Equipment maintenance methods, liquefied hydrogen system

Abstract

To provide a maintenance method for a device that can prevent nitrogen gas from solidifying when separating the device from a flow passage for liquefied hydrogen.SOLUTION: In a maintenance method for a device, a worker makes hydrogen gas flow into a first portion LS1, a second portion LS2, a third portion LS3, and a fourth portion LS4 to discharge liquefied hydrogen. After that, the worker makes nitrogen gas flow into the second portion LS2 and the third portion LS3 to discharge the hydrogen gas. When the second portion LS2 and the third portion LS3 are filled with the nitrogen gas, the worker divides a flow passage LS in a first joint part LT1 and a second joint part LT2 to detach a pump 50.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present disclosure relates to a maintenance method for equipment handling liquefied hydrogen.

Background Art

[0002] As a technology for handling cryogenic liquefied gas, Patent Document 1 discloses an LNG shipping method from an LNG receiving terminal tank and an apparatus therefor.

[0003] In this technology, a lorry truck is connected to an LNG receiving terminal via a flexible hose. When the loading operation of LNG from the LNG receiving terminal to the lorry truck is completed, nitrogen gas is flowed into the flexible hose from a nitrogen gas supply facility, so that the LNG remaining in the flexible hose is purged, and the lorry truck is disconnected from the LNG receiving terminal.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the technology described in Patent Document 1, when disconnecting a lorry truck from an LNG receiving terminal, nitrogen gas is used for purging. However, when applying such a purging technology to equipment handling liquefied hydrogen, nitrogen may solidify due to the cold heat of liquefied hydrogen. [[ID=…]] An object of the present disclosure is to provide a maintenance method for equipment capable of preventing nitrogen gas from solidifying when separating the equipment from a liquefied hydrogen flow path.

Means for Solving the Problems

[0007] Note: There seems to be an incomplete tag ID in the original text at line 41 which is maintained as

[0006] in the translation. If this is an error in the original, it should be corrected for a more accurate translation. Also, the text between lines 40 and 43 in the original has some consecutive tags without content which are translated as is for consistency.A method for maintaining equipment according to one aspect of the present disclosure is a method for maintaining equipment in a flow path having a first valve, a second valve, equipment, a third valve, and a fourth valve arranged in order along the direction in which liquefied hydrogen flows, comprising: filling the space between the first valve and the fourth valve of the flow path with hydrogen gas; filling the space between the second valve and the third valve of the flow path with nitrogen gas from a state in which the space between the first valve and the fourth valve of the flow path is filled with hydrogen gas; and, with the space between the second valve and the equipment and the space between the third valve and the equipment respectively being separated and sealed, thereby separating the equipment from the flow path. [Effects of the Invention]

[0008] According to this disclosure, it is possible to provide a maintenance method for equipment that can prevent nitrogen gas from solidifying when separating the equipment from a liquid hydrogen flow path. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an overall schematic diagram of the liquefied hydrogen system covered by this disclosure. [Figure 2] Figure 2 is an enlarged schematic diagram of a liquefied hydrogen system according to one embodiment of the present disclosure, showing how liquefied hydrogen flows through the flow path. [Figure 3] Figure 3 is a flowchart of a maintenance method for equipment according to one embodiment of the present disclosure. [Figure 4] Figure 4 is an enlarged schematic diagram of a liquefied hydrogen system according to one embodiment of the present disclosure, showing a state in which a part of the flow path is replaced with hydrogen gas. [Figure 5] Figure 5 is an enlarged schematic diagram of a liquefied hydrogen system according to one embodiment of the present disclosure, showing a state in which a portion of the flow path is further replaced with nitrogen gas. [Figure 6]Figure 6 is an enlarged schematic diagram of a liquefied hydrogen system according to one embodiment of the present disclosure, showing the equipment separated from the flow path. [Figure 7] Figure 7 is an enlarged schematic diagram of a liquefied hydrogen system according to the first modified embodiment of the present disclosure, showing a state in which a portion of the flow path is replaced with hydrogen gas and nitrogen gas. [Figure 8] Figure 8 is an enlarged schematic diagram of a liquefied hydrogen system according to a second modified embodiment of the present disclosure, showing a state in which a portion of the flow path is replaced with hydrogen gas and nitrogen gas. [Modes for carrying out the invention]

[0010] Hereinafter, with reference to the drawings, embodiments of the maintenance method for the equipment according to this disclosure will be described in detail. The equipment according to this disclosure consists of components and devices for handling liquefied hydrogen. The following embodiments will be described based on an example in which a pump is used as the equipment.

[0011] Figure 1 is an overall schematic diagram of the liquefied hydrogen system 1S covered by this disclosure. The liquefied hydrogen system 1S comprises a liquefied hydrogen tank 100, hydrogen utilization equipment 101, and a plurality of pumps 50. The liquefied hydrogen tank 100, the hydrogen utilization equipment 101, and the plurality of pumps 50 are connected by a flow path LS.

[0012] The liquefied hydrogen tank 100 is a tank capable of storing liquefied hydrogen and is located on land. For example, the liquefied hydrogen tank 100 is a flat-bottomed tank installed on land. The hydrogen utilization equipment 101 is equipment that uses the liquefied hydrogen stored in the liquefied hydrogen tank 100. For example, the hydrogen utilization equipment 101 includes a tanker truck for transporting the liquefied hydrogen. Multiple pumps 50 have the function of sending the liquefied hydrogen stored in the liquefied hydrogen tank 100 to the hydrogen utilization equipment 101. As shown in Figure 1, in this embodiment, multiple pumps 50 are arranged in parallel.

[0013] The liquefied hydrogen system 1S further includes two detachable mechanisms 1. Each detachable mechanism 1 separates the portion including the pump 50 from the flow path LS during maintenance of the pump 50.

[0014] Next, taking the vicinity of one of the pumps 50 in FIG. 1 as an example, the configuration and function of the detachable mechanism 1 will be described in detail. FIG. 2 is a schematic overview of the liquefied hydrogen system 1S according to the present embodiment, showing the state in which liquefied hydrogen flows through the flow path LS.

[0015] The detachable mechanism 1 includes a first valve 91, a second valve 92, a third valve 93, and a fourth valve 94.

[0016] The first valve 91, the second valve 92, the third valve 93, and the fourth valve 94 are arranged in order from the liquefied hydrogen tank 100 side. Each valve opens and closes a part of the flow path LS. The aforementioned pump 50 is arranged between the second valve 92 and the third valve 93.

[0017] Hereinafter, in the flow path LS, the portion between the first valve 91 and the second valve 92 is called the first portion LS1, the portion between the second valve 92 and the pump 50 is called the second portion LS2, the portion between the pump 50 and the third valve 93 is called the third portion LS3, and the portion between the third valve 93 and the fourth valve 94 is called the fourth portion LS4.

[0018] The detachable mechanism 1 further includes a hydrogen supply / discharge unit 70, a hydrogen supply / discharge unit 71, a nitrogen supply unit 80, and a nitrogen discharge unit 81.

[0019] Each supply / discharge unit supplies gas to the flow path LS and discharges gas from the flow path LS. Specifically, the hydrogen supply / discharge unit 70 communicates with the first portion LS1 and supplies hydrogen gas to the flow path LS. Also, the hydrogen supply / discharge unit 70 discharges hydrogen gas from the first portion LS1. The hydrogen supply / discharge unit 70 includes a hydrogen gas tank 70A, a flow path 70B, and a hydrogen valve 70C. The hydrogen gas tank 70A stores hydrogen gas. The flow path 70B communicates the hydrogen gas tank 70A and the first portion LS1. The hydrogen valve 70C opens and closes the flow path 70B.

[0020] The hydrogen supply / discharge unit 71 communicates with the fourth part LS4 and supplies hydrogen gas to the flow path LS. Also, the hydrogen supply / discharge unit 71 discharges hydrogen gas from the fourth part LS4. The hydrogen supply / discharge unit 71 includes a hydrogen gas tank 71A, a flow path 71B, and a hydrogen valve 71C. The structures and functions of these members are the same as those of the respective members of the hydrogen supply / discharge unit 70.

[0021] The nitrogen supply unit 80 communicates with the second part LS2 of the flow path LS. In particular, the nitrogen supply unit 80 communicates directly with the second part LS2 without passing through the first part LS1, and supplies nitrogen gas to the flow path LS. The nitrogen supply unit 80 includes a nitrogen gas tank 80A, a flow path 80B, and a nitrogen valve 80C. The nitrogen gas tank 80A stores nitrogen gas. The flow path 80B communicates the nitrogen gas tank 80A and the second part LS2. The nitrogen valve 80C opens and closes the flow path 80B.

[0022] The nitrogen discharge unit 81 communicates with the third part LS3 of the flow path LS and discharges nitrogen gas from the flow path LS. The nitrogen discharge unit 81 includes a nitrogen gas tank 81A, a flow path 81B, and a nitrogen valve 81C. The nitrogen gas tank 81A stores nitrogen gas. The flow path 81B communicates the nitrogen gas tank 81A and the third part LS3. The nitrogen valve 81C opens and closes the flow path 81B.

[0023] The attachment / detachment mechanism 1 further includes a pressure gauge 61, a thermometer 62, a pressure gauge 63, and a thermometer 64. The pressure gauge 61 detects the pressure of the first part LS1, and the thermometer 62 detects the temperature of the first part LS1. Similarly, the pressure gauge 63 detects the pressure of the fourth part LS4, and the thermometer 64 detects the temperature of the fourth part LS4.

[0024] The attachment / detachment mechanism 1 further includes a first joint part LT1 and a second joint part LT2. The pump 50 can be attached to and detached from the flow path LS by the first joint part LT1 and the second joint part LT2. In the present embodiment, the first joint part LT1 and the second joint part LT2 have a bayonet joint structure. Note that any joint structure such as a flange joint can be adopted for the first joint part LT1 and the second joint part LT2.

[0025] Next, the procedure for removing the pump 50 from the flow path LS of the liquefied hydrogen system 1S and performing maintenance on the pump 50 will be described with reference to Figures 2 to 6. Figure 3 is a flowchart of the maintenance method for the pump 50. Figure 4 is an enlarged schematic diagram of the liquefied hydrogen system 1S according to this embodiment, showing a state in which a part of the flow path LS has been replaced with hydrogen gas. Similarly, Figure 5 shows a state in which a part of the flow path LS has been further replaced with nitrogen gas. Figure 6 shows a state in which the pump 50 has been separated from the flow path LS. In each figure, a valve painted white means that the valve is open, and a valve painted black means that the valve is closed.

[0026] As shown in step S01 of Figures 2 and 3, when the pump 50 is operational, the first valve 91, second valve 92, third valve 93, and fourth valve 94 are all open, and the hydrogen valve 70C, nitrogen valve 80C, nitrogen valve 81C, and hydrogen valve 71C are all closed. In this state, when the pump 50 is activated, liquefied hydrogen flows through the flow path LS.

[0027] When separating pump 50 from flow path LS for maintenance, with flow path LS filled with liquefied hydrogen, the worker closes the first valve 91 and the fourth valve 94 as shown in step S02 of Figure 3 and in Figure 4, and opens the hydrogen valve 70C and the hydrogen valve 71C respectively, allowing room temperature hydrogen gas from the hydrogen gas tank 70A to flow into the first section LS1 of flow path LS. As a result, the hydrogen gas flows into the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4, and liquid hydrogen is discharged from the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4 to the hydrogen supply and discharge section 71. In other words, the liquefied hydrogen in the first section LS1 to the fourth section LS4 is replaced with room temperature hydrogen gas. After this, the worker closes the hydrogen valve 70C and the hydrogen valve 71C.

[0028] Next, with hydrogen gas flowing into the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4, the operator closes the second valve 92 and the third valve 93, respectively, as shown in step S03 of Figure 3 and in Figure 5. As a result, the first section LS1 and the fourth section LS4 are filled with hydrogen gas at room temperature. In this state, the operator opens the nitrogen valve 80C and the nitrogen valve 81C, respectively. As a result, nitrogen gas flows into the second section LS2 and the third section LS3 from the nitrogen supply unit 80, and hydrogen gas is discharged from the second section LS2 and the third section LS3 to the nitrogen discharge unit 81. In other words, the hydrogen gas in the second section LS2 and the third section LS3 is replaced with nitrogen gas. After this, the operator closes the nitrogen valve 80C and the nitrogen valve 81C.

[0029] With the second section LS2 and the third section LS3 filled with nitrogen gas, the worker separates the first joint section LT1 and the second joint section LT2, as shown in step S04 of Figure 3 and Figure 6, and removes the pump 50 from the flow path LS. At this time, the flow path LS is sealed at each joint section, so that the second section LS2 and the third section LS3 are sealed while filled with nitrogen gas. Once the pump 50 is separated from the flow path LS as described above, the worker can perform maintenance on the pump 50.

[0030] After the maintenance of pump 50 is completed, the worker reconnects pump 50 to the flow path LS at the first joint LT1 and the second joint LT2. Then, the worker performs the reverse of the removal process described above. Specifically, the worker replaces pump 50, the second valve 92, and the third valve 93 with nitrogen gas to prevent mixing of air and hydrogen gas. More specifically, with the second valve 92 and the third valve 93 closed, the worker opens the nitrogen valve 80C and the nitrogen valve 81C to allow nitrogen gas to flow into pump 50, the second section LS2, and the third section LS3, replacing the air with nitrogen gas. Then, the worker opens the second valve 92 and the third valve 93 to allow hydrogen gas to flow back into the second section LS2 and the third section LS3. Next, the worker opens the first valve 91 and the fourth valve 94 to allow liquefied hydrogen to flow into the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4. As a result, the pump 50 can be restarted. The opening and closing of each valve during the removal and installation of the pump 50 may be performed automatically.

[0031] As described above, in this embodiment, the first valve 91, the second valve 92, the first joint LT1, the pump 50, the second joint LT2, the third valve 93, and the fourth valve 94 are arranged in order along the direction in which liquefied hydrogen flows from the liquefied hydrogen tank 100 to the hydrogen usage equipment 101 in the flow path LS. When separating the pump 50 from this flow path LS, the operator, with the flow path LS filled with liquefied hydrogen, introduces hydrogen gas into the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4 to discharge the liquefied hydrogen. Next, with hydrogen gas flowing into the first section LS1, the second section LS2, the third section LS3, and the fourth section LS4, the operator introduces nitrogen gas into the second section LS2 and the third section LS3 to discharge the hydrogen gas. Furthermore, with nitrogen gas flowing into the second section LS2 and the third section LS3, the worker separates and seals the flow path LS using the first joint section LT1 and the second joint section LT2, thereby separating the pump 50.

[0032] This method allows the pump 50 to be safely removed from the flow path LS while it is purged with nitrogen gas. Since the melting point of nitrogen gas is -210°C, it tends to solidify when exposed to the cold of liquefied hydrogen at -253°C. However, in this embodiment, even when liquefied hydrogen is filled on the side of the liquefied hydrogen tank 100 beyond the first valve 91 and on the side of the hydrogen usage equipment 101 beyond the fourth valve 94, hydrogen gas is filled into the first section LS1 and the fourth section LS4, respectively. This prevents the cold of liquefied hydrogen at approximately -253°C from being transferred to the nitrogen gas in the second section LS2 and the third section LS3. In other words, the first section LS1 and the fourth section LS4 can function as temperature buffers. As a result, damage to valves and flow paths caused by the transfer of cold from liquefied hydrogen to nitrogen gas and the solidification of nitrogen gas within each valve and flow path can be prevented. Therefore, the pump 50 can be removed from the flow path LS for maintenance purposes by using nitrogen gas, which is cheaper than helium, which is generally used as an inert gas. Therefore, maintenance of the pump 50 can be performed regardless of the helium gas supply. As a result, the maintenance cost of the liquefied hydrogen system 1S can also be reduced. Furthermore, after maintenance, the operation of the pump 50 can be quickly restarted by flowing liquefied hydrogen again into the limited area from the first valve 91 to the fourth valve 94.

[0033] Furthermore, in this embodiment, when the operator fills the flow path LS between the first valve 91 and the fourth valve 94 with hydrogen gas, the operator closes the first valve 91 and the fourth valve 94 respectively, and introduces hydrogen gas between the first valve 91 and the fourth valve 94 to discharge liquefied hydrogen. In this way, the hydrogen gas filling operation and the liquefied hydrogen discharge operation can be performed efficiently while pushing out the liquefied hydrogen with hydrogen gas. Similarly, when the operator fills the flow path LS between the second valve 92 and the third valve 93 with nitrogen gas, the operator closes the second valve 92 and the third valve 93 respectively, and introduces nitrogen gas between the second valve 92 and the third valve 93 to discharge hydrogen gas. In this case as well, the nitrogen gas filling operation and the hydrogen gas discharge operation can be performed efficiently while pushing out the hydrogen gas with nitrogen gas.

[0034] Furthermore, in this embodiment, the nitrogen supply unit 80 for supplying nitrogen gas to the second section LS2 and the third section LS3 is directly connected to the second section LS2 of the flow path LS. Therefore, compared to the case where nitrogen gas is supplied to the second section LS2 and the third section LS3 via the first section LS1 and the fourth section LS4, no nitrogen gas remains in the first section LS1 and the fourth section LS4, and solidification of the remaining nitrogen gas can be prevented. In addition, this configuration can prevent leakage of hydrogen gas from the first section LS1 and the fourth section LS4, which act as temperature buffers, into the atmosphere, and also prevents air from entering the temperature buffers.

[0035] In Figures 5 and 6, with the first section LS1 filled with hydrogen gas, the operator can adjust the amount of hydrogen gas filled in the first section LS1 by adjusting the opening and closing of the hydrogen valve 70C according to the detection results of the pressure gauge 61 and the thermometer 62. Similarly, with the fourth section LS4 filled with hydrogen gas, the operator can adjust the amount of hydrogen gas filled in the fourth section LS4 by adjusting the opening and closing of the hydrogen valve 70C according to the detection results of the pressure gauge 63 and the thermometer 64. In each of the above adjustment operations, the operator may also adjust the amount of hydrogen gas filled according to the detection result of either temperature or pressure.

[0036] The above adjustment procedure will be explained in detail using the first section LS1 in Figure 6 as an example. In the first section LS1, the hydrogen gas tends to contract due to the propagation of the cold heat of the liquefied hydrogen, causing the pressure to drop. If the pressure in the first section LS1 is left low in this manner, the pressure difference between the first section LS1 and the second section LS2 may cause nitrogen gas to flow into the first section LS1 through the second valve 92, and there is a risk that it will solidify within the first section LS1 due to the cold heat of the liquefied hydrogen. In this embodiment, to prevent such problems, if the pressure in the first section LS1 drops, the operator can supply hydrogen gas from the hydrogen supply / discharge section 70 to maintain the pressure in the first section LS1.

[0037] On the other hand, if the temperature of the first section LS1 drops significantly, nitrogen may liquefy and solidify between the second valve 92 and the first joint section LT1. When nitrogen gas liquefies in this way, negative pressure may be generated, potentially causing hydrogen gas to leak from the first section LS1 to the second section LS2. If the hydrogen gas leaked into the second section LS2 re-vaporizes due to heat input from the atmosphere, its pressure will increase, potentially causing further hydrogen gas to leak into the atmosphere. In this embodiment, if the temperature of the first section LS1 drops, the operator can raise the temperature of the first section LS1 by repeatedly supplying and releasing hydrogen gas through the hydrogen supply and discharge section 70. For example, the operator can increase the amount of hydrogen gas supplied to the first section LS1 to raise its temperature, and as the pressure increases accordingly, they can adjust the pressure of the first section LS1 by slightly releasing hydrogen gas from the first section LS1. Note that measuring instruments such as the pressure gauge 61 and thermometer 62 are not essential in this disclosure. Furthermore, the above adjustment process may be performed automatically.

[0038] Furthermore, in this embodiment, as shown in Figure 4, when filling the space between the first valve 91 and the fourth valve 94 with hydrogen gas, the operator introduces hydrogen gas between the first valve 91 and the second valve 92 and discharges liquefied hydrogen from between the third valve 93 and the fourth valve 94. Therefore, the pump 50 can be used as a hydrogen gas flow path to efficiently fill the space between the first valve 91 and the fourth valve 94 with hydrogen gas.

[0039] Similarly, in this embodiment, as shown in Figure 5, when filling the space between the second valve 92 and the third valve 93 with nitrogen gas, the operator introduces nitrogen gas between the second valve 92 and the pump 50, and discharges hydrogen gas from between the pump 50 and the third valve 93. Therefore, the pump 50 can be used as a flow path for nitrogen gas, allowing for efficient filling of the space between the second valve 92 and the third valve 93 with nitrogen gas. Furthermore, since the pump 50 can be replaced with nitrogen gas during this process, the pump 50 can be safely removed.

[0040] Furthermore, as in this embodiment, when the pump 50, which handles liquefied hydrogen, is separated from the flow path LS, maintenance may take several days. Even in such cases, as shown in Figure 1 of this embodiment, since the pumps 50 are arranged in parallel, the transfer of liquefied hydrogen can be continued by operating the other pumps while one pump is being maintained. In addition, as described above, even if the pump 50 is separated from the flow path LS for a long period of time, the operator can adjust the amount of hydrogen gas filling the first section LS1 and the fourth section LS4, thereby reliably preventing the transfer of cold or heat to the nitrogen gas in the second section LS2 and the third section LS3, even during long-term maintenance.

[0041] [Modified Embodiment] The above describes the maintenance method for the equipment relating to this disclosure, but this disclosure is not limited to the embodiments described above. For example, the following modified embodiments can be taken for the above-described maintenance method for the equipment.

[0042] In the above embodiment, the valves and the like were described in a manner in which each valve and the like are arranged in order along the direction in which liquefied hydrogen flows from the liquefied hydrogen tank 100 toward the hydrogen utilization equipment 101. However, the direction in which liquefied hydrogen flows may also be from the hydrogen utilization equipment 101 toward the liquefied hydrogen tank 100. In this case, the first valve 91, the second valve 92, the first joint LT1, the pump 50, the second joint LT2, the third valve 93, and the fourth valve 94 should be arranged in order from the hydrogen utilization equipment 101 toward the liquefied hydrogen tank 100.

[0043] Furthermore, although the above embodiment was described in which hydrogen gas and nitrogen gas are supplied from the second valve 92 side to the third valve 93 side through the pump 50, respectively, this disclosure is not limited thereto. The attachment / detachment mechanism 1 may have its own supply and discharge passages for hydrogen gas and nitrogen gas on both sides of the pump 50.

[0044] Figure 7 is an enlarged schematic diagram of a liquefied hydrogen system according to the first modified embodiment of this disclosure, showing a state in which a portion of the flow path LS is replaced with hydrogen gas and nitrogen gas, respectively. This modified embodiment differs from the previous embodiment in the supply path of nitrogen gas to the flow path LS, and will be explained focusing on these differences.

[0045] The liquefied hydrogen system 1S includes a seal gas passage 51 and a valve 52 instead of the nitrogen supply unit 80 and nitrogen discharge unit 81 according to the previous embodiment. The seal gas passage 51 supplies a seal gas consisting of nitrogen into the gaps inside the pump 50 to prevent liquefied hydrogen from leaking inside the pump 50. The operator can supply the above nitrogen gas to the passage LS by switching the opening and closing of the valve 52.

[0046] In this modified embodiment, similar to the previous embodiment, with hydrogen gas filled between the first valve 91 and the fourth valve 94, when the operator closes the second valve 92 and the third valve 93 and opens valve 52, nitrogen gas flows from the pump 50 into the flow path between the second valve 92 and the third valve 93. At this time, hydrogen gas is discharged from an unillustrated discharge flow path. Subsequently, similar to the previous embodiment, the operator can separate the flow path LS at the first joint LT1 and the second joint LT2 and remove the pump 50. Even with this configuration, the pump 50 can be safely removed from the flow path LS while preventing the nitrogen gas from solidifying. Thus, the nitrogen gas supply source in this disclosure may also be the pump 50.

[0047] Furthermore, Figure 8 is an enlarged schematic diagram of a liquefied hydrogen system according to a second modified embodiment of the present disclosure, showing a state in which a part of the flow path LS is replaced with hydrogen gas and nitrogen gas. In the previous embodiment, the hydrogen supply and discharge section 70 communicating with the first section LS1 and the hydrogen supply and discharge section 71 communicating with the fourth section LS4 were described as supplying and discharging hydrogen gas through a single passage, but as shown in Figure 8, the hydrogen gas supply passage and the discharge passage may be provided independently.

[0048] Specifically, the attachment / detachment mechanism 1 includes a hydrogen supply unit 75 and a hydrogen adjustment discharge unit 76. The hydrogen supply unit 75 has the function of supplying hydrogen gas to the portion between the first valve 91 and the fourth valve 94. The hydrogen supply unit 75 also has the function of adjusting the amount of hydrogen gas filled in the first portion LS1 by supplying hydrogen gas to the first portion LS1 after the second valve 92 is closed. The hydrogen adjustment discharge unit 76 also has the function of adjusting the amount of hydrogen gas filled in the first portion LS1 by discharging hydrogen gas from the first portion LS1 after the second valve 92 is closed.

[0049] Similarly, the attachment / detachment mechanism 1 includes a hydrogen supply adjustment unit 85 and a hydrogen discharge unit 86. The hydrogen discharge unit 86 has the function of receiving liquefied hydrogen and hydrogen gas from the section between the first valve 91 and the fourth valve 94. The hydrogen discharge unit 86 also has the function of adjusting the amount of hydrogen filled into the fourth section LS4 by receiving hydrogen gas from the fourth section LS4 after the third valve 93 is closed. The hydrogen supply adjustment unit 85 also has the function of adjusting the amount of hydrogen gas filled into the fourth section LS4 by supplying hydrogen gas to the fourth section LS4 after the third valve 93 is closed.

[0050] Even with the configuration described above, the operator can adjust the amount of hydrogen gas supplied from the hydrogen supply unit 75 and the amount of hydrogen gas discharged from the adjustment hydrogen discharge unit 76 according to the detection results of the pressure gauge 61 and the thermometer 62. Furthermore, the operator can adjust the amount of hydrogen gas supplied from the adjustment hydrogen supply unit 85 and the amount of hydrogen gas discharged from the hydrogen discharge unit 86 according to the detection results of the pressure gauge 63 and the thermometer 64. In particular, it is desirable for the operator to increase the amount of hydrogen gas supplied from the hydrogen supply unit 75 when the pressure gauge 61 or thermometer 62 detects a decrease in the hydrogen gas pressure or temperature. The same applies to the adjustment hydrogen supply unit 85.

[0051] [Summary of this disclosure] The specific embodiments described above include disclosures having the following configurations.

[0052] A method for maintaining equipment according to one aspect of the present disclosure is a method for maintaining equipment in a flow path having a first valve, a second valve, equipment, a third valve, and a fourth valve arranged in order along the direction in which liquefied hydrogen flows, comprising: filling the space between the first valve and the fourth valve of the flow path with hydrogen gas; filling the space between the second valve and the third valve of the flow path with nitrogen gas from a state in which the space between the first valve and the fourth valve of the flow path is filled with hydrogen gas; and, with the space between the second valve and the equipment and the space between the third valve and the equipment respectively being separated and sealed, thereby separating the equipment from the flow path.

[0053] According to this method, starting with a flow path filled with liquefied hydrogen, hydrogen gas is filled between the first and fourth valves, and then nitrogen gas is filled between the second and third valves. By then interrupting the flow path between the second valve and the equipment, and between the third valve and the equipment, equipment maintenance can be performed safely. As a result, after maintenance, the equipment can be quickly restarted by flowing liquefied hydrogen again into the limited area from the first to the fourth valves. Furthermore, since the hydrogen gas filled between the first and second valves, and between the third and fourth valves, functions as a temperature buffer, the coldness of the liquefied hydrogen is transferred to the nitrogen gas, preventing the nitrogen gas from solidifying during equipment maintenance.

[0054] In the above method, when filling the space between the first valve and the fourth valve of the flow path with hydrogen gas, the method may further include closing the first valve and the fourth valve, respectively, and discharging the liquefied hydrogen by introducing the hydrogen gas between the first valve and the fourth valve.

[0055] This method allows for efficient hydrogen gas filling and liquefied hydrogen discharge operations.

[0056] In the above method, when filling the space between the second valve and the third valve of the flow path with nitrogen gas, the method may further include closing the second valve and the third valve, respectively, and introducing the nitrogen gas between the second valve and the third valve to discharge the hydrogen gas.

[0057] This method allows for efficient nitrogen gas filling and hydrogen gas discharge operations.

[0058] In the above method, when filling the space between the first valve and the fourth valve of the flow path with hydrogen gas, the hydrogen gas may be further introduced between the first valve and the second valve, and the liquefied hydrogen may be discharged from between the third valve and the fourth valve.

[0059] According to this method, the equipment can be used as a hydrogen gas flow path to efficiently fill the section between the first valve and the fourth valve with hydrogen gas.

[0060] In the above method, when filling the space between the second valve and the third valve of the flow path with nitrogen gas, the nitrogen gas may be further introduced between the second valve and the device, and the hydrogen gas may be discharged from between the device and the third valve.

[0061] According to this method, the equipment can be used as a nitrogen gas flow path, allowing for efficient filling of the section between the second and third valves with nitrogen gas. Furthermore, since the inside of the equipment can be replaced with nitrogen gas during this process, the equipment can be safely removed.

[0062] The above method may further include detecting the temperature and pressure between the first valve and the second valve or between the third valve and the fourth valve while the device is separated from the flow path, and adjusting the amount of hydrogen gas to be filled according to the detection result of at least one of the temperature and pressure.

[0063] According to this method, even if the temperature and pressure of the filled hydrogen gas fluctuate during equipment maintenance, the temperature balance of liquefied hydrogen, hydrogen gas, and nitrogen gas can be stably maintained by adjusting the amount of hydrogen gas filled.

[0064] In the above method, if a decrease in temperature or pressure between the first valve and the second valve, or between the third valve and the fourth valve, is detected, the amount of hydrogen gas to be filled may be increased.

[0065] According to this method, even if the temperature and pressure of the filled hydrogen gas decrease during equipment maintenance, the temperature balance of liquefied hydrogen, hydrogen gas, and nitrogen gas can be maintained more stably by increasing the amount of hydrogen gas filled. [Explanation of Symbols]

[0066] 1. Detachable mechanism 100 liquefied hydrogen tanks 101 Hydrogen-using equipment 1S Liquefied Hydrogen System 50 pumps 61, 63 Pressure gauge 62, 64 thermometer 70, 71 Hydrogen Intake and Exhaust Sections 80 Nitrogen supply unit 81 Nitrogen release section 91 First valve 92 Second valve 93 Third valve 94. Valve No. 4 LS flow path LS1 Part 1 LS2 2nd part LS3 3rd part LS4 Part 4 LT1 First joint section LT2 Second joint section

Claims

1. A method for maintaining equipment in a flow path having a first valve, a second valve, equipment, a third valve, and a fourth valve arranged sequentially along the direction of flow of liquefied hydrogen, The process involves filling the space between the first valve and the fourth valve of the aforementioned flow path with hydrogen gas, From a state in which the hydrogen gas is filled between the first valve and the fourth valve of the flow path, nitrogen gas is filled between the second valve and the third valve of the flow path. With the nitrogen gas filled between the second valve and the third valve of the flow path, the flow path between the second valve and the equipment, and between the third valve and the equipment are separated and sealed, thereby separating the equipment from the flow path. A maintenance method for equipment that includes [the necessary features / features].

2. A method for maintaining equipment according to claim 1, further comprising closing the first valve and the fourth valve, respectively, when filling the flow path between the first valve and the fourth valve with hydrogen gas, and discharging the liquefied hydrogen by introducing the hydrogen gas between the first valve and the fourth valve.

3. A method for maintaining equipment according to claim 1 or 2, further comprising closing the second valve and the third valve, respectively, when filling the space between the second valve and the third valve of the flow path with nitrogen gas, and discharging the hydrogen gas by introducing the nitrogen gas between the second valve and the third valve.

4. A method for maintaining equipment according to claim 2, further comprising introducing the hydrogen gas between the first valve and the second valve and discharging the liquefied hydrogen from between the third valve and the fourth valve when filling the flow path with the hydrogen gas between the first valve and the fourth valve.

5. A method for maintaining equipment according to claim 3, further comprising introducing the nitrogen gas between the second valve and the equipment and discharging the hydrogen gas from between the equipment and the third valve when filling the space between the second valve and the third valve of the flow path with nitrogen gas.

6. A method for maintaining equipment according to any one of claims 1 to 5, further comprising detecting at least one of the temperature and pressure between the first valve and the second valve or between the third valve and the fourth valve while the equipment is separated from the flow path, and adjusting the amount of hydrogen gas to be filled according to the detection result of at least one of the temperature and pressure.

7. A method for maintaining the equipment according to claim 6, wherein when a decrease in temperature or pressure between the first valve and the second valve or between the third valve and the fourth valve is detected, the amount of hydrogen gas to be filled is increased.

8. A channel through which liquefied hydrogen flows, A first valve, a second valve, equipment, a third valve, and a fourth valve are arranged in sequence in the flow path along the direction of flow of liquefied hydrogen. The flow path includes a first receiving section capable of receiving liquefied hydrogen in the region between the first valve and the fourth valve, A first filling section capable of filling the region between the first valve and the fourth valve of the aforementioned flow path with hydrogen gas, The flow path includes a second receiving section capable of receiving hydrogen gas in the region between the second valve and the third valve, The flow path includes a second filling section capable of filling the region between the second valve and the third valve with nitrogen gas, A separation mechanism capable of separating and closing the flow path between the second valve and the device, and between the device and the third valve, respectively. A liquefied hydrogen system equipped with [the following features].

9. The liquefied hydrogen system according to claim 8, wherein, with the first valve and the fourth valve closed, the first filling unit introduces hydrogen gas into the region between the first valve and the fourth valve, thereby pushing out liquefied hydrogen from that region, and the first receiving unit is capable of receiving the pushed-out liquefied hydrogen.

10. The liquefied hydrogen system according to claim 8 or 9, wherein, with the second valve and the third valve closed, the second filling section introduces nitrogen gas into the region between the second valve and the third valve, thereby pushing out hydrogen gas from that region, and the second receiving section is capable of receiving the pushed-out hydrogen gas.

11. The liquefied hydrogen system according to claim 9, wherein the first filling section is arranged to communicate with the region of the flow path between the first valve and the second valve, and the first receiving section is arranged to communicate with the region of the flow path between the third valve and the fourth valve.

12. The liquefied hydrogen system according to claim 10, wherein the second filling section is arranged to communicate with the region of the flow path between the second valve and the equipment, and the second receiving section is arranged to communicate with the region of the flow path between the equipment and the third valve.

13. A detection unit capable of detecting at least one of the temperature and pressure between the first valve and the second valve or between the third valve and the fourth valve, An adjustment unit capable of adjusting the amount of hydrogen gas filled in the flow path according to the detection result of at least one of the temperature and pressure, A liquefied hydrogen system according to any one of claims 8 to 12, further comprising:

14. The liquefied hydrogen system according to claim 13, wherein the adjustment unit increases the amount of hydrogen gas filling in the flow path when it detects that the temperature or pressure in the region between the first valve and the second valve or the region between the third valve and the fourth valve has decreased.

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