JP2681003B2 - 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 of leakage of the gland packing which seals the internal fluid as another abnormality,
During use, the surface pressure of this part may be insufficient and the internal fluid may leak. To prevent this, there is a method in which the backsheet is always effective.

[0004]

However, in the above-mentioned method, since the surface pressure is constantly applied even when there is no fear of leakage, the gland packing and the back sheet are promoted to deteriorate over time, which is useful when actually necessary. There was something I didn't do.

Further, the existing stem has no means for obtaining various kinds of information by using the temperature of the internal fluid as a medium, and when measuring the temperature, the temperature sensor is not permanently installed. At the same time, the measured values could not be calibrated,
When a temperature change is detected and you want to make some judgment about the detected value, it is necessary to calibrate each time when the plant stops, etc., and there is a problem such as lack of practicality. Since only one piece of information was processed, it lacked comprehensive information evaluation.

Therefore, the leakage from the gland packing can be detected, the information obtained by the detection is processed, and the drive device of the valve stem is controlled based on the processing information, so that the valve itself can respond to the leakage. There is a need for anomaly detection devices that allow treatment.

A main object of the present invention is to detect a rise in the temperature of the stem due to the leakage when a leak occurs in the gland packing portion of the valve body and drive the stem in the direction in which the valve body further opens. An object of the present invention is to provide an abnormality detecting device for a valve device, which can apply a surface pressure to a reverse seat (back seat) provided in the valve device and thereby stop leakage.

Another object of the present invention is to measure the load applied to the stem at the time of leakage prevention, and compare the measured load with a preset maximum allowable stem-specific load of the valve,
An object of the present invention is to provide an abnormality detecting device for a valve device that can increase the load on the stem and prevent leakage from the gland packing.

Still another object of the present invention is to store the information in the memory of the microcomputer and call it to the display device as needed when the leakage does not stop even when the maximum load is applied to the stem. An object of the present invention is to provide an abnormality detecting device for a valve device, which can be used as information for knowing damage to a back seat (back seat) at the time of valve maintenance at the time of periodic inspection and the like.

Further, an object of the present invention is to use a strain sensor used for preventing leakage of a gland packing part, thereby making it possible to detect an abnormal state such as a valve body being caught due to an abnormally high pressure inside the valve box under a high temperature condition. Another object of the present invention is to provide an abnormality detection device for a valve device that can deal with the above.

[0011]

In order to achieve the above-mentioned object, an abnormality detecting device of the present invention is a valve box which defines a fluid passage having a valve seat therein, and selectively opens and closes the fluid passage. A valve body having a valve seat movable between a fully open position and a fully closed position and adapted to selectively engage the valve seat in a fluid sealing relationship; Is integrally connected, and the other end penetrates the gland packing of the valve box and extends to the outside of the valve box, and the outside of the valve box to move the valve element between the fully open position and the fully closed position. In the valve device including a drive device that engages with a part of the stem, the stem has a temperature inside the stem portion outside the valve box when the valve body is in the fully closed position. A sensor and a strain sensor are arranged, and the temperature sensor is provided outside the valve box. A control device that receives output signals from the sensor and the strain sensor is arranged, and when the valve body is in the fully open position, the temperature sensor detects a temperature change due to leakage of the gland packing. Sometimes the valve element is further driven in the opening direction from the fully opened position via the stem, and the strain sensor monitors a load applied to the stem by the drive until the temperature change is substantially eliminated. It is characterized in that the drive device is controlled to operate.

In a preferred embodiment, a part of the stem with which the drive device is engaged is provided with a threaded portion on its outer circumference, and the temperature sensor is preferably provided in the outer circumferential groove of the stem near the lower end of the threaded portion. And the strain sensor is disposed so as to be covered with the covering material. 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 in the central portion of the stem. Further, a connection terminal for the signal line of the temperature sensor and the strain sensor is provided on the top of the stem, and the outer peripheral groove of the stem communicates with the signal passage through the lateral hole. The signal line is connected to the connection terminal through the lateral hole and the signal passage.

The control device is a microcomputer including an interface, a memory, and a central processing unit. The maximum allowable load of the stem is stored in advance in this memory, and the fully open position or the fully closed position of the valve body is stored. Further driving of the stem in the open or closed direction from is carried out comparing the maximum permissible load stored in the memory with the load detected by the strain sensor.

A display device is connected to the above-mentioned interface, and when the load does not stop even when the load applied to the stem reaches the maximum allowable load, the information is stored in the memory. The information can be read out to the display device.

[0015]

If the gland packing is damaged when the valve body is fully opened, the fluid flowing through the fluid passage leaks from the gland packing, causing a temperature change in the stem portion where the temperature sensor is provided, which causes the temperature sensor to It detects and sends an output signal to the control device. The control device determines that this signal is a leakage of the gland packing, and drives the stem in a direction in which the valve body opens further. As a result, a reverse seat (back sheet) provided on the valve lid and the stem acts to prevent leakage of the gland packing. Also in this case, the load on the stem is monitored by the strain sensor.

[0016]

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
At the top of the valve box 1, a valve lid 3 connected by a suitable fastening means such as a bolt 2a selectively intervenes between the valve seats formed in the valve box, and a fluid inlet passage 1b and an outlet passage 1c. 2 is a valve body that brings the valve into a communication state or a non-communication state and has a valve seat 3a. In this well-known valve element 3, as shown in FIG. The lower end of the valve stem 4 including the strain sensor (gauge) 10 and the like is integrally connected by a 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. 1 in an enlarged manner. Since a known device may be used, the description of the sensor itself is omitted.

The stem 4 extends upward through a well-known gland packing 12 arranged in the cylindrical portion 2c of the valve lid 2 and is attached to the top of the valve lid 2 by a bolt / nut assembly 2d. Extended into the drive device 13 and
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 by a packing retainer 12a from above, and the gland packing 12 of the lower reverse seat 12 is held.
A concave conical surface 12c is formed on the lower surface of b. 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 constitute a reverse seat (back seat).

The mounting positions of the above-mentioned various sensors 9 and 10 on the stem 4 are selected at the lower end position outside the stem screw portion 4a which moves when the valve is opened and closed, and at such a position, the temperature sensor 9 and The strain sensor 10 is embedded in a groove 4c formed on the outer peripheral surface of the stem 4 with an appropriate resin coating material (a heat resistant resin such as a registered trade name "Teflon" is preferable) 11 at the above-mentioned position, Protected. As described above, the temperature sensor 9 is attached at a position adjacent to the strain sensor 10 having a diameter smaller than the outer diameter of the stem, can be calibrated simultaneously with the production of the stem, and operates as a permanent sensor. The groove 4c communicates with the signal passage 4b through the lateral hole 4d, and the signal lines (not shown) of the temperature sensor 9 and the strain sensor 10 (not shown) pass through the lateral hole 4d.
It reaches | attains to b, and it connects with the connection terminal 14 provided in the head of the stem 4. When the stem has a small diameter, the temperature sensor 9 and the strain sensor 10 may be attached so as to project from the outer peripheral surface of the stem rather than the inside thereof.

By selecting the positions of the sensors 9 and 10 as described above, the temperature sensor can be provided at a position close to the gland packing.

The control unit 15 may be a microcomputer or a personal computer, and the central processing unit 1
6, a memory 17 and an interface 18. The interface 18 has a signal line 14 a from a connection terminal 14 provided on the head of the stem 4,
14b and the like are connected, and the output signals of the sensors 9 and 10 are input through the same line. Further, the above-mentioned drive device 13 is also connected to the interface 18 via the line 13c, and the operation of the drive device 13 is controlled by the control device 15
Is controlled by.

Next, the operation of the abnormality detecting device for a valve device according to the present invention will be described. First, when the valve is closed while a fluid such as high-temperature and high-pressure steam is flowing through the valve device, the valve 3
At the same time, since a part of the stem 4 is exposed to the fluid, the stem 4 expands in a direction to push the valve body 3 to the valve closing position.
When the valve device is cooled by shutting off the high-temperature and high-pressure fluid due to the closing of the valve, the valve box 1 is provided with the valve seats 1a and 1 formed in the fluid passage.
Since a contracts in the directions approaching each other, the valve body normally embraces, and it becomes difficult to open the valve. However, according to the present invention, since the temperature sensor 9 monitors the stem temperature and the strain sensor 10 monitors the load of the stem 4, the expansion of the stem 4 pushes the valve body 3 to the closed position. In order not to do so, the controller 15 calculates the expansion amount of the stem due to the rise of the stem temperature, and pulls up the stem 4 by a distance corresponding to that amount. At this time, by monitoring the load at the time of raising the stem with the strain sensor 10, it is possible to prevent the valve seat surface pressure from becoming insufficient and the valve seat from leaking.
A command can be issued to the driving device 13. Therefore, even if the valve box cools with the closing of the valve, no trouble occurs in the valve opening operation.

After the valve is closed, the bottom of the valve body 3 and the valve box 1 are also closed.
When the drain accumulates in the space 1d defined between the bottom of the valve and the valve case, the temperature of the valve box rises at the time of warm-up accompanying the restart, and the drain in the space 1d is heated and vaporized. Since there is no escape space for the steam, the valve body 3 is often urged in a direction to further close the valve, that is, a direction in which the valve body 3 is pressed against the valve seat of the valve box. However, according to the present invention, the temperature sensor 9 is attached to the stem 4.
And the strain sensor 10 is provided to detect the temperature rise and to raise and retract the stem 4 while taking into account the load acting on the stem 4, so that the phenomenon of embracing the valve body is avoided.

On the other hand, regarding the leakage of the gland packing 12 in the valve open state, the temperature of the stem 4 is monitored by the temperature sensor 9 and sent to the control unit 15, and the central processing unit 16 of the temperature change width stores the temperature change width in the memory 17. Judgment is made as to whether or not it exceeds the reference range stored in 1., and if it exceeds, it is judged that a leakage state has occurred. Then, the control device 15 issues a command to drive the stem 4 in the direction in which the valve element 3 at the fully open position further moves up until the change width of the temperature falls within the reference range. When the valve body is in the fully opened state, as described above, the concave conical surface 12 formed on the lower surface of the inverted seat 12b.
Since the convex conical surface 4e formed on the stem 4 is fitted to c, the surface pressure load on the conical surface, that is, the back seats 12c, 4e is increased by the above-described driving of the stem 4, and as a result, Stop the leak. In this way, even in the case of leakage of the gland packing 12, the leakage can be stopped by feeding back the temperature detection result as a change in the axial position of the stem, and if it does not stop, the abnormality of the gland packing is notified. The information is stored in the memory 17 and can be used to care for the gland packing at the time of the periodic inspection at the time of the stop of the plant, similarly to the leakage of the valve seat.

Regarding the back seats, ie, the conical surfaces 12c and 4e for preventing the leakage of the gland packing, the existing valve device always uses the back seat even if there is no leakage, so that this part is damaged. However, it has been a factor of trouble such as not being useful when it is necessary to stop leakage, but in the present invention, the temperature of the stem is monitored and the backsheet can be used to prevent leakage of the gland packing part. As compared with the conventional valve device, there is less concern about the deterioration of the back seat over time, and the occurrence of trouble can be reduced accordingly.

Further, in the existing valve device, when the valve closing operation is performed under a high temperature condition, the valve box temperature is lowered from the high temperature after the valve is closed, so that the distance between both valve seats of the valve box is contracted. There is an accident that hugs the body and causes the inability to open the valve,
In the present invention, the stem and the valve element are configured to move integrally, and the temperature change of the stem after the valve is closed and the load change applied to the stem are detected by the temperature sensor 9 and the strain sensor 10, respectively. Even a slight movement of the stem due to the opening and closing of the body, the load on the stem is detected by the strain sensor and the load is too large (thrust of the valve body → embracing) or too small (small surface pressure → leakage). Easy), and by operating the valve according to the load, an appropriate valve body position is secured, and cuddling is prevented beforehand.
The trouble caused by this can be avoided.

[0027]

According to the present invention, not only the temperature sensor and the strain sensor are provided inside the valve stem, but these sensors are connected to the external control device for controlling the drive device of the valve device. In addition, since the drive device is controlled and the stem is operated in response to the output signal of each sensor representing the information inside the valve, it is possible to prevent leakage of the gland packing part and prevent inability to open the valve. . In addition, if the load information of the stem at the time when the leakage can be stopped is stored in the memory of the control device, it is possible to know the aging of the valve by appropriately calling this information.

Regarding the use of the back seat to prevent leakage of the gland packing, the existing valve device always works even without leakage, so that the back seat is apt to be damaged and is not useful when necessary. Although it was a cause of trouble such as no occurrence, in the present invention, since the surface pressure is exerted on the back sheet only when the temperature change of the stem is detected and the leakage occurs, there is less fear of deterioration over time as compared with the conventional one. As a result, a valve device with less trouble can be provided.

Further, in the existing valve device, when a high temperature and high pressure fluid is handled as in a nuclear power plant, when the valve closing operation is performed, the temperature of the valve box through which the high temperature and high pressure fluid is flowing after the valve is closed. Since the temperature drops from a high temperature, there is a possibility that the space between the valve seat surfaces contracts and hugs the valve element, resulting in inability to open the valve.However, according to the present invention, the stem temperature change after the valve is closed and the load change on the stem are changed. By detecting the, the entanglement can be prevented in advance by performing the valve operation according to the change. As described above, according to the present invention, it is possible to provide a high-performance valve device having self-diagnosis and self-operation functions.

[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 in FIG. 1 showing various sensors provided in a stem of the valve device in FIG. 1, and FIG. FIG. 2 is an enlarged cross-sectional view showing a portion near a region B in FIG.

[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 passage, 4c ... Outer peripheral groove, 4d ... Horizontal hole, 4e
... Convex conical surface (back seat or back seat), 9 ...
Temperature sensor, 10 ... Strain sensor, 11 ... Coating material, 1
2 ... Gland packing, 12a ... Suppressing packing, 1
2b ... reciprocal seat, 12c ... concave conical surface (reverse seat or back seat), 13 ... driving device, 14 ... connection terminal,
15 ... Control device, 16 ... Central processing unit, 17 ... Memory, 18 ... Interface, 19 ... Display device.

Claims (6)

(57) [Claims] 1. A valve box defining a fluid passage having a valve seat therein, movable between a fully open position and a fully closed position for selectively opening and closing the fluid passage, and the valve seat. A valve body having a valve seat adapted to selectively engage in a fluid-sealed relationship and a valve body having one end integrally coupled to the valve body and the other end penetrating a gland packing of the valve box. In a valve device comprising a stem extending to the outside of the box, and a drive device engaging a part of the stem outside the valve box so as to move the valve element between the fully open position and the fully closed position, In the stem, a temperature sensor and a strain sensor are arranged on a stem portion outside the valve box when the valve body is in the fully closed position, and the temperature sensor is arranged outside the valve box. A control device for receiving an output signal from the sensor and the strain sensor, When the valve body is in the fully open position by the control device, the valve body is further driven from the fully open position to the opening direction via the stem when the temperature sensor detects a temperature change due to leakage of the gland packing. An abnormality detection device for a valve device, which controls the drive device to operate until the temperature change substantially disappears while monitoring the load applied to the stem by the same drive by the strain sensor. . 2. A part of the stem with which the driving device is engaged has a thread formed on an outer periphery thereof. The temperature sensor and the strain are formed in an outer peripheral groove of the stem near a lower end of the thread. The abnormality detection device according to claim 1, wherein the sensor is provided so as to be covered by a covering material. 3. The abnormality detection according to claim 2, wherein 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 in the central portion of the stem. apparatus. 4. A connection terminal for signal lines of the temperature sensor and the strain sensor is provided on the top of the stem, and an outer peripheral groove of the stem communicates with the signal passage through a lateral hole. The abnormality detection device according to claim 3, wherein signal lines of the temperature sensor and the strain sensor are connected to the connection terminal through the lateral hole and the signal passage. 5. The control device, comprising: an interface;
A microcomputer including a memory and a central processing unit, wherein the maximum allowable load of the stem is stored in the memory, and driving of the stem in a further opening direction from a fully opened position of the valve body is performed. The abnormality detection device according to claim 1, wherein the abnormality detection device is performed while comparing the maximum allowable load stored in the memory with a load detected by the strain sensor. 6. A display device connected to the interface, wherein the memory stores the information when leakage does not stop even if the load on the stem reaches the maximum allowable load. The abnormality detection device according to claim 5, wherein the information is readable to the display device.