Flywheel structure of nuclear power main pump

Abstract

The invention discloses a nuclear power main pump flywheel structure, and belongs to the technical field of nuclear power main pump devices. The structure comprises a flywheel base body arranged on a rotating shaft in a sleeving mode, a cover plate is further arranged on the rotating shaft where one end of the flywheel base body is located, an auxiliary impeller is arranged on the rotating shaft where the other end of the flywheel base body is located, a locking mechanism is arranged on the other side of the auxiliary impeller, balance weight holes are formed in the circumference of the flywheel base body in an array mode, and tungsten alloy columns are arranged in the balance weight holes. The tungsten alloy column comprises a tungsten column base material, and the outer side face of the tungsten column base material is coated with a stainless steel metal layer. The stainless steel metal layer is arranged on the outer side of the tungsten column base material, so that the corrosion resistance of the tungsten alloy column can be effectively improved, the defects of the tungsten alloy column in the prior art are further overcome, the service life of the flywheel is prolonged, and the stability of the nuclear power main pump is better facilitated.

Description

Technical Field

[0001] The present invention relates to a flywheel structure of a nuclear power main pump, belonging to the technical field of nuclear power main pump devices. Background Art

[0002] In order to increase the moment of inertia of the rotating components of the nuclear main pump rotor and extend the coast-down time after pump shutdown to discharge the residual heat in the reactor core, high-quality flywheels are assembled on the main pump rotor components, and the flywheels generally adopt high-density heavy metal alloys.

[0003] The hot isostatic pressing process places the product in a sealed container, applies equal pressure in all directions to the product, and simultaneously applies high temperature. Under the action of high temperature and high pressure, the product is sintered and densified.

[0004] With the application of materials and cost considerations, more and more high-density materials are embedded to increase the mass of the flywheel, as follows:

[0005] The literature ("Discussion on the Structure and Design Requirements of the Flywheel of Nuclear Power Main Pumps", Shanghai Electric KSB and Electric Pump Valve Co., Ltd., June 2013, Cui Haiyan, Li Tianbin) discloses a flywheel structure, and its structure discloses a structural design of a flywheel with counterweight holes and high-density tungsten steel rods (usually high-purity tungsten steel or depleted uranium materials) arranged thereon. In actual application, based on the service environment of the nuclear power main pump structure, its specific structure will be greatly affected in terms of service life in application.

[0006] The doctoral thesis ("Optimal Design of the Flywheel Structure of Nuclear Power Main Pumps", Dalian University of Technology, Jiang Lu, June 2018) discloses a structural design of sub-theories and layers, which designs the flywheel structure in multiple layers and adds tungsten alloy layers to solve the mass problem of the flywheel.

[0007] The master's thesis ("Strength Analysis and Structural Dimension Design of the Flywheel of a Shielded Nuclear Power Main Pump under Static Conditions", Dalian University of Technology, Xu Fangbin, May 19, 2019) also discloses a flywheel structure, and its structure discloses a structural design of a flywheel with assembly holes and high-density tungsten steel rods (usually high-purity tungsten steel or depleted uranium materials) arranged thereon.

[0008] In the above-mentioned publicly available literature, it shows that using tungsten alloy columns as the main mass-bearing part of the flywheel is a more common structure at present. However, in specific actual applications, especially in the field of nuclear power applications, it has an adverse effect on the tungsten alloy part, and its corrosion resistance effect is relatively weak. Summary of the Invention

[0009] The object of the present invention is to: in view of the above problems, provide a flywheel structure for a nuclear power main pump. Based on the fact that tungsten-based heavy alloy is prone to corrosion in a special application environment and needs protection, an austenitic stainless steel is coated on its surface to improve its corrosion resistance.

[0010] The technical solution adopted by the present invention is as follows:

[0011] A flywheel structure for a nuclear power main pump, characterized in that: it includes a flywheel base sleeved on a rotating shaft, a cover plate is also arranged on the rotating shaft where one end of the flywheel base is located, an auxiliary impeller is arranged on the rotating shaft where the other end is located, a locking mechanism is arranged on the other side of the auxiliary impeller, weight holes are arranged in a circumferential array on the flywheel base, tungsten alloy columns are arranged in the weight holes, the tungsten alloy columns include tungsten column substrates, and a stainless steel metal layer is coated on the outer side of the tungsten column substrates.

[0012] Further, a mirror plate is arranged at the bottom of the auxiliary impeller near the outer side, the mirror plate is fixedly embedded at the bottom of the auxiliary impeller, a first through hole is arranged in the middle of the rotating shaft along the axial direction, and a second through hole is arranged between the auxiliary impeller and the rotating shaft along the direction perpendicular to the axial direction of the rotating shaft, and the first through hole communicates with the second through hole arranged on the rotating shaft.

[0013] Further, the rotating shaft and the auxiliary impeller are assembled through a conical surface, the diameter of the rotating shaft at the part where the auxiliary impeller is assembled is larger at the top and smaller at the bottom, and the inner diameter of the installation hole of the auxiliary impeller is larger at the top and smaller at the bottom.

[0014] Further, the locking mechanism includes a compression nut arranged at the bottom of the auxiliary impeller, and the compression nut is threadedly assembled with the rotating shaft, and the thread direction is opposite to the rotation direction of the rotating shaft.

[0015] Further, a compression ring for providing a locking force for the compression nut is also arranged outside the compression nut, and the compression ring matches the compression nut.

[0016] Further, a plurality of first assembly holes are arranged in a circumferential array on the compression ring, and second assembly holes matching the compression ring are arranged on the auxiliary impeller. After the compression ring is assembled, the first assembly holes and the second assembly holes are assembled with screws.

[0017] Further, a retaining collar is also arranged at the cap of the screw after the screw is assembled.

[0018] Further, a counterbore is preset at the bottom of the auxiliary impeller, and a part of the compression nut and the compression ring is located in the counterbore.

[0019] Further, the tungsten alloy column is integrally formed by a hot isostatic pressing process.

[0020] Further, the weight holes include multiple groups, and each group of weight holes is distributed in a circumferential array. The tungsten alloy columns are assembled in the weight holes by interference fit.

[0021] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0022] 1. For a flywheel structure of a nuclear power main pump according to the present invention, by providing a stainless steel metal layer on the outer side of the tungsten column substrate, the corrosion resistance of the tungsten alloy column can be effectively improved, further improving the deficiencies of the tungsten alloy column in the prior art, enhancing the service life of the flywheel, and being more conducive to the stable performance of the nuclear power main pump.

[0023] 2. For a flywheel structure of a nuclear power main pump according to the present invention, it can effectively achieve better assembly of the structure, ensure its assembly effect, and at the same time further ensure the disassembly and assembly efficiency and application effect of the entire structure. In the design of the conical surface, the conical surface fit not only ensures concentricity but also improves the tightness between the shaft and the thrust disk. At the same time, it further ensures the assembly effect and stability of the entire structure, and it can effectively achieve the effect of quick disassembly and assembly.

[0024] 3. For a flywheel structure of a nuclear power main pump according to the present invention, through the design of the locking mechanism, the assembly stability of the auxiliary impeller can be effectively ensured. At the same time, during maintenance and repair, quick disassembly and assembly can be achieved, further improving work efficiency. In terms of the assembly effect, the assembly requirements are greatly reduced, thus ensuring the disassembly and assembly effect, effectively solving the inconvenience of traditional structure assembly. Especially in the role of positioning and centering, not too much assistance is required, and it has more advantages in assembly efficiency compared with traditional structures. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be described by way of examples with reference to the accompanying drawings, where:

[0026] Figure 1 is a schematic structural diagram of the present invention;

[0027] Figure 2 is a schematic structural diagram of the flywheel of the present invention;

[0028] Reference numerals in the drawings: 1 - rotating shaft, 2 - flywheel base, 3 - cover plate, 4 - auxiliary impeller, 5 - tungsten alloy column, 6 - pressing ring, 7 - pressing nut, 8 - first through hole, 9 - second through hole. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] All features disclosed in this specification, or all steps in any method or process disclosed, can be combined in any way, except for mutually exclusive features and / or steps.

[0030] Any feature disclosed in this specification, unless specifically described, can be replaced by other equivalent or similar-purpose alternative features. That is, unless specifically described, each feature is only an example of a series of equivalent or similar features.

[0031] Embodiment 1

[0032] A flywheel structure for a nuclear power main pump, as Figure 1 , includes a flywheel base body 2 sleeved on a rotating shaft 1. A cover plate 3 is also provided on the rotating shaft 1 at one end of the flywheel base body 2, and an auxiliary impeller 4 is provided on the rotating shaft 1 at the other end. A locking mechanism is provided on the other side of the auxiliary impeller 4. Weight holes are arranged in a circumferential array on the flywheel base body 2, and tungsten alloy columns 5 are arranged in the weight holes. The tungsten alloy columns 5 include tungsten column substrates, and the outer side of the tungsten column substrates is coated with a stainless steel metal layer.

[0033] In a sub-theory structure of a nuclear power main pump of this structure, in the specific structural design, the traditional part uses high-density heavy metals as the core part, but there are also differences in the specific structural design. The effect of using a tungsten column substrate and a stainless steel metal layer in combination in this structure is to effectively coat a protective layer on the outside of the tungsten column substrate, solving the problem that tungsten-based heavy alloys are prone to corrosion and need protection in special application environments, thus achieving a longer service life of the flywheel, and further improving the service life of the flywheel and the stability of the entire nuclear power main pump.

[0034] As a more specific design, a mirror plate is provided at the bottom of the auxiliary impeller 4 near the outer side. The mirror plate is fixedly embedded at the bottom of the auxiliary impeller 4. A first through hole 8 is provided in the middle of the rotating shaft 1 along the axial direction. The auxiliary impeller 4 and the rotating shaft 1 are provided with a second through hole 9 along the direction perpendicular to the axial direction of the rotating shaft 1. The first through hole 8 communicates with the second through hole 9 provided on the rotating shaft 1.

[0035] Different from the traditional structural design, in this structure, a structural design of a locking mechanism is adopted, which can effectively ensure the assembly stability of the auxiliary impeller 4, avoid other non-compliant situations during operation, further improve the service life of the overall structure, and at the same time improve the maintenance efficiency of the entire structure, thereby achieving better functions and effects.

[0036] In the above specific structural design, based on the design of the locking mechanism, its main purpose is designed based on the assembly situation of the auxiliary impeller 4 and the rotating shaft 1. For better centering and assembly, as well as facilitating disassembly and assembly for subsequent maintenance and improving work efficiency, in a more specific design, the rotating shaft 1 and the auxiliary impeller 4 are assembled through a conical surface. The diameter of the rotating shaft 1 in the part where the auxiliary impeller 4 is assembled is larger at the top and smaller at the bottom, and the inner diameter of the mounting hole of the auxiliary impeller 4 is larger at the top and smaller at the bottom. The mating position between the rotating shaft 11 and the thrust disk is set as a conical surface, and a through hole is opened on the rotating shaft 1, with a large hole combined with a small hole. The small hole keeps the same direction and size as the radial hole of the thrust disk. The conical surface fit not only ensures concentricity but also improves the tightness between the shaft and the thrust disk.

[0037] Based on the above specific structural design, more specifically, after the mirror plate is assembled, the bottom side of it matches the bottom side of the auxiliary impeller 4, and the diameter of the first through hole 8 is larger than the diameter of the second through hole 9.

[0038] Based on the above specific structural design, the indentation mechanism includes a compression nut 7 arranged at the bottom of the auxiliary impeller 4. The compression nut 7 and the rotating shaft 1 are assembled by threads, and the thread direction is opposite to the rotation direction of the rotating shaft 1. In the design of this structure, compared with the design of traditional structure such as a snap pin or interference fit, the design of this structure can achieve a more stable effect in actual application and has obvious advantages and performance compared with the traditional structure.

[0039] To better ensure that the compression nut 7 does not withdraw and loosen, in a more specific design, a compression ring 6 for providing a locking force for the compression nut 7 is further arranged on the outer side of the compression nut 7, and the compression ring 6 matches the compression nut 7.

[0040] As a specific design, the end of the compression nut 7 that matches the auxiliary impeller 4 is provided with a limiting step (preferably a ring step) for being pressed, and the end of the compression ring 6 that matches the auxiliary impeller 4 is also provided with a limiting step (preferably a ring step) for pressing the compression nut 7. Through the structural design in this way, the assembly effect of the compression nut 7 on the auxiliary impeller 4 can be further ensured.

[0041] As a more specific design, to further ensure the stable effect of the compression ring 6, a plurality of first assembly holes distributed in a circumferential array are arranged on the compression ring 6, and second assembly holes matching the compression ring 6 are arranged on the auxiliary impeller 4. After the compression ring 6 is assembled, the first assembly holes and the second assembly holes are assembled with screws. As a specific design, the second assembly holes arranged on the auxiliary impeller 4 can be threaded holes, and at the same time, both the first assembly holes and the second assembly holes can be set as threaded holes.

[0042] To further ensure the locking effect of the locking mechanism, more specifically, a retaining collar is further arranged at the head of the screw after the screw is assembled.

[0043] As a specific design, a counterbore is preset at the bottom of the auxiliary impeller 4, and a part of the compression nut 7 and the compression ring 6 is located in the counterbore.

[0044] More specifically, an annular groove is formed on the side surface of the bottom of the auxiliary impeller 4, and a hard alloy formed mirror plate is press-fitted and embedded in the annular groove.

[0045] As a specific design, the tungsten alloy column 5 is integrally formed by hot isostatic pressing process.

[0046] More specifically, the weight holes include multiple groups, and each group of weight holes is distributed in a circumferential array. The tungsten alloy column 5 is press-fitted into the weight holes. In this structure, the inner diameters between each group of weight holes can be designed to be of different sizes. For example, the outer ones are larger than the inner assembly holes, or they are arranged in a cross pattern.

[0047] Embodiment 2

[0048] For a further design of the specific processing technology of the tungsten alloy column 5, a manufacturing process of the tungsten alloy column 5 for a nuclear power main pump is as Figure 1 and Figure 2 shown, and it includes the following steps:

[0049] S1. Manufacturing of tungsten column: Using tungsten metal material to manufacture tungsten column according to the target size requirements to form a tungsten column substrate;

[0050] S2. Manufacturing of tungsten alloy column 5: Placing the tungsten column substrate into a manufacturing mold, and coating a layer of stainless steel metal on the outer side surface of the tungsten column substrate to form the tungsten alloy column 5;

[0051] S3. Inspecting the geometric dimensions of the tungsten alloy column 5 bar, and combining finish machining to make the geometric dimensions of the final tungsten alloy column 5 bar meet the requirements.

[0052] In the above specific process design, as a specific design, in step 2, when coating the stainless steel metal layer on the outer side surface of the tungsten column substrate, the casting process is used to completely wrap the tungsten column substrate with the stainless steel metal.

[0053] As a different design and more suitable for the requirements of this design, in step 2, when coating the stainless steel metal layer on the outer side surface of the tungsten column substrate, the hot isostatic pressing process is used to completely wrap the tungsten column substrate with the stainless steel metal.

[0054] As a specific description, the hot isostatic pressing process is that the product is placed in a closed container, and while applying an isotropic pressure to the product, high temperature is applied. Under the combined action of high temperature and high pressure, the product is sintered, densified or diffusion-bonded.

[0055] Further, before the tungsten column substrate is placed into a sealable container, stainless steel metal powder is laid at the bottom, the tungsten column substrate is placed in, and then more stainless steel metal powder is added to completely wrap the tungsten column substrate.

[0056] In the design of this process, the tungsten alloy column using the hot isostatic pressing diffusion bonding technology has the advantages of high bonding strength, complete microstructure, small distortion, and the ability to achieve bonding between different materials. Since no liquid phase is generated at the interface, the interface bonding strength is the same as that of the weaker side base material, enabling good metallurgical bonding and forming a high-density composite tungsten alloy column.

[0057] In summary:

[0058] 1. For a flywheel structure of a nuclear power main pump according to the present invention, by providing a stainless steel metal layer outside the tungsten column substrate, the corrosion resistance of the tungsten alloy column can be effectively improved, further improving the deficiencies of the tungsten alloy column in the prior art, enhancing the service life of the flywheel, and being more conducive to the stable performance of the nuclear power main pump.

[0059] 2. For a flywheel structure of a nuclear power main pump according to the present invention, it can effectively achieve better assembly of this structure, ensure its assembly effect, and at the same time further ensure the disassembly and assembly efficiency and application effect of the entire structure. In the design of the conical surface, the conical surface fit not only ensures concentricity but also improves the tightness between the shaft and the thrust disk, and at the same time further ensures the assembly effect and stability of the entire structure, and it can effectively achieve the effect of rapid disassembly and assembly.

[0060] 3. For a flywheel structure of a nuclear power main pump according to the present invention, through the design of the locking mechanism, the assembly stability of the auxiliary impeller can be effectively ensured. At the same time, rapid disassembly and assembly can be achieved during maintenance and repair, further improving work efficiency. In terms of the assembly effect, the assembly requirements are greatly reduced, thus ensuring the disassembly and assembly effect, effectively solving the inconvenience of traditional structure assembly. Especially in the role of positioning and centering, not much assistance is required, and it has more advantages in assembly efficiency compared to traditional structures.

[0061] The present invention is not limited to the foregoing specific embodiments. The present invention extends to any new feature or any new combination disclosed in this specification, as well as any new method or process step or any new combination disclosed.

Claims

1. A flywheel structure of a nuclear power main pump, characterized in that: It includes a flywheel base sleeved on a rotating shaft. A cover plate is also arranged on the rotating shaft where one end of the flywheel base is located, and an auxiliary impeller is arranged on the rotating shaft where the other end is located. A locking mechanism is arranged on the other side of the auxiliary impeller. The flywheel base is provided with counterweight holes arranged in a circumferential array, and tungsten alloy columns are arranged in the counterweight holes. The tungsten alloy column includes a tungsten column base material, and the outer side of the tungsten column base material is coated with a stainless steel metal layer.

2. The flywheel structure of a nuclear power main pump according to claim 1, characterized in that: A mirror plate is arranged at the bottom near the outer part of the auxiliary impeller. The mirror plate is fixedly embedded at the bottom of the auxiliary impeller. A first through hole is arranged in the middle of the rotating shaft along the axial direction. The auxiliary impeller and the rotating shaft are provided with a second through hole along the direction perpendicular to the axial direction of the rotating shaft, and the first through hole communicates with the second through hole arranged on the rotating shaft.

3. The flywheel structure of a nuclear power main pump according to claim 1, characterized in that: The rotating shaft and the auxiliary impeller are assembled through a conical surface. The diameter of the part of the rotating shaft where the auxiliary impeller is assembled is larger at the top and smaller at the bottom, and the inner diameter of the mounting hole of the auxiliary impeller is also larger at the top and smaller at the bottom.

4. The flywheel structure of a nuclear power main pump according to claim 1, characterized in that: The locking mechanism includes a compression nut arranged at the bottom of the auxiliary impeller. The compression nut is threadedly assembled with the rotating shaft, and the thread direction is opposite to the rotation direction of the rotating shaft.

5. The flywheel structure of a nuclear power main pump according to claim 4, characterized in that: A compression ring for providing a locking force for the compression nut is also arranged on the outer side of the compression nut, and the compression ring matches the compression nut.

6. The flywheel structure of a nuclear power main pump as described in claim 5, characterized in that: A plurality of first assembly holes are arranged on the compression ring in a circumferential array. The auxiliary impeller is provided with second assembly holes matching the compression ring. After the compression ring is assembled, the first assembly holes and the second assembly holes are assembled with screws.

7. The flywheel structure of a nuclear power main pump according to claim 6, characterized in that: A retaining collar is also arranged at the head of the screw after the screw is assembled.

8. The flywheel structure of a nuclear power main pump according to claim 5, characterized in that: A counterbore is preset at the bottom of the auxiliary impeller, and a part of the compression nut and the compression ring is located in the counterbore.

9. The flywheel structure of a nuclear power main pump according to claim 1, characterized in that: The counterweight holes include multiple groups, and each group of counterweight holes is arranged in a circumferential array. The tungsten alloy columns are assembled in the counterweight holes through interference fit.

10. A flywheel structure of a nuclear power main pump according to claim 1, characterized in that: The tungsten alloy column is made by the following process: S1. Fabrication of the tungsten column: Using tungsten metal material, fabricate the tungsten column into a formed shape according to the target size requirements to form the tungsten column base material. S2. Fabrication of the tungsten alloy column: Place the tungsten column base material into a fabrication mold, and coat a layer of stainless steel metal layer on the outer side of the tungsten column base material to form the tungsten alloy column. S3. Inspect the geometric dimensions of the tungsten alloy column bar, and combine precision machining to make the geometric dimensions of the final tungsten alloy column bar meet the requirements.

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