Liquefied hydrogen pump system, and method for controlling liquefied hydrogen pump system

Abstract

To suppress hydrogen concentration in surrounding atmosphere to a determined reference value or less by detecting a change in the hydrogen concentration if liquefied hydrogen leaks.SOLUTION: A liquefied hydrogen pump system includes a liquefied hydrogen pump and a control device, and the liquefied hydrogen pump includes a cylinder, a piston, a rod, a drive part, and a seal part. The seal part includes a first seal member, a second seal member provided with an interval in the direction of separating from the piston an axial direction with respect to the first seal member, a flow passage part, one end of which communicates with a gap between the rod and the cylinder and the other end of which opens to the outside of the cylinder, and an information acquisition part for acquiring information on hydrogen concentration in a fluid flowing to the outside of the cylinder through the flow passage part. The control device stops the operation of the liquefied hydrogen pump in the case of determining that hydrogen concentration in the fluid exceeds a preset reference value on the basis of information on the acquired hydrogen concentration.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a liquefied hydrogen pump system and a method for controlling a liquefied hydrogen pump system.

Background Art

[0002] Reciprocating pumps have been used as liquefied hydrogen pumps for compressing liquefied hydrogen. This type of pump is capable of boosting liquefied hydrogen up to about 90 MPa, for example. Specifically, the reciprocating pump mainly includes a piston that reciprocates in the axial direction and a cylinder that covers the piston from the outside. As the piston reciprocates within the cylinder, the liquefied hydrogen is compressed and discharged to the outside. The piston is driven by a drive unit. The piston provided inside the cylinder and the drive unit provided outside the cylinder are connected via a rod. The rod extends through the inside and outside of the cylinder.

[0003] For example, Patent Document 1 discloses a configuration in which a plurality of seal members are provided between a rod and a cylinder with a gap in the axial direction of the rod in this type of liquefied hydrogen pump. Patent Document 1 also discloses a configuration for monitoring the pressure of a fluid flow path that communicates between a plurality of seal members. In such a configuration, by detecting an increase in the pressure of the fluid flow path, leakage of liquefied hydrogen through the gap between the seal member and the rod due to wear of the seal member is monitored.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, in the hydrogen liquefier pump as described above, even when hydrogen leaks from the hydrogen liquefier pump into the atmosphere, it is required to keep the hydrogen concentration in the surrounding atmosphere below a defined reference value. However, in the configuration described in Patent Document 1, although the presence or absence of leakage of liquefied hydrogen can be monitored, when liquefied hydrogen leaks from the hydrogen liquefier pump into the atmosphere, it is not possible to detect the hydrogen concentration in the surrounding atmosphere.

[0006] The present disclosure has been made to solve the above problems, and an object thereof is to provide a hydrogen liquefier pump system and a control method for the hydrogen liquefier pump system that can keep the hydrogen concentration in the surrounding atmosphere below a defined reference value by detecting a change in the hydrogen concentration when liquefied hydrogen leaks.

Means for Solving the Problems

[0007] To solve the above problems, a liquefied hydrogen pump system according to the present disclosure is a liquefied hydrogen pump system including a liquefied hydrogen pump that compresses liquefied hydrogen and a control device that controls the operation of the liquefied hydrogen pump. The liquefied hydrogen pump includes a cylindrical cylinder extending in the axial direction, a piston provided reciprocally movable in the axial direction within the cylinder that compresses the liquefied hydrogen introduced into the cylinder from the outside and discharges it outside the cylinder, a rod having one end connected to the piston within the cylinder and the other end protruding outside the cylinder, a drive unit connected to the other end of the rod that reciprocates the piston in the axial direction within the cylinder via the rod, and a seal unit. The seal unit includes a first seal member that seals the gap between the rod and the cylinder, a second seal member provided at a distance from the first seal member in a direction away from the piston in the axial direction that seals between the rod and the cylinder, a flow path portion formed in the cylinder having one end communicating with the gap between the rod and the cylinder between the first seal member and the second seal member and the other end opening to the outside of the cylinder, and an information acquisition unit that acquires information regarding the hydrogen concentration in the fluid flowing out 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 information regarding the hydrogen concentration acquired by the information acquisition unit that the hydrogen concentration in the fluid exceeds a preset reference value.

[0008] A control method for a liquefied hydrogen pump system according to the present disclosure is a control method for a liquefied hydrogen pump system as described above, including a step of acquiring information regarding the hydrogen concentration in the fluid flowing out of the cylinder through the flow path portion, a step of determining whether the hydrogen concentration in the fluid exceeds a preset reference value based on the acquired information regarding the hydrogen concentration, and a step of stopping the operation of the liquefied hydrogen pump when it is determined that the hydrogen concentration in the fluid exceeds the preset reference value.

Advantages of the Invention

[0009] According to the liquefied hydrogen pump system and the control method of the liquefied hydrogen pump system of the present disclosure, when liquefied hydrogen leaks, by detecting the change in hydrogen concentration, the hydrogen concentration in the surrounding atmosphere can be suppressed below a determined reference value.

Brief Description of the Drawings

[0010]

Figure 1

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Mode for Carrying Out the Invention

[0011] Hereinafter, with reference to the accompanying drawings, embodiments for implementing a liquid hydrogen pump system and a control method of a liquid hydrogen pump system according to the present disclosure will be described. However, the present disclosure is not limited only to these embodiments. (First Embodiment) (Configuration of Liquid Hydrogen Pump System) As shown in FIG. 1, the liquid hydrogen pump system 100 includes a liquid hydrogen pump 101 and a control device 60.

[0012] (Configuration of Liquid Hydrogen Pump) The liquid hydrogen pump 101 is a reciprocating pump for boosting liquid hydrogen to a high pressure (for example, about 90 MPa). The liquid hydrogen pump 101 mainly includes a piston 1, a cylinder 2, a rod 8, a drive unit 3, a casing 4, and a seal portion 9A.

[0013] (Configuration of Piston) The piston 1 has a columnar piston body 10 centered on an axis O extending in the vertical direction, a wear ring 11 attached to the piston body 10, and a piston ring 12. The dimension of the piston body 10 in the radial direction is constant over the entire region in the direction of the axis O. The wear ring 11 is provided at the tip of the piston body 10. The wear ring 11 has an annular shape centered on the axis O and is formed of a resin material.

[0014] One wear ring 11 is provided at the lower end of the piston body 10, and another wear ring 11 is provided at an interval from the wear ring 11 in the direction of the axis O. Between these pair of wear rings 11, a plurality (six as an example) of piston rings 12 arranged at intervals in the direction of the axis O are provided. The wear ring 11 is provided to guide the piston body 10 along the inner peripheral surface of the cylinder body 20 described later. On the other hand, the piston ring 12 is provided to maintain liquid tightness and air tightness between the inner peripheral surface of the cylinder body 20.

[0015] (Configuration of the cylinder) The cylinder 2 has a cylinder body 20 and a seal part body 90 (see FIG. 2) described later. The cylinder body 20 has a cylindrical shape extending in the direction of the axis O along the axis O. The cylinder body 20 has a bottomed cylindrical shape that covers the piston 1 from the outer peripheral side. The piston 1 is inserted into the cylinder body 20 from the upper opening of the cylinder body 20. The space below the piston 1 inside the cylinder body 20 is a compression chamber 21. A check valve 5 for guiding liquefied hydrogen to the compression chamber 21 is provided at the bottom of the cylinder body 20. This check valve 5 is enabled to allow liquefied hydrogen to flow in only in the direction from the outside of the cylinder body 20 into the compression chamber 21. In other words, even if the pressure in the compression chamber 21 increases, the liquefied hydrogen does not flow out of the cylinder body 20 through the check valve 5.

[0016] A discharge pipe 6 is connected to a side surface of the cylinder body 20 at a portion facing the above-mentioned compression chamber 21. The discharge pipe 6 is provided to take out the liquefied hydrogen compressed in the compression chamber 21 to the outside of the cylinder body 20. A discharge valve 7 is provided in the middle of this discharge pipe 6. The discharge valve 7 is enabled to allow liquefied hydrogen to flow only in the direction from the compression chamber 21 to the outside when the pressure in the compression chamber 21 reaches a predetermined value or more.

[0017] (Configuration of the rod) The rod 8 connects the piston 1 and the drive unit 3. The rod 8 is formed in a columnar shape extending in the direction of the axis O. One end of the rod 8 is connected to the piston body 10 of the piston 1 within the cylinder 2. The other end of the rod 8 protrudes upward from the upper end of the cylinder 2. The other end of the rod 8 is connected to the swing shaft portion 35 of the drive unit 3 within the housing 37 of the drive unit 3. The piston 1 and the rod 8 are enabled to move along the direction of the axis O within the cylinder 2.

[0018] (Configuration of the drive unit) The drive unit 3 reciprocates the piston 1 and the rod 8 in the direction of the axis O within the cylinder main body 20. The drive unit 3 has an eccentric shaft portion 31, a rotating body 32, a link portion 33, a crosshead 36, and a housing 37.

[0019] The eccentric shaft portion 31 is rotationally driven around a rotation axis X (central axis) extending in a horizontal direction orthogonal to the axis O by an electric motor (not shown). The eccentric shaft portion 31 has a columnar shape centered on the rotation axis X. The rotating body 32 is provided integrally with this eccentric shaft portion 31 and has a disk shape centered on an axis different from the rotation axis X. That is, with respect to the center of the rotating body 32, the rotation axis X of the eccentric shaft portion 31 is provided at an eccentric position. When the eccentric shaft portion 31 is rotationally driven, the rotating body 32 revolves around the rotation axis X.

[0020] The link portion 33 is a member for converting the revolving motion of the rotating body 32 into a reciprocating motion in the direction of the axis O and transmitting it to the piston 1. The link portion 33 has an annular upper annular portion 33a that covers the rotating body 32 from the outer peripheral side, a connecting portion 33b, and a lower annular portion 33c. A bearing device (not shown) is provided between the inner peripheral surface of the upper annular portion 33a and the outer peripheral surface of the rotating body 32. The upper annular portion 33a revolves around the rotation axis X together with the rotating body 32. The lower annular part 33c is annular, similar to the upper annular part 33a, and is integrally connected to the upper annular part 33a by the connecting part 33b. The lower annular part 33c is housed within the crosshead 36. The crosshead 36 is formed in a bottomed cylindrical shape that covers the lower annular part 33c from the outside. The crosshead 36 is provided within the housing 37, which will be described later, so as to be movable in the direction of the axis O. As the lower annular part 33c revolves around the rotation axis X of the upper annular part 33a, it rotates within the crosshead 36, which will be described later, and reciprocates in the direction of the axis O together with the crosshead 36 within the housing 37. A swing shaft part 35 is attached to the lower end of the lower annular part 33c. The lower end of the swing shaft part 35 is connected to the other end of the rod 8. The swing shaft part 35 is capable of swinging around a swing axis that extends in a horizontal direction perpendicular to the axis O with respect to the lower annular part 33c.

[0021] The housing 37 is formed so as to cover the eccentric shaft part 31, the rotating body 32, the link part 33, and the crosshead 36. The housing 37 is cylindrical and extends in the direction of the axis O, and both ends in the direction of the axis O are closed by a top plate 37a and a bottom plate 37b. A wear band 38 is provided between the outer peripheral surface of the crosshead 36 and the inner peripheral surface of the housing 37. The wear band 38 is a member having the same function and material as the above-described wear ring 11.

[0022] At the lower part of the housing 37, an air circulation portion 39 is formed. The air circulation portion 39 is formed so as to penetrate the housing 37 in a direction intersecting the axis O direction. The air circulation portion 39 has an air inlet 39a and an air outlet 39b. The air inlet 39a is formed in the housing 37 on one side in the radial direction intersecting the axis O direction so as to penetrate the inside and outside of the housing 37. The air outlet 39b is formed in the housing 37 on the other side in the radial direction intersecting the axis O direction so as to penetrate the inside and outside of the housing 37. The air circulation portion 39 introduces air into the space below the crosshead 36 in the housing 37 through the air inlet 39a by a fan, a blower, etc. (not shown). The air introduced into the housing 37 is discharged to the outside of the housing 37 through the air outlet 39b. Thereby, ventilation is performed in the lower part of the housing 37.

[0023] (Configuration of the casing) The casing 4 covers the above-described cylinder body 20 from the outside. The casing 4 has a bottomed cylindrical casing body 41, a supply pipe 42, and a gas discharge pipe 43. The supply pipe 42 is a pipe for guiding liquefied hydrogen from an external supply source into the casing body 41. The liquefied hydrogen introduced into the casing body 41 through the supply pipe 42 is stored in a liquid storage chamber 44 at the bottom inside the casing body 41. The supply pipe 42 is provided near the bottom surface of the casing body 41. The gas discharge pipe 43 is provided for discharging the components (gas components) vaporized in the liquid storage chamber 44 to the outside. The gas discharge pipe 43 is provided at a position spaced above the supply pipe 42. Further, the liquid level of the liquefied hydrogen in the liquid storage chamber 44 is adjusted to be located below the gas discharge pipe 43. Note that the above-described discharge pipe 6 extends to the outside of the casing 4.

[0024] At the upper end of the casing 4, a cylindrical portion 45 is formed. The cylindrical portion 45 protrudes upward along the axis O direction from the upper surface 4t of the casing 4. The upper end of the cylindrical portion 45 is connected to the bottom plate 37b of the housing 37. The upper end portion of the cylinder body 20 is accommodated inside the cylindrical portion 45. The rod 8 extends upward within the housing 37 from the upper end portion of the cylinder body 20.

[0025] When operating such a liquefied hydrogen pump 101, first, with liquefied hydrogen supplied from the outside of the casing 4 into the casing 4 by the supply pipe 42, the piston 1 is reciprocated within the cylinder body 20 by the drive unit 3. As a result, the liquefied hydrogen in the liquid storage chamber 44 is sucked into the cylinder body 20 through the check valve 5. The piston 1 compresses the liquefied hydrogen introduced into the cylinder body 20 from the outside 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 operation of the piston 1.

[0026] (Configuration of the sealing portion) As shown in FIG. 2, the sealing portion 9A is for sealing the gap between the cylinder 2 and the rod 8. The sealing portion 9A includes a sealing portion main body 90, a first sealing member 91, a second sealing member 92, a flow path portion 95, and an inert gas supply flow path portion 96.

[0027] The sealing portion main body 90 is fitted into the opening at the upper end of the cylinder body 20. The sealing portion main body 90 integrally has an insertion cylinder portion 90a and a diameter-expanded portion 90b. The insertion cylinder portion 90a is inserted into the cylinder body 20 from the opening at the upper end of the cylinder body 20. The insertion cylinder portion 90a is formed in a cylindrical shape extending in the axis O direction. The inner peripheral surface of the insertion cylinder portion 90a is formed to be radially outwardly spaced from the outer peripheral surface of the rod 8. Thereby, a cylindrical gap S is formed between the insertion cylinder portion 90a forming a part of the cylinder body 20 and the rod 8. The diameter-expanded portion 90b expands in the radially outward direction centered on the axis O from the upper end of the insertion cylinder portion 90a. The diameter-expanded portion 90b is provided so as to close the opening at the upper end of the cylinder main body 20 from above. In the embodiment of the present disclosure, the seal portion main body 90 is attached to the upper end portion of the cylinder main body 20, but a configuration similar to that of the seal portion main body 90 may be integrally formed with the upper end portion of the cylinder main body 20.

[0028] The first seal member 91 and the second seal member 92 are provided on the inner peripheral surface of the insertion cylinder portion 90a. The first seal member 91 is accommodated in a groove 90m formed on the inner peripheral surface of the lower end portion of the insertion cylinder portion 90a. The first seal member 91 is formed in an annular shape continuous in the circumferential direction around the axis O. The first seal member 91 protrudes radially inward with respect to the inner peripheral surface of the insertion cylinder portion 90a and is in sliding contact with the outer peripheral surface of the rod 8. The first seal member 91 seals between the rod 8 and the seal portion main body 90 that constitutes a part of the cylinder 2.

[0029] The second seal member 92 is provided at an interval from the first seal member 91 in the direction away from the piston 1 (upward) in the direction of the axis O. The second seal member 92 is accommodated in a groove 90n formed on the inner peripheral surface of the upper end portion of the insertion cylinder portion 90a. The second seal member 92 is formed in an annular shape continuous in the circumferential direction around the axis O. The second seal member 92 protrudes radially inward with respect to the inner peripheral surface of the insertion cylinder portion 90a and is in sliding contact with the outer peripheral surface of the rod 8. The second seal member 92 seals between the rod 8 and the seal portion main body 90 provided on the cylinder main body 20.

[0030] The distance D between the first seal member 91 and the second seal member 92 in the direction of the axis O is larger than the movement stroke of the rod 8 driven together with the piston 1 by the drive unit 3 in the direction of the axis O.

[0031] As shown in FIGS. 2 and 3, the flow path portion 95 is formed in the seal portion main body 90. The flow path portion 95 is formed on one side in the radial direction with respect to the axis O. One end 95a of the flow path portion 95 is provided so as to communicate with the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92. In the embodiment of the present disclosure, one end 95a of the flow path portion 95 is formed above the first seal member 91 at the lower end of the insertion cylinder portion 90a. That is, one end 95a is formed so as to face the lower end portion of the gap S. The flow path portion 95 extends radially outward from one end 95a. The other end 95b of the flow path portion 95 opens to the outside of the cylinder 2. In the embodiment of the present disclosure, the other end 95b of the flow path portion 95 opens, for example, on the upper surface of the enlarged diameter portion 90b. One end of a pipe 95p is connected to the other end 95b of the flow path portion 95. An on-off valve 95v is provided in the middle of the pipe 95p. The other end of this pipe 95p is connected to a hydrogen recovery portion 95r. When hydrogen leaks from the cylinder main body 20 side through between the first seal member 91 and the rod 8 and flows into the gap S, such a flow path portion 95 causes the inflowing hydrogen to flow out to the outside of the cylinder 2. The hydrogen flowing out from the other end 95b of the flow path portion 95 to the outside of the cylinder 2 passes through the pipe 95p and is sent into the hydrogen recovery portion 95r.

[0032] The inert gas supply passage portion 96 is formed in the seal portion main body 90. The inert gas supply passage portion 96 is formed on the other side in the radial direction with respect to the axis O. That is, the inert gas supply passage portion 96 is formed on the opposite side of the flow passage portion 95 with the axis O interposed therebetween. One end 96a of the inert gas supply passage portion 96 is provided so as to communicate with the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92. In the embodiment of the present disclosure, one end 96a of the inert gas supply passage portion 96 is formed below the second seal member 92 at the upper end portion of the insertion cylinder portion 90a. That is, one end 96a is formed so as to face the upper end portion of the gap S. The inert gas supply passage portion 96 extends radially outward from one end 96a. The other end 96b of the inert gas supply passage portion 96 opens to the outside of the cylinder 2. In the embodiment of the present disclosure, the other end 96b of the inert gas supply passage portion 96 opens, for example, on the upper surface of the diameter-expanded portion 90b. One end of a pipe 96p is connected to the other end 96b of the inert gas supply passage portion 96. An on-off valve 96v is provided in 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 supplied from the inert gas supply source provided outside the cylinder 2 through the pipe 96p flows through the inert gas supply passage portion 96. In the embodiment of the present disclosure, for example, helium (He), which has a specific gravity smaller than that of the atmosphere, is used as the inert gas.

[0033] In the embodiment of the present disclosure, prior to operating the liquefied hydrogen pump 101, gaseous helium as an inert gas is filled into the seal portion 9A through the inert gas supply passage portion 96. Specifically, the filling of the inert gas is carried out after the installation of the liquefied hydrogen pump 101, at the timing of the initial state before the liquefied hydrogen pump 101 operates, that is, prior to performing the first operation of the liquefied hydrogen pump 101. To do this, connect an inert gas supply source to the pipe 96p and open the on-off valves 95v and 96v. Then, send helium from the inert gas supply source through the pipe 96p into the inert gas supply passage portion 96. When supplying an inert gas from the outside of the cylinder 2 to the inert gas supply passage portion 96, the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92, and the passage portion 95 communicating with this gap S are filled with the inert gas.

[0034] In this way, when supplying an inert gas from the outside of the cylinder 2 through the inert gas supply passage portion 96, the inert gas flows into the gap S from one end 96a that opens at the upper end portion of the gap S. At that time, the air existing in the inert gas supply passage portion 96 and the gap S between the rod 8 and the cylinder 2 is pushed downward along with the supply of the inert gas. By using helium, which has a specific gravity smaller than that of air, as the inert gas, in the gap S, the air existing in the gap S sinks below the helium. As a result, the air pushed downward flows into the passage portion 95 from one end 95a of the passage portion 95 that opens at the lower end portion of the gap S, and is pushed out to the outside of the liquefied hydrogen pump 101 through the passage portion 95. Thereby, the inside of the seal portion 9A can be efficiently replaced with the inert gas.

[0035] In this way, by filling the liquefied hydrogen pump 101 in the initial state before operation with the inert gas, even if hydrogen flows into the gap S between the rod 8 and the cylinder 2 after the start of operation of the liquefied hydrogen pump 101, there is no air containing oxygen in the gap S, the passage portion 95, and the inert gas supply passage portion 96. The hydrogen flows into the inert gas that does not contain oxygen. Thereby, of course, the hydrogen concentration in the air does not reach the lower explosion limit, and the liquefied hydrogen pump system 100 can be operated safely.

[0036] As shown in FIG. 2, the seal portion 9A further includes an information acquisition unit 200. The information acquisition unit 200 acquires information regarding the hydrogen concentration in the fluid flowing out of the cylinder 2 through the flow path portion 95. In the embodiment of the present disclosure, for example, a flow meter 201 is provided as the information acquisition unit 200. The flow meter 201 detects the flow rate of the fluid flowing through the flow path portion 95, that is, the flow rate of hydrogen leaking into the gap S through the gap between the first seal member 91 and the rod 8 from the cylinder body 20 side. 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 through the gap between the first seal member 91 and the rod 8 from the cylinder body 20 side. 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 portion 95 to the control device 60.

[0037] Further, the seal portion 9A includes a hydrogen concentration detection unit 202 and an atmospheric temperature detection unit 203. The hydrogen concentration detection unit 202 detects the hydrogen concentration in the atmosphere outside the cylinder 2. In the embodiment of the present disclosure, the hydrogen concentration detection unit 202 is, for example, a water concentration sensor that detects the hydrogen concentration in the atmosphere in the air circulation portion 39. The atmospheric temperature detection unit 203 detects the atmospheric temperature outside the cylinder 2. In the embodiment of the present disclosure, the atmospheric temperature detection unit 203 is, for example, a thermocouple that detects the atmospheric temperature in the air circulation portion 39. The hydrogen concentration detection unit 202 and the atmospheric temperature detection unit 203 output the detected values of the hydrogen concentration and the atmospheric temperature to the control device 60.

[0038] (Hardware Configuration Diagram) As shown in FIG. 4, the control device 60 is a computer including each hardware such as a CPU 61, a ROM 62, a RAM 63, a storage 64 such as an HDD (Hard Disk Drive), and a communication module 65.

[0039] (Functional Block Diagram) The control device 60 functionally includes an input unit 71, a pump control unit 72, and a command signal output unit 73, as shown in FIG. 5, by the CPU 61 executing a program stored in the device in advance. The input unit 71 receives signal inputs of each detected value output from the information acquisition unit 200, the hydrogen concentration detection unit 202, the atmospheric temperature detection unit 203, and the like. Based on the detected values from each of the information acquisition unit 200, the hydrogen concentration detection unit 202, and the atmospheric temperature detection unit 203, the pump control unit 72 generates a command for the motor that rotationally drives the eccentric shaft portion 31 in order to control the operation of the liquefied hydrogen pump 101. Based on the command generated by the pump control unit 72, the command signal output unit 73 outputs a signal for controlling the operation of the liquefied hydrogen pump 101.

[0040] When it is determined that the hydrogen concentration in the fluid exceeds a preset reference value based on the information on the hydrogen concentration acquired by the information acquisition unit 200, the control device 60 stops the operation of the liquefied hydrogen pump 101. In the embodiment of the present disclosure, the flow meter 201 as the information acquisition unit 200 acquires the flow rate of the fluid flowing through the flow path portion 95 as information on the hydrogen concentration. When the flow rate of the fluid is equal to or greater than a preset flow rate threshold value, the control device 60 determines that the hydrogen concentration in the fluid exceeds the preset reference value and stops the operation of the liquefied hydrogen pump 101.

[0041] Further, when the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is equal to or higher than a preset hydrogen concentration threshold value, the control device 60 stops the operation of the liquefied hydrogen pump 101. In the embodiment of the present disclosure, the hydrogen concentration detection unit 202 detects the hydrogen concentration in the atmosphere in the air circulation unit 39. When hydrogen leaks from between the second seal member 92 and the rod 8, the hydrogen concentration in the atmosphere in the air circulation unit 39 increases. In the control device 60, when the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is equal to or higher than a preset hydrogen concentration threshold value, it is determined that hydrogen is leaking from between the second seal member 92 and the rod 8, and the operation of the liquefied hydrogen pump 101 is stopped. Here, the hydrogen concentration threshold value is preferably, for example, 1 vol%, which is the lower explosive limit of hydrogen.

[0042] Further, when the atmospheric temperature detected by the atmospheric temperature detection unit 203 is lower than a preset atmospheric temperature threshold value, the control device 60 stops the operation of the liquefied hydrogen pump 101. When the atmospheric temperature is so low that the moisture in the atmosphere freezes, the second seal member 92 may be damaged by the frozen moisture (ice). On the other hand, when the atmospheric temperature is lower than a preset atmospheric temperature threshold value, the operation of the liquefied hydrogen pump 101 is stopped. The atmospheric temperature in the air circulation unit 39 also decreases when hydrogen leaks from between the second seal member 92 and the rod 8. Here, the atmospheric temperature threshold value is preferably, for example, a temperature exceeding 0°C, which is the freezing point (ice point) of water.

[0043] (Procedure of processing) As shown in FIG. 6, the control method of the liquefied hydrogen pump system according to the embodiment of the present 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, automatic stop steps S16 to S18, and a restart step S19. These steps S10 to S19 are repeatedly executed at preset time intervals during the operation of the liquefied hydrogen pump 101.

[0044] In the hydrogen concentration detection step S10, the hydrogen concentration detector 202 detects the hydrogen concentration in the atmosphere within the air circulation section 39. The detected value of the hydrogen concentration in the atmosphere detected by the hydrogen concentration detector 202 is output to the control device 60.

[0045] 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 detector 202 is less than a preset hydrogen concentration threshold. As a result, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detector 202 is less than the preset hydrogen concentration threshold (Yes in step S11), the process proceeds to step S12.

[0046] On the other hand, if the hydrogen concentration in the atmosphere detected by the hydrogen concentration detector 202 is equal to or greater than the preset hydrogen concentration threshold (No in step S11), it is determined that hydrogen is leaking from between the second seal member 92 and the rod 8, and the process proceeds to the automatic stop step S16.

[0047] In the automatic stop step S16, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101. At this time, while stopping the operation of the liquefied hydrogen pump 101, information indicating that the hydrogen concentration is equal to or greater than the hydrogen concentration threshold may be output to the operator by lighting a warning lamp, emitting a sound from a warning buzzer, outputting a message, etc. When the operation of the liquefied hydrogen pump 101 stops in the automatic stop step S16, the operator or worker implements countermeasure measures to reduce the hydrogen concentration in the atmosphere, such as increasing the rotation speed of the fan or blower that circulates air in the air circulation section 39, or ventilating the installation location of the liquefied hydrogen pump 101. After the implementation of the countermeasure process is completed, the operator or worker performs a predetermined operation to restart the liquefied hydrogen pump 101. When a predetermined operation input for restarting the liquefied hydrogen pump 101 is made, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0048] In the flow rate detection step S12, the flow meter 201 as the information acquisition unit 200 detects the flow rate of the fluid (hydrogen) flowing through the flow path unit 95. The detection value of the flow rate of the fluid detected by the information acquisition unit 200 is output to the control device 60. In the flow rate 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 rate threshold value. As a result, if the flow rate of the fluid flowing through the flow path unit 95 detected by the flow meter 201 is less than the preset flow rate threshold value (Yes in step S13), the process proceeds to step S14.

[0049] On the other hand, if the flow rate flowing through the flow path unit 95 detected by the flow meter 201 is equal to or greater than the preset flow rate threshold value (No in step S13), it is determined that hydrogen is leaking from between the first seal member 91 and the rod 8, and the process proceeds to the automatic stop step S17.

[0050] 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 may be stopped and information indicating that the flow rate of the flow path unit 95 is equal to or greater than the flow rate threshold value may be output. When the operation of the liquefied hydrogen pump 101 stops in the automatic stop step S17, an operator or worker performs countermeasure measures to reduce the flow rate of the fluid in the flow path unit 95, for example, by replacing the first seal member 91. After the implementation of the countermeasure process is completed, the operator or worker performs a predetermined operation to restart the liquefied hydrogen pump 101. When a predetermined operation input for restarting the liquefied hydrogen pump 101 is made, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0051] In the atmospheric temperature detection step S14, the atmospheric temperature detection unit 203 detects the temperature in the atmosphere in the air circulation unit 39. The detection value of the atmospheric temperature detected by the atmospheric temperature detection unit 203 is output to the control device 60. 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 equal to or higher than a preset atmospheric temperature threshold value. As a result, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is equal to or higher than the preset atmospheric temperature threshold value (Yes in step S15), a series of processes is terminated.

[0052] On the other hand, if the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than the preset atmospheric temperature threshold value (No in step S15), it is determined that there is a risk of freezing of moisture in the atmosphere in the air circulation unit 39, and the process proceeds to the automatic stop step S18.

[0053] 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 may be stopped and information indicating that the atmospheric temperature is less than the atmospheric temperature threshold value may be output. When the operation of the liquefied hydrogen pump 101 stops in the automatic stop step S18, an operator or worker performs countermeasure measures such as heating around the second seal member 92 in order to raise the atmospheric temperature to be equal to or higher than the atmospheric temperature threshold value. After completion of the countermeasure process, the operator or worker performs a predetermined operation for restarting the liquefied hydrogen pump 101. When a predetermined operation input for restarting the liquefied hydrogen pump 101 is made, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0054] (Function and effect) In the liquid hydrogen pump system 100 configured as described above, in the drive unit 3, the piston 1 is reciprocated in the axial direction O within the cylinder 2 via the rod 8, thereby compressing the liquid hydrogen introduced into the cylinder 2 from the outside and discharging it outside the cylinder 2. When a part of the liquid hydrogen in the cylinder 2 passes through the gap S between the first seal member 91 and the outer peripheral surface of the rod 8, the liquid hydrogen or the low-temperature hydrogen gas generated by the vaporization of the liquid hydrogen flows into the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92. The hydrogen (liquid hydrogen or hydrogen gas) that has flowed into the gap S between the rod 8 and the cylinder 2 circulates through the flow path portion 95 as a fluid and is discharged to the outside of the cylinder 2. The information acquisition unit 200 acquires information regarding the hydrogen concentration in the fluid that circulates outside the cylinder 2 through the flow path portion 95. When hydrogen circulates within the flow path portion 95, the information regarding the hydrogen concentration acquired by the information acquisition unit 200 changes. When it is determined based on the information regarding the hydrogen concentration acquired by the information acquisition unit 200 that the hydrogen concentration in the fluid exceeds a preset reference value, the control device 60 stops the operation of the liquid hydrogen pump 101. In this way, when liquid hydrogen leaks, by detecting the change in the hydrogen concentration and stopping the operation of the liquid hydrogen pump 101, the hydrogen concentration in the surrounding atmosphere can be suppressed below the determined reference value.

[0055] Further, the information acquisition unit 200 acquires the flow rate of the fluid as information regarding the hydrogen concentration. When a part of the liquid hydrogen in the cylinder 2 passes through the gap S between the first seal member 91 and the outer peripheral surface of the rod 8, the hydrogen that has flowed into the gap S between the rod 8 and the cylinder 2 circulates through the flow path portion 95 as a fluid. Therefore, the greater the flow rate of the fluid circulating through the flow path portion 95, the greater the amount of hydrogen leakage. In this manner, the flow rate of the fluid in the flow path portion 95 is acquired as information regarding the hydrogen concentration, and when the flow rate of the fluid is equal to or greater than a preset flow rate threshold value, the control device 60 determines that the hydrogen concentration in the fluid exceeds the preset reference value and can stop the operation of the liquid hydrogen pump 101. As a result, the hydrogen concentration in the surrounding atmosphere can be suppressed below the determined reference value.

[0056] Further, in the liquefied hydrogen pump system 100, when the atmospheric temperature is lower than a preset atmospheric temperature threshold value, the operation of the liquefied hydrogen pump 101 is stopped. Thereby, in a temperature environment where moisture in the atmosphere freezes, by preventing the liquefied hydrogen pump 101 from operating, damage to the second seal member 92 can be suppressed. As a result, leakage of hydrogen from between the damaged second seal member 92 and the rod 8 can be suppressed.

[0057] Further, in the liquefied hydrogen pump system 100, when the hydrogen concentration in the atmosphere detected by the hydrogen concentration detector 202 is equal to or higher than a preset hydrogen concentration threshold value, the operation of the liquefied hydrogen pump 101 is stopped. Thereby, an increase in the hydrogen concentration in the atmosphere due to hydrogen leaking from the liquefied hydrogen pump 101 can be suppressed.

[0058] Further, in the liquefied hydrogen pump system 100, an inert gas is supplied from the outside of the cylinder 2 through the inert gas supply passage portion 96. Thereby, the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92, and the passage portion 95 communicating with this gap S can be filled with the inert gas. In the liquefied hydrogen pump 101 in the initial state before the first operation, by filling with the inert gas, even if hydrogen flows into the gap S between the rod 8 and the cylinder 2 after the start of operation of the liquefied hydrogen pump 101, the hydrogen flows into the inert gas containing no oxygen. Thereby, the hydrogen concentration in the atmosphere does not reach the lower explosion limit, and the liquefied hydrogen pump system can be operated safely.

[0059] Further, in the liquefied hydrogen pump system 100, one end 96a of the inert gas supply passage portion 96 communicates with the gap S between the rod 8 and the cylinder 2 at a position above one end 95a of the passage portion 95. Thus, when helium, which is an inert gas with a specific gravity smaller than that of the atmosphere, is supplied from the outside of the cylinder 2 through the inert gas supply passage portion 96, the atmosphere existing in the inert gas supply passage portion 96 and the gap S between the rod 8 and the cylinder 2 at that time is pushed downward along with the supply of the inert gas. As a result, the pushed atmosphere is pushed out of the liquefied hydrogen pump 101 through the passage portion 95 from the gap S between the rod 8 and the cylinder 2. Thereby, the inside of the liquefied hydrogen pump 101 can be efficiently replaced with the inert gas.

[0060] Further, in the liquefied hydrogen pump system 100, the distance D between the first seal member 91 and the second seal member 92 in the axial direction of the axis O is larger than the moving stroke of the rod 8 in the axial direction of the axis O. Thereby, when the rod 8 moves in the axial direction of the axis O, it is possible to suppress foreign matters or the like generated by the sliding between the second seal member 92 and the rod 8 from reaching the sliding portion between the first seal member 91 and the rod 8. Thereby, it is possible to suppress damage to the first seal member 91 caused by foreign matters or the like generated by the sliding between the second seal member 92 and the rod 8. Further, it is possible to suppress foreign matters or the like generated by the sliding between the first seal member 91 and the rod 8 from reaching the sliding portion between the second seal member 92 and the rod 8. Thereby, it is possible to suppress damage to the second seal member 92 caused by foreign matters or the like generated by the sliding between the first seal member 91 and the rod 8.

[0061] In the control method of the liquefied hydrogen pump system 100 with the above configuration, information regarding the hydrogen concentration in the fluid flowing out of the outside of the cylinder 2 is acquired, and based on the acquired information regarding the hydrogen concentration, when 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, when liquefied hydrogen leaks, by detecting the change in hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, and the hydrogen concentration in the surrounding atmosphere can be suppressed below a determined reference value.

[0062] (Second Embodiment) Next, a second embodiment of the liquefied hydrogen pump system and the control method of the liquefied hydrogen pump system according to the present disclosure will be described. In the second embodiment described below, components common to the first embodiment are denoted by the same reference numerals in the drawings and their description is omitted. The second embodiment is different from the first embodiment in that it has a thermometer 205 for the fluid instead of the flowmeter 201.

[0063] As shown in FIG. 7, in the liquefied hydrogen pump 101 of the liquefied hydrogen pump system 100 in the present embodiment, the seal portion 9B includes, as an information acquisition unit 200, for example, a thermometer 205. The thermometer 205 is, for example, a thermocouple that detects the temperature of the fluid flowing through the flow path portion 95, that is, the temperature of the hydrogen leaking from the cylinder body 20 side through the gap between the first seal member 91 and the rod 8 into the gap S. The thermometer 205 as the information acquisition unit 200 outputs the detected value of the temperature of the fluid flowing through the flow path portion 95 to the control device 60. As shown in FIG. 8, the lower the temperature of the fluid detected by the thermometer 205 when a certain period of time has elapsed, the more hydrogen leaks from the cylinder body 20 side through the gap between the first seal member 91 and the rod 8, and it can be estimated that the flow rate of the hydrogen (fluid) flowing into the gap S is large. The thermocouple, which is the thermometer 205, is preferably provided at a position as close as possible to the lower first seal member 91 in the flow path portion 95. Thereby, the temperature drop due to the influence of the hydrogen passing through the gap between the first seal member 91 and the rod 8 can be detected more responsively.

[0064] (Procedure of processing) As shown in FIG. 9, the control method of the liquefied hydrogen pump system according to the embodiment of the present 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, automatic stop steps S16 to S18, and a restart step S19.

[0065] In the hydrogen concentration detection step S10, the hydrogen concentration detection unit 202 detects the hydrogen concentration in the atmosphere in the air circulation unit 39.

[0066] 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, when 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.

[0067] On the other hand, when the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is equal to or greater than the preset hydrogen concentration threshold (No in step S11), it is determined that hydrogen is leaking from between the second seal member 92 and the rod 8, and similar to the first embodiment, the process sequentially proceeds to the automatic stop step S16 and the restart step S19.

[0068] In the temperature detection step S22, the thermometer 205 as the information acquisition unit 200 detects the temperature of the fluid (hydrogen) flowing through the flow path unit 95. The detected value of the temperature of the fluid detected by the information acquisition unit 200 is output to the control device 60. In the temperature determination step S23, the pump control unit 72 determines whether the temperature of the fluid detected by the thermometer 205 is equal to or greater than a preset temperature threshold. As a result, when the temperature flowing through the flow path unit 95 detected by the thermometer 205 is equal to or greater than the preset temperature threshold (Yes in step S23), the process proceeds to step S14.

[0069] On the other hand, when the temperature detected by the thermometer 205 of the temperature flowing through the flow path portion 95 is less than a preset temperature threshold value (No in step S23), it is determined that hydrogen is leaking from between the first seal member 91 and the rod 8, and the process proceeds to the automatic stop step S17. In the automatic stop step S17, the operation of the liquefied hydrogen pump 101 is stopped. At this time, while stopping the operation of the liquefied hydrogen pump 101, information indicating that the temperature of the flow path portion 95 is equal to or higher than the temperature threshold value may be output. When the operation of the liquefied hydrogen pump 101 stops in the automatic stop step S17, an operator or a worker performs a countermeasure measure for suppressing a decrease in the temperature of the fluid in the flow path portion 95, for example, by replacing the first seal member 91 or the like. After the implementation of the countermeasure process is completed, the operator or the worker performs a predetermined operation for restarting the liquefied hydrogen pump 101. When a predetermined operation input for restarting the liquefied hydrogen pump 101 is made, the control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0070] In the ambient temperature detection step S14, the ambient temperature detector 203 detects the temperature in the air in the air circulation section 39. In the ambient temperature determination step S15, the pump control unit 72 determines whether or not the ambient temperature detected by the ambient temperature detector 203 is equal to or higher than a preset ambient temperature threshold value. As a result, when the ambient temperature detected by the ambient temperature detector 203 is equal to or higher than the preset ambient temperature threshold value (Yes in step S15), the series of processes is terminated.

[0071] On the other hand, when the ambient temperature detected by the ambient temperature detector 203 is less than the preset ambient temperature threshold value (No in step S15), it is determined that there is a risk that moisture in the air freezes in the air circulation section 39, and the process sequentially proceeds to the automatic stop step S18 and the restart step S19.

[0072] (Function and effect) In the liquefied hydrogen pump system 100 configured as described above, the temperature of the fluid in the flow path portion 95 is acquired as information regarding the hydrogen concentration. When the acquired temperature of the fluid is less than a preset temperature threshold value, 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 be equal to or less than a defined reference value.

[0073] (Third Embodiment) Next, a third embodiment of the liquefied hydrogen pump system and the control method of the liquefied hydrogen pump system according to the present disclosure will be described. In the third embodiment described below, for the components common to the first embodiment, the same reference numerals are given in the drawings and the description thereof is omitted. The third embodiment is different from the first embodiment in that a heater 98 is provided. In the third embodiment, in addition to the configuration shown in the first embodiment, a heater 98 is provided.

[0074] As shown in FIG. 10, in the liquefied hydrogen pump 101 of the liquefied hydrogen pump system 100 in the present embodiment, the seal portion 9C further includes a heater 98 that heats the second seal member 92. The heater 98 is provided, for example, at a position overlapping the second seal member 92 when viewed from above on the upper surface of the enlarged diameter portion 90b of the seal portion main body 90. The heater 98 may be provided over the entire upper surface of the enlarged diameter portion 90b. Further, the heater 98 may be embedded in the enlarged diameter portion 90b.

[0075] In the present embodiment, when the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than a preset temperature threshold value, the control device 60 heats the second seal member 92 with the heater 98.

[0076] (Procedure of Processing) As shown in FIG. 11, the control method of the liquefied hydrogen pump system according to the embodiment of the present 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, automatic stop steps S16 and S17, a heater activation step S28, and a restart step S19.

[0077] In this embodiment, the heater activation step S28 is executed when, in the atmospheric temperature determination step S15, the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than the atmospheric temperature threshold value (No in step S15). In the heater activation step S28, the pump control unit 72 stops the operation of the liquefied hydrogen pump 101 and activates the heater 98. As a result, the temperature of the second seal member 92 and the vicinity of the second seal member 92 and the inside of the air circulation part 39 rises, suppressing the freezing of moisture in the air in the air circulation part 39. After the atmospheric temperature rises above the atmospheric temperature threshold value by the heater activation step S28, the operator or worker performs a predetermined operation to restart the liquefied hydrogen pump 101. The control device 60 restarts the liquefied hydrogen pump 101 (step S19).

[0078] (Function and effect) In the liquefied hydrogen pump system 100 configured as described above, as in the first embodiment, when the atmospheric temperature is less than the preset atmospheric temperature threshold value, the operation of the liquefied hydrogen pump 101 is stopped. As a result, by preventing the liquefied hydrogen pump 101 from operating in a temperature environment where moisture in the air freezes, damage to the second seal member 92 can be suppressed. As a result, leakage of hydrogen from between the damaged second seal member 92 and the rod 8 can be suppressed.

[0079] Furthermore, the seal part 9C further includes a heater 98 for heating the second seal member 92, and the control device 60 heats the second seal member 92 and its vicinity with the heater 98 when the atmospheric temperature detected by the atmospheric temperature detection unit 203 is less than the preset temperature threshold value. As a result, when the atmospheric temperature is lower than a preset atmospheric temperature threshold value, heating by the heater 98 can suppress the freezing of moisture in the atmosphere. As a result, damage to the second seal member 92 caused by frozen moisture can be suppressed, and hydrogen leakage from between the second seal member 92 and the rod 8 can be suppressed.

[0080] Also, similar to the first embodiment, when it is determined that the hydrogen concentration in the fluid exceeds a preset reference value based on the information on the hydrogen concentration acquired by the information acquisition unit 200, the operation of the liquefied hydrogen pump 101 is stopped. In this way, when liquefied hydrogen leaks, by detecting a change in the hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, and the hydrogen concentration in the surrounding atmosphere can be suppressed to be equal to or lower than a defined reference value.

[0081] (First Modification of the Embodiment) As described above, the embodiments of the present disclosure have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included. For example, as shown in FIG. 12, a dust seal 99 may be provided in the air circulation portion 39 as the seal portion 9D of the liquefied hydrogen pump system 100.

[0082] The dust seal 99 is provided in the enlarged diameter portion 90b of the seal portion main body 90. The dust 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 so as to overlap the second seal member 92 when viewed from above. Thereby, foreign matters and the like mixed in the air circulation portion 39 can be prevented from reaching the second seal member 92.

[0083] Further, the protruding portion 99b is preferably provided at a radially outer side and spaced apart from the outer peripheral surface of the rod 8. Thereby, it is possible to suppress the retention of hydrogen flowing out from between the second seal member 92 and the rod 8 between the rod 8 and the dust seal 99. In order to suppress the retention of hydrogen, the dust seal 99 may be formed of a mesh-like material, a porous material, or the like. In this case, it is preferable to use a mesh-like material or a porous material having an opening size that can prevent the intrusion of foreign matter while allowing the passage of hydrogen.

[0084] According to such a configuration, the dust seal 99 provided in the air circulation portion 39 can suppress foreign matters and the like existing in the air flowing through the air circulation portion 39 from entering the gap S between the rod 8 and the second seal member 92.

[0085] (Second Modification of the Embodiment) Also, as shown in FIG. 13, as the seal portion 9E of the liquefied hydrogen pump system 100, the seal portion main body 90E may be provided with a recess 300.

[0086] The recess 300 is formed in the insertion cylinder portion 90a of the seal portion main body 90E. The recess 300 is formed in the insertion cylinder portion 90a of the seal portion main body 90E constituting the cylinder 2 between the first seal member 91 and the second seal member 92. The recess 300 is formed below the inner wall surface 94 formed at a radially outer side and spaced apart from the outer peripheral surface of the rod 8 in the insertion cylinder portion 90a. The recess 300 is formed to be recessed radially outward from the inner wall surface 94. The recess 300 is formed continuously in the circumferential direction around the axis O. The bottom surface 300b of the recess 300 is inclined obliquely downward from the radially inner side toward the outer side. A guide portion 301 protruding radially inward with respect to the inner wall surface 94 is provided on the bottom surface 300b. The guide portion 301 extends obliquely upward from the radially outer side toward the inner side.

[0087] In this way, by providing the concave portion 300 at a position below the inner wall surface 94, it is possible to collect wear powder of the second seal member 92 generated by the sliding of the second seal member 92 and the rod 8 into the concave portion 300. In particular, by providing the guide portion 301 in the concave portion 300, it is possible to efficiently guide and collect the wear powder falling from the second seal member 92 into the concave portion 300. Thereby, when the rod 8 moves in the direction of the axis O, it is possible to suppress foreign matters and the like generated by the sliding of the second seal member 92 and the rod 8 from reaching the sliding portion between the lower first seal member 91 and the rod 8. Thereby, it is possible to suppress damage to the first seal member 91 caused by foreign matters and the like generated by the sliding of the second seal member 92 and the rod 8.

[0088] (Other Embodiments) In addition to this, the configurations shown in the above embodiments and their modifications may be appropriately combined and provided. Also, the procedures of the control method of the liquefied hydrogen pump system shown in the above embodiments may be appropriately changed in their order and the threshold values used for various determinations.

[0089] <Appendix> The liquefied hydrogen pump system 100 and the control method of the liquefied hydrogen pump system 100 described in each embodiment are understood as follows, for example.

[0090] (1) The hydrogen liquefied pump system 100 according to the first aspect is a hydrogen liquefied pump system 100 including a hydrogen liquefied pump 101 that compresses hydrogen liquefied gas, and a control device 60 that controls the operation of the hydrogen liquefied pump 101. The hydrogen liquefied pump 101 includes a cylindrical cylinder 2 extending in the direction of axis O, a piston 1 provided reciprocally movable in the cylinder 2 in the direction of axis O, compressing the hydrogen liquefied gas introduced into the cylinder 2 from the outside and discharging it outside the cylinder 2, a rod 8 having one end connected to the piston 1 inside the cylinder 2 and the other end protruding outside the cylinder 2, a drive unit 3 connected to the other end of the rod 8 and reciprocating the piston 1 in the cylinder 2 in the direction of axis O via the rod 8, and seal portions 9A to 9E that seal the gap S between the rod 8 and the cylinder 2. The seal portions 9A to 9E include a first seal member 91 that seals the gap S between the rod 8 and the cylinder 2, a second seal member 92 provided spaced apart from the first seal member 91 in a direction away from the piston 1 in the direction of axis O, a flow path portion 95 formed in the cylinder 2, having one end communicating with the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92 and the other end opening to the outside of the cylinder 2, and an information acquisition unit 200 that acquires information regarding the hydrogen concentration in the fluid flowing out of the cylinder 2 through the flow path portion 95. The control device 60 stops the operation of the hydrogen liquefied pump 101 when it is determined based on the information regarding the hydrogen concentration acquired by the information acquisition unit 200 that the hydrogen concentration in the fluid exceeds a preset reference value.

[0091] This liquefied hydrogen pump system 100 compresses the liquefied hydrogen introduced into the cylinder 2 from the outside and discharges it outside the cylinder 2 by reciprocating the piston 1 in the cylinder 2 in the direction of the axis O via the rod 8 by the drive unit 3. When a part of the liquefied hydrogen in the cylinder 2 leaks through the gap S between the first seal member 91 and the outer peripheral surface of the rod 8, the liquefied hydrogen or the hydrogen gas generated by the vaporization of the liquefied hydrogen flows into the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92. The hydrogen that has flowed into the gap S between the rod 8 and the cylinder 2 circulates through the flow path portion 95 as a fluid and is discharged to the outside of the cylinder 2. The information acquisition unit 200 acquires information regarding the hydrogen concentration in the fluid that circulates outside the cylinder 2 through the flow path portion 95. When hydrogen circulates in the flow path portion 95, the information regarding the hydrogen concentration acquired by the information acquisition unit 200 changes. When it is determined based on the information regarding the hydrogen concentration acquired by the information acquisition unit 200 that the hydrogen concentration in the fluid exceeds a preset reference value, the control device 60 stops the operation of the liquefied hydrogen pump 101. In this way, when liquefied hydrogen leaks, by detecting the change in the hydrogen concentration, the operation of the liquefied hydrogen pump 101 can be stopped, and the hydrogen concentration in the surrounding atmosphere can be suppressed below a determined reference value.

[0092] (2) The liquefied hydrogen pump system 100 according to the second aspect is the liquefied hydrogen pump system 100 of (1), wherein the information acquisition unit 200 acquires the flow rate of the fluid as the information regarding the hydrogen concentration, and the control device 60 stops the operation of the liquefied hydrogen pump 101 when the flow rate of the fluid is equal to or greater than a preset flow rate threshold.

[0093] As a result, when a part of the liquefied hydrogen in the cylinder 2 passes through the gap S between the first seal member 91 and the outer peripheral surface of the rod 8, the hydrogen (liquefied hydrogen or hydrogen gas) flowing into the gap S between the rod 8 and the cylinder 2 flows through the flow path portion 95 as a fluid. Therefore, the greater the flow rate of the fluid flowing through the flow path portion 95, the greater the hydrogen leakage amount. Thus, the flow rate of the fluid in the flow path portion 95 is acquired as information regarding the hydrogen concentration. When the flow rate of the fluid is equal to or greater than a preset flow rate threshold value, 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 be equal to or lower than a defined reference value.

[0094] (3) The liquefied hydrogen pump system 100 according to the third aspect is the liquefied hydrogen pump system 100 of (1) or (2), wherein the information acquisition unit 200 acquires the temperature of the fluid as information regarding the hydrogen concentration, and the control device 60 stops the operation of the liquefied hydrogen pump 101 when the temperature of the fluid is lower than a preset temperature threshold value.

[0095] As a result, when a part of the liquefied hydrogen in the cylinder 2 passes through the gap S between the first seal member 91 and the outer peripheral surface of the rod 8, the hydrogen flowing into the gap S between the rod 8 and the cylinder 2 flows through the flow path portion 95 as a fluid. The greater the flow rate of the hydrogen flowing through the flow path portion 95, the lower the temperature of the fluid. For this reason, the temperature of the fluid in the flow path portion 95 is acquired as information regarding the hydrogen concentration. When the temperature of the fluid is lower than a preset temperature threshold value, 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 be equal to or lower than a defined reference value.

[0096] (4) The hydrogen liquefied pump system 100 according to the fourth aspect is any one of the hydrogen liquefied pump systems 100 from (1) to (3), and the seal parts 9A to 9E further include an atmospheric temperature detection part 203 for detecting the atmospheric temperature outside the cylinder 2. When the atmospheric temperature detected by the atmospheric temperature detection part 203 is less than a preset atmospheric temperature threshold value, the control device 60 stops the operation of the hydrogen liquefied pump 101.

[0097] When the atmospheric temperature is so low that moisture in the atmosphere freezes, the second seal member 92 may be damaged by the frozen moisture (ice). In contrast, when the atmospheric temperature is less than a preset atmospheric temperature threshold value, the operation of the hydrogen liquefied pump 101 is stopped. Thereby, by preventing the hydrogen liquefied pump 101 from operating in a temperature environment where moisture in the atmosphere freezes, damage to the second seal member 92 can be suppressed. As a result, leakage of hydrogen from between the damaged second seal member 92 and the rod 8 can be suppressed.

[0098] (5) The hydrogen liquefied pump system 100 according to the fifth aspect is the hydrogen liquefied pump system 100 of (4), and the seal part 9C further includes a heater 98 for heating the second seal member 92. When the atmospheric temperature detected by the atmospheric temperature detection part 203 is less than a preset temperature threshold value, the control device 60 heats the second seal member 92 with the heater 98.

[0099] Thereby, when the atmospheric temperature is less than a preset atmospheric temperature threshold value, by heating the second seal member 92 with the heater 98, the temperature of the second seal member 92 and its vicinity can be raised. Thereby, even in a temperature environment where moisture in the atmosphere freezes, freezing of moisture in the atmosphere can be suppressed. As a result, damage to the second seal member 92 caused by frozen moisture can be suppressed, and leakage of hydrogen from between the second seal member 92 and the rod 8 can be suppressed.

[0100] (6) The hydrogen liquefier pump system 100 according to the sixth aspect is any one of the hydrogen liquefier pump systems 100 from (1) to (5), and the seal parts 9A to 9E further include a hydrogen concentration detection unit 202 that detects the hydrogen concentration in the atmosphere outside the cylinder 2. When the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit 202 is equal to or higher than a preset hydrogen concentration threshold, the control device 60 stops the operation of the hydrogen liquefier pump 101.

[0101] Thereby, when the hydrogen concentration in the atmosphere is equal to or higher than a preset hydrogen concentration threshold, by stopping the operation of the hydrogen liquefier pump 101, it is possible to suppress the further increase in the hydrogen concentration in the atmosphere due to the hydrogen leaking from the hydrogen liquefier pump 101.

[0102] (7) The hydrogen liquefier pump system 100 according to the seventh aspect is any one of the hydrogen liquefier pump systems 100 from (1) to (6), and the seal parts 9A to 9E are formed in the cylinder 2, and an inert gas supply passage portion 96 for supplying inert gas from the outside of the cylinder 2 to the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92 is further provided.

[0103] Thereby, when inert gas is supplied from the outside of the cylinder 2 through the inert gas supply passage portion 96, the gap S between the rod 8 and the cylinder 2 between the first seal member 91 and the second seal member 92 and the passage portion 95 communicating with this gap S can be filled with inert gas. Therefore, in the hydrogen liquefier pump 101 in the initial state before operation, by filling with inert gas, even if hydrogen flows into the gap S between the rod 8 and the cylinder 2, the hydrogen flows into the inert gas containing no oxygen. Thereby, the hydrogen concentration in the atmosphere does not reach the lower explosion limit, and the hydrogen liquefier pump system can be operated safely.

[0104] (8) The liquefied hydrogen pump system 100 according to the eighth aspect is 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 passage portion 96 communicates with the gap S between the rod 8 and the cylinder 2 at a position above one end of the passage portion 95.

[0105] Thus, when an inert gas is supplied from the outside of the cylinder 2 through the inert gas supply passage portion 96, the atmosphere existing in the inert gas supply passage portion 96 and the gap S between the rod 8 and the cylinder 2 at that time is pushed downward as the inert gas is supplied. As a result, the pushed atmosphere is pushed out of the liquefied hydrogen pump 101 through the passage portion 95 from the gap S between the rod 8 and the cylinder 2. Thereby, the inside of the liquefied hydrogen pump 101 can be efficiently replaced with the inert gas. An example of the inert gas having a specific gravity smaller than that of the atmosphere is helium.

[0106] (9) The liquefied hydrogen pump system 100 according to the ninth aspect is the liquefied hydrogen pump system 100 of any one of (1) to (8), wherein the distance D between the first seal member 91 and the second seal member 92 in the direction of the axis O is larger than the movement stroke of the rod 8 in the direction of the axis O.

[0107] By making the distance D between the first seal member 91 and the second seal member 92 larger than the moving stroke of the rod 8, when the rod 8 moves in the direction of the axis O, it is possible to suppress foreign matter or the like generated by the sliding between the second seal member 92 and the rod 8 from reaching the sliding portion between the lower first seal member 91 and the rod 8. Thereby, it is possible to suppress damage to the first seal member 91 caused by foreign matter or the like generated by the sliding between the second seal member 92 and the rod 8. Further, it is possible to suppress foreign matter or the like generated by the sliding between the first seal member 91 and the rod 8 from reaching the sliding portion between the second seal member 92 and the rod 8. Thereby, it is possible to suppress damage to the second seal member 92 caused by foreign matter or the like generated by the sliding between the first seal member 91 and the rod 8.

[0108] (10) The hydrogen liquefied pump system 100 according to the tenth aspect is any one of the hydrogen liquefied pump systems 100 according to (1) to (9), and is formed on the second seal member 92 on the side separated from the piston 1 in the direction of the axis O, and further includes an air circulation portion 39 through which air circulates, and a dust seal 99 provided in the air circulation portion 39 and covering the second seal member 92.

[0109] Thereby, it is possible to suppress foreign matter or the like existing in the air flowing through the air circulation portion 39 from entering the gap S between the rod 8 and the second seal member 92 by the dust seal 99 provided in the air circulation portion 39.

[0110] (11) The hydrogen liquefied pump system 100 according to the eleventh aspect is any one of the hydrogen liquefied pump systems 100 according to (1) to (10), and further includes an inner wall surface 94 formed on the cylinder 2 between the first seal member 91 and the second seal member 92 and separated radially outward of the rod 8 with respect to the outer peripheral surface of the rod 8, and a recess 300 formed below the inner wall surface 94 and recessed radially outward from the inner wall surface 94 between the first seal member 91 and the second seal member 92.

[0111] As a result, by providing the concave portion 300 at a position below the inner wall surface 94, wear powder and the like of the second seal member 92 generated by the sliding between the second seal member 92 and the rod 8 can be collected in the concave portion 300. Thereby, when the rod 8 moves in the direction of the axis O, it is possible to suppress foreign matter and the like generated by the sliding between the second seal member 92 and the rod 8 from reaching the sliding portion between the lower first seal member 91 and the rod 8. Thereby, it is possible to suppress damage to the first seal member 91 caused by foreign matter and the like generated by the sliding between the second seal member 92 and the rod 8.

[0112] (12) The control method of the liquefied hydrogen pump system 100 according to the 12th aspect is the control method of the liquefied hydrogen pump system 100 according to any one of (1) to (11), and includes a step of obtaining information on the hydrogen concentration in the fluid flowing out of the cylinder 2 through the flow path portion 95, steps S13 and S23 of determining whether or not the hydrogen concentration in the fluid exceeds a preset reference value based on the obtained information on the hydrogen concentration, and a step S17 of 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.

[0113] As a result, information on the hydrogen concentration in the fluid flowing out of the cylinder 2 is obtained, and when it is determined based on the obtained information on the hydrogen concentration 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, when liquefied hydrogen leaks, by detecting a change in the hydrogen concentration, the hydrogen concentration in the surrounding atmosphere can be suppressed below a determined reference value.

Explanation of reference numerals

[0114] 1…Piston 2…Cylinder 3…Drive unit 4…Casing 4t…Upper surface 5…Check valve 6…Discharge pipe 7… Discharge valve 8… Rod 9A~9E… Seal part 10… Piston body 11… Wear ring 12… Piston ring 20… Cylinder body 21… Compression chamber 31… Eccentric shaft part 32… Rotating body 33… Link part 33a… Upper annular part 33b… Connection part 33c… Lower annular part 35… Rocking shaft part 36… Crosshead 37… Housing 37a… Top plate 37b… Bottom plate 38… Wear band 39… Air flow part 39a… Air inlet 39b… Air outlet 41… Casing body 42… Supply pipe 43… Gas discharge pipe 44… Liquid storage chamber 45… Cylindrical part 60… Control device 61… CPU 62… ROM 63… RAM 64… Storage 65… Communication module 71… Input part 72… Pump control part 73… Command signal output part 90, 90E… Seal part body 90a… Insertion cylinder part 90b… Diameter-expanded part 90m, 90n… Groove 91… First seal member 92… Second seal member 94… Inner wall surface 95… Flow path part 95a… One end 95b… The other end 95p… Pipe 95r… Hydrogen recovery section 95v… On-off valve 96… Inert gas supply passage section 96a… One end 96b… The other end 96p… Pipe 96v… On-off valve 98… Heater 99… Dust seal 99a… Fixed part 99b… Overhanging part 100… Liquid hydrogen pump system 101… Liquid hydrogen pump 200… Information acquisition section 201… Flow meter 202… Hydrogen concentration detection section 203… Ambient temperature detection section 205… Thermometer 206… Thermometer 300… Concave part 300b… Bottom surface 301… Guide O… Axis S… Gap

Claims

1. A liquid hydrogen pump for compressing liquid hydrogen, and A control device for controlling the operation of the liquid hydrogen pump, a liquid hydrogen pump system comprising: The liquid hydrogen pump, A cylindrical cylinder extending in the axial direction, Provided in the cylinder so as to be reciprocable in the axial direction, compressing the liquid hydrogen introduced into the cylinder from the outside, and a piston discharged outside the cylinder, One end is connected to the piston in the cylinder, and the other end is a rod protruding outside the cylinder, Connected to the other end of the rod, a drive unit for reciprocating the piston in the axial direction in the cylinder via the rod, A seal part, The seal part, A first seal member for sealing the gap between the rod and the cylinder, With respect to the first seal member, a second seal member provided at an interval in a direction away from the piston in the axial direction and sealing between the rod and the cylinder, Formed in the cylinder, one end communicates with the gap between the rod and the cylinder between the first seal member and the second seal member, and the other end is a flow path portion opening to the outside of the cylinder, An information acquisition unit for acquiring information regarding the hydrogen concentration in the fluid flowing out to the outside of the cylinder through the flow path portion, The control device stops the operation of the liquid hydrogen pump when it is determined that the hydrogen concentration in the fluid exceeds a preset reference value based on the information regarding the hydrogen concentration acquired by the information acquisition unit Liquid hydrogen pump system.

2. The information acquisition unit acquires the flow rate of the fluid as information regarding the hydrogen concentration, The control device stops the operation of the liquid hydrogen pump when the flow rate of the fluid is equal to or greater than a preset flow rate threshold The liquid hydrogen pump system according to claim 1.

3. The information acquisition unit acquires the temperature of the fluid as information regarding the hydrogen concentration, The control device stops the operation of the liquid hydrogen pump when the temperature of the fluid is less than a preset temperature threshold The liquid hydrogen pump system according to claim 1 or 2.

4. The seal part, Further comprising an atmospheric temperature detection unit for detecting the atmospheric temperature outside the cylinder, When the atmospheric temperature detected by the atmospheric temperature detection unit is less than a preset atmospheric temperature threshold value, the control device stops the operation of the liquefied hydrogen pump. The liquefied hydrogen pump system according to claim 1 or 2.

5. The seal part further includes a heater for heating the second seal member. When the atmospheric temperature detected by the atmospheric temperature detection unit is less than a preset atmospheric temperature threshold value, the control device heats the second seal member with the heater. The liquefied hydrogen pump system according to claim 4.

6. The seal part further includes a hydrogen concentration detection unit that detects the hydrogen concentration in the atmosphere outside the cylinder. When the hydrogen concentration in the atmosphere detected by the hydrogen concentration detection unit is equal to or higher than a preset hydrogen concentration threshold value, the control device stops the operation of the liquefied hydrogen pump. The liquefied hydrogen pump system according to claim 1 or 2.

7. The seal part further includes an inert gas supply passage part formed in the cylinder, through which an inert gas is supplied from the outside of the cylinder into the gap between the rod and the cylinder. The liquefied hydrogen pump system according to claim 1 or 2.

8. The inert gas has a specific gravity smaller than that of the atmosphere. One end of the inert gas supply passage part communicates with the gap between the rod and the cylinder at a position above one end of the passage part. The liquefied hydrogen pump system according to claim 7.

9. The distance between the first seal member and the second seal member in the axial direction is larger than the moving stroke of the rod in the axial direction. The liquefied hydrogen pump system according to claim 1 or 2.

10. an air circulation part formed on the side of the second seal member away from the piston in the axial direction, through which air circulates; and a dust seal provided in the air circulation part to cover the gap between the rod and the second seal member. The liquefied hydrogen pump system according to claim 1 or 2.

11. an inner wall surface formed in the cylinder between the first seal member and the second seal member, with a gap in the radially outer direction of the rod with respect to the outer peripheral surface of the rod; and a recess formed below the inner wall surface and recessed radially outward from the inner wall surface between the first seal member and the second seal member. The liquid hydrogen pump system according to claim 1 or 2.

12. A control method for a liquid hydrogen pump system according to claim 1 or 2, the step of obtaining information regarding the hydrogen concentration in the fluid flowing out of the cylinder through the flow path portion; the step of determining whether or not the hydrogen concentration in the fluid exceeds a preset reference value based on the obtained information regarding the hydrogen concentration; and the step of stopping the operation of the liquid hydrogen pump when it is determined that the hydrogen concentration in the fluid exceeds a preset reference value. A control method for a liquid hydrogen pump system.

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