A volute inlet steam turbine high-pressure module overhauling method

Abstract

The application discloses a volute inlet steam turbine high-pressure module maintenance method, and belongs to the technical field of steam turbine maintenance. In order to solve the problem that the existing volute inlet steam turbine high-pressure module has no standard maintenance process, the maintenance of the damaged parts is easy, and the safe hidden trouble is brought to the operation of the unit, four core processes of separating the steam cylinder from the valve, disassembling and maintaining the outer cylinder, disassembling and maintaining the inner cylinder and resetting are clearly divided, and each step operation process, tool usage specification and operation sequence are refined, so that the status of no unified maintenance standard and disordered operation mode of the equipment is completely changed. Field maintenance personnel can construct according to the established process specification, get rid of the blind groping operation mode, and greatly reduce various problems caused by operation sequence errors and random operation modes. The application is mainly used for the maintenance method of the volute inlet steam turbine high-pressure module.

Description

Technical Field

[0001] This application belongs to the field of steam turbine maintenance technology, specifically relating to a method for overhauling the high-pressure module of a spiral-casing steam turbine. Background Technology

[0002] Currently, the energy industry, as a core pillar supporting global economic development, is facing the dual challenges of limited fossil fuel reserves and increasingly stringent ecological and environmental constraints. Energy security, green environmental protection, and high efficiency have become the core principles for the development of the global energy industry. At present, the thermal power generation industry is continuously transforming and upgrading towards higher parameters, higher efficiency, lower energy consumption, and lower emissions. Eliminating outdated and inefficient units and promoting advanced, large-capacity, high-parameter steam turbine generator units has become the mainstream development path for improving the quality and efficiency of the thermal power sector.

[0003] Steam turbines are the core power equipment of thermal power generating units, and their operating efficiency directly determines the overall coal consumption, energy consumption, and pollutant emissions of the unit. Major domestic steam turbine manufacturers are focusing on technological breakthroughs, vigorously developing and promoting high-efficiency ultra-supercritical steam turbines. Compared to traditional subcritical and supercritical units, ultra-supercritical units offer significantly improved thermal efficiency and a marked reduction in coal consumption for power generation, resulting in outstanding comprehensive environmental and economic benefits. They have become the main type of turbine for new and expanded thermal power projects. Among the core components of ultra-supercritical steam turbines, the high-pressure module is a key component determining the unit's steam inlet efficiency, sealing performance, and overall operational stability. To further overcome the technical bottlenecks of traditional high-pressure modules, the industry is gradually popularizing the volute-type high-pressure module structure design and forming standardized application schemes. This structure offers several technological advantages over traditional high-pressure modules: First, the 2×180° volute inlet steam inlet combined with a horizontally mounted stationary vane layout effectively reduces flow resistance during steam intake and minimizes steam loss. Second, the inner cylinder employs a barrel-shaped structure, coupled with a red-ring interference seal to replace the traditional flange split-face seal, eliminating steam leakage at the split face at its source. Third, the high-pressure cylinder and main steam regulating valve use a direct connection structure, eliminating the traditional steam pipe arrangement and significantly reducing steam pipeline transport losses. Fourth, the entire high-pressure module is assembled in the factory and then shipped to the project site, greatly shortening the on-site installation period. Due to these advantages, the volute inlet type high-pressure module has been widely used in next-generation high-efficiency ultra-supercritical steam turbines, and its market installation scale continues to expand.

[0004] From the perspective of equipment service life, a large number of volute-type high-pressure modules have entered their first major overhaul and centralized maintenance cycle. Subsequent similar units will also gradually enter their maintenance windows, leading to an explosive growth in the demand for specialized maintenance of these high-pressure modules. However, due to the unique structural characteristics of volute-type high-pressure modules, most domestic units currently lack mature standardized maintenance methods, work instructions, and complete tooling usage specifications. Maintenance work is often carried out by relying solely on the experience of on-site personnel, resulting in numerous practical problems. On the one hand, an unreasonable disassembly sequence can easily cause damage, scratches, and deformation to precision components such as valve seat inserts, cylinder sealing surfaces, collars, and blades. On the other hand, improper control of collar heating temperature and duration can easily lead to uneven heating of the cylinder body and material damage. Inadequate hoisting and temporary support of the rotor and inner cylinder module can also cause irreversible problems such as shaft bending and decreased rotor accuracy.

[0005] Therefore, the industry urgently needs a professional maintenance method that is adapted to its structural characteristics and has a clear process. Against this industry backdrop, this invention proposes a maintenance method for the high-pressure module of a spiral-casing steam turbine, specifically addressing the core operational challenges of separating the cylinder and valves, disassembling and maintaining the outer cylinder, and assembling and disassembling the barrel-shaped inner cylinder and collar. This fills a gap in maintenance technology in this sub-sector and has significant practical and engineering application value for ensuring the maintenance quality and operational safety of similar units, as well as extending the service life of the equipment. Summary of the Invention

[0006] This application aims to address the current lack of standardized maintenance procedures for high-pressure modules in spiral-casing steam turbines, which can lead to safety hazards during maintenance of easily damaged components and the resulting safety risks to unit operation. Therefore, this application provides a maintenance method for high-pressure modules in spiral-casing steam turbines.

[0007] A method for overhauling the high-pressure module of a volute-type steam turbine, the method being implemented through the following steps;

[0008] Step 1: Separate the cylinders and valves on the high-pressure module from the high-pressure module;

[0009] Step 2: After the cylinder and valve in Step 1 have completed the separation process, disassemble and repair the outer cylinder in the high-pressure module;

[0010] Step 3: After the outer cylinder maintenance process in Step 2 is completed, disassemble and maintain the inner cylinder in the high-voltage module.

[0011] Step 4: After the inner cylinder overhaul process in Step 3 is completed, repeat the above disassembly steps in reverse to reassemble the high-voltage module;

[0012] Furthermore, the specific steps for separating the cylinders and valves on the high-pressure module from the high-pressure module in step 1 are as follows:

[0013] Step 1a: Lock the spring brackets used to support the high-pressure valves on both sides to prevent the vertical position of the valves from changing after disassembly;

[0014] Step 1b: Remove the valve regulating actuators from both high-pressure valves;

[0015] Step 1c: Remove the valve cores of both regulating valves, use a valve seat removal tool to pull the valve seat out of the high-pressure module, and use sleepers to temporarily support the valve seat inside the valve body;

[0016] Step 1d: Remove the flange bolts connecting the upper and lower steam injection pipes to the cylinder and valve respectively, remove the steam injection pipes as a whole, and place them in the storage location;

[0017] Step 1e: Remove the connecting bolts between the left and right cylinders and the valves respectively, and use the jacking bolts to separate the cylinders and valves;

[0018] Step 1f: Using a valve pulling tool, separate the left and right high-pressure valves from the cylinder by about 40mm, then lock the hand chain hoist to fix it. At this point, the cylinder and valves are completely separated from the high-pressure module.

[0019] Furthermore, the specific steps for disassembling the outer cylinder of the high-pressure module in step 2 are as follows:

[0020] Step 2a: Remove the upper half of the insulation shell of the high-voltage module body;

[0021] Step 2b: Remove all measuring points on the upper half of the high-voltage module body, and remove the upper half of bearing housing No. 1 and bearing housing No. 2, as well as the upper half of the bearings and oil retaining rings inside them.

[0022] Step 2c: Remove the flange bolts of the steam leakage inlet pipe of the balance drum, cut the steam leakage pipe of the balance drum at a suitable location, pull out the steam leakage inlet pipe of the balance drum, and place it in the storage location;

[0023] Step 2d: Use a bolt heater to loosen the connecting bolts on the split surface of the high-voltage module body;

[0024] Step 2e: Use lifting tools to lift the upper half of the outer cylinder as a whole and place it in the storage location;

[0025] Step 2f: After removing the split bolts on the middle face of the steam seal body at the electric and regulating ends, remove the upper half of the steam seal body;

[0026] Step 2g: Install the intermediate pressure rotor end-adjusting support dummy bearing, and loosen the connecting bolts between the high pressure rotor and the intermediate pressure rotor;

[0027] Step 2h: Install the upper positioning plate of the inner cylinder and rotor to fix the relative position of the rotor and cylinder;

[0028] Step 2i: After lifting the inner cylinder and rotor module as a whole using lifting tools, install the lower half positioning plate of the inner cylinder and rotor, and then place it on the transport bracket. At this point, the removal of the outer cylinder in the high-voltage module is completed.

[0029] Furthermore, the specific steps for overhauling the outer cylinder in the high-voltage module in step 2 are as follows:

[0030] Step 2j: Clean the surfaces of the balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module;

[0031] Step 2k: Perform surface inspection and repair on the cleaned balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module.

[0032] Furthermore, the specific principles for repairing the cleaned balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module in step 2k are as follows: the slightly deformed parts are appropriately ground, and the parts that cannot be repaired are replaced.

[0033] Furthermore, the specific steps for disassembling the inner cylinder in the high-pressure module in step 3 are as follows:

[0034] Step 3a: First, support the entire high-pressure inner cylinder module;

[0035] Step 3b: Loosen the inlet volute flange bolts and remove them one by one;

[0036] Step 3c: After the steam inlet volute flange bolts are removed, remove collars 1, 2, 3, 4, 5 and 6 one by one;

[0037] Step 3d: After all the collars have been removed, use lifting tools to lift the upper half of the high-pressure inner cylinder away;

[0038] Step 3e: After the upper half of the inner cylinder is lifted off, use lifting tools to lift the high-pressure rotor out and place it in the storage position. At this point, the disassembly and assembly of the high-pressure inner cylinder module is completed.

[0039] Furthermore, the specific process of supporting the high-pressure inner cylinder module in step 3a is as follows: the high-pressure inner cylinder module is supported by five support points. Support points 1 and 2 are located on the front side of the high-pressure inner cylinder and support the high-pressure rotor. Support points 4 and 5 are located on the rear side of the high-pressure inner cylinder and support the high-pressure rotor. Support point 3 is located at the bottom of the high-pressure inner cylinder and supports the high-pressure inner cylinder. Support point 3 is supported by a fixed pad box. Support points 1, 2, 4 and 5 are all supported by screw jacks.

[0040] Furthermore, the specific steps for removing the No. 1 collar in step 3c are as follows:

[0041] Step 3c1: Install the eye bolt on the top of the No. 1 collar;

[0042] Step 3c2: Heat the No. 1 collar with a tool for about 30-50 minutes, and check that the gap between the bottom of the collar and the cylinder is greater than 2mm.

[0043] Step 3c3: Using the gantry crane, move the No. 1 collar to the left and move it laterally out of the cylinder body. Then, temporarily remove the jack at the No. 2 fulcrum.

[0044] Step 3c4: After the No. 1 collar moves past the original position of the No. 2 fulcrum, reinstall the jack at the No. 2 fulcrum and temporarily remove the jack at the No. 1 fulcrum.

[0045] Step 3c5: After the No. 1 collar moves past the original position of the No. 1 fulcrum, reinstall the jack at the No. 1 fulcrum;

[0046] Step 3c6: Continue to move the No. 1 collar to the left until the No. 1 collar is removed from the high-voltage rotor. At this point, the No. 1 collar has been completely removed.

[0047] Furthermore, the disassembly methods for collars 2, 3, 4, and 5 are the same as those for collar 1. Collar 6 is disassembled by passing through fulcrums 4 and 5 in sequence.

[0048] Furthermore, in step 3, the inner cylinder in the high-pressure module is inspected, specifically including checking the appearance of the moving and stationary blades, checking the wear of the diaphragm coating, conducting a comprehensive flaw detection inspection of the extraction ring cavity, conducting a full-surface flaw detection inspection of the rotor, checking and replacing the rotor steam seals, checking the gap between the cylinder split surfaces, and checking the wear of the balance hub steam seal ring.

[0049] The beneficial effects of this application compared to the prior art are:

[0050] This application provides a method for overhauling the high-pressure module of a volute-type steam turbine. For special structures and precision components of the high-pressure module, such as the integrated valve seat insert, barrel-shaped inner cylinder, interference collar, and rotor shaft system, this solution includes specialized protection and disassembly / reassembly processes. By locking the valve spring bracket, temporarily supporting the valve seat with sleepers, and limiting the position of the valve pulling tool, collisions, scratches, and deformations to the valve seat, pipelines, and connecting surfaces are prevented. Strictly defined heating methods, durations, and gap standards for the interference collar effectively prevent uneven heating and material damage to the cylinder body. Measures such as multi-point jack support, adding temporary rotor "dummy bearings," and setting positioning plates to fix the relative position of the shaft system eliminate irreversible damage such as rotor bending and decreased precision, significantly reducing the probability of component damage and scrap. Attached Figure Description

[0051] Figure 1 This is a front view of the high-pressure module of the volute-type steam turbine described in this application;

[0052] Figure 2 This is a top view of the high-pressure module of the volute-type steam turbine described in this application;

[0053] Figure 3 This is a left view of the high-pressure module of the volute-type steam turbine described in this application;

[0054] Figure 4 This is a cross-sectional view of the high-pressure module of the volute-type steam turbine described in this application;

[0055] Figure 5 This is a schematic diagram of the cylinder valve connections in the high-pressure module of the volute-type steam turbine described in this application;

[0056] Figure 6 This is a schematic diagram of the valve (inlet pipe) removal tool used during the overhaul of the high-pressure module of the volute inlet steam turbine described in this application;

[0057] Figure 7 This is a schematic diagram illustrating the operation of using a valve-pulling tool to pull the valve during the overhaul of the high-pressure module of the volute inlet steam turbine described in this application.

[0058] Figure 8 This is a schematic diagram showing the placement of the inner cylinder and rotor module in this application;

[0059] Figure 9 This is a schematic diagram showing the support of the inner cylinder and rotor module in this application;

[0060] In the diagram: 1. Bearing housing No. 1; 2. Bearing housing No. 2; 3. High-pressure module body; 4. High-pressure valve; 5. Steam supply valve guide pipe; 6. Regulating valve actuator; 7. Spring bracket; 8. Balance drum leakage pipe; 9. Upper half positioning plate of inner cylinder; 10. Lower half positioning plate of inner cylinder; 11.1. No. 1 collar; 11.2. No. 2 collar; 11.3. No. 3 collar; 11.4. No. 4 collar; 11.5. No. 5 collar; 11.6. No. 6 collar; 12.1. No. 1 fulcrum; 12.2. No. 2 fulcrum; 12.3. No. 3 fulcrum; 12.4. No. 4 fulcrum; 12.5. No. 5 fulcrum; 13. Valve removal tool; 14. Valve push-pull tool; and 15. Valve temporary fixing tool. Detailed Implementation

[0061] Specific implementation method one: Combining Figures 1 to 9 This embodiment describes a method for overhauling the high-pressure module of a volute-type steam turbine inlet, which is implemented through the following steps:

[0062] Step 1: Separate the cylinders and valves on the high-pressure module from the high-pressure module;

[0063] Step 2: After the cylinder and valve in Step 1 have completed the separation process, disassemble and repair the outer cylinder in the high-pressure module;

[0064] Step 3: After the outer cylinder maintenance process in Step 2 is completed, disassemble and maintain the inner cylinder in the high-voltage module.

[0065] Step 4: After the inner cylinder overhaul process in Step 3 is completed, repeat the above disassembly steps in reverse to reassemble the high-voltage module.

[0066] This embodiment provides a method for overhauling the high-pressure module of a volute-type steam turbine. This method is specifically designed for overhauling the high-pressure module of a volute-type steam turbine and includes three parts: separation of the cylinder and valves, disassembly and overhaul of the outer cylinder, and disassembly and overhaul of the inner cylinder. The specific steps in step 1, separating the cylinder and valves from the high-pressure module, are as follows:

[0067] Step 1a: Lock the spring bracket 7 used to support the high-pressure valves 4 on both sides to prevent the vertical position of the valves from changing after disassembly;

[0068] Step 1b: Remove the valve regulating actuator 6 from both high-pressure valves 4;

[0069] Step 1c: Remove the valve cores of the regulating valves on both sides, use valve seat removal tool 13 to pull the valve seat out of the high pressure module, and use sleepers to temporarily support the valve seat inside the valve body;

[0070] Step 1d: Remove the flange bolts connecting the upper and lower steam injection pipes to the cylinder and valve respectively, remove the steam injection pipes as a whole, and place them in the storage location;

[0071] Step 1e: Remove the connecting bolts between the left and right cylinders and the valves respectively, and use the jacking bolts to separate the cylinders and valves;

[0072] Step 1f: Using valve pulling tool 14, separate the left and right high-pressure valves from the cylinder by about 40mm, then lock the hand chain hoist to fix it. At this point, the cylinder and valves are completely separated from the high-pressure module.

[0073] In the above steps, the valve is rigidly limited by locking the spring bracket 7 to prevent vertical displacement of the valve, protect the sealing surface between the valve body and the cylinder, and help maintain the original positional accuracy of the components. By using the temporary support of the sleeper inside the valve body, the valve seat can be removed smoothly, avoiding deformation and impact damage to the integrated tube and valve seat, and protecting the core sealing structure to the greatest extent. The two are precisely separated by 40mm by the valve pulling tool, and the valve pulling distance is controllable. Then, the valve is locked and fixed by hand chain hoist, which not only prevents the components from being damaged by excessive pulling, but also avoids the safety risks of valve tipping and sliding, and improves the safety of on-site operation.

[0074] Step 2 involves disassembling and inspecting the outer cylinder of the high-voltage module. The specific steps are as follows:

[0075] Step 2a: Remove the upper half of the insulation shell of the high-voltage module body 3;

[0076] Step 2b: Remove all measuring points on the upper half of the high voltage module body 3, and remove the upper half of bearing housing 1 and bearing housing 2, as well as the upper half of the bearings and oil retaining rings inside them.

[0077] Step 2c: Remove the flange bolts of the steam leakage inlet pipe of the balance drum, cut the steam leakage pipe of the balance drum at a suitable location, pull out the steam leakage inlet pipe 8 of the balance drum, and place it in the storage location;

[0078] Step 2d: Use a bolt heater to loosen the connecting bolts on the split surface of the high-pressure module body 3;

[0079] Step 2e: Use lifting tools to lift the upper half of the outer cylinder as a whole and place it in the storage location;

[0080] Step 2f: After removing the split bolts on the middle face of the steam seal body at the electric and regulating ends, remove the upper half of the steam seal body;

[0081] Step 2g: Install the intermediate pressure rotor end-adjusting support dummy bearing, and loosen the connecting bolts between the high pressure rotor and the intermediate pressure rotor;

[0082] Step 2h: Install the upper positioning plate of the inner cylinder and rotor to fix the relative position of the rotor and cylinder;

[0083] Step 2i: After lifting the inner cylinder and rotor module as a whole using lifting tools, install the lower half positioning plate 9 of the inner cylinder and rotor, and then place it on the transport bracket. At this point, the removal of the outer cylinder in the high-voltage module is completed.

[0084] Step 2j: Clean the surfaces of the balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module;

[0085] Step 2k: Perform surface inspection and repair on the cleaned balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module. The specific repair principles are: grind slightly deformed parts appropriately, and replace parts that cannot be repaired.

[0086] The above steps take into account that the balance drum leakage pipe and pipeline are pressure-bearing sealing components with low pipeline rigidity and high sealing surface precision requirements. Rough pulling and arbitrary cutting can easily cause pipeline twisting and flange sealing surface damage, leading to leakage failures during unit operation. Standardized flange disassembly, fixed-point cutting, smooth removal and fixed-point storage ensure the integrity of the leakage pipeline and pipe structure, protect the sealing joint surface, avoid potential leakage risks in the future, and completely remove the pipeline from the cylinder hoisting. The high and medium pressure rotors of this model are supported by N+1 bearings, and the medium pressure rotor adjustment end has no original support bearing. After disassembly, the rotor end is in a suspended state, which is very easy to cause irreversible damage such as shaft sinking, bending, and coaxiality misalignment. Temporary dummy bearings are added as auxiliary supports to provide reliable support for the suspended rotor ends, maintaining the original shape of the shaft system and completely preventing rotor bending and decreased precision. The orderly disassembly of the coupling bolts prevents wear and damage to the coupling mating surfaces caused by forced disassembly. Furthermore, considering the extremely small assembly clearance between the inner cylinder and the rotor, any relative displacement during hoisting or relocation could directly cause friction between moving and stationary parts, scratching the blades and rotor journals. Positioning plates lock the relative positions of both, strictly limiting displacement deviation and effectively preventing scratches between moving and stationary parts, protecting the rotor blades, journals, and other core precision structures.

[0087] The specific steps for disassembling and inspecting the inner cylinder in the high-voltage module in step 3 are as follows:

[0088] Step 3a: First, support the entire high-pressure inner cylinder module;

[0089] Step 3b: Loosen the inlet volute flange bolts and remove them one by one;

[0090] Step 3c: After the steam inlet volute flange bolts are removed, remove the No. 1 collar 11-1, No. 2 collar 11-2, No. 3 collar 11-3, No. 4 collar 11-4, No. 5 collar 11-5 and No. 6 collar 11-6 one by one.

[0091] Step 3d: After all the collars have been removed, use lifting tools to lift the upper half of the high-pressure inner cylinder away;

[0092] Step 3e: After the upper half of the inner cylinder is lifted off, use a lifting tool to lift the high-pressure rotor out and place it in the storage position. At this point, the disassembly and assembly of the high-pressure inner cylinder module is completed.

[0093] Step 3 involves inspecting the inner cylinder of the high-voltage module, specifically including the following:

[0094] 1) Inspect the appearance of the moving and stationary blades and perform flaw detection;

[0095] 2) Inspect the wear condition of the partition coating and re-spray or re-spray as needed;

[0096] 3) Conduct a comprehensive flaw detection inspection of the extraction annular cavity and repair as needed;

[0097] 4) Perform full-surface flaw detection on the rotor and check for rotor runout; repair as needed.

[0098] 5) Inspect the condition of the rotor steam seals and replace them if necessary;

[0099] 6) Check the clearance between the cylinder split surfaces and take appropriate action as needed;

[0100] 7) Check the wear condition of the balance hub steam seal ring and replace it as needed.

[0101] The above steps establish a logically rigorous and sequential disassembly process for the special structure of the cylindrical cylinder and multiple sets of interference-fit rings in the volute inlet steam turbine. This changes the previous situation where there were no unified operating standards for this type of internal cylinder and construction relied entirely on experience, standardizing on-site maintenance procedures and significantly reducing the rate of human error. From the initial overall support and step-by-step removal of connection constraints to the later separation of the cylinder body and rotor using specialized lifting tools, the entire process takes into account cylinder stress release, uniform load distribution, and component isolation and protection, effectively avoiding problems such as cylinder deformation, ring scrapping, blade breakage, and rotor precision damage. This reduces spare parts replacement and lowers equipment operation and maintenance costs. This process follows the mechanical maintenance principle of first external constraints, then internal sealing, and first fixing supports, then disassembly and relocation. Through overall support, it effectively prevents safety risks such as tipping and falling caused by lifting large components and moving heavy cylinder bodies. At the same time, the standardized process reduces rework and improves the overall operational efficiency of the internal cylinder disassembly process.

[0102] Specific Implementation Method Two: Combining Figures 1 to 9 This embodiment further defines step 3a in specific embodiment one. The specific process of supporting the high-pressure inner cylinder module in step 3a is as follows: five support points are used to support the entire high-pressure inner cylinder module. Support points 1 (12-1) and 2 (12-2) are located at the front of the high-pressure inner cylinder and support the high-pressure rotor; support points 4 (12-4) and 5 (12-5) are located at the rear of the high-pressure inner cylinder and support the high-pressure rotor; and support point 3 (12-3) is located at the bottom of the high-pressure inner cylinder and supports the high-pressure inner cylinder. Support point 3 (12-3) is supported by a fixed pad box. Support points 1 (12-1), 2 (12-2), 4 (12-4), and 5 (12-5) are all supported by screw jacks. Other methods and steps are the same as in specific embodiment one.

[0103] The five-point support system in this embodiment is designed to adapt to the ring distribution system of this machine model. By separating the load, providing uniform support at multiple points, and leveling the rotor, deformation of the barrel-shaped inner cylinder, bending of the high-pressure rotor, and damage to the journal precision are effectively prevented. This preserves the original performance of the equipment to the greatest extent and reduces the cost of scrapping parts and maintenance. There are a total of 6 rings in this machine model. The 6 rings are divided into two groups, and the two groups of rings are fitted from both ends of the high-pressure inner cylinder. Support point 3 (12-3) of the five supports is used to support the bottom of the high-pressure inner cylinder and is supported by a fixed gasket. Support points 1 (12-1) and 2 (12-2) form one support system, and support points 4 (12-4) and 5 (12-5) form another support system. The two support systems are located on both sides of the fixed gasket and are supported by screw jacks for the high-pressure rotor. The advantage of this design is that when the collar is disassembled, as the collar moves away, a screw jack can always be provided on one side of the fixed gasket for support. This can effectively prevent the high-pressure rotor from tilting during the collar disassembly process. Moreover, the stable support system throughout the process ensures the original relative position of the cylinder and rotor. When carrying out blade flaw detection, rotor inspection, steam seal replacement, and reverse reassembly of components, there is no need to recalibrate the benchmark, which further improves the quality of maintenance and reassembly.

[0104] Specific implementation method three: Combining Figures 1 to 9 This embodiment further defines step 3c in specific embodiment one. The specific steps for removing the first collar 11-1 in step 3c are as follows:

[0105] Step 3c1: Install the eye bolt on the top of collar 11-1;

[0106] Step 3c2: Use a tool to heat the No. 1 collar 11-1 for about 30-50 minutes, and check that the gap between the bottom of the collar and the cylinder is greater than 2mm;

[0107] Step 3c3: Using the gantry crane, move the No. 1 collar 11-1 to the left side. After moving it laterally out of the cylinder, temporarily remove the jack at the No. 2 fulcrum 12-2.

[0108] Step 3c4: After the No. 1 collar 11-1 moves past the original position of the No. 2 fulcrum 12-2, reinstall the jack of the No. 2 fulcrum 12-2 and temporarily remove the jack of the No. 1 fulcrum 12-1.

[0109] Step 3c5: After the No. 1 collar 11-1 moves past the original position of the No. 1 fulcrum 12-1, reinstall the jack of the No. 1 fulcrum 12-1;

[0110] Step 3c6: Continue to move collar 11-1 to the left until collar 11-1 is removed from the high-voltage rotor. At this point, collar 11-1 is completely removed. Other steps are the same as in Specific Implementation Method 1.

[0111] In this application, the high-pressure inner cylinder of the volute inlet steam turbine has a barrel-shaped structure. The collar and cylinder body are interference-sealed, requiring high assembly tightness, large component weight, and stringent structural precision. Traditional maintenance lacks standardized dismantling procedures, often resulting in arbitrary heating methods, rough relocation operations, and chaotic support point alignment. This easily leads to collar deformation, cylinder body thermal damage, rotor impact, and shaft instability and bending. This implementation method establishes a complete standardized procedure from hoisting preparation, constant temperature heating, segmented translation, to alternating dismantling and assembly at support points. It is also deeply compatible with the five-support-point system mentioned above, achieving safe, non-destructive, and controllable dismantling of the collar. It also provides a standard operating procedure for the dismantling of other collars. Two points need attention when dismantling collars 2 to 6. First, this model has an extraction ring cavity between collar 1 (11-1) and collar 2 (11-2). The extraction ring cavity is clearance-fitted with the inner cylinder, and no thermal expansion treatment is required during its dismantling. Only collar 1 needs to be referenced. For the disassembly procedure of 11-1, when moving it, first temporarily remove the jack at fulcrum 2 (12-2), and then temporarily remove the jack at fulcrum 1 (12-1). Secondly, it should be noted that collar 6 (11-6) is located to the right of fulcrum 3 (12-3). Therefore, when disassembling it, it needs to be disassembled through fulcrum 4 (12-4) and fulcrum 5 (12-5). Refer to the disassembly procedure of collar 1 (11-1). Other steps remain the same. When moving it, first temporarily remove the jack at fulcrum 4 (12-4), and then temporarily remove the jack at fulcrum 5 (12-5).

[0112] The present invention has been disclosed above with preferred embodiments, but it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed structure and technical content to create equivalent embodiments without departing from the scope of the present invention. However, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for overhauling the high-pressure module of a volute-type steam turbine, characterized in that: The maintenance method is implemented through the following steps: Step 1: Separate the cylinders and valves on the high-pressure module from the high-pressure module; Step 2: After the cylinder and valve in Step 1 have completed the separation process, disassemble and repair the outer cylinder in the high-pressure module; Step 3: After the outer cylinder maintenance process in Step 2 is completed, disassemble and maintain the inner cylinder in the high-voltage module. Step 4: After the inner cylinder overhaul process in Step 3 is completed, repeat the above disassembly steps in reverse to reassemble the high-voltage module.

2. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 1, characterized in that: The specific steps for separating the cylinders and valves on the high-pressure module from the high-pressure module in step 1 are as follows: Step 1a: Lock the spring bracket (7) used to support the high-pressure valves (4) on both sides to prevent the vertical position of the valves from changing after disassembly; Step 1b: Remove the valve regulating actuator (6) of the high-pressure valves (4) on both sides; Step 1c: Remove the valve cores of the regulating valves on both sides, and use the valve seat removal tool (13) to pull the valve seat out of the high pressure module. Use sleepers to temporarily support the valve seat inside the valve body. Step 1d: Remove the flange bolts connecting the upper and lower steam injection pipes to the cylinder and valve respectively, remove the steam injection pipes as a whole, and place them in the storage location; Step 1e: Remove the connecting bolts between the left and right cylinders and the valves respectively, and use the jacking bolts to separate the cylinders and valves; Step 1f: Using the valve pulling tool (14), separate the left and right high-pressure valves from the cylinder by about 40mm, and then lock the hand chain hoist to fix it. At this point, the cylinder and valves are completely separated from the high-pressure module.

3. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 1, characterized in that: The specific steps for disassembling the outer cylinder of the high-voltage module in step 2 are as follows: Step 2a: Remove the upper half of the insulation shell of the high-voltage module body (3); Step 2b: Remove the measuring points at each part of the upper half of the high voltage module body (3), and remove the upper half of bearing box 1 (1) and bearing box 2 (2) and the upper half of the bearings and oil retaining ring inside them; Step 2c: Remove the flange bolts of the steam leakage inlet pipe of the balance drum, cut the steam leakage pipe of the balance drum at a suitable position, pull out the steam leakage inlet pipe (8) of the balance drum and place it in the storage position; Step 2d: Use a bolt heater to loosen the connecting bolts on the split surface of the high-pressure module body (3); Step 2e: Use lifting tools to lift the upper half of the outer cylinder as a whole and place it in the storage location; Step 2f: After removing the split bolts on the middle face of the steam seal body at the electric and regulating ends, remove the upper half of the steam seal body; Step 2g: Install the intermediate pressure rotor end-adjusting support dummy bearing, and loosen the connecting bolts between the high pressure rotor and the intermediate pressure rotor; Step 2h: Install the upper positioning plate (9) of the inner cylinder and rotor to fix the relative position of the rotor and cylinder; Step 2i: After lifting the inner cylinder and rotor module as a whole using lifting tools, install the lower half positioning plate (10) of the inner cylinder and rotor, and then place it on the transport bracket. At this point, the removal of the outer cylinder in the high-voltage module is completed.

4. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 1, characterized in that: The specific steps for overhauling the outer cylinder in the high-voltage module in step 2 are as follows: Step 2j: Clean the surfaces of the balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module; Step 2k: Perform surface inspection and repair on the cleaned balance drum leak pipe, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module.

5. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 4, characterized in that: The specific principles for repairing the leaking steam pipe of the cleaned balance drum, the upper half of the outer cylinder, and the lower half of the outer cylinder located on the high-pressure module in step 2k are as follows: the slightly deformed parts are appropriately ground, and the parts that cannot be repaired are replaced.

6. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 5, characterized in that: The specific steps for disassembling the inner cylinder in the high-pressure module in step 3 are as follows: Step 3a: First, support the entire high-pressure inner cylinder module; Step 3b: Loosen the inlet volute flange bolts and remove them one by one; Step 3c: After the steam inlet volute flange bolts are removed, remove the No. 1 collar (11-1), No. 2 collar (11-2), No. 3 collar (11-3), No. 4 collar (11-4), No. 5 collar (11-5), and No. 6 collar (11-6) one by one. Step 3d: After all the collars have been removed, use lifting tools to lift the upper half of the high-pressure inner cylinder away; Step 3e: After the upper half of the inner cylinder is lifted off, use a lifting tool to lift the high-pressure rotor out and place it in the storage position. This completes the disassembly and assembly of the high-pressure inner cylinder module.

7. The method for overhauling the high-pressure module of a volute-type steam turbine according to claim 6, characterized in that: The specific process of supporting the high-pressure inner cylinder module in step 3a is as follows: the high-pressure inner cylinder module is supported by five support points. Support points 1 (12-1) and 2 (12-2) are located on the front side of the high-pressure inner cylinder and support the high-pressure rotor. Support points 4 (12-4) and 5 (12-5) are located on the rear side of the high-pressure inner cylinder and support the high-pressure rotor. Support point 3 (12-3) is located at the bottom of the high-pressure inner cylinder and supports the high-pressure inner cylinder. Support point 3 (12-3) is supported by a fixed pad box. Support points 1 (12-1), 2 (12-2), 4 (12-4), and 5 (12-5) are all supported by screw jacks.

8. A method for overhauling a high-pressure module of a volute-type steam turbine according to claim 6, characterized in that: The specific steps for removing collar 1 (11-1) in step 3c are as follows: Step 3c1: Install the eye bolt on the top of collar 1 (11-1); Step 3c2: Heat the No. 1 collar (11-1) with a tool for about 30-50 minutes, and check that the gap between the bottom of the collar and the cylinder is greater than 2mm; Step 3c3: Using the gantry crane, move the No. 1 collar (11-1) to the left side. After moving it laterally out of the cylinder, temporarily remove the jack at the No. 2 fulcrum (12-2). Step 3c4: After the No. 1 collar (11-1) moves past the original position of the No. 2 fulcrum (12-2), reinstall the jack of the No. 2 fulcrum (12-2) and temporarily remove the jack of the No. 1 fulcrum (12-1); Step 3c5: After the No. 1 collar (11-1) moves past the original position of the No. 1 fulcrum (12-1), reinstall the jack of the No. 1 fulcrum (12-1); Step 3c6: Continue to move the No. 1 collar (11-1) to the left until the No. 1 collar (11-1) is removed from the high-voltage rotor. At this point, the No. 1 collar (11-1) has been completely removed.

9. A method for overhauling a high-pressure module of a volute-type steam turbine according to claim 8, characterized in that: The disassembly methods for collars 2 (11-2), 3 (11-3), 4 (11-4), and 5 (11-5) are the same as those for collar 1 (11-1). Collar 6 (11-6) is disassembled by passing through fulcrum 4 (12-4) and fulcrum 5 (12-5) in sequence.

10. A method for overhauling a high-pressure module of a volute-type steam turbine according to claim 5, characterized in that: Step 3 involves overhauling the inner cylinder of the high-voltage module, specifically including checking the appearance of the moving and stationary blades, checking the wear of the diaphragm coating, conducting a comprehensive flaw detection inspection of the extraction ring cavity, performing a full-surface flaw detection inspection of the rotor, checking and replacing the rotor steam seals, checking the gap between the cylinder split surfaces, and checking the wear of the balance hub steam seal rings.

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