JPH11257014A - Working fluid leakage prevention apparatus for axial-flow turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent increase in the amount of working fluid leakage and excessive vibrations caused by the contact of the rotor of the axial-flow turbine and the seal fin. SOLUTION: A leaf spring 20 provided to the outer periphery of a seal ring 9 located at the upper half of a rotational rotor 5 holds down the seal ring 9 in the direction toward the center of the rotational rotor shaft. In order to correct the pressing force which becomes disproportionate by the own weight of each seal ring 9, strength of each leaf spring 20 is adjusted. A curved spring 17 inserted into a communicating groove 16 of the seal ring 9 is engaged with hook portions 18, 19 formed at the inset portion 8 of a nozzle diaphragm inner ring 3, pressing the seal ring 9 in the outer peripheral direction. In such a condition, if the pressure difference between the outside and inside peripheries is changed, the seal ring 9 moves in the radial direction of the rotational rotor shaft without any irregular movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation of an axial flow turbine for reducing an amount of leakage fluid passing through a gap between a rotary rotor and a seal ring attached to a nozzle diaphragm inner ring of a stationary portion in an axial flow turbine stage. The present invention relates to a fluid leakage prevention device.

[0002]

2. Description of the Related Art Generally, an axial flow turbine such as a steam turbine or a gas turbine includes a stationary nozzle and rotating blades. The nozzle expands a working fluid such as steam from a high pressure upstream to a low pressure downstream and converts thermal energy into velocity energy. The rotor blade rotates at high speed due to this velocity energy and becomes rotational energy,
The generator or the like is turned by the rotational energy and taken out as power.

In the stage of the axial flow turbine, when the working fluid passes through the stage passage, the working fluid leaks in a gap between the rotating part and the stationary part. This has led to a decrease in efficiency. One of the causes of the decrease in the turbine efficiency is a loss that occurs when the working fluid leaks from the inner periphery of the rotating rotor and the inner ring of the nozzle diaphragm.

In order to reduce the leakage loss, a seal ring having a seal fin fixed thereto is provided on the inner periphery of the inner ring of the nozzle diaphragm, in order to reduce leakage fluid passing through a gap between the rotary rotor and the seal fin. The gap is reduced.

It is preferable to minimize the gap in order to reduce the amount of leakage. However, if the gap is too small, the rotating rotor and the seal fins come into contact with each other, causing a problem of excessive vibration of the turbine shaft. I'm making it bigger. That is, during the turbine start-up, load change, and stop processes, the vibration tends to be excessively large. If the gap is small, the tip of the seal fin is scraped off due to the contact between the rotating rotor and the seal fin, and the leakage area becomes large. Loss increases and turbine efficiency decreases.

FIG. 6 shows a conventional working fluid leakage prevention device (part 1) for an axial turbine. A nozzle diaphragm outer ring 2 fixed by a casing 1 is provided at the turbine stage.
A nozzle 4 forming a plurality of blade rows in a circumferential direction between the rotor 4 and the inner ring 3, and a rotatable rotor 5 at the center of the casing 1.
And a rotor blade 7 that is implanted on a wheel 6 concentric with the rotor 5 to form a cascade. An implanted portion 8 is formed on the inner peripheral side of the nozzle diaphragm inner ring 3, and a plurality of seal rings 9 are mounted therein. A seal fin 10 is fixed to the inner surface of the seal ring 9 so as to keep the gap a between the rotor 5 and the seal fin 10 at a minimum.

In the turbine stage section, the gap a is reduced in order to reduce the amount of the working fluid b leaking from the gap a between the rotor 5 and the seal fin 10. Generally, since the gap a is narrow, the rotor 5 comes into contact with the seal fin 10 during rotation of the rotor 5, and the tip of the seal fin 10 wears out, the gap a widens, and the paragraph efficiency decreases due to an increase in the amount of leakage of the working fluid. Was exerted. Further, the contact of the rotor 5 with the seal fins 10 causes excessive vibration of the rotor 5, which hinders stable operation of the turbine. for that reason,
Conventionally, a working fluid leakage prevention device as shown in FIGS. 7 and 8 has been employed for the purpose of preventing a reduction in turbine efficiency and excessive vibration due to fin contact wear.

A conventional hydraulic fluid leakage prevention device for an axial flow turbine (part 2) shown in FIG. 7 has a bellows 11 connected to the outer periphery of a seal ring 9 and communicated with the inner ring 3 of the nozzle diaphragm. Is provided with a pressure hole 12 communicating with the bellows 11. During the turbine start-up, load change, and stop processes, the rotor 5
In the rated load operation, a high-pressure fluid is supplied from the pressurizing hole 12 to drive the seal ring 9 toward the center of the shaft to narrow the gap a.

A working fluid leakage prevention device (part 3) for an axial turbine shown in FIG.
Each of the seal rings 9 has a plurality of seal rings 9, and a hole 13 is provided in an end face adjacent to each seal ring 9, perpendicular to the end face, into which a spring 14 is inserted. FIG. 8A shows a state during rated load operation from the intermediate load region after the rotation of the turbine is increased. However, since a pressure difference occurs between the upstream side and the downstream side of the seal ring 9, the outer periphery of the seal ring 9 A force Fa due to an upstream pressure is applied to the surface, and a force Fb due to a lower pressure than the upstream is applied between the seal fins 10 on the inner peripheral surface. The seal ring 9 moves toward the center of the shaft due to the difference in the acting force, and the gap a is made the narrowest.

[0010] On the other hand, during the turbine start and stop process, FIG.
As shown in (b), the spring 14 seals the seal ring 9.
Abut each other in the direction of arrow c, and the seal ring 9 moves toward the outer diameter side. Thereby, the gap a between the rotor 5 and the seal fin 10 is widened as shown in FIG. Further, as shown in FIG. 8B, the lower half of the seal ring 9 falls downward by its own weight, and is therefore supported vertically by the gravity spring 15.

[0011]

However, in the conventional working fluid leakage prevention device for an axial turbine as shown in FIG. 7, the bellows is frequently activated or stopped or the load of the turbine changes. Since the bellows 11 are liable to be broken by repeated stress, it is necessary to increase the strength of the bellows 11, which causes a disadvantage that the size of the working fluid leakage prevention device increases.

On the other hand, in the conventional working fluid leakage prevention device for an axial turbine as shown in FIG. 8, when the seal ring 9 moves toward the center of the shaft under a low load operation condition during a load rising and falling process. Since the individual seal rings 9 are not completely fixed, irregular movement tends to occur. In this case, there is a disadvantage that an unnecessary repetitive load or a high-temperature creep load is applied to the spring 14 inserted into the end face of the seal ring 9 so that long-time low-load operation cannot be performed. Since each seal ring 9 is subjected to its own weight by gravity, a gravity spring 15 is added to the lower half seal ring 9 to push it upward in the vertical direction. , The gravity spring 15
However, there is a drawback that the individual seal rings 9 do not move at the same time and easily move irregularly as described above. As described above, the conventional working fluid leakage prevention device for an axial turbine has various disadvantages, and it is necessary to improve the reduction in turbine efficiency and the excessive vibration.

The present invention prevents excessive vibration due to contact between the rotor of the axial flow turbine and the seal fins and an increase in the amount of leakage of the working fluid, and operates the axial flow turbine with high reliability even during long-time low-load operation. It is an object to provide a fluid leakage prevention device.

[0014]

According to a first aspect of the present invention, there is provided an apparatus for preventing a working fluid from leaking in an axial flow turbine, wherein a nozzle is provided between a rotary rotor of the axial flow turbine and an inner ring of a stationary nozzle diaphragm corresponding to the rotary rotor. An implant is provided on the inner ring of the diaphragm, and a plurality of seal rings are implanted in the circumferential direction.
In a working fluid leakage prevention device for an axial flow turbine, the seal ring is movable in a radial direction of a rotating rotor shaft by a pressure difference between an outer periphery and an inner periphery of the seal ring to prevent leakage of a working fluid of the axial turbine. , At least on the outer peripheral surface of the seal ring located on the upper half side of the rotating rotor, for pressing the seal ring toward the center of the rotating rotor shaft so as to eliminate the imbalance in the pressing force caused by the weight of each seal ring. A leaf spring and a curved spring inserted into a communication groove provided in each seal ring and engaged with a hook portion formed in an implanted portion of the nozzle diaphragm inner ring to press each seal ring in an outer peripheral direction. It is characterized by.

According to the first aspect of the present invention, at least the leaf spring provided on the outer peripheral surface of the seal ring located on the upper half side of the rotary rotor is provided in a direction toward the center of the rotary rotor shaft. Force acts in the direction to press the seal ring. In this case, the pressing force becomes unbalanced due to the own weight of each seal ring, and the strength of each leaf spring is adjusted to correct the imbalance. Also,
The curved spring inserted into the communication groove of each seal ring
A force acts in a direction in which each seal ring is pressed in the outer peripheral direction by engaging with a hook portion formed in the implanted portion of the nozzle diaphragm inner ring. In this state, when the pressure difference between the outer circumference and the inner circumference of the seal ring changes, the seal ring moves in the radial direction of the rotating rotor shaft without irregular movement.

According to a second aspect of the present invention, there is provided an apparatus for preventing working fluid leakage of an axial turbine according to the first aspect of the present invention, wherein the leaf spring is provided on a seal ring on an upper half side of a rotary rotor. Is longer than the leaf spring provided on the lower half seal ring of the rotating rotor,
It is characterized in that one of the width and the thickness is reduced so as to eliminate the imbalance in the pressing force caused by the weight of each seal ring.

According to a second aspect of the present invention, in addition to the operation of the first embodiment, the working force of the seal ring is reduced by the weight of the seal ring. In order to eliminate the imbalance, the leaf spring provided on the seal ring on the upper half side of the rotating rotor is smaller in leaf length, width, or thickness than the leaf spring provided on the seal ring on the lower half side of the rotating rotor. To reduce the spring force.

According to a third aspect of the present invention, there is provided an apparatus for preventing working fluid leakage of an axial flow turbine according to the first aspect of the present invention, wherein an imbalance in pressing force caused by the own weight of each seal ring is provided. In order to eliminate this, a leaf spring is provided only on the seal ring on the lower half side of the rotating rotor.

According to the third aspect of the present invention, in addition to the working fluid leakage preventing device for an axial flow turbine according to the first aspect, the working fluid leakage preventing device is provided on the lower half seal ring of the rotary rotor. The leaf spring bears its own weight on the lower half-side seal ring, and the upper half-side seal ring is not provided with a leaf spring, thereby eliminating imbalance in the pressing force caused by the own weight of each seal ring. .

According to a fourth aspect of the present invention, there is provided a device for preventing working fluid leakage of an axial flow turbine according to the first aspect of the present invention, wherein the curved springs are provided at both end surfaces of respective seal rings adjacent to each other. The upstream hook portion, the communication groove, and the downstream hook portion of the implanted portion which is inserted into the communication groove provided so as to communicate from the upstream side to the downstream side of the working fluid, and in which the seal ring of the inner ring of the nozzle diaphragm is implanted. It is characterized by being supported by.

According to a fourth aspect of the present invention, in addition to the operation of the first embodiment, the curved spring further includes a seal ring for the inner ring of the nozzle diaphragm. Supported at three points: an upstream hook portion and a downstream hook portion of the implanted portion to be implanted, and communication grooves provided on both end surfaces of each seal ring adjacent to each other so as to communicate from the upstream side to the downstream side of the working fluid. And
Prevents irregular movement of each seal ring as it moves in the direction of the rotating rotor.

According to a fifth aspect of the present invention, there is provided a working fluid leakage prevention device for an axial flow turbine, wherein the curved spring comprises a head on the outer peripheral side of each seal ring. The upstream hook portion, the communication hole, and the downstream hook portion of the implanted portion, which is inserted into the communication hole provided to communicate the working fluid from the upstream side to the downstream side and implants the seal ring of the inner ring of the nozzle diaphragm. It is characterized by being supported by.

According to a fifth aspect of the present invention, in addition to the operation of the first embodiment, the curved spring further includes a seal ring for the inner ring of the nozzle diaphragm. Supported at three points: an upstream hook portion and a downstream hook portion of the implanted portion to be implanted, and a communication hole provided in the head on the outer peripheral side of each seal ring so as to communicate from the upstream side to the downstream side of the working fluid. This prevents irregular movement when each seal ring moves in the direction of the rotating rotor.

According to a sixth aspect of the present invention, there is provided a working fluid leakage prevention device for an axial flow turbine according to any one of the first to fifth aspects, wherein a bending spring is used. Thus, a plate-like elastic member made of two different materials is used.

According to a sixth aspect of the present invention, in the working fluid leakage prevention device for an axial flow turbine, in addition to the operation of the working fluid leakage prevention device for an axial flow turbine according to any one of the first to fifth aspects, the following features are provided. The plate-like elastic members made of two different materials prevent irregular movement of each seal ring in the direction of the rotating rotor.

According to a seventh aspect of the present invention, there is provided an apparatus for preventing working fluid leakage of an axial flow turbine, wherein the elastic member comprises a plate-shaped expansion member and a shape memory alloy. Characterized by being formed from

According to a seventh aspect of the present invention, there is provided a working fluid leakage prevention device for an axial flow turbine, wherein in addition to the function of the working fluid leakage prevention device for an axial flow turbine, a plate-shaped expansion member and a shape memory alloy are used. The formed elastic member prevents irregular movement of each seal ring in the direction of the rotating rotor.

According to an eighth aspect of the present invention, there is provided a working fluid leakage preventing device for an axial flow turbine according to the first aspect, wherein the inner peripheral surface of the implanted portion of the inner ring of the nozzle diaphragm and the seal ring are provided. The radial gap formed between the outer peripheral surface and the outer peripheral surface is equal to the amount by which the seal ring moves in the radial direction of the rotating rotor shaft when the load of the axial flow turbine increases or decreases. I do.

According to the eighth aspect of the present invention, in addition to the operation of the first embodiment, the working fluid leakage prevention device for an axial flow turbine can be used when the load of the axial flow turbine rises or falls. In addition, the amount by which the seal ring moves in the radial direction of the rotary rotor shaft is regulated by the radial gap formed between the inner peripheral surface of the implanted portion of the nozzle diaphragm inner ring and the outer peripheral surface of the seal ring. No more excessive movement than necessary.

According to a ninth aspect of the present invention, there is provided an apparatus for preventing working fluid leakage of an axial flow turbine according to the first aspect, wherein the seal ring is pressed to the downstream side by the working fluid. The surface of the seal ring in surface contact with the implanted portion of the inner ring of the nozzle diaphragm is subjected to a corrosion-resistant coating or a surface hardening treatment.

According to the ninth aspect of the present invention, in addition to the working fluid leakage preventing device for an axial flow turbine according to the first aspect, in addition to the action of the working fluid leakage preventing device for an axial flow turbine, a seal that comes into surface contact with the implanted portion of the inner ring of the nozzle diaphragm. The corrosion-resistant coating or surface hardening treatment applied to the ring portion allows the seal ring to move smoothly in the radial direction of the rotating rotor shaft even when the seal fluid is pressed downstream by the working fluid.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A working fluid leakage prevention device for an axial turbine according to an embodiment of the present invention will be described below. FIG. 1 is an explanatory view of a working fluid leakage prevention device for an axial flow turbine according to a first embodiment of the present invention. FIG. 1 (a) is a partially cutaway sectional view, and FIG. 1A is a partial side view from the direction of the arrow A (axial direction), and FIG. 1C is a partially cutaway perspective view of the seal ring 9.

As shown in FIG. 1A, an implanted portion 8 is provided in the nozzle diaphragm inner ring 3, and the implanted portion 8 is provided.
A plurality of seal rings 9 are implanted in the circumferential direction on the inner periphery of the. A seal fin 10 is fixed to the inner peripheral surface of the seal ring 9 on the side of the rotary rotor 5.
There is a gap a between the rotating rotor 5 and the opposing seal fin 10, and the leaked fluid passes through the gap a as shown by an arrow b.

A communication groove 16 is cut out in the seal ring 9, and a curved spring 17 is inserted into the communication groove 16. This curved spring 17 is connected to the upstream hook portion 1 formed on the implanted portion 8 of the nozzle diaphragm inner ring 3.
8 and the downstream side hook portion 19 to engage with the seal ring 9.
Is pressed in the outer peripheral direction. That is, the curved spring 17
Are the upstream hook portion 18 of the implanted portion 8 of the nozzle diaphragm inner ring 3, the outer peripheral surface of the communication groove 16, and the downstream hook portion 19.
The curved spring 1 is supported at three points.
Reference numeral 7 is curved so as to be in contact with the outer peripheral surface of the communication structure 16 and has a function of moving the seal ring 9 to the outer peripheral side. Further, a leaf spring 20 for pressing the seal ring 9 toward the center of the axis of the rotary rotor 5 is provided on the outer peripheral surface of the seal ring 9.

As shown in FIG. 1B, communication grooves 16 penetrating the upstream and downstream sides of the outer periphery of the seal ring 9 are cut out at both end faces 21a and 21b of the seal ring 9 adjacent to each other. It has been processed. In FIG. 1 (c),
FIG. 2 shows a partially cutaway perspective view of one seal ring 9. As shown in FIG. 1A, a curved spring 17 is inserted into the communication groove 16, and the curved spring 17 is connected to the upstream hook 18 of the implant 8, the outer peripheral surface of the communication structure 16, and the downstream hook 19. It is supported so that it contacts.

FIG. 2 is an explanatory view of the movement of the seal ring 9 and the change of the gap a in the first embodiment of the present invention. FIG. 2A shows the gap a1 during the stop of the turbine or the low load operation. 2B shows a state in which the gap a2 has become narrower during the rated load operation, and FIG.
(C) is a characteristic diagram showing a change characteristic of a gap a during a turbine operation process.

In FIG. 2A, the gap a is widened as shown by the gap a1 under the condition that the turbine is stopped or the engine is operating at a low load. Under this condition, there is almost no moving force Fr of the seal ring due to the pressure difference between the outer peripheral pressure and the inner peripheral pressure of the seal ring 9, and the pressing force Fp of the curved spring 17 becomes larger than the pressing force Fs of the leaf spring 20,
The seal ring 9 moves to the outer peripheral side.

On the other hand, as shown in FIG. 2B, under the condition of the rated load operation, the gap a is narrow as shown by the gap a2. Under this condition, the moving force Fr of the seal ring 9 due to the pressure difference between the outer peripheral pressure and the inner peripheral pressure of the seal ring 9 increases, and the resultant force with the pressing force Fs of the leaf spring 20 is larger than the pressing force Fp of the curved spring 17. Become
The seal ring 9 moves inward.

As shown in FIG. 2A, when the turbine is stopped or the engine is running at a low load, the curved spring 17 is set at H1.
When the turbine is stopped, the outer surface of the communication groove 16 is pushed up using the upstream hook portion 18 and the downstream hook portion 19 of the implanted portion as a fulcrum, and as shown in FIG. Then, the bending spring 17 is compressed by the moving force Fr of the seal ring 9 and is reduced to the dimension H2.

The gap a is set so that the seal ring 9 moves in the radial direction of the rotating rotor shaft (gap k = gap a1-gap a2) while the load on the turbine rises and falls. . By adjusting the gap k in this manner, it becomes possible to manage the gap when the turbine load rises or falls, and it is possible to increase the leakage amount and reduce the shaft vibration caused by contact.

FIG. 2C shows the gap a during the turbine operation process.
FIG. 4 is a characteristic diagram showing changes in Since the vibration amplitude of the rotating rotor 5 is large in the low load region from the start of the turbine, the gap a is widened (the gap a1), and the generation of shaft vibration due to the contact between the rotating rotor 5 and the seal fins 10 is prevented. I have. Thereby, the wear of the seal fin 10 can be prevented.

On the other hand, the operation in the range from the intermediate load to the rated load is a stable operation condition, and the abrasion due to the contact between the rotating rotor 5 and the seal fins 10 hardly occurs, so that the gap a is narrowed (gap a2) and the working fluid The amount of leakage has been reduced. Thereby, turbine efficiency can be improved.

When the seal ring 9 moves toward the center of the rotating rotor shaft in the intermediate load region and the gap a becomes narrow, the seal ring 9 generally tends to move irregularly.
In the embodiment, the curved spring 17 pushes the outer surface of the communication groove 16 to the outer peripheral side with the upstream hook portion 18 and the downstream hook portion 19 as fulcrums, and the seal ring 9 is contradicted by the leaf spring 20 to the inner peripheral side. The seal ring 9
Can be suppressed.

Here, as shown in FIGS. 2 (a) and 2 (b), during operation of the turbine, the seal ring 9 causes the inner ring of the nozzle diaphragm located on the downstream side in the axial direction of the rotary rotor 5 by the working fluid. 3 and is in surface contact with the implanted portion 8. In particular, it is strongly pressed during the rated load operation of the turbine. If the surface in contact with the surface becomes rough due to corrosion or wear, the coefficient of friction changes and the balance of force changes when the seal ring 9 moves in the radial direction of the rotating rotor shaft.

Therefore, in the first embodiment, the surface contact portion between the nozzle diaphragm inner ring 3 and the seal ring 9 is subjected to a corrosion-resistant coating treatment or a surface hardening treatment. This allows the seal ring 9 to move smoothly, and also prevents the friction coefficient from changing over time. That is, the surface treatment makes it possible to manage the gap when the turbine load rises or falls, and it is possible to increase the leakage amount of the working fluid and reduce the shaft vibration caused by contact.

Next, FIG. 3 is an explanatory view of a leaf spring disposed on the outer periphery of the seal ring 9 in the working fluid leakage prevention device for an axial turbine according to the first embodiment of the present invention. FIG. 3A is a plan view of the seal ring 9 viewed from the axial direction, FIG. 3B is a perspective view of the leaf spring 20, and FIG.
(C) is a perspective view of the curved spring 17.

As shown in FIG. 3A, the seal ring 9
Are divided in the circumferential direction, and are usually composed of 4 to 12 pieces. Each seal ring 9 has a force Fj due to its own weight.
, A force acts to move the upper half-side seal ring 9 to the inner peripheral side of the rotating rotor 5 and to move the lower half-side seal ring 9 to the outer peripheral side.

Therefore, in order for each seal ring 9 to simultaneously narrow the gap a in the intermediate load region, it is necessary to change the pressing force Fs of the leaf spring 20 against the seal ring 9 between the upper half side and the lower half side. Therefore, as shown in FIG.
Change the dimensions of length L, width W, and thickness T, which are the sizes of 0,
Change the spring constant. That is, the leaf spring 20 provided on the upper half seal ring 9 of the rotary rotor 5 is the same as the leaf spring 2 provided on the lower half seal ring 9 of the rotor 5.
Any one of the total length L, width W, and thickness T is made smaller than 0 so as to eliminate the imbalance in the pressing force Fs caused by the weight of each seal ring 9. In this case, as shown in FIG. 3C, the size of the curved spring 17 such as the length L, the width W, and the thickness T may be similarly changed to change the spring constant. .

In the above description, any one of the total length L, the width W, and the thickness T of the upper half-side leaf spring 20 is made smaller than that of the lower half-side in order to eliminate the imbalance in the pressing force of the seal ring 9. However, the leaf spring 20 may be attached to only the lower half without installing the leaf spring 20 on the upper half.

As described above, in the first embodiment, when each seal ring 9 moves in the direction of the rotating rotor due to the pressure difference between the outer circumference and the inner circumference of the seal ring 9 in the intermediate load region of the turbine. , Since they start moving almost simultaneously and do not move irregularly, it is possible to prevent trouble stoppage due to excessive vibration. Further, an increase in leakage fluid due to wear of the seal fins 10 can be prevented.

Next, a working fluid leakage prevention device for an axial turbine according to a second embodiment of the present invention will be described. FIG.
FIG. 4A is an explanatory view of a working fluid leakage prevention device for an axial turbine according to a second embodiment of the present invention. FIG. 4A is a partially cutaway sectional view, and FIG. arrow A in a)
FIG. 4C is a partially cutaway perspective view of the seal ring 9 from a direction (axial direction).

The second embodiment is different from the first embodiment shown in FIGS. 1 to 3 in that the communication groove 16 for inserting the curved spring 17 is replaced by the outer peripheral side of each seal ring 9. The head 23 has a communication hole 22 communicating from the upstream side to the downstream side of the working fluid, and the curved spring 17 is inserted into the communication hole 22.

As shown in FIG. 4A, a plurality of seal rings 9 are circumferentially implanted on the inner periphery of the nozzle diaphragm inner ring 3, and seal fins 10 are fixed to the inner peripheral surface of the seal ring 9. Have been. There is a gap a between the rotating rotor 5 and the opposing seal fin 10, and the leaked fluid passes through the gap a in the direction of arrow b.

As shown in FIG. 4 (b), a plurality of communication holes 22 are formed in the head 23 on the outer periphery of the seal ring 9 so as to penetrate the upstream and downstream sides of the working fluid in the circumferential direction. ing. A curved spring 17 is inserted into the communication hole 22 in the implantation portion 8.
And the outer hook portion 18, the outer surface of the communication hole 22, and the downstream hook portion 19. The curved spring 17 has a function of bending so as to be in contact with the outer surface of the communication hole 22 and moving the seal ring 9 to the outer peripheral side.

A leaf spring 20 for pressing the seal ring 9 toward the center of the axis of the rotary rotor 5 is attached to the outer periphery of the seal ring 9. By providing the communication hole 22 and the curved spring 17, the same operation as in the first embodiment is provided. Since the gap a is wide in the low load region from the start of the turbine, excessive vibration does not occur and the seal fin 10 Can be prevented from being worn.

On the other hand, in the range from the intermediate load to the rated load, the gap a
Can be reduced, so that the leakage amount of the working fluid can be reduced. In the second embodiment, in the intermediate load region of the turbine, the seal ring 9 does not move irregularly when moving in the direction of the rotary rotor 5, so that trouble stop due to excessive vibration can be prevented, and the seal fins can be prevented. 10
The increase of the leakage fluid due to the abrasion can be prevented.

Next, a working fluid leakage prevention device for an axial turbine according to a third embodiment of the present invention will be described. FIG.
FIG. 5A is an explanatory view of a working fluid leakage prevention device for an axial flow turbine according to a third embodiment, and FIG. 5A shows a state in which a gap a2 is narrowed during a cold stop or a rated load operation. FIG. 5B shows a state in which the gap a1 is widened during warming with no load or low-load operation.

The third embodiment differs from the first embodiment shown in FIGS. 1 to 3 in that a plate-shaped elastic member 24 made of two different materials is used instead of the curved spring 17. It is like that. The elastic member 24 is composed of a plate-shaped expansion member 24a and a shape memory alloy 24b.

When the cooling of the turbine is stopped, as shown in FIG. 5A, the expansion member 24a of the elastic member 24 has a flat plate shape, and the shape memory alloy 24b has a flat plate shape. Accordingly, the seal ring 9 is moved in the direction of the center of the axis of the rotary rotor 5 by the pressing force Fs of the leaf spring 20, and the gap a is reduced to the gap a2.

On the other hand, during warming with no load or during low-load operation, as shown in FIG. 5B, the temperature of the expansion member 24a of the elastic member 24 becomes high so that the shape stored in the shape memory alloy 24b is obtained. The elastic member 24 bends. Thereby, the seal ring 9 is moved to the outer peripheral side with the upstream hook portion 18 and the downstream hook portion 19 of the implantation portion 8 as fulcrums, so that the gap a is widened and becomes the gap a1.

Further, during the rated load operation, FIG.
As shown in (1), the force Fr due to the pressure difference between the outer periphery and the inner periphery of the seal ring 9 becomes larger than the force for maintaining the shape of the elastic member 24 stored in the shape memory alloy 24b. It becomes a flat plate. Therefore, the seal ring 9 moves in the direction of the center of the axis of the rotating rotor 5, and the gap a is narrowed to become the gap a2.

FIG. 5 (c) shows a 2 having the above characteristics.
FIG. 9 is a characteristic diagram showing a change in a gap a during a turbine operation process when an elastic member 24 made of two different materials is used. When disassembling or assembling the turbine in a state where the cooling of the turbine is stopped, the elastic member 24 does not expand due to the low temperature, and the radial gap a is narrow.

On the other hand, when the turbine is warming, rotating up or down, or operating at a low load, the seal fins 10 and the rotating rotor 5 come into contact with each other due to thermal deformation of the turbine casing or the like and imbalance of the rotating rotor 5. Although easy, the temperature around the seal ring 9 rises, the elastic member 24 curves, and the radial gap a widens, so that axial vibration due to contact can be prevented. Further, during the rated load operation, the pressure difference between the outer peripheral pressure and the inner peripheral pressure of the seal ring 9 causes
The expansion member 24a of the elastic member 24 is compressed flat, and the gap a is reduced.

By using the elastic member 24, the gap a1 in the low load region where the seal fin 10 and the rotary rotor 5 are easily contacted can be increased, so that the axial vibration caused by the contact between the seal fin 10 and the rotary rotor 5 can be achieved. Can be prevented. Further, it is possible to make the gap during the rated load operation substantially the same as the gap when disassembling or assembling the turbine in the cold stopped state, and by measuring the gap a when the turbine is opened, the gap a during the rated output operation can be managed. In addition, it is possible to increase the leakage amount of the working fluid and reduce the shaft vibration caused by the contact.

[0065]

As described above, according to the present invention,
During the rated operation of the turbine, the gap between the rotating rotor of the axial flow type turbine stage and the seal ring attached to the inner ring of the nozzle diaphragm at the stationary part can be reduced, so the amount of leaked fluid passing through the gap can be reduced and the stage efficiency can be reduced. Can be improved. In addition, since the gap between the seal fins and the rotating rotor can be increased during the low-load unstable operation, generation of shaft vibration due to contact can be suppressed.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a working fluid leakage prevention device for an axial turbine according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a seal ring movement and a gap change in the working fluid leakage prevention device of the axial flow turbine according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a leaf spring on the outer periphery of a seal ring in the working fluid leakage prevention device for an axial turbine according to the first embodiment of the present invention.

FIG. 4 is an explanatory view of a working fluid leakage prevention device for an axial turbine according to a second embodiment of the present invention.

FIG. 5 is an explanatory view of a working fluid leakage prevention device for an axial turbine according to a third embodiment of the present invention.

FIG. 6 is an explanatory view of a conventional working fluid leakage prevention device (part 1) for an axial turbine.

FIG. 7 is an explanatory view of a conventional working fluid leakage prevention device (part 2) for an axial turbine.

FIG. 8 is an explanatory view of a conventional working fluid leakage prevention device (part 3) for an axial flow turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Casing 2 Nozzle diaphragm outer ring 3 Nozzle diaphragm inner ring 4 Nozzle 5 Rotor 6 Wheel 7 Moving blade 8 Implanted part 9 Seal ring 10 Seal fin 11 Bellows 12 Pressure hole 13 Hole 14 Spring 15 Gravity spring 16 Communication groove 17 Curved spring 18 Upstream side Hook 19 Downstream hook 20 Leaf spring 21 Both end faces 22 Communication hole 23 Head 24 Elastic member

Claims (9)

[Claims] 1. The method according to claim 1, further comprising: a rotating rotor of the axial flow turbine and an inner ring of a stationary nozzle diaphragm corresponding to the rotating rotor.
A plurality of seal rings are provided in the circumferential direction by providing an implanted portion on the inner ring of the nozzle diaphragm, and the seal ring can be moved in the radial direction of the rotating rotor shaft by a pressure difference between the outer periphery and the inner periphery of the seal ring. In the working fluid leakage prevention device for an axial flow turbine configured to prevent the working fluid of the axial flow turbine from leaking, at least an outer peripheral surface of the seal ring located on an upper half side of the rotating rotor is provided with each of the above-mentioned components. A leaf spring for pressing the seal ring in the direction of the center of the rotating rotor shaft so as to eliminate an imbalance in the pressing force caused by the weight of the seal ring; and a leaf spring inserted into a communication groove provided in each of the seal rings. A curve that engages with a hook portion formed on the implanted portion of the inner ring of the nozzle diaphragm and presses each of the seal rings in the outer peripheral direction. Ne working fluid leakage prevention apparatus of an axial flow turbine comprising the. 2. The working fluid leakage prevention device for an axial turbine according to claim 1, wherein the plate spring provided on the seal ring on the upper half of the rotary rotor is the seal ring on the lower half of the rotary rotor. The total length, width,
An apparatus for preventing a working fluid from leaking in an axial flow turbine, wherein one of the thicknesses is reduced so as to eliminate the imbalance in the pressing force caused by the weight of each of the seal rings. 3. The seal ring on the lower half side of the rotary rotor according to claim 1, wherein an imbalance in the pressing force caused by the weight of each of the seal rings is eliminated. A working fluid leakage prevention device for an axial turbine, wherein only the leaf spring is provided. 4. The working fluid leakage prevention device for an axial turbine according to claim 1, wherein the curved springs communicate with both end faces of each of the seal rings adjacent to each other from the upstream side to the downstream side of the working fluid. It is inserted into the provided communication groove, and is supported at three points of the upstream hook portion, the communication groove, and the downstream hook portion of the implant portion where the seal ring of the nozzle diaphragm inner ring is implanted. A working fluid leakage prevention device for an axial turbine. 5. The working fluid leakage prevention device for an axial flow turbine according to claim 1, wherein the curved spring communicates with a head on an outer peripheral side of each of the seal rings from an upstream side to a downstream side of the working fluid. The upstream hook portion, the communication hole, and the downstream hook portion of the implanted portion which is inserted into the provided communication hole and in which the seal ring of the nozzle diaphragm inner ring is implanted.
A working fluid leakage prevention device for an axial turbine, wherein the device is supported at a point. 6. One of claims 1 to 5
3. The working fluid leakage prevention device for an axial flow turbine according to claim 1, wherein a plate-shaped elastic member made of two different materials is used instead of the curved spring. . 7. The working fluid for an axial flow turbine according to claim 6, wherein the elastic member is formed of a plate-shaped expansion member and a shape memory alloy. Leak prevention device. 8. A radial gap formed between an inner peripheral surface of an implanted portion of the inner ring of the nozzle diaphragm and an outer peripheral surface of the seal ring in the hydraulic fluid leakage prevention device for an axial flow turbine according to claim 1. A working fluid leakage prevention device for an axial turbine, wherein the seal ring moves in a radial direction of the rotary rotor shaft when the load of the axial turbine increases or decreases. . 9. The working fluid leakage prevention device for an axial flow turbine according to claim 1, wherein when the working fluid presses the seal ring to a downstream side, the sealing ring comes into surface contact with an implanted portion of the inner ring of the nozzle diaphragm. A leakage prevention device for a working fluid of an axial turbine, wherein a corrosion-resistant coating or a surface hardening treatment is applied to a portion of a seal ring.