A method for repairing cavitation erosion of a hydraulic turbine and related devices

Abstract

The application provides a water turbine cavitation erosion repair method and related device, and belongs to the technical field of hydraulic machinery maintenance. When the evaluation result meets the requirements, the cavitation erosion part of the water turbine flow part is subjected to targeted replacement groove processing, and a targeted replacement groove is obtained. Based on the size of the cavitation erosion area of the water turbine flow part, a targeted replacement base plate is designed, and the surface of the targeted replacement base plate is subjected to laser cladding to obtain a laser cladding initial processing plate. According to the size of the targeted replacement groove, the laser cladding initial processing plate is processed to obtain a laser cladding targeted replacement plate. The laser cladding targeted replacement plate is welded with the replacement groove, and after the welding is completed, the part polished higher according to the water turbine streamline is polished, and the surface of the laser cladding targeted replacement plate is subjected to nondestructive testing at a set time. After the nondestructive testing is qualified, the repair of the cavitation erosion part of the water turbine flow part is completed. The application solves the problems of great implementation difficulty and low repair quality of the water turbine cavitation erosion repair.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic machinery repair and maintenance technology, specifically relating to a method and related device for repairing cavitation in water turbines. Background Technology

[0002] Due to limitations in hydraulic design and model testing, many prototype turbines develop cavitation or wear problems before reaching their major overhaul cycle after operation. Turbine runners, guide vanes, bottom rings, and other flow-through components are crucial parts of the unit. Due to water quality conditions or design limitations, long-term operation can lead to changes in surface structure dimensions caused by cavitation erosion and sediment abrasion, resulting in hydraulic instability and impacting the safe and stable operation of the unit. To ensure the turbine's operational stability during the overhaul cycle, online repair of worn and cavitated areas is essential. Common online repair methods include grinding, welding, and non-destructive testing of cavitated and worn areas. While these methods can ensure safe operation of the unit in the short term, the turbine's characteristics remain unchanged, leading to repeated cavitation and wear problems in the same locations. Furthermore, repeated repairs severely affect the turbine's service life.

[0003] The materials used to protect turbine runners must be approached from two aspects: first, finding alloy materials with good anti-corrosion properties; and second, surface treatment of the flow passages to improve their anti-corrosion performance. Laser cladding technology utilizes the extremely high energy concentration of a high-energy laser beam to instantly and completely melt alloy powder with special physical, chemical, or mechanical properties, either pre-placed on the substrate surface or automatically fed in sync with the laser. Simultaneously, the substrate partially melts, forming a new composite material. After scanning with the laser beam, it rapidly solidifies, obtaining a dense coating metallurgically bonded to the substrate, thus achieving the purpose of restoring geometric dimensions and surface strengthening.

[0004] Currently, there are many patents and reports on the use of laser cladding technology to prepare wear-resistant and corrosion-resistant alloy coatings for equipment components.

[0005] Chinese patent application publication number CN101994112A discloses a laser cladding process for a wear-resistant and corrosion-resistant alloy coating on a turbine runner. The process selects iron-based alloy powder, uses laser equipment and an adjustable automatic powder feeding device to make the alloy powder from the automatic powder feeding head fall into the laser molten pool. By adjusting the powder feeding amount, a uniform and dense laser cladding layer is formed on the upper and lower crown surfaces, with a thickness of 0.2-1.8 mm.

[0006] Chinese patent application publication number CN101994113A discloses a laser cladding process for a wear-resistant and corrosion-resistant coating on the top cover of a hydro turbine unit. The process uses nickel-based welding wire to weld a beveled process ring at the right angle where the inner ring surface of the leak-proof ring and the wear-resistant plane of the top cover intersect. Iron-based alloy powder is selected, and laser equipment and an automatic powder feeding device are used to make the alloy powder from the automatic powder feeding head fall into the laser molten pool. The powder feeding amount is adjusted so that the thickness of the alloy powder coating reaches 0.2-1.8mm.

[0007] Chinese patent application publication number CN108034941A discloses a laser cladding construction method for anti-cavitation of water pump turbines applicable to power plant sites. The steps include: pre-repair inspection and recording; cleaning the surface of the water pump turbine blades and marking the laser cladding area; grinding, repairing, fine welding, and fine repairing the laser cladding area on the water pump turbine blades, and performing blade surface activation treatment; installing and debugging the cladding system; and performing cladding.

[0008] Chinese patent application CN117226420A discloses an online repair method for cavitation damage of a turbine runner. The method includes: S1: Equipment installation; S2: Surface cleaning and drying: using a cleaning agent to remove oil and dirt from the runner, and using a heating belt-type local heating device to heat the surface of the runner blades; S3: Damage recording: performing 100% PT flaw detection on the runner surface, recording and marking the distribution, size, and type of damage; S4: Pre-welding cleaning; S5: Pre-welding preheating; S6: Repairing martensitic stainless steel ZG0... Damage to different sizes of turbine runners made of Cr13Ni5Mo and ZG0Cr16Ni5Mo materials is repaired by overlay welding; S7: stress-relief annealing; S8: surface polishing; S9: quality inspection; by combining three repair methods—manual electric welding, tungsten inert gas welding, and laser additive manufacturing—online repair of the turbine runner without disassembly is achieved on-site. This solves the problem of abrasion damage to the flow components of mixed-flow units in medium- and high-head hydropower stations, improves the cavitation resistance of the turbine runner surface, reduces turbine failures, shortens maintenance cycles, lowers maintenance costs, and improves repair efficiency.

[0009] The above patents mainly describe the general process flow for laser cladding repair of the surfaces of turbine runners, top covers, and other flow-through components. Both offline and online methods are used, but all involve direct surface cladding of the flow-through surfaces by laser cladding equipment. This construction method has certain technical difficulties and drawbacks. First, due to the complex structure and large size variations of turbines, and the uncertain areas where cavitation damage occurs, the area that laser cladding equipment can operate on is limited, resulting in poor applicability and consequently, low precision in turbine cavitation repair. Second, online turbine repair is generally carried out on the turbine runner maintenance platform, requiring consideration of the installation and layout of the laser cladding equipment and the platform's load-bearing capacity, posing certain safety risks and resulting in a long equipment installation and commissioning cycle. Furthermore, the uncertain surface location during on-site construction (potentially the upper surface or an inclined surface), coupled with the harsh on-site environment, makes quality control and inspection of the laser cladding layer difficult. Summary of the Invention

[0010] The purpose of this invention is to provide a method and related apparatus for repairing cavitation in water turbines, which solves the problems of high implementation difficulty and low repair quality in the prior art for repairing cavitation in water turbines.

[0011] To achieve the above objectives, the present invention adopts the following technical solution:

[0012] In a first aspect, the present invention provides a method for repairing cavitation erosion in a hydraulic turbine, comprising the following steps:

[0013] Obtain the cavitation condition and original dimensions of the turbine's flow-through components;

[0014] Based on the cavitation condition of the turbine's flow-through components, the size of the cavitation area of ​​the turbine's flow-through components is determined, and based on the size of the cavitation area of ​​the turbine's flow-through components, the shape and size of the surface laser cladding targeted repair area are preliminarily determined;

[0015] Based on the original dimensions of the turbine's flow-through components and the shape and size of the laser cladding targeted repair area on the surface, the feasibility of laser cladding targeted repair was evaluated, and the evaluation results were obtained.

[0016] When the evaluation results meet the requirements, the cavitation parts of the turbine flow components are processed with targeted replacement grooves to obtain targeted replacement grooves.

[0017] Based on the dimensions of the cavitation area of ​​the turbine's flow components, a targeted replacement base plate was designed, and the surface of the targeted replacement base plate was laser clad to obtain a laser clad preliminary processing plate.

[0018] Based on the dimensions of the targeted replacement groove, the laser cladding pre-processing plate is processed to obtain the laser cladding targeted replacement plate;

[0019] The laser cladding targeted replacement plate is welded to the replacement groove. After welding, the raised part is ground according to the turbine flow line. The surface of the laser cladding targeted replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

[0020] A further improvement of the present invention is that the turbine flow passage components include a runner, guide vanes, and a bottom ring.

[0021] A further improvement of the present invention is that the surface laser cladding targeted repair area is a rectangle, a circle, or an ellipse with an arc.

[0022] A further improvement of the present invention is that the processing of the laser cladding pre-processing plate specifically includes:

[0023] The bottom and top surfaces of the laser cladding pre-processing plate are processed, and the sides of the laser cladding pre-processing plate are processed into bevel surfaces with a set slope.

[0024] A further improvement of the present invention is that the welding of the laser cladding target replacement plate to the replacement groove is specifically performed by using argon arc welding or electric arc welding to weld the laser cladding target replacement plate to the replacement groove.

[0025] A further improvement of the present invention is that the welding method is layered symmetrical welding.

[0026] A further improvement of the present invention is that the non-destructive testing includes PT (Penetrant Testing) non-destructive testing and MT (Magnetic Particle Testing) non-destructive testing.

[0027] Secondly, the present invention provides a hydraulic turbine cavitation repair system, comprising:

[0028] The data acquisition module is used to acquire the cavitation condition and original dimensions of the turbine's flow-through components.

[0029] The size determination module is used to determine the size of the cavitation area of ​​the turbine's flow-through components based on the cavitation condition of the turbine's flow-through components, and to preliminarily determine the shape and size of the surface laser cladding targeted repair area based on the size of the cavitation area of ​​the turbine's flow-through components;

[0030] The feasibility assessment module is used to assess the feasibility of laser cladding targeted repair based on the original dimensions of the turbine flow components and the shape and size of the surface laser cladding targeted repair area, and obtain the assessment results;

[0031] The targeted replacement groove processing module is used to perform targeted replacement groove processing on the cavitation parts of the turbine flow components when the evaluation results meet the requirements, so as to obtain targeted replacement grooves.

[0032] The laser cladding preliminary processing plate acquisition module is used to design a targeted replacement base plate based on the size of the cavitation area of ​​the turbine flow component, and to perform surface laser cladding on the targeted replacement base plate to obtain the laser cladding preliminary processing plate;

[0033] The laser cladding pre-processing plate processing module is used to process the laser cladding pre-processing plate according to the size of the target replacement groove to obtain the laser cladding target replacement plate;

[0034] The repair module is used to weld the laser cladding target replacement plate to the replacement groove. After welding, the raised part is ground according to the turbine flow line, and the surface of the laser cladding target replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

[0035] Thirdly, the present invention provides an electronic device, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the above-described turbine cavitation repair method.

[0036] Fourthly, the present invention provides a storage medium storing a computer program thereon, which, when executed by a processor, implements the steps of the above-described turbine cavitation repair method.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The turbine cavitation repair method proposed in this invention employs a targeted replacement approach, replacing the surface of the severely cavitation-damaged base material with a laser cladding layer material exhibiting high abrasion resistance. This improves the local surface mechanical properties and abrasion resistance of the turbine, eliminating the need for on-site laser cladding equipment. It features low construction difficulty, short construction period, low construction safety risk, and wide applicability. It can solve the problem of localized cavitation caused by design flaws, avoid the risk of structural strength reduction due to component cavitation, and improve the operational safety of turbine flow components. Furthermore, when the evaluation results meet the requirements, targeted replacement grooves are machined on the cavitation areas of the turbine flow components to obtain these grooves. Laser cladding targeted replacement blocks are then manufactured in the factory according to the groove dimensions and welded onto the grooves. Since the laser cladding targeted replacement plates can be manufactured in the factory, the manufacturing quality of the laser cladding layer is effectively guaranteed, production efficiency is improved, and the maintenance schedule is not affected. Simultaneously, because welding is performed on the surface of the base material, the welding volume of the targeted replacement plates is small, minimizing the impact on the base material and reducing the likelihood of cracking defects during welding. Moreover, the method proposed in this invention does not require repeated welding of the underlying base material. It can be repeatedly repaired in the cavitation damage area (cavitation area of ​​the turbine flow component) without affecting the performance of the base material. Compared with traditional repair methods, it greatly reduces the impact on the base material and improves the service life of the turbine. Attached Figure Description

[0039] Figure 1 This is a flowchart of the turbine cavitation repair method of the present invention;

[0040] Figure 2 This is a schematic diagram of the turbine cavitation repair system of the present invention;

[0041] Figure 3 This is a flowchart of the turbine cavitation repair method in Embodiment 4 of the present invention;

[0042] Figure 4 This is a schematic diagram of the planar repair of crown cavitation on the turbine in Embodiment 4 of the present invention;

[0043] Figure 5 This is a schematic cross-sectional view of the crown cavitation repair on the runner in Embodiment 4 of the present invention;

[0044] Figure 6 This is a schematic diagram of the cavitation repair range design in Embodiment 4 of the present invention;

[0045] Figure 7 This is a schematic diagram of the targeted replacement groove construction process in Embodiment 4 of the present invention;

[0046] Figure 8 This is a schematic diagram of the plan and cross-section of the rectangular targeted replacement groove in Embodiment 4 of the present invention;

[0047] Figure 9 This is a schematic diagram of the laser cladding targeted replacement plate processing in Embodiment 4 of the present invention;

[0048] Figure 10 This is a schematic diagram of the curvature of the surface to be clad in Embodiment 4 of the present invention;

[0049] Figure 11 This is a schematic diagram of the plan and cross-section of the laser cladding targeted replacement plate in Embodiment 4 of the present invention;

[0050] Figure 12 This is a schematic diagram of the welding plane and cross-section of the laser cladding targeted replacement plate in Embodiment 4 of the present invention;

[0051] Figure 13 This is a schematic diagram of the structure of the electronic device of the present invention;

[0052] In the diagram: 1. Boundary line of the targeted replacement groove; 2. Boundary line of the targeted replacement plate; 3. Boundary line of the laser cladding layer; 4. Cavitation damage area; 5. Base material; 51. Grinding area of ​​the weld bevel of the targeted replacement groove; 52. Welding repair area of ​​the targeted replacement groove; 6. Targeted replacement groove; 61. Bottom surface of the targeted replacement groove; 62. Weld bevel of the targeted replacement groove; 7. Targeted replacement base plate; 8. Laser cladding initial processing plate; 81. Grinding area of ​​the laser cladding initial processing plate; 9. Laser cladding targeted replacement plate; 91. Laser cladding layer; 92. Weld bevel of the laser cladding targeted replacement plate; 10. V-shaped weld; 11. Upper crown of the rotor; 12. Rotor blade; 13. Cavitation damage area of ​​the rotor. Detailed Implementation

[0053] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0054] Example 1:

[0055] The flowchart of the turbine cavitation repair method of the present invention is as follows: Figure 1 As shown, the turbine cavitation repair method of the present invention includes the following steps:

[0056] S1. Obtain the cavitation condition and original dimensions of the turbine's flow-through components;

[0057] S2. Based on the cavitation condition of the turbine's flow-through components, determine the size of the cavitation area of ​​the turbine's flow-through components, and based on the size of the cavitation area of ​​the turbine's flow-through components, preliminarily determine the shape and size of the surface laser cladding targeted repair area;

[0058] S3. Based on the original dimensions of the turbine's flow-through components and the shape and size of the laser cladding targeted repair area on the surface, the feasibility of laser cladding targeted repair is evaluated, and the evaluation results are obtained;

[0059] S4. When the evaluation results meet the requirements, the cavitation parts of the turbine flow components are processed with targeted replacement grooves to obtain targeted replacement grooves;

[0060] S5. Based on the dimensions of the cavitation area of ​​the turbine's flow components, a targeted replacement base plate is designed, and the surface of the targeted replacement base plate is laser-clad to obtain a laser-clad preliminary processing plate;

[0061] S6. Process the laser cladding pre-processing plate according to the size of the target replacement groove to obtain the laser cladding target replacement plate;

[0062] S7. Weld the laser cladding target replacement plate to the replacement groove. After welding, grind the raised part according to the turbine flow line, and perform non-destructive testing on the surface of the laser cladding target replacement plate at a set time. After the non-destructive testing is qualified, the repair of the cavitation part of the turbine flow component is completed.

[0063] Example 2:

[0064] A schematic diagram of the turbine cavitation repair system of the present invention is shown below. Figure 2 As shown, the turbine cavitation repair system of the present invention includes:

[0065] The data acquisition module is used to acquire the cavitation condition and original dimensions of the turbine's flow-through components.

[0066] The size determination module is used to determine the size of the cavitation area of ​​the turbine's flow-through components based on the cavitation condition of the turbine's flow-through components, and to preliminarily determine the shape and size of the surface laser cladding targeted repair area based on the size of the cavitation area of ​​the turbine's flow-through components;

[0067] The feasibility assessment module is used to assess the feasibility of laser cladding targeted repair based on the original dimensions of the turbine flow components and the shape and size of the surface laser cladding targeted repair area, and obtain the assessment results;

[0068] The targeted replacement groove processing module is used to perform targeted replacement groove processing on the cavitation parts of the turbine flow components when the evaluation results meet the requirements, so as to obtain targeted replacement grooves.

[0069] The laser cladding preliminary processing plate acquisition module is used to design a targeted replacement base plate based on the size of the cavitation area of ​​the turbine flow component, and to perform surface laser cladding on the targeted replacement base plate to obtain the laser cladding preliminary processing plate;

[0070] The laser cladding pre-processing plate processing module is used to process the laser cladding pre-processing plate according to the size of the target replacement groove to obtain the laser cladding target replacement plate;

[0071] The repair module is used to weld the laser cladding target replacement plate to the replacement groove. After welding, the raised part is ground according to the turbine flow line, and the surface of the laser cladding target replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

[0072] Example 3:

[0073] The flowchart of the turbine cavitation repair method of the present invention is as follows: Figure 3 As shown, the turbine cavitation repair method of the present invention includes the following steps:

[0074] S1. Obtain the cavitation condition and original dimensions of the turbine's flow-through components.

[0075] First, obtain the cavitation condition and original dimensions of the turbine's flow-through components (including the runner, guide vanes, and bottom ring).

[0076] S2. Based on the cavitation condition of the turbine's flow-through components, determine the size of the cavitation area of ​​the turbine's flow-through components, and based on the size of the cavitation area of ​​the turbine's flow-through components, preliminarily determine the shape and size of the surface laser cladding targeted repair area.

[0077] In this step, the surface laser cladding targeted repair area is shaped like a rectangle with an arc, a circle, or an ellipse.

[0078] S3. Based on the original dimensions of the turbine flow components and the shape and size of the laser cladding targeted repair area on the surface, the feasibility of laser cladding targeted repair is evaluated, and the evaluation results are obtained.

[0079] The following is a detailed explanation of this step:

[0080] A feasibility assessment of laser cladding targeted repair was conducted based on the original dimensions of the turbine's flow components and the shape and size of the surface laser cladding targeted repair area. The repair area is generally subjected to relatively small alternating stress, and simulation analysis shows that the repair scheme will not affect the structural strength of the area.

[0081] The dimensions of the repaired area generally meet the following conditions: 1) The thickness of the cavitation erosion area is relatively large, generally greater than 30mm; 2) The area of ​​the cavitation erosion region is relatively small, generally less than 100mm in width and less than 200mm in length, or the total area is less than 20,000mm². 2 3) The cavitation area has space for manual grinding and welding.

[0082] S4. When the evaluation results meet the requirements, the cavitation parts of the turbine flow components are processed with targeted replacement grooves to obtain targeted replacement grooves.

[0083] The following is a detailed explanation of this step:

[0084] For the treatment of cavitation areas on the rotor, the damaged base material is removed by arc gouging or grinding. After grinding to a smooth metal surface, non-destructive testing of the surface is carried out using PT or MT methods until no defects are found. Then, the shape of the initially designed repair surface is reviewed, and welding and secondary grinding are performed to obtain a flat bottom surface and a weld bevel. Finally, a targeted replacement groove with a trapezoidal cross-section is formed, and the plane dimensions and depth of the replacement groove are accurately measured.

[0085] S5. Based on the dimensions of the cavitation area of ​​the turbine's flow components, a targeted replacement base plate is designed, and the surface of the targeted replacement base plate is laser-clad to obtain a laser-clad preliminary processing plate.

[0086] The following is a detailed explanation of this step:

[0087] Based on the measured dimensions of the cavitation erosion area, a targeted replacement base plate is designed, and surface laser cladding is performed to obtain a laser-clad preliminary processing plate. The laser cladding area covers the cavitation erosion area with a 10% redundancy. Laser cladding on the targeted replacement plate is carried out in a factory or laboratory. The laser cladding system mainly includes a high-power fiber laser, a water-cooling system, a powder feeding system, and a preparation stage. Furthermore, different powder materials are designed according to the degree of cavitation erosion damage to ensure that the cladding layer has good anti-cavitation erosion performance. The laser cladding layer preparation process includes raw material preparation, single-layer cladding layer preparation, and multi-layer cladding layer preparation. To reduce cladding plate deformation, methods such as controlling the interlayer temperature and pre-setting curvature are used to reduce the amount of cladding layer deformation.

[0088] S6. Process the laser cladding pre-processing plate according to the size of the target replacement groove to obtain the laser cladding target replacement plate.

[0089] The laser cladding pre-processing plate is processed, specifically including:

[0090] The bottom and top surfaces of the laser cladding pre-processing plate are processed to make it flat and smooth, and the sides of the laser cladding pre-processing plate are processed into a predetermined range (in this embodiment, the predetermined range is 30). -60 The bevel face of the slope.

[0091] The following is a detailed explanation of this step:

[0092] Based on the dimensions of the target replacement groove, the laser cladding initial processing plate is processed to produce a laser cladding target replacement plate. After installation, the width of the weld seam reserved around the plate is uniform, and the bottom of the replacement plate fits the replacement groove. After installation, it is about 0.5 to 1 mm higher than the original streamline.

[0093] S7. Weld the laser cladding target replacement plate to the replacement groove. After welding, grind the raised part according to the turbine flow line, and perform non-destructive testing on the surface of the laser cladding target replacement plate at a set time. After the non-destructive testing is qualified, the repair of the cavitation part of the turbine flow component is completed.

[0094] The laser cladding targeted replacement plate is welded to the replacement groove. After welding, the raised part is ground according to the turbine flow line. At a set time (24 hours in this embodiment, the set time can be adjusted according to actual needs), non-destructive testing (including PT non-destructive testing and MT non-destructive testing) is carried out on the surface of the laser cladding targeted replacement plate. After the non-destructive testing is qualified, the repair of the cavitation part of the turbine flow component is completed.

[0095] The laser cladding target replacement plate is welded to the replacement groove. Specifically, the laser cladding target replacement plate is welded to the replacement groove using argon arc welding or electric arc welding (the welding method is layered symmetrical welding).

[0096] The following is a detailed explanation of this step:

[0097] The laser-clad targeted replacement plate is welded to the replacement groove using argon arc welding or electric arc welding. The raised portion is then ground according to the turbine's flow lines to ensure a smooth transition. After welding, the surface of the laser-clad targeted replacement plate undergoes non-destructive testing for 24 hours. Once the non-destructive testing is passed, the repair of cavitation areas in the turbine's flow components is completed.

[0098] After completing step S7, regularly check the operation of the repaired area. If cavitation recurs in the original cavitation area, adjust the laser cladding material and process, cut the original replacement plate, and re-repair. Because the replacement groove is shallow and the bottom remains unchanged, the secondary repair process is faster and has less impact on the base material than the first one.

[0099] Example 4:

[0100] The flowchart of the turbine cavitation repair method of the present invention is as follows: Figure 3 As shown, the turbine cavitation repair method of the present invention includes the following steps:

[0101] The method of the present invention will be described in detail below using a large mixed-flow hydropower unit as an example:

[0102] A large mixed-flow hydroelectric generator unit has a single-unit capacity of 600MW, a turbine runner diameter of 6000mm, a height of 2500mm, and a total of 15 blades. During a minor overhaul, severe cavitation erosion was found on the runner crown 11. The cavitation damage area 13 occurred between the runner blades 12, with a total of 14 cavitation points. Each cavitation point measures approximately 150mm × 80mm (length × width), with a maximum cavitation depth of approximately 5mm. Due to the deep cavitation depth, to ensure stable operation of the turbine in the next overhaul cycle, the cavitation damage area needs to be repaired. The repair method proposed in this invention is proposed, and the main steps are described below:

[0103] Step S1: Measurement of cavitation erosion area and preliminary design of repair shape

[0104] During turbine overhaul, the dimensions of the cavitation damage area 13 on the runner were measured and recorded. A preliminary design for the shape and size of the targeted surface laser cladding repair area was then developed. Based on measurements, the cavitation damage area is approximately band-shaped, measuring approximately 150mm × 80mm (length × width), with a maximum depth of 5mm. The preliminary repair shape design adopts a rectangular structure (e.g., ...). Figure 6 As shown), the boundary line 1 of the target replacement groove, the boundary line 2 of the target replacement plate, and the boundary line 3 of the laser cladding layer are determined. The maximum groove size is 220mm×150mm×8mm (length×width×depth), of which the laser cladding layer range is 170mm×100mm (length×width).

[0105] Step S2: Feasibility assessment of laser cladding targeted repair

[0106] According to the design drawings (such as...) Figure 4 and Figure 5 As shown, the cavitation area 13 has a base material thickness of approximately 50-60 mm. A feasibility assessment of laser cladding targeted repair was conducted based on the original dimensions of the turbine's flow components. The repair area generally experiences relatively low alternating stress. Simulation analysis confirmed that the structural strength of this area meets the usage requirements for the repair scheme. Furthermore, the cavitation area is located between two blades, and due to the large size of the turbine runner, there is sufficient space in this area for grinding, welding, and other operations. Therefore, this method is feasible.

[0107] Step S3: Targeted replacement groove processing

[0108] After determining the repair method, treat the cavitation erosion areas of the runner (such as...). Figure 7As shown), the base material 5 is cleaned by arc gouging to remove the cavitation damage area 4. After grinding to a smooth metal surface, the base material 5 is subjected to non-destructive testing using PT or MT methods until no defects are found. Then, the shape of the initially designed repair surface is reviewed, and the targeted replacement groove welding area 52 is welded. The targeted replacement groove weld bevel grinding area 51 is ground a second time to obtain a flat targeted replacement groove bottom surface 61 and a targeted replacement groove weld bevel 62, finally forming a targeted replacement groove 6 with a trapezoidal cross-section (as shown). Figure 8 As shown), and accurately measure the plane dimensions and depth of the replacement groove (a=150mm, b=220mm, h1=8mm, α=120°).

[0109] Step S4: Fabrication of laser cladding pre-processed plate

[0110] Based on the measured dimensions of the cavitation area, a targeted replacement base plate 7 (e.g.) was designed. Figure 9 As shown), the base plate is 208mm long, 138mm wide, and 9mm high, with a laser cladding area depth of 3mm. Surface laser cladding is then completed, resulting in a laser-clad preliminary processing plate 8. The laser cladding area covers the cavitation area, the non-laser cladding layer range is 174mm × 104mm (length × width), and the laser cladding layer thickness is greater than 3mm.

[0111] Preferably, the laser cladding process on the targeted replacement base plate 7 is performed in a factory or laboratory. The laser cladding system mainly includes a high-power fiber laser, a water cooling system, a powder feeding system, and a preparation worktable. The laser's performance parameters include: adjustable laser power from 0-3300W, a spot diameter of 2mm, an operating voltage of 220V, a laser focal length of 65±0.2mm, and a laser chiller operating temperature of 24±0.5℃. The fiber laser serves as the heat source, internally converting electrical energy into laser light before outputting it through the fiber optic cable. The laser's on / off state and power are adjusted via a control box. The water cooling system consists of two subsystems: laser head cooling and laser cooling. The system uses circulating water to maintain the temperature within a specific range. Furthermore, the water cooling system's filtration device ensures the cleanliness and stability of the instrument's internal components. The powder feeding system uses a pneumatic powder feeding method. The cladding powder is fed to the laser head through a powder feeding tube under the influence of airflow, using nitrogen as the powder feeding gas. To protect the molten pool and the lens during the preparation process, a protective gas must be activated; the protective gas used is the inert gas argon.

[0112] (1) Selection of alloy powder

[0113] Nickel-based alloy powder with excellent cavitation erosion resistance and good metallurgical compatibility with the matrix was selected. The chemical composition of the nickel-based alloy powder, by weight percentage, is: Cr: 16.0%, W: 6.5%, Co: 10.0%, B: 2.8%, Si: 3.8%, C: 0.5%, Fe: ≤2.5%, O: <0.03%, with the balance being Ni. Adding Co to the material improves its corrosion resistance and fatigue resistance, and enhances the matrix's cavitation erosion resistance through solid solution strengthening and the formation of intermetallic compounds (such as Co-Cr and Co-W).

[0114] (2) The laser cladding layer preparation process for the targeted replacement plate is as follows:

[0115] 1) Raw material preparation: First, prepare mixed powder according to the designed alloy powder material, and mix it using a powder mixer for 2-4 hours; then place the laser cladding powder in a drying oven to dry at a temperature of 140-160℃ for 4-6 hours. In this embodiment, the material of the wheel to be repaired is 0Cr13Ni5Mo. Prepare a piece of 0Cr13Ni5Mo steel plate, and machine the base plate of the target replacement plate according to the size requirements of the target replacement plate.

[0116] 2) The process steps for preparing the cladding layer are as follows:

[0117] ① Use an angle grinder to remove the oxide layer from the surface to be clad.

[0118] ② Preheat the cladding base plate to 200℃-250℃ for 4 hours. Preheating the cladding base plate can effectively prevent cracking of the cladding layer.

[0119] ③ The preheated cladding base plate is fixed on the cladding worktable. A laser cladding layer is prepared using a laser cladding system. The thickness of a single cladding layer is controlled at 800-1000μm. After cladding a single layer, surface impurities are cleaned and cladding continues until the cladding layer thickness reaches 3.5-4mm, leaving a certain allowance for finishing. The cladding process parameters are as follows: laser power P = 3300W, scanning speed V = 10cm / s, powder feeding speed 45g / min, and step rate 0.7mm.

[0120] To reduce deformation of the cladding plate, this embodiment proposes the following methods:

[0121] 1. Control the temperature between cladding layers. After cladding a single layer, air cool the cladding layer to below 80°C to prevent excessive heat input.

[0122] 2. Targeted replacement of the base plate laser cladding: The surface to be clad is designed with a slightly convex shape. By pre-setting curvature to compensate for shrinkage deformation, it approaches a flat surface or a slightly concave surface after cooling, which can significantly reduce the deformation of the cladding layer. The formula for calculating the radius of curvature R is established as follows:

[0123]

[0124] in, k 1 represents the empirical coefficient. k 2 represents the ratio of the elastic model of the substrate to that of the cladding layer sample. h cladding thickness, α Difference in thermal expansion coefficients (cladding layer and substrate). ΔT Cooling temperature difference, ν Poisson's ratio, in this implementation case the curvature R value is set to 300mm, such as Figure 10 As shown.

[0125] Step S5: Laser cladding targeted replacement plate finishing

[0126] Based on the size of the targeted replacement groove, the laser cladding pre-processing plate 8 is processed, including processing its bottom surface, cladding layer surface, and welding bevel surface. Figure 9 The laser cladding initial processing plate (represented by polishing area 81) is used to produce the laser cladding targeted replacement plate 9 (e.g., the laser cladding target replacement plate 9 is made by grinding the initial processing area 81). Figure 11 As shown), length n=206mm, width m=136mm, transition zone c=10mm, weld bevel ( Figure 11 The laser cladding targeted replacement plate (represented by weld bevel 92) has a bevel angle of β=120°, a height of h2=9mm, and a laser cladding layer 91 thickness of approximately 3mm. After the laser cladding targeted replacement plate 9 is positioned with the targeted replacement groove 6, there is approximately 1mm of welding deformation and grinding adjustment allowance. After installation, the V-shaped weld 10 (in this embodiment, the weld can also be U-shaped) reserved around the perimeter of the replacement plate has an opening size of d=12mm, a 2mm blunt edge at the bottom, and the bottom of the replacement plate fits snugly against the replacement groove. After installation, it protrudes approximately 0.5-1mm above the original streamline.

[0127] Step S6: Perform laser cladding targeted replacement plate welding.

[0128] The laser cladding target replacement plate 9 is welded to the target replacement groove 6 using argon arc welding or electric arc welding (e.g., Figure 12 As shown in the figure, layered symmetrical welding is used during welding to control deformation. After welding, the raised part is ground according to the turbine streamline to ensure a smooth transition of the streamline. 24 hours after welding, the surface of the laser cladding targeted replacement plate 9 is subjected to PT and MT non-destructive testing. After passing the inspection, the cavitation area is repaired.

[0129] Example 5:

[0130] Please see Figure 13As shown, the present invention also provides an electronic device 100 for a method of repairing cavitation in water turbines; the electronic device 100 includes a memory 101, at least one processor 102, a computer program 103 stored in the memory 101 and executable on the at least one processor 102, and at least one communication bus 104.

[0131] The memory 101 can be used to store the computer program 103. The processor 102 implements the steps of the turbine cavitation repair method described in Embodiment 1 by running or executing the computer program stored in the memory 101 and calling the data stored in the memory 101. The memory 101 may mainly include a program storage area and a data storage area. The program storage area may store the operating system, at least one application program required for a function (such as sound playback function, image playback function, etc.), etc.; the data storage area may store data created according to the use of the electronic device 100 (such as audio data), etc. In addition, the memory 101 may include non-volatile memory, such as hard disk, memory, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other non-volatile solid-state storage device.

[0132] The at least one processor 102 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor 102 may be a microprocessor or any conventional processor. The processor 102 is the control center of the electronic device 100, connecting various parts of the electronic device 100 via various interfaces and lines.

[0133] The memory 101 in the electronic device 100 stores multiple instructions to implement a method for repairing cavitation in a water turbine, and the processor 102 can execute the multiple instructions to achieve the following:

[0134] Obtain the cavitation condition and original dimensions of the turbine's flow-through components;

[0135] Based on the cavitation condition of the turbine's flow-through components, the size of the cavitation area of ​​the turbine's flow-through components is determined, and based on the size of the cavitation area of ​​the turbine's flow-through components, the shape and size of the surface laser cladding targeted repair area are preliminarily determined;

[0136] Based on the original dimensions of the turbine's flow-through components and the shape and size of the laser cladding targeted repair area on the surface, the feasibility of laser cladding targeted repair was evaluated, and the evaluation results were obtained.

[0137] When the evaluation results meet the requirements, the cavitation parts of the turbine flow components are processed with targeted replacement grooves to obtain targeted replacement grooves.

[0138] Based on the dimensions of the cavitation area of ​​the turbine's flow components, a targeted replacement base plate was designed, and the surface of the targeted replacement base plate was laser clad to obtain a laser clad preliminary processing plate.

[0139] Based on the dimensions of the targeted replacement groove, the laser cladding pre-processing plate is processed to obtain the laser cladding targeted replacement plate;

[0140] The laser cladding targeted replacement plate is welded to the replacement groove. After welding, the raised part is ground according to the turbine flow line. The surface of the laser cladding targeted replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

[0141] Compared with the prior art, the present invention has the following beneficial effects:

[0142] (1) The method proposed in this invention has low construction difficulty. It is the first to propose the idea of ​​targeted replacement to replace the surface of the base material in the severely cavitation-damaged area with a laser cladding layer material with high anti-abrasion performance, which can effectively improve the anti-abrasion damage capability of the flow components. This method does not require on-site installation of laser cladding equipment, has low construction difficulty, short construction period, and low construction safety risk.

[0143] (2) The method proposed in this invention has a wide range of applications. This method can be applied to areas with thicker base material and limited space, and has a wide range of applications. It can solve the problem of local cavitation caused by design defects, avoid the risk of reduced structural strength due to cavitation of components, and improve the operational safety of components.

[0144] (3) The laser cladding layer manufactured by the method proposed in this invention has reliable manufacturing quality. Since the laser cladding target replacement plate can be manufactured in the factory, the manufacturing quality of the laser cladding layer can be effectively guaranteed, while greatly improving the manufacturing efficiency, without affecting the maintenance period, which is conducive to ensuring the power generation benefits of the power plant.

[0145] (4) The method proposed in this invention has little impact on the base material. Since the welding is performed on the surface of the base material, the amount of welding of the targeted replacement plate is small, which has little impact on the base material and is less likely to cause defects such as cracks.

[0146] (5) The method proposed in this invention can be repeatedly repaired in the cavitation-damaged area with high repair efficiency. Due to the anti-cavitation effect of the laser cladding layer, cavitation damage is greatly reduced, but it can also be repeatedly repaired in the same location depending on the operating conditions. Since the targeted replacement method is used, it is not necessary to repeatedly repair the underlying base material, which greatly reduces the impact on the base material compared with traditional repair methods, and the repair efficiency will also be improved.

[0147] Example 6:

[0148] If the modules / units integrated in the electronic device 100 are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or device capable of carrying the computer program code, a recording medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, and a read-only memory (ROM).

[0149] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0150] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1A device that provides the functions specified in one or more boxes.

[0151] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0152] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0153] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for repairing cavitation in a hydraulic turbine, characterized in that, Includes the following steps: Obtain the cavitation condition and original dimensions of the turbine's flow-through components; Based on the cavitation condition of the turbine's flow-through components, the size of the cavitation area of ​​the turbine's flow-through components is determined, and based on the size of the cavitation area of ​​the turbine's flow-through components, the shape and size of the surface laser cladding targeted repair area are preliminarily determined; Based on the original dimensions of the turbine's flow-through components and the shape and size of the laser cladding targeted repair area on the surface, the feasibility of laser cladding targeted repair was evaluated, and the evaluation results were obtained. When the evaluation results meet the requirements, the cavitation parts of the turbine flow components are processed with targeted replacement grooves to obtain targeted replacement grooves. Based on the dimensions of the cavitation area of ​​the turbine's flow components, a targeted replacement base plate was designed, and the surface of the targeted replacement base plate was laser clad to obtain a laser clad preliminary processing plate. Based on the dimensions of the targeted replacement groove, the laser cladding pre-processing plate is processed to obtain the laser cladding targeted replacement plate; The laser cladding targeted replacement plate is welded to the replacement groove. After welding, the raised part is ground according to the turbine flow line. The surface of the laser cladding targeted replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

2. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The turbine flow passage components include a runner, guide vanes, and a bottom ring.

3. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The surface laser cladding targeted repair area is rectangular, circular, or elliptical with an arc.

4. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The processing of the laser cladding pre-processing plate specifically includes: The bottom and top surfaces of the laser cladding pre-processing plate are processed, and the sides of the laser cladding pre-processing plate are processed into bevel surfaces with a set slope.

5. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The process of welding the laser cladding target replacement plate to the replacement groove specifically involves using argon arc welding or electric arc welding to weld the laser cladding target replacement plate to the replacement groove.

6. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The welding method is layered symmetrical welding.

7. The method for repairing cavitation in a water turbine according to claim 1, characterized in that, The non-destructive testing includes PT non-destructive testing and MT non-destructive testing.

8. A hydraulic turbine cavitation repair system, characterized in that, include: The data acquisition module is used to acquire the cavitation condition and original dimensions of the turbine's flow-through components. The size determination module is used to determine the size of the cavitation area of ​​the turbine's flow-through components based on the cavitation condition of the turbine's flow-through components, and to preliminarily determine the shape and size of the surface laser cladding targeted repair area based on the size of the cavitation area of ​​the turbine's flow-through components; The feasibility assessment module is used to assess the feasibility of laser cladding targeted repair based on the original dimensions of the turbine flow components and the shape and size of the surface laser cladding targeted repair area, and obtain the assessment results; The targeted replacement groove processing module is used to perform targeted replacement groove processing on the cavitation parts of the turbine flow components when the evaluation results meet the requirements, so as to obtain targeted replacement grooves. The laser cladding preliminary processing plate acquisition module is used to design a targeted replacement base plate based on the size of the cavitation area of ​​the turbine flow component, and to perform surface laser cladding on the targeted replacement base plate to obtain the laser cladding preliminary processing plate; The laser cladding pre-processing plate processing module is used to process the laser cladding pre-processing plate according to the size of the target replacement groove to obtain the laser cladding target replacement plate; The repair module is used to weld the laser cladding target replacement plate to the replacement groove. After welding, the raised part is ground according to the turbine flow line, and the surface of the laser cladding target replacement plate is subjected to non-destructive testing at a set time. After passing the non-destructive testing, the repair of the cavitation part of the turbine flow component is completed.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the turbine cavitation repair method according to any one of claims 1 to 7.

10. A storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the steps of the turbine cavitation repair method according to any one of claims 1 to 7.

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