Liquefied gas pump

Abstract

This liquefied gas pump comprises: a rotary shaft that has a rotary shaft body extending in an axial direction, a thrust collar protruding from the rotary shaft body toward the outer peripheral side, and a flange part protruding from the rotary shaft body at an axial position different from that of the thrust collar; an impeller provided on the rotary shaft and capable of rotating together with the rotary shaft to pump a low-temperature liquid; an electric motor for rotationally driving the rotary shaft around the axis; a starting bearing on which the flange part is placed from above when the rotary shaft is stopped, and which rotatably supports the flange part, and from which the flange part is separated upward when the rotary shaft is rotated; and a thrust bearing which faces the thrust collar from below with a clearance therebetween when the rotary shaft is stopped, and which supports the thrust collar with fluid pressure when the rotary shaft is rotated.

Description

Liquefied gas pump

[0001] This disclosure relates to a liquefied gas pump. This application claims priority to Japanese Patent Application No. 2024-163889 filed in Japan on September 20, 2024, the content of which is incorporated herein by reference.

[0002] As a pump for boosting the pressure of a liquid, there is a vertical type rotary pump. For example, Patent Document 1 discloses a technique for simplifying the structure, improving the reliability, and enhancing the efficiency of a pump for liquefied gas used in a low-temperature environment.

[0003] Japanese Patent Application Laid-Open No. 2006-170046

[0004] By the way, when a hydrostatic sliding bearing is used as a thrust bearing in a pump whose rotating shaft extends in the vertical direction, some contrivance is required during startup and shutdown of the pump. That is, in the case of a configuration in which the hydrostatic pressure is supplied to the hydrostatic sliding bearing from the impeller, the hydrostatic pressure is not supplied during startup and shutdown. Therefore, at the location where the rotating shaft is supported in the vertical direction, the hydrostatic pressure is not stably supplied and friction occurs. As a result, the thrust bearing may be worn out.

[0005] This disclosure provides a liquefied gas pump capable of suppressing wear of the thrust bearing during startup and shutdown.

[0006] The liquefied gas pump according to this disclosure includes a rotating shaft body extending in the axial direction, a thrust collar protruding from the rotating shaft body to the outer peripheral side, and a flange portion protruding from the rotating shaft body at an axial position different from the thrust collar, an impeller provided on the rotating shaft and capable of pumping a low-temperature liquid by rotating together with the rotating shaft, an electric motor for rotationally driving the rotating shaft around its axis, a startup bearing that supports the flange portion rotatably with the flange portion placed thereon from above when the rotating shaft stops, and the flange portion being spaced apart upward when the rotating shaft rotates, and a thrust bearing that faces the thrust collar from below through a clearance when the rotating shaft stops and supports the thrust collar through fluid pressure when the rotating shaft rotates.

[0007] The liquefied gas pump of this disclosure provides a liquefied gas pump that can suppress wear of the thrust bearing during startup and shutdown.

[0008] This is a schematic diagram showing the entire liquefied gas pump according to the embodiment of this disclosure. This is an enlarged view of the main part showing the liquefied gas pump according to the embodiment of this disclosure when it is stopped. This is an enlarged view of the main part showing the liquefied gas pump according to the embodiment of this disclosure when it is rotating.

[0009] <Embodiment> Hereinafter, a liquefied gas pump 1 according to an embodiment of this disclosure will be described in detail with reference to Figures 1 to 3.

[0010] <Liquefied Gas Pump> As shown in Figure 1, the liquefied gas pump 1 is positioned so as to be suspended inside the sump 50. The liquefied gas pump 1 is a device for pressurizing a cryogenic liquid as a fluid. In this embodiment, the liquefied gas pump 1 for pressurizing liquid hydrogen will be described. Note that the fluid is not limited to liquid hydrogen, but may be other liquids or gases. For example, liquefied natural gas (LNG) is one example.

[0011] The sump 50 is capable of storing liquid. In this embodiment, the sump 50 is capable of storing liquid hydrogen. The sump 50 is a vacuum-insulated container. That is, the sump 50 is an insulated structure with a bottomed cylindrical shape. The sump 50 has a liquid storage chamber 53 formed inside it. The liquid storage chamber 53 is capable of storing liquid hydrogen. The sump 50 has an outer circumferential flange 51 provided on its upper vertical side. The sump 50 is installed on a stand (not shown). The sump 50 has an upper flange 52 provided on its upper vertical side. The upper flange 52 is provided vertically above the outer circumferential flange 51. The upper flange 52 and the outer circumferential flange 51 are arranged in contact with each other. The upper flange 52 and the outer circumferential flange 51 are connected, for example, via bolts. The upper flange 52 is positioned to maintain airtightness of the sump 50. Furthermore, the upper flange 52 can be installed in such a way as to suspend the liquefied gas pump 1.

[0012] The sump 50 has a supply pipe 60 and a gas discharge pipe 61 connected to its side. The supply pipe 60 is a pipe that allows liquid hydrogen to be supplied to the liquid storage chamber 53 from an external source. The gas discharge pipe 61 is a pipe that allows vaporized hydrogen from the liquid storage chamber 53 to be discharged to the outside of the sump 50. The gas discharge pipe 61 is located vertically above the supply pipe 60. The gas discharge pipe 61 may also be capable of discharging liquid hydrogen to the outside of the sump 50, as well as vaporized hydrogen.

[0013] The liquefied gas pump 1 is located inside the sump 50. The liquefied gas pump 1 comprises a casing 10, a rotating shaft 20, an electric motor 30, an inducer 24, an impeller 25, and a bearing device 40.

[0014] <Casing> The casing 10 forms the outer shell of the liquefied gas pump 1. The casing 10 has a hollow shape. The casing 10 may be composed of a single component, or it may be composed of multiple components assembled together. The casing 10 is capable of housing the electric motor 30, inducer 24, impeller 25, and bearing device 40 inside. The upper end of the casing 10 is connected to the upper flange 52 and suspended and supported inside the sump 50. The casing 10 has a cylindrical shape centered on an axis O that extends in the vertical direction, but is not limited to this. In addition, although both the sump 50 and the casing 10 spread out from the axis O, the centers of the sump 50 and the casing 10 may be offset from each other.

[0015] The casing 10 has a suction section 11 at its lower end. The suction section 11 is formed to communicate with the liquid storage chamber 53. Liquid hydrogen stored in the liquid storage chamber 53 can flow through the suction section 11. The casing 10 also has a discharge section 12 at its upper end. The discharge section 12 is connected to a discharge pipe 62 that extends to the outside of the sump 50. The suction section 11 may also be directly connected to piping extended from the supply pipe 60 or the like. In other words, liquid hydrogen may be introduced directly from the piping to the suction section 11 without first being stored in the liquid storage chamber 53.

[0016] <Rotational shaft> The rotational shaft 20 is a rod-shaped member extending along the axis O. The rotational shaft 20 and the casing 10 are arranged concentrically with respect to the axis O. The rotational shaft 20 is supported by a bearing device 40 so as to be rotatable around the axis O relative to the casing 10. Hereinafter, the radial direction of the rotational shaft 20 will be simply referred to as the radial direction, and the circumferential direction of the rotational shaft 20 will be simply referred to as the circumferential direction. The direction in which the axis O extends will be referred to as the axial direction. The inducer 24, the impeller 25, and the rotor 36 of the electric motor 30 are fixed to the rotational shaft 20. The rotational shaft 20 also has a rotational shaft body 21, a thrust collar 22, and a flange portion 23.

[0017] The rotating shaft body 21 is a rod-shaped member extending along the axis O. The rotating shaft body 21 is fixed to the thrust collar 22 and flange portion 23 by connection. The thrust collar 22 is fixed to the outer circumference of the rotating shaft body 21. The thrust collar 22 is disc-shaped and is provided to expand the diameter of the rotating shaft body 21 in the radial direction while fixed to the rotating shaft body 21. In other words, the thrust collar 22 is provided to protrude outward from the rotating shaft body 21. The thrust collar 22 is rotatable integrally with the rotating shaft body 21. Furthermore, the thrust collar 22 is movable integrally with the rotating shaft body 21 in the axial direction. The thrust collar 22 has an upper surface 22A facing upward in the axial direction and a lower surface 22B facing downward. Note that the rotating shaft body 21 and the thrust collar 22 may be molded as a single unit or molded separately and then connected.

[0018] The flange portion 23 is fixed to the outer circumference of the rotating shaft body 21. The flange portion 23 is located at a different axial position from the thrust collar 22. In this embodiment, the flange portion 23 is located at the upper end of the rotating shaft body 21 in the axial direction. The flange portion 23 is disc-shaped and is provided to expand the diameter of the rotating shaft body 21 in the radial direction while fixed to the rotating shaft body 21. In other words, the flange portion 23 is provided to protrude outward from the rotating shaft body 21. The flange portion 23 is rotatable together with the rotating shaft body 21. Furthermore, the flange portion 23 is movable together with the rotating shaft body 21 in the axial direction. Note that the rotating shaft body 21 and the flange portion 23 may be molded as a single unit or molded separately and then connected.

[0019] <Bearing Device> The bearing device 40 is a component that supports the rotating shaft 20 so that it can rotate around axis O relative to the casing 10. The bearing device 40 is fixedly installed inside the casing 10. The bearing device 40 includes a radial bearing 41, a thrust bearing 44, and a starting bearing 45.

[0020] The radial bearing 41 is positioned to receive the radial load of the rotating shaft 20. That is, the radial bearing 41 is positioned concentrically with the rotating shaft 20 and is provided to cover the rotating shaft 20 from its outer circumferential surface. Multiple radial bearings 41 are provided. In this embodiment, a first radial bearing 42 and a second radial bearing 43 are provided. The first radial bearing 42 is positioned vertically above the casing 10. The second radial bearing 43 is positioned vertically below the casing 10. The radial bearing 41 in this embodiment is a sliding bearing, but the type is not limited. For example, the radial bearing 41 may be a rolling bearing. Also, the first radial bearing 42 and the second radial bearing 43 may be bearings of the same type, or they may be bearings of different types.

[0021] The thrust bearing 44 is positioned to withstand the axial load of the rotating shaft 20. The thrust bearing 44 is provided to sandwich the thrust collar 22 in the axial direction. As shown in Figure 2, the thrust bearing 44 is provided so as not to come into contact with the thrust collar 22 in the axial direction when the rotating shaft 20 is stopped. In other words, the thrust bearing 44 is provided to face the thrust collar 22 from below in the axial direction with a clearance when the rotating shaft 20 is stopped. The thrust bearing 44 in this embodiment is a hydrostatic bearing. The thrust bearing 44 is provided so as to be able to support the thrust collar 22 in the axial direction via fluid pressure when the rotating shaft 20 is rotating.

[0022] Furthermore, the thrust bearing 44 is positioned vertically above the first radial bearing 42 and the second radial bearing 43. However, the position of the thrust bearing 44 is not limited to this. The thrust bearing 44 may be positioned between the first radial bearing 42 and the second radial bearing 43, or vertically below the first radial bearing 42 and the second radial bearing 43.

[0023] The starting bearing 45 is positioned to receive the axial load of the rotating shaft 20. The starting bearing 45 is positioned to receive the flange portion 23. The starting bearing 45 is designed so that the flange portion 23 can be placed on it from above in the axial direction when the rotating shaft 20 is stopped. The starting bearing 45 is designed to rotatably support the flange portion 23. In other words, the starting bearing 45 is provided so that it contacts the flange portion 23 in the axial direction when the rotating shaft 20 is stopped. The starting bearing 45 is provided so that the flange portion 23 is spaced apart upward in the axial direction when the rotating shaft 20 is rotating. The starting bearing 45 is, for example, a rolling bearing, but is not limited to this.

[0024] Furthermore, a lubricating layer is formed on the starting bearing 45 over the circumferential direction of the surface facing upward in the axial direction. That is, the starting bearing 45 is formed to abut the flange portion 23 via the lubricating layer. The lubricating layer contains a solid lubricant. The lubricating layer is a component that reduces the coefficient of friction at the contact surface between the starting bearing 45 and the flange portion 23. Note that the lubricating layer may not be formed.

[0025] <Inducer and Impeller> The inducer 24 and impeller 25 are provided so as to be able to pump liquid hydrogen as the rotating shaft 20 rotates. The inducer 24 and impeller 25 are fixed to the rotating shaft 20 and are provided as a single unit. The inducer 24 and impeller 25 are rotatable together with the rotating shaft 20. In addition, the inducer 24 and impeller 25 are movable together with the rotating shaft 20 in the axial direction. Multiple impellers 25 are provided and are spaced apart in the axial direction. The impeller 25 includes a first-stage impeller 26, a second-stage impeller 27, and a third-stage impeller 28. Note that the number of impellers 25 is not limited to three. The number of impellers 25 may be two or fewer, or four or more.

[0026] The inducer 24 is located at the lower end of the rotating shaft 20. The first stage impeller 26 is provided integrally with the inducer 24. Specifically, the first stage impeller 26 is located axially above the inducer 24. The inducer 24 and the first stage impeller 26 are located in the suction section 11 of the casing 10. The second stage impeller 27 and the third stage impeller 28 are located axially above the first stage impeller 26. Specifically, the second stage impeller 27 and the third stage impeller 28 are located axially above the first stage impeller 26, sandwiching the second radial bearing 43. Note that the inducer 24 is not required.

[0027] <Electric Motor> The electric motor 30 is a component for rotating the rotating shaft 20 around the axis O. The electric motor 30 is installed inside the casing 10. The electric motor 30 has a rotor 36 and a stator 31.

[0028] The rotor 36 is a component that receives power to rotate the rotating shaft 20 around axis O and rotates the rotating shaft 20. The rotor 36 is integrally fixed to the rotating shaft 20. Specifically, the rotor 36 is fixed to the outer circumferential surface of the rotating shaft 20. The rotor 36 has a rotor core 38 and permanent magnets.

[0029] The rotor core 38 is arranged concentrically with the rotating shaft 20. The rotor core 38 is provided inside the stator 31, with a clearance between it and the stator 31. The rotor core 38 has an overall cylindrical shape that extends in the axial direction. The rotor core 38 is fixedly provided on the outer circumferential surface of the rotating shaft body 21. The rotor core 38 is made of multiple layers of electromagnetic steel sheets stacked in the axial direction. Multiple permanent magnets are provided inside the rotor core 38, spaced apart in the circumferential direction. In addition, the rotor core 38 may have a support member provided on its outer circumferential surface.

[0030] The stator 31 is fixed to the inner circumferential surface of the casing 10. The stator 31 is arranged concentrically with the rotating shaft 20 and the rotor 36. The stator 31 is cylindrical in shape. The stator 31 is arranged to surround the rotating shaft 20 and the rotor 36 from the radially outer side. In other words, the stator 31 is facing the rotor 36 with a radial gap between them. The stator 31 has a stator core 32 and a coil 35.

[0031] The stator core 32 has a yoke and teeth. The yoke is cylindrical with an axis O. The yoke is fixed to the inner surface of the casing 10 with its outer surface fixed thereto. The teeth are provided so as to protrude from the inner surface of the yoke. Multiple teeth are formed, spaced apart from each other in the circumferential direction. Multiple coils 35 are provided, corresponding to each tooth. The coils 35 are wound around each tooth. Therefore, multiple coils 35 are provided, spaced apart in the circumferential direction.

[0032] <Pump Operation> When the pump is not in operation (stopped), it is arranged as shown in Figure 2. Specifically, the thrust collar 22 and thrust bearing 44 are arranged so that they do not come into contact with each other in the axial direction. On the other hand, the flange portion 23 and starting bearing 45 are arranged so that they come into contact with each other in the axial direction. When the electric motor 30 is driven, the rotating shaft 20 rotates. The inducer 24 and impeller 25 fixed to the rotating shaft body 21 rotate, causing the liquefied gas pump 1 to operate.

[0033] When the liquefied gas pump 1 is activated, the liquid hydrogen in the liquid storage chamber 53 is drawn into the suction section 11 by the inducer 24. The drawn-in liquid hydrogen is pressurized by one stage by the first-stage impeller 26. The pressurized liquid hydrogen is supplied to the second-stage impeller 27 through the flow path 70 provided in the casing 10. The liquid hydrogen is pressurized by two stages by the second-stage impeller 27. The pressurized liquid hydrogen is supplied to the third-stage impeller 28 through the flow path 71 provided in the casing 10. The liquid hydrogen is pressurized by three stages by the third-stage impeller 28. The pressurized liquid hydrogen is supplied to the discharge section 12 through the flow path 72 provided in the casing 10. The liquid hydrogen supplied to the discharge section 12 is discharged to the outside of the sump 50 from the discharge pipe 62. Furthermore, it is preferable that multiple flow paths 70, 71, and 72 are provided radially outside the impeller 25, spaced apart in the circumferential direction. In addition, other paths through which liquid hydrogen flows may be provided besides the above-mentioned flow paths 70, 71, and 72.

[0034] Furthermore, the flow path 71 in this embodiment is branched as follows: The flow path 71 includes flow path 711, flow path 712, flow path 713, and flow path 714. Flow path 711 is provided to supply liquid hydrogen from the second stage impeller 27 to the third stage impeller 28. Flow path 712 is provided to supply liquid hydrogen from the second stage impeller 27 to the second radial bearing 43. Flow path 713 is provided to supply liquid hydrogen from the second stage impeller 27 to the first radial bearing 42. Flow path 714 is provided to supply liquid hydrogen from the second stage impeller 27 to the thrust bearing 44.

[0035] When the liquefied gas pump 1 is started and the rotating shaft 20 reaches a predetermined rotational speed, the impeller 25 can pressurize the liquid hydrogen to a predetermined pressure. In this state, liquid hydrogen is also supplied to the bearing device 40, and the position of the rotating shaft 20 in the axial direction is stabilized. Figure 3 shows the liquefied gas pump 1 in the state when the rotating shaft 20 has reached a predetermined rotational speed. As liquid hydrogen is supplied to the thrust bearing 44 through the flow path 714, the thrust collar 22 is held in a position where it does not come into contact with the thrust bearing 44 in the axial direction via fluid pressure. In other words, as high-pressure liquid hydrogen is supplied to the thrust bearing 44, the axial load on the rotating shaft 20 is supported by the thrust bearing 44.

[0036] Furthermore, when the rotating shaft 20 reaches a predetermined rotational speed, the positional relationship between the thrust collar 22 and the radial bearing 41 is as follows: In the axial direction, the distance between the lower surface 22B of the thrust collar 22 and the thrust bearing 44 facing the lower surface 22B is smaller than the distance between the upper surface 22A of the thrust collar 22 and the thrust bearing 44 facing the upper surface 22A. Note that the axial positional relationship between the thrust collar 22 and the radial bearing 41 is not limited to this.

[0037] When the motor 30 is stopped, the rotating shaft 20 is no longer subjected to any external force for rotation. Immediately after the motor 30 is stopped, the rotating shaft 20 continues to rotate due to inertia. The rotational speed of the rotating shaft 20 gradually decreases and then stops. As the rotational speed of the rotating shaft 20 decreases, the amount of liquid hydrogen supplied to the bearing device 40 by the impeller 25 also decreases. Therefore, the flange portion 23 and the starting bearing 45 are again brought into contact with each other in the axial direction. The liquefied gas pump 1 stops when the rotation of the rotating shaft 20 comes to a complete halt. Note that when the liquefied gas pump 1 stops, the flange portion 23 and the starting bearing 45 may be brought into contact before the rotating shaft 20 comes to a complete halt, or they may be brought into contact after the rotating shaft 20 comes to a complete halt.

[0038] <Effects> In the liquefied gas pump 1 described above, when the liquefied gas pump 1 is stopped (non-operating), the flange portion 23 is supported axially by the starting bearing 45. In this state, the thrust collar 22 and thrust bearing 44 are positioned with a clearance in the axial direction. When the liquefied gas pump 1 rotates, the flange portion 23 moves upward in the axial direction and is separated from the starting bearing 45. As a result, even when the liquefied gas pump 1 is stopped, the thrust collar 22 and thrust bearing 44 do not come into contact in the axial direction. Furthermore, when the liquefied gas pump 1 rotates, the radial bearing 41 is supplied with liquid hydrogen and functions to hold the thrust collar 22 in the axial direction. Therefore, regardless of whether the liquefied gas pump 1 is operating or not, the thrust collar 22 and thrust bearing 44 do not come into contact. Consequently, wear on the thrust collar 22 and thrust bearing 44 can be suppressed.

[0039] In this embodiment, when the liquefied gas pump 1 is stopped (non-operating), the flange portion 23 is supported by the starting bearing 45, thereby supporting the rotating shaft 20 in the vertical direction. Therefore, frictional force is generated by the rotation of the rotating shaft 20 only at the contact surface between the flange portion 23 and the starting bearing 45. Even if the flange portion 23 and the starting bearing 45 wear out, they are easier to replace than the thrust collar 22 and thrust bearing 44. In other words, according to this embodiment, the flange portion 23 and the starting bearing 45 improve the maintainability of the liquefied gas pump 1.

[0040] Furthermore, the starting bearing 45 has a lubricating layer formed over the circumferential direction of the surface facing upward in the axial direction. The flange portion 23 and the starting bearing 45 are in contact via the lubricating layer provided on the starting bearing 45. The lubricating layer contains a solid lubricant. As a result, the coefficient of friction at the contact surface between the starting bearing 45 and the flange portion 23 is reduced, and the resulting frictional force is reduced. In other words, wear of the flange portion 23 and the starting bearing 45 that may occur when the liquefied gas pump 1 is started and stopped can be suppressed. This leads to improved maintainability of the liquefied gas pump 1.

[0041] Such a liquefied gas pump 1 is applicable to various fluids. Further, the liquefied gas pump 1 of the present embodiment is capable of boosting the pressure of liquid hydrogen. That is, the liquefied gas pump 1 of the present embodiment is applicable to liquid hydrogen which is at a lower temperature than LNG.

[0042] <Other Embodiments> Although the embodiments of the present disclosure have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present disclosure are also included.

[0043] The positions of the flange portion 23 and the starting bearing 45 according to the embodiment may be provided at different positions in the vertical direction. For example, the flange portion 23 and the starting bearing 45 may be provided so as to be sandwiched between the first radial bearing 42 and the thrust bearing 44 in the vertical direction.

[0044] Further, the bearing device 40 according to the embodiment may be provided so as to be capable of supplying liquid hydrogen from an impeller 25 other than the second-stage impeller 27. Further, the bearing device 40 may be provided so as to be capable of supplying liquid hydrogen from different impellers 25 respectively.

[0045] <Supplementary Note> The liquefied gas pump 1 described in each embodiment is grasped as follows, for example.

[0046] (1) The liquefied gas pump 1 according to the first aspect includes a rotary shaft body 21 extending in the axial direction, a thrust collar 22 projecting from the rotary shaft body 21 to the outer peripheral side, and a flange portion 23 projecting from the rotary shaft body 21 at an axial position different from that of the thrust collar 22. A rotary shaft 20, an impeller 25 provided on the rotary shaft 20 and capable of pumping a cryogenic liquid by rotating together with the rotary shaft 20, an electric motor 30 for rotationally driving the rotary shaft 20 about an axis O, and when the rotary shaft 20 stops, the flange portion 23 is placed from above and rotatably supports the flange portion 23, and a starting bearing 45 that separates the flange portion 23 upward when the rotary shaft 20 rotates, and a thrust bearing 44 that faces the thrust collar 22 from below through a clearance when the rotary shaft 20 stops and supports the thrust collar 22 through fluid pressure when the rotary shaft 20 rotates.

[0047] According to the above configuration, when the liquefied gas pump 1 stops, the flange portion 23 is supported by the starting bearing 45. In this state, the thrust collar 22 and the thrust bearing 44 are arranged through a clearance. When the liquefied gas pump 1 rotates, the flange portion 23 moves upward and is separated from the starting bearing 45. According to this, even when the liquefied gas pump 1 stops, the thrust collar 22 and the thrust bearing 44 do not contact. When the liquefied gas pump 1 rotates, the radial bearing 41 functions to hold the thrust collar 22. Therefore, it is possible to suppress wear of the thrust collar 22 and the thrust bearing 44.

[0048] (2) The liquefied gas pump according to the second aspect is the liquefied gas pump according to (1), and the starting bearing 45 has a lubricating layer containing a solid lubricant provided over the circumferential direction of the surface facing upward.

[0049] According to the above configuration, the flange portion 23 and the starting bearing 45 are in contact with each other through the lubricating layer provided on the starting bearing 45. The lubricating layer contains a solid lubricant. Therefore, it is possible to suppress wear of the flange portion 23 and the starting bearing 45 that may occur when the liquefied gas pump starts and stops.

[0050] (3) The liquefied gas pump relating to the third aspect is the liquefied gas pump of (1) or (2), wherein the cryogenic liquid is liquid hydrogen.

[0051] The liquefied gas pump of this disclosure provides a liquefied gas pump that can suppress wear of the thrust bearing during startup and shutdown.

[0052] 1. Liquefied Gas Pump 10. Casing 11. Suction Section 12. Discharge Section 20. Rotating Shaft 21. Rotating Shaft Body 22. Thrust Collar 22A. Top Surface 22B. Bottom Surface 23. Flange Section 24. Inducer 25. Impeller 26. First Stage Impeller 27. Second Stage Impeller 28. Third Stage Impeller 30. Electric Motor 31. Stator 32. Stator Core 35. Coil 36. Rotor 38. Rotor Core 40. Bearing System 41. Radial Bearing 42. First Radial Bearing 43. Second Radial Bearing 44. Thrust Bearing 45. Starting Bearing 50. Sump 51. Outer Flange 52. Upper Flange 53. Liquid Storage Chamber 60. Supply Pipe 61. Gas Discharge Pipe 62. Discharge Pipe 70, 71, 72, 711, 712, 713, 714 Flow path O axis

Claims

1. A liquefied gas pump comprising: a rotating shaft having a rotating shaft body extending in the axial direction, a thrust collar protruding outward from the rotating shaft body, and a flange portion protruding from the rotating shaft body at an axial position different from the thrust collar; an impeller provided on the rotating shaft and capable of pumping cryogenic liquid by rotating together with the rotating shaft; an electric motor that rotates the rotating shaft around its axis; a starting bearing on which the flange portion is placed from above when the rotating shaft is stopped and which rotatably supports the flange portion, and which separates the flange portion upward when the rotating shaft is rotated; and a thrust bearing that faces the thrust collar from below with a clearance when the rotating shaft is stopped and supports the thrust collar via fluid pressure when the rotating shaft is rotated.

2. The liquefied gas pump according to claim 1, wherein the starting bearing has a lubrication layer containing a solid lubricant provided over the circumferential direction of the upward-facing surface.

3. The liquefied gas pump according to claim 1, wherein the cryogenic liquid is liquid hydrogen.

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