JPH03180731A - Heat medium leakage detecting method for piping for heat medium transportation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for detecting heat medium leakage in heat medium transport piping used for pipes transporting high temperature or low temperature heat medium.
In particular, heat medium transport piping is useful for measuring the temperature of heat medium transport piping and detecting the location of heat medium leaks, and for managing the maintenance, temperature monitoring, and security of plants, buildings, factories, etc. that are equipped with heat medium transport piping. The present invention relates to a heat medium leakage detection method.

[Prior Art] Conventionally, a method for measuring temperature and detecting heat medium leakage in a heat medium transport pipe using a double pipe system is to use a heat insulating material wrapped around a main pipe 101 through which the heat medium passes, as shown in FIG. Thermocouples 103 . By taking out the lead wire 106 taken out from the pair 103 to the outside from the outlet hole 105 of the casing pipe 104 and wiring it to a temperature measuring device, multi-point temperature measurement of the heat medium transport piping is performed. This is a method of detecting the location of a heat medium leak from the abnormal temperature.

[Problem 8 to be solved by the invention] However, the following problems have been pointed out in the case of the multi-point temperature measurement and leakage detection method using thermocouples as described above.

■In order to improve the accuracy of temperature measurement of heat medium transport piping and detection of heat medium leakage, a considerable number of thermocouples 103,...
is necessary.

■ Numerous thermocouples 103° outside the heat insulating material 102...
It is virtually impossible to attach the thermocouples 103, . . . must be drawn out from the outlet hole 105 of the casing pipe 104, there is naturally a limit to the number of temperature measurement points.

■, a large number of thermocouples 103. Lead wire of 106°・
It is very difficult to locate the wiring when taking it out from the casing pipe 104 and wiring it.

■, Each lead wire unit 06.・
... is attached, but because of this, the lead wires 106, ... are easily damaged by gravel contained in the soil, and are easily corroded by various substances. Therefore, it is necessary to take anti-corrosion measures for the thermocouple 103 and the lead wire 106 of the thermocouple 103.

■ Furthermore, a large number of leads and holes 10 are provided in the casing pipe 104.
5 is formed, but it is very difficult to align the thermocouple 103 and the lead-out hole 105, and furthermore, the lead-out hole 105.・・・
・Appropriate waterproofing measures must be taken to prevent corrosion and waterproofing.

The present invention was made in view of the above circumstances, and enables temperature measurement and heat medium leakage detection by creating a large number of measurement points.
Another object of the present invention is to provide a method for detecting heat medium leakage in heat medium transport piping, which does not require a special place for wiring and can easily avoid damage and corrosion of a temperature sensor.

[Means for Solving the Problems] In order to solve the above problems, the present invention installs an optical fiber temperature sensor on the outside of the main pipe through which the heating medium passes, and inputs an optical signal from the input end of the fiber temperature sensor. After that, by receiving scattered light having temperature information reflected from inside the optical fiber temperature sensor, the heating medium transport piping detects the position of the heating medium leak from a sudden change in temperature information due to the leakage of the heating medium. This is a method for detecting heat medium leakage.

[Function] Therefore, by taking the above measures, the present invention allows, for example, one optical fiber temperature sensor to be attached linearly to the outer periphery of the heat insulating material on the outside of the main pipe. For example, the position of the heat medium leak can be detected by detecting the intensity of scattered light that changes depending on temperature information within the optical fiber temperature sensor due to medium leak. Moreover, by utilizing heat convection, it is possible to reliably detect a heating medium leakage state other than the vicinity of the optical fiber temperature sensor, for example, at the bottom of the main pipe.In addition, by wrapping the optical fiber temperature sensor above the main pipe, , it is possible to detect temperature changes with higher sensitivity.

[Example] Hereinafter, an example of the method of the present invention will be described with reference to the drawings. First, Fig. 1 is a diagram showing how a temperature sensor is attached to a pipe, and 1 is a main pipe through which a heat medium such as high temperature or cold temperature passes, and outside of this main pipe 1 there is a pipe for measuring the temperature of the heat medium. A heat insulating material 2 is wrapped around it for holding. Furthermore, an optical fiber temperature sensor 3 is attached to the outer periphery of the heat insulating material 2 in a straight line along the longitudinal direction of the main pipe. 4 is a metal casing pipe, and 5 is a coating material such as resin for protecting the casing pipe 4.

Next, FIG. 2 is a block diagram of a piping temperature measurement and heat medium leakage detection device that employs the method of mounting the temperature sensor 3 as described above. That is, this device includes a pulse drive circuit 11 that generates a pulse signal, a light emitting element 12 that converts the pulse signal of this pulse drive circuit 11 into an optical pulse, and an optical fiber temperature sensor 3 that converts the optical pulse converted by the light emitting element 12. A directional coupler 13 and the like is provided to input the light pulse, and the Raman scattered light having temperature information that is reflected within the optical fiber temperature sensor 3 and returned via the directional coupler 13 after the light pulse is input is converted into Stokes light. Interference filters 141 and 142 that separate the Stokes light and anti-Stokes light into electrical signals, and an optical detection element 15 such as an avalanche photodiode that separately converts the Stokes light and the anti-Stokes light into electric signals.
1,152, the Raman scattered light itself is a very weak signal and fluctuations occur, and the optical detection element 15. ．． In view of the occurrence of shot noise, thermal noise, etc. in 152, an averaging processing means 16 that performs averaging processing for the purpose of improving the S/N, after receiving the pulse generation timing signal of the pulse drive circuit 11, performs Raman scattering. A data processing means 17 and the like are provided for determining the position of scattered light generation from the delay time until light is detected and the temperature from the intensity of the scattered light. Reference numeral 18 denotes a temperature distribution display that displays data such as the state of temperature distribution.

Therefore, according to the embodiment described above, when a pulse signal is generated from the pulse drive circuit 11, this pulse signal is converted into an optical pulse by the light emitting element 12, and then the directional coupler 1
3 and enters the optical fiber temperature sensor 3. Further, the pulse drive circuit 11 supplies a pulse signal or a pulse generation timing signal to the averaging processing means 16 and the temperature data processing means 17 at the same time as sending out the pulse signal to the light emitting element 12 .

After the pulse enters, Raman scattered light with intensity changes depending on the temperature is reflected from inside the optical fiber temperature sensor 3 and passes through the directional coupler 13 to the interference filter 141.14.
People come to □. These interference filters 141.14□ individually extract the Stokes component and anti-Stokes component from the Raman scattered light, and then the optical detection elements 15□, 15□
After converting the converted electrical signals into electrical signals by averaging processing means 16,
The data is supplied to the data processing means 17.

The heat medium leak detection means 17 performs the following processing.

That is, assuming that the speed of light within the optical fiber temperature sensor 3 is known, the scattering position of the Raman scattered light, that is, the distance ML of the tip fiber temperature sensor 3, can be determined by calculating, for example, L = (C/2n) ・Δt. demand.

However, in the above equation, C is the speed of light in vacuum, n is the refractive index of the optical fiber temperature sensor 3, and Δt is the time from receiving the pulse generation timing signal from the pulse drive circuit 11 to detecting the Raman scattered light. be.

On the other hand, the temperature value detected by the optical fiber temperature sensor 3 can be determined from the intensity ratio of the Stokes component and the anti-Stokes component in the Raman scattered light.

Then, by sequentially determining the distance and temperature of the optical fiber temperature sensor 3 at each predetermined period as described above,
The temperature distribution can be known, and the leakage position of the heating medium can be detected from this temperature distribution.

Therefore, according to the method of the above embodiment, the heat insulating material 2
It is only necessary to attach one optical fiber temperature sensor 3 continuously to the outside of the main pipe 1, and if the optical fiber temperature sensor 3 is attached so as to be located above the main pipe 1, the heat convection phenomenon can be utilized. It is possible to detect temperature changes and heat medium leaks outside of the vicinity of the optical fiber temperature sensor 3, such as at the bottom of the main pipe, making it possible to easily measure the temperature at multiple temperature measurement points without the need for multiple sensors as in the past. Can be measured. Moreover, since the optical fiber temperature sensor 3 can be attached to the inside of the casing pipe 4 and pulled out from one end of the pipe, there is no need to make any special arrangements for wiring as in the past. can prevent damage and corrosion.

In the above embodiment, the optical fiber temperature sensor 3 is linearly attached to the outside of the heat insulating material 2, but for example, as shown in FIG. There may be. In addition, not on the outside of the heat insulating material 2,
The optical fiber temperature sensor 3 may be arranged in a straight line, in a meandering manner, or wound around the outside of the main pipe 1 directly or via some member. Furthermore, a plurality of optical fiber temperature sensors 3 may be attached in a straight line at predetermined intervals. In addition, the present invention can be implemented with various modifications without departing from the gist thereof.

[Effects of the Invention] As explained above, according to the present invention, it is possible to detect the leakage state of the heating medium by creating a large number of measurement points, measuring the temperature and specifying the leaking position of the heating medium, and moreover, it is possible to detect the leakage state of the heating medium by creating a large number of measurement points. A special place for wiring is not required, and damage and corrosion of the temperature sensor can be reliably prevented.

[Brief explanation of drawings]

Figures 1 and 2 are shown to explain one embodiment of the method of the present invention. Figure 1 shows the installed state of the temperature sensor, and Figure 2 shows the temperature of the piping and the location of the heat medium leak. FIG. 3 is a diagram showing how a temperature sensor is installed as another embodiment of the method of the present invention, and FIG. 4 is a diagram showing how a temperature sensor is installed to explain the conventional method. It is. DESCRIPTION OF SYMBOLS 1... Main pipe, 2... Heat insulating material, 3... Optical fiber temperature sensor, 4... Casing tube, 11... Pulse drive circuit, 12... Light emitting element, 13... Direction sexual coupler, 14114□...interference filter, 15. ．． 15□・
...Photodetection element, 16...Averaging processing means, 17...
・Data processing means.

Claims (1)

[Claims] In a method for detecting a heat medium leak in a heat medium transport pipe that transports a high temperature or low temperature heat medium, an optical fiber temperature sensor is attached to the outside of the main pipe through which the heat medium passes, and a After inputting an optical signal, by receiving scattered light having temperature information reflected from inside the optical fiber temperature sensor, detecting a position of a heat medium leak from a sudden change in temperature information due to a leak of the heat medium. A method for detecting heat medium leakage in heat medium transport piping, characterized by: