JP2021011993A - Hot diagnostic method for refractories - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately grasp the residual dimension of a refractory lined in a furnace while reducing a heat load and avoiding restrictions on measurement frequency by arranging a measuring device outside the container. SOLUTION: A step of calculating a residual dimension A of a fireproof material based on a profile of a fireproof material measured by using a laser profile meter installed outside the container, and iron measured from the outside of the container at the same time as measuring the profile. It has a step of calculating the residual dimension B of the fireproof material based on the surface temperature of the skin, and if the profile can be measured, the residual dimension A is set as the residual dimension of the fireproof material, and both the profile and the surface temperature are If it is measurable, the difference between the remaining dimension A and the remaining dimension B is recorded as the correction value, and if the profile is not measurable and the surface temperature is measurable, the remaining dimension B is the latest correction value. A hot diagnostic method for fireproof materials, which calculates the residual dimensions of the fireproof material by correcting with. [Selection diagram] Fig. 2

Description

The present invention relates to a method for hot diagnosis of a refractory, and more particularly to a technique for diagnosing the residual size of a refractory lined inside a container at a high temperature.

In steel refining containers, the inner surface of the iron skin is lined with a refractory that can withstand high temperatures, but due to melting damage to the slag and cracking due to thermal shock, the remaining size of the refractory can be reduced by repeated use. It will decrease. If the operation is continued without noticing the abnormal wear of the refractory or the reduction of the remaining size, the refractory may disappear completely, the iron skin may be melted or punctured, and the molten metal or slag as the contents may leak out. Therefore, it is necessary to carry out repair and replacement work of refractories at an appropriate timing.

In particular, the vacuum degassing device used in steel refining is divided into an upper tank, a lower tank, and an immersion pipe, and among these, the refractory lined in the lower tank for recirculating molten steel causes particularly severe damage. However, since the vacuum degassing device is a closed container, there are few places where the refractory can be visually inspected under high temperature immediately after the treatment, and it can be said that the hot diagnosis of the refractory is particularly difficult.

In response to the above problems, the following methods have been proposed for diagnosing the residual dimensions and conditions of refractories. For example, Patent Document 1 and Patent Document 2 propose a method of measuring the residual size of a refractory in a refining container using a fixed profile meter, but a blind spot is generated due to the adhesion of bare metal or the like inside the container. There is a problem that measurement cannot be performed if this is done. In the case of equipment with a small opening such as a vacuum degassing device, blind spots are likely to occur due to the adhesion of the metal inside the tank, and the residual refractory dimensions should be measured stably only with the profile meter installed outside the container. It is difficult.

Patent Document 3 and Patent Document 4 propose a method of inspecting by inserting a camera or a laser profile meter from an immersion tube under a vacuum degassing facility. However, in this method, since the measuring device is inserted inside the lower tank in a high temperature atmosphere, there is a problem that the life of the measuring device is shortened due to the heat load. Further, since the laser profile meter is inserted into the tank by combining a number of driving devices, there is a problem that a large error occurs in the position of the laser profile meter itself and the accuracy of the measured data is low. Further, since it takes time to move the measuring device and the vacuum degassing tank itself, there is a problem that the inspection frequency is limited.

On the other hand, Patent Documents 5 and 6 propose a method of measuring the internal temperature of the refractory and the temperature of the iron skin and indirectly grasping the residual size of the refractory in the tank. However, this method has a problem that the temperature varies depending on the number of times the lower tank is used and the operating conditions such as the processing time and the processing interval, and the accuracy of the predicted residual size is low.

Japanese Unexamined Patent Publication No. 60-138407 JP-A-2007-291435 Japanese Unexamined Patent Publication No. 2006-299314 Japanese Unexamined Patent Publication No. 1-145514 JP-A-2010-281515 Japanese Unexamined Patent Publication No. 2013-147714

The present invention has been made in view of the above problems, and the residual dimensions of the refractory lined in the furnace are reduced while reducing the heat load and avoiding the limitation of the measurement frequency by arranging the measuring device outside the container. It is an object of the present invention to provide a hot diagnosis method for refractories that can accurately grasp the above.

The gist of the present invention is as follows.
(1) Using one or more laser profile meters installed outside the container in which the refractory is lined on the inner surface of the iron skin, the inside of the container is irradiated with a laser to measure the profile of the refractory. At the same time as the step of calculating the residual size A of the refractory based on the profile and the measurement of the profile, at least the surface temperature of the iron skin is measured from the outside of the container, and the refractory is based on the surface temperature. It has a step of calculating the residual dimension B, and when the profile is measurable, the residual dimension A is set as the residual dimension of the refractory, and both the profile and the surface temperature can be measured. In that case, the difference between the residual dimension A and the residual dimension B calculated based on each is recorded as a correction value, and if the profile is not measurable and the surface temperature is measurable. A method for hot diagnosis of a refractory, which comprises calculating the residual size of the refractory by correcting the residual dimension B using the latest correction value.

(2) The method for hot diagnosis of a refractory according to (1), wherein the step of calculating the residual dimension B measures the surface temperature of the refractory in addition to the surface temperature of the iron skin. ..

(3) The container is a vacuum degassing device used in steel refractory, and the laser profile meter is arranged above the outside of the furnace of the vacuum degassing device and is inside the vacuum degassing device from the opening at the top of the furnace. The method for hot diagnosis of a refractory according to (1) or (2), which comprises irradiating a laser toward

According to the present invention, by installing the profile meter outside the furnace, the heat load on the profile meter is reduced and the measurement accuracy is improved. Furthermore, by measuring the iron skin temperature at the same time as the profile measurement and recording the difference between the accurate residual size by the profile and the predicted residual size by the iron skin temperature as a correction value, the blind spot will be created due to the adhesion of bare metal. Even if the profile cannot be measured, the accurate residual size can be grasped by correcting the predicted residual size due to the iron skin temperature.

It is a figure which shows the structure of the lower tank refractory of RH equipment. It is a figure which shows the appearance of RH equipment and the installation example of a profile meter. It is a graph which shows the number of times of use of RH equipment, and the transition of the remaining size of a refractory of a lower tank. It is a graph which shows the example of the measurement of the residual size of the lower tank refractory in the prior art.

FIG. 1 is a diagram showing a wall structure (RH lower tank side wall) of a container to which the hot diagnostic method for refractories according to the embodiment of the present invention is applied. In the illustrated example, the container 1 has a wall structure in which the refractory 4 is lined on the inner surface of the iron skin 2 via the back heat insulating material 3, and the refractory 4 is inside the permanent refractory 4A on the iron skin side. Includes refractory 4B and clothing.

In the present embodiment, the residual size (residual size A) of the ware refractory is measured by using one or more laser profile meters installed outside the container 1. The laser profile meter measures the profile of refractory clothing and at least a portion of the profile of iron skin. If the positional relationship between the iron skin shape and the ware refractory is known from the design drawings and the like, the residual size of the ware refractory can be calculated from the above profile measurement results with reference to the iron skin profile. Here, the laser profile meter is installed at a position where it is possible to observe a portion where the refractory is heavily worn and the residual size needs to be measured. Even when it is difficult to fix and install the device in such a position due to the connection of the devices, the moving time is significantly shorter than that when the laser profile meter is inserted in the container, for example. Further, since the residual size value of the refractory wear measured by the laser profile meter is calculated based on the iron skin profile each time, it can be measured with good accuracy even when the laser profile meter is not fixedly installed.

On the other hand, in predicting the remaining dimensions by temperature measurement, the temperature of the iron skin or the back of the refractory is measured using a radiation thermometer, thermocouple, optical fiber, etc., and the temperature inside the tank and the physical properties of the refractory are used. The residual size of the ware refractory is calculated using Equation 1 representing the heat flux Q of the multilayer flat plate below.

Here, t ₁ is the temperature of the working surface of the ware refractory [K], t ₂ is the temperature of the working surface of the back and the permanent refractory of the ware [K], and t ₃ is the temperature of the working surface of the back and the back insulating material of the permanent refractory [K]. K], _{t 4} the back heat insulating material back and Tetsugawa temperature [K], _{t 5} is the atmospheric temperature [K], _{h a} is Tetsugawa - heat transfer coefficient [W / ^mK 2 between the atmosphere], lambda ₁ is Ware refractory thermal conductivity [W / mK], λ ₂ is permanent refractory thermal conductivity [W / mK], λ ₃ is back insulation material thermal conductivity [W / mK], l ₁ is ware refractory The thickness of the object [mm], l ₂ is the thickness of the permanent refractory [mm], and l ₃ is the thickness of the back refractory [mm].

For temperature measurement, for example, with reference to Patent Document 5 (Japanese Patent Laid-Open No. 2010-281515) and Patent Document 6 (Japanese Patent Laid-Open No. 2013-147714), in order to suppress temperature variation due to the influence of cooling or the like, after the treatment is completed. , The measurement is performed after a certain amount of time has passed. If there is a difference between the residual size of the refractory of the wear obtained by profile measurement and the residual size of the refractory of the wear calculated from the temperature measurement (predicted residual size), the difference between the two residual dimensions is recorded as a correction value. .. A correction value is recorded each time the profile is measured. For example, if profile measurement is difficult due to the influence of bullion adhesion, the predicted residual size is adjusted by adding or subtracting the correction value calculated at the time of the latest profile measurement to the predicted residual size. It is possible to improve the accuracy of.

The results of applying the present invention in a vacuum degassing facility (RH) will be described below. The lower tank 8 of the RH equipment according to the present embodiment shown in FIG. 2 has a wall structure composed of an iron skin 2, a heat insulating material 3, a permanent refractory 4A, and a ware refractory 4B as shown in FIG. In the RH equipment, refining treatment is carried out for 20 to 40 minutes per molten steel pan, and if it is 1 ch (charge), the refractory life of the lower tank 8 is about 400 ch on average.

In the RH equipment as described above, as shown in FIG. 2, a laser profile meter 11 is installed above the OB lance charging hole 5 of the canopy 6, and every 10 charges, 3 minutes after the processing is completed, the lower tank 8 is installed. The refractory profile was measured to determine the remaining dimensions. However, as shown in FIG. 2, when the bullion 10 adheres to the upper tank 7, the refractory of the lower tank 8 is located in the blind spot, and the profile cannot be measured.

On the other hand, as shown in FIG. 2, at the same time as the profile measurement, the iron skin temperature of the lower tank 8 and the operating surface temperature of the ware refractory were measured using the radiation thermometer 12 (AD5616 manufactured by A & D). Every minute was charged, that is, at the same timing as the profile measurement. Regarding the temperature measurement part, the part located at the height of the molten metal surface at the time of molten steel recirculation in the 3rd to 5th stages of the side wall refractory of the lower tank 8 has the smallest residual size of the refractory, so the iron skin temperature of the part. Was measured. Further, the operating surface temperature of the ware refractory was measured by using a radiation thermometer on the side wall refractory in the range visible from the immersion pipe 9, and substituted into Equation 1. If the refractory operating surface temperature cannot be measured, by unifying the measurement timing and applying the latest measurement result to the operating surface temperature, the refractory residue can be maintained while maintaining accuracy only by measuring the iron skin temperature. The dimensions can be calculated. Measured values for the thermal conductivity of each of the ware refractory, permanent refractory, and heat insulating material (wear refractory: 12 [W / mK] permanent refractory: 1.2 [M / mK] heat insulating material: 0.03 [W / mK] mK]) was substituted to make the thickness of the permanent refractory and the heat insulating material unchanged from the time of construction. For the atmospheric temperature, the measured value of the outside air temperature was substituted, and the remaining garment size was calculated using Equation 1. When the profile measurement was performed every 10 charges, the difference between the calculated predicted residual size result and the profile measurement result was recorded as a correction value.

FIG. 3 shows changes in the number of uses and the remaining size of the refractory. Let the profile measurement dimension be the residual dimension A and the predicted residual dimension from the temperature measurement be the residual dimension B. The remaining dimension was indexed with the initial value of the profile measurement dimension as 100. Both the remaining size A and the remaining size B show a situation in which the remaining size of the refractory decreases as the number of uses increases. By installing the laser profile meter 11 outside the furnace as described above, the measurement time can be shortened, and measurement can be performed at a significantly shorter interval than before without production loss. However, in the measurement of 90ch, 100ch, 190ch, 200ch, 310ch, 320ch, and 390ch, the measured value is an abnormal value due to the presence of the bullion 10 in the upper tank 7 and the blind spot as shown in FIG. (The value greatly deviated from the previous measurement value), and the profile could not be measured.

On the other hand, the residual dimension B calculated from the result of the temperature measurement can be calculated even when the profile measurement cannot be performed as described above, but the deviation is large as compared with the residual dimension A by the profile measurement. This is because the residual dimension B is calculated from the steady-state heat transfer calculation, but the physical property value of the refractory at the time of temperature measurement does not always match the measured value measured in advance, and the physical property value itself is used repeatedly. It is thought that this is because it changes each time it receives a heat load.

Therefore, in this embodiment, as described above, while the residual dimension A by profile measurement is used as the basic control value of the residual dimension of the lining refractory, both the residual dimension A by profile measurement and the residual dimension B by temperature measurement are used. Is obtained, the difference (residual size A-residual size B) is recorded as a correction value, and if the profile is not measurable and therefore the remaining size A cannot be obtained, the remaining size B is the latest. The correction value is used for correction, that is, (residual size B + latest correction value) is used as the control value for the residual size of the lining refractory. Specifically, in FIG. 3, for example, in 80ch, profile measurement was possible, and the correction value represented by the exponent was 11. In the next 90ch, profile measurement was not possible due to the adhesion of the bullion, but since the temperature measurement could be performed without any problem, (90ch residual size A) = (80ch residual size B) + (80ch correction value 11). ).

If profile measurements cannot be made continuously, the most recent, or previously obtained, correction value obtained last is still used. For example, in FIG. 3, the remaining size A could not be measured for 100ch following 90ch, but the temperature measurement could be performed without any problem, so (100ch remaining size A) = (90ch remaining size B) + (80ch). The correction value was 11). When profile measurement becomes possible by removing the metal adhering to the tank (for example, 110ch), the residual size A by profile measurement is used as the residual size of the lining refractory without making the above corrections. In addition to the control value, the difference between the residual dimension A and the residual dimension B by temperature measurement (residual dimension A-residual dimension B) is recorded as a new correction value.

As a comparative example, in the same RH equipment as in the example, the residual size of the refractory was measured by a method of inserting a profile meter from a dip tube, which is a conventional technique, and compared with the result according to the example. FIG. 4 shows changes in the number of uses and the residual size of the refractory in the comparative example. In the case of the comparative example, it takes time to move the profile meter directly under the tank in order to perform the measurement, but since the operation is interrupted during this period, the embodiment is required to secure the same production amount as the embodiment. Measurements can only be performed less frequently than (every 10 charges). Further, in the process of inserting and measuring the profile meter in the tank using many driving devices, the accuracy of grasping the position of the profile meter is lowered, and as a result, the accuracy of the measurement result is also lowered.

Table 1 shows the results of actually verifying the residual size accuracy for a plurality of lower tanks in the above examples and comparative examples. In each example, when the error between the hot measured value after the processing was completed and the measured value measured in the furnace after that was calculated, the error from the measured value was 25% or more in the comparative example (conventional technique). In contrast to about 40%, in the present invention, it was suppressed to 4% or less, and the accuracy was greatly improved.

By applying the present invention, it was possible to accurately grasp the residual size of the refractory in the tank and reduce the trouble of perforating the iron skin of the refractory in the lower tank from 4 times / year to 0 times / year. In addition, it was possible to replace the tank after the refractory was used up safely, and the cost of the refractory could be reduced.

1 ... container, 2 ... iron skin, 3 ... back insulation material, 4A ... permanent refractory, 4B ... wear refractory, 5 ... OB lance charging hole, 6 ... canopy, 7 ... upper tank, 8 ... lower tank, 9 ... Immersion tube, 10 ... Bullion, 11 ... Laser profile meter, 12 ... Radiation thermometer.

Claims (3)

Using one or more laser profile meters installed outside the container with the refractory lined on the inner surface of the iron skin, the inside of the container is irradiated with a laser to measure the profile of the refractory, and the profile is measured. Based on the process of calculating the residual dimension A of the refractory,
A step of measuring at least the surface temperature of the iron skin from the outside of the container at the same time as measuring the profile and calculating the residual size B of the refractory based on the surface temperature is included.
If the profile is measurable, the residual dimension A is defined as the residual dimension of the refractory.
When both the profile and the surface temperature were measurable, the difference between the residual dimension A and the residual dimension B calculated based on each was recorded as a correction value.
When the profile is not measurable and the surface temperature is measurable, the residual dimension B is corrected by using the latest correction value to calculate the residual dimension of the refractory. , Hot diagnostic method for refractories. The hot diagnostic method for a refractory according to claim 1, wherein in the step of calculating the residual dimension B, the surface temperature of the refractory is measured in addition to the surface temperature of the iron skin. The container is a vacuum degassing device used in steel refining.
Claim 1 or claim, wherein the laser profile meter is installed above the outside of the furnace of the vacuum degassing device and irradiates a laser from a furnace top opening toward the inside of the vacuum degassing device. The method for hot diagnosis of refractories according to 2.