JPH0565516A - Method for operating blast furnace - Google Patents

Abstract

(57) [Summary] [Object] The present invention provides a method for removing unburned char in a blast furnace core. [Composition] In a blast furnace with a large amount of pulverized coal blowing operation, H ₂ O, CO ₂ or a gas containing these is blown into the furnace core through a pipe inserted from outside the furnace during operation to remove unburned char in the furnace core. Remove to increase the upper limit of pulverized coal injection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention aims to secure stable blast furnace operation by blowing out a large amount of pulverized coal from tuyere of a blast furnace when unburned char is deposited on the core of the furnace. It is what

[0002]

2. Description of the Related Art In blast furnace operation, a technique of blowing fuel from tuyere to replace coke charged from the top of the furnace was developed (Japanese Patent Publication No. 40-23763) to reduce hot metal production costs and improve productivity. ing. Pulverized coal, petroleum, heavy oil, naphtha and the like are used as the fuel, but recently, pulverized coal injection is mainly used in terms of price.

The pulverized coal blown from the tuyere burns in the area near the tuyere in the raceway, the carbon content becomes CO ₂ , and H ₂ O is also generated due to the organic matter partially contained.
Further, when oxygen disappears in the area outside the raceway, CO and H ₂ are formed by reaction with coke, and these are supplied as reducing gas into the furnace.

That is, the carbon content in the pulverized coal is once completely oxidized to CO ₂ and CO is produced by the solution reaction. That is, the amount of oxygen required to finally form CO gas is required in the course of the reaction, and the amount of air required for complete combustion of the pulverized coal, that is, the air ratio needs to be 1 or more. Therefore, if the blowing of the pulverized coal increases, the combustion efficiency of the pulverized coal decreases as the air ratio decreases. Then, when the air ratio falls below the vicinity of 1, the amount of unburned char generated in the raceway increases rapidly. Blast furnace fuel ratio is 500
The blowing amount of the pulverized coal that gives an air ratio of 1 at kg / t-pig is about 170 kg / t-pig, which is the limit of the blowing amount.

[0005]

Since it is cost effective to replace coke with pulverized coal as much as possible, attempts have been made to increase the amount of pulverized coal blown. However, if a large amount of the charcoal is blown in beyond the above-mentioned limit, the unburned char generated will be deposited on the core of the furnace, impairing air permeability and liquid permeability. For this reason, the amount of tapped iron is reduced, which is not profitable.
The present invention is intended to solve the above problems and eliminate the adverse effect of the accumulation of the above-mentioned unburned char on the core portion of the furnace, thereby making it possible to blow a large amount of pulverized coal.

[0006]

Means for Solving the Problems The present invention is intended to solve the above problems, and in a blast furnace operating method in which pulverized coal is blown together with hot air from the blast tuyere of a blast furnace, H ₂ O, CO ₂ or A gas containing these is blown into the furnace core through a tube inserted from outside the furnace to remove unburned char in the furnace core. Alternatively, during operation, at least one of H ₂ O and CO ₂ and O ₂
A gas containing and is blown into the furnace core through a tube inserted from outside the furnace to remove unburned char in the furnace core and to remove O ₂ and H ₂
The feature is that the balance of the heat balance is properly maintained by the ratio of O and CO ₂ . Further, as a means for these, an opening is provided in the belly of the blast furnace, a lance is inserted, and gas is blown in.

[0007]

The present invention significantly increases the pulverized coal ratio, for example, 2
The operation is performed with a blowing amount of 00 kg / t-pig or more, whereby the unburned char accumulated on the core of the furnace is removed from time to time, for example, periodically during the operation.

As a means for this, gas is blown into the core of the furnace during operation by a pipe inserted from the outside of the blast furnace to react with the unburned char and remove it. As gas, H ₂ O (steam), C
O ₂ or a gas containing these, for example, hot-blast stove exhaust gas or the like is also used. Since H ₂ O and CO ₂ remove carbon by an endothermic reaction as shown by the following chemical formula, it is preferable to use heating means together.

H ₂ O + C = CO + H ₂ −28.4 (kcal / mo
l) CO ₂ + C = 2CO-38.2 (kcal / mol)

As heating means, plasma heating may be used in addition to the generally used combustion heat. In the case of plasma heating, the plasma torch itself can also serve as a gas blowing lance described later.

The present invention is applied to periodically remove unburned char in a normal operating condition, and to heat when the core cools and an inactive portion is formed. is not. Therefore, the method of unnecessarily heating undesirably destroys the heat balance in the furnace.

Therefore, although the unburned char is removed, it is preferable that the thermal condition is such that the balance is balanced. As a method for balancing the heat balance, in addition to the method for heating the above-mentioned gas, a method for balancing by the composition of the gas itself can be used. That is, O ₂ reacts with carbon to generate heat as shown in the following formula.

O ₂ + 2C = 2CO + 58.8 (kcal / mol)

Therefore, it is possible to balance the heat balance by adding O ₂ or air to the gas containing H ₂ O or CO ₂ . For example when using a gas containing between H ₂ O and O _2, because the amount of heat generated O ₂ 1 mole per is approximately twice the amount of heat absorption per H ₂ O1 moles, the ratio of between H ₂ O and O ₂ 2 to 1
If so, unburned char can be removed without thermally affecting. Actually, when the temperature of the gas to be fed is taken into consideration, when the temperature is low, the amount of O ₂ may be increased to increase heat generation.

As a gas blowing means, a blowing lance is inserted from the tuyere, between the tuyere, on the tuyere, and the furnace belly to the core of the furnace. FIG. 1 is a sectional view of a part of the blast furnace 1 showing this situation. In recent years, a technique for inserting a sonde from a tuyere or the like has been developed, but as shown in FIG. 1, the present invention inserts a water-cooling blow-in lance 6 from an opening provided in advance by the same means as this. It is to blow.

Of these, when the blowing lance 6 is inserted from the tuyere 2, the lance is inserted through the high temperature portion of the raceway, so the blowing time is restricted by the durability of the lance, but existing equipment can be used. There is an advantage that there is no need to newly provide an opening. Further, a method (not shown) in which openings are provided between the tuyere is preferable because the high temperature portion of the raceway can be avoided. However, the space between the tuyere is the thickest part of the iron shell of the blast furnace due to strength problems, and there is the problem that it is quite difficult to provide openings. For this reason, there is also a method (not shown) of providing an opening on the upper part of the tuyere, but this part has an annular pipe 7 and a blower branch pipe 8 for blowing the tuyere, which may be an obstacle, and thus the blowing lance There is a case where it is difficult to have equipment.

From these points, it is most preferable to provide an opening in the furnace belly 3. As shown in FIG. 1, the blowing lance 6 is inserted obliquely downward from the furnace belly 3 until reaching the furnace core 4. According to this method, although the distance to the furnace core 4 is slightly long, the lance can reach the furnace core without passing through the high temperature part in the middle, and the work can be continued for a long time preferably in terms of durability of the lance.

[0018]

EXAMPLES Examples will be described below with reference to Table 1.

[Table 1]

In a blast furnace with an internal volume of 3900 cubic meters, the amount of pulverized coal blown was changed to test the effect of blowing gas into the furnace core by a lance. Gas blowing was performed during operation by providing an opening in the furnace belly 3 and inserting the lance 6 as shown in FIG. The blowing time was once for 15 minutes, and the locations were sequentially changed at six locations around the blast furnace. The gas is blown into one place once a day.

Comparative Example 1 is a standard condition, in which the amount of pulverized coal blown is 150 kg / t-pig and normal operation is performed without blowing gas into the furnace core. In Examples 1 to 4, the amount of pulverized coal blown was increased to 200 kg / t-pig and the unburned char in the furnace core was removed by blowing gas. In Examples 1 to 3, the gas containing no O ₂ was heated to a high temperature, but in Example 4, the heating temperature of the gas was lowered by introducing air and utilizing the exothermic reaction of O ₂ . In these examples, the coke substitution ratio by the pulverized coal does not change and the fuel ratio does not increase. In addition, the amount of tapped metal is good. On the other hand, in the comparative example 2 in which the amount of pulverized coal blown was increased to 200 kg / t-pig, but gas was not blown into the furnace core, the fuel ratio tended to increase and the amount of tapped metal tended to decrease.

Further, the amount of pulverized coal blown is 250 kg /
Although the amount was increased to t-pig, when gas was blown into the furnace core as seen in Examples 5 to 7, there was almost no increase in the fuel ratio as in Examples 1 to 4, and the amount of tapped metal was increased. Is also going well. Note that Examples 5 and 6 are Examples 1 to 3.
An example using a gas containing no O ₂ as in the above, and Example 7 is an example using a gas containing O ₂ as in Example 4. On the other hand, in Comparative Example 3, the amount of pulverized coal blown was increased to 230 kg / t, but unburned char was accumulated because gas was not blown into the core, which impaired air permeability and liquid permeability of the core. As a result, the fuel ratio increases and the amount of tapping metal decreases.

[0022]

In the operation of the blast furnace, unburned char accumulated on the core of the furnace when the amount of pulverized coal blown from the tuyere is increased can be removed by the method of the present invention during the operation. As a result, the amount of pulverized coal injected can be increased without deteriorating the furnace condition, the amount of coke used can be reduced, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for blowing gas into a furnace core according to the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hisaro Kamiyama 5-3 Tokai-cho, Tokai-shi, Aichi Nippon Steel Co., Ltd. Nagoya Steel Works

Claims (3)

[Claims] 1. In a blast furnace operating method in which pulverized coal is blown together with hot air from a blast tuyere of a blast furnace, H
A blast furnace operating method characterized by removing unburned char in the furnace core by blowing ₂ O, CO ₂ or a gas containing these from the outside of the furnace through a tube inserted into the furnace core. 2. In a blast furnace operation method in which pulverized coal is blown together with hot air from a blast furnace tuyere, sometimes H
Gas containing at least one of ₂ O and CO ₂ and O ₂ is blown into the furnace core through a tube inserted from outside the furnace to remove unburned char in the furnace core and to remove O ₂ and H ₂ O and CO ₂ . The blast furnace operating method is characterized by maintaining a proper balance of heat balance depending on the ratio. 3. The blast furnace operating method according to claim 1, wherein an opening is provided in the blast furnace belly, a lance is inserted, and gas is blown into the blast furnace.