Booster pump, low-temperature fluid supply system, and method for discharging low-temperature fluid in booster pump

Abstract

To inhibit leakage of a low-temperature fluid stored inside a booster pump and inhibit state change of the low-temperature fluid in the booster pump, a low-temperature fluid supply system, and a method for discharging the low-temperature fluid in the booster pump.SOLUTION: A booster pump includes: a casing that stores a low-temperature fluid; a cylinder that is disposed inside the casing, has a compression chamber, and has an upper end in a vertical direction supported by an upper part of the casing; a piston that is supported inside the cylinder so as to be movable along the vertical direction and compresses the low-temperature fluid sucked into the compression chamber; and a drain pipe having one end supported by the upper part of the casing and the other end extending to a bottom part of the casing.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a boost pump, a cryogenic fluid supply system, and a method for discharging a cryogenic fluid from a boost pump. [Background technology]

[0002] One of the systems that can achieve carbon neutrality is to use hydrogen gas as fuel. Hydrogen is stored in a tank in liquid hydrogen state, and the liquid hydrogen stored in the tank is vaporized to produce hydrogen gas, which is then supplied to, for example, a fuel cell or a hydrogen engine. The hydrogen supply system includes a boost pump that boosts the pressure of the liquid hydrogen. One example of a boost pump is the technology described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-138950 A Summary of the Invention [Problem to be solved by the invention]

[0004] The boost pump described in Patent Document 1 includes a cylinder, a piston, a drive unit, a sump, an inlet valve, and an outlet valve. The boost pump alternately sucks in and compresses the liquid by vertically reciprocating the piston, and discharges the high-pressure liquid to the outside. During maintenance, the boost pump needs to discharge all of the liquid stored in the sump to the outside. Conventional boost pumps have a sealed connection at the bottom end of the sump, and discharge the liquid remaining in the sump from the sealed connection to the outside. However, if there is a liquid discharge unit for maintenance at the bottom end of the sump, there is a concern that the liquid may leak to the outside during operation of the boost pump. In addition, if the liquid stored in the sump is a low-temperature fluid, external heat may be transmitted from the liquid discharge unit to the sump, causing the temperature of the liquid to rise and vaporize.

[0005] The present disclosure is devised to solve the above-mentioned problems, and aims to provide a boost pump and a low-temperature fluid supply system that are capable of suppressing leakage of the low-temperature fluid stored therein and suppressing changes in the state of the low-temperature fluid, and a method for discharging the low-temperature fluid in the boost pump. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the boost pump of the present disclosure comprises a casing for storing a low-temperature fluid, a cylinder disposed inside the casing and having a compression chamber, the cylinder having an upper vertical end supported on an upper portion of the casing, a piston supported inside the cylinder so as to be freely movable along the vertical direction and compressing the low-temperature fluid sucked into the compression chamber, and a drain pipe having one end supported on the upper portion of the casing and the other end extending to the bottom of the casing.

[0007] The cryogenic fluid supply system of the present disclosure also includes a compression device having the boost pump and compressing a cryogenic fluid, an evaporation device which vaporizes the cryogenic fluid compressed by the compression device, and a dispenser which supplies the gas vaporized by the evaporation device.

[0008] In addition, a method of discharging low-temperature fluid in a boost pump disclosed herein includes a boost pump including a casing for storing low-temperature fluid, a cylinder disposed inside the casing and having a compression chamber, the cylinder having a vertical upper end supported on an upper portion of the casing, and a piston supported inside the cylinder for movement freely along the vertical direction and compressing the low-temperature fluid sucked into the compression chamber, the method comprising the steps of: moving the piston back and forth inside the cylinder to discharge to the outside the high-pressure low-temperature fluid pressurized in the compression chamber; stopping the reciprocating movement of the piston when it becomes impossible to suck low-temperature fluid into the compression chamber; and discharging to the outside the low-temperature fluid remaining in the casing using a drain pipe having one end supported on the upper portion of the casing and the other end extended to the bottom of the casing. Effect of the Invention

[0009] According to the boost pump and the cryogenic fluid supply system of the present disclosure, leakage of the cryogenic fluid stored therein can be suppressed, and changes in the state of the cryogenic fluid can be suppressed. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram showing the overall configuration of a hydrogen supply system according to the first embodiment. [Diagram 2] FIG. 2 is a vertical cross-sectional view illustrating the compression device of the first embodiment. [Diagram 3] FIG. 3 is a horizontal cross-sectional view (cross-sectional view taken along line III-III in FIG. 2) illustrating the boost pump of the first embodiment. [Figure 4] FIG. 4 is a vertical cross-sectional view showing a lower part of the boost pump of the second embodiment. [Diagram 5] FIG. 5 is a schematic diagram showing the tip of the drain pipe. [Figure 6] FIG. 6 is a bottom cross-sectional view showing a boost pump of the first modified example. [Figure 7] FIG. 7 is a bottom cross-sectional view showing a boost pump of the second modified example. [Figure 8] FIG. 8 is a cross-sectional view taken along line VIII-VIII of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes a configuration in which each embodiment is combined. In addition, the components in the embodiments include those that a person skilled in the art can easily imagine, those that are substantially the same, and those that are within the so-called equivalent range.

[0012] [First embodiment] <Hydrogen supply system> FIG. 1 is a schematic diagram showing the overall configuration of a hydrogen supply system according to the first embodiment.

[0013] As shown in FIG. 1, a hydrogen supply system (low-temperature fluid supply system) 10 supplies (replenishes) liquid hydrogen stored in a container 11 as hydrogen gas at a predetermined pressure to a power source of a vehicle 12. Here, the power source is, for example, a fuel cell or a hydrogen engine, and is mounted on the vehicle 12. The hydrogen supply system 10 is, for example, a so-called hydrogen station that supplies (replenishes) hydrogen gas, which is a fuel, to the power source of the vehicle 12. However, the hydrogen supply system 10 is not limited to one that supplies hydrogen gas to the power source of the vehicle 12, but also includes one that supplies hydrogen gas to a tank of a trailer for transporting hydrogen. The hydrogen supply system 10 also operates in the same way when compressing and supplying not only hydrogen but also a low-temperature fluid (for example, liquid hydrogen, liquid nitrogen, liquid oxygen, liquefied carbon dioxide, liquefied natural gas, liquefied propane gas, etc.).

[0014] The hydrogen supply system 10 has a compressor 21, an evaporator 22, and a dispenser 23. The compressor 21 compresses liquid hydrogen (low-temperature fluid) supplied from the container 11 to a predetermined high pressure (high-pressure state) that is set in advance. The evaporator 22 generates hydrogen gas by vaporizing the high-pressure liquid hydrogen compressed by the compressor 21. The dispenser 23 fills the hydrogen gas generated by the evaporator 22 into the power source of the vehicle 12.

[0015] Although the compression device 21 compresses the liquid hydrogen stored in the container 11 to a predetermined high pressure, the present invention is not limited to this configuration.

[0016] The compression device 21 has a drive unit 31 and a boost pump 32. The drive unit 31 has a drive motor and a drive mechanism, not shown. The drive motor is an electric motor that can be driven by power supplied from the outside. The rotation speed of the drive motor is controlled by an inverter (not shown). The drive mechanism has a crank mechanism and converts the rotation power of the drive motor into linear reciprocating power. The drive motor transmits the rotation power to the drive mechanism, and the drive mechanism transmits the linear reciprocating power to the boost pump 32. The boost pump 32 is operated by the drive unit 31 and compresses the liquid hydrogen. The drive unit 31 may have a reducer between the drive motor and the drive mechanism.

[0017] <Compression device> FIG. 2 is a vertical cross-sectional view showing the compression device of the first embodiment, and FIG. 3 is a horizontal cross-sectional view (cross-section taken along line III-III in FIG. 2) showing the boost pump of the first embodiment.

[0018] 2, the compressor 21 has a drive unit 31 and a boost pump 32, and the drive unit 31 has a drive motor 33 and a drive mechanism 34. The compressor 21 (boost pump 32) is a device for boosting the pressure of liquid hydrogen, which is a cryogenic liquid, to a high pressure (about 90 MPa).

[0019] <Drive unit> The drive mechanism 34 includes an eccentric shaft portion 41, a rotor 42, a link portion 43, a swing shaft portion 44, a crosshead 45, and a housing 46.

[0020] The eccentric shaft portion 41 has a cylindrical shape and is disposed along the horizontal direction. The eccentric shaft portion 41 is supported so as to be rotatable about an axis O1 along the horizontal direction. The tip portion of the output shaft 33a of the drive motor 33 is connected to the eccentric shaft portion 41. When the drive motor 33 is driven, the output shaft 33a rotates, and the rotational power of the output shaft 33a is transmitted to the eccentric shaft portion 41, causing the eccentric shaft portion 41 to rotate.

[0021] The rotor 42 has a disk shape, is disposed outside the eccentric shaft portion 41, and is capable of rotating integrally with the eccentric shaft portion 41. The rotor 42 has a center along the axis O2, and the center (axis O2) of the rotor 42 and the center (axis O1) of the eccentric shaft portion 41 are shifted in the radial direction. In other words, the center (axis O1) of the eccentric shaft portion 41 is provided at a position opposite to the center (axis O2) of the rotor 42. When the eccentric shaft portion 41 rotates, the rotor 42 oscillates and rotates about the axis O1.

[0022] The link portion 43 constitutes a crank mechanism, converts the rotational power into linear reciprocating power, and transmits it to the boost pump 32. The link portion 43 has an upper annular portion 43a, a connecting portion 43b, and a lower annular portion 43c. The upper annular portion 43a is in a circular ring shape. The upper annular portion 43a is disposed outside the rotor 42 via a bearing portion (not shown), and is rotatable relative to the rotor 42. The lower annular portion 43c is in a circular ring shape. The connecting portion 43b is disposed between the upper annular portion 43a and the lower annular portion 43c, and integrally connects the upper annular portion 43a and the lower annular portion 43c.

[0023] When the eccentric shaft portion 41 rotates and the rotor 42 oscillates and rotates about the axis O1, the link portion 43 is actuated. That is, in the link portion 43, the upper annular portion 43a oscillates about the axis O1 due to the rotation of the rotor 42, the oscillating force of the upper annular portion 43a is transmitted to the lower annular portion 43c via the connection portion 43b, and the lower annular portion 43c moves linearly back and forth in the vertical direction while rotating about the axis O3 parallel to the axes O1 and O2.

[0024] The oscillating shaft portion 44 has an upper end connected to a lower end of the lower annular portion 43c of the link portion 43. The oscillating shaft portion 44 has a lower end connected to an upper end of a piston 53 (described later) of the boost pump 32. The oscillating shaft portion 44 is oscillable between the lower annular portion 43c and the piston 53 about an oscillating axis that is horizontal to the lower annular portion 43c and the piston 53.

[0025] The crosshead 45 has a bottomed cylindrical shape that covers the lower annular portion 43c from the outside. The housing 46 is disposed on the outer periphery of the crosshead 45. The housing 46 is supported on a stand (not shown), and the crosshead 45 is supported so as to be movable in the vertical direction relative to the housing 46. The lower annular portion 43c of the link portion 43 is supported so as to be rotatable by the crosshead 45. When the eccentric shaft portion 41 and the rotating body 42 rotate and the link portion 43 swings back and forth in the vertical direction, the lower annular portion 43c and the crosshead 45 move back and forth in the vertical direction relative to the housing 46.

[0026] <Booster pump> As shown in FIGS. 2 and 3, the boost pump 32 includes a casing 51, a cylinder 52, and a piston 53.

[0027] <Casing> The casing 51 is a pressure vessel for storing liquid hydrogen, and is also a heat-insulating vacuum vessel. The support plate 61 is arranged along the horizontal direction and is installed on a stand (not shown). The support plate 61 is provided with a through hole 61a at a position on an axis O4 along the vertical direction. The casing 51 has a casing main body 51a, an intermediate flange portion 51b, a support cylinder portion 51c, and an upper flange portion 51d. The casing main body 51a is a heat-insulating structure having a bottomed cylindrical shape, and an internal liquid storage chamber 62 is formed. The intermediate flange portion 51b is disc-shaped, and a circular hole is formed at the center position. The intermediate flange portion 51b is fastened integrally to the upper end of the casing main body 51a. The intermediate flange portion 51b is provided integrally with a support cylinder portion 51c having a smaller diameter than the casing main body 51a at the upper portion. The support cylinder 51c has an upper flange 51d formed integrally with the upper end thereof, the upper flange 51d having a larger diameter than the support cylinder 51c, and a circular hole is formed in the center of the upper flange 51d. The upper flange 51d of the casing 51 is in close contact with the lower surface of the support plate 61 and is fastened with bolts. That is, the upper end of the casing 51 is supported by being suspended from the support plate 61.

[0028] Casing 51 has a supply pipe 63 and a gas discharge pipe 64 connected to the side of casing body 51a. Supply pipe 63 is a pipe for supplying liquid hydrogen from an external supply source to liquid storage chamber 62 of casing 51. Supply pipe 63 is provided near the bottom of casing 51. Gas discharge pipe 64 is a pipe for discharging components (hydrogen gas) vaporized in liquid storage chamber 62 to the outside. Gas discharge pipe 64 is disposed at a position spaced above supply pipe 63. Liquid hydrogen is stored in liquid storage chamber 62, and the liquid level of the liquid hydrogen is adjusted to be located below gas discharge pipe 64.

[0029] <Cylinder> The cylinder 52 is a container for compressing liquid hydrogen. The cylinder 52 has a cylinder body 62a and a flange portion 62b. The cylinder body 52a has a bottomed cylindrical shape, and a compression chamber 65 is provided at the lower side inside. The cylinder body 52a is integrally provided with a flange portion 52b having a larger diameter than the cylinder body 52a at the upper end, and the flange portion 52b is open at the center. The flange portion 52b of the cylinder 52 fits into the through hole 61a of the support plate 61, and the cylinder 52 is placed on the upper surface of the upper flange portion 51d of the casing 51. That is, the upper end of the cylinder 52 is supported by being suspended from the support plate 61. A seal member (not shown) is provided between the flange portion 52b of the cylinder 52 and the upper flange portion 51d of the casing 51.

[0030] A suction valve 66 is provided at the bottom of the cylinder 52. The suction valve 66 is for introducing liquid hydrogen from the liquid storage chamber 62 into the compression chamber 65. That is, the suction valve 66 is a check valve, and opens when the pressure in the compression chamber 65 becomes lower than the pressure in the liquid storage chamber 62, and the liquid hydrogen from the liquid storage chamber 62 is introduced into the compression chamber 65. On the other hand, when the pressure in the compression chamber 65 becomes higher than the pressure in the liquid storage chamber 62, the check valve closes, and the liquid hydrogen in the compression chamber 65 is prevented from flowing back into the liquid storage chamber 62. Note that, although FIG. 2 shows the suction valve 66 exposed to the outside of the cylinder 52, FIG. 2 is a schematic diagram, and the suction valve 66 is actually provided inside the cylinder 52.

[0031] A discharge valve 67 is provided on the lower side of the cylinder 52. The discharge valve 67 is for discharging (discharging) the high-pressure liquid water compressed in the compression chamber 65 to the outside. That is, the discharge valve 67 is a check valve, which opens when the pressure in the compression chamber 65 becomes higher than the pressure on the discharge side, and discharges the high-pressure liquid hydrogen in the compression chamber 65 to the outside. On the other hand, when the pressure in the compression chamber 65 becomes lower than the pressure on the discharge side, the discharge valve closes, and the high-pressure liquid hydrogen on the discharge side is prevented from flowing back to the compression chamber 65. Note that, although FIG. 2 shows the discharge valve 67 exposed to the outside of the cylinder 52, FIG. 2 is a schematic diagram, and the discharge valve 67 is actually provided inside the cylinder 52.

[0032] A discharge pipe 68 is connected to the discharge valve 67. The discharge pipe 68 is a pipe for discharging high-pressure liquid hydrogen compressed in the compression chamber 35 to the outside. The discharge pipe 68 is disposed inside the casing 51 adjacent to the cylinder 52. The cylinder 52 is disposed at a position (axis O4) shifted to one side in the radial direction from the center (axis O5) of the casing 51. The discharge pipe 68 is disposed at a position shifted to the other side in the radial direction from the center (axis O5) of the casing 51. The discharge pipe 68 is disposed along the vertical direction, and a lower end portion is connected to a lower portion of the cylinder 52 and communicates with the compression chamber 65 via the discharge valve 67. The discharge pipe 68 has an upper end portion that penetrates the upper portion of the casing 51 and extends to the outside, and is supported by the upper portion of the casing 51.

[0033] <Piston> The piston 53 has a piston body 53a, a wear ring 53b, and a piston ring 53c. The piston body 53a has a long cylindrical shape and is disposed inside the cylinder 52. The piston body 53a is disposed along an axis O4 along the vertical direction. The piston body 53a has a constant outer diameter over the entire area in the direction of the axis O4. The piston body 53a has an upper end connected to the drive unit 31.

[0034] A plurality of wear rings 53b and a plurality of piston rings 53c are attached to the lower end of the piston body 53a. The wear ring 53b is attached to the tip of the piston body 53a. The wear ring 53b has an annular shape centered on the axis O4 and is made of a resin material. The piston ring 53c is attached to the tip of the piston body 53a. The piston ring 53c has an annular shape centered on the axis O4 and is made of a resin material.

[0035] That is, the piston 53 is provided with one wear ring 53b at the lower end of the piston body 53a, and another wear ring 53b is provided at a distance from the wear ring 53b in the direction of the axis O4. The piston 53 is provided with a plurality of piston rings 53c at intervals in the direction of the axis O4 between the pair of wear rings 53b. The wear ring 53b is provided to guide the piston body 53a along the inner circumferential surface of the cylinder 52. The piston ring 53c is provided to maintain liquid-tightness and air-tightness between the piston 53 and the inner circumferential surface of the cylinder 52.

[0036] A piston 53 is disposed inside the cylinder 52, and a compression chamber 65 is defined at the lower end. The piston 53 reciprocates inside the cylinder 52 along the direction of the axis O4 by the drive unit 31. When the piston 53 moves upward inside the cylinder 52, the volume of the compression chamber 65 expands, the pressure decreases, and liquid hydrogen is sucked in. When the piston 53 moves downward inside the cylinder 52, the volume of the compression chamber 65 contracts, the pressure increases, and the liquid hydrogen is compressed. Note that a seal member is provided on the opening inner circumferential surface of the flange portion 52d of the cylinder 52 to seal the gap with the outer circumferential surface of the piston body 53a.

[0037] <Cylinder and piston arrangement> The cylinder 52 is disposed at a position shifted from the center of the casing 51 to one side in the radial direction. That is, the center position of the cylinder 52 is located on the axis O4. The center position of the casing 51 is located on the axis O5. That is, in the casing 51, the center position of the casing main body 51a is located on the axis O5, and the center positions of the support tube portion 51c and the upper flange portion 51d are located on the axis O4. Therefore, the center (axis O4) of the cylinder 52 is disposed at a predetermined distance shifted from the center (axis O5) of the casing main body 51a of the casing 51 to one side in the radial direction.

[0038] <Liquid hydrogen discharge device> The boost pump 32 includes a casing 51, a cylinder 52, a piston 53, and a liquid hydrogen discharge device 54.

[0039] The liquid hydrogen discharge device 54 has a drain pipe 71 and a pressurizing pipe 72. The drain pipe 71 discharges liquid hydrogen remaining in the casing 51 to the outside. One end of the drain pipe 71 is supported on the upper part of the casing 51, and the other end is extended to the bottom of the casing 51. That is, as described above, the casing 51 has a casing main body 51a which is a thermally insulating structure having a bottomed cylindrical shape, and an intermediate flange portion (lid portion) 51b which closes the upper part of the casing main body 51a. The intermediate flange portion 51b is not a thermally insulating structure, but may be a thermally insulating structure. The upper end of the drain pipe 71 is fixed by penetrating the intermediate flange portion 51b in the thickness direction, and the lower end is extended to the vicinity of the bottom surface of the casing 51. In this case, it is preferable that the lower end of the drain pipe 71 is open, and the opening faces the bottom surface of the casing 51 with a small gap therebetween.

[0040] Drain piping 71 is provided with a drain valve 73 outside casing 51. Drain valve 73 is capable of opening and closing the flow path of drain piping 71. One end of drain piping 71 is open to the atmosphere outside casing 51, and when drain valve 73 is opened, liquid storage chamber 62 of casing 51 communicates with the atmosphere. Note that one end of drain piping 71 may not be open to the atmosphere, and may be connected to a liquid hydrogen supply source to which liquid storage chamber 62 is connected via supply pipe 63.

[0041] Pressurization pipe 72 pressurizes the inside of casing 51 (liquid storage chamber 62) by supplying gas from the outside to the inside of casing 51. One end of pressurization pipe 72 is supported on the upper part of casing 51, and the other end is disposed inside casing 51. That is, pressurization pipe 72 has an upper end that penetrates intermediate flange portion 51b in the thickness direction and is fixed, and a lower end that is located in the upper part of casing 51, that is, in the gas phase portion above the liquid level of liquid hydrogen.

[0042] A pressurization source 74 is connected to one end of the pressurization pipe 72 outside the casing, and a pressurization valve 75 is provided in the middle. The pressurization source 74 can supply a fluid for pressurizing the inside of the casing 51 to the pressurization pipe 72. The pressurization valve 75 can open and close the flow path of the pressurization pipe 72. When the pressurization valve 75 is opened, the liquid storage chamber 62 of the casing 51 communicates with the pressurization source 74. It is preferable that the fluid supplied by the pressurization source 74 is a gas obtained by heating the same type of low-temperature fluid as the low-temperature fluid (liquid hydrogen) stored in the casing 51. That is, it is preferable that the pressurization source 74 is connected to the above-mentioned liquid hydrogen supply source, heats the liquid hydrogen to form hydrogen gas, and supplies the hydrogen gas to the pressurization pipe 72.

[0043] <Operation of the compression device> As shown in Fig. 2, when the drive motor 33 is driven, the eccentric shaft portion 41 rotates, and the rotor 42 oscillates and rotates. Then, the link portion 43 operates to convert the rotational power into linear reciprocating power and transmits it to the boost pump 32 via the oscillating shaft portion 44. When the boost pump 32 operates, first, in the suction stroke where the piston 53 rises, the liquid hydrogen in the casing 51 is sucked into the compression chamber 65. Next, in the compression stroke where the piston 53 descends, the liquid hydrogen in the compression chamber 65 is compressed, and the high-pressure liquid hydrogen is discharged to the discharge pipe 68.

[0044] <Booster pump maintenance> During maintenance, the boost pump 32 needs to discharge all of the liquid hydrogen stored in the liquid storage chamber 62 of the casing 51 to the outside. In this case, the lower end of the cylinder 52 is disposed in the lower part of the casing 51. Therefore, when the liquid level of the liquid hydrogen stored in the liquid storage chamber 62 falls below the suction part at the lower end of the cylinder 52, the boost pump 32 cannot compress the liquid hydrogen stored in the liquid storage chamber 62 and discharge it to the outside. In this case, by detecting the flow rate and pressure of the liquid hydrogen discharged from the discharge pipe 68, it is possible to detect the inability of the boost pump 32 to discharge the liquid hydrogen. At this time, the operation of the boost pump 32 is stopped, and then the liquid hydrogen in the liquid storage chamber 62 is discharged to the outside by the liquid hydrogen discharge device 54.

[0045] After the operation of booster pump 32 is stopped, first, pressurization valve 75 is opened. Then, pressurization source 74 supplies hydrogen gas generated by heating liquid hydrogen to liquid storage chamber 62 of casing 51 through pressurization piping 72. In casing 51, liquid storage chamber 62 is pressurized by the hydrogen gas supplied from pressurization piping 72, and the pressure increases. Liquid hydrogen is stored in bottom 51e of casing 51, and this liquid hydrogen is pressurized and heated by the hydrogen gas supplied from pressurization piping 72 to become hydrogen gas.

[0046] Next, the drain valve 73 is opened. The liquid storage chamber 62 of the casing 51 is filled with hydrogen gas and is in a pressurized state. When the flow path of the drain pipe 71 is opened by the drain valve 73, the hydrogen gas in the liquid storage chamber 62 is pushed out to the drain pipe 71 and discharged to the outside through the drain pipe 71. At this time, the unvaporized liquid hydrogen is also discharged to the outside from the drain pipe 71. When all the remaining liquid hydrogen in the liquid storage chamber 62 of the casing 51 is discharged, the drain valve 73 and the pressurizing valve 75 are closed. Note that thereafter, for example, an inert gas (e.g., nitrogen gas) at room temperature may be supplied to the liquid storage chamber 62 of the casing 51 using the pressurizing pipe 72 and discharged to the outside using the drain pipe 71, thereby raising the temperature of the casing 51 to room temperature.

[0047] When liquid hydrogen is discharged from liquid storage chamber 62 of casing 51 and the temperature of casing 51 rises to room temperature, maintenance work on boost pump 32 is carried out.

[0048] In the boost pump 32 of the first embodiment, an upper end of the drain pipe 71 is supported on the top of the casing 51, and the other end extends to the bottom of the casing 51. When the boost pump 32B is in operation, the flow path of the drain pipe 71 is closed by the drain valve 73, but external heat is likely to be transferred through the drain pipe 71 to the liquid hydrogen in the liquid storage chamber 62 of the casing 51. However, since the drain pipe 71 is supported on the top of the casing 51 and a portion of it is disposed in a space filled with hydrogen gas, it is sufficiently cooled and external heat is less likely to be transferred to the liquid hydrogen in the liquid storage chamber 62, making it possible to suppress an increase in the temperature of the liquid hydrogen.

[0049] [Second embodiment] FIG. 4 is a vertical cross-sectional view showing a lower part of a booster pump of the second embodiment, and FIG. 5 is a schematic view showing a tip part of a drain pipe.

[0050] <Liquid hydrogen discharge device> As shown in FIG. 4, the boost pump 32A includes a casing 51, a cylinder 52, a piston 53, and a liquid hydrogen discharge device 54A.

[0051] The liquid hydrogen discharge device 54A has a drain pipe 71A and a pressurizing pipe 72. The pressurizing pipe 72 is the same as in the first embodiment.

[0052] Drain pipe 71A discharges liquid hydrogen remaining in the casing 51 to the outside. One end of drain pipe 71A is supported on the upper part of the casing 51, and the other end extends to the bottom of the casing 51. That is, the upper end of drain pipe 71A is fixed by penetrating intermediate flange portion 51b in the thickness direction, and the lower end extends to the vicinity of the bottom surface of the casing 51.

[0053] The drain pipe 71A is arranged so that its lower end is curved and follows the bottom surface of the casing 51. That is, the casing 51 has a curved shape in which the bottom 51e of the casing body 51a is convex downward in the vertical direction. Therefore, the position of the bottom surface of the center (axis O4) of the bottom 51e of the casing body 51a corresponds to the lowest end position of the liquid storage chamber 62. The drain pipe 71A is arranged so that its lower end is curved and follows the bottom surface of the casing 51, and it is preferable that its lower end is located at the lowest end position of the bottom surface of the bottom 51e.

[0054] As shown in FIGS. 4 and 5, the drain pipe 71A has a straight portion 81, a curved portion 82, and an opening 83. The straight portion 81 is disposed vertically inside the casing body 51a of the casing 51. The curved portion 82 is connected to the lower end of the straight portion 81. The curved portion 82 has an opening 83 formed at a tip portion along the bottom surface of the bottom portion 51e. The opening 83 has an opening surface that is inclined with respect to the axial direction of the drain pipe 71A. That is, the drain pipe 71A (straight portion 81, curved portion 82) is a cylindrical pipe, but by cutting the tip portion at an angle, the opening surface of the opening 83 becomes elliptical.

[0055] Like the drain pipe 71, the drain pipe 71A is provided with a drain valve 73 (see FIG. 2) outside the casing 51.

[0056] Therefore, when the pressurization valve 75 (see FIG. 2) is opened after the operation of the boost pump 32A is stopped, heated hydrogen gas is supplied to the liquid storage chamber 62 of the casing 51 through the pressurization piping 72. The hydrogen gas supplied from the pressurization piping 72 pressurizes the liquid storage chamber 62 of the casing 51, and the pressure increases. Also, liquid hydrogen is stored in the bottom 51e of the casing 51, and this liquid hydrogen is pressurized and heated by the hydrogen gas supplied from the pressurization piping 72 to become hydrogen gas.

[0057] When drain valve 73 (see FIG. 2) is opened, hydrogen gas in liquid storage chamber 62 of casing 51 is pushed out to drain piping 71A and discharged to the outside through drain piping 71A. At this time, because opening 83 of drain piping 71A is located on the bottom surface of bottom 51e of casing 51, all of the liquid hydrogen remaining in bottom 51e of liquid storage chamber 62 of casing 51 can be discharged to the outside. When all of the liquid hydrogen remaining in liquid storage chamber 62 of casing 51 has been discharged, drain valve 73 and pressurization valve 75 are closed.

[0058] <Modification> FIG. 6 is a bottom cross-sectional view showing a boost pump of the first modified example.

[0059] As shown in FIG. 6, the boost pump 32B of the first modified example includes a casing 51, a cylinder 52, a piston 53, and a liquid hydrogen discharge device 54B.

[0060] The liquid hydrogen discharge device 54B has a drain pipe 71B and a pressurizing pipe 72. The pressurizing pipe 72 is the same as in the first embodiment.

[0061] Drain pipe 71B discharges liquid hydrogen remaining in the casing 51 to the outside. One end of drain pipe 71B is supported on the upper part of the casing 51, and the other end extends to the bottom of the casing 51. That is, the upper end of drain pipe 71B is fixed by penetrating intermediate flange portion 51b in the thickness direction, and the lower end extends to the vicinity of the bottom surface of the casing 51.

[0062] Drain pipe 71B is arranged so that its lower end is curved and runs along the bottom surface of casing 51. Drain pipe 71B has a straight portion 81, a curved portion 82, an opening 83, and a spiral portion 84. Straight portion 81 is arranged along the vertical direction inside casing body 51a of casing 51. The spiral portion 84 is connected to the lower end of straight portion 81 and arranged so as to revolve around cylinder 52. The spiral portion 84 is arranged above the liquid level of liquid hydrogen in liquid storage chamber 62. Curved portion 82 is connected to the lower end of spiral portion 84. Curved portion 82 has an opening 83 formed at its tip portion running along the bottom surface of bottom portion 51e. The opening 83 has an opening surface that is inclined with respect to the axial direction of drain pipe 71B.

[0063] It should be noted that the spiral portion 84 is not limited to the above-mentioned configuration. The spiral portion 84 may be disposed so as to make not only one revolution around the cylinder 52 but multiple revolutions. The spiral portion 84 may also be disposed so as to make a revolution around the position of the straight portion 81, without making a revolution around the cylinder 52.

[0064] Drain pipe 71B has a spiral portion 84 provided between straight portion 81 and curved portion 82, and spiral portion 84 is disposed above the liquid level of liquid hydrogen in liquid storage chamber 62. When boost pump 32B is in operation, drain pipe 71B has its flow path closed by drain valve 73 (see FIG. 2), but external heat is likely to be transferred through drain pipe 71B to liquid hydrogen in liquid storage chamber 62 of casing 51. However, since drain pipe 71B has straight portion 81 and spiral portion 84 disposed in a space filled with hydrogen gas, it is sufficiently cooled and external heat is less likely to be transferred to liquid hydrogen in liquid storage chamber 62, thereby suppressing the temperature rise of the liquid hydrogen.

[0065] FIG. 7 is a bottom cross-sectional view showing a booster pump of a second modified example, and FIG. 8 is a cross-sectional view taken along line VIII-VIII in FIG.

[0066] As shown in FIGS. 7 and 8, a boost pump 32C of the second modified example includes a casing 51, a cylinder 52, a piston 53, and a liquid hydrogen discharge device 54C.

[0067] The liquid hydrogen discharge device 54C has a drain pipe 71A, a pressurized pipe 72, and a guide member 91. The drain pipe 71A and the pressurized pipe 72 are similar to those in the second embodiment.

[0068] The guide member 91 includes a horizontal plate 92 and a plurality of guide plates 93. The horizontal plate 92 is disk-shaped, and its outer diameter is slightly smaller than the inner diameter of the cylindrical portion of the casing body 51a of the casing 51. The horizontal plate 92 is disposed slightly above the bottom surface of the bottom portion 51e of the casing body 51a, and its outer periphery contacts the inner periphery of the bottom portion 51e. The plurality of guide plates 93 are connected to the lower surface of the horizontal plate 92 at intervals in the circumferential direction. The plurality of guide plates 93 are disposed radially from the center (axis O4) of the casing body 51a along the radial direction of the casing body 51a. However, the plurality of guide plates 93 are not excluded from the center (axis O4) of the horizontal plate 92. The guide plate 93 is substantially triangular, and its lower surface is in close contact with the bottom surface of the bottom portion 51e.

[0069] The guide member 91 has a horizontal plate 92 having a plurality of notches 94. The notches 94 provided in the horizontal plate 92 allow the interior of the casing 51 to communicate with the upper and lower parts of the horizontal plate 92. The lower end of the drain pipe 71A passes through the horizontal plate 92.

[0070] When boost pump 32C is stopped, liquid hydrogen remaining in liquid storage chamber 62 of casing 51 flows along multiple guide plates 93 of guide member 91 and collects at the center of bottom portion 51e. Therefore, drain pipe 71A can take in the liquid hydrogen that has collected at the center of bottom portion 51e through opening 83 and discharge it all to the outside.

[0071] [Effects of this embodiment] The boost pump of the first embodiment comprises a casing 51 for storing liquid hydrogen (low-temperature fluid), a cylinder 52 arranged inside the casing 51, having a compression chamber 65 and having its vertical upper end supported on the top of the casing 51, a piston 53 supported inside the cylinder 52 so as to be freely movable along the vertical direction and compressing liquid hydrogen sucked into the compression chamber 65, and drain pipes 71, 71A, 71B, one end of which is supported on the top of the casing 51 and the other end of which extends to the bottom 51e of the casing 51.

[0072] According to the boost pump of the first aspect, when boost pumps 32, 32A, 32B, 32C are operating, external heat is transferred to drain pipes 71, 71A, 71B, but because drain pipes 71, 71A, 71B extend from the top of casing 51 to bottom 51e, a portion of the drain pipes is cooled by the hydrogen gas inside casing 51, making it difficult for external heat to be transferred to liquid hydrogen in liquid storage chamber 62, and thus making it possible to suppress a rise in temperature of the liquid hydrogen. As a result, leakage of fluid hydrogen stored inside casing 51 can be suppressed, and changes in the state of liquid hydrogen can be suppressed.

[0073] The boost pump according to the second embodiment is the boost pump according to the first embodiment, and further, the casing 51 has a casing body 51a which is a thermally insulating structure having a cylindrical shape with a bottom, and an intermediate flange portion (lid portion) 51b which closes the upper portion of the casing body 51a, and one end of the drain pipes 71, 71A, 71B is supported by penetrating the intermediate flange portion 51b. As a result, by making the casing body 51a a thermally insulating structure, the liquid hydrogen stored in the casing body 51a can be maintained at an appropriate temperature, and by supporting the upper end of the drain pipes 71, 71A, 71B on the intermediate flange portion 51b, there is no need to provide a support hole or the like in the casing body 51a which is a thermally insulating structure, and a decrease in the cooling function of the casing body 51a can be suppressed.

[0074] The boost pump according to the third aspect is the boost pump according to the first or second aspect, and further, drain pipes 71A, 71B are arranged so that the other end is curved and follows the bottom surface of casing 51. This allows liquid hydrogen at bottom 51e of casing 51 to be discharged to the outside without leaving any liquid hydrogen therein through drain pipes 71A, 71B.

[0075] The boost pump according to the fourth embodiment is the boost pump according to the third embodiment, and further includes drain pipes 71A, 71B each having a straight portion 81 disposed vertically inside casing 51, a curved portion 82 connected to a lower end of straight portion 81, and an opening 83 disposed at a tip of curved portion 82 and serving as an opening surface inclined with respect to the axial direction. This allows the lower ends of drain pipes 71A, 71B to be disposed appropriately along bottom portion 51e of casing 51.

[0076] The boost pump according to a fifth aspect is the boost pump according to any one of the first to fourth aspects, and further, the drain pipes 71, 71A, 71B are provided with a drain valve 73 for opening and closing the flow path outside the casing 51. As a result, by closing the drain valve 73 when the boost pumps 32, 32A, 32B, 32C are in operation, it is possible to suppress heat transfer from the outside to the inside of the casing 51 and also to suppress leakage of liquid hydrogen inside the casing 51 to the outside.

[0077] The boost pump according to the sixth aspect is the boost pump according to any one of the first to fifth aspects, and further includes pressurization piping 72 supported on an upper portion of casing 51 and capable of supplying gas from the outside of casing 51 to the inside thereof to pressurize it. As a result, by supplying gas to the inside of casing 51 through pressurization piping 72 and pressurizing it, liquid hydrogen or hydrogen gas inside casing 51 can be efficiently discharged from drain piping 71, 71A, 71B.

[0078] The boost pump according to the seventh aspect is the boost pump according to the sixth aspect, and further, pressurizing pipe 72 supplies gas obtained by heating the same type of liquid hydrogen as the liquid hydrogen stored in casing 51 to the inside of casing 51. This allows the liquid hydrogen to be used efficiently, and the hydrogen gas discharged to the outside of casing 51 can be collected and reused.

[0079] The boost pump according to an eighth aspect is the boost pump according to any one of the first to seventh aspects, and further, the bottom surface of the casing 51 has a curved shape that is convex downward in the vertical direction. This allows liquid hydrogen remaining in the casing 51 to be collected at the center position of the bottom part 51e, and allows the liquid hydrogen to be properly discharged by the drain pipes 71, 71A, 71B.

[0080] A hydrogen supply system (low-temperature fluid supply system) according to a ninth aspect includes a compressor 21 having boost pumps 32, 32A, 32B, 32C according to any one of the first to eighth aspects and compressing liquid hydrogen (low-temperature fluid), an evaporator 22 which vaporizes the liquid hydrogen compressed by the compressor 21, and a dispenser 23 which supplies hydrogen gas vaporized by the evaporator 22. This makes it possible to suppress leakage of liquid hydrogen stored inside the casing 51 by the boost pumps 32, 32A, 32B, 32C, and to suppress changes in the state of the liquid hydrogen.

[0081] The method of discharging a low-temperature fluid in the boost pump according to the tenth aspect includes the steps of discharging high-pressure liquid hydrogen pressurized in the compression chamber 65 to the outside by reciprocating the piston 53 inside the cylinder 52, stopping the reciprocating movement of the piston 53 when it becomes impossible to draw liquid hydrogen into the compression chamber 65, and discharging fluid hydrogen remaining in the casing 51 to the outside using a drain pipe 71 having one end supported on the top of the casing 51 and the other end extended to the bottom 51e of the casing 51. This makes it possible to properly discharge the fluid hydrogen remaining in the casing 51, suppress leakage of the fluid hydrogen stored inside the casing 51, and suppress changes in the state of the liquid hydrogen. [Explanation of symbols]

[0082] 10 Hydrogen supply system (low temperature fluid supply system) 11 Container 12 Vehicles 21 Compression device 22 Evaporation device 23 Dispenser 31 Drive unit 32, 32A, 32B, 32C Booster Pump 33 Drive motor 34 Drive mechanism 41 Eccentric shaft part 42 Rotating Body 43 Link section 44 Swing shaft 45 Crosshead 46 Housing 51 Casing 51a Casing body 51b Intermediate flange portion (lid portion) 52 cylinders 53 Piston 54, 54A, 54B, 54C Liquid hydrogen discharge device 61 Support plate 62 Liquid storage chamber 63 Supply pipe 64 Gas exhaust pipe 65 Compression Chamber 66 Intake valve 67 Discharge valve 68 Discharge piping 71, 71A, 71B Drain piping 72 Pressurized piping 73 Drain valve 74 Pressure source 75 Pressure valve 81 Straight section 82 Curved section 83 Opening 84 Spiral part 91 Guide member

Claims

1. a casing for storing a cryogenic fluid; a cylinder disposed inside the casing, having a compression chamber, and having a vertical upper end supported by an upper portion of the casing; a piston supported within the cylinder so as to be movable vertically and compresses the low-temperature fluid sucked into the compression chamber; a drain pipe having one end supported on the upper portion of the casing and the other end extending to the bottom portion of the casing; A boost pump comprising:

2. The casing has a casing body 51a which is a thermally insulating structure having a bottomed cylindrical shape, and a lid portion which closes an upper portion of the casing body 51a, and one end of the drain pipe is supported by penetrating the lid portion.

2. The boost pump of claim 1.

3. The drain pipe is arranged so that the other end is curved and follows the bottom surface of the casing. The boost pump according to claim 1 or 2.

4. The drain pipe has a straight portion disposed along a vertical direction inside the casing, a curved portion connected to a lower end of the straight portion, and an opening portion disposed at a tip end of the curved portion and having an opening surface inclined with respect to an axial direction.

4. The boost pump according to claim 3.

5. The drain piping is provided with a drain valve that opens and closes a flow path outside the casing.

2. The boost pump of claim 1.

6. a pressure piping supported on an upper portion of the casing and capable of supplying gas from the outside of the casing to the inside of the casing to pressurize the gas; 2. The boost pump of claim 1.

7. The pressurized piping supplies a gas obtained by heating a cryogenic fluid of the same type as the cryogenic fluid stored in the casing to the inside of the casing.

7. The boost pump according to claim 6.

8. The casing has a bottom surface that is curved and convex downward in the vertical direction.

2. The boost pump of claim 1.

9. A compression device having the boost pump according to claim 1 for compressing a cryogenic fluid; an evaporator that vaporizes the low-temperature fluid compressed by the compressor; a dispenser for supplying the gas vaporized by the vaporizer; A cryogenic fluid supply system comprising:

10. a casing for storing a cryogenic fluid; a cylinder disposed inside the casing, having a compression chamber, and having a vertical upper end supported by an upper portion of the casing; a piston supported within the cylinder so as to be movable vertically and compresses the low-temperature fluid sucked into the compression chamber; In a booster pump comprising: discharging the high-pressure cryogenic fluid pressurized in the compression chamber to the outside by reciprocating the piston inside the cylinder; stopping the reciprocating movement of the piston when it becomes impossible to draw low-temperature fluid into the compression chamber; discharging the cryogenic fluid remaining in the casing to the outside using a drain pipe having one end supported on the top of the casing and the other end extended to the bottom of the casing; A method for discharging a cryogenic fluid in a boost pump having the steps:

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