Liquefied hydrogen pump system, control method of liquefied hydrogen pump system

Abstract

A liquefied hydrogen pump system has a liquefied hydrogen pump and a control device. The liquefied hydrogen pump has a cylinder, a piston, a rod, a driving portion, and a sealing portion. The sealing portion has a first sealing member, a second sealing member disposed apart from the first sealing member in a direction away from the piston in an axial direction, a flow path portion having one end in communication with a gap between the rod and the cylinder and the other end open to the outside of the cylinder, and an information acquisition portion that acquires information related to a hydrogen concentration in a fluid flowing to the outside of the cylinder through the flow path portion. The control device stops the operation of the liquefied hydrogen pump when it is determined based on the acquired information related to the hydrogen concentration that the hydrogen concentration in the fluid exceeds a predetermined reference value.

Description

Technical Field

[0001] This disclosure relates to a liquefied hydrogen pump system and a control method for the liquefied hydrogen pump system. This application claims priority based on Japanese Patent Application No. 2023-198546, filed on November 22, 2023, the contents of which are incorporated herein by reference. Background Technology

[0002] Reciprocating pumps have been used to date as pumps for compressing liquefied hydrogen. For example, such pumps can pressurize liquefied hydrogen to approximately 90 MPa. Specifically, a reciprocating pump mainly consists of a piston that moves back and forth along its axis and a cylinder that covers the piston from the outside. By the reciprocating movement of the piston within the cylinder, the liquefied hydrogen is compressed and discharged to the outside. The piston is driven by a drive unit. The piston, located inside the cylinder, and the drive unit, located outside the cylinder, are connected by a rod. The rod extends through the inside and outside of the cylinder.

[0003] For example, Patent Document 1 discloses a structure in which multiple sealing components are spaced apart along the axial direction of the rod between the rod and the cylinder. Furthermore, Patent Document 1 discloses a structure for monitoring the pressure of a fluid flow path communicating with the multiple sealing components. In this structure, leakage of liquefied hydrogen through the gap between the sealing components and the rod caused by wear of the sealing components is monitored by detecting a pressure rise in the fluid flow path.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 6982034 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] However, in the aforementioned liquefied hydrogen pump, it is required that even if hydrogen leaks from the liquefied hydrogen pump into the atmosphere, the hydrogen concentration in the surrounding atmosphere be suppressed to below a specified reference value.

[0009] However, in the structure described in Patent Document 1, although it is possible to monitor whether liquefied hydrogen leaks out, it is impossible to detect the hydrogen concentration in the surrounding atmosphere when liquefied hydrogen leaks from the liquefied hydrogen pump into the atmosphere.

[0010] This disclosure was made to solve the above-mentioned problems, and its purpose is to provide a liquefied hydrogen pump system and a control method for the liquefied hydrogen pump system that can suppress the hydrogen concentration in the surrounding atmosphere to below a specified reference value by detecting changes in hydrogen concentration in the event of liquefied hydrogen leakage.

[0011] Technical solutions for solving technical problems

[0012] To address the aforementioned issues, the liquefied hydrogen pump system disclosed herein comprises: a liquefied hydrogen pump that compresses liquefied hydrogen; a control device that controls the operation of the liquefied hydrogen pump, wherein the liquefied hydrogen pump comprises: a cylindrical cylinder extending along an axial direction; a piston reciprocatingly disposed within the cylinder in the axial direction, compressing liquefied hydrogen introduced from the outside into the cylinder and discharging it out of the cylinder; a rod, one end of which is connected to the piston within the cylinder, and the other end of which protrudes out of the cylinder; a drive unit connected to the other end of the rod, which causes the piston to reciprocate within the cylinder along the axial direction via the rod; and a sealing portion comprising: a first sealing member that seals the space between the rod and the cylinder. The system includes: a gap seal; a second sealing component, which is spaced apart from the first sealing component in the axial direction away from the piston, to seal the space between the rod and the cylinder; a flow path formed in the cylinder, one end of which communicates with the gap between the rod and the cylinder between the first and second sealing components, and the other end which opens to the outside of the cylinder; and an information acquisition unit that acquires information related to the hydrogen concentration in the fluid flowing out of the cylinder through the flow path. The control device stops the operation of the liquefied hydrogen pump when it determines, based on the information related to the hydrogen concentration acquired by the information acquisition unit, that the hydrogen concentration in the fluid exceeds a preset reference value.

[0013] The control method for the liquefied hydrogen pump system disclosed herein includes the following steps: obtaining information related to the hydrogen concentration in the fluid flowing out of the cylinder through the flow path; determining, based on the obtained information related to the hydrogen concentration, whether the hydrogen concentration in the fluid exceeds a preset reference value; and stopping the operation of the liquefied hydrogen pump if it is determined that the hydrogen concentration in the fluid exceeds the preset reference value.

[0014] Invention Effects

[0015] According to the liquefied hydrogen pump system and control method of the liquefied hydrogen pump system disclosed herein, in the event of liquefied hydrogen leakage, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a specified reference value by detecting changes in hydrogen concentration. Attached Figure Description

[0016] Figure 1 This is a cross-sectional view showing the schematic structure of the liquefied hydrogen pump system according to an embodiment of the present disclosure.

[0017] Figure 2 This is a cross-sectional view showing the structure of the sealing portion of the liquid hydrogen pump in the liquefied hydrogen pump system of the first embodiment of this disclosure.

[0018] Figure 3 yes Figure 2 Sectional view in direction III-III.

[0019] Figure 4 This is a diagram illustrating the hardware structure of the control device according to an embodiment of the present disclosure.

[0020] Figure 5 It means Figure 4 Functional block diagram of the functional structure of the control device.

[0021] Figure 6 This is a flowchart illustrating the steps of a control method for a liquefied hydrogen pump system according to the first embodiment of this disclosure.

[0022] Figure 7 This is a cross-sectional view showing the structure of the sealing portion of the liquid hydrogen pump in the liquefied hydrogen pump system of the second embodiment of this disclosure.

[0023] Figure 8 This is a graph illustrating an example of the correlation between fluid temperature and fluid flow rate.

[0024] Figure 9 This is a flowchart illustrating the steps of the control method for the liquefied hydrogen pump system according to the second embodiment of this disclosure.

[0025] Figure 10 This is a cross-sectional view showing the structure of the sealing portion of the liquid hydrogen pump in the liquefied hydrogen pump system of the third embodiment of this disclosure.

[0026] Figure 11 This is a flowchart illustrating the steps of a control method for a liquefied hydrogen pump system according to a third embodiment of this disclosure.

[0027] Figure 12 This is a cross-sectional view showing the structure of the sealing portion of the liquid hydrogen pump in the liquefied hydrogen pump system of the first modified embodiment of the present disclosure.

[0028] Figure 13 This is a cross-sectional view showing the structure of the sealing portion of the liquid hydrogen pump in the liquefied hydrogen pump system of the second modified embodiment of the present disclosure. Detailed Implementation

[0029] Hereinafter, the liquefied hydrogen pump system and the control method for implementing the present disclosure will be described with reference to the accompanying drawings. However, the present disclosure is not limited to these embodiments.

[0030] (First Implementation)

[0031] (Structure of a liquefied hydrogen pump system)

[0032] like Figure 1 As shown, the liquefied hydrogen pump system 100 includes a liquefied hydrogen pump 101 and a control device 60.

[0033] (Structure of a liquefied hydrogen pump)

[0034] The liquefied hydrogen pump 101 is a reciprocating pump used to pressurize liquefied hydrogen to a high pressure (e.g., around 90 MPa). The liquefied hydrogen pump 101 mainly includes a piston 1, a cylinder 2, a rod 8, a drive unit 3, a housing 4, and a sealing unit 9A.

[0035] (The structure of a piston)

[0036] The piston 1 has a cylindrical piston body 10 centered on an axis O extending in the vertical direction, a wear ring 11 mounted on the piston body 10, and piston rings 12. The radial dimension of the piston body 10 is constant throughout the entire region along the axis O. The wear ring 11 is disposed at the front end of the piston body 10. The wear ring 11 is annular in shape centered on the axis O and is formed of resin material.

[0037] A wear-resistant ring 11 is provided at the lower end of the piston body 10, and another wear-resistant ring 11 is provided at intervals along the axis O from this wear-resistant ring 11. Between these pairs of wear-resistant rings 11, a plurality of piston rings 12 (for example, six) are arranged at intervals along the axis O. The wear-resistant rings 11 are provided to guide the piston body 10 along the inner circumferential surface of the cylinder body 20 (described later). On the other hand, the piston rings 12 are provided to maintain liquid and gas tightness between themselves and the inner circumferential surface of the cylinder body 20.

[0038] (Cylinder structure)

[0039] Cylinder 2 has a cylinder body 20 and a sealing body 90 (described later) (see reference). Figure 2 The cylinder body 20 is cylindrical, extending along the axis O. The cylinder body 20 is a bottomed cylinder that covers the piston 1 from its outer periphery. The piston 1 is inserted into the cylinder body 20 through an opening at the top. The space inside the cylinder body 20 below the piston 1 is a compression chamber 21. A check valve 5 is provided at the bottom of the cylinder body 20 for guiding liquefied hydrogen into the compression chamber 21. This check valve 5 allows liquefied hydrogen to flow only from the outside of the cylinder body 20 towards the inside of the compression chamber 21. In other words, even if the pressure in the compression chamber 21 increases, liquefied hydrogen will not flow out of the cylinder body 20 through the check valve 5.

[0040] A discharge pipe 6 is connected to the side of the cylinder body 20 facing the compression chamber 21. The discharge pipe 6 is provided for removing the liquefied hydrogen compressed in the compression chamber 21 to the outside of the cylinder body 20. A discharge valve 7 is provided midway through the discharge pipe 6. When the pressure in the compression chamber 21 reaches a predetermined value or higher, the discharge valve 7 allows the liquefied hydrogen to flow only in the direction from the compression chamber 21 toward the outside.

[0041] (The structure of the rod)

[0042] Rod 8 connects piston 1 and drive unit 3. Rod 8 is formed as a cylinder extending along axis O. One end of rod 8 is connected to piston body 10 of piston 1 inside cylinder 2. The other end of rod 8 protrudes upward from the upper end of cylinder 2. The other end of rod 8 is connected to swing shaft 35 of drive unit 3 inside housing 37 of drive unit 3. Piston 1 and rod 8 can move along axis O within cylinder 2.

[0043] (Structure of the drive unit)

[0044] The drive unit 3 causes the piston 1 and rod 8 to reciprocate within the cylinder body 20 along the axis O. The drive unit 3 has an eccentric shaft 31, a rotating body 32, a connecting rod 33, a crosshead 36, and a housing 37.

[0045] An eccentric shaft portion 31 is driven by a motor (not shown) to rotate about a rotation axis X (central axis) extending in a horizontal direction orthogonal to axis O. The eccentric shaft portion 31 is cylindrical with the rotation axis X as its center. A rotating body 32 is integrally disposed on the eccentric shaft portion 31 and is disk-shaped with its center on an axis different from the rotation axis X. That is, the rotation axis X of the eccentric shaft portion 31 is positioned eccentrically relative to the center of the rotating body 32. By rotating the eccentric shaft portion 31, the rotating body 32 rotates about the rotation axis X.

[0046] The connecting rod 33 is a component used to convert the rotational motion of the rotating body 32 into reciprocating motion in the direction of axis O and transmit it to the piston 1. The connecting rod 33 has an annular upper part 33a, a connecting part 33b, and a lower part 33c that cover the rotating body 32 from the outer periphery.

[0047] A bearing device (not shown) is provided between the inner circumferential surface of the upper annular portion 33a and the outer circumferential surface of the rotating body 32. The upper annular portion 33a and the rotating body 32 revolve together around the rotation axis X. The lower annular portion 33c is also annular like the upper annular portion 33a and is integrally connected to the upper annular portion 33a via a connecting portion 33b. The lower annular portion 33c is housed within a crosshead 36. The crosshead 36 is a bottomed cylinder that covers the lower annular portion 33c from the outside. The crosshead 36 is configured to move along the axis O within the housing 37 (described later). The lower annular portion 33c rotates within the crosshead 36 (described later) in tandem with the upper annular portion 33a's revolution around the rotation axis X, and reciprocates along the axis O within the housing 37 together with the crosshead 36. A swing shaft portion 35 is mounted at the lower end of the lower annular portion 33c. The lower end of the swing shaft 35 is connected to the other end of the rod 8. The swing shaft 35 is able to swing relative to the lower annular portion 33c about a swing shaft that extends in a horizontal direction orthogonal to the axis O.

[0048] The outer casing 37 is formed to cover the eccentric shaft portion 31, the rotating body 32, the connecting rod portion 33, and the crosshead 36. The outer casing 37 is cylindrical and extends along the axis O, with both ends in the axis O direction closed by a top plate 37a and a bottom plate 37b.

[0049] A wear-resistant band 38 is provided between the outer peripheral surface of the crosshead 36 and the inner peripheral surface of the housing 37. The wear-resistant band 38 is a component with the same function and material as the wear-resistant ring 11 mentioned above.

[0050] An air circulation section 39 is formed in the lower part of the outer casing 37. The air circulation section 39 is formed to penetrate the outer casing 37 in a direction intersecting the axis O. The air circulation section 39 has an air inlet 39a and an air outlet 39b. The air inlet 39a is formed in the outer casing 37 on one radial side intersecting the axis O, penetrating both the inside and outside of the outer casing 37. The air outlet 39b is formed in the outer casing 37 on the other radial side intersecting the axis O, penetrating both the inside and outside of the outer casing 37. The air circulation section 39 uses a fan, blower, etc. (not shown) to introduce air into the space below the crosshead 36 in the outer casing 37 through the air inlet 39a. The air introduced into the outer casing 37 is discharged to the outside of the outer casing 37 through the air outlet 39b. This allows for ventilation of the lower part of the outer casing 37.

[0051] (Structure of the shell)

[0052] The housing 4 covers the cylinder body 20 from the outside. The housing 4 has a bottomed cylindrical housing body 41, a supply pipe 42, and a gas discharge pipe 43. The supply pipe 42 is a conduit for guiding liquefied hydrogen from an external supply source into the housing body 41. The liquefied hydrogen introduced into the housing body 41 through the supply pipe 42 is stored in a liquid storage chamber 44 at the bottom of the housing body 41. The supply pipe 42 is located near the bottom surface of the housing body 41. The gas discharge pipe 43 is provided for discharging the vaporized components (gas components) within the liquid storage chamber 44 to the outside. The gas discharge pipe 43 is located at a position separated from the supply pipe 42 by upwards. Furthermore, the liquid level of the liquefied hydrogen in the liquid storage chamber 44 is adjusted to be located below the gas discharge pipe 43. Additionally, the aforementioned discharge pipe 6 extends to the outside of the housing 4.

[0053] A cylindrical portion 45 is formed at the upper end of the housing 4. The cylindrical portion 45 protrudes upward from the upper surface 4t of the housing 4 along the axis O. The upper end of the cylindrical portion 45 is connected to the bottom plate 37b of the outer casing 37. The upper end of the cylinder body 20 is housed inside the cylindrical portion 45. The rod 8 extends upward from the upper end of the cylinder body 20 inside the outer casing 37.

[0054] When the liquefied hydrogen pump 101 is operated, liquefied hydrogen is first supplied from the outside of the housing 4 to the inside of the housing 4 through the supply pipe 42. Then, the piston 1 is moved back and forth within the cylinder body 20 by the drive unit 3. As a result, liquefied hydrogen in the reservoir 44 is drawn into the cylinder body 20 through the check valve 5. The piston 1 compresses the liquefied hydrogen introduced from the outside into the cylinder body 20 to a high-pressure state. The high-pressure liquefied hydrogen is discharged to the outside through the discharge valve 7 and the discharge pipe 6 by the action of the piston 1.

[0055] (Structure of the sealing part)

[0056] like Figure 2 As shown, the sealing part 9A is used to seal the gap between the cylinder 2 and the rod 8. The sealing part 9A includes a sealing part body 90, a first sealing member 91, a second sealing member 92, a flow path 95, and an inert gas supply flow path 96.

[0057] The sealing part body 90 is embedded in the upper opening of the cylinder body 20. The sealing part body 90 integrally has an insertion cylinder part 90a and an enlarged diameter part 90b.

[0058] The insertion cylinder portion 90a is inserted into the cylinder body 20 through the upper end opening. The insertion cylinder portion 90a is formed as a cylinder extending along the axis O. The inner circumferential surface of the insertion cylinder portion 90a is formed radially outward relative to the outer circumferential surface of the rod 8. As a result, a cylindrical gap S is formed between the insertion cylinder portion 90a, which forms part of the cylinder body 20, and the rod 8.

[0059] The enlarged diameter portion 90b expands radially outward from the upper end of the insertion cylinder portion 90a, centered on the axis O. The enlarged diameter portion 90b is provided such that it opens from above to close the upper end of the cylinder body 20. Furthermore, in the embodiments disclosed herein, the sealing portion body 90 is mounted on the upper end of the cylinder body 20, but it is also possible to integrally form the same structure as the sealing portion body 90 on the upper end of the cylinder body 20.

[0060] The first sealing component 91 and the second sealing component 92 are disposed on the inner circumferential surface of the insertion cylinder portion 90a.

[0061] The first sealing member 91 is housed in a groove 90m formed on the inner circumferential surface of the lower end of the insertion cylinder 90a. The first sealing member 91 is formed in a continuous annular shape in the circumferential direction about the axis O. The first sealing member 91 protrudes radially inward relative to the inner circumferential surface of the insertion cylinder 90a and slides in contact with the outer circumferential surface of the rod 8. The first sealing member 91 seals the space between the rod 8 and the sealing body 90, which forms part of the cylinder 2.

[0062] The second sealing member 92 is spaced apart from the first sealing member 91 in the direction away from the piston 1 (upward) in the axial direction O. The second sealing member 92 is housed in a groove 90n formed on the inner circumferential surface of the upper end of the insertion cylinder portion 90a. The second sealing member 92 is formed as a continuous annulus in the circumferential direction about the axial direction O. The second sealing member 92 protrudes radially inward relative to the inner circumferential surface of the insertion cylinder portion 90a and slides in contact with the outer circumferential surface of the rod 8. The second sealing member 92 seals the space between the rod 8 and the sealing body 90 provided in the cylinder body 20.

[0063] The gap D between the first sealing member 91 and the second sealing member 92 in the direction of axis O is greater than the travel of the rod 8 driven by the drive unit 3 together with the piston 1 in the direction of axis O.

[0064] like Figure 2 , Figure 3 As shown, a flow path 95 is formed on the sealing body 90. The flow path 95 is formed radially relative to the axis O. The flow path 95 is provided such that one end 95a connects to the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92. In the embodiment of this disclosure, one end 95a of the flow path 95 is formed above the first sealing member 91 at the lower end of the insertion cylinder 90a. That is, one end 95a is formed as the lower end facing the gap S. The flow path 95 extends radially outward from one end 95a. The other end 95b of the flow path 95 opens to the outside of the cylinder 2. In the embodiment of this disclosure, the other end 95b of the flow path 95 opens, for example, on the upper surface of the enlarged diameter portion 90b. One end of the pipe 95p is connected to the other end 95b of the flow path 95. An on / off valve 95v is provided in the middle of the pipe 95p. The other end of the pipe 95p is connected to the hydrogen recovery unit 95r. In the event that hydrogen leaks from the cylinder body 20 side through the gap S between the first sealing member 91 and the rod 8, the flow path 95 causes the incoming hydrogen to flow out to the outside of the cylinder 2. The hydrogen flowing out to the outside of the cylinder 2 from the other end 95b of the flow path 95 is sent to the hydrogen recovery section 95r through the piping 95p.

[0065] An inert gas supply flow path 96 is formed on the sealing body 90. The inert gas supply flow path 96 is formed on the opposite side of the axis O in the radial direction. That is, the inert gas supply flow path 96 is formed on the opposite side of the flow path 95, separated by the axis O. The inert gas supply flow path 96 is provided such that one end 96a communicates with the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92. In the embodiment of this disclosure, one end 96a of the inert gas supply flow path 96 is formed below the second sealing member 92 at the upper end of the insertion cylinder portion 90a. That is, one end 96a is formed as an upper end facing the gap S. The inert gas supply flow path 96 extends radially outward from one end 96a. The other end 96b of the inert gas supply flow path 96 opens to the outside of the cylinder 2. In the embodiment of this disclosure, the other end 96b of the inert gas supply flow path 96 opens, for example, on the upper surface of the enlarged diameter portion 90b. One end of a pipe 96p is connected to the other end 96b of the inert gas supply flow path 96. An on / off valve 96v is installed on this pipe 96p. The other end of the pipe 96p can be connected to an inert gas supply source (not shown), such as a tank filled with inert gas. The inert gas supply flow path 96 allows inert gas supplied from an inert gas supply source located outside the cylinder 2 to flow through the pipe 96p.

[0066] In embodiments of this disclosure, helium (He), which has a lower specific gravity than atmosphere, is used as the inert gas.

[0067] In the embodiments of this disclosure, before the liquefied hydrogen pump 101 is operated, helium in a gaseous state is filled into the sealing section 9A through the inert gas supply flow section 96 as an inert gas. Specifically, the filling of the inert gas is carried out at a time after the liquefied hydrogen pump 101 is installed and before the liquefied hydrogen pump 101 is in its initial state before operation, that is, before the first operation of the liquefied hydrogen pump 101.

[0068] To this end, an inert gas supply source is connected to pipe 96p, and on / off valves 95v and 96v are opened. Then, helium is supplied from the inert gas supply source to the inert gas supply path 96 through pipe 96p. When inert gas is supplied to the inert gas supply path 96 from outside the cylinder 2, inert gas is filled in the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92, and in the flow path 95 communicating with the gap S.

[0069] Thus, when inert gas is supplied from outside the cylinder 2 through the inert gas supply flow path 96, the inert gas flows into the gap S from the end 96a, which opens at the upper end of the gap S. At this moment, the atmosphere present in the inert gas supply flow path 96 and the gap S between the rod 8 and the cylinder 2 is pressed downwards with the supply of inert gas. By using helium, which has a lower specific gravity than atmosphere, as the inert gas, the atmosphere present in the gap S settles downwards towards the helium. As a result, the downwardly pressed atmosphere flows into the flow path 95 from the end 95a, which opens at the lower end of the gap S, and is pushed out to the outside of the liquefied hydrogen pump 101 through the flow path 95. Thus, the seal 9A can be efficiently replaced with inert gas.

[0070] Thus, in the initial state before operation, the liquefied hydrogen pump 101 is pre-filled with inert gas. Even after the liquefied hydrogen pump 101 starts operating, hydrogen flows into the gap S between the rod 8 and the cylinder 2. There is no oxygen-containing atmosphere in the gap S, the flow path 95, and the inert gas supply flow path 96. Hydrogen flows into the oxygen-free inert gas. Therefore, the hydrogen concentration in the atmosphere will not reach the lower explosive limit, and the liquefied hydrogen pump system 100 can be used safely.

[0071] like Figure 2 As shown, the sealing section 9A also includes an information acquisition unit 200. The information acquisition unit 200 acquires information related to the hydrogen concentration in the fluid flowing out of the cylinder 2 through the flow path section 95. In the embodiments of this disclosure, the information acquisition unit 200 includes, for example, a flow meter 201. The flow meter 201 detects the flow rate of the fluid flowing through the flow path section 95, that is, the flow rate of hydrogen leaking from the cylinder body 20 side through the first sealing member 91 and the rod 8 into the gap S. The greater the flow rate of the fluid detected by the flow meter 201, the greater the amount of hydrogen flowing into the gap S from the cylinder body 20 side through the first sealing member 91 and the rod 8. The flow meter 201, as the information acquisition unit 200, outputs the detected value of the flow rate of the fluid flowing through the flow path section 95 to the control device 60.

[0072] In addition, the sealing part 9A includes a hydrogen concentration detection unit 202 and an atmospheric temperature detection unit 203.

[0073] The hydrogen concentration detection unit 202 detects the hydrogen concentration in the atmosphere outside the cylinder 2. In embodiments of this disclosure, the hydrogen concentration detection unit 202 is, for example, a water concentration sensor that detects the hydrogen concentration in the atmosphere within the air circulation section 39.

[0074] The atmospheric temperature detection unit 203 detects the atmospheric temperature outside the cylinder 2. In embodiments of this disclosure, the atmospheric temperature detection unit 203 is, for example, a thermocouple that detects the atmospheric temperature inside the atmospheric flow section 39.

[0075] The hydrogen concentration detection unit 202 and the atmospheric temperature detection unit 203 output the detected values ​​of hydrogen concentration and atmospheric temperature to the control device 60.

[0076] (Hardware structure diagram)

[0077] like Figure 4 As shown, the control device 60 is a computer equipped with various hardware such as a CPU 61, ROM 62, RAM 63, HDD (Hard Disk Drive) memory 64, and communication module 65.

[0078] (Function block diagram)

[0079] Control device 60 executes a program pre-stored in the device via CPU 61, such as... Figure 5 As shown, it functionally includes an input unit 71, a pump control unit 72, and a command signal output unit 73.

[0080] The input unit 71 receives signals from various detection values ​​output from the information acquisition unit 200, the hydrogen concentration detection unit 202, and the atmospheric temperature detection unit 203.

[0081] In order to control the operation of the liquefied hydrogen pump 101 based on the detection values ​​from the information acquisition unit 200, the hydrogen concentration detection unit 202 and the atmospheric temperature detection unit 203 respectively, the pump control unit 72 generates commands for the electric motor that drives the eccentric shaft unit 31 to rotate.

[0082] The command signal output unit 73 outputs a signal for controlling the operation of the liquefied hydrogen pump 101 based on the command generated by the pump control unit 72.

[0083] The control device 60 stops the operation of the liquefied hydrogen pump 101 when it determines, based on information related to hydrogen concentration obtained by the information acquisition unit 200, that the hydrogen concentration in the fluid exceeds a preset reference value. In this embodiment of the present disclosure, the flow meter 201, which is the information acquisition unit 200, acquires the flow rate of the fluid flowing through the flow path 95 as information related to hydrogen concentration. The control device 60 determines that the hydrogen concentration in the fluid exceeds a preset reference value when the fluid flow rate is above a preset flow rate threshold, and stops the operation of the liquefied hydrogen pump 101.

[0084] Furthermore, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is above a preset hydrogen concentration threshold, the control device 60 stops the operation of the liquefied hydrogen pump 101. In the embodiment of this disclosure, the hydrogen concentration detection unit 202 detects the hydrogen concentration in the atmosphere in the atmosphere flow section 39. When hydrogen leaks from between the second sealing member 92 and the rod 8, the hydrogen concentration in the atmosphere in the atmosphere flow section 39 increases. In the control device 60, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is above a preset hydrogen concentration threshold, the control device 60 determines that hydrogen is leaking from between the second sealing member 92 and the rod 8, and stops the operation of the liquefied hydrogen pump 101. Here, the hydrogen concentration threshold is preferably set, for example, to the lower explosive limit of hydrogen, i.e., 1 vol%.

[0085] Furthermore, the control device 60 stops the operation of the liquefied hydrogen pump 101 when the atmospheric temperature detected by the atmospheric temperature detection unit 203 is lower than a preset atmospheric temperature threshold. In cases of extremely low atmospheric temperatures, such as when moisture in the atmosphere freezes, the second sealing member 92 may be damaged due to the frozen moisture (ice). Conversely, the operation of the liquefied hydrogen pump 101 is stopped when the atmospheric temperature is lower than the preset atmospheric temperature threshold. The atmospheric temperature of the atmospheric flow section 39 also decreases when hydrogen leaks between the second sealing member 92 and the rod 8. Here, the atmospheric temperature threshold is preferably set, for example, to a temperature exceeding the freezing point of water, i.e., 0°C.

[0086] (Processing steps)

[0087] like Figure 6 As shown, the control method of the liquefied hydrogen pump system according to this embodiment includes a hydrogen concentration detection step S10, a hydrogen concentration determination step S11, a flow rate detection step S12, a flow rate determination step S13, an atmospheric temperature detection step S14, an atmospheric temperature determination step S15, an automatic stop step S16-S18, and a restart step S19. These steps S10-S19 are repeatedly executed at preset time intervals during the operation of the liquefied hydrogen pump 101.

[0088] In the hydrogen concentration detection step S10, the hydrogen concentration in the atmosphere within the atmospheric flow section 39 is detected by the hydrogen concentration detection unit 202. The detected value of the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is output to the control device 60.

[0089] In the hydrogen concentration determination step S11, the pump control unit 72 determines whether the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is less than a preset hydrogen concentration threshold. As a result, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is less than the preset hydrogen concentration threshold ("yes" in step S11), the process proceeds to step S12.

[0090] On the other hand, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is above the preset hydrogen concentration threshold ("No" in step S11), it is determined that hydrogen is leaking from between the second sealing member 92 and the rod 8, and the automatic stop step S16 is entered.

[0091] In the automatic stop step S16, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101. At this time, the operation of the liquefied hydrogen pump 101 can also be stopped, and information indicating that the hydrogen concentration is above the hydrogen concentration threshold is output to the operator through the illumination of a warning light, the sound of a warning buzzer, and the output of a message. In the automatic stop step S16, when the operation of the liquefied hydrogen pump 101 has stopped, the operator or staff implements countermeasures to reduce the hydrogen concentration in the atmosphere, such as increasing the speed of the fan or blower that circulates air to the air circulation section 39, or ventilating the area where the liquefied hydrogen pump 101 is installed. After the countermeasures are implemented, the operator or staff performs a prescribed operation to restart the liquefied hydrogen pump 101. Upon receiving the prescribed operation input to restart the liquefied hydrogen pump 101, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0092] In the flow detection step S12, the flow rate of the fluid (hydrogen) flowing in the flow path section 95 is detected by the flow meter 201, which is the information acquisition unit 200. The detected value of the fluid flow rate detected by the information acquisition unit 200 is output to the control device 60.

[0093] In the flow determination step S13, the pump control unit 72 determines whether the flow rate of the fluid detected by the flow meter 201 is less than a preset flow threshold.

[0094] As a result, if the flow rate of the fluid flowing in the flow path 95, as detected by the flow meter 201, is less than a preset flow rate threshold ("Yes" in step S13), the process proceeds to step S14.

[0095] On the other hand, if the flow rate detected by the flow meter 201 in the flow path 95 is above a preset flow rate threshold ("No" in step S13), it is determined that hydrogen is leaking from between the first sealing member 91 and the rod 8, and the automatic stop step S17 is entered.

[0096] In the automatic stop step S17, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101. At this time, similar to the automatic stop step S16, the operation of the liquefied hydrogen pump 101 can also be stopped, and information indicating that the flow rate of the flow path 95 is above a flow rate threshold is output. In the automatic stop step S17, when the operation of the liquefied hydrogen pump 101 stops, the operator or staff implements countermeasures to reduce the flow rate of the fluid in the flow path 95, for example, by replacing the first sealing member 91. After the countermeasures are implemented, the operator or staff performs a prescribed operation to restart the liquefied hydrogen pump 101. Upon receiving the prescribed operation input to restart the liquefied hydrogen pump 101, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0097] In the atmospheric temperature detection step S14, the atmospheric temperature detection unit 203 detects the temperature of the atmosphere within the atmospheric flow section 39. The atmospheric temperature detected by the atmospheric temperature detection unit 203 is output to the control device 60.

[0098] In the atmospheric temperature determination step S15, the pump control unit 72 determines whether the atmospheric temperature detected by the atmospheric temperature detection unit 203 is above the preset atmospheric temperature threshold.

[0099] As a result, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is above the preset atmospheric temperature threshold ("Yes" in step S15), the series of processes ends.

[0100] On the other hand, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than the preset atmospheric temperature threshold ("No" in step S15), it is determined that the moisture in the atmosphere may freeze in the atmospheric circulation unit 39, and the automatic stop step S18 is entered.

[0101] In the automatic stop step S18, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101. At this time, similar to the automatic stop steps S16 and S17, the operation of the liquefied hydrogen pump 101 can also be stopped, and information indicating that the atmospheric temperature is below the atmospheric temperature threshold is output. In the automatic stop step S18, when the liquefied hydrogen pump 101 stops operating, the operator or staff takes countermeasures to raise the atmospheric temperature above the atmospheric temperature threshold, such as heating the area around the second sealing component 92. After the countermeasures are completed, the operator or staff performs a prescribed operation to restart the liquefied hydrogen pump 101. Upon receiving the prescribed operation input to restart the liquefied hydrogen pump 101, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0102] (Effects)

[0103] In the liquefied hydrogen pump system 100 with the above-described structure, the piston 1 is reciprocated along the axis O within the cylinder 2 via the drive unit 3 and the rod 8, thereby compressing the liquefied hydrogen introduced from the outside into the cylinder 2 and discharging it out of the cylinder 2. When a portion of the liquefied hydrogen in the cylinder 2 passes through the gap S between the first sealing member 91 and the outer peripheral surface of the rod 8, liquefied hydrogen, or low-temperature hydrogen gas generated by the vaporization of liquefied hydrogen, flows into the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92. The hydrogen (liquefied hydrogen or hydrogen gas) flowing into the gap S between the rod 8 and the cylinder 2 circulates as a fluid within the flow path 95 and is discharged to the outside of the cylinder 2.

[0104] The information acquisition unit 200 acquires information related to the hydrogen concentration in the fluid flowing to the outside of the cylinder 2 through the flow path 95. When hydrogen flows within the flow path 95, the information related to the hydrogen concentration acquired by the information acquisition unit 200 changes. If the control device 60 determines, based on the information related to the hydrogen concentration acquired by the information acquisition unit 200, that the hydrogen concentration in the fluid exceeds a preset reference value, it stops the operation of the liquefied hydrogen pump 101. Thus, in the event of liquefied hydrogen leakage, by detecting changes in hydrogen concentration and stopping the operation of the liquefied hydrogen pump 101, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a predetermined reference value.

[0105] Furthermore, the information acquisition unit 200 acquires the fluid flow rate as information related to hydrogen concentration. When a portion of the liquefied hydrogen in cylinder 2 passes through the gap S between the first sealing member 91 and the outer peripheral surface of the rod 8, the hydrogen flowing into the gap S between the rod 8 and cylinder 2 circulates as fluid within the flow path 95. Therefore, the more the flow rate of the fluid flowing within the flow path 95 increases, the more hydrogen leaks out. Thus, by acquiring the fluid flow rate within the flow path 95 as information related to hydrogen concentration, if the fluid flow rate is above a preset flow rate threshold, the control device 60 determines that the hydrogen concentration in the fluid exceeds a preset reference value, and can stop the operation of the liquefied hydrogen pump 101. As a result, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a predetermined reference value.

[0106] Furthermore, in the liquefied hydrogen pump system 100, the operation of the liquefied hydrogen pump 101 is stopped when the atmospheric temperature is lower than a preset atmospheric temperature threshold. Thus, by preventing the liquefied hydrogen pump 101 from operating in a temperature environment such as when moisture in the atmosphere freezes, damage to the second sealing member 92 can be suppressed. As a result, hydrogen leakage from the damaged second sealing member 92 and the rod 8 can be suppressed.

[0107] Furthermore, in the liquefied hydrogen pump system 100, if the atmospheric hydrogen concentration detected by the hydrogen concentration detection unit 202 is above a preset hydrogen concentration threshold, the operation of the liquefied hydrogen pump 101 is stopped. This prevents the atmospheric hydrogen concentration from further increasing due to hydrogen leakage from the liquefied hydrogen pump 101.

[0108] Furthermore, in the liquefied hydrogen pump system 100, inert gas is supplied from outside the cylinder 2 via the inert gas supply flow path 96. This allows inert gas to be filled into the gap S between the rod 8 and the cylinder 2 (between the first sealing member 91 and the second sealing member 92) and the flow path 95 communicating with this gap S. In the initial state of the liquefied hydrogen pump 101 before its first operation, by pre-filling it with inert gas, even if hydrogen flows into the gap S between the rod 8 and the cylinder 2 after the liquefied hydrogen pump 101 begins operation, the hydrogen flows into an oxygen-free inert gas. Therefore, the hydrogen concentration in the atmosphere will not reach the lower explosive limit, allowing the liquefied hydrogen pump system to be used safely.

[0109] Furthermore, in the liquefied hydrogen pump system 100, one end 96a of the inert gas supply flow path 96 is positioned above one end 95a of the flow path 95 and communicates with the gap S between the rod 8 and the cylinder 2. Therefore, if an inert gas, helium, with a specific gravity less than atmosphere, is supplied from outside the cylinder 2 through the inert gas supply flow path 96, the atmosphere present in the inert gas supply flow path 96 and the gap S between the rod 8 and the cylinder 2 is pushed downwards with the supply of inert gas. Consequently, the pushed atmosphere is expelled from the gap S between the rod 8 and the cylinder 2 through the flow path 95 to the outside of the liquefied hydrogen pump 101. This allows for efficient replacement of the liquefied hydrogen pump 101 with inert gas.

[0110] In addition, in the liquefied hydrogen pump system 100, the distance D between the first sealing member 91 and the second sealing member 92 in the direction of axis O is greater than the travel distance of the rod 8 in the direction of axis O.

[0111] Therefore, when rod 8 moves along axis O, it is possible to prevent foreign objects or the like generated by the sliding of the second sealing member 92 and rod 8 from reaching the sliding portion between the first sealing member 91 and rod 8. This prevents damage to the first sealing member 91 from foreign objects or the like generated by the sliding of the second sealing member 92 and rod 8. Furthermore, it is possible to prevent foreign objects or the like generated by the sliding of the first sealing member 91 and rod 8 from reaching the sliding portion between the second sealing member 92 and rod 8. This also prevents damage to the second sealing member 92 from foreign objects or the like generated by the sliding of the first sealing member 91 and rod 8.

[0112] In the control method of the liquefied hydrogen pump system 100 with the above-described structure, information related to the hydrogen concentration in the fluid flowing out of the cylinder 2 is obtained. If, based on the obtained information related to the hydrogen concentration, it is determined that the hydrogen concentration in the fluid exceeds a preset reference value, the operation of the liquefied hydrogen pump 101 is stopped. In this way, in the event of liquefied hydrogen leakage, by detecting changes in hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, suppressing the hydrogen concentration in the surrounding atmosphere to below a predetermined reference value.

[0113] (Second Implementation)

[0114] Next, a second embodiment of the liquefied hydrogen pump system and the control method for the liquefied hydrogen pump system of this disclosure will be described. Furthermore, in the second embodiment described below, structures common to the first embodiment described above will be labeled with the same reference numerals in the figures, and their descriptions will be omitted. The second embodiment differs from the first embodiment in that a fluid thermometer 205 is used instead of a flow meter 201.

[0115] like Figure 7 As shown, in the liquefied hydrogen pump 101 of the liquefied hydrogen pump system 100 in this embodiment, the sealing part 9B serves as an information acquisition unit 200, for example, equipped with a thermometer 205. The thermometer 205 is, for example, a thermocouple that detects the temperature of the fluid flowing in the flow path 95, that is, the temperature of the hydrogen leaking from the cylinder body 20 side through the first sealing member 91 and the rod 8 into the gap S. As an information acquisition unit 200, the thermometer 205 outputs the detected temperature value of the fluid flowing in the flow path 95 to the control device 60.

[0116] like Figure 8 As shown, the lower the temperature of the fluid detected by the thermometer 205 after a certain period of time, the more hydrogen (fluid) can be presumed to leak from the cylinder body 20 side through the first sealing component 91 and the rod 8 and flow into the gap S.

[0117] The thermocouple, which serves as the thermometer 205, is preferably positioned in the flow path 95 as close as possible to the lower first sealing member 91. This allows for more responsive detection of temperature drops caused by the influence of hydrogen passing through the first sealing member 91 and the rod 8.

[0118] (Processing steps)

[0119] like Figure 9 As shown, the control method of the liquefied hydrogen pump system of this disclosure includes a hydrogen concentration detection step S10, a hydrogen concentration determination step S11, a temperature detection step S22, a temperature determination step S23, an atmospheric temperature detection step S14, an atmospheric temperature determination step S15, an automatic stop step S16~S18, and a restart step S19.

[0120] In the hydrogen concentration detection step S10, the hydrogen concentration in the atmosphere within the atmospheric flow section 39 is detected by the hydrogen concentration detection unit 202.

[0121] In the hydrogen concentration determination step S11, the pump control unit 72 determines whether the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is less than a preset hydrogen concentration threshold. As a result, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is less than the preset hydrogen concentration threshold ("yes" in step S11), the process proceeds to step S22.

[0122] On the other hand, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is above the preset hydrogen concentration threshold ("No" in step S11), it is determined that hydrogen is leaking from between the second sealing member 92 and the rod 8, and similarly to the first embodiment described above, the automatic stop step S16 and the restart step S19 are entered sequentially.

[0123] In temperature detection step S22, the temperature of the fluid (hydrogen) flowing in the flow path section 95 is detected by thermometer 205, which is an information acquisition unit 200. The detected value of the fluid temperature detected by the information acquisition unit 200 is output to the control device 60.

[0124] In temperature determination step S23, the pump control unit 72 determines whether the fluid temperature detected by the thermometer 205 is above a preset temperature threshold.

[0125] As a result, if the temperature of the flow in the flow path 95 detected by the thermometer 205 is above the preset temperature threshold ("Yes" in step S23), the process proceeds to step S14.

[0126] On the other hand, if the temperature of the flow in the flow path 95 detected by the thermometer 205 is less than the preset temperature threshold ("No" in step S23), it is determined that hydrogen is leaking from between the first sealing member 91 and the rod 8, and the automatic stop step S17 is entered.

[0127] In the automatic stop step S17, the operation of the liquefied hydrogen pump 101 is stopped. At this time, the operation of the liquefied hydrogen pump 101 can also be stopped, and information indicating that the temperature of the flow path 95 is above a temperature threshold is output. In the automatic stop step S17, when the operation of the liquefied hydrogen pump 101 has stopped, the operator or staff implements countermeasures to suppress the temperature drop of the fluid in the flow path 95, for example, by replacing the first sealing member 91. After the countermeasures are implemented, the operator or staff performs a prescribed operation to restart the liquefied hydrogen pump 101. When the prescribed operation input for restarting the liquefied hydrogen pump 101 is input, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0128] In the atmospheric temperature detection step S14, the atmospheric temperature detection unit 203 detects the temperature of the atmosphere in the atmospheric circulation section 39.

[0129] In the atmospheric temperature determination step S15, the pump control unit 72 determines whether the atmospheric temperature detected by the atmospheric temperature detection unit 203 is above the preset atmospheric temperature threshold.

[0130] As a result, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is above the preset atmospheric temperature threshold ("Yes" in step S15), the series of processes ends.

[0131] On the other hand, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than the preset atmospheric temperature threshold ("No" in step S15), it is determined that the moisture in the atmosphere may freeze in the atmospheric circulation unit 39, and the automatic stop step S18 and restart step S19 are entered sequentially.

[0132] (Effects)

[0133] In the liquefied hydrogen pump system 100 with the above-described structure, the temperature of the fluid within the flow path 95 is obtained as information related to hydrogen concentration. If the obtained fluid temperature is lower than a preset temperature threshold, the control device 60 determines that the hydrogen concentration in the fluid exceeds a preset reference value, and can stop the operation of the liquefied hydrogen pump 101. As a result, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a predetermined reference value.

[0134] (Third implementation method)

[0135] Next, a third embodiment of the liquefied hydrogen pump system and the control method for the liquefied hydrogen pump system of this disclosure will be described. Furthermore, in the third embodiment described below, structures common to the first embodiment are labeled with the same reference numerals in the figures, and their descriptions are omitted. The third embodiment differs from the first embodiment in that it includes a heater 98. In the third embodiment, in addition to the structure shown in the first embodiment, a heater 98 is also included.

[0136] like Figure 10 As shown, in the liquefied hydrogen pump 101 of the liquefied hydrogen pump system 100 of this embodiment, the sealing portion 9C further includes a heater 98 for heating the second sealing member 92. The heater 98 is provided, for example, on the upper surface of the expanded diameter portion 90b of the sealing portion body 90 at a position overlapping with the second sealing member 92 when viewed from above. The heater 98 may also be provided on the entire upper surface of the expanded diameter portion 90b. Alternatively, the heater 98 may be embedded within the expanded diameter portion 90b.

[0137] In this embodiment, when the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than a preset temperature threshold, the control device 60 heats the second sealing member 92 by the heater 98.

[0138] (Processing steps)

[0139] like Figure 11 As shown, the control method of the liquefied hydrogen pump system of this disclosure includes a hydrogen concentration detection step S10, a hydrogen concentration determination step S11, a flow rate detection step S12, a flow rate determination step S13, an atmospheric temperature detection step S14, an atmospheric temperature determination step S15, an automatic stop step S16, S17, a heater start step S28, and a restart step S19.

[0140] In this embodiment, the heater start-up step S28 is performed if the atmospheric temperature detected by the atmospheric temperature detection unit 203 in the atmospheric temperature determination step S15 is lower than the atmospheric temperature threshold (in step S15, this is "No"). In the heater start-up step S28, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101 and starts the heater 98. As a result, the temperature of the second sealing member 92 and its vicinity in the atmospheric flow section 39 rises, suppressing the freezing of moisture in the atmosphere within the atmospheric flow section 39. After the atmospheric temperature is raised above the atmospheric temperature threshold by the heater start-up step S28, the operator performs a prescribed operation to restart the liquefied hydrogen pump 101. The control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0141] (Effects)

[0142] In the liquefied hydrogen pump system 100 with the above-described structure, similar to the first embodiment, the operation of the liquefied hydrogen pump 101 is stopped when the atmospheric temperature is lower than a preset atmospheric temperature threshold. Therefore, by preventing the liquefied hydrogen pump 101 from operating in a temperature environment such as when moisture in the atmosphere freezes, damage to the second sealing member 92 can be suppressed. As a result, hydrogen leakage from the damaged second sealing member 92 and the rod 8 can be suppressed.

[0143] Furthermore, the sealing part 9C also includes a heater 98 for heating the second sealing member 92. When the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than a preset temperature threshold, the control device 60 heats the second sealing member 92 and its vicinity through the heater 98.

[0144] Therefore, when the atmospheric temperature is lower than a preset atmospheric temperature threshold, heating with heater 98 can suppress the freezing of moisture in the atmosphere. As a result, it is possible to prevent frozen moisture from damaging the second sealing member 92 and to prevent hydrogen from leaking between the second sealing member 92 and the rod 8.

[0145] Furthermore, similar to the first embodiment described above, if the hydrogen concentration in the fluid exceeds a preset reference value based on information related to hydrogen concentration obtained by the information acquisition unit 200, the operation of the liquefied hydrogen pump 101 is stopped. In this way, in the event of liquefied hydrogen leakage, by detecting changes in hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, suppressing the hydrogen concentration in the surrounding atmosphere to below a predetermined reference value.

[0146] (First variation of the implementation method)

[0147] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, the specific structure is not limited to this embodiment and may include design changes that do not depart from the scope of this disclosure.

[0148] For example, such as Figure 12 As shown, the sealing part 9D of the liquefied hydrogen pump system 100 may also have a dustproof seal 99 in the atmospheric flow part 39.

[0149] A dustproof seal 99 is provided in the enlarged diameter portion 90b of the sealing body 90. The dustproof seal 99 integrally has a fixing portion 99a fixed to the enlarged diameter portion 90b and a protruding portion 99b extending radially inward from the upper end of the fixing portion 99a. The protruding portion 99b is formed to overlap with the second sealing member 92 when viewed from above. As a result, it is possible to prevent foreign matter or other contaminants mixed into the atmospheric flow portion 39 from affecting the second sealing member 92.

[0150] Furthermore, the protrusion 99b is preferably provided radially outward from the outer periphery of the rod 8. This prevents hydrogen leakage from between the second sealing member 92 and the rod 8 from accumulating between the rod 8 and the dust seal 99. To suppress hydrogen retention, the dust seal 99 can also be formed of a mesh material, a porous material, or the like. In this case, the mesh material or porous material preferably uses a material with an opening size that allows hydrogen to pass through while preventing the intrusion of foreign matter.

[0151] With this structure, the dustproof seal 99 provided in the atmospheric flow section 39 can prevent foreign objects or the like from entering the gap S between the rod 8 and the second sealing member 92 in the atmospheric flow section 39.

[0152] (Second variation of the implementation method)

[0153] In addition, such as Figure 13 As shown, the sealing part 9E of the liquefied hydrogen pump system 100 may also have a recess 300 in the sealing part body 90E.

[0154] A recess 300 is formed in the insertion cylinder portion 90a of the sealing body 90E. The recess 300 is formed between the first sealing member 91 and the second sealing member 92 in the insertion cylinder portion 90a constituting the cylinder 2. The recess 300 is formed below the inner wall surface 94 in the insertion cylinder portion 90a, which is formed radially outward from the outer periphery of the rod 8. The recess 300 is formed by recessing radially outward from the inner wall surface 94. The recess 300 is continuously formed in the circumferential direction about the axis O. The bottom surface 300b of the recess 300 slopes obliquely downward from the radially inward side toward the outward side. A guide portion 301 is provided on the bottom surface 300b, protruding radially inward from the inner wall surface 94. The guide portion 301 extends obliquely upward from the radially outward side toward the inward side.

[0155] In this way, by providing a recess 300 at a position below the inner wall surface 94, wear powder and other debris from the second sealing member 92 generated by the sliding of the second sealing member 92 and the rod 8 can be collected into the recess 300. In particular, by providing a guide portion 301 in the recess 300, wear powder falling from the second sealing member 92 can be efficiently guided and collected into the recess 300.

[0156] Therefore, when rod 8 moves along axis O, it can prevent foreign objects or other debris generated by the sliding of the second sealing member 92 and rod 8 from reaching the sliding portion of the first sealing member 91 and rod 8 below. Thus, it can prevent damage to the first sealing member 91 from foreign objects or other debris generated by the sliding of the second sealing member 92 and rod 8.

[0157] (Other implementation methods)

[0158] In addition, the structures shown in the above embodiments and their variations can be appropriately combined to form the product.

[0159] Furthermore, the steps of the control method for the liquefied hydrogen pump system shown in the above embodiments can be appropriately changed in their order, and the thresholds used for various determinations can also be modified.

[0160] <Postscript>

[0161] The liquefied hydrogen pump system 100 and the control method of the liquefied hydrogen pump system 100 described in each embodiment are as follows.

[0162] (1) The first embodiment of the liquefied hydrogen pump system 100 includes: a liquefied hydrogen pump 101 that compresses liquefied hydrogen; a control device 60 that controls the operation of the liquefied hydrogen pump 101, wherein the liquefied hydrogen pump 101 includes: a cylindrical cylinder 2 that extends along an axis O; a piston 1 that is reciprocally movable within the cylinder 2 along the axis O, compressing the liquefied hydrogen introduced from the outside into the cylinder 2 and discharging it out of the cylinder 2; a rod 8, one end of which is connected to the piston 1 within the cylinder 2, and the other end of which protrudes out of the cylinder 2; a drive unit 3 that is connected to the other end of the rod 8, causing the piston 1 to reciprocate within the cylinder 2 along the axis O via the rod 8; and sealing parts 9A~9E that seal the gap S between the rod 8 and the cylinder 2, wherein the sealing parts 9A~9E include: a first sealing member 9 1. It seals the gap S between the rod 8 and the cylinder 2; 2. The second sealing member 92 is spaced apart from the first sealing member 91 in the direction away from the piston 1 in the axial direction O, and seals the gap between the rod 8 and the cylinder 2; 3. The flow path 95 is formed in the cylinder 2, one end of which communicates with the gap between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92, and the other end opens to the outside of the cylinder 2; 4. The information acquisition unit 200 acquires information related to the hydrogen concentration in the fluid flowing out of the cylinder 2 through the flow path 95, and the control device 60 stops the operation of the liquefied hydrogen pump 101 when it determines that the hydrogen concentration in the fluid exceeds a preset reference value based on the information related to the hydrogen concentration acquired by the information acquisition unit 200.

[0163] The liquefied hydrogen pump system 100 uses a drive unit 3 to reciprocate the piston 1 along the axis O within the cylinder 2 via a rod 8, thereby compressing the liquefied hydrogen introduced from the outside into the cylinder 2 and discharging it out of the cylinder 2. When a portion of the liquefied hydrogen in the cylinder 2 leaks out through the gap S between the first sealing member 91 and the outer peripheral surface of the rod 8, liquefied hydrogen, or hydrogen gas generated by the vaporization of liquefied hydrogen, flows into the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92. The hydrogen flowing into the gap S between the rod 8 and the cylinder 2 circulates as a fluid within the flow path 95 and is discharged to the outside of the cylinder 2.

[0164] The information acquisition unit 200 acquires information related to the hydrogen concentration in the fluid flowing to the outside of the cylinder 2 through the flow path 95. When hydrogen flows within the flow path 95, the information related to the hydrogen concentration acquired by the information acquisition unit 200 changes. If the control device 60 determines, based on the information related to the hydrogen concentration acquired by the information acquisition unit 200, that the hydrogen concentration in the fluid exceeds a preset reference value, it stops the operation of the liquefied hydrogen pump 101. In this way, in the event of liquefied hydrogen leakage, by detecting changes in hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, suppressing the hydrogen concentration in the surrounding atmosphere to below a predetermined reference value.

[0165] (2) The second scheme of the liquefied hydrogen pump system 100 is based on the liquefied hydrogen pump system 100 of (1). The information acquisition unit 200 acquires the flow rate of the fluid as information related to the hydrogen concentration. When the flow rate of the fluid is above a preset flow rate threshold, the control device 60 stops the operation of the liquefied hydrogen pump 101.

[0166] Therefore, when a portion of the liquefied hydrogen in cylinder 2 passes through the gap S between the first sealing member 91 and the outer peripheral surface of rod 8, the hydrogen (liquefied hydrogen or hydrogen gas) flowing into the gap S between rod 8 and cylinder 2 circulates as a fluid within the flow path 95. Thus, the more the flow rate of the fluid flowing within the flow path 95 increases, the more hydrogen leaks out. In this way, by obtaining the flow rate of the fluid within the flow path 95 as information related to hydrogen concentration, if the flow rate is above a preset flow rate threshold, the control device 60 determines that the hydrogen concentration in the fluid exceeds a preset reference value, and can stop the operation of the liquefied hydrogen pump 101. As a result, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a predetermined reference value.

[0167] (3) The third embodiment of the liquefied hydrogen pump system 100 is based on the liquefied hydrogen pump system 100 of (1) or (2), wherein the information acquisition unit 200 acquires the temperature of the fluid as information related to the hydrogen concentration, and the control device 60 stops the operation of the liquefied hydrogen pump 101 when the temperature of the fluid is less than a preset temperature threshold.

[0168] Therefore, when a portion of the liquefied hydrogen in cylinder 2 passes through the gap S between the first sealing member 91 and the outer peripheral surface of the rod 8, the hydrogen flowing into the gap S between the rod 8 and cylinder 2 circulates as fluid within the flow path 95. The more the flow rate of hydrogen flowing within the flow path 95 increases, the lower the fluid temperature becomes. Therefore, by obtaining the fluid temperature within the flow path 95 as information related to hydrogen concentration, if the fluid temperature is lower than a preset temperature threshold, the control device 60 determines that the hydrogen concentration in the fluid exceeds a preset reference value, and can stop the operation of the liquefied hydrogen pump 101. As a result, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a predetermined reference value.

[0169] (4) In the fourth embodiment, the liquefied hydrogen pump system 100 is based on any of the liquefied hydrogen pump systems 100 in (1) to (3), wherein the sealing part 9A to 9E is further provided with an atmospheric temperature detection part 203 for detecting the atmospheric temperature outside the cylinder 2, and the control device 60 stops the operation of the liquefied hydrogen pump 101 when the atmospheric temperature detected by the atmospheric temperature detection part 203 is less than a preset atmospheric temperature threshold.

[0170] In low-temperature conditions, such as when atmospheric moisture freezes, the second sealing component 92 may be damaged due to the frozen moisture (ice). Conversely, when the atmospheric temperature is below a preset atmospheric temperature threshold, the operation of the liquefied hydrogen pump 101 is stopped. Thus, by preventing the liquefied hydrogen pump 101 from operating in a temperature environment such as when atmospheric moisture freezes, damage to the second sealing component 92 can be suppressed. As a result, leakage of hydrogen from the damaged second sealing component 92 and the rod 8 can be suppressed.

[0171] (5) The fifth embodiment of the liquefied hydrogen pump system 100 is based on the liquefied hydrogen pump system 100 of (4). The sealing part 9C is further equipped with a heater 98 for heating the second sealing component 92. When the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than a preset temperature threshold, the control device 60 heats the second sealing component 92 by the heater 98.

[0172] Therefore, when the atmospheric temperature is lower than a preset atmospheric temperature threshold, heating the second sealing member 92 using the heater 98 can raise the temperature of the second sealing member 92 and its vicinity. This prevents the freezing of atmospheric moisture even in environments where moisture in the atmosphere freezes. As a result, damage to the second sealing member 92 by frozen moisture can be prevented, and hydrogen leakage between the second sealing member 92 and the rod 8 can be suppressed.

[0173] (6) The sixth embodiment of the liquefied hydrogen pump system 100 is based on any one of (1) to (5) of the liquefied hydrogen pump system 100, wherein the sealing part 9A to 9E further comprises a hydrogen concentration detection part 202 for detecting the hydrogen concentration in the atmosphere outside the cylinder 2, and when the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection part 202 is above a preset hydrogen concentration threshold, the control device 60 stops the operation of the liquefied hydrogen pump 101.

[0174] Therefore, when the hydrogen concentration in the atmosphere is above a preset hydrogen concentration threshold, stopping the operation of the liquefied hydrogen pump 101 can prevent the hydrogen concentration in the atmosphere from further increasing due to hydrogen leakage from the liquefied hydrogen pump 101.

[0175] (7) The liquefied hydrogen pump system 100 of the seventh embodiment is based on the liquefied hydrogen pump system 100 of any one of (1) to (6), wherein the sealing part 9A to 9E further comprises an inert gas supply flow path 96, which is formed in the cylinder 2 and supplies inert gas from the outside of the cylinder 2 to the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92.

[0176] Therefore, when inert gas is supplied from outside the cylinder 2 through the inert gas supply flow path 96, inert gas can be filled into the gap S between the rod 8 and the cylinder 2 between the first sealing member 91 and the second sealing member 92, and into the flow path 95 communicating with the gap S. Thus, in the initial state of the liquefied hydrogen pump 101 before operation, by pre-filling with inert gas, even if hydrogen flows into the gap S between the rod 8 and the cylinder 2, the hydrogen flows into an oxygen-free inert gas. Therefore, the hydrogen concentration in the atmosphere will not reach the lower explosive limit, and the liquefied hydrogen pump system can be used safely.

[0177] (8) The liquefied hydrogen pump system 100 of the eighth scheme is based on the liquefied hydrogen pump system 100 of (7), wherein the specific gravity of the inert gas is smaller than that of the atmosphere, and one end of the inert gas supply flow path 96 is connected to the gap S between the rod 8 and the cylinder 2 at a position above the end of the flow path 95.

[0178] Therefore, when inert gas is supplied from outside the cylinder 2 through the inert gas supply flow path 96, the atmosphere present in the inert gas supply flow path 96 and the gap S between the rod 8 and the cylinder 2 at that moment is pushed downwards with the supply of inert gas. As a result, the pushed atmosphere is pushed out from the gap S between the rod 8 and the cylinder 2 through the flow path 95 to the outside of the liquefied hydrogen pump 101. Thus, the liquefied hydrogen pump 101 can be efficiently replaced with inert gas.

[0179] Helium is an example of an inert gas with a density less than that of atmosphere.

[0180] (9) The liquefied hydrogen pump system 100 of the ninth scheme is based on the liquefied hydrogen pump system 100 of any one of (1) to (8), wherein the distance D between the first sealing member 91 and the second sealing member 92 in the direction of the axis O is greater than the travel of the rod 8 in the direction of the axis O.

[0181] Therefore, by making the distance D between the first sealing member 91 and the second sealing member 92 larger than the travel of the rod 8, when the rod 8 moves along the axis O, it is possible to prevent foreign objects or the like generated by the sliding of the second sealing member 92 and the rod 8 from reaching the sliding portion of the first sealing member 91 and the rod 8 below. This prevents damage to the first sealing member 91 from foreign objects or the like generated by the sliding of the second sealing member 92 and the rod 8. Furthermore, it prevents foreign objects or the like generated by the sliding of the first sealing member 91 and the rod 8 from reaching the sliding portion of the second sealing member 92 and the rod 8. Thus, it is possible to prevent damage to the second sealing member 92 from foreign objects or the like generated by the sliding of the first sealing member 91 and the rod 8.

[0182] (10) The liquefied hydrogen pump system 100 of the tenth embodiment, based on any one of (1) to (9), further comprises: an atmospheric flow section 39, which is formed on the side away from the piston 1 in the direction of the axis O relative to the second sealing member 92, for atmospheric flow; and a dustproof seal 99, which is disposed in the atmospheric flow section 39 and covers the second sealing member 92.

[0183] Therefore, by providing a dustproof seal 99 within the atmospheric flow section 39, it is possible to prevent foreign objects or other contaminants present in the atmosphere flowing through the atmospheric flow section 39 from entering the gap S between the rod 8 and the second sealing member 92.

[0184] (11) The liquefied hydrogen pump system 100 of the eleventh embodiment, based on the liquefied hydrogen pump system 100 of any one of (1) to (10), further comprises: an inner wall surface 94 formed in the cylinder 2 between the first sealing member 91 and the second sealing member 92, and formed radially outward relative to the outer periphery of the rod 8; a recess 300 formed below the inner wall surface 94 between the first sealing member 91 and the second sealing member 92, and formed recessed from the inner wall surface 94 toward the radially outward.

[0185] Therefore, by providing a recess 300 below the inner wall surface 94, wear particles and other debris from the second sealing member 92 generated during sliding between the second sealing member 92 and the rod 8 can be collected into the recess 300. Consequently, when the rod 8 moves along the axis O, it is possible to prevent foreign matter generated during sliding between the second sealing member 92 and the rod 8 from reaching the sliding portion between the first sealing member 91 and the rod 8 below. This prevents damage to the first sealing member 91 from foreign matter generated during sliding between the second sealing member 92 and the rod 8.

[0186] (12) The control method of the liquefied hydrogen pump system 100 of the twelfth scheme is a control method of the liquefied hydrogen pump system 100 of any one of (1) to (11), including the following steps: obtaining information related to hydrogen concentration in the fluid flowing out of the flow path 95 to the outside of the cylinder 2; determining, based on the obtained information related to hydrogen concentration, whether the hydrogen concentration in the fluid exceeds a preset reference value; and stopping the operation of the liquefied hydrogen pump 101 when it is determined that the hydrogen concentration in the fluid exceeds the preset reference value.

[0187] Thus, information related to the hydrogen concentration in the fluid flowing out of cylinder 2 is obtained. If, based on the obtained information related to the hydrogen concentration, it is determined that the hydrogen concentration in the fluid exceeds a preset reference value, the operation of the liquefied hydrogen pump 101 is stopped. In this way, in the event of liquefied hydrogen leakage, by detecting changes in hydrogen concentration, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a specified reference value.

[0188] Industrial availability

[0189] According to the liquefied hydrogen pump system and control method of the liquefied hydrogen pump system disclosed herein, in the event of liquefied hydrogen leakage, the hydrogen concentration in the surrounding atmosphere can be suppressed to below a specified reference value by detecting changes in hydrogen concentration.

[0190] Explanation of reference numerals in the attached figures

[0191] 1: Piston

[0192] 2: Cylinder

[0193] 3: Drive unit

[0194] 4: Casing

[0195] 4t: Upper surface

[0196] 5: Check valve

[0197] 6: Drainage piping

[0198] 7: Discharge valve

[0199] 8: Rod

[0200] 9A~9E: Sealing section

[0201] 10: Piston Body

[0202] 11: Wear ring

[0203] 12: Piston rings

[0204] 20: Cylinder body

[0205] 21: Compression Chamber

[0206] 31: Eccentric shaft section

[0207] 32: Solid of Revolution

[0208] 33: Connecting rod section

[0209] 33a: Upper annular portion

[0210] 33b: Connecting part

[0211] 33c: Lower annular portion

[0212] 35: Swing shaft

[0213] 36: Crosshead

[0214] 37: Outer shell

[0215] 37a: Top plate

[0216] 37b: Base plate

[0217] 38: Wear-resistant belt

[0218] 39: Atmospheric Circulation Department

[0219] 39a: Atmospheric inlet

[0220] 39b: Atmospheric exhaust outlet

[0221] 41: Main body of the shell

[0222] 42: Supply Management

[0223] 43: Gas exhaust pipe

[0224] 44: Liquid Storage Chamber

[0225] 45: Cylindrical part

[0226] 60: Control device

[0227] 61: CPU

[0228] 62: ROM

[0229] 63: RAM

[0230] 64: Memory

[0231] 65: Communication Module

[0232] 71: Input Section

[0233] 72: Pump Control Unit

[0234] 73: Command signal output unit

[0235] 90, 90E: Main body of the sealing part

[0236] 90a: Insertion tube section

[0237] 90b: Expanded diameter section

[0238] 90m, 90n: slot

[0239] 91: First sealing component

[0240] 92: Second sealing component

[0241] 94: Inner wall surface

[0242] 95: Flow path part

[0243] 95a: One end

[0244] 95b: The other end

[0245] 95p: Piping

[0246] 95r: Hydrogen Recovery Department

[0247] 95V: On / off valve

[0248] 96: Inert gas supply flow path section

[0249] 96a: One end

[0250] 96b: The other end

[0251] 96p: Piping

[0252] 96V: On / off valve

[0253] 98: Heater

[0254] 99: Dustproof seals

[0255] 99a: Fixing part

[0256] 99b: Protruding part

[0257] 100: Liquefied hydrogen pump system

[0258] 101: Liquefied Hydrogen Pump

[0259] 200: Information Acquisition Department

[0260] 201: Flow meter

[0261] 202: Hydrogen Concentration Detection Department

[0262] 203: Atmospheric Temperature Detection Department

[0263] 205: Thermometer

[0264] 206: Thermometer

[0265] 300: Concave

[0266] 300b: Bottom surface

[0267] 301: Guidance Department

[0268] O: Axis

[0269] S: Gap

Claims

1. A liquefied hydrogen pump system, comprising: a liquefied hydrogen pump for compressing liquefied hydrogen; and a control device for controlling the operation of the liquefied hydrogen pump, characterized in that, The liquefied hydrogen pump has the following features: A cylindrical cylinder that extends along its axial direction; A piston, which is reciprocally movable within the cylinder in the axial direction, compresses the liquefied hydrogen introduced from the outside into the cylinder and discharges it out of the cylinder; A rod, one end of which is connected to the piston inside the cylinder, and the other end protruding out of the cylinder; A drive unit, which is connected to the other end of the rod, causes the piston to reciprocate within the cylinder along the axial direction via the rod; Sealing part, The sealing part includes: A first sealing component seals the gap between the rod and the cylinder; The second sealing component is spaced apart from the first sealing component in the axial direction away from the piston, and seals the space between the rod and the cylinder. A flow path is formed in the cylinder, one end of which communicates with the gap between the rod and the cylinder between the first sealing member and the second sealing member, and the other end opens to the outside of the cylinder; The information acquisition unit acquires information related to the hydrogen concentration in the fluid flowing out of the cylinder through the flow path unit. If the control device determines, based on information related to the hydrogen concentration obtained by the information acquisition unit, that the hydrogen concentration in the fluid exceeds a preset reference value, it stops the operation of the liquefied hydrogen pump.

2. The liquefied hydrogen pump system according to claim 1, characterized in that, The information acquisition unit acquires the flow rate of the fluid as information related to the hydrogen concentration. The control device stops the operation of the liquefied hydrogen pump when the flow rate of the fluid is above a preset flow rate threshold.

3. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, The information acquisition unit acquires the temperature of the fluid as information related to the hydrogen concentration. The control device stops the operation of the liquefied hydrogen pump when the temperature of the fluid is lower than a preset temperature threshold.

4. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, The sealing part also includes an atmospheric temperature detection part for detecting the ambient temperature outside the cylinder. The control device stops the operation of the liquefied hydrogen pump when the atmospheric temperature detected by the atmospheric temperature detection unit is lower than a preset atmospheric temperature threshold.

5. The liquefied hydrogen pump system according to claim 4, characterized in that, The sealing part also includes a heater for heating the second sealing component. If the atmospheric temperature detected by the atmospheric temperature detection unit is lower than a preset atmospheric temperature threshold, the control device heats the second sealing component through the heater.

6. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, The sealing part also includes a hydrogen concentration detection part for detecting the hydrogen concentration in the atmosphere outside the cylinder. If the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit is above a preset hydrogen concentration threshold, the control device stops the operation of the liquefied hydrogen pump.

7. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, The sealing part also includes an inert gas supply flow path, which is formed in the cylinder and supplies inert gas from the outside of the cylinder to the gap between the rod and the cylinder.

8. The liquefied hydrogen pump system according to claim 7, characterized in that, The specific gravity of the inert gas is less than that of the atmosphere. One end of the inert gas supply flow path is connected to the gap between the rod and the cylinder at a position slightly above one end of the flow path.

9. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, The distance between the first sealing component and the second sealing component in the axial direction is greater than the travel distance of the rod in the axial direction.

10. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, It also has: An atmospheric flow section is formed on the side of the piston away from the piston in the axial direction relative to the second sealing member, for atmospheric flow. A dustproof seal is disposed within the air circulation section, covering the gap between the rod and the second sealing component.

11. The liquefied hydrogen pump system according to claim 1 or 2, characterized in that, It also has: An inner wall surface, formed in the cylinder between the first sealing member and the second sealing member, is formed at a distance from the outer peripheral surface of the rod on the radially outer side of the rod. A recess is formed below the inner wall surface between the first sealing member and the second sealing member, and is recessed radially outward from the inner wall surface.

12. A control method for a liquefied hydrogen pump system, as described in claim 1 or 2, characterized in that, Includes the following steps: Obtain information related to the hydrogen concentration in the fluid flowing out of the cylinder through the flow path; Based on the information obtained related to the hydrogen concentration, it is determined whether the hydrogen concentration in the fluid exceeds a preset benchmark value; If the hydrogen concentration in the fluid is determined to exceed a preset benchmark value, the operation of the liquefied hydrogen pump is stopped.

Images