JPS5912103A - Labyrinth packing - Google Patents

Abstract

PURPOSE:To prevent the amount of fluid leakage from increasing and yet opposing member from being damaged by a structure wherein packing fins to form the leakage passage of turbine working fluid are composed of bimetal, which deforms in the direction to narrow the leakage passage at high temperature and yet at the tip of which wearing part is provided. CONSTITUTION:A packing ring 4 is fixed to a casing 3 by means of an expansion member 5. A plurality of the packing fins 6 are provided on the surface of the ring 4 at the side opposing to a turbine rotor 1. The tips of fins 6 are free end and are arranged near the surface of the rotor 1 equipped with circumferential grooves 2. In this case, said packing fin 6 is made of bimetal comprising two sheet plates 7 and 8, the thermal expansion conefficients of which are different from each other and at the same time arranged in parallel with a sheet plate 9 made of wearable material at the side near the surface of the rotor 1. Due to the structure just mentioned above, the fins are deformed in the drection so as to narrow the leakage passage at high temperature and at the same time, if the fins 6 come into contact with the rotor 1 or the like, the sheet plates 9 are ready to wear themselves.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to labyrinth packings used in steam turbines, etc.

Technical background of the invention and its problems] General 1: Various gaskets are used to prevent leakage of turbine working fluid, such as steam, of a turbine. For example, there is a birind packing used to prevent steam from leaking from the leakage passage along the rotor axis, which occurs in the gap between the turbine rotor and the casing of a steam turbine. Rinse packing is used on the surface of the turbine rotor (: the turbine rotor shaft is provided with many circumferential grooves, and the casing (one end is fixed on the fin), the other end is a self-contained end, and is close to the grooved surface of the turbine rotor. A plurality of these packing fins are provided in the axial direction of the turbine rotor.
A number of narrow parts and enlarged parts are formed in the gap between the turbine rotor and the casing.

If one Nibirin patchkin is provided like this,
The leaking steam is constricted in the narrow part, and the speed is reduced in the expanded part (2), which is repeated to prevent steam leakage.

However, for steam turbine operation, e.g.
Since high-temperature and high-pressure steam of about 246J$/c+J is used,
As the temperature rises during operation of the steam turbine, leakage passages such as the gap between the casing and the turbine rotor expand due to thermal expansion (2), resulting in an increase in the amount of leaked steam. There was also the problem that an increase in leakage steam caused a pressure loss and reduced the efficiency of the steam turbine.

Such leakage of steam due to thermal expansion has become more prominent as the steam temperature and pressure become higher in order to improve efficiency.

Possible ways to prevent the above-mentioned leaks include reducing the distance between the packing fins and the turbine rotor, increasing the number of packing fins, etc., but the former prevents the operational trouble of rubbing (double-connected turbine rotor). There was a problem of damage to the rotor, etc., and the latter caused problems such as an increase in the span and a corresponding lengthening of the turbine rotor, so there was a natural limit, and it was extremely difficult to reduce the amount of leaked steam. .

[Purpose of the invention]

The present invention has been made in consideration of the above points, and it is an object of the present invention to provide a labyrinth packing that reduces leakage of turbine working fluid, improves turbine efficiency, and prevents damage to a turbine rotor, etc. purpose.

[Summary of the invention]

The labyrinth packing of the present invention provides leakage passages (two narrow spaces) for turbine working fluid, such as the gap between the turbine rotor and the casing, the gap between the turbine rotor and the inner ring of the nozzle diaphragm, and the gap between the casing and the rotor blades.

An L fin (made of bimetal) that forms the enlarged portion is provided. This bimetal fin is configured to be displaced in the direction of narrowing this leakage passage in the high temperature environment during turbine operation. (The tip of the packing fin is made of an abrasive material. This abrasive material may be joined to the packing fin as a plate.) .

Since high-temperature, high-pressure fluid such as steam or high-temperature combustion gas is used as the turbine working fluid, the gaps in the leakage passages described above widen due to thermal expansion of the casing, turbine rotor, etc. as the temperature -F increases during turbine operation. According to the present invention I, the packing fin is displaced so as to narrow the leakage passage due to the metal effect (2), so thermal expansion (2) increases the leakage amount of the turbine working fluid due to the widening of the leakage passage. Even if the tip of the packing fin comes into contact with, for example, a turbine rotor, etc., the packing fin will wear out more quickly because it is equipped with abrasive material. turbine rotor,
No damage to rotor blades etc.

[Embodiments of the Invention] An embodiment in which the present invention is used for preventing steam leakage from a gap between a turbine rotor and a casing of a steam turbine is shown. Figure 2 i2 shows an enlarged view of the main part a in Figure 1.

On the surface of the turbine rotor (1), there is a surface of the turbine rotor (1).
) A plurality of circumferential grooves (2) coaxial with the rotating shaft are provided in the axial direction. The arc-shaped packing ring (4) is still attached to the casing (3) with an extensible fixing member such as a spring (
5) (Fixed with two, Patsukin ring like this (3)
A plurality of them are combined to form an annular shape.

Turbine rotor (1) 1″ of this packing ring (3)
A plurality of packing fins (6) are provided on one opposing surface along the axial direction of the turbine rotor (1), and one end of the packing fin (6) is provided with a packing ring (4).
) 1 is fixed, and the other end is provided as a free end so as to be close to the surface on which the circumferential groove (2) of the turbine rotor (1) is provided. Therefore, the gap between the free end of the packing fin (6) and the surface of the turbine rotor (1) prevents silver from leaking in the narrow part of the leakage passage.

This packing fin (6) is made of 13% Cr-Fe ferritic stainless steel as a plate material (8) with a low thermal expansion coefficient, and 18% Ni-12% cr-F6 austenite as a plate material (7) with a high thermal expansion coefficient. stainless steel.

The plate material (9) made of an abrasive material is, for example, a bonded plate in which 0 holes are bonded in this order. The shape ranges from a plate material with a high coefficient of thermal expansion (80cm) to a plate material with a low coefficient of thermal expansion (8
) The plate member (9) made of an abrasive material is curved in a convex manner and is closest to the surface of the turbine rotor (1). Each plate material (7), t
s), <9) and the degree of curvature of the packing fin (6) are such that the tip of the packing fin (6) does not come into contact with the surface of the turbine rotor (1) in the high-temperature environment during turbine operation, and the leakage path is prevented. Do not widen the spacing (''-set as appropriate during design.

In a steam turbine with two configurations, the hot steam (-) is located north of the turbine rotor (1) and the casing (
3) The gap between the turbine rotor (1) and the casing (3) widens as both of them undergo thermal expansion, but due to the bimetal effect, the packing fin (6) is displaced in the horizontal direction to narrow this gap. The gap between the free end of the packing fin (6) and the surface of the turbine rotor (1) does not widen. , it is possible to prevent an increase in the amount of leaked steam due to the widening of this interval, thereby improving steam turbine efficiency.

Further, since this gap can be controlled by adjusting the displacement position due to bimetal effect 1, the amount of leaked steam can be reduced without increasing the number of parts.

Furthermore, when designing, it is only necessary to take into account the expansion of the gap due to thermal expansion and the displacement due to the bimetallic effect of the packing fin, so 1: is relatively easy.

In recent years, there has been a trend to increase the temperature of steam to a higher temperature in order to improve thermal efficiency. In addition, as the temperature and pressure increase, the use of conventional iron-based ferritic steel (instead, iron-based austenitic steel is being considered) for materials such as turbine rotors and casings. The thermal expansion coefficient of the former is approximately 12.5 x 10-'°C (compared to the latter, it is approximately 18.5 x 1σ-'°C, which is 1.5 times larger. Therefore, the gap between the two becomes noticeably wider due to thermal expansion. By giving the packing fin (6) itself a bimetal effect as in the present invention, it is possible to increase the amount of displacement in the length of the packing fin (6), so the effect of the present invention is particularly effective. .

In addition, the packing ring (4) is an expandable fixing member (5).
(Since it is fixed with :, if the packing fin (6) comes into contact with the turbine rotor (1) for some reason, this fixing member (5) will contract and alleviate the contact between the packing fin (6) and the turbine rotor.) 1. Damage to the turbine rotor (1) due to this contact can be prevented.Furthermore, since the curved packing fin (6) itself has a spring effect, if such a contact occurs, it can be quickly removed. (=The packing fin (6) is shrunk and damage to the turbine rotor (1) can be prevented.

The tip of the packing fin (6) is made of abrasive material, so if the packing fin (6) comes into contact with the turbine rotor (1) for some reason, the packing fin (6) will quickly wear out and the turbine rotor ( 1) damage can be prevented.

The packing fin (6) can be fixed to the packing ring (41) by any general fixing method such as implantation, bolting, welding, pinning, or caulking. If the convex surface is placed on the low pressure side B (2 positions), the high pressure steam will cause the packing fins (6
) is pushed, and the packing fin (6) is displaced in a direction that narrows the steam leakage passage, thereby further reducing the amount of steam leakage.

In addition, when the packing fin (6) is placed in a high pressure environment, it should have a certain degree of strength and the turbine rotor (1) ('''
--In the case of contact, the turbine rotor (1) 1- It is necessary to have enough abrasion to not cause damage, but in this example, a plate material (7) with a high coefficient of thermal expansion and a plate material with a low coefficient of thermal expansion are used. This strength can be achieved by (8),
This abrasive property can be provided by the abrasive material (9), and strength and abrasive properties can be satisfied at the same time.

This example (-In addition to the shape of the packing fin shown,
Direction 1 of narrowing the steam leakage passage in a high-temperature environment: It goes without saying that the effects of the present invention can be obtained by using a packing fin made of a displacing bimetal. For example, a bent bimetal may be used, or a bimetal with a partially curved portion may be used.Also, a bimetal with a plurality of curved portions may be used. By providing several curved parts, the displacement of the packing fin can be increased.Also, even if it is not curved,
A similar effect can be obtained with a packing fin in which a bimetal is implanted diagonally so that the side with a high coefficient of thermal expansion approaches the packing ring.

The joining order of the respective plate materials constituting the packing fin is not limited to the embodiment shown in FIGS. 1 and 2. Other embodiments of the present invention are shown in FIG.

FIG. 3 - In the embodiment shown, a plate (9) made of abrasive material
) is sandwiched between a plate material (8) having a high coefficient of thermal expansion and a plate material (8) having a low coefficient of thermal expansion to form a packing fin (6).
The shape of the plate (6) is curved in a dogleg shape so as to convex from the plate material (8) with a high coefficient of thermal expansion to the plate material (8) with a low coefficient of thermal expansion, and the tip is a plate material (8) made of an abrasive material. 9) so that it protrudes and tapers toward the tip (
It is said to have a tapered shape. The other configurations are the same as the embodiment shown in FIGS. 1 and 2, and the packing ring f4) i
n packing fin (61 is joined, turbine rotor (
1) It has a structure in which the tip of the packing fin (6) is close to the surface.

Fig. 3 (It goes without saying that the embodiment shown in Fig. 2 also achieves the same effect as the embodiment shown in Figs. The effect of preventing damage to the turbine rotor (1), which is prone to wear, is further increased.

If the plates are joined without being aligned at the tip of the packing fin, the number of narrow parts can be increased without increasing the number of packing fins, and the sealing effect of the labyrinth packing can be further increased.

Figure 4 (2 schematically shows an embodiment of the present invention in which the plates are joined without being aligned at the two tips. In the packing fin (6) of this embodiment, the plate (9) made of an abrasive material has a high coefficient of thermal expansion. Plate material with strength and low thermal expansion coefficient (
A plate member (9) made of an abrasive material is joined at the tip of the packing fin (6) so as to protrude from the tip of the packing fin (6).
6) is diagonally placed so that the plate material (7) with a high coefficient of thermal expansion is close to the packing ring (4).
), and the tip is connected to the turbine rotor (1) E
configured to be close to each other. With this configuration, the narrow portions C, C/
Can be composed of one piece of Patsukin fin (6)
Since two narrow portions are formed, the sealing effect is increased. The other configurations are similar to those of the embodiment shown in FIGS. 1 and 2, and it is impossible to obtain the same effect as this embodiment.

In the above embodiments, the tips of the packing fins are made abrasive by using a plate made of an abrasive material, but the abrasive material may be provided only at the tips of the packing fins. In terms of manufacturing, it is easier to use a plate material.

In the above embodiments, the case where the packing ring 1 and the packing fin are joined together has been described, but the packing fin may be provided directly on the casing. In this way, directly casing 1'
″- Even when a packing fin is provided, the packing fin itself can have a double spring effect as described above, so it is possible to obtain the same effect as fixing the packing ring with an expandable fixing member. (2) Since the present invention can prevent the leakage passage from widening, it is possible to reduce or eliminate the depth of the circular frequency waves on the surface of the turbine rotor, which are provided (1) to reduce steam leakage.

These circumferential grooves tend to cause concentration of thermal stress and vapor quality, contributing to environmental damage to the turbine rotor such as stress corrosion cracking and corrosion. This cause of environmental damage to the turbine rotor can be eliminated, and the reliability of the turbine can be improved.

In addition to preventing steam leakage from the gap between the turbine rotor and the casing, it also prevents steam leakage from steam leakage passages in the axial direction of the turbine rotor, such as the gap between the casing and the rotor blades, and the gap between the nozzle diaphragm and the turbine rotor. It may be used for

Another embodiment of the present invention is shown in FIG. 4 (1=schematic) using a 1-nivirin packing to prevent steam leakage from the gap between the moving XH and the casing (3).

The casing (3) l- is made of a plate material (7) having a high coefficient of thermal expansion.
), a plate material (8) having a low coefficient of thermal expansion, and a plate material (9) made of an abrasive material are joined.
) are fixed, and a plurality of rotor blades Ql are provided in the direction of the rotation axis of the rotor blade Ql. This packing fin (6) is constructed so that the plate (9) made of an abrasive material is closest to the rotor blade. It is convex (= curved).

With the labyrinth packing constructed in this way, the bimetal effect of the packing fins (6) can cancel out the expansion of the gap due to thermal expansion (due to the rise in temperature during turbine operation), thereby reducing the amount of leaked steam. Also, since the packing fin (6) has a spring effect, even if the packing fin (6) comes into contact with the moving blade for some reason, this contact can be alleviated, and the moving blade (
II can be prevented from being damaged. In addition, since the tip of the packing fin (6) is made of an abrasive material, even if they come into contact, the packing fin (6) will quickly wear out (the two sides will wear out and the rotor blade Ql).
This can prevent damage.

[Effects of the Invention] As explained above, according to the present invention, it is possible to prevent an increase in the leakage of the working fluid caused by the expansion of the leakage passage of the turbine working fluid due to thermal expansion (1), thereby improving the turbine efficiency. Therefore, it has the advantage of greatly saving fuel costs and is extremely effective.Also, even if the packing fin comes into contact with the turbine rotor, the turbine rotor etc. will not be damaged, so the turbine operation will be interrupted. (It is very effective (= effective).

[Brief explanation of drawings]

Fig. 1 is a partial sectional view of a steam turbine for detailed explanation of the present invention, Fig. 2 is an enlarged view of the fish tank section a in Fig. 1, and M3.
5 through 5 are schematic cross-sectional views showing other embodiments of the present invention. 6... Packing fin 7... Plate material having a high coefficient of thermal expansion 8... Plate material having a low coefficient of thermal expansion 9... Plate material made of abrasive material (7317) Agent Patent attorney Noriyuki Chika (
1 other person) Figure 1 Figure 2 Figure 8! Figure 4 Figure 5

Claims (1)

[Claims] In a labyrinth packing provided with packing fins provided to form a leakage passage (two narrow parts and an enlarged part) of the turbine working fluid, the packing fins narrow the leakage passage in a high-temperature environment during turbine operation in a direction 1'- 1. A labyrinth packing made of a displacing bimetal, characterized in that the tip of the packing fin is made of an abrasive material.