WO2012001997A1

WO2012001997A1 - Seal device and fluid machinery provided with same

Info

Publication number: WO2012001997A1
Application number: PCT/JP2011/051444
Authority: WO
Inventors: 平井　孝昌; 山下　勝也
Original assignee: 三菱重工業株式会社
Priority date: 2010-06-28
Filing date: 2011-01-26
Publication date: 2012-01-05
Also published as: JP2012007594A

Abstract

The disclosed seal device seals a radial gap of a rotation body formed between a casing and the outer circumference surface of the rotation body, which is rotatably arranged within the casing, and is provided with a seal unit, which limits fluids that flow from a high pressure side to a low pressure side, and a swirl breaker on the high pressure side of the seal unit, which extends from the casing to the outer circumference surface of the rotation body and limits fluids that flow in the circumferential direction of the rotation body through the aforementioned gap. The rotation body is provided with a stepped part that is formed in such a manner that the outer circumference surface of the rotation body reduces in diameter from the high pressure side to the low pressure side. The swirl breaker extends towards the outer circumference surface that is located closer to the low pressure side than to the stepped part. The tip of the swirl breaker reaches to a radial position identical to the outer circumference surface that is located closer to the high pressure side than to at least the stepped part.

Description

SEALING DEVICE AND FLUID MACHINE HAVING THE SAME

The present invention relates to a sealing device and a fluid machine including the same.
This application claims priority based on Japanese Patent Application No. 2010-146625 filed in Japan on June 28, 2010, the contents of which are incorporated herein by reference.

As is well known, in a fluid machine including a casing and a rotating body that is rotatably disposed in the casing, a seal portion that seals a radial gap formed between the casing and the rotating body is provided. It has been. As an example, in a multi-stage centrifugal compressor, an impeller outer peripheral portion in the vicinity of an impeller inlet of each stage, that is, an outer peripheral surface of a shroud disk, is composed of a rotating body provided in a plurality of stages in the axial direction and a housing that accommodates the rotating body. A labyrinth seal is provided in a radial gap between the housing and the inner periphery of the housing (see, for example, Patent Document 1 below).

In the fluid machine as described above, the seal excitation force acting on the shaft vibration increases with the high pressure and high performance of the fluid machine, and the shaft system instability problem tends to become remarkable. This excitation force is greatly influenced by a swirling flow (swirl) having a circumferential velocity component flowing along the outer periphery of the rotating body. That is, as a result of the swirling flow flowing into the seal portion, the natural frequency of the shaft system is excited, and the shaft vibration increases.

As a means for suppressing vibration due to this swirling flow, a sealing device is known in which a plurality of swirl breakers extending radially inward are provided on the high-pressure side of the labyrinth seal with an interval in the circumferential direction (for example, See Patent Document 2 below). By blocking the fluid (swirl flow) circulating in the circumferential direction by the swirl breaker, the fluid is decelerated to prevent an increase in vibration. In this sealing device, guide vanes are attached to a baffle plate attached to a swirl breaker along the flow direction of the swirl flow. By guiding the swirling flow with the guide vanes, the swirling flow is prevented from entering the labyrinth seal.

JP 2008-303767 A Japanese Patent No. 3492101

In order to prevent the occurrence of rotation loss due to friction between the swirl breaker and the rotating body, the tip of the swirl breaker is arranged with a slight gap from the rotating body. Therefore, the swirl flow can be interrupted in the range where the swirl breaker exists in the radial direction of the rotating body, while the swirling flow flows between the tip of the swirl breaker and the rotating body. As a result of the swirling flow reaching the seal portion, a seal excitation force acting on the shaft vibration is generated, and there is a problem that a sufficient vibration suppressing effect cannot be obtained.

In addition, like the sealing device of the above-mentioned patent document 2, the swirling flow is prevented from flowing into the gap between the tip of the swirl breaker and the rotating body by guiding the swirling flow in a desired direction with the guide vanes. It is also possible. However, the configuration of the sealing device itself is complicated by the additional provision of guide vanes, and there is a disadvantage that production costs and maintenance costs increase.

The present invention has been made in view of such circumstances, and an object thereof is to provide a sealing device and a fluid machine that can stably obtain a vibration suppressing effect with a simple configuration.

In order to achieve the above object, the present invention employs the following means.
The sealing device according to the present invention seals the radial gap of the rotating body formed between the casing and the outer peripheral surface of the rotating body that is rotatably disposed inside the casing so as to reduce the pressure from the high pressure side. A seal portion that suppresses fluid flowing toward the side, and a swirl breaker that extends from the casing toward the outer peripheral surface and suppresses fluid flowing in the circumferential direction on the high pressure side of the seal portion. The rotating body is provided with a stepped portion formed such that the outer peripheral surface is reduced in diameter as it goes from the high pressure side to the low pressure side, and the swirl breaker is located on the low pressure side than the stepped portion. It extends toward the outer peripheral surface, and the tip of the swirl breaker reaches at least the same radial position as the outer peripheral surface located on the high-pressure side from the stepped portion.

According to the sealing device having such a feature, the flow in the circumferential direction of the fluid, that is, all of the swirl flow can be guided to the swirl breaker by the outer peripheral surface on the high pressure side of the stepped portion in the rotating body. Therefore, it is possible to suppress the swirling flow from flowing between the swirl breaker and the rotating body. Furthermore, in addition to the swirl breaker and the seal portion, the above-described effect can be obtained only by performing a process for forming a stepped portion on the rotating body, so there is no need to provide a separate member.

The tip of the swirl breaker may reach the radially inner side from the outer peripheral surface located on the high pressure side of the stepped portion.

In this case, the outer peripheral surface on the high pressure side of the stepped portion and the tip of the swirl breaker are separated in the radial direction of the rotating body. Thereby, it becomes difficult for the swirl flow to reach the tip of the swirl breaker, and it is possible to further suppress the swirl flow from flowing into the gap between the swirl breaker and the rotating body.

The radial distance between the tip of the swirl breaker and the outer peripheral surface may be set to be substantially the same as the axial distance of the rotating body between the swirl breaker and the stepped portion.

In this case, the distance between the tip of the swirl breaker and the outer peripheral surface of the rotating body is usually set to be extremely narrow from the viewpoint of preventing the swirling flow from flowing into the gap. Therefore, by setting the distance between the swirl breaker and the stepped portion to be substantially the same as the distance between the tip of the swirl breaker and the outer peripheral surface of the rotating body, the swirl between the swirl breaker and the stepped portion turns. It is possible to prevent the flow from flowing in, and thus more reliably prevent the swirling flow from flowing between the swirl breaker and the rotating body.

A plurality of the seal portions are provided in the axial direction of the rotary body, and the swirl breakers are provided on the high pressure side of the seal portions, respectively, and the rotary body includes a plurality of the step portions so as to correspond to the swirl breakers. May be provided.

Here, even if the swirl flow is suppressed by the swirl breaker, the swirl flow may be generated again on the low pressure side of the swirl breaker due to the rotation of the rotating body.
On the other hand, the swirl flow generated on the low pressure side of the swirl breaker arranged on the highest pressure side is effectively achieved by arranging a plurality of seal parts and swirl breakers from the high pressure side to the low pressure side. It is possible to obtain a stable vibration suppressing effect for the entire shaft system.

A fluid machine according to the present invention includes a casing and a rotating body rotatably disposed in the casing, and the fluid machine in which a fluid flows in the casing includes any one of the above-described sealing devices. .

As a result, the swirl flow can be guided to the swirl breaker by the outer peripheral surface on the high pressure side of the stepped portion in the rotating body, so that the swirling flow is prevented from flowing into the gap between the swirl breaker and the rotating body. Can do.

The outer peripheral surface of the rotating body may be an outer peripheral surface of an impeller shroud, and the stepped portion may be provided on the outer peripheral surface of the shroud.

In this case, it is possible to suppress vibration based on the swirling flow in the outer peripheral portion of the impeller near the impeller inlet, that is, in the sealing device between the outer peripheral surface of the shroud of the impeller and the casing. In particular, since the outer peripheral surface of the shroud of the impeller can be easily changed in design, the sealing device of the present invention can be easily applied.

The outer peripheral surface of the rotating body may be an outer peripheral surface of a balance piston, and the step portion may be provided on the outer peripheral surface of the balance piston.

In this case, vibration based on the swirling flow in the sealing device between the outer peripheral surface of the balance piston and the casing can be suppressed.

According to the sealing device and the fluid machine of the present invention, the stepped portion is formed on the outer peripheral surface of the rotating body and the swirl flow is guided to the swirl breaker by the outer peripheral surface located on the high pressure side of the stepped portion in the rotating body. The swirling flow can be prevented from flowing between the swirl breaker and the rotating body. Therefore, it is possible to stably obtain the vibration suppressing effect with a simple configuration without providing a separate member or the like.

It is principal part sectional drawing of the compressor provided with the sealing device which concerns on 1st embodiment. FIG. 2 is a cross-sectional view taken along line AA in FIG. It is an enlarged view of the sealing device in FIG. It is a schematic block diagram of the compressor provided with the sealing device which concerns on 2nd embodiment. It is an enlarged view of the sealing device in FIG. It is a principal part enlarged view of the compressor provided with the sealing device which concerns on 3rd embodiment. It is a figure explaining the example which applied the sealing device to the steam turbine.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 3. In the present embodiment, an example in which the sealing device 1 is applied to a gap S between a shroud 17 of an impeller 14 and a casing 11 in a compressor (fluid machine) 10 is shown.
As shown in FIG. 1, the compressor 10 includes a casing 11 and a rotating body 12 having a rotor shaft 13 and an impeller 14.

The casing 11 has a cylindrical shape that forms the appearance of the compressor 10, and a rotor shaft 13 is disposed inside the casing 11 so as to penetrate the center. On both sides of the casing 11, radial bearings (not shown) and thrust bearings (not shown) are arranged. The rotor shaft 13 is supported by the radial bearing and the thrust bearing, so that the rotating body 12 can rotate around the axis O.

The impeller 14 is a so-called closed impeller, and includes a hub 15, a plurality of blades 16, and a shroud 17.
As shown in FIGS. 1 and 2, the hub 15 is a cylindrical disk member, and is integrally fixed to the rotor shaft 13 so that the rotor shaft 13 penetrates coaxially. The hub 15 has a shape that gradually increases in diameter from one side in the axis O direction (left side in FIG. 1) toward the other side in the axis O direction (right side in FIG. 1).

The blade 16 is a curved blade-like part, and extends from the outer peripheral surface 15a of the hub 15 toward the outer side of the axis O radial direction (hereinafter simply referred to as the radial direction), and is arranged along the outer peripheral surface 15a. Yes. A plurality of blades 16 are provided in the circumferential direction of the axis O (hereinafter simply referred to as the circumferential direction).

The shroud 17 is a part formed in a cylindrical shape so as to cover the outer peripheral surface 15 a of the hub 15, and is connected to the outer peripheral side in the radial direction of each blade 16. The outer peripheral surface 18 of the shroud 17 has a shape that gradually increases in diameter from one side in the direction of the axis O toward the other side.

In the impeller 14 having such a configuration, a space defined between the hub 15, the shroud 17, and the blade 16 serves as a fluid flow path. A portion opening toward the axis O direction on one side of the axis O direction is a gas inflow portion 14a, and a portion opening toward the radial direction on the other side of the axis O direction is a gas outflow portion 14b.

The casing 11 is provided with a suction port (not shown) for sucking fluid from the outside. The fluid sucked into the suction port is changed in the direction of the axis O by passing through the suction flow path 11a and is introduced into the gas inflow portion 14a of the impeller 14. On the other hand, the compressed fluid flowing out from the gas outflow portion 14 b is led out radially outward through the diffuser portion 11 b provided in the casing 11.

A gap S is formed between the shroud facing surface 11 c and the outer peripheral surface 18 of the shroud 17.

Here, in the impeller 14, since the fluid flowing in from the gas inflow portion 14a is compressed and flows out from the gas outflow portion 14b, the gas outflow portion 14b side has a higher pressure than the gas inflow portion 14a side. Accordingly, in the gap S, fluid flows from the impeller 14 outlet side (gas outflow portion 14b side), which is the high pressure side, toward the impeller 14 inlet side (gas inflow portion 14a side), which is the low pressure side. And the sealing apparatus 1 of this embodiment is used in order to seal the clearance gap S through which the fluid distribute | circulates in this way.

Hereinafter, the sealing device 1 will be described with reference to FIG. The sealing device 1 is provided on one side of the gap S in the direction of the axis O, that is, on the low pressure side of the gap S, and includes a labyrinth seal (seal part) 2 and a swirl breaker 3. Further, in the sealing device 1, the outer peripheral surface 18 of the shroud 17 in the impeller 14 is a component of the sealing device 1.

The labyrinth seal 2 is configured by a plurality of annular fins 2a extending inward in the radial direction from the shroud facing surface 11c in the casing 11 in the axis O direction. In the present embodiment, the outer peripheral surface 18 of the shroud 17 is larger in diameter than the small-diameter outer peripheral surface 18 a with the small-diameter outer peripheral surface 18 a forming one side in the axis O direction, the step surface 19, and the step surface 19 as a boundary. The large-diameter outer peripheral surface 18b is formed. The annular fin 2a extends so as to face the small-diameter outer peripheral surface 18a, that is, the labyrinth seal 2 is provided to face the small-diameter outer peripheral surface 18a in the radial direction. Thereby, the labyrinth seal 2 seals the existence area of the small-diameter outer peripheral surface 18a in the gap S, and fluid leaks in the gap S from the other side in the axis O direction to one side, that is, from the high pressure side to the low pressure side. To prevent it from happening.

The swirl breaker 3 is a plate-like member that extends radially inward from the shroud facing surface 11c on the other side in the axis O direction of the labyrinth seal 2, that is, on the high pressure side, and is spaced apart in the circumferential direction of the axis O. There are a plurality of open spaces. The swirl breaker 3 extends toward the small-diameter outer peripheral surface 18 a of the outer peripheral surface 18 of the shroud 17 like the annular fin 2 a of the labyrinth seal 2.

In the present embodiment, the tip 3a of the swirl breaker 3 extending radially inward from the shroud facing surface 11c as described above reaches the radially inner side than the large-diameter outer peripheral surface 18b. That is, the tip 3 a of the swirl breaker 3 reaches the radially inner side of the outer peripheral surface 18 on the high pressure side of the step surface 19. More specifically, the tip 3a of the swirl breaker 3 reaches radially inward from the boundary between the large-diameter outer peripheral surface 18b and the step surface 19 (the low-pressure end of the large-diameter outer peripheral surface 18b).

Therefore, when the swirl breaker 3 is viewed from the direction of the axis O, the tip 3a of the swirl breaker 3 enters a state radially inward from the large-diameter outer peripheral surface 18b. That is, when the swirl breaker 3 is viewed from the direction of the axis O, the swirl breaker 3 and the step surface 19 overlap each other in the direction of the axis O.
The radial distance between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 18a and the distance in the axis O direction between the swirl breaker 3 and the stepped surface 19 are narrowed to prevent the inflow of the swirl flow C, which will be described later. Is done. In particular, the distance between the swirl breaker 3 and the stepped surface 19 in the axis O direction is preferably set to be substantially the same as the distance between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 18a.

Next, the operation of the sealing device 1 will be described. When the rotor shaft 13 rotates, a shear force acts on the fluid around the outer peripheral surface 18 of the shroud 17 in the impeller 14 from the rotating body 12 in the rotational tangential direction, and the swirl having a circumferential speed component by the action of the shear force. Stream C is generated. The swirling flow C is directed from the high pressure side toward the low pressure side, that is, along the large-diameter outer peripheral surface 18b of the shroud 17 from the other side in the axis O direction to one side due to the pressure difference between both sides in the axis O direction of the gap S. Circulate.

Here, in this embodiment, since the swirl breaker 3 enters inward in the radial direction from the large-diameter outer peripheral surface 18b, the clearance S extends along the large-diameter outer peripheral surface 18b from the high-pressure side toward the low-pressure side. The swirling flow C flowing in this way is guided to the swirl breaker 3 by the large-diameter outer peripheral surface 18b. Therefore, all of the swirl flow C flowing along the large-diameter outer peripheral surface 18b can be blocked by the swirl breaker 3, so that the swirl flow C flows between the swirl breaker 3 and the small-diameter outer peripheral surface 18a. Can be suppressed. Therefore, since it is possible to prevent the swirling flow C from reaching the labyrinth seal 2, the natural frequency of the shaft system is not excited, and the impeller 14 is stably rotated without vibration. It becomes possible.

In the present embodiment, since the tip 3a of the swirl breaker 3 reaches the radially inner side with respect to the large-diameter outer peripheral surface 18b, the tip 3a of the swirl breaker 3 and the large-diameter outer peripheral surface 18b are in the radial direction. It is separated. Thereby, since the swirl flow C does not easily reach the tip 3a of the swirl breaker 3, it is possible to further suppress the swirl flow C from flowing between the swirl breaker 3 and the small-diameter outer peripheral surface 18a. .

Here, the interval between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 18a is normally set to be extremely narrow from the viewpoint of preventing the swirling flow C from flowing in. Therefore, when the distance between the swirl breaker 3 and the stepped surface 19 is set substantially the same as the distance between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 18a, the swirl breaker 3 and the stepped surface 19 It is possible to prevent the swirl flow C from flowing in between, and more reliably to prevent the swirl flow C from flowing between the swirl breaker 3 and the small-diameter outer peripheral surface 18a.

Further, in addition to the labyrinth seal 2 and the swirl breaker 3, the sealing device 1 of the present embodiment includes a small-diameter outer peripheral surface 18a, a large-diameter outer peripheral surface 18b, and a step surface on the outer peripheral surface 18 of the shroud 17 that is relatively easy to change. 19 can be realized only by performing the process of forming 19, and without adding other members other than the labyrinth seal 2 and the swirl breaker 3, the swirl breaker 3 and the small-diameter outer peripheral surface 18 a can be configured with a simple configuration. It is possible to suppress the swirling flow C from flowing in between.

In the present embodiment, the tip 3a of the swirl breaker 3 is configured to reach the radially inner side with respect to the large-diameter outer peripheral surface 18b. However, the tip 3a of the swirl breaker 3 is at least the same as the large-diameter outer peripheral surface 18b. That is, the radial position of the tip 3a of the swirl breaker 3 may coincide with the low-pressure end of the large-diameter outer peripheral surface 18b.
Also in this case, since the swirl flow C can be guided to the swirl breaker 3 by the large-diameter outer peripheral surface 18b, the swirl flow C is prevented from flowing between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 18b. Can do.

(Second embodiment)
Next, a second embodiment will be described in detail with reference to FIGS. In the present embodiment, an example in which the sealing device 1 is applied to a gap S between a balance piston 29 and a casing 28 in a so-called back-to-back compressor (fluid machine) 20 is shown.
As shown in FIG. 4, the compressor 20 of the present embodiment includes a rotor shaft 21, a low pressure section 22, a high pressure section 25, a balance piston (rotary body) 29, and a casing 28.

The rotor shaft 21 is rotatable about the axis O by supporting both ends of the rotor shaft 21 with a radial bearing (not shown) and a thrust bearing (not shown), for example.

The low pressure section 22 includes a low pressure side impeller 23 and a gas flow path 24 dug in the casing 28.
The low-pressure side impeller 23 has a gas passage defined by a hub, blades, and a shroud. The gas passage has a rotor shaft 21 side as a gas inlet 23a and a side away from the rotor shaft 21 has a gas outlet 23b. Has been. The low pressure side impeller 23 is arranged in a state where the gas inlet 23a is directed to one side of the axis O (left side in FIG. 4).

The gas flow path 24 includes a low pressure suction path 24a connecting a gas source (not shown) and a gas inlet 23a of the low pressure side impeller 23, and a low pressure discharge path 24b communicating from the gas outlet 23b of the low pressure side impeller 23 to the outside of the system. Yes.

The high pressure section 25 includes a high pressure side impeller 26 and a gas flow path 27 dug in the casing 28.
The high-pressure side impeller 26 has a gas passage defined by a hub, blades, and a shroud. The gas passage 26 has a gas inlet 26a on the rotor shaft 21 side and a gas outlet 26b on the side away from the rotor shaft 21. Has been. The high pressure side impeller 26 is arranged with the gas inlet 26a facing the other side of the axis O (the right side in FIG. 4). Therefore, the low-pressure side impeller 23 of the low-pressure section 22 and the high-pressure side impeller 26 of the high-pressure section 25 are disposed so as to face each other, and the compressor 20 disposed in this way is configured to be back-to-back (Back To Back). Back) type.

The gas flow path 27 includes a high-pressure suction path 27a that communicates gas introduced from the low-pressure discharge path 24b via a device such as an external intercooler to the gas inlet 26a of the high-pressure side impeller 26, and the high-pressure side impeller. And a high-pressure discharge passage 27b communicating from the gas outlet 26b to the outside of the system.

The balance piston 29 is provided between the low pressure section 22 and the high pressure section 25. The balance piston 29 has a substantially cylindrical shape, and is fixed integrally with the rotor shaft 21 by being fitted on the outer peripheral side of the rotor shaft 21. This balance piston 29 adjusts the load balance in the axis O direction of the rotor shaft 21 by resisting a load toward one side in the axis O direction caused by the pressure difference between the low pressure side impeller 23 and the high pressure side impeller 26. Have a role.

The outer peripheral surface 30 of the balance piston 29 has a small-diameter outer peripheral surface 30a that corresponds to the entire area in the axis O direction except for the vicinity of the other end on the other side of the axis O. Further, a portion of the outer peripheral surface 30 located on the other side (high pressure side) of the small-diameter outer peripheral surface 30a in the axis O direction, that is, a portion near the end on the other side in the axis O direction expands from the small-diameter outer peripheral surface 30a by one step. The outer peripheral surface 30b is a large diameter. In other words, the large-diameter outer peripheral surface 30b having a flange shape is provided at one end of the balance piston 29 in the direction of the axis O, and the entire region excluding the large-diameter outer peripheral surface 30b is larger than the large-diameter outer peripheral surface 30b. Is also a small-diameter outer peripheral surface 30a having a reduced diameter by one step.

A surface facing one side in the axis O direction, which is a transition region between the small-diameter outer peripheral surface 30a and the large-diameter outer peripheral surface 30b, is a step surface (step portion) 31 that is flat and orthogonal to the axis O. .
That is, the balance piston 29 is provided with a stepped surface 31 formed so that its outer peripheral surface 30 is reduced in diameter by one step from the other side (high pressure side) in the axis O direction toward one side (low pressure side). . The outer peripheral surface 18 positioned on one side in the axis O direction with respect to the step surface 31 is a small-diameter outer peripheral surface 30a, and the outer peripheral surface 30 positioned on the other side in the axis O direction with respect to the step surface 31 is a large-diameter outer peripheral surface 30b. It has become.

Here, the surface of the casing 28 facing the outer peripheral surface 30 of the balance piston 29 is a piston facing surface 28a. A gap S is formed between the outer peripheral surface 30 of the balance piston 29 and the piston facing surface 28 a of the casing 28. In the gap S, the fluid flows from the high pressure side impeller 26 side of the high pressure section 25 toward the low pressure side impeller 23 side of the low pressure section 22. In this embodiment, the sealing device 1 is used to seal the gap S through which the fluid flows in this way.

Hereinafter, the sealing device 1 of the second embodiment will be described with reference to FIG. Similar to the first embodiment, the seal device 1 of the second embodiment includes a labyrinth seal (seal part) 2 and a swirl breaker 3, and the outer peripheral surface 30 of the balance piston 29 is the same as that of the seal device 1. It is a component.

The labyrinth seal 2 is configured by a plurality of annular fins 2 a extending inward in the radial direction from the piston facing surface 28 a in the casing 28 in the axis O direction. In the present embodiment, these annular fins 2a extend so as to oppose the small-diameter outer peripheral surface 30a of the outer peripheral surface 30 of the balance piston 29. That is, the labyrinth seal 2 is in the radial direction with respect to the entire area of the small-diameter outer peripheral surface 18a. It is provided facing. Thereby, the labyrinth seal 2 seals the gap S and prevents the fluid from leaking from the other side in the axis O direction to the one side, that is, from the high pressure side to the low pressure side. Yes.

The swirl breaker 3 extends radially inward from the piston facing surface 28a on the other side in the axis O direction of the labyrinth seal 2, that is, on the high pressure side, and a plurality of swirl breakers 3 are provided at intervals in the circumferential direction of the axis O. Yes. Like the annular fin 2a of the labyrinth seal 2, the swirl breaker 3 extends toward the small-diameter outer peripheral surface 18a of the piston facing surface 28a, that is, extends toward the outer peripheral surface 30 on the low pressure side of the step surface 31. Yes.

And in this embodiment, the front-end | tip 3a of the swirl breaker 3 extended toward the radial inside from the piston opposing surface 28a has reached the radial inside rather than the large diameter outer peripheral surface 30b. That is, the tip of the swirl breaker 3 reaches the inside in the O-diameter direction from the boundary between the large-diameter outer peripheral surface 30b and the stepped surface 31 (the low-pressure end of the large-diameter outer peripheral surface 30b).

Therefore, when the swirl breaker 3 is viewed from the direction of the axis O, the tip 3a of the swirl breaker 3 enters a state radially inward from the large-diameter outer peripheral surface 30b. That is, when the swirl breaker 3 is viewed from the direction of the axis O as in the first embodiment, the swirl breaker 3 and the stepped surface 31 overlap each other in the direction of the axis O.
In addition, it is preferable that the space | interval of the axis line O direction of the swirl breaker 3 and the level | step difference surface 31 is set substantially the same as the space | interval of the radial direction of the front-end | tip 3a of the swirl breaker 3, and the small diameter outer peripheral surface 30a.

Also in the sealing device 1 of the second embodiment, the swirl flow entering the gap S because the swirl breaker 3 enters radially inward from the large-diameter outer peripheral surface 30b as in the first embodiment. C is guided to the swirl breaker 3 by the large-diameter outer peripheral surface 30b.
Therefore, all of the swirl flow C flowing along the large-diameter outer peripheral surface 30b can be blocked by the swirl breaker 3, so that the swirl flow C flows between the swirl breaker 3 and the small-diameter outer peripheral surface 18a. Can be suppressed. As a result, the swirling flow C can be prevented from reaching the labyrinth seal 2, so that the natural frequency of the shaft system is not excited, and the balance piston 29 can be stably kept in a vibration-free state. It can be rotated.

In the present embodiment, the tip 3a of the swirl breaker 3 only needs to reach at least the same radial position as the large-diameter outer peripheral surface 30b. Also in this case, since the swirl flow C can be guided to the swirl breaker 3 by the large-diameter outer peripheral surface 30b, the swirl flow C is prevented from flowing between the tip 3a of the swirl breaker 3 and the small-diameter outer peripheral surface 30a. Can do.

(Third embodiment)
Next, a third embodiment will be described in detail with reference to FIG. The sealing device 40 of the third embodiment is disposed in the gap S between the balance piston 29 and the casing 28 in the compressor 20 as in the second embodiment. The sealing device 1 of the second embodiment has a configuration in which the single labyrinth seal 2 and the swirl breaker 3 are arranged, whereas the sealing device 40 of the present embodiment includes a plurality of (two in this embodiment). ) Labyrinth seal 2 (2A, 2B) and swirl breaker 3 (3A, 3B). Accordingly, the outer peripheral surface 32 of the balance piston 29 is formed in a multistage shape.

That is, the outer peripheral surface 32 of the balance piston 29 of the present embodiment includes a first outer peripheral surface 32a and the first outer peripheral surface from the high pressure side (the other side in the axis O direction) toward the low pressure side (the one side in the axis O direction). The second outer peripheral surface 32b having a one-step diameter reduction from 32a and the third outer peripheral surface 32c having a one-step diameter reduction from the second outer peripheral surface 32b are sequentially arranged. And the surface which faces the low voltage | pressure side which is a transition area | region of the 1st outer peripheral surface 32a and the 2nd outer peripheral surface 32b is made into the 1st step surface (step part) 33a, and the 2nd outer peripheral surface 32b and the 3rd outer peripheral surface 32c A surface facing the low pressure side, which is a transition region, is a second step surface (step portion) 33b.

The labyrinth seals 2A and 2B are composed of a plurality of annular fins 2a extending radially inward from the piston facing surface 28a of the casing 28, as in the second embodiment. The first labyrinth seal 2A is provided to face the second outer peripheral surface 32b, and the second labyrinth seal 2B is provided to face the third outer peripheral surface 32c.

Of the two

swirl breakers

3A and 3B, the first swirl breaker 3A is arranged so as to extend toward the second outer peripheral surface 32b on the high pressure side of the first labyrinth seal 2A. The swirl breaker 3B is arranged to extend toward the third outer peripheral surface 32c on the high pressure side of the second labyrinth seal 2B.

Also in the present embodiment, the tip 3a of the first swirl breaker 3A reaches radially inward from the first outer peripheral surface 32a, and the tip 3a of the second swirl breaker 3B is from the second outer peripheral surface 32b. Has also reached the inside in the radial direction.

According to the sealing device 40 of the third embodiment having such a configuration, the swirl flow entering from the high pressure side of the gap S is guided to the swirl breaker 3 by the large-diameter outer peripheral surface 30b. This prevents the swirl flow C from flowing into the first labyrinth seal 2A beyond the first swirl breaker 3A.

Here, even if the swirl flow C is suppressed by the first swirl breaker 3A, the fluid is accompanied by the rotation of the balance piston 29, so that the low pressure side of the first swirl breaker 3A, that is, the first labyrinth seal 2A. And a swirling flow C may occur between the first outer peripheral surface 32b and the second outer peripheral surface 32b.
In this regard, in the present embodiment, since the second swirl breaker 3B is disposed on the low pressure side of the first labyrinth seal 2A, the swirl flow C is guided to the second swirl breaker 3B by the second outer peripheral surface 32b. can do.

Thus, the swirl flow generated on the low pressure side of the swirl breaker 3 arranged on the highest pressure side by arranging a plurality of sets of labyrinth seals 2 and swirl breakers 3 from the high pressure side to the low pressure side. Can be effectively suppressed. Therefore, even if the gap S in which the sealing device 40 is provided is formed long in the direction of the axis O, it is possible to effectively suppress the swirling flow C and obtain a stable vibration suppressing effect as the entire shaft system. .

As described above, the embodiments of the present invention have been described in detail. However, the present invention is not limited to these without departing from the technical idea of the present invention, and some design changes and the like are possible.

For example, in the embodiment, the example in which the labyrinth seal 2 is employed as the seal portion has been described, but a damper seal having a honeycomb structure may be employed instead of the labyrinth seal 2.

Moreover, also in the sealing device 1 provided in the gap S between the shroud 17 and the casing 11 in the first embodiment, a plurality of labyrinth seals 2 and swirl breakers 3 are provided as in the third embodiment, and an outer periphery corresponding to these. The surface 18 may have a plurality of stages.

Furthermore, instead of providing the labyrinth seal 2 on the

casings

11 and 28, the labyrinth seal 2 may be provided on the rotating body side, that is, on the shroud 17 or the balance piston 29.

Further, in the embodiment, the example in which the sealing device 1 is applied to the

compressors

10 and 20 has been described. However, for example, as illustrated in FIG. 7, the sealing device 1 may be applied to a steam turbine.
In the steam turbine 50 of FIG. 7, a nozzle is incorporated in a partition plate 56 fixed to a casing 55, and a rotor shaft (rotary body) 51 is generated by a thrust force when steam passing through the nozzle passes through a moving blade. It is set as the structure which rotates.

Further, the labyrinth seal 2 is provided between the casing 55 and the rotor shaft 51, and the outer periphery of the rotor shaft 51 is disposed on the high pressure side of the labyrinth seal 2, that is, on the other side of the axis O (left side in FIG. 7). A step surface 51a and a large-diameter outer peripheral surface 51b are formed so that the surface is enlarged by one step. A swirl breaker 3 is provided between the labyrinth seal 2 and the large-diameter outer peripheral surface 51 b so as to extend from the casing 55 toward the rotor shaft 51. The tip 3a of the swirl breaker 3 reaches the radially inner side with respect to the large-diameter outer peripheral surface 51b.

Accordingly, the swirl flow C flowing from the high pressure side toward the low pressure side can be guided to the swirl breaker 3 by the large-diameter outer peripheral surface 51b, and thus the swirl flow C flows into the labyrinth seal 2 as in the embodiment. This can be suppressed. Also in this steam turbine 50, instead of the sealing device 1, a sealing device 40 including a plurality of labyrinth seals 2 and swirl breakers 3 may be applied as in the third embodiment.

Furthermore, the

sealing devices

1 and 40 may be applied not only to the compressor and the steam turbine but also to other fluid machines such as a gas turbine, a water turbine, a refrigerator, and a pump.

According to the sealing device and the fluid machine of the present invention, a vibration suppressing effect can be stably obtained with a simple configuration.

1 Sealing device 2 Labyrinth seal (seal part)
2A Labyrinth seal (seal part)
2B Labyrinth seal (seal part)
2a annular fin 3 swirl breaker

3A swirl breaker

3B swirl breaker 3a tip 10 compressor 11 casing 11c shroud facing surface 12 rotor 13 rotor shaft 14 impeller 17 shroud 18 outer peripheral surface 18a small diameter outer peripheral surface 18b large diameter outer peripheral surface 19 step surface (step Part)
20 Compressor 21 Rotor shaft 28 Casing 28a Piston facing surface 29 Balance piston 30 Outer peripheral surface 30a Small outer peripheral surface 30b Large outer peripheral surface 31 Step surface 32 Outer peripheral surface 32a First outer peripheral surface 32b Second outer peripheral surface 32c Third outer peripheral surface 33a First One step surface 33b Second step surface 40 Sealing device 50 Steam turbine 51 Rotor shaft (rotating body)
51a Step surface (step)
51b Large-diameter outer peripheral surface 55 Casing

Claims

Sealing the gap in the radial direction of the rotating body formed between the casing and the outer peripheral surface of the rotating body that is rotatably arranged inside the casing, the fluid flowing from the high pressure side toward the low pressure side A seal part to suppress,
A swirl breaker that extends from the casing toward the outer peripheral surface on the high pressure side of the seal portion and suppresses fluid flowing through the gap in the circumferential direction of the rotating body;
The rotating body is provided with a stepped portion formed so that the outer peripheral surface is reduced in diameter as it goes from the high pressure side to the low pressure side,
The swirl breaker extends toward the outer peripheral surface located on the lower pressure side than the stepped portion,
A sealing device in which a tip of the swirl breaker reaches at least the same radial position as the outer peripheral surface located on the high pressure side of the stepped portion.
The sealing device according to claim 1, wherein a tip of the swirl breaker reaches the radially inner side with respect to the outer peripheral surface located on the high pressure side of the stepped portion.
2. The radial distance between the tip of the swirl breaker and the outer peripheral surface is set to be substantially the same as the axial distance of the rotating body between the swirl breaker and the stepped portion. Sealing device.
A plurality of the seal portions are provided in the axial direction of the rotating body, and the swirl breaker is provided on the high pressure side of each seal portion,
The sealing device according to claim 1, wherein the rotating body is provided with a plurality of the stepped portions so as to correspond to the swirl breakers.
In a fluid machine comprising a casing and a rotating body rotatably arranged in the casing, wherein a fluid flows in the casing,
A fluid machine comprising the sealing device according to any one of claims 1 to 4.
The outer peripheral surface of the rotating body is an outer peripheral surface of an impeller shroud,
The fluid machine according to claim 5, wherein the step portion is provided on an outer peripheral surface of the shroud.
The outer peripheral surface of the rotating body is an outer peripheral surface of a balance piston,
The fluid machine according to claim 5, wherein the step portion is provided on an outer peripheral surface of the balance piston.