JP5159436B2 - Method and apparatus for detecting scale adhesion - Google Patents

Description

The present invention relates to boiler equipment, steam system piping, particularly scale attached to a base material such as steam piping of a thermal power generation boiler, in particular, scale lift, peeling boundary, step, thickness change, etc. The present invention relates to a method and an apparatus for detecting an adhesion state of a scale in a heterogeneous adhesion portion of the scale by an electromagnetic ultrasonic resonance method.

  A scale made of metal oxide, hydroxide, or the like adheres to the inner surface of a boiler tube of a power plant or the like, and this reduces the heat transfer performance, thereby reducing boiler efficiency. In particular, the steam oxidation scale generated in steam systems such as boiler superheater tubes not only reduces heat transfer, but also rises due to the difference in coefficient of thermal expansion between the tubes and the scale, and eventually peels and falls off. Along with the steam, it flies to the turbine of the subsequent stage and causes wear corrosion of the turbine blade. Turbine blades are inspected and repaired at a high cost during regular inspections. However, a method that can detect the scales when they are rising is desired for early detection of the scales.

  Further, when the scale is peeled or dropped, a stepped portion, a marked thickness change portion or the like is generated. However, in such a heterogeneous adhesion portion, the scale is often lifted and there is a risk of peeling and dropping. For this reason, there is a demand for a method that can detect an inhomogeneous adhesion portion of a scale, such as a scale floating portion, a peeling boundary portion, a step portion, or a thickness changing portion, at an early stage.

  Conventionally, the presence / absence, thickness, etc. of scales have been detected by transmitting ultrasonic pulses with an ultrasonic inspection apparatus using piezoelectric elements, receiving the reflected echoes, and calculating the time difference between the two. In this method, since the probe needs to be in contact with the outer surface of the pipe, it is necessary to smooth the outer surface of the pipe in advance before cleaning and apply a contact medium such as glycerin paste or oil to the outer surface of the pipe. Yes, the work was very complicated.

  In order to improve the problems of the ultrasonic inspection apparatus using such a conventional piezoelectric element, Patent Document 1 describes the circumferential direction of the pipe from the outside of the pipe by an electromagnetic ultrasonic probe (Electro-Magnetic Acoustic Transducer). In addition, a method of scanning in the longitudinal direction and detecting a scale adhesion state such as a thickness of a scale adhered to a base material such as a boiler pipe without contact, peeling, or a lifted state is shown. This method is a method of inspecting the thickness, delamination, lifting, etc. of the steam oxidation scale such as piping by an echo method in which an ultrasonic pulse is generated on an object by an electromagnetic ultrasonic probe and a reflected wave is detected, By detecting the echo (reflected wave) of the ultrasonic pulse, the thickness of the scale, peeling, lifting, etc. are inspected from the time difference of the echo.

  However, according to this method, since the thickness of the substrate and scale is detected by the time difference between the ultrasonic pulse and echo (reflected wave), there is a detection limit due to the wavelength of the ultrasonic wave. Ultrasonic pulses can be detected, but when the scale is thin, the detection accuracy decreases due to interference of echoes (reflected waves), and detection becomes impossible when waves overlap. For example, in the case of a scale with a thickness of 100 μm or less, the boundary echo between the scale and the tube and the echo on the surface of the scale become a composite wave, making it impossible to clearly separate them. It cannot be detected. In this case, even if the scale layer is as thick as 100 μm or more, it cannot be detected if the peeled or lifted layer is 100 μm or less.

  On the other hand, in Patent Document 2, as a method different from such an electromagnetic ultrasonic echo method, a conductive material superimposed on a non-conductive interface using electromagnetic ultrasonic waves having a common resonance frequency in a plurality of layers. A method for diagnosing a damage state such as corrosion and fatigue of a laminated structure is shown. In this method, an ultrasonic wave is generated by an electromagnetic ultrasonic probe and transmitted from one side surface of the laminated structure, and an ultrasonic wave reflected by the other side surface is received, and the sound velocity and attenuation of the received ultrasonic wave are received. This is a method of diagnosing the damage state of the laminated structure based on the change of the above. However, Patent Document 2 does not disclose a method for detecting the attached state of the scale, such as a change in the thickness of the scale attached to the substrate, peeling, or a lifted state.

  Non-Patent Document 1 discloses a method of measuring the thickness of a steam oxidation scale attached to a boiler pipe or the like by an electromagnetic ultrasonic resonance method. Here, an electromagnetic ultrasonic probe as shown in Patent Documents 1 and 2 transmits an electromagnetic wave as an electromagnetic induction signal to generate an ultrasonic wave on one side surface of the laminated structure. An ultrasonic signal such as an electromotive force obtained from the ultrasonic wave in the structure including the ultrasonic wave reflected by the other side is received from the object, and the ultrasonic resonance is performed by changing the frequency of the electromagnetic induction signal and sweeping it. A method of generating and measuring the thickness of a substrate and oxide scale from a plurality of resonance peaks having different frequencies is shown.

However, in Non-Patent Document 1, a plurality of resonance peaks obtained from a boiler pipe to which a specific thickness of oxide scale is attached are shifted along the frequency axis due to discontinuity between the base material layer and the scale layer. For this reason, the thickness calculated from each peak changes, and it has been shown to correct this, but it detects non-uniform adhesion parts of scales such as floating parts, peeling boundary parts, step parts, and thickness changing parts. How to do is not shown.
JP 2004-45124 A JP 2003-254943 A Inspection technology 2003.5. Pages 36-39

As described above, in the prior art, the electromagnetic ultrasonic resonance method is merely used for measuring the thickness of the scale adhering portion, and in order to accurately measure the thickness, the output and frequency at which a single resonance peak appears. Was selected. In the conventional thickness measurement method, if the output of the measuring device is increased, a divided resonance peak group may appear.In this case, since the thickness of the adhered portion cannot be measured accurately, the output is reduced. It was usual to keep the value so low that only a single resonance peak appears.
As described above, the prior art relates to the measurement of the thickness of the scale adhering portion, and the state of non-uniform adhesion of the scale such as lifting, peeling, stepped portion, and thickness change cannot be detected by the electromagnetic ultrasonic resonance method. It was. Further, in the prior art, the fact that only the single resonance peak is used and the significance of the divided resonance peak group was not recognized at all.

While utilizing the above-described conventional technology based on the electromagnetic ultrasonic resonance method, the present inventor may not have a split resonance peak group that has not been recognized for its usefulness at all depending on the state of the scale adhesion portion. I found out the phenomenon. Therefore, when an experiment was performed with several test pieces with different scale attachment states, the phenomenon of split resonance peaks appearing or not appearing was caused by scale lift, peeling, stepped portions, thickness change, etc. The present inventors have found that there is a close relationship with change, and have reached the present invention. Then, as the experiment was further repeated, it was also found that the preferable ultrasonic frequency region in which the divided resonance peak group clearly appears is 1.0 to 3.5 MHz, more preferably 1.5 to 2.5 MHz.
The object of the present invention is to attach the scale attached to the base material such as the steam system piping of the boiler in a high accuracy and in a short time even in a non-contact manner by the electromagnetic ultrasonic resonance method, in particular, the lifted portion of the scale, the separation boundary portion. Another object of the present invention is to propose a scale adhesion state detection method and apparatus for detecting a scale adhesion state in a non-uniform adhesion portion of a scale such as a stepped portion and a thickness changing portion.

The present invention is the following method and apparatus for detecting a scale adhesion state.
(1) The electromagnetic ultrasonic probe is moved and arranged at a different position so as to face the surface opposite to the surface of the substrate on which the scale is attached to the object on which the scale is attached to the substrate ,
The electromagnetic ultrasonic probe transmits an electromagnetic induction signal to generate an ultrasonic wave on the object, and receives an ultrasonic signal from the object.
Sweeping by changing the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe, obtaining the resonance spectrum by generating ultrasonic resonance,
When a resonance spectrum consisting of repetition of a single peak is obtained as a resonance peak with a different resonance order, it is determined as a homogeneous adhesion portion,
Calculate the overall wall thickness including the base material and the attached scale from the difference in resonance frequency in the homogeneous adhesion part,
When a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks corresponding to each other at different resonance orders is obtained as a resonance peak having different resonance orders, it is determined as a heterogeneous adhesion portion ,
Among the plurality of individual resonance peaks constituting each of the plurality of resonance peak groups having different resonance orders in the heterogeneous adhesion portion, the difference in resonance frequency between the individual resonance peaks in the corresponding relationship among the resonance peak groups having different resonance orders Calculate the total wall thickness including the base material and the attached scale from the difference in resonance frequency between the individual resonance peaks in other corresponding relations, and compare it with the wall thickness in the homogeneously attached part. A method for detecting a scale adhesion state, wherein the scale adhesion state is determined from the difference .
(2) An electromagnetic ultrasonic probe transmits an electromagnetic wave generated by applying a high-frequency current to a transmission coil in a magnetic field as an electromagnetic induction signal, and an eddy current is generated in the object by electromagnetic induction. causing ultrasonic vibration in the object, thereby excited electromotive force of the method (1) Symbol placement is of the Lorentzian taken out as an induction current in the receiver coil as an ultrasonic signal.
(3) The method according to (1) or (2) above, wherein the individual resonance peaks in a corresponding relationship are individual resonance peak pairs in a corresponding relationship in adjacent resonance peak groups.
(4) The method according to any one of (1) to (3) , wherein an ultrasonic wave of 1.0 to 3.5 MHz is generated on the object.
(5) An electromagnetic ultrasonic probe that transmits an electromagnetic induction signal to an object having a scale attached to a substrate and receives an ultrasonic signal;
A moving arrangement device that moves and arranges the electromagnetic ultrasonic probe to a different position opposite to the surface opposite to the surface of the substrate on which the scale is attached to the substrate with the scale attached to the substrate ,
Transmission / reception control that generates an ultrasonic wave by transmitting an electromagnetic induction signal from an electromagnetic ultrasonic probe to an object with a scale attached to the substrate, and receives an ultrasonic signal from the object by the electromagnetic ultrasonic probe Equipment,
Resonance spectrum is obtained by changing the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe and sweeping it to obtain a resonance spectrum. Resonance peaks consist of repeated single peaks as resonance peaks with different resonance orders. When a spectrum is obtained, it is judged as a homogeneously attached part, and the total thickness including the substrate and attached scale is calculated from the difference in resonance frequency at the homogeneously attached part, and resonances with different resonance orders are obtained. When a resonance spectrum consisting of a repetition of resonance peak groups divided into a plurality of individual resonance peaks having a correspondence relationship in order is obtained, it is determined as a heterogeneous adhesion portion, and a plurality of resonance orders having different resonance orders in the heterogeneous adhesion portion are determined . Individual resonance peaks corresponding to each other among the resonance peak groups having different resonance orders among the plurality of individual resonance peaks constituting the resonance peak groups. From the difference in resonance frequency between ringing peaks and the difference in resonance frequency between individual resonance peaks in other corresponding relations, the total wall thickness including the substrate and the attached scale is calculated, and the with comparison with the thickness detection apparatus of the scale deposition condition, characterized in that it comprises an arithmetic control unit for determining the state of adhesion of scale from the difference in thickness.
(6) An electromagnetic ultrasonic probe transmits an electromagnetic wave generated by applying a high-frequency current to a transmission coil in a magnetic field as an electromagnetic induction signal, and an eddy current is generated in the object by electromagnetic induction. causing ultrasonic vibration in an object, that of the Lorentz type is the (5) Symbol mounting device for taking out the electromotive force excited by this as an induction current in the receiver coil as an ultrasonic signal.
(7) The apparatus according to (5) or (6) above, wherein the individual resonance peaks in a corresponding relationship are individual resonance peak pairs in a corresponding relationship in adjacent resonance peak groups.
(8) The device according to any one of (5) to (7) , wherein the transmission / reception control device generates an ultrasonic wave of 1.0 to 3.5 MHz on the object.

  In the present invention, the target for the scale adhesion state detection is that the scale is adhered to the base material, such as boiler equipment, steam system piping, particularly steam system piping of a thermal power generation boiler, metal oxide, hydroxide It is a structure to which a scale composed of etc. is attached. Such a base material is often made of steel, copper, or other metal, but may be made of concrete, wood, or other materials.

As the above-mentioned object, a structure such as a pipe or a tank having a scale attached to the inner surface of the base material is suitable as a detection target, but a structure having a scale attached to the outer surface may be used. Examples of the boiler pipe include a superheater pipe, a reheater pipe, and an evaporation pipe. In the present invention, so as to face the opposite surface of the scale of these substrates are adhered surface (typically an outer surface) to place the electromagnetic ultrasonic probe, the heterogeneous deposition of scale in a non-contact While detecting the state of adhesion of scale, a surface (outer surface) opposite to the scale is adhered surface oxide, without dirt adhesion, preferably a uniform surface.

  If a scale made of metal oxide, hydroxide, or the like adheres to the inner surface of the boiler tube, the heat transfer performance is lowered and the boiler efficiency is lowered. Except for this point, the attached scale is removed by chemical cleaning during periodic inspections of boilers and the like, so there is often no need to deal with it urgently unless the danger of peeling or dropping is imminent. However, if the scale is lifted, it will be peeled off and cause wear corrosion of the turbine blade, so it is desirable to detect the scale lift early.

Further, when the scale is peeled or dropped, a stepped portion appears and a scale thickness changing portion is generated. However, in such a portion, the scale is often lifted, and there is a risk of peeling and dropping. For this reason, in the present invention, the detection target is a heterogeneous adhesion state including a heterogeneous adhesion part of the scale such as a scale floating part, a peeling boundary part, a step part, and a thickness change part. to the homogeneous deposition conditions including a homogeneous attachment or non-attachment of the scale also shall be the detection target.

  In the present invention, the material, type, thickness, etc. of the base material and scale to be detected are not limited as long as electromagnetic ultrasonic resonance is generated, and can be detected even when the thickness of the scale layer is 100 μm or less. is there. The thickness of the base material to be detected is generally 1 to 60 mm, preferably 3 to 30 mm, and the thickness of the scale layer is about 0.01 to 1.0 mm, preferably about 0.05 to 0.6 mm. It is.

  In the present invention, the non-uniformly adhered portion of the scale, such as the raised portion of the scale, the stepped portion, and the thickness changing portion, is measured by measuring the total thickness including the thickness of the base material and the scale, Is detected as a difference in thickness between the thinner one and the thinner one, but the overall thickness measured at this time is generally 1 to 60 mm, preferably 3 to 30 mm, and the thickness difference is 10 to 1000 μm. The thickness may preferably be about 50 to 600 μm.

  An object having a scale attached to a base material such as metal is generated by transmitting an electromagnetic induction signal such as an electromagnetic wave by an electromagnetic ultrasonic probe to generate ultrasonic waves. When measuring the thickness, in the case of an object having a uniformly attached scale, a single resonance peak repeatedly appears at a substantially constant frequency interval, and the method of calculating the thickness from the resonance frequency is the non-patent document 1. Is shown in Therefore, if the thickness of the entire object including the scale attached by this method is measured at a plurality of portions and the difference in thickness is examined, it is possible to determine the presence or absence of scale peeling. However, the position at which the resonance peak appears varies slightly depending on the measurement conditions, and it is difficult to accurately determine the difference in thickness, particularly when the thickness of the scale and the difference in thickness are small.

  At the position where the scale layer is uniformly attached to the homogeneous base layer as described above, a resonance spectrum consisting of repetition of a single resonance peak is obtained, but the scale is used as the detection region of the electromagnetic ultrasonic probe. When detecting by placing an electromagnetic ultrasonic probe on a non-uniform adhesion site such as a floating part, peeling boundary part, stepped part due to dropping, or a change in scale thickness, resonance peaks with different resonance orders are detected. It was found that a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks having a corresponding relationship at different resonance orders was obtained. In the present invention, when a resonance spectrum composed of repetition of such divided resonance peak groups is obtained, the adhesion state of the scale is detected with high accuracy and in a short time by determining the heterogeneous adhesion portion.

  The electromagnetic ultrasonic resonance method is a method for detecting ultrasonic resonance in the detection region of the electromagnetic ultrasonic probe. If the structure in the detection region is simple, a resonance spectrum consisting of repetition of a single resonance peak is generated. Will be obtained. This is because, within the detection area, when the scale is not attached to the substrate, the scale is uniformly attached, or even if it is peeled off evenly, the single resonance peak A resonance spectrum consisting of repetition is obtained.

  On the other hand, if there is a non-uniform adhesion site such as a scale lift, a peeling boundary, a step due to dropping, or a change in the thickness of the scale in the detection area of the electromagnetic ultrasonic probe, many resonances occur. A plurality of resonance peaks appear. For example, at the separation boundary or stepped part, resonance due to a normal homogeneous adhesion part and resonance due to a thin-walled part due to peeling or dropping occur, and if there are multiple thin-walled parts, multiple resonances will occur and split Of repeated resonance peaks. The floating portion is a state in which the homogeneously adhered portion and the peeled portion are gathered at a small interval, and becomes a heterogeneous adhered portion, which causes repetition of the divided resonance peak group.

  For this reason, in the present invention, when a resonance spectrum composed of repeated divided resonance peak groups is obtained, it is determined as a heterogeneous adhering portion, thereby detecting the scale adhering state with high accuracy and in a short time. It is possible to detect the scale adhesion state only by detecting such a heterogeneous adhesion part, but by moving the electromagnetic ultrasonic probe to change the detection site, the normal homogenous adhesion part is detected. The presence and distribution of the heterogeneous adhesion can be confirmed by obtaining and comparing resonance spectra.

  In the present invention, an electromagnetic ultrasonic transducer (Electro-Magnetic Acoustic Transducer) used for detecting a scale adhesion state generates an ultrasonic wave in an object by transmitting an electromagnetic induction signal such as an electromagnetic wave in a non-contact manner, The apparatus receives an ultrasonic signal such as electromotive force and electromagnetic waves that are secondarily generated in, and can be the one that has been conventionally used for the Electro-Magnetic Acoustic Resonance.

  As such an electromagnetic ultrasonic probe, an electromagnetic wave generated by applying a high-frequency current to a transmission coil in a magnetic field is transmitted as an electromagnetic induction signal, an eddy current is generated in an object by electromagnetic induction, and a Lorentz force is used. A Lorentz type that generates ultrasonic vibrations in an object and extracts an electromotive force excited thereby as an induced current by a receiving coil as an ultrasonic signal is preferable, but a magnetostrictive type that utilizes periodic repetition of expansion and contraction It may be.

  The electromagnetic ultrasonic probe is of a non-contact type and transmits an electromagnetic induction signal such as an electromagnetic wave from the outside of the object in a non-contact state to generate an ultrasonic wave on the object. It is preferably configured to receive ultrasonic signals such as electromotive force and electromagnetic waves obtained from ultrasonic waves in the structure including ultrasonic waves reflected by the side surfaces, but it generates ultrasonic waves in contact state. And reception. The type, shape, configuration, and the like of the electromagnetic ultrasonic probe are not limited, and those suitable for transmission and reception of the above ultrasonic signals can be employed.

  The transmission coil and the reception coil may be separate or integrated as a transmission / reception coil, but may be selected according to the base material and scale. The electromagnetic ultrasonic probe may be detected by manually facing an arbitrary detection position of the object, but is configured so that the electromagnetic ultrasonic probe is moved and arranged at a different position of the object. The electromagnetic ultrasonic probe and / or the object are mechanically attached by the moving arrangement device, and the electromagnetic ultrasonic probe and / or the object is moved to the detection position to be positioned or scanned. Also good.

  Such an electromagnetic ultrasonic probe feeds a high-frequency current from a power supply device and a transmission / reception control device including a high-frequency generation circuit, and transmits an electromagnetic induction signal such as an electromagnetic wave to an object having a scale attached to the substrate. In addition to generating ultrasonic waves, ultrasonic signals such as electromotive force and electromagnetic waves generated by the ultrasonic waves are received by an electromagnetic ultrasonic probe, detected as an induced current, and analyzed. The electromagnetic induction signal can be a signal having an arbitrary waveform such as a burst wave, a pulse, or a continuous wave as long as resonance occurs between the ultrasonic wave generated on the object and the reflected ultrasonic wave. Waves are preferred. The burst wave is an electromagnetic induction signal in which a single frequency waveform (sine wave, rectangular wave, triangular wave, etc.) lasts for a predetermined time. The time width of the burst wave may be in a range where resonance occurs, but is generally 40 to 400 μs, preferably 40 to 200 μs. The output of electromagnetic induction signals such as burst waves, pulses, and continuous waves vary depending on the type, characteristics, etc. of the electromagnetic ultrasonic probe and the material, dimensions, reflection characteristics, etc. of the object. The output etc. can be selected so that.

  The transmission / reception control device is configured to sweep by changing the frequency of the electromagnetic wave of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe by a signal from the arithmetic control device. The frequency to be swept can preferably be between 0.5 and 10 MHz, but is generally 1.0 to 3.5 MHz, more preferably 1.5 to 2.5 MHz. Since the frequency range in which the resonance peak is obtained varies depending on the type of substrate and scale, material, thickness, etc., the divided individual resonance peaks are divided in the frequency range in which a distinguishable resonance peak is obtained, particularly in the resonance peaks having different resonance orders. It is preferable to select a frequency range that can be recognized, and sweep by changing the frequency in small increments. In the transmission / reception control device, the frequency resolution can be set to a value that can be discriminated in accordance with the type and material of the base material and scale, the material, the thickness, and the characteristics of the device. The frequency resolution is determined by the measurement frequency interval when the measurement frequency is changed in small increments. The frequency interval varies depending on the type of substrate and scale, material, thickness, and device characteristics, but can be generally 1 to 10 kHz, preferably 2 to 8 kHz. This frequency resolution can be a frequency interval at which the divided individual resonance peaks can be recognized at resonance peaks having different resonance orders. As a specific determination method, it is possible to select a frequency interval at which the individual resonance peaks divided by sequentially changing from a wide frequency interval to a narrow frequency interval can be recognized.

  The arithmetic and control unit generates an ultrasonic resonance by changing the frequency of the electromagnetic wave of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe and sweeping it to obtain a resonance spectrum. When a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks corresponding to each other at different resonance orders is obtained, it is configured to determine that the scale is a heterogeneous adhesion portion.

When a resonance spectrum consisting of repetition of a single peak is obtained as a resonance peak having a different resonance order, the arithmetic and control unit determines that the scale is a homogeneous adhesion portion, and determines the substrate and the substrate from the difference in resonance frequency at the homogeneous adhesion portion. It configured to calculate the thickness of the whole, including the attached scale. In addition, the arithmetic and control unit is configured so that individual resonance peaks having a corresponding relationship among resonance peak groups having different resonance orders among a plurality of individual resonance peaks that respectively constitute a plurality of resonance peak groups having different resonance orders in the heterogeneous adhesion portion. and the difference between the resonance frequency, and a difference between the resonance frequency of the individual resonance peaks each other in other correspondence, and calculates the thickness of the whole including the scale and substrate and adhesion, the thickness of the homogeneous attachment contrasted while, configured for determining the heterogeneous state of adhesion of scale as a change in thickness from the difference in thickness.

  The electromagnetic ultrasonic probe is controlled by such an arithmetic control device and a transmission / reception control device, and an electromagnetic induction signal is transmitted to an object having a scale attached to the substrate to generate an electromagnetic ultrasonic wave on the object. When an ultrasonic signal is received from an object and swept by changing the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe by the signal from the arithmetic and control unit, ultrasonic resonance occurs in a specific frequency range and frequency interval. To do. Ultrasonic resonance is generated when the natural resonance frequency of the object and the sweep frequency coincide with each other, and when the frequency is an integral multiple of the resonance frequency. At this time, since the frequency range in which ultrasonic resonance occurs is limited, the divided individual resonance peaks are recognized in the frequency range where resonance peaks that can be discriminated in each measurement system are obtained, especially in the resonance peaks with different resonance orders. Select the frequency range that can be used, and determine the sweep frequency range. The frequency resolution is also the same, and the measurement frequency interval at which a recognizable resonance peak can be obtained in each measurement system, particularly the measurement frequency interval at which the divided individual resonance peaks can be recognized in the resonance peaks having different resonance orders is determined.

  When the object has a uniform material and thickness, for example, when it consists of a homogeneous base material to which no scale adheres, a resonance spectrum consisting of repetition of a single resonance peak is obtained. The resonance peak of each resonance order has a constant frequency interval, and the frequency of each resonance peak and the thickness of the object are inversely proportional to each other as shown in the later-described equation (A). The wall thickness is determined from the frequency of

  On the other hand, in the case of an object with a scale attached to the base material, there is a difference in sound speed between the base material and the scale, so the phase of each resonance peak shifts due to the discontinuity between layers, and Since the frequency and the thickness of the object are not inversely proportional, the thickness calculated from the frequency of each resonance peak changes. In Non-Patent Document 1, a specific coefficient is set for the maximum thickness value calculated. It is shown that the actual thickness value is obtained by multiplication. However, even when the phase of each resonance peak shifts, the difference in resonance frequency between resonance peaks, in particular, the difference in resonance frequency between adjacent resonance peaks becomes substantially equal, and the thickness can be calculated from the difference in resonance frequency. . In particular, since the difference in resonance frequency is substantially reduced at a thin scale thickness as the object of the present invention, the entire thickness including the substrate and the attached scale is calculated with high accuracy from the difference in resonance frequency. can do.

  When the base layer and the scale layer are in a homogeneous adhesion state with a uniform material and thickness, if a detection is performed by placing an electromagnetic ultrasonic probe in a position opposite to this, a single resonance peak is repeated. A resonance spectrum is obtained, and the frequency interval of each resonance order is substantially constant. When such a resonance spectrum consisting of repetition of a single resonance peak is obtained, it can be determined as a homogeneous adhesion portion by the arithmetic and control unit. In such a homogeneous adhesion portion, since the reflected wave (echo) reflected from the opposite scale layer by the ultrasonic wave generated by the electromagnetic induction signal is a single wave, a single resonance peak is formed and repeated. .

  For this reason, as a position determined to be a homogeneous adhesion portion, in the detection region of the electromagnetic ultrasonic probe, a position where the scale layer is uniformly adhered to the homogeneous base material layer without peeling, or peeling. Even in such a case, in the detection region of the electromagnetic ultrasonic probe, there is a position where the scale layer is uniformly attached to the homogeneous base material layer after being peeled off. In other words, in the detection region of the electromagnetic ultrasonic probe, even if it is not peeled off or peeled off, at the position where the scale layer is uniformly attached to the homogeneous base material layer, a single resonance peak A resonance spectrum consisting of repetition is obtained, and it is determined by the arithmetic and control unit as a homogeneous adhesion portion.

  On the other hand, if the detection is performed by placing an electromagnetic ultrasonic probe at the position of the scale lift, separation boundary, step due to drop-off, or heterogeneous adhesion such as scale thickness change, the resonance order As the different resonance peaks, resonance spectra composed of repetitions of resonance peak groups divided into a plurality of individual resonance peaks corresponding to each other at different resonance orders are obtained.

  In other words, if there is an inhomogeneous part such as a peeling boundary, stepped part, or part with a varying thickness due to scale lifting, peeling or dropping in the detection area of the electromagnetic ultrasonic probe, the supersonic wave generated by the electromagnetic induction signal In the acoustic resonance, resonance by a normal homogeneous adhesion part and resonance by a thin-walled part due to peeling and dropping occur, and when there are multiple thin-walled parts, multiple resonances will occur. A group of resonance peaks divided into a plurality of individual resonance peaks appears periodically, and a resonance spectrum consisting of these repetitions is obtained. A plurality of divided individual resonance peaks constituting resonance peak groups having different resonance orders have a corresponding relationship in different resonance orders, and the individual resonance peaks in the corresponding relationship appear periodically in different resonance orders, and the resonance peak group Each of the individual resonance peaks that constitutes is repeated at a different frequency interval (period).

  When such a resonance spectrum is obtained, it is determined by the arithmetic and control unit that the inhomogeneous adhesion state is present. Whether the resonance peak of the obtained resonance spectrum is a single peak or a group of resonance peaks divided into a plurality of individual resonance peaks depends on the position, height, and frequency interval of each divided individual resonance peak. Etc. are judged comprehensively. In general, when another individual resonance peak whose intensity from the baseline is 1/10 or more, particularly 1/8 or more with respect to the strongest individual resonance peak, it was divided into a plurality of individual resonance peaks. Although it can be determined that the group is a resonance peak group, since it varies depending on the measurement conditions, it can be comprehensively determined from the characteristics of the peak.

  When a resonance spectrum consisting of repetitions of resonance peak groups divided into a plurality of individual resonance peaks is obtained, in the case of the raised part of the scale, the region where the repetition of resonance peak groups appears tends to be narrow, In this case, since the region where the resonance peak group repeats is wide, it is easy to distinguish between the two. However, in the case of a raised part of the scale, if there is a thickness change part such as a stepped part, there is a risk of peeling of the scale, so these are not distinguished, and resonances divided into multiple individual resonance peaks When a resonance spectrum consisting of repetition of peak groups is obtained, it can be determined as a heterogeneous adhesion portion.

  In these cases, among a plurality of individual resonance peaks that respectively constitute a plurality of resonance peak groups having different resonance orders, a difference in resonance frequency between individual resonance peaks in a corresponding relationship among resonance peak groups having different resonance orders, and It is possible to calculate the overall thickness including the base material and attached scale from the resonance frequency difference between the individual resonance peaks in other corresponding relations, and to detect the heterogeneous adhesion part of the scale from the difference in thickness. it can.

  A plurality of resonance peak groups having different resonance orders are each composed of a plurality of individual resonance peaks, and each individual resonance peak is located between a plurality of resonance peak groups having different resonance orders. The intervals and the like have similarities in correspondence, and the correspondence can be recognized at a glance. These individual resonance peak features such as position, height, shape, and the like represent different adhesion states such as scale thickness, peeling, and lifting. Each resonance peak group is composed of individual resonance peaks having a corresponding relationship, and appears in order of the resonance order.

  In the present invention, in the arithmetic and control unit, among the plurality of individual resonance peaks constituting each of the plurality of resonance peak groups having different resonance orders, the resonance frequencies of the individual resonance peaks having a corresponding relationship among the resonance peak groups having different resonance orders Is compared with the difference in resonance frequency between the individual resonance peaks in other corresponding relations, and the adhesion state of the scale is detected. The individual resonance peaks in the correspondence relationship are preferably individual resonance peak pairs in the correspondence relationship in adjacent resonance peak groups. Calculate the total wall thickness including the base material and the attached scale from the difference in resonance frequency between the individual resonance peaks in correspondence, and the scale thickness will rise, peel, drop, or change in thickness of the scale from the difference in thickness. The degree can be detected, and when the degree of thickness change is a specific value or more, it can be determined as a non-uniformly adhered portion of the scale.

  The detection of the scale adhesion state as described above is performed by arranging the electromagnetic ultrasonic probe at a specific position facing the object and performing a detection operation, and repeating the resonance peak group divided into a plurality of individual resonance peaks. If a resonance spectrum is obtained, it can be determined as a heterogeneous adhering part, but the electromagnetic ultrasonic probe is moved to a different position on the object and placed, and the resonance consists of repetition of a single resonance peak. When a spectrum is obtained, it is determined as a homogeneous adhesion part, and when a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks is obtained, it is determined as a heterogeneous adhesion part. It is preferable that the presence and distribution of the heterogeneous adhesion portion can be accurately detected.

  Thus, by detecting the adhesion state of the scale such as the lift of the steam oxide scale using electromagnetic ultrasonic resonance, the scale lift, separation boundary, step, It is possible to accurately detect the heterogeneous adhesion portion of the scale such as the thickness changing portion, thereby detecting a state where the steam oxidation scale generated in the steam system such as the superheater tube is separated and flying. In response to this, by taking measures such as acid cleaning and superheater tube replacement, it is possible to prevent wear corrosion of the turbine blade in the subsequent stage.

According to the present invention, the electromagnetic ultrasonic probe is moved to a different position and arranged opposite to the surface opposite to the surface of the substrate on which the scale is attached to the target with the scale attached to the substrate , The electromagnetic ultrasonic probe transmits an electromagnetic induction signal to generate ultrasonic waves on the object, receives the ultrasonic signal from the object, and changes the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe. And sweep, generate ultrasonic resonance to obtain a resonance spectrum, and when a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks is obtained, it is determined as a heterogeneous adhesion portion , Among the plurality of individual resonance peaks constituting each of the plurality of resonance peak groups having different resonance orders in the heterogeneous adhesion portion, the difference in resonance frequency between the individual resonance peaks in the corresponding relationship among the resonance peak groups having different resonance orders Calculate the total wall thickness including the base material and the attached scale from the difference in resonance frequency between the individual resonance peaks in other corresponding relations, and compare it with the wall thickness at the homogeneously attached part. Since the scale adhesion state is determined from the surface of the scale, the scale floats on the substrate such as the steam piping of the boiler and the separation boundary in high accuracy and in a short time even without contact by electromagnetic ultrasonic resonance. It is possible to detect the adhesion state of the scale in the non-uniform adhesion portion of the scale such as the portion, the step portion, and the thickness changing portion.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a detection apparatus according to an embodiment, FIG. 2 shows a detection method, (a) is a plan view, and (b) is a vertical sectional view thereof.

  In FIG. 1, 1 is an object to be detected, and shows an example of a steam system piping of a boiler in which a scale 1b is attached to the inner surface of a base material 1a. An electromagnetic ultrasonic probe 2 is a Lorentz type electromagnetic ultrasonic probe that transmits an electromagnetic induction signal to the object 1 from the outside in a non-contact manner and receives an ultrasonic signal. Reference numeral 3 denotes a transmission / reception control device that feeds a high-frequency current to the electromagnetic ultrasonic probe 2, transmits an electromagnetic wave as an electromagnetic induction signal to the object 1, generates an ultrasonic wave, and the electromagnetic ultrasonic probe 2 An ultrasonic signal is received from the object 1 and is detected as an induced current. 4 is an arithmetic control device, 5 is an interface, 6 is a display device such as an oscilloscope, and 7 is a preamplifier.

  The arithmetic and control unit 4 changes the frequency of the electromagnetic number as the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe 2 and sweeps it to generate ultrasonic resonance in the target 1, thereby causing the target 1 to An electromotive force or an electromagnetic wave generated by a sound wave is received as an ultrasonic signal by an electromagnetic ultrasonic probe, detected as an induced current, a resonance spectrum is obtained, and a resonance spectrum consisting of repetition of a single resonance peak (FIG. 5A ), (B), n-order, n + 1-order, n + second-order, etc.) in FIG. 8 (a) are determined to be homogeneous adhering portions, and the resonance peak group divided into a plurality of individual resonance peaks Repetitive resonance spectra (FIGS. 6 (a), (b), FIGS. 7 (a), (b), 8 (b), FIGS. 9 (a), (b), n-order, n + 1-order, n + second-order,・ ・) Is obtained, it is judged as a heterogeneous adhesion part. It is configured to.

  Further, the arithmetic and control unit 4 obtains a resonance spectrum (n-order, n + 1-order, n + second-order... In FIGS. 5A, 5B, and 8A) consisting of repetition of a single resonance peak. In this case, the entire thickness including the substrate 1a and the attached scale 1b is calculated from the difference in resonance frequency between adjacent resonance peaks.

  Further, the arithmetic and control unit 4 obtains a plurality of resonance peak groups having different resonance orders (FIGS. 6A and 6B) when a resonance spectrum composed of repetition of resonance peak groups divided into a plurality of individual resonance peaks is obtained. ), FIGS. 7A, 7B, 8B, 9A, 9B, nth order, n + 1 order, n + second order, etc.) 6 (a), (b), FIGS. 7 (a), (b), 8 (b), and in FIGS. 9 (a) and 9 (b), an, an + 1, an + 2..., Bn, bn + 1, bn + 2,. , Cn, cn + 1, cn + 2...), The difference in resonance frequency between individual resonance peaks (for example, an and an + 1, or an + 1 and an + 2) in a corresponding relationship among resonance peak groups having different resonance orders, Individual resonance peaks in other corresponding relations (for example, bn and bn + 1, Alternatively, the total thickness including the substrate 1a and the attached scale 1b is calculated by comparing with the difference in resonance frequency between bn + 1 and bn + 2, or cn and cn + 1, or cn + 1 and cn + 2.

  FIG. 2 shows a state in which an electromagnetic induction signal is transmitted from the outside and an ultrasonic signal is received by the Lorentz-type electromagnetic ultrasonic probe 2 to the object 1. The object 1 is different from FIG. 1 and shows a test piece made of a steel plate in which slits 8 used in Example 1 described later are formed. The electromagnetic ultrasonic probe 2 has a structure in which a transmission / reception coil 11 is arranged so as to face the object 1 in the magnetic field of two permanent magnets 9a, 9b in which NS magnetic poles are arranged in reverse. The transmission / reception coil 11 is formed by spirally forming a transmission coil and a reception coil, but is illustrated as a single coil.

  The detection by the above-mentioned device is performed by transmitting an electromagnetic wave generated by feeding a high-frequency current from the transmission / reception control device 3 to the transmission / reception coil 11 of the electromagnetic ultrasonic probe 2 as an electromagnetic induction signal by a signal from the arithmetic control device 4. An eddy current 12 is generated in a portion of the object 1 facing the transmission / reception coil 11 by electromagnetic induction. Points (·) and marks (x) illustrated in the transmission / reception coil 11 and the eddy current 12 indicate the directions of arrows indicating the direction of the current. Due to the generation of the eddy current 12, an ultrasonic wave is generated by the Lorentz force, and resonance occurs at a frequency at which the wavelengths of the transmitted wave 13 and the reflected wave 14 coincide with each other, and at a frequency that is an integral multiple thereof.

  In the object 1, an electromotive force is excited in a portion facing the transmission / reception coil 11 by the transmitted wave 13, the reflected wave 14, and a resonance wave generated when they match, and an electromagnetic wave as an ultrasonic signal generated by the electromotive force is generated. Is received by the transmission / reception coil 11 to generate an induced current. The induced current is amplified from the electromagnetic ultrasonic probe 2 by the preamplifier 7, the resonance spectrum is detected by the transmission / reception control device 3, input to the arithmetic control device 4, and the ultrasonic spectrum is displayed on the display device 6. When the frequency of the electromagnetic induction signal electromagnetic wave transmitted from the electromagnetic ultrasonic probe 2 is changed and swept by a signal from the arithmetic control device 4, ultrasonic resonance is generated at a constant frequency interval, and a resonance spectrum is generated on the display device 6. Is displayed.

  In the arithmetic and control unit 4, when a resonance spectrum consisting of repetition of a single resonance peak is obtained, it is determined as a homogeneous adhesion portion, and a resonance spectrum consisting of repetition of a resonance peak group divided into a plurality of individual resonance peaks is obtained. If it is, it is determined that it is a heterogeneous adhesion portion. Further, when a resonance spectrum composed of repetition of a single resonance peak is obtained, the arithmetic and control unit 4 determines the overall thickness including the substrate 1a and the attached scale 1b from the difference in resonance frequency between adjacent resonance peaks. Is calculated.

  Further, the arithmetic and control unit 4 obtains a plurality of resonance peak groups having different resonance orders (FIGS. 6A and 6B) when a resonance spectrum composed of repetition of resonance peak groups divided into a plurality of individual resonance peaks is obtained. ), FIGS. 7A, 7B, 8B, 9A, 9B, nth order, n + 1 order, n + second order, etc.) 6 (a), (b), FIGS. 7 (a), (b), 8 (b), and in FIGS. 9 (a) and 9 (b), an, an + 1, an + 2..., Bn, bn + 1, bn + 2,. .., Cn, cn + 1, cn + 2,...) Are in a corresponding relationship between adjacent resonance peak groups (for example, nth order and n + 1st order, or n + 1st order and n + second order). Between individual resonance peaks (eg, an and an + 1, or an + 1 and an + 2) The difference in resonance frequency is compared with the difference in resonance frequency between the individual resonance peaks having other corresponding relationships (for example, bn and bn + 1, or bn + 1 and bn + 2, or cn and cn + 1, or cn + 1 and cn + 2), and the substrate 1a + is attached. The thickness of the scale 1b is calculated, and the attached state of the scale is detected. In this case, the thickness of the scale attached to the base material is calculated from the difference in resonance frequency between the individual resonance peaks in the corresponding relationship, and the attached state of the scale corresponding to the difference in thickness is detected as the change in thickness. Can do.

In the object 1 made of a single metal, if the thickness is d and the ultrasonic sound velocity in the object 1 is C, the n-th individual resonance peak (FIGS. 6A, 6B, 7) (A), (b), 8 (b), and the resonance frequency fn of an, bn, cn) in FIGS. 9 (a) and 9 (b) can be expressed by the following equation (A).
fn = nC / 2d (A)
In the equation (A), the thickness d can be obtained by actually measuring the resonance spectrum and giving the resonance frequency fn, the ultrasonic velocity C, and the order n (integer).

Here, as shown below, the thickness can be calculated without using the order n. That is, for the resonance frequency fn + 1 of the resonance peak n + 1 order individual resonance peak (an + 1, bn + 1, cn + 1) adjacent to the nth order resonance peak, the following formula (B) is derived from the formula (A).
fn + 1 = (n + 1) C / 2d (B)
The following formula (C) is derived from the formulas (A) and (B).
fn + 1−fn = C / 2d (C)
In equation (C), if the resonance peak pairs fn + 1 and fn and the sound velocity C are known, the wall thickness d can be calculated.

The reason for using the formula (C) is as follows.
1) In the actually measured resonance spectrum, the order n may not be an integer.
2) Therefore, it is desirable not to use n in the detection of the thickness of an oxide scale showing various forms.
3) Only by paying attention to the resonance peak pairs fn + 1 and fn, the thickness detection including various oxide scales becomes possible, and the scale floating portion can be derived.

  The above formulas (A) to (C) are established for the object 1 made of a single metal. According to Non-Patent Document 1, as described above, when the scale adheres with a constant thickness, It shows that the phase of the resonance peak is shifted. However, even if the phase of each resonance peak shifts, the difference in resonance frequency between resonance peaks, particularly the difference in resonance frequency difference between adjacent resonance peaks, is small. Now, since the difference in resonance frequency is substantially negligible, the total thickness including the substrate and the attached scale is calculated with high accuracy from the difference in resonance frequency by the above equations (A) to (C). can do.

  Therefore, at the homogeneous adhesion site of the scale, resonance spectra consisting of repetition of a single resonance peak as shown in FIGS. 5 (a), 5 (b), 8 (a), nth order, n + 1st order, n + second order,. Is obtained, the wall thickness d can be calculated from the resonance peak pair by the above equations (A) to (C).

  On the other hand, when the thickness of the scale attached to the base material changes or in the non-uniformly attached portion such as peeling or floating, FIGS. 6 (a), (b), 7 (a), (b), 8 ( b), as shown in FIGS. 9A and 9B, each resonance peak is divided into a plurality of individual resonance peaks, and a plurality of individual resonance peaks (an, an + 1, an + 2..., bn, bn + 1, bn + 2..., cn, cn + 1, cn + 2...)) and a resonance peak group (n-order, n + 1-order, n + second-order...). This resonance peak group (n-order, n + 1-order, n + second-order ...) appears at substantially constant frequency intervals in the resonance spectrum in accordance with the above equations (A) to (C), and a plurality of resonance orders having different resonance orders. A group of resonance peaks appears repeatedly.

  Individual resonance peaks (an, an + 1, an + 2..., Bn, bn + 1, bn + 2..., Cn constituting a plurality of resonance peak groups (n-order, n + 1-order, n + second-order...) Having different resonance orders. , Cn + 1, cn + 2...) Have similarities that correspond to each other among a plurality of resonance peak groups having different resonance orders, and the peak position, height, It has a shape and the like. The individual resonance peaks (an, an + 1, an + 2..., Bn, bn + 1, bn + 2..., Cn, cn + 1, cn + 2...) Corresponding to each other correspond to a plurality of resonance peak groups having different resonance orders. Thus, each individual resonance peak appears at a different fixed frequency interval.

  These individual resonance peak positions, that is, characteristics such as frequency interval, height, shape, etc., represent different adhesion states such as scale thickness, separation, and lift, and each resonance peak group has a corresponding relationship. The resonance frequencies of the individual resonance peaks (for example, an, an + 1, an + 2...) In a corresponding relationship are changed to other corresponding relationships. Contrast with the difference in resonance frequency between certain individual resonance peaks (for example, bn, bn + 1, bn + 2...), And calculate the thickness of the scale attached to the substrate using the above formula (C), and change in the thickness. It is possible to detect the attached state of the scale.

  The scale adhesion state detected here is the difference in resonance frequency between individual resonance peaks in a corresponding relationship among resonance peak groups having different resonance orders, and the difference in resonance frequency between individual resonance peaks in other corresponding relationships. Scale adhering state that can be detected from the scale, but non-uniformly adhering part of scale, such as floating part of scale, peeling boundary part, step part, thickness changing part, etc. Change in scale thickness due to the difference in thickness at the part, peel thickness, lift thickness, and other scale thickness corresponding to the difference in thickness.

  As shown in FIG. 3 as the object 1, a steel plate (material: SS400) in which slit portions 15 having slits 8 and missing portions 17 are formed on both ends of a reference portion 16 having a uniform surface and thickness. A test piece consisting of: The unit of the numbers indicating the dimensions in FIG. 3 is mm. This test piece simulates the slit 8 as the raised part of the oxide scale, and simulates the missing part 17 as the peeling part, (1): the central part of the reference part 16, (2): the central part of the slit 8, ( 3): at the center of the slit boundary 18 that is the boundary between the reference portion 16 and the slit portion 15; and (4) at the center of the step 19 that is the boundary between the reference portion 16 and the lacking portion 17. The tactile elements 2 were moved and arranged so as to face each other, and detection was performed. As the transmission / reception control device 3, a RAM5000 manufactured by RITEC is used, the time width of the burst wave is 40 μs, the measurement frequency interval (resolution) is 1 to 2 kHz (same in the following examples), and the resonance is swept between the frequencies 1 to 2 MHz. A spectrum was obtained.

  FIG. 5A shows a resonance spectrum at the center of the reference portion 16, and a resonance spectrum consisting of repetition of a single resonance peak of the nth order, n + 1 order, n + second order,... It shows that it is a part. In FIG. 5A, the thickness calculation of the reference portion 16 based on the equation (C) based on the resonance peak pair method from adjacent resonance peaks is as follows, and a value corresponding to the thickness 10 mm in FIG. 3 is detected. ing.

[Reference part 16]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.286−1.124)[1/MHz]=9.927(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.448−1.286)[1/MHz]=9.927(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.608−1.448)[1/MHz]=10.051(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.768−1.608)[1/MHz]=10.051(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.932−1.768)[1/MHz]＝9.806(mm)

In FIG. 5 (a), as the thickness of the reference portion 16, the MAMR values (thickness obtained from the resonance spectrum) of 9.927mm, 10.050mm, and 9.806mm were calculated. 1 μm), it was 10.051 mm. Therefore, it was determined that 10.051 mm in the EMR value represents the thickness of the base metal part. Also, since the wall thickness value of 9.927 mm is obtained on the low frequency side of the measurement frequency range, the wall thickness excludes the effect of the bite (120 μm or less / upper and lower surfaces) remaining on the upper and lower surfaces of the test material. Can be evaluated. On the other hand, the value of 9.806mm is estimated to be the thickness due to multiple reflection echoes from the side of the test material because the test material size (40mm width) is not large with respect to the EMAT measurement area (16W × 15L (mm ² )). .

  From the above, the resonance spectrum in the central portion of the reference portion 16 in FIG. 5A is obtained by repeating a single resonance peak of the nth order, n + 1 order, n + second order,... Since the reference portion 16 has a uniform material and thickness, it indicates that it is homogeneous.

  FIG. 5B shows a resonance spectrum at the center of the slit portion 15. Like the reference portion 16, a resonance spectrum consisting of repetition of single resonance peaks of the nth order, n + 1 order, n + second order,... It is obtained and indicates a homogeneous part. In FIG. 5B, the calculation of the thickness of the reference portion 16 from the adjacent resonance peak based on the resonance peak pair method according to the above equation (C) is as follows, and is a value substantially corresponding to the thickness of 9.5 mm in FIG. Has been detected.

[Slit part 15]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.224−1.052)[1/MHz]=9.350(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.570−1.398)[1/MHz]=9.350(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.398−1.224)[1/MHz]=9.243(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.744−1.570)[1/MHz]=9.243(mm)
3216.4 [m / s] × 10 ⁻³ /2×1/(1.918−1.744)[1/MHz]=9.243(mm)

  In FIG. 5B, two thickness values (9.350 mm, 9.243 mm) are also obtained in the resonance spectrum of the slit portion 15. Considering the thickness of the bite (60 μm or less) and the discharge wire cut (150 μm or less), it can be determined that a value of 9.350 mm is appropriate as the thickness of the slit portion 15. The value of 9.243 mm seems to be the thickness due to the resonance spectrum from the side of the test material.

  From the above, the resonance spectrum in the central portion of the slit portion 15 in FIG. 5B is obtained by repeating a single resonance peak of the nth order, n + 1 order, n + second order,... Since the slit portion 15 has a uniform material and thickness, it indicates that it is homogeneous.

  As shown in FIGS. 5A and 5B, uniform adhering portions having a uniform material and thickness such as the reference portion 16 and the slit portion 15 are n-order, n + 1-order, n + second-order, and so on. A resonance spectrum composed of repetition of one resonance peak is obtained, but the center portion of the slit boundary portion 18 that is the boundary between the reference portion 16 and the slit portion 15 and the step portion 19 that is the boundary between the reference portion 16 and the lack portion 17 are obtained. In such a heterogeneous portion, it can be seen that a resonance spectrum composed of repetition of a group of resonance peaks divided into a plurality of individual resonance peaks is obtained. 6A shows the resonance spectrum at the center of the slit boundary 18 that is the boundary between the reference portion 16 and the slit portion 15, and FIG. 6B shows the step 19 that is the boundary between the reference portion 16 and the missing portion 17. The resonance spectrum in the center part of is shown.

  In FIG. 6 (a), a plurality of individual resonance peaks (an, an + 1, an + 2..., Bn, bn + 1, bn + 2 in FIG. 6 (a) are used as resonance spectra at the slit boundary portion 18 of the reference portion 16 and the slit portion 15. A resonance spectrum consisting of repetition of resonance peak groups n-order, n + 1-order, n + second-order, etc. divided into (...) is obtained. The individual resonance peaks an, an + 1, an + 2... And the individual resonance peaks bn, bn + 1, bn + 2... Have similarities that correspond to each other in the position, height, shape, etc. of the peaks. It repeats at almost equal intervals. From the individual resonance peaks (an + 2 and an + 3) of the reference portion 16 and the individual resonance peaks (bn + 4 and bn + 5) of the slit portion 15, the thickness calculation of the equation (C) by the resonance peak pair method is as follows.

[Reference part 16]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.456−1.294)[1/MHz]=9.927(mm)
[Slit part 15]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.922−1.750)[1/MHz]=9.350(mm)

  In FIG. 6A, small individual resonance peaks an, an + 1, an + 2... Appear at substantially the same interval, and the value corresponding to the thickness of the reference portion 16 is obtained from the difference in frequency between adjacent individual resonance peaks. The obtained individual resonance peaks correspond to the resonance peaks in the reference portion 16. Large individual resonance peaks bn, bn + 1, bn + 2... Appear at substantially the same interval, and a value corresponding to the thickness of the slit portion 15 is obtained from the difference in frequency between adjacent individual resonance peaks. It shows that the peak corresponds to the resonance peak in the slit portion 8. Among these individual resonance peaks, pairs of (an + 2) and (an + 3) and (bn + 4) are represented as individual resonance peak pairs relatively accurately representing the thickness of the reference portion 16 and the thickness of the slit portion 15. There are (bn + 5) pairs. The other individual resonance peak pairs are presumed to deviate from accurate values because they include the influence of the bite and the side of the test material, but are not clear.

  From the result of FIG. 6A, the resonance spectrum at the slit boundary portion 18 of the reference portion 16 and the slit portion 15 has a plurality of individual resonance peaks an, an + 1, an + 2. A resonance spectrum consisting of repetition of a plurality of resonance peak groups n-order, n + 1-order, n + second-order, etc. divided into a plurality of individual resonance peaks bn, bn + 1, bn + 2,. It turns out that it is obtained.

  As a resonance spectrum at the step portion 19 which is a boundary between the reference portion 16 and the lack portion 17 in FIG. 6B, the resonance spectrum is divided into a plurality of individual resonance peaks an, an + 1, an + 2... And bn, bn + 1, bn + 2. A resonance spectrum consisting of repetition of the resonance peak group n-order, n + 1-order, n + second-order, etc. is obtained. The individual resonance peaks an, an + 1, an + 2... And the individual resonance peaks bn, bn + 1, bn + 2... Have similarities that correspond to each other in the position, height, shape, etc. of the peaks. It repeats at almost equal intervals. From the individual resonance peaks (an + 3 and an + 4) of the reference portion 16 and the individual resonance peaks (bn + 3 and bn + 4) of the lacking portion 17, the thickness calculation of the equation (C) by the resonance peak pair method is as follows.

[Reference part 16]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.784−1.622)[1/MHz]=9.927(mm)
[Lack part 17]:
3216.4 [m / s] × 10 ⁻³ /2×1/(1.862−1.694)[1/MHz]=9.573(mm)

  In FIG. 6B, small individual resonance peaks an, an + 1, an + 2... Appear at substantially the same interval, and the value corresponding to the thickness of the reference portion 16 is obtained from the difference in frequency between adjacent individual resonance peaks. The obtained individual resonance peaks correspond to the resonance peaks in the reference portion 16. Large individual resonance peaks bn, bn + 1, bn + 2... Appear at approximately the same interval, and a value corresponding to the thickness of the lacking portion 17 is obtained from the difference in frequency between adjacent individual resonance peaks. It shows that the peak corresponds to the resonance peak in the missing part 17. Among these individual resonance peaks, pairs of (an + 3) and (an + 4) and (bn + 3) are represented as individual resonance peak pairs that relatively accurately represent the thickness of the reference portion 16 and the thickness of the missing portion 17. There are (bn + 4) pairs. The other individual resonance peak pairs are presumed to deviate from accurate values because they include the influence of the bite and the side of the test material, but are not clear.

  From the result of FIG. 6B, the resonance spectrum in the stepped portion 19 that is the boundary between the reference portion 16 and the lacking portion 17 is a plurality of individual resonance peaks (corresponding to the resonance peaks in the reference portion 16 (FIG. 6B)). an, an + 1, an + 2...) and a plurality of individual resonance peaks divided into a plurality of individual resonance peaks (bn, bn + 1, bn + 2... It can be seen that a resonance spectrum composed of repetitions of the nth order, n + 1st order, n + second order,... is obtained.

  From the results of FIGS. 6A and 6B, the inhomogeneity such as the slit boundary portion 18 that is the boundary between the reference portion 16 and the slit portion 15 and the step portion 19 that is the boundary between the reference portion 16 and the missing portion 17. In the resonance spectrum of the portion, a small resonance peak (an, an + 1, an + 2... In FIGS. 6A and 6B) representing the reference portion 16 and a large resonance peak representing the slit portion 15 or the lack portion 17 (FIG. 6 (a) and (b) appear bn, bn + 1, bn + 2..., And these constitute resonance peak groups (nth order, n + 1st order, n + second order...) As individual resonance peaks, A plurality of different resonance peak groups are repeated at intervals. The individual resonance peaks representing the reference portion 16 (an, an + 1, an + 2...), The slit portion 15 or the missing portion 17 in a plurality of resonance peak groups (n-order, n + 1-order, n + second-order,...) Having different resonance orders. (Bn, bn + 1, bn + 2,...) Have similarities in correspondence with each other in the peak position, height, shape, etc., and correspond to the slit portion 8, the reference portion 16, and the lack portion 17. It can be seen that the peaks can be identified.

  As shown in FIG. 4, a superheater tube (material: STBA24) of a power generation boiler in which lift of oxide scale was recognized was used as the object 1. 4A is a perspective view of a steel pipe as the object 1, FIG. 4B is an enlarged side view of the B part of the sample 1, and FIG. 4C is an enlarged side view of the B part of the sample 2, which is cut after the test. FIG.

A sample 1 shown in FIG. 4B of the object 1 is a pipe in which a scale 1b having a thickness of 0.3 mm is attached to the inner surface of a base material 1a made of steel and having a thickness of 7.3 mm. A raised portion 15a is formed in a portion close to the material 1a. A sample 2 shown in FIG. 4C is a pipe in which a scale 1b having a thickness of 0.5 mm adheres to the inner surface of a base material 1a made of steel and having a thickness of 9.3 mm, and is far from the base material 1a of the scale 1b. A raised portion 15b is formed in the portion. The electromagnetic ultrasonic probe 2 is disposed in the vicinity of the raised portion 15a of the sample 1 so as to be opposed to each other, swept at a frequency of 3.1 to 3.8 MHz, and the electromagnetic ultrasonic probe is located near the raised portion 15b of the sample 2. The tactile elements 2 were placed facing each other, swept between frequencies of 1.5 to 1.9 MHz, and detected in the same manner as in Example 1 to obtain a resonance spectrum.

FIG. 7A shows a resonance spectrum in the raised portion 15b , and FIG. 7B shows a resonance spectrum in the raised portion 15a .
When the resonance peak pair method is applied to boiler piping, individual resonance peaks (an, an + 1, an + 2, bn, bn + 1, bn + 2, cn, cn + 1) appearing in the waveform of a large resonance peak group (n-order, n + 1-order, n + second-order) ), The resonance peak pair fn + 1 and fn or fn + 2 and fn + 1 was selected based on the similarity.
Then, the thickness for each resonance peak pair is calculated according to the equation (C), and the maximum floating amount is estimated from the thickness difference.

From the individual resonance peaks (an and an + 1, bn and bn + 1, cn and cn + 1) of the resonance spectrum group (n-order, n + 1-order) in the floating portion 15b in FIG. The thickness calculation is as follows.
3,262.2 [m / s] × 10 ⁻³ /2×1/(1.805−1.635)[1/MHz]=9.595(mm)
3,262.2 [m / s] × 10 ⁻³ /2×1/(1.818−1.646)[1/MHz]=9.483(mm)
3,262.2 [m / s] × 10 ⁻³ /2×1/(1.833−1.658)[1/MHz]=9.321(mm)

The thickness calculated from the pair of individual resonance peaks as described above is the total thickness of the base material 1a and the scale 1b, but the difference between each pair of individual resonance peaks is caused by the scale 1b being lifted. It shows that. Therefore, calculating the maximum lifting thickness (the surface of the scale where there is no lifting and the thickness of the lifting pipe) based on the difference between the maximum wall thickness and the minimum wall thickness is as follows. .
Maximum lift thickness = 9.595-9.321 = 0.274mm

From the individual resonance peaks (an and an + 1, bn and bn + 1, ann and bn + 1, bn + 1 and bn + 2, bn + 1 and bn + 2) of the resonance spectrum group (n-order, n + 1-order, n + second-order) in the floating portion 15a in FIG. The thickness calculation of the formula (C) is as follows.
3,262.2 [m / s] × 10 ⁻³ /2×1/(3.432−3.220)[1/MHz]=7.694(mm)
3,262.2 [m / s] × 10 ⁻³ /2×1/(3.438−3.230)[1/MHz]=7.842(mm)
3,262.2 [m / s] × 10 ⁻³ /2×1/(3.642−3.432)[1/MHz]=7.767(mm)
3,262.2 [m / s] × 10 ⁻³ /2×1/(3.650−3.438)[1/MHz]=7.694(mm)

As in the case of FIG. 7A, the maximum lifted thickness is calculated from the difference between the maximum thickness and the minimum thickness as follows.
Maximum lift thickness = 7.842-7.694 = 0.148mm

  As described above, the thickness calculation by the equation (C) by the resonance peak pair method for each individual resonance peak indicates that there are portions having different thicknesses, and these correspond to the raised portions 15a and 15b of the scale 1b. Therefore, it can be understood that the scale lifting state can be detected by calculating the thickness calculation by the equation (C) by the calculation control device 4.

  Using the superheater tube (material: 2.25Cr-1Mo low alloy steel tube and SUS304 stainless steel tube) of the actual boiler of the thermal power plant, select the part where there is no unevenness or clinker adhesion on the outer surface of the pipe, Move the transducer, measure the resonance spectra of different parts, and determine whether the oxide scale is peeled off or lifted from the difference in the thickness of the spectrum form (resonance peak position, height, shape, etc.) and the resonance peak pair. . Then, at the measurement site where the thickness difference was recognized, the microscopic photograph and the scanning electron microscope (SEM) photograph of the tube cross section were performed.

  In the measurement of resonance spectrum, the optimum measurement frequency range and frequency resolution were selected as approximately 2.0 to 3.0 MHz and 2 kHz, respectively, and the resonance spectrum measurement of low alloy steel pipe (2.25Cr-1Mo) and stainless steel pipe (SUS304) was performed. . Resonance spectra consisting of repeated single resonance peaks were obtained at sites where the properties of the oxide scale were homogeneous, but multiple individual resonances were observed at heterogeneous sites where abnormalities such as exfoliation and lift were observed on the oxide scale. A resonance spectrum consisting of repetition of resonance peak groups n-order, n + 1-order, n + second-order, etc. divided into peaks was obtained. The thickness was calculated from the resonance frequency difference between the divided individual resonance peak pairs, the thickness difference was obtained for each adjacent resonance peak pair, and was shown in the form of maximum and average.

  FIG. 8 (a) shows a resonance spectrum at a site recognized as a homogeneous adhesion portion of a low alloy steel pipe. The resonance spectrum consisting of repetition of a single resonance peak of nth order, n + 1st order, n + second order,... Has been obtained. In FIG. 8A, the thickness calculation by the above equation (C) based on the resonance peak pair method from adjacent resonance peaks is as follows. The following formula shows the calculation process in a simplified manner.

3.2622 / 2 × 1 / (2.282-2.120) = 10.069 (mm)
3.2622 / 2 × 1 / (2.444-2.282) = 10.069 (mm)
3.2622 / 2 × 1 / (2.604-2.444) = 10.194 (mm)
3.2622 / 2 × 1 / (2.768-2.604) = 9.946 (mm)
3.2622 / 2 × 1 / (2.930-2.768) = 10.069 (mm)
Average wall thickness: 10.069mm

  From the result of FIG. 8A, the resonance spectrum consists of repetition of a single resonance peak, and since there is no difference in thickness, it is recognized that the resonance spectrum is a homogeneous adhesion portion without any scale lift or step difference. FIG. 11 shows a microscopic microphotograph (100 times) of a homogeneous adhesion portion different from the measurement site in FIG.

  FIG. 8 (b) shows a resonance spectrum at a site recognized as a heterogeneous adhesion portion of a low alloy steel pipe, and is divided into a plurality of individual resonance peaks an, an + 1, an + 2... And bn, bn + 1, bn + 2. A resonance spectrum composed of repeated resonance peak groups n-order, n + 1-order, n + second-order, etc. is obtained. In FIG. 8B, the wall thickness calculation based on the equation (C) based on the resonance peak pair method from adjacent individual resonance peaks is as follows.

[Individual resonance peaks an, an + 1, an + 2 ...]
3.2622 / 2 × 1 / (2.462-2.268) = 8.408 (mm)
3.2622 / 2 × 1 / (2.654-2.462) = 8.495 (mm)
3.2622 / 2 × 1 / (2.846-2.654) = 8.495 (mm)
3.2622 / 2 × 1 / (3.038-2.846) = 8.495 (mm)

[Individual resonance peaks bn, bn + 1, bn + 2...]
3.2622 / 2 × 1 / (2.486-2.286) = 8.156 (mm)
3.2622 / 2 × 1 / (2.678-2.486) = 8.495 (mm)
3.2622 / 2 × 1 / (2.874-2.678) = 8.322 (mm)
3.2622 / 2 × 1 / (3.066-2.874) = 8.495 (mm)

  In the wall thickness calculation in FIG. 8 (b), the wall thickness difference is calculated from the wall thickness of the corresponding order of the resonance peak pairs. The maximum thickness is 252 μm, but it may be zero and the average is 106 μm. It is recognized. FIG. 12 shows a micromicrograph (100 times) showing a cross section of the tube at the measurement site in FIG. 8B, and FIG. 13 shows a scanning electron micrograph (1000 times). From FIGS. 12 and 13, floating was observed at the boundary between the base material and the inner scale layer.

  FIG. 9 (a) shows resonance spectra at other sites recognized as heterogeneous adhesion portions of the low alloy steel pipe, and a plurality of individual resonance peaks an, an + 1, an + 2... And bn, bn + 1, bn + 2. A resonance spectrum composed of repetitions of the resonance peak group n-order, n + 1-order, n + second-order, etc. divided into two is obtained. In FIG. 9 (a), the thickness calculation by the above equation (C) based on the resonance peak pair method from adjacent individual resonance peaks is as follows.

[Individual resonance peaks an, an + 1, an + 2 ...]
3.2622 / 2 × 1 / (2.436-2.244) = 8.495 (mm)
3.2622 / 2 × 1 / (2.626-2.436) = 8.585 (mm)
3.2622 / 2 × 1 / (2.814-2.626) = 8.676 (mm)
3.2622 / 2 × 1 / (3.006-2.814) = 8.495 (mm)

[Individual resonance peaks bn, bn + 1, bn + 2...]
...
3.2622 / 2 × 1 / (2.642-2.454) = 8.676 (mm)
3.2622 / 2 × 1 / (2.832-2.642) = 8.585 (mm)
3.2622 / 2 × 1 / (3.024-2.832) = 8.495 (mm)

  In the wall thickness calculation of FIG. 9 (a), the wall thickness difference is calculated from the wall thickness of the corresponding order of the resonance peak pair. The maximum is 91 μm, but it may be zero and negative, and the average is 61 μm. Adhered part is recognized. FIG. 14 shows a microscopic micrograph (100 ×) showing a cross section of the tube at the measurement site in FIG. 9A, and FIG. 15 shows a scanning electron micrograph (1000 ×). As shown in FIGS. 14 and 15, floating was observed in the middle part of the inner layer of the scale attached to the base material.

  FIG. 9 (b) shows a resonance spectrum at a site recognized as a heterogeneous adhesion portion of the stainless steel pipe, which is divided into a plurality of individual resonance peaks an, an + 1, an + 2... And bn, bn + 1, bn + 2. A resonance spectrum consisting of repetition of the resonance peak group n-order, n + 1-order, n + second-order, etc. is obtained. In FIG. 9B, the wall thickness calculation based on the equation (C) based on the resonance peak pair method from adjacent individual resonance peaks is as follows.

[Individual resonance peaks an, an + 1, an + 2 ...]
3.0680 / 2 × 1 / (1.784-1.606) = 8.618 (mm)
3.0680 / 2 × 1 / (1.960-1.784) = 8.716 (mm)
3.0680 / 2 × 1 / (2.138-1.960) = 8.618 (mm)
3.0680 / 2 × 1 / (2.314-2.138) = 8.716 (mm)

[Individual resonance peaks bn, bn + 1, bn + 2...]
3.0680 / 2 × 1 / (1.792-1.614) = 8.618 (mm)
3.0680 / 2 × 1 / (1.968-1.792) = 8.716 (mm)
3.0680 / 2 × 1 / (2.144-1.968) = 8.716 (mm)
3.0680 / 2 × 1 / (2.322-2.144) = 8.618 (mm)

  In the wall thickness calculation of FIG. 9 (b) above, when the wall thickness difference is calculated from the wall thickness of the corresponding order of the resonance peak pair, it is 98 μm at the maximum, but it may be zero and negative, and the average is 49 μm. Adhered part is recognized. FIG. 16 shows a micromicrograph (100 times) showing a cross section of the tube at the measurement site in FIG. 9B, and FIG. 17 shows a scanning electron micrograph (500 times). 16 and 17, a part of the outer layer further adhered onto the inner layer of the scale adhered to the base material was peeled off and a stepped portion was formed.

  From the series of test results of Example 3 above, a characteristic morphological correlation is recognized between the resonance spectrum and the cross-sectional observation result. In other words, in the case of a low alloy steel pipe, when the oxide scale is raised at the boundary between the base material and the inner layer of the scale, the resonance peak appears in a form in which the resonance peak is divided into a plurality of individual resonance peaks. In addition, when floating occurs in the inner layer scale, the resonance spectrum is divided into large and small individual resonance peaks. On the other hand, sharp resonance peak cracks were observed in the stainless steel pipes, and the difference in thickness between them indicates peeling of the scale. When comparing the lift amount estimated from the resonance spectrum and cross-sectional observation, it is necessary to consider that the former has a wide measurement area for surface measurement, while the latter has a difference that the observation area is narrow for line measurement. However, the maximum lift calculated from the resonance spectrum is considered to roughly correspond to the lift position (boundary between the base material and the inner layer of the scale or the inner layer of the scale) as seen in the microphotograph. It is done.

  FIG. 10 shows a resonance spectrum having a measurement frequency range of 1.4 to 2.4 MHz corresponding to the resonance spectrum of FIG. 9A, and the frequency resolution is 2 kHz, as in FIG. 9A. Although only a single resonance peak appears in the resonance spectrum in the low frequency range shown in FIG. 10, a plurality of individual resonance peaks that show rising of the oxide scale are shown in the resonance spectrum in the high frequency range shown in FIG. Resonance peak groups divided into two appear. Therefore, in order to detect scale peeling or lifting, it is necessary to select an appropriate sweep frequency range in which a group of resonance peaks divided into a plurality of individual resonance peaks appears. Such a sweep frequency range varies depending on the substrate, scale material, composition, thickness, and the like, and can be determined by a preliminary test.

  Method of detecting scale adhesion such as boiler thickness, steam system piping, especially steam system piping for thermal power boilers, etc. And available to the device.

It is a block diagram which shows the detection apparatus of embodiment. (A) is a plan view showing a detection method, and (b) is a vertical sectional view thereof. 1 is a perspective view showing an object 1 of Example 1. FIG. (A) is a perspective view which shows the target object 1 of Example 2, (b) is an enlarged side view of the B part of the sample 1, (c) is an enlarged side view of the B part of the sample 2. (A) is the resonance spectrum in the center part of the reference | standard part 16 of Example 1, (b) is a diagram which shows the resonance spectrum in the center part of the slit part 15. FIG. (A) is the resonance spectrum in the slit boundary part 18 of Example 1, (b) is a diagram which shows the resonance spectrum in the level | step-difference part 19. FIG. (A) is a resonance spectrum in the floating part 15b of Example 2, (b) is a diagram which shows the resonance spectrum in the floating part 15a . (A) is the resonance spectrum in the site | part recognized as the homogeneous adhesion part of the low alloy steel pipe of Example 3, (b) is a diagram which shows the resonance spectrum in the site | part recognized as the heterogeneous adhesion part of a low alloy steel pipe. (A) is the resonance spectrum in the other site | part recognized as the heterogeneous adhesion part of the low alloy steel pipe of Example 3, (b) is a diagram which shows the resonance spectrum in the site | part recognized as the heterogeneous adhesion part of a stainless steel pipe. . It is a diagram which shows the resonance spectrum whose measurement frequency range corresponding to the resonance spectrum of Fig.9 (a) is 1.4-2.4MHz. It is a micromicrograph of a homogeneous adhesion part. A microscopic micrograph showing the cross section of the measurement site in FIG. It is a scanning electron micrograph which shows the pipe cross section of the measurement site | part of FIG.8 (b). A micromicrograph showing the cross section of the measurement site in FIG. 9 (a), It is a scanning electron micrograph which shows the pipe cross section of the measurement site | part of Fig.9 (a). A microscopic micrograph showing the cross section of the measurement site in FIG. It is a scanning electron micrograph which shows the pipe cross section of the measurement site | part of FIG.9 (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Object 2 Electromagnetic ultrasonic probe 3 Transmission / reception control apparatus 4 Operation control apparatus 5 Interface 6 Display apparatus 7 Preamplifier 8 Slit 9a, 9b Permanent magnet 11 Transmission / reception coil 12 Eddy current 13 Transmission wave 14 Reflected wave 15 Slit part 15a, 15b Lifting portion 16 Reference portion 17 Missing portion 18 Slit boundary portion 19 Step portion

Claims (8)

The electromagnetic ultrasonic probe is moved to a different position and placed opposite to the surface opposite to the surface of the substrate with the scale attached to the substrate .
The electromagnetic ultrasonic probe transmits an electromagnetic induction signal to generate an ultrasonic wave on the object, and receives an ultrasonic signal from the object.
Sweeping by changing the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe, obtaining the resonance spectrum by generating ultrasonic resonance,
When a resonance spectrum consisting of repetition of a single peak is obtained as a resonance peak with a different resonance order, it is determined as a homogeneous adhesion portion,
Calculate the overall wall thickness including the base material and the attached scale from the difference in resonance frequency in the homogeneous adhesion part,
When a resonance spectrum consisting of a repetition of a group of resonance peaks divided into a plurality of individual resonance peaks corresponding to each other at different resonance orders is obtained as a resonance peak having different resonance orders, it is determined as a heterogeneous adhesion portion ,
Among the plurality of individual resonance peaks constituting each of the plurality of resonance peak groups having different resonance orders in the heterogeneous adhesion portion, the difference in resonance frequency between the individual resonance peaks in the corresponding relationship among the resonance peak groups having different resonance orders Calculate the total wall thickness including the base material and the attached scale from the difference in resonance frequency between the individual resonance peaks in other corresponding relations, and compare it with the wall thickness in the homogeneously attached part. A method for detecting a scale adhesion state, wherein the scale adhesion state is determined from the difference . An electromagnetic ultrasonic probe transmits an electromagnetic wave generated by applying a high-frequency current to a transmitting coil in a magnetic field as an electromagnetic induction signal, generates an eddy current in the object by electromagnetic induction, and in the object by Lorentz force causing ultrasonic vibration method of claim 1 Symbol placement is of the Lorentzian taking out an electromotive force excited by this as an induction current in the receiver coil as an ultrasonic signal. The method of the corresponding individual resonance peaks in a relationship is individual resonance peak pairs in the corresponding relationship in the resonance peaks adjacent claim 1 or 2 wherein. The method according to any one of claims 1 causes ultrasound 1.0~3.5MHz the object 3. An electromagnetic ultrasonic probe that transmits an electromagnetic induction signal to an object having a scale attached to the substrate and receives an ultrasonic signal; and
A moving arrangement device that moves and arranges the electromagnetic ultrasonic probe to a different position opposite to the surface opposite to the surface of the substrate on which the scale is attached to the substrate with the scale attached to the substrate ,
Transmission / reception control that generates an ultrasonic wave by transmitting an electromagnetic induction signal from an electromagnetic ultrasonic probe to an object with a scale attached to the substrate, and receives an ultrasonic signal from the object by the electromagnetic ultrasonic probe Equipment,
Resonance spectrum is obtained by changing the frequency of the electromagnetic induction signal transmitted from the electromagnetic ultrasonic probe and sweeping it to obtain a resonance spectrum. Resonance peaks consist of repeated single peaks as resonance peaks with different resonance orders. When a spectrum is obtained, it is judged as a homogeneously attached part, and the total thickness including the substrate and attached scale is calculated from the difference in resonance frequency at the homogeneously attached part, and resonances with different resonance orders are obtained. When a resonance spectrum consisting of a repetition of resonance peak groups divided into a plurality of individual resonance peaks having a correspondence relationship in order is obtained, it is determined as a heterogeneous adhesion portion, and a plurality of resonance orders having different resonance orders in the heterogeneous adhesion portion are determined . Individual resonance peaks corresponding to each other among the resonance peak groups having different resonance orders among the plurality of individual resonance peaks constituting the resonance peak groups. From the difference in resonance frequency between ringing peaks and the difference in resonance frequency between individual resonance peaks in other corresponding relations, the total wall thickness including the substrate and the attached scale is calculated, and the with comparison with the thickness detection apparatus of the scale deposition condition, characterized in that it comprises an arithmetic control unit for determining the state of adhesion of scale from the difference in thickness. An electromagnetic ultrasonic probe transmits an electromagnetic wave generated by applying a high-frequency current to a transmitting coil in a magnetic field as an electromagnetic induction signal, generates an eddy current in the object by electromagnetic induction, and in the object by Lorentz force causing an ultrasonic vibration device of claim 5 Symbol mounting is of the Lorentzian taking out an electromotive force excited by this as an induction current in the receiver coil as an ultrasonic signal. The apparatus according to claim 5 or 6 , wherein the individual resonance peaks in a correspondence relationship are individual resonance peak pairs in a correspondence relationship in adjacent resonance peak groups. The device according to any one of claims 5 to 7 , wherein the transmission / reception control device generates an ultrasonic wave of 1.0 to 3.5 MHz on the object.