JP5758243B2 - Stator blades and steam turbines - Google Patents

Description

  The present invention relates to a stationary blade used in a steam turbine, and a steam turbine including the stationary blade.

  In recent years, in order to reduce the weight, a steam turbine including a stationary blade having a hollow structure inside is known. In addition, in order to improve the performance of the stationary blade, a technology has been proposed in which a slit is provided to communicate the interior and exterior of the stationary blade, and water droplets adhering to the surface of the stationary blade are taken in and removed (for example, patents) Reference 1). The water thus taken into the interior is discharged toward the shroud connected to the stationary blade and discharged.

  Depending on the exterior shape (geometrical shape) and mass of the steam blade of such a steam turbine, the environment around the stationary blade at the time of turbine operation (for example, the flow velocity and mass of steam passing through the stationary blade), Self-excited vibration (flutter) may occur. In particular, it is known that self-excited vibration is likely to occur when the mass of the stationary blade is small or when the blade height (the entire length of the blade) is long. Furthermore, a stationary blade having a hollow structure inside (hereinafter referred to as “hollow stationary blade”) is lighter than a stationary blade having a solid structure inside (hereinafter referred to as “solid stationary blade”). It becomes. Therefore, since the self-excited vibration is more likely to occur in the hollow stationary blade than in the solid stationary blade, it is necessary to suppress this.

  In order to suppress such self-excited vibration, a technique for attenuating vibration generated in the stationary blade by providing a damping mechanism (damper) at the joint between the stationary blade and the shroud has been proposed (for example, Patent Documents). 2).

  FIG. 8 shows an example of a stationary blade provided with such a damping structure. FIG. 8A is a cross-sectional view of the main part of the stationary blade, and FIG. 8B is a side view of the main part of the stationary blade. is there.

  In the figure, the stationary blade 1 has a ventral member 2 mainly constituting the ventral side and a dorsal member 3 mainly constituting the dorsal side. Further, the abdominal member 2 and the dorsal member 3 are obtained by bending metal plate-like members in different warping directions and joining the vicinity of both edges by welding. The abdomen side member 2 is warped so that the surface side becomes the abdomen surface 4 of the stationary blade 1. Further, the back member 3 is warped so that the surface side is the back surface 5 of the stationary blade 1. Further, the abdominal member 2 and the back member 3 have a hollow structure by making their warpage different, and a cavity 6 is formed in the interior.

  The hollow portion 6 is provided with an arcuate leaf spring 7 which is welded and fixed to the back surface 2a of the ventral member 2 with the central portion as a base portion 7a. In addition, the cavity 6 has, for example, slits 2 b and 2 c formed in the ventral member 2 so that the inside (cavity 6) and the outside of the stationary blade 1 communicate with each other, and water droplets attached to the surface of the stationary blade 1. Is taken inside and removed.

  The arcuate leaf spring 7 is formed with inclined connection portions 7d and 7e from the base portion 7a to the end portions 7b and 7c toward the back side member 3 from the abdominal side member 2, and the end portions 7b and 7c are connected to the back side member 3. It is made to contact | abut to the back surface 3c.

Japanese Patent Laid-Open No. 11-336503 JP 2008-133825 A

  By the way, in the stationary blade 1 using the arched leaf spring 7 as described above, the central portion of the arched leaf spring 7 is the base portion 7a, and both ends thereof are in contact with the back surface 3c of the back side member 3. Therefore, the spring pressure is set so as to be applied to both the steam inlet side (indicated by the arrow Q) of the stationary blade 1 and the outlet side. The steam inlet side is the upstream side of the stationary blade 1 in the rectifying direction, and the steam outlet side is the downstream side of the stationary blade 1 in the rectifying direction.

  On the other hand, since the load applied to the stationary blade 1 with the passage of steam is larger on the steam outlet side, it is desirable to concentrate the damper function on the outlet side as much as possible.

  However, in the above-described bow-shaped leaf spring 7, the steam outlet side is sufficiently damped because both the steam inlet side and the outlet side of the stationary blade 1 are in contact with the back surface 3 c with substantially the same area. There was a problem of being unable to do so. Also, if the damping function between the steam inlet side and the outlet side is unbalanced, the contact state between the both ends 7b, 7c and the back surface 3c is likely to be point contact or line contact due to generation of vibration due to insufficient damping. There was a problem that the contact area could not be secured, causing further vibration.

  Moreover, in the bow-shaped leaf spring 7, since the two ends 7b and 7c are brought into contact with the back surface 3c, not only the whole leaf spring is increased in size but also the three portions including the base portion 7a of the central portion. In combination with the need to make surface contact with the rear surfaces 2a and 3a, it becomes a dedicated product that changes the spring pressure, shape, etc. for each exterior shape and mass of the stationary blade 1, making it difficult to share and general purpose There was also a problem of inferiority.

  Therefore, the present invention has been made in view of the above, and can suppress self-excited vibration with a simple configuration, and can easily and stably ensure its damping function, and further improve versatility. It is an object of the present invention to provide a stationary blade and a steam turbine that can be used.

In order to solve the above problems, the present invention proposes the following means.
That is, the stator blade according to the present invention includes a stator blade body in which a cavity portion is defined by the back surfaces of the abdominal side portion and the back side portion, and an axis that is disposed in the cavity portion and extends along the back surface. And a torsion plate spring member that applies a pressing force to each of the back surfaces by being twisted.

  According to such a configuration, the self-excited vibration can be suppressed with a simple configuration, the damping function thereof can be easily and stably secured, and versatility can be improved.

  The torsion plate spring member is disposed in the hollow portion in a state where the twist is returned, and applies a pressing force to each back surface by a restoring force based on the torsion.

  According to such a configuration, the spring pressure can be set with a simple configuration, and it is possible to cope with the outer shape and mass of the stationary blade only by setting the spring pressure.

  The torsion plate spring member is disposed in the cavity so that the surface thereof is along the back surface.

  According to such a configuration, the spring pressure can be evenly applied.

  The torsion plate-like spring member is characterized in that the axis is arranged along a blade height direction of the stationary blade body or a direction intersecting with the blade height direction.

  According to such a configuration, it is possible to further easily cope with the outer shape and mass of the stationary blade.

  The steam turbine according to the present invention is characterized in that the stationary blades are arranged at predetermined intervals in the circumferential direction of the rotor shaft.

  According to such a configuration, the self-excited vibration can be suppressed with a simple configuration, the damping function thereof can be easily and stably secured, and versatility can be improved.

  The stationary blade body is formed with a slit for guiding water droplets from the surface side to the inside of the cavity.

  According to such a configuration, water droplets adhering to the surface of the stationary blade body can be taken into the cavity and removed.

  The stationary blade and the steam turbine of the present invention can suppress self-excited vibration with a simple configuration, and can easily and stably secure the damping function, and can improve versatility.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the schematic structure of a steam turbine, which shows the steam turbine carrying the stationary blade which concerns on one Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external perspective view of a main part of a steam turbine according to an embodiment of the present invention, as viewed from the low-pressure final stage side. It is the enlarged view which showed the stationary blade which concerns on one Embodiment of this invention, and looked at the stationary blade from the back side. 1 shows a stationary blade according to an embodiment of the present invention, in which (A) is a cross-sectional view showing an airfoil shape of the stationary blade, and (B) is a front view of the stationary blade. The twist plate-like spring member used for the stationary blade which concerns on one Embodiment of this invention is shown, (A) is a perspective view of the use condition of a torsion plate-like spring member, (B) is the twist state of the torsion plate-like spring member. It is a perspective view. The twist plate-shaped spring member used for the stationary blade which concerns on one Embodiment of this invention is shown, (A) is explanatory drawing of the state which has arrange | positioned the twist plate-shaped spring along the average curvature line of a stationary blade, (B) is It is explanatory drawing of the state which has arrange | positioned the twisted plate-shaped spring so that it may cross | intersect the average curvature line of a stationary blade. The other example of arrangement | positioning of the torsion plate-like spring member used for the stator blade which concerns on one Embodiment of this invention is shown, (A) is explanatory drawing of the example of arrangement | positioning of a horizontal state, (B) is description of the example of arrangement | positioning of an inclination state. (C) is explanatory drawing of the example of multiple arrangement | positioning of a horizontal orientation, (D) is explanatory drawing of the example of multiple arrangement | positioning of an inclination state. A conventional stator blade is shown, (A) is a sectional view showing an airfoil shape of the stator blade, and (B) is a side view of a main part of the stator blade.

  Next, a stationary blade and a steam turbine according to an embodiment of the present invention will be described with reference to the drawings. The following examples are preferred specific examples of the stationary blades and steam turbines of the present invention, and may have various technically preferable limitations. However, the technical scope of the present invention is particularly limited to the present invention. Unless stated to limit the invention, it is not limited to these embodiments. In addition, the constituent elements in the embodiments shown below can be appropriately replaced with existing constituent elements and the like, and various variations including combinations with other existing constituent elements are possible. Therefore, the description of the embodiment described below does not limit the contents of the invention described in the claims.

  FIG. 1 is an explanatory view schematically showing a schematic configuration of a steam turbine equipped with a stationary blade according to an embodiment of the present invention, and FIG. 2 is a view of the steam turbine showing an embodiment of the present invention from the low-pressure final stage side. FIG. 3 is an enlarged perspective view of a stationary blade showing an embodiment of the present invention viewed from the back side, FIG. 4 shows a stationary blade according to an embodiment of the present invention, and FIG. FIG. 4B is a front view of the stationary blade, FIG. 5 shows a torsion plate spring member used for the stationary blade according to the embodiment of the present invention, and FIG. 5A is a perspective view of the torsion plate spring member in use, FIG. 5B is a perspective view of the torsion plate spring member in a twist state, and FIG. 6 is a torsion blade used in the stationary blade according to the embodiment of the present invention. FIG. 6A shows a plate-like spring member, FIG. 6A is an explanatory view showing a state in which a twisted plate-like spring is arranged along the average warp line of the stationary blade, and FIG. 6B shows the average warp line of the stationary blade. By intersecting an explanatory view of a state of arranging the torsion plate spring.

  As shown in FIG. 1, a steam turbine 10 according to the present embodiment is a low-pressure steam turbine used in, for example, a nuclear power plant, and a steam generator 11 that generates high-pressure steam and a high-pressure from the steam generator 11. The high pressure steam turbine 12 to which the steam of the steam is directly supplied, the moisture separation heater 13 for separating and heating the steam moisture from the steam generator 11 and the high pressure steam turbine 12, and the low pressure from the moisture separation heater 13 A low-pressure steam turbine 10 to which the steam is supplied is provided. Hereinafter, in the present embodiment, the low-pressure steam turbine 10 that receives supply of steam from the moisture separation heater 13 as the steam turbine 10 will be described.

  In the low-pressure steam turbine 10, the steam from the moisture separator / heater 13 is supplied to the steam inlet 14, and the steam passage 15 formed in the low-pressure steam turbine 10 passes through the axial direction of the rotor shaft 16 (arrow A in the figure). Flows along). In the steam passage 15, the moving blades 17 and the stationary blades 18 are alternately arranged, and the low-pressure steam turbine 10 generates kinetic energy by the pressure drop in the stationary blades 18, and this is converted into rotational torque by the moving blades 17. It has been converted. As a result, the rotor shaft 16 coupled with the moving blade 17 rotates by the rotational torque converted by the moving blade 17.

  As shown in FIGS. 1 to 3, the stationary blade 18 has an inner end 18 a in the radial direction (indicated by an arrow R in the drawing) of the rotor shaft 16 at the shroud 19 and an outer end 18 b in the radial direction at the blade root ring 20. Are connected by welding (the welded portion is indicated by reference numeral 21 in FIG. 3).

  As shown in FIG. 1, the moving blade 17 and the stationary blade 18 are paired and one step 22 is arranged as many as necessary. Further, the stage 18 is configured such that the blade heights of the rotor blades 17 and the stationary blades 18 (the blade lengths in the direction substantially perpendicular to the rotor shaft 16) increase as the steam passage 15 moves from the upstream side to the downstream side. Has been. The stage 22 on the most downstream side of the steam passage 15 is referred to as a “low pressure final stage”. The stationary blade 18 of the low-pressure final stage 22 has a particularly long blade height compared to the stationary blade 18 in the upstream stage 22. In the low-pressure final stage 22, a plurality of stationary blades 18 are arranged at a predetermined interval in the circumferential direction of the rotor shaft 16 (indicated by an arrow Q in the figure) as shown in FIGS. Is forming.

  As shown in FIG. 4A, the stationary blade 18 includes a ventral member 24 that mainly configures the ventral side, and a dorsal member 25 that mainly configures the dorsal side. The abdominal member 24 and the dorsal member 25 are made by bending metal plate-like members in different warping directions, respectively, and bending the metal plate-like members in different warping directions. By joining the vicinity of the edge along the edge by welding, an exterior shape as the stationary blade body is formed. In the present embodiment, the leading edge portion (indicated by arrow P indicates the inflow direction of steam) located on the steam inlet side is TIG welding (reference numeral 26), and the trailing edge portion located on the steam outlet side is a laser. They are joined by welding (reference numeral 27). The abdomen side member 24 is warped so that the surface side becomes the abdomen surface 28 of the stationary blade 18. Further, the back member 25 is warped so that the surface side is the back surface 29 of the stationary blade 18. Furthermore, the abdominal member 24 and the dorsal member 25 form a hollow portion 30 with a hollow structure inside by making the curvature of the warpage different. That is, the cavity 30 extending along the blade height direction is formed between the back surface 24 c of the abdominal member 24 and the back surface 25 a of the back member 25. In addition, inside the stationary blade 18, the inner surface of the blade is formed by the back surface 24 c of the abdominal member 24 and the back surface 25 a of the back member 25. The steam inlet side is the upstream side of the stationary blade 18 in the rectifying direction, and the steam outlet side is the downstream side of the stationary blade 18 in the rectifying direction.

The ventral member 24 and the back member 25 extend along the blade height direction over substantially the same length. The ventral member 24 includes a plurality of slits 24 a on the front edge side and slits 24 b on the rear edge side along the radial direction R.
The “blade height direction” is a direction perpendicular to the airfoil cross section (transverse cross section parallel to the axis of the rotor shaft 16) shown in FIG. It is. In addition, slits substantially the same as the slits 24 a and 24 b can be formed in the back member 25. Furthermore, the shapes and lengths of the slits 24a and 24b are arbitrary.

  Thus, in the stationary blade 18 of the present embodiment, the ventral member 24 constitutes the ventral side of the cavity portion 30 of the stationary blade 18, and the back member 25 is on the back side of the cavity portion 30 of the stationary blade 18. Is configured.

  The cavity 30 formed inside the stationary blade 18 communicates with the outside of the stationary blade 18 through slits 24 a and 24 b formed in the ventral member 24. In the stationary blade 18 in which the cavity 30 and the slits 24a and 24b are formed, the water adhering to the abdominal surface 28 moves, for example, on the abdominal surface 28 under the vapor pressure, and is indicated by an arrow W in FIG. Thus, it can flow into the cavity 30 from the slits 24a and 24b.

  The water taken into the cavity 30 flows toward the shroud 19. As shown in FIG. 3, the shroud 19 is formed with an opening 31 communicating with the cavity 30 of the stationary blade 18. Water in the cavity 30 is discharged from the opening 31 as indicated by an arrow E. It is possible.

  Thus, the hollow stationary blade 18 having the hollow portion 30 therein has a relatively low natural frequency as compared with the solid stationary blade having no hollow portion 30 therein, and the low-pressure steam turbine 10 During operation, self-excited vibration (flutter) is likely to occur. When the self-excited vibration occurs, the stationary blade 18 is bent or twisted due to elastic deformation, and a relative position variation occurs between the abdominal member 24 and the back member 25 of the stationary blade 18.

  In order to attenuate this relative positional variation, the stationary blade 18 according to the present embodiment is provided with a twisted plate-like spring member 32 in the cavity 30, and when the stationary blade 18 is elastically deformed, the twisted plate As shown in FIG. 4 (A), the shaped spring member 32 is disposed along the blade height direction, and suppresses self-excited vibration by the spring pressure due to the torsional restoring force.

  Specifically, as shown in FIG. 5A, the torsion plate spring member 32 includes a plate spring main body 33 made of a metal plate and supported portions 34 and 35 provided at both ends of the plate spring main body 33. As shown in FIG. 5 (B), the leaf spring body 33 is twisted around the axis, and this is disposed in the cavity 30 in a state before twisting against the spring pressure generated by the twist. A spring pressure can be applied to the stationary blade 18 by a restoring force in the twisting direction (twisting restoring force).

  The shroud 19 and the blade root ring 20 are provided with a pair of support portions 36 and 37 that sandwich the supported portions 34 and 35. The support portions 36 and 37 may be formed on the back surface 24c of the ventral member 24 and the back surface 25a of the back member 25.

  When the stationary blade 18 is elastically deformed by the spring pressure of the torsion plate spring member 32 and a relative positional variation occurs between the back surface 24c of the abdominal member 24 and the back surface 25a of the back member 25, this spring pressure is generated. The dynamic frictional force corresponding to the size can be applied.

  During operation of the low-pressure steam turbine 10, depending on the operating conditions, self-excited vibration may occur in the stationary blade 18, and the stationary blade 18 may try to elastically deform.

  At this time, the torsion plate spring member 32 generates a spring pressure in a direction that suppresses relative positional fluctuation between the ventral member 24 and the dorsal member 25. This spring pressure attenuates the relative positional fluctuation between the ventral member 24 and the dorsal member 25. As a result, the self-excited vibration generated in the stationary blade 18 can be suppressed.

  By the way, in the said embodiment, as shown to FIG. 4 (A) and FIG. 6 (A), the torsion plate-shaped spring member 32 makes the leaf | plate spring main body 33 the back surface of the belly side member 24 (back side member 25). Although the example arranged along 24c (along the airfoil center line C) has been shown, for example, as shown in FIG. 6B, it may be arranged in a direction orthogonal to the airfoil center line C. good. Moreover, as shown to FIG. 7 (A), you may arrange | position to the horizontal state which makes the direction in alignment with the airfoil centerline C a longitudinal direction, and as shown in FIG. Further, as shown in FIG. 7C, the upper side and the lower side may be arranged in a horizontal state, or as shown in FIG. 7D, a plurality may be arranged in an inclined state in the intersecting direction.

  Thus, the plate spring main body 33 made of a metal plate and the supported portions 34 and 35 provided at both ends of the plate spring main body 33 are provided. As shown in FIG. By twisting the main body 33 and disposing it in the cavity 30 in a state before twisting against the spring pressure generated by the twisting, the spring pressure is applied to the stationary blade 18 by the restoring force in this twisting direction (torsion restoring force). Can be granted.

  In addition, the cavity 30 is defined by the back surfaces 24c and 25a of the abdominal member 24 and the back member 25, and is arranged in the cavity 30 and twisted around the axis extending along the back surfaces 24c and 25a. By providing the torsion plate-like spring member 32 for applying a pressing force to the back surfaces 24c and 25a, it is possible to suppress self-excited vibration with a simple configuration and to easily and stably secure the damping function. In addition, versatility can be improved.

  Further, the torsion plate spring member 32 is disposed in the cavity 30 in a state where the twist is returned, and by applying a pressing force to each of the back surfaces 24c and 25a by the restoring force, the spring pressure is applied with a simple configuration. It is possible to set the outer shape and mass of the stationary blade 18 only by setting the spring pressure.

  Further, the torsional plate spring member 32 is provided in the cavity 30 so that the surface of the plate spring main body 33 is along the back surfaces 24c and 25a, so that the spring pressure can be evenly applied.

  The torsion plate-like spring member 32 is arranged along the blade height direction of the stationary blade 18 or the direction intersecting with the blade height direction, thereby further supporting the outer shape and mass of the stationary blade 18. It can be made easier.

DESCRIPTION OF SYMBOLS 10 ... Steam turbine 18 ... Stator blade 24 ... Abdominal side member (abdominal side part)
24a ... Slit 24b ... Slit 24c ... Back side 25 ... Back side member (back side part)
25a ... Back 30 ... Cavity 32 ... Twist plate spring member

Claims (6)

A stationary blade body in which a cavity is defined by the back surfaces of the ventral side and the back side; and
A stationary blade, comprising: a torsion plate spring member that is arranged in the hollow portion and twists about an axis extending along the back surface to apply a pressing force to each back surface.   The twisted plate-like spring member is disposed in the hollow portion in a state in which the twist is returned, and applies a pressing force to each of the back surfaces by a restoring force based on the twist. Static wing. The stationary blade according to claim 1 or 2, wherein the torsion plate spring member is disposed in the hollow portion so that a surface thereof is along the back surface.   The twisted plate-like spring member is arranged along the direction in which the axis line intersects the blade height direction of the stationary blade body or the blade height direction. The stator blade according to Item.   A steam turbine, wherein the stationary blades according to any one of claims 1 to 4 are arranged at a predetermined interval in a circumferential direction of the rotor shaft.   The steam turbine according to claim 5, wherein a slit for guiding water droplets from the surface side to the inside of the hollow portion is formed in the stationary blade body.

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