JP5073538B2 - Wall damage detection apparatus and damage detection method - Google Patents

Description

  The present invention is a technique for detecting damage to a wall surface, and is particularly suitable for detecting damage such as broken holes opened in a furnace wall in a high-temperature atmosphere by ultrasonic waves in a furnace such as a coke oven carbonization chamber. Regarding technology.

  For example, a coke oven in the steel industry is composed of a plurality of carbonization chambers and combustion chambers between the carbonization chambers, and a partition wall between the carbonization chamber and the adjacent combustion chamber is composed of a refractory. The carbonizing chamber of a coke oven is operated continuously for a long period of 20 years or more under severe conditions, and the refractory bricks constituting the carbonizing chamber gradually deteriorate due to thermal, chemical and mechanical factors. . For this reason, when the strength of the refractory constituting the partition wall between the combustion chambers is reduced due to deterioration of the refractory brick, the brick may fall off due to the side pressure applied when the coke is extruded, or a wider range may collapse. This is called a hole. If coke production is continued using the carbonization chamber with a hole in the partition wall separating the carbonization chamber and the combustion chamber, gas flow will occur between the carbonization chamber and the combustion chamber through the hole and through the hole. Coal to be treated is pushed out from the carbonization chamber into the combustion chamber, causing troubles such as blockage of the combustion chamber, blockage of the heat storage chamber, generation of black smoke, cracking of the combustion chamber brick, and damage to the furnace body.

  Conventionally, as means for grasping the state of damage to the furnace wall brick in the coke oven carbonization chamber, for example, the uneven shape of the furnace wall is obtained by a triangulation method or a light wave distance meter combining a laser and an image sensor described in Patent Document 1. Methods for measuring are known. However, the distance measurement means using light in a dust environment with an ambient temperature exceeding 1000 ° C. has a problem that it is necessary to take sufficient measures against heat and dust of the light emitter / receiver, which increases the cost of the apparatus or maintenance. .

  In addition, a method for measuring the concavo-convex shape by distance measuring means using microwaves or millimeter waves as a wave source strong against heat and dust has been proposed as described in Patent Document 2, for example. However, since microwave and millimeter-wave devices are expensive not only for antennas but also for oscillators, mixers, and waveguides necessary for transmission and reception, the number of sensors cannot be increased. With a small number of sensors, in order to inspect the entire furnace wall, it is necessary to scan two-dimensionally and it takes a long measurement time. Therefore, the inspection during the actual extrusion operation is limited to a part of the wall.

  In the above-mentioned patent document, it is possible to know the uneven shape of the furnace wall by a method using a distance meter, but a signal processing method when there is a hole in the furnace wall or a method for detecting a hole is described. It has not been.

  On the other hand, an airborne ultrasonic sensor is applied to a level meter in a high temperature environment such as a liquid level meter described in Patent Document 3 as a sensor resistant to dust. Since the speed of sound of ultrasonic waves changes depending on the temperature in the atmosphere, a layer in which the temperature changes can be regarded as a layer having a refractive index different from that of the ultrasonic wave. For this reason, there is a problem that ultrasonic waves cannot be stably detected due to refraction of ultrasonic waves in an atmosphere having a temperature distribution. However, in Patent Document 3, a high-temperature liquid surface of 300 ° C. or higher, preferably about 400 to 700 ° C. When measuring, a high-temperature air layer near the liquid surface is blown away by flowing a fluid with a constant temperature and a constant flow velocity through the path of ultrasonic waves inside and outside the waveguide. In particular, sound waves are guided outside the waveguide by creating a low-temperature layer having a higher refractive index (lower speed of sound) toward the inner side. Patent Document 4 discloses an ultrasonic level meter for measuring the level of a melt in a melting furnace or the like that generates a large amount of dust at a high temperature. In this document, an ultrasonic sensor installed outside the furnace is transmitted and received, and an ultrasonic wave is propagated in an L-shaped waveguide and guided into the furnace. It is said that it is possible to measure.

  However, the liquid level gauge using ultrasonic waves described in Patent Document 3 has a large area and a flat liquid surface position compared to the broken hole at a temperature much lower than that of a coke oven in an operating state. This is an apparatus for measuring, and has a large apparatus configuration for supplying a fluid and flowing it in the atmosphere. Further, in the ultrasonic level meter described in Patent Document 4, the ultrasonic sensor itself is disposed outside the furnace. Therefore, these technologies using the ultrasonic sensor should be applied as they are to measure the ultrasonic sensor in the furnace when detecting damage to the wall of the coke oven having a length of 10 m or more. There were great difficulties.

JP 2001-3058 A JP 2002-80852 A JP 63-73117 A Japanese Patent Laid-Open No. 5-240681

  In view of the above-mentioned problems of the prior art, the present invention is capable of performing damage such as a hole in the wall quickly and accurately, which can be performed simultaneously with the coke extrusion operation using an ultrasonic sensor. An object of the present invention is to provide a technique for detecting by a simpler apparatus configuration and procedure.

  The gist of the present invention is as follows.

  The wall damage detection apparatus according to the present invention emits an ultrasonic wave by an ultrasonic transmission / reception sensor toward a wall in a high-temperature atmosphere, and receives the reflected wave by the ultrasonic transmission / reception sensor. An ultrasonic damage detection device that scans along a wall to detect damage to a wall, the opening end faces the wall, the ultrasonic transmission / reception sensor is provided at the other end, and a cooling gas is allowed to flow inside. An L-shaped waveguide for propagating ultrasonic waves generated by the ultrasonic transmission / reception sensor and a cooling gas supplied to the ultrasonic transmission / reception sensor and the waveguide connected to the other end of the waveguide. An ultrasonic burst wave is generated by driving the blower tube and the ultrasonic transmission / reception sensor, and the presence or absence of a reflected wave from the wall is determined based on the amplitude and reception time of the reception signal output from the ultrasonic transmission / reception sensor. Detect and the reflected wave is detected A distance measuring means for outputting the distance from the ultrasonic transmission / reception sensor to the reflection point on the wall surface as a distance value when a reflected wave is not detected, and the ultrasonic transmission / reception sensor on the wall surface. The missing value is calculated based on the scanning position detecting means for scanning along the scanning position and detecting the scanning position, the scanning position detected by the scanning position detecting means and the distance value measured by the distance measuring means. The signal processing means for determining the presence or absence of wall damage based on the number of consecutive missing measurements continuously detected, and the display means for displaying the position of the wall damage determined by the signal processing means And

  Also, in the furnace wall damage detection apparatus of the present invention, the distance measuring means includes an amplitude detection unit for detecting the amplitude of the ultrasonic reception signal, and a maximum value of the amplitude of the reception signal within a preset time domain. And a maximum amplitude detector that detects the reception time of the reflected wave, which is the time for giving the maximum value, and based on the reception time and transmission time of the ultrasonic wave when the maximum value of the amplitude satisfies a preset threshold value And a distance calculation unit that outputs the distance from the ultrasonic transceiver to the wall calculated as described above and outputs a missing value as a distance value when the distance is not satisfied.

  Further, in the furnace wall damage detection device of the present invention, the signal processing device is configured to detect the distance based on the scanning position of the wall surface of the ultrasonic transmission / reception sensor and the distance value output from the scanning distance measuring means. It is characterized by comprising a damage discriminating unit for discriminating and detecting a damaged part of the wall on the basis of the number of consecutive missing measurements in which the missing side value is set in advance.

  Furthermore, a plurality of L-shaped waveguides having the ultrasonic transmission / reception sensor are arranged in parallel in a direction orthogonal to the scanning direction.

  In the method for detecting damage to a furnace wall according to the present invention, an ultrasonic wave is emitted from an ultrasonic transmission / reception sensor toward a wall in a high temperature atmosphere, and the ultrasonic transmission / reception sensor is received while receiving the reflected wave by the ultrasonic transmission / reception sensor. An ultrasonic damage detection method for detecting damage to a wall by scanning along a wall, wherein an open end faces the wall and an L-shaped waveguide is provided with the ultrasonic transmission / reception sensor at the other end. A step of propagating an ultrasonic burst wave generated by the ultrasonic transmission / reception sensor while flowing a cooling gas through the air pipe connected to the waveguide to the tube, and the ultrasonic transmission / reception sensor reflects the reflected wave on the wall The step of detecting the amplitude of the received ultrasonic wave, which is an ultrasonic wave, and outputting the received signal, the maximum value of the amplitude of the received ultrasonic wave within the preset reception time region, and the time of the maximum value as the reception time Detecting, and a maximum of said amplitude Calculating the distance from the transmission / reception sensor to the wall based on the ultrasonic reception time and transmission time when the threshold value satisfies a preset threshold value, and outputting the missing value as the distance value when the threshold value is not satisfied A step of recording the distance value while scanning the ultrasonic sensor along the wall, and a portion of the wall where the number of consecutive missing values of the distance value satisfies a preset number of consecutive missing times. And a step of determining and detecting as a damaged portion.

  The present invention uses an ultrasonic transmission / reception sensor, compares the maximum amplitude within the reception time region of the reception ultrasonic wave with a threshold value, determines the presence or absence of the reception ultrasonic wave, and determines the wavehole by the continuity of the missing value. To detect. By using inexpensive ultrasonic sensors, it is possible to increase the number of sensors than before, and when applied to the detection of damage to coke oven furnace walls, it is possible to perform inspection simultaneously during extrusion operations. Yes, it is possible to detect a puncture early.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a wall surface damage detection apparatus and detection method according to the present invention will be described below in detail with reference to the drawings, taking as an example the case of detecting a hole in a coke oven furnace wall in the steel industry. First, an outline of the arrangement and configuration of the damage (broken hole) detection device will be described with reference to FIGS. 1 and 2, and the components of the device and the damage detection method will be described in detail with reference to other drawings.

<First Embodiment>
FIG. 1 is a schematic view of the structure of the furnace wall damage detection apparatus according to the present embodiment, and is a view of a hearth of a single coke oven carbonization chamber surrounded by the furnace wall 6 as viewed from above. . An ultrasonic transmission / reception sensor (ultrasonic sensor) 1 composed of an ultrasonic transducer for transmitting / receiving ultrasonic waves to / from the furnace wall 6 is disposed inside the waveguide 11, and the waveguide 11 is made of coke. It is attached to the extrusion beam 51 of the extruder 5, and the ultrasonic wave injection port 11a of the waveguide 11 is directed to the furnace wall 6 on both sides of the carbonization chamber. As will be described later with reference to FIG. 2, only one or a plurality of waveguides 11 are arranged in the height direction and arranged in the height direction in the extruded beam 51. Hereinafter, a configuration in which a plurality of waveguides 11 including the ultrasonic transmission / reception sensor 1 are arranged in parallel will be described. Since a plurality of ultrasonic sensors are arranged in this way, a plurality of distance meters 2 for driving the ultrasonic transmission / reception sensor 1 are also arranged in the main body of the extruder 5 so as to correspond to each sensor on a one-to-one basis. The blower 16 that cools the ultrasonic transmission / reception sensor 1 in the high-temperature carbonization chamber and blows the cooling gas for stably guiding the ultrasonic wave is not necessarily one-to-one, but depending on the blowing capacity. A plurality of units may be arranged on the main body of the extruder 5. Further, the signal line 14 connecting the ultrasonic transmission / reception sensor 1 and the distance meter 2 supplies cooling gas to the ultrasonic transmission / reception sensor 1 and the waveguide 11, and has a heat-resistant air duct that also serves as a protective tube. 15 is wired. The blower tube 15 may be made of a ceramic tube such as alumina or SiN, or a stainless tube. Furthermore, on the extruder 5 main body outside the coke oven, the distance value from the ultrasonic transmission / reception sensor 1 output from the plurality of distance meters 2 to the furnace wall 6 is recorded to detect the presence or absence of a broken hole. A signal processing device 3 and a display device 4 for displaying a hole detection result are mounted. In addition, the encoder 52 for detecting the extrusion distance is attached to the push beam 51, the distance value from the ultrasonic transmission / reception sensor 1 output from the distance meter 2 to the furnace wall 6 by the signal processing device 3, and the ultrasonic sensor Information on the measurement position of the ultrasonic transmission / reception sensor 1 in the scanning direction, that is, in the pushing direction (the depth direction of the carbonization chamber) is recorded in a recording device (not shown) constituted by a semiconductor memory, a hard disk, a DVD, or the like.

  FIG. 2 is a layout view of a plurality of waveguides 11 attached to the extruder 5 shown in FIG. 1 as viewed from a direction perpendicular to the furnace wall 6. As will be described in detail later in the description of FIG. 3, the waveguide 11 has an L-shaped structure, is parallel to the hearth 7, and the ultrasonic wave injection port 11 a transmits ultrasonic waves to the furnace wall. 6 is arranged so as to be fired perpendicularly. Although it is good to detect the damage of each furnace wall brick if it arrange | positions in the height direction of the furnace wall 6 of the waveguide 11 at the same space | interval as a furnace wall brick, it is necessary to arrange as many as the number of bricks of a height direction. However, it may be intensively arranged at a place where a hole is expected to occur.

  FIG. 3 shows the arrangement of the waveguide 11 and the components attached to the waveguide 11. The ultrasonic transmission / reception sensor 1 is an ultrasonic transducer for both transmission and reception, and is attached to the inside of the waveguide 11 via a sensor mount 13. As the ultrasonic sensor 1, a so-called aerial ultrasonic sensor of a type in which a matching device such as a cone resonator is connected to a piezoelectric element can be used. In order to avoid direct exposure of the ultrasonic transmission / reception sensor 1 to radiant heat due to a high temperature atmosphere in the coke oven, the waveguide 11 has an L-shaped structure, and the opening end of the waveguide 11 serves as an ultrasonic injection port 11a. Opposite to. Further, in order to prevent radiation from being reflected on the inner wall of the waveguide 11 and entering the ultrasonic transmission / reception sensor 1, the inside of the waveguide 11 including the reflecting surface of the reflecting mirror 12 is painted black with a heat-resistant substance. It has been. Further, the reflectance of visible light and infrared light may be reduced by processing the inside of the waveguide 11 into a rough surface. A blower pipe 15 is connected to the other end portion 11b of the waveguide 11, and at the same time as sending a cooling gas such as air or nitrogen gas from the blower 16 shown in FIG. It plays the role which protects the signal wire | line 14 which connects the ultrasonic sensor 1 arrange | positioned inside and the distance meter 2 shown in FIG. 1 from a heat | fever. The blower tube 15 may be made of the same material as that of the waveguide 11, but may be another member having heat resistance with respect to the temperature of about 1000 ° C. which is an atmosphere. The sensor mount 13 has a hole through which a cooling gas passes. The sensor mount 13 is blown into the waveguide 11 through the hole, passes through the reflector 11 through the reflector 12, and is blown to the furnace wall 6. On the other hand, the transmission wave emitted from the ultrasonic transmission / reception sensor 1 is reflected by the reflecting mirror 12 and then propagates through the waveguide 11 to reach the furnace wall 6, and a reflected wave is generated at the furnace wall 6. When there is no significant damage such as a broken hole in the furnace wall portion where the transmitted wave reaches, a part or most of the reflected wave propagates in the waveguide 11 and is received by the ultrasonic sensor 1 via the reflecting mirror 12. The When the furnace wall portion is damaged, the transmitted wave is diffusely reflected, and a large reflected wave does not return to the inside of the waveguide 11. Therefore, the reflected wave is not detected or detected by the ultrasonic transmission / reception sensor 1. .

  The transmission wave emitted from the ultrasonic transmission / reception sensor 1 uses a burst wave composed of ultrasonic waves having a predetermined frequency for a plurality of wave numbers. The predetermined frequency may be about several tens of kHz, but may be determined as appropriate depending on the length of the waveguide 11 and the magnitude of damage to be detected.

  FIG. 4 is a schematic diagram showing a processing flow in the distance meter 2 as a distance measuring unit and the signal processing device 3 as a signal processing unit of the damage detection apparatus according to the present embodiment. As described with reference to FIGS. 1 and 2, in the present embodiment, since there are a plurality of distance meters 2 for one signal processing device 3, the processing performed by the distance meter 2 and the processing performed by the signal processing device 3 are appropriately performed. Although it is necessary to divide the processing, the description of the separation of processing will be given later with reference to FIG.

A process after the ultrasonic wave reflected by the furnace wall 6 as described above is received by the ultrasonic transmission / reception sensor 1 to obtain a reception signal will be described with reference to FIG.
(S101) As in the so-called normal AM detection, the envelope of the burst waveform of the received signal is detected as the received signal amplitude for the received signal (absolute value detection).
(S102) Since the ultrasonic transmission / reception sensor 1 is used for both transmission and reception of ultrasonic waves, since the reception signal may include a transmission signal for emitting a transmission wave (ultrasonic wave), a time region including only the reception signal is used. A reception time region is set in advance, and the maximum value (maximum amplitude value) Ap of the received signal amplitude and the maximum value detection time point (maximum value detection time point) Tp are detected within the reception time region.
(S103) If the maximum amplitude value Ap detected in the above (S102) is larger than the preset threshold value Ath (or more than the threshold value), the difference from the transmission time point Ts with the maximum value detection time point Tp as the reception time point ( The distance value L from the ultrasonic sensor to the furnace wall is calculated as L = V (Tp−Ts) / 2 from Tp−Ts) and the sound velocity V. If the maximum amplitude Ap is less than or equal to the set threshold value Ath (or smaller than the threshold value), it is determined that the maximum value detection time is invalid, and a predetermined missing value is set as a distance value.
(S104) When the extruder 5 moves from the inlet of the coke oven to the back (or in the opposite direction), the position is determined in advance with reference to the position information of the ultrasonic transmission / reception sensor 1 in the scanning direction (extrusion direction). The scanning position Pm, the distance value L, and the maximum amplitude value Vp are recorded for each measurement interval ΔP, with a predetermined scanning distance, for example, 10 mm as the measurement interval ΔP.
(S105) If the missing number of times Nd at which the distance value becomes the missing value continuously becomes the missing value continuously for a preset number of times (1 or more), it is determined as a damaged part. Then, a point connecting the start coordinate and the end coordinate in the scanning direction (furnace depth direction) of the damaged part is obtained as the depth position of the damaged part furnace, and the installation position of the ultrasonic transmission / reception wave sensor 1 that detects the damage is obtained. The height position is obtained from (height).
(S106) The depth position and height position of the damaged part are displayed on the screen of the display device 4 constituted by a liquid crystal screen or other known display elements.

  FIG. 5 shows a more detailed diagram of the configuration of the distance meter 2 and the signal processing device 3 described with reference to FIG. A transmission voltage signal generated as a burst wave of several waves at a predetermined frequency by the oscillating unit 21 is amplified by the transmission amplifying unit 22 and drives the ultrasonic transmission / reception sensor 1 to generate a transmission wave (ultrasonic wave). The reflected wave reflected by the furnace wall 6 shown in FIG. 1 is received by the ultrasonic transmission / reception sensor 1, converted into a reception voltage signal, amplified by the reception amplification unit 23, and then received by the amplitude detection unit 24. Is detected (absolute value detection).

  Since the time waveform of the received voltage signal output from the ultrasonic transmission / reception sensor 1 includes the time waveform of the transmitted voltage signal due to the circuit configuration, the time domain setting unit 26 sets the time domain including only the received wave to the maximum amplitude detecting unit. Set to 25. The set time region is set by a worker with a manual switch provided in the distance meter 2 or by remote operation using an external signal transmission cable such as an RS232C cable from the control unit 35 of the signal processing device 3. The distance meter 2 may be set. The maximum amplitude detection unit 25 detects the maximum amplitude value (maximum amplitude value) Ap in the time domain set by the time domain setting unit 26 and the maximum value detection time point (maximum value detection time point) Tp, and the distance calculation unit. 27. In order to detect the received voltage signal in the time domain, for example, the signal may be cut out in time by a switching element in an analog circuit configuration, or may be cut out from the received voltage signal versus time data by digital signal processing.

  In the threshold value setting unit 28, the operator inputs and sets a threshold value Ath that the maximum amplitude value Ap detected by the maximum amplitude detection unit 25 should satisfy, and inputs and sets the threshold value Ath in the distance calculation unit 27. The set threshold value Ath can be set by a manual switch inside the distance meter 2 or can be set in the distance meter 2 by remote operation from the outside, that is, from the control unit 35 of the signal processing device 3 through an RS232C cable or the like. In the distance calculation unit 27, when the maximum amplitude value Ap is larger than the set threshold value Ath (or more than the threshold value), the maximum value detection time point Tp is set as the reception time point using the information of the transmission time point Ts input from the oscillation unit 21. The difference from the transmission time Ts is calculated, the distance is calculated from the sound velocity V, and the distance value L is output to the signal processing device 3. If the maximum amplitude value Ap is less than or equal to the set threshold value Ath (or smaller than the threshold value), it is determined that the maximum value detection time Tp is invalid, and a predetermined missing value is output to the signal processing device 3 as the distance value L. Regardless of whether the distance value is valid or invalid, the maximum amplitude value Ap is output to the signal processing device 3 together with the distance value L.

  In the signal processing device 3, damage is detected by determining the presence or absence of damage based on the control of the distance meter 2 and the distance value and maximum amplitude value output from the distance meter 2. The control unit 35 sets the time domain of the received wave to be detected and the threshold Ath of the maximum amplitude value Ap in the time domain setting unit 26 and the threshold setting unit 28 of the distance meter 2, respectively. The position detector 34 determines the position of the ultrasonic sensor 1 in the scanning direction (furnace depth direction = extrusion direction) based on the two-phase voltage pulse output from the encoder (PLG) 52 attached to the extrusion beam 51 of FIG. To detect. In the distance recording unit 31, a predetermined scanning distance is set as a measurement interval ΔL, and a scanning position and a distance value output from the distance meter 2 and a maximum amplitude value are stored in the signal processing device 3 for each measurement interval. Record in memory or hard disk (not shown). The continuous missing measurement number setting unit 33 sets a lower limit of the continuous missing number for determining a damaged portion if the distance value output from the distance meter 2 continuously becomes a missing value. If the distance value becomes the missing value continuously for the number of times specified by the number of consecutive missing measurements, the broken hole discriminating unit 32 judges that the damage has occurred. In the display device 4, when the scanning position coordinates of the sensor and the distance value are always displayed in a graph, the operator can grasp the position currently measured. Further, the point connecting the start coordinate and the end coordinate of the damage scanning direction is set as the position of the damaged portion in the depth direction of the furnace, and the height position is also displayed.

  The distance meter 2 may be configured by an analog electronic circuit. However, the signal processing after the amplitude detector 24 is performed by software using a digital signal processor or a personal computer after A / D conversion of the signal. Each signal processing may be executed. In addition, it is preferable that the signal processing apparatus performs each signal processing by software using a personal computer in order to realize high-level signal processing. As input / output means, a keyboard, a mouse, and a LAN board may be provided.

  In the above description, a method and apparatus for evaluating the presence or absence of damage to the furnace wall 6 based on the magnitude of the amplitude obtained by transmitting / receiving burst wave ultrasonic waves and detecting the absolute value of the received voltage signal will be specifically described. did. Instead, the received voltage signal may be heterodyne detected and the presence or absence of damage to the furnace wall 6 may be determined from the magnitude of the phase change of the received voltage signal.

<Second Embodiment>
FIG. 6 shows a schematic diagram of a measurement flow of the wall damage detection method of the present embodiment. In other words, the method for detecting damage to the furnace wall is:
(S201) While the cooling gas is allowed to flow toward the furnace wall 6 inside the waveguide 11 bent into an L shape, the waveguide 11 is disposed so that the radiation from the furnace wall 6 does not directly strike the waveguide 11. An ultrasonic burst wave is transmitted from the ultrasonic transmission / reception sensor 1 toward the wall,
(S202) The ultrasonic wave reflected from the furnace wall 6 is received by the ultrasonic transmission / reception sensor 1, and a reception voltage signal is output.
(S203) absolute value detection or heterodyne detection of the received voltage signal to detect the received voltage signal due to the reflected wave from the furnace wall;
(S204) In (S203) above, from the received voltage signal due to the reflected wave from the furnace wall, the distance from the ultrasonic sensor to the wall is recorded as missing if it is not detected.
(S205) The number of consecutive missing measurements is determined by detecting the presence or absence of damage compared to a preset threshold value.
(S206) Display the depth direction and height position of the detected damaged portion of the furnace on the display device;
Consists of procedures.

  Embodiments of the present invention will be specifically described with reference to the drawings. FIG. 7 is a diagram showing a configuration of an apparatus of an example of the wall damage detection apparatus according to the embodiment of the present invention. As the ultrasonic transmission / reception sensor 1, a commercially available aerial ultrasonic sensor having a resonance frequency of 40 kHz and an outer diameter of 16 mm used for an on-vehicle obstacle detection device was used. The distance from the ultrasonic transmission / reception sensor 1 to the wall 6 'was set to about 500 mm. If the inner diameter of the waveguide 11 is reduced, the receiving sensitivity is lowered, and if it is increased, it becomes difficult to detect a broken hole smaller than the inner diameter of the tube, and the blowing capacity of the blower 16 is also increased. The inner diameter of the waveguide 11 was about 30 mm. Commercially available general-purpose devices were used for the pulse generator 21, the transmission amplifier 22, and the reception amplifier 23. Further, a measurement circuit 29 for a transmission / reception ultrasonic sensor is inserted between the transmission amplifier 22 and the reception amplifier 23 and the ultrasonic transmission / reception sensor 1. The received time waveform of the received voltage signal is amplified by the receiving amplifier 23, and once taken by the digital oscilloscope 20, it is taken into the personal computer 30 by USB communication. In the personal computer 30, the processing from amplitude detection to display in FIG. 4 is executed by software processing from the amplitude detection circuit 24 in the distance meter 2 to the signal processing device 3 and the display device 4 in FIG. 5.

  The pulse generator 21 generates a burst wave having a frequency of 40 kHz, 5 waves, 10 Hz repetition, and a voltage of 2 Vpp. The gain of the transmission amplifier 22 is multiplied by 10 and a voltage burst wave of 20 Vpp is applied to the ultrasonic sensor 1 having a withstand voltage of 100 Vpp. The gain of the receiving amplifier 23 was set to 25 times. The digital oscilloscope has 2500 sampling points, and the sampling interval is 4 μsec.

  First, the waveguide 11 was directed to the normal part 6b of the furnace wall 6 and it was confirmed that the reflected wave from the furnace wall 6 could be received while blowing air at 800 ° C. FIG. 8 shows both the received waveform at 800 ° C. and the amplitude detected by amplitude detection (envelope of burst wave).

  Amplitude detection was performed by software processing using a personal computer. The method is shown below.

First, it is assumed that the captured signal F (t) is locally expressed by the following equation (1).

  Assuming that the amplitude A (t) and the phase φ (t) are constant in the local time region near the time τ, the method 1 for detecting only the amplitude A (τ) and the amplitude A (τ) and the phase φ (τ) are There is a method 2 for detecting both.

In Method 1, when the signal F (t) is square-averaged over one period T in the vicinity of the time τ, the amplitude A (τ) can be calculated as in the following equation (2).

In method 2, the signal F (t) is multiplied by cos2πft and sin2πft (3), averaged over one period T as shown in equation (4), and A (t) and φ (t) are calculated.

  Although amplitude can be detected by any method, amplitude detection was performed by Method 1 here.

  It was found that the reflected wave from the normal part 6b of the furnace wall 6 can be sufficiently detected even at a high temperature if the ultrasonic wave is blown to the propagation path and the high temperature layer is removed.

  FIG. 9 shows the result of scanning the ultrasonic sensor 1 on the furnace wall 6 and recording the maximum amplitude value. As shown in FIG. 8, the reception waveform detection time region has a start time of 2.5 μsec and a length of 5 μsec. The maximum amplitude value gradually decreases in the vicinity of the broken hole portion. The result of calculating the distance at the threshold value of 0.1 V is shown in FIG. Below the threshold, the calculated distance value was regarded as a missing value. In the case of the missing side value, since the distance is not plotted, the hole portion can be clearly seen. In addition, the number of times of continuous missing measurement corresponding to the inner diameter of 30 mm of the waveguide 11 divided by the scanning measurement interval is set as the number of consecutive missing measurements, and it was automatically recognized as a broken hole portion.

  Although the embodiment has been described with the configuration shown in FIG. 7, when one ultrasonic sensor is scanned, the broken hole portion can be detected with sufficient accuracy even with this configuration. When there are a plurality of ultrasonic sensors, it is only necessary to prepare a circuit constituting a distance meter and input only a distance value and a maximum amplitude value to a personal computer which is a signal processing device.

  Furthermore, the heat resistance of the damage detection apparatus of the above example was separately evaluated. The blower tube 15 and the waveguide 11 were fixed and installed in a furnace close to 1000 ° C., and air was supplied to the inside by the blower 16 to perform ultrasonic transmission / reception experiments and heat resistance evaluation. The measurement for 2 minutes per cycle was repeated a plurality of times. However, ultrasonic transmission / reception was sufficiently possible, and there was no significant thermal deterioration in the transmission / reception unit that would cause a measurement problem.

  The present invention can be applied as a technique for detecting wall damage.

It is the figure which looked at the outline of the structure of the damage detection apparatus of this invention, and the said apparatus from the hearth surface vertical upper direction of the coke oven carbonization chamber. It is the figure which looked at arrangement | positioning of the waveguide of the damage detection apparatus of this invention from the direction perpendicular | vertical to a furnace wall. It is the figure which looked at arrangement | positioning with respect to a furnace wall from the furnace floor surface vertical upper direction about components, such as a waveguide and an ultrasonic transmission / reception sensor in the damage detection apparatus of this invention. It is the figure which showed the flow of the detection process after reception of the distance meter and signal processing apparatus in the damage detection apparatus of this invention. It is a figure which shows the internal block structure of the distance meter and signal processing apparatus of the damage detection apparatus of this invention. It is the figure which showed the detection procedure of the damage detection method of this invention. It is the figure which showed the structure of the experimental apparatus in the Example of this invention. The reception waveform (reception voltage signal) detected in the Example of this invention and its amplitude waveform are shown. It is a figure which shows the relationship between the scanning position of a transmission / reception sensor and the detected maximum amplitude value in the Example of this invention. It is a figure which shows the relationship between the scanning position of an ultrasonic transmission / reception sensor and the detected distance in the Example of this invention.

Explanation of symbols

1: Ultrasonic transmission / reception sensor 2: Distance meter 3: Signal processing device 4: Display device 5: Extruder 6: Furnace wall 6 ': Wall 11: Waveguide 11a: Ultrasonic outlet 12: Reflector 13: Sensor mount 14: Signal line 15: Air duct 51: Pushed beam 52: Encoder

Claims (5)

The ultrasonic transmission / reception sensor emits ultrasonic waves toward the wall in a high-temperature atmosphere, and the ultrasonic transmission / reception sensor scans along the wall while receiving the reflected wave by the ultrasonic transmission / reception sensor. An ultrasonic damage detection device for detecting,
An L-shaped waveguide having an open end facing the wall and including the ultrasonic transmission / reception sensor at the other end, and propagating ultrasonic waves generated by the ultrasonic transmission / reception sensor while flowing a cooling gas therein; ,
A blower pipe connected to the other end of the waveguide to supply a cooling gas to the ultrasonic transmission / reception sensor and the waveguide;
The ultrasonic transmission / reception sensor is driven to generate an ultrasonic burst wave. Based on the amplitude and reception time of the reception signal output from the ultrasonic transmission / reception sensor, the presence / absence of a reflected wave from the wall is detected and reflected. Distance measuring means for outputting a distance from the ultrasonic transmission / reception sensor to a reflection point on the wall surface when a wave is detected, and a predetermined missing value as a distance value when no reflected wave is detected;
Scanning position detecting means for scanning the ultrasonic transmission / reception sensor along the wall surface and detecting the scanning position;
Based on the scanning position detected by the scanning position detecting means and the distance value measured by the distance measuring means, the presence / absence of damage to the wall is determined by the number of consecutive missing measurements in which the missing values are continuously detected. Signal processing means for
A wall damage detection apparatus comprising: display means for displaying a wall damage position determined by the signal processing means. The distance measuring means includes
An amplitude detector for detecting the amplitude of the ultrasonic reception signal;
A maximum amplitude detector that detects a maximum value of the amplitude of the received signal within a preset time region and a reception time of a reflected wave that is a time when the maximum value is given;
The distance from the ultrasonic transmission / reception sensor to the wall calculated based on the reception time and transmission time of the ultrasonic wave when the maximum value of the amplitude satisfies a preset threshold, and the missing value when not satisfying the distance A distance calculation unit that outputs a value;
The wall damage detection device according to claim 1, comprising: The signal processing device includes:
Based on the scanning position of the wall surface of the ultrasonic transmission / reception sensor and the distance value output from the scanning distance measuring means, the damage of the wall is determined based on the number of consecutive missing measurements in which the missing value of the distance is set in advance. The wall damage detection device according to claim 1, further comprising a damage determination unit that determines and detects the portion.   4. The L-shaped waveguide including the ultrasonic transmission / reception sensor is arranged in parallel in a direction orthogonal to the scanning direction. 5. Wall damage detection device. The ultrasonic transmission / reception sensor emits ultrasonic waves toward the wall in a high-temperature atmosphere, and the ultrasonic transmission / reception sensor scans along the wall while receiving the reflected wave by the ultrasonic transmission / reception sensor. An ultrasonic damage detection method for detecting,
The opening end is opposed to the wall, and the other end is provided with the ultrasonic transmission / reception sensor. A step of propagating the ultrasonic burst wave generated by the acoustic wave transmission / reception sensor;
A step of detecting an amplitude of a reception ultrasonic wave, which is an ultrasonic wave reflected by a wall, and outputting a reception signal by the ultrasonic transmission / reception sensor;
Detecting a maximum value of the amplitude of the received ultrasonic wave within a preset reception time region, and a time of the maximum value as a reception time;
When the maximum value of the amplitude satisfies a preset threshold value, the distance from the transmission / reception sensor to the wall is calculated based on the reception time and transmission time of the ultrasonic wave to obtain a distance value. Outputting as a value;
Recording the distance value while scanning the ultrasonic sensor along a wall;
A wall damage detection method comprising: a step of discriminating and detecting, as a damaged portion, a wall portion in which the number of consecutive missing values of the distance value satisfies a preset number of consecutive missing measurements.

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