Penultimate-stage 272 mm moving blade of variable-speed steam turbine for driving feed pump

Abstract

The invention discloses a penultimate-stage 272 mm moving blade of a variable-speed steam turbine for driving a feed pump, and belongs to the technical field of steam turbine design. The variable-speed steam turbine blade solves the technical problems that when an existing variable-speed steam turbine blade for driving a feed pump runs in a resonance state, damping is small, and rigidity is insufficient. The rotor blade comprises a tie bar, a blade body, a middle body and a blade root, and the rotor blade is configured to operate when the working rotating speed continuously changes within the range of 3000 rpm to 6000 rpm; each moving blade is sequentially composed of a lacing wire, a blade body, a middle body and a blade root which are integrally formed from top to bottom; after the multiple moving blades are assembled on the rotor wheel disc in a whole circle, the tie bars of the adjacent moving blades are attached to each other under the action of centrifugal force so as to provide additional damping, the tie bars and the blade roots jointly form a damping system so as to adapt to vibration loads generated when a resonance area is crossed within the working rotating speed range, and when the working rotating speed penetrates through the resonance area, the damping system is closed. And the vibration stress value of the moving blade is lower than the allowable stress value. And the damping and rigidity are improved. The method is used for turbine design.

Description

Technical Field

[0002] This invention relates to a 272mm moving blade for the second and last stage of a variable speed steam turbine used to drive a feedwater pump, belonging to the field of steam turbine design technology. Background Technology

[0003] The operating range of variable-speed steam turbines driving feedwater pumps in thermal power plants is 3000 rpm to 6000 rpm. In safety design, avoiding the resonance speed of a turbine operating at a fixed speed within the range of 2820 rpm to 3090 rpm is sufficient to ensure the safe operation of the moving blades. However, for variable-speed steam turbines driving auxiliary equipment such as boiler feedwater pumps, the operating mode is completely different. To meet the load regulation requirements of the unit, their operating speed needs to be continuously adjusted within a range of 3000 rpm to 6000 rpm or even wider. This means that the frequency of the excitation force will become a continuous frequency band as the speed changes, inevitably coinciding with the inherent multi-order vibration frequencies of the blades at multiple speed points, thus triggering resonance. Therefore, the traditional "avoid resonance" design concept fails, and the inevitability of resonance becomes a technical problem that must be directly addressed and solved in the design of such blades.

[0004] Therefore, it is necessary to analyze each resonant speed to ensure that the vibration stress of the moving blade does not exceed the allowable value within the operating speed range. To achieve the goal of keeping the vibration stress of the moving blade under resonant conditions within the allowable value, the moving blade structure needs to be meticulously designed, requiring both increased damping and sufficiently high stiffness. These requirements increase the difficulty of moving blade design.

[0005] In summary, existing variable-speed turbine blades that drive feedwater pumps suffer from low damping and insufficient stiffness during resonant operation. Summary of the Invention

[0006] The present invention aims to solve the technical problems of low damping and insufficient stiffness of existing variable speed steam turbine blades that drive feedwater pumps during resonance operation. It provides a 272mm moving blade for the second and last stage of a variable speed steam turbine that drives feedwater pumps. The blade includes a tie rod, blade body, intermediate body and blade root. The moving blade is configured to operate when the operating speed varies continuously within the range of 3000 rpm to 6000 rpm. The moving blade is composed of an integrally formed tie rod, blade body, intermediate body and blade root from top to bottom. After multiple moving blades are assembled around the rotor disk, the tie rods of adjacent moving blades fit together under the action of centrifugal force to provide additional damping. The tie rod and blade root together form a damping system to adapt to the vibration load when passing through the resonance zone within the operating speed range. When the operating speed passes through the resonance zone, the vibration stress value of the moving blade is lower than the allowable stress value.

[0007] As another improvement of the present invention, the leaf root is a toothed fir-shaped leaf root.

[0008] As another improvement of the invention, the leaf root has three pairs of bearing teeth.

[0009] As another improvement of the present invention, the cross-section of the tie rod is elliptical.

[0010] As another improvement of the present invention, after the moving blades are installed on the rotor, the total number of blades in the entire circle is 84.

[0011] As another improvement of the present invention, the moving blade is installed after the rotor, and the radius R of the upper surface of its intermediate body from the center of the rotor is 487.5 mm.

[0012] As another improvement of the present invention, the height L of the leaf body is 272.00 mm, the width B of the intermediate body is 155.00 mm, the thickness C is 7.30 mm, and the height E of the leaf root is 36.12 mm.

[0013] As another improvement of the present invention, the height H of the center of the tie rod from the upper surface of the intermediate body is 217.60 mm.

[0014] As another improvement of the present invention, the profile of the blade is defined by six sections taken from the upper surface of the intermediate body at 40mm intervals along the blade height direction, and the six sections are H1 to H6 respectively. The axial width of section H1 is 97.00 mm, and the thicknesses at the five equal division points along the chord length are 11.75 mm, 14.65 mm, 13.80 mm, and 10.50 mm, respectively. The installation angle is 73.37°. The axial width of section H2 is 77.95 mm, and the thicknesses at the five equal division points along the chord length are 10.37 mm, 14.01 mm, 13.71 mm, and 10.36 mm, respectively. The installation angle is 64.88°. The axial width of section H3 is 61.61 mm, and the thicknesses at the five equal division points along the chord length are 10.35 mm, 14.42 mm, 13.38 mm, and 9.61 mm, respectively. The installation angle is 54.04°. The axial width of section H4 is 47.84 mm, and the thicknesses at the five equal division points along the chord length are 9.37 mm, 15.16 mm, 13.95 mm, and 8.94 mm, respectively. The installation angle is 42.74°. The axial width of section H5 is 36.79 mm, and the thicknesses at the five equal division points along the chord length are 10.14 mm, 16.07 mm, 13.36 mm, and 7.70 mm, respectively. The installation angle is 32.53°. The axial width of section H6 is 26.55 mm, and the thicknesses at the five equal division points along the chord length are 8.20 mm, 13.48 mm, 12.09 mm, and 7.35 mm, respectively. The installation angle is 23.02°.

[0015] As another improvement of the present invention, multiple 272mm moving blades of the second and last stages of a variable speed steam turbine used to drive a feedwater pump are uniformly assembled along the circumference of the steam turbine rotor.

[0016] The beneficial effects of this invention are: The advantages of the secondary and final stage moving blades applied for in this application are that the blades have high stiffness and low dynamic stress in the operating speed range of 3000rpm~6000rpm, and can operate safely for a long time.

[0017] 1. The leaf base is a 3-tooth oblique fir type, with a large load-bearing surface.

[0018] 2. The blade profile is designed according to the thermodynamic parameter requirements of variable speed, resulting in high efficiency within the variable speed operating range.

[0019] The blades utilize a boss-shaped tie structure. Finite element method analysis and design were applied to ensure close contact between adjacent blades within the operating speed range, resulting in high damping and low vibration stress. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the composition of the 272mm moving blades of the second and last stage of a variable speed steam turbine for driving a feedwater pump, according to the present invention.

[0021] Figure 2 This is a schematic diagram of the flow path of the 272mm moving blades in the second and last stages of a variable-speed steam turbine used to drive a feedwater pump, according to the present invention.

[0022] Figure 3 This is a schematic diagram of the complete circular assembly of the 272mm moving blades of the second and final stages of a variable-speed steam turbine for driving a feedwater pump.

[0023] Figure 4 This is a first three-dimensional schematic diagram of the 272mm moving blade of the second and last stage of a variable speed steam turbine for driving a feedwater pump according to the present invention.

[0024] Figure 5 This is a second three-dimensional schematic diagram of the 272mm moving blade of the second and last stage of a variable speed steam turbine for driving a feedwater pump according to the present invention.

[0025] Figure 6 This is a schematic diagram of the leaf blade's profile dimensions.

[0026] Figure 7 This is a three-dimensional structural schematic diagram of the 272mm moving blade of the second and last stage of a variable speed steam turbine for driving a feedwater pump, according to the present invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Specific implementation method one: Combining Figures 1 to 7 This embodiment describes a 272mm moving blade for the second and last stage of a variable-speed steam turbine used to drive a feedwater pump. The blade is characterized by comprising a tie rod, blade body, intermediate body, and blade root. The moving blade is configured to operate when the operating speed continuously varies within the range of 3000 rpm to 6000 rpm. The moving blade is composed of an integrally formed tie rod, blade body, intermediate body and blade root from top to bottom. After multiple moving blades are assembled around the rotor disk, the tie rods of adjacent moving blades fit together under the action of centrifugal force to provide additional damping. The tie rod and blade root together form a damping system to adapt to the vibration load when passing through the resonance zone within the operating speed range. When the operating speed passes through the resonance zone, the vibration stress value of the moving blade is lower than the allowable stress value.

[0029] The advantages of the secondary and final stage moving blades proposed in this application are that the blades exhibit low dynamic stress within the operating speed range of 3000rpm to 6000rpm, ensuring long-term operational safety. This guarantees the safety of variable-speed steam turbines within their operating speed range.

[0030] Specific Implementation Method Two: Combining Figures 1 to 7 This embodiment differs from specific embodiment one in that the leaf root is a toothed fir-shaped leaf root. This design provides a larger load-bearing surface. Other components and connection methods are the same as in specific embodiment one.

[0031] Specific implementation method three: Combining Figures 1 to 7 This embodiment differs from specific embodiment one in that the leaf root has three pairs of bearing teeth. Other components and connection methods are the same as in specific embodiment one or two.

[0032] Specific implementation method four: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment 1 in that the cross-section of the tie rod is elliptical. Other components and connection methods are the same as any one of Specific Embodiments 1 to 3.

[0033] Specific Implementation Method Five: Combining Figures 1 to 7This embodiment differs from specific embodiment one in that the moving blades are installed on the rotor, and the total number of blades in the entire ring is 84. Other components and connection methods are the same as any one of specific embodiments one through four.

[0034] Specific Implementation Method Six: Combination Figures 1 to 7 This embodiment differs from specific embodiment one in that the moving blade, after being installed on the rotor, has a radius R of 487.5 mm from the upper surface of its intermediate body to the rotor center. Other components and connection methods are the same as any one of specific embodiments one through five.

[0035] Specific implementation method seven: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment 1 in that the height L of the leaf body is 272.00 mm, the width B of the intermediate body is 155.00 mm, and the thickness C is 7.30 mm; the height E of the leaf root is 36.12 mm. Other components and connection methods are the same as in any one of Specific Embodiments 1 to 6.

[0036] Specific implementation method eight: Combination Figures 1 to 7 This embodiment differs from Specific Embodiment 1 in that the height H of the center of the tie rod from the upper surface of the intermediate body is 217.60 mm. Other components and connection methods are the same as any one of Specific Embodiments 1 to 7.

[0037] Specific Implementation Method Nine: Combining Figures 1 to 7 This embodiment differs from specific embodiment one in that the blade profile is defined by six sections, H1 to H6, taken at 40mm intervals from the upper surface of the intermediate body along the blade height direction; the dimensional data are shown in the table below. Data Description: Starting from the upper surface of the intermediate body, a cross-section is taken every 40mm, named H1 to H6 respectively. (See attached image) Figure 6 The center line indicates the outlet and inlet sides of the blade. The axial (parallel to the rotor center) width of each section is denoted as P. Each section is divided into 5 equal parts, and 4 thickness values ​​are taken along the rotation direction, denoted as S1 to S4 respectively. The angle between the chord length direction of each section and the blade rotation direction is denoted as K.

[0038] The axial width of section H1 is 97.00 mm, and the thicknesses at the five equal division points along the chord length are 11.75 mm, 14.65 mm, 13.80 mm, and 10.50 mm, respectively. The installation angle is 73.37°. The axial width of section H2 is 77.95 mm, and the thicknesses at the five equal division points along the chord length are 10.37 mm, 14.01 mm, 13.71 mm, and 10.36 mm, respectively. The installation angle is 64.88°. The axial width of section H3 is 61.61 mm, and the thicknesses at the five equal division points along the chord length are 10.35 mm, 14.42 mm, 13.38 mm, and 9.61 mm, respectively. The installation angle is 54.04°. The axial width of section H4 is 47.84 mm, and the thicknesses at the five equal division points along the chord length are 9.37 mm, 15.16 mm, 13.95 mm, and 8.94 mm, respectively. The installation angle is 42.74°. The axial width of section H5 is 36.79 mm, and the thicknesses at the five equal division points along the chord length are 10.14 mm, 16.07 mm, 13.36 mm, and 7.70 mm, respectively. The installation angle is 32.53°. The axial width of section H6 is 26.55 mm, and the thicknesses at the five equal division points along the chord direction are 8.20 mm, 13.48 mm, 12.09 mm, and 7.35 mm, respectively. The installation angle is 23.02°. Other components and connection methods are the same as any one of specific embodiments one to eight.

[0039] Specific Implementation Method Ten: Combining Figures 1 to 7 This implementation method is described in conjunction with Figures 1 to 7 This embodiment differs from Specific Embodiment 1 in that multiple 272mm moving blades of the second and last stages of the variable-speed turbine used to drive the feedwater pump are uniformly assembled along the circumference of the turbine rotor. The blades are assembled around the rotor in a complete circle, totaling 84 blades. The radius R of the upper surface of the blade's intermediate body from the rotor center is 487.5mm. The overall structural data of the blade are as follows: blade height L = 272.00mm, angle A between the blade tip and the axial direction = 22°, intermediate body thickness C = 7.30mm, blade root height E = 36.12mm, blade intermediate body width B = 155.00mm, and height H of the boss tie rod center from the upper surface of the intermediate body = 217.60mm.

[0040] In this embodiment, the blades exhibit low dynamic stress within the operating speed range of 3000rpm~6000rpm, ensuring safe long-term operation.

[0041] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A 272mm moving blade for the second and last stage of a variable-speed steam turbine for driving a feedwater pump, characterized in that... It includes a tie rod, blade body, intermediate body and blade root, and the moving blade is configured to operate continuously within the range of 3000 rpm to 6000 rpm; The moving blade is composed of an integrally formed tie rod, blade body, intermediate body and blade root from top to bottom. After multiple moving blades are assembled around the rotor disk, the tie rods of adjacent moving blades fit together under the action of centrifugal force to provide additional damping. The tie rod and blade root together form a damping system to adapt to the vibration load when passing through the resonance zone within the operating speed range. When the operating speed passes through the resonance zone, the vibration stress value of the moving blade is lower than the allowable stress value.

2. The second and last stage 272mm moving blades of a variable speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The leaf roots are of the serrated fir type.

3. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The leaf root has three pairs of bearing teeth.

4. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The cross-section of the tie rod is elliptical.

5. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, After the moving blades are installed on the rotor, the total number of blades in the entire circle is 84.

6. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The moving blade is installed after the rotor, and the radius R of the upper surface of its intermediate body from the center of the rotor is 487.5 mm.

7. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The height L of the leaf body is 272.00 mm, the width B of the intermediate body is 155.00 mm, and the thickness C is 7.30 mm; the height E of the leaf root is 36.12 mm.

8. The second and last stage 272mm moving blades of a variable speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The height H of the center of the tie rod from the upper surface of the intermediate body is 217.60 mm.

9. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, The blade profile is defined by six sections taken from the upper surface of the intermediate body at 40mm intervals along the blade height direction, with the six sections being H1 to H6 respectively. The axial width of section H1 is 97.00 mm, and the thicknesses at the five equal division points along the chord length are 11.75 mm, 14.65 mm, 13.80 mm, and 10.50 mm, respectively. The installation angle is 73.37°. The axial width of section H2 is 77.95 mm, and the thicknesses at the five equal division points along the chord length are 10.37 mm, 14.01 mm, 13.71 mm, and 10.36 mm, respectively. The installation angle is 64.88°. The axial width of section H3 is 61.61 mm, and the thicknesses at the five equal division points along the chord length are 10.35 mm, 14.42 mm, 13.38 mm, and 9.61 mm, respectively. The installation angle is 54.04°. The axial width of section H4 is 47.84 mm, and the thicknesses at the five equal division points along the chord length are 9.37 mm, 15.16 mm, 13.95 mm, and 8.94 mm, respectively. The installation angle is 42.74°. The axial width of section H5 is 36.79 mm, and the thicknesses at the five equal division points along the chord length are 10.14 mm, 16.07 mm, 13.36 mm, and 7.70 mm, respectively. The installation angle is 32.53°. The axial width of section H6 is 26.55 mm, and the thicknesses at the five equal division points along the chord length are 8.20 mm, 13.48 mm, 12.09 mm, and 7.35 mm, respectively. The installation angle is 23.02°.

10. The second and last stage 272mm moving blades of a variable-speed steam turbine for driving a feedwater pump according to claim 1, characterized in that, Multiple 272mm moving blades of the second and last stages of the variable speed steam turbine used to drive the feedwater pump are uniformly assembled along the circumference of the steam turbine rotor.

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