JP2557544B2 - Control method of pig iron solidified layer thickness at blast furnace bottom - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to adjusting the temperature of a cooling medium for cooling the bottom of a blast furnace by adjusting the thickness of the solidified layer of pig iron solidified on the inner surface of the blast furnace bottom refractory. The present invention relates to a method for controlling the thickness of a pig iron solidified layer at the bottom of a blast furnace, which is controlled to a constant control value.

BACKGROUND ART Refractory at the bottom of blast furnace has a direct effect on the life of the blast furnace due to its wear, but it is difficult to repair or replace it. So conventionally,
In order to prevent wear of the refractory material, a cooling pipe is provided at the bottom of the blast furnace and a cooling medium is passed through the pipe to cool the refractory material. By cooling, a solidified layer of pig iron is formed on the inner surface of the blast furnace at the bottom of the blast furnace to prevent the refractory from directly touching the molten pig iron to prevent wear.

If the thickness of the solidified layer of pig iron formed on the inner surface of the blast furnace becomes extremely large, the internal volume of the blast furnace will be narrowed and the production amount of pig iron will decrease, and it will be difficult to extract molten pig iron to the outside of the blast furnace. Become.

Therefore, it is desirable to keep the thickness of the solidified layer of pig iron solidified on the blast furnace inner surface of the bottom refractory of the blast furnace to an appropriate thickness in consideration of both protection of the refractory and stable operation. It becomes necessary to adjust the temperature of.

Conventionally, the cooling medium which has passed through the inside of the cooling pipe at the bottom of the blast furnace and has reached a high temperature is passed through a cooling tower or cooled by the method shown in Japanese Patent Application No. 53-58405 and circulated. According to the cooling method, the temperature of the cooling medium after cooling cannot be adjusted to an appropriate temperature depending on the outside air temperature and the temperature of the cooling water, and therefore the solidified layer thickness of pig iron cannot be kept constant. Therefore, when you want to increase the thickness of the solidified layer of pig iron,
It is easy to solidify pig iron by adding expensive titanium to pig iron, increasing the fuel consumption per 1 ton of pig iron to increase the silicon contained in pig iron, or reducing sulfur, and reducing the production amount of pig iron. Was.

On the other hand, if you want to reduce the thickness of the solidified layer of pig iron,
It was difficult to solidify pig iron by increasing the fuel consumption per ton of pig iron to raise the temperature of pig iron or by increasing the sulfur in pig iron.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As described above, the conventional cooling tower and Japanese Patent Application No. 53
It is difficult to keep the thickness of the solidified layer of pig iron constant with a cooling method such as -58405, and it is necessary to use a method that accelerates or makes it difficult to solidify the pig iron. , And quality fluctuations will occur. Moreover, since there are a plurality of operating factors for keeping the thickness of the solidified layer of pig iron constant, automatic control becomes difficult.

The present invention intends to solve the above-mentioned problem by unifying the operation factor for keeping the thickness of the solidified layer of pig iron constant only to the temperature control of the cooling medium.

Means for Solving the Problems That is, the present invention, the cooling medium that has passed through the cooling pipe at the bottom of the blast furnace, through a refrigeration type cooling device that can freely control the load, solidification of pig iron in the range from the freezing point temperature of the cooling medium to the boiling point temperature The temperature is controlled so that the layer thickness can be kept constant, and the pig iron solidified on the blast furnace inner surface of the blast furnace bottom refractory from the indicated value of the thermometer embedded in the blast furnace bottom refractory. Of the solidification layer of the pig iron, the deviation from the target control value of the thickness of the solidification layer of pig iron, the time derivative of the deviation, and the circulating temperature of the cooling medium, the solidification layer thickness becomes the target control value. After calculating the set temperature of such a cooling medium, the load of the refrigerating cooling device through which the cooling medium is passed is adjusted, and the circulating temperature of the cooling medium is controlled to be the set temperature. .

Action In FIG. 4, when the thickness of the solidified layer of pig iron exceeds the target control value represented by the dotted line, the circulating temperature of the cooling medium rises,
This melts the solidified layer and reduces the thickness. On the other hand, when the thickness of the solidified layer is below the target control value, the circulating temperature of the cooling medium is lowered, the solidification of pig iron is promoted, and the thickness of the solidified layer is increased.

Example FIG. 1 shows a schematic cross-section of the bottom of the blast furnace. The bottom refractory 1 is a bottom cooling pipe 3 embedded in the upper part of the blast furnace foundation 2.
It is designed to be cooled by a cooling medium passed through. Although the molten pig iron 4 is accumulated in the blast furnace, the pig iron 5 solidified by cooling by the cooling medium adheres to the inner surface of the blast furnace bottom refractory 1 and the molten pig iron 4 and the bottom refractory 1
To prevent the furnace bottom refractory 1 from being worn out. When the solidified pig iron 5 grows thicker and exceeds the height of the exit nozzle 6, the molten pig iron 4
Cannot be extracted outside the blast furnace. Therefore, it is desired to keep the thickness of the solidified pig iron 5 constant. Therefore, in this example, the thickness of the pig iron solidified layer was controlled to be constant as follows. This will be described with reference to FIG.

The cooling medium is circulated in the circulation medium pit 8 by the circulation pump 7.
It is further pumped up, passes through the pipe 9, is distributed by the header pipe 11, and is passed through the furnace bottom cooling pipe 3. Then, after cooling the furnace bottom, it is collected again by the header pipe 11 and sent to the refrigerating type cooling device 12 through the pipe 9. The cooling medium cooled by the cooling device 12 is returned to the circulating medium pit 8 again.

A thermometer 13 is embedded in the furnace bottom refractory 1, and the thickness of the solidified layer of pig iron is calculated by the temperature measured by the thermometer.
It is calculated by the point-to-point method by 14, for example, and the value is output to the load controller 15.

The cooling medium in the circulating medium pid is agitated by the agitating device 16 to make the temperature uniform, and the measurement value measured by the thermometer 17 is output to the load control device 15.

The load control device 15 uses the deviation from the target control value of the thickness of the solidification layer of pig iron, the time derivative of the deviation, and the temperature of the cooling medium in the circulating medium pin based on a constant calculation formula to determine the solidification layer thickness. Then, the set temperature of the cooling medium is calculated so that the target management value is calculated as follows. Then, the load of the refrigeration type cooling device 12 is controlled so that the temperature of the cooling medium in the circulating medium pit becomes the set temperature. FIG. 3 shows an example of the control method by the load control device 15, in which the temperature of the furnace bottom refractory 1 is measured by the thermometer 13 (step 21), and based on the measured value, the calculation device 14 causes the pig iron to operate. The thickness of the solidified layer is calculated (step 22). On the other hand, the temperature of the cooling medium in the circulating medium pit is measured by the thermometer 17 (step 23). Next, the deviation between the thickness of the solidified layer of pig iron obtained by calculation and the preset target control value is calculated (step 24), and the time derivative of the deviation and the temperature of the cooling medium in the circulating medium pit are calculated. The set temperature of the cooling medium such that the thickness of the solidified layer of pig iron reaches the target control value is calculated based on an empirical formula (step 25).
Next, the temperature of the cooling medium measured by the thermometer 17 is compared with the set temperature (step 26), and when the measured temperature is higher, the temperature is lower, and when the measured temperature is lower, the temperature is higher than that of the refrigerating type. Control the load on the device 12 (step 27).

As described above, the cooling medium in the circulating medium pit is kept at the set temperature, pumped up by the circulation pump 7, and then supplied to the furnace bottom cooling pipe 3 to cool the furnace bottom (step 28).

As described above, the temperature of the cooling medium can be freely controlled within the range of the boiling point temperature from the freezing point temperature of the cooling medium according to the present embodiment, and various freezing point temperatures and boiling point ranges can be set by changing the type of the cooling medium. You can choose.

As described above, according to the present invention, it is possible to keep the thickness of the solidified layer constant, thereby preventing the furnace bottom refractory from being worn,
Also, stable operation of the blast furnace can be maintained. Moreover, since the thickness of the solidified layer of pig iron is kept constant only by controlling the temperature of the cooling medium, the cost, production and quality of pig iron are not affected and automatic control is possible.

[Brief description of drawings]

1 is a vertical sectional view of the bottom of the blast furnace, FIG. 2 is a block diagram of the method of the present invention, FIG. 3 is the same flowchart, and FIG. 4 is a graph of the circulating temperature of the cooling medium and the thickness of the solidified layer of pig iron. It is a figure. 1 ... Furnace bottom refractory, 2 ... Furnace bottom foundation 3 ... Furnace bottom cooling pipe, 4 ... Molten pig iron 5 ... Solid pig iron, 6 ... Exit gun 7 ... Circulation pump, 8 ... Circulating medium pit 12 ... Refrigerating cooling device , 13, 17 ... Thermometer 14 ... Computing device, 15 ... Load control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-184607 (JP, A) JP-A-2-293513 (JP, A) JP-A-57-32309 (JP, A)

Claims (1)

(57) [Claims] 1. A process for calculating the solidified layer thickness of pig iron solidified on the blast furnace inner surface of the blast furnace bottom refractory from the temperature measurement value of the blast furnace bottom refractory, and the obtained target control value of the solidified layer thickness. Deviation, the time derivative of the deviation, and the process of calculating the set temperature of the cooling medium such that the solidified layer thickness of the pig iron is the target control value from the temperature of the cooling medium circulating in the furnace bottom cooling pipe, Adjusting the load of the refrigerating cooling device through which the cooling medium is passed, and controlling the circulating temperature of the cooling medium to be the above set temperature, which is characterized in that it comprises a process of controlling the thickness of the pig iron solidified layer at the bottom of the blast furnace. Control method.