JPH11236801A - Turbine rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a turbine rotor which can monitor the crack initiating and propagating situation even under the service and can prevent cracking and make appropriate care certainly before the situation leads to a significant damage. SOLUTION: A turbine rotor is structured so that turbine blades 5 are implanted in a blade implanting part 2 of a rotor wheel 1, wherein a strain gauge 3 is affixed to the top of a first hook 2a in the blade implanting part. The configuration includes a telemeter installed in a coupling part for receiving the sensing signal detected by the strain gauge 3 and transmitting the signal and a signal receiving antenna for receiving the signal transmitted from the telemeter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbine rotor, and more particularly to a turbine rotor capable of detecting the occurrence and progress of corrosion and fatigue cracks in a low-pressure rotor of a steam turbine.

[0002]

2. Description of the Related Art In a part of a low-pressure section of a steam turbine, there is a so-called dry-wet alternating area as an environmental condition during operation such that a steam state becomes a wet state at a high load and a dry state at a low load. At a site under such environmental conditions, a small amount of corrosive components present in the steam is precipitated by the start / stop or load change, and the precipitated corrosive components accumulate after many years of operation. By locally depositing and accumulating a high concentration of corrosive components, corrosion (pitting corrosion) occurs over time, and further corrosion (pitting corrosion) proceeds to reduce the fatigue strength of the material.

As described above, in a steam turbine low-pressure rotor that has been operated for a long period of time, a corrosive environment is formed over a long period of time in a dry-wet alternating region, so that pitting is likely to occur starting from nonmetallic inclusions. Often grow and undergo corrosion fatigue damage originating from pitting corrosion due to the effects of centrifugal stress and vibrational stress.

[0004] Corrosion fatigue damage appears as a phenomenon in which cracks occur due to pitting of the first hook of the rotor-side blade implantation portion as shown in FIG. 9 or FIG.

In a conventional turbine rotor, blades are extracted from the rotor during a periodic inspection, and cracks caused by corrosion fatigue damage are detected by a nondestructive inspection method, for example, a magnetic particle flaw detection method.

Further, cracks have been detected by ultrasonic flaw detection without removing the blades.

[0007]

The conventional turbine rotor has a problem in that it must be inspected for cracks during periodic inspections, and cracks cannot be detected during operation. there were.

[0008] In the case of the magnetic particle flaw detection method which is a non-destructive inspection method, there is a problem that the blades must be extracted, and when the blades are implanted again, the shoulder must be slapped.

As a method for inspecting without removing the blade, an ultrasonic flaw detection method is used. However, the shape of the rotor-side blade implantation portion is complicated, and the inspection is performed in a state where the blade is implanted. However, there is a problem that it is difficult to perform accurate detection with ease.

[0010] Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art, and to monitor the progress of crack initiation even during movable operation, so that the crack can be removed before serious damage is caused. An object of the present invention is to provide a turbine rotor capable of reliably performing preventive maintenance.

[0011]

In order to achieve the above object, a turbine rotor according to the present invention is a turbine rotor in which turbine blades are implanted in a blade implant portion of a rotor wheel, wherein the blade implant portion is provided. Wherein a strain gauge is disposed on the top of the first hook, which is the outermost part of the first hook.

Here, the turbine blades are grouped by a shroud, and the strain gauge is disposed at the position between the groups.

Further, the strain gauge is a welded capsule strain gauge.

A stop blade for fixing the turbine blade to the blade implant portion is provided adjacent to the turbine blade, and a lead hole for passing a lead wire of the strain gauge is provided. It is characterized in that it is formed on the retaining blade.

Further, a lead wire hole for passing a lead wire of the strain gauge is formed in the rotor wheel so as to penetrate in a radial direction and open to a rotor center hole.

Further, a lead hole for passing the lead wire of the strain gauge is formed in the coupling portion so as to penetrate in the radial direction and open to the center hole of the rotor. Is wired so as to pass through a lead wire hole formed in the rotor wheel, then pass through the rotor center hole, and then pass through a lead wire hole formed in the coupling portion.

A telemeter connected to a lead wire of the strain gauge, the telemeter being provided in a coupling unit for receiving and transmitting a detection signal detected by the strain gauge; and transmitting the detection signal transmitted by the telemeter. And a receiving antenna disposed at a stationary part near the telemeter for receiving.

Also, a slip ring connected to a lead wire of the strain gauge and capable of receiving a detection signal of the strain gauge and transmitting the received detection signal to a stationary portion is arranged near the coupling portion. Features.

In the above-described invention, since the strain gauge is provided on the first hook where cracks are most likely to occur, it is possible to monitor the progress of crack generation and to prevent corrosion during operation of the turbine rotor. Fatigue cracks can be detected, and even if cracks are not found during periodic inspection, cracks that have developed and propagated during operation can be detected.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1 or FIG. 2, in a low-pressure rotor in a low-pressure stage of a steam turbine, a blade implant portion 2 for implanting a turbine blade 5 is formed at a circumferential end of a rotor wheel 1. I have. The blade implant portion 2 includes an outermost first hook 2a, an intermediate second hook 2b,
And the innermost third hook 2c. FIG.
As shown in (1), the turbine blade 5 is fitted into the uneven portion formed by the first hook 2a, the second hook 2b, and the third hook 2c.

As shown in FIG. 1, the strain gauge 3 has a resistance wire type strain gauge 3 attached to the surface of the top of the first hook 2a which is susceptible to corrosion fatigue. On the top surface of the first hook 2a, a lead wire 4 for transmitting a detection signal of the strain gauge 3 to a predetermined location is attached.

FIG. 9 shows a crack generated in the acasill direction (rotor axial direction) on the steam inlet side of the first hook 2a. FIG. 10A is a cross-sectional view corresponding to FIG. 9 and showing a position of a crack generated in the first hook 2a, and FIG. 10B is a diagram showing a pit which is a crack starting point and a progress from the pit. FIG. 3 is a diagram showing the progress of cracks. As shown in FIGS. 10A and 10B,
The starting point (hole point) of the crack is determined by the first hook 2a in the first hook 2a where the turbine blade 5 and the blade implant 2 mesh.
In the vicinity of the meshing portion a, a crack is generated and propagates in the acasill direction (rotor axial direction) so as to pass through the first hook 2a.

Therefore, in order to detect a crack in the first hook 2a in the acasill direction (axial direction), as shown in FIG. 1, the strain gauge 3 is moved in the circumferential direction on the top surface of the first hook 2a. Affixed. By attaching the strain gauge 3 in the circumferential direction so as to be in a direction perpendicular to the crack, a change in strain due to the opening of the crack can be detected.

As shown in FIG. 2, the first hook 2a
A gap 2d is formed between the surface of the turbine blade 5 and the back surface of the turbine blade 5 located on this surface.
The first hook 2a is disposed on the top surface of the first hook 2a so as to straddle the gap 2d.

As shown in FIG. 4, the tip portions of the plurality of turbine blades 5 implanted in the blade implant portion 2 are connected to each other by a predetermined number of shrouds 8 to form a group. I have. At the inter-group position between the groups formed by the shroud 8, the corrosive components having a high concentration locally precipitate and accumulate, and as a result, they corrode over time as shown in FIG. (Pitting corrosion) occurs and it is easy to progress,
Therefore, the probability of occurrence of cracks increases. Therefore, strain gauge 3
Is selected as a position between the groups formed by the shroud 8.

Although the turbine rotor is in the low pressure stage, it is in a temperature environment of about 80 ° C. to about 130 ° C. and becomes wet steam, so that the resistance wire type strain gauge 3 can withstand high temperatures and is subjected to severe conditions. It is preferred to use a welded capsule strain gauge that can be used below. FIG. 5 shows a specific configuration of the capsule type strain gauge.

As shown in FIG. 5, the capsule type strain gauge 3
1 is in a stainless steel gauge tube 32,
For example, an active wire 33 that changes resistance by a strain made of a Pt-W wire and a dummy wire 34 that is made of, for example, a Pt-W wire for lowering the zero point due to a temperature change are mutually connected. It is configured by wiring with a gap and filling with inorganic insulating powder 35 made of MgO. A base flange 36 that protrudes outward is integrally fixed to the bottom surface of the gauge tube 32, and the capsule-type strain gauge 31 is fixed to the measured object 37 by spot welding so that the capsule-type strain gauge 31 is fixed to the measured object 37. It is configured to be fixed to.

FIG. 6 is a diagram showing a method of fixing the lead wire 4. The lead wire 4 is formed of a heat-resistant inner wire, and is circumferentially arranged on the surface of the top of the first hook 2a. As shown in FIG.
1 is put on the lead wire 4, and the stainless steel foil 41 is spot-welded 42 to the structure 43 along the laying direction of the lead wire 4.
Is done. The stainless steel foil 41 does not need to be continuously covered over the entire lead wire 4, but is covered over the lead wire 4 at an appropriate interval.

Next, a method of laying the lead wire 4 will be described with reference to FIG. As shown in FIG. 3, a stop blade 6 for fixing the turbine blade 5 to the blade implant 2 is provided adjacent to the turbine blade 5. The stop feather 6
A lead wire hole 7 for passing the lead wire 4 is formed so as to penetrate the surface of the first hook 2a. The lead wire 4 is provided along the surface of the first hook 2 a from the strain gauge 3, reaches the retaining blade 6, passes through the gap between the first hook 2 a and the retaining blade 6, and from below the lead wire hole 7. , And is guided to a predetermined location along the side of the stop blade 6.

Next, with reference to FIG. 7 or FIG. 8, how the strain gauge 3 and the lead wire 4 are arranged in the entire turbine rotor will be described.
A method of transmitting a detection signal will be described.

The target paragraph in the turbine rotor where it is necessary to attach the strain gauge 3 in order to detect the distortion is a low-pressure paragraph, among which the paragraph is susceptible to corrosion fatigue. Therefore, the paragraph to which the strain gauge 3 is attached is a dry-wet alternation area in which the steam condition is a salt zone, and for example, as shown in FIG. 7, L-1 paragraph (low pressure first paragraph) 51 and L
-The second paragraph (low-pressure second paragraph) 52.

As shown in FIG. 7, L-1 paragraph 51 and L-
The lead wire 4 is attached to the rotor wheel 1 in the second paragraph 52.
Lead holes 11 and 12 for passing through are formed so as to penetrate in the radial direction and open to the rotor center hole 14. The coupling portion 15 is fixed to a portion of the rotor shaft extending in the axial direction from the L-2 paragraph 52.
A lead wire hole 13 for passing the lead wire 4 is formed in the coupling portion 15 so as to penetrate in the radial direction and open to the rotor center hole 14.

The strain gauges 3 are attached to the first hooks 2a of the L-1 paragraph 51 and the L-2 paragraph 52, and the lead wires 4 are respectively connected to the lead holes 11 and 12 from the strain gauges 3. Through the rotor hole 13 and through the lead hole 13.

The coupling unit 15 is provided with a telemeter 21 for receiving and transmitting a detection signal detected by the strain gauge 3. Further, a bearing cover 17 that forms a stationary portion with respect to the rotating turbine rotor is provided outside the bearing 16 of the rotor shaft. A receiving antenna 22 for receiving the detected signal is attached. The lead wire 4 that has passed through the lead hole 13 is connected to a telemeter 21.

The strain gauge 3, the lead wires 11, 12 and the lead wire 4 passing through the rotor center hole 14 and the lead wire hole 13,
And the telemeter 21 rotate integrally with the rotor wheel 1, while the receiving antenna 22 is stationary. The detection signal representing the strain detected by the strain gauge 3 is the telemeter 2
1 and received by the receiving antenna 22;
Monitoring of data on distortion is continuously performed on a display unit (not shown).

As described above, since the telemeter 21 and the receiving antenna 22 are provided, it is possible to monitor the progress of crack generation even during the movable operation of the turbine rotor, and to prevent cracks from occurring before serious damage. Maintenance can be performed reliably.

FIG. 8 shows the telemeter 21 and the receiving antenna 2.
An embodiment using a slip ring 61 instead of using the slip ring 61 will be described.

As shown in FIG. 8, a slip ring 61 is provided near the coupling portion 15 and outside the rotor shaft. The signal receiving unit 62 is attached to the bearing cover 17 forming the stationary unit. Slip ring 61
Is connected to the lead wire 4 that has passed through the lead wire hole 13 and rotates integrally with the rotor wheel 1. The other end of the slip ring 61 is electrically connected to one end thereof, forms a stationary part, and is connected to the signal receiving part 62 by the lead wire 4a. Since the slip ring 61 is provided, as in the case shown in FIG. 7, even during the movable operation of the turbine rotor, it is possible to monitor the progress of crack generation and preventive maintenance before major damage is caused. Can be performed reliably.

As described above, according to the embodiment of the present invention, in the conventional method, it is necessary to check the state of crack occurrence by nondestructive inspection during the periodic inspection.
Even during operation, it is possible to monitor the progress of crack initiation and preventive maintenance before the steam turbine is seriously damaged.

Further, in the case of nondestructive inspection, crack detection can be performed with high accuracy by magnetic particle inspection, but various operations such as extraction and inspection of the turbine blade 5 and implantation of the turbine blade 5 are required. However, according to the embodiment of the present invention, such a problem can be solved.

In the case of the ultrasonic inspection, it is not necessary to carry out the sampling inspection of the turbine blade 5, but there is a problem in the detection accuracy. However, according to the embodiment of the present invention, such a problem can be solved.

In the above description, a steam turbine is described as an example of a turbine rotor, but the present invention is not limited to this, and the turbine rotor may be a gas turbine.

Also, the strain gauge 3 has been described as being stuck in the circumferential direction of the first hook 2a. However, the strain gauge 3 is not limited to the circumferential direction, and is not limited to the circumferential direction as long as the crack can be easily detected. .

[0045]

As described above, according to the structure of the present invention, it is possible to monitor the progress of crack generation even during the movable operation of the turbine rotor, and to prevent cracks from being damaged before serious damage. Preventive maintenance of cracks can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which a strain gauge for crack detection is attached to a first hook of a blade implantation part.

FIG. 2 is a perspective view showing a state in which turbine blades are implanted in FIG.

FIG. 3 is a perspective view showing a state where a lead wire of a strain gauge is taken out through a retaining blade.

FIG. 4 is a side view showing that the turbine blades are grouped by a shroud.

FIG. 5 is a sectional view showing a capsule-type strain gauge.

FIG. 6 is a view showing a method for fixing a lead wire of a strain gauge.

FIG. 7 is a sectional view for explaining a wiring route of a lead wire and a method of transmitting a detection signal.

FIG. 8 is a cross-sectional view for explaining a wiring route of a lead wire and another method of transmitting a detection signal.

FIG. 9 is a perspective view showing a blade implantation portion showing a crack generated in the acasill direction (rotor axial direction) on the steam inlet side of the first hook.

10 is a sectional view corresponding to FIG. 9, showing a position of a crack generated in the first hook, and a diagram showing a pit which is a crack initiation point and a state of propagation of a crack which propagates from the pit; (B).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotor wheel 2 Blade implantation part 2a 1st hook 2b 2nd hook 2c 3rd hook 2d Clearance 3 Strain gauge 4 Lead wire 5 Turbine blade 6 Stopper blade 7 Lead wire hole 8 Shoroud 11 Lead wire hole 12 Lead wire Hole 13 Lead wire hole 14 Rotor center hole 17 Bearing cover (stationary part) 21 Telemeter 22 Receiving antenna 61 Slip ring

Claims (8)

[Claims] 1. A turbine rotor in which turbine blades are implanted in a blade implant portion of a rotor wheel, wherein a strain gauge is disposed on a top of a first hook which is the outermost of the blade implant portion. Turbine rotor. 2. A turbine rotor according to claim 1, wherein said turbine blades are grouped by a shroud, and said strain gauge is disposed at a position between said groups. 3. The turbine rotor according to claim 1, wherein said strain gauge is a welding-type capsule strain gauge. 4. A stop blade for fixing the turbine blade to the blade implant portion is provided adjacent to the turbine blade, and a lead wire hole for passing a lead wire of the strain gauge is provided. The turbine rotor according to claim 1, wherein the turbine rotor is formed on the stop blade. 5. The rotor wheel according to claim 1, wherein a lead wire hole for passing the lead wire of the strain gauge is formed in the rotor wheel so as to penetrate in a radial direction and open to a rotor center hole. 1 turbine rotor. 6. A lead wire for passing the lead wire of the strain gauge is formed in the coupling portion so as to penetrate in the radial direction and open to the center hole of the rotor. Is wired so as to pass through a lead wire hole formed in the rotor wheel, then pass through the center hole of the rotor, and then pass through a lead wire hole formed in the coupling portion. Item 6. A turbine rotor according to item 5. 7. A telemeter which is connected to a lead wire of the strain gauge and is provided in a coupling unit for receiving and transmitting a detection signal detected by the strain gauge, and transmitting the detection signal transmitted by the telemeter. The turbine rotor according to claim 1, further comprising: a receiving antenna disposed at a stationary part near the telemeter for receiving. 8. A slip ring connected to a lead wire of the strain gauge and receiving a detection signal of the strain gauge and capable of transmitting the received detection signal to a stationary portion is disposed near the coupling portion. The turbine rotor according to claim 1, wherein: