Pump device, pump system, and method for operating a pump system

Abstract

The present invention provides a pump device, a pump system, and an operating method of the pump system in which liquid hydrogen does not leak to the external environment and which is more suitable for high-speed rotation than a pump with a liquid-sealed rotating shaft. The pump device (2, 2A) of the present invention is connected to a storage tank (T1) that stores liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveys the liquid hydrogen. The pump device includes: a rotating shaft (31); a motor (M) that rotates the rotating shaft; an impeller (41) that is installed at the front end portion (31a) of the rotating shaft; a housing (30, 40) that has a motor chamber (36) for accommodating the motor and a pump chamber (43) for accommodating the impeller; and a mechanical seal (42) that is installed on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The motor includes: a rotor (34) that is installed on the rotating shaft; and a stator (35) that directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor. Hydrogen gas is introduced into the motor chamber.

Description

Technical Field

[0001] The present invention relates to a pump device, a pump system, and an operation method of the pump system. Background Art

[0002] In recent years, hydrogen energy has attracted much attention as a next-generation energy source. Hydrogen can theoretically be converted into electricity with high energy efficiency by being used as fuel for a fuel cell, and it does not emit harmful emissions, so it can be an efficient clean energy source. Hydrogen is stored, for example, as liquid hydrogen at a hydrogen refueling station for fuel cell vehicles.

[0003] When a centrifugal pump having a motor section and a pump section divided by a mechanical seal is used to transport liquid hydrogen, a small amount of liquid hydrogen leaks from the mechanical seal section. The leaked liquid hydrogen vaporizes into hydrogen gas and leaks into the external environment. Therefore, for example, it is necessary to perform a purge treatment of hydrogen gas using helium gas, but the operating cost of this treatment is high, and the system of this treatment is complex. Therefore, a method of using a leak-free canned motor pump for transporting liquid hydrogen has been proposed (for example, refer to Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents:

[0006] Patent Document 1: Japanese Patent Laid-Open No. 2020-162275 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] Since the specific gravity of liquid hydrogen is as small as about 0.07, in order to obtain the pressure required to transport the liquid, the rotor needs to rotate at a high speed. In this case, the magnetic flux through the metal can that liquid-seals the rotor changes at a high speed, and a phenomenon of eddy current flow (so-called can loss) occurs in the metal can. This phenomenon increases according to the rotation frequency of the motor section (rotor). In addition, since the rotor rotates in the liquid, the fluid friction loss caused by the liquid to the rotor increases according to the rotation frequency of the motor section (rotor). Therefore, a canned motor pump is sometimes not suitable as a centrifugal pump for transporting liquid hydrogen using high-speed rotation.

[0009] On the other hand, as a leak-free centrifugal pump, a pump is known in which a motor part (rotor and stator) is liquid-sealed together with the processing liquid. In this pump, the above-described phenomenon of eddy flow does not occur, but fluid friction loss caused by the liquid to the rotor occurs. In addition, when this pump and a canned motor pump are used, if the discharge flow rate becomes small, the temperature of the discharged liquid is likely to rise rapidly, and two-phase flow in the pump part is also likely to occur. In this pump and the canned motor pump, if two-phase flow occurs in the pump part, the lubrication of the bearing of the rotating shaft of the rotor becomes unstable, the fluid exciting force on the rotor becomes large, and the life of the bearing is shortened. Therefore, in this pump and the canned motor pump, the motor part must always be filled with the processing liquid. However, the boiling point of liquid hydrogen is extremely low, and in order to always fill the motor part with liquid hydrogen, special design and a certain degree of flow rate are required.

[0010] An object of the present invention is to provide a pump device, a pump system, and an operating method of a pump system in which liquid hydrogen does not leak to the external environment and is more suitable for high-speed rotation than a pump with a liquid-sealed rotor.

[0011] Means for Solving the Problem

[0012] A pump device according to an aspect of the present invention is connected to a storage tank that stores liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveys the liquid hydrogen. The pump device includes: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is axially mounted on one end of the rotating shaft; a housing that has a motor chamber for accommodating the motor and a pump chamber for accommodating the impeller; and a mechanical seal that is mounted on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The motor includes: a rotor that is mounted on the rotating shaft; and a stator that directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor. The hydrogen gas is introduced into the motor chamber.

[0013] A pump system according to an aspect of the present invention is connected to a storage tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveys the liquid hydrogen. The pump system includes: a pump device that sucks and discharges the liquid hydrogen; and a gas path connected to a gas phase portion of the storage tank storing the hydrogen gas. The pump device includes: a rotating shaft; an electric motor that rotates the rotating shaft; an impeller axially mounted at one end of the rotating shaft; a housing having a motor chamber that houses the electric motor and a pump chamber that houses the impeller; and a mechanical seal mounted on the rotating shaft and the housing to seal the motor chamber with respect to the pump chamber. The electric motor includes: a rotor mounted on the rotating shaft; and a stator directly opposed to the rotor in the radial direction of the rotating shaft and rotating the rotor. The housing has a gas inlet that opens into the motor chamber and is connected to the gas path, and the hydrogen gas is introduced into the motor chamber via the gas path and the gas inlet.

[0014] A method of operating a pump system according to an aspect of the present invention, the pump system being connected to a storage tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveying the liquid hydrogen. The pump system includes: a pump device that sucks and discharges the liquid hydrogen; and a gas path connected to a gas phase portion of the storage tank storing the hydrogen gas. The pump device includes: a rotating shaft; an electric motor that rotates the rotating shaft; an impeller axially mounted at one end of the rotating shaft; a housing having a motor chamber that houses the electric motor and a pump chamber that houses the impeller; and a mechanical seal mounted on the rotating shaft and the housing to seal the motor chamber with respect to the pump chamber. The electric motor includes: a rotor mounted on the rotating shaft; and a stator directly opposed to the rotor in the radial direction of the rotating shaft and rotating the rotor. The method of operating the pump system includes: a pre-preparation step of preparing until the pump device can perform liquid conveyance; and a step of discharging the liquid hydrogen from the pump chamber. The pre-preparation step includes: a step of introducing the liquid hydrogen into the pump chamber; and a step of introducing the hydrogen gas into the motor chamber via the gas path.

[0015] Advantages of the Invention

[0016] According to the present invention, it is possible to provide a pump device, a pump system, and a method of operating a pump system in which liquid hydrogen and hydrogen gas do not leak to the external environment and are more suitable for high-speed rotation than a pump with a liquid-sealed rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic pipeline diagram showing a first embodiment of the pump system of the present invention.

[0018] Figure 2It is a schematic cross-sectional view showing the first embodiment of the pump device of the present invention.

[0019] Figure 3 It is showing Figure 1 a schematic piping diagram of the first modification of the pump system.

[0020] Figure 4 It is showing Figure 1 a schematic piping diagram of the second modification of the pump system.

[0021] Figure 5 It is a schematic piping diagram showing the second embodiment of the pump system of the present invention.

[0022] Figure 6 It is a schematic cross-sectional view showing the second embodiment of the pump device of the present invention.

[0023] Figure 7 It is showing Figure 5 a schematic piping diagram of the first modification of the pump system.

[0024] Figure 8 It is showing Figure 5 a schematic piping diagram of the second modification of the pump system.

[0025] Figure 9 It is showing Figure 5 a schematic piping diagram of the third modification of the pump system.

[0026] Explanation of reference numerals

[0027] 1: Pump system (first embodiment)

[0028] 1A: Pump system (first modification of the first embodiment)

[0029] 1B: Pump system (second modification of the first embodiment)

[0030] 1C: Pump system (second embodiment)

[0031] 1D: Pump system (first modification of the second embodiment)

[0032] 1E: Pump system (second modification of the second embodiment)

[0033] 1F: Pump system (third modification of the second embodiment)

[0034] 2: Pump device (first embodiment)

[0035] 2A: Pump device (second embodiment)

[0036] 3: Motor section

[0037] 30: Housing

[0038] 30a: Gas inlet

[0039] 30b: Gas outlet

[0040] 30c: Partition wall

[0041] 30d: Vent hole

[0042] 30e: Outer wall

[0043] 30f: Guide flow path

[0044] 31: Rotating shaft

[0045] 31a: Front end (one end)

[0046] 31b: Rear end (the other end)

[0047] 34: Rotor

[0048] 35: Stator

[0049] 36: Motor chamber

[0050] 36a: First motor chamber

[0051] 36b: Second motor chamber

[0052] 4: Pump section

[0053] 40: Housing

[0054] 40a: Outer wall

[0055] 40b: Guide flow path

[0056] 41: Impeller

[0057] 42: Mechanical seal

[0058] 43: Pump chamber

[0059] HE: Heat exchanger

[0060] L1: Gas path

[0061] L11: Pipe section

[0062] L12: First pipe section (first gas path)

[0063] L13: Second pipe section (second gas path)

[0064] L14: Third pipe section (third gas path)

[0065] L2: Purge gas path

[0066] L3: Suction flow path

[0067] L4: Discharge flow path

[0068] T1: First storage tank (storage tank)

[0069] T1 G: Gas phase part

[0070] T2: Second storage tank (purge gas tank)

[0071] T3: Buffer tank (buffer tank, heat exchanger)

[0072] V1: First valve (on - off valve, switching part)

[0073] V3: Third valve (switching part) Detailed implementation mode

[0074] Hereinafter, while referring to the attached Figure 1 The embodiments of the pump device, pump system, and operation method of the pump system of the present invention will be described. In each figure, the same reference numerals are assigned to the same components and elements, and repeated descriptions are omitted. In addition, for ease of explanation, the dimensional ratios of the elements are sometimes exaggerated and are not limited to the ratios shown in each figure.

[0075] Pump system (1)

[0076] First, the embodiment of the pump system of the present invention (hereinafter referred to as "the first embodiment") will be described.

[0077] Structure of the pump system (1)

[0078] Figure 1 It is a schematic pipeline diagram showing the first embodiment of the pump system of the present invention.

[0079] The pump system 1 transports liquid hydrogen H2 (L). The pump system 1 includes a pump device 2, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12.

[0080] The pump device 2 is connected to the first storage tank T1 and transports the liquid hydrogen H2 (L) stored in the first storage tank T1. The structure of the pump device 2 will be described later.

[0081] The first storage tank T1 is a known high - pressure hydrogen tank that stores liquid hydrogen H2 (L). The first storage tank T1 is an example of the storage tank in the present invention. Inside the first storage tank T1, a liquid phase part T1 L and a gas phase part T1 G are formed. The liquid phase part T1 L stores liquid hydrogen H2 (L), and the gas phase part T1 G stores hydrogen gas H2 (G) vaporized from the liquid hydrogen H2 (L). The gas phase part T1 G is arranged above the liquid phase part T1 L.

[0082] The second storage tank T2 is a known high-pressure helium tank that stores helium He(G) in the pump system 1, and the helium He(G) serves as a purge gas for hydrogen H2(G). The second storage tank T2 is an example of the purge gas tank in the present invention.

[0083] The gas path L1 is connected to the gas phase part T1 G and the motor chamber 36 described later, and it is a path through which hydrogen H2(G) passes between them. The gas path L1 includes a pipe body part L11, a first valve V1, and a second valve V2.

[0084] The pipe body part L11 is a known pipe body connected to the gas phase part T1 G and the motor chamber 36 described later. The pipe body part L11 is made of stainless steel, for example, and has a known heat insulation structure (for example, a vacuum heat insulation structure formed by a double structure).

[0085] The first valve V1 and the second valve V2 are known valves (for example, gate valves) that are connected to the pipe body part L11 and open and close the pipe body part L11. The first valve V1 and the second valve V2 are made of stainless steel, for example, and have a known heat insulation structure (for example, a vacuum heat insulation structure formed by a double structure). In the gas path L1, the second valve V2 is arranged at a position more downstream (on the pump device 2 side) than the first valve V1. The first valve V1 is an example of the opening and closing valve in the present invention.

[0086] The purge gas path L2 is connected to the second storage tank T2 and the gas path L1, and it is a path through which helium He(G) passes between them. The purge gas path L2 includes a pipe body part L21 and a third valve V3. The connection point between the gas path L1 and the purge gas path L2 is arranged between the first valve V1 and the second valve V2 in the pipe body part L11.

[0087] The pipe body part L21 is a known pipe body connected to the second storage tank T2 and the gas path L1. The pipe body part L21 is made of metal, for example, in the same way as the pipe body part L11, and has the same heat insulation structure as the pipe body part L11.

[0088] The third valve V3 is a known valve (for example, a gate valve) that is connected to the purge gas path L2 and opens and closes the purge gas path L2. The third valve V3 is made of metal, for example, in the same way as the first valve V1, and has the same heat insulation structure as the first valve V1.

[0089] The suction flow path L3 is a known pipe body connected to the liquid phase part T1L and the suction port 44a described later. The suction flow path L3 is made of stainless steel, for example, and has a known heat insulation structure (for example, a vacuum heat insulation structure formed by a double structure).

[0090] The suction valve V11 is a known valve (e.g., a gate valve) that is connected to the suction flow path L3 and opens and closes the suction flow path L3. The suction valve V11 is made of stainless steel, for example, and has a known heat insulation structure (e.g., a vacuum heat insulation structure formed by a double structure).

[0091] The discharge flow path L4 is a known pipe body connected to a discharge port 45a described later. The discharge flow path L4 is made of metal, for example, in the same way as the suction flow path L3, and has the same heat insulation structure as the suction flow path L3.

[0092] The discharge valve V12 is a known valve (e.g., a gate valve) that is connected to the discharge flow path L4 and opens and closes the discharge flow path L4. The discharge valve V12 is made of stainless steel, for example, and has a known heat insulation structure (e.g., a vacuum heat insulation structure formed by a double structure).

[0093] Here, the pipe body parts L11 and L21 are mainly pipes through which gases (hydrogen H2(G), helium He(G)) described later pass in order to make the gas environment in the motor chamber 36 described later a corresponding gas environment. The pipe body parts L11 and L21 are composed of thinner pipes (thin pipes) according to the volume of the motor chamber 36. On the other hand, the suction flow path L3 and the discharge flow path L4 are composed of thicker pipes (thick pipes) according to the corresponding flow rate of the pump device 2.

[0094] In addition, the heat insulation structures of the respective pipe bodies, the first to third valves V1 to V3, the suction valve V11, and the discharge valve V12 are known heat insulation structures and are not limited to the structures described in this embodiment. That is, for example, it may also be configured to accommodate the pump device 2, the gas path L1, the purge gas path L2, the suction flow path L3, the suction valve V11, the discharge flow path L4, and the discharge valve V12 in a chamber and maintain the gas environment in the chamber as a vacuum environment.

[0095] Structure of the pump device (1)

[0096] Figure 2 is a schematic cross-sectional view showing an embodiment of the pump device of the present invention (hereinafter referred to as "the first embodiment"). In this figure, the flow of hydrogen H2(G) introduced into the pump device 2 is illustrated by white arrows, and the flow of liquid hydrogen H2(L) is illustrated by black arrows.

[0097] The pump device 2 includes a motor section 3, a pump section 4, a temperature sensor 5, and a pressure sensor 6. Except that the pump device 2 does not have a metal can for liquid-sealing a rotor 34 described later and the pump device 2 has a mechanical seal 42 described later, the main structure of the pump device 2 is almost the same as the main structure of a known canned motor pump. Therefore, in the following description, the structures of the motor section 3 and the pump section 4 will be described centering on the points different from the structures of known canned motor pumps, and the detailed description of other structures will be omitted.

[0098] In the following description, the "front direction" is the direction in which the pump unit 4 is located with respect to the motor unit 3, and the "rear direction" is the direction in which the motor unit 3 is located with respect to the pump unit 4.

[0099] The motor unit 3 is driven at a predetermined drive voltage / drive frequency to rotate an impeller 41 described later. The motor unit 3 includes a housing 30, a rotating shaft 31, bearings 32, 33, a rotor 34, a stator 35, and a motor chamber 36. The rotor 34 and the stator 35 constitute an example of the motor in the present invention, i.e., the motor M.

[0100] The housing 30 defines a motor chamber 36 that houses the rotating shaft 31, the bearings 32, 33, the rotor 34, and the stator 35. That is, the housing 30 has the motor chamber 36. The housing 30 is provided with a gas inlet 30a. The housing 30 is made of, for example, stainless steel.

[0101] The gas inlet 30a is a through-hole that penetrates the housing 30. The gas inlet 30a is disposed, for example, at the rear of the housing 30 and opens into the motor chamber 36. A gas path L1 (a pipe body portion L11) is connected to the gas inlet 30a.

[0102] The rotating shaft 31 rotates by the rotation of the rotor 34 and transmits the rotational power to the impeller 41 described later. The shape of the rotating shaft 31 is, for example, cylindrical. The rotating shaft 31 is inserted through the rotor 34 and fixed to the rotor 34. In the axial direction of the rotating shaft 31, the front end portion 31a of the rotating shaft 31 protrudes into a pump chamber 43 described later. In the axial direction of the rotating shaft 31, the front end portion 31a is an example of one end portion in the present invention, and the rear end portion 31b is an example of the other end portion in the present invention.

[0103] The bearings 32, 33 are mounted on the housing 30 and the rotating shaft 31, thereby rotatably supporting the rotating shaft 31. The bearing 32 is disposed in front of the rotor 34, and the bearing 33 is disposed behind the rotor 34. The bearings 32, 33 are, for example, known ball bearings.

[0104] The rotor 34 rotates by the rotating magnetic field generated by the stator 35. The shape of the rotor 34 is cylindrical. The rotor 34 is housed in the stator 35.

[0105] The stator 35 generates a rotating magnetic field that rotates the rotor 34. The stator 35 includes a cylindrical stator core 35a and a plurality of motor windings 35b. In the radial direction of the rotating shaft 31, the inner peripheral surface of the stator 35 directly faces the outer peripheral surface of the rotor 34. That is, no structure (shield) such as a metal can provided in a known canned motor is disposed between the rotor 34 and the stator 35.

[0106] The pump unit 4 sucks in and discharges liquid hydrogen H2(L). The pump unit 4 includes a housing 40, an impeller 41, a mechanical seal 42, a pump chamber 43, a suction pipe portion 44, and a discharge pipe portion 45.

[0107] The housing 40 defines a pump chamber 43 that houses the impeller 41 and the mechanical seal 42, and forms a suction pipe portion 44 and a discharge pipe portion 45. The suction pipe portion 44 is a flow path for the liquid hydrogen H2(L) sucked into the pump chamber 43, and the discharge pipe portion 45 is a flow path for the liquid hydrogen H2(L) discharged from the pump chamber 43. That is, the housing 40 has the pump chamber 43, the suction pipe portion 44, and the discharge pipe portion 45. The pump chamber 43 communicates with the suction pipe portion 44 and the discharge pipe portion 45. The suction pipe portion 44 has a suction port 44a connected to the suction flow path L3. The discharge pipe portion 45 has a discharge port 45a connected to the discharge flow path L4. The housing 40 is made of metal in the same way as the housing 30. The housing 40 is disposed in front of the housing 30 and is mounted on the housing 30. The housing 40 and the housing 30 together constitute the housing in the present invention.

[0108] The impeller 41 is mounted on the front end portion 31a of the rotating shaft 31 and is housed in the pump chamber 43.

[0109] The mechanical seal 42 is mounted on the rotating shaft 31 and the housing 40, thereby sealing the motor chamber 36 with respect to the pump chamber 43. In the axial direction of the rotating shaft 31, the mechanical seal 42 is disposed between the bearing 32 and the impeller 41. The mechanical seal 42 is, for example, a known mechanical seal, and includes a stationary ring (not shown) mounted on the housing 40 and a rotating ring (not shown) mounted on the rotating shaft 31.

[0110] The temperature sensor 5 is mounted on the motor unit 3 and detects the temperature inside the motor chamber 36. The temperature sensor 5 is, for example, a known temperature sensor that can detect extremely low temperatures (for example, the temperature of liquid hydrogen H2(L)).

[0111] The pressure sensor 6 is mounted on the motor unit 3 and detects the pressure inside the motor chamber 36. The pressure sensor 6 is, for example, a known pressure sensor.

[0112] Operation of the pump system (1)

[0113] Next, the operation of the pump system 1, that is, the operation method of the pump system 1 of the present invention, will be described. In the following description, appropriate reference will be made to Figure 1 and Figure 2 .

[0114] Before the pump system 1 starts operating (before the pump device 2 runs), close the first valve V1, the third valve V3, the suction valve V11, and the discharge valve V12. Additionally, on the downstream side of the first valve V1 in the gas path L1, in the motor chamber 36, on the downstream side of the suction valve V11 in the suction flow path L3 (on the pump device 2 side), in the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and on the upstream side of the discharge valve V12 in the discharge flow path L4 (on the pump device 2 side), it is maintained in a vacuum environment, for example, by a vacuum pump (not shown. The same applies hereinafter) connected to the discharge flow path L4.

[0115] It should be noted that in the present invention, before the pump system 1 starts operating, the downstream side of the first valve V1 in the gas path L1 and the motor chamber 36 may also be filled with helium gas having a melting point lower than that of hydrogen.

[0116] First, perform preparations until the pump device 2 can perform liquid transportation (preparation step). In the preparation step, first, disconnect the discharge flow path L4 from the vacuum pump. Next, open the suction valve V11, and the liquid hydrogen H2(L) in the liquid phase portion T1L of the first storage tank T1 is introduced into the suction flow path L3, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and the upstream side of the discharge valve V12 in the discharge flow path L4 (liquid hydrogen introduction step). As a result, the suction flow path L3, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and the upstream side of the discharge valve V12 in the discharge flow path L4 are filled with liquid hydrogen H2(L). As a result, the suction flow path L3, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and the upstream side of the discharge valve V12 in the discharge flow path L4 are cooled to the temperature of the liquid hydrogen H2(L) (flow path pre-cooling step).

[0117] Next, the first valve V1 and the second valve V2 are opened. At this time, the motor chamber 36 communicates with the gas phase part T1 G via the gas path L1 and the gas inlet 30a, and the hydrogen gas H2(G) stored in the gas phase part T1 G is introduced into the motor chamber 36 via the gas path L1 and the gas inlet 30a (hydrogen gas introduction step). As a result, the motor chamber 36 is filled with hydrogen gas H2(G), and this hydrogen gas H2(G) is cooled by the liquid hydrogen H2(L) in the pump chamber 43 via the rotating shaft 31 and the casings 30 and 40. Finally, the gas environment in the gas path L1 and the motor chamber 36 will be balanced with the gas environment in the gas phase part T1 G. That is, the gas path L1 and the inside of the motor chamber 36 are cooled to an extremely low temperature by the hydrogen gas H2(G) and become a stable hydrogen gas H2(G) environment. Here, as described above, before introducing the hydrogen gas H2(G), the downstream side of the first valve V1 in the gas path L1 and the inside of the motor chamber 36 are maintained in a vacuum environment (or a helium gas environment). Therefore, there are no other gas components (such as oxygen or nitrogen, etc.) in the gas path L1 and the motor chamber 36 that can be frozen by the extremely low temperature hydrogen gas H2(G) to be introduced, and technical problems (such as blockage of the pipe body part L11 of the thin pipe, freezing of the bearings 32 and 33, etc.) caused by the freezing of this gas component will not occur.

[0118] It should be noted that in the pre-preparation step, the hydrogen gas introduction step can be executed simultaneously with the liquid hydrogen introduction step, or can be executed prior to the liquid hydrogen introduction step. In the latter case, the hydrogen gas introduction step can also be executed before the gas environment in the motor chamber 36 is balanced.

[0119] Next, the discharge valve V12 is opened, the pump device 2 operates, and the impeller 41 rotates, whereby the liquid hydrogen H2(L) in the pump chamber 43 is discharged to the discharge flow path L4 via the discharge pipe part 45. As a result, the discharge flow path L4 (mainly the downstream side of the discharge valve V12) is cooled to the temperature of the liquid hydrogen H2(L) (transport flow path pre-cooling step). At this time, the liquid hydrogen H2(L) can be transported by the pump device 2 (each action in the pre-preparation step is completed). Then, the transportation of the liquid hydrogen H2(L) is started (liquid hydrogen transportation step). At this time, the first valve V1 is closed, and the motor chamber 36 is blocked from the gas phase part T1 G. As a result, the gas environment in the downstream side of the first valve V1 in the gas path L1 and the inside of the motor chamber 36 is maintained as a predetermined hydrogen gas H2(G) environment.

[0120] At this time, the bearings 32 and 33 are lubricated by the hydrogen gas H2(G). Here, the kinematic viscosity of the hydrogen gas H2(G) is several times larger than that of the liquid hydrogen H2(L). Therefore, compared with the case where the liquid hydrogen H2(L) is used to lubricate the bearings 32 and 33, the lubricity of the bearings 32 and 33 in the pump device 2 is more excellent.

[0121] As described above, since the first valve V1 is closed, a closed space (gas phase space) that is in a hydrogen H2(G) environment is formed on the downstream side of the first valve V1 in the gas path L1 and inside the motor chamber 36. Therefore, the hydrogen H2(G) inside the motor chamber 36 is cooled by the liquid hydrogen H2(L) flowing in the pump chamber 43 via the casings 30, 40 and the rotating shaft 31, and the hydrogen H2(G) environment inside the motor chamber 36 reaches a state of heat and pressure balance. Moreover, the heat locally generated inside the motor chamber 36 (e.g., the bearings 32, 33 or the motor M) is absorbed by the extremely low-temperature hydrogen H2(G) inside the motor chamber 36. Here, the structures of the gas path L1 and the motor chamber 36 (casing 30) that form the gas phase space are configured to allow for the heat and the pressure changes caused by the heat assumed during the normal operation of the pump device 2. Additionally, since the first valve V1 is closed, the heat absorbed by the hydrogen H2(G) inside the motor chamber 36 is not transferred to the gas phase portion T1G.

[0122] Moreover, as described above, the motor chamber 36 is filled with hydrogen H2(G) instead of the liquid hydrogen H2(L) which is the processing liquid. Therefore, no fluid friction loss occurs to the rotor 34 as in the case of the liquid-sealed rotor of an existing leak-free centrifugal pump (hereinafter referred to as "existing pump"). Additionally, since no metal tank is disposed between the rotor 34 and the stator 35, no loss caused by eddy currents occurs as in the case of an existing canned motor pump. That is to say, in the pump device 2, even if the rotation speed of the rotor 34 is increased, no fluid friction loss and no loss caused by eddy currents as in the existing pump occur. Therefore, the overall efficiency of the pump device 2 is higher than that of the existing pump, and the pump device 2 is more adaptable to high-speed rotation operation than the existing pump. Moreover, even if the pump device 2 operates at a low rotation speed, the gas environment inside the motor chamber 36 is a hydrogen H2(G) environment (single-phase flow), and no two-phase flow occurs inside the motor chamber 36. Therefore, the pump device 2 is more adaptable to low-speed rotation operation than the existing pump.

[0123] Moreover, as described above, the motor chamber 36 is sealed with respect to the pump chamber 43 by the mechanical seal 42. Therefore, as the rotating shaft 31 rotates, a small amount of liquid hydrogen H2(L) may leak into the motor chamber 36 via the mechanical seal 42. The liquid hydrogen H2(L) that leaks into the motor chamber 36 vaporizes to become hydrogen H2(G), but this hydrogen H2(G) diffuses into the hydrogen H2(G) filling the motor chamber 36 ( Figure 2 gray arrow), and does not leak to the external environment of the motor chamber 36, the gas path L1 and the gas phase portion T1G (when the first valve V1 is opened). That is to say, while using the mechanical seal 42, the pump system 1 also achieves leak-free of the liquid hydrogen H2(L) and the hydrogen H2(G) for the entire pump system 1.

[0124] In addition, as described above, the motor chamber 36 is filled with hydrogen gas H2(G), rather than liquid hydrogen H2(L) which is the processing liquid. Therefore, at the start of the operation of the pump system 1, unlike existing pumps, there is no need to fill the motor unit 3 with liquid hydrogen H2(L), and at the end of the operation of the pump system 1, there is no need to perform a process (vaporization process) of vaporizing the liquid hydrogen H2(L) filled in the motor unit 3 before discharging it. That is, in the pump system 1, liquid hydrogen H2(L) is only introduced into the pump chamber 43. Therefore, unnecessary consumption of liquid hydrogen H2(L) can be suppressed, the operating cost of the pump system 1 can be reduced, and energy can be saved.

[0125] In this way, in the pump system 1, hydrogen (liquid hydrogen H2(L) and hydrogen gas H2(G)) does not leak into the external environment, and liquid hydrogen H2(L) can be efficiently discharged. During the operation of the pump system 1, the state (temperature and pressure) inside the motor chamber 36 is detected by the temperature sensor 5 and the pressure sensor 6. Therefore, the state abnormality inside the motor chamber 36 can always be detected. Thus, even if the mechanical seal 42 fails and a large amount of liquid hydrogen H2(L) leaks into the motor chamber 36, the pump system 1 can detect the failure of the mechanical seal 42 by detecting the state abnormality inside the motor chamber 36.

[0126] Next, when stopping the operation of the pump system 1, first, the operation of the pump device 2 is stopped, and the suction valve V11 and the discharge valve V12 are closed. As a result, the introduction of liquid hydrogen H2(L) into the pump chamber 43 and the liquid transportation by the pump device 2 are stopped. Next, the third valve V3 is opened, and helium gas He(G) from the second storage tank T2 is introduced into the gas path L1 downstream of the first valve V1 and the motor chamber 36. As a result, the hydrogen gas H2(G) in the gas path L1 and the motor chamber 36 is purged by the helium gas He(G). The purged gas is discharged, for example, through a discharge path (not shown) connected to the gas path L1. Therefore, in the case of maintenance of the pump device 2, the hydrogen gas H2(G) as a flammable gas does not leak into the external environment, and the pump device 2 can be safely disassembled and decomposed. Next, the third valve V3 is closed, and a vacuum environment is maintained in the downstream of the first valve V1 in the gas path L1, the motor chamber 36, the downstream of the suction valve V11 in the suction flow path L3, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and the upstream of the discharge valve V12 in the discharge flow path L4 by a vacuum pump.

[0127] In this way, when the first valve V1 is closed and the third valve V3 is opened, a purge gas (helium gas He(G)) is introduced into the motor chamber 36, and when the first valve V1 is opened and the third valve V3 is closed, hydrogen gas H2(G) is introduced into the motor chamber 36. That is, the first valve V1 and the third valve V3 function as a switching unit that switches the gas introduced into the motor chamber 36 between the purge gas and hydrogen gas H2(G).

[0128] Summary (1)

[0129] According to the embodiment described above, the pump device 2 includes a rotating shaft 31, a motor M (rotor 34, stator 35), an impeller 41, housings 30, 40, and a mechanical seal 42. The motor M is accommodated in the motor chamber 36 and rotates the rotating shaft 31. The impeller 41 is attached to the front end portion 31a of the rotating shaft 31 and is accommodated in the pump chamber 43. The housing 30 defines the motor chamber 36, and the housing 40 defines the pump chamber 43. The mechanical seal 42 is attached to the rotating shaft 31 and the housing 40 and seals the motor chamber 36 with respect to the pump chamber 43. In the radial direction of the rotating shaft 31, the rotor 34 and the stator 35 face each other directly. Liquid hydrogen H2(L) from the liquid phase portion T1L is introduced into the pump chamber 43, and hydrogen gas H2(G) from the gas phase portion T1G is introduced into the motor chamber 36.

[0130] According to this structure, during the operation of the pump device 2, the motor chamber 36 is filled with hydrogen gas H2(G) introduced from the gas phase portion T1G. Therefore, the liquid hydrogen H2(L) leaking into the motor chamber 36 through the mechanical seal 42 vaporizes and diffuses into the hydrogen gas H2(G) in the motor chamber 36, and does not leak to the external environment of the motor chamber 36. That is, while using the mechanical seal 42, the pump device 2 also achieves leak-free of hydrogen (liquid hydrogen H2(L) and hydrogen gas H2(G)). In addition, the bearings 32, 33 are lubricated by hydrogen gas H2(G) having a higher kinematic viscosity than liquid hydrogen H2(L). Then, the heat locally generated in the motor chamber 36 is absorbed by the cryogenic hydrogen gas H2(G) in the motor chamber 36. Moreover, the hydrogen gas H2(G) in the motor chamber 36 is cooled by the liquid hydrogen H2(L) in the pump chamber 43, and the hydrogen gas H2(G) environment in the motor chamber 36 becomes a state of heat and pressure balance. In addition, in the pump device 2, losses caused by fluid friction loss or eddy current as in existing pumps do not occur. Therefore, compared with existing pumps, the overall efficiency of the pump device 2 is improved compared with existing pumps, and the pump device 2 can adapt to operations from low-speed rotation to high-speed rotation. In addition, different from existing pumps, when the pump device 2 starts operating, liquid hydrogen H2(L) is not introduced into the motor unit 3. Therefore, when the pump device 2 ends its operation, there is no need for a vaporization process before discharging the liquid hydrogen H2(L) filled in the motor unit 3. Therefore, unnecessary consumption of liquid hydrogen H2(L) can be suppressed, the operation cost of the pump device 2 can be reduced, and energy can be saved.

[0131] In addition, according to the embodiment described above, the pump system 1 has a gas path L1 and the above-mentioned pump device 2. The gas path L1 is connected to the gas phase portion T1G in which the hydrogen gas H2(G) is stored in the first tank T1. The frame 30 has a gas inlet port 30a connected to the gas path L1. The hydrogen gas H2(G) from the gas phase portion T1G is introduced into the motor chamber 36 via the gas path L1 and the gas inlet port 30a. According to this structure, during the operation of the pump system 1, the liquid hydrogen H2(L) leaked into the motor chamber 36 via the mechanical seal 42 is vaporized and diffused into the hydrogen gas H2(G) in the motor chamber 36. Since the motor chamber 36 is connected to the gas phase portion T1G via the gas path L1, the hydrogen gas H2(G) does not leak to the external environment of the pump system 1. That is, the pump system 1 achieves no leakage of hydrogen (liquid hydrogen H2(L) and hydrogen gas H2(G)) while using the pump device 2 having the mechanical seal 42. Furthermore, since the pump system 1 includes the above-described pump device 2 , there is no loss due to fluid friction or eddy current as in conventional pumps, and the pump system 1 can accommodate operations from low-speed rotation to high-speed rotation.

[0132] Moreover, according to the embodiment described above, the pump system 1 has a purge gas path L2 connected to the second tank T2 and the gas path L1, and the second tank T2 stores helium He (G) for purging the hydrogen H2 (G) introduced into the motor chamber 36. The purge gas path L2 includes a tube portion L21 and a third valve V3. The first valve V1 and the third valve V3 function as a switching unit that switches the gas introduced into the motor chamber 36 between the purge gas and the hydrogen H2 (G). According to this structure, by closing the first valve V1 and opening the third valve V3, the helium He (G) from the second tank T2 is introduced into the gas path L1 and the motor chamber 36 on the downstream side of the first valve V1. As a result, the hydrogen H2 (G) in the gas path L1 and the motor chamber 36 is purged by the helium He (G). Therefore, during maintenance of the pump device 2 or the like, hydrogen gas H2(G), which is a combustible gas, will not leak into the external environment, and the pump device 2 can be safely disassembled and disassembled.

[0133] In addition, according to the embodiment described above, the operation method of the pump system 1 includes a pre-preparation step and a liquid hydrogen delivery step. The pre-preparation step includes a liquid hydrogen introduction step, a flow path pre-cooling step, a hydrogen introduction step, and a delivery flow path pre-cooling step. According to this structure, before the pump device 2 starts to deliver liquid hydrogen H2 (L), the gas path L1 and the motor chamber 36 become an extremely low temperature hydrogen H2 (G) environment, and the flow path from the intake flow path L3 to the discharge flow path L4 is pre-cooled by liquid hydrogen H2 (L). Therefore, even if the pump device 2 starts liquid delivery, the hydrogen H2 (G) environment in the motor chamber 36 will not change drastically, and the pump device 2 can stably deliver liquid hydrogen H2 (L).

[0134] Modification Example (1)

[0135] Next, centering on the points different from the first embodiment described above, a modification example of the pump system 1 will be described as follows. In the description of the following modification examples, for ease of explanation, the same reference numerals as those in the first embodiment are assigned to the same components and components having the same functions as those in the first embodiment. In the following modification examples, appropriate references are made to Figure 1 and Figure 2 .

[0136] First Modification Example

[0137] Figure 3 is a schematic pipeline diagram showing a first modification example of the pump system of the first embodiment.

[0138] The pump system 1A includes a pump device 2, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12. The gas path L1 includes a pipe body portion L11, a first valve V1, a buffer tank T3, and a second valve V2.

[0139] The pipe body portion L11 includes a first pipe body portion L12 and a second pipe body portion L13. The first pipe body portion L12 is a known pipe body connected to the gas phase portion T1G and the buffer tank T3. The second pipe body portion L13 is a known pipe body connected to the buffer tank T3 and the gas introduction port 30a. The first pipe body portion L12 is an example of the first gas path in the present invention, and the second pipe body portion L13 is an example of the second gas path in the present invention.

[0140] The buffer tank T3 temporarily stores hydrogen H2(G) in the gas path L1. The design pressure (volume) of the buffer tank T3 is set to be large enough to absorb the pressure change based on the temperature change on the more downstream side of the gas path L1 than the buffer tank T3 and in the motor room 36. The buffer tank T3 is installed between the first valve V1 and the second valve V2 in the pipe body portion L11.

[0141] According to this structure, during the operation of the pump system 1A, even if the pressure in the motor chamber 36 changes due to local heat in the motor chamber 36, this change is suppressed by the hydrogen gas H2(G) stored in the buffer tank T3. As a result, during the operation of the pump system 1A, even if the first valve V1 is closed and the space downstream of the first valve V1 in the gas path L1 and inside the motor chamber 36 becomes a closed space, the pressure inside the motor chamber 36 remains stable. In addition, the volume of the gas path L1 in this modified example is larger than the volume of the gas path L1 in the first embodiment by an amount equivalent to the volume of the buffer tank T3. Therefore, even if the temperature of the hydrogen gas H2(G) in the motor chamber 36 rises due to local heat in the motor chamber 36, the temperature rise of the hydrogen gas H2(G) in the gas path L1 can be suppressed more effectively than in the first embodiment. Therefore, the changes in pressure and temperature inside the motor chamber 36 are more stable than in the first embodiment. Therefore, in the first modified example, even if the first valve V1 is opened, the temperature rise of the hydrogen gas H2(G) in the motor chamber 36 will not be transmitted to the gas phase part T1G.

[0142] Second modified example

[0143] Figure 4 It is a schematic pipeline diagram showing a second modified example of the pump system of the first embodiment.

[0144] The pump system 1B includes a pump device 2, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12. The gas path L1 includes a pipe body part L11, a first valve V1, a buffer tank T3, and a second valve V2.

[0145] In this modified example, a part of the discharge flow path L4 is installed in the buffer tank T3 in such a way that heat exchange occurs between the liquid hydrogen H2(L) in the discharge flow path L4 and the hydrogen gas H2(G) in the buffer tank T3. That is, for example, a part of the discharge flow path L4 is installed in the buffer tank T3 in a meandering manner. As a result, the buffer tank T3 and a part of the discharge flow path L4 function as a heat exchanger that uses the discharge liquid (liquid hydrogen H2(L)) of the pump device 2 as a refrigerant.

[0146] In this structure, since the buffer tank T3 and the heat exchanger are integrated, during the operation of the pump device 2, the hydrogen H2(G) in the buffer tank T3 is always cooled. Therefore, the effect of suppressing pressure changes by using the buffer tank T3 is further improved compared to the first modified example. In addition, since a closed space is formed together with the motor chamber 36, the hydrogen H2(G) in the buffer tank T3 with a relatively large volume is cooled, so the cooling efficiency of the hydrogen H2(G) in this space is good, and the rise in temperature and pressure in the gas path L1 and the motor chamber 36 can also be suppressed. Moreover, there is no need to separately connect the gas path L1 to the heat exchanger, the number of connection parts that may be the main cause of hydrogen H2(G) leakage is suppressed to the minimum, and space can be saved.

[0147] In addition, in this modified example, the buffer tank T3 may not function as a heat exchanger, and the pump system 1B is additionally provided with a heat exchanger that performs heat exchange between the hydrogen H2(G) in the gas path L1 and the liquid hydrogen H2(L) in the discharge flow path L4. In this structure, the hydrogen H2(G) in the gas path L1 is also always cooled, so the rise in temperature and pressure in the motor chamber 36 can be suppressed more effectively than in the first modified example.

[0148] Pump system (2)

[0149] Next, a description will be given of another embodiment of the pump system (hereinafter referred to as the "second embodiment") centered on the points different from the first embodiment, the first modified example, and the second modified example. In the following description of the second embodiment, for ease of explanation, the same reference numerals as those in the first embodiment, the first modified example, and the second modified example are assigned to the same components and components having the same functions. In addition, in the following description, appropriate references are made to Figure 1 and Figure 2 .

[0150] Structure of pump system (2)

[0151] Figure 5 is a schematic pipeline diagram showing the second embodiment of the pump system.

[0152] The pump system 1C transports liquid hydrogen H2(L). The pump system 1C includes a pump device 2A, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12.

[0153] The pump device 2A is connected to the first storage tank T1 and transports the liquid hydrogen H2(L) stored in the first storage tank T1. The structure of the pump device 2A will be described later.

[0154] The gas path L1 includes a pipe body portion L11, a first valve V1, a second valve V2, a fourth valve V4, and a buffer tank T3.

[0155] The pipe body portion L11 includes a first pipe body portion L12, a second pipe body portion L13, and a third pipe body portion L14. The third pipe body portion L14 is a known pipe body that is connected to the buffer tank T3 and a gas outlet 30b described later. The third pipe body portion L14 is an example of the third gas path in the present invention.

[0156] The fourth valve V4 is a known valve (e.g., a gate valve) that is connected to the third pipe body portion L14 and opens and closes the third pipe body portion L14. The fourth valve V4 is made of metal, for example, in the same manner as the first valve V1, and has the same heat insulation structure as the first valve V1.

[0157] Structure of the pump device (2)

[0158] Figure 6 It is a schematic cross-sectional view showing another embodiment (hereinafter referred to as "the second embodiment") of the pump device of the present invention (i.e., the pump device 2A).

[0159] The pump device 2A includes a motor section 3, a pump section 4, a temperature sensor 5, and a pressure sensor 6. Except that the motor section 3 includes a fan 37, a gas outlet 30b, and a partition wall 30c described later, the structure of the pump device 2A is the same as the structure of the pump device 2 in the first embodiment.

[0160] The motor section 3 includes a housing 30, a rotating shaft 31, two bearings 32, 33, a rotor 34, a stator 35, a motor chamber 36, and a fan 37.

[0161] The housing 30 includes a gas inlet 30a, a gas outlet 30b, and a partition wall 30c.

[0162] The gas inlet 30a is disposed, for example, at the rear of the housing 30 and opens into a second motor chamber 36b described later. The gas path L1 (the second pipe body portion L13) is connected to the gas inlet 30a. In the axial direction of the rotating shaft 31, the gas inlet 30a is disposed at a position rearward (on the side of the rear end portion 31b of the rotating shaft 31) of the motor M.

[0163] The gas outlet 30b is a through hole that penetrates the housing 30. The gas outlet 30b is disposed, for example, at the front of the housing 30 and opens into a first motor chamber 36a described later. The gas path L1 (the third pipe body portion L14) is connected to the gas outlet 30b. In the axial direction of the rotating shaft 31, the gas inlet 30a is disposed at a position forward (on the side of the front end portion 31a of the rotating shaft 31) of the motor M.

[0164] The partition wall 30c divides the motor chamber 36 into a first motor chamber 36a that houses the motor M and a second motor chamber 36b that houses the fan 37. The first motor chamber 36a is disposed in front of the second motor chamber 36b. The partition wall 30c has a plurality of ventilation holes 30d that penetrate the partition wall 30c in the front-rear direction, thereby connecting the first motor chamber 36a and the second motor chamber 36b.

[0165] The fan 37 causes the hydrogen gas H2(G) in the motor chamber 36 to flow, thereby circulating the hydrogen gas H2(G) between the gas path L1 and the motor chamber 36. The fan 37 is made of, for example, stainless steel. The fan 37 is installed at the rear end portion 31b of the rotating shaft 31 that protrudes into the second motor chamber 36b and is housed in the second motor chamber 36b. That is, the fan 37 is disposed within the motor chamber 36. The fan 37 is configured to rotate together with the rotating shaft 31 to cause the hydrogen gas H2(G) to flow forward.

[0166] Operation of the pump system (2)

[0167] Next, the operation of the pump system 1C, that is, another operation method of the pump system 1C of the present invention, will be described. In the following description, appropriate reference will be made to Figure 1 、 Figure 2 、 Figure 5 and Figure 6 .

[0168] Before the pump system 1C starts operating (before the pump device 2A operates), the first valve V1, the third valve V3, the suction valve V11, and the discharge valve V12 are closed. In addition, the downstream side of the first valve V1 in the gas path L1, the motor chamber 36, the downstream side of the suction valve V11 in the suction flow path L3, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45, and the upstream side of the discharge valve V12 in the discharge flow path L4 are maintained in a vacuum environment, for example, by the above-described vacuum pump.

[0169] First, similar to the first embodiment, the liquid hydrogen introduction step and the flow path pre-cooling step in the pre-preparation step are performed.

[0170] Next, the first valve V1, the second valve V2, and the fourth valve V4 are opened. At this time, the motor chamber 36 is connected to the gas phase portion T1 G via the gas path L1, and the hydrogen gas H2(G) stored in the gas phase portion T1 G is introduced into the motor chamber 36 via the gas path L1 (hydrogen gas introduction step). As a result, the inside of the motor chamber 36 is filled with the hydrogen gas H2(G), and finally, the gas environment in the gas path L1 and the motor chamber 36 will be in an equilibrium state with the gas environment in the gas phase portion T1 G. That is, the gas path L1 and the inside of the motor chamber 36 are cooled to an extremely low temperature by the hydrogen gas H2(G) and become a stable hydrogen gas H2(G) environment.

[0171] Next, the discharge valve V12 is opened, and the pump device 2A operates, causing the impeller 41 to rotate. As a result, the liquid hydrogen H2(L) in the pump chamber 43 is discharged through the discharge pipe portion 45 to the discharge flow path L4. As a result, the discharge flow path L4 (mainly the downstream side of the discharge valve V12) is cooled to the temperature of the liquid hydrogen H2(L) (pre-cooling step of the transfer flow path). At the same time, the fan 37 rotates as the rotary shaft 31 rotates. As a result, the hydrogen gas H2(G) in the second motor chamber 36b flows into the first motor chamber 36a. As a result, in the motor chamber 36, the hydrogen gas H2(G) introduced into the second motor chamber 36b from the gas inlet 30a flows from the rear to the front and flows out from the gas outlet 30b to the third pipe portion L14. Thus, the hydrogen gas H2(G) returns from the motor chamber 36 to the buffer tank T3 (start of circulation step). At this time, the liquid hydrogen H2(L) can be transported by the pump device 2A (completion of each operation in the pre-preparation step). Then, the transportation of the liquid hydrogen H2(L) is started (liquid hydrogen transportation step). At this time, the first valve V1 is closed, blocking the motor chamber 36 from the gas phase portion T1G. As a result, the gas environment on the downstream side of the first valve V1 in the gas path L1 and inside the motor chamber 36 is maintained as a predetermined hydrogen gas H2(G) environment.

[0172] At this time, since the first valve V1 is closed, the space on the downstream side of the first valve V1 in the gas path L1 and inside the motor chamber 36 becomes a closed space (gas phase space) with a hydrogen gas H2(G) environment. Then, a circulation path LR for the hydrogen gas H2(G) is formed by the buffer tank T3, the second pipe portion L13, the gas inlet 30a, the second motor chamber 36b, the ventilation hole 30d, the first motor chamber 36a, the gas outlet 30b, and the third pipe portion L14. As described above, the hydrogen gas H2(G) in the circulation path LR is circulated by the fan 37. In this structure, the hydrogen gas H2(G) in the motor chamber 36 is cooled by the liquid hydrogen H2(L) in the pump chamber 43 via the frames 30, 40, and the rotary shaft 31 and circulates in the circulation path LR. As a result, the hydrogen gas H2(G) environment in the circulation path LR becomes a state of heat and pressure balance. Therefore, the temperature inside the motor chamber 36 is maintained at a lower temperature than that in the motor chamber 36 in the first embodiment. In addition, since the wind from the fan 37 blows directly onto the motor M, the motor M is cooled more than in the first embodiment.

[0173] In addition, in the second embodiment, the pump system 1C has the same structure as the pump systems 1 and 1A in the first embodiment and the first modification of the first embodiment. Therefore, the effects obtained in the pump systems 1 and 1A can also be obtained in the pump system 1C.

[0174] Summary (2)

[0175] According to the embodiment described above, the pump system 1C has the same structure as the pump system 1 in the first embodiment, and a fan 37 that circulates hydrogen H2(G) between the motor chamber 36 and the buffer tank T3. The housing 30 has a gas outlet 30b that discharges the hydrogen H2(G) introduced into the motor chamber 36 to the gas path L1. The gas path L1 has a third pipe body portion L14 connected to the gas outlet 30b and the buffer tank T3. According to this structure, by the operation of the fan 37, the hydrogen H2(G) introduced into the motor chamber 36 from the gas inlet 30a is discharged from the gas outlet 30b to the third pipe body portion L14, returns to the buffer tank T3, and is introduced into the motor chamber 36 again via the second pipe body portion L13 and the gas inlet 30a. As a result, the hydrogen H2(G) in the motor chamber 36 is cooled by the liquid hydrogen H2(L) in the pump chamber 43, does not stay in the motor chamber 36, and circulates between the motor chamber 36 and the buffer tank T3. Therefore, the hydrogen H2(G) environment in the motor chamber 36 and the buffer tank T3 can achieve a better balance of heat and pressure than in the first embodiment, and the temperature in the motor chamber 36 is maintained at a lower temperature than in the first embodiment.

[0176] In addition, according to the embodiment described above, the fan 37 is mounted on the rotating shaft 31 to cause the hydrogen H2(G) introduced from the gas inlet 30a to flow toward the gas outlet 30b. According to this structure, no special mechanism for accommodating and rotating the fan 37 is required, and the hydrogen H2(G) in the motor chamber 36 can flow easily.

[0177] Moreover, according to the embodiment described above, in the axial direction of the rotating shaft 31, the fan 37 is mounted on the rear end portion 31b of the rotating shaft 31. The housing 30 has a partition wall 30c that divides the first motor chamber 36a accommodating the motor M and the second motor chamber 36b accommodating the fan 37. The partition wall 30c has a ventilation hole 30d that communicates the first motor chamber 36a and the second motor chamber 36b. The gas inlet 30a opens in the second motor chamber 36b. The gas outlet 30b opens in the first motor chamber 36a and is disposed at a position closer to the front end portion 31a side than the motor M in the axial direction of the rotating shaft 31. According to this structure, a circulation path LR for circulating hydrogen H2(G) is formed by the buffer tank T3, the second pipe body portion L13, the gas inlet 30a, the second motor chamber 36b, the ventilation hole 30d, the first motor chamber 36a, the gas outlet 30b, and the third pipe body portion L14. The hydrogen H2(G) in the motor chamber 36 is cooled by the liquid hydrogen H2(L) in the pump chamber 43 and circulates in the circulation path LR. As a result, the gas environment in the circulation path LR becomes a state of heat and pressure balance. Therefore, the temperature in the motor chamber 36 is maintained at a lower temperature than in the first embodiment. In addition, since the wind from the fan 37 directly blows on the motor M, the motor M is cooled more than in the first embodiment.

[0178] In addition, according to the embodiment described above, the operation method of the pump system 1C includes a preliminary preparation step and a liquid hydrogen delivery step. The preliminary preparation step includes a liquid hydrogen introduction step, a flow path pre-cooling step, a hydrogen gas introduction step, a delivery flow path pre-cooling step, and a circulation start step. According to this structure, before the pump device 2A starts delivering liquid hydrogen H2(L), the gas path L1 and the motor chamber 36 are in an extremely low-temperature hydrogen gas H2(G) environment, and the flow path from the suction flow path L3 to the discharge flow path L4 is pre-cooled by the liquid hydrogen H2(L). In addition, the temperature in the motor chamber 36 is maintained at a lower temperature than the temperature in the motor chamber 36 in the first embodiment. Therefore, even when the pump device 2A starts liquid delivery, the hydrogen gas H2(G) environment in the motor chamber 36 does not change suddenly, and the pump device 2A can stably deliver the liquid hydrogen H2(L).

[0179] It should be noted that in the second embodiment, the arrangement of the fan 37 is not limited to the rear end portion 31b side of the rotating shaft 31. That is, for example, the fan 37 can also be arranged on the front end portion 31a side in the motor chamber 36 (for example, between the motor M and the bearing 32 in the axial direction of the rotating shaft 31). In addition, for example, the fan 37 can also be installed not on the rotating shaft 31 but on a fan rotating shaft dedicated to the fan 37 (not shown). Moreover, for example, the fan 37 can also be provided in the gas path L1 and connected to the second pipe body portion L13 or the third pipe body portion L14.

[0180] In addition, in the second embodiment, the housing 30 may not have the partition wall 30c.

[0181] Moreover, in the second embodiment, the positions of the gas inlet 30a and the gas outlet 30b only need to be positions where the hydrogen gas H2(G) can circulate between the motor chamber 36 and the buffer tank T3, and are not limited to the positions described in the second embodiment.

[0182] In addition, in the second embodiment, the pump system 1C may not have the buffer tank T3.

[0183] Modification (2)

[0184] Next, centering on the points different from the second embodiment described above, the modification of the pump system 1C will be described as follows. In the following description of the modification, for the sake of convenience, the same reference numerals as those in the second embodiment are given to the components that are the same as those in the second embodiment and have the same functions. In addition, in the following modification, appropriate reference is made to Figure 1 , Figure 2 , Figure 5 and Figure 6 .

[0185] First Modification

[0186] Figure 7 It is a schematic piping diagram showing a first modification of the pump system according to the second embodiment.

[0187] The pump system 1D includes a pump device 2A, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12.

[0188] In this modification, a part of the discharge flow path L4 is installed in the buffer tank T3 in such a way as to effect heat exchange between the liquid hydrogen H2(L) in the discharge flow path L4 and the hydrogen gas H2(G) in the buffer tank T3. As a result, the buffer tank T3 and a part of the discharge flow path L4 function as a heat exchanger that uses the discharged liquid (liquid hydrogen H2(L)) of the pump device 2A as a refrigerant.

[0189] In this structure, during the operation of the pump device 2A, the hydrogen gas H2(G) in the buffer tank T3 is always cooled. Therefore, the effect of suppressing pressure changes by using the buffer tank T3 is further enhanced compared to the second embodiment. In addition, since the hydrogen gas H2(G) in the buffer tank T3 that forms a closed circulation path LR together with the motor chamber 36 is cooled, the rise in temperature and pressure in the motor chamber 36 can also be more effectively suppressed.

[0190] Second modification

[0191] Figure 8 It is a schematic piping diagram showing a second modification of the pump system according to the second embodiment.

[0192] The pump system 1E includes a pump device 2A, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, a discharge valve V12, and a heat exchanger HE.

[0193] The heat exchanger HE is installed in the third pipe section L14 and the discharge flow path L4 to effect heat exchange between the hydrogen gas H2(G) in the third pipe section L14 and the liquid hydrogen H2(L) in the discharge flow path L4. That is, the heat exchanger HE uses the discharged liquid (liquid hydrogen H2(L)) of the pump device 2A as a refrigerant to cool the hydrogen gas H2(G) in the third pipe section L14.

[0194] In this structure, during the operation of the pump device 2A, the hydrogen gas H2(G) in the third pipe body portion L14 where the heat exchanger HE is installed is always cooled and sent to the buffer tank T3. That is, the hydrogen gas H2(G) returning from the motor chamber 36 to the buffer tank T3 is always cooled. Therefore, an effect equivalent to that of suppressing pressure changes by using the buffer tank T3 in the first modification of the second embodiment can be obtained. In addition, since the hydrogen gas H2(G) in the third pipe body portion L14 that forms a closed circulation path LR together with the motor chamber 36 is cooled, the rise in temperature and pressure in the motor chamber 36 can also be suppressed as in the first modification of the second embodiment.

[0195] It should be noted that in this modification, the heat exchanger HE may also be installed in the second pipe body portion L13.

[0196] Third Modification

[0197] Figure 9 It is a schematic pipeline diagram showing the third modification of the pump system of the second embodiment.

[0198] The pump system 1F includes a pump device 2A, a first storage tank T1, a second storage tank T2, a gas path L1, a purge gas path L2, a suction flow path L3, a suction valve V11, a discharge flow path L4, and a discharge valve V12.

[0199] The housing 30 includes a gas inlet 30a, a gas outlet 30b, a partition wall 30c, an outer wall 30e, and a guiding flow path 30f.

[0200] The outer wall 30e is the outer shell portion of the housing 30 that defines the motor chamber 36. A part of the outer wall 30e is a hollow double structure and forms the guiding flow path 30f. That is, the guiding flow path 30f is arranged inside the outer wall 30e. In addition, a part of the outer wall 30e protrudes outward to form a discharge pipe portion 30g. That is, in the third modification, the discharge pipe portion 30g and the discharge port 30h are arranged on the motor unit 3 side. The discharge pipe portion 30g communicates with the guiding flow path 30f.

[0201] Similar to the first embodiment, the suction pipe portion 44 and the suction port 44a are arranged on the pump portion 4 side. The housing 40 includes an outer wall 40a and a guiding flow path 40b.

[0202] The outer wall 40a is the outer shell portion of the housing 40 that defines the pump chamber 43. A part of the outer wall 40a is a hollow double structure and forms the guiding flow path 40b. That is, the guiding flow path 40b is arranged inside the outer wall 40a. The guiding flow path 40b communicates with the pump chamber 43 and the guiding flow path 30f. Therefore, the liquid hydrogen H2(L) in the pump chamber 43 is transported to the discharge flow path L4 through the guiding flow path 40b, the guiding flow path 30f, the discharge pipe portion 30g, and the discharge port 30h.

[0203] A part of the upstream side (gas outlet 30b side) of the third pipe body portion L14 is installed in the frames 30 and 40 in such a manner that heat exchange can occur between the hydrogen H2(G) in the third pipe body portion L14 and the liquid hydrogen H2(L) in the guide and drainage paths 30f and 40b. That is, for example, a part of the third pipe body portion L14 is arranged in a meandering manner within the guide and drainage paths 30f and 40b. As a result, a part of the frames 30 and 40 and the third pipe body portion L14 (gas path L1) functions as a heat exchanger, and the liquid hydrogen H2(L) before being discharged by the pump device 2A is used as the refrigerant. A part of the third pipe body portion L14 (gas path L1) is an example of the heat exchange path in the present invention.

[0204] In this structure, during the operation of the pump device 2A, similar to the second modification of the second embodiment, the hydrogen H2(G) in the third pipe body portion L14 is always cooled and sent to the buffer tank T3. That is, the hydrogen H2(G) returning from the motor chamber 36 to the buffer tank T3 is always cooled. Therefore, an effect equivalent to that of suppressing pressure changes by using the buffer tank T3 in the first modification of the second embodiment can be obtained. In addition, since the hydrogen H2(G) in the third pipe body portion L14 that forms a closed circulation path LR together with the motor chamber 36 is cooled, the rise in temperature and pressure in the motor chamber 36 can also be suppressed, similar to the first modification of the second embodiment. Moreover, since the pump device 2A also functions as a heat exchanger, additional connections and pipelines for the heat exchanger are not required.

[0205] Furthermore, in this modification, as long as a part of the upstream side (gas outlet 30b side) of the third pipe body portion L14 is installed in the frames 30 and 40 in such a manner that heat exchange can occur between the hydrogen H2(G) in the third pipe body portion L14 and the liquid hydrogen H2(L) in the guide and drainage paths 30f and 40b, it is not necessary to arrange it within the guide and drainage paths 30f and 40b. That is, for example, a part of the upstream side (gas outlet 30b side) of the third pipe body portion L14 can also be installed on the outer surfaces of the outer walls 30e and 40a that form the guide and drainage paths 30f and 40b.

[0206] In addition, in this modification, the gas path L1 can also be configured to perform heat exchange between the hydrogen H2(G) and the liquid hydrogen H2(L) at other positions that are not the guide and drainage paths 30f and 40b. That is, for example, in this modification, similar to the first or second modification of the second embodiment, heat exchange between the hydrogen H2(G) and the liquid hydrogen H2(L) can also be performed in the buffer tank T3 or the heat exchanger HE. In this case, the guide and drainage paths 30f and 40b are used to cool the frame 30 (the hydrogen H2(G) in the motor chamber 36).

[0207] Other Embodiments

[0208] It should be noted that in the first embodiment and the second embodiment, the pump systems 1 and 1C only need to include the pump devices 2 and 2A and the gas path L1, and the structures of the pump systems 1 and 1C are not limited to the structures described in the first embodiment and the second embodiment. That is, for example, the pump system of the present invention may not include the first storage tank T1, the second storage tank T2, the purge gas path L2, the suction flow path L3, and / or the discharge flow path L4, and may be connected to a device having these components.

[0209] In addition, in the first embodiment and the second embodiment, the pump systems 1 and 1C may also include, for example, a vacuum pump and a discharge path connected to the gas path L1.

[0210] Moreover, in each modification, the buffer tank T3 and the heat exchanger HE that function as heat exchangers only need to be configured to be able to perform heat exchange between the hydrogen H2(G) in the gas path L1 and the liquid hydrogen H2(L) in the discharge flow path L4, and their structures are not limited to those in each modification.

[0211] In addition, in the first embodiment and the second embodiment, the pump devices 2 and 2A may also include an inducer disposed on the suction port 44a side of the impeller 41.

[0212] In addition, in the first embodiment and the second embodiment, during the operation of the pump device 2, the first valve V1 may be opened according to the state (temperature and pressure) in the motor chamber 36, or may also be opened and closed. That is, for example, the first valve V1 is opened when the temperature (pressure) in the motor chamber 36 rises, and the first valve V1 is closed when the temperature (pressure) decreases (balances).

[0213] In addition, in the first embodiment and the second embodiment, the motor M may also be a permanent magnet motor in which the rotor 34 has a permanent magnet. In this case, the pump devices 2 and 2A include a protection member (for example, a stainless steel protection member) that covers the rotor 34 and isolates the rotor 34 from the hydrogen H2(G). According to this structure, embrittlement of the permanent magnet caused by hydrogen H2(G) can be prevented.

[0214] In addition, in the first embodiment, the second embodiment, and each modification, the structures of each pipe body and each valve only need to be structures that can introduce the hydrogen H2(G) from the gas phase part T1 G into the motor chamber 36 and can introduce the liquid hydrogen H2(L) from the liquid phase part T1 L into the pump chamber 43, and are not limited to the structures described in the first embodiment, the second embodiment, and each modification.

[0215] In addition, the structures of the first embodiment, the second embodiment, and each modification may also be combined with each other.

[0216] Embodiments of the present invention

[0217] Next, referring to the terms and reference numerals described in each embodiment, the embodiments of the present invention understood from the above-described embodiments are described as follows.

[0218] The first embodiment of the present invention is a pump device (for example, pump devices 2, 2A), which is connected to a storage tank (for example, the first storage tank T1) that stores liquid hydrogen (for example, liquid hydrogen H2(L)) and hydrogen gas (for example, hydrogen gas H2(G)) vaporized from the liquid hydrogen, and conveys the liquid hydrogen. The pump device includes: a rotating shaft (for example, rotating shaft 31); a motor (for example, motor M) that rotates the rotating shaft; an impeller (for example, impeller 41) that is mounted on one end (for example, front end 31a) of the rotating shaft in the axial direction of the rotating shaft; a housing (for example, housings 30, 40) that has a motor chamber (for example, motor chamber 36) for accommodating the motor and a pump chamber (for example, pump chamber 43) for accommodating the impeller; and a mechanical seal (for example, mechanical seal 42) that is mounted on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The motor includes: a rotor (for example, rotor 34) that is mounted on the rotating shaft; and a stator (for example, stator 35) that directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor. The hydrogen gas is introduced into the motor chamber.

[0219] According to this structure, the pump device achieves leak-free hydrogen (liquid hydrogen and hydrogen gas) while using a mechanical seal, and can adapt to operations from low-speed rotation to high-speed rotation.

[0220] The second embodiment of the present invention is the pump device according to the first embodiment, wherein the housing includes a gas inlet (for example, gas inlet 30a) connected to a gas path (for example, gas path L1), and the gas path (for example, gas path L1) is connected to a gas phase portion (for example, gas phase portion T1G) that stores the hydrogen gas in the storage tank. The hydrogen gas is introduced into the motor chamber through the gas inlet.

[0221] According to this structure, since the motor chamber is connected to the gas phase portion through the gas path, the hydrogen gas does not leak into the external environment of the pump system.

[0222] A third embodiment of the present invention is based on the pump device described in the second embodiment (for example, the pump device 2A), wherein the housing includes: an outer wall (for example, the outer walls 30e, 40a) that divides between the pump chamber and the motor chamber and the external environment of the housing; a suction port (for example, the suction port 44a) that is disposed on the pump chamber side of the housing and sucks the liquid hydrogen from the storage tank into the pump chamber; a discharge port (for example, the discharge port 45a) that is disposed on the motor chamber side of the housing and discharges the liquid hydrogen from the pump chamber; and a guiding flow path (for example, the guiding flow paths 30f, 40b) that is disposed within the outer wall and guides the liquid hydrogen from the pump chamber to the discharge port.

[0223] According to this structure, the liquid hydrogen guided within the guiding flow path cools the housing (the hydrogen gas within the motor chamber).

[0224] A fourth embodiment of the present invention is based on the pump device described in the third embodiment, wherein the pump device has a heat exchange path that forms a part of the gas path, and the heat exchange path is configured such that heat exchange can occur between the hydrogen gas within the heat exchange path and the liquid hydrogen within the guiding flow path.

[0225] According to this structure, during the operation of the pump device, the hydrogen gas within the third pipe body portion is constantly cooled and sent to the buffer tank. Therefore, the effect of suppressing pressure changes by the buffer tank is enhanced.

[0226] A fifth embodiment of the present invention is based on the pump device described in any one of the second to fourth embodiments, wherein the pump device has a fan (for example, the fan 37) disposed within the motor chamber, the housing includes a gas outlet (for example, the gas outlet 30b) that guides the hydrogen gas introduced into the motor chamber to the gas path, and the fan causes the hydrogen gas introduced into the motor chamber from the gas inlet to flow toward the gas outlet.

[0227] According to this structure, the hydrogen gas within the motor chamber is cooled by the liquid hydrogen within the pump chamber and circulates without remaining within the motor chamber. As a result, the hydrogen gas environment within the motor chamber and the buffer tank achieves a balance of heat and pressure, and the temperature within the motor chamber is maintained at a low temperature.

[0228] A sixth embodiment of the present invention is based on the pump device described in the first embodiment, wherein the motor is a permanent magnet motor in which the rotor (for example, the rotor 34) includes permanent magnets, and the pump device includes a protective member that covers the rotor and isolates the rotor from the hydrogen gas.

[0229] According to this structure, embrittlement of the permanent magnets caused by hydrogen gas can be prevented.

[0230] The seventh embodiment of the present invention is a pump system (e.g., pump systems 1, 1A, 1B, 1C, 1D, 1E, 1F), which is connected to a storage tank (e.g., the first storage tank T1) that stores liquid hydrogen (e.g., liquid hydrogen H2(L)) and hydrogen gas (e.g., hydrogen gas H2(G)) vaporized from the liquid hydrogen, and transports the liquid hydrogen. The pump system includes: a pump device (e.g., pump devices 2, 2A) that sucks and discharges the liquid hydrogen; and a gas path (e.g., gas path L1) that is connected to a gas phase portion (e.g., gas phase portion T1G) of the storage tank that stores the hydrogen gas. The pump device includes: a rotating shaft (e.g., rotating shaft 31); an electric motor (e.g., electric motor M) that rotates the rotating shaft; an impeller (e.g., impeller 41) that is axially mounted on one end portion (e.g., front end portion 31a) of the rotating shaft; a housing (e.g., housings 30, 40) that has a motor chamber (e.g., motor chamber 36) for accommodating the electric motor and a pump chamber (e.g., pump chamber 43) for accommodating the impeller; and a mechanical seal (e.g., mechanical seal 42) that is mounted on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The electric motor includes: a rotor (e.g., rotor 34) that is mounted on the rotating shaft; and a stator (e.g., stator 35) that directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor. The housing has a gas inlet (e.g., gas inlet 30a) that is connected to the gas path, and the hydrogen gas is introduced into the motor chamber via the gas path and the gas inlet.

[0231] According to this structure, the pump system uses a pump device with a mechanical seal, achieves leak-free hydrogen, and can adapt to the transportation of liquid hydrogen from low-speed rotation to high-speed rotation.

[0232] The eighth embodiment of the present invention is the pump system (e.g., pump systems 1A, 1B, 1C, 1D, 1E, 1F) according to the seventh embodiment, wherein the gas path includes: a buffer tank (e.g., buffer tank T3) that temporarily stores the hydrogen gas; a first gas path (e.g., first pipe portion L12) that is connected to the buffer tank and the gas phase portion; a second gas path (e.g., second pipe portion L13) that is connected to the buffer tank and the gas inlet; and an on-off valve (e.g., first valve V1) that is connected to the first gas path and opens and closes the first gas path.

[0233] According to this structure, during the operation of the pump system, even if the pressure in the motor chamber changes due to local heat from the bearing or the stator, the change is suppressed by the hydrogen gas stored in the buffer tank. In addition, even if the temperature of the hydrogen gas in the motor chamber rises due to local heat, the rise in the temperature of the hydrogen gas in the gas path and the motor chamber can be suppressed.

[0234] The ninth embodiment of the present invention is based on the pump system described in the eighth embodiment (for example, pump systems 1B, 1D, 1E, 1F), wherein the pump system has: a discharge flow path (for example, discharge flow path L4) that is connected to a discharge port (for example, discharge port 45a) provided on the housing and discharging the liquid hydrogen from the pump chamber; and a heat exchanger (for example, buffer tank T3, heat exchanger HE) that exchanges heat between the hydrogen gas in the gas path and the liquid hydrogen in the discharge flow path.

[0235] According to this structure, even if the temperature of the hydrogen gas in the motor chamber rises due to local heat, the rise in the temperature of the hydrogen gas in the gas path and the motor chamber can be suppressed.

[0236] The tenth embodiment of the present invention is based on the pump system described in the ninth embodiment (for example, pump systems 1B, 1D), wherein the discharge flow path is arranged in such a way that heat exchange can be carried out between the liquid hydrogen flowing in the discharge flow path and the hydrogen gas in the buffer tank, and the buffer tank functions as the heat exchanger.

[0237] According to this structure, during the operation of the pump device, the hydrogen gas in the buffer tank is always cooled. As a result, the rise in the temperature and pressure in the gas path and the motor chamber can be further suppressed.

[0238] The eleventh embodiment of the present invention is based on the pump system described in the seventh embodiment (for example, pump system 1F), wherein the housing includes: an outer wall (for example, outer walls 30e, 40a) that divides the pump chamber and the motor chamber respectively; a suction port (for example, suction port 44a) that is arranged on the pump chamber side of the housing and sucks the liquid hydrogen from the storage tank into the pump chamber; a discharge port (for example, discharge port 30h) that is arranged on the motor chamber side of the housing and discharges the liquid hydrogen from the pump chamber; and a guiding flow path (for example, guiding flow paths 30f, 40b) that is arranged inside the outer wall and guides the liquid hydrogen from the pump chamber to the discharge port.

[0239] According to this structure, the housing (hydrogen gas in the motor chamber) is cooled by the liquid hydrogen guided in the guiding flow path.

[0240] The twelfth embodiment of the present invention is based on the pump system described in the eleventh embodiment, wherein the gas path includes a heat exchange path (for example, the third pipe body portion L14) installed in the pump device, and the heat exchange path is arranged in such a way that heat exchange can be carried out between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guiding flow path.

[0241] According to this structure, during the operation of the pump device, the hydrogen gas in the third pipe body portion is always cooled and sent to the buffer tank. Therefore, the effect of suppressing pressure changes by using the buffer tank is enhanced.

[0242] A 13th embodiment of the present invention is the pump system according to any one of the 7th to 12th embodiments, wherein the pump system has a fan (for example, fan 37) that circulates the hydrogen gas between the motor chamber and the gas path, the housing includes a gas outlet (for example, gas outlet 30b) that leads the hydrogen gas introduced into the motor chamber to the gas path, and the gas path includes a third gas path (for example, the third pipe body portion L14) connected to the gas outlet.

[0243] According to this structure, the hydrogen gas in the motor chamber is cooled by the liquid hydrogen in the pump chamber and circulates without staying in the motor chamber. As a result, the hydrogen gas environments in the motor chamber and the buffer tank achieve heat and pressure balance, and the temperature in the motor chamber is maintained at a low level.

[0244] A 14th embodiment of the present invention is the pump system according to the 13th embodiment, wherein the fan is mounted on the rotating shaft and causes the hydrogen gas introduced from the gas inlet to flow toward the gas outlet.

[0245] According to this structure, no special mechanism for accommodating and rotating the fan is required, and the hydrogen gas in the motor chamber can easily flow.

[0246] A 15th embodiment of the present invention is the pump system according to the 14th embodiment, wherein the fan is axially mounted at the other end portion (for example, the rear end portion 31b) of the rotating shaft, the housing (for example, housing 30) includes a partition wall (for example, partition wall 30c) that divides a first motor chamber (for example, the first motor chamber 36a) accommodating the motor from a second motor chamber (for example, the second motor chamber 36b) accommodating the fan, the partition wall has a ventilation hole (for example, ventilation hole 30d) that communicates the first motor chamber with the second motor chamber, the gas inlet opens in the second motor chamber, the gas outlet opens in the first motor chamber, and is axially disposed at a position closer to the one end portion side than the motor.

[0247] According to this structure, a circulation path for the hydrogen gas to circulate is formed. The hydrogen gas in the motor chamber is cooled by the liquid hydrogen in the pump chamber and circulates in the circulation path. Thus, the gas environment in the circulation path becomes a state of heat and pressure balance.

[0248] A 16th embodiment of the present invention is the pump system according to the 7th embodiment, wherein the pump system has: a purge gas path (e.g., purge gas path L2), which is connected to a purge gas tank (e.g., the second storage tank T2) and the gas path, and the purge gas tank (e.g., the second storage tank T2) stores a purge gas (e.g., helium He(G)) for purging the hydrogen introduced into the motor chamber; and a switching unit (e.g., the first valve V1, the second valve V2), which switches the gas introduced into the motor chamber between the purge gas and the hydrogen.

[0249] According to this structure, in cases such as the maintenance of the pump device, hydrogen, which is a flammable gas, will not leak to the external environment, and the disassembly and decomposition of the pump device can be safely carried out.

[0250] A 17th embodiment of the present invention is an operation method of a pump system (e.g., pump systems 1, 1A, 1B, 1C, 1D, 1E, 1F), which is connected to a storage tank (e.g., the first storage tank T1) storing liquid hydrogen (e.g., liquid hydrogen H2(L)) and hydrogen gas (e.g., hydrogen gas H2(G)) vaporized from the liquid hydrogen, and transports the liquid hydrogen. The pump system includes: a pump device (e.g., pump devices 2, 2A), which sucks and discharges the liquid hydrogen; and a gas path (e.g., gas path L1), which is connected to the gas phase part (e.g., gas phase part T1 G) storing the hydrogen gas in the storage tank. The pump device includes: a rotating shaft (e.g., rotating shaft 31); a motor (e.g., motor M), which rotates the rotating shaft; an impeller (e.g., impeller 41), which is installed at one end (e.g., front end 31a) of the rotating shaft in the axial direction of the rotating shaft; a housing (e.g., housings 30, 40), which has a motor chamber (e.g., motor chamber 36) for accommodating the motor and a pump chamber (e.g., pump chamber 43) for accommodating the impeller; and a mechanical seal (e.g., mechanical seal 42), which is installed on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The motor includes: a rotor (e.g., rotor 34), which is installed on the rotating shaft; and a stator (e.g., stator 35), which directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor. The operation method of the pump system includes: a pre-preparation step of preparing until the pump device can perform liquid transportation; and a step of discharging the liquid hydrogen from the pump chamber. The pre-preparation step includes: a step of introducing the liquid hydrogen into the pump chamber; and a step of introducing the hydrogen gas into the motor chamber via the gas path.

[0251] According to this structure, in a pump device equipped with a mechanical seal, leak-free hydrogen can be achieved, and stable transportation of liquid hydrogen from low-speed rotation to high-speed rotation can be achieved.

Claims

1. A pump device is connected to a storage tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveys the liquid hydrogen. Among them, the pump device includes: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is axially mounted on one end of the rotating shaft; a housing that has a motor chamber for accommodating the motor and a pump chamber for accommodating the impeller; and a mechanical seal that is mounted on the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber, the motor includes: a rotor that is mounted on the rotating shaft; and a stator that directly faces the rotor in the radial direction of the rotating shaft and rotates the rotor, the hydrogen gas is introduced into the motor chamber.

2. The pump device according to claim 1, wherein the housing has a gas inlet connected to a gas path that is connected to the gas phase portion of the storage tank storing the hydrogen gas, the hydrogen gas is introduced into the motor chamber through the gas inlet.

3. The pump device according to claim 2, wherein the housing includes: an outer wall that divides between the pump chamber and the motor chamber and the external environment of the housing; a suction port that is disposed on the pump chamber side of the housing and sucks the liquid hydrogen from the storage tank into the pump chamber; a discharge port that is disposed on the motor chamber side of the housing and discharges the liquid hydrogen from the pump chamber; and a guiding flow path that is disposed inside the outer wall and guides the liquid hydrogen from the pump chamber to the discharge port.

4. The pump device according to claim 3, wherein the pump device has a heat exchange path that forms part of the gas path, the heat exchange path is arranged such that heat exchange can occur between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guiding flow path.

5. The pump device according to any one of claims 2 to 4, wherein the pump device has a fan disposed in the motor chamber, the housing has a gas outlet that discharges the hydrogen gas introduced into the motor chamber to the gas path, the fan causes the hydrogen gas introduced into the motor chamber from the gas inlet to flow toward the gas outlet.

6. The pump device according to claim 1, wherein the motor is a permanent magnet motor in which the rotor has a permanent magnet, the pump device includes a protection member that covers the rotor and isolates the rotor from the hydrogen gas.

7. A pump system is connected to a storage tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and conveys the liquid hydrogen. Among them, the pump system includes: a pump device that sucks and discharges the liquid hydrogen; and a gas path that is connected to the gas phase portion of the storage tank storing the hydrogen gas, the pump device includes: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is axially mounted on one end of the rotating shaft; a housing that has a motor chamber for accommodating the motor and a pump chamber for accommodating the impeller; and A mechanical seal is installed on the rotating shaft and the housing to seal the motor chamber relative to the pump chamber. The motor includes: a rotor installed on the rotating shaft; and a stator directly opposed to the rotor in the radial direction of the rotating shaft to rotate the rotor. The housing has a gas inlet connected to the gas path. The hydrogen gas is introduced into the motor chamber via the gas path and the gas inlet.

8. The pump system according to claim 7, wherein the gas path includes: a buffer tank for temporarily storing the hydrogen gas; a first gas path connected to the buffer tank and the gas phase part; a second gas path connected to the buffer tank and the gas inlet; and a switching valve connected to the first gas path to open and close the first gas path.

9. The pump system according to claim 8, wherein the pump system has: a discharge flow path connected to a discharge port provided on the housing for discharging the liquid hydrogen from the pump chamber; and a heat exchanger for exchanging heat between the hydrogen gas in the gas path and the liquid hydrogen in the discharge flow path.

10. The pump system according to claim 9, wherein the discharge flow path is arranged so as to be able to exchange heat between the liquid hydrogen flowing in the discharge flow path and the hydrogen gas in the buffer tank, and the buffer tank functions as the heat exchanger.

11. The pump system according to claim 7, wherein the housing includes: an outer wall for partitioning the pump chamber and the motor chamber respectively; a suction port arranged on the pump chamber side of the housing for sucking the liquid hydrogen from the storage tank into the pump chamber; a discharge port arranged on the motor chamber side of the housing for discharging the liquid hydrogen from the pump chamber; and a guiding flow path arranged inside the outer wall for guiding the liquid hydrogen from the pump chamber to the discharge port.

12. The pump system according to claim 11, wherein the gas path has a heat exchange path installed on the pump device, and the heat exchange path is arranged so as to be able to exchange heat between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guiding flow path.

13. The pump system according to any one of claims 7 to 12, wherein the pump system has a fan for circulating the hydrogen gas between the motor chamber and the gas path, the housing has a gas outlet for discharging the hydrogen gas introduced into the motor chamber to the gas path, and the gas path has a third gas path connected to the gas outlet.

14. The pump system according to claim 13, wherein the fan is installed on the rotating shaft and makes the hydrogen gas introduced from the gas inlet flow toward the gas outlet.

15. The pump system according to claim 14, wherein the fan is installed at the other end of the rotating shaft in the axial direction, and the housing has a partition wall that partitions a first motor chamber for accommodating the motor and a second motor chamber for accommodating the fan. The partition wall is provided with ventilation holes that communicate the first motor chamber with the second motor chamber. The gas inlet opens into the second motor chamber. The gas outlet opens into the first motor chamber and is arranged axially at a position closer to the one end side than the motor.

16. The pump system according to claim 7, wherein The pump system includes: A purge gas path connected to a purge gas tank and the gas path, the purge gas tank storing a purge gas for purging the hydrogen introduced into the motor chamber; and A switching unit that switches the gas introduced into the motor chamber between the purge gas and the hydrogen.

17. An operating method of a pump system, the pump system being connected to a storage tank storing liquid hydrogen and hydrogen vaporized from the liquid hydrogen and transporting the liquid hydrogen, wherein The pump system includes: A pump device that sucks and discharges the liquid hydrogen; and A gas path connected to a gas phase portion of the storage tank storing the hydrogen. The pump device includes: A rotating shaft; A motor that rotates the rotating shaft; An impeller axially mounted at one end of the rotating shaft; A housing having a motor chamber for accommodating the motor and a pump chamber for accommodating the impeller; and A mechanical seal mounted on the rotating shaft and the housing to seal the motor chamber from the pump chamber. The motor includes: A rotor mounted on the rotating shaft; and A stator directly opposed to the rotor in the radial direction of the rotating shaft and rotating the rotor. The operating method of the pump system includes: A pre-preparation step of preparing until the pump device can perform liquid transportation; and A step of discharging the liquid hydrogen from the pump chamber. The pre-preparation step includes: A step of introducing the liquid hydrogen into the pump chamber; and A step of introducing the hydrogen into the motor chamber via the gas path.

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