JP2648288B2 - Valve device abnormality detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve device suitable for use in, for example, a plant such as a nuclear power plant that handles high-temperature and high-pressure steam, and more particularly to a sensor for detecting an abnormality such as leakage of fluid inside the valve. The present invention relates to an abnormality detection device provided on a stem of a valve device.

[0002]

2. Description of the Related Art Conventionally, a method of judging an abnormality of a valve is to detect a load acting on the stem by measuring current and voltage values required for driving a stem directly connected to a valve body during a periodic inspection of the valve. By using this load information, it is determined whether there is an abnormality in the valve and whether there is an abnormality in the stem drive unit.

In the case where the valve seat leakage is taken as an example of another abnormality, vibration is detected and it is determined that the leakage is present. However, in the prior art, a vibration sensor is attached to the stem head to interlock with the stem. A method of detecting vibration caused by a fluid flow of a valve body or applying a vibration sensor to an outer wall of a valve box has been adopted.

[0004]

However, in this method, since the distance between the vibration source and the valve seat, which is the vibration source, is considerable, or measurement is performed at a position deviated from the direct vibration source, the vibration is not measured. Not only could it not be detected accurately, but it only provided leak information, which lacked practicability and did not contribute much to the advancement of valve functions.

In addition, since the vibration sensor is not integrally attached to the stem, it is not possible to calibrate the measured value at the same time as the production of the stem. When the vibration is detected, whether the detected value is the vibration from the valve body, It is necessary to give a reference vibration to the valve device when the plant is stopped, etc. when it is necessary to judge whether it is piping vibration or when calibrating the vibration, etc. There were problems such as chipping.

Accordingly, it is possible to detect leakage from the valve seat, process information obtained by the detection, control the valve stem driving device based on the processed information, and treat the leakage with the valve itself. There is a need for an anomaly detection device that allows.

A main object of the present invention is to detect vibration of a valve body caused by leakage when a valve seat leaks when the valve body is fully closed, and drive a stem in a direction to further close the valve body. An object of the present invention is to provide a valve device abnormality detection device that can prevent leakage.

[0008]

In order to achieve the above object, an abnormality detecting device according to the present invention comprises a valve box defining a fluid passage having a valve seat therein, and selectively opening and closing the fluid passage. A valve body having a valve seat movable and selectively engaged with the valve seat in a fluid-tight relationship, and one end integrally coupled to the valve body, A stem extending outside the valve box, and a driving device that engages with a part of the stem outside the valve box to move the valve body, wherein the stem includes the valve body When the valve is in the closed position, a vibration sensor is disposed on a stem portion outside the valve box, and a control device that receives an output signal from the vibration sensor is disposed outside the valve box, When the valve body is in the closed position, the vibration device is controlled by the control device. When the valve detects vibration due to leakage of the valve seat, the valve is further driven from the closed position through the stem in the closing direction until the vibration sensor substantially eliminates vibration detection. Is controlled so as to operate.

In a preferred embodiment, a threaded portion is formed on the outer periphery of a part of the stem with which the driving device is engaged, and an outer peripheral groove is formed near the lower end of the threaded portion. A signal passage extending from the vicinity of the lower end of the threaded portion to the top of the other end of the stem is defined at the center of the stem, and a vibration sensor is fixed to the bottom of the signal passage with an adhesive, and a heat insulating material is used. It is arranged and surrounded. Also,
A connection terminal for the signal line of the vibration sensor is provided on the top of the stem, and the signal line of the vibration sensor is connected to the connection terminal through a signal path.

[0010]

If the valve seat is leaking when the valve body is fully closed, the valve body vibrates due to the leakage flow, and also the stem integrally connected to the valve body. When this vibration is detected by the vibration sensor provided on the stem, the output signal of the vibration sensor is sent to the control device. As a result, based on the command from the control device, the driving device moves the stem in the direction in which the valve element closes. Drive. This stops leakage of the valve seat.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts. FIG. 1 typically shows, in a longitudinal section, an example in which the present invention is applied to a gate valve provided with a stem for vertically moving a valve body against a flow of a fluid. In the figure, 1 is adjacent to each other. A substantially annular valve seat 1a at the end
A valve box having a fluid inlet passage (fluid passage) 1b and an outlet passage (fluid passage) 1c having a flange portion 2b
The valve cover 3, which is connected to the top of the valve box 1 by a suitable fastening means such as a bolt 2a, is selectively interposed between the valve seats formed in the valve box, and has a fluid inlet passage 1b and an outlet passage 1c. The valve body 3 is a known valve body having a valve seat 3a. The region A of FIG. 1 is enlarged and the vibration sensor 6 is provided as shown in FIG.
The lower end of the valve stem 4 provided with is integrally connected by well-known means such as screwing. In the present invention, there is no gap between the stem 4 and the valve body 3 as can be understood from FIG. 2B showing the region B of FIG. Therefore, the description of the sensor itself is omitted.

The stem 4 extends upward through a well-known gland packing 12 disposed in the cylindrical portion 2c of the valve cover 2 and is attached to the top of the valve cover 2 by a bolt and nut assembly 2d. Into the driving device 13,
To be driven up and down. for that reason,
The stem 4 has a screw portion 4a in an upper half thereof, while the driving device 13 has a rotating member (not shown) which engages with the screw portion 4a, and the rotating member is connected to a manual handle 13a or an electric motor. By driving by the motor 13b, the stem 4 can be moved in the vertical direction.

The gland packing 12 is held from above by a packing restraint 12a, and a lower reverse seat 12b is provided.
Has a concave conical surface 12c formed on the lower surface thereof. A convex conical surface 4e having a shape substantially coinciding with the conical surface 12c is formed at a lower portion of the stem 4, and when the stem 4 moves upward when the valve body 3 is fully opened, the conical surface of the reverse seat 12b is formed. 12
c is adapted to receive the conical surface 4e of the stem 4. These conical surfaces 12c and 4e calibrate the inverted seat (back sheet).

The position at which the vibration sensor 6 is attached to the stem 4 is determined by the position of the stem screw portion 4 that moves when the valve is opened and closed.
The vibration sensor 6 is disposed at the lower end of the signal passage 4b extending in the axial direction through the center of the stem 4 and surrounded by the heat insulating material 7 at this position. Are attached thereto by a suitable adhesive 8. Since the vibration sensor 6 is embedded in the inside of the stem, the above-described heat insulation is performed so that the connection between the vibration sensor 6 and the stem 4 is not insufficient and the vibration sensor 6 is protected from a temperature rise of the stem 4. The material 7 and the adhesive 8 are injected from the lateral hole 4d into the signal path 4b when the sensor is mounted. As the adhesive 8, a commercially available adhesive can be used.
Further, the heat insulating material is preferably a non-metallic material having low heat conductivity, such as a material sold under the trade name “PEEK”.

By setting the position of the vibration sensor 6 at the position of the lower end which is displaced from the stem screw portion which moves by opening and closing the valve as described above, the vibration sensor 6 is the same as the known method in which the vibration sensor 6 is provided on the stem head. The sensor can be prevented from being directly exposed to the vibration caused by the movement of the stem.

Since the valve body 3 and the stem 4 exposed to the fluid inside the valve box 1 are integrally and directly connected, the valve seat 3a of the valve body 3 comes into liquid-tight contact with the valve seat 1a of the valve box. When the valve is in a closed state in which the flow is shut off, there is insufficient pressure between the valve seats due to insufficient holding force by the valve stem 4, and valve seat leakage due to insufficient pressure between the valve seats caused by the differential pressure between the fluid inlet passage and the fluid outlet passage. It becomes easy to detect the minute vibration of the valve body 3 caused by the above. Further, a signal representing the vibration is transmitted to the control device 15 of the driving device 13 through the connection terminal 14 provided on the stem head, and the signal is processed by a known method, so that appropriate stem operation can be performed.

Referring again to FIG. 2A, the vibration sensor 6
Must be firmly fixed to the stem 4. When the fluid has a high temperature, an increase in the temperature of the stem 4 that comes into contact with the internal fluid is inevitable. Therefore, a countermeasure against a high temperature and a countermeasure for fixing the vibration sensor 6 are necessary for the rise in temperature.
Therefore, the lateral hole 4d provided in the stem side wall so as to communicate with the vibration sensor installation position in the signal path 4b allows the heat insulating material 7 having a low thermal conductivity to be interposed between the vibration sensor 6 and the stem material, or the vibration sensor 6 to be used. It is used for encapsulating an adhesive 8 for fixing to the stem 4. The stem manufactured in this manner performs a performance test of the vibration sensor by itself and performs calibration on the driving device 13 so that the relationship between the sensor signal and the stem driving signal can be made accurate.

The control unit 15 includes a central processing unit (not shown) for performing well-known signal processing, and a signal line 14 a from a connection terminal 14 provided on the head of the stem 4.
Are connected, and an output signal of the vibration sensor 6 is input through the same line. The driving device 13 is also communicated via the line 13c, and the operation of the driving device 13 is controlled by the control device 15.

Next, the operation of the valve device abnormality detecting device according to the present invention will be described. If leakage occurs in the valve seat when the valve body is fully closed, the leakage flow causes the valve body 3 to vibrate, and the stem 4 integrated with the valve body 3 to vibrate. This is detected by the vibration sensor 6, and a detection signal is sent to the control device 15. The control device 15 responds to the detection signal by using the motor 1 of the drive device 13.
A signal is sent to 3b to rotate, and the stem 4 is driven in a direction to further close the valve body 3 until there is no leakage.

[0020]

According to the present invention, not only is the vibration sensor provided inside the valve stem, but this sensor is connected to an external control device for controlling the driving device of the valve device, and the vibration sensor is provided inside the valve stem. Since the drive device is controlled and the stem is operated in response to the output signal of the vibration sensor representing the information, valve seat leakage can be prevented and an accident due to valve vibration can be prevented.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram schematically illustrating a valve device abnormality detection system according to the present invention.

2A is an enlarged cross-sectional view of a portion of a region A of FIG. 1 showing a vibration sensor provided in a stem of the valve device of FIG. 1, and FIG. FIG. 2 is an enlarged cross-sectional view showing a portion near a region B in FIG. 1 at a certain time.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Valve box, 1a ... Valve seat, 1b ... Fluid inlet passage (fluid passage), 1c ... Fluid outlet passage (fluid passage), 3 ... Valve body, 3a ... Valve seat, 4 ... Stem, 4a ... Screw part,
4b: signal path, 4e: convex conical surface (reverse seat or back sheet), 6: vibration sensor, 7: heat insulating material,
8: adhesive, 13: drive device, 14: connection terminal,
15 ... Control device.

Claims (3)

(57) [Claims] 1. A valve box defining a fluid passage having a valve seat therein, and a valve case movable to selectively open and close the fluid passage, and selectively engaged with the valve seat in a fluid-tight relationship. A valve body having a valve seat adapted to fit therewith; a stem having one end integrally connected to the valve body and the other end extending outside the valve box; and the valve box moving the valve body. A drive device that engages a part of the stem outside of the valve device, wherein the stem has a vibration sensor on a stem portion outside the valve box when the valve body is in the closed position. A control device that receives an output signal from the vibration sensor is disposed outside the valve box, and the control device controls the vibration sensor when the valve body is in the closed position. When vibration due to leakage of the valve seat is detected, the valve is inserted through the stem. An abnormality detection device for a valve device, characterized in that the body is further driven from the closed position in the closing direction, and the drive device is controlled so as to operate until vibration detection by the vibration sensor is substantially eliminated. 2. A signal passage extending from a vicinity of a lower end of a thread portion formed on a part of the stem to a top of the other end of the stem is defined in a central portion of the stem. The abnormality detection device according to claim 1, wherein the vibration sensor is fixed to the bottom with an adhesive and surrounded by a heat insulating material. 3. A connection terminal for a signal line of the vibration sensor is provided on a top portion of the stem,
The outer peripheral groove of the stem communicates with the signal path through a lateral hole, and a signal line of the vibration sensor is connected to the connection terminal through the signal path. Abnormality detection device.