300MW grade subcritical steam turbine parameter increasing structure

Abstract

The invention discloses a parameter increasing structure of a 300MW-grade subcritical steam turbine. Relates to the field of subcritical turbines. The problems that an existing 300MW grade subcritical thermal power generating unit is limited in economical efficiency improvement due to through-flow transformation without changing steam inlet parameters, and the cost is high when the existing 300MW grade subcritical thermal power generating unit is transformed into a supercritical unit are solved. The system comprises a high-pressure valve, a high-pressure main steam guide pipe, a medium-pressure valve, a medium-pressure reheating steam guide pipe, a high-medium-pressure module, a medium-low-pressure communicating pipe and a low-pressure module. The high-pressure valves are arranged on the left side and the right side of the high-and-medium-pressure module and fixedly installed on an original platform embedded part, and the medium-pressure valves are arranged on the left side and the right side in front of the high-and-medium-pressure module, installed on an original spring floating support and connected with a reheating steam inlet port of the high-and-medium-pressure module in a butt welding mode through a medium-pressure reheating steam guide pipe. The upper portions of the high-medium-pressure module and the low-pressure module are in sealed connection through a middle-low-pressure communicating pipe, and the high-medium-pressure rotor and the low-pressure rotor in the high-medium-pressure module and the low-pressure module are in rigid connection through a flange. The method is applied to the field of 300MW grade subcritical steam turbines.

Description

Technical Field

[0001] This invention relates to the field of subcritical steam turbines, and specifically to a parameter-raising structure for a 300MW-class subcritical steam turbine. Background Technology

[0002] Currently, the industry's retrofitting solutions for 300MW-class subcritical thermal power units are mainly divided into two categories, but both have obvious limitations:

[0003] Firstly, there is the flow path modification scheme with unchanged steam inlet parameters. This scheme only improves efficiency by optimizing the aerodynamic design of the turbine flow path components or upgrading some materials, without addressing the optimization of the core steam inlet parameters. Limited by the original thermodynamic design of the unit, the improvement in operating economy after modification is limited, and it cannot fundamentally solve the problem of high unit energy consumption.

[0004] Secondly, there is the option of converting to supercritical units. Although the cycle efficiency of supercritical units is significantly better than that of subcritical units, resulting in a significant improvement in economic efficiency, this option requires a comprehensive and disruptive upgrade of the turbine, boiler, and supporting auxiliary systems, which is extremely costly. For old power plants that have been in operation for many years, this not only puts enormous pressure on investment but is also limited by factors such as site conditions and equipment foundations, making large-scale adoption impractical. Summary of the Invention

[0005] To address the issues of limited economic improvement in the flow path modification of existing 300MW-class subcritical thermal power units due to unchanged inlet steam parameters, and high costs in converting them to supercritical units, this invention provides a parameter-raising structure for a 300MW-class subcritical steam turbine.

[0006] The technical solution of this invention is:

[0007] A parameter-raising structure for a 300MW-class subcritical steam turbine includes a high-pressure valve, a high-pressure main steam pipe, an intermediate-pressure valve, an intermediate-pressure reheat steam pipe, an intermediate-high-pressure module, an intermediate-low-pressure connecting pipe, a low-pressure module, and a condenser.

[0008] The high-pressure valves are arranged on the left and right sides of the high-pressure module and fixedly installed on the original platform embedded parts. They are butt-welded to the steam inlet port of the high-pressure module through the high-pressure main steam pipe.

[0009] The intermediate pressure valve is located on the left and right sides in front of the intermediate and high pressure modules and is installed on the original spring floating bracket. It is butt-welded to the reheat steam inlet port of the intermediate and high pressure modules through the intermediate pressure reheat steam pipe.

[0010] The high- and medium-pressure modules and the low-pressure modules are arranged in series along the same axis. The upper parts of the two are sealed and connected by a medium- and low-pressure connecting pipe. The internal high- and medium-pressure rotors and the low-pressure rotors are rigidly connected by flanges.

[0011] The condenser is located below the low-pressure module and is directly connected to the exhaust port of the low-pressure module.

[0012] It also includes support bearing No. 1, support bearing No. 2, support bearing No. 3, and support bearing No. 4;

[0013] Among them, support bearing No. 1 and support bearing No. 2 are installed in the original bearing housing to jointly support the high and medium pressure rotor, while support bearing No. 3 and support bearing No. 4 are installed in the original bearing housing to jointly support the low pressure rotor.

[0014] Furthermore, the high-pressure valve and the medium-pressure valve are replaced as a whole. The high-pressure valve and the medium-pressure valve are made of high-temperature resistant alloy material to adapt to the increased steam inlet temperature. The external dimensions, mounting holes and interface structure of the high-pressure valve and the medium-pressure valve are consistent with the original high-pressure valve and the original medium-pressure valve, and they can be directly replaced and installed in the original position.

[0015] The high-temperature resistant alloy material is a nickel-based high-temperature alloy or a cobalt-based high-temperature alloy.

[0016] Furthermore, both the high-pressure main steam pipe and the medium-pressure reheat steam pipe are replaced as a whole. The high-pressure main steam pipe and the medium-pressure reheat steam pipe are made of heat-resistant steel. The pipe length, pipe diameter and flange structure of the high-pressure main steam pipe and the medium-pressure reheat steam pipe are matched with the original steam pipe. Both ends are fixedly connected to the corresponding valve outlet and the corresponding port of the high-pressure and medium-pressure module by butt welding.

[0017] The heat-resistant steel is austenitic heat-resistant stainless steel or pearlitic heat-resistant steel.

[0018] Furthermore, the high-pressure and intermediate-pressure module includes a high-pressure and intermediate-pressure outer cylinder, a high-pressure No. 1 diaphragm sleeve, a high-pressure No. 2 diaphragm sleeve, a high-pressure No. 3 diaphragm sleeve, a high-pressure exhaust balance ring, a high-pressure inlet balance ring, an intermediate-pressure No. 1 diaphragm sleeve, an intermediate-pressure No. 2 diaphragm sleeve, a high-pressure cylinder adjusting end steam seal, a high-pressure cylinder electrical end steam seal, a high-pressure and intermediate-pressure rotor, a No. 1 support bearing, and a No. 2 support bearing;

[0019] Two steam extraction ports are installed at the original extraction port position of the high-pressure and medium-pressure external cylinder. The two ends of the port are placed on the original bearing housing and are fixedly connected to the high-pressure cylinder adjusting end steam seal and the high-pressure cylinder electric end steam seal through the flange structure.

[0020] The high-pressure inner cylinder is a one-piece forged structure, which is installed on the adjusting end side inside the high-pressure outer cylinder by means of positioning pins and sealing gaskets. The high-pressure steam inlet balance ring, high-pressure No. 3 diaphragm sleeve, high-pressure No. 2 diaphragm sleeve and high-pressure No. 1 diaphragm sleeve are sequentially installed from the adjusting end to the electrical end inside.

[0021] The intermediate pressure No. 1 diaphragm sleeve, the intermediate pressure No. 2 diaphragm sleeve, and the high pressure cylinder adjusting end steam seal are all connected to the intermediate and high pressure inner cylinder for positioning by overlapping.

[0022] The high-pressure exhaust balance ring is overlapped and installed inside the high- and medium-pressure outer cylinder on the adjusting end side and in front of the high- and medium-pressure inner cylinder. It is used to balance the axial thrust of the medium-pressure flow and seal the high-pressure exhaust. The high-pressure inlet balance ring is overlapped and installed inside the high- and medium-pressure inner cylinder on the adjusting end side to achieve the sealing of the high-pressure inlet to the medium-pressure part.

[0023] The high-pressure rotor is supported at both ends by No. 1 and No. 2 support bearings in the original bearing housing. The No. 1 and No. 2 support bearings are adapted to the new rotor load and are fixed in position with the bearing housing.

[0024] Furthermore, the high-pressure and medium-pressure module also includes high-pressure guide vanes for stages 1 to 6, high-pressure guide vanes for stages 7 to 9, high-pressure guide vanes for stages 10 to 14, medium-pressure guide vanes for stages 1 to 7, medium-pressure guide vanes for stages 8 to 10, and medium-pressure guide vanes for stages 11 to 13.

[0025] The aforementioned guide vanes all adopt a pre-twisted assembly structure and are respectively installed on the high-pressure No. 1 diaphragm sleeve, the high-pressure No. 2 diaphragm sleeve, the high-pressure No. 3 diaphragm sleeve, the high-medium-pressure inner cylinder, the medium-pressure No. 1 diaphragm sleeve, and the medium-pressure No. 2 diaphragm sleeve.

[0026] The high-pressure module also includes high-pressure reverse 1-14 stages of moving blades and medium-pressure forward 1-13 stages of moving blades;

[0027] The high-pressure reverse 1-14th stage moving blades and the medium-pressure forward 1-13th stage moving blades are fixed on the adjusting end half and the electric end half of the high-pressure rotor, respectively.

[0028] Furthermore, the high-pressure guide vanes of stages 1 to 6, the high-pressure guide vanes of stages 7 to 9, the high-pressure guide vanes of stages 10 to 14, and the high-pressure reverse moving vanes of stages 1 to 14 constitute the high-pressure flow passage of stages 1 to 14.

[0029] The medium-pressure guide vanes of stages 1 to 7, stages 8 to 10, stages 11 to 13, and stages 1 to 13 of the medium-pressure forward moving vanes constitute the medium-pressure flow path of stages 1 to 13.

[0030] Furthermore, the medium and low pressure connecting pipe is a complete replacement of the medium and low pressure connecting pipe. The interface structure at both ends of the connecting pipe is adapted to the size changes of the exhaust port of the high and medium pressure module and the inlet port of the low pressure module, and a corrugated compensator is added in the middle of the pipe body.

[0031] Furthermore, the low-pressure module includes a low-pressure outer cylinder, a low-pressure inner cylinder, a low-pressure adjusting end baffle sleeve, a low-pressure electrical end baffle sleeve, a low-pressure reverse secondary and final stage baffle, a low-pressure forward secondary and final stage baffle, a low-pressure reverse final stage baffle, a low-pressure forward final stage baffle, a low-pressure exhaust guide ring, a low-pressure cylinder end steam seal, a low-pressure rotor, a No. 3 support bearing, a No. 4 support bearing, and a low-pressure transverse guide vane.

[0032] The low-pressure inner cylinder adopts a 360° volute steam inlet structure and is equipped with low-pressure horizontal guide vanes. The low-pressure inner cylinder is installed inside the low-pressure outer cylinder. The low-pressure horizontal guide vanes are embedded in the steam inlet position. The interior is connected in sequence from the regulating end to the electrical end: low-pressure reverse final stage baffle, low-pressure reverse secondary final stage baffle, low-pressure regulating end baffle sleeve, low-pressure electrical end baffle sleeve, low-pressure forward secondary final stage baffle, and low-pressure forward final stage baffle.

[0033] The low-pressure exhaust guide ring is fixedly connected to both ends of the low-pressure inner cylinder through a flange. The steam seal at the end of the low-pressure cylinder is connected to both ends of the low-pressure outer cylinder through a bellows. Both ends of the low-pressure rotor are supported in the original bearing housing through support bearing No. 3 and support bearing No. 4. Support bearing No. 3 and support bearing No. 4 are adapted to the new rotor load and are positioned and fixed with the bearing housing.

[0034] Furthermore, the low-pressure module also includes low-pressure reverse 2nd to 3rd stage guide vanes, low-pressure forward 2nd to 3rd stage guide vanes, low-pressure reverse 1st to 5th stage moving vanes, and low-pressure forward 1st to 5th stage moving vanes;

[0035] The low-voltage reverse second and third stage guide vanes and the low-voltage forward second and third stage guide vanes adopt a pre-twisted assembly structure and are respectively installed on the low-voltage adjusting end partition sleeve and the low-voltage electrical end partition sleeve;

[0036] Water erosion resistant coating is sprayed onto the surface of the last stage moving blades of the first to fifth stage moving blades in low-pressure reverse direction and the first to fifth stage moving blades in low-pressure forward direction.

[0037] Furthermore, the condenser has a steam extraction pipe that connects to the steam extraction interface of the new low-pressure inner cylinder to ensure the sealing and flow stability of the steam extraction system.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] This invention maintains the same inlet steam pressure after modification, only appropriately increasing the inlet and reheat steam temperatures based on the original boiler performance. Combined with the latest flow path design, it significantly improves the unit's operational economy while minimizing modification costs for the power plant by eliminating the need for boiler and auxiliary piping modifications, thus ensuring the widespread feasibility of this technology. It not only provides an important direction for the modification of existing 300MW-class subcritical thermal power units but also accumulates practical experience for the modification of larger-capacity thermal power units.

[0040] This invention only modifies key components of the steam turbine itself, without altering the boiler, auxiliary piping, or support platform. The modification cost is significantly lower than that of supercritical units, and the pre-twisted assembly parts reduce assembly difficulty and shorten the construction period. After modification, the overall layout of the unit remains consistent with the original, and key components can be adapted to the existing installation foundation without adjusting the plant layout. It is perfectly compatible with 300MW-class subcritical units that have been in operation for many years, only increasing the inlet steam and reheat steam temperatures without changing the main inlet steam pressure. It is adaptable to the performance of existing boilers in different power plants and has the potential for large-scale deployment.

[0041] The core components of this invention are upgraded with high-temperature resistant materials. The high and medium pressure inner cylinder adopts an integrated structure to reduce steam leakage. The balance ring strengthens the sealing and thrust balance, making it suitable for high-temperature working conditions. The low-pressure exhaust guide ring uses dual-path water spray technology to avoid overheating under low load. The final stage moving blades are treated to resist water erosion. The cylinder structure is optimized to improve rigidity, reduce deformation and stress concentration, and the whole machine has low vibration and high reliability.

[0042] The turbine of this invention retains the same layout as the original after modification. High-pressure valves are located on the left and right sides of the intermediate-high-pressure module, mounted on the original platform embedded parts. Intermediate-pressure valves are located on the left and right sides in front of the intermediate-high-pressure module, mounted on the original spring floating supports. The high-pressure valves are connected to the intermediate-high-pressure module via high-pressure main steam pipes, and the intermediate-pressure valves are connected to the intermediate-pressure reheat module via intermediate-pressure reheat steam pipes. The intermediate-high-pressure module and the low-pressure module are arranged in series along the same axis. The intermediate-high-pressure rotor and the low-pressure rotor are rigidly connected via flanges. The upper parts of the intermediate-high-pressure module and the low-pressure module are connected via intermediate-low-pressure connecting pipes. The condenser is located below the low-pressure module and is directly connected to it. In this way, apart from the turbine body and condenser, other auxiliary components such as steam supply and extraction pipelines do not need to be modified. The foundation and bearing housing, etc., used for support, remain unchanged, saving on the cost of modifying auxiliary components and platforms, and reducing the construction difficulty of the entire modification project. Attached Figure Description

[0043] Figure 1 This is a longitudinal sectional view of the steam turbine after the modification of this invention;

[0044] Figure 2 Side view of the high and intermediate pressure sections of the modified steam turbine;

[0045] Figure 3 This is a top view of the overall shape of the modified steam turbine.

[0046] Figure 4 A longitudinal sectional view of the high-voltage module modification;

[0047] Figure 5 Longitudinal sectional view of the low-voltage module modification;

[0048] In the diagram: Ⅰ, High-pressure valve; Ⅱ, High-pressure main steam pipe; Ⅲ, Medium-pressure valve; Ⅳ, Medium-pressure reheat steam pipe; Ⅴ, High and medium pressure module; Ⅵ, Medium and low pressure connecting pipe; Ⅶ, Low-pressure module; Ⅷ, Condenser.

[0049] 1. High and medium pressure outer cylinder; 2. High and medium pressure inner cylinder; 3. High pressure No. 1 diaphragm sleeve; 4. High pressure No. 2 diaphragm sleeve; 5. High pressure No. 3 diaphragm sleeve; 6. High pressure exhaust balance ring; 7. High pressure inlet balance ring; 8. Medium pressure No. 1 diaphragm sleeve; 9. Medium pressure No. 2 diaphragm sleeve; 10. High pressure cylinder adjusting end steam seal; 11. High pressure cylinder electric end steam seal; 12. No. 1 support bearing; 13. High and medium pressure rotor; 14. No. 2 support bearing.

[0050] 15. High-pressure guide vanes, stages 1-6; 16. High-pressure guide vanes, stages 7-9; 17. High-pressure guide vanes, stages 7-9; 18. Medium-pressure guide vanes, stages 1-7; 19. Medium-pressure guide vanes, stages 8-10; 20. Medium-pressure guide vanes, stages 11-13; 21. High-pressure reverse-direction moving vanes, stages 1-14; 22. Medium-pressure forward-direction moving vanes, stages 1-13.

[0051] 23. Low-pressure outer cylinder; 24. Low-pressure inner cylinder; 25. Low-pressure adjusting end baffle sleeve; 26. Low-pressure electrical end baffle sleeve; 27. Low-pressure reverse secondary and final stage baffle; 28. Low-pressure forward secondary and final stage baffle; 29. ​​Low-pressure reverse final stage baffle; 30. Low-pressure forward final stage baffle; 31. Low-pressure exhaust guide ring; 32. Low-pressure cylinder end steam seal; 33. Low-pressure rotor; 34. Support bearing No. 3; 35. Support bearing No. 4; 36. Low-pressure transverse guide vane.

[0052] 37. Low-pressure reverse 2nd to 3rd stage guide vanes; 38. Low-pressure forward 2nd to 3rd stage guide vanes; 39. Low-pressure reverse 1st to 5th stage moving vanes; 40. Low-pressure forward 1st to 5th stage moving vanes. Detailed Implementation

[0053] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention. Specific implementation method one:

[0055] Combination Figure 1 — Figure 3 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine, including a high-pressure valve I, a high-pressure main steam pipe II, an intermediate-pressure valve III, an intermediate-pressure reheat steam pipe IV, an intermediate-high-pressure module V, an intermediate-low-pressure connecting pipe VI, a low-pressure module VII, and a condenser VIII.

[0056] After the turbine is modified, its layout is the same as the original. High-pressure valve I is located on the left and right sides of the intermediate-high pressure module V and installed on the original platform embedded parts. Intermediate-pressure valve III is located on the left and right sides in front of the intermediate-high pressure module V and installed on the original spring floating bracket. High-pressure valve I is connected to the intermediate-high pressure module V through high-pressure main steam pipe II. Intermediate-pressure valve III is connected to the intermediate-high pressure module V through intermediate-pressure reheat steam pipe IV. The intermediate-high pressure module V and the low-pressure module VII are arranged in series along the same axis. The intermediate-high pressure rotor 13 and the low-pressure rotor 33 are rigidly connected by flanges. The upper part of the intermediate-high pressure module V and the low-pressure module VII are connected through the intermediate-low pressure connecting pipe VI. The condenser VIII is located below the low-pressure module VII and is directly connected to the low-pressure module VII. In this way, apart from the turbine body and condenser VIII, other auxiliary components such as steam supply and extraction pipelines do not need to be modified, and the foundation and bearing housing and other supporting platforms remain unchanged, saving the cost of modifying auxiliary components and platforms and reducing the construction difficulty of the entire modification project.

[0057] New steam enters the high-pressure module V via high-pressure valve I and high-pressure main steam pipe II. After passing through the 1st to 14th stages of flow corresponding to the 1st to 14th stages of high-pressure reverse moving blades 21, it exits the high-pressure module V and flows into the boiler reheater. After being heated in the boiler reheater, it forms reheated steam. The reheated steam enters the high-pressure module V via medium-pressure valve III and medium-pressure reheat steam pipe IV. After passing through the 1st to 13th stages of flow corresponding to the 1st to 13th stages of medium-pressure forward moving blades 22, it exits the high-pressure module V and enters the low-pressure module VII via the medium-low pressure connecting pipe VI. In the low-pressure module VII, after passing through the 1st to 5th stages of forward and reverse flow corresponding to the 1st to 5th stages of low-pressure reverse moving blades 39 and the 1st to 5th stages of low-pressure forward moving blades 40, it exits the low-pressure module VII and enters the condenser VIII. In the condenser VIII, it condenses into liquid water and is finally pumped back to the boiler. Specific Implementation Method Two:

[0059] Combination Figure 1 — Figure 3 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine. The high-pressure valve I and the intermediate-pressure valve III are replaced as a whole. The high-pressure valve I and the intermediate-pressure valve III are made of high-temperature resistant alloy material to adapt to the increased inlet steam temperature. The external dimensions, mounting holes, and interface structure of the high-pressure valve I and the intermediate-pressure valve III are consistent with the original high-pressure valve and the original intermediate-pressure valve, and they can be directly replaced and installed in the original position.

[0060] The high-temperature resistant alloy material is a nickel-based high-temperature alloy or a cobalt-based high-temperature alloy.

[0061] To adapt to higher temperatures, the high-pressure valve modification I involves replacing the entire valve and upgrading the material to suit the new steam inlet temperature. The valve shape and interface remain unchanged for easy installation in the original position.

[0062] To adapt to higher temperatures, the medium-pressure valve modification III involves replacing the entire valve and upgrading the material to match the new steam inlet temperature. The valve shape and interface remain unchanged for easy installation in the original position. Specific implementation method three:

[0064] Combination Figure 1 — Figure 3 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine. Both the high-pressure main steam pipe II and the intermediate-pressure reheat steam pipe IV are replaced as a whole. The high-pressure main steam pipe II and the intermediate-pressure reheat steam pipe IV are made of heat-resistant steel. The pipe length, diameter, and flange structure of the high-pressure main steam pipe II and the intermediate-pressure reheat steam pipe IV are matched with the original steam pipes. Both ends are fixedly connected to the corresponding valve outlets and the corresponding ports of the intermediate and high-pressure modules V by butt welding.

[0065] The heat-resistant steel is austenitic heat-resistant stainless steel or pearlitic heat-resistant steel.

[0066] To adapt to higher temperatures, the second modification of the high-pressure main steam pipe involves replacing the entire steam pipe and upgrading the material to match the new inlet steam temperature. One end of the pipe is butt-welded to the high-pressure valve, and the other end is butt-welded to the intermediate and high-pressure module.

[0067] To adapt to higher temperatures, the modification of the intermediate-pressure reheat steam pipe IV involves replacing the entire steam pipe, upgrading the material to match the new inlet steam temperature, welding one end of the pipe to the high-pressure valve, and welding the other end to the intermediate-pressure module. Specific implementation method four:

[0069] Combination Figure 4 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine.

[0070] To adapt to the increased steam extraction system after raising the inlet steam temperature and improve operating efficiency, the intermediate and high-pressure module modification V includes replacing the intermediate and high-pressure outer cylinder 1, intermediate and high-pressure inner cylinder 2, high-pressure diaphragm sleeve 1 3, high-pressure diaphragm sleeve 2 4, high-pressure diaphragm sleeve 3 5, high-pressure exhaust balance ring 6, high-pressure inlet balance ring 7, intermediate-pressure diaphragm sleeve 1 8, intermediate-pressure diaphragm sleeve 2 9, high-pressure cylinder adjusting end steam seal 10, high-pressure cylinder electric end steam seal 11, support bearing 1 12, intermediate and high-pressure rotor 13, and support bearing 2 14. Due to the changes in the thermal extraction system caused by the increased inlet steam temperature, the intermediate and high-pressure outer cylinder 1 needs to be replaced. The original extraction port position has been adjusted, and two new extraction ports have been added.

[0071] To accommodate the increased steam inlet temperature and reduce internal steam leakage caused by excessive component interfaces, the high-pressure inner cylinder 2 has been upgraded with a new material and a one-piece structure. This integrates the original high-pressure inner cylinder, high-pressure steam inlet chamber, medium-pressure heat insulation cover, and No. 1 diaphragm sleeve structure into a single unit. The high-pressure inner cylinder 2 is then mounted on the adjusting end side inside the high-pressure outer cylinder 1. The high-pressure No. 1 diaphragm sleeve 3 has also been upgraded with a new material to accommodate the increased steam temperature. The high-pressure No. 2 diaphragm sleeve 4 and high-pressure No. 3 diaphragm sleeve 5 have only had their guide vane installation interface structure optimized; the material remains unchanged.

[0072] A new high-pressure exhaust balance ring 6 is added to balance the axial thrust from the intermediate-pressure flow and to seal the steam from the high-pressure exhaust. The high-pressure inlet balance ring 7 requires a material upgrade to accommodate higher steam temperatures; its function is to seal the steam leaking from the high-pressure inlet to the intermediate-pressure section. New intermediate-pressure diaphragm sleeves 8 (No. 1) and 9 (No. 2) replace the original No. 2 diaphragm sleeve structure, while maintaining the same material. The high-pressure cylinder adjusting end steam seal 10 and the high-pressure cylinder electric end steam seal 11 are replaced with new ones and installed at both ends of the intermediate and high-pressure outer cylinder 1, respectively, to seal the steam leaking from the cylinder interior to the atmosphere.

[0073] The high-pressure rotor 13 adopts a one-piece forged structure, and the material has been upgraded to adapt to the higher steam inlet temperature. New support bearings 12 (No. 1) and 14 (No. 2) have been replaced to accommodate the load changes brought about by the new rotor. Specific implementation method five:

[0075] Combination Figure 4 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine.

[0076] To adapt to the increased steam extraction system and improve operating efficiency after raising the inlet steam temperature, the V-type modification of the intermediate and high-pressure modules includes replacing the high-pressure guide vanes 1-6 (15), 7-9 (16), 10-14 (17), 18 (18), 8-10 (19), 11-13 (20), 14-14 (21), and 1-13 (22) with new high-pressure reverse moving vanes.

[0077] High-pressure guide vanes 15 (stages 1-6), 16 (stages 7-9), 17 (stages 10-14), 18 (stages 1-7), 19 (stages 8-10), and 20 (stages 11-13) are respectively installed on high-pressure diaphragm sleeve 3 (stage 1), high-pressure diaphragm sleeve 4 (stage 2), high-pressure diaphragm sleeve 5 (stage 3), high- and medium-pressure inner cylinder 2 (stage 2), high- and medium-pressure diaphragm sleeve 8 (stage 1), and high- and medium-pressure diaphragm sleeve 9 (stage 2). All guide vanes adopt a pre-twisted assembly structure, which has high machining accuracy and low assembly difficulty. High-pressure reverse moving vanes 21 (stages 1-14) and high-pressure forward moving vanes 22 (stages 1-13) are respectively installed on the adjusting end half and the electric end half of the high- and medium-pressure rotor 13. The high-pressure guide vanes 15 (stages 1-6), 16 (stages 7-9), 17 (stages 10-14), and 21 (stages 1-14) together form the high-pressure flow path 1-14 stages. The medium-pressure guide vanes 18 (stages 1-7), 19 (stages 8-10), 20 (stages 11-13), and 22 (stages 1-13) together form the medium-pressure flow path 1-13 stages. The medium- and high-pressure flow paths employ reaction-type multi-stage small enthalpy drop technology, resulting in high flow efficiency. Specific implementation method six:

[0079] Combination Figure 4 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine. Inside the high-pressure module V, support bearing 12 and support bearing 2 are installed in the original bearing housing, and the high-pressure rotor 13 is supported by support bearing 12 and support bearing 2.

[0080] The high-pressure outer cylinder 1 is placed on the original bearing housing at both ends. The high-pressure cylinder adjusting end steam seal 10 and the high-pressure cylinder electric end steam seal 11 are respectively installed at both ends of the high-pressure outer cylinder 1 through flange structures. The high-pressure exhaust balance ring 6, the high-pressure inner cylinder 2, the intermediate pressure No. 1 diaphragm sleeve 8, and the intermediate pressure No. 2 diaphragm sleeve 9 are sequentially overlapped and installed inside the high-pressure outer cylinder 1 from the adjusting end to the electric end. The high-pressure inlet balance ring 7, the high-pressure No. 3 diaphragm sleeve 5, the high-pressure No. 2 diaphragm sleeve 4, and the high-pressure No. 1 diaphragm sleeve 3 are sequentially overlapped and installed inside the high-pressure inner cylinder 2 from the adjusting end to the electric end. The high-pressure first to sixth stage guide vanes 15, high-pressure... The guide vanes 16 (stages 7-9), 17 (high-pressure stage 10-14), 18 (medium-pressure stage 1-7), 19 (medium-pressure stage 8-10), and 20 (medium-pressure stage 11-13) are respectively embedded in the inner diameters of the high-pressure diaphragm sleeve 3 (stage 1), the high-pressure diaphragm sleeve 4 (stage 2), the high-pressure diaphragm sleeve 5 (stage 3), the electric end side of the high- and medium-pressure inner cylinder 2, the medium-pressure diaphragm sleeve 8 (stage 1), and the medium-pressure diaphragm sleeve 9. The moving vanes 21 (high-pressure reverse stage 1-14) and 22 (medium-pressure forward stage 1-13) are respectively embedded in the adjusting end half and the electric end half of the high- and medium-pressure rotor 13. This forms a high- and medium-pressure module V with high-pressure reverse stage 1-14 flow passages, medium-pressure forward stage 1-13 flow passages, and a double-layer cylinder structure. Specific implementation method seven:

[0082] Combination Figure 1 —3 Description of this embodiment: This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine. The intermediate and low-pressure connecting pipe VI is a complete replacement of the intermediate and low-pressure connecting pipe. The interface structures at both ends of the connecting pipe are adapted to the size changes of the exhaust port of the intermediate and high-pressure module V and the inlet port of the low-pressure module VII. A corrugated compensator is added to the middle of the pipe body. Detailed implementation method eight:

[0084] Combination Figure 5 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine.

[0085] The content of medium and low pressure connecting pipe renovation VI is to replace the medium and low pressure connecting pipe with a new one to adapt to the interface changes brought about by the high and medium pressure module renovation V and the low pressure module renovation VII. The new medium and low pressure connecting pipe adds a compensator structure to reduce the deformation of the pipeline during operation and improve the pipeline strength.

[0086] The modification of the low-pressure module VII includes replacing the low-pressure outer cylinder 23, low-pressure inner cylinder 24, low-pressure adjusting end baffle sleeve 25, low-pressure electrical end baffle sleeve 26, low-pressure reverse secondary and final stage baffle 27, low-pressure forward secondary and final stage baffle 28, low-pressure reverse final stage baffle 29, low-pressure forward final stage baffle 30, low-pressure exhaust steam guide ring 31, low-pressure cylinder end steam seal 32, low-pressure rotor 33, support bearing No. 3 34, support bearing No. 4 35, and low-pressure transverse guide vane 36.

[0087] Through structural optimization, cylinder rigidity is improved, reducing compression deformation caused by the negative pressure between the steam inside the cylinder and the external atmosphere. The low-pressure inner cylinder 24 is replaced with a new one, employing 360° volute steam inlet technology and new low-pressure transverse guide vanes 36 to reduce steam inlet pressure loss and improve the uniformity of the steam inlet flow field. An integrated cast iron structure is adopted to improve cylinder rigidity and reduce manufacturing costs. The position of the low-pressure extraction steam pipe is adjusted to avoid the risk of stress concentration caused by the extraction steam pipe being too close.

[0088] Replace the low-pressure adjusting end baffle sleeve 25 and the low-pressure electrical end baffle sleeve 26 with new ones. Optimize the guide vane installation interface structure to adapt to the low-pressure reverse second-to-third stage guide vanes 37 and low-pressure forward second-to-third stage guide vanes 38, while keeping the material unchanged. Optimize the structure of the low-pressure reverse secondary-to-final stage baffle 27, low-pressure forward secondary-to-final stage baffle 28, low-pressure reverse final stage baffle 29, and low-pressure forward final stage baffle 30 to adapt to the new low-pressure inner cylinder 24.

[0089] Replace the low-pressure exhaust guide ring 31 with a new one, optimize the structure to reduce the exhaust pressure loss at both ends of the low-pressure inner cylinder 24, and adopt dual-path water spray technology to prevent the low-pressure exhaust temperature from being too high due to the heat generated by the blower at low load, which would damage the turbine components and improve the turbine's operational safety.

[0090] Replace the low-pressure cylinder end steam seal 32 with a new one, and modify its structure to adapt to the new low-pressure outer cylinder 23. Replace the low-pressure rotor 33 with a new one-piece forged structure, keeping the material the same, and modify the moving blade interface to adapt to the new low-pressure reverse 1st to 5th stage moving blades 39 and low-pressure forward 1st to 5th stage moving blades 40. Replace the No. 3 support bearing 34 and the No. 4 support bearing 35 with new ones to accommodate the load changes brought about by the new rotor. Specific implementation method nine:

[0092] Combination Figure 5 This embodiment describes a parameter-increasing structure for a 300MW-class subcritical steam turbine. The low-pressure module modification VII includes replacing the low-pressure reverse 2nd-3rd stage guide vanes 37, the low-pressure forward 2nd-3rd stage guide vanes 38, the low-pressure reverse 1st-5th stage moving vanes 39, and the low-pressure forward 1st-5th stage moving vanes 40. The low-pressure outer cylinder 23 is also replaced.

[0093] The low-pressure reverse-direction 2nd-3rd stage guide vanes 37 and the low-pressure forward-direction 2nd-3rd stage guide vanes 38 adopt a pre-twisted assembly structure, which has high machining accuracy and low assembly difficulty. The low-pressure reverse-direction 1st-5th stage moving blades 39 and the low-pressure forward-direction 1st-5th stage moving blades 40 adopt a wide load adaptability design, and the last stage moving blade adopts surface spraying anti-water erosion technology, which can better adapt to low load conditions.

[0094] Inside the low-pressure module VII, support bearings 34 and 35 are installed in the original bearing housing, and the low-pressure rotor 33 is supported by support bearings 34 and 35; the low-pressure outer cylinder 23 is placed on the base plate.

[0095] The low-pressure cylinder end steam seal 32 is axially connected to both ends of the low-pressure outer cylinder 23 via a bellows; the low-pressure inner cylinder 24 is overlapped and installed inside the low-pressure outer cylinder 23; the low-pressure exhaust steam guide ring 31 is connected to both ends of the low-pressure inner cylinder 24 via a flange.

[0096] Low-pressure reverse final stage baffle 29, low-pressure reverse secondary final stage baffle 27, low-pressure adjusting end baffle sleeve 25, low-pressure electrical end baffle sleeve 26, low-pressure forward secondary final stage baffle 28, and low-pressure forward final stage baffle 30 are sequentially overlapped and installed inside the low-pressure inner cylinder 24 from the adjusting end to the electrical end.

[0097] The low-pressure transverse guide vane 36 is embedded in the steam inlet position of the low-pressure inner cylinder 24. The low-pressure reverse second-to-third stage guide vanes 37 and the low-pressure forward second-to-third stage guide vanes 38 are embedded in the inner diameter of the low-pressure adjusting end partition sleeve 25 and the low-pressure electrical end partition sleeve 26, respectively. The low-pressure reverse first-to-fifth stage moving vanes 39 and the low-pressure forward first-to-fifth stage moving vanes 40 are embedded in the adjusting end half and the electrical end half of the low-pressure rotor 33, respectively. This forms a low-pressure module VII with a reverse 1-to-5 stage flow path, a forward 1-to-5 stage flow path, and a double-layer cylinder structure. Specific Implementation Method Ten:

[0099] Combination Figure 1 — Figure 3 This embodiment describes a parameter-raising structure for a 300MW-class subcritical steam turbine. The condenser VIII has an extraction steam pipe that connects to the extraction steam interface of the new low-pressure inner cylinder 24 to ensure the sealing and flow stability of the extraction steam system.

[0100] Condenser Modification VIII involves modifying the extraction steam pipeline based on the original condenser to accommodate the interface changes brought about by the new low-pressure inner cylinder 24.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, 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 technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A parameter-raising structure for a 300MW-class subcritical steam turbine, characterized in that, It includes a high-pressure valve (Ⅰ), a high-pressure main steam pipe (Ⅱ), a medium-pressure valve (Ⅲ), a medium-pressure reheat steam pipe (Ⅳ), a high-medium-high pressure module (Ⅴ), a medium-low pressure connecting pipe (Ⅵ), a low-pressure module (Ⅶ), and a condenser (Ⅷ). The high-pressure valve (Ⅰ) is arranged on the left and right sides of the high-pressure module (Ⅴ) and fixedly installed on the original platform embedded parts. It is butt-welded to the steam inlet port of the high-pressure module (Ⅴ) through the high-pressure main steam pipe (Ⅱ). The intermediate pressure valve (Ⅲ) is arranged on the left and right sides in front of the intermediate and high pressure module (Ⅴ) and installed on the original spring floating bracket. It is butt-welded to the reheat steam inlet port of the intermediate and high pressure module (Ⅴ) through the intermediate pressure reheat steam pipe (Ⅳ); The high-pressure module (V) and the low-pressure module (VII) are arranged in series along the same axis. The upper part of the two is sealed and connected by the medium-low pressure connecting pipe (VI). The internal high-pressure rotor and the low-pressure rotor are rigidly connected by flanges. The condenser (VIII) is located below the low-pressure module (VII) and is directly connected to the exhaust port of the low-pressure module (VII); It also includes support bearing No. 1 (12), support bearing No. 2 (14), support bearing No. 3 (34), and support bearing No. 4 (35). Among them, No. 1 support bearing (12) and No. 2 support bearing (14) are installed in the original bearing housing to jointly support the high and medium pressure rotor, and No. 3 support bearing (34) and No. 4 support bearing (35) are installed in the original bearing housing to jointly support the low pressure rotor.

2. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The high-pressure valve (Ⅰ) and medium-pressure valve (Ⅲ) are to replace the high-pressure valve and medium-pressure valve as a whole. The high-pressure valve (Ⅰ) and medium-pressure valve (Ⅲ) are made of high-temperature resistant alloy material to adapt to the increased steam inlet temperature. The external dimensions, mounting holes and interface structure of the high-pressure valve (Ⅰ) and medium-pressure valve (Ⅲ) are consistent with the original high-pressure valve and the original medium-pressure valve, and can be directly replaced and installed in the original position. The high-temperature resistant alloy material is a nickel-based high-temperature alloy or a cobalt-based high-temperature alloy.

3. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The high-pressure main steam pipe (II) and the medium-pressure reheat steam pipe (IV) are both replaced as a whole. The high-pressure main steam pipe (II) and the medium-pressure reheat steam pipe (IV) are made of heat-resistant steel. The pipe length, pipe diameter and flange structure of the high-pressure main steam pipe (II) and the medium-pressure reheat steam pipe (IV) are matched with the original steam pipe. Both ends are fixedly connected to the corresponding valve outlet and the corresponding port of the high-pressure and medium-pressure module (V) by butt welding. The heat-resistant steel is austenitic heat-resistant stainless steel or pearlitic heat-resistant steel.

4. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The high-pressure and intermediate-pressure module (V) includes a high-pressure and intermediate-pressure outer cylinder (1), a high-pressure and intermediate-pressure inner cylinder (2), a high-pressure No. 1 partition sleeve (3), a high-pressure No. 2 partition sleeve (4), a high-pressure No. 3 partition sleeve (5), a high-pressure exhaust balance ring (6), a high-pressure inlet balance ring (7), an intermediate-pressure No. 1 partition sleeve (8), an intermediate-pressure No. 2 partition sleeve (9), a high-pressure cylinder adjusting end steam seal (10), a high-pressure cylinder electric end steam seal (11), a high-pressure and intermediate-pressure rotor (13), a No. 1 support bearing (12), and a No. 2 support bearing (14). The high-pressure outer cylinder (1) has two steam extraction ports installed at the original steam extraction port position. Its two ends are placed on the original bearing box and are fixedly connected to the high-pressure cylinder adjusting end steam seal (10) and the high-pressure cylinder electric end steam seal (11) through the flange structure. The high-pressure inner cylinder (2) is an integral forged structure. It is installed on the adjusting end side inside the high-pressure outer cylinder (1) by means of positioning pins and sealing gaskets. The high-pressure steam inlet balance ring (7), high-pressure No. 3 diaphragm sleeve (5), high-pressure No. 2 diaphragm sleeve (4), and high-pressure No. 1 diaphragm sleeve (3) are installed in sequence from the adjusting end to the electrical end. The medium-pressure No. 1 diaphragm sleeve (8), the medium-pressure No. 2 diaphragm sleeve (9) and the high-pressure cylinder adjusting end steam seal (10) are all connected to the high-pressure inner cylinder (2) by overlapping. The high-pressure exhaust balance ring (6) is installed on the adjusting end side inside the high-pressure outer cylinder (1) and in front of the high-pressure inner cylinder (2) to balance the axial thrust of the medium-pressure flow and seal the high-pressure exhaust. The high-pressure inlet balance ring (7) is installed on the adjusting end side inside the high-pressure inner cylinder (2) to achieve the sealing of the high-pressure inlet to the medium-pressure part. The high-pressure rotor (13) is supported at both ends by No. 1 support bearing (12) and No. 2 support bearing (14) in the original bearing housing. No. 1 support bearing (12) and No. 2 support bearing (14) are adapted to the new rotor load and are fixed in position with the bearing housing.

5. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 4, characterized in that, The high-pressure and medium-pressure module (V) also includes high-pressure guide vanes 1-6 (15), high-pressure guide vanes 7-9 (16), high-pressure guide vanes 10-14 (17), medium-pressure guide vanes 1-7 (18), medium-pressure guide vanes 8-10 (19), and medium-pressure guide vanes 11-13 (20). The above-mentioned guide vanes all adopt a pre-twisted assembly structure and are respectively installed on the high pressure No. 1 diaphragm sleeve (3), the high pressure No. 2 diaphragm sleeve (4), the high pressure No. 3 diaphragm sleeve (5), the high and medium pressure inner cylinder (2), the medium pressure No. 1 diaphragm sleeve (8) and the medium pressure No. 2 diaphragm sleeve (9); The high-pressure module (V) also includes high-pressure reverse 1-14 stages of moving blades (21) and medium-pressure forward 1-13 stages of moving blades (22). The high-pressure reverse 1-14 stage moving blades (21) and the medium-pressure forward 1-13 stage moving blades (22) are respectively fixed on the adjusting end half and the electric end half of the high-pressure rotor (13).

6. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 5, characterized in that, High-pressure guide vanes 1-6 (15), high-pressure guide vanes 7-9 (16), high-pressure guide vanes 10-14 (17), and high-pressure reverse moving vanes 1-14 (21) constitute high-pressure flow passage 1-14; The medium-pressure guide vanes 1 to 7 (18), medium-pressure guide vanes 8 to 10 (19), medium-pressure guide vanes 11 to 13 (20), and medium-pressure forward moving vanes 1 to 13 (22) constitute the medium-pressure flow path 1 to 13.

7. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The medium and low pressure connecting pipe (VI) is a complete replacement of the medium and low pressure connecting pipe. The interface structure at both ends of the connecting pipe is adapted to the size changes of the exhaust port of the high and medium pressure module (V) and the inlet port of the low pressure module (VII). A corrugated compensator is added in the middle of the pipe body.

8. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The low-pressure module (VII) includes a low-pressure outer cylinder (23), a low-pressure inner cylinder (24), a low-pressure adjusting end baffle sleeve (25), a low-pressure electrical end baffle sleeve (26), a low-pressure reverse secondary and final stage baffle (27), a low-pressure forward secondary and final stage baffle (28), a low-pressure reverse final stage baffle (29), a low-pressure forward final stage baffle (30), a low-pressure exhaust guide ring (31), a low-pressure cylinder end steam seal (32), a low-pressure rotor (33), a No. 3 support bearing (34), a No. 4 support bearing (35), and a low-pressure transverse guide vane (36). The low-pressure inner cylinder (24) adopts a 360° volute steam inlet structure and is equipped with a low-pressure horizontal guide vane (36). The low-pressure inner cylinder (24) is installed inside the low-pressure outer cylinder (23). The low-pressure horizontal guide vane (36) is embedded in the steam inlet position. The interior is connected in sequence from the regulating end to the electrical end to the low-pressure reverse final stage baffle (29), the low-pressure reverse secondary final stage baffle (27), the low-pressure regulating end baffle sleeve (25), the low-pressure electrical end baffle sleeve (26), the low-pressure forward secondary final stage baffle (28), and the low-pressure forward final stage baffle (30). The low-pressure exhaust guide ring (31) is fixedly connected to both ends of the low-pressure inner cylinder (24) through the flange. The low-pressure cylinder end steam seal (32) is axially connected to both ends of the low-pressure outer cylinder (23) through the bellows. Both ends of the low-pressure rotor (33) are supported in the original bearing housing through the No. 3 support bearing (34) and the No. 4 support bearing (35). The No. 3 support bearing (34) and the No. 4 support bearing (35) are adapted to the new rotor load and are positioned and fixed with the bearing housing.

9. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 8, characterized in that, The low-pressure module (VII) further includes low-pressure reverse second-to-third stage guide vanes (37), low-pressure forward second-to-third stage guide vanes (38), low-pressure reverse first-to-fifth stage moving vanes (39), and low-pressure forward first-to-fifth stage moving vanes (40). The low-voltage reverse second-to-third stage guide vanes (37) and the low-voltage forward second-to-third stage guide vanes (38) adopt a pre-twisted assembly structure and are respectively installed on the low-voltage adjusting end partition sleeve (25) and the low-voltage electrical end partition sleeve (26). Water erosion resistant coating is sprayed onto the surface of the last stage moving blades of the first to fifth stage moving blades (39) of the low-pressure reverse direction and the first to fifth stage moving blades (40) of the low-pressure forward direction.

10. The parameter-raising structure for a 300MW-class subcritical steam turbine according to claim 1, characterized in that, The condenser (VIII) has a steam extraction pipe that is connected to the steam extraction interface of the new low-pressure inner cylinder (24) to ensure the sealing and flow stability of the steam extraction system.

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