atmospheric side of the first seal gas space, and a second seal gas flows through the second seal gas space; the discharge facility includes a hydrogen regeneration device that is connected to the first seal gas space and the second seal gas space and separates the first seal gas from the second seal gas; The hydrogen regeneration device is guided to a mixed gas of the first seal gas and the second seal gas discharged from each of the first seal gas space and the second seal gas space, separates the first seal gas from the mixed gas, and returns it to the seal gas supply system. The liquefied hydrogen loading system described in claim 6.

8. the loading and unloading facility includes a return gas blower that sends boil-off gas to a delivery tank that delivers liquefied hydrogen to the hydrogen tank, 8. The liquefied hydrogen loading and unloading system according to claim 1, wherein the sealing device is provided in the return gas blower.

9. a hydrogen tank for storing liquefied hydrogen; a transfer facility for transferring the boil-off gas vaporized in the hydrogen tank; a sealing device provided in the transfer facility and configured to seal between the inside of the transfer facility and the atmosphere using a first seal gas; A boil-off gas transfer system, wherein the sealing device is supplied with boil-off gas as a first sealing gas.

10. a seal gas supply system including the transfer facility and a boil-off gas storage tank, and supplying the boil-off gas to the sealing device as a first seal gas; the boil-off gas storage tank stores the boil-off gas transferred by the transfer equipment, The boil-off gas transfer system according to claim 9 , wherein the seal gas supply system supplies the boil-off gas in the boil-off gas storage tank to the seal device as a first seal gas.

11. a seal gas supply system that supplies boil-off gas vaporized in the hydrogen tank to the seal device as a first seal gas; The boil-off gas transfer system according to claim 9 , wherein the transfer facility is a compressor that compresses the boil-off gas and transfers it to an onshore facility.

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