JP2627232B2 - Blast furnace operation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION An object of the present invention is to ensure stable operation of a blast furnace by removing unburned char from the core of the furnace in the operation of blowing a large amount of pulverized coal from the tuyere of the blast furnace. It is assumed that.

[0002]

2. Description of the Related Art In a blast furnace operation, a technique of injecting fuel from tuyere to replace coke charged from the furnace top has been developed (Japanese Patent Publication No. 40-23763) to reduce hot metal production cost and improve productivity. ing. Examples of the fuel include pulverized coal, petroleum, heavy oil, naphtha, and the like. Recently, pulverized coal has been mainly used in terms of price.

[0003] The pulverized coal blown from the tuyere burns in a region near the tuyere in the raceway, the carbon content becomes CO ₂ , and H ₂ O is also generated due to organic substances contained in part.
Further, when oxygen is depleted in a region outside the raceway, CO and H ₂ are formed by reaction with coke, and this is supplied to the furnace as a reducing gas.

That is, the carbon content in pulverized coal is once completely oxidized to CO ₂ , and CO is generated by a solution reaction. That is, an amount of oxygen exceeding the amount that finally forms CO gas is required in the middle of the reaction process, and the amount of air required for complete combustion of the pulverized coal, that is, the air ratio needs to be 1 or more. For this reason, if the pulverized coal blowing increases, the combustion efficiency of the pulverized coal decreases with a decrease in the air ratio. When the air ratio falls below about 1, the amount of unburned char generated in the raceway sharply increases. Blast furnace fuel ratio is 500
At the time of kg / t-pig, the blowing amount of pulverized coal at which the air ratio becomes 1 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 injected. However, if a large amount is blown beyond the above-mentioned limit, the unburned char generated accumulates on the furnace core and impairs air permeability and liquid permeability. This leads to a drop in tapping capacity, which does not result in profit.
An object of the present invention is to solve the above problems and eliminate the adverse effect of the accumulation of the unburned char on the furnace core, thereby enabling a large amount of pulverized coal to be blown.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems. In a blast furnace operating method in which pulverized coal is blown together with hot air from a blowing tuyere of a blast furnace, a method for operating the blast furnace from outside the furnace to a furnace core portion is provided.
A gas containing H ₂ O and / or CO ₂ is sometimes blown into the furnace core by the inserted pipe during the operation to remove burnt char from the furnace core. Or
During operation, H ₂ is sometimes used due to a tube inserted into the furnace core from outside the furnace.
A gas containing at least one of O and CO ₂ and O ₂ is blown into the furnace core to remove unburned char from the furnace core and to remove O 2.
_2, blown of the gas by the ratio of _{H 2} O and CO ₂
It is characterized by keeping the heat balance at the same level as before injection . In addition, as these means, a lance is inserted into the furnace core through an opening provided in the belly of the
It is also characterized by blowing into the core .

[0007]

According to the present invention, the pulverized coal ratio is greatly increased,
The operation is performed with a blowing amount of 00 kg / t-pig or more, and the unburned char deposited on the furnace core is sometimes removed during the operation, for example, by periodically removing the char.

As a means for this, gas is blown into the furnace core during operation by means of a pipe inserted from outside the blast furnace to react with unburned char and remove it. H ₂ O (water vapor), C
O ₂ or a gas containing them, 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 in the following chemical formula, it is preferable to use a heating means in combination.

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

As the heating means, plasma heating can be used in addition to the generally used means of 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 for the purpose of periodically removing unburned char under normal operating conditions, and for heating when the furnace core cools down and an inert portion is formed. is not. Therefore, the method of unnecessarily heating is not preferable because the heat balance in the furnace is lost.

Therefore, the unburned char is removed, but it is preferable to make the thermal condition that the balance is almost balanced. As a method of balancing the heat balance, there is a method of balancing by the composition of the gas itself, in addition to the above-described method of heating the gas. 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 a 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
In this case, the unburned char can be removed without affecting the heat. Actually, in consideration of the temperature of the gas to be fed, when the temperature is low, adjustment may be made such as increasing O ₂ and increasing heat generation.

As a means for blowing gas, a blowing lance is inserted from the tuyere portion, between the tuyere, on the tuyere, from the furnace belly, etc. to the furnace core. 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 uses a similar means to insert a water-cooled blowing lance 6 from an opening provided in advance during operation. A blow is performed.

The insertion of the blowing lance 6 from the tuyere 2 involves insertion of the lance through the high-temperature portion of the raceway, so that the blowing time is restricted by the durability of the lance, but existing equipment can be used. Therefore, there is an advantage that it is not necessary to newly provide an opening. Also, a method of providing an opening between the tuyeres (not shown) is preferable because a high temperature portion of the raceway can be avoided. However, the space between the tuyere is the thickest part of the steel shell of the blast furnace due to the problem of strength, and there is a problem that it is quite difficult to provide an opening. For this reason, there is a method (not shown) of providing an opening at the upper part of the tuyere. However, this part has an annular pipe 7 and a blower branch pipe 8 for the tuyere ventilation, which may be an obstacle. It may be difficult to arrange the 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 to the furnace core 4. According to this method, the distance to the furnace core 4 is slightly increased, but the lance can reach the furnace core without passing through the high-temperature portion on the way, and work can be continued for a long time, which is preferable in terms of lance durability.

[0018]

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

[Table 1]

In a blast furnace having an internal volume of 3900 cubic meters, the effect of gas injection into the furnace core by a lance was tested by changing the amount of pulverized coal injected. As shown in FIG. 1, the gas was blown during the operation by providing an opening in the furnace belly 3 and inserting a lance 6 therein. The blowing time was 15 minutes at a time, and the places were sequentially changed at six places around the blast furnace. The number of gas injections for one location is once a day.

Comparative Example 1 is a reference condition, in which the pulverized coal is blown at a rate of 150 kg / t-pig, and is a normal operation in which gas is not blown into the furnace core. In Examples 1 to 4, the amount of pulverized coal injected was increased to 200 kg / t-pig, and the unburned char of the furnace core was removed by gas injection. In the first to third embodiments, the gas containing no O ₂ is heated to a high temperature. In the fourth embodiment, the heating temperature of the gas is lowered by introducing air and utilizing the exothermic reaction of O ₂ . In these examples, the replacement ratio of coke by pulverized coal does not change and the fuel ratio does not increase. Also, tapping capacity is on track. On the other hand, in Comparative Example 2 in which the pulverized coal injection amount was increased to 200 kg / t-pig but gas was not injected into the furnace core, a tendency of an increase in the fuel ratio and a decrease in the tapping amount were observed.

Further, the amount of pulverized coal to be blown is 250 kg /
Although it 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 Is also going well. Examples 5 and 6 correspond to Examples 1 to 3
Example 7 is an example using a gas containing no O _2, and Example 7 is an example using a gas containing O ₂ , as in Example 4. On the other hand, in Comparative Example 3, although the pulverized coal injection rate was increased to 230 kg / t, unburned char was deposited because gas was not injected into the furnace core, and this impaired gas permeability and liquid permeability of the furnace core. As a result, an increase in fuel ratio and a decrease in tapping rate are observed.

[0022]

According to the present invention, in the blast furnace operation, unburned char deposited on the furnace core when the amount of pulverized coal blown from the tuyere is increased can be removed during the operation by the method of the present invention. This makes it possible to increase the amount of pulverized coal injected without deteriorating the furnace condition, and reduce the amount of coke used to reduce costs.

[Brief description of the drawings]

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

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hisao Kamiyama 5-3 Tokai-cho, Tokai-shi, Aichi Prefecture Nippon Steel Corporation Nagoya Works (56) References JP-A-4-268005 (JP, A) JP-A-3-291312 (JP, A) JP-A-3-56611 (JP, A) JP-A-62-270709 (JP, A) JP-A-59-107009 (JP, A)

Claims (3)

(57) [Claims] 1. In a blast furnace operating method in which pulverized coal is blown together with hot air from a blowing tuyere of a blast furnace, the blast furnace is inserted into the core from outside the furnace.
By the tube, sometimes during operation _H 2 O and / or CO
_2. A blast furnace operating method comprising blowing a gas containing ₂ into a furnace core to remove unburned char in the furnace core. 2. In a blast furnace operating method in which pulverized coal is blown together with hot air from a blowing tuyere of a blast furnace, the blast furnace is inserted into the core from outside the furnace.
During the operation, a gas containing at least one of H ₂ O and CO ₂ and O ₂ is sometimes blown into the furnace core during the operation to remove unburned char in the furnace core and to remove O ₂ , H ₂ O and C
The same level of heat as before the gas injection due to the ratio with O ₂
A blast furnace operating method characterized by maintaining a good balance . 3. A lance is connected to a blast furnace through an opening provided on the belly of the blast furnace.
Insert the core portion, blast furnace operation method according to claim 1 or claim 2, wherein the blowing gas into the furnace core section.