JP6596536B2 - Piping inspection method - Google Patents

Description

  Embodiments described herein relate generally to a pipe inspection apparatus and a pipe inspection method.

  Inspection of pipe thinning and corrosion is performed using, for example, an ultrasonic flaw detection method. In the ultrasonic flaw detection method, a probe that transmits and receives ultrasonic waves is pressed against the surface of a test object, and ultrasonic waves of various frequencies are propagated inside the test object. And the ultrasonic wave which reflected and returned by the defect inside a to-be-tested object and the back surface of a to-be-tested object is received, and the state inside a to-be-tested object is grasped | ascertained.

  In power plants, there is a tendency for thinning to occur easily in the elbow part of the piping or the downstream side of the orifice part due to FAC (Flow Accelerated Corrosion) or erosion. Pipe thickness reduction management is performed, for example, by pipe thickness measurement using an ultrasonic thickness measuring instrument. However, this method requires a great deal of time and cost because it is necessary to disassemble and restore the heat insulating material covering the pipe every time the wall thickness is measured.

  Therefore, in order to realize low-cost thinning management, an embedded type fixed point measuring sensor has been developed. For example, an optical fiber EMAT method using an ultrasonic optical probe in which an electromagnetic ultrasonic transducer (EMAT) and an optical fiber sensor are combined is known. The electromagnetic ultrasonic oscillator is an oscillator that excites ultrasonic waves in a pipe by the action of electromagnetic force. The optical fiber sensor is a sensor for detecting a resonance wave of an excited ultrasonic wave with a laser beam.

  However, the optical fiber EMAT method is based on the premise that an optical fiber sensor is attached to a pipe surface and an electromagnetic ultrasonic oscillator is placed on the optical fiber sensor. For this reason, pipe inspection devices are installed from individual ultrasonic optical probes on pipes for power supply to the electromagnetic ultrasonic oscillator, signal input to the electromagnetic ultrasonic oscillator, and signal output from the electromagnetic ultrasonic oscillator. It is necessary to draw out the power supply line and the signal line, and the problem is that the local wiring volume increases. When the wiring volume is large, the convenience of pipe inspection is impaired due to the difficulty of routing the wiring and the possibility of disconnection of the wiring. This problem becomes more serious as the number of ultrasonic optical probes is increased.

  Moreover, in a power plant, the performance of the plant and equipment often deteriorates due to a change in the state of the inner and outer surfaces of the poorly accessible piping such as buried piping and high-temperature piping. For example, there are a variety of phenomena to be detected by pipe inspection, such as adhesion of scales to the inner surface of heat exchanger piping, peeling of coating on the inner surface of pipes through which corrosive fluid flows, and rusting on the inner surface of water and sewage piping. However, it is difficult to detect these, which impairs the convenience of pipe inspection. As described above, the optical fiber EMAT method is expected as a technique capable of quantitatively evaluating the wall thickness of pipes that are thickened or thinned due to various causes.

Riichiro Uchigasaki et al. “Nuclear Power and Design Technology” Taiga Publishing (1980) pp.226-250 Sasaki, Takahashi et al. "Metal thickness measurement by electromagnetic ultrasonic resonance using optical fiber Doppler sensor" welding structure symposium 2006 lecture collection (November 2006) Takahashi, Sasaki et al. "Metal pipe thickness measurement by electromagnetic ultrasonic resonance method using fiber optic Doppler" Material "The 1st Joint Lecture on Inspection, Evaluation and Maintenance" by the Maintenance Society (January 2008) Yamaya, Takahashi, Ahiko "Measurement technology of pipe thinning in thermal power plants" Toshiba review Vol.63, No.4 (2008) pp.41-44 Sasaki, Takahashi, Yamaya "Pipe thinning measurement technology using electromagnetic ultrasonic resonance method" Thermal Nuclear Power Generation No.636, Vol.60 (2009) pp.40-46

  Provided are a pipe inspection apparatus and a pipe inspection method capable of improving the convenience of pipe inspection.

  According to one embodiment, a pipe inspection method includes supplying power to an ultrasonic optical probe attached to a pipe using wireless power feeding or energy harvesting. Further, the method includes inputting an ultrasonic wave from the ultrasonic oscillator of the ultrasonic optical probe to the pipe and inputting a laser beam to an optical fiber sensor of the ultrasonic optical probe. Further, the method includes detecting the laser light transmitted through the optical fiber sensor that the ultrasonic wave has reached from the pipe, and determining a state of the pipe based on a detection result of the laser light. .

It is the schematic which shows the structure of the piping inspection system of 1st Embodiment. It is the schematic which shows the structure of the ultrasonic optical probe of 1st Embodiment. It is the schematic which shows the example of attachment to piping of the ultrasonic optical probe of 1st Embodiment. It is the schematic which shows the structure of the piping inspection system of 1st Embodiment. It is the schematic which shows the structure of the laser light-emitting end for probes of 1st Embodiment, and a laser light-receiving end. It is the schematic which shows the structure of the terminal block of 1st Embodiment. It is a figure for demonstrating the example of the wireless electric power feeding of 1st Embodiment. It is a figure for demonstrating the example of the energy harvesting of 1st Embodiment. It is a figure for demonstrating the structural example of the optical fiber sensor of 1st Embodiment. 10 is a graph showing experimental results of intensity measurement of a reference laser beam in the cases of FIGS. 9A and 9B. It is a figure which shows the 1st example of a connection of the optical fiber sensors of 1st Embodiment. It is sectional drawing and the side view which show the detail of the 1st example of a connection of the optical fiber sensors of 1st Embodiment. It is a figure which shows the 2nd example of a connection of the optical fiber sensors of 1st Embodiment. It is a figure which shows the 3rd connection example of the optical fiber sensors of 1st Embodiment. It is a figure which shows the 1st example of connection of EMAT of 1st Embodiment. It is a figure which shows the 2nd example of connection of EMAT of 1st Embodiment. It is a figure which shows the 3rd example of connection of EMAT of 1st Embodiment. It is sectional drawing which shows the 1st modification of the ultrasonic optical probe of 1st Embodiment. It is sectional drawing which shows the 2nd modification of the ultrasonic optical probe of 1st Embodiment. It is a figure for demonstrating the piping inspection method of 1st Embodiment. It is a graph for demonstrating the 1st example of the piping test | inspection method of 1st Embodiment. It is a graph for demonstrating the 1st example of the piping test | inspection method of 1st Embodiment. It is a figure for demonstrating the 2nd example of the piping inspection method of 1st Embodiment. It is a figure for demonstrating the 3rd example of the piping inspection method of 1st Embodiment. It is a flowchart for demonstrating the 4th example of the piping inspection method of 1st Embodiment. It is sectional drawing for demonstrating the modal analysis of a 4th example. It is sectional drawing for demonstrating the frequency response analysis of a 4th example. It is a graph for demonstrating the time history response analysis of a 4th example. It is the graph which showed the frequency spectrum obtained by the time history response analysis of a 4th example.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a schematic diagram illustrating a configuration of a pipe inspection system according to the first embodiment.

  The piping inspection system of this embodiment includes an ultrasonic optical probe 1 including an electromagnetic ultrasonic oscillator (hereinafter referred to as “EMAT”) 1a and an optical fiber sensor 1b, a light source 2a, an optical interferometer 2b, and a waveform signal generator 2c. And a pipe inspection apparatus 2 including an amplifier 2d and a computer 3. The ultrasonic optical probe 1 is attached to the surface of the pipe 4. The pipe 4 of this embodiment is, for example, a pipe in a nuclear power plant, a thermal power plant, or a geothermal power plant, a pipe constituting a pipeline or a water pipe, and the like.

  The EMAT 1a is attached to the pipe 4 via the optical fiber sensor 1b, and excites ultrasonic waves in the pipe 4 by the action of electromagnetic force. The optical fiber sensor 1b is a circular flat plate in which a linear optical fiber is wound in a spiral shape (mosquito-repellent incense), and is used to detect a resonance wave of an excited ultrasonic wave with a laser beam. This circular flat plate has the same size as, for example, a 5-yen coin.

  The waveform signal generator 2c and the amplifier 2d generate and amplify a high-frequency current under the control of the computer 3 and supply it to the EMAT 1a. The light source 2a generates reference laser light and supplies it to the optical fiber sensor 1b. The optical interferometer 2b detects a change in the reference laser light transmitted through the optical fiber sensor 1b.

  The computer 3 has a diagnostic database in which determination thresholds relating to deterioration of the pipe 4 such as corrosion and thinning of the pipe 4 are stored. The computer 3 compares the detection result of the original waveform received from the optical interferometer 2b and the processing result obtained by performing signal processing on the original waveform with the data in the diagnostic database, and determines the deterioration degree of the pipe 4.

  FIG. 2 is a schematic diagram showing the configuration of the ultrasonic optical probe 1 of the first embodiment.

  The EMAT 1a includes a permanent magnet A1 and an electric coil A2. The permanent magnet A1 and the electric coil A2 are integrated via a resin sheet 1c.

  As a factor governing the heat resistance and durability of the permanent magnet A1, there is a material of the permanent magnet A1. An example of the material of the permanent magnet A1 with good heat resistance is samarium cobalt. Since the demagnetization point of samarium cobalt is between 350 and 400 ° C., when the samarium cobalt permanent magnet A1 is used at a high temperature, it is desirable to use it at 350 ° C. or less.

  Further, from the viewpoint of considering cobalt as a rare metal, a permanent magnet A1 using an alternative material for cobalt has also been developed. For example, a samarium iron-based (Sm—Fe—N-based) permanent magnet A1 has been commercialized as a bonded magnet. If a samarium iron-based sintered magnet is used as the permanent magnet A1 to execute the optical fiber EMAT method, which is a high-temperature application, the ultrasonic optical probe 1 that is cheaper and more environmentally friendly can be realized.

  A high-frequency current is supplied to the electric coil A2 from the amplifier 2d. As a result, ultrasonic waves are excited inside the pipe 4 by Lorentz force and magnetostriction generated by electromagnetic induction in the electric coil A2. The high-frequency current is adjusted to have a predetermined frequency and amplitude under the control of the waveform signal generator 2c and the amplifier 2d by the computer 3.

  The optical fiber sensor 1b is integrated with the EMAT 1a by the resin sheet 1c and the adhesive 1d. The ultrasonic optical probe 1 is bonded to the measurement target pipe 4 with an adhesive 1d.

  When an ultrasonic wave is input from the EMAT 1a to the pipe 4, a part of the ultrasonic wave reaches the optical fiber sensor 1b. Here, when the ultrasonic wave reaches the optical fiber sensor 1b in a state where the reference laser light from the light source 2a is input to the optical fiber sensor 1b, the optical fiber sensor 1b expands and contracts slightly due to the influence of the ultrasonic wave. The Doppler frequency shift and the polarization plane change occur in the laser light.

  The optical interferometer 2b detects this variation by photoelectrically converting and measuring the reference laser light transmitted through the optical fiber sensor 1b. As described above, the optical interferometer 2b can detect the resonance state of the ultrasonic wave in the thickness direction through detection of the reference laser beam. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  The ultrasonic optical probe 1 can obtain a sufficient signal intensity in measuring the thickness even if the shape of the EMAT 1a is a simple shape as shown in FIG. Factors that influence the accuracy and sensitivity of wall thickness measurement include the oscillation power of EMAT 1a and the degree of adhesion of the optical fiber sensor 1b to the pipe 4. Therefore, the magnetic force of the permanent magnet A1 at a high temperature and the reliability (durability) of the joint between the optical fiber sensor 1b and the pipe 4 are important.

  Regarding the magnetic force of the permanent magnet A1, there is a method of preventing oxidation of the permanent magnet A1 by using a heat-resistant permanent magnet A1 for high temperature and plating it. By using the plated high-temperature permanent magnet A1 and the polyimide-coated electric coil A2, the oscillation power of the EMAT 1a can be maintained even at high temperatures.

  On the other hand, examples of a method for joining the optical fiber sensor 1b and the pipe 4 include adhesion with a high-temperature adhesive and thermal spraying. It is desirable that the optical fiber sensor 1b is disposed so as to be in close contact with the surface of the pipe 4 according to the surface shape or curvature of the pipe 4, and is fixed to the surface of the pipe 4 by adhesion or thermal spraying. At this time, the optical fiber sensor 1b and the pipe 4 may be in direct contact with each other, or may be in close contact with each other through an indirect material such as a flexible sheet. In the latter case, it becomes possible to improve reliability such as heat resistance and durability over a long period by increasing the bonding strength, and to perform bonding with an inexpensive material because the construction is easy.

  When bonding the polyimide-coated optical fiber sensor 1b, a polyimide-based adhesive has good long-term reliability, and an epoxy-based or silicon-based adhesive tends to deteriorate relatively quickly. When the polyimide-coated optical fiber sensor 1b is bonded to the metal pipe 4, it is desirable to bond the polyimide-coated optical fiber sensor 1b by a vacuum impregnation method using a polyimide adhesive.

  In the vacuum impregnation method, first, the optical fiber sensor 1b is sandwiched between glass cloths impregnated with an adhesive. Next, a predetermined heat-curing is performed by adjusting the temperature of the heater while vacuum-packing it on the surface of the pipe 4 together with a planar heater or a rubber heater and pressing it at atmospheric pressure. Next, after curing and bonding, the release film, breather, heater, pack film, etc. are removed from the surface of the glass cloth.

  The optical fiber sensor 1b can be manufactured by the following procedure. First, a heat-resistant coated fiber is wound in a spiral shape. Next, the heat-resistant coated fiber wound in a spiral shape is fixed on a flexible sheet made of a heat-resistant material such as polyimide using a polyimide varnish. The optical fiber sensor 1b may be sandwiched between a glass cloth impregnated with an adhesive together with the flexible sheet, or may be directly sandwiched between glass cloths.

  Moreover, you may use the ceramic type adhesive agent which mix | blended the metal powder instead of the polyimide-type adhesive agent. It has been confirmed that ceramic adhesives containing metal powder have good workability and durability. When such an adhesive is used, a sufficient bonding strength can be obtained by simply applying and holding the optical fiber sensor 1b on the surface of the pipe 4 and curing the adhesive at room temperature. In this case, a glass cloth may be interposed between the optical fiber sensor 1b and the pipe 4, or may not be interposed.

  FIG. 3 is a schematic view showing an example of attachment of the ultrasonic optical probe 1 of the first embodiment to the pipe 4.

  In the present embodiment, the thickness of the pipe 4 is measured by attaching a plurality of ultrasonic optical probes 1 to the outer surface of the pipe 4 and analyzing by the computer 3 the resonance ultrasonic signals that are multiple-reflected from the inner face and the outer face of the pipe 4. To do. The material of the pipe 4 is, for example, carbon steel. In the present embodiment, the ultrasonic light probe 1 is embedded in advance between the pipe 4 and the heat insulating material (heat insulating material) 5 so that the thickness measurement (degradation degree determination) can be performed online. According to this embodiment, since it is not necessary to disassemble and restore the heat insulating material 5 every time the wall thickness is measured, the safety of the power plant and the equipment operation rate can be increased.

  In the pipe thinning management standard, the position of the thickness measurement point of the pipe 4 is determined according to the diameter of the pipe 4. When the size of the pipe 4 is 150A (outer diameter: about 165 mm) or more, eight locations (45 ° intervals) in the circumferential direction of the pipe 4 are determined. In addition, when the size of the pipe 4 is less than 150 A, four locations (90 ° intervals) are determined in the circumferential direction of the pipe 4. FIG. 3 shows an example of the former case. In addition, about the axial direction of the piping 4, it is decided to set the thickness measurement point of the piping 4 by the space | interval below the outer diameter length of the piping 4. FIG.

  A method for measuring the thickness of the pipe 4 using these ultrasonic optical probes 1 will be described.

  When a high frequency current flows, the electric coil A2 of the EMAT 1a vibrates the pipe 4 and generates an ultrasonic wave in the pipe 4. At this time, the computer 3 sweeps the ultrasonic frequency in a desired frequency band by changing the frequency of the high-frequency current through the waveform signal generator 2c.

  The ultrasonic wave in the pipe 4 propagates to the optical fiber sensor 1b. When an ultrasonic wave reaches the optical fiber sensor 1b in a state where the reference laser beam is input to the optical fiber sensor 1b, a shift of the Doppler frequency or a fluctuation of the polarization plane occurs in the reference laser beam. The fluctuation value (expansion / contraction speed) is converted into a voltage value by photoelectric conversion by the optical interferometer 2b, whereby the frequency of the ultrasonic wave propagating in the pipe 4 can be measured.

  When the relationship of λ = 2d is established between the thickness d of the pipe 4 and the wavelength λ of the ultrasonic wave in the pipe 4, the incident wave and the reflected wave of the ultrasonic wave resonate, and the amplitude of these combined waves Becomes larger. This relationship can be expressed as f = v / 2d using the frequency f of the ultrasonic wave in the pipe 4 and the speed of sound v. Therefore, if the frequency f and the speed of sound v of the ultrasonic wave at the time of the resonance are obtained, the wall thickness d of the pipe 4 can be obtained.

  Therefore, in this embodiment, when measuring the wall thickness d of the pipe 4, the ultrasonic frequency is swept in a desired frequency band, and the resonance frequency f is measured. On the other hand, the speed of sound v can be calculated from the material of the pipe 4. Therefore, in this embodiment, the wall thickness d of the pipe 4 can be derived using the measured resonance frequency f and the calculated sound velocity v.

  For example, in the case of a steel pipe 4 having a wall thickness of 15 mm, resonance occurs when an ultrasonic wave of 200 kHz is input. According to this embodiment, if it is known that the pipe 4 is made of steel and the resonance frequency f is 200 kHz, it can be determined that the wall thickness d of the pipe 4 is 15 mm.

  The ultrasonic optical probe 1 according to the present embodiment includes a portion considered to be statistically susceptible to thinning, such as an elbow portion or a downstream side of an orifice portion of a piping 4 of a nuclear power plant or a thermal power plant, a geothermal power plant piping, It is desirable to attach to the place etc. which are easy to raise | generate blockage of the piping 4 which comprises a water pipe. Further, the waveform signal generator 2c of the present embodiment is preferably configured such that the frequency of vibration generated in the pipe 4 can be set to an arbitrary frequency of 1 Hz to 10 MHz according to the thickness of the pipe 4. . In addition, it is desirable that the computer 3 of the present embodiment is configured to detect not only ultrasonic vibration with a frequency of 20 kHz to 10 MHz but also non-ultrasonic vibration with a frequency of 1 Hz to 20 kHz via the optical interferometer 2b. .

  Reference numerals 11 and 12 shown in FIG. 3 indicate optical fibers connected to the ultrasonic optical probe 1 and the pipe inspection apparatus 2 (optical interferometer 2b), respectively. These optical fibers 11 and 12 may have exposed surfaces, may be sandwiched between members such as a resin sheet and a flexible sheet material, or may be configured by a combination thereof. Moreover, the adhesive agent may be filled in the clearance gap between the optical fibers 11 and 12 and the member which pinches | interposes these. Details of the optical fibers 11 and 12 will be described later.

(1) Power Supply and Signal Input / Output in the First Embodiment FIG. 4 is a schematic diagram showing the configuration of the pipe inspection system of the first embodiment.

  FIG. 4 shows a probe laser emission end 21 connected to one end of the optical fiber sensor 1b via the optical fiber 11, and a laser receiving end 22 connected to the optical interferometer 2b via the optical fiber 12. A laser emission end 23 connected to the light source 2a via the optical fiber 13 and a probe laser receiving end 24 connected to the other end of the optical fiber sensor 1b via the optical fiber 14 are shown.

  FIG. 4 further shows a wireless power feeding / transmitting circuit 25 that is disposed apart from the ultrasonic optical probe 1, and a wireless power feeding / receiving circuit 26 and a chirp wave transmitting circuit 27 that are connected to the ultrasonic optical probe 1. The wireless power supply transmission circuit 25 is disposed in the pipe inspection device 2, for example.

  The reference laser light generated from the light source 2a is transmitted from the laser light emitting end 23 and received by the probe laser receiving end 24, thereby being input to the optical fiber sensor 1b. Further, the reference laser light transmitted through the optical fiber sensor 1b that has reached the ultrasonic wave from the pipe 4 is transmitted from the probe laser light emitting end 21 and received by the laser light receiving end 22, so that it is transmitted to the optical interferometer 2b. Is output. The computer 3 determines the state of the pipe 4 based on this reference laser beam.

  Thus, in this embodiment, transmission / reception of a signal (reference laser light) between the ultrasonic optical probe 1 and the pipe inspection device 2 is performed using wireless communication. Therefore, according to this embodiment, it can suppress that the wiring volume of a signal wire | line (optical fiber cable) becomes large locally at the time of construction and operation of a power plant. Therefore, according to the present embodiment, it is possible to easily handle the signal line at the site and reduce the probability that the signal line is disconnected due to an unexpected accident at the site.

  The wireless power supply transmission circuit 25 supplies power to the wireless power supply reception circuit 26 by wireless power supply. This electric power is supplied to the EMAT 1a and used to oscillate ultrasonic waves. Transfer of power between the wireless power supply transmission circuit 25 and the wireless power supply reception circuit 26 is performed by, for example, microwave power transmission or laser power transmission.

  Thus, in this embodiment, power supply to the ultrasonic optical probe 1 is performed using wireless power feeding. Therefore, according to this embodiment, it can suppress that the wiring volume of a power wire (EMAT cable) becomes large in the field at the time of construction of a power plant, or operation. Therefore, according to the present embodiment, it is possible to easily handle the power line at the site and reduce the probability that the power line is disconnected due to an unexpected accident at the site.

  FIG. 5 is a schematic diagram showing the configuration of the probe laser emission end 21 and the laser receiving end 22 of the first embodiment.

  The probe laser emission end 21 includes a lens 21a and an optical amplifier 21b connected to the end of the optical fiber 11 and amplifying the laser beam. The laser receiving end 22 includes a lens 22b and a control device 22b that is disposed in the vicinity of the end of the optical fiber 12 and that controls the waveguide of the laser light. Laser light can be supplied from the ultrasonic optical probe 1 to the pipe inspection device 2 by the laser emitting end 21 and the laser receiving end 22 for the probe.

  The laser emitting end 23 and the probe laser receiving end 24 have the same structure as the probe laser emitting end 21 and the laser receiving end 22, respectively.

  FIG. 6 is a schematic diagram illustrating the configuration of the terminal block 31 according to the first embodiment.

  6 shows a plurality of ultrasonic optical probes 1 attached to a pipe 4, a plurality of probe laser receiving ends 24 connected to these ultrasonic optical probes 1 via an optical fiber 14, and the probes. The terminal block 31 to which the laser receiving end 24 is attached is shown.

  FIG. 6 further shows a laser emission end 23 connected to a pipe inspection apparatus 2 (not shown) via an optical fiber 13. In the present embodiment, one laser emission end 23 corresponds to a plurality of probe laser receiving ends 24.

  When supplying a laser beam to a certain ultrasonic optical probe 1, the pipe inspection device 2 irradiates the laser light receiving end 24 for the probe connected to the ultrasonic optical probe 1 with the laser light from the laser light emitting end 23. Thereby, it is possible to perform piping inspection using the ultrasonic optical probe 1.

  The mechanism for supplying power from the wireless power supply transmission circuit 25 to the wireless power supply reception circuit 26 may be configured using the terminal block 31 or may be configured without using the terminal block 31. The power supply from the wireless power supply transmission circuit 25 to the wireless power supply reception circuit 26 is performed by, for example, microwave power transmission or laser power transmission. In order to use microwaves or laser light, when power is supplied to a specific wireless power receiving circuit 26 among the plurality of wireless power receiving circuits 26, the wireless power receiving circuit 26 is aimed and irradiated with electromagnetic waves. There is an advantage that it is easy to do. In the present embodiment, power may be supplied to the ultrasonic optical probe 1 by directly irradiating the electric coil A2 of the ultrasonic optical probe 1 with microwaves or laser light.

  FIG. 7 is a diagram for explaining an example of wireless power feeding according to the first embodiment.

  The wireless power feeding according to the present embodiment can be performed by, for example, the power feeding method illustrated in FIGS. 7A to 7D.

  FIG. 7A shows an “electromagnetic induction method” using electromagnetic induction in which an electromotive force is generated in a secondary coil adjacent to a magnetic flux generated by passing a current through the primary coil.

  FIG. 7B shows a “magnetic field resonance method” using a magnetic field resonance phenomenon between the primary coil and the secondary coil.

  FIG. 7C shows an “electric field coupling method” using electric field coupling between electrodes.

  FIG. 7D shows a “radio wave reception method” in which current is converted into electromagnetic waves and transmitted / received via an antenna.

  In addition, since the ultrasonic optical probe 1 of this embodiment is provided with the electric coil A2 in the shape of a spiral coil, it can be used as a receiving device for wireless power feeding. In this case, wireless power feeding may be performed by directly irradiating the electric coil A2 with electromagnetic waves (for example, microwaves or laser light).

  FIG. 8 is a diagram for explaining an example of energy harvesting (energy harvesting) according to the first embodiment.

  In the present embodiment, power supply to the ultrasonic optical probe 1 may be performed using an energy harvesting element.

  A region A in FIG. 8 shows the thermoelectric conversion element 41, the heat exchange device 42 connected to the thermoelectric conversion element 41, and the power storage / boosting circuit 43 connected to the thermoelectric conversion element 41.

  The thermoelectric conversion element 41 is attached to the pipe 4 and generates power by converting thermal energy from the pipe 4 into electricity when there is a temperature difference between the pipe 4 and the surroundings. The heat exchanging device 42 supplies heat such as air, steam, water, and underground heat in the power plant to the thermoelectric conversion element 41. In this case, the thermoelectric conversion element 41 generates power by converting the heat energy from the heat exchange device 42 into electricity (in addition, when the thermoelectric conversion element 41 is used in this way, the thermoelectric conversion element 41 is other than the pipe 4. May be attached to the location of). In the present embodiment, a MEMS (Micro Electro Mechanical Systems) turbine may be used instead of the thermoelectric conversion element 41.

  The power storage / boosting circuit 43 stores the power obtained by the thermoelectric conversion element 41 and boosts the voltage. The power storage / boosting circuit 43 is connected to the ultrasonic optical probe 1 and supplies power to the ultrasonic optical probe 1 by wire. The power storage / boosting circuit 43 may supply power to the ultrasonic optical probe 1 using wireless power feeding.

  A region B in FIG. 8 shows the vibration power generation element 51 and the power storage / boosting circuit 52 connected to the vibration power generation element 51.

  The vibration power generation element 51 is attached to the pipe 4 and generates electric power by converting vibration energy of the pipe 4 during operation of the plant into electricity. Examples of the vibration power generation element 51 include a piezoelectric element and an electrostatic element. The configuration of the power storage / boost circuit 52 is the same as that of the power storage / boost circuit 43.

  A region C in FIG. 8 shows the photoelectric conversion element 61 and the power storage / boosting circuit 62 connected to the photoelectric conversion element 61.

  The photoelectric conversion element 61 generates electric power by converting the energy of local sunlight or indoor light into electricity. An example of the photoelectric conversion element 61 is a solar cell. The photoelectric conversion element 61 may be attached to the pipe 4 or may be attached to a place other than the pipe 4. The configuration of the power storage / boost circuit 62 is the same as that of the power storage / boost circuit 43.

  Thus, in the present embodiment, power supply to the ultrasonic optical probe 1 may be performed using energy harvesting. In this case, according to the present embodiment, the ultrasonic optical probe 1 and the energy harvesting element are arranged at a short distance, so that the wiring volume of the power supply line is prevented from becoming large in the field during construction or operation of the power plant. can do. Therefore, according to the present embodiment, it is possible to easily handle the power line at the site and reduce the probability that the power line is disconnected due to an unexpected accident at the site.

(2) Optical fiber sensor 1b of the first embodiment
FIG. 9 is a diagram for explaining a configuration example of the optical fiber sensor 1b according to the first embodiment.

  FIG. 9A shows an optical fiber sensor 1b having the same structure as that of FIG. FIG. 9A shows a tube portion 71 in which the optical fibers 11 and 14 are collectively surrounded, and a fiber portion 72 with a protective coating in which the optical fibers 11 and 14 are separately surrounded.

  On the other hand, FIG. 9B shows an optical fiber sensor 1b corresponding to this modification. Reference numerals B1 and B2 in FIG. 9B indicate first and second ends of the optical fiber sensor 1b, respectively. The first end B1 is connected to a probe laser light emitting / receiving end 75 serving as a light emitting end and a light receiving end via an optical fiber 74 serving both as an input line and an output line for a reference laser beam. . The second end B2 is connected to a reflection end 73 having a reflection surface capable of reflecting the reference laser beam.

  In the optical fiber sensor 1b of FIG. 9B, the reference laser light from the light source 2a is input to the first end B1 via the probe laser emission / light reception end 75. At this time, when the ultrasonic wave reaches the optical fiber sensor 1b in a state where the reference laser beam is input to the optical fiber sensor 1b, a shift of the Doppler frequency and a fluctuation of the polarization plane occur in the reference laser beam.

  The reference laser light travels through the optical fiber sensor 1b toward the second end B2, is reflected by the reflecting surface of the reflection end 73, and returns through the optical fiber sensor 1b toward the first end B1. Go. The reference laser light is output from the first end B1 and supplied to the optical interferometer 2b via the probe laser emission / light reception end 75. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  According to the optical fiber sensor 1b having the structure of FIG. 9B, the two optical fibers 11 and 14 for each ultrasonic optical probe 1 are reduced to one optical fiber 74, and signal lines in the power plant are wired. Volume can be reduced.

  In addition, the structure of FIG.9 (b) is not only when the optical fiber sensor 1b and the pipe inspection apparatus 2 are wirelessly connected, but when the optical fiber sensor 1b and the pipe inspection apparatus 2 are connected by wire. Is also applicable.

  FIG. 10 is a graph showing experimental results of the intensity measurement of the reference laser beam in the cases of FIGS. 9 (a) and 9 (b).

A curve C ₁ shows the detected intensity of the reference laser beam detected by the optical interferometer 2b in the case of FIG. A curve C ₂ shows the detected intensity of the reference laser beam detected by the optical interferometer 2b in the case of FIG. 9B. The test specimen in the experiment of FIG. 10 was a carbon steel SS400 having a thickness of 5 mm and a size of 150 × 150 mm.

  In the case of FIG. 9B, spike-like noise due to base noise time fluctuation overlaps the resonance frequency spectrum, but the same dominant resonance frequency as in FIG. 9A is obtained. Therefore, in the case of FIG. 9B, the thickness of the pipe 4 can be measured as in the case of FIG. 9A.

  Further, as shown in FIG. 10, the vibration intensity of the reference laser light in the case of FIG. 9B is about four times that in the case of FIG. 9A. Therefore, the measurement waveform amplitude of the reference laser beam in the case of FIG. 9B is about twice that in the case of FIG. 9A. This is because the reference laser beam in FIG. 9B reciprocates in the optical fiber sensor 1b, and the reference laser beam in FIG. It is to do.

  Therefore, according to the structure of FIG. 9B, the detection intensity of the reference laser beam can be increased, and the inspection accuracy of the pipe 4 can be improved.

  FIG. 11 is a diagram illustrating a first connection example between the optical fiber sensors 1b of the first embodiment.

  FIG. 11 shows a plurality of (here, four) ultrasonic optical probes 1 attached to the same pipe 4. The optical fiber sensors 1 b of these ultrasonic optical probes 1 are connected to each other in series by an optical fiber 76. Each optical fiber 76 connects the optical fiber sensors 1b adjacent to each other in a single line, and the first end B1 of one optical fiber sensor 1b and the second end B2 of the other optical fiber sensor 1b. It is connected to the. Reference numerals [A] to [D] are assigned to distinguish the ultrasonic optical probes 1 from each other.

  Among these optical fiber sensors 1 b, the first end B 1 of the optical fiber sensor 1 b located at one end (hereinafter referred to as “front end”) is probed laser emitting / receiving via the optical fiber 74. Connected to the end 75. The second end B 2 of the optical fiber sensor 1 b located at the other end (hereinafter referred to as “rear end”) is connected to the reflection end 73. The structures of the reflection end 73, the optical fiber 74, and the probe laser emission / light reception end 75 in FIG. 11 are the same as those in FIG.

  In FIG. 11, the reference laser light from the light source 2a is input to the first end B1 of the optical fiber sensor 1b at the front end via the probe laser emission / light reception end 75. This reference laser beam is also input to the first end B1 of the other optical fiber sensor 1b via the optical fiber 76. At this time, when an ultrasonic wave reaches these optical fiber sensors 1b in a state where the reference laser light is input to these optical fiber sensors 1b, a shift of the Doppler frequency and a fluctuation of the polarization plane occur in the reference laser light.

  The reference laser light travels toward the second end B2 of the optical fiber sensor 1b at the rear end, is reflected by the reflection surface of the reflection end 73, and is the first end B1 of the optical fiber sensor 1b at the front end. Go back towards. The reference laser light is output from the first end B1 of the optical fiber sensor 1b at the front end, and is supplied to the optical interferometer 2b via the probe laser light emitting / receiving end 75. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  According to the connection example of FIG. 11, the eight optical fibers 11 and 14 for the four ultrasonic optical probes 1 are reduced to one optical fiber 74 and three optical fibers 76, and signal lines in the power plant. The wiring volume can be reduced.

  In general, the length of the optical fiber 76 is shorter than the length of the optical fiber 74. Therefore, according to the connection example of FIG. 11, the wiring volume can be reduced as compared with the case where the four optical fibers 74 are connected to the four ultrasonic optical probes 1 without adopting the series connection. The effect of reducing the wiring volume in the connection example of FIG. 11 increases as the number of ultrasonic optical probes 1 connected in series increases.

  Next, details of the pipe inspection method in the connection example of FIG. 11 will be described.

  In the connection example of FIG. 11, the same reference laser light is used for the four ultrasonic optical probes 1. Therefore, it can be determined whether or not the pipe 4 has deteriorated at the four places where the four ultrasonic optical probes 1 are installed. In general, it cannot be specified where the pipe 4 is deteriorated. For example, although the maximum value of the thinning amount of the pipe 4 at four locations can be measured, it is generally not possible to specify which portion the thinning amount is the maximum value.

  However, at the site of the pipe inspection, it is often sufficient to know which range of the pipe 4 is deteriorated without knowing which part of the pipe 4 is deteriorated. In such a case, it is considered that there is a great need for the connection example of FIG.

  In addition, in the connection example of FIG. 11, when it is desired to specify a deteriorated portion of the pipe 4, the vibration outputs of the four ultrasonic optical probes 1 are differentiated from each other, and the vibration outputs of the four ultrasonic optical probes 1 are differentiated from each other. May be. This can be realized by, for example, combining the combination of the number of turns of the ultrasonic optical probe 1, the winding direction of the coil, and the exciting force of the electromagnet with a unique combination for each ultrasonic optical probe 1. . In this case, by analyzing the detection data of the reference laser light, it is possible to grasp the position of the ultrasonic optical probe 1 where the pipe 4 is deteriorated.

  FIG. 12 is a cross-sectional view and a side view showing details of a first connection example between the optical fiber sensors 1b of the first embodiment.

  12 (a) and 12 (b) show that four rows of ultrasonic optical probes 1 are installed in a pipe 4 having a size of 150A or more in accordance with the JSME power generation equipment standard for power generation (JSME S CA1-2009). An example is shown. Each row includes eight ultrasonic optical probes 1 at equal intervals. The distance between these columns is set to the same value as the diameter (outer diameter) φ of the pipe 4. FIG. 12A is a cross-sectional view showing one row of ultrasonic optical probes 1. FIG. 12B is a side view showing the four rows of ultrasonic optical probes 1.

  In FIG. 12, the optical fiber sensors 1 b of the eight ultrasonic optical probes 1 constituting one row are connected to each other in series by an optical fiber 76. According to such a configuration, the presence or absence of deterioration of the pipe 4 can be grasped in units of columns (per unit of circumference).

  FIG. 13 is a diagram illustrating a second connection example of the optical fiber sensors 1b according to the first embodiment.

  In the connection example of FIG. 13, the optical fiber sensors 1b of the four ultrasonic optical probes 1 are connected to each other in series as in the connection example of FIG. However, in the connection example of FIG. 13, the tube portion 71 has the same structure as that of FIG. 11, whereas the fiber portion 72 with protective coating has the same structure as that of FIG.

  In the connection example of FIG. 13, a circulator 77 is installed between the tube portion 71 and the fiber portion 72 with a protective coating. The circulator 77 is installed to distinguish between the reference laser beam for going and returning. An example of the circulator 77 is a polarizing plate.

  For example, the reference laser light that has reached the circulator 77 from the fiber portion 72 with the protective coating on the light receiving end 24 side passes through the tube portion 71 but does not pass through the fiber portion 72 with the protective coating on the light emitting end 21 side. .

  In addition, the reference laser beam returned from the tube portion 71 to the circulator 77 is transmitted through the protective-coated fiber portion 72 on the light emitting end 21 side, but not transmitted through the protective-coated fiber portion 72 on the light receiving end 24 side. .

  According to the connection example of FIG. 13, it is possible to prevent the outgoing reference laser light from propagating to the light emitting end 21 and the returning reference laser light from propagating to the light receiving end 24.

  FIG. 14 is a diagram illustrating a third connection example of the optical fiber sensors 1b according to the first embodiment.

  In the connection example of FIG. 14, the optical fiber 74 is branched into optical fibers 74 a and 74 b at the point of the distributor 78. The optical fiber sensors 1b of the two ultrasonic optical probes 1 are connected to each other in parallel by optical fibers 74a and 74b. The first end B1 of each optical fiber sensor 1b is connected to one of the optical fibers 74a and 74b. The second end B2 of each optical fiber sensor 1b is connected to one of the two reflection ends 73. The structures of the reflection end 73 and the probe laser emission / light reception end 75 in FIG. 14 are the same as those in FIG. 9B.

  In FIG. 14, the reference laser light from the light source 2 a is input to the distributor 78 via the probe laser emission / light receiving end 75 and is divided by the distributor 78. The divided reference laser light is input to the first ends B1 of the two optical fiber sensors 1b. At this time, when an ultrasonic wave reaches these optical fiber sensors 1b in a state where the reference laser light is input to these optical fiber sensors 1b, a shift of the Doppler frequency and a fluctuation of the polarization plane occur in the reference laser light.

  The reference laser light travels toward the second end B2 of the two optical fiber sensors 1b, is reflected by the reflection surface of the reflection end 73, and travels toward the first end B1 of the two optical fiber sensors 1b. Go back. The reference laser light is output from the first end B1 of these optical fiber sensors 1b and supplied to the optical interferometer 2b through the distributor 78 and the probe laser emission / light reception end 75. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  According to the connection example of FIG. 14, the four optical fibers 11 and 14 for the two ultrasonic optical probes 1 are reduced to one optical fiber 74 branched into optical fibers 74a and 74b, and the signal in the power plant is reduced. The wiring volume of the line can be reduced.

  In the connection example of FIG. 14, the optical fiber sensors 1b of three or more ultrasonic optical probes 1 may be connected in parallel to each other. The details of the pipe inspection method in the connection example of FIG. 14 are the same as those of the connection example of FIG.

  In addition, the structure of FIGS. 11-14 is not only when the optical fiber sensor 1b and the pipe inspection apparatus 2 are wirelessly connected, but when the optical fiber sensor 1b and the pipe inspection apparatus 2 are connected by wire. Is also applicable.

(3) EMAT 1a of the first embodiment
FIG. 15 is a diagram illustrating a first connection example between the EMATs 1a according to the first embodiment.

  FIG. 15 shows a plurality (four in this case) of ultrasonic optical probes 1 attached to the same pipe 4. The EMATs 1 a of these ultrasonic optical probes 1 are connected to each other in series by a power line 16. Each power line 16 connects the EMATs 1a adjacent to each other in a single line. Reference numerals [A] to [D] are assigned to distinguish the ultrasonic optical probes 1 from each other.

  Of these EMAT1a, EMAT1a located at one end (hereinafter referred to as "front end") is connected to the first terminal 27a of the chirp wave transmission circuit 27 (FIG. 4) via the power line 15. . The EMAT 1 a located at the other end (hereinafter referred to as “rear end”) is connected to the second terminal 27 b of the chirp wave transmission circuit 27 via the power line 15. In FIG. 15, a high frequency current flows from the first terminal 27a to the second terminal 27b via the power supply lines 15 and 16, whereby electric power is supplied to the four EMATs 1a.

  According to the connection example of FIG. 15, the eight power lines 15 for the four ultrasonic optical probes 1 are reduced to two power lines 15 and three power lines 16, and the wiring of the power lines in the power plant is performed. Volume can be reduced.

  In general, the length of the power supply line 16 is shorter than the length of the power supply line 15. Therefore, the effect of reducing the wiring volume in the connection example of FIG. 15 increases as the number of ultrasonic optical probes 1 connected in series increases.

  Next, details of the pipe inspection method in the connection example of FIG. 15 will be described.

  Four EMAT1a are installed in order to give fixed vibration to the piping 4. FIG. When current flows from the first terminal 27a to the second terminal 27b in FIG. 15, these EMATs 1a vibrate the pipe 4 simultaneously. As a result, the four optical fiber sensors 1b expand and contract slightly, and the Doppler frequency shift and the polarization plane fluctuation occur in the reference laser light in these optical fiber sensors 1b. The computer 3 determines the state of the pipe 4 based on the detection result of the reference laser light.

  The four optical fiber sensors 1b in FIG. 15 are not connected to each other in series or in parallel, but are connected to the optical fibers 11 and 14 individually. Therefore, according to the connection example of FIG. 15, by detecting which optical fiber sensor 1b the reference laser beam has changed, it is possible to specify at which location the pipe 4 is deteriorated.

  However, the four optical fiber sensors 1b may be connected to each other in series or in parallel as shown in FIGS. In this case, it is possible to determine that the piping 4 has deteriorated in the installation range of these optical fiber sensors 1b by detecting changes in the reference laser light transmitted through these optical fiber sensors 1b. In this case, the vibration outputs of the four EMATs 1a are differentiated from each other, thereby making it possible to grasp the position of the ultrasonic optical probe 1 in which the pipe 4 has deteriorated.

  FIG. 16 is a diagram illustrating a second connection example of the EMATs 1a according to the first embodiment.

  In the connection example of FIG. 16, as in the connection example of FIG. 15, the EMATs 1a of the four ultrasonic optical probes 1 are connected to each other in series. However, in the connection example of FIG. 16, EMATs 1 a adjacent to each other are connected by two power supply lines 16. An example of one power supply line 16 is a Vcc wiring, and an example of the other power supply line 16 is a Vss wiring.

  Of these EMAT 1 a, EMAT 1 a located at the front end is connected to the first and third terminals 27 a and 27 c of the chirp wave transmission circuit 27 via the two power lines 15. The EMAT 1 a located at the rear end is connected to the second and fourth terminals 27 b and 27 d of the chirp wave transmission circuit 27 via the two power supply lines 15. Examples of these power supply lines 15 are Vcc wiring and Vss wiring.

  FIG. 17 is a diagram illustrating a third connection example of the EMATs 1a according to the first embodiment.

  In the connection example of FIG. 17, each power line 15 is branched into power lines 15a and 15b. The EMATs 1a of the two ultrasonic optical probes 1 are connected to each other in parallel by power supply lines 15a and 15b. In FIG. 17, the high frequency current flows from the first terminal 27a through the power supply line 15 to the second terminal 27b, whereby electric power is supplied to the two EMATs 1a.

  According to the connection example of FIG. 17, the four power lines 15 for the two ultrasonic optical probes 1 are reduced to two optical fibers 74 branched to the power lines 15a and 15b, and the power lines in the power plant are reduced. The wiring volume can be reduced.

  In the connection example of FIG. 17, the EMATs 1a of three or more ultrasonic optical probes 1 may be connected in parallel to each other. In the connection example of FIG. 17, the optical fiber sensors 1b may be connected to each other in series or in parallel. The details of the pipe inspection method in the connection example of FIG. 17 are the same as those of the connection example of FIG.

  15 to 17 can be applied not only when the EMAT 1a and the wireless power transmission circuit 25 are wirelessly connected, but also when the EMAT 1a and the wireless power transmission circuit 25 are connected by wire. is there. In addition, the wireless power feeding transmission circuit 25 may be replaced with the energy harvesting element shown in FIG.

(4) Modification of Ultrasonic Optical Probe 1 of First Embodiment The ultrasonic optical probe 1 of this embodiment includes an EMAT 1a that functions as a vibration source and an optical fiber sensor 1b that functions as a sensor. However, in this embodiment, the function of the excitation source may be separated from the ultrasonic optical probe 1. In this case, the ultrasonic optical probe 1 includes only the optical fiber sensor 1b and does not include the EMAT 1a. Hereinafter, an example of such an ultrasonic optical probe 1 will be described with reference to FIGS. 18 and 19.

  FIG. 18 is a cross-sectional view showing a first modification of the ultrasonic optical probe 1 of the first embodiment.

  FIG. 18 shows a pipe 4, a heat insulating material (heat insulating material) 5, and eight optical fiber sensors 1 b embedded between the pipe 4 and the heat insulating material 5. These optical fiber sensors 1b may be connected to each other in series or in parallel. These optical fiber sensors 1b may be connected to the reflection end 73.

  FIG. 18 further shows a large electromagnetic ultrasonic oscillator (hereinafter referred to as “large EMAT”) 6 arranged outside the pipe 4. Unlike the above-described EMAT 1a, the large EMAT 6 is separated from the optical fiber sensor 1b. An example of the large EMAT 6 is a piezo element. In this modification, the pipe 4 can be vibrated by the large EMAT 6 as indicated by an arrow A by bringing the large EMAT 6 into contact with the heat insulating material 5 or installing it near the heat insulating material 5.

  When the large EMAT 6 vibrates, ultrasonic waves from the large EMAT 6 reach the optical fiber sensor 1b via the pipe 4. At this time, when the ultrasonic wave reaches the optical fiber sensor 1b in a state where the reference laser light from the light source 2a is input to the optical fiber sensor 1b, a shift of the Doppler frequency and a fluctuation of the polarization plane occur in the reference laser light. This reference laser beam is output from the optical fiber sensor 1b and supplied to the optical interferometer 2b. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  According to this modification, it is not necessary to attach the ultrasonic optical probe 1 including the EMAT 1 a and the optical fiber sensor 1 b to the pipe 4, and it is sufficient to attach the optical fiber sensor 1 b to the pipe 4. It is possible to save labor for attaching the sonic optical probe 1 (optical fiber sensor 1b).

  FIG. 19 is a cross-sectional view showing a second modification of the ultrasonic optical probe 1 of the first embodiment.

  FIG. 19 shows the pipe 4, the heat insulating material 5, and the eight optical fiber sensors 1 b as in FIG. 18. FIG. 19 further shows the working fluid 7 flowing through the pipe 4. An example of the working fluid 7 is a liquid such as water. Depending on the flow velocity, type, state, and the like of the working fluid 7 that flows through the pipe 4, the pipe 4 vibrates at high frequency due to the influence of the working fluid 7. In this modification, the phenomenon that the flow of the working fluid 7 vibrates the pipe 4 is used for pipe inspection. Symbols B and C in FIG. 19B indicate the flow of the working fluid 7 and the vibration of the pipe 4, respectively.

  When the working fluid 7 flows in the pipe 4, the ultrasonic waves generated in the pipe 4 due to the influence of the working fluid 7 reach the optical fiber sensor 1b. At this time, when the ultrasonic wave reaches the optical fiber sensor 1b in a state where the reference laser light from the light source 2a is input to the optical fiber sensor 1b, a shift of the Doppler frequency and a fluctuation of the polarization plane occur in the reference laser light. This reference laser beam is output from the optical fiber sensor 1b and supplied to the optical interferometer 2b. The computer 3 can determine the state of the pipe 4 based on the detection result of the reference laser beam by the optical interferometer 2b.

  According to this modification, it is not necessary to attach the ultrasonic optical probe 1 including the EMAT 1 a and the optical fiber sensor 1 b to the pipe 4, and it is sufficient to attach the optical fiber sensor 1 b to the pipe 4. It is possible to save labor for attaching the sonic optical probe 1 (optical fiber sensor 1b).

  Furthermore, according to the present modification, it is not necessary to prepare a large EMAT 6, and therefore it is possible to further save labor for pipe inspection.

(5) Chirp wave transmission circuit 27 of the first embodiment
Next, the chirp wave transmission circuit 27 of FIG. 4 will be described.

  In this embodiment, in order to obtain resonance in the thickness direction of the pipe 4, the oscillation frequency of the EMAT 1a is swept (swept) according to the resolution. This sweep process takes a certain sweep time corresponding to the resolution. If the sweep time is long, the time required for pipe inspection becomes long.

  Therefore, in this embodiment, the chirp wave transmission circuit 27 is connected to the EMAT 1a so that a chirp wave including a desired frequency band from a certain frequency to a certain frequency can be oscillated. Therefore, according to the present embodiment, the EMAT 1a oscillates a chirp wave as an ultrasonic wave, so that the resonance frequency can be detected in a short time by a minute resonance by the chirp wave, and the pipe inspection time can be shortened.

(6) Pipe Inspection Method of First Embodiment FIG. 20 is a diagram for explaining the pipe inspection method of the first embodiment.

Fig.20 (a) shows the piping 4 which consists only of the piping preform | base_material 4a. Symbols d ₁ , E ₁ , and ρ ₁ indicate the thickness, longitudinal elastic modulus, and density of the pipe base material 4a.

FIG. 20B shows the pipe 4 in which the pipe deposit 4b, which is a different material from the pipe base 4a, is attached to the inner surface of the pipe base 4a. Reference signs d ₂ , E ₂ , and ρ ₂ indicate the thickness, longitudinal elastic modulus, and density of the pipe deposit 4b. Examples of the pipe deposit 4 include a scale attached to the inner surface of the pipe base material 4a, a coating on the inner surface of the pipe base material 4a, and rust generated on the inner surface of the pipe base material 4a.

FIG. 20C shows the pipe 4 in which the pipe 4 in FIG. 20B is considered to be formed of a mixed material 4c of the material of the pipe member 4a and the material of the pipe deposit 4b. Reference sign d ₃ indicates the thickness of the pipe 4 and corresponds to the total thickness of the pipe base material 4a and the pipe deposit 4b (d ₃ = d ₁ + d ₂ ). The symbols E _equ and ρ _equ indicate the equivalent longitudinal elastic modulus and equivalent density of the pipe 4.

  Hereinafter, the pipe inspection method of the first embodiment will be described based on the result of the pipe inspection actually performed on the pipe 4 in the power plant.

  First, an analysis result obtained by analyzing the measurement result of the pipe 4 with the model of FIG.

The wall thickness d ₁ of the pipe base material 4a was 9.873 mm from the measurement result with a micrometer. Moreover, the speed of sound in the pipe preform 4a was 5419 m / sec based on the measurement results obtained by the micrometer and the optical fiber EMAT method. Based on these values, the resonance frequency when the pipe 4 is composed only of the pipe base material 4a is 274.4 kHz, which is different from the measurement result of 269.9 kHz by the optical fiber EMAT method. .

  From this result, the measurement result of the resonance frequency is deviated from the resonance frequency when the pipe 4 is composed only of the pipe base material 4a, reflecting that the pipe deposit 4b is attached to the inner surface of the pipe base material 4a. I can confirm that.

  Next, an analysis result obtained by analyzing the measurement result of the pipe 4 with the model of FIG. 20B will be described. However, in this analysis, it was assumed that the pipe deposit 4b is made of the same material as the pipe member 4a.

The wall thickness d ₁ + d ₂ of the pipe 4 was 10.96 mm from the measurement result with a micrometer. The sound speed in the pipe 4 is assumed to be the same as the sound speed in the pipe base material 4a, and is set to 5419 m / sec. Based on these values, the resonance frequency when the pipe deposit 4b adheres to the inner surface of the pipe base 4a is calculated to be 247.2 kHz, which is different from the measurement result of the optical fiber EMAT method, 269.9 kHz. As a result. This is the same when it is assumed that the pipe base material 4a is made of the same material as the pipe deposit 4b.

  From this result, when analyzing the resonance frequency of the pipe 4 with the pipe deposit 4b attached to the inner surface of the pipe base material 4a, it is assumed that the pipe deposit 4b is made of the same material as the pipe member 4a. Can be confirmed.

  Therefore, in this embodiment, when analyzing the pipe 4 having the pipe deposit 4b attached to the inner surface of the pipe base material 4a, it is assumed that the pipe deposit 4b is made of a material different from that of the pipe member 4a. Furthermore, in the present embodiment, it is assumed that the pipe 4 is made of a mixed material 4c of the material of the pipe member 4a and the material of the pipe deposit 4b. That is, in the present embodiment, the model shown in FIG.

Hereinafter, the equivalent longitudinal elastic modulus E _equ and the equivalent density ρ _equ of the model of FIG. 20C will be described, and further, the resonance frequency in the model of FIG. 20C will be described.

ただし、符号ｄ、Ｅは、配管４の肉厚、縦弾性係数を示し、符号Ｓは、荷重Ｐが付与される面積を示す。 When the pipe 4 is made of a single material, the elongation λ of the pipe 4 when the load P is applied to the pipe 4 is given by the following formula (1).

However, the code | symbols d and E show the thickness and longitudinal elastic modulus of the piping 4, and the code | symbol S shows the area where the load P is provided.

ここで、図２０(ｂ)のモデルにおける配管４のひずみエネルギーＵ_compは、配管母材４ａのひずみエネルギーＵ₁と、配管付着物４ｂのひずみエネルギーＵ₂との合計と考えることができる。よって、図２０(ｂ)の配管４のひずみエネルギーＵ_compは、次の式（３）で与えられる。

また、図２０(ｃ)のモデルにおける配管４のひずみエネルギーＵ_equは、式（２）にｄ＝ｄ₁＋ｄ₂やＥ＝Ｅ_equを代入することにより、次の式（４）で与えられる。

ここで、図２０(ｃ)のモデルにおける配管４内の等価音速ｖ_equは、等価縦弾性係数Ｅ_equと等価密度ρ_equとを用いて、次の式（５）で与えられる。

式（５）に含まれる等価縦弾性係数Ｅ_equと等価密度ρ_equに関し、等価縦弾性係数Ｅ_equは、Ｕ_comp＝Ｕ_equという関係式に式（３）、式（４）を代入することで算出可能である。また、等価密度ρ_equは、図２０(ｃ)の配管４の質量が、配管母材４ａと配管付着物４ｂの合計質量に等しいという次の式（６）により算出可能である。

ここで、配管４が単一材料からなる場合において、配管４のＮ次の共振周波数ｆ（Ｎ）は、配管４の肉厚ｄと配管４内の音速ｖとを用いて、次の式（７）で与えられる。

ただし、Ｎは正の整数である。なお、本明細書中のここより以前の説明中における共振周波数は、１次の共振周波数であったことに留意されたい。 Further, the strain energy U of the pipe 4 when the load P is applied to the pipe 4 is given by the following formula (2) by calculation using the formula (1).

Here, strain energy U _comp of the pipe 4 in the model of FIG. 20 (b), an energy U ₁ strain of the pipe base material 4a, can be considered as the sum of the strain energy U ₂ pipe deposits 4b. Therefore, the strain energy U _comp of the pipe 4 in FIG. 20B is given by the following equation (3).

Further, the strain energy U _equ of the pipe 4 in the model of FIG. 20C is given by the following equation (4) by substituting d = d ₁ + d ₂ or E = E _equ into the equation (2). .

Here, the equivalent sound velocity v _equ in the pipe 4 in the model of FIG. 20C is given by the following equation (5) using the equivalent longitudinal elastic modulus E _equ and the equivalent density ρ _equ .

Regarding the equivalent longitudinal elastic modulus E _equ and equivalent density ρ _equ included in Equation (5), the equivalent longitudinal elastic modulus E _equ is obtained by substituting Equation (3) and Equation (4) into the relational expression U _comp = U _equ. Can be calculated. Further, the equivalent density ρ _equ can be calculated by the following equation (6) that the mass of the pipe 4 in FIG. 20C is equal to the total mass of the pipe base material 4a and the pipe deposit 4b.

Here, when the pipe 4 is made of a single material, the Nth-order resonance frequency f (N) of the pipe 4 is expressed by the following equation (4) using the thickness d of the pipe 4 and the sound velocity v in the pipe 4 7).

However, N is a positive integer. It should be noted that the resonance frequency in the description before this part of the present specification was the primary resonance frequency.

よって、配管付着物４ｂの肉厚ｄ₂は、配管母材４ａの肉厚ｄ₁、配管母材４ａの物性値Ｅ₁、ρ₁、配管付着物４ｂの物性値Ｅ₂、ρ₂が分かれば、配管４のいずれか１つの次数の共振周波数ｆ（Ｎ）を計測することで算出できる。 The Nth-order resonance frequency of the pipe 4 in the model of FIG. 20C is given by the following equation (8) by substituting equation (5) into equation (7).

Therefore, the thickness d ₂ of the pipe deposits. 4b, the thickness d ₁ of the pipe base material 4a, physical properties E ₁ of the pipe base material 4a, [rho _1, physical properties E ₂ of pipe deposits 4b, [rho ₂ is known For example, it can be calculated by measuring the resonance frequency f (N) of any one order of the pipe 4.

However, it is also assumed that any one of the thickness d _{1 of} the pipe base material 4a, the physical property values E ₁ and ρ _{1 of} the pipe base material 4a, and the physical property values E ₂ and ρ ₂ of the pipe deposit 4b is unknown. For example, it is considered that the physical property values E ₂ and ρ ₂ of the pipe deposit 4b are often unknown.

Hereinafter, _first to fourth examples of the pipe inspection method according to the first embodiment that can calculate the thickness d ₁ of the pipe base material 4a even in such a situation will be described. Note that examples of the physical property values of the pipe 4 include Poisson's ratio and the like in addition to the longitudinal elastic modulus (E ₁ , E ₂ ) and the density (ρ ₁ , ρ ₂ ).

[First example]
21 and 22 are graphs for explaining a first example of the pipe inspection method according to the first embodiment.

In FIG. 21, the peak of the curve C ₁ shows the resonance frequency of the pipe 4 before the pipe deposit 4b adheres to the pipe base material 4a, and the peak of the curve C ₂ shows the pipe deposit 4b on the pipe base material 4a. The resonance frequency of the pipe 4 after adhering is shown. Thus, when the pipe deposit 4b adheres to the pipe base material 4a, the resonance frequency of the pipe 4 shifts to the low frequency side.

In the measurement of the resonance frequency when the pipe deposits 4b to the pipe base material 4a is attached, the resonance frequency of the pipe base material 4a on the basis of the peak of the curve C ₁ is measured, the entire pipe 4 on the basis of the peak of the curve C ₂ The resonance frequency (hereinafter simply referred to as “the resonance frequency of the pipe 4”) is measured. The resonance frequency of the pipe 4 corresponds to the resonance frequency of the above equation (8).

Therefore, in this embodiment, K values among the thickness d _{1 of} the pipe base material 4a, the physical property values E ₁ and ρ _{1 of} the pipe base material 4a, and the physical property values E ₂ and ρ ₂ of the pipe deposit 4b are as follows. If unknown (K is a positive integer), the resonance frequency of the pipe 4 is measured for K + 1 orders. For example, the primary to K + 1 order resonance frequencies of the pipe 4 are measured.

Next, the measurement result of K + 1 resonance frequencies is substituted into Expression (8). As a result, K + 1 equations including the thickness d ₂ of the pipe deposit 4a and other K variables are obtained. That is, K + 1 equations including K + 1 variables are obtained.

Next, the K + 1 equations are solved as simultaneous equations, and the thickness d ₂ of the pipe deposit 4a is calculated. At this time, values of K variables other than the wall thickness d ₂ may also be calculated.

22A shows the relationship between d ₂ and f (N) calculated from equation (8), and FIG. 22B shows E ₂ and f (N) calculated from equation (8). Shows the relationship.

Thus, the longitudinal elastic modulus E ₂ of the pipe deposit 4b is nonlinearly dependent on the resonance frequency f (N). That is, the longitudinal elastic modulus E ₂ is a nonlinear function of the resonance main fraction f (N). Thereby, the K + 1 equations including the longitudinal elastic modulus E ₂ are linearly independent from each other. Therefore, the K + 1 equations can be solved as simultaneous equations, and the thickness d ₂ of the pipe deposit 4a can be calculated.

[Second example]
FIG. 23 is a diagram for explaining a second example of the pipe inspection method according to the first embodiment.

FIG. 23 shows the pipe 4 in which the pipe deposit 4b, which is a different material from the pipe base 4a, is attached to the inner surface of the pipe base 4a. FIG. 23 shows the thickness d ₁ of the pipe base material 4a, the thickness d ₂ of the pipe deposit 4b, and the total thickness d _{3 of} the pipe member 4a and the pipe deposit 4b (d ₃ = d ₁ + d ₂ ).

When the thickness measurement of the pipe 4 in FIG. 23 is performed, it is estimated that the _first to third resonance frequencies f _{1 to} f ₃ are detected.

The first resonance frequency f ₁ is a resonance frequency of resonance generated in the pipe base material 4a. From the thickness d ₁ of the pipe base material 4a and the sound velocity v ₁ in the pipe base material 4a, f ₁ = v ₁ / is given by 2d _1.

The second resonance frequency f ₂ is a resonance frequency of resonance generated in the pipe deposit 4b, and f ₂ = v ₂ from the thickness d ₂ of the pipe deposit 4b and the sound velocity v ₂ in the pipe deposit 4b. / is given by 2d _2.

The third resonance frequency f ₃ is a resonance frequency of resonance generated in the entire pipe 4, and is the total thickness d ₃ of the pipe base material 4 a and the pipe deposit 4 b, and the pipe base material 4 a and the pipe deposit 4 b. From the average sound velocity v ₃ , f ₃ = v ₃ / 2d ₃ is given.

Note that the orders of the _first to third resonance frequencies f _{1 to} f ₃ of the present embodiment are all primary, but may be secondary or higher.

式（９）にｄ₃＝ｄ₁＋ｄ₂を代入すると、平均音速ｖ₃は、次の式（１０）のように与えられる。

また、式（１０）をｆ₃＝ｖ₃／２ｄ₃に代入すると、第３の共振周波数ｆ₃は、次の式（１１）のように与えられる。

一般に、配管母材４ａの材質は既知であるため、配管母材４ａの材質から音速ｖ₁を算出可能である。よって、第１の共振周波数ｆ₁を測定できれば、ｆ₁＝ｖ₁／２ｄ₁の式を用いて、肉厚ｄ₁を導出することができる。 Here, the sum of the ultrasonic wave propagation time d ₁ / v ₁ in the pipe base material 4 a and the ultrasonic wave propagation time d ₂ / v ₂ in the pipe deposit 4 b is equal to the ultrasonic wave in the pipe 4. Since the total propagation time of sound waves is equal to d ₃ / v ₃ , the following equation (9) is obtained.

By substituting d ₃ = d ₁ + d ₂ into equation (9), the average sound velocity v ₃ is given by the following equation (10).

Further, when Expression (10) is substituted into f ₃ = v ₃ / 2d ₃ , the third resonance frequency f ₃ is given by the following Expression (11).

In general, since the material of the pipe base material 4a is known, the sound velocity v ₁ can be calculated from the material of the pipe base material 4a. Therefore, if the first resonance frequency f ₁ can be measured, the thickness d ₁ can be derived using the formula f ₁ = v ₁ / 2d ₁ .

On the other hand, the material of the pipe deposits 4b because normally can not be known, it is impossible to calculate the speed of sound v _2. However, if the second and third resonance frequencies f ₂ and f ₃ can be measured, the equation f ₂ = v ₂ / 2d ₂ and f ₃ = v ₁ v ₂ / (v ₂ d ₁ + v ₁ d ₂ ) / The thickness d ₂ can be derived using the equation 2 and the derived result of the thickness d ₁ .

Therefore, in the second example of the present embodiment, when the ultrasonic frequency is swept when measuring the thickness of the pipe 4, the ultrasonic frequency band is set to the first resonance frequency f ₁ and the second resonance frequency f _2. , And the third resonance frequency f ₃ is set to be detected. That is, the frequency sweep is continued until _three of the _first to third resonance frequencies f _{1 to} f ₃ are detected. Thereby, according to this embodiment, it becomes possible to determine the adhesion state of the pipe deposit 4b from the spectrum shape and intensity of the _first to third resonance frequencies f _{1 to} f ₃ .

The processing determines the attachment state of the first to third resonance frequency f ₁ ~f ₃ detected and piping deposits 4b is also applicable when using the chirp wave as an ultrasonic.

[Third example]
FIG. 24 is a diagram for explaining a third example of the pipe inspection method according to the first embodiment.

In the third example of the present embodiment, a relationship between d ₁ , E ₁ , ρ ₁ , E ₂ , ρ ₂ and f (N) is derived in advance by numerical calculation using the simulation model shown in FIG. Then, functions and tables indicating this relationship are stored in the computer 3. Examples of such numerical calculations include modal analysis and frequency response analysis. FIG. 24 shows a state of simulation in which a load P is applied to the pipe 4 to cause a resonance mode.

According to the third example of the present embodiment, as in the first example, the thickness d ₂ of the pipe deposit 4b can be calculated by measuring the resonance frequency of the pipe 4 for a plurality of orders. it can. If the relationship between d ₁ , E ₁ , ρ ₁ , E ₂ , ρ ₂ and f (N) is held as a function, a plurality of equations are solved as simultaneous equations as in the first example. that is, the wall thickness d ₂ of pipe deposits 4a is calculated. These equations can be derived by substituting the measurement results of a plurality of orders f (N) into the above function.

  In addition, you may acquire said function by the experiment which actually measures the resonant frequency of the piping 4, instead of acquiring by simulation like the 3rd example of this embodiment. The acquired function is stored in advance in the computer 3 before measuring the thickness of the pipe 4.

[Fourth example]
FIG. 25 is a flowchart for explaining a fourth example of the pipe inspection method according to the first embodiment.

FIG. 25 shows a flow of simulation for obtaining a function representing the relationship between the Nth-order resonance frequency f (N) of the pipe 4 and variables (for example, d ₁ , E ₁ , ρ ₁ , E ₂ , ρ ₂ ). Show. This corresponds to a specific example of the simulation of the third example. The simulation of the fourth example is executed by an information processing apparatus such as a large computer.

  First, a numerical analysis model of the pipe 4 is constructed (step S1). Specifically, as shown in FIGS. 23 and 24, a model of the pipe 4 is constructed in which the pipe deposit 4b adheres to the inner surface of the pipe base material 4a. Hereinafter, this model is referred to as a “piping model”. For example, a numerical analysis tool using a finite element method is used to construct the piping model.

  Next, the values of variables such as boundary conditions, physical properties, dimensions, etc. of the piping model are set (step S2). At this time, it is desirable that the values of these variables be set to practical values in order to construct a simulation model that can respond immediately to the actual piping 4.

  Next, ultrasonic analysis using a piping model is performed (steps S3 to S6). Specifically, the ultrasonic characteristics peculiar to this piping model are calculated by numerical analysis using the finite element method.

In the ultrasonic analysis, first, a modal analysis for calculating the mode of the piping model is executed (step S3). FIG. 26 is a cross-sectional view for explaining the modal analysis of the fourth example. In the modal analysis, various vibration modes of the piping model are calculated. FIG. 26 shows, as an example of such a vibration mode, a resonance mode of the ultrasonic wave W ₁ propagating in the thickness direction of the pipe 4 and a resonance mode of the ultrasonic wave W ₂ propagating along the outer surface of the pipe 4. ing. According to the modal analysis, it is possible to visually confirm what resonance mode occurs in the piping model, and it is possible to roughly calculate the resonance frequency of the resonance mode.

  Next, frequency response analysis for calculating the frequency response of the piping model is executed (step S4). FIG. 27 is a cross-sectional view for explaining the frequency response analysis of the fourth example. In the frequency response analysis, a standing wave generated in the piping model is calculated when the piping model is continuously vibrated at a constant frequency. FIG. 27 shows a state in which a vibration force F is applied to the outer surface of the pipe 4 to continuously vibrate the pipe 4 in the thickness direction at a constant frequency. As a result, a standing wave W propagating in the thickness direction of the pipe 4 is generated.

  The frequency response analysis of the present embodiment is executed to calculate a standing wave that propagates in the thickness direction, such as the standing wave W in FIG. Therefore, in order to efficiently execute the frequency response analysis, the vibration frequency of the excitation force F is swept in small increments in a frequency band close to the resonance frequency of the resonance mode propagating in the thickness direction calculated by the modal analysis. This makes it possible to calculate a standing wave propagating in the thickness direction in a short time.

  Next, a time history response analysis for calculating a time history response of the piping model is executed (step S5). In the time history response analysis, when the vibration of the piping model is stopped after the piping model is continuously vibrated at a constant frequency to generate ultrasonic waves (stationary waves), the process of the time change of the ultrasonic waves is calculated. The

  FIG. 28 is a graph for explaining the time history response analysis of the fourth example.

The horizontal axis in FIG. 28 indicates time. The vertical axis in FIG. 28 indicates the drive voltage V ₁ of the EMAT 1a and the output voltage V of the optical fiber sensor 1b when it is assumed that the ultrasonic optical probe 1 is installed at the point of application of the excitation force F in FIG. ₂ is shown. In FIG. 28, it is assumed that the excitation force F is applied by the EMAT 1a and the ultrasonic wave is measured by the optical fiber sensor 1b.

In the time history response analysis of FIG. 28, the drive voltage V _{1 of the} EMAT 1a is a burst wave having a constant frequency. The application of this burst wave is started at time t ₁ and stopped at time t ₂ . From time t _{1 to} t ₂ , the piping model vibrates at a constant frequency, and a standing wave is generated in the piping model. Therefore, the time t ₁ ~t _2, the output voltage V ₂ of the optical fiber sensor 1b is largely vibrated. The value of time t _{1 to} t _{2 in} FIG. 28 is 1 ms.

When the application of the burst wave is stopped at time t ₂ , as indicated by the symbol R, the output voltage V ₂ of the optical fiber sensor 1 b is attenuated. Symbol R corresponds to reverberation of a standing wave. In the time history ultrasonic response analysis of FIG. 28, the vibration amplitude of the reverberation R is measured from time t ₃ to time t ₄ after the burst wave application is stopped, and the square integral value (sum) of the vibration amplitude is calculated. The value of time t ₂ ~t ₃ in FIG. 28 is 10 [mu] s. The value of the times t _{3 to} t _{4 in} FIG. 28 is 200 μs.

  The process of calculating the integral value of the reverberation R is repeatedly executed by changing the frequency of the burst wave to various values. For example, the integral value calculation process is repeated by increasing (or decreasing) the frequency by 0.2 kHz for each process. As a result, as shown in FIG. 29, a frequency spectrum with the integral value of the reverberation R as the signal intensity is obtained (step S6).

  FIG. 29 is a graph showing a frequency spectrum obtained by the time history response analysis of the fourth example.

  The horizontal axis in FIG. 29 indicates the frequency of the burst wave. The vertical axis in FIG. 29 represents the integral value (signal intensity) of the reverberation R. The peak frequency f in this frequency spectrum corresponds to the resonance frequency in the thickness direction of the piping model. The resonance frequency f in FIG. 29 is 300 kHz.

  The time history response analysis of the present embodiment is executed to calculate various orders of resonance frequencies for ultrasonic waves propagating in the thickness direction. Therefore, in order to efficiently execute the time history response analysis, the frequency of the burst wave is swept in small increments in a frequency band close to the frequency of the stationary wave calculated by the frequency response analysis. This makes it possible to calculate various orders of resonance frequencies in a short time. In order to calculate these resonance frequencies in a short time, a chirp wave may be used instead of a burst wave in the time history response analysis.

  Moreover, the process of step S2 to S6 is repeatedly performed by setting the variable of a piping model to various values. As a result, the relationship between various orders of resonance frequencies and variables of the piping model is analytically determined. That is, a function representing the relationship between the Nth order resonance frequency f (N) of the piping model and the variable is obtained.

  Thereafter, this function is stored in a predetermined database (step S7). This function is stored in the computer 3 in advance when the actual thickness measurement of the pipe 4 is executed.

  In the fourth example of the present embodiment, both the modal analysis and the frequency response analysis are performed before the time history response analysis is performed in order to limit the frequency band to which the time history response analysis is applied. Only one of the modal analysis and the frequency response analysis may be executed. In general, modal analysis has an advantage that it can be executed in a short time, and frequency response analysis has an advantage that calculation accuracy is high. When both of these are executed, the frequency band limiting process takes a longer time than when only one of these is executed, but an accurate calculation result can be obtained as compared with the case where only one of these is executed. In the fourth example of the present embodiment, if possible, the time history response analysis may be executed without executing the modal analysis and the frequency response analysis.

  According to the fourth example of the present embodiment, a function representing the relationship between the N-th resonance frequency f (N) of the pipe 4 and the variable can be obtained by simulation. Calculating the resonance frequency by simulation as in the fourth example of the present embodiment has an advantage that it is easy to specify a high-order resonance frequency that has a small vibration amplitude and is difficult to measure in an experiment.

  As described above, in the present embodiment, power supply to the ultrasonic optical probe 1 is performed using wireless power feeding or energy harvesting. Therefore, according to the present embodiment, it is possible to suppress the wiring volume of the power supply line for pipe inspection. As a result, according to the present embodiment, it is possible to reduce the difficulty in handling the power supply line and the possibility of disconnection of the power supply line, and improve the convenience of the pipe inspection.

  Moreover, in this embodiment, transmission / reception of the laser beam between the ultrasonic optical probe 1 and the pipe inspection apparatus 2 is performed using wireless communication. Therefore, according to the present embodiment, it is possible to suppress the wiring volume of the signal line for pipe inspection. As a result, according to the present embodiment, it is possible to reduce the difficulty in handling signal lines and the possibility of disconnection of signal lines, and improve the convenience of pipe inspection.

  Moreover, according to this embodiment, it is possible to suppress the wiring volume of the signal line for pipe inspection by connecting the reflection end 73 to the optical fiber sensor 1b.

  Further, according to the present embodiment, it is possible to suppress the wiring volume of the signal line for power supply inspection and the power supply line by connecting at least one of the EMATs 1a and the optical fiber sensors 1b in series or in parallel with each other. It becomes.

  Further, according to the present embodiment, instead of the vibration of the EMAT 1a, the vibration of the large EMAT 6 or the vibration caused by the working fluid 7 is used for pipe inspection, so that the ultrasonic optical probe 1 (optical fiber sensor) to the pipe 4 is used. It is possible to save labor in the mounting work 1b).

  Moreover, in this embodiment, the thickness of the pipe | tube deposit | attachment 4b adhering to the pipe | tube base material 4a is calculated from the measurement result of several resonance frequency. Therefore, according to the present embodiment, it is possible to calculate the thickness of the pipe deposit 4b even when data available for calculating the thickness of the pipe deposit 4b is limited. As a result, according to the present embodiment, it becomes possible to detect various phenomena that are desired to be detected by the pipe inspection, thereby improving the convenience of the pipe inspection. For example, according to the present embodiment, the adhesion of scale to the inner surface of the heat exchange pipe, the peeling of the coating on the inner surface of the pipe through which the corrosive fluid flows, the occurrence of rust on the inner surface of the water and sewage pipe, etc. Can be detected non-destructively and online when needed.

  Although several embodiments have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. The novel apparatus and methods described herein can be implemented in a variety of other forms. In addition, various omissions, substitutions, and changes can be made to the forms of the apparatus and method described in the present specification without departing from the spirit of the invention. The appended claims and their equivalents are intended to include such forms and modifications as fall within the scope and spirit of the invention.

1: ultrasonic optical probe, 1a: electromagnetic ultrasonic oscillator, 1b: optical fiber sensor,
1c: resin sheet, 1d: adhesive, 2: piping inspection device,
2a: light source, 2b: optical interferometer, 2c: waveform signal generator, 2d: amplifier,
3: computer, 4: piping, 4a: piping base material, 4b: piping deposit,
4c: mixed material, 5: heat insulating material, 6: large electromagnetic ultrasonic oscillator, 7: working fluid,
11, 12, 13, 14: optical fiber, 15, 16: power line,
21: Probe laser emitting end, 22: Laser receiving end,
23: Laser emitting end, 24: Probe laser receiving end,
25: Wireless power transmission circuit, 26: Wireless power reception circuit,
27: Chirp wave transmission circuit, 31: Terminal block,
41: thermoelectric conversion element, 42: device for heat exchange, 43: power storage / boost circuit,
51: Vibration power generation element, 52: Power storage / boosting circuit,
61: photoelectric conversion element, 62: power storage / boosting circuit,
71: Tube portion, 72: Fiber portion with protective coating,
73: Reflection end, 74: Optical fiber, 75: Probe laser emission / light reception end,
76: optical fiber, 77: circulator, 78: distributor

Claims (5)

Input ultrasonic waves into the pipe from the ultrasonic oscillator of the ultrasonic optical probe attached to the pipe,
Laser light is input to the optical fiber sensor of the ultrasonic optical probe,
Detecting the laser beam transmitted through the optical fiber sensor that the ultrasonic wave has reached from the pipe,
Based on the detection result of the laser beam, a plurality of resonance frequencies are detected,
Using the plurality of resonance frequencies, calculate the thickness of the deposit attached to the base material of the pipe,
Look at including it,
The plurality of resonance frequencies include a resonance frequency of the base material of the pipe, a resonance frequency of the deposit of the pipe, and a resonance frequency of the pipe.
Pipe inspection method. Input ultrasonic waves into the pipe from the ultrasonic oscillator of the ultrasonic optical probe attached to the pipe,
Laser light is input to the optical fiber sensor of the ultrasonic optical probe,
Detecting the laser beam transmitted through the optical fiber sensor that the ultrasonic wave has reached from the pipe,
Based on the detection result of the laser beam, a plurality of resonance frequencies are detected,
Using the plurality of resonance frequencies, calculate the thickness of the deposit attached to the base material of the pipe,
Look at including it,
The thickness of the deposit is calculated by solving simultaneous equations including resonance frequencies of a plurality of orders of the pipe,
The simultaneous equations include the resonance frequency derived on the assumption that the pipe is formed of a mixed material of the base material and the deposit material.
Pipe inspection method. Input ultrasonic waves into the pipe from the ultrasonic oscillator of the ultrasonic optical probe attached to the pipe,
Laser light is input to the optical fiber sensor of the ultrasonic optical probe,
Detecting the laser beam transmitted through the optical fiber sensor that the ultrasonic wave has reached from the pipe,
Based on the detection result of the laser beam, a plurality of resonance frequencies are detected,
Using the plurality of resonance frequencies, calculate the thickness of the deposit attached to the base material of the pipe,
Look at including it,
The thickness of the deposit is calculated by solving simultaneous equations including resonance frequencies of a plurality of orders of the pipe,
The simultaneous equations are derived by substituting the detection result of the resonance frequency into a function obtained by simulation,
The simulation includes at least one of modal analysis, frequency response analysis, and time history response analysis using a model of the piping.
Pipe inspection method. 4. The pipe inspection method according to claim 2 , wherein the simultaneous equations include a variable that depends nonlinearly on the resonance frequency. 5. 5. The pipe inspection method according to claim 1, wherein the plurality of resonance frequencies includes a plurality of orders of resonance frequencies of the pipe.

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