A final stage moving blade

Abstract

The invention discloses a last-stage moving blade and relates to the technical field of steam turbine blades. The last-stage moving blade provided by the invention aims at the problem of insufficient last-stage blades for high-speed industrial steam turbines, takes industrial steam turbine units with speeds and powers exceeding 10,000 as the target, provides an independently developed last-stage moving blade with excellent variable-condition aerodynamic performance and strength vibration performance, and is suitable for industrial steam turbines with a back pressure of 5 to 25 KPa, a speed regulation range of 7500 rpm to 11000 rpm, and an exhaust steam flow rate of 70 t / h. The invention adopts an inclined four-tooth fir-tree-shaped blade root and a half-split loose-tensioned full-circle connection structure, has excellent variable-condition aerodynamic performance, high strength, good damping characteristics, and a firm and stable combination of the blade and the rotor, which can meet the safety requirements of the blade.

Description

Technical Field

[0001] The invention relates to the technical field of steam turbine blades, and in particular to a last-stage moving blade. Background Art

[0002] In the industrial production process of modern enterprises, there are a large number of various production processes that require both power and by-product heat energy. In order to improve energy utilization and achieve energy conservation, there is a wide demand for industrial steam turbines. Especially in the chemical industry, industrial steam turbines can directly drive machines such as pumps, blowers and compressors in the production process, and flexibly and stably coordinate with these driven machines to change speeds to adapt to changes in production process working conditions. The advantages are very obvious.

[0003] Industrial steam turbines are different from conventional power station steam turbines. Their operating speed is determined by the driven device and is usually variable speed operation. The speed can reach 7000-10000r / min or even higher, and the power ranges from several thousand kilowatts to tens of thousands of kilowatts. The high speed of industrial steam turbines and the wide and frequent changes in operating conditions bring great difficulties to the aerodynamic, strength and vibration design of the low-pressure flow final stage blades. A comprehensive consideration must be made to design high-performance final stage blades. At the same time, various factors such as the rationality of material selection and manufacturing difficulty must also be considered.

[0004] At present, most of the domestic industrial steam turbine last-stage blades are below 6000rpm. There are fewer and smaller last-stage blades with higher speeds, which cannot meet the needs of modern industry for high-end industrial drive steam turbines, namely high speed, high efficiency and high load. One of the typical models of high-end industrial steam turbines has a power of more than 10000KW and a rated operating speed of 10000rpm or above, which represents the comprehensive strength of steam turbine manufacturers. Summary of the invention

[0005] The purpose of the present invention is: to address the above-mentioned problems, the present invention provides a last-stage moving blade, and to address the problem of insufficient last-stage blades for the above-mentioned high-speed industrial steam turbines, with the industrial steam turbine units with a speed and power of over 10,000 as the target, to provide an independently developed last-stage moving blade with excellent variable operating condition aerodynamic performance and strength vibration performance, which is suitable for industrial steam turbines with a back pressure of 5 to 25 KPa, a speed regulation range of 7500 rpm to 11000 rpm, and an exhaust steam flow rate of 70 t / h; it adopts an inclined four-tooth fir-tree-shaped blade root and a half-split loose-tensioned full-circle connection structure, which has excellent variable operating condition aerodynamic performance, high strength, good damping characteristics, and the blades are firmly and stably combined with the rotor, which can meet the safety requirements of the blades.

[0006] The technical solution adopted by the present invention is as follows:

[0007] A last-stage moving blade comprises a single blade, wherein the single blade comprises a blade root and a blade body; the blade root is located at the root of the blade body, the blade root and the blade body are an integral structure, and the blade body is a special-shaped body formed by superimposing a number of characteristic cross sections according to a specific rule; the contour line of the characteristic cross section is a closed curve surrounded by an inner arc curve and a back arc curve, and has characteristic parameters: blade profile installation angle C, blade body cross section chord length B, blade body cross section maximum thickness W, blade body cross section axial width Xa, blade body cross section area A; the superposition rule of the characteristic cross sections is that each cross section from the root end of the blade body to the top end of the blade body has a continuous and smooth transition along the blade height direction, the root of the blade body is a subsonic blade shape, the middle part is a transonic blade shape, and the top part is a supersonic blade shape, the blade body has a blade height Ld of 221 mm and a root diameter Dr of 400 mm; the relative value of the blade height Ld is monotonically increased from 0.0 Increases to 1.0; Correspondingly, the blade installation angle C decreases monotonically from 74.03° to 21.74°; the relative change law of the blade cross-sectional area A from the root section to the top section decreases monotonically from 4.197 to 1.0; the relative change law of the blade cross-sectional axial width Xa from the root section to the top section decreases monotonically from 3.184 to 1.0; the relative change law of the blade cross-sectional chord length B from the root section to the top section decreases monotonically from 1.273 to 1.0; the relative change law of the maximum thickness W of the blade cross-sectional area from the root section to the top section decreases monotonically from 2.489 to 1.0. The blade profile of the single blade is monotonically twisted along the height, and the relative value of its outlet geometric angle α1 decreases monotonically from 1.795 to 1.0 along the height direction from the blade root to the blade tip. The calculation process of the outlet geometric angle α1 is shown in the following formula (1):

[0008] α1=sin -1 (O / T) (1)

[0009] In formula 1, O is the width of the exit throat of the blade section, that is, the minimum distance between the steam outlet edge F of the blade profile and the back arc D of the adjacent blade section, and T is the circumferential installation distance of the profile sections of the same height of two adjacent single blades.

[0010] Furthermore, there is a tie rod hole on the blade body, and the height Lj of the center of the tie rod hole satisfies the relationship 0.7≤Lj / Ld≤0.85; the diameter Φ of the tie rod hole satisfies the relationship 7mm≤Φ≤10.5mm.

[0011] Furthermore, the inner arc E and the back arc D of the blade body have a smooth thickness reinforcement area along the axial direction and the blade height direction of the tie rod hole in the area matching the tie rod hole.

[0012] By adopting the above technical solution, the weakening of the cross section where the tie rod hole is located can be effectively compensated, and the stress concentration in the intersection area between the tie rod hole and the blade body surface can be reduced.

[0013] Furthermore, it also includes a loosening reinforcement, wherein the loosening reinforcement can pass through the reinforcement hole and match the reinforcement hole, and the diameter of the loosening reinforcement Satisfies the relationship: The length L satisfies the relationship 2.7·T1≤L≤2.95·T1 or 5.7·T1≤L≤5.95·T1 or 11.7·T1≤L≤11.95·T1; the loose reinforcement forms an arc structure along the length L according to the radius R. The calculation process of the radius R is shown in the following formula (2):

[0014] R=(Dr / 2+Lj) (2)

[0015] In Formula 2, Dr is the blade root diameter, that is, the diameter of the circle where the root section of the blade body is located after the single blade is installed on the rotor, and Lj is the height position of the tie rod hole on the blade body.

[0016] Furthermore, the loose reinforcement is radially divided into equal half reinforcements, and the two half reinforcements can be matched with each other and pass through the reinforcement holes.

[0017] Furthermore, the plurality of single blades surround the rotor and are evenly distributed on the outer circle of the rotor, the blade root is confined in the impeller groove on the outer circle of the rotor, the loose tension rod passes through the tension rod hole to connect the plurality of blade bodies, and the loose tension rod surrounds the rotor to form an annular structure.

[0018] Furthermore, a blade cascade channel is formed between two adjacent single blades, and the half tie rods on the same side cooperate with each other to form a half tie rod ring, and the two half tie rod rings on the opposite side can be combined to form a loose tie rod ring; in the same half tie rod ring, the adjacent half tie rod end faces cooperate in the middle of the blade cascade channel to form an intersection area, and an intersection gap Ga is arranged at the intersection area, and the intersection areas in the two half tie rod rings on the opposite side are arranged in different blade cascade channels.

[0019] Due to the adoption of the above technical solution, by controlling the intersection gap Ga, the length of the cantilever at the extended end formed by the end of the semi-tensioned bar extending out of the tensioning hole can be effectively adjusted, thereby ensuring the safety of the cantilever at the extended end of the semi-tensioned bar.

[0020] Furthermore, the end of the half tie rod is provided with a limiting portion which can be limited to the tie rod hole.

[0021] Due to the adoption of the above technical solution, the end of the half-tie bar is locally positioned to prevent the half-tie bar from moving significantly in the circumferential direction, thereby connecting the entire circle of the blade body to achieve the effect of a circle damping connection.

[0022] Furthermore, it also includes a rotor, wherein the blade root is an inclined four-tooth longitudinal tree-shaped blade root; the axial width Bg of the blade root satisfies the relationship: 90mm≤Bg≤150mm.

[0023] Furthermore, the horizontal angle between the blade root centerline and the rotor center axis U is D1, and the angle D1 satisfies the relationship: 0°≤D1≤30°.

[0024] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0025] 1. The present invention is applicable to industrial steam turbines with a back pressure of 5 to 25 KPa, a speed range of 7500 rpm to 11000 rpm, and an exhaust flow rate of 70 t / h; under medium temperature and medium pressure, high temperature and high pressure, and high temperature and ultra-high pressure steam environments, the pure condensing power of the unit covers 6 MW to 20 MW, which can well meet the demand of the chemical industry for steam turbine models near the 10000 rpm level, meet the demand of the domestic market for high-speed and high-power industrial steam turbines, enhance the competitiveness in the international market, and have broad market application prospects.

[0026] 2. The present invention adopts an inclined four-tooth fir-tree-shaped blade root and a half-split loose-tensioned full-circle connection structure, which has excellent variable-condition aerodynamic performance, high strength, and good damping characteristics. The blades and rotors are firmly and stably combined, and can meet the safety requirements of the blades.

[0027] 3. The present invention has high economy and reliability.

[0028] 4. The present invention can effectively compensate for the weakening of the cross section where the tie rod hole is located and reduce the stress concentration in the intersection area between the tie rod hole and the blade body surface.

[0029] 5. The present invention can prevent the semi-tensioning bar from moving significantly in the circumferential direction, thereby connecting the entire circle of blades to achieve the effect of a circle damping connection. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic diagram of the structure of a single blade;

[0031] Figure 2 is a schematic diagram of the blade cross section;

[0032] Figure 3 It is a schematic diagram of the blade root structure;

[0033] Figure 4 This is the main view of loosening the tie rod assembly;

[0034] Figure 5 It is a schematic diagram of the loose tension reinforcement assembly structure;

[0035] Figure 6 It is a schematic diagram of the structure in which the loose tension bars are assembled along the blade height direction;

[0036] Figure 7 It is the stress distribution cloud diagram of a single blade;

[0037] Figure 8 It is the streamline distribution diagram of the last stage moving blades.

[0038] Markings in the figure: 1-blade root, 2-blade body, 3-thickness reinforcement area, 4-tensioning hole, 5-half tensioning, 6-blade cascade channel, 7-limiting part. DETAILED DESCRIPTION

[0039] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0040] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0041] Example 1

[0042] A final stage moving blade, such as Figure 1-8 As shown, it includes a single blade, and the single blade includes a blade root 1 and a blade body 2; the blade root 1 is located at the root of the blade body 2, the blade root 1 and the blade body 2 are an integral structure, and the blade body 2 is a special-shaped body formed by superimposing a number of characteristic sections according to a specific rule; the contour line of the characteristic section is a closed curve surrounded by an inner arc curve and a back arc curve, and has characteristic parameters: blade installation angle C, blade body section chord length B, blade body section maximum thickness W, blade body section axial width Xa, blade body section area A; the superposition rule of the characteristic sections is that each section from the root end of the blade body 2 to the top end of the blade body 2 has a continuous and smooth transition along the blade height direction, the root of the blade body 2 is a subsonic blade shape, the middle is a transonic blade shape, and the top is a supersonic blade shape, the blade height Ld of the blade body 2 is 221mm, and the root diameter Dr is 400mm; the relative value of the blade height Ld is 0. 0 increases monotonically to 1.0; correspondingly, the blade installation angle C decreases monotonically from 74.03° to 21.74°; the relative change law of the blade cross-sectional area A from the root section to the top section decreases monotonically from 4.197 to 1.0; the relative change law of the blade cross-sectional axial width Xa from the root section to the top section decreases monotonically from 3.184 to 1.0; the relative change law of the blade cross-sectional chord length B from the root section to the top section decreases monotonically from 1.273 to 1.0; the relative change law of the maximum thickness W of the blade cross-sectional area from the root section to the top section decreases monotonically from 2.489 to 1.0. The blade profile of the single blade is monotonically twisted along the height, and the relative value of its outlet geometric angle α1 decreases monotonically from 1.795 to 1.0 along the height direction from the blade root to the blade tip. The calculation process of the outlet geometric angle α1 is shown in the following formula (1):

[0043] α1=sin -1 (O / T) (1)

[0044] In formula 1, O is the width of the exit throat of the blade 2 section, that is, the minimum distance between the steam outlet edge F of the blade profile and the back arc D of the adjacent blade 2 section, and T is the circumferential installation distance of the profile sections of the same height of two adjacent single blades.

[0045] The specific parameters of each section of the blade body 1 are as follows:

[0046]

[0047]

[0048] The blade body 2 is provided with a tie rod hole 4, and the height Lj of the center of the tie rod hole 4 satisfies the relationship of 0.7≤Lj / Ld≤0.85; the diameter Φ of the tie rod hole 4 satisfies the relationship of 7mm≤Φ≤10.5mm.

[0049] The inner arc E and the back arc D of the blade body 2 have a smooth thickness reinforcement area 3 along the axial direction and blade height direction of the tie rod hole 4 in the area matching the tie rod hole 4. Specifically, it can effectively compensate for the weakening of the cross section where the tie rod hole 4 is located and reduce the stress concentration in the intersection area between the tie rod hole 4 and the blade body 2 profile.

[0050] It also includes a loosening reinforcing bar, which can pass through the reinforcing bar hole 4 and match the reinforcing bar hole 4. The diameter of the loosening reinforcing bar Satisfies the relationship: The length L satisfies the relationship 2.7·T1≤L≤2.95·T1 or 5.7·T1≤L≤5.95·T1 or 11.7·T1≤L≤11.95·T1; the loose reinforcement forms an arc structure along the length L according to the radius R. The calculation process of the radius R is shown in the following formula (2):

[0051] R=(Dr / 2+Lj) (2)

[0052] In Formula 2, Dr is the blade root diameter, that is, the diameter of the circle where the root cross section of the blade body 2 is located after the single blade is installed on the rotor, and Lj is the height position of the tie rod hole 4 on the blade body 2.

[0053] like Figure 4-6 As shown, the loose reinforcement is radially divided into equal half reinforcements 5, and the two half reinforcements 5 can be matched with each other and pass through the reinforcement hole 4.

[0054] The plurality of single blades surround the rotor and are evenly distributed on the outer circle of the rotor. The blade root 1 is confined in the impeller groove on the outer circle of the rotor. The loose tie rod passes through the tie rod hole 4 to connect the plurality of blade bodies 2. The loose tie rod surrounds the rotor to form an annular structure.

[0055] A blade cascade channel 6 is formed between two adjacent single blades, and the half tie bars 5 on the same side cooperate with each other to form a half tie bar ring, and the two half tie bar rings on the opposite side can be combined to form a loose tie bar ring; in the same half tie bar ring, the end faces of adjacent half tie bars 5 cooperate in the middle of the blade cascade channel 6 to form an intersection area, and an intersection gap Ga is provided at the intersection area, and the intersection areas in the two half tie bar rings on the opposite side are arranged in different blade cascade channels 6.

[0056] Specifically, by controlling the intersection gap Ga, the length of the cantilever at the outward end formed by the end of the half tie rod 5 extending out of the tie rod hole 4 can be effectively adjusted, thereby ensuring the safety of the cantilever at the outward end of the half tie rod 5.

[0057] The end of the semi-tensioning bar 5 is provided with a limiting portion 7 which can be limited to the tensioning bar hole. Preferably, the limiting portion 7 is a protrusion spot-welded on the end of the semi-tensioning bar 5 .

[0058] Specifically, the end of the half tie bar 5 is locally positioned to prevent the half tie bar 5 from moving significantly in the circumferential direction, thereby connecting the entire circle of the blade body 2 to achieve the effect of a circle damping connection.

[0059] It also includes a rotor, wherein the blade root 1 is an inclined four-tooth longitudinal tree-shaped blade root; the axial width Bg of the blade root 1 satisfies the relationship: 90mm≤Bg≤150mm.

[0060] The horizontal angle between the center line of the blade root 1 and the rotor center axis U is D1, and the angle D1 satisfies the relationship: 0°≤D1≤30°.

[0061] like Figure 7 As shown, at the maximum continuous operating speed of 11000rpm, the centrifugal force of the single blade is very large, reaching 49.5 tons; the stress distribution of the single blade and the matching wheel groove and loose tension bar is relatively uniform, without obvious stress singularity area, and the strength performance of the material is reasonably utilized. The selection of conventional moving blade materials can meet the operating speed requirements described in this embodiment.

[0062] like Figure 8 As shown, the flow field of the single blade is evenly distributed, can well adapt to the changes in operating conditions within the speed regulation range, and has excellent aerodynamic performance.

[0063] The principles and implementation methods of the present invention are described in this article using specific embodiments. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0064] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the inventive product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as a limitation on the present invention.

[0065] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

Claims

1. A last-stage moving blade, comprising a single blade, wherein the single blade comprises a blade root and a blade body; the blade root is located at the root of the blade body, the blade root and the blade body are an integral structure, and the blade body is a special-shaped body formed by superimposing a number of characteristic cross sections according to a specific rule; the contour line of the characteristic cross section is a closed curve surrounded by an inner arc curve and a back arc curve, and has characteristic parameters: blade installation angle C, blade body cross section chord length B, blade body cross section maximum thickness W, blade body cross section axial width Xa, blade body cross section area A; the superposition rule of the characteristic cross sections is that each cross section has a continuous and smooth transition from the root end of the blade body to the top end of the blade body along the blade height direction, characterized in that, The root of the blade is a subsonic blade type, the middle is a transonic blade type, and the top is a supersonic blade type. The blade height Ld of the blade is 221 mm and the root diameter Dr is 400 mm. The relative value of the blade height Ld increases monotonically from 0.0 to 1.

0. Correspondingly, the blade installation angle C decreases monotonically from 74.03° to 21.74°. The relative change law of the blade cross-sectional area A from the root section to the top section decreases monotonically from 4.197 to 1.

0. The relative change law of the blade cross-sectional axial width Xa from the root section to the top section is The relative variation law of the blade section chord length B from the root section to the top section monotonically decreases from 1.273 to 1.0; the relative variation law of the blade section maximum thickness W from the root section to the top section monotonically decreases from 2.489 to 1.

0. The blade profile of the single blade is monotonically twisted along the height, and the relative value of its outlet geometric angle α1 decreases monotonically from 1.795 to 1.0 from the blade root to the blade tip along the height direction. The calculation process of the outlet geometric angle α1 is shown in the following formula (1): α1=sin -1 (O / T) (1) In formula 1, O is the width of the exit throat of the blade section, that is, the minimum distance between the steam outlet edge F of the blade profile and the back arc D of the adjacent blade section, and T is the circumferential installation distance of the profile sections of the same height of two adjacent single blades.

2. The last stage moving blade according to claim 1, characterized in that: The blade body is provided with a tie rod hole, and the height Lj of the center of the tie rod hole satisfies the relationship of 0.7≤Lj / Ld≤0.85; the diameter Φ of the tie rod hole satisfies the relationship of 7mm≤Φ≤10.5mm.

3. The last stage moving blade according to claim 2, characterized in that: The inner arc E and the back arc D of the blade body have a smooth thickness reinforcement area along the axial direction and the blade height direction of the tie rod hole in the area matching the tie rod hole.

4. The last stage moving blade according to claim 2, characterized in that: The invention also includes a loosening reinforcing bar, wherein the loosening reinforcing bar can pass through the reinforcing bar hole and match the reinforcing bar hole, and the diameter of the loosening reinforcing bar is Satisfies the relationship: The length L satisfies the relationship 2.7·T1≤L≤2.95·T1 or 5.7·T1≤L≤5.95·T1 or 11.7·T1≤L≤11.95·T1; the loose reinforcement forms an arc structure along the length L according to the radius R. The calculation process of the radius R is shown in the following formula (2): R=(Dr / 2+Lj) (2) In Formula 2, Dr is the blade root diameter, that is, the diameter of the circle where the root section of the blade body is located after the single blade is installed on the rotor, and Lj is the height position of the tie rod hole on the blade body.

5. The last stage moving blade according to claim 4, characterized in that: The loose reinforcement is radially divided into equal half reinforcements, and two half reinforcements can be matched with each other and pass through the reinforcement holes.

6. The last stage moving blade according to claim 5, characterized in that: The plurality of single blades surround the rotor and are evenly distributed on the outer circle of the rotor. The blade root is limited in the impeller groove on the outer circle of the rotor. The loose tie rod passes through the tie rod hole to connect the plurality of blade bodies. The loose tie rod surrounds the rotor to form an annular structure.

7. The last stage moving blade according to claim 6, characterized in that: A blade cascade channel is formed between two adjacent single blades, and the half tie bars on the same side cooperate with each other to form a half tie bar ring, and the two half tie bar rings on the opposite side can be combined to form a loose tie bar ring; in the same half tie bar ring, the adjacent half tie bar end faces cooperate in the middle of the blade cascade channel to form an intersection area, and an intersection gap Ga is arranged at the intersection area, and the intersection areas in the two half tie bar rings on the opposite side are arranged in different blade cascade channels.

8. The last stage moving blade according to claim 7, characterized in that: The end of the half tie rod is provided with a limiting portion which can be limited to the tie rod hole.

9. The last stage moving blade according to any one of claims 6 to 8, characterized in that: It also includes a rotor, wherein the blade root is an inclined four-tooth longitudinal tree-shaped blade root; the axial width Bg of the blade root satisfies the relationship: 90mm≤Bg≤150mm.

10. The last stage moving blade according to claim 9, characterized in that: The horizontal angle between the blade root centerline and the rotor centerline U axis is D1, and the angle D1 satisfies the relationship: 0°≤D1≤30°.

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