JPH0315606A - Abnormal abrasion detector for steam turbine control valve - Google Patents

Abstract

PURPOSE:To rationalize repairs by obtaining a difference between a reference distance and a detected distance of the sliding portion of a steam turbine control valve, determining abnormal abrasion on the basis of comparison of the difference and a preset distance, and recording distance comparison information at predetermined timing intervals to predict an abnormal timing. CONSTITUTION:A signal output from a distance detector 21 for detecting a distance between the lever support of a steam turbine control valve and a cross head is amplified by an amplifier 22 so as to be input into a recorder 23 and an A/D converter 24, whereby distance detection information is displayed by the recorder 23. Meanwhile, the distance detection information converted into a digital signal by the A/D converter 24 is sent to a comparative calculator 25 to be compared with preset distance information, thus obtaining a difference (displacement) therebetween. In case of the displacement larger than an allowable set value, abnormal abrasion is determined so that an alarm 26 is operated. In addition, the displacement is input into a predictable calculator 27 every predetermined period, wherein a past tendency of an increase in displacement is obtained so that a future increase is predicted to be recorded in another recorder 28.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a hole wear detection device for a steam turbine control valve that controls the main steam flow rate in a steam turbine.

(Conventional technology) Conventionally, steam turbines used in steam power plants, etc.
A predetermined rotational torque is generated according to the demand, that is, the load, and this 2U is achieved by adjusting the flow rate of steam and air flowing into the turbine. This is done using a valve.

From the viewpoints of increasing the capacity of a steam turbine, improving efficiency, etc., the conditions for steam flowing into the turbine are becoming increasingly high temperature and high pressure.

On the other hand, in recent years, due to changes in the industrial structure, the difference in electricity demand between day and night and between seasons has been widening, and this trend is expected to continue.

Under these circumstances, as nuclear power generation capacity increases, making it difficult to make large-scale load adjustments, thermal power generation is also playing a role as a 2L load adjustment unit to support nuclear power generation in order to respond to changes in electricity demand. ing.

The steam control valve of the steam turbine in such thermal power generation is required to control the flow rate of steam at high temperature and high pressure.
The operating conditions are more severe than those of other turbine equipment, and mechanical stress is added, such as vibrations generated when the valve is throttled and wear of sliding parts due to opening and closing of the valve.

Figure 3 shows an example of the structure of a conventional steam control valve.
A valve 2 is housed above. Further, a guide sleeve 3, a stand 4, and a lever support 5 are provided on the valve seat 1, and the valve stem 6 supporting the valve 2 is attached to the guide sleeve 3.
, inserted into the stand 4. Valve stem pushers 7 and 8 for guiding the valve stem 6 are provided between the valve stem 6 and the inner wall of the stand 4. The upper part of the valve stem 6 is connected to the crosshead 9 by a screw, and these have an integral structure.

The center part of this crosshead 9 is connected to a lower horizontal lever 10 with a pin 11, and one end of this lower horizontal lever 10 is connected to a push rod 12 from a Ura tube (not shown). The vertical movement of the rod 12 causes the crosshead 9 to rotate around the pin 11. The valve 2 is opened and closed by the rotation of the crosshead 9, and the amount of steam flowing into the turbine is adjusted.

Further, a spring box 13 is provided above the lever support 5, and a spring mechanism 14 for pressing the valve stem 6 is accommodated within the spring box 13.

An upper horizontal lever 15 is rotatably attached to the upper part of the spring box 13, and one end of the upper horizontal lever 15 and one end of the lower horizontal lever 10 are connected by a fulcrum 16 to form a link mechanism. There is.

In such a structure, due to load fluctuations and frequency fluctuations,
Wear of sliding parts such as the valve stem 6 and pushers 7 and 8, and the crosshead 9 and its guide bush 17 is accelerated. especially,
In the negative G1 adjustment unit as described above, excessive wear of the sliding portion may occur in a short period of time. In addition, due to such excessive wear, vibrations are likely to occur in the valve stem 6, and when the gaps between the sliding parts become large due to excessive wear,
The displacement of the valve stem 6 in the lateral direction tends to increase, and the bending stress of the threaded portion that fixes the valve stem 6 also tends to increase.

There have also been reports of accidents due to breakage of the threaded part of the valve stem due to this phenomenon.

Factors that affect this bending stress on the valve stem thread include the gap A between the valve stem 6 and the inner circumference of the upper part of the stand 4, the gap B between the crosshead 9 and the guide bush 17, and the gap C below the valve stem screw. As these gaps become larger, the bending stress in the threaded portion of the valve head becomes larger.

(The problem to be solved by the invention WrJ) In this way, since the steam control valve has to adjust the load: I3, the frequency of repeating the opening and closing of the valve increases, causing wear on the valve stem sliding part and the crosshead guide sliding part. As the gap between these sliding parts increases, the bending displacement of the valve stem becomes excessive, and excessive bending stress is generated in the threaded part of the valve stem. Further, as the gap becomes larger, vibration of the valve stem is promoted, and a large fluctuating stress acts on the threaded portion of the valve stem, which may lead to breakage of the valve stem. Therefore, it is necessary to perform inspection and maintenance work in detail, which causes a reduction in the operating rate of the unit.

The present invention was made in view of the above-mentioned conventional circumstances, and even during operation of a steam turbine plant, the lateral displacement of the part that most affects the threaded part of the valve stem is monitored, and the present invention is used to detect excessive displacement. To provide a true wear detection device for a steam turbine control valve, which makes it possible to perform preventive maintenance by detecting a point in time or a tendency of increase in displacement amount and setting appropriate timing for disassembly, inspection, and repair. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) An abnormal wear detection device for a steam turbine control valve of the present invention is a device for detecting abnormal wear in a gap in a sliding portion of a steam turbine control valve. A distance M detector detects the distance between the gaps between the parts, the difference between the detected distance information and the preset reference distance information is calculated, and the difference between the two distance information is compared with the preset setting distance information. and a comparison calculation means for determining abnormal wear from the comparison results, and recording distance comparison information obtained by the comparison calculation means at predetermined time intervals, and predicting the period of normal wear based on the recorded results. The present invention is characterized in that it includes a prediction calculation means that performs the following operations.

(Function) The present invention measures the gap between the lower part of the crosshead and the lever support as the lateral displacement of the sliding part of the steam turbine control valve, for example, the crosshead, monitors the amount of change in this gap value, and measures the displacement. If the amount exceeds the clearance control value, an alarm is issued, or the progress of fluctuations in the clearance value is recorded and the timing of abnormal wear is predicted from the recorded results, so that the threaded portion of the valve stem can be prevented from breaking. Appropriate maintenance timing can be set with prevention in mind, and repairs such as disassembly and inspection can be streamlined.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Incidentally, the same parts as in FIG. 3 are given the same reference numerals, and the explanation of the overlapping parts will be omitted.

FIG. 1 is a diagram showing the structure of a steam turbine control valve to which an embodiment is applied. The lower part of the lever support 5 that guides the upper part of the crosshead 9 has an inner part that penetrates this lever support 5 in the radial direction. A through hole communicating with the circumferential surface is bored. In the outer circumferential direction of this through hole, there is an abnormal wear detection mechanism that detects the distance Ate from the through hole to the cross head 9, and detects wear on the inner wall surface of the lever support 5 and the surface of the cross head 9 from this detected value. A detector 21 is provided.

FIG. 2 is a diagram showing the configuration of this abnormal wear detection mechanism, in which the distance value detected by the distance detector 21 to the crosshead 9 is subjected to an earth-width correction by the amplifier 22, and then sent to the recorder 23 and the A/ The signals are output to the D converter 24, respectively. The distance detection information manually entered into the recorder 23 is displayed here, while the distance detection information manually entered into the A/D converter 24 [output information is converted into a digital signal here and outputted to the comparison calculation section 25]. ．． Ru.

In this comparison calculator 25, the input distance i! i Compare the detection information and preset set distance information, for example, the distance in a stationary state, find the difference between the distance detection information and the set distance information, that is, the amount of displacement, and calculate the amount of displacement as a preset allowable setting value. If the fluctuation is larger than the lever support 5.
It is determined that the inner wall surface of the crosshead 9 and the surface of the crosshead 9 are abnormally worn due to sliding, and an abnormality signal is output. Then, this abnormality signal is output to the alarm device 26 and an alarm is issued. Further, the distance displacement amount calculated by the comparison calculator 25 is outputted to the 17113 calculation unit 27 at predetermined time intervals,
Here, the increasing tendency of the excessive displacement amount is determined, and based on this increasing tendency, the future increasing amount is predicted as a-1, and preliminary i1F1 information is outputted to the recorder 28. Using the predictive information recorded in the recorder 28, operators can predict when future abnormalities will occur and the timing of maintenance inspections, and take appropriate maintenance measures to prevent breakage of the threaded part of the valve stem. You can set the period,
It becomes possible to streamline repairs such as disassembly and inspection.

By the way, in the above-mentioned embodiment, the present invention was explained with reference to an example of detecting an abnormality in the sliding part between the inner wall surface of the lever support 5 and the surface of the crosshead 9. It can also be applied to abnormality detection between 7 and 8.

[Effects of the Invention] As explained above, according to the abnormal wear detector for a steam turbine control valve of the present invention, the amount of displacement of sliding parts such as the lower part of the crosshead and the predicted value of future displacement can be detected during operation. By detecting this, it is possible to set an appropriate maintenance period while taking into account the prevention of breakage of the threaded part of the valve stem, and it is possible to streamline repairs such as disassembly and inspection.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional view of a steam control valve to which a hole normal wear detector for a steam turbine control valve according to an embodiment of the present invention is applied, and FIG. 2 is a partial sectional view of a steam turbine control valve abnormal wear detector according to an embodiment of the present invention. FIG. 3 is a sectional view showing an example of a steam control valve. 2... Valve 5... Lever support 6... Valve stem 21... Distance detector 22. ......Amplifier 23......Recorder 24...A/D converter 25...Comparison calculator 26 ......Alarm device 27...Prediction calculation section 28...Recorder

Claims (1)

[Claims] A device for detecting abnormal wear in a gap between a sliding part of a steam turbine control valve, comprising: a distance detector that detects a distance between the gap in the sliding part; a comparison calculation means for calculating the difference between the distance information and the reference distance information obtained by the comparison calculation means, and comparing the difference between the two distance information with preset setting distance information and determining abnormal wear from the comparison result; What is claimed is: 1. An abnormal wear detection device for a steam turbine control valve, comprising: a predictive calculation means for recording distance comparison information at predetermined time intervals and predicting the timing of abnormal wear based on the recorded results.