JP2718274B2 - Cooling capacity control method for 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 controlling a cooling capacity of a hearth in a blast furnace having a thin hearth structure.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing the structure of a conventional normal furnace bottom, in which a multilayered chamotte brick 3 and a carbon brick 4 are laid from a furnace interior 1 to a base 2.
A cooling pipe 5 is buried under the furnace to indirectly cool the furnace bottom.

However, recently, in order to extend the life of a blast furnace, a thin furnace bottom structure having a strong cooling capacity that is hardly corroded by hot metal has been adopted. This furnace bottom is
As shown in FIG.
And a graphite brick 6 having a high thermal conductivity is employed below the carbon brick 4 which is a conventional bottom brick of the furnace bottom, and the cooling pipe 5 of the bottom is directly connected to the bottom 2 as shown in FIG. The cooling capacity is enhanced by the contact arrangement, and the hot-metal-resistant C-SiC brick 7 having high thermal conductivity is adopted for the side wall.
By adopting such a structure, the cooling capacity is enhanced about five times as compared with the conventional furnace bottom. In addition, 8 in FIG. 2 shows a blast furnace cement, and 9 shows a stamp material.

[0004]

However, since the cooling capacity of the above-mentioned thin furnace bottom is constant irrespective of the production amount of the blast furnace, the cooling capacity of the furnace bottom at the time of a decrease in the production amount or at the time of a shut down is considered. When the heat input decreases, the cooling capacity becomes superior, and the pig iron or slag in the hearth solidifies, as shown in FIG. 5, and the effective hearth volume decreases, causing a tapping residue discharge trouble. Cause. In addition, 10 in FIG.
Reference numeral 1 denotes a tuyere.

[0005] That is, conventionally, the technology related to the hearth,
There are many things about raising the cooling capacity to prevent the erosion of the furnace bottom, and easing the cooling capacity promotes local erosion by hot metal, which may cause the hot metal to flow out of the furnace bottom, Almost no study has been made, but only in a normal blast furnace with a bottom structure.
Nos. 48 and 59-125957. However, even in these cases, fine control cannot be performed in accordance with the amount of change in the production amount.

Further, by adjusting the hot metal composition in the operation of the blast furnace, it is possible to adjust the erosion amount to some extent, such as a decrease in [Ti] and the hot metal temperature, but it is impossible in the case of a large fluctuation in the production amount. .

The present invention has been made in view of the above-mentioned conventional problems. The present invention has been made to reduce the furnace bottom cooling capacity to such an extent that the erosion of the furnace bottom is not promoted, so that even when the production amount is reduced, the furnace is cooled. It is an object of the present invention to provide a method for controlling a cooling capacity of a blast furnace bottom, which can suppress the growth of a solidified layer on a bed as much as possible.

[0008]

In order to achieve the above object, a method for controlling the cooling capacity of a blast furnace hearth according to the present invention comprises the steps of:
By reducing the thickness of chamotte bricks at the bottom of the furnace bottom lower brick with placing graphite bricks, C in the sidewall portion throughout -
In a blast furnace having a thin furnace bottom structure employing SiC bricks, a drain plate is provided in the entire circumferential direction of the side wall at a height near the maximum allowable erosion line of the furnace bottom, and a cooling pipe and a shower pipe in the side wall portion arranged in contact with the bottom plate. In addition, a cooling medium flow control valve is interposed, and the flow rate of the cooling medium is adjusted to decrease according to the rate of decrease in the blast furnace production, thereby preventing the growth of a solidified layer in the hearth.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below with reference to FIGS. Reference numeral 12 denotes a drain plate provided so as to surround the entire side wall of the furnace bottom at a height near the maximum allowable erosion line L. Cooling shower pipes 13 and 14 on the furnace bottom side wall so as to sandwich the drain plate 12 therebetween. Is installed. In the present invention, a flow control valve is provided in each supply pipe (not shown) for supplying cooling water to the cooling pipe 5 and the shower pipes 13 and 14, and the flow rate is adjusted in accordance with a change in blast furnace production. The opening of the regulating valve is adjusted to optimally control the amount of cooling water.

That is, when the blast furnace production volume is reduced, the method of the present invention reduces the amount of cooling water in accordance with the rate of this decrease. Assuming that the cooling capacity in the case of (1) is 100, the cooling capacity is reduced by adjusting the opening of each flow control valve as shown in Table 1 below when the blast furnace is shut down. Table 1
2 also shows the cooling capacity in the case of a normal furnace bottom structure.

[0011]

[Table 1]

The rate of decrease in the amount of cooling water according to the present invention may be determined based on the temperature detected by a thermometer 15 buried in the bottom refractory brick in order to monitor the state of wear of the bottom refractory brick. Alternatively, it may be determined on the basis of the relationship between the blast furnace production amount and the respective cooling water amounts, which is obtained in advance in the experimental furnace or the first operation. When the cooling capacity was reduced as shown in Table 1 above by reducing the amount of cooling water when the blast furnace was shut down, the rate of decrease in the furnace bottom temperature was as indicated by the black circle in FIG. 3, and in the case of the conventional thin furnace bottom structure (FIG. , The decrease in the furnace bottom temperature could be suppressed. This makes it possible for the calm wind to rise smoothly,
It means that it is effective in preventing trouble.

At the same time, FIG. 3 shows a case of a normal furnace bottom structure (▲
) Is also shown, but in this case the furnace bottom temperature is 15
It does not drop much at 0 hours. This means that the bricks at the bottom of the furnace are greatly worn.

[0014]

As described above, according to the present invention, it is possible to suppress the decrease in the production amount of the blast furnace and the growth of the solidified portion of the hearth when the blast furnace is shut off, while preventing the wear of the hearth brick as much as possible. It has the effect of.

[Brief description of the drawings]

FIG. 1 is a drawing of a thin hearth structure to which the method of the present invention is applied.

FIG. 2 is an enlarged view of the vicinity of a bottom plate in FIG.

FIG. 3 is a diagram illustrating an example of a relationship between a pause time and a decrease in a furnace bottom temperature.

FIG. 4 is a drawing of a normal furnace bottom structure.

FIG. 5 is a diagram illustrating the growth of a solidified layer in a hearth.

[Explanation of symbols]

 5 Cooling pipe 12 Drain plate 13, 14 Shower pipe 15 Thermometer L Maximum allowable erosion line

Claims (1)

(57) [Claims] 1. A blast furnace having a thin hearth structure in which the thickness of chamotte bricks at the hearth is reduced and graphite bricks are arranged below the bottom bricks at the bottom of the hearth, and C- SiC bricks are used in the entire side wall portion, A drain plate is provided on the entire circumference of the side wall at the height near the maximum allowable erosion line on the furnace bottom, and
A cooling medium flow control valve is interposed in the cooling pipe and the shower pipe on the side wall that are in contact with each other, and the flow rate of the cooling medium is adjusted to decrease according to the rate of decrease in blast furnace production, and the solidification layer in the hearth grows. A method for controlling the cooling capacity of a blast furnace bottom, characterized by preventing blasting.