Steam turbine through-flow structure and steam turbine

Abstract

The utility model discloses a novel steam turbine through-flow structure and a steam turbine, the novel steam turbine through-flow structure comprises a plurality of stages of moving blade groups, each stage of moving blade group is provided with a plurality of moving blades, and the plurality of moving blades are connected in a whole circle through a shroud ring; and the steam seal ring is arranged at the shroud ring, is of a concave-convex table structure and is used for being matched with the shroud ring to achieve sealing. The through-flow structure solves the problems that the last three stages of blades of an existing through-flow structure of the steam turbine are free blades without shroud rings, effective damping cannot be formed to restrain vibration of the blades, and steam leakage loss of blade tops is increased; the rotor inserted tooth steam seal solves the problems that a rotor inserted tooth steam seal is not easy to maintain and poor in steam seal effect and can form a tighter steam channel by connecting the whole circle of moving blades through a shroud ring, and the leakage amount of steam between the blades is reduced. Through the sealing mode of the steam sealing ring and the structural design of the concave-convex table, the number of sealing teeth is effectively increased, the sealing efficiency is improved, and the steam sealing ring is convenient to replace and maintain after being damaged.

Description

TECHNICAL FIELD

[0001] The utility model relates to steam turbine technical field, concretely relates to a steam turbine through -flow structure and steam turbine. BACKGROUND

[0002] Steam turbine is the rotating power machinery of steam energy conversion into mechanical work, the steam from boiler enters steam turbine, and successively passes through a series of annular configuration's nozzle and moving blade, and steam heat energy is converted into the mechanical energy of steam turbine rotor rotation. Steam in steam turbine, with different ways, energy conversion, constitute different working principle steam turbine.

[0003] According to the working process of steam in moving vane, steam turbine is divided into impulse steam turbine and reaction steam turbine: impulse steam turbine refers to steam mainly expands in nozzle, and steam does not expand or expand little in moving blade, and mainly changes flow direction; Reaction steam turbine refers to the expansion degree of steam in nozzle and moving blade is basically same. Moving blade is not only subjected to the force caused by steam impact, but also subjected to the reaction force caused by steam expansion acceleration in blade.

[0004] The existing high temperature and high pressure reaction type condensing turbine unit has low steam turbine through -flow efficiency, and the steam consumption is seriously high. And the large steam consumption leads to high coal consumption, and the current power coal price is in high position, which seriously affects the economic benefit of enterprises. However, the replacement of equipment may cause the idling of the original equipment. As an important part of steam turbine energy conversion, through -flow structure is an important factor affecting through -flow efficiency, however, the last three stages of blades in steam turbine through -flow structure are free blades without surrounding band, on the one hand, cannot form effective damping to inhibit blade vibration, on the other hand, lead to the increase of blade tip steam leakage loss. In addition, the rotor inlay tooth steam seal is not easy to maintain, and the steam seal effect is poor. UTILITY MODEL CONTENTS

[0005] The utility model wants to solve the technical problem that the last three stages of blades in existing steam turbine through -flow structure are free blades without surrounding band, on the one hand, cannot form effective damping to inhibit blade vibration, on the other hand, lead to the increase of blade tip steam leakage loss, and the rotor inlay tooth steam seal is not easy to maintain, and the steam seal effect is poor. Provide a steam turbine through -flow structure and steam turbine, solve the last three stages of blades in existing steam turbine through -flow structure are free blades without surrounding band, on the one hand, cannot form effective damping to inhibit blade vibration, on the other hand, lead to the increase of blade tip steam leakage loss, and the rotor inlay tooth steam seal is not easy to maintain, and the steam seal effect is poor.

[0006] The utility model realizes by the following technical scheme:

[0007] A steam turbine through -flow structure, comprising:

[0008] The movable blade group is provided with multiple stages, each stage of the movable blade group is provided with multiple movable blades, and the multiple movable blades are connected in a whole circle by a shroud;

[0009] The steam seal ring is provided at the shroud and is in a concave-convex structure, and is used for cooperating with the shroud to realize sealing.

[0010] As one of the preferred technical solutions, a partition plate is further included, and the partition plate is a full-cold-state-installed assembled partition plate.

[0011] As one of the preferred technical solutions, a stationary blade is installed in the partition plate, and the stationary blade is a bending-torsion composite shaped blade.

[0012] As one of the preferred technical solutions, the root of the movable blade and the root and top of the stationary blade are all designed to be smooth.

[0013] As one of the preferred technical solutions, an adjusting stage blade is further included, and the adjusting stage blade includes a nozzle group blade and an adjusting stage movable blade; the nozzle group blade is a bending blade, and the adjusting stage movable blade is a variable cross-section torsion blade.

[0014] As one of the preferred technical solutions, the shroud is in an inner-inclined and outer-flat structure, and the top of the shroud is provided with high-low teeth.

[0015] As one of the preferred technical solutions, the steam seal ring and the high-low teeth jointly form a high-low teeth labyrinth steam seal structure.

[0016] As one of the preferred technical solutions, the movable blade group further includes a last stage blade, and the last stage blade is a non-adjusted frequency blade.

[0017] As one of the preferred technical solutions, the movable blade is made of alloy steel or stainless steel.

[0018] The utility model further provides a steam turbine with the steam turbine through-flow structure.

[0019] Compared with the prior art, the utility model has the following advantages and beneficial effects:

[0020] 1. The movable blades are connected in a whole circle by the shroud, a more compact steam passage can be formed, and the steam leakage amount between the blades is reduced. This design not only improves the thermal efficiency of the steam turbine, but also helps to maintain a stable steam flow state and ensure efficient operation of the steam turbine. Thus, the dynamic stress can be significantly reduced, and the steam leakage loss can be reduced.

[0021] 2. The sealing form of the steam seal ring and the structure design of the concave-convex platform effectively increase the number of sealing teeth and improve the sealing efficiency. After the steam seal ring is damaged, the steam seal ring can be conveniently replaced and maintained. DETAILED DESCRIPTION

[0022] In order to more clearly illustrate the technical scheme in the example embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows, and it should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can also be obtained without creative labor on the basis of the drawings. In the drawings:

[0023] Figure 1 The figure is a structural schematic diagram of the present application;

[0024] Figure 2 The figure is a structural schematic diagram of the surrounding band of the moving blade group of the present application;

[0025] Figure 3 The figure is a schematic diagram of the cooperation relationship between the steam seal ring and the surrounding band of the present application;

[0026] Figure 4 The figure is a structural schematic diagram of the nozzle group blade of the present application.

[0027] The marks in the drawings and the corresponding component names are as follows:

[0028] 1-moving blade, 11-final stage blade, 2-surrounding band, 3-steam seal ring, 4-stationary blade, 5-high-low tooth, 6-baffle. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application more clear and understandable, the present application will be further described in detail below in combination with embodiments and drawings, and the schematic embodiments of the present application and the description thereof are only used to explain the present application, and should not be considered as limiting the present application.

[0030] The embodiments of the present application will be described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in the present description. The present application can also be implemented or applied through other different specific embodiments, and each detail in the present description can be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the drawings provided in the following embodiments only illustrate the basic concept of the present application in a schematic manner, and the following embodiments and the features in the embodiments can be combined with each other without conflict.

[0031] Among them, the drawings are only used for example illustration, and the representation is only a schematic diagram, not a physical diagram, and should not be understood as limiting the present application; in order to better illustrate the embodiments of the present application, some components in the drawings will be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it can be understood that some known structures in the drawings and their description can be omitted.

[0032] Example 1

[0033] In existing steam turbine flow paths, the last three stages of blades are free blades without shrouds. This not only fails to provide effective damping to suppress blade vibration but also increases steam leakage at the blade tips. Furthermore, the rotor toothed steam seals are difficult to maintain and have poor sealing performance.

[0034] Based on the above problems, this utility model provides a novel steam turbine flow path structure, such as... Figure 1 and Figure 2 As shown, it includes:

[0035] The turbine blade assembly has multiple stages, with each stage containing multiple moving blades 1. These moving blades 1 are connected in a continuous loop by a shroud 2. Connecting the moving blades 1 in a continuous loop with the shroud 2 creates a tighter steam passage, reducing steam leakage between the blades. This design not only improves the turbine's thermal efficiency but also helps maintain a stable steam flow state, ensuring efficient turbine operation. This significantly reduces dynamic stress and steam leakage losses.

[0036] The steam seal ring 3, located at the shroud 2, has a boss-and-concave structure and is used to mate with the shroud 2 to achieve a seal. Through the sealing method of the seal ring and the boss-and-concave structure design, the number of sealing teeth is effectively increased, improving sealing efficiency. The steam seal ring 3 is easy to replace and repair when damaged.

[0037] Specifically, the retaining band 2 has an inner sloping and outer flat structure, and its top is provided with high and low teeth 5. Specifically, the inner part of the retaining band 2 is sloping, while the outer side remains flat. This design not only enhances the structural strength of the retaining band 2 but also helps optimize fluid dynamics performance. The sloping inner side helps guide fluid flow along a specific path, reducing the formation of eddies and turbulence, thereby reducing energy loss. The flat outer design facilitates the cooperation and installation with adjacent components, ensuring the stability and reliability of the entire system.

[0038] Furthermore, such as Figure 3 As shown, the steam seal ring 3 and the high-low teeth 5 together form a labyrinthine steam seal structure. The steam seal ring 3, as a crucial component of the steam seal system, functions to fit tightly against the rotor, preventing steam or other working media from leaking from the high-pressure area to the low-pressure area. When the steam seal ring 3 and the high-low teeth 5 are combined, they form a complex labyrinthine channel. The staggered arrangement of the high-low teeth 5 within this channel forces the fluid to constantly change direction as it passes through, significantly increasing the difficulty of leakage and enhancing the sealing performance.

[0039] The moving blade 1 is made of alloy steel or stainless steel. Specifically, this embodiment designs a total of 29 moving blade groups. The moving blades 1 of the first to 25th moving blade groups are made of CrMoV alloy steel. These moving blades 1 typically incorporate multiple alloying elements such as chromium, molybdenum, and vanadium. The addition of these elements not only significantly enhances the mechanical strength of the blades but also improves their heat resistance and creep resistance under high temperature and high pressure environments, making the alloy steel moving blades 1 key components in rotating machinery such as steam turbines and gas turbines that withstand extreme operating conditions. The moving blades 1 of the 26th to 29th moving blade groups are made of martensitic stainless steel, enabling the moving blades 1 to obtain high strength, high hardness, and good wear resistance. While rotating at high speed and withstanding huge centrifugal forces, they can still maintain excellent mechanical properties and stability. In addition, martensitic stainless steel also has good corrosion resistance, enabling it to maintain a long service life in various harsh environments.

[0040] Example 2

[0041] Based on Embodiment 1, this embodiment is configured to further include a partition 6, wherein the partition 6 is a prefabricated partition 6 installed in a completely cold state.

[0042] The beneficial effects are as follows: Firstly, the completely cold-fitting method can maximize the throat width and installation angle of the baffle 6. The final formed dimensions allow for precise control of the flow area of ​​the baffle 6, ensuring the quality of the final product and its actual operational performance.

[0043] On the other hand, all welding can be eliminated, and the stationary blade 4 can be directly assembled onto the inner cylinder or retaining ring. The inner cylinder and stationary blade 4 can be assembled as a whole at the manufacturing plant before shipment. During on-site construction, only the center of the inner cylinder and retaining ring needs to be located. Maintenance and repair also save a lot of disassembly and reassembly work. If the stationary blade 4 is partially damaged, only the damaged blade can be replaced, significantly reducing accident handling costs. The convenience and economy of the unit's installation, adjustment, maintenance and repair are greatly improved.

[0044] Furthermore, the moving and stationary blades 4 are core components of the turbine's flow path, and their performance directly affects the turbine's flow efficiency. Adopting advanced moving and stationary blade designs can significantly improve the unit's flow efficiency. Based on this, this embodiment optimizes the blade profile. Specifically, the blade design is achieved through iterative interactions of one-dimensional thermodynamic calculations, quasi-three-dimensional aerodynamic-thermal design, and three-dimensional / four-dimensional aerodynamic design and structural strength design. One-dimensional thermodynamic design and quasi-three-dimensional aerodynamic-thermal design optimize the enthalpy drop distribution of each stage of the turbine and the reaction degree within each stage, enabling each stage or cylinder to achieve global or local optimization. In terms of aerodynamic design, various methods such as optimizing the blade profile, optimizing the blade stacking form, optimizing dynamic-static matching, and considering the interaction between leakage flow and the mainstream flow are used to optimize the design of each stage and component. The interaction with structural strength design ensures the usability and reliability of the design.

[0045] Furthermore, the flow of steam inside a steam turbine is a three-dimensional, viscous, and unsteady flow state. Its unsteady flow characteristics have a significant impact on the accurate simulation of its physical field. When conducting aerodynamic analysis, unsteady factors need to be incorporated into the design system. The unsteady effects of the flow field between the moving and stationary blade rows during turbine operation must be analyzed to comprehensively assess their impact on flow characteristics. Based on the mutual interference between the moving and stationary blade rows, the number and profile of the moving and stationary blades should be rationally matched to further improve stage efficiency.

[0046] Subsequently, multi-channel and multi-stage calculations were performed on the blade stages under different operating conditions to obtain detailed flow field characteristics including dynamic and static disturbances. Corresponding measures were then taken for different situations to improve the internal flow of the entire stage and multi-stage blade cascade channels and increase flow efficiency.

[0047] Based on the above theories and experiments, the following configuration is established: a stationary blade 4 is installed within the diaphragm 6. The stationary blade 4 is a composite bent-twisted blade, possessing characteristics of both bent and twisted blades. This design allows the blade to better adapt to the flow characteristics of fluids (such as airflow or waterflow), improving the fluid dynamics performance. By optimizing and controlling the blade stacking line and the angle distribution curve along the blade height, the generation and development of secondary flow at the endwall are suppressed, reducing the flow expansion of the main flow towards the wall, thereby effectively reducing secondary flow losses and improving stage efficiency. Simultaneously, the dense flow is concentrated in the more efficient central section, resulting in even smaller flow losses across the entire blade cascade. Furthermore, optimal matching of the flow field between the moving and stationary blades is achieved at each cross-section of the blades in this stage, effectively improving both the efficiency within the stationary blades and significantly enhancing the flow field within the moving blades.

[0048] Furthermore, the existing unit's low-pressure module selection is inappropriate, the last-stage blade 11 is too short, and the small flow passage and exhaust area results in significant residual velocity loss, which has a noticeable impact on the unit's steam consumption. Based on these issues, the design is as follows: the moving blade assembly also includes a last-stage blade 11, which is a non-frequency-tuned blade. Specifically, the non-frequency-tuned blade can directly respond to changes in the steam conditions inside the turbine without external signal control, greatly enhancing its adaptability and flexibility.

[0049] In addition, the last-stage blade 11 can be enhanced by laser solid solution strengthening treatment, which can improve the active and passive protection capabilities of the last-stage blade 11.

[0050] In addition, due to the large enthalpy drop of the regulating stage, which has a significant impact on the overall efficiency, and the high operating temperature, complex operating conditions, and large influence from load fluctuations, the working environment is harsh. Therefore, in order to improve the efficiency of the regulating stage, safety must be given high priority. Thus, before the design, high-standard strength verification was carried out on the moving and stationary blades, and modal analysis was performed on the entire ring connection of the moving blades.

[0051] Based on the above analysis, this embodiment is configured to further include an adjustment stage blade, wherein the adjustment stage blade includes a nozzle group blade and an adjustment stage moving blade; the nozzle group blade is a curved blade, and the adjustment stage moving blade is a variable cross-section torsion blade.

[0052] like Figure 4 As shown, the nozzle blades, through their unique curved shape, can more effectively guide steam flow, reduce flow losses, and enhance the impact force of steam on the moving blades, thereby improving energy conversion efficiency. This blade design not only optimizes the steam flow path but also reduces the formation of eddies and turbulence, further reducing energy loss.

[0053] The blade cross-section and torsion angle of the regulating stage moving blades are adjusted according to the change in steam flow direction. This design allows the moving blade 1 to better adapt to the expansion process of steam in different pressure stages, ensuring that steam can effectively perform work in each stage of the moving blade 1. By accurately calculating and adjusting the cross-sectional shape and torsion angle of the blades, the variable cross-section torsion blades can maximize the kinetic energy conversion efficiency of steam, thereby enhancing the overall performance of the steam turbine.

[0054] High-efficiency curved blades and variable cross-section twisted blades also help reduce turbine noise and vibration levels. By optimizing blade shape and arrangement, these designs reduce the impact and friction of steam between blades, thereby reducing noise generation. At the same time, blade stability and rigidity are enhanced, helping to reduce the impact of vibration on turbine operation.

[0055] Example 3

[0056] In existing turbine units, the smoothness of the flow path in the meridional plane is insufficient, resulting in significant flow losses. Furthermore, the roots of the stationary blade 4 and the tops and roots of the moving blade 1 are all straight, failing to achieve optimal flow channel design. Based on these issues, this embodiment proposes a design where the roots of the moving blade 1 and the roots and tops of the stationary blade 4 are all smoothly designed, thereby reducing flow losses in the meridional plane. Specifically, the blades are formed in a single milling operation on a five-axis machine tool from square steel blanks, achieving high machining precision for each blade. Combined with the outer flat and inner inclined circumferential band 2 structure of the moving blade 1, smooth flow on the upper and lower walls of the meridional plane is ensured.

[0057] Example 4

[0058] This embodiment 4 also provides a steam turbine for using the flow passage structure described in embodiment 1.

[0059] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this utility model. It should be understood that the above description is only a specific embodiment of this utility model and is not intended to limit the scope of protection of this utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the scope of protection of this utility model.

Claims

1. A steam turbine flow path structure, characterized in that, include: The moving blade assembly has multiple levels, and each level of the moving blade assembly has multiple moving blades, which are all connected in a complete circle by a surrounding belt; The steam seal ring is located at the sealing strip and has a concave-convex structure. It is used to cooperate with the sealing strip to achieve a seal.

2. The turbine flow path structure according to claim 1, characterized in that, It also includes a partition, which is a prefabricated partition installed in a completely cold state.

3. The turbine flow path structure according to claim 2, characterized in that, The partition is equipped with stationary blades, which are bent-twisted composite blades.

4. The turbine flow path structure according to claim 3, characterized in that, The root of the moving blade and the root and top of the stationary blade are both designed to be smooth.

5. The turbine flow path structure according to claim 1, characterized in that, It also includes regulating stage blades, which include nozzle group blades and regulating stage moving blades; the nozzle group blades are curved blades, and the regulating stage moving blades are variable cross-section torsion blades.

6. The turbine flow path structure according to claim 1, characterized in that, The surrounding band has an inner sloping and outer flat structure, and its top is provided with high and low teeth.

7. The turbine flow path structure according to claim 6, characterized in that, The steam seal ring and the high and low teeth together form a high and low tooth labyrinth steam seal structure.

8. The turbine flow path structure according to claim 1, characterized in that, The moving blade assembly also includes a final-stage blade, which is a non-frequency-tuned blade.

9. The turbine flow path structure according to claim 1, characterized in that, The moving blades are made of alloy steel or stainless steel.

10. A steam turbine employing the steam turbine flow path structure as described in any one of claims 1-9.

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