Turbine rotor and steam turbine and steam-driven feed water pump set using same

Abstract

The utility model discloses a steam turbine rotor and apply its steam turbine, steam feed water pump group, steam turbine rotor is applied to steam turbine, and steam turbine rotor includes spindle, air inlet side coupling, exhaust side coupling and a plurality of blades, air inlet side coupling and exhaust side coupling are arranged respectively in both ends of spindle and all with steam turbine is connected, a plurality of blades interval setting in the middle part of spindle, and the outer surface of at least two blade roots is provided with a plurality of outer convex sections and inner retraction section, the outer convex section with the inner retraction section is connected alternately, and at least one inner retraction section is arranged between every two outer convex sections to form the clearance for giving room. The utility model discloses by setting up the outer convex section and the inner retraction section alternately connected on the outer surface of blade root, like this, the clearance for giving room can be constituted on the outer surface of blade root to reduce the local stress concentration of blade root and inhibit the occurrence of SCC.

Description

Technical Field

[0001] This utility model relates to the field of nuclear power technology, and in particular to a steam turbine rotor and a steam turbine and steam-driven feedwater pump set using the same rotor. Background Technology

[0002] During the refurbishment inspection of old turbine rotors in nuclear power plants, equipment manufacturers discovered multiple stress corrosion cracks (SCC) in the rotor grooves. Currently, the rotor's commonly used blade root-to-rotor groove fit lacks a clearance design to release local stress. This leads to stress concentration on the outer surface of the blade root under long-term variable-speed impulse operation, causing SCC cracks to intensify and making it difficult to fully guarantee the rotor's safety and service life. Utility Model Content

[0003] The purpose of this utility model is to provide a steam turbine rotor and a steam turbine and steam-driven feedwater pump set using the same rotor, aiming to solve the technical problem in the prior art that stress concentration easily forms on the outer surface of the blade root of the steam turbine rotor under long-term variable speed impulse operation, which leads to the aggravation of SCC cracks.

[0004] To solve the above-mentioned technical problems, the purpose of this utility model is achieved through the following technical solution: A steam turbine rotor is provided, which is applied to a steam turbine. The steam turbine rotor includes a main shaft, an inlet-side coupling, an exhaust-side coupling, and multiple blades. The inlet-side coupling and the exhaust-side coupling are respectively disposed at both ends of the main shaft and are both connected to the steam turbine. The multiple blades are spaced apart in the middle of the main shaft. At least two blades have multiple outwardly convex sections and inwardly concave sections on the outer surface of their blade roots. The outwardly convex sections and the inwardly concave sections are alternately connected, and at least one inwardly concave section is provided between every two outwardly convex sections to form a clearance gap.

[0005] Furthermore, the main shaft and multiple blades are all made of alloy structural steel.

[0006] Furthermore, at least three of the leaf roots are fir-type leaf roots.

[0007] Furthermore, the outer surface of the fir-shaped leaf roots is covered with a surrounding band that has its own crown.

[0008] Furthermore, the blades are provided with at least seven, which are arranged sequentially from the intake-side coupling to the exhaust-side coupling as first-stage blades, second-stage blades, third-stage blades, fourth-stage blades, fifth-stage blades, sixth-stage blades, and seventh-stage blades. The blade roots of the second-stage blades, third-stage blades, and fourth-stage blades are fir-shaped blade roots, and the blade roots of the fifth-stage blades and sixth-stage blades are provided with the clearance gap.

[0009] Furthermore, the cross-sections of the plurality of blades are mirror-symmetrical along the axis of the main shaft.

[0010] Furthermore, the turbine rotor also includes a locking component, which is spot-welded to the intake-side coupling.

[0011] This utility model embodiment also provides a steam turbine, including the steam turbine rotor as described above.

[0012] Furthermore, the steam turbine is an impulse steam turbine.

[0013] This utility model embodiment also provides a steam-driven feedwater pump set, including a steam turbine, a reduction gearbox, a booster pump and a pressure stage pump as described above. The pressure stage pump is connected to the steam turbine, and the booster pump is connected to the steam turbine through the reduction gearbox.

[0014] This invention provides a steam turbine rotor for use in a steam turbine. The steam turbine rotor includes a main shaft, an inlet-side coupling, an exhaust-side coupling, and multiple blades. The inlet-side coupling and the exhaust-side coupling are respectively located at both ends of the main shaft and are both connected to the steam turbine. The multiple blades are spaced apart in the middle of the main shaft. At least two blades have multiple outwardly convex sections and inwardly concave sections on the outer surface of their blade roots. The outwardly convex sections and inwardly concave sections are alternately connected, and at least one inwardly concave section is provided between every two outwardly convex sections to form a clearance. This invention, by providing alternating outwardly convex sections and inwardly concave sections on the outer surface of the blade roots, creates a clearance on the outer surface of the blade roots, thereby reducing local stress concentration at the blade roots and suppressing the occurrence of stress concentration cracking (SCC). Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the structure of a steam turbine rotor provided for an embodiment of this utility model; Figure 2 for Figure 1 Enlarged view of section A; Figure 3 for Figure 1 Enlarged view of section B; Figure 4 A schematic block diagram of a steam-driven feedwater pump set provided for an embodiment of this utility model.

[0017] Explanation of the markings in the image: 10. Spindle; 20. Intake-side coupling; 30. Exhaust-side coupling; 40. Leaf; 41. Outwardly convex section; 42. Inwardly contracted section; 43. Fir-type leaf root; 44. Encircling band. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present utility model.

[0019] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0020] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0021] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0022] Combination Figure 1 and Figure 2 As shown, this utility model embodiment provides a steam turbine rotor, which is applied to a steam turbine. The steam turbine rotor includes a main shaft 10, an intake-side coupling 20, an exhaust-side coupling 30, and multiple blades 40. The intake-side coupling 20 and the exhaust-side coupling 30 are respectively disposed at both ends of the main shaft 10 and are both connected to the steam turbine. Multiple blades 40 are spaced apart in the middle of the main shaft 10. At least two blades 40 have multiple outwardly protruding sections 41 and inwardly concave sections 42 on the outer surface of their blade roots. The outwardly protruding sections 41 and inwardly concave sections 42 are alternately connected, and at least one inwardly concave section 42 is provided between every two outwardly protruding sections 41 to form a clearance gap.

[0023] In this embodiment, the intake-side coupling 20 and the exhaust-side coupling 30 are respectively installed at both ends of the main shaft 10 for connection with external transmission components. Multiple blades 40 are installed in corresponding wheel grooves in the middle of the main shaft 10. Each blade 40 is distributed circumferentially at a preset angle and maintains an axial clearance with adjacent blades 40. The outer surface of the blade root of at least two blades 40 is machined into an alternating structure consisting of multiple outwardly convex sections 41 and inwardly concave sections 42 connected end-to-end. The outwardly convex sections 41 bulge outwards radially, serving as a support platform for contacting or positioning with the wheel groove sidewall; the inwardly concave sections 42 retract inwards radially, serving as a neck transition between adjacent outwardly convex sections 41. At least one inwardly concave section 42 is provided between two adjacent outwardly convex sections 41; a rounded corner transition is used between each outwardly convex section 41 and inwardly concave section 42, with the rounded corner radius determined comprehensively based on strength, machining, and assembly to avoid sharp corners. Through the continuous outwardly convex and inwardly concave contours, a clearance corresponding to the wheel groove is formed on the outer surface of the blade root. Of course, the number and distribution of the convex segments 41 of the alternating structure can be matched and set according to the geometric parameters of the grooves of different grades.

[0024] In one embodiment, the main shaft 10 and the plurality of blades 40 are both made of alloy structural steel.

[0025] In this embodiment, considering the long-term variable-speed impulse operation of the steam turbine and the requirements for SCC (stress corrosion cracking) risk control, the main shaft 10 is preferably made of 30Cr2Ni4MoV forgings, and the blades 40 are preferably made of alloy structural steel compatible with the main shaft 10, with the yield strength uniformly controlled below 900 MPa. According to SCC theoretical research and EPRI conclusions, materials with yield strengths above 900 MPa fall within the SCC sensitive range, while the yield strength of existing rotor materials is close to 900 MPa, making them prone to SCC in high-stress areas. Therefore, this embodiment optimizes the material hierarchy to control the yield strength of the main shaft 10 and blades 40 to approximately 760 MPa (represented by 30Cr2Ni4MoV), reducing the material's sensitivity to SCC while meeting strength and stiffness requirements.

[0026] Combination Figure 3 As shown, in one embodiment, the leaf roots of at least three leaves 40 are fir-type leaf roots 43.

[0027] In this embodiment, the cross-section of the fir-shaped leaf root 43 is mirror-symmetrical along the centerline, and is composed of multiple levels of left-right symmetrical toothed steps and a neck transition. During assembly, the blade 40 is inserted axially into the corresponding fir-shaped wheel groove with the fir-shaped leaf root 43, and the working fit is achieved according to the predetermined interference fit and contact zone position, and is fixed by conventional limiting and constraint structures.

[0028] In one embodiment, the outer surface of the fir-shaped leaf roots 43 is covered with a crown-like band 44.

[0029] In this embodiment, the sheath 44 is a segmented ring that circumferentially encircles the fir-shaped leaf root 43 along the radial outer side of the blade 40. Its inner circumferential surface is machined with a fitting profile that matches the outer surface of the fir-shaped leaf root 43. An integrally formed crown step (i.e., a "self-crown" structure) is located on the inner circumferential surface near the axial direction, serving as a limiting shoulder corresponding to the outer surface of the leaf root in the assembled state, forming axial positioning. The outer circumferential surface of the sheath 44 is a cylinder or a stepped cylinder structure. Preferably, the sheath 44 is manufactured as a two- or three-segment circumferential segment, with each segment having a butt joint bevel and rounded corner transition at its end. After the end faces are joined, a small assembly gap is left circumferentially to absorb thermal expansion and vibration tolerances. During assembly, the sheath 44 is heated and expanded or cold-pressed and placed radially onto the outer surface of the fir-shaped leaf root 43, so that the self-contained crown on the inner circumference of the sheath 44 and the limiting shoulder of the leaf root are axially positioned, and the inner working belt and the outer surface of the leaf root form an interference or transition fit, and are fixed in non-working belt positions with process pins, clips or spot welding to prevent loosening and rotation.

[0030] In one embodiment, the blades 40 are provided with at least seven blades, which are arranged sequentially from the intake-side coupling 20 to the exhaust-side coupling 30 as first-stage blades, second-stage blades, third-stage blades, fourth-stage blades, fifth-stage blades, sixth-stage blades and seventh-stage blades. The blade roots of the second-stage blades, third-stage blades and fourth-stage blades are fir-shaped blade roots 43, and the blade roots of the fifth-stage blades and sixth-stage blades are provided with the clearance gap.

[0031] In this embodiment, at least seven stages of blades 40, i.e., the first to the seventh stage, are arranged axially along the main shaft 10 from the inlet-side coupling 20 to the exhaust-side coupling 30. Each stage of blade 40 is installed at the corresponding wheel groove position in the middle of the main shaft 10. Considering the actual operating conditions of the turbine rotor, where the fifth and sixth stages have high stress levels and are prone to defects during long-term operation, the stage and blade root type are designed in a graded manner in this embodiment: the blade roots of the second, third, and fourth stages uniformly adopt the fir tree-shaped blade root 43. The blade roots of the fifth and sixth stages adopt a clearance structure: that is, a profile with contour undulation is designed on the outer surface of the blade root, so that it forms a continuous clearance gap with the corresponding wheel groove of the main shaft 10 in the non-load-bearing area after assembly. For ease of manufacturing and description, this profile can be understood as a continuous contour with alternating working contact zones and non-working clearance zones; rounded corners are used at each transition to avoid sharp corners.

[0032] In one embodiment, the cross-sections of the plurality of blades 40 are mirror-symmetrical along the axis of the main shaft 10.

[0033] In this embodiment, multiple blades 40 are circumferentially distributed around the axis of the main shaft 10. Using the centerline of the main shaft 10 as a symmetry reference line, a symmetry plane encompassing this centerline is established. At any designed cross-section (orthogonal to the axis of the main shaft 10), the blades 40 located on both sides of the cross-section are arranged in pairs as symmetrical objects, such that the symmetry plane maps the cross-sectional profile of one side of the blade 40 to the cross-sectional profile of the other side of the blade 40, achieving mirror symmetry along the axis of the main shaft 10. If necessary, a circumferential band 44 can be provided around the blade 40 for circumferential constraint, and its segmentation and docking are also implemented according to the principle of symmetrical pairing.

[0034] In one embodiment, the turbine rotor further includes a locking element, which is spot-welded to the intake-side coupling 20.

[0035] In this embodiment, the turbine rotor is provided with a locking component on the intake side. The locking component can be an annular locking ring, which is installed in conjunction with the intake side coupling 20 and fixed by spot welding. The assembly process is as follows: S1, the intake-side coupling 20 is connected to the end of the main shaft 10 by a button or a tapered interference fit to complete the end face fit and radial positioning; S2, a locking ring is assembled on the axial positioning surface of the intake-side coupling 20, so that its inner circle and the corresponding limiting section of the intake-side coupling 20 achieve a transition or slight interference fit. The self-locking structure of the locking ring (e.g., circumferential wedge or anti-reverse tongue) is embedded in the corresponding groove of the intake-side coupling 20 to achieve primary anti-rotation; S3, a multi-point symmetrical spot welding connection is implemented at the contact boundary between the locking ring and the intake-side coupling 20, preferably three points are equally distributed, or two or four or more points are equally angled. The spot welding positions are located in the non-working zone and avoid the corners where stress is concentrated; S4, the appearance of the weld and penetrant / magnetic particle non-destructive testing are completed. After confirming that the weld nugget is continuous and defect-free, the overall dynamic balance is checked.

[0036] The locking ring and the intake-side coupling 20 can be made of alloy structural steel, the same material as the main shaft 10, and undergo the same or compatible heat treatment process to ensure welding metallurgical compatibility and dimensional stability. The spot welding process can be resistance spot welding or argon arc spot welding. The weld size, welding current, and heat input are set according to the material thickness and on-site tooling conditions, and batch production is implemented after successful trial welding. Unlike traditional screw-fastened structures, this embodiment, based on the self-locking fit of the locking ring, forms a secondary anti-loosening and permanent positioning through spot welding with the intake-side coupling 20. No additional fasteners are required after assembly, reducing maintenance procedures caused by loosening of connecting parts.

[0037] This utility model embodiment also provides a steam turbine, including the steam turbine rotor as described above.

[0038] Furthermore, the steam turbine is an impulse steam turbine.

[0039] In this embodiment, the turbine is a single-cylinder, single-flow, variable-speed impulse turbine. Under full-power operation, the turbine rotor typically operates at approximately 5000 rpm (the specific value is set based on the transmission ratio and pump set operating conditions). The assembly process includes: precision machining and fixture verification of the main shaft 10 and wheel grooves; machining of the blade root profile of the blades 40 (the second to fourth stages have fir-tree shaped blade roots 43, and the fifth and sixth stages have blade root profiles with clearance); if necessary, installing a sheathing 44 around the fir-tree shaped blade roots 43 and completing self-crown positioning; inserting the blades 40 axially and circumferentially symmetrically in pairs; spot welding the inlet-side coupling 20 to the locking element and connecting the end of the exhaust-side coupling 30; finally, performing non-destructive testing and overall mechanical balancing tests to confirm that the flow channel geometry, sealing clearance, and vibration limits for the impulse turbine are met before putting it into use.

[0040] Combination Figure 4 As shown in the figure, this utility model embodiment also provides a steam-driven feedwater pump set, including a steam turbine, a reduction gearbox, a booster pump and a pressure stage pump as described above. The pressure stage pump is connected to the steam turbine, and the booster pump is connected to the steam turbine through the reduction gearbox.

[0041] In this embodiment, the turbine's work capacity simultaneously drives both the booster pump and the pressure stage pump via mechanical transmission. The pressure stage pump directly transmits torque to the turbine via a gear coupling located between the turbine and the pressure stage pump's input shaft. The booster pump is connected to the turbine via a reduction gearbox; the input end of the reduction gearbox is connected to the turbine's output end, and the output end is connected to the booster pump's input shaft, thus matching the booster pump's speed. For ease of installation and maintenance, the gear coupling and the reduction gearbox are respectively equipped with coaxial alignment references and limiting shoulders, and anti-loosening structures (such as keys / splines or anti-loosening shims) are fitted at their ends.

[0042] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A steam turbine rotor, used in a steam turbine, characterized in that, The device includes a main shaft, an intake-side coupling, an exhaust-side coupling, and multiple blades. The intake-side coupling and the exhaust-side coupling are respectively located at both ends of the main shaft and are both connected to the steam turbine. The multiple blades are spaced apart in the middle of the main shaft. At least two blades have multiple convex sections and concave sections on the outer surface of their blade roots. The convex sections and concave sections are alternately connected, and at least one concave section is provided between every two convex sections to form a clearance gap.

2. The turbine rotor according to claim 1, characterized in that, The main shaft and multiple blades are all made of alloy structural steel.

3. The turbine rotor according to claim 1, characterized in that, At least three of the leaf roots are fir-type leaf roots.

4. The turbine rotor according to claim 3, characterized in that, The outer surface of each fir-shaped leaf root is covered with a self-contained crown-like band.

5. The turbine rotor according to claim 3, characterized in that, The blades are provided with at least seven, and are arranged in the following order from the intake-side coupling to the exhaust-side coupling: first-stage blade, second-stage blade, third-stage blade, fourth-stage blade, fifth-stage blade, sixth-stage blade, and seventh-stage blade. The blade roots of the second-stage blade, third-stage blade, and fourth-stage blade are fir-shaped blade roots, and the blade roots of the fifth-stage blade and sixth-stage blade are provided with the clearance gap.

6. The turbine rotor according to claim 1, characterized in that, The cross-sections of the plurality of blades are mirror-symmetrical along the axis of the main shaft.

7. The turbine rotor according to claim 1, characterized in that, It also includes a locking component, which is spot-welded to the intake-side coupling.

8. A steam turbine, characterized in that, Including the turbine rotor as described in any one of claims 1-7 above.

9. The steam turbine according to claim 8, wherein the steam turbine is an impulse steam turbine.

10. A steam-driven feedwater pump set, characterized in that, It includes the steam turbine, reduction gearbox, booster pump and pressure stage pump as described in claim 8 above, wherein the pressure stage pump is connected to the steam turbine, and the booster pump is connected to the steam turbine through the reduction gearbox.

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