JP2005010139A - Residual thickness measuring method and device for furnace refractory using elastic wave - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a residual thickness measuring method and a residual thickness measuring device using an elastic wave, capable of measuring accurately the thickness of a refractory used for the furnace wall of a blast furnace or the like without opening the shell largely, and a service life prediction method of furnace and a repair method of furnace by using the residual furnace measuring method of the refractory. <P>SOLUTION: In the method of measuring the thickness of refractory by a reflection method using elastic wave relative to the furnace having the furnace wall constituted of the shell and the refractory, this residual thickness measuring method of the furnace refractory is used as follows: dispatch and reception of the elastic wave are performed at two different refractory body surface positions; the elastic wave is dispatched to the inside of the refractory body; while preventing a noise generated by propagating the elastic wave on the refractory body surface and receiving it, a reflected wave from the furnace inside surface of the refractory of the elastic wave is received; and thereby the thickness of the refractory is measured. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for measuring the thickness of a furnace refractory, and more particularly to a method and apparatus for measuring the remaining thickness of a refractory such as a refractory used in a blast furnace or other furnace during operation.

  A furnace wall of an industrial furnace such as a blast furnace generally has a multilayer structure in the order of an iron skin, a stamp material that is an irregular refractory, and a refractory brick that is a main refractory from the outside. Since the innermost refractory bricks are worn away from the core side, measuring the thickness of the refractory is extremely important for maintaining the furnace. The bottom of the blast furnace, in particular, is a part that cannot be directly repaired for several decades when the blast furnace is operated because it is constantly exposed to the hot metal even when there is no wind. By accurately measuring the remaining thickness of the refractory during operation, it is possible to optimize the operation of the blast furnace to prolong the life of the blast furnace and to appropriately predict the life of the blast furnace and the time for repair.

  The most widespread method for measuring the thickness of the refractory as described above is a method in which a thermometer is installed in the refractory and the heat flux transmitted from the core side to the core side is measured. In this method, thermometers are installed at more than 100 locations around the furnace wall, the heat flux is measured, and the thickness of the refractory is estimated by solving the heat conduction equation based on the result.

  However, in the method of solving the heat conduction equation by measuring the heat flow rate, it is necessary to use the thermal conductivity of refractory bricks, stamp materials, etc. when solving the heat conduction equation. In actual operation, a solidified layer and an embrittled layer are formed on the back side of the refractory brick from the core side, and the thermal conductivity of the refractory brick when these are attached is unknown, so an accurate thickness can be estimated. There is a problem that you can not.

  As methods other than the above, the following methods (a) to (d) are known in which the thickness of a refractory is measured using elastic waves (ultrasonic waves).

(A) Shock elastic wave method which is a non-destructive measurement method. This is a method for measuring the thickness of a refractory by measuring the reciprocation time of an elastic wave that propagates through the iron skin, stamp material, and refractory bricks by vibrating the iron skin with a hammer or hammering device to generate elastic waves. . (For example, see Patent Document 1.)
(B) Shock elastic wave resonance method. This is a method of measuring thickness by using a low frequency and obtaining a resonance frequency. The thickness of the refractory brick can be calculated from the resonance frequency of the elastic wave inside the furnace wall by examining the thickness and sound velocity value of the iron skin and stamp material in advance (see, for example, Patent Document 2).

  (C) A method in which the iron skin is opened and flaw detection is performed with ultrasonic waves (one probe method). In this method, first, the iron skin and the stamp material (or a part of the stamp material) are opened, and the opening hole is filled with the filler. Next, with the filler fully cured, the thickness of the refractory brick is measured from above the filler by a single probe method. By performing the opening, noise due to the iron skin and the stamp material can be reduced (see, for example, Patent Document 3).

(D) A method in which the iron skin is opened and flaw detection is performed with ultrasonic waves (two-probe method). (2) Transmitter and receiver are measured by the two-probe method using separate probes, and (c) prevent leakage of transmitted waves directly into the probe caused by the single-probe method. (For example, refer to Patent Document 4). There is one opening.
Japanese Patent Laid-Open No. 62-297710 JP-A-8-219751 JP-A-8-110217 Japanese Patent Laid-Open No. 9-61144

  However, the techniques (a) to (d) described above have the following problems.

  (A) The impact elastic wave method, which is a non-destructive measurement method, is difficult to measure because the signal-to-noise ratio (S / N) is low due to multiple reflections by the stamp material and the iron skin.

  (B) In the shock elastic wave resonance method, the press-fit condition when the stamp material is press-fitted between the iron shell and the refractory brick is slightly different depending on the location even in the furnace wall of the same blast furnace. Since the state of the stamp material changes with time, it is very difficult to know the accurate sound velocity value of the stamp material. Therefore, the accuracy of thickness measurement by the shock elastic wave method is low.

  (C) In the method of opening an iron skin and flaw-detecting with ultrasonic waves (one probe method), in the one probe method, the same probe is used for transmission and reception. However, there is a problem that a dead zone occurs due to the strong noise that leaks. FIG. 14 shows an example of a dead zone generated by the single probe method. When there is a dead zone Y, when the thickness of the refractory brick is thin, the reflected wave Z from the back side of the refractory brick is buried in the dead zone Y, making measurement impossible. In the case of FIG. 14, it can be seen that measurement becomes difficult when the fire brick becomes thin and the time taken to receive the reflected wave is 300 μsec or less.

  In addition, since the refractory brick strongly scatters ultrasonic waves, there is a problem that measurement cannot be performed with a high S / N due to noise caused by scattered waves. Furthermore, since the filler is made of a material having a heat insulating effect, the cooling capacity of the opening portion is lowered and a load is imposed on the refractory.

  (D) In the case of the two-probe method, the method of opening the iron skin and flaw-detecting with ultrasonic waves, as shown in FIG. Although it is a small range compared with the one probe method, the dead zone Y is also generated.

  In order to suppress the influence of surface waves, a moving stage and a linear guide are attached to the receiving probe, and a plurality of signals are measured while moving the measuring position of the receiving probe little by little. / N can be improved, but in order to measure while moving the probe in the opened hole, it is necessary to open the hole so that the hole has a sufficient size. This is not preferable. In addition, if the opening is large, the refractory is not sufficiently cooled, which places a burden on the refractory.

  As described above, in the conventional technique, it is difficult to measure so that the S / N is sufficiently high unless the iron skin is opened. However, even when the iron skin is opened, when measurement is attempted by the single probe method, the S / N is lowered due to the scattered wave and the dead zone, and high-precision measurement is difficult. In addition, when the two-probe method is used, the S / N is reduced due to the dead zone caused by the surface wave, so that not only high-precision measurement is difficult, but also the strength of the furnace wall increases because the opening hole becomes large. And the cooling capacity of the refractory decreases.

  Accordingly, an object of the present invention is to solve such problems of the prior art and accurately measure the thickness of a refractory used on a furnace wall of a blast furnace or the like without greatly opening the iron skin. An object of the present invention is to provide a refractory remaining thickness measuring method and a remaining thickness measuring apparatus using elastic waves. Another object of the present invention is to provide a method for predicting the life of a furnace and a method for repairing the furnace using a method for measuring the remaining thickness of a refractory.

The features of the present invention for solving such problems are as follows.
(1) In a furnace having a furnace wall composed of an iron skin and a refractory, the thickness of the refractory is measured by a reflection method using an elastic wave, and transmission and reception of an elastic wave Is performed at two different refractory surface positions, and an elastic wave is transmitted to the inside of the refractory, and noise generated when the elastic wave is received through the refractory surface is prevented, while the elastic wave A method for measuring a remaining thickness of a furnace refractory, comprising: measuring a thickness of the refractory by receiving a reflected wave from a furnace inner surface of the refractory.
(2) In a furnace having a furnace wall composed of an iron skin and a refractory, the thickness of the refractory is measured by a reflection method using an elastic wave, and formed on the iron skin A reflected wave from the furnace inner surface of the refractory obtained by transmitting an elastic wave from one of the at least two openings into the refractory is received at at least one other opening. Then, the thickness of the said refractory is measured, The residual thickness measuring method of the furnace refractory characterized by the above-mentioned.
(3) In a furnace having a furnace wall composed of an iron skin and a refractory, the thickness of the refractory is measured by a reflection method using an elastic wave, and two openings are formed in the iron skin. Forming a portion, exposing the surface of the refractory through the opening, and transmitting the elastic wave from one opening to the inside of the refractory, the reflected wave from the furnace inner surface of the refractory, the other The thickness of the said refractory is measured by receiving in the opening part of the furnace, The remaining thickness measurement method of the furnace refractory characterized by the above-mentioned.
(4) The method for measuring the remaining thickness of a furnace refractory according to (3), wherein an installation interval between the two openings is set according to a predicted remaining thickness of the refractory.
(5) The installation interval between the two openings is 2Ltanθ or less, which is twice the product of the tangent value of the effective directivity angle θ of the elastic wave and the predicted remaining thickness L of the refractory. The method for measuring the remaining thickness of the furnace refractory according to (3) or (4).
(6) The thickness measurement of the furnace refractory according to any one of (2) to (5), wherein the thickness of the refractory is repeatedly measured using the same opening formed in the iron skin. Method.
(7) It is possible to open and close by installing a removable cap on the opening part of the iron skin, removing the cap when measuring the remaining thickness, and closing the opening with the cap after measuring the remaining thickness. The method for measuring a remaining thickness of a furnace refractory according to any one of (2) to (6), which is characterized in that
(8) The transmission and reception of elastic waves are performed using a probe, and the distance between the probes is adjusted so as to be adjustable with a connecting member that does not easily propagate the elastic waves. 7) The method for measuring the remaining thickness of the furnace refractory according to any one of the above.
(9) When performing transmission and reception of elastic waves using a probe and bringing the probe into contact with the surface of the refractory, a heat insulating material is provided on the contact surface of the probe with the refractory. The method for measuring a remaining thickness of a furnace refractory according to any one of (1) to (8), wherein the method is provided.
(10) An apparatus for measuring the thickness of the refractory by a reflection method using an elastic wave in a furnace having a furnace wall composed of an iron skin and a refractory, and adjusting the distance between them A furnace refractory comprising a pair of possible probe holding arms A1 and A2, and a transmitting probe and a receiving probe held at the tips of the A1 and A2, respectively. Remaining thickness measuring device.
(11) Using the method for measuring the remaining thickness of a furnace refractory according to any one of (1) to (9), the thickness of the refractory on the furnace wall is measured for a predetermined period, and the measured refractory is measured. A furnace life prediction method, wherein the life of the furnace is predicted by estimating the life of the refractory from the thickness of the furnace.

  ADVANTAGE OF THE INVENTION According to this invention, the remaining thickness of the refractory material used with the furnace which has an iron skin can be measured with high precision during operation. Moreover, it is not necessary to perform complicated work for each measurement, and the remaining thickness can be repeatedly measured without placing a burden on the refractory. In addition, the life of the furnace can be predicted with high accuracy and repaired at an appropriate time.

  The present invention is a method of measuring the thickness of the refractory by a reflection method using an elastic wave in a furnace having a furnace wall composed of an iron shell and a refractory. Is performed at two different refractory surface positions, and an elastic wave is transmitted to the inside of the refractory, and noise generated when the elastic wave is received through the refractory surface is prevented, while the elastic wave The thickness of the refractory is measured by receiving a reflected wave from the furnace inner surface of the refractory. While transmitting an elastic wave to the inside of the refractory and preventing noise generated when the elastic wave is transmitted through the surface of the refractory, a reflected wave of the elastic wave from the furnace inner surface is generated. In order to receive, for example, from the furnace inner surface of the refractory obtained by transmitting an elastic wave from one of the at least two openings formed in the iron shell into the refractory. A method of receiving the reflected wave of at least one other opening can be used. More specifically, the first opening and the second opening that reach a surface of the refractory by removing a part of the iron skin are formed as two different openings, and the refractory is formed through these openings. A reflected wave from the furnace inner surface of the refractory obtained by exposing the surface of the object and transmitting an elastic wave directly from the first opening to the inside of the refractory is received at the second opening. Thus, a method for measuring the remaining thickness of the furnace refractory is used, wherein the thickness of the refractory is measured. Examples of the furnace having a furnace wall composed of an iron shell and a refractory include industrial furnaces such as a blast furnace, a gasification melting furnace, and an RH furnace.

  The present invention will be described in detail using a blast furnace.

  The furnace wall of the blast furnace has a multilayer structure composed of an iron skin, a stamp material, and a refractory brick in this order from the outside. The refractory for measuring the remaining thickness in the present invention is a portion of the refractory brick that is always exposed to the hot metal and wears out. The stamp material is an irregular refractory material that is press-fitted between the iron skin and the refractory brick. However, since the stamp material does not cause wear, the refractory material that needs to be measured is the refractory brick portion.

  FIG. 1 shows a schematic diagram of an embodiment of the present invention. In the present invention, a part of the iron skin 1 on the surface of the blast furnace is removed, the stamp material 2 under the removed iron skin is removed, and two openings 3 reaching the outer surface of the refractory are formed. And the probe 4 for transmission is installed in the 1st opening part 3a, and the elastic wave 6 is transmitted directly from the surface of the refractory brick (refractory material) 5 of the 1st opening part 3a to the inside of the refractory brick 5. The receiving probe 7 installed in the second opening 3b different from the first opening 3a used for transmission is used to transmit the reflected wave from the back side of the refractory brick 5 (the inner surface of the blast furnace). Receive. The received signal is analyzed to measure the thickness of the refractory brick (remaining thickness).

  By removing the iron skin and the stamp material under the iron skin to form the opening, it is possible to eliminate the influence of the iron skin and the stamp layer when the elastic wave is transmitted and received. In addition, by using the two-probe method in which two probes are installed, it is possible to improve the S / N by removing the dead band that is generated when the transmission wave leaks directly into the probe. Also, by forming two openings separately, the opening for transmitting the elastic wave and the opening for receiving are spatially separated, and the iron between the two openings By giving the skin and stamp layer the effect of a damper, it is possible to suppress the influence on the measurement by the surface wave propagating directly between the probes. Moreover, since it is a two-probe method, the influence by a scattered wave can be prevented.

  The opening 3 can be formed, for example, as a cylindrical hole having a bottom surface made of refractory brick and a side surface made of a stamp material and an iron skin by removing the iron skin and the stamp material by boring. Since the opening operation is easy, the opening is preferably a cylindrical hole. The area of the opening on the refractory and the iron shell is preferably small so as not to affect the operation of the blast furnace, but there is a problem that the noise level increases. When a probe having a diameter of 20 mm is used, the diameter of the opening can be about 20 mm. On the other hand, as described below, since the preferred installation interval between the transmitting probe and the receiving probe changes depending on the remaining thickness of the refractory to be measured, the opening can be formed with a certain margin. desirable. In any case, highly accurate measurement is possible by forming the opening as a circle having a diameter of 60 mm or less on the refractory and the iron skin, which is smaller than the case where the opening is used for the conventional remaining thickness measurement.

  The interval between the two openings and the installation interval between the two probes are preferably set according to the predicted remaining thickness. FIG. 2 shows a schematic diagram of changes in the intensity of noise (N) and signal (S) received by the receiving probe when the opening interval is changed. If the distance between the openings is too short, it is not possible to obtain a sufficient effect as a damper by the iron skin and the stamp material for suppressing the surface wave directly propagating between the probes. As shown in FIG. 2, when the distance between the openings is short, the strength increases, and as the distance increases, the strength decreases. Therefore, it is preferable that the space | interval of an opening part has a certain fixed value or more. On the other hand, regarding the signal intensity (S) of the elastic wave, the signal intensity changes differently when the remaining thickness of the refractory to be measured is thin and thick. When the remaining thickness is small, the signal intensity (S1) is sharply attenuated as the distance between the openings is increased because the overlapping of the visual field of the probe is small. However, when the remaining thickness is thick, the field of view of the probe is sufficiently overlapped as compared with the case where the remaining thickness is thin, so that the attenuation of the signal (S2) is gentle even if the interval between the openings is widened. The spacing between the openings is preferably determined so that the attenuation ratio of the signal strength (S) is 0.5 to 1. Therefore, if the remaining thickness of the refractory is expected to be thin, It is necessary to set a narrow interval between the openings. Therefore, when measuring the remaining thickness, the optimum opening interval can be determined according to the predicted remaining thickness range.

The interval between the openings can be set as follows. First, using the probe diameter and the transmission frequency, the effective directivity angle θ of the elastic wave is calculated by the equations (1) and (2). φ: diameter of probe, λ: wavelength of elastic wave, f: frequency of elastic wave, v: speed of sound in refractory,
λ = v / f (1)
θ = 29λ / φ (2)
From the effective directivity angle θ, it is possible to obtain a visual field range W in which an elastic wave signal can be transmitted and received with little attenuation (with an attenuation ratio of 0.5 to 1). The field-of-view range W of the probe with respect to the reflective surface range of the elastic wave from the effective directivity angle θ with respect to the remaining brick thickness L to be measured is obtained by equation (3) (see FIG. 3).

W = Ltanθ (3)
Therefore, in the two-probe method, it is necessary to arrange the two probes so that the visual field range W obtained from this effective directivity angle overlaps.

  FIG. 4 shows the relationship between the visual field ranges of the two probes when the probe installation interval D is changed. FIG. 4A shows a state in which D = W and the visual field ranges W of the two probes are completely overlapped. Therefore, the case of D ≦ W is most preferable as the distance between the two probes. The limit at which the opening interval can be separated is when the probe is arranged so that D = 2W as shown in FIG. 4B, and D ≦ 2W is a preferable interval between the two probes.

  On the other hand, when the probe is arranged so that D> 2W as shown in FIG. 4C, the visual field ranges W do not overlap, so that the signal intensity of the elastic wave that can be received is very weak and is not suitable for the remaining thickness measurement. is there.

Therefore, as shown in FIG. 5, assuming that the remaining brick thickness to be measured is L _{1 to} L ₀ (L ₁ <L ₀ ), it is effective if a preferable opening interval is set with respect to L ₁ which is the lower limit value. Since the visual field ranges obtained from the directivity angles always overlap, the remaining thickness can be measured at L _{1 to} L ₀ . FIG. 5A shows a case where D = W, and a sufficient signal strength can be obtained even when the remaining brick thickness is L ₁ . FIG. 5B shows a case where the probe installation interval D is set to 2 W, and if the probe installation interval is further increased, it is not suitable for the remaining thickness measurement.

  In the actual operation of the blast furnace, the range in which the thickness of the refractory brick is considered necessary to be measured is 200 to 2000 mm as the length of the refractory. Therefore, the distance between the openings for measuring this range is as described above, assuming that the probe has a diameter (φ) of 20 mm, the transmission frequency is 100 kHz, and the sound velocity in the refractory (refractory brick: BC-8SR) is 3141 m / sec. From the formulas (1) and (2), the effective directivity angle is θ = 45.5, and the field of view W of the probe when measuring a thickness of 200 mm or more from the formula (3) is W = 203.84 mm. Is obtained. Therefore, the distance between the probes is preferably D ≦ 2W = 407.68 mm, and particularly preferably D ≦ W = 203.84 mm. However, if an opening is provided at a position where the distance between the probes is less than 100 mm, noise increases. Therefore, the distance between the probes is preferably 100 to 410 mm, particularly preferably 100 to 200 mm. Set the interval between parts accordingly.

  It is clear from the above formulas (1) and (2) that the effective directivity angle θ also depends on the speed of sound in the refractory. When various types of refractory materials (BC-5: manufactured by Nihon Electrode, K-2RS: manufactured by TYK, BC-8SR: manufactured by Nihon Electrode, all carbonaceous blocks) for which the velocity of sound was measured were changed under the same conditions Table 1 shows preferable inter-probe distances and particularly preferable inter-probe distances.

  When the diameter (φ) of the probe is 40 mm, if the transmission frequency is 100 kHz and the speed of sound in the refractory is 3141 m / sec, the distance between the probes is preferably D ≦ 2W, as described above. = 167.92 mm, particularly preferably D ≦ W = 83.96 mm, and a preferable opening interval is 50 mm to about 170 mm, particularly preferably 50 to 84 mm. Further, Table 2 shows preferable inter-probe distances and particularly preferable inter-probe distances when various kinds of refractories whose sound speeds are measured are changed under the same conditions.

  It is desirable to repeatedly measure the thickness of the refractory using the same opening formed in the iron skin. The opening work can be reduced and the remaining thickness of the furnace refractory can be managed at the same location.

  It is desirable that the opening obtained by cutting the iron shell is repeatedly used for measuring the remaining thickness of the refractory. With a structure that allows the opening to be closed with a cap or lid so that water does not leak, the stamp material can be pressed again after the thickness measurement to close the opening, and the opening can be easily reopened. Thickness measurement can be performed. By facilitating the formation of the opening, it becomes easy to measure the thickness repeatedly over a long period of time, managing the tendency of the remaining thickness at the same location, and calibrating other remaining thickness measuring methods (for example, operation Inside, the remaining brick thickness is estimated by a method such as a thermometer installed on the furnace wall or a shock elastic wave resonance method that does not open the iron skin, and the operation is based on the data measured by the method of the present invention when the wind is off. It can be used as a method for increasing the measurement accuracy of the remaining thickness to be measured. Moreover, since the cooling capacity is not impaired, it is possible to prevent a burden on the refractory due to a decrease in the cooling capacity.

  An embodiment in which a cap is attached to the opening will be described with reference to FIG. First, the iron skin 1 and the stamp material 2 are hollowed out to form a cylindrical opening 3 having a diameter of 60 mm. Next, a short tube 10 made of SUS304 having an inner diameter of 87.3 mm, an outer diameter of 114.3 mm, and a length of 60 mm is attached around the opening 3 of the iron skin 1. The position of the short pipe 10 is determined so that the center of the opening 3 on the refractory brick and the center of the short pipe 10 are in the same straight line parallel to the normal direction of the iron skin surface. It is fixed by welding from the inside and outside of the iron skin 1. The cap 11 for closing the opening 3 has an outer diameter of 140 mm and a length of 60 mm. The cap 11 is removed from the short tube 10 by threading the inner side and threading the outer side of the short tube 10. Mounting is possible, and the opening can be closed.

  It is preferable to connect the two probes, ie, the transmission probe and the reception probe, using a fixing member made of a material that does not easily propagate an elastic wave, and integrate them for use in measuring the remaining thickness of the refractory. It is desirable that the distance between the probes can be arbitrarily adjusted.

  FIG. 7 shows an embodiment in which two probes are fixed with an arm for measurement. Since the two probes 4 and 7 are integrated by the arm 15, the operation of bringing the probes 4 and 7 into contact with the surface of the refractory 5 is facilitated. By using a material that does not easily propagate the elastic wave for the arm 15, it is possible to prevent the acoustic wave (transmission wave) from propagating through the fixing member to generate noise and deteriorate the S / N. For example, wood is particularly suitable as a material that does not easily propagate elastic waves. By making it possible to adjust the length of the arm using the fixing screw 16 or the like, the distance between the probes can be arbitrarily set.

  It is preferable to install a heat insulating material on the contact surface of the probe with the refractory.

  The surface of the refractory is usually about 80 ° C., but when the refractory becomes worn and thin, the surface temperature also increases. Since the heat-resistant temperature of the probe is about 100 ° C, it can be affected even when the temperature of the refractory becomes high by attaching a heat insulating material to the contact surface side of the probe with the refractory. The remaining thickness can be measured without any problem.

  FIG. 8 shows an example in which a heat-resistant plate is attached to the contact surface of the probe with the refractory. The heat insulating plate 17 is, for example, a circular plate having a diameter of 48 mm, which is the same as the tip portion of the probe, and a plate made of acrylic resin or polyimide resin having a thickness of 10 mm. In addition, FIG. 9 shows a comparison between the temperature of the surface of the refractory and the temperature of the surface of the probe when a 20 mm thick plate made of acrylic resin or polyimide resin is used as a heat insulating material. The effect of the board is shown. According to FIG. 9, even when the temperature of the contact surface with the refractory probe is around 300 ° C., the surface of the probe when using a heat insulating material rises only to about 50 ° C. .

  Next, an embodiment of a specific process for measuring the remaining thickness of the refractory in the blast furnace will be described with reference to FIGS.

  FIG. 10 is an explanatory diagram for carrying out the method for measuring the remaining thickness of a refractory according to the present invention. The measurement process consists of the following (a) to (d).

  (A) Before forming the opening, the remaining thickness of the refractory to be measured beforehand is estimated to some extent empirically or using a simple method other than the present invention. Determine the spacing of the openings. Next, the iron skin 1 and the stamp material 2 are opened, and the probes 4 and 7 are brought into contact with the surface of the refractory 5. Since the surface of the iron skin 1, the stamp material 2, and the refractory 5 is slightly inclined, a hole is formed in the normal direction to the inclination so that the probe is easily brought into contact with each other, and the opening 3 is formed. Expose the refractory surface. By making the opening angle in the normal direction with respect to the surface of the refractory, the measurement work is facilitated. Furthermore, it is desirable to perform a construction for welding the short pipe 10 or the like so that a cap can be attached to the opening 3 so that the structure can be closed.

  (B) The interval between the two probes 4 and 7 fixed by a jig made of a material that hardly propagates the elastic wave is adjusted according to the interval between the openings. A 10 mm thick insulating plate made of resin is attached to the contact surface of the probe with the refractory.

  (C) A transmission waveform is created by the pulser 20 and the transmission wave is transmitted to the inside of the refractory 5 by the transmission probe 4. The waveform may be an arbitrary waveform such as a burst wave or a chirp wave. The reflected wave from the back side of the refractory 5 is measured by the receiving probe 7. The reflected wave received by the receiving probe 7 is A / D converted by an A / D converter (digital oscilloscope) 23 through an amplifier 21 and a band pass filter 22 and displayed. Waveform information changed in discrete values by the digital oscilloscope 23 is taken into a computer (personal computer) 24 via a GPIB interface and analyzed to calculate the remaining thickness. FIG. 11 shows a waveform example of a reflected wave from the back side (furnace inner surface) of the refractory measured by the receiving probe 7. The reception signal Z of the reflected wave from the back surface of the refractory can be received with a sufficiently good S / N. Since the propagation time t is read from the received signal Z of the reflected wave and the sound velocity value in the refractory is known, the thickness of the refractory can be calculated. Further, a more accurate remaining thickness value is calculated by performing correction in consideration of the propagation path of the elastic wave in the two-probe method. It is preferable to create a database of sound velocity values in various refractories.

  (D) After the thickness measurement of the refractory is completed, the opening 3 is closed. After removing the probe from the surface of the refractory, the stamp material is again pressed into the opening 3. After press-fitting the stamp material, a cap is attached to the portion of the short tube 10 in the opening, and a blocking process is performed so that water does not leak into the opening 3. If you do not perform a process to attach the cap, press the stamp material into the opening and close it by welding the iron plate, etc., but it takes a lot of time to measure again and frequently measure the remaining thickness. It becomes difficult.

  When measuring the remaining thickness of the refractory again at the same position, remove the cap, remove the stamp material pressed into the opening to expose the surface of the refractory (refractory brick), then (b) to (d) Step 2) is executed again. If the opening is formed, one measurement can be completed in a short time of about 30 minutes. If the already opened opening cannot be used because the remaining thickness of the refractory is reduced, it is necessary to form a new opening. FIG. 12 shows a flowchart of one embodiment of the work for measuring the remaining thickness of the refractory at the bottom of the blast furnace corresponding to such a case. If the remaining thickness can be measured simply by changing the probe size (area of the refractory contact area) to minimize the opening formation work, change the probe size to a smaller one. It is preferable to measure it. The probe is preferable because the S / N is higher as the area of the transmission (reception) part that comes in contact with the refractory is higher, but the formation of the opening is also in terms of reducing the cost in terms of blast furnace operation. The smaller the number, the better. It is preferable to change the probe size if it can be dealt with only by changing the size of the probe.

  Next, the apparatus for measuring the remaining thickness of a refractory according to the present invention will be described.

  In order to perform the above method, in the present invention, in a furnace having a furnace wall composed of an iron shell and a refractory, an apparatus for measuring the thickness of the refractory by a reflection method using an elastic wave. A pair of probe holding arms A1 and A2 whose distances can be adjusted from each other, and a transmitting probe and a receiving probe respectively held at the tips of these A1 and A2 It is preferable to use a refractory residual thickness measuring device characterized by the following. As such an apparatus, for example, the apparatus shown in FIG. 7 can be used. By using the refractory residual thickness measuring device of the present invention, it becomes possible to bring two probes into contact with the refractory with uniform and sufficient force, and perform stable measurement even when there is only one worker. Can do.

  In addition, since the refractory may become hot, it is preferable that a heat insulating plate is attached to the contact surface of the transmission probe and the reception probe with the refractory.

  Next, the case where it opens to three or more places and the remaining thickness of a refractory is measured is demonstrated.

  When two openings are formed in the iron skin and measurement is performed using the two-probe method, a plurality of reflected waves as shown in FIG. 16 may be received, which makes it difficult to measure the remaining thickness. There is a case. In such a case, it is considered that cracks exist in the refractory. FIG. 17 shows a reflection path of the elastic wave when a crack exists. As shown in FIG. 17, the reflected wave from the crack 25 portion is received by the probe 7 before the reflected wave from the furnace inner surface of the refractory 5 corresponding to the remaining thickness of the refractory. A wave may be generated from a joint portion or the like, and it is difficult to distinguish a reflected wave corresponding to the remaining thickness of the refractory from a plurality of reflected waves. In such a case, it is possible to measure the remaining thickness of the refractory by the following method by providing three or more openings in the iron skin.

  18 and 19 are schematic views in the case where the remaining thickness is measured with three or more openings. It is desirable that the openings do not open on the same straight line. Two openings are selected and the remaining thickness between the openings is measured using the probe 26. The example of the received wave at the time of measuring between each opening part is shown on the right side of FIG. When there is no crack in the refractory, a waveform as shown in FIG. 18 is measured by the receiving probe, and when a crack 25 is present in the refractory, a waveform as shown in FIG. 19 is received. Measured with a probe. Since two peaks may occur when a crack exists, it is possible to identify the presence of the crack, and by referring to the time until the reflected wave of the portion where the crack does not exist is received, The reflected wave corresponding to the remaining thickness among the reflected waves can be identified, and the remaining thickness can be measured accurately.

  If the furnace inner surface of the refractory is flat, that is, if the remaining thickness of the refractory is almost uniform near the measurement point, the reflected wave is received almost simultaneously by each receiving probe. If non-uniformity occurs, a time difference occurs at each measurement point in receiving the reflected wave, and if this is used, the shape of the refractory inside surface of the furnace can be measured. In order to measure the shape of the furnace inner surface of the refractory, it is preferable that the number of openings is large. However, since it is not desirable for the operation of the furnace to provide a large number of openings in the iron skin, the number of openings is the minimum necessary. To do.

  When measuring the remaining thickness with three or more openings, after attempting to measure the remaining thickness between all existing openings, a new opening is formed, and the newly formed opening is already formed. It is efficient to measure the remaining thickness between the openings. That is, it is desirable to form a new opening in the iron skin after measuring the remaining thickness between the existing openings, and measure the remaining thickness between the newly formed opening and the existing opening. .

  FIG. 20 is a flowchart of an embodiment of a refractory residual thickness measurement operation at the bottom of a blast furnace when three or more openings are set. In FIG. 20, first, two methods are used using the method described above. The remaining thickness of the refractory is measured through the opening. Each opening has a No. It is identified by D (D = 1, 2, 3,...). The first two openings are designated as No. 1 and No. 1. No. 2 in the openings in the order of new openings. Let D be set. No. 1, No. 1 When there are two or more received reflected waves when measuring using the aperture of 2, the reflected wave with the maximum signal intensity is set as Sm1, and the reflected wave with the next highest intensity is set as Sm2. Compared with the intensity threshold value Sθ, if Sm2 ≦ Sθ (when Sm2> Sθ is No), the remaining thickness is obtained using Sm1 as a reflected wave. On the other hand, when Sm2> Sθ (when Sm2> Sθ is Yes), one of Sm1 and Sm2 may be a reflected wave caused by a crack, and either Sm1 or Sm2 is a reflected wave corresponding to the remaining thickness. Since it is unclear whether or not there is, a new opening (No. 3: D = 3) is set. At this time, the variable d = 0.

  When a new opening (No. 3: D = 3) is set, d = d + 1 is set. 3 (No. D) and No. 3 The remaining thickness of the refractory is measured between the openings of No. 1 (No. d) using the method of the present invention. If there is only one reflected wave, the remaining thickness is obtained using the reflected wave. However, if two or more reflected waves are received even when the new opening is used, the reflected wave with the maximum signal intensity is set as Sm1, and the reflected wave with the next highest intensity is set as Sm2. Compared with the threshold value Sθ, if Sm2 ≦ Sθ (when Sm2> Sθ is No), the remaining thickness is obtained with Sm1 as the reflected wave. On the other hand, when Sm2> Sθ (when Sm2> Sθ is Yes), it is unclear which of Sm1 and Sm2 is the reflected wave corresponding to the remaining thickness. 2 opening and No. 2 The remaining thickness of the refractory is measured between the three openings. At this time, it is determined whether or not a new opening needs to be formed by comparing the values of D and d + 1. That is, no. 1 and No. 3 is measured between the openings, D> 3 and d = 1, so that D> d + 1, and d = d + 1. d and opening No. No. D is measured. 2 and No. In the case of measuring between three openings, D = 3 and d = 2, so D = d + 1. In this case, d = 0 and a new opening (No. D: D = 4) is formed. Form.

  The remaining thickness is obtained by repeating the above process until one reflected wave is received or until Sm2 ≦ Sθ (when Sm2> Sθ is No). By using the above method, the remaining thickness of the refractory can be measured more accurately while minimizing the opening work of the iron skin.

  Next, a method for predicting the lifetime of the furnace using the present invention will be described.

  By using the refractory residual thickness measurement method described above, the accurate residual thickness of the refractory can be measured. Therefore, the thickness of the refractory on the furnace wall is measured for a predetermined period, and the measured refractory is measured. By estimating the life of the refractory from the thickness of the furnace, the life of the furnace can be predicted.

  In the case of a blast furnace, it is possible to estimate the age of the blast furnace during operation by obtaining the exact thickness (remaining thickness) of the blast furnace refractory using the above-described method of the present invention. The life of the blast furnace can be estimated well and easily. The thickness of the refractory at the bottom of the blast furnace is periodically measured using the method of the present invention, and the life is estimated from the remaining thickness history data using, for example, the least square method. Since the portion of the refractory that is heavily worn is empirically known, it is preferable to measure the remaining thickness of the refractory that is particularly worn. It is desirable to provide a plurality of measurement points on the bottom of the blast furnace and measure the remaining thickness. It is desirable to measure the thickness of the refractory from the start of operation, but if the refractory thickness data of the past few years can be accumulated, the life expectancy of the blast furnace can be predicted. During the operation of the blast furnace, since the cooling water is flowing on the surface of the iron skin, it is difficult to measure. Therefore, the thickness of the refractory is usually measured when the wind is off. Since the blast furnace wind is several times a year, it is preferable to measure the remaining thickness at each wind break. FIG. 13 shows an example of approximate calculation for predicting the life of a blast furnace.

  In FIG. 13, among the measurement data of the refractory brick thickness for the past 12 years, an approximate straight line is obtained by the least square method using the measured thickness for the past three years, and from this approximate straight line, the thickness of the refractory brick is determined as the lifetime. The number of years of operation F for the possible thickness X is calculated. If the current operating age of the blast furnace is P, the residual age Cr of the refractory can be obtained by the following equation (4).

Cr = FP (4)
When measuring the thickness of the refractory bricks at N locations, the refractory age of the refractory bricks is obtained as Cr ₁ , Cr ₂ , Cr ₃ ,... Cr _{N. As} shown in the following formula (5), The minimum value among the individual ages is defined as the blast furnace age Br.

Br = min [Cr ₁ , Cr ₂ , Cr ₃ ,... Cr _N ] (5)
Since the life of the furnace can be predicted using the above method, it is desirable to stop the furnace based on the predicted life and perform repair. That is, the remaining thickness of the refractory in the furnace is measured periodically, the life of the furnace is predicted based on the measured remaining thickness, the time for refurbishing the furnace is determined based on the predicted life, and the refurbishment of the furnace is performed. By implementing it, it is possible to refurbish the furnace at an appropriate time, prevent accidents that damage the refractory during operation, and operate the furnace to near the upper limit of its lifetime. The measurement of the remaining thickness of the refractory in the furnace may be performed a plurality of times at appropriate intervals over a certain long period, and it is not always necessary to perform the measurement at the same time interval.

1 is a schematic diagram of one embodiment of the present invention. Schematic of the intensity change of the noise (N) and signal (S) which a receiving probe receives when an opening part space | interval is changed. Schematic which shows the relationship between the effective directivity angle (theta) and the visual field range W of a probe. Schematic which shows the relationship of the visual field range of two probes at the time of changing the installation space | interval D of a probe. (A) D = W, (B) D = 2W, (C) D> 2W Schematic which shows the relationship of the visual field range of two probes at the time of changing the installation space | interval D of a probe. (A) D = W, (B) D = 2W Schematic of one embodiment of attaching a cap to the opening. Schematic of one Embodiment which fixes and fixes two probes with an arm. The schematic of one Embodiment which attaches a heat-resistant board. The graph which shows the effect of a heat insulating material. Explanatory drawing for implementing this invention. The graph which shows the example of a waveform of a reflected wave. The flowchart of one Embodiment of the remaining thickness measurement operation | work of the refractory of the bottom of a blast furnace. The graph which shows the example of the approximate calculation which performs the lifetime prediction of a blast furnace. The graph which shows the example of the dead zone which arises with one probe method. The graph which shows the example of the dead zone which arises with the two probe method. The figure which shows an example in case a some reflected wave is received. The figure which shows the reflective path | route of an elastic wave in case a crack exists. Schematic (when there is no crack) when opening to three or more places and measuring the remaining thickness. Schematic (when there is a crack) when opening to three or more places and measuring the remaining thickness. The flowchart of one Embodiment of the remaining thickness measurement operation | work in the case of setting three or more openings.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Iron skin 2 Stamp material 3 Opening part 3a 1st opening part 3b 2nd opening part 4 Probe for transmission 5 Refractory brick (refractory material)
6 Elastic Wave 7 Receiving Probe 10 Short Tube 11 Cap 15 Arm 16 Fixing Screw 17 Heat Resistant Plate 20 Pulsar 21 Amplifier 22 Band Pass Filter 23 A / D Converter (Digital Oscilloscope)
24 Computer (personal computer)
25 Crack 26 Probe A1 Probe holding arm A2 Probe holding arm Cr Refractory age F Lifetime of firebrick P Lifetime of blast furnace t Propagation time X Fireproof brick Life Thickness Y Dead Band Z Reflected Wave

Claims (13)

  In a furnace having a furnace wall composed of an iron shell and a refractory, a method for measuring the thickness of the refractory by a reflection method using elastic waves, wherein the transmission and reception of elastic waves are different from each other. Performing at the position of the surface of the refractory, transmitting an elastic wave to the inside of the refractory, and preventing noise generated when the elastic wave is received through the surface of the refractory, A method for measuring a residual thickness of a furnace refractory, wherein the thickness of the refractory is measured by receiving a reflected wave from a furnace inner surface.   A furnace having a furnace wall composed of an iron skin and a refractory, wherein the thickness of the refractory is measured by a reflection method using an elastic wave, wherein at least two or more formed on the iron skin By receiving a reflected wave from the furnace inner surface of the refractory obtained by transmitting an elastic wave from one of the openings to the inside of the refractory, at least in the other one of the openings, A method for measuring a remaining thickness of a furnace refractory, comprising measuring the thickness of the refractory.   In a furnace having a furnace wall composed of an iron shell and a refractory, a method of measuring the thickness of the refractory by a reflection method using elastic waves, after measuring the remaining thickness between existing openings The furnace refractory according to claim 2, wherein a new opening is formed in the iron skin, and a remaining thickness is measured between the newly formed opening and an existing opening. Remaining thickness measurement method.   In a furnace having a furnace wall composed of an iron skin and a refractory, the thickness of the refractory is measured by a reflection method using an elastic wave, and two openings are formed in the iron skin. Then, the surface of the refractory is exposed through the opening, and the reflected wave from the furnace inner surface of the refractory obtained by transmitting an elastic wave from one opening to the inside of the refractory is reflected in the other opening. A method for measuring a remaining thickness of a furnace refractory, wherein the thickness of the refractory is measured by receiving the thickness.   The method for measuring the remaining thickness of a furnace refractory according to claim 4, wherein an installation interval between the two openings is set according to the predicted remaining thickness of the refractory.   The installation interval between the two openings is 2Ltanθ or less, which is twice the product of the tangent value of the effective directivity angle θ of the elastic wave and the expected remaining thickness L of the refractory. The method for measuring a remaining thickness of the furnace refractory according to claim 4 or 5.   The method for measuring a remaining thickness of a furnace refractory according to any one of claims 2 to 6, wherein the thickness of the refractory is repeatedly measured using the same opening formed in the iron skin.   The cap can be opened and closed by installing a removable cap at the opening of the iron skin, the cap is removed when measuring the remaining thickness, and the opening is closed with the cap after measuring the remaining thickness. Item 8. A method for measuring a remaining thickness of a furnace refractory according to any one of Items 2 to 7.   9. The method according to claim 1, wherein transmission and reception of elastic waves are performed using a probe, and the distance between the probes is adjusted by a connecting member that does not easily propagate the elastic waves. A method for measuring the residual thickness of the furnace refractory as described in claim 1.   Transmitting and receiving elastic waves using a probe, and when contacting the probe to the surface of the refractory, installing a heat insulating material on the contact surface of the probe with the refractory The method for measuring a remaining thickness of a furnace refractory according to any one of claims 1 to 9.   An apparatus for measuring a thickness of the refractory by a reflection method using an elastic wave in a furnace having a furnace wall composed of an iron shell and a refractory, wherein a pair of the distances is adjustable. The furnace refractory residual thickness measuring apparatus, comprising: a probe holding arm A1, A2 and a transmitting probe and a receiving probe respectively held at the tips of the A1, A2. .   Using the method for measuring a remaining thickness of a furnace refractory according to any one of claims 1 to 10, the thickness of the refractory on the furnace wall is measured for a predetermined period, and the measured thickness of the refractory is used. A method for predicting the lifetime of a furnace, wherein the lifetime of the furnace is predicted by estimating the lifetime of the refractory.   A furnace refurbishment method, comprising: refurbishing the furnace by determining a refurbishment period of the furnace based on the life of the furnace predicted by using the furnace life prediction method according to claim 12.

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