JPH0894545A - In-pipe material detecting device - Google Patents

Abstract

PURPOSE: To provide an in-pipe material detecting device capable of properly detecting any abnormality occurring inside a pipe by specifying the kind of a gas inside the pipe. CONSTITUTION: This detecting device 1 comprises a transmitter 10 for transmitting an electric wave into a pipe 9, a receiver 14 for receiving the electric wave transmitted through the pipe from the transmitter 10; and a signal processing device 4 for detecting the strength of the received electric wave at each frequency, etc. When the transmitter 10 transmits an electric wave from one side of the pipe 9, the electric wave is transmitted through the pipe 9 and received by the receiver 14 and the strength of the received wave is calculated by the signal processing device 4. From the strength calculated, a frequency that has been greatly attenuated is determined and made to correspond to an absorption frequency so as to detect any material existing inside the pipe. When the material existing inside the pipe is thus specified, an abnormality can be judged to occur inside the pipe 9 if the material should not normally exist within the pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-pipe substance detecting device for transmitting a radio wave into a pipe and identifying a substance existing in the pipe from a frequency band absorbed by the substance in the pipe.

[0002]

2. Description of the Related Art For example, a large number of gas pipes for supplying fuel gas to consumers are installed underground, and in chemical plants and the like, pipes for transporting various fluids are arranged regardless of the ground or ground. Has been done. Such gas pipes and pipes carrying various fluids constantly receive external influences such as vibrations of vehicles traveling on the ground, pressure in the ground, or vibrations transmitted from motors in factories, Appropriate inspection is required to prevent cracks and breakage accidents in pipes caused by these external influences. In addition, when an earthquake occurs, it is necessary to inspect the pipes for cracks before supplying gas.

By the way, it is not easy to inspect pipes buried in the ground, and it takes a lot of time and labor to excavate and inspect, and it is economically impossible to inspect all of them. In addition, it is very difficult to directly observe the inside and visually inspect a long pipe that is complicatedly piped.

Therefore, the inventor of the present invention has invented a device for detecting an abnormality that has occurred in the buried pipe using radio waves, and has already applied for it. (Japanese Patent Application No. 5-168550, etc.)

[0005]

However, in the above-mentioned device, attention is paid to the fact that the frequency band of radio waves passing therethrough is narrowed when the opening area inside the pipe is narrowed, and the foreign matter in the pipe is checked to determine the occurrence of an abnormality. It is designed to detect the reflected wave by using the fact that the radio waves transmitted in the pipe are reflected by the obstacle inside the pipe, and the obstacle inside the pipe, especially the substance inside the pipe is confirmed. It was not possible to identify what kind of gas the gas was and what was mixed.

For example, if it is possible to find out by inspection that the gas in the pipe contains water vapor, it can be found that a hole is formed at any location and water enters the pipe through the hole to generate water vapor. . In this way, if the substance mixed in the pipe can be identified, a physical change occurs in the pipe such that the opening area in the pipe is actually narrowed or there is an obstacle in the pipe that reflects radio waves. Even if not
If there is a change in the gas inside the tube, such as when water vapor is mixed, it is possible to detect an anomaly that has occurred in the tube.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide an in-pipe substance detection device capable of easily detecting a substance existing in a pipe for detecting an abnormality occurring in the pipe.

[0008]

In order to solve the above-mentioned problems, the present invention provides a transmitting means which is installed on one side of a metal tube and transmits a radio wave of a predetermined frequency band into the tube, and another means of the other side of the tube. A receiving unit installed on the side for receiving the radio wave from the transmitting unit propagating in the pipe, and a receiving frequency connected to the receiving unit to detect the attenuation frequency of the received radio wave to obtain the frequency absorbed in the pipe, The in-pipe substance detection device was configured with a detection means for detecting the substance existing in the pipe from the absorption frequency.

Further, the transmission frequency band of the transmission means is set according to the absorption frequency of the specific substance to be detected.

Further, the pipe to be inspected is a metal gas pipe, and the detection substance is limited to water vapor.

[0011]

When a radio wave is passed through a tube containing water vapor, oxygen gas, etc., the radio wave having a specific frequency determined for each gas is absorbed by the gas. Therefore, when the receiving means receives the radio wave that has passed through the pipe and inspects the strength for each frequency, the electric field strength in the frequency band peculiar to the gas inside is significantly attenuated, so the attenuated frequency band is detected and the absorption frequency is detected. The substance existing in the pipe is specified by performing the correspondence between the substance and the substance.

[0012]

EXAMPLE An example of the in-pipe substance detecting device of the present invention will be described.

As shown in FIG. 1, the detector 1 includes a transmitter 2, a receiver 3, a signal processor 4 for processing a signal received by the receiver 3, a display 5 for displaying the processed signal, and a frequency range. The switch 6 and the like for switching the

The transmitter 2 includes a transmitter 10 and an antenna 11.
The transmitter 10 is a radio wave transmitter that emits a frequency in the GHz band, and can emit a radio wave in this band while sweeping over a wide frequency band. The antenna 11 is an antenna corresponding to the frequency band transmitted by the transmitter 10, and has a shape that can be inserted into the tube 9 to be inspected.

The pipe 9 is a gas pipe buried in the ground and is made of metal. The pipe 9 is not limited to the gas pipe but may be a pipe provided on the ground used in the plant.

The receiver 3 includes a receiver 14 and an antenna 15.
The receiver 14 is a receiver that receives a radio wave having a frequency corresponding to the radio wave transmitted from the transmitter 10, and can sweep the reception frequency to receive the electric field strength for each frequency. The antenna 15 corresponds to the reception frequency band, and has a shape that can be inserted into the tube 9 like the transmission antenna 11.

The signal processing device 4 analyzes and calculates the electric field strength of the radio wave received by the receiver 14 for each frequency. The switch 6 is a device that is connected to the transmitter 10 and the receiver 14 and matches the frequency range of radio waves used between the transmitter 10 and the receiver 14 with a predetermined frequency band.
The display device 5 displays the frequency on the horizontal axis and the intensity of the received radio wave on the vertical axis on a so-called monitor.

Next, the in-pipe inspection using the detection device 1 will be described.

The antenna 11 of the transmitter 2 and the antenna 14 of the receiver 3 are inserted from both ends of the tube 9 to be inspected and faced each other. The antenna is inserted by, for example, removing the connection port of the flow meter and opening the connection pipe. Here, for example, when inspecting whether water vapor is mixed in the pipe 9, the water vapor absorption frequency band (22.2 GHz, 183.3 GHz, 32) is transmitted from the transmitter 10.
Transmitting while sweeping a frequency band including 5.1 GHz, 380.2 GHz, etc.) with a constant intensity. Fig. 2 shows the intensity distribution of the transmitted radio waves. Note that the strength of the radio wave is not constant over the entire sweep frequency, and may be changed in a predetermined manner, for example, a certain frequency may be increased or decreased if predetermined.

When a radio wave is transmitted from the antenna 11, the radio wave passes through the pipe 9 and is received by the antenna 15. The received radio wave is sent from the receiver 14 to the signal processing device 4, and the signal processing device 4 obtains the electric field strength for each frequency of the received radio wave. The calculated electric field strength for each frequency is displayed on the display device 5.

As described above, the absorption frequency of water vapor is 2
2.2 GHz, 183.3 GHz, 325.1 GHz,
Since it is 380.2 GHz, etc., it is checked from the electric field intensity displayed on the display device 5 whether or not the received intensity is attenuated at a frequency equal to the absorption frequency of water vapor. In the absence of water vapor, a change in only the natural attenuation due to passage through the tube and the attenuation at the frequency specified by the gas should be observed from the type of gas in the tube 9 that is known in advance.

On the other hand, when water vapor is present, attenuation occurs at the water vapor absorption frequency. The state is shown in FIG. As shown in FIG. 3, when water vapor is present in the gas in the tube 9, the strength of the water vapor is reduced at least at the absorption frequency α. Therefore, if it is confirmed that this attenuation frequency matches the absorption frequency of water vapor, it can be determined that the radio waves have been absorbed by the water vapor in the pipe 9, and there is a hole in the wall of the pipe 9 due to the presence of water vapor. From there, it can be determined that water has entered.

In the above embodiment, water vapor is used as an example, but the present invention is not limited to water vapor and other gas may be used.
The absorption frequencies of typical gases are described below.

Oxygen 60 GHz, etc. Nitric oxide 100.4 GHz, 125.6 GHz,
150.7 GHz, 175.8 GHz, etc. Chlorine oxide, 164.3 GHz, 167.2 GHz, etc. Carbon monoxide, 115.2 GHz, 345.8 GHz, etc. Therefore, when the electric field strength is attenuated not only in water vapor but also in these listed frequencies, The detection device 1 can confirm that the corresponding gas is contained in the pipe 9.

In the above embodiment, the transmitter 11 emits a radio wave having a frequency matched to the substance to be inspected. However, the frequency band is not limited and a wide frequency band is emitted to inspect the attenuated frequency band. It may be used to detect the substance in the tube by.

The frequency range may be automatically switched by the signal processing device. For example, when the attenuation at one of the absorption frequencies of water vapor is detected, the frequency band may be switched to check whether the attenuation occurs at the absorption frequency of water vapor at the other frequencies as well. . By doing so, the same substance can be confirmed at a plurality of frequencies, and the accuracy can be increased.

Further, although the transmitter 11 and the receiver 14 are movable in the above example, they may be fixed to the tube 9. For example, the transmitting unit 2 and the receiving unit 3 may be installed in the pipe 9 in advance, and radio waves may be appropriately transmitted from the transmitting unit 2 to check whether or not any abnormality has occurred in the pipe 9. In this way, the pipe at a specific position can be continuously inspected. If such an apparatus is continuously installed, it is possible to easily inspect a pipe over a long distance. Moreover, in this case, even if only the antennas are installed in the pipe at a predetermined interval, the input / output terminals of the antennas are respectively drawn to the ground in advance, and a transmitter or a receiver is connected at the time of inspection so that the inspection can be performed between them. Good. In this way, it is not necessary to insert the antenna for each inspection, and the inspection inside the pipe can be easily performed over a long distance.

[0028]

According to the in-pipe substance detecting device of the present invention, the transmitting means installed on one side of the pipe to be inspected and the constant intensity transmitted from the transmitting means installed on the other side of the pipe are transmitted. Since it is composed of receiving means for receiving radio waves, signal processing means for detecting the frequency attenuated from the received radio waves and comparing it with the radio wave absorption band of the substance, and display device for displaying the result, the substances existing in the pipe (gas ) Can be easily detected by radio waves, and an abnormality that has occurred in the pipe can be reliably detected by using the change in the gas in the pipe.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an in-pipe substance detection device according to the present invention.

FIG. 2 is a graph showing the intensity of transmitted radio waves.

FIG. 3 is a graph showing the intensity of received radio waves.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 detection device 2 transmission part 3 reception part 4 signal processing device 5 display device 6 switcher 10 transmitters 11 and 15 antenna 14 receiver

Claims (4)

[Claims] 1. A transmitting means installed on one side of a metal tube for transmitting a radio wave of a predetermined frequency band into the tube, and a transmitting means installed on the other side of the metal tube and propagating in the tube. A receiving means for receiving the electric wave, and a detecting means connected to the receiving means for detecting the attenuation frequency of the received electric wave to obtain the frequency absorbed in the pipe, and detecting the substance existing in the pipe from the absorption frequency. An in-pipe substance detection device comprising: 2. The in-pipe substance detection device according to claim 1, wherein the transmission frequency band of the transmission means is set according to the absorption frequency of a specific substance to be detected. 3. The in-pipe substance detection device according to claim 1, wherein the pipe is a metal gas pipe. 4. The in-pipe substance detection device according to claim 1, wherein the detection substance is water vapor.