JPS61132706A - Ajuster for clearance at sealing area of turbine - Google Patents

Abstract

PURPOSE:To adjust a clearance at a sealing area simply by fitting sealing fin segments to stationary parts via bellows, and introducing high pressure or low pressure into the bellows. CONSTITUTION:Bellows 11, 11a are interposed and mounted between sealing segments 8, 8a and stationary parts 3, 4 respectively, so as to be movable in radial direction. Insides of bellows 11, 11a are communicated to both high pressure section and low press section of a turbine via a regulator valve 14 and a switching valve 16 respectively so that both high pressure and low pressure way be introduced therein. Thus, a clearance at a sealing area can be adjusted simply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for adjusting the radial gap of a seal portion of a turbine.

[Technical background of the invention and its problems] In recent years, in response to the increase in fuel prices, improving turbine performance has become increasingly important, and various performance improvement measures have been proposed.

By the way, the most effective measure to improve performance is to reduce the amount of steam leaking through the gaps between the stationary part and the rotating part, which inevitably exist in each part of the turbine.

That is, FIG. 6 is a diagram showing the upper half of the assembled cross section of the steam turbine, and shows the areas between the rotor blades 2 fixedly attached to the turbine axle 1 and the nozzle outer ring 3, and between the turbine axle 1 and the nozzle inner ring 4. A seal device for preventing steam leakage called a tip fin, a nozzle packing, or a gland packing is provided between the turbine axle 1 and the casing 5. By the way, FIG. 7 is a sectional view showing a sealing device (tip fin) between the dynamic R2 and the nozzle outer ring 3 as an example of the sealing device for each of the above parts,
A dovetail-shaped mounting groove 6 extending in the circumferential direction is formed in the nozzle outer ring 3, which is a stationary part, in a portion facing the outer peripheral end of the rotor blade 2. A segment 8 provided with a plurality of circumferentially extending seal fins 7 protruding toward the surface is engaged with and attached to the seal fins 7.
A predetermined minute gap is maintained between the rotor blade 2 and the tip of the rotor blade 2, which is a rotating body, so that steam leakage is minimized.

By the way, in this type of non-contact type sealing device, the biggest factor that determines the steam leakage prevention effect is the size of the gap between the tip of the seal fin 7 and the rotating body, and the smaller the gap, the greater the leakage amount. However, if this gap is made too small, the seal fin and rotating part may come into contact with each other during operation, damaging the rotating part or seal fin, or the contact may increase shaft vibration, making it impossible to continue operation. There are also problems such as bending of the rotating part due to heat generation due to contact.

Such contact occurs because the gap value changes depending on the operating state of the turbine, and such changes are caused by various factors such as uneven thermal deformation of the casing, deformation due to pressure, or the support characteristics of the bearing that supports the turbine axle. This is caused by the following factors. Therefore, when designing and assembling a normal turbine, the gap must be set taking into account the above conditions.

However, the gap value changes only when starting, stopping,
Alternatively, most of the time occurs when the load changes, and during steady operation, the amount of deformation and the change m settle down to a constant value over time, so the change m in the gap is extremely small. Therefore, with the current method of operation, in which the gap is set in consideration of the gap state during startup, stoppage, and load changes, the gap becomes unnecessarily large during steady-state operation, which is the longest period of operation, and the effectiveness of preventing steam leakage increases. becomes insufficient.

However, in order to eliminate such problems, it is necessary to install some kind of drive mechanism between the fin segments and the stationary part, and change the gap depending on the operating condition or the measured value of the gap between the seal parts. It is conceivable to provide a movable seal structure.

However, using a gear device, hydraulic device, etc. as such a drive mechanism requires a large amount of space due to the complicated mechanism, and there are also environmental constraints such as being exposed to high temperature and high pressure steam. Due to the unique conditions of the turbine, it is extremely difficult to put it into practical use.

[Object of the Invention] In view of these points, the present invention provides a movable sealing mechanism and uses a driving device using steam power as a device for moving the sealing mechanism and adjusting the gap between the sealing parts. It is an object of the present invention to provide a seal gap adjustment device that does not have the above-mentioned problems.

[Summary of the invention]

The present invention enables a sealing fin segment disposed facing the rotating part of the turbine to be moved in the radial direction to a stationary part of the turbine, and a bellows is inserted between the stationary part and the fin segment. , the interior of the vessel is communicated with multiple positions at different pressures in either one of the high-pressure part and the low-pressure part of the turbine via a selection valve, and communicated with the other appropriate position via a switching valve. The internal pressure applied to the bellows is changed by appropriately selectively opening and closing the above-mentioned selection valve, and the pressure difference between the inside and outside of the bellows is maintained within an appropriate pressure range according to the operating state of the turbine. This allows the gap to be adjusted to the optimum value.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 2 denotes a rotor blade provided on the turbine axle 1, and immediately upstream of the rotor blade 2 is a nozzle outer ring 3.
A nozzle m9 is disposed fixedly between the nozzle inner rings 4, and the nozzle outer ring 3 is mounted on the stationary part 10 of the turbine.

Incidentally, the nozzle outer ring 3 is formed with a dovetail-shaped mounting groove 6 extending in the circumferential direction at a position facing the outer circumferential portion of the tip of the rotor blade 2, and the attachment groove 6 is formed in the nozzle outer ring 3 at a position facing the outer circumference of the tip of the rotor blade 2. A plurality of arc-shaped fin segments 8 each have a plurality of circumferentially extending seal fins 7 protruding from a surface facing the outer peripheral surface.
As shown in FIG. 2, they are arranged and mounted in the circumferential direction. Each of the fin segments 8 is mounted so as to be able to move to a certain degree in the radial direction with respect to the mounting groove 6, and several pieces (two in the figure) are provided between the inner surface of the mounting groove 6 and each fin segment 8. The bellows 11 are interposed, and the bellows 11
The outer end of the fin segment 8 is attached to the inner peripheral surface of the mounting groove 6, and the inner end thereof is attached to the outer surface of the fin segment 8.

Each bellows 11 includes a conduit 12 and a plurality of branch pipes 13a and 13b branched from the conduit 12.

13c, the bellows 11 is connected to a plurality of locations of the turbine at higher pressure than the installed position of the bellows 11.

That is, the branch pipe 13a is opened, for example, in a passage part one stage before the tongue 11 installation stage, 13b is opened in a passage part two stages before, and 13G is opened in a working fluid inlet pipe, etc., and each branch pipe 13a, 13b.

Selection valves 14a and 14b are provided at 13c, respectively.

14c is provided. Further, the bellows 11 is connected to the low pressure section of the turbine, that is, the blade outlet side of the stage where the bellows 11 is provided, via a conduit 15 connected to the conduit 12, and the bellows 11 is connected to the blade outlet side of the stage in which the bellows 11 is provided. Valve 1
6 is provided.

On the other hand, a fin segment 8a is also attached to the surface of the nozzle inner ring 4 facing the turbine axle 1 in the same manner as described above, and a bellows 11a provided on the back surface of the fin segment 8a is also connected to the conduit 12, and a branch pipe 13a, 13b, 13C
It is communicated via J3 and conduit 15 with multiple high pressure parts and low pressure parts of the turbine.

Then, the switching valve 16 is closed and the selection valve 14a is closed.

When you open either 14b or 14C, Be 0-11
．． The pressure inside 11a increases and the fin segments 8, 8a
is adjusted so that the gap between the fin segment 8 and the outer periphery of the rotor blade 2 and the gap between the fin segment 8a and the turbine axle 1 are narrowed. Moreover, the selection valve 14a.

Each branch pipe 13a is provided with 14b and 14c.

Since the selection valves 13b and 13G are opened in sequentially high pressure parts in the turbine, the selection valves 14a to be opened are
, 14b, and 14c, the pressure inside the bellows 11.11a increases one after another, and when the external pressure of the bellows is constant, the gap between the fin segments 8 and 8a can be reduced.

On the other hand, if the selection valves 14a, 14b, 14c are closed and the switching valve 16 is opened, the internal pressure of the bellows 11, 118 decreases, the bellows 11.11a contract, and the fin segments 8,
The gap between 8a and the rotating body can be increased.

By the way, in general, bellows 11.11a are not designed as structurally strong materials, so if the pressure difference between the inside and outside is too large, they will break.If the pressure difference is too small, the amount of expansion and contraction will be small, so it is difficult to set the desired gap amount. I can't.

In other words, FIG. 3 shows bellows 1 corresponding to the turbine load.
1.118 of the passage section of the installation section (external pressure of the bellows) P, and each branch pipe 13a, 13b.

13c is a diagram showing changes in the pressures Pa, Pb, and Pc at the opening of the turbine 13c, and the pressure at each part changes almost linearly according to the load of the turbine. Therefore, for example, when the switching valve 16 in FIG. 1 is closed and only the selection valve 14a is listened to, the pressure difference between the inside and outside of the bellow is the amount shown by X at 100% load, but becomes x1 at 50% load. This is approximately 1/2 of the time when the load is 100%.

Therefore, in the bellows designed based on the above X,
When the pressure difference is x1, the expansion m of the bellows is insufficient, and the gap between the fin segments 8, 8a and the rotating body may not be reduced to a predetermined amount.

On the other hand, the relationship between the gap between the fin segment and the rotating body and the pressure difference between the inside and outside of the bellows is shown in FIG. That is, inflate the bellows 11 and fin segment 8! 1j
When pushing out to the J wing side and trying to make the gap between them the minimum gap, the displacement position S at that time is as shown in Figure 4.
A pressure difference p between the inside and outside of the bellows is required. Therefore, when this pressure difference p is shown in Fig. 3, it becomes as shown in the figure, and 50
% load, pressure difference due to selection valve 14a1m x 1,
It is not possible to ensure the pressure difference p required to achieve the minimum gap. In this case, if the selection valve 1/1a is closed and the selection valve 14b is opened, the pressure difference between the inside and outside of the bellow becomes ×2,
The gap between the fin segment and the rotating body can be a minimum gap.

Furthermore, since there is a risk of damage to the bellows 11.11a if excessive pressure is applied unnecessarily, it is better not to apply pressure in excess of the required pressure difference as much as possible even when minimizing the gap. For example, if the selection valve 14G is opened and the other valves are closed at 100% load, a pressure difference of x3 will occur in Figure 3, but this will cause a pressure considerably greater than the required pressure difference p at the bellows 11.118. There will be a difference. Therefore, depending on the case, there is a possibility that the blade O-1, 118 may be damaged. Therefore, in the present invention, by opening the selection valve 14a at 100% load, the bellows 11.
A pressure difference of X, which is somewhat larger than p, is created at 11a, so that the gap between the seals is minimized.

In this way, when realizing the minimum gap of the sealing part, the intake part of the pressure fluid can be controlled according to the load, so that the bellows are always kept from being subjected to a pressure difference within an appropriate range.

By the way, the conduit 12 connected to the bellows 11 is provided with a first pressure detector 17 for detecting the pressure inside the conduit (bellow internal pressure), and the bellows 1 in the turbine is
A second pressure detector 18 for detecting the external pressure of the bellows 11 is provided near the bellows 11, and both positive force detectors 17 and 18
The detected pressure signal is manually input to the program setting device 19. Further, a gap target signal 20 is also applied to the program setting device 19 from the outside, and each selection valve 14a, 14b is controlled by the output signal from the program setting device 19.

14G and the switching valve 16 are controlled to open and close. When the gap target signal 20 corresponding to the operating condition of the turbine is input to the program setting device 19, a signal indicating that the switching valve 16 is open is first output, and the switching valve 16 is closed. Meanwhile, at the same time, an open signal is output to a selection valve, for example 14b, at a position such that an optimum pressure is applied inside the bellows in response to the bellows external pressure detected from the second pressure detector 18, and thereby the valve 14b is is opened, and the fin segments 8, 8a are brought closer to the corresponding rotating body side in the manner described above, and the gap therebetween is maintained at an optimum value. Also, at this point, the internal pressure of the bellows and the external pressure of the bellows are compared, and this is checked against the previously known elastic deformation characteristics of the bellows to confirm that the gap is appropriate.

On the other hand, when the turbine is started, when large vibrations occur, when the above-mentioned gap becomes less than a predetermined value, or when abnormal noise due to contact is confirmed, a signal from the program setting device 19 ^Pressure side selection valves 14a, 1
4b and 14c are closed, and the low pressure side switching valve 16 is opened. Therefore, the pressure in the bellows 11.11a becomes equal to the pressure in the low-pressure part of the turbine, the bellows 11.11a contracts, the fin segment 8.8a retracts, and the gap in that part increases.

By the way, since the pressure in each part of the turbine has a characteristic that is almost proportional to the load as described above, it is not necessary to install the second pressure detector 18 near the bellows 11, and it is not necessary to install the second pressure detector 18 near the bellows 11. Measure the pressure at a point, simple proportionality = 1
By calculation, the bellows external pressure and the pressure at each pressure intake can be determined fairly accurately. Thereby, a pressure intake point that matches the gap target signal can be selected using a simple program. Further, it is desirable that the program setting device be provided with a safety circuit so as to immediately open the switching valve 16 when the difference between the conduit pressure and the external pressure of the bellows becomes too large and there is a possibility that the bellows will be damaged.

FIG. 5 shows another embodiment of the present invention.
1a is a conduit 12 and a branch conduit 21 branched from it
a, 21b, and 21c are connected to multiple locations with lower pressure than the installation position of the bellows, and each branch conduit 2
1a, 21b.

21c is provided with selection valves 22a, 22b, and 22c, respectively.

By listening to the selection valves on the low pressure side one after another, the fin segments 8, 8a can be moved to the retracted position and adjusted so that the gap between the seals becomes wider one after another. In this case, since a large number of selection valves can be disposed on the low pressure side, that is, on the low temperature side, the cost can be reduced.

〔Effect of the invention〕

Since the present invention is configured as described above, the gap between the seal parts can be adjusted extremely easily depending on the operating state of the turbine, and since no external power such as a motor is used as the drive mechanism, there is no energy loss. Furthermore, since there is no mechanical drive unit such as a gear, reliability can be increased. Furthermore, in the present invention, the pressure for driving the fin segments is selectively taken in from different pressure points, so the pressure applied to the bellows can be selected to be the optimal value for the operating condition of the turbine, and excessive force can be avoided on the bellows. It is possible to prevent this from occurring, and also to maintain the interval between the seal portions at an optimum value, thereby improving turbine performance.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of an embodiment of the seal gap adjustment device of the present invention, Fig. 2 is a longitudinal sectional front view showing the sealing device of the turbine #Jπ section, and Fig. 3 is the bellows operation in response to the load of the turbine. Fig. 4 is a diagram showing the relationship between the pressure difference between the inside and outside of the bellows and the displacement of the bellows, Fig. 5 is a diagram showing another embodiment of the present invention, Fig. 6 7 is a partially vertical upper half view of a turbine, and FIG. 7 is a longitudinal sectional view showing the configuration of a seal portion in a conventional turbine. 1... Turbine axle, 2... arA, 3... Nozzle outer ring. , 4... Nozzle inner ring, 6... Mounting groove, 8, 8
a... Fin segment, 11.11a... Bellows, 14a. 14b, 14c... Selection valve, 16... Switching valve, 19
...Program setting device. Applicant's agent Kiyotsu Inomata 3 Ward No. 4 Figure P Pressure difference certain 5 Prisoner 6 Figure 7

Claims (1)

[Claims] 1. A sealing fin segment disposed opposite to the rotating part of the turbine is movable in the radial direction to a stationary part of the turbine, and a bellows is inserted between the stationary part and the fin segment. The inside of the bellows is connected to a plurality of positions having different pressures in one of the high-pressure part and the low-pressure part of the turbine, and to an appropriate position in the other part, respectively, through a selection valve or a switching valve. , turbine seal gap adjustment device. 2. The turbine according to claim 1, wherein the selection valve is selectively opened and closed depending on the operating state of the turbine, and is maintained so that the difference in pressure between the inside and outside of the bellows is within an appropriate pressure range. Seal gap adjustment device.