JP5504482B2 - Ultrasonic wall thickness measuring device and ultrasonic wall thickness measuring method - Google Patents

Description

  The present invention relates to an ultrasonic wall thickness measuring apparatus and an ultrasonic wall thickness measuring method for measuring the wall thickness of a furnace bottom tube of a boiler by ultrasonic waves. In particular, the present invention relates to an ultrasonic wall thickness measuring apparatus and an ultrasonic wall thickness measuring method capable of easily measuring the wall thickness of the upper part of the furnace bottom tube.

2. Description of the Related Art Conventionally, a boiler that heats water supplied into a pipe by providing a plurality of pipes on a furnace bottom surface or a furnace wall surface is known. FIG. 1 shows an example of such a boiler. FIG. 1A is a perspective view of the boiler 1, and FIG. 1B is a partial cross-sectional view of the furnace bottom surface of the boiler 1.
A plurality of tubes 10 bent in a U-shape are arranged in parallel to constitute a bottom surface and a wall surface of the boiler 1. Here, the tube 10 constituting the bottom surface of the boiler 1 is called a furnace bottom tube 11. Water is circulated in the tube 10. The pipes 10 are connected to each other by welding or the like through the plate material 1a so that there is no gap. And combustion is performed in the boiler 1, the water in the pipe | tube 10 is heated, becomes a vapor | steam, and is used as a power source etc.

In a paper mill, a waste liquid called black liquor discharged from the manufacturing process is burned in the boiler 1, and the water in the tube 10 is vaporized by the heat, and the turbine is rotated by the vapor to generate electricity or dry the paper. I do. (Such boilers in paper mills are called soda recovery boilers.)
However, when the black liquor is burned, a residue called smelt accumulates on the upper side of the boiler bottom of the boiler (upper side of the furnace bottom tube). The smelt corrodes the furnace bottom tube 11 constituting the furnace bottom surface and reduces the thickness of the upper portion of the furnace bottom tube 11.
For this purpose, the thickness of the upper part of the furnace bottom tube 11 must be measured as appropriate. And if it is going to measure the thickness of the upper part of the furnace bottom pipe 11 by the ultrasonic wave from the inside of the boiler 1, the smelt laminated | stacked on the upper side of the furnace bottom pipe 11 must be removed. However, since the smelt hardens due to the heat of the boiler, it is difficult to remove the smelt laminated on the upper side of the furnace bottom tube 11 over the entire upper surface of the furnace bottom tube 11. Therefore, the thickness of the upper part of the furnace bottom tube 11 is measured by partially removing smelt. Thus, there is a problem that it is difficult to measure the thickness of the upper part of the furnace bottom tube 11.
In addition, the boiler for thermal power generation has a similar problem that the residue is stacked on the upper side of the bottom surface of the furnace.

In addition, the inventions of Patent Documents 1 to 3 are known regarding apparatuses and methods for measuring various properties of a tube by ultrasonic waves.
However, the invention described in Patent Document 1 is a device for flaw detection of a tube, and is not a device for measuring the wall thickness of the tube.
The invention described in Patent Document 2 is an apparatus for measuring the thickness of the furnace wall tube of the boiler, and is not an apparatus for measuring the thickness of the upper part of the furnace bottom tube.
The invention described in Patent Document 3 is a method for flaw detection of a corrosion crack in a furnace wall tube of a boiler, and is not a method for measuring the thickness of the upper portion of the furnace bottom tube.

JP 58-108451 A Japanese Patent Laid-Open No. 61-290357 Japanese Patent Laid-Open No. 4-6462

  The present invention has been made to solve the problems of the prior art, and an ultrasonic thickness measuring apparatus and an ultrasonic thickness measuring method capable of easily measuring the thickness of the upper portion of the furnace bottom tube. It is an issue to provide.

  In order to solve the above-mentioned problem, the present inventor has studied a method of measuring the thickness of the upper portion of the furnace bottom tube by transmitting ultrasonic waves from the bottom of the furnace bottom tube to the furnace bottom tube. As a result, the thickness of the top of the bottom tube is measured by transmitting ultrasonic waves from the bottom of the bottom tube while receiving water and filling it with water. I got the knowledge that I can.

  The present invention has been completed based on the knowledge of the present inventors. That is, in order to solve the above-mentioned problem, the present invention provides an ultrasonic wall thickness measuring apparatus that measures the wall thickness of a furnace bottom tube of a boiler by means of ultrasonic waves, and is provided below the furnace bottom tube. An ultrasonic probe that transmits toward the furnace bottom tube and receives echoes from the furnace bottom tube, and causes the ultrasonic probe to transmit ultrasonic waves and a contact medium filled in the furnace bottom tube The ultrasonic probe receives echoes from the inner and outer surfaces of the furnace bottom tube through the top of the furnace bottom tube, and acquires electrical signals corresponding to the echoes from the ultrasonic probe. Detecting the time difference of the propagation time of the echo from the inner and outer surfaces of the furnace bottom tube based on the electrical signal acquired by the control unit, and calculating the thickness of the upper part of the furnace bottom tube based on the time difference An ultrasonic wall thickness measuring device is provided, To.

  According to the present invention, since the thickness of the upper portion of the furnace bottom tube can be measured from below the furnace bottom tube, it is not necessary to remove the residue on the upper side of the furnace bottom tube. Can be easily measured.

  Preferably, the ultrasonic wall thickness measuring device includes a drive unit that moves the ultrasonic probe in the tube axis direction while swinging around the tube axis of the furnace bottom tube.

According to such a preferable method, the thickness of the upper portion of the furnace bottom tube within the range in which the ultrasonic probe swings can be easily measured along the tube axis direction of the furnace bottom tube.
In addition, since the ultrasonic probe swings around the tube axis of the furnace bottom tube, if the shape of the furnace bottom tube is almost a perfect circle, the ultrasonic probe and the furnace bottom tube are arranged in the circumferential direction of the furnace bottom tube. The distance from the top is almost constant. As a result, even when the thickness of the top of the furnace bottom tube is continuously measured in the circumferential direction of the furnace bottom tube, the electrical signal is acquired by the control unit and the thickness of the top of the furnace bottom tube is calculated by the calculation unit. Calculation becomes easy.

  Preferably, in order to calculate the thickness of the upper portion of the furnace bottom tube, a first ultrasonic probe in which the focus of the transmitted ultrasonic wave is set near the upper portion of the furnace bottom tube, and the furnace bottom tube A second ultrasonic probe in which the focal point of the transmitted ultrasonic wave is set in the vicinity of the lower part of the furnace bottom tube, and the control unit includes the first ultrasonic wave The ultrasonic probe transmits ultrasonic waves, and echoes from the inner and outer surfaces of the ultrasonic wave propagated to the upper part of the furnace bottom pipe through the contact medium filled in the furnace bottom pipe An acoustic probe receives the electrical signal corresponding to the echo from the first ultrasound probe, transmits the ultrasound to the second ultrasound probe, and lowers the bottom of the furnace bottom tube. Echoes from the inner and outer surfaces of the furnace bottom tube are received by the second ultrasonic probe, and electric waves corresponding to the echoes are received from the second ultrasonic probe. A signal is acquired, and the calculation unit calculates a time difference in reception of echoes from the inner and outer surfaces of the bottom tube at the top of the bottom tube based on the electrical signal from the top of the bottom tube obtained by the control unit. Detecting, calculating the thickness of the upper part of the furnace bottom pipe based on the time difference, and based on the electric signal from the lower part of the furnace bottom pipe acquired by the control unit, the furnace at the lower part of the furnace bottom pipe A time difference in receiving echoes from the inner and outer surfaces of the bottom tube is detected, and a thickness of the lower portion of the furnace bottom tube is calculated based on the time difference.

According to such a preferable method, the thickness of the upper part and the lower part of an arbitrary portion of the furnace bottom tube can be easily measured simultaneously.
In particular, when the ultrasonic probe is moved in the tube axis direction while swinging around the tube axis of the bottom tube, the upper and lower portions of the bottom tube within the range in which the ultrasonic probe swings. The wall thickness can be easily measured along the tube axis direction of the furnace bottom tube.

  In order to solve the above-mentioned problem, the present invention provides an ultrasonic wall thickness measuring method for measuring the wall thickness of a furnace bottom tube of a boiler by using an ultrasonic wave, and the first step of filling the furnace bottom tube with a contact medium. A second step of transmitting ultrasonic waves from an ultrasonic probe toward the furnace bottom tube from below the furnace bottom tube, and ultrasonic waves propagated to the upper part of the furnace bottom tube via the contact medium A third step of receiving echoes from the inner and outer surfaces of the bottom tube by the ultrasonic probe, and a time difference between echoes from the inner and outer surfaces of the bottom tube received by the ultrasonic probe, And a fourth step of calculating an upper wall thickness. An ultrasonic wall thickness measurement method is provided.

  Preferably, the second to fourth steps are performed while the ultrasonic probe is swung around the tube axis of the furnace bottom tube and moved in the tube axis direction.

  According to the present invention, since the thickness of the upper portion of the furnace bottom tube can be measured from below the furnace bottom tube, it is not necessary to remove the residue on the upper side of the furnace bottom tube. Can be easily measured.

Fig.1 (a) is a perspective view of a boiler, FIG.1 (b) is a partial cross section figure of the furnace bottom face of a boiler. FIG. 2 is a configuration diagram of the ultrasonic thickness measuring apparatus according to the first embodiment. FIGS. 3A to 3D show surface echoes and bottom surface echoes converted into electrical signals (echo signals) by the ultrasonic thickness measuring device in four furnace bottom tubes having different upper wall thicknesses. FIG. FIG. 4 is a correlation diagram between measured values and measured values of the thickness of the four furnace bottom tubes 11 shown in FIGS. 3 (a) to 3 (d). FIG. 5 is a configuration diagram of an ultrasonic thickness measuring apparatus according to the second embodiment. FIG. 6A is a schematic view of the first drive unit in the ultrasonic thickness measuring apparatus as viewed from the tube axis direction of the furnace bottom tube, and FIG. 6B is a perspective view of the ultrasonic probe. . FIG. 7 is a diagram for explaining the oscillation of the ultrasonic probe in the ultrasonic thickness measuring apparatus. FIG. 8 is a diagram for explaining the operation of the guide portion in the ultrasonic thickness measuring apparatus.

(First embodiment)
Hereinafter, an ultrasonic thickness measuring apparatus according to a first embodiment of the present invention will be described with reference to the accompanying drawings as appropriate. In the present embodiment, as an example, an ultrasonic thickness measuring device used in a soda recovery boiler is shown. FIG. 2 is a configuration diagram of the ultrasonic thickness measuring apparatus. The furnace bottom tube 11 is made of steel.
The ultrasonic thickness measurement apparatus 2 includes an ultrasonic probe 21 provided below the furnace bottom tube 11, a control unit 22 that transmits ultrasonic waves to the ultrasonic probe 21, and a thickness of the furnace bottom tube 11. And an arithmetic unit 23 for calculating
The ultrasonic probe 21 is provided so that the transmission direction of the ultrasonic wave is directed toward the tube axis of the furnace bottom tube 11, and is controlled by the control unit 22 to transmit the ultrasonic wave toward the furnace bottom tube 11 and at the bottom of the furnace. An echo from the tube 11 is received.

The furnace bottom tube 11 is filled with a contact medium for propagating ultrasonic waves. In this embodiment, water W is filled as an example.
The focal point of the ultrasonic wave is set in the vicinity of the upper part of the furnace bottom tube 11, and the ultrasonic wave transmitted from the ultrasonic probe 21 propagates the water W filled in the pipe and reaches the upper part of the furnace bottom tube. It reaches the upper surface of the furnace bottom tube 11 and is reflected by the upper surface 11a and the outer surface 11b. The echo W propagates through the water W filled in the furnace bottom tube and is received by the ultrasonic probe 21. The echo reflected by the upper inner surface 11a of the furnace bottom tube 11 is called a surface echo, and the echo reflected by the upper outer surface 11b of the furnace bottom tube 11 is called a bottom echo.
The ultrasonic probe 21 receives surface echoes and bottom surface echoes, converts them into electrical signals (echo signals) corresponding to the intensity of the respective echoes, and transmits them to the control unit 22.
The control unit 22 amplifies the electrical signal received from the ultrasonic probe 21, performs A / D conversion, and transmits the A / D converted signal.
The calculation unit 23 receives the surface echo and the bottom surface echo that have been A / D converted by the control unit 22, and based on the time difference in propagation time between the A / D converted surface echo and the bottom surface echo, The thickness of the upper part of the furnace bottom tube 11 is calculated from the propagation speed of. The calculation unit 23 outputs the calculated thickness by a display unit (not shown) such as a liquid crystal display or a printer.
At this time, water is supplied between the furnace bottom tube 11 and the ultrasonic probe 21 by a water supply device (not shown), and ultrasonic waves are provided between the furnace bottom tube 11 and the ultrasonic probe 21. To be propagated.

The thickness of the upper part of the furnace bottom tube is measured by ultrasonic as follows.
First, the user fills the furnace bottom tube 11 with water W as a contact medium (first step). At this time, when the boiler 1 in operation is stopped and the thickness of the upper part of the furnace bottom tube 11 is measured, the water W originally filled in the furnace bottom tube 11 for the operation of the boiler 1 is used. Can be used.
Subsequently, the user installs the ultrasonic probe 21 below the furnace bottom tube 11 toward the furnace bottom tube 11, and causes the ultrasonic probe 21 to transmit ultrasonic waves via the control unit 22 (first operation). 2 steps). At this time, the user supplies water between the furnace bottom tube 11 and the ultrasonic probe 21 by the water supply device so that the ultrasonic wave is propagated from the ultrasonic probe 21 to the furnace bottom tube 11. .
Subsequently, the ultrasonic wave propagated to the upper part of the furnace bottom tube 11 through the water W in the furnace bottom tube 11 is reflected on the inner and outer surfaces of the furnace bottom tube 11 and received as an echo by the ultrasonic probe 21. (Third step).
Subsequently, the control unit 22 and the calculation unit 23 calculate the thickness of the upper portion of the furnace bottom tube 11 based on the time difference of the echo propagation time from the inner and outer surfaces of the furnace bottom tube 11 received by the ultrasonic probe 21. (Fourth step). The calculated thickness is output by the control unit 22 to a display unit such as a liquid crystal display or a printer.

  In the above method, the method of calculating the wall thickness of the furnace bottom tube 11 by the control unit 22 and the calculation unit 23 has been described. However, the present invention is not limited to this. For example, the electrical signal received by the control unit 22 May be displayed on a display device, and the time difference between the propagation times of the surface echo and the bottom echo may be read manually from the waveform to calculate the thickness of the furnace bottom tube 11.

Next, the measurement result of the thickness of the upper part of the furnace bottom tube 11 having an outer diameter of 70φ and an initial thickness of 6 mm measured in this manner will be shown.
3 (a) to 3 (d) show the upper part of the furnace bottom tube 11 converted into an electric signal (echo signal) by the ultrasonic probe 21 in the four furnace bottom pipes 11 having different upper wall thicknesses. It is a figure which shows a surface echo and a bottom face echo. The horizontal axis indicates the propagation distance of the ultrasonic wave in the furnace bottom tube 11 and is converted from the propagation time. The vertical axis represents the intensity of the received echo as a percentage of a predetermined reference intensity. The maximum intensity of the surface echo and the bottom echo exceeds the reference intensity. A line segment G in the figure is a gate provided to remove noise and detect a surface echo and a bottom echo. Since the bottom echo has a smaller amplitude than the surface echo and is susceptible to noise, the gate height relative to the reference intensity is set higher for the bottom echo than for the surface echo. The set time of the gate is determined based on the propagation time of the oscillation echo (not shown), but the time between the gate start time of the surface echo and the gate start time of the bottom echo is the furnace bottom measured so far. It is adjusted by the thickness of the upper part of the tube 11 and the degree of thinning.
The computing unit 23 detects the rise of the waveform of the surface echo (shown by a broken line t1) and the rise of the waveform of the bottom echo (shown by a broken line t2) from the A / D converted surface echo and the bottom echo, Based on the difference in echo rise time, the thickness of the upper portion of the furnace bottom tube 11 is calculated from the propagation speed.
The right side of each figure shows the measured value obtained by the ultrasonic thickness measuring apparatus 2 and the actually measured value obtained by actually measuring the thickness.

FIG. 4 is a correlation diagram between measured values and measured values of the thickness of the four furnace bottom tubes 11 shown in FIGS. 3 (a) to 3 (d).
The four points are arranged in a straight line, and the measured value and the actually measured value show a strong correlation. The thickness of the upper part of the furnace bottom tube 11 can be accurately measured by the ultrasonic thickness measuring device 2.

  As described above, since the thickness of the upper portion of the furnace bottom tube 11 can be measured from the lower side of the furnace bottom tube 11, it is not necessary to remove the residue on the upper side of the furnace bottom tube 11. The wall thickness can be easily measured.

  Further, as the ultrasonic probe 21, the first ultrasonic probe in which the focal point of the ultrasonic wave is set in the vicinity of the upper portion of the furnace bottom tube 11 and the focal point of the ultrasonic wave are set in the vicinity of the lower portion of the furnace bottom tube 11. A thickness of the upper portion of the furnace bottom tube 11 is calculated by the first ultrasonic probe, the control unit 22 and the calculation unit 23, and the second ultrasonic probe The thickness of the lower portion of the furnace bottom tube 11 may be calculated by the control unit 22 and the calculation unit 23. The thickness of the upper part and the lower part of an arbitrary portion of the furnace bottom tube 11 can be easily measured simultaneously.

(Second Embodiment)
Next, an ultrasonic thickness measuring apparatus according to the second embodiment will be described with reference to the drawings. The description of the same configuration as that of the first embodiment is omitted. FIG. 5 is a configuration diagram of the ultrasonic thickness measuring apparatus 2.
The ultrasonic thickness measuring apparatus 2 according to the present embodiment is a tube that swings the ultrasonic probe 21 of the ultrasonic thickness measuring apparatus 2 according to the first embodiment around the tube axis of the furnace bottom tube 11. A drive unit 3 that moves in the axial direction is provided.
The drive unit 3 holds the ultrasonic probe 21 and swings around the tube axis of the furnace bottom tube 11, and moves the first drive unit 4 in the tube axis direction of the furnace bottom tube 11. The second driving unit 5 is provided, and the fixing unit 6 that fixes the second driving unit 5 to the lower surface of the furnace bottom tube 11 is provided. The fixing part 6 is a magnet, for example.

6A is a schematic view of the first drive unit 4 viewed from the tube axis direction of the furnace bottom tube 11, and FIG. 6B is a perspective view of the ultrasonic probe 21, and FIG. FIG. 8 is a diagram for explaining the swinging of the ultrasonic probe 21, and FIG. 8 is a diagram for explaining the operation of the guide portion constituting the first drive unit 4.
The first drive unit 4 has a through hole 40 through which the stage 51 of the second drive unit 5 passes. In addition, the first drive unit 4 includes two holding plates 41 provided so as to sandwich the ultrasonic probe 21 from both sides of the furnace bottom tube 11 in the tube axis direction with a gap. The holding plate 41 is provided with arc-shaped slits 41a with the concave side facing upward.
Three pins 210 that fit into the slits 41 a are provided on each surface of the ultrasonic probe 21 that faces the holding plate 41. Of the three pins 210, the central central pin 210 a is longer than the other two pins 210. The pin 210 can slide in the slit 41a. The ultrasonic probe 21 is held by the first drive unit 4 by fitting the pin 210 into the slit 41a and can swing around the tube axis of the furnace bottom tube 11 (see FIG. 7). .
The curvature of the slit 41 a is set so that the ultrasonic probe 21 swings around the tube axis of the furnace bottom tube 11 in a state where the ultrasonic wave transmitted from the ultrasonic probe 21 is directed to the furnace bottom tube 11. ing.

On both outer sides of the holding plate 41 in the tube axis direction of the furnace bottom tube 11, guide portions 42 for swinging the ultrasonic probe 21 are provided. The guide part 42 is provided with a slit 42a in the vertical direction (see FIG. 8).
Of the three pins 210 of the ultrasonic probe 21, the pins 210 at both ends are long enough to reach the slit 41 a of the first drive unit 4, but the central pin 210 a passes through the slit 41 a. The length reaches the slit 42a of the guide portion 42, and the tip is fitted in the slit 42a.
The guide portion 42 is penetrated by a horizontal shaft 43 which is perpendicular to the tube axis direction of the furnace bottom tube 11 and can slide along the shaft 43. The guide portion 42 is connected to the tip of a lever 45 that rotates about a rotation shaft 44 provided in parallel with the tube axis direction of the furnace bottom tube 11 by a connecting rod 46. The joint portion between the guide portion 42 and the connecting rod 46, and the connecting rod 46 and the lever 45 are rotatable.

The rotating shaft 44 is rotated by a motor under the control of the control unit 22. When the rotating shaft 44 rotates, the lever 45 and the connecting rod 46 bend and extend, and the guide portion 42 reciprocates along the shaft 43.
When the guide portion 42 reciprocates, the center pin 210a fitted in the slit 42a reciprocates along the shaft 43 while moving up and down along the slit 42a.
When the center pin 210 a reciprocates along the shaft 43, the ultrasonic probe 21 swings around the tube axis of the furnace bottom tube 11 while facing the furnace bottom tube 11.
In the present embodiment, the angle at which the ultrasonic probe 21 swings as viewed from the tube axis of the furnace bottom tube 11 is set to 100 °, but the thickness of the upper portion of the furnace bottom tube 11 is set in the width direction of the furnace bottom tube 11. Can be measured over almost the entire area.

As shown in FIG. 5, the second drive unit 5 extends in the tube axis direction of the furnace bottom tube 11 and holds the first drive unit 4, a drive wheel 52 provided on one end side of the stage 51, It has a pulley 53 provided on the other end side, and a drive wheel 52 and a wire 54 hung on the pulley 53.
The first drive unit 4 slides on the stage 51 through the stage 51 through the through hole 40. The first drive unit 4 is also fixed to the wire 54.
The drive wheel 52 is rotated by a motor under the control of the control unit 22. When the driving wheel 52 rotates, the ultrasonic probe 21 provided in the first driving unit 4 is pulled by the wire 54 and moves in the tube axis direction of the furnace bottom tube 11.
Note that the distance between the ultrasonic probe 21 and the furnace bottom tube 11 varies due to the fact that the shape of the furnace bottom tube 11 is not a perfect circle as the ultrasonic probe 21 swings and moves in the tube axis direction. Thus, the propagation time of the surface echo and the bottom echo varies. In order to detect the surface echo and the bottom echo even if the propagation times of the surface echo and the bottom echo vary, the control unit 22 follows the fluctuation when the propagation time of the surface echo fluctuates. The set times of the gates of the surface echo and the bottom echo after the reception timing of the echo are varied.
Further, each of the rotating shaft 44 and the driving wheel 52 may be manually rotated by a handle without using a motor. At this time, a handle for rotating the rotation shaft 44 is included in the first drive unit 4, and a handle for rotating the drive wheel 52 is included in the second drive unit 5.

The thickness of the upper part of the furnace bottom tube is measured by ultrasonic as follows.
First, the user fills the furnace bottom tube 11 with water W as a contact medium (first step). At this time, when the boiler 1 in operation is stopped and the thickness of the upper part of the furnace bottom tube 11 is measured, the water W originally filled in the furnace bottom tube 11 for the operation of the boiler 1 is used. Can be used.
Subsequently, the user swings the ultrasonic probe 21 by the first drive unit 4 via the control unit 22 and moves the ultrasonic probe 21 by the second drive unit 5 in the tube axis direction of the furnace bottom tube 11. The following second step to fourth step are repeated while moving to. At this time, the rotation of the rotating shaft 44 and the driving wheel 52 may be manually performed by a handle without using a motor.
The user transmits ultrasonic waves from the ultrasonic probe 21 via the control unit 22 (second step). At this time, the user supplies water between the furnace bottom tube 11 and the ultrasonic probe 21 by the water supply device so that the ultrasonic wave is propagated from the ultrasonic probe 21 to the furnace bottom tube 11. .
Subsequently, the ultrasonic wave propagated to the upper part of the furnace bottom tube 11 through the water W in the furnace bottom tube 11 is reflected on the inner and outer surfaces of the furnace bottom tube 11 and received as an echo by the ultrasonic probe 21. (Third step).
Subsequently, the control unit 22 and the calculation unit 23 calculate the thickness of the upper portion of the furnace bottom tube 11 based on the time difference of the echo propagation time from the inner and outer surfaces of the furnace bottom tube 11 received by the ultrasonic probe 21. (Fourth step). The calculated thickness is output by the control unit 22 to a display unit such as a liquid crystal display or a printer.

By configuring the ultrasonic thickness measuring device 2 as described above, the thickness of the upper portion of the furnace bottom tube 11 within the range in which the ultrasonic probe 21 swings is increased in the tube axis direction of the furnace bottom tube 11. Can be easily measured along.
Further, since the ultrasonic probe 21 swings around the tube axis of the furnace bottom tube 11, if the shape of the furnace bottom tube 11 is almost a perfect circle, the ultrasonic probe 21 in the circumferential direction of the furnace bottom tube 11. And the top of the furnace bottom tube 11 are substantially constant. Thus, even when the thickness of the upper portion of the furnace bottom tube 11 is continuously measured in the circumferential direction of the furnace bottom tube 11, the acquisition of the electrical signal by the control unit 22 and the calculation of the furnace bottom tube 11 by the calculation unit 23 are performed. The thickness of the upper part can be easily calculated.

  Also in the present embodiment, as in the first embodiment, as the ultrasonic probe 21, a first ultrasonic probe in which the focal point of the ultrasonic wave is set near the upper portion of the furnace bottom tube 11, A second ultrasonic probe whose focal point is set in the vicinity of the lower portion of the furnace bottom tube 11, and the first ultrasonic probe, the control unit 22, and the calculation unit 23, The thickness may be calculated, and the thickness of the lower part of the furnace bottom tube 11 may be calculated by the second ultrasonic probe, the control unit 22 and the calculation unit 23. The thickness of the upper and lower portions of the entire width of the furnace bottom tube 11 can be easily measured along the tube axis direction of the furnace bottom tube 11.

DESCRIPTION OF SYMBOLS 1 ... Boiler 11 ... Furnace bottom tube 2 ... Ultrasonic wall thickness measuring device 21 ... Ultrasonic probe 22 ... Control part 23 ... Calculation part 3 ... Drive part W ... Water (contact medium)

Claims (5)

An ultrasonic wall thickness measuring device for measuring the wall thickness of a boiler bottom tube by ultrasonic waves,
An ultrasonic probe that is provided below the furnace bottom tube and transmits ultrasonic waves toward the furnace bottom tube and receives echoes from the furnace bottom tube;
The ultrasonic probe transmits ultrasonic waves, and echoes from the inner and outer surfaces of the ultrasonic wave propagated to the upper part of the furnace bottom pipe through the contact medium filled in the furnace bottom pipe. A control unit that causes the acoustic probe to receive the electrical signal corresponding to the echo from the ultrasound probe;
A calculation unit that detects a time difference in propagation time of echoes from the inner and outer surfaces of the furnace bottom tube based on the electrical signal acquired by the control unit, and calculates a thickness of an upper portion of the furnace bottom tube based on the time difference; An ultrasonic wall thickness measuring device comprising:   2. The ultrasonic thickness measuring apparatus according to claim 1, further comprising a drive unit that moves the ultrasonic probe in a tube axis direction while swinging around the tube axis of the furnace bottom tube. In order to calculate the thickness of the upper portion of the furnace bottom tube, a first ultrasonic probe in which the focal point of the transmitted ultrasonic wave is set near the upper portion of the furnace bottom tube;
A second ultrasonic probe in which the focal point of the transmitted ultrasonic wave is set near the lower part of the furnace bottom tube to calculate the thickness of the lower part of the furnace bottom tube;
The control unit causes the first ultrasonic probe to transmit an ultrasonic wave and transmits the ultrasonic wave propagating to the upper portion of the furnace bottom tube through a contact medium filled in the furnace bottom tube. An echo from the outer surface is received by the first ultrasonic probe, and an electrical signal corresponding to the echo is obtained from the first ultrasonic probe;
The second ultrasonic probe is made to transmit ultrasonic waves, and the echo from the inner and outer surfaces of the bottom tube at the bottom of the bottom tube is received by the second ultrasonic probe, so that the second ultrasonic probe is received. Obtain an electrical signal corresponding to the echo from the tentacle,
The arithmetic unit detects a time difference of reception of echoes from the inside and outside surfaces of the bottom tube at the top of the bottom tube based on the electrical signal from the top of the bottom tube acquired by the control unit, and the time difference Calculate the thickness of the top of the furnace bottom tube based on
Based on the electrical signal from the lower part of the furnace bottom tube acquired by the control unit, a time difference of reception of echoes from the inner and outer surfaces of the furnace bottom pipe at the lower part of the furnace bottom tube is detected, and based on the time difference, the furnace The ultrasonic thickness measuring apparatus according to claim 1 or 2, wherein a thickness of a lower portion of the bottom tube is calculated. An ultrasonic wall thickness measuring method for measuring the wall thickness of a furnace bottom tube of a boiler by ultrasonic waves,
A first step of filling the furnace bottom tube with a contact medium;
A second step of transmitting ultrasonic waves from an ultrasonic probe toward the furnace bottom tube from below the furnace bottom tube;
A third step of receiving, by the ultrasonic probe, echoes from the inner and outer surfaces of the ultrasonic wave propagated to the upper part of the furnace bottom tube through the contact medium;
And a fourth step of calculating a thickness of an upper portion of the bottom tube based on a time difference of echoes from the inner and outer surfaces of the bottom tube received by the ultrasonic probe. Method.   5. The ultrasonic wave according to claim 4, wherein the second to fourth steps are performed while the ultrasonic probe is swung around the tube axis of the furnace bottom tube and moved in the tube axis direction. 6. Thickness measurement method.

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