A low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine

Abstract

A low-pressure secondary final-stage moving blade for a million-kilowatt double reheat steam turbine. This relates to the field of high-power steam turbines. Existing low-pressure secondary final-stage moving blades suffer from aerodynamic performance mismatch with large-capacity units, and an imbalance between structural strength and vibration characteristics. This new design includes a blade working section, a blade root, and a shroud; the shroud, blade working section, and blade root are integrally formed from top to bottom; the blade working section is a variable cross-section twisted blade, with relative twisting between adjacent cross-sections, and the cross-sectional area gradually decreases from the root to the tip; the height L of the blade working section is 330 mm, the axial width V at the root is 89.56 mm, the root diameter is φ2078 mm, and the exhaust area is 2.50 m²; the blade root is a fir-shaped oblique blade root with an axial width W of 117 mm; the thickness H of the shroud is 15 mm, and the axial distance B1 between the working surfaces of the shroud is 52 mm. This invention is applied to the field of million-kilowatt double reheat steam turbines.

Description

Technical Field

[0001] This utility model relates to the field of high-power steam turbines, specifically to a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine. Background Technology

[0002] As the core power equipment of a power plant, the safety and economy of high-power thermal power turbines directly determine the overall operational efficiency of the power plant. The flow path components of the turbine are crucial for energy conversion, especially the low-pressure flow path system, whose design rationality has a decisive impact on unit efficiency, output, and operational stability. The low-pressure secondary and final stage blades, as an important component of the low-pressure flow path, operate under complex conditions of high temperature, high pressure, and high speed for extended periods, and must simultaneously meet the dual requirements of optimized aerodynamic performance and reliable structural strength.

[0003] Currently, existing blades often suffer from insufficient aerodynamic design precision and difficulty in balancing structural strength and flow efficiency. Specifically, the blade exhaust area is limited, making it unable to meet the steam flow requirements of high-power units; the blade vibration characteristics are poor, and long-term operation is prone to fatigue damage; at the same time, some blades are complex to assemble and have poor frequency regulation performance, affecting the safety and economy of unit operation. Utility Model Content

[0004] In order to solve the problems of mismatch between the aerodynamic performance of existing low-pressure secondary final stage moving blades and large-capacity units, as well as the imbalance between structural strength and vibration characteristics, this utility model provides a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine.

[0005] The technical solution of this utility model is: A low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine, comprising a blade working part, a blade root, and a shroud; The surrounding band, the working part of the blade, and the blade root are integrally formed from top to bottom; The working part of the blade is a variable cross-section twisted blade, with relative twisting between adjacent cross-sections, and the cross-sectional area gradually decreases from the root to the top; The working part of the blade has a height L of 330mm, a root axial width V of 89.56mm, a root diameter of φ2078mm, and an exhaust area of ​​2.50m².

[0006] Furthermore, the leaf root is a fir-type oblique leaf root, and the axial width W of the leaf root is 117mm.

[0007] Furthermore, the thickness H of the shroud is 15mm, and the axial distance B1 between the working surfaces of the shroud is 52mm.

[0008] Furthermore, the axial width V at the root of the working part of the blade varies from 89.56 mm to 47.25 mm, and the chord length b varies from 100.62 mm to 98.76 mm.

[0009] Furthermore, the installation angle βy of the working part of the blade varies from 64.46° to 28.73°, and the maximum thickness T of the profile varies from 26.46 mm to 7.36 mm.

[0010] Furthermore, the inlet angle α of the working part of the blade varies from 47.92° to 121.07°, and the outlet angle θ varies from 23.28° to 20.72°.

[0011] Furthermore, the total height K of the leaf root is 65.72 mm.

[0012] Furthermore, a locking piece is provided at the blade root to prevent the blade from moving axially.

[0013] Furthermore, the shroud is a self-damping shroud, and through pre-twisting assembly, the adjacent blade shrouds contact each other to form a full-circle connection through torsional recovery during blade operation.

[0014] Compared with the prior art, the present invention has the following advantages: This utility model relates to a low-pressure secondary-final stage 330mm blade. Based on one-dimensional / quasi-three-dimensional / full three-dimensional aerodynamic and strength analysis, it adopts a fully three-dimensional design of a variable cross-section twisted blade. While meeting the requirements of turbine moving blades in terms of blade strength and aerodynamic performance, the blade profile uses a controllable reaction degree airfoil, and the secondary-final stage moving blade is a blade with a self-contained rib. The blade profile is twisted along the blade height to form a medium-length variable cross-section twisted blade, which has a large exhaust area and can adapt to the needs of high-power thermal power turbines. The blade tip adopts a self-contained rib to reduce losses and improve unit efficiency.

[0015] This invention is easy to assemble. Pre-twisting assembly ensures the moving blades form a complete ring connection, which is beneficial for frequency regulation and ensures safe and reliable operation. This invention has been successfully applied to a 1000MW thermal power turbine unit. By comprehensively considering fluid dynamics and structural strength, the integrated aerodynamic / structural design optimization problem is solved, achieving optimal flow efficiency and strength vibration characteristics for the 330mm blades in the last stage.

[0016] The 330mm moving blade of this utility model has reached an advanced level in terms of economy, strength and vibration characteristics, static strength and ensuring the safety and reliability of the unit. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the utility model; Figure 2 This is a top view of the circumference 3; Figure 3 This is a schematic diagram of the cross-sectional fault superposition of the working part 1 of the blade; Figure 4 This is a schematic diagram of a typical cross-section of the working part 1 of the blade; Figure 5 yes Figure 4 Enlarged view of part II; Figure 6 yes Figure 4 Enlarged view of part I; In the diagram: 1. Working part of the leaf, 2. Leaf root, 3. Surrounding band. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this utility model 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 this utility model, but are not intended to limit the scope of this utility model. Specific Implementation Method 1

[0020] Combination Figure 1 — Figure 6 This embodiment describes a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine, comprising a blade working part 1, a blade root 2, and a shroud 3. The surrounding band 3, the working part of the blade 1, and the blade root 2 are integrally formed from top to bottom; The working part 1 of the blade is a variable cross-section twisted blade, with relative twisting between adjacent cross-sections, and the cross-sectional area gradually decreases from the root to the top; The working part 1 of the blade has a height L of 330mm, a root axial width V of 89.56mm, a root diameter of φ2078mm, and an exhaust area of ​​2.50m².

[0021] The working part 1 of the blade is designed as a variable cross-section twisted blade, with relative torsion between adjacent cross-sections, and the cross-sectional area gradually decreases from the root to the top to adapt to the steam flow pattern and optimize the structural strength. The key dimensional parameters of the working part 1 of the blade are as follows: height L is 330mm, root axial width V is 89.56mm, root diameter is φ2078mm, and exhaust area is 2.50m², which can meet the steam flow requirements of a 1000MW high-power thermal power turbine.

[0022] The blade root 2 adopts a fir tree-shaped oblique blade root structure with an axial width W of 117mm. This structure can ensure a firm connection between the blade and the rim and improve the load-bearing capacity. The thickness H of the sheath 3 is 15mm and the axial distance B1 of the working surface is 52mm. The blade top reduces steam leakage loss through its own sheath and improves the aerodynamic efficiency of the unit.

[0023] During the assembly process, locking plates are installed at the blade root to restrict the axial movement of the blade and ensure assembly accuracy. The entire blade adopts a loose assembly method, that is, the shrouds of adjacent blades do not contact each other in the assembled state. When the unit is running, the shrouds of adjacent blades are brought into contact with each other by the blade torsion recovery, forming a full-circle connection structure, which is conducive to improving the frequency regulation performance of the unit and ensuring safe and reliable operation. Specific Implementation Method Two

[0025] Combination Figure 1 , Figure 4 , Figure 5 and Figure 6 The illustration shows an embodiment of a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine. The blade root 2 is a fir-type oblique blade root, and the axial width W of the blade root 2 is 117 mm.

[0026] The thickness H of the shroud 3 is 15mm, and the axial distance B1 between the working surfaces of the shroud 3 is 52mm.

[0027] Based on Embodiment 1, this embodiment further limits the variation range of key structural parameters of the working part 1 of the blade: the variation range of the axial width V at the root to the axial width V1 at the top is 89.56mm to 47.25mm, the variation range of the chord length b is 100.62mm to 98.76mm, the variation range of the installation angle βy is 64.46° to 28.73°, the variation range of the maximum profile thickness T is 26.46mm to 7.36mm, the variation range of the inlet angle α is 47.92° to 121.07°, and the variation range of the outlet angle θ is 23.28° to 20.72°.

[0028] The above parameter design ensures that the blade's external dimensions meet the design requirements of a high-power steam turbine, while also reducing the difficulty of blade processing and assembly through reasonable parameter gradient optimization. Simultaneously, it balances aerodynamic performance and structural stability, enabling the blade to maintain excellent performance across the entire operating range. The other components and connections in this embodiment are the same as in Embodiment 1. Specific Implementation Method 3

[0030] Combination Figure 1 — Figure 6This embodiment describes a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine. The inlet angle α of the working part 1 of the blade varies from 47.92° to 121.07°, and the outlet angle θ varies from 23.28° to 20.72°. Specific Implementation Method Four

[0032] Combination Figure 1 — Figure 6 This embodiment describes a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine, wherein the total height K of the blade root 2 is 65.72 mm.

[0033] The total height K of the leaf root 2 is limited to 65.72 mm. This size design, combined with the structure of the fir-shaped oblique leaf root, further enhances the connection stability between the blade and the rim, ensuring that the blade is firmly installed under high speed and high load conditions, avoiding loosening or displacement, and significantly enhancing the operational safety and reliability of the blade. The other components and connection relationships in this embodiment are the same as in Embodiment 1. Detailed Implementation Method Five

[0035] Combination Figure 1 , Figure 4 , Figure 5 and Figure 6 This embodiment describes a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine. The axial width V at the root of the working part 1 of the blade varies from 89.56 mm to 47.25 mm to the axial width V1 at the top, and the chord length b varies from 100.62 mm to 98.76 mm.

[0036] The installation angle βy of the working part 1 of the blade varies from 64.46° to 28.73°, and the maximum thickness T of the profile varies from 26.46 mm to 7.36 mm.

[0037] By using the above structural parameters, the blade's external dimensions meet design requirements while also facilitating assembly. Other components and connections are the same as in Specific Implementation Method 1.

[0038] In this embodiment, the axial widths V of the working portion 1 of the blade at heights L of 35.63mm, 106.90mm, 178.17mm, 213.80mm, 249.44mm, and 285.07mm are respectively 85.14mm, 75.70mm, 66.49mm, 61.91mm, 57.37mm, and 52.89mm. The corresponding chord lengths b are respectively 100.01mm, 100.41mm, 99.69mm, 99.10mm, 98.62mm, and 98.56mm. The corresponding installation angles βy are respectively... The blade angles are 59.48°, 49.66°, 42.29°, 39.04°, 35.86°, and 32.65°, respectively. The corresponding maximum blade thicknesses T are 24.35mm, 21.29mm, 17.57mm, 15.12mm, 12.66mm, and 10.33mm, respectively. The corresponding inlet angles α are 50.85°, 58.87°, 75.01°, 82.17°, 94.57°, and 102.22°, respectively. The corresponding outlet angles θ are 21.70°, 21.37°, 19.92°, 18.85°, 18.17°, and 18.61°, respectively. Using these structural parameters ensures that the blade's external dimensions meet design requirements while also facilitating blade assembly. Other components and connections are the same as in Specific Implementation Method 1.

[0039] The specific parameters for each section are shown in the table below: Specific Implementation Method Six

[0041] Combination Figure 1 — Figure 6 This embodiment describes a low-pressure secondary final stage moving blade for a million-kilowatt double reheat steam turbine, wherein a locking plate is provided at the blade root 2 to prevent axial movement of the blade.

[0042] The shroud 3 is a self-damping shroud. Through pre-twisting assembly, the adjacent blade shrouds 3 are brought into contact and form a complete loop connection through torsion recovery during blade operation.

[0043] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. 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 utility model's technical solution. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present utility model's technical solution, based on the technical essence of the present utility model and within the spirit and principles of the present utility model, shall still fall within the protection scope of the present utility model's technical solution.

Claims

1. A low pressure penultimate stage blade for a 1000 MW double reheat steam turbine, characterized in that, It includes the working part of the blade (1), the leaf root (2) and the surrounding band (3); The surrounding band (3), the working part of the blade (1), and the blade root (2) are integrally formed from top to bottom; The working part (1) of the blade is a variable cross-section twisted blade, with relative twisting between adjacent cross-sections, and the cross-sectional area gradually decreases from the root to the top; The working part (1) of the blade has a height L of 330mm, a root axial width V of 89.56mm, a root diameter of φ2078mm, and an exhaust area of ​​2.50m².

2. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in claim 1, characterized by, The leaf root (2) is a fir-type oblique leaf root, and the axial width W of the leaf root (2) is 117 mm.

3. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in claim 1, characterized by The thickness H of the shroud (3) is 15mm, and the axial distance B1 between the working surfaces of the shroud (3) is 52mm.

4. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in Claim 1, characterized by The axial width V at the root of the working part (1) of the blade varies from 89.56 mm to 47.25 mm to the axial width V1 at the top, and the chord length b varies from 100.62 mm to 98.76 mm.

5. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in Claim 1, characterized by, The installation angle βy of the working part (1) of the blade varies from 64.46° to 28.73°, and the maximum thickness T of the profile varies from 26.46 mm to 7.36 mm.

6. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in Claim 1, characterized by The inlet angle α of the working part (1) of the blade varies from 47.92° to 121.07°, and the outlet angle θ varies from 23.28° to 20.72°.

7. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in Claim 1, characterized by The total height K of the leaf root (2) is 65.72 mm.

8. The LP penultimate stage moving blade for a megawatt dual reheat steam turbine as set forth in claim 7, characterized in that, A locking piece is provided at the leaf root (2) to prevent the leaf from moving axially.

9. The LP penultimate stage blade for a megawatt dual reheat steam turbine as set forth in either claim 1 or claim 3, characterized by, The shroud (3) is a self-damping shroud. Through pre-twisting assembly, the blades can be rotated and restored during operation to make the adjacent blade shrouds (3) contact each other to form a full circle connection.

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