Steam compensation structure for reducing steam turbine low-pressure stage air flow excitation force during deep peak shaving

Abstract

The present invention belongs to the technical field of steam turbine equipment and relates to a steam compensation structure for reducing the gas flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving, comprising: a plurality of steam guide rods, each of which is hollow inside and has an open structure at one end, each steam guide rod is connected to the cylinder of the steam turbine through a fixing member, the closed end of each steam guide rod is close to the blade roots of the stationary blades and the moving blades, and a plurality of jet holes are provided at a position on the side of each steam guide rod close to its closed end; an external steam source for providing external steam to the plurality of steam guide rods. The present invention can utilize the pressure difference inside and outside the steam turbine to suck the external steam into the blade roots of the stationary blades and the moving blades, forming a positive gas flow, changing the steam flow rate, velocity distribution and pressure in the flow passage area of the low-pressure stage of the steam turbine, making the steam flow more uniform, reducing the generation of eddy currents, suppressing the blowing, and preventing the steam from flowing back, thereby significantly reducing the gas flow excitation caused by eddy currents, blowing, steam backflow, etc. under low-flow operation.

Description

Technical Field

[0001] The invention belongs to the technical field of steam turbine equipment and relates to a steam compensation structure for reducing the air flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving. Background Art

[0002] Under the operating condition of deep peak shaving of a steam turbine unit, the steam inlet of the low-pressure stage (pressure less than 0.8 MPa) of the steam turbine is very small, and the low-pressure stage is always in the operating condition of small flow rate (15% - 30% of the rated flow rate of the steam turbine). Its flow condition becomes extremely complex, and phenomena such as eddy current, outlet backflow, and back suction will occur. The moving and stationary blades in the flow passage area of the low-pressure stage of the steam turbine also enter the blowing state. The blowing state causes the blade temperature to rise. The complex flow condition leads to a very poor operating state in the flow passage area of the low-pressure stage of the steam turbine. Eddy current and backflow cause the moving and stationary blades to be affected by complex air flow excitation forces, seriously threatening the vibration safety of the moving and stationary blades, and further affecting the safe and stable operation of the entire unit. At the same time, the eddy current, blowing, and steam backflow phenomena in the low-pressure stage of the steam turbine under small flow rate conditions mainly occur at the blade root positions close to the moving and stationary blades, and develop upstream towards the blade row and the blade tip as the flow rate decreases.

[0003] At present, there is no good solution for the eddy current, blowing, and steam backflow phenomena in the low-pressure stage of the steam turbine under small flow rate conditions. Therefore, it is necessary to design a steam compensation structure. When the low-pressure stage of the steam turbine operates under small flow rate conditions, it can reduce the eddy current, blowing, and steam backflow phenomena in the flow passage, reduce the air flow excitation force received by the moving and stationary blades in the flow passage area of the low-pressure stage of the steam turbine, and improve the vibration safety of the moving and stationary blades. Summary of the Invention

[0004] The purpose of the invention is to provide a steam compensation structure for reducing the air flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving, which can reduce the eddy current, blowing, and steam backflow phenomena and reduce the air flow excitation force received by the moving and stationary blades in the flow passage area of the low-pressure stage of the steam turbine by increasing steam compensation.

[0005] To achieve the above purpose, the technical solution provided by the invention is as follows:

[0006] A steam compensation structure for reducing the air flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving, comprising:

[0007] Multiple steam guide rods are arranged inside the cylinder of the steam turbine and are located between the stationary blades and the moving blades in the flow passage area of the low-pressure stage of the steam turbine. The multiple steam guide rods are evenly arranged circumferentially around the cylinder of the steam turbine. The inside of each steam guide rod is hollow and one end is an open structure. The open end of each steam guide rod passes through the inner wall of the cylinder of the steam turbine and is located outside the cylinder of the steam turbine. Each steam guide rod is connected to the cylinder of the steam turbine through a fixing member. The closed end of each steam guide rod is close to the roots of the stationary blades and the moving blades. Multiple jet holes are formed in the side of each steam guide rod near its closed end, and the multiple jet holes are arranged along the length direction of the steam guide rod.

[0008] An external steam source is arranged outside the cylinder of the steam turbine and is connected to the open ends of the multiple steam guide rods for providing external steam to the multiple steam guide rods.

[0009] The features of the present invention further include:

[0010] Wherein the fixing member includes:

[0011] A base is arranged outside the cylinder of the steam turbine and is close to the corresponding steam guide rod. The base is of a U-shaped structure. The bottom of the base is fixedly connected to the cylinder of the steam turbine, and the steam guide rod passes through the bottom of the base and is located inside the base.

[0012] A fixing block and a slider are arranged inside the base and are located on both sides of the steam guide rod. The fixing block is fixedly connected to the base, and the slider is slidably connected to the base.

[0013] A fixing bolt is arranged on the side of the base. One end of the fixing bolt passes through the side of the base and is rotatably connected to the slider. The fixing bolt is threadedly connected to the base.

[0014] Wherein grooves matching the shape of the steam guide rod are respectively formed in the opposite surfaces of the fixing block and the slider close to the steam guide rod.

[0015] Wherein a scale is arranged on the side of each steam guide rod close to the open end.

[0016] Wherein the number of the steam guide rods is 1 / 5 to 1 / 2 of the number of the stationary blades.

[0017] Wherein the cross section of each steam guide rod is one of a circle, an ellipse and a streamline shape.

[0018] Wherein the wall thickness of each steam guide rod is the same from the open end to the closed end or the wall thickness gradually increases from the open end to the closed end.

[0019] Wherein the positions of the multiple jet holes on each steam guide rod are located at 1 / 6 to 1 / 3 of the height of the stationary blade.

[0020] The steam compensation structure for reducing the aerodynamic excitation force of the low-pressure stage of the steam turbine during deep peak shaving of the present invention has the following advantages:

[0021] Through the cooperation of multiple steam guide rods and their corresponding multiple jet holes, utilizing the pressure difference inside and outside the steam turbine, external steam is inhaled into the roots of the stationary blades and moving blades, forming a positive steam flow, compensating for the steam in the flow path area of the low-pressure stage of the steam turbine, changing the steam flow rate, velocity distribution and pressure in the flow path area of the low-pressure stage of the steam turbine, making the steam flow more uniform, reducing the generation of eddy currents, suppressing the blowing effect, preventing steam backflow, thereby significantly reducing the airflow excitation caused by eddy currents, blowing effect, steam backflow, etc. under low-flow operation, and improving the vibration safety of the stationary and moving blades in the flow path area of the low-pressure stage of the steam turbine. Brief Description of the Drawings

[0022] Figure 1 It is a front view structural schematic diagram of the present invention.

[0023] Figure 2 It is a side view structural schematic diagram of the present invention.

[0024] Figure 3 It is an overall structural schematic diagram of the steam guide rod in the present invention.

[0025] Figure 4 It is an overall structural schematic diagram of the fixing part in the present invention.

[0026] Figure 5 It is a structural schematic diagram of the steam guide rod with a circular cross-section at a in the present invention, a structural schematic diagram of the steam guide rod with an elliptical cross-section at b, and a structural schematic diagram of the steam guide rod with a streamlined cross-section at c.

[0027] Figure 6 It is a structural schematic diagram of the steam guide rod with the same wall thickness from the open end to the closed end at a in the present invention, and a structural schematic diagram of the steam guide rod with the wall thickness gradually increasing from the open end to the closed end at b.

[0028] Figure 7 It is a structural schematic diagram of a square jet hole at a in the present invention, a structural schematic diagram of a circular jet hole at b, a structural schematic diagram of an elliptical jet hole at c, a structural schematic diagram of the jet hole gradually increasing in size at d, and a structural schematic diagram of the jet hole gradually decreasing in size at e.

[0029] Figure 8 It is a schematic diagram of eddy currents in the existing steam turbine under the deep peak shaving condition.

[0030] Figure 9 It is a schematic diagram of eddy currents in the present invention under the deep peak shaving condition.

[0031] Figure 10 It is the dimensionless exciting force generated by the existing steam turbine.

[0032] Figure 11 It is the dimensionless exciting force generated after adding the steam guide rod in the present invention.

[0033] Reference Signs:

[0034] 1. Static blade, 2. Moving blade, 3. Steam guide rod, 4. Jet hole, 5. Base, 6. Fixed block, 7. Slide block, 8. Fixed bolt, 9. Scale. Specific implementation manner

[0035] The technical solutions in the present invention will be clearly and elaborately described below in conjunction with the accompanying drawings. Among them, in the description of the embodiments of the present invention, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "a plurality of" means two or more than two. The following terms "first" and "second" are only used for descriptive purposes and cannot be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0036] Such as Figure 1 、 Figure 2 、 Figure 3As shown in the figure, the present invention provides a steam compensation structure for reducing the gas flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving, which includes a plurality of steam guide rods 3 and an external steam source. The plurality of steam guide rods 3 are arranged in the cylinder of the steam turbine. The plurality of steam guide rods 3 are located between the stationary blades 1 and the moving blades 2 in the flow passage area of the low-pressure stage of the steam turbine. The stationary and moving blades are the stationary blades 1 and the moving blades 2. The plurality of steam guide rods 3 are evenly arranged circumferentially around the cylinder of the steam turbine. The inside of each steam guide rod 3 is hollow and one end is an open structure. The open end of each steam guide rod 3 passes through the inner wall of the cylinder of the steam turbine and is located outside the cylinder of the steam turbine. Each steam guide rod 3 is connected to the cylinder of the steam turbine through a fixing member. The closed end of each steam guide rod 3 is close to the blade roots of the stationary blade 1 and the moving blade 2. A plurality of jet holes 4 are provided on the side of each steam guide rod 3 near its closed end. The plurality of jet holes 4 are arranged along the length direction of the steam guide rod 3. The external steam source is arranged outside the cylinder of the steam turbine. The external steam source is connected to the open ends of the plurality of steam guide rods 3. The external steam source is used to provide external steam for the plurality of steam guide rods 3. When the low-pressure stage of the steam turbine is operating under a small flow rate condition, that is, when the flow rate of the low-pressure stage is operating under a small flow rate condition of 15% to 30% of the rated flow rate, the external steam is sucked into the inside of the steam guide rod 3 and injected into the blade roots of the stationary blade 1 and the moving blade 2 through the plurality of jet holes 4, so as to reduce the eddy current, blowing and backflow caused by the small flow rate operation, thereby reducing the gas flow excitation force. Through the cooperation of the plurality of steam guide rods 3 and the corresponding plurality of jet holes 4, the present invention utilizes the pressure difference inside and outside the steam turbine to suck the external steam into the blade roots of the stationary blade 1 and the moving blade 2, forming a positive steam flow, compensating the steam in the flow passage area of the low-pressure stage of the steam turbine, changing the steam flow rate, velocity distribution and pressure in the flow passage area of the low-pressure stage of the steam turbine, making the steam flow more uniform, reducing the generation of eddy current, suppressing blowing, and preventing steam backflow, thereby significantly reducing the gas flow excitation caused by eddy current, blowing, steam backflow, etc. under the small flow rate operation, and improving the vibration safety of the stationary and moving blades in the flow passage area of the low-pressure stage of the steam turbine.

[0037] As Figure 4As shown in the figure, the fixing member includes a base 5, a fixing block 6, a slider 7 and a fixing bolt 8. The base 5 is arranged outside the cylinder of the steam turbine. The position of the base 5 is close to the corresponding steam guide rod 3. The base 5 is of a U-shaped structure. The bottom of the base 5 is fixedly connected to the cylinder of the steam turbine. The steam guide rod 3 passes through the bottom of the base 5 and is located inside the base 5. The fixing block 6 and the slider 7 are arranged inside the base 5. The fixing block 6 and the slider 7 are located on both sides of the steam guide rod 3. The fixing block 6 is fixedly connected to the base 5. The slider 7 is slidably connected to the base 5, facilitating the sliding of the slider 7 inside the base 5. The fixing bolt 8 is arranged on the side of the base 5. The position of the fixing bolt 8 is close to the slider 7 and is located on the side of the slider 7 away from the fixing block 6. One end of the fixing bolt 8 passes through the side of the base 5 and is rotatably connected to the slider 7. The fixing bolt 8 is threadedly connected to the base 5. By rotating the fixing bolt 8, the slider 7 is driven to move towards the fixing block 6 inside the base 5, adjusting the distance between the slider 7 and the fixing block 6, facilitating the clamping and fixing of the steam guide rod 3.

[0038] As Figure 4 shown in the figure, grooves matching the shape of the steam guide rod 3 are respectively formed at positions close to the steam guide rod 3 on the opposite surfaces of the fixing block 6 and the slider 7. Through the two grooves, it is convenient to cooperate with the steam guide rod 3, making the clamping of the steam guide rod 3 more stable.

[0039] As Figure 3 shown in the figure, a scale 9 is arranged at a position close to the open end on the side of each steam guide rod 3. Through the fixing member, the radial position of each steam guide rod 3 extending into the cylinder of the steam turbine can be accurately controlled, and it can be observed through the scale 9 to adjust the position of the jet hole 4 relative to the stationary blade 1, thereby precisely adjusting the position where the steam is injected, further reducing the gas flow excitation force.

[0040] As Figure 2 shown in the figure, the number of steam guide rods 3 is 1 / 5 - 1 / 2 of the number of stationary blades 1, which can be designed according to the actual operating power parameters of the unit and the steam compensation flow parameters. The more the required compensation steam flow, the more the number of arranged steam guide rods 3. The evenly arranged steam guide rods 3 can also reduce the risk of low-frequency gas flow excitation occurring between the stationary and moving blades.

[0041] As Figure 5 shown in the figure, the cross-section of each steam guide rod 3 is one of a circle, an ellipse and a streamline shape. It is necessary to ensure that the gap between the stationary blade 1 and the moving blade 2 is greater than twice the cross-section width dimension of the steam guide rod 3. When the gap between the stationary blade 1 and the moving blade 2 is small, a cylindrical or elliptical cross-section is adopted to reduce the occupied space of the steam guide rod 3. When the gap between the stationary blade 1 and the moving blade 2 is large, a streamline cross-section is adopted to reduce the wake vortex caused by the steam disturbing the steam guide rod 3, reduce the flow loss, reduce the adverse impact on the mainstream flow field, and further reduce the gas flow excitation force.

[0042] As Figure 6As shown, the wall thickness of each steam guide rod 3 is the same from the open end to the closed end or gradually increases from the open end to the closed end, that is, the wall thickness of the steam guide rod 3 is non-uniform. Since the steam guide rod 3 is in the flow field and is impacted by the mainstream, the steam guide rod 3 is also subject to a relatively high steam flow force. When the steam velocity in the steam turbine flow path is relatively fast, the force exerted by the steam on the steam guide rod 3 is large. A non-uniform wall thickness can be adopted to ensure the structural strength of the steam guide rod itself when it is impacted by the flow field and minimize the impact on the flow field, improving safety. When the steam velocity in the steam turbine flow path is relatively low, the steam flow force on the steam guide rod is small, and a uniform wall thickness can be adopted to ensure the stability of the compensation steam flow inside the steam guide rod, thereby ensuring the normal use of multiple steam guide rods 3 and further reducing the steam flow excitation.

[0043] Among them, the positions of multiple jet holes 4 on each steam guide rod 3 are located at 1 / 6 to 1 / 3 of the height of the stationary blade 1. The position of the compensation steam jet is adjusted according to the eddy current position generated under different actual operating conditions, so that the steam jet directly impacts the central area of the eddy current, which can meet the requirements of different small-flow operating conditions and improve the effect of the compensation steam in reducing the steam flow excitation.

[0044] As Figure 7 shown, each jet hole 4 is one of a square, a circle, and an ellipse. The sizes of multiple jet holes 4 on each steam guide rod 3 are the same or gradually change along the length direction of the steam guide rod 3. Figure 7 In Figure 7 where d is the jet hole 4 whose size gradually increases along the steam guide rod from its open end to the closed end, and e is the jet hole 4 whose size gradually decreases along the direction of the steam guide rod 3 from its open end to the closed end. Different forms are used to meet the uniform or non-uniform distribution of the compensation steam flow in different jet holes. According to the actual eddy current position generated, the aperture of the jet hole 4 can be increased at the position where there are more eddy currents.

[0045] At the same time, the arrangement of the jet holes 4 includes but is not limited to single-row, double-row, multi-row arrangements, etc. The single-row arrangement of the jet holes can ensure that the steam jet can accurately impact the eddy current area, and the double-row or multi-row jet holes can make the steam jet more evenly distributed in the tangential direction. The positions of the jet holes 4 include but are not limited to symmetric distribution on both sides of the guide rod, asymmetric distribution on both sides of the guide rod, and downstream distribution along the flow direction of the guide rod.

[0046] As Figure 8 、 Figure 9 shown, it can be clearly seen that a large range of eddy currents will be generated under the existing deep peak shaving conditions of the steam turbine. After adding multiple steam guide rods 3 in the present invention, the eddy currents are significantly reduced. At the same time, as Figure 10 、 Figure 11 shown, it can be clearly seen that Figure 9The dimensionless exciting force therein is significantly reduced. Therefore, compared with the existing steam turbine structure, the present invention can significantly reduce the gas flow excitation caused by eddy current, drum wind, steam reflux, etc. under low-flow operation, and improve the vibration safety of the moving and static blades in the flow passage area of the low-pressure stage of the steam turbine.

[0047] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that various changes or equivalent replacements can be made to these features and embodiments without departing from the spirit and scope of the present invention. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention belong to the scope protected by the present invention.

Claims

1. A steam compensation structure for reducing the steam excitation force of the low-pressure stage of a steam turbine during deep peak shaving, characterized in that Including: A plurality of steam guide rods (3) are arranged in the cylinder of the steam turbine and are located between the stationary blades (1) and the moving blades (2) in the low-pressure stage flow passage area of the steam turbine. The plurality of steam guide rods (3) are uniformly arranged circumferentially around the cylinder of the steam turbine. The inside of each steam guide rod (3) is hollow, with one end open and the other end closed. The open end of each steam guide rod (3) passes through the inner wall of the cylinder of the steam turbine and is located outside the cylinder of the steam turbine. Each steam guide rod (3) is connected to the cylinder of the steam turbine through a fixing member. The closed end of each steam guide rod (3) is close to the blade roots of the stationary blade (1) and the moving blade (2). A plurality of jet holes (4) are provided at a position on the side of each steam guide rod (3) close to its closed end. The plurality of jet holes (4) are arranged along the length direction of the steam guide rod (3); An external steam source is arranged outside the cylinder of the steam turbine and is connected to the open ends of the plurality of steam guide rods (3) for providing external steam to the plurality of steam guide rods (3); The fixing member includes: A base (5) is arranged outside the cylinder of the steam turbine and is close to the corresponding steam guide rod (3). The base (5) is of a U-shaped structure. The bottom of the base (5) is fixedly connected to the cylinder of the steam turbine. The steam guide rod (3) passes through the bottom of the base (5) and is located inside the base (5); A fixing block (6) and a slider (7) are arranged inside the base (5) and are located on both sides of the steam guide rod (3). The fixing block (6) is fixedly connected to the base (5), and the slider (7) is slidably connected to the base (5); A fixing bolt (8) is arranged on the side of the base (5). One end of the fixing bolt (8) passes through the side of the base (5) and is rotatably connected to the slider (7). The fixing bolt (8) is threadedly connected to the base (5); Grooves matching the shape of the steam guide rod (3) are respectively provided at positions on the opposite surfaces of the fixing block (6) and the slider (7) close to the steam guide rod (3).

2. The steam compensation structure for reducing the steam flow excitation force of the low-pressure stage of the steam turbine during deep peak shaving according to claim 1, wherein A scale (9) is provided at a position on the side of each steam guide rod (3) close to the open end.

3. The steam compensation structure for reducing the steam flow excitation force of the low-pressure stage of the steam turbine during deep peak shaving according to claim 1, characterized in that, The number of the steam guide rods (3) is 1 / 5 to 1 / 2 of the number of the stationary blades (1).

4. The steam compensation structure for reducing the steam flow excitation force of the low-pressure stage of a steam turbine during deep peak shaving according to claim 1, characterized in that, The cross-section of each steam guide rod (3) is one of a circle, an ellipse, and a streamline shape.

5. The steam compensation structure for reducing the steam flow excitation force of the low-pressure stage of the steam turbine during deep peak shaving according to claim 1, characterized in that The wall thickness of each steam guide rod (3) is the same from the open end to the closed end or gradually increases from the open end to the closed end.

6. The steam compensation structure for reducing the steam flow excitation force of the low-pressure stage of the steam turbine during deep peak shaving according to claim 1, characterized in that, The positions of the plurality of jet holes (4) on each steam guide rod (3) are located at 1 / 6 to 1 / 3 of the height of the stationary blade (1).

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