JPH05239513A - Raw material charging method of blast furnace - Google Patents

Abstract

PURPOSE:To eliminate trouble at the operation of the blast furnace whose type is of an auxiliary fuel blowing-in from tuyere. CONSTITUTION:When a weight ratio of ore to coke quantity charged from a furnace top exceeds five at the operation of the blast furnace where type is of an auxiliary fuel blowing-in from tuyere, change in the lapse of time of the coke grain size charged into blast furnace from a furnace top bunker is adjusted to charge a coarse grain coke into the center part of the blast furnace.

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 for a blast furnace, and particularly to a suitable charge distribution and a charge distribution adjusting method for blowing auxiliary fuel such as coal or heavy oil from tuyere. It is about.

[0002]

2. Description of the Related Art In recent years, in blast furnace operation, the number of blast furnaces in which auxiliary fuel such as coal or heavy oil is blown from the tuyere for the purpose of cost reduction is increasing, but the amount of these auxiliary fuels is increased. The amount of coke charged from the furnace top decreases, and the weight ratio of the amount of ore charged from the furnace top to the amount of coke (hereinafter referred to as charging O / C) increases. At this time, if a locally high O / C portion occurs in the radial direction of the furnace, the amount of gas flowing through that portion decreases, and a reduction delay of ore occurs in the blast furnace and a melting delay of ore occurs in the cohesive zone. .. This condition deteriorates the air permeability in the lower part of the furnace during blast furnace operation.
This causes troubles such as a decrease in the temperature of the furnace core and an increase in the fluctuation of the hot metal temperature.

From the results of operation tests and various investigations in the blast furnace, it has been found that the O / C in the central part of the furnace rises as the charging O / C rises. As a means for coping with this, there is a method of charging coke into the central part of the furnace as disclosed in Japanese Patent Application Laid-Open No. 1-65209, which requires special equipment in the bell blast furnace. Even in a bellless blast furnace that requires and does not require facility modification, there is a drawback that the charging time is extended. Further, in the blast furnace operation, as disclosed in Japanese Patent Application Laid-Open No. 2-225607, there is a proper gas flow distribution in the furnace radial direction, and maintaining this proper gas flow distribution keeps stable operation. It is known to be a condition for.

[0004]

FIG. 7 shows the O / C distribution in the radial direction of the furnace according to the conventional charge distribution control method. According to the conventional method, as the charging O / C increases, the O /
The result was that C increased. FIG. 8 shows the movement of the gas flow distribution index, which is the ratio of the gas flow rates per unit area in the region divided into three equal parts in the furnace radial direction.

The appropriate gas flow distribution in the blast furnace is disclosed in
No. 225607, the central gas flow shown in FIG. 8 is 25-35%, the intermediate gas flow is 30 ± 2%, and the peripheral gas flow is 35-4.
Although the area is 5%, according to the conventional method, charging O /
The central gas flow decreases with increasing C, and when the charging O / C exceeds 5, it indicates that the central gas flow deviates from this proper region. This means that in the blast furnace operation, in the short term, the phenomenon of deterioration of air permeability due to insufficient central gas flow, the phenomenon of rise of radiant heat from the furnace wall due to the increase of peripheral gas flow, and the reduction of ore in the central part in the long term It also suggests that there is an adverse effect of inactivating the furnace core due to melting delay.

[0006]

The present invention has been made to solve the above-mentioned problems of the prior art. In the blast furnace operation in which auxiliary fuel is blown from the tuyere, the amount of ore and coke charged from the top of the furnace. When the weight ratio of the amount exceeds 5, the change in particle size of the coke charged into the blast furnace from the top bunker is adjusted over time, and coarse grain coke is charged into the center of the blast furnace. The raw material charging method is the main point.

[0007]

The present invention will be described below with reference to the drawings. Figure 5
FIG. 3 is a diagram showing a furnace top charging device in a blast furnace in which the present invention is implemented. This apparatus can adjust the deposition shape in the upper hopper 1 by the tiltable upper swirling chute 2, and by adjusting the deposition shape in the upper hopper, the particle size change of the raw material charged into the furnace with time is changed. It is possible to control FIG. 6 shows changes in the relative particle size of the charging coke with time using this charging device and the conventional device.
In the conventional apparatus, the change in relative particle size with time was almost uniform, but according to this charging apparatus, when the tilting angle of the upper turning chute is 0 degree, fine coke is introduced at the beginning of charging. At the end of charging, coarse coke was charged into the furnace and the tilt angle was 4
On the contrary, at 0 degree, coarse coke is inserted into the furnace at the beginning of charging and fine coke at the end of charging. In the bellless charging device, the charging into the furnace is usually such that the peripheral part of the furnace is sequentially charged into the central part of the furnace, so that the coarse coke is charged into the central part of the furnace when the tilt angle is 0 degree. It will be.

FIG. 2 shows the relationship between the amount of change in relative particle size at the beginning and end of charging in this charging device and the tilt angle of the upper turning chute. The tilt angle and change in relative particle size are shown in FIG. It turns out that the amount of is determined uniquely. According to the present invention, when the charging O / C exceeds 5, the central portion O according to the conventional method is used.
It is intended to eliminate the high C / C and the resulting decrease in the central gas flow by adjusting the coke particle size over time. FIG. 1 shows the movement of the gas flow distribution index when the particle size adjustment of the coke particle size over time is used. Even if the O / C distribution in the radial direction is the same as that of the conventional method, the tilt angle of the upper swirling chute is made small and the central gas flow is increased by charging the coarse coke into the center of the furnace.
It shows that it enters the proper gas flow distribution region. Figure 3
It shows the amount of change in particle size between the charging O / C and the start and end of charging of coke in the region of proper gas flow distribution. As the charging O / C increases, It has been found that it is necessary to increase the amount of diameter change.

[0009]

EXAMPLE FIG. 4 shows an example of the present invention and shows the central gas flow distribution index when the charging O / C rises and the air permeability of the blast furnace. Although the central gas flow decreased and the air permeability deteriorated with the increase of / C, the introduction of the present invention increased the central gas flow, improved the air permeability, and ensured stable operation. You can see that you were able to continue.

[0010]

As described above, according to the present invention, even when the O / C exceeds 5 by injecting the auxiliary fuel, it is possible to avoid the decrease of the central gas flow in the furnace and the deterioration of the air permeability, and to stabilize the blast furnace. Operation is possible.

[Brief description of drawings]

FIG. 1 is a diagram showing changes in a gas flow distribution in a furnace according to the present invention.

FIG. 2 is a diagram showing the relationship between the amount of change in relative particle size at the beginning and end of charging of coke and the tilt angle of the upper turning chute.

FIG. 3 is a diagram showing the relationship between charging O / C and the amount of change in relative particle size at the start and end of charging coke.

FIG. 4 is an operational transition diagram comparing a conventional method and the method of the present invention as an example.

FIG. 5 is a conceptual diagram of a blast furnace top charging device according to the present invention.

FIG. 6 is a diagram showing a change in relative particle size of coke charged into the furnace over time.

FIG. 7 is a diagram showing an O / C distribution in a furnace radial direction according to a conventional method.

FIG. 8 is a diagram showing changes in the gas flow distribution in the furnace according to the conventional method.

Front page continuation (72) Inventor Issei Yamaguchi 1 Kimitsu, Kimitsu City, Chiba Nippon Steel Corporation Kimitsu Works Ltd.

Claims (1)

[Claims] 1. In a blast furnace operation in which auxiliary fuel is blown from the tuyere, when the weight ratio of the amount of ore charged from the furnace top to the amount of coke exceeds 5, the coke charged into the blast furnace from the furnace bunker changes with time. A method for charging a raw material for a blast furnace, characterized in that a coarse grain coke is charged in the central portion of the blast furnace by adjusting the change in the particle size.