CN215057590U - Secondary and final blade of low-pressure stage group of large-scale air cooling steam turbine - Google Patents

Abstract

The application relates to the technical field of steam turbines, in particular to a low-pressure stage group penultimate blade of a large-scale air cooling steam turbine, which comprises a blade body, a blade root and a shroud band, wherein the top end of the blade body is connected with the shroud band, and the bottom end of the blade body is connected with the blade root; the two opposite sides of the blade body are provided with connecting parts for connecting two adjacent blades in the impeller together; the shroud ring is a self-locking shroud ring, and the gravity center of the shroud ring is coincided with the gravity center of the blade profile base stacking of the blades. Under operating speed, connecting portion and connecting portion between the adjacent blade, shroud ring and shroud ring are all laminated, the damping of system has been increased, the blade whole circle auto-lock has been reached, the vibration performance of blade has been improved, the dynamic stress of blade has been reduced, and most main point is that the focus of shroud ring coincides mutually with the profile basic pile focus of blade, make the mass distribution of shroud ring more even, the bulk strength is better, bear stress the minimum, further improve the security and the reliability of blade in the course of the work.

Description

Secondary and final blade of low-pressure stage group of large-scale air cooling steam turbine

Technical Field

The application relates to the technical field of steam turbines, in particular to a low-pressure stage set penultimate blade of a large-scale air cooling steam turbine.

Background

At present, the demand of the domestic petrochemical industry on large-scale air cooling turbines is continuously increased, and urgent requirements are put on the large-scale and high efficiency of the turbines. The air cooling unit is a typical variable working condition operation unit, and for the water cooling unit, the design backpressure of air cooling unit is high and the backpressure change range is big, and atmospheric environmental change scope is big, causes the blade to have to satisfy and can move under by the operating mode of blockking to the blast air operating mode, no matter in blast air operating mode or blockking operating mode, operating condition all is very abominable. The secondary-last-stage blade is an important link for connecting the last-stage blade and the high-pressure-stage blade and is a key part for determining the safety and the through-flow efficiency of the whole low-pressure-stage group, so that the safety and the reliability of the blade under all working conditions are urgently needed to be improved.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a large-scale air cooling steam turbine low-pressure stage group penultimate stage blade has solved the technical problem that the fail safe nature of blade under the full operating mode that urgently needs to improve that exists among the prior art to a certain extent.

The application provides a large-scale air cooling steam turbine low-pressure stage group penultimate stage blade includes: a blade body, a blade root and a shroud; the top end of the blade body is connected with the shroud band, and the bottom end of the blade body is connected with the blade root; the two opposite sides of the blade body are respectively provided with a connecting part for connecting two adjacent blades in the impeller together; the shroud ring is a self-locking shroud ring, and the gravity center of the shroud ring is coincided with the gravity center of the blade profile base stacking of the blades.

In the above technical solution, further, a cross section of the shroud ring along a direction perpendicular to a height direction of the blade body is arranged in a centrosymmetric manner with a center of gravity of the blade profile base stack of the blade body as a center.

In any of the above technical solutions, further, the shroud ring includes a first extending wall surface, a first bending wall surface, a first clamping wall surface, a second extending wall surface, a second bending wall surface, and a second clamping wall surface, which are connected in sequence, so as to form a closed structure;

wherein the first and second bent wall surfaces form an obtuse angle; the second extending wall surface and the first extending wall surface are both planes and are arranged in a central symmetry manner;

the second bending wall surface and the first bending wall surface are both planes and are arranged in a central symmetry manner; the second clamping wall surface and the first clamping wall surface are arranged in a central symmetry mode.

In any of the above technical solutions, further, the thickness range of the shroud ring is 9.5mm to 19.5 mm.

In any of the above technical solutions, further, the two connecting portions on two sides of the blade body are arranged in a central symmetry manner.

In any one of the above technical solutions, further, the connecting portion is frustum-shaped, and the connecting portion gradually expands and thickens toward the blade body.

In any of the above technical solutions, further, an angle at which the connecting portion gradually expands toward the blade body is 3 ° to 3.5 °.

In any of the above technical solutions, further, an end face of the connecting portion, which is far away from the blade body, is elliptical, an included angle between an axis of a long side of the ellipse and a horizontal reference line of the blade is 10 °, and a ratio of the long side to a short side of the ellipse is 1.8 or more and e0/e1 or less and 2.3 or less.

In any of the above technical solutions, further, the blade root is an arc vertical tree blade root.

In any of the above technical solutions, further, the blade body is a variable cross-section twisted blade body, and the geometric parameters from the bottom cross-section of the blade body to the top cross-section of the blade body are as follows: the height position ranges from 0mm to 354.5 mm; the cross-sectional area ranges from 1938.0165mm 2mm to 540.015mm 2; the maximum thickness range is 22.346 mm-9.077 mm; the range of the installation angle is 67.838-25.695 degrees; the thickness of the air outlet edge ranges from 1.7mm to 0.98 mm; the range of the chord length is 117.368 mm-101.892 mm; the axial width ranges from 108.347mm to 44.891 mm; the range of the ratio of pitch to chord length is: t/b is more than or equal to 0.2 and less than or equal to 0.9; the ratio of pitch to maximum thickness of the profile section ranges from: T/Dmax is more than or equal to 2.3 and less than or equal to 7.5; and/or

The back arc of the steam inlet side of the blade body is provided with a hardening part.

Compared with the prior art, the beneficial effect of this application is:

the application provides a large-scale air cooling steam turbine low-pressure stage group time last stage blade, self-locking shroud has, make the impeller that includes a plurality of this large-scale air cooling steam turbine low-pressure stage group time last stage blades, under operating speed, shroud and shroud between the adjacent blade laminate mutually, the system damping has been increased, the whole circle of auto-lock of blade has been reached, the vibration performance of blade has been improved, the dynamic stress of blade has been reduced, and the most important point is that the focus of shroud overlaps the focus mutually with the leaf profile base of blade, make the mass distribution of shroud more even, the bulk strength is better, bear stress the minimum, further improve security and the reliability of blade in the course of the work.

In addition, under the working rotating speed, two connecting parts between two adjacent blades are attached to each other, system damping is further increased, the vibration performance of the blades is improved, the dynamic stress of the blades is reduced, and the stability and the reliability of the operation of the blades are guaranteed.

Drawings

In order to more clearly illustrate the detailed description of the present application or the technical solutions in the prior art, the drawings needed to be used in the detailed description of the present application or the prior art description will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a schematic structural diagram of a last-stage blade of a low-pressure stage group of a large air-cooled steam turbine according to an embodiment of the present invention;

FIG. 2 is a schematic view of another structure of a last blade of a low-pressure stage group of a large air-cooled steam turbine according to an embodiment of the present invention;

FIG. 3 is a schematic structural diagram of a plurality of LSW low-pressure stage set penultimate blades assembled together according to an embodiment of the present invention;

fig. 4 is a schematic view of a blade-type stack according to an embodiment of the present application.

Reference numerals:

1-blade root, 2-blade body, 21-connecting part, 3-shroud band, 31-first extending wall surface, 32-first bending wall surface, 33-first clamping wall surface, 34-second extending wall surface, 35-second bending wall surface and 36-second clamping wall surface.

Detailed Description

The technical solutions of the present application will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are only some embodiments of the present application, but not all embodiments.

The components of the embodiments of the present application, generally described and illustrated in the figures herein, can be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present application, presented in the accompanying drawings, is not intended to limit the scope of the claimed application, but is merely representative of selected embodiments of the application.

All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.

Referring now to fig. 1-4, a description of a penultimate blade of a low-pressure stage group of a large air-cooled steam turbine according to some embodiments of the present application will be given.

Referring to fig. 1 to 3, an embodiment of the present application provides a penultimate blade of a low-pressure stage group of a large air-cooled steam turbine, including: a blade body 2, a blade root 1 and a shroud 3;

wherein, the top end of the blade body 2 is connected with the shroud ring 3, and the bottom end of the blade body 2 is connected with the blade root 1; two opposite sides of the blade body 2 are provided with connecting parts 21 respectively, so that two adjacent blades in the impeller are connected together;

the shroud ring 3 is a self-locking shroud ring 3, and the center of gravity of the shroud ring 3 coincides with the center of gravity of the blade profile base stack of the blade, and the most ideal structure is as described above, but of course, if the center of the shroud ring 3 does not coincide completely with the center of gravity of the blade profile base stack of the blade body 2, the difference may be small, and for example, the coincidence ratio of the two may be greater than or equal to 99.5%.

The application provides a large-scale air cooling steam turbine low-pressure stage group time last stage blade, self-locking shroud 3 has, make the impeller that includes a plurality of this large-scale air cooling steam turbine low-pressure stage group time last stage blades, under operating speed, shroud 3 between the adjacent blade is laminated with shroud 3 mutually, the system damping has been increased, the auto-lock of whole circle of blade has been realized, the vibration performance of blade has been improved, the dynamic stress of blade has been reduced, and the most important point is that shroud 3's focus overlaps mutually with the blade profile basic of blade and coincides, make shroud 3's mass distribution more even, the bulk strength is better, the bearing stress is minimum, further improve security and the reliability of blade in the course of the work.

In addition, under the operating speed, two connecting parts 21 between two adjacent blades are attached and interfered, so that the system damping is further increased, the vibration performance of the blades is improved, the dynamic stress of the blades is reduced, and the stability and the reliability of the operation of the blades are ensured.

And note that, the connecting portion 21 between the adjacent blades and the connecting portion 21, and the shroud 3 all have a gap of about 0.3mm, and the blades receive centrifugal force at the operating speed, and the blade body 2 generates a certain anti-twisting displacement, so that the connecting portion 21 between the adjacent blades and the connecting portion 21, and the shroud 3 are better attached.

In one embodiment of the present application, it is preferable that, as shown in fig. 2, the cross section of the shroud band 3 along the direction perpendicular to the height direction of the blade body 2 is arranged to be centrosymmetric around the center of gravity of the blade profile base stack of the blade body 2, which contributes to rationalization of the mass distribution of the shroud band 3, and the shroud band is regular in shape and convenient to manufacture.

In one embodiment of the present application, preferably, as shown in fig. 2, the shroud 3 includes a first extending wall 31, a first bending wall 32, a first clamping wall 33, a second extending wall 34, a second bending wall 35 and a second clamping wall 36 connected in sequence to form a closed structure;

wherein the first bending wall surface 32 and the second bending wall surface 35 form an obtuse angle; the second extending wall surface 34 and the first extending wall surface 31 are both planar and are arranged in central symmetry;

the second bending wall surface 35 and the first bending wall surface 32 are both planar and are arranged in central symmetry; the second clamping wall surface 36 is arranged in central symmetry with the first clamping wall surface 33.

Based on the above description, the shroud ring 3 is formed into a central symmetrical structure, which can meet the requirement that the gravity center of the shroud ring coincides with the gravity center of the blade profile base stack of the blade, so that the uniform mass distribution is ensured, the overall strength is better, the bearing stress is minimum, the safety and the reliability of the blade in the working process are further improved, the processing and the manufacturing are convenient, and the cost is reduced.

Preferably, as shown in fig. 1, the projection of the shroud 3 in the height direction of the blade body 2 completely covers the tip of the blade body 2.

In one embodiment of the present application, the thickness of the shroud 3 is preferably in the range of 9.5mm to 19.5mm, and different shroud thicknesses can be selected for blade tuning to meet different operating speed requirements.

In an embodiment of the present application, as shown in fig. 1, preferably, the two connecting portions 21 on two sides of the blade body 2 are arranged in a central symmetry manner, so that the connecting portions 21 of any two adjacent blades in the impeller can meet and interfere with each other during operation.

In an embodiment of the present application, preferably, as shown in fig. 1 to 3, the connecting portion 21 is in a frustum shape, and the connecting portion 21 gradually expands and thickens toward the blade body 2, that is, the root of the connecting portion 21 is thick, and the head of the connecting portion 21 is thin, so that the stress between the connecting portion 21 and the profile of the blade body 2 can be effectively reduced, the stress distribution of the joint surface is more uniform, and the strength of the connecting portion 21 itself is effectively improved.

Preferably, the angle of the connection part 21 gradually expanding towards the blade body 2 is 3 to 3.5 degrees, so that the requirement is met, and the processing and the manufacturing are convenient.

In one embodiment of the present application, preferably, as shown in fig. 1, the end surface of the connecting portion 21 away from the blade body 2 is oval, the included angle between the long side axis of the oval and the horizontal reference line of the blade is 10 °, and the long side-to-short side ratio of the oval is 1.8 ≦ e0/e1 ≦ 2.3.

The design ensures that the adjacent connecting parts 21 have good fitting effect when the blade works, and meanwhile, the connecting parts 21 are bent along the axial direction of the connecting parts to conform to the airflow, so that the flow loss caused by additionally installing the connecting parts 21 is reduced to a certain extent.

In an embodiment of the present application, preferably, as shown in fig. 1, the blade root 1 is an arc longitudinal tree-shaped blade root 1, so that the installation and the disassembly are convenient, and the safe and stable operation of the blade within 4200r/min can be ensured.

In one embodiment of the present application, the back arc of the steam inlet side of the blade body 2 is preferably provided with a hardened portion, as shown in fig. 1, to improve wear resistance and avoid long-term erosion by the air flow.

In one embodiment of the present application, preferably, as shown in fig. 1 and 4, the blade body 2 is a variable cross-section twisted blade body 2, and the geometrical parameters from the bottom section of the blade body 2 to the top section of the blade body 2 are: the height position ranges from 0mm to 354.5 mm; the cross-sectional area is in the range of 1938.0165mm²～540.015mm²(ii) a The maximum thickness range is 22.346 mm-9.077 mm; the range of the installation angle is 67.838-25.695 degrees; the thickness of the air outlet edge ranges from 1.7mm to 0.98 mm; the range of the chord length is 117.368 mm-101.892 mm; the axial width ranges from 108.347mm to 44.891 mm; the range of the ratio of pitch to chord length is: t/b is more than or equal to 0.2 and less than or equal to 0.9; the ratio of pitch to maximum thickness of the profile section ranges from: T/Dmax is more than or equal to 2.3 and less than or equal to 7.5, and the specific reference is given in the following table I.

Table one: geometric parameters of each section

Based on the structure, the secondary and final blades of the low-pressure stage group of the large-scale air cooling steam turbine are designed by adopting a ternary flow design means. The installation angle, the air outlet angle, the chord length, the thickness and the cross section area of the section of the blade body 2 and the shroud 3 are reasonably calculated and designed, so that the blade has good pneumatic performance, reliable strength requirements and reasonable frequency modulation range, meanwhile, the twist rule of the integral blade body 2 in the blade height direction is ensured, the blade is in monotonous smooth transition, and the pneumatic design and the twist rule of the blade body 2 conform to the three-dimensional flow theory. When the back pressure is 0.2bar and the outlet Mach number is 0.5, the reaction degree of the stage is 0.5, the pneumatic efficiency of the low-pressure stage group is about 83.0 percent, the maximum flow of the stage group is more than 260t/h, and the maximum operation rotating speed is 4200 r/min.

Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. The utility model provides a large-scale air cooling steam turbine low-pressure stage group penultimate stage blade which characterized in that includes: a blade body, a blade root and a shroud; the top end of the blade body is connected with the shroud band, and the bottom end of the blade body is connected with the blade root; the two opposite sides of the blade body are respectively provided with a connecting part for connecting two adjacent blades in the impeller together; the shroud ring is a self-locking shroud ring, and the gravity center of the shroud ring is coincided with the gravity center of the blade profile base stacking of the blades.

2. The LSI air-cooled steam turbine low-pressure stage group penultimate blade according to claim 1, wherein a cross section of the shroud in a direction perpendicular to a height direction of the blade body is arranged to be centrosymmetric about a centroid of a profile stacking of the blade body.

3. The LSI steam turbine low-pressure stage sub-last blade of claim 2, wherein the shroud includes a first extended wall, a first bent wall, a first clamping wall, a second extended wall, a second bent wall and a second clamping wall connected in series to form a closed structure;

wherein the first and second bent wall surfaces form an obtuse angle; the second extending wall surface and the first extending wall surface are both planes and are arranged in a central symmetry manner;

the second bending wall surface and the first bending wall surface are both planes and are arranged in a central symmetry manner; the second clamping wall surface and the first clamping wall surface are arranged in a central symmetry mode.

4. The LSI air-cooled steam turbine low-pressure stage group penultimate blade of claim 1, wherein the shroud thickness is in the range of 9.5mm to 19.5 mm.

5. The LSI air-cooled steam turbine low-pressure stage group penultimate blade according to claim 1, wherein two of said connecting portions on both sides of said blade body are arranged in central symmetry.

6. The LSI air-cooled steam turbine low-pressure stage group penultimate blade according to claim 1, wherein the connecting portion is in a frustum shape, and the connecting portion gradually expands and thickens toward the blade body.

7. The LSI air-cooled steam turbine low-pressure stage group penultimate blade according to claim 6, wherein the angle of the gradual expansion of the connecting portion toward the blade body is 3 ° to 3.5 °.

8. The last-stage blade of the low-pressure stage group of the large air-cooled steam turbine according to claim 1, wherein the end surface of the connecting portion, which is far from the blade body, is elliptical, the included angle between the long-side axis of the ellipse and the horizontal reference line of the blade is 10 °, and the long-side to short-side ratio of the ellipse is 1.8 ≤ e0/e1 ≤ 2.3.

9. The last-stage penultimate blade of a LSI steam turbine low-pressure stage group according to claim 1, wherein the blade root is a curved longitudinal tree blade root.

10. The LSI air-cooled steam turbine low pressure stage group penultimate blade of any one of claims 1 to 9, wherein the blade body is a variable cross-section twisted blade body and the geometrical parameters from a bottom section of the blade body to a top section of the blade body are: the height position ranges from 0mm to 354.5 mm; the cross-sectional area is in the range of 1938.0165mm²～540.015mm²(ii) a The maximum thickness range of the blade-shaped section is 22.346-9.077 mm; the range of the installation angle is 67.838-25.695 degrees; the thickness of the air outlet edge ranges from 1.7mm to 0.98 mm; the range of the chord length is 117.368 mm-101.892 mm; the axial width is in the range of 108.347mm-44.891 mm; the range of the ratio of pitch to chord length is: t/b is more than or equal to 0.2 and less than or equal to 0.9; the ratio of pitch to maximum thickness of the profile section ranges from: T/Dmax is more than or equal to 2.3 and less than or equal to 7.5; and/or

The back arc of the steam inlet side of the blade body is provided with a hardening part.

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