JPH05195714A - Method and device for monitoring vibration of y-globe valve - Google Patents

Abstract

PURPOSE:To monitor deterioration of a Y-globe valve caused by vibration of a disc such as fatigue of the valve stem and the wear of the disc and guide ribs by installing vibration sensors on the outer surface of the valve body. CONSTITUTION:At least two vibration sensors 10, 11 are installed on the outer surface of a valve body 2, and the vibratory mode of a disc 1 (whether it vibrates rectangularly to or parallel with steam flow 4, or vibrates while rotating, etc.) is anticipated from dislocation of the time between the effective value peaks of two sensing signals given b them 10, 11. From the effective values determined during the plant in operation, fatigue of valve stem and the wear amounts of the disc and guide ribs are determined on the basis of the predetermined relationship between the valve stem fatigue and sensing value and/or the predetermined relationship between the wear amounts of disc 1 and guide ribs 6, 7 and the corresponding sensing values, and if the allowable value is exceeded, an alarm is issued.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided in a main steam passage of a thermal power plant, a nuclear power plant, etc., and a valve element obliquely moves back and forth with respect to the main steam passage to shut off the main steam passage. The present invention relates to a Y-shaped lens valve, and particularly to a vibration monitoring method and apparatus suitable for detecting vibration and wear of a disk of the Y-shaped valve.

[0002]

2. Description of the Related Art A main steam isolation valve for steam shutoff, which is one of Y-shaped ball valves used in, for example, a nuclear power plant, causes high temperature steam generated in a nuclear reactor to be introduced into a power generation turbine to cause a plant abnormality. It shuts off at times. The structure of a commonly used air-driven main steam isolation valve is shown in Fig. 4 (a). In FIG. 4 (a), the valve body 2 is formed with a fluid passage 9 that allows high-temperature steam to flow almost linearly. The disc passage 8 forming an angle of 45 ° with the fluid passage 9 extends to a position where the lower end of the disc passage 8 blocks the fluid passage 9, and the disc 1 moving forward and backward in the disc passage 8 opens and shuts the fluid passage 9. On the upper portion of the disc passage 8, a valve lid 5 that seals the upper portion of the disc passage 8 is fixed to the valve body 2 by bolts. The steam flow 4 is leftward in FIG. 4 (a), and is usually 40 to 50 per second.
Main steam with a flow velocity of m is flowing. The direction of gravity is shown in Fig. 4.
Downwards. Even in the fully open position, the disk 1 projects about halfway into the fluid passage 9, and the high-speed steam impinges on the disk 1, which may cause vibration and wear of the disk 1.

FIG. 4 (b) is a view of the main steam isolation valve shown in FIG. 4 (a).
It is a figure which shows the AA sectional view in. An upper guide rib 6 and a lower guide rib 7 are formed on the inner surface of the valve body 2 where the disc 1 advances and retracts to guide the disc 1.

In general, as a device for detecting a valve abnormality, a vibration detector is installed in a servo valve to detect the deterioration state of the valve (for example, Japanese Patent Laid-Open No. 61-231420).
There is also a steam turbine control valve in which a distance detector is installed in the valve and the wear amount is detected from the difference from the reference distance (for example, Japanese Patent Laid-Open No. 03-15606).

[0005]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the Y-shaped valve, since the disc 1 that shuts off the fluid passage protrudes into the fluid passage and is exposed to the fluid even when the valve is fully opened, the fluid force acts on the disc 1. To work. Due to the fluctuation of the fluid force, the disc 1 vibrates, and the disc 1 and the guide ribs 6 and 7 may be worn due to fatigue of the valve rod 3 and sliding with the guide ribs 6 and 7. If a vibration detector or a distance detector is provided in the valve in order to detect the vibration of the disk 1 in a high temperature and high pressure environment such as a nuclear power plant, fluid may leak from the signal extraction part of the detector, It reduces reliability.

A first object of the present invention is to provide a vibration monitoring method for a Y-shaped lens valve and its apparatus for detecting the vibration and wear portion of a disk without lowering the reliability such as fluid leakage. is there.

A second object of the present invention is to make it possible to estimate the deterioration state of the valve, set an appropriate repair time such as disassembly / inspection, rationalize the inspection, and predict a failure in advance. It is an object of the present invention to provide a method and an apparatus for monitoring the vibration of a Y-shaped lens valve having high performance.

[0008]

The first object of the present invention is to vibrate (sound) generated when a disk and a guide rib collide with each other, for example, in the vicinity of the guide rib on the outer surface of the valve body, and friction between the disk and the guide rib. A plurality of vibration detectors that detect vibrations (sounds) that occur occasionally are provided, and the disc vibration mode is determined from the peak time difference of the effective value of the vibration detection signal detected by these detectors at the time of collision or wear. In other words, it is achieved by specifying the friction point.

The second object is to predict the fatigue of the valve rod during plant operation from the relationship between the stress acting on the valve rod at the time of disk vibration and the effective value of the detection signal, which is obtained in advance, and
Predict the amount of wear of the disks and guide ribs during plant operation from the relationship between the amount of wear of the disks and guide ribs that was obtained in advance and the effective value of the detection signal, and calculate the fatigue and wear amount of these accumulated values using the preset allowable values. This is achieved by outputting an alarm when exceeding.

[0010]

In the present invention, a plurality of vibration detectors are provided in the vicinity of the guide ribs on the outer surface of the valve body, and the vibration mode of the disk is specified from the time difference between the peaks of the effective value of this signal to determine the magnitude of the effective value. From this, the fatigue of the valve stem and the amount of wear of the guide ribs and discs are predicted. As a result, breakage of the valve stem, guide ribs,
It is possible to predict in advance defects such as abnormal wear of the disk and set an appropriate repair time.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 2 is a diagram showing the installation position of the vibration detector of the vibration monitoring device according to the embodiment of the present invention. The present embodiment shows the installation position of the vibration detector when applied to the main steam isolation valve of a nuclear power plant. The structure of the main steam isolation valve is the same as that of FIG. 4, the same members are designated by the same reference numerals, and the description of the overlapping portions will be omitted. A vibration detector 10 is installed near the lower guide rib 7 on the outer surface of the valve body 2, and a vibration detector 11 is installed near the upper guide rib 6.

FIG. 1 is a block diagram of a vibration monitoring apparatus according to an embodiment of the present invention. The respective detection signals of the vibration detectors 10 and 11 are amplified by the amplifiers 12a and 12b, respectively, and then only the frequency band of interest is extracted. That is, only the vibration component generated when the disc 1 and the guide ribs 6 and 7 collide and the vibration component generated when the disc 1 and the guide ribs 6 and 7 rub are taken out by the bandpass filters 13a and 13b. Next, it is converted into an effective value (square root of the root mean square value) through the effective value converters 14a and 14b.

Differences in effective value depending on the vibration mode of the disk 1 are shown in FIGS. FIG. 5 shows the disk 1 in FIG.
6 is a graph showing an effective value when the vibration vibrates in the same direction as the steam flow 4. At this time, the disk 1 collides with the upper guide rib 6 and the lower guide rib 7 alternately, so that the effective value 2 of the vibration detector 10 installed near the lower guide rib 7
A periodic peak 22 appears at 0. Similarly, a periodic peak 22 appears in the effective value 21 of the vibration detector 11 installed near the upper guide rib 6. This effective value of 20
The peak and the peak of the effective value 21 have a time shift of about 1/2 of the vibration period of the disk 1. The peak 23 having a small effective value 20 is for detecting the vibration component generated when the upper guide rib 6 and the disk 1 collide, and is transmitted through the valve body 2, so that the output is attenuated and the effective value 21 There is a time lag compared to the peak 22. The collision point can be estimated from this time delay.

Next, FIG. 6 shows effective values when the disk 1 vibrates in the direction perpendicular to the steam flow 4. In this case, the disc 1 collides with the two upper guide ribs 6 alternately. Therefore, the peak 22 appears only in the effective value 21 of the vibration detector 11 installed near the upper guide rib 6, and the effective value 20 of the vibration detector 10 installed near the lower guide rib 7
Shows only a small peak 23 due to the transmission of this collision. The peak 23 having a small effective value 21 is provided on the upper guide rib 6 and the disc 1 on the side where the vibration detector is not installed.
The vibration component at the time of collision with is transmitted through the valve body 2.

FIG. 7 shows the effective value when the vibration of the disk 1 is a composite in the direction perpendicular to the flow direction of the steam, that is, when the disk 1 oscillates elliptically. In this case, disk 1
Is one lower guide rib 7 and two upper guide ribs 6.
Clash in turn. Therefore, the time difference between the peaks of the effective value 20 and the effective value 21 is about 1/3 of the vibration period of the disk 1.
Or 2/3. As described above, the time lag at which the two effective values show peaks differs depending on the vibration mode of the disk. Therefore, in this embodiment, as shown in FIG. 1, after the two effective values are converted by the A / D converters 16a and 16b, the signal comparison / calculation unit 17 obtains the time difference between the two effective values being a peak. The disk vibration mode is specified, and the number of vibrations is counted.

Next, in the wear / fatigue predicting calculation unit 18 having as a database the relationship between the stress acting on the valve stem at the time of disk vibration and the effective value which has been obtained in advance, the valve stem during plant operation is selected. Find the stress that acts. Fatigue of the valve rod is determined from the stress and the number of vibrations based on the S-N curve of the valve rod material (a curve showing the relationship between the stress repeatedly applied and the number of repetitions until failure). Further, in the wear / fatigue prediction calculation unit 18 having the previously obtained relationship between the wear amount of the disc or the guide rib and the effective value as a data base, the wear amount in one vibration is calculated, and this is calculated as the number of vibrations. The total amount of wear of the disks and guide ribs during plant operation is calculated by integrating over.

If the fatigue of the valve stem or the total amount of wear of the disc and the guide ribs obtained by the wear / fatigue prediction calculation unit 18 exceeds a preset allowable value, an alarm device 19
By outputting an alarm from the valve, it is possible to predict the malfunction of the valve in advance, set the appropriate repair time such as disassembly and inspection, rationalize the regular inspection, etc. It can prevent transient changes. In this embodiment, the vibration mode of the disk was obtained using the two vibration detectors 10 and 11. However, if a vibration detector is provided near each guide rib (in the case of the embodiment of FIG. 2, three vibration detectors are used). A vibration detector will be provided.), So that the vibration mode of the disk can be predicted with higher accuracy.

FIG. 3 is a block diagram of a vibration monitoring apparatus according to another embodiment of the present invention. In addition to the configuration of the vibration monitoring device shown in FIG. 1, an abnormal vibration determination unit 24 that compares the magnitude of the effective value after A / D conversion with a preset value is provided, and when the set value is exceeded, an alarm 27 Therefore, an alarm is output. According to this embodiment, in addition to the deterioration of the valve over time such as fatigue of the valve rod and wear of the guide ribs and the disc, abnormal vibration caused by falling of parts, eccentricity of the disc, and the like can be quickly detected.

[0019]

According to the present invention, it is possible to detect the deterioration state of the Y-shaped lens valve with time, to set the appropriate repair time such as disassembly and inspection, to rationalize the inspection, and to prevent the valve from malfunctioning. This has the effect of preventing the resulting transient change in the plant.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a vibration monitoring device according to a first embodiment of the present invention.

FIG. 2 is a layout view of a vibration detector in the vibration monitoring device according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a vibration monitoring device according to a second embodiment of the present invention.

FIG. 4 is a structural diagram of a main steam isolation valve.

FIG. 5 is a graph showing effective values when a disk vibrates in the same direction as the flow of steam.

FIG. 6 is a graph showing effective values when a disk vibrates in a direction perpendicular to the flow of steam.

FIG. 7 is a graph showing an effective value when a disk is elliptically vibrated.

[Explanation of symbols]

1 ... Disc, 2 ... Valve main body, 3 ... Valve rod, 4 ... Steam flow, 5 ... Valve lid, 6 ... Upper guide rib, 7 ... Lower guide rib, 8 ... Disk passage, 9 ... Fluid passage, 10 ... Vibration detector , 11 ... Vibration detector, 12a, 12b ... Amplifier, 13
a, 13b ... band pass filter, 15a, 15b ... RMS converter, 16a, 16b ... A / D converter, 17 ... 2
Signal comparison / calculation unit 18, wear / fatigue prediction calculation unit 19,
27 ... Alarm device, 20 ... Effective value of vibration detector provided near the lower guide rib, 21 ... Effective value of vibration detector provided near upper guide rib, 22 ... Peak of effective value, 23 ... Other guide ribs Transmission of the generated effective value peak, 24 ... Abnormal vibration determination unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Kawamura 1168 Moriyama-cho, Hitachi-shi, Ibaraki Hiritsu Seisakusho Co., Ltd. Energy Research Institute (72) Iwa Yokoyama 1168 Moriyama-cho, Hitachi-shi, Ibaraki Nitate Seisakusho Co., Ltd. Energy Research Institute

Claims (5)

[Claims] 1. A body having a fluid passage formed therein, a disc provided in the body for advancing and retreating obliquely with respect to the fluid passage to block and open the fluid passage, and the disc integrally formed with the body. At least two vibrations are formed on the outer surface of the main body in a Y-shaped lens-shaped valve including a disc passage that advances and retreats, a drive device that drives the disc, and a guide plate for the disc that is formed in the disc advancing and retracting portion of the body. A detector is provided, a judging means for judging the vibration of the disk from the outputs of both detectors, a means for predicting the fatigue of the valve rod transmitting the driving force to the disk from the vibration judgment result, and a judgment means for the disk or the disk. It is characterized by comprising means for predicting wear of the guide plate, and comparison calculation means for judging abnormal fatigue of the valve rod and abnormal wear of the disc or the guide plate of the disc. A Y-shaped ball valve vibration monitoring device. 2. A device for monitoring vibration of a Y-shaped target valve, which is provided in a main steam flow path of a power generation plant and shuts off the main steam flow path when an abnormality occurs in the power generation plant, comprising: At least two vibration detectors are provided on the outside of the main body, and a vibration occurrence point in the Y-shaped lens-shaped valve is obtained from the difference between the respective vibration detection signals of both vibration detectors. .. 3. A device for monitoring the vibration of a Y-shaped target valve, which is provided in the main steam flow path of a power generation plant and shuts off the main steam flow path when an abnormality occurs in the power generation plant, comprising: At least two vibration detectors provided outside the main body,
A Y-type lens-shaped valve vibration monitoring device, further comprising: means for determining a vibration occurrence point in the Y-shaped lens-shaped valve from a difference between respective vibration detection signals of both vibration detectors. 4. A device for monitoring vibration of a Y-shaped target valve, which is provided in a main steam flow path of a power generation plant and shuts off the main steam flow path when an abnormality occurs in the power generation plant, comprising: At least two vibration detectors are provided on the outside of the main body, and the vibration occurrence point in the Y-shaped lens valve is obtained from the difference between the vibration detection signals of both vibration detectors, and the valve rod at the time of disc vibration that was previously obtained Predict valve rod fatigue during plant operation from the relationship between the stress acting and the effective value of the detected signal, and
Predict the amount of wear of the disks and guide ribs during plant operation from the relationship between the amount of wear of the disks and guide ribs that was obtained in advance and the effective value of the detection signal, and calculate the fatigue and wear amount of these accumulated values using the preset allowable values. A vibration monitoring method for a Y-shaped lens valve, which is characterized in that an alarm is output when it exceeds. 5. An apparatus for monitoring the vibration of a Y-shaped target valve, which is provided in a main steam flow path of a power generation plant and shuts off the main steam flow path when an abnormality occurs in the power generation plant, comprising: At least two vibration detectors provided outside the main body,
From the difference between the respective vibration detection signals of both vibration detectors, the means for obtaining the vibration occurrence point in the Y-shaped lens valve, and the relationship between the stress acting on the valve rod and the effective value of the detection signal at the time of disk vibration that have been obtained in advance. A means for predicting the fatigue of the valve rod during plant operation, and a means for predicting the wear amount of the disk or guide rib during plant operation from the relationship between the effective value of the wear amount and the detection signal of the disk or guide rib that was previously obtained, A vibration monitoring device for a Y-shaped lens valve, comprising means for outputting an alarm when the integrated value of these fatigue and wear amounts exceeds a preset allowable value.