JPH05205177A - Gas leak position detection device - Google Patents

Abstract

PURPOSE:To detect gas leak in a gas flow passage, etc., and specify the leak position. CONSTITUTION:A gas meter 8 monitors flow of gas and when a flow of gas is detected, a flow rate signal transmitter sends a flow rate signal. A 1st leak sound detection sensor 7 and a 2nd leak sound detection sensor 9 monitor leak sound of gas from the gas flow passage, etc., and once a gas leak sound is detected, signals are sent from a 1st leak signal transmitter 12 and a 2nd leak signal transmitter 13. A microcomputer 11 calculates the leak position from the difference in the arrival time of the leak sound between the leak sound detection sensors 7 and 9. The arithmetic result is displayed on a display unit 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas leakage position detecting device capable of detecting a gas leakage from a gas passage, a gas container, a combustion appliance, etc. and calculating a leakage position.

[0002]

2. Description of the Related Art In recent years, gas explosion accidents caused by gas leakage from gas pipes have frequently occurred. Especially, the distance from the gas storage facility to the gas use facility is long, as in hospitals and schools.
If a gas pipe buried underground is used to connect between these spaces, there is a risk that the buried pipe will crack due to corrosion of the buried pipe and uneven settlement of the ground, causing gas leakage.

Conventionally, in order to detect a gas leak from such a gas flow path, a pressure sensor is provided in the gas flow path, and a predetermined inspection period, for example, once a year or once every two years. Each time, the both ends of the gas flow passage to be inspected are closed, the pressure in the gas flow passage is increased to about 850 mmH2 O, and the presence or absence of pressure drop due to the leakage is inspected to detect the gas leakage.

Further, a flow rate sensor is provided in the gas flow path,
There is also a method of detecting a gas leak by constantly monitoring the gas flow rate, thereby monitoring an abnormality in the gas flow rate that cannot be normally used.

[0005]

However, in the above-mentioned conventional leak inspection method, the leak position of the gas cannot be specified although the leak of the gas can be detected. As described above, in facilities such as hospitals and schools, the distance from the gas storage facility to the gas use facility is long, and in many cases there is a gas pipe buried underground. In the case of a long gas pipe (for example, about 200 m) buried underground as described above, it is necessary to dig up the entire buried pipe in order to detect the leak and then specify the leak position. Therefore, the work becomes large-scale, and much labor and time are required to find the leakage position.

[0006]

SUMMARY OF THE INVENTION The present invention has been proposed in view of the above circumstances, and is intended to detect the leakage of gas from a gas flow path or the like and to identify the leakage position. Flow rate detecting means for detecting the flow rate, first leak sound detecting means provided in the gas flow path upstream of the flow rate detecting means,
Leakage sound detected by both of the leakage sound detection means and the second leakage sound detection means provided in the gas flow path downstream of the flow rate detection means, the first leakage sound detection means and the second leakage sound detection means. And a display unit for displaying the leakage position calculated by the leakage position calculation unit.

[0007]

The gas flow rate of the gas flow path is monitored by the flow rate detecting means. The first leak sound detecting means and the second leak sound detecting means monitor the leak sound generated when the gas leaks from the gas passage or the gas container.

In the leak position calculating means, when each leak sound detecting means detects a leak sound, the leak position calculating means calculates the leak position based on the difference in arrival time of each detected leak sound. The leakage position calculated by the leakage position calculation means is displayed on the display means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the embodiments shown in the drawings. FIG. 1 is a schematic block diagram of an embodiment of a gas leakage position detecting device 1 according to the present invention, and FIG. 2 is an explanatory diagram when the gas leakage position detecting device 1 is actually installed. This gas leakage position detection device 1 includes a gas flow path 4 for supplying gas from a gas container 2 such as a gas cylinder to a combustion appliance 3 or the like.
A shutoff valve 5 is provided in the middle of the flow path, and a pressure regulator 6 for adjusting the gas pressure to a constant level is provided in the gas flow path 4 between the gas container 2 and the shutoff valve 5. A first leak sound detection sensor 7 that detects a leak sound of gas is provided between the two, and a gas meter 8 that detects the flow rate of the gas flowing in the gas flow path 4 is provided downstream of the shutoff valve 5 and the gas meter 8 and the combustion Instrument 3
Second, which detects the sound of gas leakage near the combustion instrument 3 between
A leak sound detection sensor 9 is provided.

Then, the microcomputer 11, which is supplied with power from the power source 10 such as a battery, is provided with the first leak sound detecting sensor 7 via the first leak signal transmitter 12 and the second leak sound detecting sensor 7.
The second leak sound detecting sensor 9 is electrically connected via the leak signal transmitter 13, and the gas meter 8 is connected via the flow rate signal transmitter 14.

Further, the microcomputer 11 is electrically connected to an indicator 15 for displaying a leakage position and the like, and a shutoff valve 5 for shutting off the gas passage 4. In addition, the shutoff valve 5 includes a return safety device 16 for returning the shutoff valve 5.
Connect.

The first leak sound detecting sensor 7 and the first leak signal transmitter 12 function as the first leak sound detecting means, and the second leak sound detecting sensor 9 and the second leak signal transmitter 13 are provided.
And 2 function as second leak sound detecting means, the gas meter 8 and the flow rate signal transmitter 14 function as flow rate detecting means, the microcomputer 11 functions as leak position detecting means, and the display 15 functions as display means. ..

The above-mentioned first leak sound detecting sensor 7 and second
The leak sound detection sensor 9 is composed of, for example, an ultrasonic microphone, and detects leak sound from the gas flow path 4 and converts it into an electrical signal.

In order to arrange the leak sound detecting sensors 7 and 9 in the gas flow path 4, it is preferable to incorporate an ultrasonic microphone in the pipe joint. By using this joint with a built-in ultrasonic microphone, the leak sound detection sensors 7 and 9 can be easily attached to existing equipment. Further, the ultrasonic microphone may be built in the pressure regulator 6, a high pressure hose connecting the gas container 2 and the pressure regulator 6, or installed on the surface of the pipe.

In the present embodiment, the leak sound detecting sensors 7 and 9 and the leak sound signal transmitters 12 and 13 are connected to each other by using electrical wiring, but the connection between them is not made by any other method. May be. For example, the sound wave signal transmitter is connected to the second leak sound detection sensor 9, and the sound wave signal transmitter converts the leak sound signal detected by the leak sound detection sensor 7 into a sound wave signal and passes through the gas pipe (gas flow path 4). To transmit. Then, the above-mentioned sound wave signal is detected by the sound wave signal detection sensor provided in the gas flow path 4 near the gas meter 8, and the detected sound wave signal is converted into an electric signal and is transmitted via the second leakage signal transmitter 13 to the micro-wave. It may be configured to input to the computer 11. The same applies to the first leak sound detection sensor 7.

As described above, by connecting the second leak sound detecting sensor 9 and the second leak signal transmitter 13 without using electrical wiring, a hole is formed in the wall for inserting the electrical wiring. There is no need to open. Furthermore, since electrical wiring is unnecessary, installation of equipment is easy. With respect to the first leak sound detection sensor 7 as well, if the upstream side of the gas meter 8 is a buried pipe, installation of equipment is easy.

The flow signal transmitter 14 has a gas meter 8 of 1
Each time it rotates, its mechanical movement is converted into an electrical signal. The case where the flow rate signal transmitter 14 is provided in the membrane gas meter 8 will be described. The flow rate signal transmitter 1
Reference numeral 4 includes a film driven by the flow of gas, a magnet that rotates in conjunction with the motion of the film, and a reed switch that detects the motion of the magnet and repeats ON / OFF. When the magnet rotates in response to the flow of gas, the magnet approaches or moves away from the reed switch, the reed switch turns on and off, and the film makes one reciprocation, that is, every time the magnet makes one revolution. Sends a pulse flow signal.

The microcomputer 11 is composed of a central processing area (CPU), a ROM area, a RAM area, etc., and performs numerical value arithmetic processing and storage processing. The outline of the microcomputer 11 will be described with reference to the block diagram shown in FIG. The leak position determination means 17 includes a flow rate signal determination means 18
And a first leak signal transmitter 12 and a second leak signal transmitter 1
3, the timer 19, and the reference leakage signal storage means 20 and the storage means 21 which will be described later in detail. Then, the flow rate signal judging means 18 judges the presence or absence of gas flowing through the gas flow path 4, the leak position judging means 17 calculates the leak position, and the calculation result is displayed on the display unit 15.

The pressure adjuster 6 is a device for adjusting the pressure of the gas flowing into the gas passage 4 to a constant value. For example, LP
In the case of gas, the pressure inside the cylinder is 0.7-15.6k
The gas pressure is limited to g / cm2, and in order to normally burn the combustion device 3, the gas pressure is 200 to 330 mmH2O.
It is necessary to adjust the pressure and supply it. Therefore, the pressure regulator 6 is attached to the outlet of the gas cylinder to adjust the pressure of the gas flowing into the gas passage 4.

FIG. 4 shows an example of the pressure regulator 6. The pressure regulator 6 is a single-stage pressure regulator, and the inside of the main body is divided into a top and bottom by a diaphragm 22, and an upper part is an air chamber 23 and a lower part is a decompression chamber 24. And decompression chamber 2
4 is provided with a nozzle 26 on the gas inlet 25 side, and the nozzle 26
A valve rod 29 having a closing valve 28 faces the injection port 27 of
The valve rod 29 is connected via a lever 30 to an operator 31 attached to the diaphragm 22. Also, the diaphragm 22
Is pushed down toward the decompression chamber 24 by a spring 32 provided in the air chamber 23.

Therefore, when the high pressure gas flows in from the gas inlet 25, the gas passes through the nozzle 26 and enters the decompression chamber 24. If gas continues to flow in here, the pressure in the decompression chamber 24 rises, and the diaphragm 22 is pushed down toward the air chamber 23 side against the bias of the spring 32. For this reason,
The operator 31 attached to the diaphragm 22 also rises, the lever 30 connected to the operator 31 rotates about the fulcrum 33, the valve rod 29 moves to the gas inlet 25 side, and the closing valve 28 causes the nozzle 26 to move. The amount of gas injected from
When the pressure is high, the injection port 27 is closed. On the other hand, when the gas in the decompression chamber 24 flows out from the gas outlet 34, the pressure in the decompression chamber 24 decreases, and the diaphragm 22 is moved toward the decompression chamber 24 side by the bias of the spring 32. For this reason,
The lever 30 connected to the operator 31 rotates about the fulcrum 33, the valve rod 29 moves to the gas outlet 34 side, the closing valve 28 separates from the injection port 27 of the nozzle 26, and the inflow amount of high-pressure gas. Will increase again. In this way, the diaphragm 22 moves up and down as the pressure inside the decompression chamber 24 rises and falls, and the gas inflow amount from the nozzle 26 is adjusted to keep the gas pressure flowing into the gas passage 4 substantially constant.

Ultrasonic waves are generated when gas leaks due to the formation of fine holes in the gas pipe or gas cylinder, or when gas leaks from the threaded portion of the connecting portion. This ultrasonic wave has a different waveform because sound pressure, frequency, etc. differ depending on the leak location, the diameter of the leak hole, and the leak amount. For example, when the gas leaks from the gas pipe or the gas cylinder on the upstream side of the pressure regulator 6, the ultrasonic wave directly reaches the first leak sound detection sensor 7 and becomes a continuous sound. On the other hand, when the gas leaks from the gas pipe or the like on the downstream side of the pressure regulator 6, the ultrasonic wave detected by the first leak sound detection sensor 7 becomes an intermittent sound.

This is due to the structure of the pressure regulator 6 described above. When the pressure in the gas pipe is a certain value or more, the closing valve 28 closes the injection port 27, so that the ultrasonic wave is the first leak sound detecting sensor 7. When the pressure in the gas pipe decreases due to leakage, the closing valve 28 separates from the injection port 27, and the ultrasonic wave accompanying the leakage and the ultrasonic wave generated when gas is ejected from the injection port 27 cause the first leakage sound. It comes to reach the detection sensor 7. Then, when the high-pressure gas flows in and the pressure in the gas pipe reaches a certain value or more again, the closing valve 28 closes the injection port 27, so that ultrasonic waves do not reach the first leak sound detection sensor 7.

Therefore, when the gas leaks from the gas pipe or the like on the downstream side of the pressure regulator 6, the synthetic ultrasonic wave of the ultrasonic wave accompanying the leak and the ultrasonic wave generated from the injection port 27 becomes an intermittent sound. It will be. Also, the ultrasonic waves due to the leakage from the threaded portion of the connecting portion of the gas pipe show a waveform different from that at the time of leakage from the hole.

Ultrasonic waves are generated from the pressure regulator 6 and the like even when normal gas is used in which no gas leakage occurs, but this ultrasonic wave also has a different waveform from the ultrasonic waves generated based on the leakage. , It is possible to distinguish between normal use and leakage. This is also the case when using caliber, so remember the ultrasonic waveforms during normal use of the device or when using caliber of the device and compare it with the waveform at the time of leakage to confirm normal use and leakage. It can be distinguished from the occurrence.

Therefore, according to the experiment, the waveform of normal use of the instrument, the diameter of the hole formed in the gas pipe or the gas cylinder, and
The relationship with the waveform of the generated ultrasonic wave, the waveform of the ultrasonic wave generated from the screw part of the connection part of the gas pipe, etc. is obtained in advance, and the ultrasonic wave generated when gas leakage actually occurs in the gas pipe It is possible to judge the normal use, estimate the shape of the leakage location, and estimate the leakage amount by comparing the waveform with the waveform.

In the actual gas leakage position detecting device 1, the pattern of the leakage signal based on the judgment of the normal use and the leakage amount obtained in advance by the experiment is stored in the reference leakage signal storage means 20 formed in the ROM area of the microcomputer 11. And then
This stored pattern may be compared with the actually detected pattern. Further, the waveform of the normal instrument use without leakage can be automatically stored in the storage means 21 formed in the RAM area in order to correspond to each equipment.

Next, a method of measuring the leak position will be described. As shown in FIG. 5, a first leak sound detection sensor 7 (point A) and a second leak sound detection sensor 9 (point B) are arranged at two locations apart from the gas pipe (gas flow path 4). If gas leakage occurs at a point X closer to the point B, there will be a difference in the time until the leakage sound reaches the points A and B.

The leak sound propagates in both AB directions at the same time, but when the leak sound reaches B, it reaches the position C in the A direction which is equal to the distance from the leak point X to B. This C
The propagation time of the leaky sound corresponding to the distance N from A to A,
It will be delayed that the leak sound reaches A. The sound velocity V of the leak sound is determined by the arrival time difference Td between the leak sound detection sensors 7 and 9.
By multiplying by, the distance N between ACs is obtained.

Therefore, the second leak sound detecting sensor 9
The distance L from (B) to the leak point X is L = (D−N) / 2 = (D−V × Td) / 2 (1) L: B (second leak sound detection sensor 9) To X (leakage point) D: First leak sound detection sensor 7 and second leak sound detection sensor 9
Distance V: Sound velocity of leakage sound Td: Arrival time difference.

Similarly, the distance l from the first leak sound detecting sensor 7 (A) to the leak point X is l = N + L = (D + N) / 2 = (D + V × Td) / 2 (2) l : Distance from A (first leak sound detection sensor 7) to X (leak point).

The process of determining the leakage position will be described with reference to the flowchart of FIG. The leakage position determination means 17 monitors the determination of the presence or absence of the flow rate signal by the flow rate signal determination means 18.

When the state in which the flow rate signal determining means 18 determines that the flow rate signal is "absent" continues for a predetermined time, for example, 30 minutes, by the timer 19, the timer 1
The leak sound is measured by the first leak sound detection sensor 7 and the second leak sound detection sensor 9 for a predetermined time, for example, 2 minutes, by 9.

Here, the first leak sound detecting sensor 7 and the second leak sound detecting sensor 7
When the leak sound detection sensor 9 detects the leak sound and the leak signal from the first leak signal transmitter 12 is input, it is determined whether or not the leak signal is a continuous signal.

If it is not a continuous signal, that is, if it is an intermittent signal, it is judged that leakage has occurred on the upstream side of the gas meter 8 between the pressure regulator 6 and the gas meter 8 as described above, and the indicator 15 is displayed. Is displayed to that effect.

On the other hand, if the signal is a continuous signal, it is determined that a leak has occurred between the gas meter 8 and the gas cylinder (gas container 2), and the leak position measurement mode is entered. In the leak position measurement mode, it is determined whether the leak position can be calculated. If the leak position cannot be calculated, the display unit 15 displays that the gas cylinder (gas container 2) is leaking. Here, the case where the calculation is impossible is, for example, the case where the calculated value of the leakage position becomes negative. On the other hand, if the calculation is possible, the above calculation is performed and the leak position is displayed on the display unit 15.

The flow signal is "present" by the flow signal judging means 18.
If it is determined that the state of the gas flow rate is continued, or if the state of being determined to be “presence” continues for a predetermined time by the timer 19, for example, 2 minutes, the state of the gas flow rate is determined and the flow rate is constant for 30 days. It is less than the amount, and it is judged whether the flow rate is constant. This is because the gas flow is generated even by using the igniter, and therefore the leak determination is performed only when the gas flow rate is less than a certain amount, for example, less than 21 l / h. That is, when igniting is used, there is a gas flow rate of a constant flow rate with a flow rate of less than 21 l / h.
If there is a flow rate of 1 / h or more, it is determined that the combustion appliance 3 is normally used or used in combination with igniting.
If the flow rate is less than the igniter flow rate less than h, it is determined that a minute leak has occurred.

When it is determined that the slight leak has occurred, the display unit 15 displays that the slight leak has occurred on the downstream side of the gas meter 8 and enters the leak position measurement mode. In the leak position measurement mode, the gas meter 8 described above is used.
Similarly to the determination of the leakage position on the upstream side of the, the display unit 15 determines whether the leakage position can be calculated.
A message indicating that there is a leak from the burner 3 is displayed on. On the other hand, if the calculation is possible, the above calculation is performed and the leak position is displayed on the display unit 15.

In the above embodiment, the leak position is automatically calculated when the gas leak is detected. However, the leak position is calculated by detecting the gas leak and displaying the indicator 17 on the display unit 17. When that is displayed on the screen, it may be configured to be performed based on an instruction from the outside. For example, the leak position determination means 17 or the like is not fixedly installed in the gas use facility, but a leak position determination device having the portable leak position determination means 17 or the like is separately provided, and the gas leak is displayed on the display 15. Only when the leak position is determined, the leak position determination device may be installed in the gas use facility to calculate the leak position.

Further, in the above-mentioned leakage determination, the leakage amount may be estimated by comparing the leakage signal with the pattern of the leakage signal stored in the reference leakage signal storage means 20.

In the leakage judgment when the flow rate signal is "present", the normal use or the leakage is determined by storing the ultrasonic waveform due to normal use or fire as a signal pattern and comparing it with the detected signal pattern. It is also possible to judge whether it is occurring.

Next, a case will be described in which a third leak sound detecting means is further added to the gas leak position detecting device 1 described above. The members having the same functions as those of the gas leak position detection device 1 described above are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 7, the gas leak position detecting device 35 is provided with a third leak sound detecting sensor 36 together with the gas meter 8, and the third leak sound detecting sensor 36 is passed through a third leak signal transmitter 37. Contact the microcomputer 11. In this case, the gas meter 8, the flow rate signal transmitter 14,
A microcomputer meter in which the microcomputer 11 and the like are integrated may be provided, and the third leak sound detection sensor 36 and the like may be built in this microcomputer meter.

As shown in FIG. 8, the third leak sound detection sensor 36 includes a storage means 21 and a leak position detection means 17 of the microcomputer 11 via a third leak signal transmitter 37.
I have contacted.

Then, the leak position of the gas on the upstream side of the gas meter 8 is judged by the first leak sound detection sensor 7 and the third leak sound detection sensor 35, and the second leak sound detection sensor 9 and the third leak sound detection are performed. The sensor 35 determines the leakage position on the downstream side of the gas meter 8. The method for determining the leakage and the method for detecting the leakage position are the same as those in the above-described embodiment, and thus the description thereof is omitted.

In the gas use facility using city gas, only the gas pipe is installed on the upstream side of the gas meter 8. Therefore, the first leak sound detecting sensor 7 is omitted and the gas leak is detected on the downstream side of the gas meter 8. It may be configured to detect only leaks.

[0047]

As described above, according to the present invention, the first leak sound detecting means is provided in the gas flow path upstream of the flow rate detecting means, and the second leak sound is provided in the gas flow path downstream of the flow rate detecting means. A detection unit is provided, and the leakage position calculation unit calculates the leakage position based on the difference between the arrival times of the leakage sounds detected by the leakage sound detection units, and displays the leakage position on the display unit.

Therefore, according to the present invention, the leakage of gas can be detected and the leakage position can be specified and displayed. Therefore, even if there is a long distance from the gas storage facility to the gas use facility and a gas leak occurs at a facility that is connected by a gas pipe buried underground between these, it is necessary to bury the gas to identify the leak location. You don't have to dig up the whole tube. For this reason, it is extremely easy and easy to find the leakage position, and it is possible to prevent a serious accident such as a gas explosion due to the gas leakage.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing a configuration of the present invention.

FIG. 2 is a schematic diagram showing an example of a mounting position of a leak sound detection sensor.

FIG. 3 is a schematic block diagram showing the configuration of a microcomputer that is a computing unit.

FIG. 4 is a side view showing the internal structure of the pressure regulator.

FIG. 5 is an explanatory diagram illustrating a method of measuring a leakage position.

FIG. 6 is a flowchart showing a procedure of leakage determination.

FIG. 7 is a schematic block diagram showing the configuration of another embodiment.

FIG. 8 is a schematic block diagram showing the configuration of a microcomputer that is a computing means in another embodiment.

[Explanation of symbols]

 1 Gas Leakage Position Detection Device 4 Gas Flow Path 7 First Leakage Sound Detection Sensor 9 Second Leakage Sound Detection Sensor 11 Microcomputer 36 Third Leakage Sound Detection Sensor

Claims (2)

[Claims] 1. A flow rate detecting means for detecting a flow rate of gas flowing through a gas flow path, a first leak sound detecting means provided in a gas flow path upstream of the flow rate detecting means, and a gas downstream of the flow rate detecting means. Contacting the second leak sound detecting means provided in the flow path, the first leak sound detecting means and the second leak sound detecting means,
And a display unit for displaying the leakage position calculated by the leakage position calculation unit, the leakage position calculation unit calculating the leakage position based on the difference in the arrival time of the leakage sound detected by each of the leakage sound detection units. Gas leak position detection device. 2. A flow rate detecting means for detecting a flow rate of the gas flowing through the gas flow path, a first leak noise detecting means provided in a gas flow path upstream of the flow rate detecting means, and a gas downstream of the flow rate detecting means. Second leak sound detecting means provided in the flow path, third leak sound detecting means provided in the gas flow path near the flow rate detecting means, first leak sound detecting means, second leak sound detecting means, and third leak A display that communicates with the sound detecting means and calculates the leak position based on the difference in the arrival time of the leak sound detected by each leak sound detecting means, and a display that displays the leak position calculated by the leak position calculating means. A gas leakage position detecting device comprising: