A flutter-resistant turbine last-stage moving blade assembly

Abstract

This invention relates to the field of steam turbine technology, and more particularly to a flutter-resistant steam turbine last-stage moving blade assembly, comprising: a group of last-stage moving blades, a group of blade tip shrouds, and a flutter-resistant assembly. The combined arrangement of the last-stage moving blades, blade tip shrouds, and flutter-resistant assembly makes the connection between the blade tip shrouds more stable. The damping effect of spring plates and steel columns on the last-stage moving blades effectively reduces the amplitude and frequency of flutter. This enhances the dynamic strength of the low-pressure last-stage moving blades, ensuring the safe and stable operation of the steam turbine unit. It solves the problem of insufficient strength of the low-pressure last-stage moving blades under low steam flow conditions, enabling the steam turbine unit to operate safely and stably even when the load factor drops to 30%–40% of the rated load due to large peak-to-valley differences in grid load.

Description

Technical Field

[0001] This invention relates to the field of steam turbine technology, and in particular to a flutter-resistant steam turbine last-stage moving blade assembly. Background Technology

[0002] Coal-fired power generation will remain an important part of my country's energy system for the foreseeable future. However, with the slowdown in the growth rate of electricity demand and the large-scale development of renewable energy, the utilization hours of coal-fired power plants will decline year by year. Therefore, improving the operational flexibility of coal-fired power units and their large-scale participation in deep grid peak shaving will be an inevitable trend.

[0003] How to complete the flexibility transformation of 220 million kilowatts of thermal power units and enhance the power system's regulation capacity by 46 million kilowatts, especially prioritizing the enhancement of the deep peak-shaving capacity of 300,000-kilowatt coal-fired power units, so that the minimum technical output of the transformed condensing units can reach 30% to 40% of the rated capacity, and the minimum technical output of the cogeneration units can reach 40% to 50% of the rated capacity, is a matter of great concern to technical personnel in the field.

[0004] For the reasons mentioned above, steam turbines need to operate in a low load range for a long time. When operating at low load, due to the low steam flow rate, the low-pressure last-stage moving blades of the steam turbine will flutter, affecting the dynamic strength of the last-stage moving blades and seriously threatening the safe and stable operation of the steam turbine unit. Summary of the Invention

[0005] (a) Technical problems to be solved

[0006] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a turbine last-stage moving blade assembly for flutter prevention, which solves the technical problem that the low-pressure last-stage moving blade of the turbine experiences flutter due to the low steam flow rate during low-load operation, thus affecting the dynamic strength of the last-stage moving blade.

[0007] (II) Technical Solution

[0008] To achieve the above objectives, the main technical solutions adopted by the present invention include:

[0009] A flutter-resistant turbine last-stage moving blade assembly includes: multiple last-stage moving blades arranged around the turbine rotor, multiple blade tip shrouds, and a flutter-resistant assembly;

[0010] The plurality of blade top shrouds and the plurality of final stage moving blades are arranged in a one-to-one correspondence, and the blade top shrouds are located on the top of the final stage moving blades. Two adjacent final stage moving blades are connected by the blade top shrouds above them, and the anti-flutter assembly is located at the connection of two adjacent blade top shrouds.

[0011] The anti-flutter assembly includes a plug, a pair of spring plates, and a steel column;

[0012] The plug is disposed at the connection of two adjacent blade tip shrouds;

[0013] The plug body has a cavity inside, the spring sheet is fixed to the inner wall of the cavity, and the steel column is clamped between two opposing spring sheets so that the steel column is suspended inside the plug body by the spring sheets.

[0014] One end of the blade tip shroud is provided with a slot, and the other end of the blade tip shroud is provided with an insert that matches the shape of the slot. Two adjacent blade tip shrouds are connected to the insert of the other blade tip shroud through the slot of one blade tip shroud.

[0015] The bottom of the slot and insert of each pair of adjacent blade top bands is provided with a threaded hole facing upwards, and the plug is screwed into the threaded hole.

[0016] The slot is a rectangular slot, and the insert is a rectangular insert.

[0017] The cavity of the plug is cylindrical.

[0018] The threaded hole is integrally formed with the blade tip shroud.

[0019] The blade tip shroud and the final stage moving blade are integrally formed.

[0020] The thickness of the blade tip shroud is 18-22 mm.

[0021] The steel column has a diameter of 8-12mm and a height of 8-12mm; the spring sheet has a thickness of 0.6-0.8mm.

[0022] (III) Beneficial Effects

[0023] The beneficial effects of this invention are as follows: This invention provides a turbine last-stage moving blade assembly for flutter prevention. By combining the last-stage moving blade, the blade tip shroud, and the flutter prevention assembly, the connection between the blade tip shrouds is made more stable, enhancing the dynamic strength of the low-pressure last-stage moving blade, ensuring the safe and stable operation of the turbine unit, and solving the problem of insufficient strength of the low-pressure last-stage moving blade under low steam flow. This enables the turbine unit to ensure safe and stable operation of the low-pressure last-stage moving blade even when the load rate drops to 30% to 40% of the rated load due to a large peak-to-valley difference in grid load.

[0024] In particular, the present invention generates a damping effect on the last-stage moving blade through spring plates and steel columns, effectively reducing the amplitude and frequency of flutter of the last-stage moving blade. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the plug body and its internal structure according to the present invention.

[0027] [Explanation of Labels in the Attached Image]

[0028] 1: First-stage moving blade;

[0029] 2: Second-stage moving blade;

[0030] 3: The top band of the first leaf;

[0031] 4: The top band of the second leaf;

[0032] 5: Plug body;

[0033] 6: Spring sheet;

[0034] 7: Steel column. Detailed Implementation

[0035] To better explain and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. In this document, directional terms such as "upper," "lower," etc., are used interchangeably with other directional terms. Figure 1 The orientation is used as a reference.

[0036] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0037] The present invention provides a turbine last-stage moving blade assembly for flutter prevention, wherein several turbine last-stage moving blade assemblies are arranged around the turbine rotor.

[0038] The turbine last-stage moving blade assembly includes: multiple last-stage moving blades arranged around the turbine rotor, multiple blade tip shrouds, and anti-flutter components;

[0039] Multiple blade tip shrouds and multiple final-stage moving blades are arranged in a one-to-one correspondence, with the blade tip shrouds positioned on top of the final-stage moving blades. The final-stage moving blades are connected by the blade tip shrouds, and anti-flutter components are positioned between two adjacent blade tip shrouds. The blade tip shrouds and final-stage moving blades are integrally machined for easy assembly and disassembly.

[0040] Optionally, the thickness of the leaf tip circumference is 18-22 mm.

[0041] One end of the leaf tip shroud has a slot, and the other end has an insert that matches the shape of the slot. Two adjacent leaf tip shrouds are connected by the slot and the insert.

[0042] Optionally, in this embodiment, the slot is a rectangular slot and the insert is a rectangular insert, so that the shapes of the slot and the insert match and the connection is tighter.

[0043] The anti-flutter assembly includes: plug 5, spring plate 6, and steel column 7.

[0044] The plug body 5 is cylindrical, with an internal cavity. Spring plates 6 and steel columns 7 are disposed within the cavity of the plug body 5. An even number of spring plates 6 are arranged, and the steel columns 7 are sandwiched between two opposing spring plates 6. One end of a spring plate 6 abuts against the plug body 5, and the other end abuts against the steel column 7, causing the steel column 7 to suspend within the cavity of the plug body 5 via the spring plates 6. This allows the steel column 7 to dampen the spring plates 6 when subjected to flutter, achieving an anti-flutter effect.

[0045] Optionally, the diameter of the steel column 7 is 8-12mm and the height is 8-12mm.

[0046] Optionally, the thickness of the spring sheet 6 is 0.6-0.8 mm.

[0047] Optionally, the cavity of the plug 5 in this embodiment is cylindrical or rectangular, used to insert the spring sheet 6 and the steel column 7, and the cavity shape can be set according to the number of spring sheets 6.

[0048] Preferably, the cavity of the plug 5 used in this embodiment is cylindrical, and the number of spring plates 6 is 4.

[0049] Each set of blade-top shrouds has a threaded hole at the bottom of the slot where it connects to the insert, with the threaded hole for inserting the plug body 5. The threaded hole is cylindrical, and the inner wall of the threaded hole is threaded. The plug body 5 is screwed into the threaded hole and threadedly connected to it, so that the connection between each set of slots and inserts is more secure.

[0050] During processing, the threaded hole and the blade tip shroud are integrally formed according to the preset position, which improves the structural integrity.

[0051] When the last stage moving blade flutters, inside the plug body 5, the steel column 7 vibrates along with the last stage moving blade and the top blade shroud. The steel column 7 is suspended in the plug body by the clamping of the spring plate 6. The steel column 7 generates a damping effect on the spring plate 6. At the same time, the damping effect is applied to the top of the last stage moving blade through the blade shroud, thus achieving the effect of anti-flutter.

[0052] Preferably, the plurality of final-stage moving blades includes a first final-stage moving blade 1 and a second final-stage moving blade 2. The plurality of blade tip shrouds include a first blade tip shroud 3 and a second blade tip shroud 4. The first blade tip shroud 3 is fixedly disposed on the top of the first final-stage moving blade 1, and the second blade tip shroud 4 is fixedly disposed on the top of the second final-stage moving blade 2. The first final-stage moving blade 1 and the second final-stage moving blade 2 are connected by the first blade tip shroud 3 and the second blade tip shroud 4.

[0053] The insert of the first blade top band 3 is inserted into the slot of the second blade top band 4 to make the first blade top band 3 and the second blade top band 4 connected. The bottom of the connection between the first blade top band 3 and the second blade top band 4 is provided with a threaded hole facing upward. The plug 5 is screwed into the threaded hole to make the connection between the first blade top band 3 and the second blade top band 4 more stable and enhance the connection strength between the blade top bands.

[0054] A steel column 7 with a diameter of 10mm and a thickness of 10mm is sandwiched between spring plates 6 with a thickness of 0.7mm. After bending and deforming the spring plates 6, it is inserted into the cavity of the plug body 5, so that the steel column 7 is suspended in the plug body 5 under the fixation of the spring plates 6.

[0055] When the first and second stage moving blades 1 and 2 flutter, the steel column 7, under the action of inertia, and the spring plate 6 exert a damping effect on the first and second stage moving blades 1 and 2, which can significantly reduce the amplitude and frequency, increase the dynamic strength of the first and second stage moving blades 1 and 2, and thus ensure the safe and stable operation of the turbine unit during deep peak shaving.

[0056] Deep peak shaving means that the turbine unit can safely and stably operate the low-pressure last-stage moving blades when the unit load rate drops to 30% to 40% of the rated load under conditions of large peak-to-valley difference in grid load.

[0057] This invention provides a flutter-resistant turbine last-stage moving blade assembly. By combining the last-stage moving blade, the blade tip shroud, and the flutter-resistant assembly, the connection between the blade tip shroud and the blade tip shroud becomes more stable. With the flutter-resistant assembly, when the turbine inlet steam flow is reduced, the amplitude and frequency of flutter in the last-stage moving blade are effectively reduced by the damping effect of the spring plate 6 and the steel column 7. This enhances the dynamic strength of the low-pressure last-stage moving blade, ensuring the safe and stable operation of the turbine unit and solving the problem of insufficient strength of the low-pressure last-stage moving blade under low steam flow conditions. The turbine unit can operate safely and stably even when the load factor drops to 30%–40% of the rated load due to large peak-to-valley differences in grid load.

[0058] In the description of this invention, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0059] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A flutter-resistant turbine last-stage moving blade assembly, characterized in that, include: Multiple last-stage moving blades arranged around the turbine rotor, multiple blade tip shrouds, and anti-flutter components; The plurality of blade tip shrouds and the plurality of final stage moving blades are arranged in a one-to-one correspondence, and the blade tip shrouds are arranged on the top of the final stage moving blades. Two adjacent final stage moving blades are connected by the blade tip shrouds above them. One end of the blade tip shroud is provided with a slot, and the other end of the blade tip shroud is provided with an insert that matches the shape of the slot. Two adjacent blade tip shrouds are connected to the insert of the other blade tip shroud through the slot of one blade tip shroud. The anti-flutter assembly includes a plug (5), a pair of spring plates (6), and a steel column (7). The plug (5) is disposed at the insertion point between the slot and the insert; The plug (5) has a cavity inside, the spring sheet (6) is fixed on the inner wall of the cavity, and the steel column (7) is clamped between two opposite spring sheets (6) so that the steel column (7) is suspended inside the plug (5) by the spring sheet (6); The bottom of the slot and insert of each pair of adjacent blade top bands is provided with a threaded hole facing upwards, and the plug (5) is screwed into the threaded hole; The cavity of the plug (5) is cylindrical.

2. The anti-flutter turbine last-stage moving blade assembly according to claim 1, characterized in that, The slot is a rectangular slot, and the insert is a rectangular insert.

3. The anti-flutter turbine last-stage moving blade assembly according to claim 1, characterized in that, The threaded hole is integrally formed with the blade tip shroud.

4. The anti-flutter turbine last-stage moving blade assembly according to claim 1, characterized in that, The blade tip shroud and the final stage moving blade are integrally formed.

5. The anti-flutter turbine last-stage moving blade assembly according to claim 1, characterized in that, The thickness of the blade tip shroud is 18-22 mm.

6. The anti-flutter turbine last-stage moving blade assembly according to claim 1, characterized in that, The steel column (7) has a diameter of 8-12 mm and a height of 8-12 mm; the spring sheet (6) has a thickness of 0.6-0.8 mm.

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