JPH06228615A - Method for charging coke into blast furnace - Google Patents

Abstract

PURPOSE:To uniformalize flowing speed distribution of gas in a furnace and to stabilize the furnace condition and to improve the productivity of the blast furnace by controlling formed coke ratio in the consumed coke in a specific range at the time of operating the blast furnace and suitably adjusting the inclining angle of the charged coke. CONSTITUTION:At the time of alternately charging raw materials of the coke for heat source and reducing agent and iron ore, sintered ore, slag-making agent, etc., as layer state from the furnace top part in the blast furnace, the coke is used with the mixed material of the ordinary coke and the formed coke. By making the wt. ratio of the formed coke in the mixed material in the range of 5-10%, the inclining angle of the coke layer in the furnace is adjusted from 30-35 deg. to 26-31 deg.. As the layer thickness distribution of the coke layer and the other raw material layer in the radial direction in the blast furnace is uniformalized, the flowing speed distribution of the lifting gas at each part of the coke layer is uniformalized. The unstable furnace condition in the blast furnace caused by blow-by and the local increase of ventilating resistance is prevented and the production efficiency of the molten iron in the blast furnace is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for achieving stable operation of a blast furnace using a molding coke.

[0002]

2. Description of the Related Art In a blast furnace, iron raw material and coke are alternately charged from the top of the furnace, and air is blown into the blast furnace from the tuyere to burn the coke. The reducing gas generated by the combustion of coke, and further the reducing gas by the combustion of pulverized coal or the like blown from the tuyere together with the air heats and reduces the iron raw material to melt and drop it. Therefore, from the viewpoint of reduction / melting of the iron raw material, it is important to properly control the radial distribution of the reducing gas. Since the distribution of the reducing gas in the radial direction is determined by the ventilation resistance distribution of the charging material, it is important to control the layer thickness ratio distribution of ore and coke, which determines the ventilation resistance distribution of the charging material.

One of the important factors that determines the layer thickness ratio distribution of ore and coke is the inclination angle of ore and coke, which are determined by the physical property values (shape, grain size, etc.) of ore and coke. It was almost impossible to control because it was difficult to control. FIG. 2 shows the measured values of the inclination angle immediately after the charging of the coke by the profile meter installed at the top of the blast furnace. Although there is a change in the tilt angle for each measurement, it can be seen that the tilt angle changes considerably every day or every season. As the coke inclination angle changes, the layer thickness distribution of coke and ore changes, so the gas velocity distribution in the radial direction changes.

This change may be due to the control accuracy of the charging device (the accuracy of the setting position of the movable armor in the case of the bell type blast furnace, the accuracy of the setting angle of the turning chute in the case of the bellless type blast furnace). In many cases, it is caused by changes in the physical properties of coke (shape, particle size, etc.) and water content. However, in this case, there is no suitable control means, and when the change in the coke inclination angle is large, the charging pattern is changed so that the layer thickness ratio distributions of the coke and the ore are matched as much as possible. However, in this case, it tends to be a trial and error action, and it takes too much time to obtain an appropriate charging pattern, so the inclination angle of the coke may change before an appropriate charging pattern is found, The action is likely to be too late.

If the gas flow velocity distribution changes largely for a long time, gas blow-through occurs or the reduction efficiency is lowered to make the operating state unstable, and the fuel ratio increases. There is a high possibility that the pig iron amount will decrease.

As a conventional technique for charging a molding coke into a blast furnace, as disclosed in Japanese Patent Laid-Open No. 56-41109, a molding coke having a size of 60 to 120 mm is crushed by a crusher into a jagged surface shape. 25-6
As disclosed in Japanese Unexamined Patent Publication No. 1-31909 and a technique of using a molded coke having a particle size adjusted to 0 mm, charging is performed by charging a pellet or molding coke having a nearly spherical shape before charging a fine-grain raw material. There is a technique for reducing the inclination angle of an object to suppress the inflow of the fine-grain raw material into the central portion.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
The technique disclosed in Japanese Patent No. 9 does not particularly mention a charging method (for example, layered charging, mixed charging) of crushed and sized molded coke, and the technique disclosed in Japanese Patent Application Laid-Open No. 1-31909. Is a technique of suppressing the inflow of the fine grain raw material into the central portion by utilizing pellets or molding coke having a small inclination angle, but is not a technique specifically aimed at controlling the inclination angle of coke.

Among the above problems, the present invention minimizes the change in the gas flow velocity distribution due to the change in the inclination angle due to the change in the physical property values (shape, particle size, etc.) of coke,
The purpose is to stabilize the operation of the blast furnace by eliminating the phenomenon that the operating state becomes unstable due to the occurrence of gas blow-through and the reduction efficiency.

[0009]

Means for Solving the Problems The present invention is to solve the above problems and, when charging coke as a reducing material into a blast furnace, the total amount of coke which is the sum of normal coke and molded coke is used. , Molded coke by weight% 5-10
It is a method for charging coke into a blast furnace, which is characterized in that 0% is mixed and charged into the blast furnace. Further, the feature here is that the inclination angle of the charging coke is adjusted within the range shown in FIG. 1 by the ratio of the normal coke and the molding coke.

Here, the normal coke means a coke produced in a conventional chamber furnace type coke oven without specially molding the coal, and the forming coke forms the coal in a certain shape in advance and moves countercurrently. It means coke produced in a layered continuous furnace or a conventional chamber furnace type coke oven. Further, the inclination angle is a range excluding the central part (usually within a range of 1 m from the center) and the peripheral part (usually within a range of 1 to 2 m from the furnace wall) in the surface deposition shape of the charge at the furnace top. Means the maximum or average of the inclination angles of.

[0011]

According to the present invention, when the normal coke and the molded coke are mixed and charged, the inclination angle of the charged coke is adjusted by the ratio of the normal coke and the molded coke to control the layer thickness ratio distribution of the coke and the ore. This stabilizes the gas flow velocity distribution in the radial direction. That is, FIG. 1 shows the relationship between the ratio of the molding coke to the total coke amount (% by weight) and the inclination angle when the normal coke and the molding coke are mixed. The inclination angle is the maximum or average value of the inclination angles in the range excluding the central portion and the peripheral portion in the blast furnace.

According to this, the inclination angle of the coke decreases as the proportion of the forming coke increases, and the inclination angle of the coke can be controlled by using this relationship. It is considered that this is because the additivity of the inclination angle due to mixing is established between the normal coke having a high inclination angle and the molded coke having a low inclination angle. Generally, the problem that the inclination angle of the coke changes is that the inclination angle becomes large, and in that case, the inclination angle of the coke can be controlled by the technique according to the present invention.

The range of the mixing ratio of the molding coke is 5-10.
The reason for excluding 0% and less than 5% is that when the mixing ratio of the molding coke is as small as less than 5%, the mixing state with the normal coke is difficult to be uniform, and it is difficult to adjust the inclination angle of the coke layer. .

Further, in FIG. 1, when the mixing ratio of the molding coke is 5%, the proper range of the inclination angle of the charging coke is 30 ° to 35 ° because the coke is in the range of the inclination angle. This is because a sharp central flow is formed by the flow of ore with a smaller inclination angle into the center of the blast furnace, and the blast furnace is stabilized. Therefore, when the inclination angle of the normal coke increases due to changes in the physical property values (shape, particle size, etc.) of the normal coke, the coke layer is adjusted by adjusting the mixing ratio of the molded coke based on the relationship of FIG. It is possible to control the inclination angle of 30 to 35 °.

Here, the mixing ratio of the molding coke is 100.
%, The proper range of the inclination angle of the charging coke is 26 °
The reason why the angle is set to 31 ° is that the inclination of the ore is close to that of the ore, so that the flow of the ore into the center is suppressed, and the O /
This is because C becomes small and the central flow is secured. This method is applied, for example, when using an ore (for example, fine-grained sintered ore, etc.) having a small inclination angle and easily flowing into the center.

As a method for mixing the chamber furnace coke and the molded coke, the chamber furnace coke amount and the molded coke amount determined from the set value of the mixing ratio are respectively measured from the chamber furnace coke bin and the molded coke bin. It is relatively easy to cut out and place it on the belt and mix it in the surge hopper.

[0017]

【Example】

Example 1 The coke tilt angle control method of the present invention was carried out in a blast furnace having an internal volume of 4400 cubic meters. FIG. 3 shows the mixing ratio of the molded coke before and after the method of the present invention, the coke inclination angle, and the relative O / C in the peripheral portion (the weight ratio of the layer thickness ratio of ore and coke is converted into the average ore and coke at the time of charging). Divided by the weight ratio of the following, hereinafter referred to as relative O / C), relative O / C of the central part
5 is a graph showing the transition of the number of slips.

In conventional blast furnace operation, when the coke inclination angle increases due to changes in the physical property values (shape, grain size, etc.) of normal coke, the relative O / C at the peripheral portion decreases and the relative O / C at the central portion decreases. An increase in C is observed and the number of slips is increasing. With the implementation of the coke tilt angle control method of the present invention, the fluctuation of the coke tilt angle was significantly reduced, the fluctuation of the relative O / C between the central portion and the peripheral portion was also reduced, and the number of slips was significantly reduced. As a result, as shown in Table 1, the reduction efficiency (shaft efficiency) was improved, and the amount of pig iron could be increased by reducing the fuel ratio.

[0019]

[Table 1]

Example 2 The coke inclination angle control method of the present invention was carried out in the same manner as in Example 1 when using a fine-grained sintered ore, which was apt to flow into the center of the ore layer. FIG. 4 is a graph showing changes in the ratio of fine-grained sinter ore, the mixing ratio of molded coke, the coke inclination angle, the relative O / C at the central portion, and the number of slips before and after the method of the present invention.

The relative O / C in the central part increased with the increase in the ratio of fine-grained sinter and the number of slips increased, but the inflow of fine-grained sinter into the central part was suppressed by the method of the present invention. The relative O / C at the central part decreased and the number of slips decreased. As a result, as shown in Table 2, fine-grained sintered ore 30
% Even when used, the reduction efficiency (shaft efficiency) did not decrease, and the fuel ratio and amount of tapping could be maintained at about the same level as before the use of fine-grained sintered ore.

[0022]

[Table 2]

[0023]

According to the present invention, the coke inclination angle is controlled to fall within a predetermined range by charging the molding coke in a certain ratio into the normal coke, and the coke inclination angle changes according to the change. It is possible to prevent changes in the gas flow velocity distribution in the radial direction and an increase in slip, and as a result, stable operation of the blast furnace can be maintained. Further, the present invention ensures a central flow even when using a fine-grained sintered ore that easily flows into the center,
It is an effective technology that can maintain stable operation.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the ratio of molded coke in all cokes and the coke inclination angle.

FIG. 2 is a graph showing changes in coke tilt angle measured by a profile meter installed at the top of the blast furnace.

FIG. 3 shows changes in the mixing ratio of the molded coke before and after the method of the present invention, the coke inclination angle, the relative O / C at the peripheral portion, the relative O / C at the central portion, and the number of slips when the inclination angle of the coke layer changes. Graph showing

FIG. 4 shows the mixing ratio of the molding coke before and after the method of the present invention when using 30% of fine-grained sinter, coke inclination angle, relative O / C at the peripheral portion, relative O / C at the central portion, and the number of slips. Graph showing changes

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Oda 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corp. Kimitsu Steel Co., Ltd.

Claims (2)

[Claims] 1. When the coke is charged into a blast furnace as a reducing material, the molding coke is 5 to 100% by weight based on the total amount of coke, which is the sum of the normal coke and the molding coke.
A method for charging coke into a blast furnace, which comprises mixing and charging the blast furnace. 2. The method for charging coke into a blast furnace according to claim 1, wherein the inclination angle of the charging coke is adjusted within the range shown in FIG. 1 by the ratio of the normal coke and the molded coke.