Method for inspecting oil-lubricated hydrodynamic plain bearing of main pump of nuclear power plant
By developing inspection methods for the oil-lubricated hydrodynamic sliding bearings of the main pumps in nuclear power plants, the problem of the lack of standardized evaluation in China has been solved, enabling independent inspection and safe and reliable operation of the bearings, reducing costs and improving efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- CNNC FUJIAN FUQING NUCLEAR POWER
- Filing Date
- 2023-03-06
- Publication Date
- 2026-07-14
AI Technical Summary
The lack of standardized evaluation methods for the reuse of main pump bearing bushes in domestic nuclear power plants leads to the risk of bushes being wasted or abnormally burned, and makes it impossible to achieve safe and reliable operation, cost reduction and efficiency improvement.
Establish inspection methods for the oil-lubricated hydrodynamic sliding bearings of main pumps in nuclear power plants, including historical operation checks, visual inspections, critical dimension checks, and non-destructive testing, and provide quantified inspection technical criteria to assess the reusability of the bearing bushes.
It has enabled independent inspection of the main pump bearings of nuclear power plants, quantified the inspection indicators, met the needs of the site, alleviated the risk of bearing inventory backlog and abnormal burn-out, and ensured the safe and reliable operation of the unit.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of equipment and materials technology, and specifically relates to a method for inspecting the oil-lubricated hydrodynamic sliding bearing of the main pump in a nuclear power plant. Background Technology
[0002] Regarding the evaluation of main pump bearing reuse, neither internationally nor domestically have standardized technical solutions (such as national standards or group standards) been published. Furthermore, imported main pump manufacturers often treat reuse assessment standards as core internal technologies, effectively blocking them from nuclear power plants. Therefore, domestic nuclear power plants often only conduct preliminary analyses through visual inspections by technical engineers, failing to provide systematic evaluation opinions. This leads to the potential waste of reusable bearings and the risk of abnormal burn-out of reused bearings. Summary of the Invention
[0003] The purpose of this invention is to provide a method for inspecting the oil-lubricated hydrodynamic sliding bearings of the main pump in nuclear power plants, to formulate technical criteria for inspecting the reuse of main pump bearings, and to evaluate the used bearings (hereinafter referred to as old bearings) according to these technical criteria, to determine whether they meet the reuse conditions and to reuse or discard them, thereby alleviating the problem of stockpiling of old main pump bearings in nuclear power plants, and achieving the goal of cost reduction and efficiency improvement while ensuring the safe and reliable operation of the unit.
[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0005] A method for inspecting the oil-lubricated hydrodynamic sliding bearing of a nuclear power plant main pump, the inspection objects being: the main thrust bearing, auxiliary thrust bearing, guide bearing, and thrust disc of the oil-lubricated hydrodynamic sliding bearing of a nuclear power plant main pump; each bearing set has 7 main thrust bearings, 10 auxiliary thrust bearings, 8 upper guide bearings, 5 lower guide bearings, and 1 thrust disc; the inspection and evaluation are carried out through historical operation checks, visual inspections, key dimension checks, and non-destructive testing.
[0006] Check the historical operation of the main pump: The coasting curves during the start-up and shutdown phases of the main pump in the previous operating cycle, namely the temperature-time and speed-time curves, should be normal. Specifically, the coasting curve should have no inflection point and the coasting temperature rise should be ≤5℃.
[0007] Apart from the coasting curve during the start-stop phase, if any abnormalities are found in important parameters of historical operating data, they should be reviewed in detail to analyze the root cause of the abnormality and indicate whether it is related to the bearing capacity of the bearing bush.
[0008] Main thrust bearing inspection:
[0009] Visual inspection of wear is conducted, with the following standards: no black discoloration caused by tar on the bearing surface; no obvious large-area indentations on the bearing surface; no large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the bearing surface; no cavitation marks on the bearing surface; no large spherical inclusions on the bearing surface; no burrs on the bearing edge; no obvious wear near the top oil hole; no abnormal damage or deformation at the top oil hole chamfer and bearing edge chamfer.
[0010] For critical dimension checks, nine points are evenly selected on the surface of each main thrust bearing. The bearing height corresponding to these nine points is recorded. The height of each main thrust bearing is taken as the average of these nine points. Flatness is taken as the difference between the maximum and minimum values, with the following standards: flatness ≤ 0.02 mm; difference in average height between bearings ≤ 0.15 mm; surface roughness is only recorded; surface contact area ≥ 75%; high points are evenly distributed after scraping.
[0011] Non-destructive testing only needs to meet the relevant standard requirements.
[0012] The 9 points are distributed in a 3x3 matrix.
[0013] Auxiliary thrust bearing inspection:
[0014] Visual inspection of wear is conducted, with the following standards: no black discoloration caused by tar on the bearing surface; no obvious large-area indentations on the bearing surface; no large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the bearing surface; no cavitation marks on the bearing surface; no large spherical inclusions on the bearing surface; no flash on the bearing edge; no abnormal damage or deformation at the chamfer of the bearing edge.
[0015] For critical dimension checks, nine points are evenly selected on the surface of each auxiliary thrust bearing. The bearing height corresponding to these nine points is recorded. The height of each auxiliary thrust bearing is the average of these nine points. Flatness is measured as the difference between the maximum and minimum values, with the following standards: flatness ≤ 0.02 mm; difference in average height between bearings ≤ 0.15 mm; surface roughness is only recorded; surface contact area ≥ 75%; high points are evenly distributed after scraping.
[0016] Non-destructive testing only needs to meet the relevant standard requirements.
[0017] The 9 points are distributed in a 3x3 matrix.
[0018] Guide tile inspection:
[0019] Visual inspection of wear is conducted, with the following standards: no black discoloration caused by tar on the bearing surface; no obvious large-area indentations on the bearing surface; no large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the bearing surface; no cavitation marks on the bearing surface; no large spherical inclusions on the bearing surface; no flash on the bearing edge; no abnormal damage or deformation at the chamfer of the bearing edge.
[0020] Key dimensions are checked; surface roughness is only recorded.
[0021] Non-destructive testing only needs to meet the relevant standard requirements.
[0022] Thrust plate inspection:
[0023] Visual inspection of wear and tear is required, with the following standards: no large-area wear on the surface; no obvious raised spots on the surface.
[0024] For critical dimension checks, take 6 measurement points at 60° intervals along the circumference of the thrust plate and record the thrust plate height corresponding to the 6 points. The standards are as follows: only the thrust plate height and surface roughness are recorded.
[0025] Non-destructive testing only needs to meet the relevant standard requirements.
[0026] The beneficial effects achieved by this invention are as follows:
[0027] The quantitative inspection techniques for the oil-lubricated hydrodynamic sliding bearings of the main pumps in nuclear power plants have enabled domestic nuclear power plants to independently inspect the availability of bearing bushes.
[0028] For the first time, quantitative indicators for the inspection technology of oil-lubricated hydrodynamic sliding bearings in the main pumps of nuclear power plants have been given.
[0029] This met the urgent needs of the power plant's on-site main pump bearing inspection work.
[0030] This is the first technical guideline for the inspection of main pump bearings in China's nuclear power industry, filling a gap in the field of inspection standards for main pump bearings in nuclear power plants. Detailed Implementation
[0031] The present invention will now be described in detail with reference to specific embodiments.
[0032] A method for inspecting the oil-lubricated hydrodynamic sliding bearing of the main pump in a nuclear power plant:
[0033] The old bearing shells are inspected and evaluated from the following four aspects: historical operation status inspection, appearance inspection, key dimension inspection, and non-destructive testing.
[0034] Inspection objects: Main thrust bearing, auxiliary thrust bearing, guide bearing, and thrust disc of the main pump oil-lubricated hydrodynamic sliding bearing in a nuclear power plant. Each bearing set contains 7 main thrust bearings, 10 auxiliary thrust bearings, 8 upper guide bearings, 5 lower guide bearings, and 1 thrust disc.
[0035] I. Inspection of the main pump's historical operating status
[0036] The coasting curves (temperature-time, speed-time) during the start-stop phase of the main pump in the previous operating cycle should be normal, specifically, the coasting curve should have no inflection point and the coasting temperature rise should be ≤5℃.
[0037] Note: In addition to the coasting curve during the start-stop phase, if any abnormalities are found in important parameters of historical operating data, they should be reviewed in detail, the root cause of the abnormality should be analyzed, and it should be noted whether it is related to the bearing capacity of the bearing bush.
[0038] II. Inspection of main thrust bearings
[0039] 1. Visual inspection: Inspect for wear and tear. Standards are as follows:
[0040] • The tile surface shows no black discoloration caused by tar;
[0041] • No obvious large-area indentations on the tile surface;
[0042] • The tile surface lacks a Babbitt metal layer, exhibiting extensive wear, peeling, or surface cracks;
[0043] ●No signs of cavitation on the tile surface;
[0044] ●The tile surface has no large spherical inclusions;
[0045] ● No flash on the edge of the bearing;
[0046] ●No obvious wear near the top oil hole;
[0047] ●The top oil hole chamfer and the bearing edge chamfer have no abnormal damage or deformation.
[0048] 2. Critical Dimension Inspection. Nine points (typically distributed in a 3x3 matrix) are evenly selected on the surface of each main thrust bearing, and the bearing height corresponding to each of the nine points is recorded. The height of each main thrust bearing is the average of the nine points, and the flatness is the difference between the maximum and minimum values. The standards are as follows:
[0049] ● Flatness should be ≤0.02mm.
[0050] ● The height difference between each tile (the difference between the average heights of each tile) is ≤0.15mm.
[0051] ●The surface roughness of the tile is only recorded.
[0052] • The contact area of the tile surface is ≥75%.
[0053] • The high points should be evenly distributed after scraping; the recommended density of high points is 10-12 per inch (reference value, not a performance requirement).
[0054] 3. Non-destructive testing only needs to meet the relevant standard requirements.
[0055] III. Inspection of Auxiliary Thrust Bearings
[0056] 1. Visual inspection: Inspect for wear and tear. Standards are as follows:
[0057] • The tile surface shows no black discoloration caused by tar;
[0058] • No obvious large-area indentations on the tile surface;
[0059] ●The tile surface has no Babbitt metal layer, and there is extensive wear, peeling, or surface cracks.
[0060] ●No signs of cavitation on the tile surface;
[0061] • The tile surface has no large spherical inclusions;
[0062] • No flash on the edge of the bearing;
[0063] ●The chamfered edges of the bearing bush show no abnormal damage or deformation.
[0064] 2. Critical Dimension Inspection. Nine points (typically distributed in a 3x3 matrix) are evenly selected on the surface of each auxiliary thrust bearing, and the bearing height corresponding to each of the nine points is recorded. The height of each auxiliary thrust bearing is the average of the nine points, and the flatness is the difference between the maximum and minimum values. The standards are as follows:
[0065] • Flatness should be ≤0.02mm.
[0066] • The height difference between each tile (the difference between the average heights of each tile) is ≤0.15mm.
[0067] ●The surface roughness of the tile is only recorded.
[0068] • The contact area of the tile surface is ≥75%.
[0069] ● The high points are evenly distributed after scraping; the recommended density of high points is 10-12 per inch (reference value, not a performance requirement).
[0070] 3. Non-destructive testing only needs to meet the relevant standard requirements.
[0071] IV. Guide Slab Inspection
[0072] 1. Visual inspection: Inspect for wear and tear. Standards are as follows:
[0073] • The tile surface shows no black discoloration caused by tar;
[0074] • No obvious large-area indentations on the tile surface;
[0075] ●The tile surface has no Babbitt metal layer, and there is extensive wear, peeling, or surface cracks.
[0076] ●No signs of cavitation on the tile surface;
[0077] • The tile surface has no large spherical inclusions;
[0078] • No flash on the edge of the bearing;
[0079] ●The chamfered edges of the bearing bush show no abnormal damage or deformation.
[0080] 2. Key Dimension Inspection. Surface roughness is only recorded.
[0081] 3. Non-destructive testing only needs to meet the relevant standard requirements.
[0082] V. Thrust plate inspection
[0083] 1. Visual inspection: Inspect for wear and tear. Standards are as follows:
[0084] ● No large-area wear on the surface;
[0085] ● No obvious high points on the surface;
[0086] 2. Critical Dimension Inspection. Take six measurement points at 60° intervals along the circumference of the thrust plate and record the corresponding thrust plate height at each of the six points. The standards are as follows:
[0087] • The thrust plate height is recorded only (155.96~156.00mm).
[0088] Surface roughness is only recorded.
[0089] 3. Non-destructive testing only needs to meet the relevant standard requirements.
[0090] Using gauge blocks, establish the reference height for the main thrust bearing and set up a dial indicator. Take measurement points and measure each main thrust bearing, recording the dial indicator reading at each point for each bearing. The height of each main thrust bearing is the average of nine points, and the flatness is the difference between the maximum and minimum values. Requirements: Flatness ≤ 0.02 mm, height difference between main thrust bearings ≤ 0.15 mm.
[0091] The measurement of the secondary thrust bearing is similar.
[0092] For the thrust plate, take measurement points (6 measurement points at 60° intervals along the circumference), measure the height using an outside micrometer and record it.
[0093] In practical applications, measurements of old tiles show that the flatness of the main thrust tile is mostly 0.02mm, and the height difference is mostly <0.05mm; the flatness of the secondary thrust tile is mostly 0.015mm, and the height difference is mostly less than 0.015mm; and the flatness of the thrust disc is mostly 0.01mm.
Claims
1. A method for inspecting oil-lubricated hydrodynamic sliding bearings in main pumps of nuclear power plants, characterized in that: Inspection objects: Main thrust bearings, auxiliary thrust bearings, guide bearings, and thrust discs of the main pump oil-lubricated hydrodynamic sliding bearings in nuclear power plants; each bearing set has 7 main thrust bearings, 10 auxiliary thrust bearings, 8 upper guide bearings, 5 lower guide bearings, and 1 thrust disc; inspection and evaluation are conducted through historical operation checks, visual inspections, critical dimension checks, and non-destructive testing. The historical operation check, visual inspection, and critical dimension check evaluation include: main pump historical operation check: the coasting curve during the start-up and shutdown phases of the main pump in the previous operating cycle should be normal, specifically, the coasting curve has no inflection point, and the coasting temperature rise is ≤5℃. The coasting curve is a temperature-time curve. Speed-time curve; Except for the coasting curve during start-stop, if any abnormalities are found in important parameters of historical operating data, they should be reviewed in detail to analyze the root cause of the abnormality and indicate whether it is related to the bearing capacity; Inspection of the main thrust bearing includes: visual inspection, visually checking for wear, with the following standards: no black discoloration caused by tar on the bearing surface; no obvious large-area indentations on the bearing surface; no large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the bearing surface; no cavitation marks on the bearing surface; no large spherical inclusions on the bearing surface; no flash on the bearing edge; no obvious wear near the top oil hole; no abnormal damage or deformation of the top oil hole chamfer and bearing edge chamfer. The main thrust bearing inspection also includes: critical dimension inspection, taking 9 points evenly distributed on the surface of each main thrust bearing in a 3*3 matrix, recording the bearing height corresponding to each of the 9 points, and taking the average of the 9 points for the height of each main thrust bearing. Flatness is taken as the difference between the maximum and minimum values. The inspection standards are as follows: flatness ≤ 0.02mm; difference in average height between bearings ≤ 0.15mm; only recording of surface roughness; bearing surface contact area ≥ 75%; uniform distribution of high points after scraping. The auxiliary thrust bearing inspection includes: visual inspection, visually checking for wear. The inspection standards are as follows: no wear caused by tar on the bearing surface. The bearing pads are black and discolored; there are no obvious large-area indentations on the surface; there is no large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the surface; there are no cavitation marks on the surface; there are no large spherical inclusions on the surface; there are no flashes on the bearing pad edges; there is no abnormal damage or deformation at the chamfers of the bearing pad edges; the inspection of the auxiliary thrust bearing pads also includes: key dimension inspection, taking 9 points evenly on the surface of each auxiliary thrust bearing pad, the 9 points being distributed in a 3*3 matrix, recording the bearing pad height corresponding to the 9 points, the height of each auxiliary thrust bearing pad being the average of its 9 points, and the flatness being the difference between the maximum and minimum values, the inspection standards are as follows: flatness should be ≤0.02mm; the difference in average height values of each pad ≤0.15mm; Surface roughness is recorded only; Surface contact area ≥75%; High points are evenly distributed after scraping; Guide tile inspection includes: visual inspection of wear, with the following standards: No black discoloration caused by tar on the surface; No obvious large-area indentations on the surface; No large-area wear, peeling, or surface cracks of the Babbitt alloy layer on the surface; No cavitation marks on the surface; No large spherical inclusions on the surface; No flash on the bearing edge; No abnormal damage or deformation at the bearing edge chamfer; Key dimensions of the guide tile inspection are checked, with the following standards: Surface roughness is recorded only.
2. The inspection method for oil-lubricated hydrodynamic sliding bearings of main pumps in nuclear power plants according to claim 1, characterized in that: It also includes thrust plate inspection, which includes: visual inspection, visually inspecting the wear condition, with the following inspection standards: no large-area wear on the surface; no obvious high points on the surface; key dimension inspection, taking 6 measurement points at 60° intervals along the circumference of the thrust plate, and recording the thrust plate height corresponding to the 6 points, with the following inspection standards: only the thrust plate height is recorded, and only the surface roughness is recorded.