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

Abstract

The invention provides a pump device, a pump system and a method for operating the pump system, wherein liquid hydrogen does not leak to the external environment and the pump device is more suitable for high-speed rotation than a pump with a rotor sealed by liquid. A pump device (2, 2A) is connected to a tank (T1) for storing liquid hydrogen and hydrogen gas obtained by vaporizing the liquid hydrogen, and conveys the liquid hydrogen. A pump device is provided with: a rotating shaft (31); a motor (M) that rotates the rotating shaft; an impeller (41) attached to the tip (31a) of the rotating shaft; a housing (30, 40) having a motor chamber (36) in which the motor is housed and a pump chamber (43) in which the impeller is housed; and a mechanical seal (42) that is attached to the rotating shaft and the housing and seals the motor chamber with respect to the pump chamber. The motor includes: a rotor (34) attached to the rotating shaft; and a 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.

Description

Technical Field

[0001] The 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 be used as a fuel for fuel cells, theoretically converting it into electricity with high energy efficiency and without releasing harmful emissions, making it an efficient clean energy source. Hydrogen is stored as liquid hydrogen at hydrogen refueling stations for fuel cell vehicles, for example.

[0003] When a centrifugal pump having a motor part and a pump part divided by a mechanical seal is used to transport liquid hydrogen, a small amount of liquid hydrogen will leak from the mechanical seal part. The leaked liquid hydrogen vaporizes and becomes hydrogen gas, and leaks into the external environment. Therefore, for example, it is necessary to use helium to purge the hydrogen gas, but the operating cost of the treatment is high and the system of the treatment is complicated. Therefore, a method of using a leak-free shielded pump to transport liquid hydrogen is proposed (for example, refer to patent document 1).

[0004] Prior art literature

[0005] Patent Literature:

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-162275 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] Since the specific gravity of liquid hydrogen is as small as about 0.07, in order to obtain the pressure required for conveying liquid, the rotor needs to rotate at high speed. In this case, the magnetic flux of the metal can sealed with the rotor will change at high speed, and the phenomenon of eddy current flow (so-called can loss (can loss)) will occur in the metal can. This phenomenon will increase according to the rotation frequency of the motor part (rotor). In addition, since the rotor rotates in the liquid, the fluid friction loss caused by the liquid to the rotor will increase according to the rotation frequency of the motor part (rotor). Therefore, the canned pump is sometimes not suitable for use as a centrifugal pump that utilizes high-speed rotation to convey liquid hydrogen.

[0009] On the other hand, as a leak-free centrifugal pump, a pump in which the motor part (rotor and stator) is liquid-sealed together with the process liquid is known. The above-mentioned eddy flow phenomenon will not occur in this pump, but fluid friction loss caused by the liquid on the rotor will occur. In addition, when using this pump and a canned pump, if the discharge flow rate becomes smaller, the temperature rise of the discharge liquid is likely to accelerate, and two-phase flow in the pump part is also likely to occur. In this pump and a canned pump, if a two-phase flow occurs in the pump part, the bearing lubrication of the rotating shaft of the rotor becomes unstable, the fluid exciting force on the rotor becomes larger, and the life of the bearing is shortened. Therefore, in this pump and a canned pump, the motor part must always be filled with the process liquid. However, the boiling point of liquid hydrogen is extremely low temperature, and in order to always fill the motor part with liquid hydrogen, a 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 the pump system, which prevents liquid hydrogen from leaking to the external environment and is more suitable for high-speed rotation than a pump with a liquid-sealed rotor.

[0011] Solutions for solving problems

[0012] A pump device in one embodiment of the present invention is connected to a storage tank storing liquid hydrogen and hydrogen gas formed by vaporizing the liquid hydrogen, and transports the liquid hydrogen, wherein the pump device comprises: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame that has a motor chamber that accommodates the motor and a pump chamber that accommodates the impeller; and a mechanical seal that is mounted on the rotating shaft and the frame and seals the motor chamber relative to the pump chamber, wherein the motor comprises: a rotor that is mounted on the rotating shaft; and a stator that is directly opposite to the rotor in the radial direction of the rotating shaft and rotates the rotor, and the hydrogen gas is introduced into the motor chamber.

[0013] A pump system in one embodiment of the present invention is connected to a tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and transports the liquid hydrogen, wherein the pump system comprises: a pump device that sucks in and discharges the liquid hydrogen; and a gas path that is connected to a gas phase portion of the tank storing the hydrogen gas, the pump device comprising: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame that has a motor chamber that accommodates the motor and a pump chamber that accommodates the impeller; and a mechanical seal that is mounted on the rotating shaft and the frame and seals the motor chamber relative to the pump chamber, the motor comprising: a rotor that is mounted on the rotating shaft; and a stator that is directly opposed to the rotor in the radial direction of the rotating shaft and rotates the rotor, the frame comprising a gas inlet that opens in 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] An operating method of a pump system in one embodiment of the present invention, the pump system is connected to a storage tank storing liquid hydrogen and hydrogen gas formed by vaporizing the liquid hydrogen, and transports the liquid hydrogen, wherein the pump system comprises: a pump device that sucks in and discharges the liquid hydrogen; and a gas path that is connected to a gas phase portion storing the hydrogen gas in the storage tank, the pump device comprises: a rotating shaft; a motor that rotates the rotating shaft; an impeller that is mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame that has a motor chamber that accommodates the motor and a pump chamber that accommodates the impeller; and a mechanical seal. A seal is mounted on the rotating shaft and the frame to seal the motor chamber relative to the pump chamber, the motor comprising: a rotor mounted on the rotating shaft; and a stator directly opposed to the rotor in the radial direction of the rotating shaft and causing the rotor to rotate, the operating method of the pump system comprising: a pre-preparation step of preparing until the pump device is capable of liquid transport; and a step of discharging the liquid hydrogen from the pump chamber, the pre-preparation step comprising: 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] Effects of the Invention

[0016] According to the present invention, it is possible to provide a pump device, a pump system, and an operating method of the pump system that prevents liquid hydrogen and hydrogen gas from leaking to the external environment and is more suitable for high-speed rotation than a pump with a liquid-sealed rotor. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0019] Figure 3 It is shown Figure 1 Schematic piping diagram of the first variant of the pump system.

[0020] Figure 4 It is shown Figure 1 Schematic piping diagram of a second variant of the pump system.

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

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

[0023] Figure 7 It is shown Figure 5 Schematic piping diagram of the first variant of the pump system.

[0024] Figure 8 It is shown Figure 5 Schematic piping diagram of a second variant of the pump system.

[0025] Fig. 9 It is shown Figure 5 Schematic piping diagram of the third variant of the pump system. DETAILED DESCRIPTION

[0026] Below, refer to the attached Figure 1 The embodiments of the pump device, pump system and operation method of the pump system of the present invention are described. In each figure, the same components and elements are marked with the same reference numerals, and repeated descriptions are omitted. In addition, for ease of description, the size ratios of each element are sometimes exaggerated, and are not limited to the ratios shown in each figure.

[0027] ●Pump system(1)●

[0028] First, an embodiment of the pump system of the present invention (hereinafter referred to as “first embodiment”) will be described.

[0029] ●Structure of pump system (1)

[0030] Figure 1 This is a schematic piping diagram showing a first embodiment of the pump system of the present invention.

[0031] The pump system 1 transports liquid hydrogen H2 (L) and includes a pump device 2, a first tank T1, a second 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.

[0032] The pump device 2 is connected to the first tank T1 and delivers the liquid hydrogen H2 (L) stored in the first tank T1. The structure of the pump device 2 will be described later.

[0033] The first tank T1 is a known high-pressure hydrogen tank that stores liquid hydrogen H2(L). The first tank T1 is an example of a tank in the present invention. A liquid phase T1L and a gas phase T1G are formed inside the first tank T1. The liquid phase T1L stores liquid hydrogen H2(L), and the gas phase T1G stores hydrogen gas H2(G) vaporized from the liquid hydrogen H2(L). The gas phase T1G is disposed above the liquid phase T1L.

[0034] The second tank T2 is, for example, a known helium high-pressure tank that stores helium gas He(G) in the pump system 1. The helium gas He(G) functions as a purge gas for the hydrogen gas H2(G). The second tank T2 is an example of a purge gas tank in the present invention.

[0035] The gas path L1 is connected to the gas phase portion T1G and the motor chamber 36 described later, and is a path through which the hydrogen gas H2 (G) passes therebetween. The gas path L1 includes a tube portion L11, a first valve V1, and a second valve V2.

[0036] The pipe body L11 is a known pipe body connected to the gas phase portion T1G and a motor chamber 36 described later. The pipe body L11 is made of, for example, stainless steel and has a known heat insulating structure (for example, a vacuum heat insulating structure formed by a double structure).

[0037] The first valve V1 and the second valve V2 are known valves (e.g., gate valves) connected to the tube body L11 and opening and closing the tube body L11. The first valve V1 and the second valve V2 are made of, for example, stainless steel and have a known heat insulation structure (e.g., a vacuum heat insulation structure formed by a double structure). In the gas path L1, the second valve V2 is arranged at a position further downstream (on the pump device 2 side) than the first valve V1. The first valve V1 is an example of an on-off valve in the present invention.

[0038] The purge gas path L2 is connected to the second tank T2 and the gas path L1, and is a path through which the helium gas He(G) passes. The purge gas path L2 includes a tube body 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 tube body L11.

[0039] The tube body L21 is a known tube body connected to the second tank T2 and the gas path L1. The tube body L21 is made of metal, for example, like the tube body L11, and has the same heat insulation structure as the tube body L11.

[0040] The third valve V3 is a known valve (eg, a gate valve) connected to the purge gas path L2 to open and close the purge gas path L2. The third valve V3 is made of metal, for example, like the first valve V1, and has the same heat-insulating structure as the first valve V1.

[0041] The suction flow path L3 is a known pipe connected to the liquid phase portion T1 L and a suction port 44a described later. The suction flow path L3 is made of, for example, stainless steel and has a known heat insulating structure (for example, a vacuum heat insulating structure formed by a double structure).

[0042] The suction valve V11 is a known valve (eg, a gate valve) connected to the suction flow path L3 and opens and closes the suction flow path L3. The suction valve V11 is made of, for example, stainless steel and has a known heat insulating structure (eg, a vacuum heat insulating structure formed by a double structure).

[0043] 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, like the suction flow path L3, and has the same heat insulation structure as the suction flow path L3.

[0044] The discharge valve V12 is a known valve (eg, a gate valve) connected to the discharge flow path L4 and opens and closes the discharge flow path L4. The discharge valve V12 is made of, for example, stainless steel and has a known heat insulating structure (eg, a vacuum heat insulating structure formed by a double structure).

[0045] Here, each tube body L11, L21 is mainly a tube body for passing these gases in order to make the gas environment in the motor chamber 36 described later become a corresponding gas (hydrogen H2(G), helium He(G)) environment. Each tube body L11, L21 is composed of a relatively thin tube body (thin tube) 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 a relatively thick tube body (thick tube) according to the corresponding flow rate of the pump device 2.

[0046] In addition, the heat insulation structure of each tube body, the first to third valves V1 to V3, the suction valve V11, and the discharge valve V12 is a known heat insulation structure and is not limited to the structure described in this embodiment. That is, for example, 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 can be accommodated in a chamber and the gas environment in the chamber can be maintained as a vacuum environment.

[0047] ●Structure of pump device (1)

[0048] Figure 2This is a schematic cross-sectional view showing an embodiment of the pump device of the present invention (hereinafter referred to as the "first embodiment"). The figure illustrates the flow of hydrogen gas H2(G) introduced into the pump device 2 with white arrows, and illustrates the flow of hydrogen gas H2(G) vaporized from liquid hydrogen H2(L) described later with black arrows.

[0049] The pump device 2 includes a motor unit 3, a pump unit 4, a temperature sensor 5, and a pressure sensor 6. The main structure of the pump device 2 is almost the same as that of a known canned pump, except that the pump device 2 does not include a metal tank for liquid-sealing a rotor 34 described later, and the pump device 2 includes a mechanical seal 42 described later. Therefore, in the following description, the structure of the motor unit 3 and the pump unit 4 is described mainly with respect to the points that are different from the structure of the known canned pump, and detailed description of other structures is omitted.

[0050] In the following description, the “front direction” is a direction in which the pump section 4 is located relative to the motor section 3 , and the “rear direction” is a direction in which the motor section 3 is located relative to the pump section 4 .

[0051] The motor unit 3 is driven at a predetermined driving voltage / driving frequency to rotate an impeller 41 described later. The motor unit 3 includes a frame 30, a rotating shaft 31, bearings 32 and 33, a rotor 34, a stator 35, and a motor chamber 36. The rotor 34 and the stator 35 constitute a motor M, which is an example of a motor in the present invention.

[0052] The housing 30 defines a motor chamber 36 for accommodating the rotating shaft 31, bearings 32 and 33, a rotor 34, and a stator 35. That is, the housing 30 includes the motor chamber 36. The housing 30 includes a gas introduction port 30a. The housing 30 is made of, for example, stainless steel.

[0053] The gas introduction port 30a is a through hole that penetrates the housing 30. The gas introduction port 30a is disposed, for example, at the rear portion of the housing 30, and opens into the motor chamber 36. The gas path L1 (tube portion L11) is connected to the gas introduction port 30a.

[0054] 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 31a of the rotating shaft 31 protrudes into the pump chamber 43 described later. In the axial direction of the rotating shaft 31, the front end 31a of the rotating shaft 31 is an example of one end in the present invention, and the rear end 31b is an example of the other end in the present invention.

[0055] The bearings 32 and 33 are attached to the frame 30 and the rotating shaft 31, thereby rotatably supporting the rotating shaft 31. The bearing 32 is arranged in front of the rotor 34, and the bearing 33 is arranged behind the rotor 34. The bearings 32 and 33 are, for example, known ball bearings.

[0056] The rotor 34 is rotated by the rotating magnetic field generated by the stator 35. The rotor 34 is cylindrical in shape and is accommodated in the stator 35.

[0057] 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 circumference of the stator 35 is directly opposite to the outer circumference of the rotor 34. That is, a structure (shielding object) such as a metal can provided in a known canned motor pump is not arranged between the rotor 34 and the stator 35.

[0058] The pump unit 4 sucks in and discharges liquid hydrogen H 2 (L). The pump unit 4 includes a housing 40 , an impeller 41 , a mechanical seal 42 , a pump chamber 43 , a suction pipe 44 , and a discharge pipe 45 .

[0059] The frame 40 is divided into a pump chamber 43 that accommodates an impeller 41 and a mechanical seal 42, and is formed with a suction pipe portion 44 and a discharge pipe portion 45. The suction pipe portion 44 is a flow path for liquid hydrogen H2 (L) sucked into the pump chamber 43, and the discharge pipe portion 45 is a flow path for liquid hydrogen H2 (L) discharged from the pump chamber 43. That is, the frame 40 has a pump chamber 43, a suction pipe portion 44, and a discharge pipe portion 45. The pump chamber 43 is connected to 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 frame 40 is made of metal like the frame 30. The frame 40 is arranged in front of the frame 30 and is installed on the frame 30. The frame 40 and the frame 30 together constitute the frame in the present invention.

[0060] The impeller 41 is attached to the front end portion 31 a of the rotating shaft 31 and is accommodated in the pump chamber 43 .

[0061] The mechanical seal 42 is mounted on the rotating shaft 31 and the frame 40, thereby sealing the motor chamber 36 relative to the pump chamber 43. The mechanical seal 42 is arranged between the bearing 33 and the impeller 41 in the axial direction of the rotating shaft 31. The mechanical seal 42 is, for example, a known mechanical seal, and includes a fixed ring (not shown) mounted on the frame 40 and a rotating ring (not shown) mounted on the rotating shaft 31.

[0062] The temperature sensor 5 is mounted on the motor unit 3, and detects the temperature in the motor chamber 36. The temperature sensor 5 is, for example, a known temperature sensor that can detect temperatures as low as extremely low temperatures (for example, the temperature of liquid hydrogen H2 (L)).

[0063] The pressure sensor 6 is mounted on the motor portion 3, and detects the pressure in the motor chamber 36. The pressure sensor 6 is, for example, a known pressure sensor.

[0064] ●Operation of the pump system (1)

[0065] Next, the operation of the pump system 1, that is, the method of operating the pump system 1 of the present invention will be described. Figure 1 and Figure 2 .

[0066] Before the pump system 1 starts to operate (before the pump device 2 starts to operate), 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 pump device 2 side), the suction pipe section 44, the pump chamber 43, the discharge pipe section 45, and the upstream side of the discharge valve V12 in the discharge flow path L4 (the pump device 2 side) are maintained in a vacuum environment, for example, by a vacuum pump (not shown. The same applies hereinafter) connected to the discharge flow path L4.

[0067] It should be noted that in the present invention, before the pump system 1 starts operating, the gas path L1 downstream of the first valve V1 and the motor chamber 36 may be filled with helium gas having a lower melting point than hydrogen.

[0068] First, preparation is performed until the pump device 2 is capable of liquid transportation (preliminary preparation step). In the preliminary preparation step, first, the connection between the discharge flow path L4 and the vacuum pump is blocked. Next, the suction valve V11 is opened, and the liquid hydrogen H2 (L) stored 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 discharge flow path L4 on the upstream side of the discharge valve V12 (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 discharge flow path L4 on the upstream side of the discharge valve V12 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 discharge flow path L4 on the upstream side of the discharge valve V12 are cooled to the temperature of liquid hydrogen H2 (L) (flow path precooling step).

[0069] Next, open the first valve V1 and the second valve V2. At this time, the motor chamber 36 is connected to the gas phase part T1 G via the gas path L1 and the gas inlet port 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 port 30a (hydrogen gas introduction step). As a result, the motor chamber 36 is filled with hydrogen gas H2(G), and the hydrogen gas H2(G) is cooled by the liquid hydrogen H2(L) in the pump chamber 43 via the rotating shaft 31 and the frames 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 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 the hydrogen gas H2(G) is introduced, the gas path L1 is maintained in a vacuum environment (or a helium environment) on the downstream side of the first valve V1 and in the motor chamber 36. Therefore, other gas components (e.g., oxygen or nitrogen, etc.) that can be frozen by the introduced extremely low-temperature hydrogen gas H2(G) do not exist in the gas path L1 and the motor chamber 36, and technical problems caused by the freezing of the gas components (e.g., clogging of the tube body L11 of the capillary, freezing of the bearings 32, 33, etc.) do not occur.

[0070] It should be noted that in the preparatory step, the hydrogen introduction step may be performed simultaneously with the liquid hydrogen introduction step or may be performed before the liquid hydrogen introduction step. In the latter case, the hydrogen introduction step may also be performed before the gas environment in the motor chamber 36 is balanced.

[0071] Next, the discharge valve V12 is opened, the pump device 2 is activated, and the impeller 41 rotates, thereby discharging the liquid hydrogen H2 (L) in the pump chamber 43 to the discharge flow path L4 via the discharge pipe portion 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 precooling step). At this time, the pump device 2 can be used to transport liquid hydrogen H2 (L) (each action in the pre-preparation step is completed). Then, the transport of liquid hydrogen H2 (L) begins (liquid hydrogen transport step). At this time, the first valve V1 is closed, and the motor chamber 36 is blocked from the gas phase portion T1 G. As a result, the gas environment in the gas path L1 downstream of the first valve V1 and in the motor chamber 36 is maintained as a predetermined hydrogen H2 (G) environment.

[0072] At this time, the bearings 32 and 33 are lubricated by hydrogen gas H2 (G). Here, the kinematic viscosity of hydrogen gas H2 (G) is several times greater than that of liquid hydrogen H2 (L). Therefore, compared with the case where 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 better.

[0073] As described above, since the first valve V1 is closed, the gas path L1 downstream of the first valve V1 and the motor chamber 36 become a closed space (gas phase space) of the hydrogen H2 (G) environment. Therefore, the hydrogen H2 (G) in the motor chamber 36 is cooled by the liquid hydrogen H2 (L) flowing in the pump chamber 43 via the frame 30, 40 and the rotating shaft 31, and the hydrogen H2 (G) environment in the motor chamber 36 becomes a state of heat and pressure balance. In addition, the heat generated locally in the motor chamber 36 (for example, the bearings 32, 33 or the motor M) is absorbed by the extremely low temperature hydrogen H2 (G) in the motor chamber 36. Here, the structure of the gas path L1 and the motor chamber 36 (frame 30) constituting the gas phase space is a structure that can allow the assumed heat and the pressure change caused by the heat during the normal operation of the pump device 2. In addition, since the first valve V1 is closed, the heat absorbed by the hydrogen H2 (G) in the motor chamber 36 is not transferred to the gas phase portion T1G.

[0074] In addition, as described above, the motor chamber 36 is filled with hydrogen H2 (G) instead of liquid hydrogen H2 (L) of the treatment liquid. Therefore, the rotor 34 will not have the fluid friction loss that occurs in the liquid-sealed rotor of the existing leak-free centrifugal pump (hereinafter referred to as the "existing pump"). In addition, since there is no metal can between the rotor 34 and the stator 35, there will be no loss caused by eddy currents such as the existing shielded pump. That is, in the pump device 2, even if the number of rotations of the rotor 34 is increased, the fluid friction loss and the loss caused by eddy currents that exist in the existing pump will not occur. Therefore, the overall efficiency of the pump device 2 is improved compared to the existing pump, and the pump device 2 is more adaptable to high-speed rotation than the existing pump. Moreover, even if the pump device 2 rotates at a low speed, the gas environment in the motor chamber 36 is also a hydrogen H2 (G) environment (single-phase flow), and no two-phase flow will occur in the motor chamber 36. Therefore, the pump device 2 is more adaptable to low-speed rotation than the existing pump.

[0075] As described above, the motor chamber 36 is sealed relative to the pump chamber 43 by the mechanical seal 42. Therefore, as the rotary shaft 31 rotates, a small amount of liquid hydrogen H2(L) may leak into the motor chamber 36 through the mechanical seal 42. The liquid hydrogen H2(L) leaked into the motor chamber 36 vaporizes and becomes hydrogen gas H2(G), but the hydrogen gas H2(G) diffuses into the hydrogen gas H2(G) filling the motor chamber 36 ( Figure 2 The pump system 1 is not leaked to the external environment of the motor chamber 36, the gas path L1 and the gas phase part T1 G (if the first valve V1 is opened). That is, the pump system 1 uses the mechanical seal 42, and the pump system 1 as a whole also achieves no leakage of liquid hydrogen H2 (L) and hydrogen gas H2 (G).

[0076] In addition, as described above, the motor chamber 36 is filled with hydrogen gas H2 (G) instead of liquid hydrogen H2 (L) of the process liquid. Therefore, when the operation of the pump system 1 starts, it is not necessary to fill the motor part 3 with liquid hydrogen H2 (L) as in the conventional pump, and when the operation of the pump system 1 ends, it is not necessary to vaporize the liquid hydrogen H2 (L) filled in the motor part 3 before discharging it (vaporization treatment). That is, in the pump system 1, the liquid hydrogen H2 (L) is introduced only into the pump chamber 43. Therefore, it is possible to suppress unnecessary consumption of liquid hydrogen H2 (L), reduce the operating cost of the pump system 1, and save energy.

[0077] In this way, in the pump system 1, hydrogen (liquid hydrogen H2(L) and hydrogen gas H2(G)) will not leak to the external environment, and liquid hydrogen H2(L) can be discharged efficiently. During the operation of the pump system 1, the state (temperature and pressure) in the motor chamber 36 is detected by the temperature sensor 5 and the pressure sensor 6. Therefore, it is always possible to detect an abnormal state in the motor chamber 36. Therefore, 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 abnormal state in the motor chamber 36.

[0078] Next, when stopping the operation of the pump system 1, first, stop the operation of the pump device 2, and close the suction valve V11 and the discharge valve V12. As a result, the introduction of liquid hydrogen H2 (L) into the pump chamber 43 and the liquid delivery of the pump device 2 are stopped. Next, the third valve V3 is opened, and 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). The purged gas is discharged, for example, via a discharge path (not shown) connected to the gas path L1. Therefore, in situations such as maintenance of the pump device 2, the hydrogen H2 (G) as a flammable gas will 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 by a vacuum pump in the gas path L1 downstream of the first valve V1, the motor chamber 36, the suction flow path L3 downstream of the suction valve V11, the suction pipe portion 44, the pump chamber 43, the discharge pipe portion 45 and the discharge flow path L4 upstream of the discharge valve V12.

[0079] In this way, when the first valve V1 is closed and the third valve V3 is opened, the purge gas (helium He(G)) is introduced into the motor chamber 36, and when the first valve V1 is opened and the third valve V3 is closed, the hydrogen 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 the hydrogen H2(G).

[0080] ●Summary(1)●

[0081] According to the embodiment described above, the pump device 2 has a rotating shaft 31, a motor M (rotor 34, stator 35), an impeller 41, frames 30, 40 and a mechanical seal 42. The motor M is housed in the motor chamber 36 and rotates the rotating shaft 31. The impeller 41 is mounted on the front end portion 31a of the rotating shaft 31 and is housed in the pump chamber 43. The frame 30 divides the motor chamber 36, and the frame 40 divides the pump chamber 43. The mechanical seal 42 is mounted on the rotating shaft 31 and the frame 40, and seals the motor chamber 36 relative to the pump chamber 43. In the radial direction of the rotating shaft 31, the rotor 34 and the stator 35 are directly opposed. 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.

[0082] According to this structure, during the operation of the pump device 2, the motor chamber 36 is filled with hydrogen 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 will vaporize and diffuse into the hydrogen H2 (G) in the motor chamber 36, and will not leak into the external environment of the motor chamber 36. That is, the pump device 2 achieves no leakage of hydrogen (liquid hydrogen H2 (L) and hydrogen H2 (G)) while using the mechanical seal 42. In addition, the bearings 32 and 33 are lubricated by hydrogen H2 (G) having a higher kinematic viscosity than liquid hydrogen H2 (L). Then, the heat generated locally in the motor chamber 36 is absorbed by the extremely low temperature hydrogen H2 (G) in the motor chamber 36. Moreover, the hydrogen H2 (G) in the motor chamber 36 is cooled by the liquid hydrogen H2 (L) in the pump chamber 43, and the hydrogen H2 (G) environment in the motor chamber 36 becomes a state of heat and pressure balance. In addition, the pump device 2 does not have losses caused by fluid friction losses or eddy currents as in the existing pumps. Therefore, compared to the existing pumps, the overall efficiency of the pump device 2 is improved, and the pump device 2 can adapt to operations from low-speed rotation to high-speed rotation. In addition, unlike the existing pumps, when the pump device 2 starts to operate, liquid hydrogen H2 (L) is not introduced into the motor part 3. Therefore, when the pump device 2 ends its operation, it is not necessary to perform a vaporization process before removing the liquid hydrogen H2 (L) filled in the motor part 3. Therefore, unnecessary consumption of liquid hydrogen H2 (L) can be suppressed, the operating cost of the pump device 2 can be reduced, and energy can be saved.

[0083] 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. In addition, the pump system 1 includes the above-mentioned pump device 2, so there is no loss caused by fluid friction loss or eddy current as in the existing pump, and it can adapt to the operation of liquid hydrogen H2 (L) from low speed rotation to high speed rotation.

[0084] 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.

[0085] 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).

[0086] ●Modification (1)●

[0087] Next, a modified example of the pump system 1 is described below, focusing on the differences from the first embodiment described above. In the following description of the modified example, for the sake of convenience, the same reference numerals as those in the first embodiment are used to indicate the same components and components having the same functions as those in the first embodiment. Figure 1 and Figure 2 .

[0088] ●First Modification

[0089] Figure 3 This is a schematic piping diagram showing a first modified example of the pump system of the first embodiment.

[0090] The pump system 1A includes a pump device 2, a first tank T1, a second 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 tube L11, a first valve V1, a buffer tank T3, and a second valve V2.

[0091] The tube body L11 includes a first tube body L12 and a second tube body L13. The first tube body L12 is a known tube body connected to the gas phase part T1G and the buffer tank T3. The second tube body L13 is a known tube body connected to the buffer tank T3 and the gas inlet 30a. The first tube body L12 is an example of the first gas path in the present invention, and the second tube body L13 is an example of the second gas path in the present invention.

[0092] The buffer tank T3 temporarily stores hydrogen gas H2 (G) in the gas path L1. The design pressure (volume) of the buffer tank T3 is set to be large enough to absorb pressure changes based on temperature changes on the downstream side of the buffer tank T3 in the gas path L1 and in the motor chamber 36. The buffer tank T3 is installed between the first valve V1 and the second valve V2 in the pipe body L11.

[0093] According to this structure, during the operation of the pump system 1A, even if the pressure in the motor chamber 36 changes due to the local heat in the motor chamber 36, the 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 gas path L1 downstream of the first valve V1 and the motor chamber 36 become closed spaces, the pressure in the motor chamber 36 is 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 the 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 than in the first embodiment. Therefore, the changes in pressure and temperature in the motor chamber 36 are more stable than in the first embodiment. Therefore, in the first modification, even if the first valve V1 is opened, the temperature rise of the hydrogen gas H2(G) in the motor chamber 36 is not transmitted to the gas phase portion T1G.

[0094] ● Second Modification

[0095] Figure 4 This is a schematic piping diagram showing a second modified example of the pump system of the first embodiment.

[0096] The pump system 1B includes a pump device 2, a first tank T1, a second 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 tube L11, a first valve V1, a buffer tank T3, and a second valve V2.

[0097] In this modified example, a portion of the discharge flow path L4 is installed in the buffer tank T3 in such a manner that heat exchange is performed 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 portion of the discharge flow path L4 is installed in the buffer tank T3 in such a manner that it meanders in the buffer tank T3. As a result, the buffer tank T3 and a portion 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.

[0098] In this structure, since the buffer tank T3 and the heat exchanger are formed as one body, the hydrogen H2(G) in the buffer tank T3 is always cooled during the operation of the pump device 2. Therefore, the effect of suppressing the pressure change by using the buffer tank T3 is further improved than that of 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 the space is good, and the increase in temperature and pressure in the gas path L1 and the motor chamber 36 can be suppressed. In addition, there is no need to connect the gas path L1 to the heat exchanger separately, and the number of connection parts that may become the main cause of the leakage of the hydrogen H2(G) is suppressed to a minimum, and space can be saved.

[0099] In addition, in this modification, the buffer tank T3 does not need to function as a heat exchanger, and the pump system 1B is provided with a heat exchanger for performing heat exchange between the hydrogen gas H2(G) in the gas path L1 and the liquid hydrogen H2(L) in the discharge flow path L4. In this structure, the hydrogen gas H2(G) in the gas path L1 is also always cooled, so the increase in temperature and pressure in the motor room 36 can be suppressed more than in the first modification.

[0100] ●Pump system (2)●

[0101] Next, another embodiment of the pump system (hereinafter referred to as the "second embodiment") is described below, focusing on the differences from the first embodiment, the first variant, and the second variant. In the following description of the second embodiment, for the sake of convenience, the same reference numerals as those in the first embodiment, the first variant, and the second variant are used for the same components and components having the same functions as those in the first embodiment, the first variant, and the second variant. In addition, in the following variants, reference is made to Figure 1 and Figure 2 .

[0102] ●Structure of pump system (2)

[0103] Figure 5 This is a schematic piping diagram showing a second embodiment of the pump system.

[0104] The pump system 1C transports liquid hydrogen H2 (L). The pump system 1C includes a pump device 2A, a first tank T1, a second tank T2, a gas path L1, a purge gas path L2, an intake flow path L3, an intake valve V11, a discharge flow path L4, and a discharge valve V12.

[0105] The pump device 2A is connected to the first tank T1 and transports the liquid hydrogen H2 (L) stored in the first tank T1. The structure of the pump device 2A will be described later.

[0106] The gas path L1 includes a tube portion L11 , a first valve V1 , a second valve V2 , a fourth valve V4 , and a buffer tank T3 .

[0107] The tube L11 includes a first tube L12, a second tube L13, and a third tube L14. The third tube L14 is a known tube connected to the buffer tank T3 and a gas outlet 30b described later. The third tube L14 is an example of a third gas path in the present invention.

[0108] The fourth valve V4 is a known valve (eg, a gate valve) connected to the third tube L14 to open and close the third tube L14. The fourth valve V4 is made of metal, for example, like the first valve V1, and has the same heat-insulating structure as the first valve V1.

[0109] ●Structure of pump device (2)

[0110] Figure 6 It is a schematic cross-sectional view showing another embodiment (hereinafter referred to as “second embodiment”) of the pump device (that is, pump device 2A) of the present invention.

[0111] The pump device 2A includes a motor unit 3, a pump unit 4, a temperature sensor 5, and a pressure sensor 6. The pump device 2A has the same structure as the pump device 2 in the first embodiment, except that the motor unit 3 includes a fan 37, a gas outlet 30b, and a partition wall 30c described later.

[0112] The motor unit 3 includes a housing 30 , a rotating shaft 31 , two bearings 32 and 33 , a rotor 34 , a stator 35 , a motor chamber 36 , and a fan 37 .

[0113] The frame 30 includes a gas introduction port 30 a , a gas outlet port 30 b , and a partition wall 30 c .

[0114] The gas inlet 30a is, for example, arranged at the rear of the frame 30 and opens at the second motor chamber 36b described later. The gas path L1 (the second tube portion L13) is connected to the gas inlet 30a. In the axial direction of the rotating shaft 31, the gas inlet 30a is arranged at a position further to the rear side than the motor M (on the rear end portion 31b side of the rotating shaft 31).

[0115] The gas outlet 30b is a through hole that penetrates the frame 30. The gas outlet 30b is, for example, arranged at the front of the frame 30 and opens at the first motor chamber 36a described later. The gas path L1 (the third tube portion L14) is connected to the gas outlet 30b. In the axial direction of the rotating shaft 31, the gas inlet 30a is arranged at a position closer to the front side (the front end portion 31a side of the rotating shaft 31) than the motor M.

[0116] The partition wall 30c divides the motor room 36 into a first motor room 36a accommodating the motor M and a second motor room 36b accommodating the fan 37. The first motor room 36a is arranged in front of the second motor room 36b. The partition wall 30c has a plurality of vents 30d that penetrate the partition wall 30c in the front-rear direction to communicate the first motor room 36a with the second motor room 36b.

[0117] The fan 37 makes the hydrogen gas H2(G) in the motor chamber 36 flow, thereby making the hydrogen gas H2(G) circulate between the gas path L1 and the motor chamber 36. The fan 37 is made of, for example, stainless steel. The fan 37 is mounted on the rear end portion 31b of the rotating shaft 31 protruding into the second motor chamber 36b, and is accommodated in the second motor chamber 36b. That is, the fan 37 is arranged in the motor chamber 36. The fan 37 is configured to rotate together with the rotating shaft 31 to make the hydrogen gas H2(G) flow forward.

[0118] ● Operation of the pump system (2)

[0119] 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. Figure 1 , Figure 2 , Figure 5 and Figure 6 .

[0120] Before the pump system 1C starts to operate (before the pump device 2A is operated), 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-mentioned vacuum pump.

[0121] First, similarly to the first embodiment, the liquid hydrogen introduction step and the flow path precooling step in the preliminary preparation step are performed.

[0122] Next, the first valve V1, the second valve V2, and the fourth valve V4 are opened. At this time, the motor chamber 36 and the gas phase portion T1G are connected via the gas path L1, and the hydrogen gas H2(G) stored in the gas phase portion T1G 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 equilibrium with the gas environment in the gas phase portion T1G. That is, the gas path L1 and 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.

[0123] Next, the discharge valve V12 is opened, the pump device 2A is activated, and the impeller 41 rotates, thereby discharging the liquid hydrogen H2 (L) in the pump chamber 43 to the discharge flow path L4 via the discharge pipe portion 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 precooling step). At the same time, the fan 37 rotates with the rotation of the rotating shaft 31, thereby the hydrogen 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 H2 (G) introduced from the gas inlet 30a into the second motor chamber 36b flows from the rear to the front, and flows out from the gas outlet 30b to the third tube body portion L14, thereby the hydrogen H2 (G) returns from the motor chamber 36 to the buffer tank T3 (circulation start step). At this time, the liquid hydrogen H2 (L) can be transported by the pump device 2A (each action in the pre-preparation step is completed). Then, liquid hydrogen H2(L) is started to be transported (liquid hydrogen transport step). At this time, the first valve V1 is closed, and the motor chamber 36 is blocked from the gas phase portion T1 G. As a result, the gas environment in the gas path L1 downstream of the first valve V1 and in the motor chamber 36 is maintained as a predetermined hydrogen gas H2(G) environment.

[0124] At this time, since the first valve V1 is closed, the downstream side of the gas path L1 and the motor chamber 36 become a closed space (gas phase space) of the hydrogen H2 (G) environment. Then, the circulation path LR for the circulation of the hydrogen H2 (G) is formed by the buffer tank T3, the second pipe body L13, the gas inlet 30a, the second motor chamber 36b, the vent 30d, the first motor chamber 36a, the gas outlet 30b and the third pipe body L14. As described above, the hydrogen H2 (G) in the circulation path LR is circulated by the fan 37. In this structure, the hydrogen H2 (G) in the motor chamber 36 is cooled by the liquid hydrogen H2 (L) in the pump chamber 43 via the frame 30, 40 and the rotating shaft 31, and circulates in the circulation path LR, thereby, the hydrogen H2 (G) 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 the temperature in the motor chamber 36 in the first embodiment. Furthermore, since the wind from the fan 37 directly blows to the motor M, the motor M is cooled further than in the first embodiment.

[0125] In the second embodiment, the pump system 1C has the same configuration 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.

[0126] ●Summary(2)●

[0127] 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 the hydrogen gas H2 (G) between the motor room 36 and the buffer tank T3. The frame 30 has a gas outlet 30b that guides the hydrogen gas H2 (G) introduced into the motor room 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 gas H2 (G) introduced into the motor room 36 from the gas inlet 30a is guided from the gas outlet 30b to the third pipe body portion L14, returns to the buffer tank T3, and is introduced into the motor room 36 again via the second pipe body portion L13 and the gas inlet 30a. As a result, the hydrogen gas H2(G) in the motor room 36 is cooled by the liquid hydrogen H2(L) in the pump room 43 and does not stay in the motor room 36, but circulates between the motor room 36 and the buffer tank T3. Therefore, the hydrogen gas H2(G) environment in the motor room 36 and the buffer tank T3 can achieve a better balance of heat and pressure than the first embodiment, and the temperature in the motor room 36 is maintained at a lower temperature than the first embodiment.

[0128] In addition, according to the embodiment described above, the fan 37 is mounted on the rotating shaft 31, and the hydrogen gas H2(G) introduced from the gas inlet 30a flows toward the gas outlet 30b. According to this structure, a special mechanism for accommodating and rotating the fan 37 is not required, and the hydrogen gas H2(G) in the motor room 36 flows easily.

[0129] Moreover, according to the embodiment described above, the fan 37 is mounted on the rear end portion 31b of the rotating shaft 31 in the axial direction of the rotating shaft 31. The frame 30 includes a partition wall 30c, which divides the first motor chamber 36a accommodating the motor M and the second motor chamber 36b accommodating the fan 37. The partition wall 30c includes a vent hole 30d that communicates the first motor chamber 36a with 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 arranged at a position closer to the front end portion 31a than the motor M in the axial direction of the rotating shaft 31. According to this structure, a circulation path LR for circulating hydrogen gas H2(G) is formed by the buffer tank T3, the second pipe body L13, the gas inlet 30a, the second motor chamber 36b, the vent hole 30d, the first motor chamber 36a, the gas outlet 30b and the third pipe body L14. The hydrogen gas H2(G) in the motor room 36 is cooled by the liquid hydrogen H2(L) in the pump room 43 and circulates in the circulation path LR, whereby the gas environment in the circulation path LR is in a state of heat and pressure balance. Therefore, the temperature in the motor room 36 is kept lower than that in the first embodiment. In addition, since the wind from the fan 37 directly blows to the motor M, the motor M is cooled more than in the first embodiment.

[0130] In addition, according to the embodiment described above, the operation method of the pump system 1C 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, a delivery flow path pre-cooling step, and a cycle start step. According to this structure, before the pump device 2A 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). 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 if the pump device 2A starts liquid delivery, the hydrogen H2 (G) environment in the motor chamber 36 will not change drastically, and the pump device 2A can stably deliver liquid hydrogen H2 (L).

[0131] 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 may 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 may not be installed on the rotating shaft 31, but may be installed on a fan rotating shaft (not shown) dedicated to the fan 37. Moreover, for example, the fan 37 may also be provided in the gas path L1 and connected to the second tube body portion L13 or the third tube body portion L14.

[0132] In the second embodiment, the frame body 30 may not include the partition wall 30c.

[0133] Furthermore, in the second embodiment, the positions of the gas inlet 30a and the gas outlet 30b may be any 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.

[0134] Furthermore, in the second embodiment, the pump system 1C may not include the buffer tank T3 .

[0135] ●Modification (2)●

[0136] Next, a modified example of the pump system 1C is described below, focusing on the differences from the second embodiment described previously. In the following description of the modified example, for the sake of convenience, the same reference numerals as those in the second embodiment are used for the same components and components having the same functions as those in the second embodiment. Figure 1 , Figure 2 , Figure 5 and Figure 6 .

[0137] ●First Modification

[0138] Figure 7 This is a schematic piping diagram showing a first modified example of the pump system of the second embodiment.

[0139] The pump system 1D includes a pump device 2A, a first tank T1 , a second 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 .

[0140] In this modified example, a portion of the discharge flow path L4 is installed in the buffer tank T3 in such a manner that heat exchange is performed 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 portion of the discharge flow path L4 function as a heat exchanger that uses the discharge liquid (liquid hydrogen H2 (L)) of the pump device 2A as a refrigerant.

[0141] In this structure, the hydrogen gas H2(G) in the buffer tank T3 is always cooled during the operation of the pump device 2A. Therefore, the effect of suppressing the pressure change by the buffer tank T3 is further improved than that of the second embodiment. In addition, since the hydrogen gas H2(G) in the buffer tank T3 that forms the closed circulation path LR together with the motor chamber 36 is cooled, the increase in temperature and pressure in the motor chamber 36 can be further suppressed.

[0142] ● Second Modification

[0143] Figure 8 This is a schematic piping diagram showing a second modified example of the pump system of the second embodiment.

[0144] The pump system 1E includes a pump device 2A, a first tank T1 , a second 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.

[0145] The heat exchanger HE is installed in the third tube body L14 and the discharge flow path L4, and performs heat exchange between the hydrogen gas H2 (G) in the third tube body L14 and the liquid hydrogen H2 (L) in the discharge flow path L4. That is, the heat exchanger HE uses the discharge liquid (liquid hydrogen H2 (L)) of the pump device 2A as a refrigerant to cool the hydrogen gas H2 (G) in the third tube body L14.

[0146] In this structure, during the operation of the pump device 2A, the hydrogen gas H2 (G) in the third tube body L14 equipped with the heat exchanger HE is always cooled and sent to the buffer tank T3. That is, the hydrogen gas H2 (G) returning from the motor room 36 to the buffer tank T3 is always cooled. Therefore, the same effect as the effect of suppressing the pressure change by using the buffer tank T3 in the first modified example of the second embodiment can be obtained. In addition, since the hydrogen gas H2 (G) in the third tube body L14 that forms the closed circulation path LR together with the motor room 36 is cooled, the increase in temperature and pressure in the motor room 36 can be suppressed as in the first modified example of the second embodiment.

[0147] It should be noted that, in this modification, the heat exchanger HE may also be mounted on the second tube portion L13.

[0148] ●3rd Modification

[0149] Fig. 9 This is a schematic piping diagram showing a third modified example of the pump system of the second embodiment.

[0150] The pump system 1F includes a pump device 2A, a first tank T1 , a second 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 .

[0151] The housing 30 includes a gas inlet 30 a , a gas outlet 30 b , a partition wall 30 c , an outer wall 30 e , and a guide flow path 30 f .

[0152] The outer wall 30e is a shell portion of the frame 30 that divides the motor chamber 36. A portion of the outer wall 30e is a hollow double structure, and forms a guide flow path 30f. That is, the guide flow path 30f is arranged inside the outer wall 30e. In addition, a portion of the outer wall 30e protrudes outward to form a discharge pipe portion 30g. That is, in the third modified example, the discharge pipe portion 30g and the discharge port 30h are arranged on the motor portion 3 side. The discharge pipe portion 30g is connected to the guide flow path 30f.

[0153] Similar to the first embodiment, the suction pipe portion 44 and the suction port 44a are disposed on the pump portion 4 side. The housing 40 includes an outer wall 40a and a guide flow path 40b.

[0154] The outer wall 40a is the outer shell portion of the frame 40 that divides the pump chamber 43. A portion of the outer wall 40a is a hollow double structure and constitutes the guide flow path 40b. That is, the guide flow path 40b is arranged in the outer wall 40a. The guide flow path 40b is connected to the pump chamber 43 and the guide flow path 30f. Therefore, the liquid hydrogen H2 (L) in the pump chamber 43 is transported to the discharge flow path L4 via the guide flow path 40b, the guide flow path 30f, the discharge pipe portion 30g, and the discharge port 30h.

[0155] A portion of the upstream side (gas outlet 30b side) of the third tube portion L14 is mounted on the frame 30, 40 in a manner that enables heat exchange between the hydrogen gas H2 (G) in the third tube portion L14 and the liquid hydrogen H2 (L) in the guide flow paths 30f, 40b. That is, for example, a portion of the third tube portion L14 is arranged in a manner that meanders in the guide flow paths 30f, 40b. As a result, the frame 30, 40 and a portion of the third tube portion L14 (gas path L1) function as a heat exchanger that uses the liquid hydrogen H2 (L) before the pump device 2A is discharged as a refrigerant. A portion of the third tube portion L14 (gas path L1) is an example of a heat exchange path in the present invention.

[0156] In this structure, during the operation of the pump device 2A, the hydrogen gas H2 (G) in the third tube portion L14 is always cooled and sent to the buffer tank T3, as in the second modified example of the second embodiment. That is, the hydrogen gas H2 (G) returning from the motor chamber 36 to the buffer tank T3 is always cooled. Therefore, the same effect as the effect of suppressing pressure changes by using the buffer tank T3 in the first modified example of the second embodiment can be obtained. In addition, since the hydrogen gas H2 (G) in the third tube portion L14 that constitutes the closed circulation path LR together with the motor chamber 36 is cooled, the increase in temperature and pressure in the motor chamber 36 can be suppressed, as in the first modified example of the second embodiment. In addition, since the pump device 2A also functions as a heat exchanger, no additional connection and pipeline for the heat exchanger are required.

[0157] In addition, in this modified example, as long as a portion of the upstream side (gas outlet 30b side) of the third tube L14 is installed in the frame 30, 40 in a manner that enables heat exchange between the hydrogen gas H2 (G) in the third tube L14 and the liquid hydrogen H2 (L) in the guide flow path 30f, 40b, it is not necessary to be arranged in the guide flow path 30f, 40b. That is, for example, a portion of the upstream side (gas outlet 30b side) of the third tube L14 may also be installed on the outer surface of the outer wall 30e, 40a constituting the guide flow path 30f, 40b.

[0158] In addition, in this modification, the gas path L1 may be configured to perform heat exchange between the hydrogen gas H2(G) and the liquid hydrogen H2(L) at other positions other than the guide flow paths 30f and 40b. That is, for example, in this modification, as in the first modification or the second modification of the second embodiment, heat exchange between the hydrogen gas H2(G) and the liquid hydrogen H2(L) may be performed in the buffer tank T3 or the heat exchanger HE. In this case, the guide flow paths 30f and 40b are used to cool the frame 30 (the hydrogen gas H2(G) in the motor room 36).

[0159] ●Other Implementation Methods●

[0160] It should be noted that in the first and second embodiments, the pump systems 1 and 1C only need to include the pump device 2 and 2A and the gas path L1, and the structure of the pump systems 1 and 1C is not limited to the structure described in the first and second embodiments. That is, for example, the pump system of the present invention may be connected to a device including these components without including the first tank T1, the second tank T2, the purge gas path L2, the suction flow path L3, and / or the discharge flow path L4.

[0161] In the first embodiment and the second embodiment, the pump systems 1 and 1C may include, for example, a vacuum pump and a discharge path connected to the gas path L1 .

[0162] Furthermore, in each modification, the buffer tank T3 and the heat exchanger HE functioning as heat exchangers only need to be configured to enable heat exchange between the hydrogen gas 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 the modifications.

[0163] Furthermore, in the first embodiment and the second embodiment, the pump device 2 , 2A may include an inducer disposed on the suction port 44 a side of the impeller 41 .

[0164] Furthermore, in the first embodiment and the second embodiment, during the operation of the pump device 2, the first valve V1 may be opened or closed according to the state (temperature and pressure) in the motor chamber 36. That is, for example, when the temperature (pressure) in the motor chamber 36 rises, the first valve V1 is opened, and when the temperature (pressure) decreases (balances), the first valve V1 is closed.

[0165] In the first embodiment and the second embodiment, the motor M may be a permanent magnet motor having a permanent magnet in the rotor 34. In this case, the pump device 2, 2A includes a protective member (for example, a stainless steel protective member) that covers the rotor 34 and isolates the rotor 34 from the hydrogen gas H2(G). According to this structure, embrittlement of the permanent magnet caused by the hydrogen gas H2(G) can be prevented.

[0166] In addition, in the first embodiment, the second embodiment and each modified example, the structure of each tube and each valve can be any structure as long as it can introduce the hydrogen gas H2(G) from the gas phase part T1G into the motor chamber 36 and can introduce the liquid hydrogen H2(L) from the liquid phase part T1L into the pump chamber 43, and is not limited to the structure described in the first embodiment, the second embodiment and each modified example.

[0167] Furthermore, the structures of the first embodiment, the second embodiment, and the modifications may be combined with each other.

[0168] ●Embodiments of the present invention●

[0169] Next, the terms and reference numerals described in each embodiment are cited, and embodiments of the present invention understood from the embodiments described above are described below.

[0170] The first embodiment of the present invention is a pump device (e.g., pump device 2, 2A), which is connected to a tank (e.g., first 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, wherein the pump device comprises: a rotating shaft (e.g., rotating shaft 31); a motor (e.g., motor M) that rotates the rotating shaft; an impeller (e.g., impeller 41) that is mounted on one end portion (e.g., front end portion 31a) of the rotating shaft in the axial direction of the rotating shaft; and a frame. A body (e.g., frame 30, 40) having 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) mounted on the rotating shaft and the frame to seal the motor chamber relative to the pump chamber, the motor comprising: a rotor (e.g., rotor 34) mounted on the rotating shaft; and a stator (e.g., stator 35) directly opposed to the rotor in the radial direction of the rotating shaft and causing the rotor to rotate, and the hydrogen is introduced into the motor chamber.

[0171] According to this structure, the pump device realizes no leakage of hydrogen (liquid hydrogen and hydrogen gas) while using a mechanical seal, and can adapt to operations from low-speed rotation to high-speed rotation.

[0172] The second embodiment of the present invention is a pump device according to the first embodiment, wherein the frame has a gas inlet port (e.g., gas inlet port 30a) connected to a gas path (e.g., gas path L1), the gas path (e.g., gas path L1) is connected to a gas phase portion (e.g., gas phase portion T1 G) storing the hydrogen gas in the storage tank, and the hydrogen gas is introduced into the motor room via the gas inlet port.

[0173] According to this structure, since the motor chamber is connected to the gas phase portion via the gas path, hydrogen gas does not leak to the external environment of the pump system.

[0174] The third embodiment of the present invention is a pump device (for example, pump device 2A) according to the second embodiment, wherein the frame comprises: an outer wall (for example, outer wall 30e, 40a), which divides the pump chamber and the motor chamber from the external environment of the frame; an intake port (for example, intake port 44a), which is arranged on the pump chamber side of the frame and sucks the liquid hydrogen from the storage tank into the pump chamber; an exhaust port (for example, exhaust port 45a), which is arranged on the motor chamber side of the frame and discharges the liquid hydrogen from the pump chamber; and a guide flow path (for example, guide flow paths 30f, 40b), which is arranged inside the outer wall and guides the liquid hydrogen from the pump chamber to the exhaust port.

[0175] According to this configuration, the housing (hydrogen gas in the motor chamber) is cooled by the liquid hydrogen guided in the guide flow path.

[0176] The fourth embodiment of the present invention is a pump device according to the third embodiment, wherein the pump device has a heat exchange path that constitutes a part of the gas path, and the heat exchange path is configured in a manner capable of performing heat exchange between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guide flow path.

[0177] According to this structure, during the operation of the pump device, the hydrogen gas in the third tube portion is always cooled and sent to the buffer tank. Therefore, the effect of suppressing pressure changes by the buffer tank is improved.

[0178] The fifth embodiment of the present invention is a pump device according to any one of the second to fourth embodiments, wherein the pump device has a fan (for example, fan 37) arranged in the motor room, the frame has a gas outlet (for example, gas outlet 30b) for discharging the hydrogen gas introduced into the motor room to the gas path, and the fan causes the hydrogen gas introduced into the motor room from the gas inlet to flow toward the gas outlet.

[0179] According to this structure, the hydrogen in the motor room is cooled by the liquid hydrogen in the pump room and circulates without being retained in the motor room. As a result, the heat and pressure of the hydrogen in the motor room and the buffer tank are balanced, and the temperature in the motor room is kept low.

[0180] The sixth embodiment of the present invention is a pump device according to the first embodiment, wherein the motor is a permanent magnet motor in which the rotor (for example, the rotor 34) has a permanent magnet, and the pump device has a protective component that covers the rotor and isolates the rotor from the hydrogen gas.

[0181] According to this structure, embrittlement of the permanent magnet due to hydrogen can be prevented.

[0182] The seventh embodiment of the present invention is a pump system (e.g., pump system 1, 1A, 1B, 1C, 1D, 1D, 1F) that is connected to a tank (e.g., first 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, wherein the pump system comprises: a pump device (e.g., pump device 2, 2A) that sucks in 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 T1) in the tank storing the hydrogen gas. G), the pump device comprises: a rotating shaft (for example, the rotating shaft 31); a motor (for example, the motor M), which rotates the rotating shaft; an impeller (for example, the impeller 41), which is installed at one end (for example, the front end 31a) of the rotating shaft in the axial direction of the rotating shaft; a frame (for example, the frame 30, 40), which has a motor chamber (for example, the motor chamber 36) for accommodating the motor and a pump chamber (for example, the pump chamber 43) for accommodating the impeller; and a mechanical seal (for example, the mechanical seal 42), which is installed on the rotating shaft and the frame and seals the motor chamber relative to the pump chamber, the motor comprises: a rotor (for example, the rotor 34), which is installed on the rotating shaft; and a stator (for example, the stator 35), which is directly opposite to the rotor in the radial direction of the rotating shaft and rotates the rotor, the frame comprises a gas inlet (for example, the gas inlet 30a) connected to the gas path, and the hydrogen gas is introduced into the motor chamber via the gas path and the gas inlet.

[0183] According to this configuration, the pump system realizes no leakage of hydrogen while using a pump device equipped with a mechanical seal, and can accommodate the transportation of liquid hydrogen at speeds ranging from low to high.

[0184] The eighth embodiment of the present invention is a pump system according to the seventh embodiment (for example, pump systems 1A, 1B, 1C, 1D, 1D, 1F), wherein the gas path comprises: a buffer tank (for example, buffer tank T3) which temporarily stores the hydrogen gas; a first gas path (for example, first tube body L12) which is connected to the buffer tank and the gas phase portion; a second gas path (for example, second tube body L13) which is connected to the buffer tank and the gas inlet port; and an opening and closing valve (for example, first valve V1) which is connected to the first gas path to open and close the first gas path.

[0185] According to this structure, even if the pressure in the motor chamber changes due to local heat from the bearing or stator during the operation of the pump system, the change is suppressed by the hydrogen stored in the buffer tank. In addition, even if the temperature of the hydrogen in the motor chamber rises due to the local heat, the increase in the temperature of the hydrogen in the gas path and the motor chamber can be suppressed.

[0186] The ninth embodiment of the present invention is a pump system according to the eighth embodiment (for example, pump systems 1B, 1D, 1E, 1F), wherein the pump system comprises: a discharge flow path (for example, discharge flow path L4) connected to a discharge port (for example, discharge port 45a) provided on the frame for discharging the liquid hydrogen from the pump chamber; and a heat exchanger (for example, buffer tank T3, heat exchanger HE) for performing heat exchange between the hydrogen gas in the gas path and the liquid hydrogen in the discharge flow path.

[0187] According to this configuration, even if the temperature of the hydrogen gas in the motor chamber rises due to local heat, the increase in the temperature of the hydrogen gas in the gas path and the motor chamber can be suppressed.

[0188] The tenth embodiment of the present invention is a pump system according to the ninth embodiment (for example, pump system 1B, 1D), wherein the discharge flow path is configured in a manner capable of performing heat exchange 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.

[0189] According to this structure, the hydrogen gas in the buffer tank is always cooled during the operation of the pump device. As a result, the increase in temperature and pressure in the gas path and the motor room can be further suppressed.

[0190] The 11th embodiment of the present invention is a pump system (for example, pump system 1F) according to the 7th embodiment, wherein the frame comprises: an outer wall (for example, outer wall 30e, 40a) which divides the pump chamber and the motor chamber respectively; a suction port which is arranged on the pump chamber side of the frame and sucks the liquid hydrogen from the storage tank into the pump chamber; a discharge port which is arranged on the motor chamber side of the frame and discharges the liquid hydrogen from the pump chamber; and a guide flow path (for example, guide flow paths 30f, 40b) which is arranged inside the outer wall and guides the liquid hydrogen from the pump chamber to the discharge port.

[0191] According to this configuration, the housing (hydrogen gas in the motor chamber) is cooled by the liquid hydrogen guided in the guide flow path.

[0192] The twelfth embodiment of the present invention is a pump system according to the eleventh embodiment, wherein the gas path includes a heat exchange path installed in the pump device, and the heat exchange path is configured in a manner capable of performing heat exchange between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guide flow path.

[0193] According to this structure, during the operation of the pump device, the hydrogen gas in the third tube portion is always cooled and sent to the buffer tank. Therefore, the effect of suppressing pressure changes by the buffer tank is improved.

[0194] The 13th embodiment of the present invention is a pump system according to any one of the 7th to 12th embodiments, wherein the pump system has a fan (for example, fan 37) for circulating the hydrogen gas between the motor chamber and the gas path, the frame 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 (for example, the third tube portion L14) connected to the gas outlet.

[0195] According to this structure, the hydrogen in the motor room is cooled by the liquid hydrogen in the pump room and circulates without being retained in the motor room. As a result, the heat and pressure of the hydrogen in the motor room and the buffer tank are balanced, and the temperature in the motor room is kept low.

[0196] A fourteenth aspect of the present invention is the pump system according to the thirteenth aspect, wherein the fan is attached to the rotating shaft and causes the hydrogen gas introduced from the gas inlet to flow toward the gas outlet.

[0197] According to this structure, a special mechanism for accommodating and rotating the fan is not required, and the hydrogen gas in the motor chamber flows easily.

[0198] The 15th embodiment of the present invention is a pump system according to the 14th embodiment, wherein the fan is mounted on the other end portion (e.g., the rear end portion 31b) of the rotating shaft in the axial direction, the frame (e.g., the frame 30) has a partition wall (e.g., the partition wall 30c) which divides a first motor chamber (e.g., the first motor chamber 36a) accommodating the motor and a second motor chamber (e.g., the second motor chamber 36b) accommodating the fan, the partition wall has a vent hole (e.g., the vent hole 30d) which connects the first motor chamber with the second motor chamber, the gas inlet port opens in the second motor chamber, the gas outlet port opens in the first motor chamber, and is arranged in the axial direction at a position closer to the one end side than the motor.

[0199] According to this structure, a circulation path for circulating hydrogen gas 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, whereby the gas environment in the circulation path is in a state of thermal and pressure balance.

[0200] The 16th embodiment of the present invention is a pump system according to the 7th embodiment, wherein the pump system comprises: a purge gas path (e.g., a purge gas path L2), which is connected to a purge gas tank (e.g., a second storage tank T2) and the gas path, the purge gas tank (e.g., the second storage tank T2) stores a purge gas (e.g., helium He(G)) for purging the hydrogen gas introduced into the motor room; and a switching part (e.g., a first valve V1, a second valve V2), which switches the gas introduced into the motor room between the purge gas and the hydrogen gas.

[0201] According to this structure, during maintenance of the pump device, hydrogen, which is a combustible gas, does not leak to the external environment, and the pump device can be safely disassembled and disassembled.

[0202] The 17th embodiment of the present invention is a method for operating a pump system (e.g., pump system 1, 1A, 1B, 1C, 1D, 1E, 1F), which is connected to a tank (e.g., first tank T1) storing liquid hydrogen (e.g., liquid hydrogen) and hydrogen gas (e.g., hydrogen gas) vaporized from the liquid hydrogen, and transports the liquid hydrogen, wherein the pump system comprises: a pump device (e.g., pump device 2, 2A) that sucks in 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 T1) in the tank storing the hydrogen gas. G), the pump device comprises: a rotating shaft (for example, the rotating shaft 31); a motor (for example, the motor M), which rotates the rotating shaft; an impeller (for example, the impeller 41), which is installed at one end of the rotating shaft (for example, the front end 31a) in the axial direction of the rotating shaft; a frame (for example, the frame 30, 40), which has a motor chamber (for example, the motor chamber 36) for accommodating the motor and a pump chamber (for example, the pump chamber 43) for accommodating the impeller; and a mechanical seal (for example, the mechanical seal 42), which is installed on the rotating shaft and the frame, relative to the The pump chamber seals the motor chamber, and the motor comprises: a rotor (for example, rotor 34) mounted on the rotating shaft; and a stator (for example, stator 35) directly opposite to the rotor in the radial direction of the rotating shaft and causing the rotor to rotate. The operating method of the pump system includes: a pre-preparation step, preparing until the pump device is capable of liquid transportation; and a step of discharging the liquid hydrogen from the pump chamber, the pre-preparation step including: 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.

[0203] According to this configuration, in a pump device including a mechanical seal, it is possible to prevent hydrogen from leaking and to achieve stable transport of liquid hydrogen from a low-speed rotation to a high-speed rotation.

[0204] Description of Reference Numerals

[0205] 1: Pump System (First Embodiment)

[0206] 1A: Pump System (First Modification of First Embodiment)

[0207] 1B: Pump System (Second Modification of First Embodiment)

[0208] 1C: Pump system (Second embodiment)

[0209] 1D: Pump System (First Modification of Second Embodiment)

[0210] 1E: Pump System (Second Modification of Second Embodiment)

[0211] 1F: Pump System (Third Modification of Second Embodiment)

[0212] 2: Pump device (first embodiment)

[0213] 2A: Pump Device (Second Embodiment)

[0214] 3: Motor

[0215] 30:Frame

[0216] 30a: Gas inlet

[0217] 30b: Gas outlet

[0218] 30c: partition wall

[0219] 30d: vent

[0220] 30e:Outer wall

[0221] 30f: Guide flow path

[0222] 31: Rotation axis

[0223] 31a: front end (one end)

[0224] 31b: rear end (other end)

[0225] 34: Rotor

[0226] 35: Stator

[0227] 36: Motor room

[0228] 36a: No. 1 motor room

[0229] 36b: Second motor room

[0230] 4: Pump

[0231] 40:Frame

[0232] 40a:Outer wall

[0233] 40b: guiding flow path

[0234] 41: Impeller

[0235] 42: Mechanical seal

[0236] 43: Pump room

[0237] HE:Heat exchanger

[0238] L1: Gas path

[0239] L11: Pipe body part

[0240] L12: 1st tube body (1st gas path)

[0241] L13: Second tube part (second gas path)

[0242] L14: 3rd tube part (3rd gas path)

[0243] L2: Purge gas path

[0244] L3: Suction flow path

[0245] L4: discharge flow path

[0246] T1: Tank 1 (storage tank)

[0247] T1 G: Gas phase

[0248] T2: Second storage tank (purge gas tank)

[0249] T3: Buffer tank (buffer tank, heat exchanger)

[0250] V1: Valve 1 (opening and closing valve, switching part)

[0251] V3: Valve 3 (Switch)

Claims

1. A pump device connected to a tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and transporting the liquid hydrogen, wherein: The pump device comprises: Axis of rotation; a motor that rotates the rotating shaft; an impeller mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame 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 frame to seal the motor chamber relative to the pump chamber, The motor has: a rotor mounted on the rotating shaft; and a stator which is directly opposed to the rotor in the radial direction of the rotating shaft and causes the rotor to rotate, The hydrogen gas is introduced into the motor chamber.

2. The pump device according to claim 1, wherein The frame body has a gas inlet connected to a gas path, and the gas path is connected to a gas phase portion storing the hydrogen gas in the tank. The hydrogen gas is introduced into the motor chamber through the gas introduction port.

3. The pump device according to claim 2, wherein: The frame has: An outer wall, which divides the pump chamber and the motor chamber from the external environment of the frame; a suction port disposed on the pump chamber side of the frame body and sucking the liquid hydrogen from the tank into the pump chamber; a discharge port disposed on the motor chamber side of the frame body and discharging the liquid hydrogen from the pump chamber; and A guide flow path is disposed in 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 formed as a part of the gas path, The heat exchange path is arranged so as to enable heat exchange between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guide flow path.

5. The pump device according to any one of claims 2 to 4, wherein: The pump device includes a fan disposed in the motor room. The frame body includes a gas outlet for outlet 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 introduction port to flow toward the gas outlet port.

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

7. A pump system connected to a tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and transporting the liquid hydrogen, wherein: The pump system has: a pump device that sucks in and discharges the liquid hydrogen; and a gas path connected to a gas phase portion storing the hydrogen in the storage tank, The pump device comprises: Axis of rotation; a motor that rotates the rotating shaft; an impeller mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame 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 frame to seal the motor chamber relative to the pump chamber, The motor has: a rotor mounted on the rotating shaft; and a stator which is directly opposed to the rotor in the radial direction of the rotating shaft and causes the rotor to rotate, The frame body includes a gas inlet connected to the gas path. The hydrogen gas is introduced into the motor chamber through the gas path and the gas introduction port.

8. The pump system of claim 7, wherein: The gas path comprises: a buffer tank for temporarily storing the hydrogen; a first gas path connected to the buffer tank and the gas phase portion; a second gas path connected to the buffer tank and the gas inlet; and The on-off valve is connected to the first gas path and opens and closes the first gas path.

9. The pump system of claim 8, wherein: The pump system has: a discharge flow path connected to a discharge port provided on the frame body and discharging the liquid hydrogen from the pump chamber; and A heat exchanger performs heat exchange between the hydrogen gas in the gas path and the liquid hydrogen in the exhaust flow path.

10. The pump system of claim 9, wherein: The exhaust flow path is arranged so as to enable heat exchange between the liquid hydrogen flowing in the exhaust flow path and the hydrogen gas in the buffer tank. The buffer tank functions as the heat exchanger.

11. The pump system of claim 7, wherein: The frame has: An outer wall, which divides the pump chamber and the motor chamber respectively; a suction port disposed on the pump chamber side of the frame body and sucking the liquid hydrogen from the tank into the pump chamber; a discharge port disposed on the motor chamber side of the frame body and discharging the liquid hydrogen from the pump chamber; and A guide flow path is disposed in the outer wall and guides the liquid hydrogen from the pump chamber to the discharge port.

12. The pump system of claim 11, wherein: The gas path includes a heat exchange path installed in the pump device, The heat exchange path is arranged so as to enable heat exchange between the hydrogen gas in the heat exchange path and the liquid hydrogen in the guide flow path.

13. A 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 frame body includes a gas outlet for outlet the hydrogen gas introduced into the motor chamber to the gas path. The gas path includes a third gas path connected to the gas outlet.

14. The pump system of claim 13, wherein: The fan is attached to the rotating shaft and allows the hydrogen gas introduced from the gas inlet to flow toward the gas outlet.

15. The pump system of claim 14, wherein: The fan is mounted on the other end of the rotating shaft in the axial direction. The frame body includes a partition wall that divides a first motor room that accommodates the motor and a second motor room that accommodates the fan. The partition wall has a vent hole that allows the first motor chamber to communicate with the second motor chamber. The gas inlet is opened in the second motor chamber, The gas outlet opens in the first motor chamber and is arranged at a position closer to the one end side than the motor in the axial direction.

16. The pump system of claim 7, wherein: The pump system has: 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 gas introduced into the motor room; and A switching unit switches the gas introduced into the motor chamber between the purge gas and the hydrogen gas.

17. A method for operating a pump system, wherein the pump system is connected to a storage tank storing liquid hydrogen and hydrogen gas vaporized from the liquid hydrogen, and delivers the liquid hydrogen, wherein: The pump system comprises: a pump device that sucks in and discharges the liquid hydrogen; and a gas path connected to a gas phase portion storing the hydrogen in the storage tank, The pump device comprises: Axis of rotation; a motor that rotates the rotating shaft; an impeller mounted on one end of the rotating shaft in the axial direction of the rotating shaft; a frame 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 frame to seal the motor chamber relative to the pump chamber, The motor has: a rotor mounted on the rotating shaft; and a stator which is directly opposed to the rotor in the radial direction of the rotating shaft and causes the rotor to rotate, The method for operating the pump system comprises: a pre-preparation step of preparing until the pump device is capable of delivering liquid; and the step of discharging the liquid hydrogen from the pump chamber, The preparatory steps include: The step of introducing the liquid hydrogen into the pump chamber; and The step of introducing the hydrogen gas into the motor chamber via the gas path.

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