Liquid metal pump and rotor axial force balancing method thereof

Abstract

The invention relates to the field of delivery pumps, in particular to a liquid metal pump and a rotor axial force balancing method thereof.The liquid metal pump comprises a pump cylinder, a pump shaft and an impeller, the pump cylinder comprises a pump body, a liquid inlet section and a guide vane which are sequentially connected, the liquid inlet section comprises a plurality of overflowing runners, and a partition mechanism for partitioning the pump body and the liquid inlet section is arranged above the overflowing runners; the partition mechanism comprises a balance drum and a partition part, the balance drum is connected with the pump shaft, the partition part is connected with the pump body and is in sealed rotating connection with the pump body, a high-pressure cavity is formed between the balance drum and the partition part, and the position where the impeller is located communicates with the high-pressure cavity; after liquid metal enters the liquid metal pump, part of the liquid metal enters the high-pressure cavity, the upper end face of the balance drum is a high-pressure area, the lower end face of the balance drum is a low-pressure area, and the balance drum can generate axial force opposite to the impeller to offset part of the axial force of the impeller. By the adoption of the technical scheme, vortexes generated in the cylinder during operation of the pump are reduced, and the operation load of the thrust bearing is reduced.

Description

Technical Field

[0001] This invention relates to the field of transfer pumps, and more specifically to liquid metal pumps and methods for balancing the axial force of their rotors. Background Technology

[0002] Liquid metal, with its excellent high-temperature thermal conductivity, neutron compatibility, and chemical stability, is the core cooling medium for heat removal. The stable delivery of liquid metal directly determines the service life of liquid metal pumps, as well as the heat exchange efficiency and operational safety of the system in which liquid metal is used.

[0003] The liquid metal pump is installed on the top cover of a pool-type container. The lower part of the container contains liquid metal, and the upper part is a covered air space. The pump casing is placed inside the container through an opening in the top cover. The hydraulic components of the liquid metal pump are located below the free surface of the liquid metal. The pump inlet is radially suctioned from the top, and the pump outlet is axially discharged from the bottom. During operation, the liquid metal pump generates vortices within the casing. Furthermore, due to the generally high density of liquid metals, the high-density medium, after being pressurized by the impeller, generates a significant axial force on the pump rotor. This impeller axial force is a major component of the rotor axial force. For example, the density of liquid lead-bismuth alloy is approximately 10 times that of water; at the same pump head, the axial force exerted by liquid lead-bismuth alloy on the pump rotor is about 10 times greater than that of water. The high axial force resulting from transporting high-density liquid metal significantly increases the operating load on the pump thrust bearing. Summary of the Invention

[0004] The present invention aims to provide a liquid metal pump that reduces vortices generated inside the pump barrel during operation and reduces the operating load on the thrust bearing.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a liquid metal pump, comprising a pump barrel, a pump shaft, and an impeller. The pump barrel includes a pump body, an inlet section, and guide vanes connected in sequence. The inlet section includes several flow channels distributed radially around the inlet section. The pump shaft is located inside the pump barrel, and the impeller is connected to the pump shaft. An isolation mechanism is provided above the flow channels to isolate the pump body and the inlet section. The isolation mechanism includes a balance drum and a partition. The balance drum is connected to the pump shaft, and the partition is connected to the pump body. The balance drum and the partition are in a sealed rotatable connection. A high-pressure chamber is formed between the balance drum and the partition. The impeller is located in communication with the high-pressure chamber.

[0006] The beneficial effects of this design are as follows: The compact structure and convenient arrangement of hydraulic components such as the inlet section, impeller, and guide vanes allow for uniform and smooth lateral intake of fluid from the upper inlet section, impeller pressurization, and axial discharge from the guide vanes, meeting the inlet / outlet interface requirements of the application scenario. Simultaneously, the flow channel, i.e., the pump inlet, is located in the lower half of the pump casing, close to the pump outlet and far from the free liquid surface, avoiding the risk of pump surge caused by the free liquid surface dropping to the pump inlet. Furthermore, the isolation mechanism effectively prevents vortices generated within the pump casing during operation. Additionally, the impeller location is connected to the high-pressure chamber, diverting the high-pressure medium from the impeller outlet to the upper end face of the balance drum. This achieves mutual cancellation or reduction of the axial forces generated by the two opposing high pressures, offsetting part or most of the impeller's axial force, thereby reducing the rotor's axial force, which in turn reduces the operating load on the thrust bearing and improves its service life.

[0007] Furthermore, the liquid inlet section also includes flow straightening ribs, and adjacent flow channels are separated by flow straightening ribs.

[0008] The beneficial effects of this solution are as follows: Firstly, it helps prevent the generation of external vortices during pump operation. Overcoming these internal and external vortices firstly avoids cavitation damage, extending the pump's service life. This is because when gas is drawn into the pump, it is rapidly compressed and ruptured under the high-pressure environment inside the pump, forming a strong cavitation impact that directly erodes the surface of internal pump components, causing pitting and spalling of materials. In severe cases, it can lead to component cracks and leaks, shortening the pump's lifespan. Secondly, it ensures the stability of pump operation and improves conveying efficiency. Vortices disrupt the uniformity of the liquid metal suction flow field, causing periodic fluctuations in the pump inlet fluid, which in turn leads to pump outlet pressure pulsations and flow oscillations. This unstable operating state not only... Reducing the pump's hydraulic efficiency leads to energy waste and can also induce increased pump vibration and noise. Long-term operation may cause loosening of pump connections and fatigue damage to pipelines, affecting the continuity of liquid metal circulation. Furthermore, it avoids the safety hazards of the system affected by liquid metal and ensures closed-loop operation of the system. The uniformity and stability of liquid metal circulation directly determine the system's heat dissipation efficiency. If vortices cause fluctuations in the pump's delivery capacity, it will cause local heat accumulation in the system, disrupting the system's thermal balance. In severe cases, it may trigger a system safety warning. Moreover, if the gas entrained in the pump remains in the loop, it will also affect the heat exchange effect, exacerbate abnormal system temperatures, and threaten the overall operational safety of the system.

[0009] Furthermore, the rectifier rib is provided with built-in pressure tapping holes, and the impeller location is connected to the high-pressure chamber through the built-in pressure tapping holes.

[0010] Furthermore, the flow channel is arc-shaped.

[0011] The beneficial effects of this scheme are as follows: the arc-shaped flow channels are distributed radially around the liquid inlet section, and adjacent arc-shaped flow channels are separated by rectifier ribs. The rectifier ribs serve to rectify the fluid intake and connect the upper and lower structures. The arc-shaped flow channels uniformly transition the fluid direction from radial to axial, so that it can enter the lower impeller inlet evenly and smoothly. After the fluid passes through the impeller and enters the lower guide vanes for deceleration and pressurization, it enters the outlet pipe from the axial pump outlet at the lower part of the guide vanes.

[0012] Furthermore, the partition element is a sealing ring or a guide bearing.

[0013] Furthermore, an annular cavity is formed between the guide vane and the liquid inlet section at the location of the impeller, and the lower end of the built-in pressure-inlet hole is bent and connected to the annular cavity.

[0014] The beneficial effects of this scheme are: by setting up an annular cavity between the guide vane and the liquid inlet section, and by using the built-in pressure-inducing hole to draw pressure through the annular cavity, the overall flow channel layout can be maintained without affecting the overall flow channel layout and hydraulic losses can be reduced.

[0015] The present invention also provides a method for balancing the axial force of a liquid metal pump rotor. After the liquid metal enters the aforementioned liquid metal pump, part of the liquid metal enters the high-pressure chamber. The upper end face of the balancing drum is the high-pressure zone, and the lower end face of the balancing drum is the low-pressure zone. The balancing drum can generate an axial force opposite to that of the impeller to offset part of the axial force of the impeller.

[0016] Furthermore, the diameter of the balancing drum is adjustable.

[0017] The beneficial effect of this solution is that the axial force of the rotor can be adjusted by replacing the balance drums of different diameters. Attached Figure Description

[0018] Figure 1 This is a front view of the present invention; Figure 2 This is a front sectional view of the present invention; Figure 3 for Figure 2 A sectional view along the AA direction.

[0019] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: pump shaft 1, impeller 2, pump body 3, inlet section 4, guide vane 5, flow channel 6, flow straightening rib 7, balance drum 8, partition 9, high pressure chamber 10, built-in pressure tapping hole 11, and annular cavity 12. Detailed Implementation

[0020] Example The basic implementation examples are as follows: Figure 1-3 As shown, Figure 1 , 2The liquid metal pump shown includes a pump casing, a pump shaft 1, and an impeller 2. The pump casing includes a pump body 3, an inlet section 4, and guide vanes 5, which are bolted together in sequence. The inlet section 4 includes several flow channels 6 and flow straightening ribs 7, such as... Figure 3 As shown, this embodiment has six flow channels 6 and six flow straightening ribs 7. The flow channels 6 are arc-shaped and are distributed radially around the liquid inlet section 4. Adjacent flow channels 6 are separated by flow straightening ribs 7. Figure 1 , 2 The position of the free liquid surface is indicated by a horizontal dashed line in the upper middle.

[0021] The pump shaft 1 is located inside the pump casing. The impeller 2 is bolted to the pump shaft 1. A partition mechanism is provided above the flow channel 6 to separate the pump body 3 and the inlet section 4. The partition mechanism includes a balance drum 8 and a partition 9. The balance drum 8 is keyed to the pump shaft 1 and axially limited by the shoulder and nut of the pump shaft 1. The partition 9 is bolted to the pump body 3 and the balance drum 8 is rotatably sealed to the partition 9. The balance drum 8 can be rotatably sealed to the inlet section 4 or rotatably unsealed. The diameter of the balance drum 8 is adjustable. The partition 9 is a sealing ring or a guide bearing. In this embodiment, a sealing ring is selected.

[0022] A high-pressure chamber 10 is formed between the balance drum 8 and the partition 9. The impeller 2 is located in connection with the high-pressure chamber 10. Specifically, as shown in the figure... Figure 2 , 3 As shown, the rectifier rib 7 has a built-in pressure-inlet hole 11. The location of the impeller 2, i.e. the outlet of the impeller 2, is connected to the high-pressure chamber 10 through the built-in pressure-inlet hole 11. Among them, the guide vane 5 and the liquid inlet section 4 at the location of the impeller 2 form an annular cavity 12. The lower end of the built-in pressure-inlet hole 11 is bent and connected to the annular cavity 12.

[0023] This embodiment also discloses a method for balancing the axial force of a liquid metal pump rotor, wherein the liquid metal is based on... Figure 2 After entering the liquid metal pump through the path indicated by the middle arrow, part of the liquid metal enters the high-pressure chamber 10 through the built-in pressure tap 11. The upper end face of the balance drum 8 is the high-pressure zone, and the lower end face of the balance drum 8 is the low-pressure zone. The balance drum 8 can generate an axial force opposite to that of the impeller 2 to offset part or most of the axial force of the impeller 2, thereby reducing the axial force of the rotor and thus reducing the operating load of the thrust bearing.

[0024] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A liquid metal pump, characterized in that: The pump includes a pump casing, a pump shaft, and an impeller. The pump casing includes a pump body, an inlet section, and guide vanes connected in sequence. The inlet section includes several flow channels distributed radially around the inlet section. The pump shaft is located inside the pump casing, and the impeller is connected to the pump shaft. An isolation mechanism is provided above the flow channels to isolate the pump body and the inlet section. The isolation mechanism includes a balance drum and a partition. The balance drum is connected to the pump shaft, and the partition is connected to the pump body. The balance drum and the partition are rotatably and sealed together. A high-pressure chamber is formed between the balance drum and the partition. The impeller is located in communication with the high-pressure chamber.

2. The liquid metal pump according to claim 1, characterized in that: The liquid inlet section also includes flow straightening ribs, and adjacent flow channels are separated by flow straightening ribs.

3. The liquid metal pump according to claim 2, characterized in that: The rectifier rib is equipped with a built-in pressure tap, and the impeller is connected to the high-pressure chamber through the built-in pressure tap.

4. The liquid metal pump according to claim 3, characterized in that: The flow channel is arc-shaped.

5. The liquid metal pump according to claim 4, characterized in that: The partition is a sealing ring or a guide bearing.

6. The liquid metal pump according to claim 5, characterized in that: An annular cavity is formed between the guide vane and the liquid inlet section at the location of the impeller, and the lower end of the built-in pressure tap is bent and connected to the annular cavity.

7. A method for balancing the axial force of a liquid metal pump rotor, characterized in that: After the liquid metal enters the liquid metal pump according to any one of claims 1-6, part of the liquid metal enters the high-pressure chamber. The upper end face of the balance drum is the high-pressure zone, and the lower end face of the balance drum is the low-pressure zone. The balance drum can generate an axial force opposite to that of the impeller to counteract part of the axial force of the impeller.

8. The method for balancing the axial force of a liquid metal pump rotor according to claim 7, characterized in that: The diameter of the balancing drum is adjustable.

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