JPH11173940A - Method and device for acoustically detecting leakage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the operational reliability of a plant by preventing malfunction of an acoustic leakage detector by realizing such a leakage monitoring function that is sensible to the occurrence of bubbles in an SG container without responding to the waveform variation of received acoustic waves caused by the operating condition. SOLUTION: The acoustic leakage detecting device is composed of transmitting sound sensors 11t and 12t and receiving sound sensors 11a, 11b, 12a, and 12b installed to the barrel 7 of an SG container, an acoustic wave generation controller 200, and a leakage detector 300. Thereby, the reliability of the operation, etc., of a plant can be improved because such leakage detection that is sensible to the variation of noise, etc., and to the occurrence of bubbles in the SG container becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention monitors the change in the sound propagation characteristic of a medium in a monitoring area by using a transmission signal of a transmission acoustic sensor and a detection signal of a reception acoustic sensor installed around the monitoring area. In particular, the present invention relates to an acoustic leakage detection method and apparatus suitable for capturing, with high sensitivity, the generation of bubbles generated in a medium due to leakage.

[0002]

2. Description of the Related Art JP-A-62-115358 discloses that
Using a transmission acoustic sensor that transmits ultrasonic waves into the liquid that is the monitoring medium, and a set of reception acoustic sensors that receive sound that has passed through the liquid, using the output of the transmission acoustic sensor to determine the presence of bubbles in the liquid, A method of detecting by an ultrasonic attenuation measurement device using a received acoustic sensor output is disclosed. In another example, Japanese Unexamined Patent Application Publication No. 9-5203 discloses that a sound is intermittently transmitted into a liquid, and a reception acoustic waveform corresponding to the previous transmission among the acoustic waves received in response to the transmission and a transmission immediately after the reception. A method is disclosed in which an integrated value of a difference between corresponding received acoustic waveforms is obtained, and when the integrated value of the difference exceeds a set value, it is determined to be leakage.

In the above other example, since the average value of the difference between the received acoustic waves is generally zero, the integrated value should also be generally zero. It is estimated to be. Although no specific device configuration is disclosed for this other example, the concept of detecting the presence or absence of leakage from the difference between the received acoustic waveform corresponding to the previous transmission and the received acoustic waveform corresponding to the immediately following transmission is shown. .

Reference (“Detection of water leak of FBR steam generator by active acoustic method”: Atomic Energy Society of Japan, 1996
A fall meeting G55) discloses a method of monitoring a time zone in which a change in sound pressure becomes large when a bubble is generated by one received acoustic wave.

In the above-described method of transmitting an acoustic wave into a liquid in a monitoring area and detecting a change in a received acoustic wave transmitted through the monitoring area to determine whether or not there is a leak, the liquid is generally contained in some kind of container. The acoustic sensors for transmission and reception are often mounted directly on the container wall. For this reason, the received acoustic wave is always detected by superimposing an acoustic wave that goes around the container wall (hereinafter referred to as “wraparound wave”) and an acoustic wave transmitted through and propagated in the liquid (hereinafter referred to as “transmitted wave in liquid”). Will be.

What is affected by bubbles generated in the liquid is a transmitted wave in the liquid that propagates through a bubble region in the liquid among the received acoustic waves. In order to propagate ultrasonic waves in the monitoring area and detect the attenuation of the ultrasonic waves due to the presence of bubbles in the monitoring area, it is necessary to grasp the presence or absence of the attenuation of the transmitted wave in the liquid.

However, the received acoustic wave itself includes a wraparound wave of the transmitted acoustic wave, a transmitted wave in liquid, and noise.
Sneaking waves and noise change even when no bubbles are generated. The causes include a change in the acoustic sensor attachment state, a change in environmental noise inside and outside the SG, a change in the SG sound propagation characteristics due to a temperature change due to a change in operating conditions, and the like.

The mere comparison of the difference between the transmitted acoustic wave and the received acoustic wave disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Sho 62-115358 cannot discriminate whether the received acoustic wave has changed due to the presence or absence of leakage or the change due to other factors. , Sometimes difficult.
Japanese Patent Application Laid-Open No. 9-5203 discloses a method of calculating a difference between a previously transmitted acoustic wave and a received acoustic wave corresponding to the immediately following transmitted acoustic wave. Is zero, so it is zero irrespective of the presence or absence of leakage, which is not applicable in this case.

A time zone sensitive to the occurrence of leakage of the received acoustic waveform disclosed in the above-mentioned document (“Detection of water leak of FBR steam generator by active acoustic method”: Atomic Energy Society of Japan, Autumn Meeting G55, 1996). In the monitoring method, the time zone sensitive to the occurrence of the leak differs depending on the location of the leak.
Not applicable if the location of the leak is unknown. That is, there is no mention of a device for discriminating whether the received acoustic wave has changed due to the presence or absence of leakage or a change due to other factors. As described above, in the above-described related art, in order to prevent a malfunction of the leak detection, a measure for reducing the detection sensitivity with respect to a change in a factor other than the leak of the received acoustic wave has not been sufficiently considered.

[0010]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for detecting the presence of air bubbles due to leakage in a liquid by transmitting a transmission acoustic wave into the liquid and detecting the leakage sound. It is an object of the present invention to provide a highly reliable acoustic leak detection method and apparatus which lowers the sensitivity in the case of a change other than the leak and prevents malfunction.

[0011]

In order to achieve the above object and to realize a highly reliable leak detection method with less malfunctions, the present invention uses the following two means.

(1) A step of estimating a wraparound wave generated by generation of a transmission acoustic wave, a step of estimating a transmitted wave in liquid from a received acoustic wave and an estimated wraparound wave, and setting a set value having a magnitude of the transmitted wave in liquid. If it changes beyond this, it is determined to be a leak. More specifically, the transfer characteristics of the looping wave on the wall are determined in advance, the looping wave is estimated from time to time, and the transmitted wave in the liquid is estimated from the received acoustic wave and the looping wave. When the transmitted wave changes beyond a certain set value, it is determined as leakage.

(2) A step of calculating a difference between detection waveforms of the reception acoustic waveforms before and after corresponding to the intermittently generated transmission acoustic wave, and calculating a time change (fluctuation) of the difference between the reception acoustic waveforms before and after. And a step of determining leakage when the fluctuation exceeds a certain set value and becomes large.

[0014]

In the leak detection, it is the transmitted wave in the liquid that propagates in the bubble region in the liquid that is greatly affected by the bubbles due to the occurrence of the leak. For this reason, due to the occurrence of leakage, the transmitted wave component in the liquid greatly changes as compared with the loop wave component propagating from the transmission point to the SG container wall. For this reason, monitoring the transmitted wave in liquid is relatively strong against disturbance such as noise.

As is clear from the literature of the conventional example,
Even if leakage occurs, the change of the received acoustic wave is slight, and it can be seen that the wraparound wave is relatively larger. For this reason, by extracting the transmitted wave component in the liquid and performing the leakage determination by evaluating the amplitude of the transmitted wave component in the liquid, it is possible to make it less likely to be affected by changes in factors other than the leakage.

By taking the difference between the waveforms before and after the detection signal of the received acoustic wave generated intermittently and monitoring the magnitude of the time fluctuation of the magnitude of the difference, noise such as noise due to a change in operating conditions in the actual machine is obtained. It is less susceptible to change and can selectively detect true leaks.

The detection signal of the received acoustic wave is used because, in signal processing, handling in evaluation of the magnitude of the difference is easier than using the acoustic signal as it is. The magnitude of the difference between the waveforms of the detection signals before and after the received acoustic wave fluctuates positively or negatively regardless of whether or not there is leakage. Therefore, in the present invention, instead of monitoring the magnitude of the difference, the leakage is detected by monitoring the time change, that is, fluctuation of the magnitude of the difference. As a result, it does not respond to a gradual change in received sound due to a change in driving conditions, etc., but responds to a relatively fast change corresponding to the complicated behavior of bubbles caused by leakage in the sound propagation path. A variation in received acoustic signal can be detected selectively.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described. FIG. 1 shows an acoustic leak detection method and apparatus according to the present invention using an SG (steam generator) of a fast breeder reactor power plant.
This is an example of application to water leak monitoring.

In FIG. 1, transmission acoustic sensors 11t and 12t are arranged on the outer wall of the SG container body 7, and the reception acoustic sensors 1t are located near the transmission acoustic sensors 11t and 12t, respectively.
The receiving acoustic sensors 11b and 12b are respectively set apart from each other in the direction opposite to the transmitting acoustic sensors 11t and 12t. For the sound, the acoustic wave generation controller 200 intermittently generates an electric signal and transmits the electric signal.
It is converted into an acoustic wave at 1t and 12t and sent out into the SG container. The acoustic wave arriving intermittently is received by the receiving acoustic sensor 11.
a, 11b, 12a, and 12b, and converts them into electric signals. In the leak detector 300, the reception acoustic sensor 11a,
The presence / absence of a leak is detected from the presence / absence of a change in the received acoustic wave characteristic of the leak, mainly using the output signals of 11b, 12a and 12b.

Here, sodium, which is a high-temperature fluid, and water, which is a low-temperature fluid, pass through the SG container body 7. The water passes through the water supply inlet pipe 2, passes through the heat transfer pipes 3, which are spirally arranged in multiple layers, and is guided from the steam outlet pipe 4 to the outside of the SG container body 7. On the other hand, sodium is supplied from the sodium inlet pipe 6 through S
It enters the G container body 7 and is guided out of the SG container body 7 through the sodium outlet pipe 8. The heat transfer tube 3 through which water passes is spirally SG
It is installed inside the container body 7 and is supported by the pipe support 5.

That is, sodium and water are separated by the wall of the heat transfer tube 3 inside the SG container body 7. Sodium pressure during reactor operation is not much different from atmospheric pressure,
The water inside the heat transfer tube 3 has a high pressure. For this reason, when a minute crack or the like is formed in the heat transfer tube 3, water leaks to the sodium side. At this time, water is blown out and chemically reacts with sodium to generate hydrogen bubbles.

Due to the generation of the hydrogen bubbles, the propagation attenuation of the transmitted wave in the liquid propagating inside the SG container increases. In the present invention, the presence or absence of leakage is known from the change in sound propagation attenuation due to the generation of hydrogen bubbles at the time of leakage.

In FIG. 1, the receiving acoustic sensors 11a, 1
The reception acoustic waves detected by 1b, 12a, and 12b are mainly superpositions of two waves: a wraparound wave of the SG container wall and a transmitted wave in liquid propagating inside the SG container. Of these two waves, the wraparound wave on the SG container wall is hardly affected by the presence or absence of leakage. On the other hand, transmitted waves in liquid are affected by hydrogen bubbles generated by leakage. For this reason, the transmitted wave in the liquid is selected from the received acoustic waves, and the change in only the transmitted wave in the liquid is captured, so that it is less affected by disturbance such as unnecessary noise.

Therefore, the transmission acoustic sensors 11t and 12t
Reception acoustic sensors 11a and 1
2a and the detection signals of the receiving acoustic sensors 11b and 12b which are separately installed in the facing direction to estimate the transmitted wave in the liquid and detect the presence or absence of leakage from the estimated transmitted wave in the liquid with high reliability. This is a feature of the present embodiment.

FIG. 2 shows an internal configuration of the acoustic wave generation controller 200 and the leak detector 300 which are main parts of the present invention. The acoustic wave generation controller 200 includes a sound transmission timing controller 2
11 and a transmitter 212. The leak detector 300 is
Amplifiers 311 and 312, detector 313, wraparound wave estimator 314, deviation extractor 315, low-pass filter 316
And a leak determiner 317. In addition, in order to make it easy to explain, the SG container is a simple expression in which illustration of the internal equipment is omitted.

An electric signal is intermittently transmitted from the sound transmission timing controller 211, converted into an ultrasonic wave by the transmission acoustic sensor 11t, and propagated into the SG container. In the reception acoustic sensor 11b, a wraparound wave wrapping around the container wall and a transmitted wave in liquid propagating in the liquid inside the container are synthesized and detected. FIG. 3 shows an example of the transmission waveform S10 of the transmitter 212, the received acoustic wave S20 at the time of no leakage, and the received acoustic wave S20 at the time of leakage. Although an electric signal is generated for a short time, an acoustic wave has a complicated waveform due to multiple reflections caused by propagation in a complex system.

Also, even if a leak occurs, only the transmitted wave in the liquid that propagates in the liquid is greatly affected, so that the change of the received acoustic wave in which the wraparound wave and the transmitted wave in the liquid are superimposed is very small. . By repeatedly generating the transmission acoustic wave of FIG. 3, temporally continuous leakage monitoring is realized. In FIG. 2, the output of the receiving acoustic sensor 11 b installed opposite to the transmitting acoustic sensor 11 t passes through the amplifier 312 and the detector 313,
It is input to the deviation extractor 315.

On the other hand, the output of the receiving acoustic sensor 11a installed near the transmitting acoustic sensor 11t passes through the amplifier 311 and
The signal is input to the wraparound wave estimator 314, outputs the estimated detection waveform of the wraparound acoustic wave, and is input to the deviation extractor 315. Here, since the acoustic wave detected by the receiving acoustic sensor 11a is installed near the transmitting acoustic sensor 11t, it is strongly affected by the transmitting wave. Therefore, by using the transfer characteristics between the acoustic sensors 11a and 11b measured in advance, it is possible to estimate a wraparound wave that is not strongly affected by the presence or absence of leakage.

The wraparound wave estimator 314 calculates the temperature of the acoustic sensor installation height from the feedwater inlet / outlet temperature and the sodium inlet / outlet temperature, and refers to the transfer characteristic for the wraparound wave estimation according to the operation state. . Deviation extractor 3
In 15, the estimated waveform S40 of the loop wave and the received acoustic wave S
From 30, the transmitted wave level S50 in the liquid is estimated by the equation (1). Since the received acoustic wave S30 is the square root of the sum of squares of the wraparound wave S40 and the transmitted wave S50 in the liquid, this relationship is calculated by back calculation.

[0030]

(Equation 1)

Here, tp is the number of transmissions of the transmitted acoustic wave, τ is the time based on the transmission start time, and T is the time width of the acoustic signal targeted for leak detection.

The output S60 of the low-pass filter 316 is
It is a time average of the estimated level S50 of the transmitted wave in liquid.
The leak determiner 317 determines that a leak has occurred when the magnitude of the amplitude exceeds a set value. The reason for taking the absolute value of the integral value in the square root in the equation (1) is to avoid a situation where the square root becomes negative and the calculation cannot be performed.

As a specific method for estimating the wraparound wave of the container wall, there are a method using a neural network, a method using a Green's function, and other function approximation methods. In this embodiment, a method based on function approximation is employed.

A received acoustic wave for a transmitted acoustic wave is measured in advance for each operating condition such as temperature, and the output of one received acoustic sensor is estimated from one received acoustic sensor by function approximation based on the measured values. . That is, from the reception acoustic wave of the reception acoustic sensor 11a having a small influence of the transmitted wave in the liquid,
The output of the reception acoustic sensor 11b is estimated and subtracted from the actual output of the reception acoustic sensor 11b to obtain a change in the transmitted wave in the liquid with high sensitivity. The detector 313, the deviation extractor 315, and the low-pass filter 316 can be realized by applying general analog circuit technology or digital circuit technology.

In the neural network method, similarly to the case of the function approximation, the receiving acoustic sensor 11 is used by using the learning function of a so-called multilayer neural network.
The output of the reception acoustic sensor 11b is estimated by learning from the reception acoustic wave of a. The method using the Green's function obtains the transfer characteristics of the received acoustic wave of the received acoustic sensor 11a and the output of the received acoustic sensor 11b in advance, and calculates the wraparound wave from the received acoustic wave of the received acoustic sensor 11a based on the transfer characteristics. It is a method of estimating.

The operation of the leak detector of this embodiment will be described with reference to FIGS. FIG. 4 shows a waveform of a main part at the time of no leakage. For the electrical transmission waveform shown in FIG.
The output signal S20 of the amplifier 312, which is a received acoustic waveform, is
The waveforms are completely different as shown in the upper part of FIGS.
This is because the acoustic wave output from the transmitting acoustic sensor 11t is
In the process of propagating from the SG container wall surface to the reception acoustic sensor 11b, reflection, scattering, and refraction are repeated, and a superimposed waveform results in a waveform completely different from an electric signal. The detection signal S30 is obtained by passing the received acoustic wave through the detector 313.

On the other hand, the wraparound wave estimator 314 outputs a detection signal S40 of the wraparound wave propagating through the SG container wall, which is estimated from the acoustic signal of the reception acoustic sensor 11a. Sneak wave detection signal S40 and reception acoustic wave detection signal S3
The difference of 0 is not large. The signal at the bottom of FIG. 4 is the square root of the square difference between the detection signals of the loop wave and the reception acoustic wave, and corresponds to the detection waveform of the transmitted wave in liquid. This transmitted wave in liquid is calculated in the process of the internal calculation of the deviation extractor 315, and is shown for explanation.

On the other hand, when leakage occurs, the received acoustic waveform slightly changes as shown in FIG. The output of the detector 313 at this time is a detection signal S30 shown in the figure. The output signal of the loop interference estimator 314 is S40. S3
The detection waveform of the transmitted wave in liquid, which is the square root of the square difference between 0 and S40, is shown at the bottom of the figure. From the signal waveforms at the bottom of FIGS. 4 and 5, the signal waveform difference depending on the presence or absence of leakage is clear. Since the output of the deviation extractor 315 is the integrated value of the signal waveform at the lowermost stage in FIGS. 4 and 5 as shown by the equation (1), the output of the leak extractor 315 in FIG. If so, its output will be small.

FIG. 6 illustrates the manner of determining leakage. In the figure, the upper part shows a change in the case where the reception acoustic wave S20 has leaked from a state where no leak has occurred. In response, the level of the output S50 of the deviation extractor 315 also changes, and the output S60 of the low-pass filter 316 also changes as shown.
The leak determiner 317 determines that a leak has occurred when the signal S60 has changed beyond a set value.

In the first embodiment, the difference between the received sound signals is evaluated by the equation (1). However, the difference can be evaluated by a simple difference or a difference obtained by weighting according to the time τ.

As described above, in the first embodiment, by providing a wraparound wave estimating mechanism, only a submerged transmitted wave which is directly affected by the propagation attenuation accompanying leakage is extracted and used for leakage determination. Therefore, it is difficult to receive the fluctuation of the loop wave at the normal time, and it is possible to prevent the malfunction of the leak detection. In addition, erroneous operation of leak detection can be prevented by taking in operating condition data, which is a factor that influences the estimation accuracy of the loop interference, and increasing the estimation accuracy of the loop interference under various operating conditions. As an effect peculiar to the present embodiment, by using a plurality of reception acoustic sensors, not only a change in SG acoustic propagation characteristics due to operating conditions, but also a change in a transmission electric signal and a change in the installation state of the transmission acoustic sensor can be corrected.

FIG. 7 shows a second embodiment. This second embodiment is also an example in which the acoustic leak detection method and device of the present invention are applied to the monitoring of water leaks from the SG of a fast breeder reactor power plant. In the first embodiment, it is necessary to evaluate in advance the transfer characteristics of the loop wave in a typical operating state and to measure the received acoustic wave in a normal state, but in the present embodiment, these advance preparations are unnecessary. It is characteristic.

In order to provide these characteristics, an acoustic wave is intermittently transmitted into a liquid, and a received acoustic waveform corresponding to the Nth previous transmission among the acoustic waves received in response to the transmission, and a current received acoustic waveform. Of the detected waveforms, and when the effective value of the fluctuation of the difference exceeds a set value, it is determined to be a leak. This is because, during normal operation, sodium is stably present inside the SG container, but when leakage occurs, hydrogen bubbles are mixed in the sodium, and the high-pressure water ejected from the bubbles is disturbed, and the mixing state is changed. It fluctuates in time and place. For this reason, when leakage occurs, the sound propagation characteristics of the SG container fluctuate with time, and the leakage is detected by capturing this time fluctuation.

FIG. 7 shows the internal configuration of the acoustic wave generation controller 200 and the leak detector 300 which are the main parts of the present embodiment.
The acoustic wave generation controller 200 includes a sound transmission timing controller 211 and a transmitter 212. The leak detector 300 includes an amplifier 312, a detector 313, and an N-stage shift register 33.
1, a deviation extractor 315, a fluctuation calculator 332, and a leak determiner 317.

An electric signal is intermittently transmitted from the sound transmission timing controller 211, converted into an ultrasonic wave by the transmission acoustic sensor 11t, and propagated into the SG container. The output of the receiving acoustic sensor 11b installed facing the transmitting acoustic sensor 11t passes through the amplifier 312 and the detector 313 and is input to the deviation extractor 315.

The delay circuit 331 stores the reception acoustic detection waveform and outputs a detection signal delayed by one pulse. The deviation extractor 315 calculates a difference between the detection signal S30 of the received acoustic wave and the detection signal S41 of the immediately preceding received acoustic wave, and outputs a difference signal S51 as a result. The operation formula of S51 adopted here is shown below.

[0047]

(Equation 2)

The difference signal is converted into an amplitude by the fluctuation calculator 332. The fluctuation calculator 332 has a function of calculating the effective value of the difference signal S51. In the leak determiner 317, when the magnitude of the fluctuation becomes larger than the set value,
Judge as a leak.

As described in the item of operation, when leakage occurs inside the SG, the hydrogen bubbles are disturbed by the leaked high-pressure water and sodium flow, and the amount of the local hydrogen bubbles inside the SG is relatively high. Changes to On the other hand, a change in the received acoustic signal due to a change in the driving conditions is a gradual change. According to the present embodiment, in which the magnitude of the difference between the front and rear reception acoustic waves is fluctuated, the reception acoustic signal is differentiated from the viewpoint, and the sensitivity to the change of the reception acoustic wave due to leakage is increased.

In this embodiment, the difference between the received acoustic signals is evaluated by the equation (2). The difference between the square root of the squared difference and the weights according to the time τ is applied to both the detected signals. It can also be evaluated by a calculation method. Further, in the present embodiment, the difference between the detection signals of the continuous reception acoustic waves is obtained, but the same effect can be expected even if the difference between the reception acoustic waves separated by two or more is obtained.

As an effect peculiar to the second embodiment, the pre-installation preparation as in the first embodiment becomes unnecessary, and since the fluctuation factor of the wraparound wave is slow in time, it is positive to remove it. There is no need to take appropriate measures, which is economically advantageous.

[0052]

As described above, in the method of detecting the leak by transmitting the acoustic wave into the liquid to detect the presence of the air bubbles accompanying the leak in the liquid, the sensitivity when the received acoustic wave changes except for the leak. As a result, there is an effect of improving the reliability of the leak detection device.

[Brief description of the drawings]

FIG. 1 is an FBR of an acoustic leak detection method and apparatus according to the present invention.
-Application example of SG to heat transfer tube leak monitoring device.

FIG. 2 is a block diagram of an acoustic leak detection device according to a first embodiment of the present invention.

FIG. 3 is a time chart example of a transmission wave and a reception acoustic wave.

FIG. 4 is a time chart showing a signal waveform of a main part in a normal state.

FIG. 5 is a time chart showing a signal waveform of each part at the time of leakage.

FIG. 6 is a time chart showing signal waveforms at various parts when the state changes from normal to leakage.

FIG. 7 is a block diagram of an acoustic leak detection device according to a second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... SG (steam generator) 7 ... SG container body 11t, 12t ... Transmission acoustic sensor 11a, 11b, 12a, 12b ... Reception acoustic sensor 200 ... Acoustic wave generation controller 211 ... Sound transmission timing controller 212 ... Transmitter 300 ... Leakage detector 311, 312 ... Amplifier 313 ... Detector 314 ... Loop wave estimator 315 ... Deviation extractor 316 ... Low-pass filter 317 ... Leakage determiner 331 ... Delay circuit 332 ... Fluctuation calculator

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takayuki Ishida 3-1-1, Sakaicho, Hitachi City, Ibaraki Prefecture Inside Hitachi, Ltd. Hitachi Plant

Claims (6)

[Claims] Claims: 1. A monitoring target area through which different media flow through pipes disposed inside a tower and tanks and the tower and tanks, respectively.
An acoustic wave is propagated from a transmitting acoustic sensor installed on the outer wall of the tower, and the propagated acoustic wave is received by a receiving acoustic sensor installed on the outer wall of the tower, and a change in the received acoustic wave is captured to form the pipe. In an acoustic leak detection method for detecting bubbles generated due to leakage of a medium from the tower to the tanks, receiving acoustic sensors are installed at a plurality of points on the outer wall of the tower,
From the receiving acoustic sensor adjacent to the transmitting acoustic sensor to the receiving acoustic sensor facing the transmitting acoustic sensor, a receiving acoustic wave mainly composed of a wraparound wave transmitted through the outer wall of the tower is estimated, and the estimated receiving acoustic wave is estimated. Calculates the difference between the respective detected signals of the received acoustic wave of the receiving acoustic sensor facing the transmitting acoustic sensor and the magnitude of the difference mainly containing the transmitted wave in the liquid in the medium and the normal value at the time of no leakage. An acoustic leak detection method characterized by detecting the presence or absence of a leak from a comparison with a set value. 2. A monitoring target area through which a different medium flows through a pipe disposed inside the tower and the tank and the tower and the tank,
An acoustic wave is propagated from a transmitting acoustic sensor installed on the outer wall of the tower, and the propagated acoustic wave is received by a receiving acoustic sensor installed on the outer wall of the tower, and a change in the received acoustic wave is captured to form the pipe. In the acoustic leak detection method for detecting air bubbles generated due to leakage of a medium from the apparatus to the towers, intermittently transmitting an acoustic wave, calculating a difference in a detection signal between intermittently received acoustic waves, An acoustic leak detection method characterized by detecting the presence or absence of a leak by comparing the magnitude of the difference with a set value that is a normal value at the time of no leak. 3. A monitoring target area through which different media flow through a pipe disposed inside the tower and the tank and the tower and the tank, respectively.
An acoustic wave is propagated from a transmitting acoustic sensor installed on the outer wall of the tower, and the propagated acoustic wave is received by a receiving acoustic sensor installed on the outer wall of the tower. In an acoustic leak detection device that detects bubbles generated due to leakage of a medium to towers, means for transmitting an acoustic wave to a monitoring target, means for synchronously receiving the propagated sound at a plurality of points, Means for estimating a wraparound wave of the other reception acoustic sensor from one reception acoustic sensor, and means for detecting a difference between the estimated reception wave and the detection reception wave,
Means for determining leakage from the magnitude of the difference. 4. The method according to claim 1, wherein the magnitude of the difference is determined by the estimated reception wave.
4. The method according to claim 3, wherein a difference between square values of the detected signals of the detected reception wave is integrated and represented by a square root of an absolute value.
3. The acoustic leak detection device according to claim 1. 5. A monitoring target area through which a different medium flows through a pipe disposed inside a tower and tanks and the tower and tanks,
An acoustic wave is propagated from a transmitting acoustic sensor installed on the outer wall of the tower, and the propagated acoustic wave is received by a receiving acoustic sensor installed on the outer wall of the tower. An acoustic leak detection device for detecting air bubbles generated due to leakage of a medium into towers, means for intermittently transmitting sound to a monitoring target, means for synchronously receiving the propagation sound thereof, Means for calculating the difference between the previous received acoustic wave and the current received acoustic wave by more than one unit, means for calculating the temporal variation of the difference, and comparing the magnitude of the temporal variation of the difference with the set value. An acoustic leak detection device comprising means for determining a leak. 6. The acoustic leak detection device according to claim 5, wherein the magnitude of the difference is represented by an effective value of an integral value of a difference between detection signals of received acoustic waves before and after the one or more separated acoustic waves.