JPH06212215A - Method for controlling temperature of refractory brick at furnace bottom - Google Patents

Abstract

(57) [Abstract] [Purpose] The temperature of refractory bricks on the bottom of the blast furnace is controlled to a predetermined value to suppress local wear of the refractory bricks around the bottom of the furnace. [Composition] At the height of the furnace mouth, the distribution of coke and ore is obtained for each of a plurality of radial directions from the center of the furnace, and the radiation including the part where the local temperature rise of the refractory brick at the furnace bottom is estimated to occur Change coke and ore distributions for direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention aims to suppress the local wear of the refractory bricks, particularly the peripheral wear of the furnace bottom, by controlling the temperature of the refractory bricks at the bottom of the blast furnace to a predetermined value. Regarding how you can.

[0002]

The most important factor in determining the life of a blast furnace is damage to the bottom of the blast furnace, that is, reduction of the wall thickness due to erosion of refractory bricks lined in the bottom. Refractory bricks are lined on the inner surface of the blast furnace, but the refractory bricks gradually wear away during operation and the wall thickness decreases. Thus, if the thickness of the refractory brick is reduced to a certain level or less due to wear, it becomes impossible to continue the operation. In such a case, it is necessary to suspend the operation and construct a new refractory brick.

In general, refractory bricks may be worn evenly over the entire surface of the furnace, but a particular part is often worn preferentially. Therefore, in order to suppress the wear of the refractory bricks, it is required to take appropriate measures depending on the degree and the site of the wear, and conventionally, to suppress the wear of the refractory bricks and prolong the life of the blast furnace. Various proposals have been made.

For example, in Japanese Patent Laid-Open No. 60-56004, when it is estimated that the wear of a refractory brick is in progress, powdery titanium ore is removed from the tuyere in the vicinity of the partially worn part. A method has been proposed in which an appropriate amount of Ti source is added to protect the worn portion.

In Japanese Patent Laid-Open No. 274209/1993, when the detected value of the furnace bottom temperature exceeds a set value, the air volume difference between the tuyere blowing Ti source and the tuyere not blowing Ti source is calculated. A method has been proposed in which the furnace bottom temperature is maintained at a normal value by detecting and controlling the supply amount of the Ti source from the tuyere blowing the Ti source in accordance with the fluctuation of the air volume difference.

In Japanese Patent Laid-Open No. 3-274207, the temperature of the refractory bricks at the bottom of the furnace is controlled by arranging a refrigerating cooling device in a part of the cooling medium path of the refractory bricks at the bottom of the furnace to control the temperature of the cooling medium. Has been proposed to control the thickness of the pig iron solidified layer at the furnace bottom, which greatly affects the erosion state of refractory bricks. This method is a method of controlling the temperature of the refractory bricks by arranging water-cooling pipes of refractory bricks at various places and appropriately controlling the amount of water flowing to the water-cooling pipes and the temperature of the water flowing therethrough.

Further, in Japanese Examined Patent Publication No. 3-77844, coke (solid reducing agent) is locally charged into the central part of the furnace to improve the liquid permeability in the central part of the core, thereby improving the bottom of the furnace. It has been proposed to suppress the erosion of the peripheral area of the furnace bottom by controlling the hot metal flow and the molten metal flow in the furnace so that they mainly pass through the central part of the furnace bottom.

[0008]

The method proposed by Japanese Patent Laid-Open No. 60-56004 or Japanese Patent Laid-Open No. 3-274209 is an effective method for localized wear of refractory bricks in a furnace. However, it is necessary to install a dedicated blower and a dedicated burner on the blast branch pipe in the necessary direction, and it is necessary to significantly reduce or stop the wind during these installations. It is not the preferred method.

In the method proposed by Japanese Patent Laid-Open No. 3-274207, a special cooling medium facility must be provided,
Equipment costs will increase significantly. Further, although this method is effective for the wear of the central part of the furnace bottom, it cannot be said that it is very effective for the site where the local wear is severe such as the peripheral part of the furnace bottom.

The method proposed in Japanese Examined Patent Publication No. 3-77844 requires the addition of a dedicated charging device capable of controlling the distribution of the charged material depending on the type of the existing charging device of the blast furnace. Further, since this method controls the wear of the central part of the furnace bottom, it is difficult to be a direct control means for the wear of the peripheral part of the furnace bottom, especially the local part of the peripheral part of the furnace bottom. There is a problem.

Here, the object of the present invention is to accurately control the temperature of the refractory bricks on the bottom of the blast furnace to a predetermined value to prevent local wear of the refractory bricks on the periphery of the bottom of the furnace. To provide a method.

[0012]

[Means for Solving the Problems] Generally, when the temperature of the refractory bricks at the bottom of the furnace rises, the wear of the refractory bricks progresses, or the pig iron solidified layer melts or disappears. When the temperature of the refractory bricks at the bottom decreases, adhesion and growth of the pig iron solidified layer occur, and when the temperature of the refractory bricks at the furnace bottom significantly decreases, excessive growth of the pig iron solidified layer occurs. It is considered that the contact between the hot metal and the refractory brick becomes insufficient at the bottom of the furnace.

Therefore, in order to suppress the wear of the refractory bricks, the refractory bricks at the bottom of the furnace should be operated at an optimum temperature without being raised or lowered too much. It is important to operate with the pig iron solidified layer present in a suitable thickness and covering and protecting the surface of the refractory brick with the pig iron solidified layer. Therefore, the present inventor wondered whether the temperature of the refractory bricks at the furnace bottom could be controlled by controlling the factors that affect the thickness of the pig iron solidified layer, and conducted further studies.

The present inventor, when operating while changing the distribution of the top charge in a plurality of radial directions at the height of the furnace mouth, uses a swirling chute type (bellless type) charging device for coke and Based on the ore charging schedule and the profile meter arranged at the furnace top, the ratio O / C value of the ore charging amount O and the coke charging amount C on the center side and the wall side in the horizontal plane, and the following formula Radial distribution index R value calculated by

[0015]

[Equation 1] R value = (wall side O / C value) / (center side O / C value) ... is calculated for each radial direction, and the R value during this operation period or the refractory brick Around the bottom of the furnace where the wear is remarkable (on the bottom wall side)
I checked the temperature. The results are summarized in the graph in FIG.

From the graph shown in FIG. 1, the temperature of the refractory brick at the bottom of the furnace decreases while the R value approaches 1, but when the R value exceeds 1, that is, the amount of coke charged on the wall side is large. It was found that when the air permeability of the center is poor, the temperature of the refractory bricks arranged around the furnace bottom (on the furnace bottom wall side) rises and shows a high value.

Therefore, the inventor of the present invention utilizes the correlation between the temperature of the refractory bricks around the furnace bottom and the R value to obtain the temperature of the refractory bricks around the furnace bottom where local wear is remarkable. Various studies have been conducted to see if it is possible to control the desired value.

FIG. 2 (a) is a vertical sectional view showing an example of the arrangement of various sensors of the blast furnace 1, and FIG. 2 (b) is shown in FIG.
It is a horizontal cross-sectional view in the furnace opening height of the blast furnace 1 shown in (a). In FIG. 2 (a), reference numeral 8 is a blast branch pipe flow meter,
Reference numeral 9 is a static pressure gauge.

The inventor of the present invention has shown in FIG. 2 (b) that various circumferential sensors provided near the furnace opening of the blast furnace (specifically, a top sonde 4 and a horizontal probe for analyzing gas components in the height direction). From the skin flow sonde 5 for analyzing the gas component in the horizontal direction, or the μ-wave profiler 6 for measuring the distribution of the vertical charge and the upper sampler 7) for measuring the horizontal charge distribution. O / C values (charge distribution) for each of a plurality of estimated radiation directions and R values according to the above equations are calculated, and various sensors provided on the bottom of the furnace (specifically,
2 (a), the refractory on the bottom of the furnace including the radiation direction from the information of the refractory brick thermometer 2 for measuring the temperature of the refractory brick on the bottom of the furnace, the ED sensor 3 for measuring the wear length of the refractory brick, etc. The heating condition of the wall is estimated, and if a local temperature rise is estimated, the distribution of coke or ore by the charging device is changed so that the R value in the radial direction approaches 1, and the O / C on the wall side is changed. By changing the value, it becomes possible to control the local temperature rise of the refractory bricks on the wall side of the hearth, and local wear, and further, the temperature of the refractory bricks on the wall side of the hearth. Is too low,
The present invention has been completed by finding that the temperature of refractory bricks around the furnace bottom can be controlled to an appropriate value by changing the distribution of coke or ore so that the R value becomes large.

Here, the gist of the present invention is a method for controlling the temperature of refractory bricks at the bottom of a furnace, in which the distribution of coke and ore at a plurality of radial directions from the center of the furnace at the height of the furnace mouth. The temperature control of the refractory bricks of the hearth is characterized by changing the distribution of coke and ore in the radial direction including the part where the local rise in the temperature of the refractory bricks of the hearth is estimated. Is the way.

In the present invention, in order to obtain the distribution of coke and ore for each of a plurality of radial directions from the furnace center at the height of the furnace mouth, for example, in the height direction in FIG. 2 (a) or FIG. 2 (b). Of the ore charging amount O with respect to the coke charging amount C on the center side and the wall side, respectively, by using the μ-wave type profile meter 6 for measuring the charging distribution of B and the upper sampler 7 for measuring the charging distribution in the horizontal direction. Skin flow for measuring the ratio O / C value, or for the apex sonde 4 for analyzing the gas component in the height direction and for analyzing the gas component in the horizontal direction in FIG. 2 (a) or 2 (b). It can be determined by conducting an analysis using a sonde 5. In addition, O /
When the C value is obtained, it is desirable to obtain it two-dimensionally by using the data in the horizontal direction and the data in the vertical direction from the viewpoint of improving the measurement accuracy.

In the present invention, the distribution of coke and ore is changed by changing the R value obtained by the above equation using the above O / C value when, for example, a μ wave type profile meter and an upper sampler are used. With respect to the radial direction in which the local temperature rise of the refractory brick at the bottom of the furnace is estimated to be calculated, R / O on the wall side is set so that the R value approaches 1.
The C value may be changed. For example, in the case of using a top sonde and a skin flow sonde, the O
The / C value may be calculated and processed in the same manner.

In other words, according to the present invention, the erosion state of the bottom brick in the radial direction estimated based on the information of various temperature sensors (furnace bottom wall and bottom portion) installed at the bottom of the furnace and the vicinity of the furnace mouth Two-dimensionally based on the information of various installed charge distribution sensors, the distribution of the measured charge in two dimensions (horizontal and height directions), or the information of various in-reactor gas component sensors installed near the furnace mouth. This is a method of changing the distribution of coke and ore at the height of the furnace mouth so as to reduce the local temperature rise of the bottom brick by combining with the calculated charge distribution situation.

[0024]

The operation of the present invention will be described in detail below. In the present invention, the distribution of coke and ore is obtained for each of a plurality of radial directions from the furnace center, for example, by sensors provided in a plurality of radial directions at the furnace mouth height. This distribution is
O / in the calculation from the gas components that were collected and analyzed in the furnace gas
Although it can be obtained by obtaining the C value, it may be obtained by directly measuring the distribution of the contents in the furnace interior using various sensors. The radiation direction may be determined appropriately. For example, the direction divided into 8 at equal intervals from the center of the furnace can be exemplified.

Next, in the present invention, the R value is obtained for each radial direction by the above formula from the wall side O / C value and the central side O / C value for each radial direction thus obtained. The R value is 2.0 to 8.0 during normal operation.

In the present invention, next, the erosion state of the refractory bricks on the furnace bottom is estimated. This estimation is performed, for example, based on data from a furnace bottom brick thermometer, an ED sensor, or the like provided in the circumferential direction of the peripheral portion of the furnace bottom, and the wear state of the peripheral portion of the furnace bottom in the circumferential direction. As reported, for example, in Japanese Examined Patent Publication No. 3-77884, the wear progresses quickly on the fire wall side of the peripheral portion of the furnace bottom having a relatively thin wall, that is, the peripheral portion of the furnace bottom.

In the present invention, the R value in the radial direction and the R value in the other radial directions including the portion where the wear of the furnace bottom is progressing.
If the R value in the radial direction including the part where the wear is progressing is larger than the other R values, either the ore or coke is set so that the R value in the radial direction approaches 1. The charging amount is adjusted to reduce the wall side O / C value. In the radial direction in which the wall-side O / C value is lowered, the amount of ore is small and the amount of hot metal is small, so that the amount of hot metal dropped decreases. Therefore, since the amount of dissolution of the pig iron solidified layer in the radial direction becomes small, heating of the refractory brick, that is, local abrasion of the refractory brick can be prevented.

The adjustment of the charging amount of either the ore or the coke is carried out by a swirling chute type as an existing charging device.
(Bellless type) Since the charging can be performed by using the charging device, the present invention can be carried out without requiring a large facility modification or the like.

In the present invention, the O / C value and R
When obtaining the value, as shown in Fig. 2 (a) and Fig. 2 (b),
The reason why the charge distribution or the gas component distribution is obtained two-dimensionally in the horizontal direction and the height direction is that the measurement error becomes large if it is obtained one-dimensionally only in the horizontal direction. Further, the present invention will be described with reference to examples.

[0030]

EXAMPLE For the blast furnace 1 shown in FIGS. 2 (a) and 2 (b), the present invention was applied to control the temperature of refractory bricks at the bottom of the furnace. Note that the O / C value at the height of the furnace mouth is the μ-wave profiler 6 for measuring the distribution of the charge in the height direction in Fig. 2 (a) or 2 (b) and the distribution of the charge in the horizontal direction. Was measured by using the upper sampler 7 for measuring. Further, the radial direction was a direction divided into eight equal intervals from the center of the furnace.

FIG. 3 shows the wall side O in a certain radial direction.
/ When the C and R values are both high, and when both are relatively low, the furnace bottom peripheral areas 1 and 2 and the bottom (center)
The transition of the temperature of is shown in a graph. From FIG. 3, in the operation period in which the R value is set to be high, the amount of coke in the peripheral portion of the furnace bottom is large and the hot metal and refractory bricks in the peripheral portion of the furnace bottom are in active contact with each other, and the air permeability is poor on the center side. The temperature rise around the furnace bottom and the wear of the refractory bricks were likely to progress.

On the other hand, according to the present invention, in the operation period in which the R value is set to be close to 1, the temperature of the peripheral portion of the furnace bottom is lower than that in the period when the R value is high, but the amount of coke on the center side is reduced. Since the liquid permeability on the center side was good and the hot metal flow and the bricks were in active contact with each other, the temperature on the center side rose.

This is because the contact state between the hot metal flow and the refractory bricks in the peripheral portion and the central portion of the furnace bottom changes due to the change of the R value, and the growth / disappearance of the pig iron solidified layer and the progress of the wear of the bricks occur. It is thought to have changed. As described above, according to the present invention, it is possible to suppress the temperature rise in the peripheral portion of the furnace bottom where the local wear of the refractory brick is remarkable.

[0034]

As described in detail above, according to the present invention,
By utilizing the existing bellless charging device, it is possible to control the temperature of the refractory bricks around the furnace bottom of the blast furnace to a predetermined value without any special equipment modification, and the local area of the refractory bricks around the furnace bottom can be controlled. It has become possible to reduce the general wear and tear.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an R value and a temperature around a furnace bottom.

FIG. 2 (a) is a vertical cross-sectional view showing an example of the arrangement of various sensors of the blast furnace 1, and FIG. 2 (b) is a throat height of the blast furnace 1 shown in FIG. 2 (a). FIG.

FIG. 3 is a graph showing the results of Examples.

[Explanation of symbols]

 1: Blast furnace 2: Furnace bottom brick thermometer 3: ED sensor 4: Layer top sonde 5: Skin flow sonde 6: Profile meter 7: Upper sampler 8: Blower branch flow meter 9: Static pressure meter

Claims (1)

[Claims] 1. A method for controlling the temperature of a refractory brick at the bottom of a furnace, wherein the distribution of coke and ore is obtained for each of a plurality of radial directions from the center of the furnace at the height of the furnace mouth, and the refractory brick at the bottom of the furnace is found. The method for controlling the temperature of refractory bricks at the bottom of the furnace, characterized in that the distribution of the coke and the ore is changed with respect to the radial direction including the part where the local temperature rise is estimated to occur.