Wide-load last-stage blade of wet cooling steam turbine

Abstract

The utility model relates to the technical field of steam turbines, and discloses a wide-load last-stage blade of a wet cooling steam turbine, which comprises a single blade, and the single blade comprises a blade root and a blade body; the blade root is located at the root of the blade body, and the blade root and the blade body are of an integral structure. The blade root adopts a multi-blade-root design and comprises a butt joint part and an inserting part which are of an integrated structure, the top end of the butt joint part is connected with the blade body, the bottom end of the butt joint part is connected with the inserting part, the two sides of the butt joint part are provided with an outwards-protruding isosceles trapezoid convex part and an inwards-concave isosceles trapezoid concave surface part respectively, the inserting part is in a fir tree shape, and a rectangular hole groove is formed in the inserting part; and a plurality of subsection roots which are arranged in parallel are arranged in the rectangular hole groove at equal intervals. Through the adoption of the fir tree type inserting part and the segmented root structure, the structural stability of the blade is remarkably improved, and the fatigue damage of the blade root is reduced. Performance and reliability of the steam turbine are improved, maintenance cost is reduced, and installation efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of steam turbines, and in particular relates to a wide-load last-stage blade of a wet-cooled steam turbine. Background Art

[0002] The last stage rotor blades are important components of the steam turbine. They are subject to the greatest centrifugal force and work in a complex environment. The working medium contains wet steam with water droplets. Under the action of water droplets, the blades are prone to water erosion. The eroded parts are prone to stress concentration, forming many small cracks.

[0003] Traditional blade designs may not effectively resist low-cycle fatigue and stress corrosion, resulting in a short blade lifespan. Frequent verification is required to reduce fatigue strength and avoid serious accidents such as breakage. Traditional blade designs may also lack rigidity. For example, the current integrated fir-tree root design may lack rigidity during use and is prone to vibration under the action of high-speed steam flow, causing additional fatigue damage. Utility Model Content

[0004] The present invention aims to solve the technical problem that the blade design in the above-mentioned prior art may not be able to effectively resist low-cycle fatigue and stress corrosion, resulting in a short blade life.

[0005] To achieve the above objectives, the present invention provides the following technical solutions:

[0006] A wide-load last-stage blade for a wet-cooled steam turbine comprises a single blade, wherein the single blade comprises a blade root and a blade body; the blade root is located at the root of the blade body and the blade root and the blade body are an integral structure; the blade root adopts a multiple-blade root design, comprising a docking portion and a plug-in portion of an integral structure, wherein the top end of the docking portion is connected to the blade body and the bottom end is connected to the plug-in portion, an outwardly convex isosceles trapezoidal convex portion and an inwardly concave isosceles trapezoidal concave portion are respectively provided on both sides of the docking portion, the plug-in portion is fir-tree-shaped, a rectangular hole groove is provided in the plug-in portion, and a plurality of parallel segmented roots are arranged at equal distances in the rectangular hole groove.

[0007] Preferably, the segmented root is a three-step convex shape, and each segment of the segmented root is designed to gradually decrease in width from top to bottom. This can reduce stress concentration at the blade root when affected by steam flow, thereby reducing the risk of fatigue damage.

[0008] Preferably, a positioning groove for fitting the wheel cover is formed between two adjacent segment roots and the inner wall of the rectangular slot, and between the segment roots and the inner wall of the rectangular slot, so as to make the insertion and positioning between the blade and the wheel cover more accurate and convenient.

[0009] Preferably, concave grooves are provided on both sides of the butt joint to fit in with the rim bosses, so as to facilitate butt joint assembly of the toothed surfaces of the blade root and the rim connection end.

[0010] Preferably, the blade is a three-dimensional linear blade adapted to the steam flow, and ribs are provided on both sides of the blade. This can more accurately adapt to the steam flow, improve the turbine performance of the blade, and thus increase the efficiency of the steam turbine.

[0011] Preferably, the blade is designed with a twist angle from the root to the tip so that all cross sections of the blade can maintain an optimal bow angle to utilize steam energy with maximum efficiency.

[0012] Preferably, a shroud is provided on the top of the blade to further improve the structural stability of the blade.

[0013] Preferably, the shroud, tie bars and blade body are designed as an integral structure.

[0014] Compared with the prior art, the technical effects and advantages of the utility model are:

[0015] This wet-cooled steam turbine's wide-load last-stage blade utilizes a fir-tree splice and segmented root design to enhance blade structural stability and reduce fatigue damage. The fir-tree splice provides a robust support network that effectively distributes stress at the blade root, while the segmented root design divides the blade root into segments, with the spacing between each segment providing support, increasing blade rigidity and reducing vibration.

[0016] The wide-load last-stage blades of this wet-cooled steam turbine significantly improve the performance and reliability of the turbine, while reducing maintenance costs and improving installation efficiency. The stepped convex design of the segmented root and the corresponding positioning grooves make the connection and positioning between the blade and the wheel cover more accurate and convenient, which is conducive to the installation of the blade and future maintenance work. In addition, the twist angle design and three-dimensional linear design of the blade body improve the aerodynamic performance of the blade and increase the efficiency of the turbine. The design of the shroud, ribs and blade body as an integral structure further improves the structural stability of the blade, ensuring that the blade maintains its shape in high temperature and high pressure environments, thereby improving the overall performance of the turbine. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of a single blade without a shroud in the present invention;

[0018] Figure 2 This is a schematic structural diagram of a single blade with a shroud according to the present invention;

[0019] Figure 3 This is a first-perspective view of the blade root of the utility model;

[0020] Figure 4 This is a second perspective view of the blade root of the utility model;

[0021] Figure 5 For this utility model Figure 3Schematic diagram of the structure after cutting along line AA.

[0022] In the figure: 100, single blade; 1, blade root; 101, docking part; 102, plug-in part; 103, isosceles trapezoidal convex part; 104, isosceles trapezoidal concave part; 105, rectangular hole groove; 106, segmented root; 107, positioning groove; 108, concave groove; 2, blade body; 3, tensioning rod; 4, shroud. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] The following is combined with Figure 1-5 To further explain this application,

[0025] The embodiment of the present application discloses a wide-load last-stage blade for a wet-cooled steam turbine, comprising a single blade 100, wherein the single blade 100 comprises a blade root 1 and a blade body 2; the blade root 1 is located at the root of the blade body 2, and the blade root 1 and the blade body 2 are an integral structure;

[0026] The blade root 1 adopts a multiple blade root 1 design, including a butt joint portion 101 and a plug-in portion 102 of an integrated structure. The top end of the butt joint portion 101 is connected to the blade airframe 2 and the bottom end is connected to the plug-in portion 102. An outwardly convex isosceles trapezoidal convex portion 103 and an inwardly concave isosceles trapezoidal concave portion 104 are respectively provided on both sides of the butt joint portion 101. The isosceles trapezoidal convex portion 103 and the isosceles trapezoidal concave portion 104 of the butt joint portion 101 provide a good contact surface for the connection between the blade root 1 and the blade airframe 2, thereby increasing the stability and reliability of the connection.

[0027] The plug-in portion 102 is fir-tree shaped, and a rectangular slot 105 is defined in the plug-in portion 102 . A plurality of parallel segmented roots 106 are arranged at equal distances in the rectangular slot 105 .

[0028] The multiple blade root 1 design is a design that uses multiple parallel segmented roots 106 structures and a fir-tree-shaped plug-in portion 102 wrapped around the outside of the segmented roots 106 at the root of the turbine blade. The two constitute a composite blade root 1 structure. The purpose of this design is to improve the structural stability of the blade and reduce fatigue damage of the blade root 1. Multiple parallel segmented roots 106 divide the blade root 1 into several sections. Each section of the blade root 1 has a certain spacing, so that support can be formed between different blade root 1 sections, increasing the rigidity of the blade and reducing vibration. The fir-tree-shaped plug-in portion 102 wrapped around the outside of the segmented root 106 is equivalent to an integral structure. The blade root 1 adopts a fir-tree-type blade root 1, which can improve the blade's resistance to low-cycle fatigue and stress corrosion. The fir-tree-type blade root 1 has multiple branches fixed to the wheel cover like the branches of a fir tree, so that a solid support network can be formed at the blade root.

[0029] The segmented root 106 is a three-stage stepped convex shape, a four-stage stepped convex shape or a five-stage stepped convex shape, and each section of the segmented root 106 is designed to gradually decrease in width from top to bottom. A positioning groove 107 for fitting the wheel cover for insertion and positioning is formed between two adjacent segmented roots 106 and the inner wall surface of the rectangular hole groove 105, and between the segmented root 106 and the inner wall surface of the rectangular hole groove 105.

[0030] By dividing the segmented root 106 into several sections, with each segmented root 106 gradually decreasing in width, stress concentration on the blade root 1 when subjected to steam flow can be reduced, thereby reducing the risk of fatigue damage and extending the service life of the blade root 1. The design of the segmented root 106 provides support between different parts of the blade root 1, increasing the rigidity of the blade root 1 and reducing fatigue damage caused by vibration of the blade root 1.

[0031] The stepped convex design of the segmented root 106 and the corresponding positioning groove 107 make the insertion and positioning between the blade and the wheel cover more accurate and convenient, which is beneficial to the installation of the blade and future maintenance work.

[0032] Concave grooves 108 are provided on both sides of the docking portion 101 for plug-in contact connection with the rim boss. The design of the concave grooves 108 facilitates docking and assembly of the toothed surface of the blade root 1 and the rim connecting end.

[0033] The blade body 2 is a three-dimensional linear blade body 2 adapted to the requirements of steam flow, and tie bars 3 are provided on both sides of the blade body 2 .

[0034] The blade 2 features a three-dimensional linear design, which more accurately adapts to the steam flow, improving the blade's dynamic performance and thus increasing turbine efficiency. Tie rods 3 are located on both sides of the blade 2. These reinforcement elements increase blade rigidity, reduce vibration, and prevent excessive deformation under high-speed steam flow. They also help maintain the blade's shape and increase its fatigue life.

[0035] The blade body 2 is designed with a twist angle from the root to the tip so that all cross sections of the blade can maintain an optimal bow angle to utilize steam energy with maximum efficiency.

[0036] The blades are twisted from root to tip, allowing each cross-section of the blade to maintain an optimal bow angle, maximizing steam energy utilization. The twisted blades better guide steam through the blades, reducing flow losses and improving the blade's performance.

[0037] A shroud 4 is provided on top of the blade 2. The shroud 4, ribs 3, and blade 2 are designed as an integral structure. This design further enhances the structural stability of the blade, ensuring that the blade maintains its shape under high temperature and high pressure conditions, thereby improving the overall performance of the steam turbine.

[0038] The wide-load last-stage blade of the wet-cooled steam turbine has significantly improved strength and stability at the blade root by adopting a fir-tree-shaped plug-in portion 102 and a segmented root 106 structure. The fir-tree-shaped structure provides multiple branches to be fixed to the wheel cover, forming a solid support network, effectively dispersing the stress on the blade root 1, and reducing damage to the blade root 1 caused by low-cycle fatigue and stress corrosion. The segmented root 106 structure allows the blade root 1 to be divided into several sections when bearing force, and the spacing between each section can form support between different parts, thereby reducing fatigue damage to the entire blade root 1. The design of the segmented root 106 increases the rigidity of the blade, reduces vibration, and thereby improves the operating efficiency and reliability of the steam turbine. The fir-tree-shaped plug-in portion 102 can improve the performance of the blade root in resisting corrosive environments, especially in wet-cooled environments, and can effectively reduce the occurrence of corrosion.

[0039] In general, this multiple blade root 1 design not only improves the performance and reliability of the turbine, but also helps reduce maintenance costs and improve installation efficiency.

[0040] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A wide-load last-stage blade for a wet-cooled steam turbine, comprising a single blade (100), wherein the single blade (100) comprises a blade root (1) and a blade body (2); the blade root (1) is located at the root of the blade body (2), and the blade root (1) and the blade body (2) are an integral structure; and the characteristics are: The blade root (1) adopts a multiple blade root (1) design, comprising a butt joint (101) and a plug-in joint (102) of an integral structure. The top end of the butt joint (101) is connected to the blade body (2) and the bottom end is connected to the plug-in joint (102). An outwardly convex isosceles trapezoidal convex portion (103) and an inwardly concave isosceles trapezoidal concave portion (104) are respectively provided on both sides of the butt joint (101). The plug-in joint (102) is fir-tree shaped. A rectangular hole (105) is provided in the plug-in joint (102). A plurality of parallel segmented roots (106) are arranged at equal distances in the rectangular hole (105).

2. The wet-cooled steam turbine wide-load last-stage blade according to claim 1, characterized in that: The segmented root (106) is a three-stage stepped convex shape, and each section of the segmented root (106) is designed to gradually decrease in width from top to bottom.

3. The wet-cooled steam turbine wide-load last-stage blade according to claim 2, characterized in that: Positioning grooves (107) for inserting and positioning the wheel cover are formed between two adjacent segmented roots (106) and the inner wall surface of the rectangular hole groove (105), and between the segmented roots (106) and the inner wall surface of the rectangular hole groove (105).

4. The wide-load last-stage blade for a wet-cooled steam turbine according to claim 1, characterized in that: Concave grooves (108) for plug-in contact connection with the rim boss are provided on both sides of the docking portion (101).

5. The wide-load last-stage blade for a wet-cooled steam turbine according to claim 1, characterized in that: The blade body (2) is a three-dimensional linear blade body adapted to the needs of steam flow, and tie bars (3) are provided on both sides of the blade body (2).

6. The wide-load last-stage blade for a wet-cooled steam turbine according to claim 5, characterized in that: The blade (2) is designed to be twisted from the root to the tip.

7. The wide-load last-stage blade for a wet-cooled steam turbine according to claim 6, characterized in that: A shroud (4) is provided on the top of the blade (2).

8. The wide-load last-stage blade for a wet-cooled steam turbine according to claim 7, characterized in that: The shroud (4), the tie bars (3) and the blade body (2) are designed as an integral structure.

Images