JP5851873B2 - Shaft seal device and turbine device including the same - Google Patents

Description

  The present invention relates to a shaft seal device and a turbine device including the shaft seal device.

For example, in a rotary machine such as a steam turbine, a labyrinth seal is frequently used as a seal device between a stationary part and a turbine rotor shaft (rotary shaft). In the labyrinth seal, it is known that when the contact between the labyrinth seal fin and the turbine rotor shaft increases, the turbine rotor shaft is thermally deformed due to heat generated by friction.

  As a result of such deformations, the heating of the turbine rotor shaft and the direct forces generated by the labyrinth seal generally cause the turbine rotor shaft to become unbalanced and increase vibrations in the rotating machine. This enlarges the gap formed between the stationary part and the turbine rotor. In some cases, the turbine device is stopped and opened, and the turbine rotor shaft and the labyrinth seal need to be repaired. Further, the gap formed between the stationary part and the turbine rotor is increased by the contact, and the leakage of gas or steam is increased, so that the efficiency of the rotating machine is lowered.

  FIG. 6 is a side sectional view showing a labyrinth seal portion of a conventional steam turbine 100. In order to seal steam and ensure efficiency, the gap between the turbine rotor shaft 101 and the fin at the tip of the labyrinth seal 103 is set narrow. However, frictional heat is generated when the fin at the tip of the labyrinth seal 103 comes into strong contact with the turbine rotor shaft 101 due to some displacement. There is a possibility that the turbine rotor shaft 103 is deformed due to heat due to friction, and vibration of the steam turbine 100 is generated. Further, in the geothermal power generation apparatus, the cleanliness of the geothermal steam used for the steam turbine 100 is low and contains a corrosive gas.

  The trouble of the shaft seal described above is caused by thermal deformation or friction of the turbine rotor shaft that occurs when the labyrinth seal fin and the turbine rotor shaft come into contact with each other due to some displacement. As a document disclosing such a measure, there is the following Patent Document 1.

  Patent Document 1 includes an insert assembly for a rotating machine including a turbine rotor shaft and a casing. The turbine rotor shaft includes an axis extending generally longitudinally and the casing is aligned substantially coaxially with the axis. The casing surrounds the turbine rotor shaft in the circumferential direction and is spaced radially from the turbine rotor shaft. The insert assembly is fixed to a brush seal by a circumferentially arranged channel on the turbine rotor shaft and fixed by welding or a fastener. An insert disposed in the circumferential direction in such a channel, and as a result, even if friction heat with the brush seal is generated, the insert is configured to thermally insulate the friction heat to the turbine rotor shaft It has been shown that.

JP 2003-328701 A

  In Patent Document 1, an insert assembly is fixed to a circumferentially arranged channel on a turbine rotor shaft by welding or a fastener, and the insert assembly thermally generates frictional heat from the turbine rotor shaft to the insert. It is described that it is configured to be insulated. However, the processing of the channel is complicated. In addition, since the insert assembly is fixed to the circumferentially arranged channel on the turbine rotor shaft by welding or a fixture, the end of the insert assembly can be welded or fixed even if it is a replaceable insert assembly. Since it is fixed with a fastener, there is a problem that the replacement work takes time and the maintainability deteriorates.

  The present invention has been made in view of such circumstances, and is a shaft that reduces the influence of contact between a labyrinth seal fin and a turbine rotor shaft that occurs when some displacement occurs with a simpler structure. It is an object of the present invention to provide a sealing device and a turbine device including the same.

In order to solve the above problems, the shaft sealing device of the present invention and the turbine device including the same employ the following means.
A shaft seal device that seals between a turbine rotor shaft to which turbine blades are attached and a turbine casing that accommodates the turbine rotor shaft, the shaft seal device being attached to the turbine casing and in the axial center direction of the turbine rotor shaft a labyrinth seal fin protruding toward, with attached to the enlarged diameter portion of the turbine rotor shaft, said constitutes a labyrinth seal with the labyrinth seal fin, of the turbine rotor shaft when in contact with the labyrinth seal fin comprising a protective cap to deform in the axial center direction, the said protective cap, Rutotomoni is possible to install and remove to the enlarged diameter portion, a convex shape which possesses a curvature R on the outer peripheral side of the turbine rotor shaft Between the enlarged diameter portion and the protective cap. Wherein the but has been formed.

When the labyrinth seal fin comes into contact with the turbine rotor shaft due to some displacement, frictional heat is generated at the contact portion, which may cause thermal deformation of the turbine rotor shaft. In order to suppress such a thermal influence on the turbine rotor shaft, a protective cap that is deformable with respect to the labyrinth seal fin is provided. With this protective cap, even if the protective cap comes into contact with the labyrinth seal fin, generation of strong contact pressure with the labyrinth seal fin can be avoided, and heat generated at the contact portion can be directly applied to the turbine rotor shaft. Can be prevented from being transmitted to.
In the present invention, such a protective cap can be attached and detached. This facilitates maintenance, and is particularly suitable for a shaft seal of a geothermal steam turbine driven by geothermal steam whose steam cleanness is not relatively high.
Moreover, since the protective cap has a gently convex shape having a curvature R on the outer peripheral side, a space is formed between the enlarged diameter portion and the protective cap. When the protective cap and the labyrinth seal fin come into strong contact due to some displacement, the contact part of the protective cap is pushed toward the internal space, reducing the resistance due to contact, reducing the contact pressure, and reducing the frictional heating value. To reduce.

  Further, the enlarged diameter portion of the turbine rotor shaft is formed with a groove for positioning the protective cap.

  By forming a groove for positioning the protective cap in the enlarged diameter portion of the turbine rotor shaft, positioning of the protective cap is facilitated, and maintenance work for attaching and removing the protective cap is further facilitated. Further, this grooving can be easily performed by pressing a cutting tool from around the enlarged diameter portion while rotating the turbine rotor shaft with a lathe machine.

Further, the protective cap is constituted by a plurality of divided bodies divided in the circumferential direction of the turbine rotor shaft, and the outer diameter side corners at the circumferential ends along the circumferential direction of the divided bodies are The labyrinth sealing fin is shaped to face with an obtuse angle during rotation.

The outer diameter side corner portion at the end portion in the circumferential direction of the protective cap formed of the divided body has a shape facing the labyrinth seal fin with an obtuse angle when rotating. This reduces the resistance when the labyrinth seal fin contacts the circumferential end of the protective cap.
The protective cap is preferably divided into 4 to 8 parts.

  Further, the circumferential end of the protective cap is formed in a direction inclined with respect to the axial direction of the turbine rotor shaft.

  By forming the circumferential end of the protective cap in a direction inclined with respect to the axial direction, the sealing performance is improved as compared with the case where the end of the protective cap is formed by extending a linear distance. By improving the sealing performance of the protective cap, the working fluid is prevented from flowing into the protective cap.

  Further, the protective cap is made of a material that is more resistant to corrosion with respect to the working fluid flowing into the turbine casing than the material of the turbine rotor shaft.

By using a material that is more corrosion resistant to the working fluid than the material of the turbine rotor shaft for the protective cap, it is possible to prevent deterioration of the sealing performance due to corrosion of the seal portion of the turbine rotor shaft.

  A turbine blade, a turbine rotor shaft to which the turbine blade is attached, a turbine casing that houses the turbine blade and the turbine rotor shaft, and a shaft seal device that seals between the turbine rotor shaft and the turbine casing; It is a turbine apparatus provided with.

  Since the above shaft seal device is provided, a turbine device including the shaft seal device excellent in maintainability can be provided.

According to the present invention, even when the labyrinth seal fin and the turbine rotor shaft come into contact with each other due to some displacement, the thermal influence on the turbine rotor shaft can be reduced. Since the protective cap having a simple structure that can be attached and detached and the fin for the labyrinth seal are in contact with the enlarged diameter portion of the turbine rotor shaft, the influence of frictional heat on the turbine rotor shaft can be reduced. Therefore, the thermal influence on the turbine rotor shaft can be reduced and maintenance can be facilitated.

It is side surface sectional drawing which showed 1st Embodiment of this invention. FIG. 2 is a perspective view of a protective cap shown in FIG. 1. FIG. 2 is a front view of the protective cap shown in FIG. 1. It is a division body edge part detail drawing of 1st Embodiment which concerns on this invention. It is a perspective view at the time of the width direction division body assembly which concerns on this invention. It is the sectional side view which showed the conventional steam turbine. It is side surface sectional drawing of 2nd Embodiment which concerns on this invention.

Hereinafter, an embodiment of a shaft seal device according to the present invention will be described with reference to the drawings.
[First Embodiment]
FIG. 1 shows a shaft seal device according to a first embodiment of the present invention. The shaft seal device includes a turbine rotor shaft 1 (hereinafter simply referred to as “rotor shaft ”) to which a turbine blade fixing portion 2 to which a blade root of a turbine blade is fixed is attached, and a turbine casing that houses the rotor shaft 1. It is a shaft seal device that seals the gap. The shaft sealing apparatus, the attached to the turbine casing, a labyrinth seal fins 3 projecting toward the rotor shaft 1, with attached to the enlarged diameter portion 4 of the rotor shaft 1, a labyrinth seal with the labyrinth seal fin 3 And a protective cap 6 that is deformed when it comes into contact with the labyrinth seal fin 3. The protective cap 6 can be attached to and detached from the enlarged diameter portion 4.

  FIG. 2 shows the protective cap 6. The protective cap 6 is substantially C-shaped when viewed in cross section, and both end portions thereof are protective cap fixing portions 6b. Since the protective cap 6 has a gently convex shape having a curvature R on the outer peripheral side, a space is formed between the enlarged diameter portion 4 and the protective cap 6. When the protective cap 6 and the labyrinth seal fin 3 come into strong contact due to some displacement, the contact portion of the protective cap 6 is pushed toward the inner space, reducing the resistance due to contact, reducing the contact pressure, and friction. Reduce heat generation.

Also, the labyrinth seal fin 3 first comes into contact with the vicinity of the center of the protective cap 6 in the width direction ( axial direction of the rotor shaft 1). An elastic support portion 5 may be provided in a portion that supports the labyrinth seal fin 3 , and the elastic support portion 5 further deforms the labyrinth seal fin 3 so as to elastically escape in the circumferential direction of the rotor shaft 1. Resistance due to strong contact between the protective cap 6 and the labyrinth seal fin 3 can be further reduced, the contact pressure can be lowered, and the amount of heat generated by friction can be further reduced.

The outer peripheral side convex shape of the protective cap 6 can be made into an appropriate convex shape by possessing a curvature R that is 1/2 to 1 times the diameter of the rotor shaft 1. R is a gap of both end portions of the labyrinth seal fins 3 in the axial direction of the rotor shaft 1 is significant at below half the diameter of the rotor shaft 1, to reduce the sealability.
Further, when R is equal to or larger than the diameter of the rotor shaft 1, the deformation of the protective cap 6 is small when it comes into contact with the labyrinth seal fin 3, which is insufficient to reduce the resistance due to contact.

A groove 7 (see FIG. 1) into which the protective cap fixing portion 6b is inserted is formed on the side surface of the enlarged diameter portion 4 of the rotor shaft 1. Thereby, the positioning of the protective cap 6 is performed with respect to the enlarged diameter portion 4 of the rotor shaft 1. The protective cap 6 can be easily attached to and detached from the enlarged diameter portion 4 of the rotor shaft 1 by expanding the distance between the opposing protective cap fixing portions 6b. Machining of the groove 7 is in the position grooving by pressing the cutting byte from the periphery of the enlarged diameter portion 4 while rotating the lathe Delo over motor shaft 1 can be easily performed.
Further, the protective cap 6 is made of a material having corrosion resistance more than that of the rotor shaft 1, and for example, a stainless material is used.

As shown in FIG. 3, the protective cap 6 is divided into a plurality of parts in the circumferential direction of the rotor shaft 1. In the figure, the number of divisions of the protective cap 6 is preferably in the range of 4 to 8 divisions according to the diameter of the rotor shaft 1.

FIG. 4 shows details of the end portion of the divided body 8 of the protective cap 6. Thus, the protective cap 6 is constituted by a plurality of divided bodies 8 divided in the circumferential direction, and the outer diameter side corners 6a at the circumferential end 6c of the divided body 8 are formed on the labyrinth seal fin 3. On the other hand, it has a shape that opposes with an obtuse angle during rotation. When the divided body 8 having the outer side corner portion 6a is used, the labyrinth when the labyrinth seal fins 3 are brought into contact with each other between the divided bodies 8 of the protective cap 6 as shown in FIG. The sealing fin 3 is not damaged by being caught in the gap between the divided bodies 8.

As shown in FIG. 5, the division | segmentation shape in the width direction of the protective cap 6 makes it the direction which inclines the circumferential direction edge part 6c of the protective cap 6 with respect to an axial direction. Thus, as compared with the case of dividing in the axial direction of the protective cap 6, the distance of the circumferential edge portion 6c may turn long. For this reason , the flow path of the working fluid that leaks and passes through the circumferential end 6c in the axial direction of the rotor shaft 1 becomes longer, and the passage resistance increases, so that the sealing performance is improved.

Next, the operation of the shaft seal device having the above configuration will be described.
The shaft seal device seals the working fluid between a rotating rotor shaft 1 to which turbine blades are attached and a turbine casing that houses the rotating rotor shaft 1. Shaft sealing apparatus, the attached to the turbine casing, a labyrinth seal fins 3 projecting toward the rotor shaft 1, to seal the working fluid by a protective cap 6 which is attached to the enlarged diameter portion 4 of the rotor shaft 1 Yes. A labyrinth seal is configured together with the labyrinth seal fin 3, and a protective cap 6 is provided that is deformed when it comes into strong contact with the labyrinth seal fin 3. The protective cap 6 can be attached to and detached from the enlarged diameter portion 4.

According to this embodiment, the following effects are produced.
If the labyrinth sealing fin 3 comes into strong contact with the rotor shaft 1 due to some displacement, frictional heat is generated at the contact portion, and the rotor shaft 1 may be thermally deformed. In order to suppress such a thermal influence on the rotor shaft 1, a protective cap 6 that can be deformed with respect to the labyrinth seal fin 3 is provided. Even if the protective cap 6 is in strong contact with the labyrinth seal fin 3, the protective cap 6 can avoid damage to the labyrinth seal fin 3, reduce frictional heat at the contact portion, and further contact It is possible to prevent the heat generated in the portion from being directly transmitted to the rotor shaft 1.

In the present invention, such a protective cap 6 can be attached and removed. This facilitates maintenance, and is particularly suitable for a shaft seal of a geothermal steam turbine driven by geothermal steam whose steam cleanness is not relatively high. Further, the groove 7 for positioning the protective cap 6 is formed in the enlarged diameter portion 4 of the rotor shaft 1 so that maintenance work can be facilitated. Further, by using a material that is more resistant to the working fluid than the material of the rotor shaft 1 for the protective cap 6, it is possible to prevent deterioration of the sealing performance due to corrosion of the seal portion of the rotor shaft 1.

Further, as shown in FIG. 5, the circumferential end 6c of the protective cap 6 is formed in a direction inclined with respect to the axial direction. Compared with the case where the end portion of the protective cap 6 is formed by extending a linear distance, the distance of the circumferential end portion 6c is increased, so that the passage resistance of the working fluid leaking in the axial direction of the rotor shaft 1 is increased. Therefore, the sealing performance is improved. By improving the sealing performance, it is possible to prevent the loss of turbine performance and the occurrence of corrosion due to leakage of the working fluid.

[Second Embodiment]
Next, a second embodiment will be described with reference to FIG.
In the present embodiment, the number of the enlarged diameter portions 4 of the rotor shaft 1 shown in the first embodiment is further added. Therefore, the same components as those in the first embodiment are denoted by the same reference numerals and the description thereof is omitted.
As shown in FIG. 2, the enlarged diameter portion 4 of the rotor shaft 1 is arranged in series in the axial direction in three stages as viewed from the turbine blade fixing portion 2 side. From the turbine blade fixing portion 2 side, the front stage, the middle stage, and the rear stage are configured, and the circumferential cap radii of the front stage and rear stage protective caps 6 on both sides are configured to be larger than those of the middle stage protective cap 6. The labyrinth seal fin 3 is provided in accordance with the circumferential radius of the protective cap 6.

According to the present embodiment , when the protective cap 6 comes into contact with the labyrinth seal fin 3, an increase in the contact pressure of the labyrinth seal fin 3 occurs. When the contact pressure increases, the elastic support portion 5 that supports the labyrinth seal fin 3 allows the entire labyrinth seal portion to escape in the circumferential direction to reduce friction and suppress heat generation. A protective cap 6 having a larger circumferential radius than the normal protective cap 6 is installed in the front and rear stages, and the normal protective cap 6 is used in the middle stage. When the displacement is caused by some displacement, the displacement of the protective cap 6 at the front stage or the rear stage having a large circumferential radius is larger than the protection cap 6 at the middle stage having a small diameter. The labyrinth sealing fin 3 comes into contact with the cap 6 first. Due to this contact, the elastic support portion 5 that supports the labyrinth seal portion is tilted, and when the other side protective cap 6, that is, the front-stage labyrinth seal fin 3 contacts first, The gap between the labyrinth seal portion and each protective cap 6 tends to be kept uniform by returning to the inclination. In this way, the labyrinth seal portion is configured not to be plastically deformed by receiving a bias pressure while maintaining a gap balance with the protective cap 6. From these configurations, damage to the labyrinth seal fin 3 can be prevented, and the sealability of the shaft seal device can be stabilized.

DESCRIPTION OF SYMBOLS 1 Turbine rotor shaft 2 Turbine blade 3 Labyrinth seal fin 4 Expanded diameter part 5 Elastic support part 6 Protective cap 6a Protective cap end part 6b Protective cap fixing part 6c Circumferential end part 7 Groove 8 Divided body

Claims (6)

A shaft seal device that seals between a turbine rotor shaft to which turbine blades are attached and a turbine casing that houses the turbine rotor shaft,
A labyrinth seal fin that is attached to the turbine casing and protrudes toward the axial center of the turbine rotor shaft;
A protective cap that is attached to the enlarged diameter portion of the turbine rotor shaft, constitutes a labyrinth seal together with the labyrinth seal fin, and deforms in the axial center direction of the turbine rotor shaft when in contact with the labyrinth seal fin;
With
It said protective cap is Rutotomoni is possible to install and remove to the enlarged diameter portion, a convex shape to hold curvature R on the outer peripheral side of the turbine rotor shaft, and the protective cap and the enlarged diameter portion A shaft sealing device characterized in that a space is formed between them .   The shaft seal device according to claim 1, wherein a groove for positioning the protective cap is formed in the enlarged diameter portion of the turbine rotor shaft. The protective cap is constituted by a plurality of divided bodies divided in the circumferential direction of the turbine rotor shaft,
The outer-diameter side corner at the circumferential end along the circumferential direction of each of the divided bodies is shaped to face the labyrinth seal fin with an obtuse angle during rotation. The shaft seal device according to 1 or 2 . The shaft seal device according to claim 3 , wherein the circumferential end of the protective cap is formed in a direction inclined with respect to an axial direction of the turbine rotor shaft. The protective cap, than the material of the turbine rotor shaft, according to any one of claims 1 to 4, characterized in that it is a material having corrosion resistance against the working fluid flowing into the turbine casing Shaft seal device. Turbine blades,
A turbine rotor shaft to which the turbine blades are attached;
A turbine casing that houses the turbine blades and the turbine rotor shaft;
A shaft sealing device that seals between the turbine rotor shaft and the turbine casing;
A turbine device comprising:
The shaft sealing device, a turbine device, characterized in that there is a shaft seal device according to any one of claims 1 to 5.

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