JP5739315B2 - Ultrasonic leak detection device and method - Google Patents

Description

  The present invention relates to an ultrasonic leak detection device and method thereof, and particularly suitable for detecting leakage of a liquid by immersing an ultrasonic sensor in a medium such as a liquid and using a reflection signal from an object in the liquid. The present invention relates to an ultrasonic leak detection apparatus and method.

  When a tank or the like provided in the basement is filled with turbid water or a liquid with low transparency, in order to stop and repair the leakage of this liquid, it is necessary to detect the leakage of the liquid and identify the leakage location. Necessary.

  Generally, as a method for inspecting leakage of liquid from a container containing liquid to another container, a method for visually confirming the leaking substance, or a characteristic property of the leaking substance (for example, salt, chemical, ph, etc.) There are known methods for detecting leakage by measuring chemical properties, electrical conductivity, resistance, physical properties such as temperature and radiation dose).

  Moreover, as a method using the physical property (radioactive substance) contained in the leaking substance, for example, as described in Patent Document 1, the radiation from the radionuclide contained in the main steam or the reactor water is detected and analyzed. There are known methods for detecting leaks.

  However, although the above-described prior art can determine the presence or absence of leakage with respect to the entire container, it is difficult to specify the leakage location. Usually, since leak detection requires sampling of gas (gas), it is not possible to detect leakage of liquid from a container filled with liquid to another container.

  Further, as another method for directly measuring the leakage, the leakage location can be identified by visualizing the flow of liquid sucked into the leakage location (or the flow of liquid flowing out if it is a leakage destination).

  However, in the case where the liquid contained in the container is an opaque liquid such as turbid water, it is difficult to visualize the flow of the leaked portion by an optical method. As a method when visualization by an optical method is difficult, there is a method (flow meter) for directly measuring a flow using ultrasonic waves or the like.

  Moreover, as a method of measuring the flow rate of the liquid with an ultrasonic sensor immersed in the liquid, for example, as described in Patent Document 2, a plurality of ultrasonic sensors are arranged so that a plurality of side lines can be obtained. A method for measuring the current is known.

  When the technique described in Patent Document 2 is applied to leakage detection, it is possible to measure the flow rate of the liquid that fills a closed space such as a water channel, so that it is possible to measure the distribution and change of the flow velocity that leads to leakage. The location cannot be specified.

  As a method of indirectly measuring the flow of a liquid, a method of measuring the flow indirectly by measuring the movement of an object with properties that follow the flow, such as tracers of fine particles and bubbles, and thin threads. It has been known.

  For example, as described in Patent Document 3, a method for measuring a flow velocity and a flow rate from an ultrasonic signal reflected by bubbles and particles in a fluid is known. However, even with this method, it is possible to measure the distribution and change of the flow velocity leading to the leakage, but it is not possible to identify the leakage location.

  On the other hand, in order to evaluate the soundness of the structure, an ultrasonic flaw detection method is widely used as a nondestructive inspection method for the surface and the inside of the structure. As one of the ultrasonic flaw detection methods, a liquid such as water or machine oil that can propagate ultrasonic waves is filled as an intermediate medium between the ultrasonic sensor and the subject, and the structure is inspected via the medium. Ultrasonic flaw detection is applied. For example, when water is used as an intermediate medium, it is called as a water immersion method.

  In this water immersion method, by using the liquid in the container as a medium, it is possible to visualize the shape change part (for example, a hole or a crack) of the outer wall by the reflected wave from the outer wall of the container filled with the liquid. However, liquid leakage cannot be confirmed.

JP 2011-13770 A JP 2011-122831 A JP 2011-185602 A

  As described above, in the above-described prior art, there is a problem that it is difficult to specify whether or not the liquid leaks from the container to other containers and the like in a container filled with turbid water or a liquid with low transparency. there were.

  The present invention has been made in view of the above-mentioned points, and the object of the present invention is whether or not there is leakage of liquid from a container containing turbid water or low-transparency liquid to another region. It is an object of the present invention to provide an ultrasonic leak detection apparatus and method capable of determining and specifying a leak location.

  In order to achieve the above object, an ultrasonic leak detection device of the present invention uses an ultrasonic sensor that is partially or wholly immersed in a liquid contained in a container, and is ultrasonically transmitted and received from within the container. In the ultrasonic leak detection device for detecting leakage of a liquid by transmitting an ultrasonic wave and receiving a reflected wave from a reflector in the container, means for generating a plurality of bubble groups in the container; Means for visualizing the structure in the container and the bubble group from the ultrasonic reception signal, and means for measuring a temporal change in the distribution of the bubble group from the visualization result of the bubble group; It is characterized by.

  According to the present invention, ultrasonic waves are transmitted from the ultrasonic transmission / reception means into the container, and the position of the shape changing portion (hole, crack, etc.) that may leak is reflected by the reflected wave from the structure in the container. In addition, by measuring the temporal change in the distribution of bubbles generated in the container, leakage occurs from the flow of the water flow accompanying the leakage and the shape-changing part that may leak. By visualizing the water flow, it is possible to identify the presence or absence of a leak and the location of the leak.

  Further, the bubble generating means may be provided with means for controlling the time for generating bubbles and the time for stopping the generation.

  According to the present invention as described above, when bubbles are continuously generated, the container is filled with bubbles, thereby avoiding the phenomenon that it is difficult to specify the presence or absence of leakage and the location of the leakage, and the possibility of leakage After discovering a certain shape change part, by generating a certain amount of bubbles for a certain period of time, it is possible to easily identify the presence or absence of a leak and the location of the leak by making it easier to capture the temporal change of the bubble group. .

  Moreover, you may provide the means to transmit the synchronizing signal synchronized with bubble generation.

  According to the present invention, after generating bubbles, the generation of bubbles is used as a trigger for starting measurement of a group of bubbles, and thereafter, the synchronization signal based on the sound is used as a trigger signal for measurement at a certain time interval. Thus, it is possible to observe the temporal change of the time change of the bubble group, and it is possible to easily identify the presence or absence of the leakage and the leakage location.

  Further, the synchronization signal may be provided with means for using the synchronization signal as an acoustic signal.

  According to the present invention, the position where the bubble is generated can be specified by the sound emitted from the bubble generating means in the liquid with low transparency, the position of the bubble generating means can be confirmed, The liquid flow in the vicinity of the generating means can be observed, and the leakage location can be easily identified.

  Furthermore, in order to achieve the above object, the ultrasonic leak detection method of the present invention uses an ultrasonic sensor that is partly or wholly immersed in a liquid contained in a container to generate ultrasonic waves from the container. In the ultrasonic leak detection method for transmitting and detecting the leakage of the liquid by receiving the reflected wave from the reflector in the container, from the received signal of the ultrasonic wave, the structure in the container The shape is visualized, and the leakage of the liquid is measured from the temporal change in the distribution of the plurality of bubble groups generated in the container.

  According to the present invention, in a container or the like filled with turbid water or a liquid with low transparency, the possibility of leakage due to the reflected wave from the structure in the container is obtained by using the signal from the reflector by the ultrasonic wave. The shape and position of a certain shape change part (hole, crack, gap) can be specified, and further, the amount of change over time of this bubble group (by generating bubbles temporarily or intermittently in the container) ( For example, by measuring the volume of the spread, the position of the center of gravity, the speed, etc.), measuring whether the liquid is sucked into the shape-changing part that may leak or whether it shows a change leading to leakage Thus, it is possible to specify the presence / absence of the leakage and the leakage position.

It is a figure which shows the ultrasonic leak detection system using one Example of the ultrasonic leak detection apparatus of this invention. It is a figure which shows the ultrasonic type leak detection system using the other Example of the ultrasonic type leak detection apparatus of this invention. It is a figure which shows the time change of the trigger signal and bubble generation amount of a bubble generation by the bubble generator employ | adopted as the ultrasonic leak detection apparatus of this invention. The bubble generation trigger signal by the bubble generator adopted in the ultrasonic leak detection device of the present invention and the time variation of the bubble generation amount are shown, and the state of the bubble is measured by the ultrasonic measuring device at regular time intervals after the bubble is generated. It is a figure for demonstrating what to do. It is a figure which shows the state which is measuring the bubble with the ultrasonic measuring device employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure which shows an example of the ultrasonic visualization apparatus employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure which shows the other example of the ultrasonic visualization apparatus employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure for demonstrating the measurement of the shape by the ultrasonic visualization apparatus employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure for demonstrating the measurement of the shape by the ultrasonic visualization apparatus employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure which shows the state which is measuring the bubble with the ultrasonic measuring device employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure which shows the example of the process result which extracts the volume of the bubble group by the image process in the ultrasonic leak detection apparatus of this invention. It is a figure which shows an example of the measurement result of the physical quantity of a bubble group using the process result which extracted the volume of the bubble group of FIG. 11 by image processing. It is a figure which shows the other example of the measurement result of the physical quantity of a bubble group using the process result which extracted the volume of the bubble group of FIG. 11 by image processing. It is a figure which shows the further another example of the measurement result of the physical quantity of a bubble group using the process result which extracted the volume of the bubble group of FIG. 11 by image processing. It is a figure which shows the further another example of the measurement result of the physical quantity of a bubble group using the process result which extracted the volume of the bubble group of FIG. 11 by image processing. It is a figure which shows the structure of the ultrasonic measuring device employ | adopted for the ultrasonic leak detection apparatus of this invention. It is a figure which shows the structure of the bubble generation apparatus employ | adopted for the ultrasonic leak detection apparatus of this invention, an ultrasonic measuring device, and an access jig. It is a flowchart which shows one Example of the ultrasonic leak detection method of this invention. It is a figure which shows the time change of the expansion | swelling of a bubble group in case a bubble is taken out in multiple times. It is the figure which attached the sound source of an acoustic generation to the bubble generation apparatus employ | adopted as the ultrasonic leak detection apparatus of this invention. It is the figure which attached the sound source and string of sound generation to the bubble generation device employ | adopted for the ultrasonic leak detection apparatus of this invention. It is the figure which attached the sound source of sound generation, the stick, and the string to the bubble generation device adopted in the ultrasonic leak detection device of the present invention.

  Hereinafter, based on the illustrated embodiment, the ultrasonic leak detection apparatus and method of the present invention will be described.

  1 and 2 show an ultrasonic leak detection system using the ultrasonic leak detection device of the present invention, and shows a situation where a liquid that is partially filled in a container that is an object of the present invention. Represent.

  For example, the access jig (moving crawler) 2 to which the ultrasonic sensor 3 is attached is inserted into the container 1 from the hole 1 </ b> A formed in the upper part of the container 1. Further, the bubble generating device 5 for generating the bubbles 4 is inserted into the same container 1 by the access jig 2.

  The ultrasonic sensor 3 is, for example, a multi-axis manipulator as shown in FIG. 1, an adsorption type that adsorbs the wall surface in the container 1 as shown in FIG. 2 by magnetism, vacuum, thruster or the like, or a migration type that swims liquid with a thruster. It is mounted on the vehicle. In FIGS. 1 and 2, reference numeral 6 denotes a liquid level, and 7 denotes a hole (leakage location) on a wall surface formed in the container 1.

  The bubble generator 5 is installed in the vicinity of the ultrasonic sensor 3 as shown in FIGS. 1 and 2, and generates a certain amount of bubbles during a certain period from time T1 to time T2, as shown in FIG. To do. That is, FIG. 3 shows the time change of the bubble generation start and end trigger signals and the bubble generation amount. From FIG. 3, it can be seen that the bubble generation is a constant amount over a certain period. The bubble generation amount is a constant value in FIG. 3, but the bubble generation amount may be changed by adjusting the flow rate or the like.

  FIG. 4 shows the time change of the bubble generation start and end trigger signals and bubble generation amount. Assuming control that bubbles are generated every N trigger signals, the ultrasonic sensor 3 It can be seen that after the occurrence, the state of the bubbles should be measured at regular time intervals.

  FIG. 5 shows a state in which bubbles in the container 1 are measured by using a visualization device that can be visualized in water as an ultrasonic measuring instrument employed in the ultrasonic leak detection device. That is, the double pipe structure portion A with the pipe 8 led out from the container wall surface 1B is a portion where there is a possibility of liquid leakage, and the access jig 2 is aimed at the double pipe structure portion A. The bubble 4 is measured by the ultrasonic sensor 3 with a visualization device inserted into the container 1. That is, the ultrasonic measuring device shown in FIG. 5 is a device that incorporates an ultrasonic sensor 3 and visualizes a reflection source in a liquid. As the reflection source, a shape changing portion (structure) in the container wall surface 1B or the container 1 is used. Objects, pipes, cracks, holes, bubbles, etc.).

  The ultrasonic sensor 3 transmits and receives ultrasonic waves three-dimensionally in the liquid filling the container 1. For example, as shown in FIGS. 6 and 7, the ultrasonic sensor 3 includes an array sensor 3A. When the piezoelectric elements 3B constituting the array sensor 3A are uniaxially arranged, as shown in FIG. By combining with scanning, three-dimensional scanning is possible. Further, as shown in FIG. 7, it is possible to electronically perform three-dimensional scanning by arranging the piezoelectric elements 3B two-dimensionally.

  As an imaging method using the array sensor 3A, there are an aperture synthesis method, a delay addition method, and the like.

  In the aperture synthesis method, for example, among the N elements constituting the array sensor 3A, the ultrasonic wave is transmitted by the jth element (position Xj) and the ultrasonic wave is received by the ith element (position Xi). For φ (τ; Xi; Xj), the elliptical orbit where the propagation time τ1 amplitude φ (τ1) is the focal point of the sensor positions Xi and Xj, and the sum of the distances between point Xi and point P and point Xj and point P is constant Is given as an amplitude value φ (τ1) in which the sum of distances is equal to the round-trip propagation distance (product of propagation time τ1 and sound velocity c), and the element positions for transmission and reception, Then, the sensor positions Xi and Xj are sequentially changed, the amplitude values at different sensor positions are added, and the pixel value of the pixel point P is obtained to form an image.

  As a special case, when data is acquired for the case where the transmission position and the reception position match, the amplitude A (τ1) of the propagation time τ1 is used as the pixel value of the point P that is the distance from the sensor position X. By giving the amplitude value Ai (τ1) of the propagation distance (product of the propagation time τ1 and the sound speed c) that is the same distance as the distance between the two points XiP, and sequentially changing the sensor position Xi, the amplitude values at different sensor positions can be obtained. The image may be formed by adding and obtaining the pixel value of the pixel point P.

  For imaging, as shown in FIG. 8, the sum of the distance between the position Xi and the position Xj is 2τ for the waveform φ (τ; Xi; Xj) 801 at the transmitting element position Xj and at the receiving element position Xi. When attention is paid to the pixel 802A that becomes xc (c is the ultrasonic wave propagation velocity in the liquid), the amplitude value 801A at the time τ is added to the transmission position Xj and the reception position Xi, and the pixel value of the pixel 802A is displayed. The area 802 is visualized as an image. At this time, as an example of the shape changing portion, the reflected wave from the pipe 8 is visualized as 802B, and the surface shape of the pipe 8 is visualized by ultrasonic waves as a boundary region 803A of the picture 802B.

  The delay addition method is also referred to as a phased array method, an electronic scanning method, or an electronic scanning method. Therefore, for example, a probe in which a plurality of ultrasonic wave generation elements made of piezoelectric vibrators are arranged in an array, so-called array sensor 3A , By applying an electrical signal that triggers the generation of ultrasonic waves to each element of the array sensor 3A with a predetermined time delay, and superposing the ultrasonic waves generated from each element to form a composite wave, Conditions such as the transmission angle and reception angle of ultrasonic waves to the inspected object, the transmission position and reception position, or the position where the combined wave interferes and strengthens each other, that is, the focal position, etc. change at high speed by electrical control. It is possible to let you.

For example, at a certain sensor position X, for the amplitude A (τ, θi) of the signal received from the angle θi direction, the propagation distance W is obtained from the product of the propagation time τ and the sound velocity c, and the angle θi with reference to the sensor position X By setting A (τ, θi) as the pixel value of the point at the distance W and changing θi, a fan-shaped image is formed, or θi is fixed and the sensor position X is moved to move in parallel. It is a method of creating a total reception image of ultrasonic waves that forms a quadrilateral image.
For imaging, as shown in FIG. 9, an amplitude value 902B and an angle at a certain time τ with respect to a waveform A (τ; θi) 902 having a path 901 propagating in a direction θi at a transmission / reception position Xk. By visualizing the pixel value corresponding to the magnitude of the amplitude value while changing θi from θi, the ultrasonic measurement result can be imaged in the sector area 904. By the amplitude value of the reflected wave from the surface of the shape changing portion (for example, the pipe 8), it is visualized as a region 903, and as the boundary of this region (that is, the rising edge 902A of the amplitude of the received signal A (τ; θi)). The surface of the pipe 8 is visualized as an ultrasonic image boundary 903A.

  In either case of the aperture synthesis method or the delay addition method, for example, a cross-sectional image on a certain plane can be formed by the above procedure. Therefore, as shown in FIG. 6, the array sensor 3A is mechanically scanned. By moving the plane on which the ultrasonic wave generated from the plane propagates in a direction including a component orthogonal to the plane, a plurality of plane images can be formed, and a three-dimensional image can be formed.

  Alternatively, as shown in FIG. 7, the piezoelectric elements 3B forming the array sensor 3A are two-dimensionally arranged to perform three-dimensional electronic scanning, and similarly, a plurality of planar images are formed to form a three-dimensional image. Can be formed. In the case of FIG. 7, in the aperture synthesis method, the trajectory of the pixel point P at which the distance XiP between the two points from the sensor position Xi is equal is a sphere (or spheroid). In addition, in the case of the delay addition method, the transmission direction of the ultrasonic wave from a certain sensor position is set by two polar angles (θ, φ) or the like.

  For example, as shown in FIG. 8, the imaged pixel values can be displayed on the display unit as a cross-sectional image corresponding to the color bar.

  In addition, as shown in FIG. 9, when imaging the surface of a reflector (structure) by a delay-and-sum imaging method, a specific axis with time (or distance) on the horizontal axis and amplitude on the vertical axis is shown. A fan-like cross-sectional view is drawn from the intensity of the received waveform propagating in the direction (incident angle) and the propagation direction (incident angle). In a fan-shaped display, pixel values are visualized as pixels in association with black and white or color color bars.

  In any case, since a strong ultrasonic signal is reflected on the surface of the structure or on a reflector such as a bubble, the region of the cross-sectional image having a large pixel value (that is, a portion having a large amplitude value). As such, the boundary of the reflector (structure or bubble) is imaged.

  Next, the operation of the array sensor 3A that transmits and receives ultrasonic waves will be briefly described.

  The piezoelectric vibrators constituting the ultrasonic array sensor are connected to the transmission / reception unit, and longitudinal wave ultrasonic waves are generated from the piezoelectric vibrators in the liquid and propagated in the liquid by a drive signal sent from the transmission / reception unit.

  When a reflector such as a structure or a bubble is present in the liquid, longitudinal wave ultrasonic waves are reflected mainly on the surface of the reflector as longitudinal wave ultrasonic waves. The ultrasonic wave reflected by the reflector propagates in the liquid, propagates again to the piezoelectric vibrators constituting the ultrasonic array sensor, and the received ultrasonic wave is converted into an electric signal.

  The electric signal of the received wave is recorded by the transmission / reception unit, and is displayed on the display unit as, for example, a reception signal, a two-dimensional cross-sectional image, or a three-dimensional image. The received signal is stored as a reference signal in the storage unit as necessary.

  Here, the ultrasonic array sensor, the transmission / reception unit, the storage unit, and the display unit will be described with reference to FIG.

  The piezoelectric vibrators constituting the ultrasonic array sensor 104 are, for example, piezoelectric ceramics or composite piezoelectric bodies in which thin rods of the piezoelectric ceramics are embedded in a polymer material as an example of an ultrasonic wave generating element (also referred to as a composite). ) Is used. Piezoelectric vibrators (or elements) are usually arranged at regular intervals.

  In the case of the delay addition method, the transmission / reception unit 107 includes, for example, a pulser 107A, a receiver 107B, a delay time control unit 107C, a data recording unit 107D, and a computer 107E, and controls the timing of the drive signal output from the pulser 107A. The delay time control unit 107C controls the input timing of the reception signal by the receiver 107B, thereby obtaining the operation of the ultrasonic array sensor 3A by the delay control method. The data recording unit functions to process reception signals supplied from the 107D and the receiver 107B and supply them to the display unit 109.

  The storage unit 108 records flaw detection data recorded by the transmission / reception unit 107, and particularly refers to a state where no bubbles are generated (or a time zone) and initial measurement data (received signal) immediately after the generation of bubbles. The data 108A is stored, and the shape data 108B of the subject is stored and supplied to the computer 107E.

  The display unit 109 is a means for displaying a reception signal corresponding to an ultrasonic reception angle (in this embodiment, since the transmission direction and the reception direction are the same, the transmission angle and the reception angle are the same). As an example, an example is shown in which received signals when ultrasonic waves are transmitted and received in the range from the start angle to the end angle are displayed in a fan shape with the angle in the circumferential direction and the one-way propagation distance in the axial direction. Note that the method of scanning by changing the transmission angle of ultrasonic waves in this way is called sector scanning.

  When the transmission angle is scanned from the start to the end, it is assumed that it is due to a reflection signal from a reflector (a shape changing portion such as a structure) in the structure in the container 1 in which the array sensor 3A is immersed, or a bubble group. The reflected signal is received, and is displayed as a region having a different color or darkness according to the strength of the received signal in a sector shape like a measurement image.

  An example of the movement of the bubbles 4 when there is a leak in the container 1 is shown in FIG.

  As shown in the figure, the position of the group of bubbles 4 at a certain time Ta is the same as that of the pipe 8 led to the inside from the container wall surface 1B at which the leakage may occur at a certain time Tb after Ta. When the vicinity of the heavy pipe structure portion A is approached and leakage occurs, it is assumed that a phenomenon occurs in which the number of bubbles 4 decreases due to leakage and the volume of the bubbles 4 group decreases.

  Here, for example, in order to compare with a measurement image after bubble generation, the reference data 108A stored in the storage unit 108 is read into the image processing unit 110A, and images at different times (for example, images before bubble generation or (E.g., immediately after the bubble is generated), by displaying it side-by-side with the measurement image, by performing image processing to determine that there is no change in the shape, and in the case where there is a change, the bubble region is extracted by extracting the moving object. Judgment can be made.

  Further, the image processing unit 110A compares the image after the bubble is generated in this way with the image at a different time so that the reflected signal from the shape changing unit of the structure is data that does not change regardless of the time. It can be determined by appearing in both the reference image and the measurement image. In addition, the reflection signal assumed to be the bubble group 602 can be identified from the measurement image and the reference image that there is a change in the location or number of appearances, and by grasping the time change of the bubble movement, It becomes possible to identify the flow of fluid that leads to leakage inside, the presence or absence of leakage, and the leakage location.

  For example, the image processing result can be displayed on the processing display unit 110 as an image obtained by extracting a bubble region from ultrasonic measurement images at different times Ta and Tb. Alternatively, the determination of leakage can be displayed in an easy-to-understand manner by displaying temporal changes in the physical quantity of the bubble group (for example, the volume of the bubble group, the position of the center of gravity, the moving speed of the center of gravity, etc.).

  Note that the aperture composition system configuration is different from the delay addition mode in that the delay time control unit 107C is not used, but visualization can also be achieved with an apparatus configuration similar to the delay addition type configuration. However, since the number of elements used simultaneously is one for transmission and one for reception, the number of channels of the pulser 107A and the receiver 107B may be reduced. The aperture synthesis algorithm is executed in the computer 107E.

  The bubble generator 5 generates a plurality of bubbles 4 from nozzles or holes mixed with gas and liquid. Further, the bubbles 4 may be generated by a chemical reaction involving electrolysis or gas generation, or a bubble such as a contrast medium may be prepared in advance and flowed together with the liquid.

  FIG. 17 shows an overall block diagram of the bubble generating device 5, the ultrasonic measuring device 104, and the access jig. Both the bubble generating device 5 and the ultrasonic measuring device 104 are connected to an access jig (multi-axis arm, moving mechanism, etc.) and access the inside of a container or the like where the occurrence of leakage is a concern.

  Bubble generation and ultrasonic measurement are performed in time synchronization, such as before bubble generation, immediately after bubble generation, and at regular intervals after bubble generation. As an example, a trigger signal (5E in FIG. 4) is generated by the synchronization interface 104A. The generated synchronization signal is sent to the ultrasonic measuring instrument 104, and the ultrasonic signal is measured in synchronization with the synchronization signal. The same synchronization signal is sent to the bubble generating device 5, and the synchronization signal is received by the synchronization processing unit 5D. For example, bubbles are generated from the bubble generator 5A by controlling the period and the number of times the bubbles are generated by the control unit 5B such that bubbles are generated once every N synchronization signals. In addition, by generating sound in synchronization with the synchronization signal by the acoustic signal generation unit 5C, by using the acoustic signal as the synchronization signal, the position of the bubble generation device and the flow of liquid around the bubble generation device are It is possible to measure with an ultrasonic measuring instrument.

  If the bubbles 4 are continuously generated, the container 1 fills up and it becomes difficult to measure the flow and leakage. Therefore, the bubbles 4 are generated for a certain period from a certain time T1 to T2.

  The bubble generated for a certain period rises slightly due to the influence of buoyancy, but if the bubble 4 is small to some extent, the influence of buoyancy can be made smaller than the influence of flow.

  When the bubble group is observed with an ultrasonic camera, the reflected wave from the bubble 4 is received and visualized as a plurality of cloud-like images. For example, the volume representing the expansion of the bubble group can be obtained by image processing for binarizing the region including the bubble group for this image.

  It is also possible to obtain the position of the center of gravity of the bubble group and the moving speed of the center of gravity from the binarized region of the bubble group.

  FIG. 11 shows an example of a view obtained by binarizing the bubble group area by image processing, and the visualization result of ultrasonic waves of the bubble group 4 at time Ta and the subsequent time Tb.

  As shown in the figure, it is assumed that the expansion (volume) of the bubble group 4 increases and decreases as time elapses from time Ta to time Tb. The increase in volume means, for example, diffusion in a liquid, and the phenomenon of volume may be the outflow of bubbles 4 due to leakage or the disappearance of bubbles 4 due to changes over time.

  Furthermore, as shown in FIG. 10, in the double pipe structure portion A where leakage is a concern, the flow of liquid accompanying the leakage occurs, so that the position of the bubble group (for example, the position of the center of gravity) does not move. It is also expected to happen.

  By measuring the change over time in the physical quantity (volume, position, velocity, etc.) of the bubble group, for example, the volume of the bubble group is expected to increase due to diffusion. Further, the position of the center of gravity moves according to the flow.

  FIG. 12 shows an example of the result of measuring the bubble generation and the subsequent change in volume of the bubble group. The bubble generation period T1 to T2 (see the lower diagram in FIG. 12) has passed, and the bubble volume has increased, and then the phenomenon occurs (see the upper diagram in FIG. 12).

  FIG. 13 shows an example of the result of measuring the bubble generation and the subsequent change in the center of gravity of the bubble group. This represents a situation (see the upper diagram in FIG. 13) in which the center of gravity of the bubbles has moved along the flow after the bubble generation periods T1 to T2 (see the lower diagram in FIG. 13).

  FIG. 14 shows an example of the result of measurement of bubble generation and the subsequent change in the velocity of the center of gravity of the bubble group. It shows a situation (see the upper diagram in FIG. 14) that the bubbles have moved at high speed after the bubble generation periods T1 to T2 (see the lower diagram in FIG. 14) and then slowly moved at a constant speed.

  Thus, by measuring the physical quantity of the bubble group at different times, it becomes possible to indirectly measure a change accompanying the leakage of the liquid.

  For example, as shown in FIG. 15, if a threshold value is provided for a physical quantity, it is possible to make a leak determination using a trigger for determination that the threshold value has been exceeded.

  As shown in FIG. 16, the measurement results at different times are displayed on the display unit, for example, at different times, or the change over time in the physical quantity to be measured is measured as shown in FIGS. Thus, leakage can be determined.

  As an example, FIG. 18 shows a leakage determination flow.

  As shown in FIG. 18, a leak detection device including an ultrasonic measuring instrument and a bubble generation device is inserted into the liquid in the container with an access jig. Examples of the access jig 2 include a manipulator as shown in FIG. 1 and a moving mechanism as shown in FIG.

  Next, by measuring the shape (structure) in the container, the shape changing portion that is likely to be leaked is specified by measuring while moving the ultrasonic measuring instrument.

  Next, when a place where there is a possibility of leakage, for example, a pipe, a hole or a crack is found, the position of the ultrasonic measuring instrument is fixed on the spot.

  After that, a certain amount of bubbles is generated for a certain period in the vicinity of the shape change portion that may leak.

  The generated bubbles are measured with an ultrasonic measuring instrument. The area of the bubble group is emphasized by image processing, physical quantities (volume, centroid position, centroid position speed, etc.) are measured, measurements are taken at two different times, and changes over time are measured as shown in FIG. .

  That is, in FIG. 19, when the bubble 4 is generated a plurality of times as shown in FIG. 4, after the Kth bubble 4 is generated by the bubble generator 5, the bubble is generated at the K + 1th time that has changed to some extent. The state where the bubbles 4 are moving and diffusing is shown, and the state of the bubbles 4 at the (K + 1) th time is measured.

  Next, measurement is performed until a predetermined set number of times is reached, and it is determined whether leakage behavior (for example, the phenomenon of the volume of the bubble group and the change in the center of gravity of the bubble group have occurred simultaneously) is shown.

  After recording the presence / absence and position of leakage, the ultrasonic measurement apparatus is moved to the next position where leakage is a concern and the above measurement is repeated.

  As a leak detection method, the shape change part of the structure in the container 1 is measured by the ultrasonic measuring instrument described above, and the position and shape thereof are visualized. This shape change portion becomes a position (candidate) that may leak.

  After the candidate position for leakage is measured, a certain amount of bubbles 4 are generated in a certain period, and the physical quantity of the bubbles is measured. If leakage occurs at the candidate position, the center of gravity of the bubble group changes so as to approach the candidate position, and further, the liquid containing the bubbles 4 leaks from the candidate position to another container or the like when approaching. By doing so, it is measured that the volume of the bubble group decreases.

  If there is no leakage at the candidate position, the center of gravity of the bubble group moves along the liquid flow in the region where the bubble 4 is generated, but the volume of the bubble group diffuses. In addition, when observed for a long time, the volume of the observed bubble group changes due to the disappearance or diffusion of the bubbles 4.

  At this time, since the bubble group moves to a position different from the candidate position, the volume reduction due to diffusion or disappearance and the volume reduction due to the leakage can be distinguished by a combination of the position specification.

  Moreover, it can measure simultaneously with bubble generation by electrically giving a common synchronizing signal to the bubble generator 5 and the ultrasonic measuring device.

  Further, if a pulse-like trigger signal at equal time intervals is given as the synchronization signal, periodic measurement can be performed with respect to time, and the change with time can be easily measured.

  Furthermore, an acoustic synchronization signal may be used as the synchronization signal of the bubble generator 5. For example, as shown in FIG. 20, this synchronization signal can be realized by an underwater speaker installed in the bubble generating device 5, a sound source 11 that generates bubbles or mechanical sound, and the like. With the acoustic synchronization signal generation device, the bubble generation device 5 can be acoustically visualized from the ultrasonic measurement device, and the bubble generation position can be specified by sound.

  Furthermore, as shown in FIG. 21, two or more sound sources 11 similar to those in FIG. 20 (three in FIG. 21) are provided, and these sound sources 11 are connected by thin strings 12 along the flow of liquid in the container. In addition to the bubble generation position 5, the flow state can be specified by sound.

  Further, as shown in FIG. 22, a second sound source 11 is installed above the first sound source 11 in a place extended from the bubble generator 6 with a stick 13 or the like. The third sound source 11 may also be connected by a string 12.

  In the above description, the sound source 11 that generates sound is given to the bubble generation device 5 as an alternative to the acoustic synchronization signal generation device. However, a passive reflection source that can be visualized by reflected waves of ultrasonic waves such as spheres with different radii. It may be used.

  DESCRIPTION OF SYMBOLS 1 ... Container, 1A ... Hole, 1B ... Container wall surface, 2 ... Access jig, 3 ... Ultrasonic sensor, 3A ... Array sensor, 3B ... Piezoelectric element, 4 ... Bubble, 5 ... Bubble generator, 5A ... Bubble generating part DESCRIPTION OF SYMBOLS 5B ... Control part, 5C ... Acoustic signal generation part, 5D ... Synchronization processing part, 5E ... Synchronization trigger signal, 6 ... Liquid level, 7 ... Wall hole, 8 ... Piping, 11 ... Sound source, 12 ... String, 13 ... 104, ultrasonic measuring device, 104A, synchronization processing interface, 107, transmission / reception unit, 107A, pulser, 107B, receiver, 107C, delay time control unit, 107D, data recording unit, 107E, computer, 108, storage unit, 108A ... reference data 108B ... shape data 109 ... display unit 110 ... leakage display unit 110A ... image processing unit 602 ... bubble group. 801: Received waveform, 801A: Received waveform amplitude at time τ, 801B ... Propagation path, 802 ... Ultrasonic measurement result display area, 802A ... Pixel, 803A ... Shape change part boundary, 803B ... Shape change part video range, 901 ... Propagation 902 ... received waveform, 902A ... rise position of amplitude value of received waveform, 902B ... received waveform amplitude at time τ, 903 ... shape change portion video range, 903A ... shape change portion boundary, 904 ... ultrasound measurement result display area

Claims (9)

Using an ultrasonic sensor that is partly or wholly immersed in the liquid contained in the container, ultrasonic waves are transmitted from the container by the ultrasonic wave transmitting / receiving means, and the reflected waves from the reflector in the container are received. In the ultrasonic leak detection device that detects the leakage of liquid by
Bubble generating means for generating a plurality of bubble groups in the container, structure in the container and visualization means for visualizing the bubble groups from the ultrasonic reception signal, and visualization results of the bubble groups by the visualization means And an ultrasonic leak detection device comprising: a measuring unit that measures a temporal change in the distribution of the bubble group. The ultrasonic leak detection device according to claim 1,
The ultrasonic leak detection apparatus further comprising a control means for controlling a time for generating the bubbles and a time for stopping the generation. In the ultrasonic leak detection device according to claim 1 or 2,
An ultrasonic leak detection apparatus further comprising a transmission means for transmitting a synchronization signal synchronized with bubble generation. The ultrasonic leak detection device according to claim 3,
An ultrasonic leak detection device comprising sound transmitting means for transmitting sound as the synchronization signal. In the ultrasonic leak detection device according to claim 4,
The ultrasonic leak detection device, wherein the sound generation means is an underwater speaker, a bubble, or a sound source that generates mechanical sound. The ultrasonic leak detection device according to claim 5,
The ultrasonic leak detection apparatus according to claim 1, wherein the sound source includes a plurality of sound sources, and the sound sources are connected with a string. Leakage of liquid by transmitting ultrasonic waves from inside the container and receiving reflected waves from the reflector in the container using an ultrasonic sensor partially or wholly immersed in the liquid contained in the container In the ultrasonic leak detection method for detecting
From the ultrasonic reception signal, visualize the shape of the container from the structure in the container, and measure the leakage of the liquid from the temporal change in the distribution of the plurality of bubble groups generated in the container. An ultrasonic leak detection method characterized by the above. In the ultrasonic leak detection method according to claim 7,
An ultrasonic leak detection method characterized in that the leak of liquid is measured by generating the bubbles temporarily or intermittently at regular intervals and measuring the distribution of the bubble group leaking from the leak location. The ultrasonic leak detection method according to claim 7 or 8,
An ultrasonic leak detection method, wherein the bubble group distribution is measured in synchronization with a bubble generation and in synchronization with a signal that repeats in time.

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