JP2718305B2 - Estimation method of erosion line at blast furnace bottom - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for estimating a bottom erosion line for accurately grasping the state of erosion of a blast furnace bottom.

[0002]

2. Description of the Related Art In the operation of a blast furnace, the blow-off timing of the blast furnace is determined based on an estimation that it is determined that the erosion of the refractory brick at the bottom has reached a critical point. Therefore, the life of the furnace body is extended or shortened by one to two years depending on the accuracy of the estimation, and the economical effect is great. Conventionally, the estimation of the erosion line at the hearth has been performed by estimating and calculating the temperature distribution in the hearth brick using the measured values of a plurality of thermometers buried in the hearth brick, and the 1150 ° C isotherm where pig iron is considered to be solidified. Was defined as the erosion equilibrium line of the brick surface. When calculating the temperature distribution in the brick, the thermal conductivity of a healthy brick was used as the thermal conductivity of the brick, and the 1150 ° C. isotherm was determined as the brick erosion equilibrium line.

[0003]

However, when the furnace bottom erosion equilibrium line of the blast furnace disassembled after blowing off is confirmed, the temperature of the eroded surface of the brick is actually 1150 ° C. due to penetration of hot metal into the brick (joint joint). Coincide with a higher isotherm,
In addition, it was found by actual measurement that the infiltrated bricks were altered and the apparent thermal conductivity was several times larger than that of healthy bricks. Therefore, the conventional method of estimating the bottom erosion line has a problem that the estimation accuracy is low and a determination for extending the life of the bottom is not accurately performed.

The present invention solves such a conventional problem by improving the accuracy of estimating the bottom erosion line, increasing the accuracy of predicting the bottom life, and changing the operation for increasing the bottom life. TiO ₂ loading timing, SoIriryou tuyere blow position, the coke particle size management, and to propose an O / C radial distribution, etc.) timing to be able to clarify a blast furnace bottom erosion line estimation method of Things.

[0005]

SUMMARY OF THE INVENTION According to the present invention, the thermal conductivity of the bottom erosion brick and the temperature of the brick erosion surface, which are found by the dismantling inspection of the blast furnace, that is, the thermal conductivity is several times that of a healthy brick due to the presence of joints. In consideration of the fact that the temperature of the brick erosion surface is larger than the solidification temperature of the hot metal (about 1150 ° C.), the accuracy of estimating the furnace bottom erosion line is improved. The temperature of the bottom brick eroded surface is set between the solidification temperature and the tapping temperature of the hot metal, and the thermal conductivity of the eroded brick in the region between the furnace bottom brick eroded surface and the hot metal solidification temperature isotherm is determined by the sound brick. Several times larger than thermal conductivity
Under the conditions ku set, based on the highest of the furnace bottom temperature values past out of the furnace bottom temperature values measured at a plurality of locations of the furnace bottom furnace bottom bricks
Estimate the temperature distribution and calculate it based on the isotherm of the calculated temperature distribution.
To estimate the bottom erosion line .

[0006]

FIG. 1 shows the result of the dismantling inspection of the blast furnace A (furnace volume: 4300 m ³ ). In the figure, 1 is a chamotte brick, 2 is a carbon brick, and 3 is a furnace bottom brick temperature measurement position. That is,
Joints were confirmed up to the 1150 ° C isothermal line where the pig iron solidified. On the other hand, the bricks in the region where no joints existed had very little alteration at high temperatures, and the thermal conductivity of the bricks was the same as that of healthy bricks. However, in the region above 1150 ° C. and up to the erosion surface of the brick, the thermal conductivity of the brick is less than that of a sound brick (thermal conductivity of 4.4 kcal / m ² / hr / ° C.) due to the jointing and penetration of hot metal. It had reached about four times. Therefore, the highest temperature was selected from the actually measured values of the furnace bottom brick temperature during operation, and the furnace bottom erosion line was estimated to match that temperature.
° C isotherm.

[0007] Next, the furnace bottom erosion line in the B blast furnace (furnace volume 5100 m3) was estimated. Again, A
As in the case of the blast furnace, the bottom erosion line was determined as an isothermal line at 1350 ° C. so as to match the maximum temperature of the bottom brick, and as a result of comparison with the dismantling inspection results, the two were within the range of ± 5 cm. However, in this case, the thermal conductivity of the brick in the region between the pig iron solidification temperature of 1150 ° C and 1350 ° C is a sound brick.
(The thermal conductivity of sound brick 4.4 kcal / m ² / hr /
° C) .

From the results of the above dismantling survey, the temperature of the eroded surface of the furnace bottom brick in the present invention was determined as the solidification temperature (1
150 ° C) and tapping temperature (1500 ° C), and the thermal conductivity is set several times larger than the thermal conductivity of healthy bricks
It is preferable to have been found. Therefore, under such conditions, among the bottom temperature values at
Estimator of temperature distribution in hearth brick based on high hearth temperature
Then, the estimated value of the bottom erosion line obtained based on the isotherm of the calculated value of the temperature distribution necessarily becomes highly accurate.

[0009]

EXAMPLES In estimating the bottom erosion line using the actually measured value of the bottom brick temperature, the highest temperature in the past was used, and the solidification temperature of pig iron at 1150 ° C. and the hot metal joint between the brick erosion surface in the hot metal joint area were determined. The thermal conductivity obtained by estimating and calculating the thermal conductivity of the brick assuming that it consists of 85% of healthy brick and 15% of hot metal is used. Then, a temperature distribution in the furnace bottom brick is determined so as to match the highest temperature in the past, and the 1150 ° C. isothermal line is used as a jointing line. 135 higher in temperature than this jointing line
The region up to 0 ° C. is treated as a deteriorated brick layer into which molten iron has penetrated, and the 1350 ° C. isothermal line is used as a brick erosion surface.

During operation, the measured temperature value changes every moment, but when the temperature decreases, the 1350 ° C. isothermal line moves from the brick erosion surface to the inside of the furnace. When the brick erosion surface becomes 1150 ° C. or less, the brick erosion surface becomes 115
The region between the 0 ° C. isothermal surface is considered to be the layer where the hot metal has solidified. FIGS. 2A and 2B are schematic diagrams showing the state of the hearth corresponding to these various temperature changes. FIG. 2A shows the state of the hearth brick at the highest brick temperature in the past, and FIG. When the temperature of the eroded surface is 1150 ° C. or more and 1350 ° C. or less, (c) shows a state where the temperature of the eroded surface is 1150 ° C. or more and a solidified layer grows on the eroded surface.

FIG. 3 shows a change with time of the bottom erosion line in the B blast furnace to which the method of the present invention is applied. In the figure, the solid line is the erosion line estimated on the solidification line of pig iron (about 1150 ° C.) according to the conventional method, and the dotted line is the hearth brick erosion line estimated on the method of the present invention. From this data, the erosion limit will be reached in the ninth year with the conventional method, but when re-estimated with the method of the present invention,
Even in the tenth year, it was found that there was room for hearth erosion, and it was not necessary to insert TiO ₂ for protecting the furnace bottom or increase the particle size of coke, which had been implemented up to that point, so that cost reduction was not possible. Was.

[0012]

According to the present invention, as described above, the thermal conductivity of the actual furnace bottom erosion brick found from the dismantling investigation of the blast furnace,
Since this method estimates the erosion line at the hearth by taking in the temperature of the brick erosion surface, the erosion line at the hearth can be estimated more accurately. Therefore, according to the present invention, by improving the accuracy of predicting the life of the hearth, it is possible to clarify the timing of the operation change means for extending the life of the hearth, thereby reducing the cost, This has an excellent effect that the time of blowing can be accurately determined.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a result of a dismantling inspection of a blast furnace A and a furnace bottom erosion estimation line in the present invention.

FIG. 2 is an explanatory view showing an erosion state of a hearth brick in an embodiment of the present invention, wherein (a) is a state of a hearth brick which is the highest ever;
(B) shows the state of the bottom erosion when the bottom erosion surface is lower than 1350 ° C., and (c) shows the state where a solidified layer exists on the bottom erosion surface.

FIG. 3 is a diagram showing a temporal change of a furnace bottom erosion line in the embodiment.

[Explanation of symbols]

 1 Chamotte brick 2 Carbon brick 3 Hearth brick temperature measurement position

Claims (1)

(57) [Claims] 1. A method for estimating an erosion line of a blast furnace bottom brick by heat transfer calculation, wherein the temperature of the erosion surface of the bottom furnace brick is set between the solidification temperature of hot metal and the tapping temperature, and The thermal conductivity of the eroded brick in the region between the hot metal and the solidification temperature isothermal surface is several times larger than that of the healthy brick.
Listen at the set conditions, the furnace bottom bricks based on record of the furnace bottom temperature value of the furnace bottom temperature values measured at a plurality of locations of the furnace bottom
Estimate the internal temperature distribution and calculate the isotherm of the calculated temperature distribution.
A method for estimating an erosion line on a blast furnace bottom, comprising estimating a bottom erosion line based on the blast furnace.