A turbine shroud type stationary vane welding diaphragm

Abstract

This invention relates to a turbine rotor blade shroud welded diaphragm, comprising a rotor blade, an outer shroud, an inner shroud, an outer ring, and an inner ring. Both the outer and inner shrouds are fully annular structures, respectively positioned at the top and bottom ends of the rotor blade. The outer and inner shrouds are respectively provided with external and internal shaped holes adapted to the cross-sections of the rotor blade's top and bottom ends. The top and bottom ends of the rotor blade are respectively inserted into and welded into the external and internal shaped holes. This invention achieves precise positioning of the rotor blade by providing shrouds with shaped holes at both ends of a rotor blade without a blade crown or root, ensuring key parameters such as throat width, blade pitch, and steam inlet angle, effectively preventing welding deformation, and improving weld strength and diaphragm service life.

Description

Technical Field

[0001] This invention belongs to the field of steam turbine technology, and specifically relates to a turbine shroud type stationary blade welded diaphragm. Background Technology

[0002] A steam turbine is a rotary power machine that converts the thermal energy of steam into mechanical energy. The stationary blade is the core stationary part of the steam turbine cylinder, which is used to cooperate with the corresponding moving blades on the rotor to form a flow structure that drives the rotor to rotate.

[0003] In the early days, direct-welded diaphragms were commonly installed inside the turbine cylinders of power plants. The blades in these diaphragms lacked crowns and roots, being directly welded to the inner and outer rings. Due to the lack of precise positioning with slots or crowns, the blades relied entirely on suspended spot welding for fixation, leading to the following problems: deformation easily occurred during welding; positioning lacked a reference point, resulting in uncontrollable dimensions of the diaphragm throat, steam outlet angle, pitch, and flow area, causing significant deviations and affecting the uniformity of steam circumferential flow, which in turn induced rotor vibration and reduced unit efficiency.

[0004] Specifically, existing direct-welded partitions have the following disadvantages: 1. The stationary blades are not precisely positioned and are directly welded to the inner and outer rings. During the stress-relief annealing process after welding, free creep without mechanical restraint is likely to occur, resulting in low pass rates for throat diameter, pitch, and steam inlet angle.

[0005] 2. Direct welding of stationary blades relies on simple tooling clamping, which increases the difficulty of tooling positioning before welding on site, and key dimensions are prone to drift and exceed tolerances during the welding process.

[0006] 3. Thin-walled stationary blades are directly welded into thick-walled inner and outer rings. The welding heat is concentrated, which can easily lead to welding bending and blade profile torsion deformation.

[0007] 4. The stationary blades are directly welded to the inner and outer rings. Due to the influence of high temperature and high pressure steam, the weld is prone to cracking and separation. Summary of the Invention

[0008] The purpose of this invention is to provide a turbine shroud-type welded diaphragm for stationary blades, in order to solve the problems of low positioning accuracy of stationary blades, large welding deformation, and easy cracking of welds in existing straight-welded diaphragms.

[0009] The technical solution adopted in this invention is: A welded bulkhead for turbine stationary blades, comprising: stationary blades; An outer ring, forming a ring, is positioned at the tip of the stationary blade, and has an externally shaped hole that matches the cross-section of the stationary blade tip; and The inner circumference band is ring-shaped and set at the bottom end of the stationary blade, and has an inner hole that matches the cross-section of the bottom end of the stationary blade. The top end of the stationary blade is inserted and welded into the outer hole, and the bottom end is inserted and welded into the inner hole.

[0010] Furthermore, the outer perimeter has an outward inclination angle, and the height of the air passage of the stationary blade gradually increases from the steam inlet side to the steam outlet side along its top, and its increasing trend is adapted to the outward inclination angle, which is 28°.

[0011] Furthermore, the thickness of the outer and inner circumference bands is the same as the thickness of the stationary blade.

[0012] Furthermore, the number of both the outer and inner holes is equal to the number of stationary blades, and a steam passage is formed between two adjacent stationary blades.

[0013] Furthermore, it also includes an outer ring and an inner ring, with the outer ring welded and fixed to the inner hole of the outer ring, and the inner ring welded and fixed to the outer circle of the inner ring.

[0014] Furthermore, the inner hole of the outer ring is provided with an inner bevel, and the outer perimeter band is welded and fixed to the outer ring through the inner bevel; the outer circle of the inner ring is provided with an outer bevel, and the inner perimeter band is welded and fixed to the inner ring through the outer bevel.

[0015] Furthermore, the outer ring includes an upper outer ring and a lower outer ring, and the inner ring includes an upper inner ring and a lower inner ring; a centering pin is provided between the upper outer ring and the lower outer ring, and a centering key is provided between the upper inner ring and the lower inner ring.

[0016] Furthermore, the centering pin is a stepped pin with an upper rhombus shape and a lower cylinder. Its lower cylindrical section is interference-fitted onto the lower outer ring, and its upper rhombus section is guided and plugged into the upper outer ring. The guiding height of the centering pin is higher than the height of the centering key, so that when the upper half and the lower half are connected, the centering pin is first guided and then the centering key prevents rotation.

[0017] Furthermore, the bottom end of the outer ring is provided with a bottom key, and slots are symmetrically opened on both horizontal sides of the outer ring.

[0018] Furthermore, the inner ring is provided with a steam seal groove, and a steam seal ring is installed in the steam seal groove.

[0019] The positive effects of this invention are: This invention replaces the traditional manual placement and direct welding method by incorporating outer and inner circumferential bands at both ends of the stationary blades. The bands have pre-formed holes that match the blade cross-section, allowing the stationary blades to be precisely positioned before welding. This ensures the accuracy of key parameters affecting steam flow area, such as the stationary blade throat width, blade pitch, and inlet angle, thus guaranteeing the unit's rated output. The banded design forms a single welded body at both ends of the stationary blades, significantly enhancing weld strength. This welded body is then welded to the inner and outer rings to form a double-layer welded structure, effectively resisting high-temperature, high-pressure steam erosion, preventing weld cracking and detachment, and extending the service life of the baffle plate. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the steam inlet side structure of the present invention; Figure 2 This is a schematic diagram of the steam outlet side structure of the present invention; Figure 3 For the present invention Figure 1 Sectional view along line AA; Figure 4 For the present invention Figure 2 Sectional view along the BB direction; Figure 5 For the present invention Figure 2 Diagram showing the connection structure between the upper and lower inner rings at point C; Figure 6 For the present invention Figure 1 Sectional view along the FF direction; Figure 7 For the present invention Figure 1 Central GG-direction sectional view; Figure 8 This is a schematic diagram of the outer band structure of the present invention; Figure 9 This is a schematic diagram of the inner circumferential band structure of the present invention. Detailed Implementation

[0021] As attached Figure 1-9 As shown, this invention discloses a turbine shroud-type welded diaphragm for stationary blades. The diaphragm mainly consists of an outer ring 1, an inner ring 2, an outer perimeter band 3, an inner perimeter band 4, and stationary blades 5. The diaphragm is a two-part finished structure, and the outer ring 1, inner ring 2, outer perimeter band 3, and inner perimeter band 4 are all integrally formed during welding.

[0022] Stationary blade 5 is a flat, twisted blade without a crown or root. This means that along the steam duct height T6, the blade profile at different horizontal heights undergoes twisting and change. Stationary blade 5 has a reaction-type blade profile, resulting in low steam flow loss, high work efficiency, and suitability for variable operating conditions.

[0023] The outer ring 3 is a circular structure located on the outer side of the top of the stationary blade 5 and is made of rolled steel plate. The thickness of the outer ring 3 is the same as the average thickness of the stationary blade 5. The outer ring 3 has evenly distributed external holes 31 that match the cross-section of the top of the stationary blade 5, and the number of external holes 31 is equal to the number of stationary blades 5. Preferably, the external holes 31 are cut according to the shape before the steel plate is rolled into a circle, and then the circular structure is formed by rolling and welding. The top of the stationary blade 5 is inserted into and welded into the external holes 31, realizing the distribution and positioning of the top circumference of the stationary blade 5.

[0024] The inner circumferential band 4 is a complete ring structure, located inside the bottom end of the stationary blade 5, and is made of rolled steel plate. The thickness of the inner circumferential band 4 is the same as the average thickness of the stationary blade 5. The inner circumferential band 4 has evenly distributed inner holes 41 that match the cross-section of the bottom end of the stationary blade 5, and the number of inner holes 41 is equal to the number of stationary blades 5. Preferably, the inner holes 41 are cut according to the shape before the steel plate is rolled into a circle, and then the complete circular structure is formed by rolling and welding. The bottom end of the stationary blade 5 is inserted into and welded into the inner holes 41, realizing the distribution and positioning of the bottom circumference of the stationary blade 5.

[0025] The thickness of the outer and inner rings is consistent with the average thickness of the stationary blades. The welding temperature is controllable and the thermal stress is uniform, which avoids welding bending and blade profile torsion deformation caused by heat concentration when thin-walled blades are directly welded to thick-walled inner and outer rings.

[0026] Stationary blades 5 are evenly distributed between the outer perimeter zone 3 and the inner perimeter zone 4. A steam passage 51 is formed between two adjacent stationary blades 5, and the total number of steam passages 51 equals the number of stationary blades 5. Steam expands and accelerates along the steam passage 51 to do work. At half the height T6 of the steam passage, the circumference of the stationary blade 5 is the pitch circle line 52. On this pitch circle line 52, the minimum directly measurable clearance between each blade is the throat width T4. The inlet side of the stationary blade 5 has a leading edge, the diameter of which is equal to the leading edge thickness T1. The outlet side has a trailing edge, the diameter of which is equal to the trailing edge thickness T2. The angle between the tangent connecting the leading and trailing edge's minimum inscribed circles and the reference plane is the inlet angle T3. The reference distance between the trailing edges of two adjacent stationary blades 5 is the blade pitch T5. Based on the number of blades installed in the entire ring and the steam parameters, the optimal assembly parameters such as the inlet angle T3, throat width T4, and blade pitch T5 can be calculated, thereby determining the flow area and blade reaction degree value at steam passage 51, ensuring the stage efficiency of the diaphragm and rotor.

[0027] The outer band 3 has an outward inclination angle of 32°, which is 28°, while the inner band 4 has an inward inclination angle of 42°, which is 0°. The stationary blades 5, along the axial direction from the inlet to the outlet side, have their bottom profile arranged horizontally to match the inward inclination angle 42 of the inner band 4; their top profile is arranged obliquely to match the outward inclination angle 32 of the outer band 3. Thus, the steam passage height T6 gradually increases axially, facilitating steam expansion.

[0028] By setting the outer perimeter band 3 and the inner perimeter band 4, the stationary blade 5 without leaf crown or leaf root is precisely positioned and welded together to form a welded body of the stationary blade and the perimeter band.

[0029] Outer ring 1 is a steel ring with an inner bevel on its inner diameter, and inner ring 2 is a steel ring with an outer bevel on its outer diameter. Outer band 3 is seated in the inner diameter of outer ring 1 and fixed to outer ring 1 by welding through the inner bevel; inner band 4 is seated on the outer diameter of inner ring 2 and fixed to inner ring 2 by welding through the outer bevel. Thus, outer ring 1 and outer band 3 are connected as one unit on the outside by stationary blade 5, and inner ring 2 and inner band 4 are connected as one unit on the inside, forming a complete partition structure. Then, this complete partition structure is cut into two halves by wire cutting, with the mating surface of the two halves being the dividing surface 11.

[0030] The outer ring 1 is divided into an upper outer ring 12 and a lower outer ring 13. The inner ring 2 is divided into an upper inner ring 21 and a lower inner ring 22. The upper outer ring 12, the upper inner ring 21 and half of the stationary blades 5 form the upper half of the partition plate, and the lower outer ring 13, the lower inner ring 22 and half of the stationary blades 5 form the lower half of the partition plate.

[0031] To achieve rapid alignment and anti-rotation of the upper and lower halves of the partition, a centering pin 14 is symmetrically distributed between the upper outer ring 12 and the lower outer ring 13 at the midpoint 11. The centering pin 14 is a stepped pin with an upper rhombus shape and a lower cylindrical shape. The lower cylindrical section is interference-fitted into the hole of the lower outer ring 13, while the upper rhombus section is guided and inserted into the upper outer ring 12. At the midpoint 11, a centering key 23 and a pressure block 24 are symmetrically distributed between the upper inner ring 21 and the lower inner ring 22. Both the centering key 23 and the pressure block 24 are rectangular long keys connected to the upper inner ring 21 by screws. The lower inner ring 22 has a keyway of the same length as the long key at this position to guide the insertion and removal of the lower inner ring 22. The guide height of the centering pin 14 is higher than that of the centering key 23. When the upper and lower halves of the partition are connected, the centering pin 14 first guides and aligns the partition, and then the centering key 23 guides and prevents rotation, thus meeting the requirements for quick alignment and installation of the partition on site.

[0032] A slot 15 is formed on the outer ring 1 at the midpoint 11, and the slots are symmetrically distributed on the left and right sides. The slots 15 are arranged on the sides of the upper outer ring 12 and the lower outer ring 13. The upper locking block passes through the slot 15 to fix the upper outer ring 12 in the upper cylinder to prevent it from falling off, and the lower locking block passes through the slot 15 to fix the lower outer ring 13 in the lower cylinder to prevent it from rotating.

[0033] A keyway is provided at the bottom of the lower outer ring 13, and the bottom key 9 is fixedly connected to it with screws. By adjusting the distance between the left and right planes of the bottom key 9 and the center line, the left and right distribution gap of the lower outer ring 13 and the partition plate as a whole in the lower cylinder can be adjusted.

[0034] An annular steam seal groove 25 is provided on the inner circumferential surface of the inner ring 2. A steam seal ring 8 is inserted into the groove, which is fitted with the rotor shaft diameter to form a dynamic-static seal. The preferred gap is 0.5mm, thereby realizing the steam seal between the stationary part of the partition and the moving part of the rotor, ensuring that the steam effectively expands and does work along the blade steam passage 51.

[0035] A water-removing ring 6 is installed around the entire circumference of the outer ring 1 on the steam outlet side, with a steam-blocking plate 61 installed on its inner diameter. The water-removing ring 6 effectively collects steam condensate, preventing high-pressure condensate from impacting the steam inlet edge of the moving blades and protecting the moving blades from erosion. The steam-blocking plate 61 forms a small-gap sealing fit with the blade crown of the moving blades installed on the rotor impeller, thereby guiding the steam flow.

[0036] The outer ring 1 has evenly distributed cylindrical pin holes on the steam inlet side of its outer circumference, and cylindrical pins 7 are installed inside. The positioning width of the partition plate installed in the cylinder block groove is adjusted by adjusting the exposed length of the circumferential cylindrical pins 7. Preferably, the upper outer ring 12 has 4 cylindrical pins 7 and the lower outer ring 13 has 4 cylindrical pins 7, which replaces the method of adjusting the positioning width value of the assembly with the cylinder block by adjusting the thickness of the outer ring 1 body.

[0037] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. 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 welded diaphragm for turbine stationary blades, characterized in that... It includes: stationary blades (5); An outer ring (3) is provided at the top of the stationary blade (5), and an outer hole (31) adapted to the cross-section of the top of the stationary blade (5) is provided thereon; and The inner circumference band (4) is in the shape of a ring and is set at the bottom end of the stationary blade (5). An inner hole (41) is provided on it that is adapted to the cross section of the bottom end of the stationary blade (5). The top end of the stationary blade (5) is inserted and welded into the outer hole (31), and the bottom end is inserted and welded into the inner hole (41).

2. The turbine shroud type welded diaphragm according to claim 1, characterized in that... The outer band (3) has an outward inclination angle (32), and the air passage height (T6) of the stationary blade (5) gradually increases from the steam inlet side to the steam outlet side along its top, and its increasing trend is compatible with the outward inclination angle (32), which is 28°.

3. The turbine shroud type welded diaphragm according to claim 1, characterized in that... The number of the outer holes (31) and the inner holes (41) are equal to the number of stationary blades (5), and a steam passage (51) is formed between two adjacent stationary blades (5).

4. A turbine shroud-type welded diaphragm for stationary blades according to any one of claims 1-3, characterized in that... It also includes an outer ring (1) and an inner ring (2), with an outer perimeter band (3) welded and fixed to the inner hole of the outer ring (1), and an inner perimeter band (4) welded and fixed to the outer circle of the inner ring (2).

5. A turbine shroud-type welded diaphragm for stationary blades according to claim 4, characterized in that... The inner hole of the outer ring (1) is provided with an inner bevel, and the outer band (3) is welded and fixed to the outer ring (1) through the inner bevel; the outer circle of the inner ring (2) is provided with an outer bevel, and the inner band (4) is welded and fixed to the inner ring (2) through the outer bevel.

6. A turbine shroud-type welded diaphragm for stationary blades according to claim 4, characterized in that... The outer ring (1) includes an upper outer ring (12) and a lower outer ring (13), and the inner ring (2) includes an upper inner ring (21) and a lower inner ring (22); a centering pin (14) is provided between the upper outer ring (12) and the lower outer ring (13), and a centering key (23) is provided between the upper inner ring (21) and the lower inner ring (22).

7. A turbine shroud-type welded diaphragm for stationary blades according to claim 6, characterized in that... The centering pin (14) is a stepped pin with an upper rhombus shape and a lower cylinder. Its lower cylindrical section is installed in an interference fit on the lower outer ring (13), and the upper rhombus section is guided and plugged into the upper outer ring (12). The guide height of the centering pin (14) is higher than the height of the centering key (23), so that when the upper half and the lower half are connected, the centering pin (14) is first guided and then the centering key (23) prevents rotation.

8. A turbine shroud-type welded diaphragm for stationary blades according to claim 4, characterized in that... The bottom of the outer ring (1) is provided with a bottom key (9), and slots (15) are symmetrically opened on both sides of the outer ring (1) at horizontal level.

9. A turbine shroud-type welded diaphragm for stationary blades according to claim 4, characterized in that... The inner ring (2) is provided with a steam seal groove (25), and a steam seal ring (8) is installed in the steam seal groove (25).

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