JP2011012631A - Turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-performance turbine small in the amount of fluid leaking to the downstream of rotor blades.SOLUTION: The turbine 1 includes a stationary annular body 11, a shaft rotatably provided inside the stationary annular body 11, the plurality of rotor blades radially provided on the shaft and having respective ends 51 facing the inner periphery 11b of the stationary annular body 11 via a radial clearance Gd, and seal fins 17 extending radially inward from the inner periphery 11b of the stationary annular body 11 and forming a minute clearance m with the ends 51 of the rotor blades. A vortex flow forming chamber R with a downstream side partitioned by the seal fin 17 is provided on an upstream side of the radial clearance Gd. The vortex flow forming chamber R has an inlet opening O through which fluid S on a main flow side flows in radially outward, and forms a vortex flow so that the fluid S reaching a downstream side flows radially inward along the seal fin 17.

Description

  The present invention relates to a turbine used in, for example, a power plant, a chemical plant, a gas plant, a steel mill, a ship, and the like.

  As is well known, as a kind of steam turbine, a casing, a shaft body rotatably provided inside the casing, a plurality of stationary blades fixedly disposed on the inner peripheral portion of the casing, and a plurality of these stationary blades Some have a plurality of blades provided radially on the shaft body on the downstream side. In the case of an impulse turbine among such steam turbines, the pressure energy of steam is converted into velocity energy by a stationary blade, and this velocity energy is converted into rotational energy (mechanical energy) by the blade. In the case of a reaction turbine, pressure energy is also converted into velocity energy even in the rotor blade, and is converted into rotational energy (mechanical energy) by reaction force from which steam is ejected.

  In such a steam turbine, a radial gap is usually formed between the tip of the moving blade and a casing surrounding the moving blade to form a steam flow path. The leaked steam that passes downstream does not give a rotational force to the moving blade. For this reason, in order to improve the performance of the steam turbine, it is important to reduce the amount of leaked steam that passes through the radial gap.

  In Patent Document 1 below, the high pressure fluid side of the tip of the seal fin is formed at right angles to the rotor blade, and the low pressure fluid side is formed in an inclined shape, and a plurality of the seal fins are arranged in series in the axial direction. Has been established. With such a configuration, the steam is prevented from passing through the radial gap by generating a large vortex of steam between the seal fins so as to lose energy.

JP 2005-180278 A

  However, in the conventional technology, since a large vortex flow of steam generated between the seal fins is formed so as to be directed toward the radial gap of the tooth tip of the downstream seal fin, the amount of leaked steam is sufficiently reduced. There was a problem that it could not be reduced.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a high-performance turbine with less leakage fluid.

In order to achieve the above object, the present invention employs the following means.
That is, the turbine according to the present invention includes a stationary annular body, a shaft body rotatably provided inside the stationary annular body, a plurality of radial bodies provided on the shaft body, and respective tip portions thereof. A moving blade that opposes the inner peripheral portion of the stationary annular body via a radial gap, and extends from the inner peripheral portion of the stationary annular body toward the radially inward side to form a minute amount with the tip of the moving blade. A turbine having a seal fin that forms a gap, and a vortex forming chamber having a downstream side partitioned by the seal fin is provided on the upstream side of the radial gap. An inflow port through which fluid flows in radially outward is formed, and a vortex is formed so that the fluid reaching the downstream side is directed radially inward along the seal fin. To do.

According to this configuration, the vortex flow forming chamber is provided, the vortex flow forming chamber has the inflow port through which the fluid on the main flow side flows toward the radially outer side, and the fluid that has reached the downstream side is supplied to the seal fin. A vortex is formed so as to be directed radially inward along. That is, the fluid flowing into the vortex forming chamber flows toward the radially outer side on the upstream side, flows toward the downstream side on the radially outer side, and radially inward along the seal fin on the downstream side. Then, a vortex flow that flows toward the upstream side is formed on the radially inward side. As a result, the pressure on the upstream side of the minute gap communicating with the vortex forming chamber is reduced, so that it is difficult for the fluid to leak downstream from the minute gap.
Accordingly, the amount of fluid leaking from the vortex forming chamber can be reduced, and the amount of leaked fluid passing through the radial gap between the tip of the moving blade and the inner peripheral portion of the stationary annular body can be reduced.
Therefore, the energy of the fluid can be efficiently converted into rotational energy, and a high-performance turbine can be provided.

Further, the stationary annular body includes an outer partition section that divides a radially outer side of the vortex forming chamber in the inner peripheral section, and the outer partition section is close to a tip portion of the moving blade. The radial gap is small.
According to this configuration, since the outer partition section that divides the radially outer side of the vortex flow forming chamber is provided and the outer partition section is close to the tip of the moving blade, the size of the vortex flow forming chamber is reduced. The smaller the distance that the vortex flow contacts with the wall forming the vortex flow chamber, the vortex rotation speed can be kept in the vortex flow chamber as it is close to the inflow velocity without being attenuated. Become stronger. As a result, the pressure on the upstream side of the minute gap communicating with the vortex forming chamber is further reduced, so that the amount of fluid leaking from the minute gap can be further reduced.

The stationary annular body includes an upstream partition portion that is formed on the upstream side of the rotor blade and partitions the upstream side of the vortex forming chamber, and the upstream partition portion and the tip portion upstream of the rotor blade The gap is defined as the inflow port.
According to this configuration, since the upstream section that divides the upstream side of the vortex flow forming chamber is formed on the upstream side of the moving blade, the tip end portion of the moving blade is relatively radially out of position due to centrifugal elongation during operation. Even if it is displaced to the side, it is possible to prevent the tip of the moving blade from interfering with the upstream partition.
In addition, since the gap between the upstream section and the upstream side of the tip of the rotor blade is the inlet of the vortex forming chamber, the vortex forming chamber can be realized with a simple configuration.

Further, the upstream partition portion is formed by forming a part of the stationary annular body with a small diameter.
According to this configuration, since the upstream partition portion is formed such that a part of the stationary annular body has a small diameter, the assembling work can be simplified.

Further, the upstream partition portion is a fin member provided on the stationary annular body.
According to this configuration, since the upstream partition is a fin member provided on the stationary annular body, the tip of the moving blade is relatively displaced and the tip of the moving blade and the upstream partition are in contact with each other. Even so, although it is inferior in strength and rigidity to the moving blades and stationary annular bodies, it is possible to suppress damage to the moving blades and stationary annular bodies by crushing the fin members that are much cheaper and easy to replace. .

Further, the upstream partition portion includes an extending portion extending radially inward from the stationary annular body, and an axial extending portion extending in the axial direction from the distal end of the extending portion. The cross-sectional shape along the line is L-shaped.
According to this configuration, since the cross-sectional shape along the axial direction is L-shaped, the tip of the moving blade is displaced relatively upstream in a range where the tip of the moving blade does not contact the upstream partition. In the case of overlapping in the axial direction, a fluid flow path is formed by the axially extending portion and the blade tip, so that the pressure loss when the fluid passes is increased and the downstream side thereof It is possible to reduce the amount of fluid flowing into the radial gap.

Further, when the axial dimension of the vortex forming chamber is B and the axial dimension of the gap between the upstream partition and the tip of the rotor blade is ΔB, the relation of 0.5B> ΔB is satisfied. It is characterized by.
According to this configuration, since the relationship 0.5B> ΔB is established, the amount and direction of the fluid flowing into the vortex forming chamber can be stabilized, and the vortex can be formed more stably.

Further, the upstream partition portion is located radially outward from the upstream side of the tip end portion of the moving blade.
According to this configuration, since the upstream section is located radially outward from the upstream side of the tip of the rotor blade, the tip of the rotor blade is displaced relatively upstream due to thermal elongation or pressure difference. Even if it does, it can suppress that the front-end | tip part of a moving blade interferes with an upstream division part.

When the radial dimension of the gap between the upstream section and the upstream end of the rotor blade is ΔH, and the axial dimension of the gap between the upstream section and the tip upstream of the rotor blade is ΔB Further, it has a relationship of ΔH <ΔB.
According to this configuration, since the relationship of ΔH <ΔB is satisfied, the velocity component in the radial direction of the fluid flowing into the vortex flow forming chamber can be increased to stabilize the vortex flow direction.

The stationary annular body has a facing surface that extends radially inward from the inner peripheral portion and faces the end surface of the tip of the moving blade via an axial gap, A circumferential groove that is recessed in the axial direction and extends in the circumferential direction is formed, and a tip portion of the moving blade extends from the end surface of the tip portion toward the axial direction in the circumferential groove and An axial seal fin that forms a minute gap with a groove wall surface in the radial direction is provided, and the circumferential groove and the axial seal fin constitute a seal unit.
According to this configuration, the stationary annular body has a facing surface that faces the end surface of the tip of the moving blade via the axial gap, is formed on the facing surface, is recessed in the axial direction, and extends in the circumferential direction. Since the circumferential groove and the axial seal fin that forms the minute gap and the groove wall surface in the radial direction of the circumferential groove constitute a seal unit, the fluid flowing from the main flow into the vortex forming chamber, in other words, the moving blade It is possible to reduce the amount of leaked fluid that passes through the radial gap between the front end portion and the inner peripheral portion of the stationary annular body and joins the main flow.
Even if the tip of the rotor blade is relatively displaced in the axial direction due to thermal expansion or pressure difference, the axial seal fin is displaced in the circumferential groove, so that the axial seal fin and the stationary annular body interfere with each other. Can be deterred.

In addition, a plurality of the seal units are provided at intervals in the radial direction.
According to this configuration, the fluid flowing from the main flow into the vortex forming chamber, in other words, the leakage fluid that passes through the radial gap between the tip of the rotor blade and the inner peripheral portion of the stationary annular body and merges with the main flow is further reduced. It becomes possible to do.

Further, the facing surface of the stationary annular body extends in the axial direction from the radially outer side toward the inner side so as to go toward the recess direction side of the circumferential groove, and the tip end surface has a diameter of The plurality of axial seal fins extend in a flat shape from the outer side in the direction, and the axial seal fin on the radially inner side is more than the axial seal fin on the radially outer side. The axial dimension is increased.
According to this configuration, since the facing surface of the stationary annular body extends from the radially outer side toward the inner side so as to extend toward the recess direction side of the circumferential groove in the axial direction, By making the annular body into half cracks, assembly and disassembly can be easily performed.

Further, the facing surface of the stationary annular body extends in the axial direction from the radially outer side toward the inner side so as to go toward the recess direction side of the circumferential groove, and the tip end surface has a diameter of It extends so that it may go to the hollow direction side of the circumferential groove of the opposing surface which opposes among axial directions as it goes inward from the direction outside.
According to this configuration, since the facing surface of the stationary annular body extends from the radially outer side toward the inner side so as to extend toward the recess direction side of the circumferential groove in the axial direction, By making the annular body into half cracks, assembly and disassembly can be easily performed.

  According to the present invention, it is possible to provide a high-performance turbine with less leakage fluid.

It is a schematic structure sectional view of steam turbine 1 concerning a first embodiment of the present invention. It is a principal part expanded sectional view of the steam turbine 1 which concerns on 1st embodiment of this invention, and is an expanded sectional view of the principal part I in FIG. It is a principal part expanded sectional view of the steam turbine 1 which concerns on 1st embodiment of this invention, and is a partially expanded view of FIG. It is operation | movement explanatory drawing of the steam turbine 1 which concerns on 1st embodiment of this invention. It is a principal part expanded sectional view of the steam turbine 2 which is a modification of 1st embodiment of this invention, and is a figure equivalent to FIG. 2 which concerns on 1st embodiment. It is a principal part expanded sectional view of the steam turbine 3 which concerns on the 1st reference example of this invention, and is a figure equivalent to FIG. 2 which concerns on 1st embodiment. It is a principal part expanded sectional view of the steam turbine 4 which concerns on the 2nd reference example of this invention, and is a figure equivalent to FIG. 2 which concerns on 1st embodiment. It is a principal part expanded sectional view of the steam turbine 5 which concerns on the 3rd reference example of this invention, and is a figure equivalent to FIG. 2 which concerns on 1st embodiment. It is a principal part expanded sectional view of the steam turbine 6 which concerns on 2nd embodiment of this invention, and is a figure equivalent to FIG. 2 which concerns on 1st embodiment. It is a figure which shows the modification of the steam turbine 6 which concerns on 2nd embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a schematic cross-sectional view showing a steam turbine 1 according to a first embodiment of the present invention.
The steam turbine 1 is provided in a casing 10, a regulating valve 20 that adjusts the amount and pressure of the steam S flowing into the casing 10, and an inward rotation of the casing 10. The main structure includes a shaft body 30 to be transmitted, a stationary blade 40 held in the casing 10, a moving blade 50 provided on the shaft body 30, and a bearing portion 60 that rotatably supports the shaft body 30 about its axis. Yes.

  The casing 10 has an internal space hermetically sealed and a flow path for the steam S. A ring-shaped partition plate outer ring (stationary annular body) 11 through which the shaft body 30 is inserted is firmly fixed to the inner wall surface of the casing 10.

  A plurality of regulating valves 20 are attached to the inside of the casing 10, and each includes a regulating valve chamber 21 into which steam S flows from a boiler (not shown), a valve body 22, and a valve seat 23. When the valve seat 23 is separated from the valve seat 23, the steam flow path is opened, and the steam S flows into the internal space of the casing 10 through the steam chamber 24.

  The shaft body 30 includes a shaft body 31 and a plurality of disks 32 extending from the outer periphery of the shaft body 31 in the entire radial direction. The shaft body 30 transmits rotational energy to a machine such as a generator (not shown).

  A large number of the stationary blades 40 are arranged radially so as to surround the shaft body 30 to form an annular stationary blade group, and are respectively held by the partition plate outer ring 11 described above. The inner sides of the stationary blades 40 in the radial direction are connected by a ring-shaped partition plate inner ring 12 through which the shaft body 30 is inserted.

  The group of annular stator blades composed of the plurality of stator blades 40 is formed at intervals in the axial direction, and the pressure energy of the steam S is converted into velocity energy, and the moving blade 50 adjacent to the downstream side Let it flow.

  The rotor blade 50 is firmly attached to the outer peripheral portion of the disk 32 included in the shaft body 30. A large number of the moving blades 50 are arranged radially on the downstream side of each annular stationary blade group to constitute the annular moving blade group.

  These annular stator blade groups and annular rotor blade groups are grouped into one stage. That is, the steam turbine 1 is configured in six stages. Among these, the front-end | tip part of the moving blade 50 in the last stage is made into the shroud 51 extended in the circumferential direction.

2 is an enlarged cross-sectional view of the main part showing the main part I in FIG. 1, and FIG. 3 is an enlarged view of a part of FIG.
As shown in FIG. 2, the shroud 51 includes a step portion 52 (52 </ b> A to 52 </ b> C) formed in a step shape with a central portion protruding in the axial direction. The shroud 51 is opposed to the partition plate outer ring 11 via a radial gap Gd in the radial direction.

As shown in FIG. 2, the partition plate outer ring 11 is formed with an annular groove 11a on the inner periphery, and a shroud 51 is accommodated in the annular groove 11a.
A groove bottom (inner peripheral portion) 11b of the annular groove 11a is formed in a step shape. Specifically, from the bottom 13 having the largest inner diameter on the downstream side, the outer partition 14 adjacent to the bottom 13 on the upstream side, and the upstream partition 15 adjacent to the outer partition 14 on the upstream side. It is configured.

As shown in FIG. 2, the bottom portion 13 is located on the most downstream side of the groove bottom 11b, and faces the downstream side of the step portion 52A and the step portions 52B and 52C in the radial direction via the radial gap Gd. Yes.
Here, as shown in FIG. 3, the radial dimension of the radial gap Gd between the bottom portion 13 and the step portion 52A is L.
As shown in FIG. 2, the bottom portion 13 is provided with three seal fins 17 (17 </ b> A to 17 </ b> C) extending in the radial direction toward the shroud 51. These three seal fins 17 (17A to 17C) will be described later.

As shown in FIG. 2, the outer partition portion 14 has an inner diameter that is smaller than the inner diameter of the bottom portion 13, and is closer to the step portion 52 </ b> A than the bottom portion 13. That is, as shown in FIG. 3, the radial dimension of the radial gap Gd between the outer partition 14 and the step part 52A is H, which is smaller than the radial dimension L.
Further, as shown in FIG. 3, the outer partition portion 14 extends toward the upstream side by an axial dimension B from an end surface 14 a extending in the radial direction between the outer partition portion 14 and the bottom portion 13.

  As shown in FIG. 2, the upstream partition 15 is located on the most upstream side of the groove bottom 11b. The upstream partition portion 15 has an inner diameter smaller than that of the outer partition portion 14. Further, as shown in FIG. 3, the inner radius of the upstream section 15 is larger by ΔH than the radial dimension from the rotation center axis to the step portion 52A. Further, the end surface 15a extending in the radial direction between the outer partition 14 and the upstream end 52a of the step portion 52A are separated from each other by the axial dimension ΔB. This axial dimension ΔB is set larger than the radial dimension ΔH.

As shown in FIG. 2, the seal fins 17 (17 </ b> A to 17 </ b> C) extend from the bottom portion 13 toward the step portions 52 (52 </ b> A to 52 </ b> C), respectively, and extend in the circumferential direction.
These seal fins 17 (17A to 17C) form step portions 52 (52A to 52C) and minute gaps m (mA to mC) in the radial direction.
Further, the seal fin 17A extends in the radial direction along the end surface 14a, and the seal fin 17B extends in the radial direction toward a substantially central position in the axial direction of the step portion 52B.

Each dimension of these minute gaps m (mA to mC) takes into account the thermal elongation amount of the casing 10 and the moving blade 50, the centrifugal elongation amount of the moving blade 50, and the like, and the seal fin 17 (17A to 17C) and the moving blade. It is set to the minimum within a safe range in which 50 does not come into contact.
Similarly, the radial dimension ΔH and the axial dimension ΔB are also set to the minimum within a safe range where the partition plate outer ring 11 and the moving blade 50 do not come into contact with each other.

  With such a configuration, on the upstream side of the radial gap Gd, the step portion 52A that partitions the radially inner side, the outer partition portion 14 that partitions the radially outer side, and the upstream side thereof. An eddy current forming chamber R formed by the upstream partition portion 15 that partitions and the seal fin 17A that partitions the downstream side thereof is configured. In this vortex forming chamber R, the gap O between the step part 52A and the upstream partition part 15 functions as an inlet of the steam S, and the minute gap mA functions as an outlet.

  The bearing portion 60 includes a journal bearing device 61 and a thrust bearing device 62, and supports the shaft body 30 in a freely rotatable manner.

Next, operation | movement of the steam turbine 1 which consists of said structure is demonstrated using figures.
First, when the regulating valve 20 (see FIG. 1) is opened, the steam S flows into the internal space of the casing 10 from a boiler (not shown).

  The steam S flowing into the internal space of the casing 10 sequentially passes through the annular stator blade group and the annular rotor blade group in each stage. At this time, the pressure energy is converted into velocity energy by the stationary blade 40, and the steam S passing through the stationary blade 40 flows between the moving blades 50 constituting the same stage, and imparts rotational force to the moving blade 50. That is, the moving blade 50 converts the velocity energy of the steam S into rotational energy.

  The steam S that has reached the final stage passes through the stationary blade 40 at the final stage and then flows between the downstream moving blades 50 to efficiently apply a rotational force to the moving blades 50.

That is, as shown in FIG. 4, a part of the steam S colliding with the front edge portion of the moving blade 50 flows outward in the radial direction.
As shown in FIG. 4, the steam S that has flowed outward in the radial direction flows into the annular groove 11a and forms a vortex E1. The majority of the vortex E1 flows toward the radially outward side, then flows upstream along the upstream partition 15 and flows out of the annular groove 11a toward the radially inward upstream. Join the mainstream.

On the other hand, a part of the steam S in the vortex flow E1 flows into the vortex forming chamber R from a gap (inlet) O provided on the radially inner side upstream of the vortex forming chamber R.
At this time, the steam S flows into the vortex forming chamber R from a substantially normal direction of the inclination of the gap O (illustrated by a two-dot chain line in FIG. 3). That is, since the axial dimension ΔB> the radial dimension ΔH of the gap O, the steam S has a radial velocity component larger than the axial velocity component, and the vortex flows outward in the radial direction. It flows into the forming chamber R.

  The steam S that has flowed into the vortex forming chamber R forms a vortex E2. The vortex E2 flows radially outward along the end face 15a, then flows downstream along the outer partition 14, and radially inward along the seal fin 17A on the downstream side. And flows toward the upstream side along the step portion 52A on the radially inner side. Thereafter, it flows again radially outward along the end face 15a.

  At this time, since the outer partition portion 14 is closer to the step portion 52A than the bottom portion 13, the end face 15a and the seal fin 17A are compared with the case where the radial dimension H of the vortex forming chamber R is equal to L. The radial dimension becomes shorter, the attenuation of the kinetic energy of the steam S flowing along the end face 15a and the seal fin 17A becomes smaller, and the vortex E2 becomes stronger.

By such vortex E2, the pressure on the upstream side of the minute gap mA is greatly reduced as compared with the case where the vortex forming chamber R does not exist. For this reason, it becomes difficult for the steam S to leak from the minute gap mA to the downstream side.
In addition, the flow of the steam S passing through the minute gap mA is contracted by the vortex E2 flowing radially inward along the seal fin 17A on the downstream side, and the leakage from the minute gap mA to the downstream side. It becomes difficult to do.

  The steam S slightly leaking from the minute gap mA forms a vortex E3 on the upstream side between the seal fin 17A and the seal fin 17B. The vortex E3 flows toward the downstream side along the step portion 52A, and flows radially outward along the end surface 52b extending in the radial direction between the step portion 52A and the step portion 52B. And after flowing toward the upstream side along the bottom portion 13, it flows toward the radially inward side along the seal fin 17 </ b> A.

  The vortex E3 induces the following vortex E4 on the downstream side between the seal fin 17A and the seal fin 17B. That is, when the vortex E3 collides with the bottom portion 13, a part thereof flows downstream along the bottom portion 13. Then, the steam S that has reached the seal fin 17B flows radially inward along the seal fin 17B, and flows upstream along the step portion 52B. And it winds up to the steam S of the eddy current E3 which flows toward radial direction outward from the end surface 52b, and flows toward radial direction outward.

  Due to the vortex E4, a flow inward in the radial direction is generated on the upstream side of the seal fin 17B even on the upstream side of the minute gap mB functioning as the outlet of the steam S. Therefore, the steam S passing through the minute gap mB is generated. The flow of is reduced. This makes it difficult for the steam S to leak downstream from the minute gap mB.

  Thus, it is difficult for the steam S to flow out downstream via the radial gap Gd, and the amount of the steam S flowing through the radial gap Gd and leaking downstream of the rotor blade 50 is extremely small. In other words, the steam S that flows between the rotor blades 50 and flows downstream through the radial gap Gd decreases, and the steam S that flows between the rotor blades 50 increases, so that the velocity energy of the steam S is efficiently increased. 50 will be transmitted.

In this way, the rotational energy is satisfactorily transmitted to the generator or the like through the shaft body 30.
The exhaust steam that has finished work is sent to a condenser (not shown) through the exhaust chamber 19.

As described above, according to the steam turbine 1 according to the present embodiment, the vortex forming chamber R is provided, and the vortex forming chamber R is an inlet through which the mainstream side steam S flows in the radially outward direction. The vortex E2 is formed so that the steam S that has reached the downstream side is directed radially inward along the seal fin 17A. That is, the steam S that has flowed into the vortex forming chamber R flows on the upstream side toward the radially outer side along the end face 15a, and flows on the radially outer side along the outer partitioning portion 14 on the downstream side, After flowing toward the radially inward side along the seal fin 17A on the downstream side, it flows toward the upstream side along the step portion 52A on the radially inward side. As a result, the pressure on the upstream side of the minute gap mA communicating with the downstream side of the vortex forming chamber R is significantly reduced as compared with the case where the vortex forming chamber R is not provided, and the flow of the steam S passing through the minute gap mA. Therefore, it is difficult for the steam S to leak downstream from the minute gap mA.
Therefore, the amount of the steam S leaking from the vortex forming chamber R can be reduced, and the amount of the leaked steam S passing through the radial gap Gd between the shroud 51 and the groove bottom 11b can be reduced.
Therefore, the energy of the steam S can be efficiently converted into rotational energy, and a high-performance steam turbine can be provided.

  Moreover, since the outer partition part 14 which divides the radial direction outer side of the vortex forming chamber R is provided, and the outer partition part 14 is closer to the step part 52A than the bottom part 13, the diameter of the vortex forming chamber R is Since the flow path length in the direction becomes shorter and the kinetic energy attenuation of the steam S flowing in the radial direction becomes smaller, the vortex E2 becomes stronger. As a result, the pressure on the upstream side of the minute gap mA communicating with the vortex forming chamber R further decreases, so that the amount of steam S leaking from the minute gap mA can be further reduced.

  In addition, since the upstream section 15 that partitions the upstream side of the vortex flow forming chamber R is formed on the upstream side of the moving blade 50, the step portion 52A of the moving blade 50 is relatively radial due to centrifugal elongation during operation. Even when displaced outward, the step portion 52A can be prevented from interfering with the upstream partition portion 15. Further, since the gap O between the upstream partition portion 15 and the step portion 52A is used as the inlet of the vortex forming chamber R, the vortex forming chamber R can be realized with a simple configuration.

  Moreover, since the upstream partition part 15 is formed with a part of the partition plate outer ring 11 having a small diameter, the assembling work can be simplified.

  Further, since the relationship 0.5B> ΔB is established, the amount and direction of the steam S flowing into the vortex forming chamber R can be stabilized, and the vortex E2 can be formed more stably.

  Further, since the upstream partition portion 15 is located radially outward from the step portion 52A of the moving blade 50, even if the shroud 51 is displaced relatively upstream due to thermal elongation or pressure difference, the shroud 51 Can be prevented from interfering with the upstream partition section 15.

  Moreover, since it has a relationship of ΔH <ΔB, the velocity component in the radial direction of the steam S flowing into the vortex forming chamber R can be increased, and the direction of the vortex can be stabilized.

In the above-described configuration, the outer partition portion 14 and the upstream partition portion 15 are configured by forming a part of the partition plate outer ring 11 to have a small diameter. However, at least of the outer partition portion 14 and the upstream partition portion 15. One may be configured by providing another member.
Further, the corners of the vortex forming chamber R, more specifically, the corners extending in the circumferential direction between the end surface 15a and the outer partition 14, and the outer partition 14 and the seal fin 17A The corners extending in the circumferential direction between them may be rounded. By doing so, the vortex E2 is easily formed and the vortex E2 becomes stronger.

  Moreover, in the structure mentioned above, although the shroud 51 was formed in step shape, you may form in flat shape.

  FIG. 5 is an enlarged cross-sectional view of a main part showing a steam turbine 2 which is a modification of the steam turbine 1, and corresponds to FIG. The steam turbine 2 is different from the steam turbine 1 described above in the configuration of the upstream partition portion. In FIG. 5, the same components as those in FIGS. 1 to 4 are denoted by the same reference numerals, and description thereof is omitted.

  The steam turbine 2 includes an upstream bottom portion 80 and an upstream partition portion 81 without including the upstream partition portion 15.

  The upstream bottom 80 is adjacent to the outer partition 14 on the downstream side in the groove bottom 11b of the annular groove 11a of the partition plate outer ring 11, and has an inner diameter substantially the same as that of the bottom 13. An end face 14 b extends in the radial direction between the upstream bottom 80 and the outer partition 14.

  The upstream partition 81 is made of a fin member and is fixed to the upstream bottom 80 or the outer partition 14. The upstream partition portion 81 has an L-shaped cross section along the axial direction, and a radially extending portion 81a extending radially inward from the upstream bottom portion 80 along the end surface 14b; An axially extending portion 81b extending from the tip of the radially extending portion 81a toward the upstream side.

  With such a configuration, the vortex forming chamber R partitioned by the step portion 52A, the outer partition portion 14, the upstream partition portion 81, and the seal fin 17A is configured on the upstream side of the radial gap Gd.

  In the configuration of the steam turbine 2 as well, the same effects as the main effects of the steam turbine 1 described above are obtained, and since the upstream partition 81 is a fin member, the shroud 51 is displaced relatively upstream. And when the shroud 51 and the upstream division part 81 contact, the upstream division part 81 which is a fin member is crushed. That is, although the strength and rigidity are inferior to the moving blade 50 including the shroud 51 and the partition plate outer ring 11, the upstream partition 81, which is a fin member that is much cheaper and easy to replace, is crushed. It is possible to suppress damage to the outer ring 11, and it is possible to shorten the time to return to operation.

  In addition, when the shroud 51 is relatively displaced to the upstream side and overlaps in the axial direction in a range where the shroud 51 and the upstream partition portion 81 do not contact with each other, the axis of the upstream partition portion 81 having an L-shaped cross section is obtained. A flow path of the steam S is formed between the direction extending part 81b and the step part 52A, and this becomes an inlet to the radial gap Gd. Since the radial dimension of this flow path is only a slight ΔH as shown in FIG. 3, the pressure loss when the steam S passes increases, and the leaked steam S flowing into the downstream radial gap Gd of the steam S increases. The amount can be reduced.

(First reference example)
FIG. 6 is an enlarged cross-sectional view of a main part showing a steam turbine 3 which is a first reference example of the present invention.
In FIG. 6, the same components as those in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.

As shown in FIG. 6, the steam turbine 3 is a shroud 100 in which the tip of a moving blade 50 is formed flat.
The shroud 100 has tip end surfaces 100a and 100b extending flat in the radial direction on the upstream and downstream sides in the axial direction.

An axial seal fin 101a extending toward the upstream side in the axial direction is fixed to the end face 100a of the distal end portion.
An axial seal fin 101b extending toward the downstream side in the axial direction is fixed to the end face 100b of the distal end.
These axial seal fins 101a and 101b each extend in the circumferential direction.

The partition plate outer ring 110 has an annular groove 110a in which a groove bottom 110b is formed in a flat shape, and the shroud 100 is accommodated in the annular groove 110a. The upstream end portion and the downstream end portion of the groove bottom 110a have opposing surfaces 111a and 111b extending flatly inward in the radial direction, respectively.
These facing surfaces 111a and 111b are opposed to the end surface 100a and 100b, respectively, via an axial gap Gp.

The facing surface 111a is formed with a circumferential groove 112a that is recessed in the axially upstream side and extends in the circumferential direction.
The opposing surface 111b is formed with a circumferential groove 112b that is recessed in the axially downstream side and extends in the circumferential direction.

The circumferential groove 112a is close to the tip of the axial seal fin 101a. The groove wall surfaces 113a and 114a that define the circumferential groove 112a form a minute gap m with the tip of the axial seal fin 101a.
The circumferential groove 112b is close to the tip of the axial seal fin 101b. The groove wall surfaces 113b and 114b that define the circumferential groove 112b form a minute gap m with the tip of the axial seal fin 101b.

  These circumferential grooves 112a and 112b are formed such that the groove width (diameter dimension) is larger than the thickness (diameter direction) of the axial seal fins 101a and 101b. The axial dimension is set to allow the thermal expansion and axial displacement of the axial seal fins 101a and 101b.

With such a configuration, the circumferential groove 112a and the axial seal fin 101a constitute a seal unit U1.
Similarly, the circumferential groove 112b and the axial seal fin 101b constitute a seal unit U2.

According to this steam turbine 3, since it has the seal unit U1 and the steam S is difficult to pass through the minute gap m, it is possible to prevent the steam S from the mainstream side from flowing into the radial gap Gd. it can. Thereby, the amount of the leaked steam S passing through the radial gap Gd can be reduced.
Moreover, since the seal unit U2 is provided and the steam S is difficult to pass through the minute gap m, the leaked steam S flowing out from the radial gap Gd is prevented from joining the main stream. Thereby, the steam S flowing between the moving blades 50 increases.
Therefore, the energy of the steam S can be efficiently converted into rotational energy, resulting in a high-performance turbine.

  Further, even if the shroud 100 is relatively displaced in the axial direction due to thermal expansion or pressure difference, the axial seal fins 101a and 101b are displaced so as to be accommodated in the circumferential grooves 112a and 112b, respectively. Contact between the fins 101a and 101b and the partition plate outer ring 110 can be prevented.

(Second reference example)
FIG. 7 is an enlarged cross-sectional view of a main part showing a steam turbine 4 which is a second reference example of the present invention.
In FIG. 7, the same components as those in FIGS. 1 to 6 are denoted by the same reference numerals, and the description thereof is omitted.
In the steam turbine 4, a seal unit U <b> 1 is provided on the upstream side, and a seal unit U <b> 2 is provided on the downstream side at intervals of four in the radial direction.

According to the steam turbine 4, since the four seal units U1 are provided, the amount of the steam S reaching the radial gap Gd can be further reduced.
Further, since the four seal units U2 are provided, the amount of the steam S that passes through the radial gap Gd and joins the main stream can be further reduced.
Therefore, the amount of the steam S flowing between the rotor blades 50 is further increased, and the energy of the steam S can be more efficiently converted into rotational energy, resulting in a higher performance turbine.

(Third reference example)
FIG. 8 is an enlarged cross-sectional view of a main part showing a steam turbine 5 which is a third reference example of the present invention.
In FIG. 8, the same components as those in FIGS. 1 to 7 are denoted by the same reference numerals, and description thereof is omitted.

  As with the steam turbine 4, the steam turbine 5 includes four seal units in the upstream and downstream axial gaps Gp. However, compared to the configuration of the steam turbine 4, the configuration of the facing surface, the axial seal fin, and the circumferential groove is different.

  The facing surfaces 111c and 111d are formed so as to be gradually separated from the end surface 100a and 100b, respectively, from the radially outer side toward the inner side. In other words, these facing surfaces 111c and 111d extend so as to go to the recess direction side of the circumferential grooves 121a to 124a and 121b to 124b, respectively, from the radially outer side toward the inner side. That is, the facing surfaces 111c and 111d are inwardly tapered with the normal direction directed radially inward.

  Four axial seal fins 102a to 105a and 102b to 105b are provided on the tip end faces 100a and 100b, respectively, with the axial dimension increasing from the radially outer side to the inner side.

On the facing surface 111c, circumferential grooves 121a to 124a are formed at the same positions as the axial seal fins 102a to 105a in the radial direction.
On the facing surface 111d, circumferential grooves 121b to 124b are formed at the same positions as the axial seal fins 102b to 105b in the radial direction.

The tips of the axial seal fins 102a to 105a form minute gaps m with the groove wall surfaces 131a to 134a on the radially outer side of the circumferential grooves 121a to 124a, respectively.
With such a configuration, the axial seal fins 102a to 105a and the circumferential grooves 121a to 124a constitute seal units U3 to U6, respectively.

The tips of the axial seal fins 102b to 105b form minute gaps m with the groove wall surfaces 131b to 134b on the radially outer side of the circumferential grooves 121b to 124b, respectively.
With such a configuration, the axial seal fins 102b to 105b and the circumferential grooves 121b to 124b constitute seal units U7 to U10, respectively.

  According to the steam turbine 5, the opposing surfaces 111 c and 111 d of the partition plate outer ring 110 are formed so as to be gradually separated from the tip end surfaces 100 a and 100 b of the shroud 100 as they go from the radially outer side to the inner side. Therefore, for example, by making the outer ring 11 of the partition plate half cracked, it becomes possible to facilitate assembly and disassembly.

  In the above-described configuration, the tip end surface 100a, 100b is configured to extend in a flat shape from radially outward to inward. However, the tip end surface 100a, 100b extends from the radially outer side. You may extend so that it may go to the hollow direction side of the circumferential grooves 121a-124a and 121b-124b, respectively, as it goes inward. That is, the tip end surface 100a, 100b may be formed in a tapered shape whose normal direction is outward, and may be opposed to the opposing surfaces 111c, 111d that are inwardly tapered. At this time, the inclinations of the end surface 100a, 100b and the facing surfaces 111c, 111d may be formed with the same inclination, or may be formed with different inclinations as long as they do not contact each other.

(Second embodiment)
FIG. 9 is a schematic cross-sectional view showing a steam turbine 6 according to the second embodiment of the present invention.
In FIG. 9, the same components as those in FIGS. 1 to 8 are denoted by the same reference numerals, and the description thereof is omitted.

The steam turbine 6 employs the configuration of the seal units U <b> 3 to U <b> 10 of the third reference example in the configuration of the steam turbine 2.
According to this configuration, the seal units U3 to U6 are provided, and the steam S is difficult to pass through the minute gap m, so that the steam S from the mainstream side can be prevented from flowing into the vortex forming chamber R. it can. Further, even if the steam S flows into the vortex forming chamber R, the pressure on the upstream side of the minute gap mA communicating with the vortex forming chamber R is reduced because the vortex E2 is formed. S becomes difficult to leak. And since it has the seal units U7-U10 and the steam S is difficult to pass through the minute gap m, the leaked steam S flowing out from the radial gap Gd is prevented from joining the main stream. Thereby, the steam S flowing between the moving blades 50 increases.
Therefore, the energy of the steam S can be efficiently converted into rotational energy, resulting in a high-performance turbine.

Furthermore, since the upstream partition 81 is a fin member, even if the shroud 51 and the upstream partition 81 contact each other, the upstream partition 81 is crushed. Thereby, it becomes possible to suppress damage to the moving blade 50 and the partition plate outer ring 11.
Even if the shroud 100 is relatively displaced in the axial direction, the axial seal fins 102a to 105a are displaced in the circumferential grooves 121a to 124a, and the axial seal fins 102b to 105b are displaced in the circumferential grooves 121b to 124b. Thus, contact between the axial seal fins 102a to 105a and the partition plate outer ring 11 (110) can be prevented.
Accordingly, it is possible to greatly reduce the adverse effects caused by the relative axial displacement of the shroud 51 (100), and to cope with a wide range of usage conditions.

In the configuration described above, the seal units U3 to U6 are applied to the upstream axial gap Gp, and the seal units U7 to U10 are applied to the downstream axial gap Gp. Also good. Further, the number of seal units to be applied can be increased or decreased as appropriate.
In the configuration described above, the upstream bottom portion 80 has an inner diameter substantially the same as that of the bottom portion 13, but may have a different inner diameter. Alternatively, as shown in FIG. The bottom 82 may be used.

Note that the operation procedure shown in the above-described embodiment, various shapes and combinations of the constituent members, and the like are examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.
For example, in the embodiment described above, the partition plate outer rings 11 and 110 are stationary annular bodies, but a configuration in which the casing 10 is a stationary annular body without providing such partition plate outer rings 11 and 110 is also conceivable. In other words, the stationary annular body may be any member as long as it surrounds the moving blade and defines the flow path so that the fluid passes between the moving blades.

  In the above-described embodiment, the present invention is applied to the final stage moving blade 50, but the present invention may be applied to the other stage moving blade 50.

  In the above-described embodiment, the case where the present invention is applied to an impact turbine has been described. However, the present invention may be applied to a reaction turbine.

  In the above-described embodiment, the present invention is applied to a condensing steam turbine. However, the present invention is applied to other types of steam turbines, for example, turbine types such as a two-stage extraction turbine, an extraction turbine, and an air-mixing turbine. Can be applied.

  In the above-described embodiment, the present invention is applied to the steam turbine. However, the present invention may be applied to a gas turbine.

1-6 ... Steam turbine (turbine)
11, 110 ... partition plate outer ring (stationary annular body)
11a, 110a ... annular grooves 11b, 110b ... groove bottom (inner circumference)
14 ... Outer partition parts 15, 81 ... Upstream partition part 17 (17A-17C) ... Seal fin 30 ... Shaft body 50 ... Rotor blade 51, 100 ... Shroud 81a ... Radial extension part 81b ... Axial extension part 100a , 100b ... end faces 101a, 101b, 102a to 105a, 102b to 105b ... axial seal fins 111a to 111d ... opposing faces 112a, 112b, 121a to 124a, 121b to 124b ... circumferential grooves 113a, 113b, 114a, 114b, 131a ... 134a, 131b to 134b ... groove wall surface B ... axial dimension E2 ... vortex Gd ... radial gap Gp ... axial gap L ... radial dimension m (mA to mC) ... minute gap O ... gap (inlet)
R ... Eddy current forming chamber S ... Steam U1-U10 ... Seal unit

Claims (13)

A stationary annulus,
A shaft provided rotatably inside the stationary annular body;
A plurality of radial blades are provided on the shaft body, and the tip of each tip is opposed to the inner peripheral portion of the stationary annular body via a radial gap;
A turbine comprising seal fins extending from the inner periphery of the stationary annular body toward the radially inward side to form a minute gap with the tip of the moving blade,
An upstream side of the radial clearance is provided with a vortex forming chamber whose downstream side is partitioned by the seal fin,
The vortex forming chamber has an inflow port through which the fluid on the main flow side flows toward the radially outward side, and the fluid that has reached the downstream side is directed toward the radially inward side along the seal fin. A turbine characterized in that a vortex is formed in the turbine. The stationary annular body includes an outer partition section that partitions the radially outer side of the vortex forming chamber on the inner peripheral section,
2. The turbine according to claim 1, wherein the outer partition portion is close to a tip end portion of the moving blade to reduce the radial clearance. The stationary annular body includes an upstream section that is formed on the upstream side of the rotor blade and partitions the upstream side of the vortex forming chamber,
The turbine according to claim 1 or 2, wherein a gap between the upstream section and the upstream side of the tip of the rotor blade is the inflow port.   The turbine according to claim 3, wherein the upstream partition portion is formed such that a part of the stationary annular body has a small diameter.   The turbine according to claim 3, wherein the upstream section is a fin member provided on the stationary annular body. The upstream partition portion includes an extending portion extending radially inward from the stationary annular body, and an axial extending portion extending in the axial direction from the tip of the extending portion,
The turbine according to claim 5, wherein a cross-sectional shape along the axial direction is L-shaped.   When the axial dimension of the vortex forming chamber is B and the axial dimension of the gap between the upstream section and the upstream side of the tip of the rotor blade is ΔB, there is a relationship of 0.5B> ΔB. The turbine according to any one of claims 3 to 6.   The turbine according to any one of claims 3 to 7, wherein the upstream partition portion is located radially outward from the upstream side of the tip end portion of the moving blade.   When the radial dimension of the gap between the upstream section and the tip upstream side of the rotor blade is ΔH, and the axial dimension of the gap between the upstream partition and the tip upstream of the rotor blade is ΔB, The turbine according to claim 8, wherein a relationship of ΔH <ΔB is satisfied. The stationary annular body has a facing surface that extends radially inward from the inner peripheral portion and faces the end surface of the tip of the moving blade via an axial gap,
The opposing surface is formed with a circumferential groove that is recessed in the axial direction and extends in the circumferential direction.
The tip of the rotor blade includes an axial seal fin that extends from the end face of the tip toward the circumferential groove in the axial direction and forms a minute gap with a groove wall surface in the radial direction of the circumferential groove,
The turbine according to claim 1, wherein the circumferential groove and the axial seal fin constitute a seal unit.   The turbine according to claim 10, wherein a plurality of the seal units are provided at intervals in the radial direction. The facing surface of the stationary annular body extends from the radially outer side toward the inner side so as to go toward the hollow direction side of the circumferential groove in the axial direction.
The end surface of the distal end extends in a flat shape from the radially outer side to the inner side,
12. The axial seal fin on the radially inner side of the plurality of axial seal fins has an axial dimension larger than that of the axial seal fin on the radially outer side. Turbine. The facing surface of the stationary annular body extends from the radially outer side toward the inner side so as to go toward the hollow direction side of the circumferential groove in the axial direction.
The end surface of the tip end portion extends toward the indentation side of the circumferential groove of the opposing surface in the axial direction as it goes from the radially outer side to the inner side. The turbine described in 1.

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