Stator blade of steam turbine

Abstract

The invention provides a steam turbine stator blade. The steam turbine stator blade comprises an outer ring; the blade molded line part is arranged between the outer ring and the inner ring so as to form a steam flowing channel; the inner ring is arranged in the blade molded line part; the inner ring gland sealing teeth are arranged on the inner cylindrical surface of the inner ring; and the inner ring rotation resisting teeth are arranged on the inner cylindrical surface of the inner ring and located at the upstream position of the inner ring steam sealing teeth in the steam flowing direction. According to the steam turbine stator blade, the flowing condition of a pressure stage inlet can be improved, the rotational flow strength of a steam seal position is reduced, and the economic performance and the operation stability of a steam turbine are improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of steam turbines, and in particular to a stationary blade of a steam turbine. Background Art

[0002] In the current domestic power generation field, with the increasing proportion of installed capacity of new energy power generation year by year, more and more thermal power units no longer only bear basic loads, but need to cooperate with grid dispatching to bear peak load regulation functions, resulting in frequent changes in unit loads over a large range. The change in operating mode makes the turbine regulating stage have the characteristics of large enthalpy drop and large range of operating conditions. There is a large radial height difference between the regulating stage and the pressure stage. In a limited space, the regulating stage wake needs to undergo multiple turns before entering the pressure stage. The regulating stage adopts partial steam inlet, and the regulating stage wake has discontinuous and uneven distribution characteristics along the circumferential direction. When the unit load changes, the regulating stage speed ratio changes accordingly, causing the circumferential velocity of the regulating stage wake to change over a large range.

[0003] In the first pressure stage after the regulating stage, the design of the traditional stator blade profile often ignores the adverse effect of the non-uniformity of the regulating stage wake on its inlet flow conditions, resulting in the efficiency of this pressure stage being significantly lower than the design value, affecting the economic performance of the unit. The design of the traditional stator blade inner ring steam seal often ignores the adverse effect of the circumferential component velocity of the regulating stage wake, resulting in a higher pre-swirl velocity of the inner ring steam seal leakage, which reduces the stability of the turbine rotor and endangers the operation safety of the unit. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] In view of the above problems, the present disclosure provides a steam turbine stator blade to at least partially solve the current technical problems of low steam turbine pressure stage efficiency, low output power, poor unit economic performance and low rotor stability.

[0006] (II) Technical solution

[0007] The present disclosure provides a steam turbine stator blade, comprising: an outer ring; a blade profile portion, arranged between the outer ring and the inner ring to form a channel for steam flow; an inner ring, arranged inside the blade profile portion; inner ring steam seal teeth, arranged on the inner cylindrical surface of the inner ring; inner ring anti-rotation teeth, arranged on the inner cylindrical surface of the inner ring and located upstream of the inner ring steam seal teeth in the steam flow direction.

[0008] According to an embodiment of the present disclosure, the blade profile portion is a variable-section bent and twisted blade.

[0009] According to an embodiment of the present disclosure, the cross-sectional area of ​​the blade profile portion gradually decreases from the root to the top of the blade profile along the blade height direction.

[0010] According to an embodiment of the present disclosure, the inner ring steam seal teeth adopt high and low tooth comb teeth, helical teeth or flat teeth steam seals.

[0011] According to an embodiment of the present disclosure, the axial width of the inner ring is greater than the axial width of the outer ring.

[0012] According to an embodiment of the present disclosure, in the passage where steam flows, the steam inlet side end surface of the inner ring is located in an upstream direction of the steam inlet side end surface of the outer ring.

[0013] According to an embodiment of the present disclosure, a ratio of a pitch of a blade root cross section of the blade profile portion to a blade profile chord length is less than or equal to a first preset threshold.

[0014] According to an embodiment of the present disclosure, two adjacent blades of the blade profile portion form a cascade channel at the root, the ratio of the throat width to the channel length of which is less than or equal to a second preset threshold.

[0015] According to an embodiment of the present disclosure, the inner ring anti-rotation teeth are arranged at a preset angle to the axial direction of the inner ring / outer ring.

[0016] According to an embodiment of the present disclosure, the inclination angle at which the inner ring anti-rotation tooth is installed relative to the reference direction is the same as the inclination angle at which the blade profile portion is installed.

[0017] (III) Beneficial effects

[0018] The steam turbine stator blade provided by the present disclosure has at least the following beneficial effects:

[0019] 1. The specially designed blade profile regulates and constrains the evolution of the regulating stage wake, improves the uniformity of the flow distribution at the inlet of the pressure stage static blades, and suppresses the flow separation at large angles of attack, thereby improving the efficiency and output power of the pressure stage.

[0020] 2. The specially designed inner ring steam seal tooth structure improves the sealing performance of the inner ring steam seal of the pressure stage stationary blade, reduces the steam seal leakage, and thus improves the efficiency and output power of the pressure stage. At the same time, it reduces the swirl intensity of the inner ring steam seal leakage steam entering the steam seal chamber, reduces the force of the steam seal leakage steam on the rotor, and improves the operating stability of the turbine rotor.

[0021] 3. The stationary blades disclosed in the present invention have a simple structure, are easy to manufacture, are easy to modify and upgrade on existing steam turbines, and have broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, in which:

[0023] Figure 1The schematic diagram of the whole circle assembly of the steam turbine stationary blades provided by the embodiment of the present disclosure is shown schematically;

[0024] Figure 2 A schematic diagram shows a front view of a steam turbine stator blade provided by an embodiment of the present disclosure;

[0025] Figure 3 A schematic top view of a steam turbine stator blade provided by an embodiment of the present disclosure is shown;

[0026] Figure 4 The flow field distribution of the first stage inlet of the pressure stage provided by the embodiment of the present disclosure using conventional stationary blades and stationary blades with the structure disclosed in the present disclosure is schematically shown.

[0027] Description of Reference Numerals

[0028] 1-Outer ring;

[0029] 2-blade profile part;

[0030] 3-Inner ring;

[0031] 4-Inner ring steam seal teeth;

[0032] 5-Inner ring anti-rotation gear. DETAILED DESCRIPTION

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the following detailed description, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0034] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0035] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0036] The disclosed embodiment provides a steam turbine stator blade, which reduces the swirl intensity of the inner ring steam seal leakage steam entering the steam seal chamber, reduces the force of the steam seal leakage steam on the rotor, and improves the operating stability of the steam turbine rotor.

[0037] Figure 1 A schematic diagram of the full circle assembly of a steam turbine stationary blade provided by an embodiment of the present disclosure is shown schematically.

[0038] Figure 2 and Figure 3 The front view and top view of the steam turbine stator blade provided by the embodiment of the present disclosure are schematically shown respectively.

[0039] like Figure 1 , Figure 2 and Figure 3 As shown, the turbine stationary blade provided by the embodiment of the present disclosure includes: an outer ring 1, a blade profile portion 2, an inner ring 3, inner ring steam seal teeth 4 and inner ring anti-rotation teeth 5.

[0040] The outer ring 1, as the outer peripheral part of the stationary blade, can be connected to the casing or other fixed parts of the steam turbine.

[0041] The blade profile part 2 is arranged between the outer ring 1 and the inner ring 3 to form a channel for steam flow (the projected length of the flow channel in the direction of fluid flow). The steam expands and accelerates in this part, converting thermal energy into kinetic energy. The blade profile part 2 is a variable-section bending and twisting blade. From the root to the tip of the blade, not only does the cross-section of the blade change, but the generatrix of the blade also presents a curved state. The cross-sectional area of ​​the blade gradually decreases from the root to the top along the blade height direction, which is different from the traditional static blade with a larger cross-sectional area at the top than at the root.

[0042] Exemplarily, the cross-sectional area of ​​the root of the airfoil is 3.03 times the cross-sectional area of ​​the tip.

[0043] Furthermore, the root section of the blade profile part 2 has an extremely low relative pitch (for example, 0.341), which is much lower than the relative pitch of conventional stationary blades. That is, the ratio of the pitch of the blade root section of the blade profile part 2 to the blade chord length is less than or equal to a first preset threshold, and the first preset threshold is extremely low. Two adjacent blades form a narrow blade channel at the root, and the ratio of the throat width (in the blade cascade, the narrowest part of the flow channel surrounded by two adjacent blades, whose width is the throat width) to the channel length is less than or equal to a second preset threshold.

[0044] Exemplarily, two adjacent blades form a narrow blade channel at the root with a ratio of throat width to channel length of only 0.174, which is much smaller than a traditional stationary blade channel.

[0045] It is understandable that the narrow blade channel can force the fluid to accelerate when passing through by reducing the throat width, which helps to convert the kinetic energy of the fluid into pressure energy, thereby improving the efficiency of the compressor or turbine. At the same time, it also helps to reduce the vortex and separation of the fluid in the channel, guide the fluid to flow along a stable path, thereby improving the stability and reliability of the equipment.

[0046] In the embodiment of the present disclosure, the inner ring 3 is arranged inside the blade profile portion 2, and has an axial width greater than that of the outer ring 1, wherein the axial width is the dimension along its axial direction (ie, length direction).

[0047] Exemplarily, the axial width B1 of the inner ring 3 is 2.28 times the axial width B2 of the outer ring 1 .

[0048] Furthermore, in the steam flow channel, the steam inlet side end surface of the inner ring 3 (the end surface portion adjacent to the steam inlet) is located in the upstream direction of the steam inlet side end surface of the outer ring 1 .

[0049] Exemplarily, the distance between the steam inlet side end faces of the inner ring 3 and the outer ring 1 is 1.28 times the axial width of the outer ring 1 .

[0050] In some exemplary embodiments, the inner ring steam seal teeth 4 are arranged on the inner cylindrical surface of the inner ring 3, and high and low tooth comb teeth, oblique teeth or flat teeth steam seals can be used.

[0051] Among them, the high-low comb-tooth steam seal tooth shape forms a staggered sealing gap through the alternating arrangement of high teeth and low teeth, which can not only effectively prevent the axial leakage of the fluid, but also produce a certain pumping effect during the rotation process, helping to redirect the leaked fluid back to the main channel, thereby improving the overall sealing efficiency. The helical tooth steam seal optimizes the flow path of the fluid between the teeth through the inclined tooth shape design, reduces the eddy current and energy loss caused by the direct impact of the fluid on the tooth surface, and at the same time, the helical teeth can also adapt to the slight deflection of the shaft to a certain extent and maintain stable sealing contact.

[0052] The flat tooth steam seal has a smooth tooth surface that is easy to process and maintain, and can effectively block most fluid leakage. It is suitable for low-speed environments or environments where sealing requirements are not particularly stringent.

[0053] On the basis of the above embodiment, in this embodiment, the inner ring anti-rotation tooth 5 is arranged on the inner cylindrical surface of the inner ring 3, for preventing or slowing down the rotation speed of the rotating part, or for providing a certain damping effect. At the same time, the inner ring anti-rotation tooth 5 is located upstream of the inner ring steam seal tooth 4 in the steam flow direction, that is, the inner ring anti-rotation tooth 5 is located at the front end of the inner ring steam seal tooth 4, so as to utilize the damping effect of the inner ring anti-rotation tooth 5 to reduce the fluid leakage at the inner ring steam seal tooth 4 or the vibration of the rotating part.

[0054] Furthermore, the inner ring anti-rotation tooth 5 is arranged at a preset angle (for example, 45°) with the axial direction (i.e., the centerline direction of the device) to prevent steam or other fluids from leaking from the high-pressure area to the low-pressure area, thereby improving the sealing performance of the device, and can also enhance its adaptability to changes in pressure differences, ensuring the stable operation of the device under various working conditions. The installation angle direction of the inner ring anti-rotation tooth 5 is the same as the installation angle direction of the blade profile part 2, that is, the inclination angle installed relative to the reference direction (such as the axial direction, radial direction or the centerline direction of the device) is the same as the inclination angle installed at the blade profile part 2, thereby ensuring that the fluid can be guided in a consistent and coordinated manner when flowing through these two components, reducing the turbulence of the fluid flow and improving the overall fluid dynamics efficiency. In addition, the consistency of the installation angles of the inner ring anti-rotation tooth 5 and the blade profile part 2 can also enable the device to cut the fluid in a more stable manner during rotation, whether it is the inner ring anti-rotation tooth 5 or the blade profile part 2, reducing the vibration and noise caused by fluid impact, and extending the service life of the equipment. At the same time, it also helps to improve the overall rigidity and stability of the equipment, so that the equipment can still maintain excellent sealing effect and operating performance when subjected to greater pressure or load.

[0055] Embodiment 1:

[0056] When a 300MW steam turbine is running at 75% rated load (tha), the absolute steam outlet angle of its moving blades is only 36 degrees. Figure 4 As shown in the schematic diagram on the left, under this specific operating condition, if a conventional stator blade design is used, the flow distribution at the inlet of the first stage stator blade of the pressure stage will be significantly uneven, resulting in a significant negative impact on the overall performance of the steam turbine. In order to solve this problem, after adopting the stator blade disclosed in the present invention, Figure 4 As shown in the schematic diagram on the right, the flow uniformity at the inlet of the first-stage stator blades of the pressure stage has been greatly improved. Specifically in terms of performance, the total output of the regulating stage and the first-stage pressure stage has increased by about 380kw compared with before, and this increase accounts for 0.15% of the total machine output.

[0057] It can be understood that the stationary blades in the embodiment of the present disclosure effectively improve the flow conditions at the pressure stage inlet and improve the pressure stage efficiency through the specially designed blade profile part. At the same time, the stationary blades reduce the steam leakage of the steam seal through the specially designed inner ring steam seal tooth structure, and effectively reduce the swirl intensity at the inner ring steam seal, thereby improving the operating stability of the turbine rotor.

[0058] It will be appreciated by those skilled in the art that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways without departing from the spirit and teachings of the present disclosure. All of these combinations and / or combinations fall within the scope of the present disclosure.

[0059] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A steam turbine stator blade, characterized in that: include: Outer ring; The blade profile part is arranged between the outer ring and the inner ring to form a passage for the steam to flow; An inner ring, arranged inside the blade profile portion; Inner ring steam seal teeth, arranged on the inner cylindrical surface of the inner ring; The inner ring anti-rotation teeth are arranged on the inner cylindrical surface of the inner ring and are located upstream of the inner ring steam seal teeth in the steam flow direction.

2. The steam turbine stator blade according to claim 1, characterized in that: The blade profile part is a variable-section bent and twisted blade.

3. The steam turbine stator blade according to claim 1 or 2, characterized in that: The cross-sectional area of ​​the blade profile portion gradually decreases from the root to the top of the blade along the blade height direction.

4. The steam turbine stator blade according to claim 1, characterized in that: The inner ring steam seal teeth adopt high and low tooth comb teeth, oblique teeth or flat teeth steam seals.

5. The steam turbine stator blade according to claim 1, characterized in that: The axial width of the inner ring is greater than the axial width of the outer ring.

6. The steam turbine stator blade according to claim 1, characterized in that: In the passage where steam flows, the steam inlet side end surface of the inner ring is located in the upstream direction of the steam inlet side end surface of the outer ring.

7. The steam turbine stator blade according to claim 1, characterized in that: The ratio of the pitch of the blade root section of the blade profile part to the blade profile chord length is less than or equal to a first preset threshold.

8. The steam turbine stator blade according to claim 1 or 7, characterized in that: Two adjacent blades of the blade profile portion form a cascade channel at the root, the ratio of the throat width to the channel length of which is less than or equal to a second preset threshold.

9. The steam turbine stator blade according to claim 1, characterized in that: The inner ring anti-rotation teeth are arranged at a preset angle to the axial direction of the inner ring / outer ring.

10. The steam turbine stator blade according to claim 1 or 9, characterized in that: The inclination angle at which the inner ring anti-rotation tooth is installed relative to the reference direction is the same as the inclination angle at which the blade profile portion is installed.

Images