JPH028725A - Leak detector - Google Patents

Abstract

PURPOSE:To achieve a reduction of the number and length of connection cables between a temperature detection means and a controlling/monitoring means by providing a leak piping with a remote shut-off valve and a thermocouple type temperature detector to input an output signal into an arithmetic device through a cable made of the same material as strands of a thermocouple with the a plurality of temperature detectors connected together in series. CONSTITUTION:A leak piping 4 is connected to a ground section of a shut-off valve 1 of a piping 2 through which a high-temperature liquid flows while being provided with the a solenoid valve 9 and temperature detectors 10. A plurality of temperature detectors 10, 10a-10c, for instance, are connected in series while being connected to an arithmetic device 18 of a controlling/monitoring means with connection wires 15, 16 and 17 made of the same material as strands of a thermocouple element composing the temperature detector. Then, when a leak occurs in the shut-off valve 1b, a command of closure is outputted sequentially to solenoid valves 9a-9c of a controller 19 associated with an increase in rate of change in an input signal of the arithmetic device 18 and the leak of the shut-off valve 1b is specified from an output of a temperature detector 10b when the valves are closed sequentially.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to valves, etc. disposed in piping containing high-temperature process fluid, such as in nuclear power plants, etc. The present invention relates to a device for detecting process fluid leaks from equipment, and particularly relates to reducing the length of a connecting cable between a temperature detecting means installed in a leak detecting device using temperature detection and a monitoring device.

(Prior art) Nuclear power plants have traditionally handled high-temperature, high-pressure process fluids, and the glands of valves and other equipment installed in piping containing these fluids have been used to detect process fluid leaks. A leak detection device is installed.

However, for example, in this type of leak detection @ installation, a leak piping for extracting leaked liquid is connected to the ground part of the equipment to be monitored among a large number of devices such as valves, and the flow of leaked liquid is temporarily blocked to this leak piping. A remote control valve (hereinafter referred to as a solenoid valve) is provided to detect the temperature rise due to the passage of the leaked liquid, and a separate operation switch is provided to open and close the solenoid valve, and a monitor detects leakage from the temperature detector signal. Equipment is being installed.

In other words, high-temperature leaked liquid that leaks from the gland of the equipment passes through the leakage pipe, flows down to the drain pit, etc. via the solenoid valve and temperature sensor, and is discharged, but during this process, the temperature change at the temperature detection part is detected. to detect whether there is a leak. Therefore, it is difficult to determine whether the detected temperature change is due to leaked liquid.
To determine whether the leak is due to an increase in ambient temperature, close the solenoid valve of the leak piping of the temperature sensor being measured using a manual operation switch to temporarily cut off the flow of the leak liquid, and confirm that the detected temperature drops as a result. leakage from the ground section of the equipment was detected.

(Problems to be Solved by the Invention) In general, high-temperature piping is installed over a wide area in a plant, and a plurality of devices to be monitored for leakage are also installed. Therefore, the leakage detection work for each device is complicated, and it is necessary to separately lay connection cables back and forth for each device from the installed temperature detection means to the remote control and monitoring means, and the number of cables is large and the E length is extremely long. This has the drawback that it requires a large amount of materials and a great deal of effort is required not only for laying it, but also for its inspection and maintenance work in the event of a breakdown.

The present invention has been made in view of the above, and an object of the present invention is to connect a plurality of thermocouple temperature detectors as temperature detection means in series and connect them together, and to connect the temperature detection means and control/monitoring means. It is an object of the present invention to provide a leakage detection device that reduces the number and n length of connection cables and automatically specifies and notifies a leakage detection location.

[Structure of the Invention] (Means for Solving the Problems) A leakage pipe for extracting leaked liquid is attached to each leakage detection part, and a remote opening/closing valve and a thermocouple temperature detector are provided on this leakage pipe.
A plurality of temperature detectors are connected in series with a connecting wire made of the same material as one of the thermocouple wires of the temperature sensor with the polarities aligned, and the output signal of this temperature detection means is connected to the thermocouple wire of the temperature sensor. A calculation device that converts the output signal of the temperature detection means into a rate of change per unit time, and automatically opens and closes the remote opening/closing valve sequentially for a certain period of time as the rate of change increases with this output signal. a control device for controlling, a monitoring device for recording and monitoring the sign of the remote on-off valve controlled by the output and the signal of the temperature detection means from the output of the calculation device; and a monitoring device for inputting the outputs of the calculation device and the monitoring device and controlling the An alarm device that notifies the location of leakage and issues an alarm when the signal level of the temperature detection means exceeds a set value or the gradient of the rate of change of this output signal reaches a predetermined value or above, and an operating switch for the remote on-off valve. .

(Function) A thermocouple temperature detector installed in the leakage pipe generates a thermoelectromotive force corresponding to the temperature of its surroundings.

The terminal block of this temperature detector is also connected to one of the thermocouple wires by a connecting wire made of a different material, and generates a thermoelectromotive force depending on the ambient temperature. These multiple temperature detectors and monitoring devices are connected in series, so
The number and length of the connecting cables used can be reduced by approximately half compared to the conventional case where the temperature detecting means and the monitoring device, which are separated from each other, are individually connected.

Furthermore, the thermoelectromotive force, which is the sum of the thermoelectromotive force generated in the total temperature detector and its terminal block, is input to a calculation device, and the rate of change per unit time is constantly calculated.

Normally, if the solenoid valve is open, there is no leakage of high-temperature process fluid, and there is no change in the ambient temperature of the temperature sensor, the total thermoelectromotive force will not change, so the rate of change per unit time will increase. is zero. If a leak of high-temperature process fluid or a change in ambient temperature occurs, the rate of change of thermoelectromotive force per unit time changes. If this exceeds a predetermined set value, the The device sequentially issues a "close" operation signal to a plurality of solenoid valves at fixed time intervals, and if the gradient of the rate of change changes to the negative side during the solenoid valve "closing operation process,"
At this time, a leak occurred in the ground of the device to which the solenoid valve that was "closed" was connected, and the solenoid valve was "closed".
This is because the leaked liquid was blocked and the thermoelectromotive force of the humidity detector decreased, allowing the leak and its equipment to be automatically identified. In addition, if there is no gradient in the rate of change after one cycle of solenoid valve operation, it can be confirmed that the temperature change is due to the surrounding environment and no leakage has occurred, and the solenoid valve is operated again.
Open

(Example) An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an example of a set of three on-off valves. The on-off valves 1a, 1b, and IC are installed in piping 2a, 2b, and 2C containing high-temperature liquid, respectively, and the on-off valve 1a for one of these will be explained as an example. FIG. 2 is a sectional view of the gland part of the on-off valve (1a), and FIG. 3 is a sectional view of the temperature detection part. A leakage pipe 4a is connected to the ground portion 3 of the on-off valve 1a. The ground part 3 is the second
As shown in the figure, an upper gasket 6 and a lower gasket 7 are installed in the gap between the main body and the valve stem 5, and are sealed to prevent high-temperature liquid inside the bonnet 8 from entering between the valve stem 5 and the main body. There is. A leakage pipe 4a is attached from the side of the main body in the gap between the upper gasket 6 and the lower gasket 7, and when high-temperature liquid leaks from the lower gasket 7, this leaked liquid flows out from the leakage piping 4a. As shown in FIG. 1, this leakage pipe 4a includes a solenoid valve 9a and a temperature detector 10 downstream thereof.
A is provided, and further downstream is a drain funnel 11.
It is connected to a sump tank (not shown) via a. The temperature detector 10a is connected to the leakage pipe 4a as shown in FIG.
A thermocouple type temperature detector is installed in the middle of the protective tube 12a to detect the temperature of the leaking liquid, and a thermocouple element 13a is housed inside the protection tube 12a. This thermocouple element 13a is made of copper (Cu) and stentanium (CU, N + alloy), and both ends are welded, but the other ends are insulated from each other and connected to the terminal block 14a.

FIG. 4 is a detailed connection diagram of the temperature detectors 10a, 10b, and 10C shown in FIG. , 14c are arranged alternately so that they are made of different materials, and are connected to each other by a connecting wire 15 made of copper (Cu), which is the material of one of the wires of the thermocouple element 13a. At the same time, a signal cable 16 made of constantan wire made of the same material is connected from one end of the terminal block 14a of the temperature sensor 10a on the left end to the constantan wire side, and a signal cable 16 made of constantan wire of the same material is connected to one end of the terminal block 14c of the temperature sensor 10c on the right end from the copper wire side. A signal cable 17 made of a copper wire made of the same material is pulled out and connected to an arithmetic device 18.

That is, the temperature detectors 10a and 10i which are the temperature detection means of the present invention
The connection cable between ob, 10G and the arithmetic device 18 of the control and monitoring means is the same as the two connecting wires 15 that connect the temperature detectors 10a, 10b, 10C and the arithmetic device 18 in series.
It is made up of two signal cables 16 and 17.

Furthermore, as shown in FIG. 1, the control and monitoring means includes an arithmetic unit RA18 that calculates the rate of change per unit time from the output of the total temperature detector and outputs a signal when the rate of change exceeds a predetermined rate; The signal issues a command to sequentially close the solenoid valves 9a, 9b, and 9C at fixed time intervals, and the solenoid valve 9
A control device 19 that outputs signals with signs a, 9b, and 9C, sign signals of the electromagnetic valves 9a, 9b, and 9C, and a signal from the arithmetic device 18 are input, and when this signal value exceeds a set value, a monitoring device 20 that issues an alarm and an identification signal when the operation occurs; an alarm device 21 that issues an alarm and a notification signal of an abnormality such as leakage based on the signals from the arithmetic device 18 and the monitoring device 20; Solenoid valve 9a, 9
b, operation switches 22a, 22b for controlling opening and closing of 9C,
It is composed of 22G.

Next, the operation of the above configuration will be explained. The signal input to the arithmetic unit @18, which is the control and monitoring means, is the sum of thermoelectromotive forces generated by the temperature detectors 10a, 10b, and 10c, which are the temperature detection means shown in FIG.

This total electromotive force E (μV) is generated by each temperature sensor 10a,
Thermoelectromotive force Ea (μv), Eb generated at 10b, 10C
(μv), EC (μv), terminal blocks 14a, 14b,
This is the sum of thermoelectromotive forces E'b (μV) and E'C (μV) generated at the connection points with different materials connected at 14c, and is expressed by the following equation (1).

E=Ea +Eb +Ec -E'b-E'C-(1)
Here, if there is no leakage from the ground part 3 of each on-off valve 1a, 1b, 1C, each temperature detector 10a, 10b, 10G is measuring the respective surrounding temperature, and each temperature detector 10
a, 10b, 10G and each terminal block 14a, 14b, 14G
The ambient temperature of each temperature sensor 10a, 10 is the same.
b, IOC ambient temperature ta (C), tb ('C),
The thermoelectromotive force E of the above formula (1) generated at tC ('C)
O is expressed as the following equation (2).

Eo = Ea (tl) + Eb (t2) 10 Ec (t3
)-E'b(t2)-E'c(13)
(2) That is, a thermal lightning pair consisting of thermocouple elements 13a, 13b, 13G of the temperature detectors 10a, 10b, 10c, and a thermal lightning pair consisting of dissimilar metals of the respective terminal blocks 14a, 14b, 14G. Since the pair is under the same conditions, E b(t2
) = E'b(t2), EC(t3) =E'C(t
3), and the equation (2) becomes EO=Ea(tl).

The signal level of this thermoelectromotive force EO (μV) is normally input to the arithmetic unit 18 and the monitoring device 20, and the solenoid valves 9a, 9b, 9C are normally open, and the monitoring device 20
The alarm setting level is set in advance to a value that can be sufficiently distinguished from the thermoelectromotive force EO during normal operation and is lower than the thermoelectromotive force during leakage.

If leakage occurs from the gland portion 3 of the on-off valve 1b, the high-temperature leaked liquid flows into the leakage pipe 4b and passes through the temperature detector 10b. If the temperature at this time is t'2 ("C), a temperature difference occurs between the terminal block 14b and the ambient temperature. At this time, the thermoelectromotive force E1 generated according to the above equation (2)
is expressed as equation (3) below.

El = Ea (tl) 10 Eb (t'2) 10 Ec (t3
)-E'b(t2)-E'C(t3)・
... (3) Since the ambient temperature does not change in the temperature detector 10C, the above equation (3) is expressed as El = Ea (tl) + Eb (
t'2) -E'b(t2), E b(t'2)>
The thermoelectromotive force E1 at this time, which is E'b(t2), is input to the arithmetic device 18 and the monitoring device 20.

Since the arithmetic unit 18 converts the input signal into a rate of change per unit time, there is no change in this during normal operation, so the rate of change ΔE
=O, but if leakage occurs in the on-off valve 1b as described above, the rate of change in amount ΔE until the input signal reaches El
increases. This rate of change ΔE=E1−Eo/l (t
: time), each solenoid valve 9a,
A "close" command signal is sequentially output to 9b and 9C.At this time, in the "closing" operation of the solenoid valves 1a and 1C, the arithmetic unit 18
Although the same change does not occur in the input signal to the temperature sensor 10b of the leakage pipe 4b where the leak has occurred, the leakage liquid is shut off by closing the solenoid valve 9b, so the detection of the temperature sensor 10b increases over time. Since the temperature decreases and the thermoelectromotive force decreases, the thermoelectromotive force E1, which is the input signal of the arithmetic unit 18, also decreases. As a result, the slope of the rate of change ΔE calculated by the arithmetic device 18 is output to the negative side, so the monitoring device 20 uses this signal to identify that a leak has occurred in the on-off valve 1b, and the signal causes the alarm device 21 to This notifies the operator of the occurrence of leakage at the on-off valve 1b.

Furthermore, if there is no gradient in the rate of change ΔF even if all the solenoid valves are operated once, then this change is due to a temperature change in the surrounding environment, and some or all of the temperature detectors may
This is due to a change in the ambient temperature, including inside the leaking pipe and the terminal block. This confirms that no leakage of high-temperature liquid has occurred, so we continue the detection work with all solenoid valves set to "listen" again. The above is performed automatically and easily, thus improving the leak detection function compared to the prior art.

Although the above embodiment has been described with reference to the case where there are three temperature detectors 10, it is possible to use a larger number of temperature detectors, and it goes without saying that the same effect can be obtained even if the temperature detectors 10 are divided into a plurality of groups.

[Effects of the Invention] As described above, according to the present invention, leakage detection can be automatically and easily carried out in various devices installed in piping containing high-pressure process fluid, each of which is installed at a large number and separated from each other at a distance. At the same time, the number and length of connection cables between the detection means and the control and monitoring means are reduced, which improves the leakage detection function and reliability, and reduces the amount of materials required for installation and maintenance work.

[Brief explanation of the drawing]

Fig. 1 is an overall configuration diagram of an embodiment of the present invention, Fig. 2 is a sectional view of the main parts of the on-off valve, Fig. 3 is a sectional view of the temperature detection section, and Fig. 4 is a detailed connection diagram of the temperature detector. . 4a, 4b, 4C...Leak piping 9a, 9b, 9c...Solenoid valve 10a, 10b, 10G...Temperature detector 13a,
13b, 13G...Thermocouple elements 14a, 14b,
14 G...Terminal block 15...Connection wire 16
．． 17... Cable 18... Arithmetic device 19.
...Control Il device 20...Supervision pA device 21...
- Alarm devices 22a, 22b, 22G...operation switches. Agent: Patent Attorney Norio Ogo

Claims (1)

[Claims] In a leakage detection device, a leakage pipe for extracting the leaked liquid is attached to a detection part for high-temperature leakage liquid, and the leakage pipe is equipped with a remote opening/closing valve, an operation switch, and a temperature detection means, wherein the temperature detection means is a thermocouple temperature detection device. The temperature detectors of multiple objects to be monitored are sequentially connected in series with the same polarity as one of the thermocouple wires of the temperature detectors using a connecting wire made of the same material. is connected to an arithmetic device that converts the signal into a rate of change per unit time with a cable made of the same material as the thermocouple wire of the temperature sensor, and as the rate of change increases with the output signal of the arithmetic device, the remote opening/closing valve a control device that automatically controls opening and closing for a certain period of time in sequence; a monitoring device that records and monitors the code of the remote on-off valve controlled by this output and the output signal of the arithmetic device; and a monitoring device that inputs signals from the arithmetic device and the monitoring device. Leakage detection characterized by comprising an alarm device that specifies the leakage location and issues an alarm when the signal level from the temperature detection means reaches a set value or more or the gradient of the rate of change of the output signal reaches a predetermined value or more. Device.