JPS63275875A - Leak detector for regulation valve - Google Patents

Abstract

PURPOSE:To control function of an alarm by detecting difference between output signal of temperature sensors arranged on the inner circumference and the outer circumference of a packing pressing member. CONSTITUTION:A valve plug 3 is inserted slidably through a packing 23 into a plug insertion hole 22 made through an upper cover 12 fixed to a valve body. A member 27 for pressing the packing 23 is arranged on the upper cover 12, and temperature sensors 51, 52 for detecting temperatures at the outer circumference and the inner circumference are arranged on the pressing member 27. Then the difference between output signals fed from the sensors 51, 52 is amplified through a comparison amplifier 56, and an alarm 57 is operated when the difference exceeds over a preset level. Upon occurrence of leakage of fluid to be controlled, temperatures at the inner and outer circumference of the pressing 27 vary, and the alarm 57 is operated through the temperature difference thus information leakage.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a leak detection device for a control valve.

[Conventional technology]

For example, toxic gases such as chlorine gas and carbon dioxide gas.

Control valves that control controlled fluids such as flammable gases such as methane gas, cooling water for nuclear power generation, and high-temperature gases (liquids) are highly dangerous if the fluid leaks outside. It is necessary to reliably prevent this. For this purpose, in a control valve using a valve plug, the valve plug is usually slidably inserted into a plug insertion hole provided in the upper cover of the valve body via a packing, and the packing is pressed by a pressing member. Additionally, leakage of the controlled fluid from between the valve plug and the seal is prevented (Example Publication No. 57-53912). and.

If a leak occurs, the gasket is replaced with a new one or the force with which the pressure member presses the gasket is increased to eliminate the gap between the valve plug and the gasket.

By the way, if the fluid to be controlled is liquid and has low volatility, leakage of the fluid to be controlled can be easily confirmed by regular patrolling and visual inspection. Also.

Even if the fluid to be controlled is a gas, if its temperature is relatively low, between θ and 100°C, apply a test liquid such as clean water or soapy water that is harmless to the fluid to be controlled and the control valve to the area where the leak occurs. That is, the presence or absence of leakage can be easily confirmed by applying it to the opening of the valve plug insertion hole in the top cover and checking whether bubbles are generated there.

[Problem that the invention seeks to solve]

However, regular inspections for leaks are cumbersome because maintenance personnel must go around and check each time, and depending on the location where the control valve is installed, it may not be easy to get close to it, resulting in the problem that it takes time to go around. Furthermore, if the fluid to be controlled is a high-temperature gas, the applied test liquid may scatter, which is dangerous. On the other hand, in the case of low-temperature gases, the applied test liquid freezes, making it impossible to test for leaks. Leakage is confirmed by the appearance of frost solidification. However, this method of using bricks cannot be confirmed depending on the amount of leakage, wind direction, wind speed, temperature of the fluid to be measured, etc.
It was uncertain.

Furthermore, in the case of harmful or flammable gases, it is dangerous to approach the control valve carelessly.

Therefore, the present invention solves the above-mentioned drawbacks.
The present invention aims to provide a leak detection device for a control valve that can constantly monitor the occurrence of leakage in a control room or the like without directly inspecting non-ejected bodies by patrolling.

[Rounding method to solve problems]

In order to achieve the above object, the present invention includes a valve plug that is movably inserted into a plug insertion hole of a top lid attached to a valve body through a gasket, and a pressing member that presses the gasket is disposed on the top lid. Two temperature sensors are disposed on this pressing member to detect the temperature of its outer part and inner peripheral part respectively, and the difference between the output signals from these two sensors is amplified by a comparator amplifier, and this difference signal is The alarm is activated when the value exceeds a preset value.

[Effect]

In the present invention, when a leak of the controlled fluid occurs, the temperature of the inner and outer peripheral portions of the pressing member changes, and the temperature difference causes an alarm to operate to notify the user of the leak.

〔Example〕

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

FIG. 1 is a block diagram showing an embodiment of a leak detection device according to the present invention, and FIG. 2 is a sectional view of a control valve equipped with the same device. In these figures, nine examples are shown in which this embodiment is applied to a top guide type single-seat control valve. The valve plug 3 is composed of a diamond slam type operation part 4 that reciprocates in its axial direction, and a valve positioner 5 that compensates for fluctuations in the valve plug 3 caused by the controlled fluid 1 and controls the valve plug 3 to accurately position it in accordance with an input signal. ing.

The main body part 2 includes a valve main body 10 connected in the middle of the piping, an upper lid 12 that securely closes an opening 11 opening at the center of the upper surface of the valve main body 10, the valve plug 3, and guides the valve plug 3. Equipped with all 13 guide rings. The inside of the valve body 10 is partitioned into an upstream passage 15 and a downstream passage 16 by a partition wall 14 .

Further, a communication hole 1γ is formed in the center of the partition wall 14 to communicate the two passages 15 and 16, and a seat ring 18 is fitted and fixed in this hole 17. The upper lid 12 is the valve body 1
0 via a gasket (not shown),
By being firmly fixed by the stud bolt 19 and the nut 20, the flange 13 & protruding from the outer peripheral surface of the upper end of the guide link 13 is connected to the opening 11 of the valve body 10.
It is fixed by pressing. A plug insertion hole 22 is formed through the center of the upper lid 12, and the valve plug 3 is slidably inserted into this hole 22 via a gasket 23, and its upper end protrudes above the upper lid 12. is connected to the lower end of the stem 24 of the operating part 4 via a stem connector 25, and the lower end is seated on the valve seat 26 of the seat ring 18 when fully closed. In order to improve the performance, a pressing member 2T is provided to press the seal 23.The pressing member 27 is formed into a cylindrical shape as shown in FIG. A packing follower 28 having a packing follower 28, a packing flange 30 placed on the packing follower 28, and a packing flange 30 placed on the packing follower 28.
8 and a plurality of stand bolts 31 and nuts 32.

The bolt 31 is screwed into a screw hole 33 of the top cover 12. Note that 34 is a plug hole formed in the center of the packing flange 30.

The 1v part 4 includes the stem 24 and the upper lid 12.
a spring 3T disposed within the spring case 36 and urging the stem 24 downward; a diaphragm case 38 disposed on the spring case 36; A diaphragm 394 whose peripheral edge is held by the diaphragm 394! The upper end of the stem 24 is connected to this diaphragm 39.

The valve positioner 5 is attached to the yoke 361 of the spring case 36, and has a feedback lever 41 that constitutes a feedback mechanism and is swingably extended toward the stem connector 25. It is connected to the stem connector 25 by a pin 43 that is inserted into and engaged with a long hole 42 provided at the outer end. The valve positioner 5 also has a nozzle (not shown).
Built-in flapper mechanism allows input signals (for example, 4 to 2
When the flapper swings and displaces in response to 0 mA) I, the nozzle back pressure changes, and this nozzle back pressure is amplified by the pylon (IJ relay (not shown)) and is applied to the lower chamber of the diaphragm of the diaphragm case 38 by a valve and drive. Supplied as pressure Pout. Then, the diaphragm 39 elastically deforms upward and pulls up the stem 24 and the valve plug 3 against the spring 3T, thereby adjusting the valve opening of the main body 2. Further, the movement of the stem 24 is fed back to the nozzle flapper mechanism by a feedback mechanism including the feedback lever 41, thereby stabilizing the movement of the flapper.

Since such a valve positioner 5 is conventionally known, further detailed table structure, explanation, etc. will be omitted. Please refer to the application filed as No.-123822.

Now, the leak detection device 50 for detecting the leakage of the controlled fluid 1 from the plug insertion hole 22 of the upper lid 12 in the control valve constructed as described above is equipped with the
first and second temperature sensors 51 and 52 that detect the temperature of the outer and inner circumferences of the sensor, and first and second preamplifiers 54 that amplify the output signals from these sensors 51 and 52, respectively. 55, a comparator amplifier 56 that compares and amplifies the output a from both amplifiers 54 and 55, and an alarm that operates to issue an alarm when the output signal from the comparator amplifier 56 exceeds a preset value. It consists of 57. The first temperature sensor 51 is connected to the packing follower 2.
The second temperature sensor 52 is an annular temperature sensor 52 that is fixed to the upper end of the outer peripheral surface of the packing follower 28 and is formed near the lower opening of the inner peripheral surface of the packing follower 28 . , 168. Said 1st. Second preamplifier 54.55 and comparison amplifier 56
is arranged in the valve positioner 5 mentioned above, and the alarm device 5
7 is located in the control room.

In the leak detection device 50 having such a configuration,
When the controlled fluid 1 does not leak from the plug insertion hole 22, the seal follower 2B is hardly affected by the temperature of the fluid 1, or the fluid temperature decreases due to heat conduction to the valve body 10. When the temperature is transmitted through the upper lid 12 or the like, the temperature of the entire follower 28 increases almost uniformly (or decreases if the controlled fluid is lower than room temperature). Therefore, the temperatures of the i-periphery and the inner circumference of the packing follower 280 are almost equal, and there is no difference in the output signals from the first and second temperature sensors 51, 52, and even if there is a difference in the temperature sensor, the difference is Extremely small. The output signals from these sensors 51 and 52 are amplified by first and second preamplifiers 54 and 55, and then compared and amplified by a comparison amplifier 56, and the difference signal is sent to the alarm 51 as an output signal. is input. However, this output signal is below a preset value and does not operate the alarm 51.

Next, when the controlled fluid 1 begins to leak from the plug insertion hole 22, albeit slightly, this leaked fluid passes through the center hole 29 of the packing follower 28 and leaks to the outside, so that the outer circumference and inner circumference of the follower 28 are There will be a difference in temperature. That is,
When the controlled fluid 1 is higher than normal temperature, the temperature of the inner peripheral part is higher than that of the outer peripheral part, and the opposite is true when the controlled fluid 1 is lower than normal temperature. Moreover, the temperature difference between the inner circumferential portion and the outer circumferential portion becomes more pronounced as the temperature difference between the controlled fluid 1 and the normal temperature increases.

As a result, a difference is generated between the output signals from the first and second temperature sensors 51 and 52, and the difference signal between these output signals is amplified by the comparator amplifier 56, and the alarm 57 is amplified as an output signal.
is input. In this case, the output signal is larger than the preset value, and the alarm 5T operates and issues a 9-alarm signal to notify the leakage of the controlled fluid 1.

Thus, with the leak detection device 50 having such a configuration, it is not necessary to periodically inspect the control valve by going around, and leakage of the controlled fluid 1 can be constantly monitored from the comfort of the control room. . Therefore, accidents during inspection can be prevented, and the occurrence of leakage can be detected immediately, so that it is possible to take prompt action and prevent a major accident from occurring.

Also, the temperature sensors 51 and 52 control the packing follower 2.
It detects a temperature of 8, so the sensitivity is that of a dog.

Unlike conventional detection methods using mirrors, leakage can be detected accurately with almost no influence from wind.

FIG. 3 is a block diagram of main parts showing another embodiment of the present invention. In this embodiment, output signals from the first and second temperature sensors are compared and amplified by a comparator amplifier 56, and the difference voltage vo is inputted to a leak comparator 60 and compared with a threshold voltage v1. Output signal 1 from comparator 60 when Vo is greater than threshold voltage v1
．． The device is configured to send out a signal to activate an alarm.

It is obvious that the same effects as in the above embodiment can be obtained also in such a configuration.

FIG. 4 is a sectional view of a packing follower showing still another embodiment of the present invention. In this embodiment, a blind hole 61 having a depth a little smaller than the wall thickness of the follower 28 is formed in the lower part of the outer peripheral surface of the packing follower 28 in the radial direction, and a second temperature sensor 52 is housed deep inside the blind hole 61. be. In such a configuration, contact between the second pressure sensor 52 and the leaked fluid can be prevented, so the durability of the sensor 52 can be improved, and it is highly effective when applied to corrosive controlled fluids. It is.

Figure 5 shows Patsukin 7 lunge 30 on Patsukin follower substitution.
First and second temperature sensors 51 and 52 are disposed in the chamber, and leakage of the fluid to be controlled is detected by detecting the temperatures at the outer and inner circumferences thereof. In this case, the through packing flange 30 shown in FIG.
8, the leakage fluid passes through the center hole 29 of the packing follower 28 and enters the plug hole 3 of the 7 flange 30.
4 leaks to the outside, a change occurs in the temperature of the outer and inner circumferences of the packing flange 3°, making it possible to detect leakage of the controlled fluid.

Although the above embodiment is applied to a top guide type single-seat control valve, the application is not limited to this, and can be applied to cage type control valves and the like.

Furthermore, it goes without saying that the present invention can also be applied to a manual valve.

〔Effect of the invention〕

As explained above, the control valve leak detection device according to the present invention detects the leakage of the gasket due to the leakage of the controlled fluid.
Since it is configured to detect temperature changes in the outer circumferential area using two temperature sensors, there is no need for security personnel to regularly patrol and check for leaks, and it can be detected reliably in control rooms, etc. Can be done. Therefore, flammable gas.

It is safe in the case of toxic gases, etc., and is extremely effective, as it enables early detection of leaks and minimizes damage caused by accidents.

Increase added value as a control valve.

[BRIEF DESCRIPTION OF THE DRAWINGS] Fig. 1 is a configuration diagram showing an embodiment of the leak detection device according to the present invention, and Fig. 2 is a sectional view of g and w joints equipped with the same device.
Fig. 3 is a main part configuration diagram showing another embodiment of the leak detection device, Fig. 4 is a sectional view of a packing follower showing still another embodiment of the present invention, and Fig. 5 shows a temperature sensor attached to the packing flange. FIG. 1... Controlled fluid, 2... Fist/body part, 3...
Valve plug, 4... Operating unit, 5... Pot valve positioner, 11-... Opening, 12... Upper lid, 18...
... Seat ring, 22 ... Plug insertion hole, 23
...Kenpatsukin, 28 ---Kenpa Nkinhorowa, 3
00.0. Packing flange, 5111...First temperature sensor, No. 52...Second temperature sensor, 54#--
・First preamplifier, 55... second preamplifier,
56...Comparison amplifier, 57...A signal, 60...
IIe・Comparator.

Claims (1)

[Claims] A valve body, an upper lid that closes an opening of the valve body, a valve plug that is inserted into a plug insertion hole of the upper lid via a packing and controls the flow rate of a controlled fluid flowing inside the valve body, and the upper lid. In the control valve, the pressure member is disposed in the pressure member and presses the packing, and the pressure member is provided with first and second temperature sensors that respectively detect temperatures at an outer circumferential portion and an inner circumferential portion of the press member. Leak detection of a control valve characterized in that the difference between the output signals from these two sensors is amplified by a comparator amplifier, and an alarm is activated when this difference signal exceeds a preset value. Device.