JPH06240315A - Method for feeding coke in bell-less blast furnace - Google Patents

Abstract

PURPOSE:To obtain the stable center gas flow even if the grain size range of ores varies and to obtain the optimum gas flow distribution by feeding a specific ratio of the total coke feed quantity per one charge into a furnace center part. CONSTITUTION:At the time of feeding the coke in a bell-less blast furnace 1, 85-90wt.% in the total coke feed quantity per one charge is spread on the whole surface of the lower layer of ore layer 2 in the radial direction in the furnace. Successively, the rest 10-15% in the total coke feed quantity is fed into the center part in the furnace 1 on the upper surface of the coke layer 3 spread on the whole surface of the lower layer of the ore layer 2. By this method, the gas flow in the center part of the furnace can be secured in the stable condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material charging method in a bellless blast furnace equipped with a distribution chute.

[0002]

2. Description of the Related Art Generally, a bellless blast furnace is constructed so that the distribution of raw materials in the radial direction of the furnace can be controlled by the combination of the inclination angle and the number of turns of the distribution chute set in advance. Then, by changing the distribution at the time of charging the raw material, the distribution of the gas flow in the radial direction of the furnace is adjusted to be optimum, and the operation of the blast furnace is stabilized and the productivity is improved.

Even in a blast furnace having a bell-type charging device, the raw material distribution control is performed to some extent by using a movable armor or the like, but the controllable range is much larger in the bell-less type.

[0004]

However, in the bellless type raw material charging device, the raw material charging time per charge is longer than that in the bell type because of the necessity of turning and tilting the distribution chute. The amount of coke flowing into the center of the furnace at the time of ore charging after charging the coke is smaller than that of the bell type.

On the other hand, the particle size distribution of the raw material formed after charging the interior of the furnace depending on the particle size range of the charged raw material is more sensitive to change in the bellless type than in the bell type. The range of this raw material particle size is
From the viewpoint of pursuing rational production cost, there is a tendency to allow a wide range, and the raw material particle size distribution in the radial direction in the bellless blast furnace tends to be unstable.

Therefore, the gas flow rate in the central part of the blast furnace becomes unstable due to the decrease in the amount of coke flowing into the central part of the furnace and the instability of the particle size distribution, which is a serious obstacle to the stabilization of the furnace condition. There is a risk of becoming.

The present invention was devised in view of the above-mentioned circumstances, and an object thereof is to ensure a stable gas flow in the central part of the furnace and also to provide a stable central gas flow even when the particle size range of the ore changes. It is an object of the present invention to provide a coke charging method in a bellless blast furnace which can obtain the above-mentioned characteristics and can improve the controllability for achieving the optimum gas flow distribution for keeping the furnace condition stable.

[0008]

In the method for charging coke in a bellless blast furnace according to the present invention, the charging of coke is 1
The weight of the total amount of coke per charge should be in the range of 10% to less than 15% in the center of the furnace.

Regarding the range of the total amount of coke charged, a method of separately charging coke in the center of the blast furnace (see Japanese Patent Laid-Open No. 60-56003) has already been introduced. In this case, it is in the range of 1.5 to 8% by weight of the total coke charging amount. In addition, a method (Japanese Patent Application Laid-Open No. 3-232912) of introducing 15 to 20% by weight of the total coke charging amount in the central part of the furnace against fluctuations in wind pressure of the blast furnace is also introduced. There is. However, both of them differ from the present invention in the range of the ratio of the coke charged in the center.

Further, in JP-A-4-6205, when the ore is mixed with coke and charged, there is an optimum range between the mixed coke amount and the coke amount charged in the center. Has been introduced. However, the present invention does not include mixed coke, and even in that case, the range of the central charging amount is different.

The coke charging method of the present invention is
By charging 10% or more and less than 15% of the total amount of coke charged per charge into the central part of the furnace, the gas flow in the central part of the furnace is secured in a stable state and the grain size of the ore A stable central gas flow is obtained even when the range varies. Further, the controllability for achieving the optimum gas flow distribution for keeping the furnace condition stable is improved.

[0012]

The method for charging coke in a bellless blast furnace according to the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 is an explanatory view showing the charging situation in the blast furnace by the coke charging method of the present invention. As shown in FIG. 1, in the coke charging method of the present invention, first, at the time of charging coke in the bellless blast furnace 1, 85 to 90% by weight of the total amount of coke charged per charge is
In the radial direction of the furnace, it is sprayed on the entire lower layer of the ore layer 2.

After that, the remaining 10 to 15% by weight of the total amount of the coke charged is charged into the central portion of the furnace 1 on the upper surface of the coke layer 3 which is spread over the entire lower layer of the ore layer 2. .

FIG. 2 shows the influence on the central gas flow distribution index when the particle size of the sintered ore in the charging ore changes, and at the same time, when the coke charging amount to the center increases, the central gas flow distribution index. This indicates that the range of change is small.

Here, if the central gas flow becomes too strong,
Since the central gas temperature becomes too high and the heat load on the furnace top equipment located directly above the center gas temperature rises, restrictions will arise from facility maintenance. Further, the deterioration of the controllability of the central gas flow distribution due to the fluctuation of the particle size of the charged ore can be suppressed by the increase of the amount of the central charging coke. There is an upper limit on the amount. Furthermore, by setting the amount of coke charged to the center to be 9 to 14% by weight of the total amount of coke charged per charge, it is possible to satisfy both restrictions from securing the central gas flow and maintaining equipment.

The central gas flow index on the vertical axis in the graph of FIG. 2 is dimensionless, and the charging sinter +25 mm ratio zero is set to 1. In this graph, the amount of coke charged in the center is >>, and the slope of the straight line is small and the change range of the central gas flow index is small in the order of ,,.

Further, the improvement of the central gas flow index is due to the addition of sinter +
It is achieved by increasing the amount of coke charged in the center without increasing the ratio of 25 mm so much that the good permeability of coke is not eliminated by the sinter, that is, the porosity is not reduced.

FIG. 3 is an explanatory diagram showing that there is an upper limit in the amount of centrally charged coke in relation to the amount of centrally charged coke and the temperature of central gas due to restrictions on equipment maintenance. Further, FIG. 4 is an explanatory diagram showing that there is a lower limit of the central charging coke amount due to the constraint on ensuring the blast furnace operation stability in the relationship between the central charging coke amount and the fluctuation of the central gas flow distribution due to disturbance. is there.

[0020]

According to the coke charging method of the present invention,
In order to charge 10% or more and less than 15% of the total amount of coke charged per charge into the central part of the furnace, the gas flow in the central part of the furnace can be secured in a stable state. In addition, even if the particle size range of the ore changes,
It is possible to obtain a stable central gas flow and improve the controllability for obtaining the optimum gas flow distribution for keeping the furnace condition stable.

1 to 4 show the case where the optimum core coke charging amount that can stably secure the central gas flow is obtained without being restricted by facility maintenance and reactor stability. It is a specific example shown. And the effect is
It is qualitatively and quantitatively expressed. That is, FIG. 1 shows the charging state of the present invention, and FIG. 2 shows the charging state of FIG.
4 shows the index (premise), and FIGS. 3 and 4 embody the effect of the present invention.

Further, in FIG. 3, the center charging coke amount ratio is 15
%, The central gas temperature rises too much (core breathability is too good), which is a problem in equipment maintenance and is not preferable.

Further, FIG. 4 shows that the center charging coke amount ratio is
If it is less than 10%, the fluctuation range of the central gas flow index (strength) becomes large due to disturbance (deterioration of core air permeability, etc.), and the reactor condition becomes unstable, which is not preferable.

[Brief description of drawings]

FIG. 1 is a schematic view showing a charging situation in a blast furnace by a coke charging method of the present invention.

FIG. 2 is a graph showing the relationship between central gas flow index and charging sinter +25 mm ratio.

FIG. 3 is a graph showing a relationship between a central gas temperature and a central charging coke amount ratio.

FIG. 4 is a graph showing the relationship between the central gas flow index fluctuation range and the central charging coke amount ratio.

[Explanation of symbols]

 1 ... Bellless blast furnace, 2 ... ore layer, 3 ... coke layer.

Claims (1)

[Claims] 1. When charging coke in a bellless blast furnace, first, 85 to 90% by weight of the total amount of coke charged per charge is sprinkled in the furnace radial direction over the entire lower layer of the ore layer. After that, the remaining 10 to 15% by weight of the total amount of the coke charged is charged into the center of the furnace on the upper surface of the coke layer sprinkled over the entire lower layer of the ore layer. Coke charging method in blast furnace.