JP5984653B2 - Steam turbine - Google Patents

Description

  The present invention relates to a steam turbine.

  For steam turbines, the stationary blades have been made longer and more compact, and the aspect ratio has been increased for the purpose of higher efficiency and lower cost. For example, in order to shorten the bearing interval in the steam turbine, the axial length (blade width) of the stationary blade is reduced in the low-pressure final stage of the stationary blade while keeping the blade height constant.

In addition, the stationary blade has a hollow structure in order to reduce the weight, and in order to collect the drain in the steam flow path, a structure in which a slit for introducing the drain into the hollow portion of the stationary blade is formed is adopted. There are many.
Due to these structures, the vibration strength of the stationary blade is reduced, and the development of a stationary blade structure that satisfies the vibration strength is an issue.

  One of the structures aimed at suppressing the vibration of the stationary blade is a hollow damper stationary blade structure that adds structural damping by providing a damper in the hollow portion of the stationary blade (see, for example, Patent Document 1).

JP 2008-133825 A

  By the way, the steam turbine has a stationary blade ring including an outer peripheral ring that connects ends on the outer peripheral side of the stationary blade and an inner peripheral ring that connects ends on the inner peripheral side of the stationary blade. The stator blade is mounted on the stator blade ring and then incorporated into the inner casing, and an additional damping structure effective for the vibration mode mainly composed of the stator blade ring is desired.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a steam turbine capable of effectively adding damping to a stator blade ring and reducing vibration of the stator blade or the stator blade ring. It is to provide.

In order to achieve the above object, the present invention provides the following means.
A steam turbine according to the present invention is provided with a plurality of stator blades having a hollow structure in which a plurality of drain turbines are provided at intervals in the circumferential direction of the rotating shaft, and drain recovery holes for recovering drain in the steam flow path are formed in communication with the inside and outside. An inner ring that connects radially inner sides of a plurality of stationary blades in the circumferential direction, and an inner space extending in the circumferential direction is formed inside the inner ring, and the drain is guided in the inner space. A partition plate that is divided into a first chamber and a second chamber separated from the first chamber, and a plurality of damping members filled in the second chamber are provided.

  According to the above configuration, when vibration is generated in the inner ring that connects the plurality of stationary blades, the damping members collide with each other to generate friction energy, and friction damping occurs. Thereby, damping is added and the vibration of the stationary blade can be reduced.

  In the steam turbine, it is preferable that the second chamber is defined on the radially inner side of the inner ring.

  According to the above configuration, the collected drain is directly guided to the first chamber, and the second chamber filled with the damping member does not interfere with the drain recovery, so that the drain recovery efficiency can be improved. it can.

In the steam turbine, the damping member is preferably a metal sphere.
According to the said structure, the adjustment with respect to the vibration mode of a stationary blade or an inner peripheral ring becomes easy by the weight which a metal bulb | ball has, and the shape which is easy to friction.

  According to the present invention, when vibration is generated in an inner ring that connects a plurality of stationary blades, the damping members collide with each other to generate friction energy, and friction damping occurs. Thereby, damping is added and the vibration of the stationary blade can be reduced.

It is a schematic sectional drawing which shows the steam turbine of embodiment of this invention. It is a figure which shows the detail of the stationary blade of the last stage of the steam turbine of embodiment of this invention. It is sectional drawing which shows the detail of the inner peripheral ring of embodiment of this invention. It is sectional drawing which shows the modification of the inner peripheral ring of embodiment of this invention. It is sectional drawing which shows the modification of the inner peripheral ring of embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in FIG. 1, the steam turbine 1 according to the present embodiment is provided with a casing 10, a regulating valve 20 that adjusts the amount and pressure of the steam S flowing into the casing 10, and an inward rotation of the casing 10. A shaft body (rotor) 30 that transmits power to a machine (not shown) such as a generator, a stationary blade 40 held by the casing 10, a moving blade 50 provided on the shaft body 30, and a shaft body 30. And a bearing portion 60 that is supported so as to be rotatable around.

  The casing 10 is formed so as to hermetically seal the inner space thereof, and a main body part 11 that defines a flow path of the steam S, and a ring-shaped outer peripheral ring 12 that is firmly fixed to the inner wall surface of the main body part 11. (Outside shroud).

  A plurality of regulating valves 20 are attached to the inside of the main body 11 of the casing 10. The regulating valve chamber 21 into which the steam S flows from a boiler (not shown), the valve body 22, the valve seat 23, and the steam chamber 24. It has. In this regulating valve 20, the steam passage is opened when the valve body 22 is separated from the valve seat 23, whereby the steam S flows into the internal space of the casing 10 through the steam chamber 24.

The shaft body 30 includes a rotating shaft 31 and a plurality of disks 32 extending outward from the outer periphery of the rotating shaft 31 in the radial direction (hereinafter, the radial direction of the rotating shaft 31 is simply referred to as a radial direction). The shaft body 30 transmits rotational energy to a machine such as a generator (not shown).
Further, the bearing portion 60 includes a journal bearing device 61 and a thrust bearing device 62, and supports the shaft body 30 inserted into the main body portion 11 of the casing 10 so as to be rotatable outside the main body portion 11.

  A plurality of the stationary blades 40 are provided radially at intervals in the circumferential direction of the shaft body 30 to form an annular stationary blade group, and are respectively held by the outer circumferential ring 12 described above. That is, each stationary blade 40 extends radially inward from the outer peripheral ring 12.

  The leading end of the stationary blade 40 in the extending direction is connected by an inner peripheral ring 41 (inner shroud). The inner ring 41 is formed in a ring shape so as to connect a plurality of stator blades 40 forming the same annular stator blade group in the circumferential direction. The shaft body 30 is inserted through the inner ring 41, but the inner ring 41 is disposed between the shaft body 30 and a radial gap.

  The annular stator blade group composed of a plurality of stator blades 40 is formed at six intervals in the extending direction of the rotation axis of the casing 10 and the shaft body 30 (hereinafter referred to as the axial direction). Is converted into velocity energy and guided to the moving blade 50 adjacent to the downstream side in the axial direction. The number of vanes of the stationary blade 40 is not limited to the above six.

The rotor blade 50 is firmly attached to the outer peripheral portion of the disk 32 constituting the shaft body 30 and extends radially outward from the shaft body 30. A large number of the moving blades 50 are arranged radially on the downstream side of each annular stationary blade group to constitute the annular moving blade group.
The above-described annular stationary blade group and the above-described annular moving blade group are set in one stage. That is, the steam turbine 1 is configured in six stages. Note that the number of stages of the annular stator blade group and the annular rotor blade group is not limited to the above six stages.

  As shown in FIG. 2, the stationary blade 40 has a hollow structure, and a slit 43 extending in the longitudinal direction (blade height direction) of the stationary blade 40 is formed at least on the ventral side of the stationary blade 40. Yes. The slit 43 is formed from the surface of the stationary blade 40 to the hollow portion 42 so that the outside of the stationary blade 40 and the hollow portion 42 inside the stationary blade communicate with each other through the slit 43, and the drain in the steam channel It functions as a drain recovery hole for recovering water.

  In the steam turbine 1 of the present embodiment, at least the inner peripheral ring 41A connected to the final stage stationary blade 40 has a hollow structure, and an internal space 44 is formed therein. The internal space 44 is formed over the circumferential direction of the rotating shaft 31 (hereinafter referred to as the circumferential direction).

As shown in FIG. 3, the inner peripheral ring 41 </ b> A includes a connection surface 45 connected to the stationary blade 40, a cylindrical bottom surface 46 having a surface parallel to the outer peripheral surface of the rotary shaft 31, and a bottom surface 46. It has a first side surface 47 and a second side surface 48 that connect the connection surface 45.
An opening 49 that communicates with the hollow portion 42 of the stationary blade 40 is formed in the connection surface 45. A plurality of openings 49 are provided for each stationary blade 40.

  The internal space 44 is partitioned into a first chamber 71 and a second chamber 72 divided from the first chamber 71 by a partition plate 70. The partition plate 70 is a cylindrical plate member formed by a surface parallel to the outer peripheral surface of the rotating shaft 31, and one end and the other end thereof are connected to the first side surface 47 and the second side surface 48. Specifically, one end of the partition plate 70 is connected to the substantially central portion of the second side surface 48 in the radial direction.

  The second chamber 72 of this embodiment is filled with a large number of metal balls 73. When the inner ring 41A vibrates, the metal spheres 73 are filled to such an extent that the metal spheres 73 can move to some extent and rub against each other while contacting the adjacent metal spheres 73 on the entire circumference. That is, the metal balls 73 act as a damping member that generates frictional energy by colliding with each other and generates frictional damping.

Next, the operation of the steam turbine 1 of the present embodiment will be described.
The steam turbine 1 operates by introducing steam S from the boiler into the casing 10 via the regulating valve 20. That is, the steam S flowing into the casing 10 passes through the flow path between the stationary blades 40 in each stage and is supplied to the moving blade 50. Then, when the fluid pressure of the steam S acts on the rotor blade 50, the shaft body 30 rotates with the rotation of the rotor blade 50. As a result, the machine connected to the shaft body 30 is driven.

  The steam sent to the steam turbine 1 of the present embodiment is superheated steam, and the degree of superheat decreases as the pressure drops and becomes dry and saturated, and further expands and becomes wet steam containing moisture (drain). Become.

In the low-pressure stage that is the wet steam region in the steam turbine 1 of the present embodiment, among the water droplets in the wet steam or the water droplets scattered from the moving blade 50, the fine water droplets are flowed downstream together with the steam because they are lightweight, and are coarse. Since the water droplets are heavy, they receive a large amount of centrifugal force and are scattered to the casing 10 side, and the medium-sized water droplets are adjacent to the moving blades 50 due to the inertia of the steam flow and the rotation of the moving blades 50 and are located downstream. 40 is reached.
The water droplets that have reached the stationary blade 40 flow into the hollow portion of the stationary blade 40 through the slit 43, and then are collected as drainage in the inner space 44 of the inner peripheral ring 41 through the opening 49.

On the other hand, when the stationary blade 40 vibrates during the operation of the steam turbine 1 and the inner ring 41 vibrates accordingly, the metal balls 73 in the second chamber 72 rub against each other inside, and vibration energy is reduced to metal. It is absorbed as movement of the sphere 73 and frictional energy.
The material, amount, size, and the like of the metal sphere 73 are appropriately adjusted according to the specifications of the stationary blade 40 and the actual vibration state.

  According to the above-described embodiment, when vibration is generated in the stationary blade 40 or the inner peripheral ring 41, the metal balls 73 that are damping members collide with each other, thereby generating friction energy and friction damping. Thereby, damping is added and the vibration of the stationary blade 40 or the inner peripheral ring 41 can be reduced.

  In addition, since the drain collected through the slit 43 is directly guided to the first chamber 71 and the second chamber 72 filled with the metal ball 73 does not interfere with the drain recovery, the drain recovery efficiency is improved. Can be improved.

  Furthermore, the weight of the metal sphere 73 and the shape that easily rubs can easily adjust the vibration mode of the stationary blade 40 and the inner ring 41.

  In the embodiment described above, the partition plate 70 is provided across the first side surface 47 and the second side surface 48 so that the internal space 44 is provided in the entire axial direction. However, the present invention is not limited to this. For example, as shown in FIG. 4, the partition plate 70 may be formed so that the metal sphere 73 is held in a part in the axial direction. In this way, by changing the arrangement of the metal spheres 73, adjustments according to the vibration state of the stationary blade 40 can be performed.

Further, as shown in FIG. 5, the metal sphere 73 may be filled not in the second chamber 72 but in the first chamber 71. This configuration is effective when a large number of metal balls 73, which are members for damping, are desired to be brought closer to the stationary blade 40. In this configuration, it is necessary to construct a hole 74 (slit) in a part of the partition plate 70 as a drain passage.

  The technical scope of the present invention is not limited to the above-described embodiments, and includes those in which various modifications are made to the above-described embodiments without departing from the spirit of the present invention. In other words, the configuration described in the above-described embodiment is an example, and can be appropriately changed.

For example, the damping member filled in the internal space 44 is not limited to the metal ball 73, and similar metal pieces having shapes that easily move and rub against each other may be used. Further, the material is not limited to metal, and may be a resin such as ceramic.
Moreover, in the said embodiment, although the structure which fills the metal sphere 73 with the inner peripheral ring 41A of the last stage of the stationary blade 40 was shown, the metal sphere 73 is attached to the inner peripheral ring 41 which connects the stator blades 40 other than the last stage. It is good also as a structure filled up.
Moreover, in the said embodiment, in order to collect | recover drains, it was set as the structure which provided the slit 43 extended in a blade | wing height direction on the surface of the stationary blade 40, However, Not only a slit but the stationary blade 40 is provided via several holes. It is good also as a structure which introduces a drain into the hollow part 42 of this.

1 Steam Turbine 31 Rotating Shaft 40 Stator Blade 41, 41A Inner Ring 43 Slit (Drain Recovery Hole)
44 Internal space 70 Partition plate 71 First chamber 72 Second chamber 73 Metal ball (damping member)

Claims (3)

A plurality of stator blades having a hollow structure in which a plurality of drain holes are provided at intervals in the circumferential direction of the rotating shaft and in which a drain recovery hole for recovering drain in the steam flow path is formed in communication with the inside and outside of the rotating shaft;
An inner ring that connects radially inner sides of the plurality of stationary blades in the circumferential direction;
An internal space extending in the circumferential direction is formed inside the inner ring,
A partition plate that divides the internal space into a first chamber through which the drain is guided and a second chamber separated from the first chamber;
A steam turbine comprising: a plurality of damping members filled in the second chamber.   The steam turbine according to claim 1, wherein the second chamber is partitioned on the radially inner side of the inner peripheral ring.   The steam turbine according to claim 1, wherein the damping member is a metal sphere.

Images