JP2003035106A - Steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine, capable of obtaining sealing effect of steam in a sealing part, despite its running state being always stable. SOLUTION: A steam turbine 1 differs in setting two short seal fins 32, 42, capable of being facing projected rims 52, 62 with each other as compared to conventional cases. For two seal fins 32, 42, an interval λ for the mutual interval in the longitudinal direction of a turbine rotor 7 is set according to the relation λ≈W and λ <= for the width W of projected rims 52, 62.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steam turbine provided with a steam sealing portion using sealing fins, and a steam sealing effect in the sealing portion can always be stably obtained regardless of an operating state of the steam turbine. The configuration is suitable for.

[0002]

2. Description of the Related Art A steam turbine is a device that rotates a turbine rotor to generate power by passing a high-speed steam flow obtained by expanding high-temperature, high-pressure steam with stationary blades through a moving blade. It is used as a drive source for machines. In this steam turbine, since the moving blades need to rotate in the circumferential direction, there is always a gap between the moving blades and the casing that surrounds the outer periphery of the moving blades and forms a flow path for the steam. There is always a gap between the stationary blade and the rotating turbine rotor. In order to cope with a decrease in efficiency due to steam leakage that occurs in these gaps, a steam turbine is generally provided with a steam seal portion at this portion.

The steam seal portion of the conventional steam turbine will be described below with reference to FIGS. 4 and 5. First, FIG.
Will be explained. 4A and 4B are explanatory views illustrating a seal portion of a conventional steam turbine, in which FIG. 4A is an explanatory view in a normal state, and FIG. 4B is an explanatory view in a case where a large expansion difference occurs. In FIG. 4A, 9 is a conventional example of a steam turbine including a casing 8, a turbine rotor 7, stationary blades 6, and moving blades 5. The vane 6 is held by a casing 8, and a shroud 61 is provided at a tip end portion of the vane 6 having a convex ridge portion 62 formed on a surface facing the turbine rotor 7 and protruding toward the turbine rotor 7. The rotor blade 5 is embedded in the turbine rotor 7, and a shroud 51 is provided at the tip end portion thereof, in which a convex ridge portion 52 that is convex toward the casing 8 is formed on the surface facing the casing 8.

Turbine rotor 7 at a portion facing the vane 6
Seal fins 41 and 42 are attached to the casing 8, and seal fins 31 and 32 are attached to the casing 8 at a portion facing the moving blade 5. Of the seal fins with multiple attached,
The length of the seal fins 32, 42 facing the ridges 52, 62 is set shorter than the length of the seal fins 31, 41 facing the flat parts of the shrouds 51, 61.
With such a structure of the seal portion, a labyrinth is formed at a portion where the tip portions of the stationary blade 6 and the moving blade 5 face the turbine rotor 7 and the casing 8, and the amount of steam 99 leaking from this portion is suppressed.

Next, description will be made with reference to FIG. 5A and 5B are explanatory views for explaining a seal portion of a steam turbine of a different conventional example, FIG. 5A is an explanatory view when normal, and FIG. 5B is an explanatory view when a large expansion difference occurs. In the following description, the same parts as those of the conventional steam turbine shown in FIG. 4 are designated by the same reference numerals, and the description thereof will be omitted. In FIG. 5 (a), 9A is a steam turbine of a different conventional example, and in the steam turbine 9, two shroud fins 21 and 22 are provided in each of the ridge portion 52 and the ridge portion 62, and The difference is that the number of the seal fins 32 and 42 is set to 2 in correspondence with the number of the shroud fins 21 and 22, respectively. Since the steam turbine 9A is provided with the shroud fins 21 and 22, the sealing effect is obtained by both the seal fins and the shroud fins. Therefore, the leakage amount of the steam 99 from this portion is smaller than that in the case of the steam turbine 9. It is known that this can be reduced.

In the above description of the conventional steam turbines 9 and 9A, the ridges 52 and 6 for each shroud are used.
The number of 2 is 1, and the seal fins 3 facing each ridge portion 3
The number of 2, 42 is one or two, or the number of the shroud fins 21, 22 provided in each of the ridges 52, 62 is two, but the number and the number of these are applicable. If the specifications of the steam turbine to be used differ, the optimum quantity is selected according to the specifications.

[0007]

The steam turbines 9 and 9A according to the prior art described above are provided with a seal portion in which a shroud having a ridge portion and fins for sealing are combined to reduce the amount of leakage of the steam 99. However, there are the following problems and their solutions are desired. That is, since high-temperature steam is supplied during the operation of the steam turbines 9 and 9A, the expansion amount of each part may differ due to the difference in the material used for each part constituting the steam turbine and the difference in the temperature to which each part is exposed. Occurs (the difference in the amount of elongation is called the difference in elongation), and the relative position in the axial direction between the turbine rotor 7 and the casing 8 changes.

Further, even when the temperatures of the turbine rotor 7 and the casing 8 change due to changes in the operating states of the steam turbines 9 and 9A, the relative position in the axial direction between the turbine rotor 7 and the casing 8 changes. Steam turbine 9,9
Regarding A, the turbine rotor 7 has a large elongation difference from the normal state shown in FIGS. 4 (a) and 5 (a).
-A large deviation δ in the relative position in the axial direction between the casings 8
The case where the occurrence occurs is shown in FIGS. 4 (b) and 5 (b). This large deviation δ is the maximum value of the deviation amount that occurs in the operating state of the steam turbines 9 and 9A (hereinafter referred to as maximum deviation δ). When a large maximum deviation δ as shown in FIGS. 4 (b) and 5 (b) occurs, the short seal fins 32, 42 are disengaged from the ridges 52, 62, and the labyrinth formation is broken. The amount of steam 99 leaked increases.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to provide a steam turbine which can always stably obtain a steam sealing effect in a sealing portion regardless of an operating state. is there.

[0010]

SUMMARY OF THE INVENTION In the present invention, the above objects are as follows: 1) A turbine having a stationary blade and / or a moving blade having a shroud at its tip and a seal fin at a portion facing the shroud. In a steam turbine provided with a rotor and / or a casing, the shroud has one or a plurality of ridges which are convex on the side facing the turbine rotor and / or the casing and project toward the turbine rotor and / or the casing. However, one or more predetermined number of the seal fins can be provided so as to face each of the ridges regardless of the operating state of the steam turbine, or 2) a shroud is provided at the tip. And a shroud fin at a portion of the shroud facing the turbine rotor and / or the casing. It provided the stationary blade and /
Alternatively, in a steam turbine including a moving blade and a turbine rotor and / or a casing provided with seal fins at a portion facing the shroud, the shroud has a turbine rotor and / or a surface facing the turbine rotor and / or the casing. Alternatively, one or a plurality of convex ridges is provided on the casing side and one or a plurality of the shroud fins are provided in each ridge, and the seal fins are irrespective of the operating state of the steam turbine. This is achieved by providing at least one predetermined number as a number capable of facing each of the ridge portions.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. First, a steam turbine according to an example of an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory diagram for explaining a steam turbine according to an example of an embodiment of the present invention, and FIG. 2 is an explanatory diagram for explaining the occurrence of a large expansion difference of the steam turbine shown in FIG. In FIGS. 1 and 2, reference numeral 1 denotes a ridge portion 52 of the conventional steam turbine 9 shown in FIG.
62 short sealing fins 32 that can face each other,
The steam turbine of the present invention is different in that two 42 are installed.

Each two sealing fins 32, 42
Is arranged such that the mutual spacing in the axial direction of the turbine rotor 7 is set to a spacing λ (λ≈W, and λ ≦ W, where W is the width of the ridges 52 and 62) in this case. (See FIG. 1). In the steam turbine 1, the steam is 9 at the seal.
In order to obtain the required sealing effect with respect to 9, at least one sealing fin 32, 42 is provided on each ridge 5.
It is necessary to face 2, 62. That is, in the case of the steam turbine 1, each ridge 5
The predetermined number of the seal fins 32, 42 that need to face the 2, 62 is one.

Thus, in the steam turbine 1, as in the case of the conventional steam turbine 9, a maximum deviation δ is generated as a relative positional deviation in the axial direction between the turbine rotor 7 and the casing 8 in the operating state. In the steam turbine 1 in which two seal fins 32 and 42 are installed at a distance λ,
The interval λ is set to a value almost equal to the maximum deviation δ, and even if any amount of relative positional deviation in the axial direction less than or equal to the maximum deviation δ occurs, the seals facing the respective ridges 52, 62. There is at least one fin 32, 42, and a predetermined number (one) of them can be held. Therefore, in the steam turbine 1, the sealing effect of the steam 99 in the seal portion can always be stably obtained regardless of the operating state.

Next, a steam turbine according to another example of the embodiment of the present invention will be described with reference to FIG. In the following description, the same parts as those in the conventional steam turbine shown in FIG. 5 and the steam turbine according to the present invention shown in FIGS. 1 and 2 are designated by the same reference numerals and the description thereof will be omitted. 3A and 3B are explanatory views for explaining a seal portion of a steam turbine according to another example of the embodiment of the present invention, FIG. 3A is an explanatory view at the time of normal operation, and FIG. Is. In FIG. 3, reference numeral 1A denotes the ridges 52, 6 of the conventional steam turbine 9A shown in FIG.
2 short sealing fins 32,4 that can face each other
The steam turbine of the present invention is different in that four 2 are installed.

Each of the four sealing fins 32, 42
Are arranged such that the mutual spacing in the axial direction of the turbine rotor 7 is set to the spacing λ (2λ≈W and 2λ ≦ W) in this case (see FIG. 3). Steam turbine 1A
In order to obtain the required sealing effect against the steam 99 at the sealing portion, at least two sealing fins 32, 42 are required.
Must be opposed to the respective ridges 52 and 62. That is, in the case of the steam turbine 1A, the predetermined number of the seal fins 32 and 42 required to face each of the ridges 52 and 62 is two.

Thus, in the steam turbine 1A, as in the case of the conventional steam turbine 9A, the maximum deviation δ is generated as the relative positional deviation in the axial direction between the turbine rotor 7 and the casing 8 in the operating state. Seal fin 32,4
Steam turbine 1A in which four 2 are installed at intervals λ
Then, the interval λ is set to approximately 1/2 of the maximum deviation δ,
Even if any amount of relative positional deviation in the axial direction less than the maximum deviation δ occurs, there are at least two seal fins 32, 42 facing the respective ridges 52, 62.
The predetermined number (two) can be held. Therefore, in the steam turbine 1A, the sealing effect of the steam 99 in the sealing portion can always be stably obtained regardless of the operating state.

In the above description, the number of the seal fins 32, 42 provided in the steam turbine 1, 1A is twice the predetermined number, but the number is not limited to this.
As a multiple value for a predetermined number of seal fins 32, 42 included in the steam turbine, an optimum multiple value corresponding to the specifications of the applied steam turbine can be selected. Further, in the above description, the mutual intervals of the seal fins 32, 42 provided in the steam turbine 1, 1A in the axial direction of the turbine rotor 7 are λ≈W, and λ ≦ W or 2λ≈W, and 2λ ≦.
Although the interval λ has been set to W, the invention is not limited to this. The relationship between the interval λ and the width W of the ridges 52 and 62 depends on the specifications of the applicable steam turbine or the seal fin 32. , 42 and shroud fins 21, 22
Can be appropriately selected according to the number of

[0018]

In the steam turbine according to the present invention, by adopting the structure described in the section of the means for solving the above-mentioned problems, the steam turbine can be provided with any relative amount in the axial direction between the turbine rotor 7 and the casing 8. Even if misalignment occurs,
The number of the seal fins 32, 42 facing the respective ridges 52, 62 can be maintained at a predetermined number required to obtain a desired sealing effect against the steam 99 in the seal portion. As a result, it is possible to obtain the effect that the sealing effect of the steam 99 in the seal portion can always be stably obtained regardless of the operating state of the steam turbine.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a steam turbine according to an example of an embodiment of the present invention.

FIG. 2 is an explanatory view for explaining the occurrence of a large expansion difference of the steam turbine shown in FIG.

3A and 3B are explanatory diagrams illustrating a seal portion of a steam turbine according to another example of the embodiment of the present invention, in which FIG. 3A is an explanatory diagram at a normal time and FIG.

4A and 4B are explanatory views for explaining a seal portion of a conventional steam turbine, in which FIG. 4A is an explanatory view when normal and FIG. 4B is an explanatory view when a large expansion difference occurs.

5A and 5B are explanatory views for explaining a seal portion of a steam turbine of a different conventional example, FIG. 5A is an explanatory view when normal, and FIG. 5B is an explanatory view when a large expansion difference occurs.

[Explanation of symbols]

1 steam turbine 32 Seal fin 42 Seal fin 52 ridge 62 ridge 7 turbine rotor

Claims (2)

[Claims] 1. A steam turbine including a stationary blade and / or a moving blade having a shroud provided at a tip portion thereof, and a turbine rotor and / or a casing having seal fins provided at a portion facing the shroud, wherein The shroud has one or a plurality of convex ridges that are convex toward the turbine rotor and / or the casing on the surface facing the turbine rotor and / or the casing, and the seal fins are irrespective of the operating state of the steam turbine. The steam turbine is characterized in that one or more predetermined number is provided as a number that can face each of the convex streak portions. 2. A stator blade and / or a rotor blade having a shroud at its tip and shroud fins at a portion of the shroud facing the turbine rotor and / or the casing, and a seal at a portion facing the shroud. In a steam turbine provided with a turbine rotor and / or a casing provided with fins, the shroud has one or a plurality of protrusions on a surface facing the turbine rotor and / or the casing, the protrusion being on the turbine rotor and / or the casing side. And one or a plurality of the shroud fins are provided in each of the ridges, and the seal fins have a predetermined number of one or more irrespective of the operating state of the steam turbine. It is characterized in that it is provided as a number that can face each other. Steam turbine.