JPH0216961B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for measuring the amount of erosion of refractories. The cost of refractory bricks in steel manufacturing accounts for 1/3 of the total cost, and reducing the cost of these refractories is a major challenge. To this end, it is desirable to accurately measure the corrosion and loss of refractories during use, limit their use, and develop new refractories based on this analysis. In practice, the current determination of the amount of erosion of refractories still relies on human visual judgment or mere estimation, resulting in unstable accuracy and extremely large errors. Various methods have been proposed to measure the amount of corrosion loss of refractories. For example, there is ``Infiltration measurement by multi-point measurement of the bottom of a converter'' at the 69th Thermal Economics Technical Subcommittee Meeting of the Japan Iron and Steel Institute (November 19-20, 1981).
On the other hand, a method may be considered in which the distance is measured by irradiating a laser from the top of the furnace. However, these have the drawbacks of being expensive and having poor operability, and have not been fully put into practical use. The present invention relates to a method of measuring the amount of erosion of a refractory material using an electric pulse propagation time measurement method. TDR is a method for measuring the propagation time of electrical pulses.
There is a time refractmetry method, which measures the point of impedance change between two electrical conductors. This is generally put into practical use as a method for detecting insulation defects in electrical cables. This method will be explained with reference to FIG.
When the conductor 3 and the conductor 3 are connected to an electric pulse propagation time measuring device 4 and an electric pulse 5 is applied to the conductor, the pulse propagates through the conductor and detects an abnormality between the two conductors, such as an insulation defect. 6, the impedance change is maximum, so the electrical pulse is reflected there. This measured waveform is shown in FIG. The time from the generation of this pulse to the detection of the reflected pulse is measured to detect an abnormal part of the cable. When this method is applied to a method for measuring erosion of refractories, an electrical conductor is embedded within the refractories. This conductor, along with the refractory bricks, is eroded by molten steel and the like.
By measuring the length of this conductor using the electric pulse propagation time difference method, it is possible to measure the amount of erosion of the refractory. However, refractory bricks are made from molten steel (temperature 1650 ~
1750°C), electrical conductors are also heated to high temperatures. Therefore, it is desirable to have a detection rod with a structure in which the impedance between the two conductors is maintained constant even at such high temperatures, and the impedance changes greatly at the tip that is melted. In addition, at high temperatures, the propagation speed of electric pulses changes, and the conductor itself also expands thermally, so
Measurement errors occur. Therefore, a method of temperature correction is needed. SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems and provide a method for measuring the amount of erosion of refractories with high accuracy even at high temperatures. Hereinafter, a detailed explanation will be given based on an example. FIG. 3 shows the structure of a measuring element according to an embodiment of the present invention, which is embedded in a refractory brick and is used to measure the propagation time of an electric pulse. 7 is a protective pipe made of a heat-resistant material such as SUS, and two constantan wires 8 and 8' are inserted into it as conductors for electric pulses.
In order to keep the impedance between the lines constant, the distance between the lines is kept constant by an insulator 9 (alumina type). Inside this insulator 9, insulators 10 and 10' (high alumina type) made of a different material from the insulator 9 are placed at regular intervals.
The pipe 7 is completely fixed by filling magnesia powder 11 between it and the insulators 9 and 10. This measuring element is inserted into a refractory brick, an electric pulse is applied from one end, and the length of this conductor is measured as the electric pulse propagation time. This measured waveform is illustrated in FIG. 4 in comparison with FIG. 3.
Clear waveform change points 12 and 12' are obtained at electrical impedance change points 10 and 10'. In addition, the tip of the measuring element has two conductors 8, 8'
Since it is electrically shot, there is no reflection of the electric pulse, and the reflectance becomes 0. Since refractory bricks are exposed to high temperatures, Figure 5 shows the results of an investigation into measurement accuracy at high temperatures. The horizontal axis represents temperature (° C.), and the vertical axis represents the difference between the length determined from the electric pulse propagation time at room temperature and the measured length at each temperature. The difference in length varies depending on the temperature, and is approximately 30 mm longer at approximately 1000°C. This is thought to be due to the propagation speed of the electric pulse and the thermal expansion of the conductor. For this reason, the fourth
Corrected by the time difference between the impedance change point distances shown in the figure. That is, it is corrected by l/t ₁ =l ₀ /t ₀ ;l ₀ =t ₀ ·l/t ₁ . where l is the known length, t ₁ is the pulse propagation time within the known length l, and l ₀ is the pulse propagation time within the distance from the reference point to the tip of the electrical conductor. In fact, it can be easily determined by the scale ratio on the recording paper based on the measured waveform of electric pulse propagation. By this method, the difference between the actual length and the length measured by the method of the present invention was determined in an atmosphere at 1200°C. The results are shown in FIG. According to this, it was found that measurement could be performed with an accuracy of ±3.0 mm. Next, an example of actual machine application will be explained. In this example, the target equipment is a molten steel ladle, and the embedding position of the measuring element is the slag line shown in FIG. Reference numeral 13 is an iron skin, a hole of 5 mmφ is made in this, and measuring elements 15, 15' are embedded into the refractory brick 14 through this hole, and the length of this measuring element is fixed for a certain period of time using the method described above. Measured at intervals. This result is the 8th
As shown in the figure, it can be seen that the pot deteriorates as the number of times it is used increases. When the amount of erosion reached the critical point, the pot was repaired and the relationship between the remaining brick thickness and the measured values was investigated. The results are shown in Table 1.

【table】

[Table] As described above, according to the present invention, a technology that can measure the amount of erosion of refractories within ±3.0 mm has been established, which has greatly contributed to accurate measurement of the remaining thickness of refractories and associated cost reduction. be. In the above embodiment, a constantan wire was used as the electric conductor, but a tungsten wire or the like may also be used in the same manner. Furthermore, although an example has been shown in which the material of the insulator is changed as a means for changing the inter-line impedance, the spacing between the conducting wires may be changed only in that portion. Furthermore, in addition to the above,
It can be similarly used for controlling the amount of erosion of bottom blowing nozzles, etc.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an outline of a device used in the electric pulse propagation time measurement method, and FIG. 2 is a graph showing measurement data in this device. FIG. 3 is a side view showing the structure of a device implementing one embodiment of the present invention, FIG. 4 is a graph showing measurement data obtained thereby, and FIG. Graph showing the relationship between temperature and elongation, No. 6
The figure is a graph showing the accuracy of the measurement results, Figure 7 is a sectional view showing the device shown in Figure 3 attached to a molten steel ladle, and Figure 8 shows the measurement results in the manner shown in Figure 7. It is a graph. 7: Protective pipe, 8, 8': Electric conductor, 9, 1
0, 10': insulator, 15, 15': measurement element.

Claims (1)

[Claims] 1. A measurement element with two or more line-to-line impedance change points in the length direction of two electrical conductors is embedded in a refractory, and the time it takes for an electrical pulse to propagate through the electrical conductors and be reflected at the tip. The length of the electrical conductor is determined by correcting the measurement time based on the distance between the line impedance change points and the pulse propagation time between these points, and from this, the amount of erosion of the refractory can be determined. Characteristic method for measuring the amount of corrosion of refractories.