JPH06172830A - Operation of blast furnace - Google Patents

Abstract

PURPOSE:To prevent the thermal damage of equipment caused by high temp. in the furnace top gas by adjusting oxygen enriching ratio in hot blast and blowing quantities of pulverized coal and iron oxide raw material, at the time of blowing the pulverized coal and the iron oxide-containing powdery raw material together with oxygen- enriching hot blast from a tuyere in a blast furnace. CONSTITUTION:At the time of reducing the production cost of molten iron, by using the air enriched with the oxygen for the hot blast blown from the tuyere at the time of operating the blast furnace and blowing the pulverized coal and the iron oxide- containing powdery raw material of powdery iron ore, etc., from the tuyere together with the hot blast to improve the productivity of the blast furnace, when raising the temp. of furnace top gas, the furnace top part is thermally damaged and the maintenance cost for the equipment is increased. In order to prevent the temp. raising in this furnace top gas, by adjusting the oxygen-enriching ratio in the hot blast or adjusting the blowing quantity of the iron oxide-containing powdery raw material or the pulverized coal, the temp. of the exhaust gas discharged from the furnace top part is held at <=300 deg.C to prevent the equipment of the raw material charge device, etc., at the furnace top part from receiving the thermal damage, and the molten iron is produced in excellent working ratio and with good productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is a stable and efficient operation in a blast furnace operation in which a powder containing pulverized coal and iron oxide is blown to prevent an excessive rise in the temperature level of the furnace top and the upper part of the shaft. The operating method to achieve

[0002]

2. Description of the Related Art An operating method for blowing iron oxide or reduced iron together with pulverized coal into a blast furnace from a blast tuyere to reduce Si in pig iron is proposed in, for example, Japanese Patent Publication No. 58-56721. In order to achieve a stable and efficient operation state of the blast furnace and maintain the furnace top equipment, it is important to maintain and manage the temperature of the furnace top below a certain level. However, when iron oxide or reduced iron is blown into the blast furnace together with pulverized coal, the temperature at the top of the furnace rises, which causes problems in operation and facility management.

[0003]

DISCLOSURE OF THE INVENTION The present invention provides a method for operating a blast furnace in which powder containing pulverized coal and iron oxide, which prevents the temperature of the furnace top from rising, is blown from the blower tuyere.

[0004]

Means for Solving the Problems The gist of the present invention is to perform oxygen enriched air blowing in a blast furnace operation in which powder containing pulverized coal and iron oxide is blown from a blast tuyere, and adjust the enrichment rate to adjust the furnace top. It is a method of operating a blast furnace, which is characterized in that the temperature is kept within a certain control range. Further, instead of / in addition to the oxygen-enriched blast, either or both of the powder injection amount and the pulverized coal injection amount of the powder containing iron oxide can be adjusted to maintain the furnace top temperature at a constant control value range. .

The present invention will be described in detail below. In blast furnace operation in which powder containing pulverized coal and iron oxide is blown from the blast tuyere, it was found that oxygen enriched blasting is effective for preventing the rise of furnace top temperature. Generally, when the amount of powder containing iron oxide, that is, iron-containing powder or pulverized coal blown from the tuyere is increased, the amount of iron ore and coke supplied from the furnace top per ton of pig iron decreases. The gas discharged from the blast furnace exchanges heat with these charges and the temperature drops and is discharged outside the furnace.However, if the amount of iron-containing powder or pulverized coal blown from the tuyere is increased, As a result, the amount of raw fuel charged from the top of the furnace is relatively reduced, so that the temperature of the gas does not drop sufficiently and is discharged outside the furnace at a high temperature.

However, in terms of equipment maintenance, the furnace top temperature is 3
It is necessary to maintain the temperature below 00 ° C, preferably below 200 ° C. Further, from the viewpoint of operation efficiency, it is desirable that the furnace top temperature is lower because the sensible heat is reduced by carrying away the gas. According to the present invention, the nitrogen ratio is reduced by enriching oxygen during air blowing and replacing it with air, and the amount of gas rising from the lower part of the furnace is reduced, and the relative ratio of the top charge to the gas is reduced. Can be reduced to the same level as before oxygen enrichment.

The iron oxide-containing powder in the present invention, that is, iron-containing powder, specifically refers to powdered ore, iron and steel dust, iron scale powder, and the like, and these are reduced to give a mixed state of metallic iron and iron oxide. Including powder that is. An increase in the oxygen enrichment rate reduces the amount of gas per ton of pig iron from the bottom of the furnace and is therefore effective in lowering the furnace top temperature, and an excessive increase in the furnace top temperature due to the injection of pulverized coal and iron-containing powder Can be suppressed. In addition, productivity can also be increased by increasing the oxygen enrichment rate. Further, when the powder blowing amount and the pulverized coal blowing amount of the powder containing iron oxide decrease, the raw fuel charged from the furnace top increases, so the furnace top temperature decreases.

[0008]

EXAMPLES Examples of the present invention are shown in Table 1 together with comparative examples.

[0009]

[Table 1]

Cases 1 and 2 are examples of lowering the furnace top temperature and increasing the tap ratio due to oxygen enrichment. In case 3, instead of enriching with oxygen, the blowing of pulverized coal from the tuyere was stopped and the amount of iron-containing powder was adjusted. Case 4 shows Example B and Comparative Example in which the pulverized coal ratio was the same and oxygen enrichment was performed. In both cases, the furnace top temperature was maintained at 200 ° C. or lower and the tap ratio increased in the case of the present invention.

[0011]

Industrial Applicability According to the present invention, it is possible to blow iron-containing powder and pulverized coal without excessively raising the temperature level at the top of the blast furnace and the upper part of the shaft, so that stable and efficient blast furnace operation can be achieved. The effect is great.

Claims (2)

[Claims] 1. In a blast furnace operation in which a powder containing pulverized coal and iron oxide is blown from a blast tuyere, oxygen-enriched air is blown and the enrichment rate is adjusted to maintain the furnace top temperature within a certain control range. Blast furnace operating method characterized by. 2. In place of / in addition to the oxygen-enriched blast, one or both of the powder injection amount and the pulverized coal injection amount of the powder containing iron oxide are adjusted to bring the furnace top temperature to a constant control value range. The method for operating a blast furnace according to claim 1, characterized in that the operation is carried out.