JPH0739805B2 - Turbine seal clearance adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Industrial field of use) The present invention relates to a seal clearance adjusting device for a turbine, and more particularly to an inner side and an outer side of a closed chamber connecting a stationary part of the turbine and a fin segment. The invention relates to a turbine seal portion clearance adjusting device for supplying a working fluid of a turbine to any of the above and expanding and contracting a sealed chamber by a pressure difference between the two working fluids.

(Prior Art) In recent years, it has become increasingly important to improve turbine performance in response to soaring fuel prices, and various performance improvement measures have been proposed. The most effective performance improvement measures are The purpose is to reduce the amount of steam leaking from the gap between the stationary part and the rotating part, which inevitably exists in each part of the turbine.

FIG. 19 is a view showing an upper half of an assembled cross section of a conventional steam turbine of this type, which shows a rotor blade fixed to a turbine axle 51.
52 between the nozzle outer ring 53, the turbine axle 51 and the nozzle inner ring
54, and between the turbine axle 51 and the nozzle inner ring 54, and between the turbine wheel 51 and the casing 55,
Each of them is provided with a tip fin, a nozzle packing, and a seal device for preventing vapor leakage called a gland packing.

FIG. 20 is a cross-sectional view showing an example of these sealing devices and showing a tip fin between the moving blade 52 and the nozzle outer ring 53. The nozzle outer ring 53, which is a stationary portion, is formed with a dovetail-shaped mounting groove 56 extending in the circumferential direction in a portion facing the outer peripheral end of the moving blade 52.
A segment 58 provided with a plurality of circumferentially extending seal fins 57 projecting toward the outer peripheral surface of 52 is mounted.
A predetermined minute gap is formed between the seal fin 57 and the tip of the rotor blade 52 that is a rotating body, and vapor leakage is kept to a minimum through this gap.

By the way, in this type of non-contact type seal device, the largest factor that determines the steam leakage prevention effect is the size of the gap between the tip of the seal fin 57 and the rotating body. However, if this gap is made too small, the seal fin and the rotating part will come into contact during operation, the rotating part and the seal fin will be damaged, and shaft vibration will increase due to the contact, making it impossible to continue operation. However, there is a problem that the rotating part is bent due to heat generated by contact.

Such contact is because the gap value changes depending on the operating state of the turbine, and such a change may be caused by uneven thermal deformation of the casing, deformation due to pressure, or various supporting characteristics of the bearing supporting the turbine axle. It is caused by a factor, and particularly occurs when the turbine is started or stopped, or when the load changes. During steady operation, the amount of deformation and change settles down to a certain value over time, so the amount of change in the gap is extremely small.If the gap is set in consideration of the gap conditions when starting and stopping or when the load changes, steady operation for a long time Sometimes the gap becomes unnecessarily large and the amount of steam leakage increases.

In order to eliminate such inconvenience, conventionally, a drive mechanism is provided between the fin segment and the stationary portion to change the gap according to the operating state or the measured value of the gap of the seal portion. A device provided with a sealing mechanism has been proposed.

FIG. 21 shows an example of a conventional movable seal gap adjusting device of this type, in which the segment mounted in the mounting groove 56 is
58 is a flange body 61 via a bellows 60 of expandable pressure
The flange body 61 is screwed to the nozzle outer ring 53 via a mounting bolt 63. A working fluid introduction hole 64 is formed in the nozzle outer ring 53, and one end of the introduction hole 64 communicates with an internal chamber 67 of the bellows 60 through a communication hole 65 formed in the mounting bolt 63. The other end of is connected to a steam introducing pipe (not shown) in which a solenoid valve is incorporated. Bellows
The outer chamber 68 located outside the 60 is filled with the working fluid of the turbine flowing in from the gap between the segment 58 and the nozzle outer ring 53, and the pressure of the working fluid in the outer chamber 68 and the introduction of steam into the inner chamber 67. The bellows 60 is expanded and contracted in the radial direction by the pressure difference from the pressure of the working fluid supplied from the pipe. When the pressure P ₁ in the inner chamber 67 is higher than the pressure P ₂ due to the working fluid of the turbine in the outer chamber 68, the bellows 60 expands due to the pressure difference, and the tips of the seal fins 57 and the blades provided in the segment 58. The gap with 52 is narrowed and steam leakage is prevented.

(Problems to be Solved by the Invention) However, in order to obtain the driving force of the bellows 60, the conventional movable seal gap adjusting device of this type requires a steam source outside and the inside of the bellows 60 through a pipe or the like. It was a method to lead. This method has a drawback in that it has a large number of external pipes and is complicated in structure and reliability is lowered. In addition, it is difficult to set the steam conditions to be introduced from the outside, and an electric valve or the like is required in the middle of the piping to control the amount of steam to be introduced. Bellows
There was a problem that the driving force of 60 could not be obtained sufficiently.

Therefore, an object of the present invention is to provide a seal part clearance adjusting device for a turbine, which has a simple structure and is capable of sufficiently adjusting the clearance of the seal part according to the turbine load.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention has a plurality of sealing fin segments arranged in the circumferential direction facing a rotating portion of a turbine and having elastic expansion and contraction forces. In a turbine seal part clearance adjusting device, which is mounted on a stationary part of a turbine via a free bellows and in which the fin segments can be moved in the radial direction of the turbine by a pressure difference of working fluid supplied to the inside and outside of the bellows. , Each of the mounting bolts for mounting the bellows to the stationary portion is provided with a communication hole that opens in the bellows through an annular hole provided in the stationary portion and an annular chamber formed on the outer periphery of the mounting bolt. And one of the annular chambers is communicated with an introduction hole communicating with the upstream side of the stationary portion, and extends in the circumferential direction on the side wall portion of the fin segment mounting groove provided in the stationary portion. Forming a groove,
It is characterized in that both end edges of the fin segment are engaged with the groove so that the fin segment can move in a radial direction within a predetermined range.

(Operation) The operation of the present invention will be described based on the above configuration. High-pressure steam upstream of the stationary portion flows into the inside of the bellows, and inside the bellows inside the bellows near the mounting portion of the fin segment. Steam with a pressure lower than the incoming steam pressure flows in,
The pressure difference between the two causes the bellows to expand and the fin segments to be pushed out in the radial direction of the turbine, narrowing the gap between the rotating part and the stationary part.

Since the spring force that constantly contracts to the initially set dimension acts on this bellows, the differential pressure between the pressure on the upstream side of the stationary portion and the pressure near the mounting portion of the fin segment is the spring force. When the ball is defeated, the bellows contract and the fin segment is drawn in the radial direction of the turbine to widen the gap.

The expansion and contraction of the bellows is determined by the pressure difference of the working fluid of the turbine supplied to the inside and outside of the bellows and the balance of the spring force of the bellows. It is possible to maintain an appropriate gap according to the above.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 is a moving blade provided on a turbine axle 2 via a wheel 3, and the tip of this moving blade 1 is connected to a plurality of groups by a shroud 4. A nozzle blade 9 fixed between the nozzle outer ring 5 and the nozzle inner ring 6 is arranged on the upstream side of the moving blade 1, and the nozzle outer ring 5 is fixed to a stationary portion 10 of the turbine.

The nozzle outer ring 5 is provided with a dovetail-shaped mounting groove 11 extending in the circumferential direction at a position facing the outer peripheral portion of the tip of the moving blade 1. Inside the mounting groove 11, a plurality of sealing fins extending in the circumferential direction are formed.
Fin segments 13 having holes 12 are arranged in the circumferential direction as shown in FIG. Each of the fin segments 13 is mounted in the mounting groove 11 so as to be movable in the radial direction, and a plurality of bellows 15 are interposed between the inner surface of the mounting groove 11 and each of the fin segments 13.

As shown in FIG. 3, this bellows 15 has one end surface fixed to the fin segment 13 and the other end surface fixed to the flange body 16 to form a closed chamber structure. The flange body 16 has a boss 17 in the center, and a female screw hole 17a is formed in the boss 17, and the flange body 16 is screwed to the nozzle outer ring 5 by a mounting bolt 18. A communication hole 19 is formed in the mounting bolt 18, one end of the communication hole 19 opens into the inner chamber 20 of the bellows 15, and the other end communicates with an annular chamber 21 formed around the mounting bolt 18. is doing.

Thus, according to the present invention, as shown in FIG.
An introduction hole 23 having one end communicating with the annular chamber 21 is bored through the nozzle outer ring 5, and the other end of the introduction hole 23 is opened on the upstream side of the nozzle blade 9. The high-pressure steam on the upstream side of the nozzle blade 9 sequentially flows through the introduction hole 23, the annular chamber 21, and the communication hole 19 into the inner chamber 20 of the bellows 15 and into the outer chamber 25 located outside the bellows 15. The working fluid of the turbine that has passed through the nozzle blade 9 flows in through the gap between the fin segment 13 and the nozzle outer ring 5. As a result, the pressure in the inner chamber 20
The bellows 15 expands and contracts due to the pressure difference between P ₁ and the pressure P ₄ in the outer chamber 25, and the fin segment 13 moves in the radial direction of the turbine.

The operating principle of the fin segment 13 at this time will be described with reference to FIG. When the driving force required to push the fin segments 13 and _{F S, F S = P 4} (A 0 -A B) + P 1 · A B -P I · A 0 -δ · K B + W ...... (1) The relational expression of is established.

Where P ₁ is the pressure in the inner chamber 20, P ₄ is the pressure in the outer chamber 25, P _{I is} the average pressure between the tips of the seal fins 12 and the shroud 4, K _{B is} the spring constant of the bellows 15, δ ... The amount of movement of the fin segment 13, W ... Weight per fin segment 13, A ₀ ... Total area of the outer circumference of the fin segment 13, A _B ... Attachment area of the bellows 15.

Note that A ₀ = b × l (2) Here, b ... Width of fin segment 13, l ... Perimeter of fin segment 13, de ... Effective diameter of bellows 15, n ... Number of bellows 15 attached to fin segment 13, (Fig. 4 (a (See (b)) On the other hand, the pressures P _I and P ₄ are obtained by the following relational expressions.

_{P I = f (P 2,} P 3, k 1) ...... (4) P 4 = f (P 2, P 3, k 2) ...... (5) , where the quantity of k ₁ ... seal fins 12 and The shape, the clearance between the tip of the seal fin 12 and the shroud 4, the shape factor comprehensively determined by the outer peripheral surface shape of the shroud 4, k ₂ = the shape of the mounting groove 11, the shape of the fin segment 13, etc. Shape factor, P ₂ ... pressure on inlet side to moving blade 1, P ₃ ... pressure on outlet side from moving blade 1, and description will be given based on the relational expression (1) above. Since the urging force of the spring force of 15 toward the outer side of the turbine in the radial direction acts, in order to push the fin segment 13 by the movement amount δ ₀ , δ =
When substituting for δ ₀ , a condition that satisfies F _S > 0 is required.

On the contrary, from the relationship between the pressures P _{1 to} P ₄ and P _I , when the condition of F _S <0 is satisfied, the fin segment 13 returns to the original state by the spring force.

FIG. 5 is a diagram showing the relationship between the above pressures P _{1 to} P ₄ and P _I and the turbine load. P _{1 to} P ₄ are zero when the turbine load is about 10% (however, P _I = 0) and then the pressures P _{1 to} P ₄ increase in proportion to the increase in turbine load.

FIG. 6 shows the state of the fin segment 13 at a turbine load of about 10%, and the pressure at that load is indicated by P ₁ ^{(10) to} P ₄ ⁽¹⁰⁾ and P _I ⁽¹⁰⁾ .

In this case, P ₁ ⁽¹⁰⁾ , P ₂ ⁽¹⁰⁾ , P ₃ ⁽¹⁰⁾ , P ₄ ⁽¹⁰⁾ , P _I ⁽¹⁰⁾ = 0
When is substituted into the relational expression of (1) above, the driving force F _S ⁽¹⁰⁾ is as follows.

^{_{F S (10) = -δ ·}} K B + W ...... (6) from 1 per weight W of the fin segments 13 is small (6) is F _S ⁽¹⁰⁾ <0, and the push driving force fin segments Does not work on 13. Therefore, the bellows 15 maintains the original length L, and the fin segment 13 is lifted from the inner peripheral wall of the mounting groove 11 by the distance δ ₁ .

On the other hand, when the turbine load is 50%, as shown in FIG. 5, pressures P ₁ ^{(50) to} P ₄ ⁽⁵⁰⁾ are generated and become P _I ⁽⁵⁰⁾ , and a pressure difference is generated between them. P _{1 in} the relational expression of (1)
⁽⁵⁰⁾ to P ₄ ^(50), the driving force F _S ⁽⁵⁰⁾ and substituting P _I ⁽⁵⁰⁾ is as follows.

F _S ⁽⁵⁰⁾ = P ₄ ⁽⁵⁰⁾ (A ₀ −A _B ) + P ₁ ⁽⁵⁰⁾ A _B −P _I ⁽⁵⁰⁾ A ₀ −δ · K _B + W …… (7) where the turbine load is Pressure at 25% P ₁ ^{(25) to} P ₄
Bellow 15 so that F _S ⁽²⁵⁾ > 0 at ⁽²⁵⁾ and P _I ⁽²⁵⁾
If the spring constant K _{B of} is set, the above equation (7) becomes F _S ⁽⁵⁰⁾
> 0. That is, in this case the turbine load is 25
%, The relationship of F _S > 0 is always established, as shown in FIG. 7, the bellows 15 extends to the entire length l, the fin segment 13 is pushed out, and the gap between the tip of the seal fin 12 and the shroud 4 is increased. S becomes narrower.

Therefore, by appropriately selecting the spring constant K _B of the bellows 15, the turbine load at which the bellows 15 begins to expand can be arbitrarily set, and the bellows 15 can be expanded and contracted according to the operating state of the turbine.

FIG. 8 is a diagram showing the relationship between the turbine load and the movement amount of the fin segment 13, and the spring constant K _B of the bellows 15 is taken as a parameter.

In the figure, the parameters have a relationship of K _B ⁽³⁾ ＞ K _B ⁽²⁾ ＞ K _B ^(1). It is shown that increasing the spring constant K _B also increases the turbine load at which the bellows 15 begins to expand. There is.

Next, the effect of the seal portion gap adjusting device according to the present invention as compared with the conventional fixed type sealing device shown in FIG. 20 will be described.

The gap between the tip of the seal fin 12 and the shroud 4 changes during turbine operation, and the steady displacement difference (hereinafter, the displacement difference means the difference in radial displacement from the stationary portion) is as follows (a) to (e). It is determined by the factors of.

(A) ... Expansion of the wheel 3 and the rotor blade 1 due to centrifugal force, (b) ... Deformation due to clearance and centrifugal force at the time of assembling the blade implant portion, (c) ... Deformation of the shroud 4 due to centrifugal force, (d). … The difference in thermal expansion between the stationary part and the rotating part based on the temperature in the steady state, (e)… The moving amount of the turbine axle, when the turbine is operating at the rated load of 100% load,
The gap value between the tip of the seal fin 12 and the shroud 4 is determined by the following relational expressions.

In the conventional example, assuming that the gap value is S ₁ , S ₁ = S ₀ − (a) − (b) − (c) − (d) − (e) (7) In the present invention, the gap value S ₁ ^(A) Then, S ₁ ^(A) = S ₀ ^(A) -(a)-(b)-(c)-(d)-(e) -δ ₂ (8) where S ₀ , S ₀ ^(A) … Seal fin 12 when assembling each
Is the gap between the tip of the shroud 4 and S ₀ ^(A) > S ₀ , δ ₂ ... the moving amount of the fin segment 13, (a) to (e)
... The displacement amount due to the above-mentioned factors, and if it is set so that the relation of δ ₂ > (S ₀ ^(A) −S ₀ ) is established, as is clear from the equations (7) and (8), the turbine The relationship of S ₁ ^(A) <S ₁ can always be maintained during operation. Therefore, according to the present invention, it is possible to reduce the amount of steam leaked from the gap during turbine operation and to improve turbine performance, as compared to the conventional example.

On the other hand, the unsteady displacement difference at the time of starting and stopping the turbine is determined by considering the following two factors in addition to the above factors (a) to (e).

(F) ... Thermal deformation due to unsteady circumferential temperature distribution in stationary part, (g) ... Thermal expansion difference due to unsteady temperature distribution in rotating part and stationary part, that is, when the turbine is operated under low load The gap value between the tip of the fin 12 and the shroud 4 is determined by the following relational expressions.

In the conventional example, assuming that the gap value is S ₂ , S ₂ = S ₀ − (a) − (b) − (c) − (d) − (e) − (f) − (g) (9) The present invention If the gap value is S ₂ ^(A) , then S ₂ ^(A) = S ₀ ^(A) -(a)-(b)-(c)-(d)-(e)-(f)-(g) …… (10) By the way, since the relation of S ₀ ^(A) ＞ S ₀ holds, (9) (1
As is clear from the equation ⁽ 0), S ₂ ^(A) > S ₂ . Therefore, according to the present invention, the gap becomes large during low load operation as compared with the conventional example, and it is possible to avoid contact between the tips of the seal fins 12 and the shroud 4.

FIG. 9 is a diagram showing a comparison with the above-described conventional example. The gap S ₀ between the tip of the seal fin 12 and the shroud 4 in assembling the fin segment in the conventional example changes according to the turbine load. It is always kept constant (x-ray in the figure). According to the present invention, the gap S ₀ ^(A) between the tips of the seal fins 12 and the shroud 4 set at the time of assembly gradually narrows according to the turbine load, and then is kept constant (y in the same figure). line). The displacement difference increases in the low turbine load region (z line in the figure).

Therefore, according to the present invention, the gap between the tip of the seal fin 12 and the shroud 4 is large in the region I where the turbine load is small, and conversely, the gap is small in the region II where the turbine load is large as compared with the conventional example. Become.

Therefore, the region I is a region for improving reliability for surely preventing the contact between the tip of the seal fin 12 and the shroud 4, and the region II is a region where performance improvement can be achieved, and excellent effects can be obtained.

Further, the turbine load corresponding to the intersection of the x-ray and the y-ray can be easily adjusted by appropriately changing the spring constant K _B of the bellows 15 as shown in FIG.

Next, a modified example when the seal gap adjusting device according to the present invention is applied will be described.

FIG. 10 shows a modified example thereof, in which a recessed groove 30 extending in the circumferential direction for controlling the movement amount of the fin segment 13 is formed in the side wall portion of the mounting groove 11 formed in the nozzle outer ring 5.
The fin segment 13 is mounted so that both ends thereof are sandwiched by the recessed groove 30, and is fixed to the nozzle outer ring 5 via the expandable bellows 15 similar to the above. When the turbine is operated under high load, the bellows 15 expands and the fin segment 13 is pushed out, as shown in FIG. 11,
During low load operation, the bellows 15 contracts to its original state as shown in FIG.

With this configuration, bellows generated during low load operation
The vibration of the vibration system consisting of 15 and fin segment 13
It can be pressed within the range of the gaps δ ₄ and δ ₅ shown in FIG.

On the other hand, the fin segment movement amount δ ₁ (Fig. 6) set when the fin segment 13 is attached is largely influenced by the accuracy of the length L when the bellows 15 is manufactured.
₁ is small, and if it is short, the movement amount δ ₁ becomes large.

12 and 13 show a modification for absorbing the error of the length L when manufacturing the bellows 15. The nozzle outer ring 5 to which this modification is applied is the same as that shown in FIG. In groove
30 are formed. At the time of manufacture, the length L ₁ of the bellows 15 is made slightly shorter than the design length L, and the depth of the mounting groove 11 is formed to be the same as the design length L of the bellows 15.

In the state before assembly, the following relationships are established among the gaps shown in FIG.

α = δ ₆ −δ ₇ (11) where α = L−L ₁ (12) Next, the flange body 16 is screwed onto the nozzle outer ring 5 by the mounting bolt 18 as shown in FIG. Be worn. At this time, if the relation of δ ₆ > δ ₇ is set, the initial tensile force equivalent to α acts on the bellows 15 as is clear from the equation (11). The movement amount δ ₉ of the fin segment 13 shown in FIG. 13 at this time is as follows.

δ ₉ = δ ₈ + δ ₇ (13) Since the bellows 15 is forcibly stretched and mounted in the mounting groove 11, the driving force P _S shown in the above equation (1) is
Is as follows.

_{F S = P 4 (A 0} -A B) + P 1 · A B + α · K B -P I · A 0 -δ · K B + W ...... (14) According to this modification, the alpha · K _B It becomes necessary to consider the force, and in order to move the fin segment 13, not only the equilibrium between the pressure and the spring constant such that F _S > 0 as shown in the above formula (1), but also the α · K _{B component} . The power to cancel the power of is needed.

Therefore, when the turbine load is higher than in the case of the formula (1), the bellows 15 begins to expand, and the turbine load at which the bellows 15 begins to expand can be set by changing only the dimensional difference α without changing the spring constant K _B. .

Fig. 14 is a diagram showing the turbine load at which the bellows 15 begins to expand by changing the dimensional difference α, and the dimensional differences α ⁽ a ⁾ , α ⁽ b ⁾ , and α ⁽ c ⁾ are set. Then, in the figure a,
It is shown that the bellows 15 start to extend and the fin segment 13 starts to move from the turbine load corresponding to the positions indicated by b and c, respectively. In this case, the dimensional difference α is α ⁽ a ⁾ <
There is a relationship of α ⁽ b ⁾ <α ⁽ c ⁾ , and if the dimensional difference α is set small, it is possible to move the fin segment 13 even when the turbine load is low without changing the spring constant K _B.

As described above, according to this modification, the turbine load at which the bellows 15 begins to expand can be easily set by changing the dimensional difference α, and at the time of assembly, the bellows 15 already have a tensile force applied thereto, so that a low load operation is possible. It is possible to reduce the vibration of the vibration system including the bellows 15 and the fin segments 13 at the time.

Although FIG. 15 shows the bellows 15 in an extended state,
The total length L _{2 of the} bellows 15 is L ₂ = L ₁ + α + δ ₇
15 is longer than it was manufactured by α + δ ₇ .

By the way, since the stress due to the elongation of the bellows 15 is proportional to the amount of elongation of the bellows 15, it is disadvantageous in terms of stress to increase the value of α too much. Therefore, it is desirable to appropriately set α and δ ₇ so as to suppress the total elongation amount of α + δ ₇ .

16 and 17 show an embodiment of the seal gap adjusting device according to the present invention. As shown in FIG. 17, two bellows are provided between the fin segment 13 and the nozzle outer ring 5.
15,15 are installed. Then, as shown in FIG. 16, the two bellows 15 and 15 are fixed to the flange bodies 16 and 16, respectively, and these flange bodies 16 and 16 are fixed to the nozzle outer ring 5 via the mounting bolts 18, respectively. ing.

Therefore, according to the present embodiment, the nozzle outer ring 5 is provided with the annular hole 35 continuous in the circumferential direction, and the annular hole 35 is formed.
A plurality of through holes 36 for communicating the 35 with the annular chambers 21 arranged in the circumferential direction are provided.

With this structure, as shown in FIG.
The steam flowing in from 23 flows into the inner chamber 20 through the annular chamber 21, and the remaining part passes through the through hole 36 to form the annular hole.
Inflow into 35. As shown in FIG. 17, the steam that has flowed into the annular holes 35 sequentially flows into the respective annular chambers 21 through the respective through holes 36, and then passes through the respective communicating holes 19 and the respective inner chambers 20.
Flows in. The inflow rate of steam is very high, and the steam is instantaneously delivered into all the inner chambers 20.

In the structure shown in FIG. 1, a plurality of introduction holes 23 must be formed in order to introduce steam into a plurality of annular chambers 21 formed at appropriate intervals in the circumferential direction. According to this, only one introduction hole 23 communicating with any one of the annular chambers 21 needs to be bored, and it is possible to reduce the processing man-hours of the nozzle outer ring 5 and improve its strength.

Although the embodiment in which the present invention is applied to the fin segment 13 mounted between the turbine axle 2 and the nozzle outer race 5 has been described above, as shown in FIG. 1, the turbine axle 2 and the nozzle inner race 6 are combined. The present invention can also be applied to the nozzle packing 40 mounted between them.

This nozzle packing 40 has a bellows 41 similar to that described above.
The flange body 42 is fixed to the flange body 42 via a screw, and the flange body 42 is screwed to an annular packing holder 45 extending in the circumferential direction by a mounting bolt 43. The packing holder 45 is fitted on the inner peripheral surface 6a of the nozzle inner ring 6 and is screwed through a bolt (not shown).

Further, the packing holder 45 is provided with an introduction hole 46, one end of the introduction hole 46 is opened to the upstream side of the nozzle inner ring 6, and the other end is a communication chamber surrounded by the nozzle inner ring 6 and the packing holder 45.
It opens in 48. The high-pressure steam on the upstream side of the nozzle inner ring 6 flows into the communication chamber 48 through the introduction hole 46, and further through the through hole 50 formed in the mounting bolt 43, the bellows 41.
Flows into the inner chamber 51 of the.

According to this structure, the gap between the nozzle packings 40 can be adjusted effectively as in the fin segment 13 described above.

Further, it goes without saying that the present invention is applicable not only to the steam turbine but also to other turbomachines in general such as gas turbines and compressors.

In the above-mentioned embodiment, the bellows manufactured in advance are fixed to the fin segment and the flange main body, but if they have an elastic restoring force and a closed chamber having an internal chamber of a closed structure is formed, Obviously, it is not limited to bellows.

FIG. 18 shows the problem with the conventional turbine solved by this technique.

The DSS operation (Dairy Start) of the contact problem between the stationary part and the rotating part is applied to the thermal turbine as an auxiliary energy source for nuclear power generation
It is one of the most serious problems at present when strict operating conditions such as (Stop) are required, and the effect of the present invention that can solve this is very large.

From the perspective of performance improvement, a 700 MW class steam turbine can achieve an improvement in turbine internal efficiency of 0.6% at high pressure, 0.4% at medium pressure, and 0.3% at low pressure, which is 0.4% improvement in turbine heat consumption rate. Can be achieved. This 0.4% is 1-year
This is equivalent to a fuel saving amount of 300 million yen, and this efficiency improvement amount is also very large, and the simple structure reduces the number of parts and greatly improves the reliability.

〔The invention's effect〕

With the above-mentioned configuration, according to the present invention, the gap of the seal portion can be adjusted very easily according to the load of the turbine.

When the turbine has a low load, the gap is widened to avoid contact between the rotating and stationary parts, improving turbine reliability.In addition, rubbing vibration due to contact between the rotating and stationary parts is prevented, improving turbine drivability. To do.

When the turbine has a high load, the gap can be narrowed to improve the internal efficiency of the turbine and ultimately improve the heat consumption rate of the turbine. Moreover, in the present invention, since the communication hole that is formed in each mounting bolt and opens in each bellows is communicated with the annular hole provided in the stationary portion through the communication hole, the introduction that communicates with the upstream side of the stationary portion. Since it is sufficient to form one hole, it is possible to reduce the number of processing steps for the outer ring of the nozzle and prevent the strength of the outer ring from decreasing.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a seal portion clearance adjusting device of the present invention, and FIG. 2 is a horizontal and vertical sectional view of the turbine moving blade portion,
FIG. 3 is an enlarged vertical sectional view showing an embodiment of a sealing device for a turbine rotor blade, FIGS. 4 (a) and 4 (b) are drawings showing dimensions of fin segments, and FIG. 5 is a turbine load and a sealing portion. FIG. 6 is a longitudinal sectional view showing the operation of the seal gap clearance adjusting device of the turbine rotor blade, and FIG. 8 is a view showing the relationship between the turbine load and the fin segment. FIG. 9 is a diagram showing the relationship with the moving amount, FIG. 9 is a diagram showing the relationship between the turbine load, the moving amount of the fin segment and the displacement difference between the rotating part and the stationary part, and FIGS. 10 and 11 are modification examples of the present invention. FIG. 12 is a vertical cross-sectional view showing the operation of the seal part clearance adjusting device for the turbine rotor blade part, and FIGS. 12 and 13 are vertical cross-sectional views showing the mounting state of the seal part clearance adjusting device for the turbine rotor part of the modified example of the present invention. FIG. 14 is a modification of the present invention shown in FIG. 12 and FIG. Graph showing the relationship between the turbine load and the amount of movement of the fin segments based, FIG. 15 No. 13
FIG. 16 is a vertical cross-sectional view showing the operation of the seal gap adjusting device of the turbine rotor blade portion of the modified example of the invention shown in FIGS.
FIG. 17 is a vertical cross-sectional view showing a modified example of the steam introduction hole in the present invention, FIG. 17 is a view taken along the line AA of FIG. 16, and FIG. 18 is a view for explaining the effect of the implementation of the present invention. FIG. 19 is a partial longitudinal upper half view of the turbine, FIG. 20 is a vertical cross-sectional view showing the structure of a fixed seal portion in a conventional turbine, and FIG. 21 is a vertical cross-sectional view showing a conventional movable seal device. . 1 ... moving blade, 2 ... turbine axle, 5 ... nozzle outer ring,
6 ... Nozzle inner ring, 11 ... Mounting groove, 12 ... Seal fin, 13 ... Fin segment, 15 ... Sealing chamber, 18 ... Mounting bolt, 20 ... Inner chamber, 21 ... Annular chamber, 23 ... … Introduction hole, 25 …… outer chamber, 30 …… concave groove, 35 …… annular hole, 36 ……
Through hole.

Claims (1)

[Claims] 1. A plurality of sealing fin segments arranged in the circumferential direction facing a rotating part of a turbine are attached to a stationary part of the turbine via bellows each having elastic elastic restoring force. In a seal part clearance adjusting device of a turbine, wherein each fin segment is movable in a radial direction of a turbine by a pressure difference of working fluid supplied to the inside and outside, in each mounting bolt for mounting the bellows on a stationary part, The communication hole opening in the bellows is communicated with the annular hole provided in the stationary portion through the through hole and the annular chamber formed on the outer periphery of the mounting bolt, and one of the annular chambers is provided on the upstream side of the stationary portion. Along with communicating the introducing holes, a concave groove extending in the circumferential direction is formed on the side wall portion of the fin segment mounting groove provided in the stationary portion, and both end edges of the fin segment are formed in the concave groove. The fins segment is characterized in that engaged to be movable in a predetermined range radially turbine seal portion clearance adjustment device.