A Repair Process for Spring Strap Support Mirror Plates During Class C Overhaul of Hydro-generator Units

Abstract

A repair process for the spring bundle support mirror plate during Class C maintenance of a hydro-generator unit includes the following steps: S1. Preparation for mirror plate repair; S2. Removal of thrust bearing components; S3. Determination of the mirror surface repair area; S4. Mirror surface repair treatment; S5. Reinstallation of thrust bearing components. This process repairs the mirror plate without removing it, saving maintenance time. After repair, the operational condition of the mirror plate is ensured, preventing minor defects from causing major malfunctions, thus guaranteeing the reliable operation of the unit and extending the service life of the mirror plate.

Description

Technical Field

[0001] This invention relates to the field of hydro-generator maintenance technology, and in particular to a repair process for the spring bundle support mirror plate of a hydro-generator in Class C maintenance. Background Technology

[0002] During prolonged operation of a hydro-generator unit, leaks from the oil cooler, paint flaking from the oil tank, residual weld beads, and iron filings can circulate with the oil and enter the space between the mirror plate and the thrust bearing, causing defects such as surface rust and scratches on the mirror plate surface. These scratches and surface rust pose a significant threat to the stable operation of the unit, necessitating mirror plate grinding. During A and B overhauls, components such as the upper frame, rotor, and thrust head are disassembled, and the mirror plate is lifted out with the mirror surface facing upwards. Special mirror plate grinding tools are then used to grind the mirror plate surface. The disassembly of components such as the upper frame, rotor, and thrust head requires substantial manpower and resources.

[0003] According to their support structures, thrust bearings of hydro-generator units can be classified into rigid supports, elastic oil tank supports, counterweight supports, double-pallet elastic beam supports, and spring-loaded supports. Analysis of the characteristics of various support structures revealed that when the distance between the spring-loaded support's mirror plate and the bottom of the oil tank is greater than 210 mm, the spring-loaded support can perform local repairs of the mirror plate within the oil tank. To save production costs, a repair process for the spring-loaded support mirror plate during Class C maintenance of hydro-generator units was designed. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the problems existing in the background technology mentioned above and provide a repair process for the spring bundle support mirror plate of a hydro-generator unit based on the C-level maintenance. By repairing the mirror plate through this process, it is not necessary to remove the mirror plate, which saves maintenance time. After the mirror plate is repaired, the operating condition of the mirror plate is guaranteed, and the mirror plate will not cause major failures due to minor defects, thus ensuring the reliable operation of the unit and extending the service life of the mirror plate.

[0005] To achieve the above-mentioned technical features, the objective of this invention is as follows: a repair process for a spring bundle support mirror plate during C-level overhaul of a hydro-generator unit, comprising the following steps:

[0006] S1. Preparations for mirror plate repair: Shut down the hydro-generator unit and perform rotor jacking and oil draining operations;

[0007] S2. Thrust bearing assembly removal: Remove the thrust bearing assembly to allow workers to enter the oil tank;

[0008] S3. Determining the repair area for the mirror plate: Clean the mirror surface of the mirror plate, check for defects such as streaks, loose threads, and rust, and mark the defects.

[0009] S4. Mirror Repair Treatment: Repair the mirror surface according to the different roughness of the mirror surface marking positions;

[0010] S5. Reinstallation of thrust bearing components.

[0011] In S1, the steps for preparing for mirror plate repair are as follows:

[0012] S11. Lift the rotor, set up a dial indicator to monitor the rotor lifting height, lift the rotor to a suitable height, and ensure that the thrust bearing and its support are ready for removal;

[0013] S12. Drain the turbine oil from the oil tank to ensure that the turbine oil in the oil tank will not overflow after the thrust bearing maintenance oil window is removed.

[0014] S13. Remove the thrust bearing inspection oil window and clean the residual oil in the oil tank;

[0015] S14. Remove the pipes and temperature measuring RTD accessories in the oil tank that affect the removal of the thrust bearing, and wrap each removed component with plastic film for protection.

[0016] In S2, the procedure for removing the thrust bearing assembly is as follows:

[0017] S21. Remove the thrust pad and thrust pad support, and thoroughly clean the oil tank and mirror surface with gasoline or anhydrous ethanol;

[0018] S22. Seal all gaps in the oil tank with masking tape, lay a thin film at the bottom of the oil tank to protect it, and fix the edges of the film to the oil tank wall. Lay wool felt on the film.

[0019] In S3, the steps for determining the mirror repair area of ​​the mirror plate are as follows:

[0020] S31. The worker lies flat on his back and enters the oil tank. He wipes the mirror surface with a cleaning cloth and checks for defects such as scratches or hanging threads. He touches the mirror surface to judge the degree of scratches by feel. He visually checks whether there is any surface rust on the mirror surface. He uses an oil-based marker to divide the work area on the mirror surface. He uses square grid lines to divide the work area. The grid line size is consistent with the length measured by the roughness tester. The grid lines are oriented towards the radius of the mirror plate.

[0021] S32. Use a roughness tester to measure and record the roughness of each grid mirror plate in the radial and circumferential directions.

[0022] In S4, when the roughness of the mirror plate is greater than or equal to 2.0µm, use a flashlight and a knife-edge ruler to check the marked high and low point areas, find the areas with scratches, hanging wires, and floating rust, and use a 120-grit polishing pad to perform pneumatic semi-finish polishing on the areas with deeper scratches, concentrated high points, scratches, hanging wires, and floating rust. After polishing, the surface color difference is uniform. The polishing line is in the circumferential rotation direction, and the polishing process must move back and forth. The polishing area is polished back and forth 15-25 times and the roughness is measured once. The measurement includes the radial direction and the circumferential direction.

[0023] In S4, when the roughness is between 1.7 and 2.0 µm, the mirror surface is pneumatically semi-finished using a 180# scouring pad, with the polishing path rotating in a circular direction. During the polishing process, the surface must be moved back and forth, and a roughness measurement is performed after 35-45 back-and-forth movements. The measurement includes both radial and circumferential directions.

[0024] In S4, when the roughness is between 0.8 and 1.7 µm, the mirror surface is manually polished with a 320-mesh scouring pad. The polishing path is in a circumferential rotation direction. The polishing process must involve moving back and forth. Roughness measurement is performed after 65-75 back-and-forth movements, including both radial and circumferential directions.

[0025] In S4, when the roughness after grinding and repair reaches less than 0.8µm, the grinding area is checked with a knife-edge ruler to ensure there are no high points, and the color of the ground area is visually uniform. The grinding and repair of the mirror plate is then completed, and the roughness of the ground area of ​​the mirror plate after repair is measured and recorded.

[0026] In S5, the reinstallation procedure for the thrust bearing components is as follows:

[0027] S51. Remove all protective materials from the oil tank and thoroughly clean the oil tank;

[0028] S52. Clean and inspect the surface of the thrust bearing for defects; otherwise, replace the thrust bearing, reinstall the thrust bearing support and thrust bearing, reinstall the high-pressure oil branch pipe, thrust bearing cooling oil branch pipe, thrust bearing RTD, and thrust bearing circumferential limit device, and perform final cleaning of the oil tank.

[0029] S53. Connect the high-pressure oil unloading system pipeline and conduct an oil injection test. Ensure that the oil output from each thrust bearing oil tank is uniform. Reinstall the thrust bearing inspection oil window and inject turbine oil into the oil tank until the oil level reaches the normal oil level of the oil tank.

[0030] The present invention has the following beneficial effects:

[0031] 1. When using the process described in this application to repair mirror plates, it is not necessary to dismantle the upper frame, rotor, thrust head, and other components, as well as the mirror plate itself, making it easier to implement and reducing the cost of mirror plate repair.

[0032] 2. Using the process described in this application to repair the mirror plate, the repair and grinding of the mirror plate can be completed in about 10 days. After grinding, the roughness of the mirror plate is between 0.2 and 0.8. There are no high points when checked with a knife edge ruler. The mirror surface color is uniform. The roughness and other indicators of the mirror plate after treatment meet the national standard requirements.

[0033] 3. By performing such online repairs on the mirror plate, the operating environment of the mirror plate is guaranteed, preventing minor defects from causing major malfunctions, ensuring the reliable operation of the unit, and extending the service life of the mirror plate. Attached Figure Description

[0034] Figure 1 This is a flowchart of the mirror plate repair process of the present invention. Detailed Implementation

[0035] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0036] See Figure 1 A repair process for spring bundle support mirror plates during Class C overhaul of hydro-generator units includes the following steps:

[0037] S1. Preparations for mirror plate repair: Shut down the hydro-generator unit and perform rotor jacking and oil draining operations;

[0038] S2. Thrust bearing assembly removal: Remove the thrust bearing assembly to allow workers to enter the oil tank;

[0039] S3. Determining the repair area for the mirror plate: Clean the mirror surface of the mirror plate, check for defects such as streaks, loose threads, and rust, and mark the defects.

[0040] S4. Mirror Repair Treatment: Repair the mirror surface according to the different roughness of the mirror surface marking positions;

[0041] S5. Reinstallation of thrust bearing components.

[0042] This process repairs the mirror plate without removing it, saving maintenance time. After repair, the mirror plate's operating condition is guaranteed, preventing minor defects from causing major malfunctions. This ensures the reliable operation of the unit and extends the lifespan of the mirror plate.

[0043] In S1, the steps for preparing for mirror plate repair are as follows:

[0044] S11. Lift the rotor, set up a dial indicator to monitor the rotor lifting height, lift the rotor to a suitable height, and ensure that the thrust bearing and its support are ready for removal;

[0045] S12. Drain the turbine oil from the oil tank to ensure that the turbine oil in the oil tank will not overflow after the thrust bearing maintenance oil window is removed.

[0046] S13. Remove the thrust bearing inspection oil window and clean the residual oil in the oil tank;

[0047] S14. Remove the pipes and temperature measuring RTD accessories in the oil tank that affect the removal of the thrust bearing, and wrap each removed component with plastic film for protection.

[0048] In S2, the procedure for removing the thrust bearing assembly is as follows:

[0049] S21. Remove the thrust pad and thrust pad support, and thoroughly clean the oil tank and mirror surface with gasoline or anhydrous ethanol;

[0050] S22. Seal all gaps in the oil tank with masking tape, lay a thin film at the bottom of the oil tank to protect it, and fix the edges of the film to the oil tank wall. Lay wool felt on the film.

[0051] In S3, the steps for determining the mirror repair area of ​​the mirror plate are as follows:

[0052] S31. The worker lies flat on his back and enters the oil tank. He wipes the mirror surface with a cleaning cloth and checks for defects such as scratches or hanging threads. He touches the mirror surface to judge the degree of scratches by feel. He visually checks whether there is any surface rust on the mirror surface. He uses an oil-based marker to divide the work area on the mirror surface. He uses square grid lines to divide the work area. The grid line size is consistent with the length measured by the roughness tester. The grid lines are oriented towards the radius of the mirror plate.

[0053] S32. Use a roughness tester to measure the roughness of each grid mirror plate in the radial and circumferential directions, and record it in Table 1.

[0054] Table 1. Roughness measurement of mirror plate before grinding

[0055]

[0056] In S4, the selection of mirror plate grinding tools is shown in Table 2.

[0057] Table 2 Selection of Mirror Plate Grinding Tools

[0058]

[0059] When the roughness of the mirror plate is greater than or equal to 2.0µm, use a flashlight and a ruler to check the marked high and low points, find the areas with scratches, hanging wires, and loose rust, and use a 120-grit polishing pad to perform pneumatic semi-finish polishing on the areas with deeper scratches, concentrated high points, scratches, hanging wires, and loose rust. After polishing, the surface color difference is uniform. The polishing path is in the circumferential rotation direction, and the polishing process must be moved back and forth. It is forbidden to fix the polishing tool in one position. The roughness is measured after polishing the area back and forth 15-25 times. The measurement includes the radial direction and the circumferential direction.

[0060] In S4, when the roughness is between 1.7 and 2.0 µm, the mirror surface is pneumatically semi-finished using a 180# scouring pad, with the polishing path rotating in a circular direction. During the polishing process, the surface must be moved back and forth, and the polishing tool must not be fixed in one position for grinding. The roughness is measured after 35-45 back-and-forth movements, including both radial and circumferential measurements.

[0061] In S4, when the roughness is between 0.8 and 1.7 µm, the mirror surface is manually polished with a 320-mesh scouring pad. The polishing path is in a circumferential rotation direction. The polishing process must involve moving back and forth. Roughness measurement is performed after 65-75 back-and-forth movements, including both radial and circumferential directions.

[0062] In S4, when the roughness after grinding repair reaches less than 0.8µm, the grinding area is checked with a knife-edge ruler to find no high points, and the color of the grinding area is visually uniform. The grinding repair of the mirror plate is then completed, and the roughness of the grinding area of ​​the mirror plate after repair is measured and recorded in Table 3.

[0063] Table 3. Roughness measurement of mirror plate after grinding

[0064]

[0065] In S5, the reinstallation procedure for the thrust bearing components is as follows:

[0066] S51. Remove all protective materials from the oil tank and thoroughly clean the oil tank;

[0067] S52. Clean and inspect the surface of the thrust bearing for defects; otherwise, replace the thrust bearing, reinstall the thrust bearing support and thrust bearing, reinstall the high-pressure oil branch pipe, thrust bearing cooling oil branch pipe, thrust bearing RTD, and thrust bearing circumferential limit device, and perform final cleaning of the oil tank.

[0068] S53. Connect the high-pressure oil unloading system pipeline and conduct an oil injection test. Ensure that the oil output from each thrust bearing oil tank is uniform. Reinstall the thrust bearing inspection oil window and inject turbine oil into the oil tank until the oil level reaches the normal oil level of the oil tank.

Claims

1. A repair process for spring bundle support mirror plates during Class C maintenance of hydro-generator units, characterized in that, Includes the following steps: S1. Preparations for mirror plate repair: Shut down the hydro-generator unit and perform rotor jacking and oil draining operations; S2. Thrust bearing assembly removal: Remove the thrust bearing assembly to allow workers to enter the oil tank; S3. Determining the repair area for the mirror plate: Clean the mirror surface of the mirror plate, check for defects such as streaks, loose threads, and rust, and mark the defects. S4. Mirror plate surface repair: Repair the mirror surface according to the different roughness of the mirror plate surface markings; S5. Reinstallation of thrust bearing components; In S3, the steps for determining the mirror repair area of ​​the mirror plate are as follows: S31. The worker lies flat on his back and enters the oil tank. He wipes the mirror surface with a cleaning cloth and checks for defects such as scratches or hanging threads. He touches the mirror surface to judge the degree of scratches by feel. He visually checks whether there is any surface rust on the mirror surface. He uses an oil-based marker to divide the work area on the mirror surface. He uses square grid lines to divide the work area. The size of the grid lines is consistent with the length measured by the roughness tester. The grid lines are oriented towards the radius of the mirror plate. S32. Use a roughness tester to measure and record the roughness of each grid mirror plate in the radial and circumferential directions; In S4, when the roughness of the mirror plate is greater than or equal to 2.0µm, use a flashlight and a knife-edge ruler to check the marked high and low point areas, find the areas with wire scratches, wire hanging, and floating rust, and use a 120-grit polishing pad to perform pneumatic semi-finish polishing on the areas with deeper scratches, concentrated high points, wire scratches, wire hanging, and floating rust. After polishing, the surface color difference is uniform. The polishing line is in the circumferential rotation direction, and the polishing process must move back and forth. The polishing area is polished back and forth 15-25 times and the roughness is measured once. The measurement includes the radial direction and the circumferential direction. When the roughness is between 1.7 and 2.0 µm, use a 180# scouring pad to perform pneumatic semi-finish polishing on the mirror surface. The polishing path is in the circumferential rotation direction. During the polishing process, the surface must be moved back and forth. Roughness measurement is performed after 35-45 back-and-forth movements. The measurement includes both radial and circumferential directions. When the roughness is between 0.8 and 1.7 µm, the mirror surface is manually polished with a 320-mesh scouring pad. The polishing path is in a circumferential rotation direction. During the polishing process, the surface must be moved back and forth. Roughness measurement is performed after 65-75 back-and-forth movements. The measurement includes both radial and circumferential directions. When the roughness after grinding and repair reaches less than 0.8µm, check the grinding area with a knife-edge ruler to ensure there are no high points, and visually inspect the grinding area for uniform color. The grinding and repair of the mirror plate is then complete. Measure and record the roughness of the ground area of ​​the mirror plate after repair.

2. The repair process for the spring bundle support mirror plate during C-level overhaul of a hydro-generator unit according to claim 1, characterized in that, In S1, the steps for preparing for mirror plate repair are as follows: S11. Lift the rotor, set up a dial indicator to monitor the rotor lifting height, lift the rotor to a suitable height, and ensure that the thrust bearing and its support are ready for removal; S12. Drain the turbine oil from the oil tank to ensure that the turbine oil in the oil tank will not overflow after the thrust bearing maintenance oil window is removed. S13. Remove the thrust bearing inspection oil window and clean the residual oil in the oil tank; S14. Remove the pipes and temperature measuring RTD accessories in the oil tank that affect the removal of the thrust bearing, and wrap each removed component with plastic film for protection.

3. The repair process for the spring bundle support mirror plate during C-level overhaul of a hydro-generator unit according to claim 1, characterized in that, In S2, the procedure for removing the thrust bearing assembly is as follows: S21. Remove the thrust pad and thrust pad support, and thoroughly clean the oil tank and mirror surface with gasoline or anhydrous ethanol; S22. Seal all gaps in the oil tank with masking tape, lay a thin film at the bottom of the oil tank to protect it, and fix the edges of the film to the oil tank wall. Lay wool felt on the film.

4. The repair process for the spring bundle support mirror plate during C-level overhaul of a hydro-generator unit according to claim 1, characterized in that, In S5, the reinstallation procedure for the thrust bearing components is as follows: S51. Remove all protective materials from the oil tank and thoroughly clean the oil tank; S52. Clean and inspect the surface of the thrust bearing for defects; otherwise, replace the thrust bearing, reinstall the thrust bearing support and thrust bearing, reinstall the high-pressure oil branch pipe, thrust bearing cooling oil branch pipe, thrust bearing RTD, and thrust bearing circumferential limit device, and perform final cleaning of the oil tank. S53. Connect the high-pressure oil unloading system pipeline and conduct an oil injection test. Ensure that the oil output from each thrust bearing oil tank is uniform. Reinstall the thrust bearing inspection oil window and inject turbine oil into the oil tank until the oil level reaches the normal oil level of the oil tank.

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