JPH02225607A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To maintain stable blast furnace operation by controlling piling shape of coke in the furnace so that distance from the furnace wall to the shoulder part exceeds the specific value. CONSTITUTION:Section from neighborhood, where an inclined angle of surface of the piling material toward the furnace wall from the furnace center becomes <15 deg., to the furnace wall, is defined to 'Terrace' and (a) for extension line of inclined surface at furnace center side of the Terrace, (b) for extension line of the piling surface of the Terrace and Terrace length R for the distance from the point of intersection of (a) and (b) to the furnace wall, are used. In the control of gas flow in the blast furnace, the piling shape of the coke in the furnace is made so that R exceeds 1.5m. By this method, gas flow distribution at the furnace center is secured to about 30% and the stable blast furnace operation is maintained.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method of operating a blast furnace.

(Prior Art) Generally, in blast furnace operation, adjustment of the charge distribution occupies an important position as a means of controlling the gas flow distribution within the furnace.

In recent years, especially with the introduction of bellless charging equipment and continuously driven movable armor, the degree of freedom in charge distribution has improved, and coke and ore can now be charged at any charging position in the radial direction of the furnace. , it became possible to create a charge pile shape that was different from the conventional one.

In addition, by using a μ-wave profile meter with a layer thickness of 1゛, etc., it becomes possible to easily obtain detailed information on the shape of the charge deposition, making it possible to understand the shape of the deposition in response to changes in the gas flow in the furnace. It is becoming.

With these technical backgrounds, it has become possible to maintain stable blast furnace operation by comparing the operating state and the shape of the burden pile.

An example based on this idea is JP-A-59-50.
102, the deposition layer of the charge in the furnace radial direction is calculated by calculating the distance from the furnace inner wall to the mountain part, the deposition angle of the charge layer deposition slope on the furnace center side by θ1, and the furnace wall. When the deposition angle of the side charge layer deposition surface is θ2, L: 0.5 to 1
．． 5m and θ of coke layer: θ2 at 25° to 35°:
Within ±lO'', θ of ore layer: θ2 between 20' and 30°
There is a disclosure that the in-furnace deposition shape that corresponds to the target gas flow distribution can be maintained by controlling the gas flow to be within ±io'.

On the other hand, it is a well-known operation method to divide the charged raw material according to particle size and charge the fine-grained raw material to the surrounding area of the furnace. The publication proposes a method of improving the gas utilization rate or producing low (Si) pig iron by dividing the charged raw material by particle size and charging the fine grained raw material around the furnace.

(Problem to be Solved by the Invention) The above-mentioned Japanese Patent Application Laid-open No. 59-50102 describes the management of the deposition shape of the raw material input into the furnace within a predetermined range, and in particular, the distance ML from the furnace inner wall to the mountain portion is 0. It is said that stable blast furnace operation can be maintained by controlling the coke within the range of . (It has been found that there is no region within the above range disclosed in Publication No. 1102 in which stable operation of the blast furnace is possible.

That is, as shown in Fig. 7, when L is in the range of 0.5 to 1.5 m, the coke inclination angle θ1 becomes more than 35'', making the coke deposition state unstable and causing finger-scale fluctuations. I found out.

On the other hand, in blast furnace operations in which fine-grained raw materials are charged into the periphery of the blast furnace, the deposition state of fine-grained raw materials is not stable, and if the fine-grained raw materials flow into the center of the furnace, the central gas flow will be extremely deteriorated. This may cause ventilation obstruction, or if fine grain raw materials are deposited in place III, unreduced and unmelted ore may fall to the lower part of the furnace, which may cause operational fluctuations. Therefore, it is desirable to charge fine-grained raw material widely and thinly around the furnace periphery, but in the conventional method, there is no knowledge that presents the deposition shape necessary to form such a charge shape.

(Means for Solving the Problems) The present invention aims to improve the stable operation of a blast furnace by quantitatively evaluating the gas flow distribution in the blast furnace and clarifying the relationship between it and the corresponding burden pile shape. In other words, it is possible to provide a deposition shape that can achieve the target gas flow distribution, and to provide a deposition shape of the charge that allows fine grain raw materials to be stably deposited around the furnace, thereby enabling stable blast furnace operation. (1) In a method of operating a blast furnace while controlling the gas flow in the blast furnace, the shape of coke deposition in the furnace is defined as the distance from the furnace wall to the shoulder, where R is the distance from the furnace wall to the shoulder. A blast furnace operation method characterized by controlling R to exceed 1.5 m, (2) A method of operating a blast furnace while controlling the gas flow in the blast furnace, in which the deposition shape of coke and ore in the furnace is When R is the distance from the furnace wall to the shoulder, R is controlled to exceed 1.5 m, and the ore is divided by particle size and fine-grained ore is charged to the area around the furnace. The main points of this paper are the following: blast furnace operating methods.

The present invention will be described in detail below based on the drawings.

Generally, blast furnace operation is controlled by the gas flow distribution within the furnace, and maintaining operation at the optimum point leads to long-term stable operation.

As a means of knowing the gas flow in the radial direction inside the furnace, there is a device that measures the radial gas component using a shaft sonde, etc. From this measurement data, the reduction rate distribution in the radial direction inside the furnace can be calculated, and it is possible to calculate the distribution of the reduction rate in the radial direction inside the furnace. Gas flow velocity distribution can be calculated.

The gas flows flowing through each part divided into three concentric circles in the radial direction of the furnace are defined as the center gas flow distribution, intermediate gas flow distribution, and peripheral gas flow distribution, respectively, and the data of blast furnaces with different internal volumes are shown in Figure 1. As a result of organizing it into a triangular diagram, the gas flow distribution that is stable for operation regardless of the size of the blast furnace is that the center gas flow distribution is 25 to 35% and the intermediate gas flow distribution is 30±.
2%, and the ambient gas flow distribution was found to be in the range of 35-45%.

Among these, the stable range of intermediate gas flow distribution is particularly narrow, and achieving this is an absolute condition for stable operation. In other words, the lack of intermediate gas flow indicates that the ventilation resistance in the middle part of the blast furnace is large and the reduction and rising of the raw material are poor.If this part descends to the softened cohesive zone, the cohesive zone will enlarge due to the delay in melt dripping. This causes deterioration of ventilation and disturbance of charge descent. On the other hand, an excessive flow of intermediate gas inevitably results in insufficient gas flow in the center and periphery, causing troubles such as a drop in furnace core temperature or an inactive state in the lower part of the furnace.

Next, in order to compare the shape of the charge deposition with the gas flow distribution, as shown in Fig. 2, from the vicinity where the inclination angle of the deposit surface is less than 15° from the furnace center toward the furnace wall, to the furnace wall. is called 1 terrace 0, and its length is defined. That is, when the extension line of the slope on the furnace center side from the terrace is a1 and the extension line of the deposition surface of the terrace is b, the distance between the intersection point where a and b intersect and the furnace wall is the terrace length R. Further, the angle between the a-line and the horizontal line was defined as the inclination angle θ.

The relationship between intermediate gas flow distribution and coke terrace length is shown in the third factor. As shown in the figure, the intermediate gas flow distribution increases as the terrace length increases, but this is because the longer the terrace length becomes, the smaller the coke inclination angle becomes, and the coke deposition shape becomes more stable. This is because the amount of coke that is broken down is reduced, and as a result, Ore/Coke in the middle portion is reduced.

From FIG. 3, it was found that in order to ensure an intermediate flow of 30%, a coke deposition shape such that the coke terrace length exceeds 1.5 rn is required.

In addition, in the method of charging fine raw materials into the surrounding area of the blast furnace,
As shown in Figure 4, by changing the amount of fine-grained raw material used, the peripheral gas flow distribution can be adjusted without changing the layer thickness of coke and raw material in the peripheral area, and the target gas flow distribution described above can be adjusted. It was found to be an effective means of maintenance.

In addition, the average particle size difference Δp between coarse particles and fine particles as shown in Table 1
When using fine grain raw materials with p of 4 to 15 mm,
As shown in Figure 5, the amount of charge per batch including fine raw materials is 1696 of the total charge amount of all raw materials per batch.
When the following conditions are met, it becomes a stable operation area.

Table 1 In addition, when using fine grain raw materials in the above method,
In order to stably deposit fine grain raw materials in the peripheral area, 1.
It has also been found that a terrace length of ore (coarse grain raw material) exceeding 5 m is required.

(Embodiment) FIG. 6 shows an embodiment of the present invention in a large blast furnace having an internal volume of 40 B3 rri.

As shown in the figure, changing the terrace length of coke and ore (coarse grain raw material) changes the number of finger-shape disturbances.
When the coke terrace exceeded 1.5 m in length, the number of finger-shaft disturbances decreased significantly, making it possible to continue stable operation. When the terrace length of coke and ore (coarse raw material) was further extended, the terrace length was 2 for coke.
-5 ms ore (coarse grain raw material) was able to continue stable operation until reaching 211rr1.

In addition, from the 8th period when the ore terrace exceeded 15 m, fine grain raw material equivalent to 18% of the total raw material charge was charged to the surrounding area of the furnace, but it was stably deposited on the ore (coarse grain raw material) terrace. I confirmed that there is.

(Effects of the Invention) According to the present invention, it has become possible to continue stable operation by creating a burden pile shape in which the coke terrace exceeds 1.5 m.

Furthermore, by extending the ore (coarse grain raw material $4.) terrace, fine grain raw material was stably deposited around the furnace, making it possible to continue stable operation.

[Brief explanation of the drawing]

Fig. 1 is a triangular diagram of the gas flow distribution in the furnace according to the present invention, Fig. 2 is a definition diagram of the in-furnace deposition shape according to the present invention, and Fig. 3 is a diagram showing the relationship between the in-furnace deposition shape and the in-furnace gas flow distribution. , Figure 4 is a diagram showing the relationship between the amount of fine raw material used and peripheral gas flow distribution, Figure 5 is a diagram showing the relationship between the usage rate of fine raw material and fuel ratio, and Figure 6 is an example of the present invention. FIG. 7 is a diagram showing the relationship between the distance from the furnace inner wall to the peak and the inclination angle of coke. Fig. 3 Coke Terrace Long Beg [Scrap] Fig. 4 Detailed Comparison Et/c＾）

Claims (2)

[Claims] (1) In a method of operating a blast furnace while controlling the gas flow in the blast furnace, the coke deposition shape in the furnace is set so that R is greater than 1.5 m, where R is the distance from the furnace wall to the shoulder. A blast furnace operating method characterized by the following: (2) In a method of operating a blast furnace while controlling the gas flow in the blast furnace, the shape of the coke and ore deposits in the furnace is 1.5 m each, where R is the distance from the furnace wall to the shoulder. This blast furnace operating method is characterized by controlling the ore to exceed 100 yen, dividing the ore by particle size, and charging fine ore to the surrounding area of the furnace.