JP2017008730A - Steam turbine seal device and steam turbine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steam turbine seal device that includes both of machinability with respect to a fin mounted to a tip of a rotor blade and an anti-erosion property with respect to flowing steam.SOLUTION: The steam turbine seal device includes multiple seal fins 2 in a body of one of a rotary part 5 and a stationary part 4 that are arranged while having an interval therebetween so as to seal a steam leakage from the interval. The seal fin 2 is a metal seal fin.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to a steam turbine seal device that is provided in a gap between a rotating portion and a stationary portion of a steam turbine and suppresses steam leakage, and a steam turbine to which the seal device is applied.

About 20% of the loss generated inside the steam turbine is loss due to steam leakage from the tip of the rotor blade, which is a rotating part.

In the prior art, it has been studied to perform thermal spraying using a powder of a Ni-base alloy, a Co-base alloy, or a MCrAlY alloy system, and coat a stationary portion of a steam turbine to form a seal.

In addition, it has been studied to mix clay in Ni, Cr and Al and form a seal on the stationary part of the steam turbine by pressing, sintering, brazing or spraying.

JP 2013-12227 A JP 2003-65076 A

However, in the method of spraying using Ni-based alloy, Co-based alloy or MCrAlY alloy-based powder and coating the stationary part of the steam turbine to form a seal, the coating itself is a porous material, Although it has machinability with respect to the fin attached to the tip, the erosion resistance against the steam flowing in the gap between the rotating part and the stationary part of the steam turbine is inferior. Therefore, it is considered that the erosion phenomenon caused by the flowing steam occurs and the seal disappears in a short period of time.

The problem to be solved by the present invention is to provide a steam turbine seal device and a steam turbine that have both machinability for fins attached to the tips of moving blades or stationary blades and erosion resistance against flowing steam. .

The steam turbine seal device according to the present embodiment includes a plurality of sealing fins in the main body of either the rotating part or the stationary part arranged with a gap, and seals the leakage of steam from the gap. In the steam turbine seal device to be stopped, the seal fin is a metal seal fin.

In the steam turbine according to the present embodiment, the steam turbine seal device is applied to any one of the outer ring seal and the inner ring seal of the stationary blade or the moving blade of the high pressure portion, the intermediate pressure portion, and the low pressure portion of the steam turbine. Features.

According to the steam turbine seal device and the steam turbine according to the embodiment of the present invention, the machinability with respect to the fin attached to the tip of the moving blade and the erosion resistance with respect to the flowing steam are combined, and the performance degradation due to steam leakage is reduced. It can be suppressed and the service life can be improved.

The principal part expanded sectional view of the steam turbine seal apparatus which shows embodiment of this invention. The principal part expanded sectional view which shows embodiment which attached the steam turbine seal apparatus shown in FIG. 1 to the steam turbine stationary part. Explanatory drawing which shows the outline of the positional relationship with the fin of a steam turbine rotation part in the state which attached the steam turbine seal apparatus shown in FIG. 1 to the steam turbine stationary part. It is a figure which shows the shape of the fin of a steam turbine seal apparatus, (a) is sectional drawing of a seal fin, (b) is the A section expanded sectional view of (a). It is a figure which shows the dimension of the thickness of the fin of a steam turbine seal apparatus, (a) is sectional drawing of a seal fin, (b) is the B section expanded sectional view of (a). It is a figure which shows the height dimension of the fin of a steam turbine seal apparatus, (a) is sectional drawing of a seal fin, (b) is the C section expanded sectional view of (a). It is a figure which shows the dimension of the distance of the fin of a steam turbine seal apparatus, (a) is sectional drawing of a seal fin, (b) is the D section expanded sectional view of (a). (A) is a schematic sectional drawing which shows the principal part schematic structure of a steam turbine, (b) is sectional drawing which expands and shows the principal part E of the low voltage | pressure part shown to (a).

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is an enlarged cross-sectional view of a main part of a steam turbine seal device showing an embodiment of the present invention.

In FIG. 1, a steam turbine seal device 1 has metal seal fins 2. This metal seal fin 2 includes carbon steel, low alloy steel, stainless steel, high chromium (Cr) steel, nickel (Ni) base alloy steel, cobalt (Co) base including the steam turbine seal device 1 main body. It is made of any of alloy steel, titanium (Ti) or titanium alloy, copper (Cu) or copper alloy, aluminum (Al) or aluminum alloy.

The steam turbine seal device 1 is composed of a single metal or an alloy having a constant density including the seal fin and the main body, and thus has a certain erosion resistance against the flowing steam.

In order to improve the erosion resistance to the flowing steam in the steam turbine seal device 1, the surface of the steam turbine seal device 1 has a surface hardness of 1500 Hv or more by diffusion treatment or coating treatment, and is resistant to erosion and high temperature. Combines oxidizing properties.

The reason why the surface hardness is 1500 Hv is that the surface hardness of the object is about 500 Hv to 1500 Hv by surface treatment or overlay welding as a countermeasure against erosion inside the conventional steam turbine.

The surface diffusion treatment of the steam turbine seal device 1 in the present embodiment is performed using a technique such as nitriding treatment or boriding treatment. Moreover, the surface coating process of the steam turbine seal apparatus 1 in this embodiment performs coating of TiN, TiAlN, etc. using PVD (physical vapor deposition method) or CVD (chemical vapor deposition method) coating technology.

On the other hand, between the seal fin 2 and the seal fin 2 of the steam turbine seal device 1, a filling portion 3 using a filler 3 having better machinability than the seal fin 2 is formed. The filling portion 3 can be formed, for example, by thermal spraying using Co, Ni, Cr, Al, Y, or an alloy powder thereof.

FIG. 2 is an enlarged cross-sectional view of a main part showing an embodiment attached to the steam turbine stationary part 4 using the steam turbine seal device 1.

The steam turbine seal device 1 is welded, bonded or mechanically attached to the steam turbine stationary part 4.

FIG. 3 schematically shows the positional relationship between the steam turbine seal device 1 attached to the steam turbine stationary part 4 and the fins 6 of the steam turbine rotating part 5. By attaching the steam turbine seal device 1 to the steam turbine stationary part 4, it is possible to minimize steam leakage.

The same effect can be obtained even if the steam turbine seal device 1 is arranged in the steam turbine rotating part 5 and the fins 6 are installed in the steam turbine stationary part 4.

As described above, in this embodiment, the steam turbine seal device 1 having both machinability with respect to the fin 6 attached to the tip of the rotating portion 5 of the steam turbine and erosion resistance with respect to the steam is used as the stationary portion of the steam turbine. 4, the leakage of the steam is minimized, and at the same time, even if the fin 6 attached to the tip of the rotating portion 5 contacts the steam turbine seal device 1, the damage to the fin 6 is not reduced. Minimized.

Further, even if the flowing steam hits the steam turbine seal device 1, the surface is hardened and 150
Since the fin 2 having a surface hardness of 0 Hv or more has excellent erosion resistance, the filler 3 can also be protected.

Moreover, since the filler 3 is filled between the seal fin 2 and the seal fin 2, the seal fin 2 is suppressed from being pushed down by the pressure of the flowing steam.

According to the present embodiment, the steam turbine seal device 1 has a porous filling 3 and has machinability with respect to the fin 6 attached to the tip of the rotating portion 5 of the steam turbine. Even if 6 contacts the steam turbine seal device 1, damage to the fins 6 is minimized, and the service life of the fins 6 can be extended.

On the other hand, since the steam turbine seal device 1 has erosion resistance to the flowing steam, the thickness reduction due to the steam erosion can be minimized, and the use period of the steam turbine seal device 1 can be extended. If the use state of the fins 6 and the steam turbine seal device 1 is good, it is possible to suppress performance degradation due to steam leakage of the steam turbine.

(Second Embodiment)
4A and 4B are cross-sectional views showing the shape of the fin 2 of the steam turbine seal device 1 according to another embodiment of the present invention. FIG. 4A is a cross-sectional view of the seal fin, and FIG. It is sectional drawing.

As shown in FIG. 4, the seal fin 2 has a plate shape, a cross section is a triangle or a quadrangle,
The tip has a pointed shape. Considering contact with the fins 6 of the rotating part 5 of the steam turbine, the tip of the seal fin 2 is formed in a pointed shape, so that it is easy to break or crush when contacting the fins 6. To do.

FIG. 5 is a view showing the thickness dimension of the seal fin 2 of the steam turbine seal device 1 according to another embodiment of the present invention, where (a) is a sectional view of the seal fin, and (b) is (a). FIG.

The thickness of the seal fins 2 of the steam turbine seal device 1 is preferably less than 2 mm in consideration of contact with the fins 6 of the rotating part 5 of the steam turbine, but is preferably as thin as possible, but less than 100 μm. Since the steam flows from the side, the thickness of the seal fin 2 needs to be 100 μm to 2 mm in consideration of the erosion resistance life. Therefore, although it depends on the material (strength, toughness, ductility, hardness, composition) of the seal fin 2 of the steam turbine seal device 1, the appropriate thickness of the seal fin 2 is desirably 100 μm.

FIG. 6 is a view showing the height dimension of the fin 2 of the steam turbine seal device 1 according to another embodiment of the present invention, where (a) is a cross-sectional view of the seal fin, and (b) is a view of (a). It is a C section expanded sectional view.

As shown in FIG. 6, the height of the fin 2 is characterized by having a thickness of 100 μm to 10 mm in consideration of the distance between the rotating portion 5 of the steam turbine 5 and the wear due to contact.

Usually, the distance between the stationary part 4 and the rotating part 5 of the steam turbine is about 100 μm to about 5 mm, so the height of the fin 2 takes into account the distance from the fin 6 of the rotating part 5 of the steam turbine. 100 μm to 10 mm. Further, the height of the fins 2 of the steam turbine seal device 1 is more preferably 1 mm to 5 mm in consideration of the distance from the above-described rotation portion 5 of the steam turbine 5 and wear due to contact.

7A and 7B are diagrams showing the distance dimension between the fin 2 and the fin 2 of the steam turbine seal device 1 according to another embodiment of the present invention. FIG. 7A is a sectional view of the seal fin, and FIG. It is the D section expanded sectional view of a).

As shown in FIG. 7, the distance between the fin 2 and the fin 2 is determined based on the capacity of the filling 3, the erosion resistance effect of the fin 2 against the flowing steam, and the fin 2 itself due to contact with the fin 6 of the rotating portion 5 of the steam turbine. In consideration of the amount of wear, damage to the fins 6, the width of the stationary portion 4 of the steam turbine, and the durability of the steam turbine seal device 1, it is desirable that the thickness be 0.5 mm to 50 mm.

Fig.8 (a) is a schematic sectional drawing which shows the principal part schematic structure of the steam turbine 20 which is one Embodiment which concerns on this invention.

As shown in FIG. 8A, the steam turbine 20 is used for a thermal power plant.
The high-pressure part 21, the intermediate-pressure part 22, and the low-pressure part 23 are provided. On the other hand, although not shown, the high-pressure part 21 and the low-pressure part 23 are provided for the nuclear power plant, and the Part 23
It has.

The low pressure portion 23 of the steam turbine 20 is an enlarged view of the E portion of FIG. 8A, and as shown in FIG. 8B, the rotor blades 24 and the turbine rotor 25 of the steam turbine rotating portion 5, the steam turbine stationary portion. 4, a stationary blade 26, a casing 27, an outer ring seal 28 of the stationary blade 26, and an inner ring seal 29 of the stationary blade 26. In addition, as shown by the arrows in the figure, the steam flows from the left side to the right side in the figure.

As shown in FIG. 8B, fins 6 are installed at the tip of the moving blade 24 of the rotating unit 5 and the body of the turbine rotor 25.

As shown in FIG. 8B, the application position of the steam turbine seal device 1 according to an embodiment of the present invention is as an outer ring seal 28 of the stationary blade 26 of the steam turbine 20 and an inner ring seal 29 of the stationary blade 26. Yes.

The above-described metal steam turbine seal device 1 is applied to the steam turbine 20 according to the site.
It is also possible to change the metal material. The steam turbine seal device 1 applied to the high-pressure part 21 and the intermediate-pressure part 22 requires not only erosion resistance but also high-temperature oxidation resistance.
Use of any of stainless steel, high chromium (Cr) steel, nickel (Ni) base alloy steel, cobalt (Co) base alloy steel, titanium (Ti) or titanium alloy is desirable. On the other hand, the steam turbine seal device 1 applied to the low-pressure part 23 requires corrosion resistance as well as erosion resistance, and therefore any use of carbon steel, copper (Cu) or copper alloy, aluminum (Al) or aluminum alloy is used. Is desirable.

As described above, according to the present embodiment, by optimizing the shape, thickness, height, and fin interval of the fin 2 of the steam turbine seal device 1, the amount of erosion wear caused by the steam of the fin 2 itself and the fin The amount of damage given to 6 can be suppressed.

Further, the steam turbine seal device 1 having such a fin structure can be applied to an outer ring seal that is the tip of the rotor blade 24 of the rotating portion 5 of the steam turbine 20 and an inner ring seal that is a body of the turbine rotor 25.

This embodiment can be applied not only to a thermal steam turbine but also to a nuclear steam turbine and a geothermal steam turbine.

According to the present invention, the present invention is not limited only to the above-described embodiment, and the constituent elements may be modified without departing from the scope of the invention in the implementation stage. In addition, various inventions can be configured by appropriately combining a plurality of components disclosed in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Steam turbine sealing apparatus 2 ... Seal fin 3 ... Filling part 4 ... Steam turbine stationary part 5 ... Steam turbine rotating part 6 ... Fin 20 ... Steam turbine 21 ... High pressure part 22 ... Medium pressure part 23 ... Low pressure part 24 ... Moving blade 25 ... Turbine rotor 26 ... Stator blade 27 ... Casing 28 ... Outer ring seal 29 ... Inner ring seal

Claims (11)

In the steam turbine seal device that includes a plurality of seal fins in the main body in either one of the rotating part and the stationary part arranged with a gap, and seals steam leakage from the gap,
A steam turbine seal device, wherein the seal fin is a metal seal fin. The steam turbine seal device according to claim 1, wherein a filling portion using a filler having better machinability than the seal fin is formed between each of the plurality of seal fins. The seal fin and the main body are carbon steel, low alloy steel, stainless steel, Ni-base alloy steel,
3. The steam turbine seal device according to claim 1, wherein the steam turbine seal device is made of any one of Co-base alloy steel, copper or copper alloy, aluminum or aluminum alloy. The surface of the seal fin and the main body is subjected to diffusion treatment or coating treatment,
The steam turbine seal device according to any one of claims 1 to 3, wherein the surface hardness is 1500 Hv or more. 5. The steam turbine seal device according to claim 1, wherein the filling portion is formed by thermal spraying Co, Ni, Cr, Al, Y, or an alloy powder thereof. The steam turbine seal device according to any one of claims 1 to 5, wherein the seal fin has a plate shape, and has a triangular or quadrangular cross section and a pointed tip. The steam turbine seal device according to claim 1, wherein the seal fin has a thickness of 100 μm to 2 mm. The height of the seal fin is 100 μm to 10 mm.
The steam turbine seal device according to claim 7. The steam turbine seal device according to any one of claims 1 to 8, wherein the seal fin has an interval between adjacent seal fins of 0.5 mm to 50 mm. The steam turbine seal device according to any one of claims 1 to 9, wherein the steam turbine seal device is applied to any one of an outer ring seal and an inner ring seal of a stationary blade of a high pressure part, an intermediate pressure part, and a low pressure part of the steam turbine. The steam turbine seal device according to any one of claims 1 to 9, wherein the steam turbine seal device is applied to any one of an outer ring seal and an inner ring seal of a moving blade of a high pressure portion, an intermediate pressure portion, and a low pressure portion of the steam turbine.

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