JPH0570813A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To provide an operational method for blast furnace, by which combustion at the core part in the blast furnace under the tendency of bad condition is executed and the furnace condition is recovered. CONSTITUTION:In the operation of the blast furnace stabilizing the furnace condition by heating the core part in the blast furnace, blasting in the specific tuyere 8 is stopped and a sampler is inserted through this tuyere 8 or an opening hole arranged at a furnace wall part above the tuyere to take the furnace core constituting material piled at a furnace hearth part in the blast furnace. Then, the measured values of any one or more among the grain size constitution and quantity of coke, quantity of ash, quantity of unmelting pig iron, quantity of unmelting slag and historical temp. of the coke in this furnace core constituting material, are used as an activity index in the furnace core. Based on this activity index in the furnace core, fluid for heating is directly supplied into the furnace core part from at least one tuyere 8 stopping the blasting or the opening hole arranged above the tuyere 8 to burn the furnace core constituting material and also the blasting is executed under the setting blasting condition from the other tuyere 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace operating method and, more particularly, to a blast furnace operating method for directly recovering the furnace condition by directly burning a core portion of a blast furnace which is in a disordered state.

[0002]

2. Description of the Related Art In the operation of a blast furnace for iron making, for example, when a high-moisture raw material, a low-grade raw material that is easily pulverized, or coke that easily deteriorates is charged, the gas flow becomes unstable and the furnace condition tends to fall into a poor condition. Reduce production. Further, if the fuel ratio is lowered and the hot metal temperature is lowered for the purpose of low Si pig iron operation, the furnace condition of the blast furnace tends to fluctuate.

Once the operation of the blast furnace has failed, it takes a considerable amount of time to recover the furnace condition. In particular, when the lower part of the furnace has cooled down, there is a problem that the amount of tapped iron decreases for several months, and the conventional furnace condition recovery operation generally adopted, for example, even in the case of high fuel ratio operation, In the process of operation, it is said that there was no drastic measure because the gas inside the furnace was unbalanced during such a downturn and the condition of the furnace was not easily recovered due to frequent blow through. The applicant of the present invention has previously disclosed, as a method for operating the furnace condition recovery of a blast furnace in which the reactor condition has become unsatisfactory, to Japanese Patent Laid-Open No.
No. 7506 proposes a blast furnace operating method in which, when a condition of the furnace is unfavorable during the operation of the blast furnace and there is a downwind or a wind reduction, the temperature of the core of the furnace is directly heated and heated, and then the blast is restarted.

[0004]

The core of the blast furnace is formed by depositing coke particles. While the charge on the shaft passes through the furnace within a few hours, the core of the blast furnace takes a few days. It is estimated that the coke will be replaced in essence.

While the high-temperature furnace gas is sufficiently flowing in the furnace core, there is no problem because it is in an activated state, but the gas permeability in the furnace is deteriorated due to the fineness of coke particles and other factors. When the flow stops, powder coke, ash, unmelted material (hot metal, slag) will stay in the furnace core, and the lower part of the furnace will be cooled. This is blown under conditions such as JP-A-61-1990.
Even if the blast temperature is raised by using a plasma generator as disclosed in No. 06 or the blowing amount of blast moisture, pulverized coal, etc. is adjusted, the high temperature blast may no longer enter the core of the furnace. Even if the surface of the furnace core is heated, the coke dust, ash, slag, etc. inside the furnace core cannot be eliminated. Even if the distribution of charge is controlled or the core in the above state is not easily replaced even if the coke ratio is increased, the powder coke, ash, and unmelted matter (hot metal / slag) stay in the core, and You can't control the cold. In addition, there are many cases where the balance of the circumference is disturbed, the load drop is not averaged, and the reactor condition becomes unstable.

[0006] Therefore, various methods have been proposed to improve the circumferential balance by taking various actions such as controlling the distribution of the charged material and adjusting the blowing conditions. However, it takes a long time to recover the furnace condition and the immediate effect is obtained. The current situation is that no effective means has been found yet.

The present invention is directed to a method for recovering the furnace condition of the blast furnace described above, and an operation method for effectively carrying out Japanese Patent Laid-Open No. 2-77506, and in particular, powder coke, ash, unmelted material (hot metal, slag, etc.) ), And when the blast furnace condition goes down, such as when the circumstance balance is disturbed and when the blast furnace condition is impaired, it provides a blast furnace operation method for recovering the furnace condition in a short time.

[0008]

Means for Solving the Problems The present invention is to solve the above-mentioned problems, and in the blast furnace operation for heating the core of the blast furnace to stabilize the furnace condition, the blowing of a specific tuyere is stopped. , A sampler is inserted through the tuyere or through an opening / closing port provided in the upper furnace wall portion of the tuyere, and the core constituent deposited on the blast furnace hearth is sampled, Composition and amount of coke that is a product, amount of ash, amount of unmelted pig iron,
A measured value of at least one of the amount of unmelted slag and the history of coke history is used as a core activity index, and based on the core activity index, at least one tuyere or the tuyere of which the blowing is stopped It is characterized in that a heating fluid is directly supplied into the furnace core through an opening / closing port provided above to burn the core constituents and the other tuyere is blown under a set blowing condition. It is also characterized in that the heating fluid is supplied and pulverized coal is blown in.

Based on the core activity index,
At least one electrode and a plasma torch are inserted from the tuyere that has stopped blowing air or the opening and closing port provided above the tuyere, the tip of the electrode is brought into contact with the furnace core, and the furnace core structure is heated by the plasma torch. The blast furnace operating method is characterized in that it is burned and blown from other tuyeres under the set blowing conditions.

[0010]

According to the present invention, the ventilation of a specific tuyere is stopped, and a sampler is inserted through the tuyere or through an opening / closing opening provided in the upper furnace wall of the tuyere to insert it into the blast furnace hearth. The accumulated core constituent is collected, and one or more measured values of the particle size composition and amount of coke which is the core constituent, the amount of unmelted pig iron, the amount of unmelted slag, and the history temperature of coke. So,
Understanding the activity of the core, and the relationship between the accumulated core activity and the furnace condition, for example, the relationship between the grain size composition and amount of coke and the furnace condition, or the amount of unmelted pig iron, the amount of unmelted slag and the furnace Based on the relationship with the condition, when it is determined that there is a sign of reactor condition failure or reactor condition failure, a heating fluid is supplied into the core to burn the core structure and a new inert core is added. Since the furnace core is sequentially replaced and activated, the furnace condition can be recovered in a significantly shorter time compared to the conventional high fuel ratio operation method.

Further, as described above, when it is judged from the furnace core activity index that the condition of the furnace is in a bad condition or the condition of the furnace is in a bad condition, the tip of the electrode is brought into contact with the core and the power is supplied to the furnace for plasma arc heating or the like. The core component can be heated and burned to replace the inactive furnace core with a new furnace core one after another for activation.

When the oxygen source is directly supplied into the furnace core to burn the coke, which constitutes the furnace core, the unmelted pig iron and slag retained between the coke particles are melted and flowed down. It is desirable to ensure the air permeability of the furnace core, and the pulverized coal is supplied to the combustion area in the furnace core and burned to use it as a heat source, so that the consumption of coke particles, which are the core components, can be suppressed.

The present invention will be specifically described below. The present invention continues the operation as it is when the furnace condition of the blast furnace is stable, but in the operation process, various measurement data indicating the furnace condition, for example, the furnace wall temperature, the gas flow distribution in the furnace, the gas temperature, and the unloading If there is any change in the situation, amount of tap metal, amount of slag, etc., the core of the furnace is sampled in the lower part of the furnace, and the particle size composition and quantity of coke in the furnace core, especially the quantity of powder coke of 3 mm or less, the quantity of ash. The amount of unmelted pig iron, the amount of unmelted slag, and the coke history temperature are measured. Here, the history temperature of coke changes the carbon content from amorphous carbon to graphite when the coke is exposed to a high temperature, and the maximum temperature received by the coke is estimated by measuring the amount.

As a sampling method for the core structure, a cylindrical sampler is inserted substantially horizontally from a specific tuyere at which the air supply has been stopped to enter the core, and the core structure is sampled. It is possible to adopt a known sampler such as a method of sampling the core constituent by inserting the cylindrical sampler diagonally downward from the opening / closing port provided in the furnace belly above the predetermined tuyere where it is stopped to enter the furnace core. ..

From the sampled core composition, the particle size composition and amount of coke, the amount of ash, and the amount of unmelted material (pig iron / slag) were measured, and the coke sampled from the coke in the core was measured. Historical temperature is measured.
An example of the relationship between these measured values and the furnace condition immediately before the measurement is shown in Fig. 2 where the depth from the tuyere tip to the furnace center and coke grain size,
As shown in the relationship between the amount and the furnace condition, if the coke grain size of 3 mm or less remains in the furnace core by 30% or more, the furnace core becomes inactive and the furnace condition deteriorates. In addition, the same relationship as in FIG. 2 is shown in FIG. 3, but the unmelted pig iron and the amount of slag are 4
If 0% or more is captured, the furnace core becomes inactive and the furnace condition deteriorates. As shown in FIG. 4, the relationship between the depth from the tuyere tip toward the center of the furnace, the coke history temperature, and the furnace condition,
When the temperature in the furnace core becomes 1400 ° C. or lower, the furnace core becomes inactive and the furnace condition deteriorates.

From the sampled core composition, the particle size composition and amount of coke, the amount of ash, and the amount of unmelted material (pig iron / slag) are measured, and one or more of the measured values are measured. The activity index is used, and if the core activity index cannot satisfy the appropriate value for operation control, or if there is a sign of it, combustion in the core is performed. As a matter of course, appropriate control values should be properly approved for each blast furnace according to the blast furnace volume, operation mode, etc., and may be a combination of two or more.

As the means for burning the core in the present invention,
Oxygen gas, oxygen-enriched air, compressed air, or a heating gas thereof and a combustible gas combusted by these, a fluid for heating such as coke, liquid fuel, etc., toward the furnace core part, or a tuyere that has stopped blowing air, or The lance is inserted through the opening and closing port provided above the tuyere, and the lance is blown directly into the core, or the electrode is brought into contact with the core and burned by plasma arc heating or the like. is there. Further, when the heating fluid is blown in, pulverized coal can be mixed and supplied to these and burned. Of course, it is possible to combine two or more of these. Here, the object to be brought into contact with the furnace core is the object to be heated (coke in this case).
Transfer type that transfers an arc current between and
This is because heating is performed by the plasma torch, so that an electric circuit is formed between the object and the object to be heated. This method is different from the non-transfer type (non-transfer type) plasma torch
Since heat is generated directly at the location of the object to be heated, thermal efficiency is good.
In addition to this, it is of course possible to use plasma heating as a means for heating the gas to be blown (see Example 3).

The electrodes and lances for burning the furnace core are the easiest to insert from the tuyere, but it is also possible to install the insertion opening separately from a specific position other than the tuyere and insert it into an appropriate part. .. When it is inserted from the tuyere, the air blown from the tuyere is partially blocked, but the air blown from the remaining tuyere is retained, so that core combustion can be performed simultaneously without resting, which is extremely effective. .. The time when the core burning is performed is not limited to the time when the air is blown, and may be performed when the air is idle or when the air is turned on. An example in which the present invention is applied to a blast furnace having an internal capacity of 3890 cubic meters will be described below.

[0019]

【Example】

(Example 1) In order to measure the coke particle size in the furnace core,
A coke sampler was inserted from the tuyere to collect the core coke. At this time, 30% or more of the coke having a grain size of 3 mm or less was measured, so that combustion in the furnace core was performed. FIG. 1 is a conceptual diagram of a cross section of the lower part of the blast furnace showing the method. The air blowing of four of the tuyere is temporarily stopped, and combustion lances 1 are respectively inserted from four tuyere 8 in the circumferential direction as shown in FIG. It was inserted into the furnace in position. The combustion lance 1 has a non-water-cooled double tube structure, and has a burner structure in which COG (coke oven gas) is supplied from the inner tube and compressed air enriched with 30% oxygen is supplied from the outer tube to burn at the tip. The combustion air amount was adjusted so that the COG amount was 600 N cubic meters / hr and the air ratio was 1.2.

After the core burn was continued for 60 minutes, the core coke grain size was measured again, and it was found that the core coke particle size was reduced to 10% or less. Therefore, four combustion lances 1 were pulled out, and the blowing was started. We were able to start stable operations.

(Example 2) In order to measure the unmelted material (hot metal / slag) in the furnace core, a coke sampler was inserted from the tuyere, and the unmelted material (pig iron / slag) in the furnace core was sampled. At this time, the unmelted matter (pig iron / slag) was 40% with respect to the collected coke, which reached the limit of impairing the operation, so the core burning was performed. FIG. 5 is a sectional view of the lower part of the blast furnace similar to that of FIG. 1, but as shown in the figure, the shutoff valve 3 provided in the blast branch pipe is closed during the blast to shut off the hot air. Next, the combustion lance 1 was inserted into the furnace core from the tuyere through the seal structure 4. The insertion position was set to 5 m from the tip of the tuyere using the insertion carriage 2. Outer diameter of combustion lance is 125m
m, an inner diameter of 85 mm, and a water-cooled structure, and an inner tube 5 through which pulverized coal can be blown is further provided. 2000 oxygen gas
By blowing N cubic meter / hr and pulverized coal into the furnace for 100 hr / hr for 1 hr, the unmelted material (pig iron / slag) in the furnace core was reduced to 20% or less and stable operation could be recovered.

(Embodiment 3) As shown in the sectional view of the lower part of the blast furnace in FIG. 6, in order to measure the history temperature of coke in the furnace core,
The coke sampler 6 was inserted from the opening on the tuyere, the core coke was sampled, and the coke hysteresis temperature was measured.
At this time, it was found that the temperature decreased to 1200 ° C. or lower at the position where the depth from the tuyere was 3 m, and therefore, core burning was performed. The method is to temporarily stop the air blow, and insert combustion lances 1 from 4 tuyere evenly in the circumferential direction as shown in Fig. 6 into the furnace to the position 5m from the tuyere tip by using the carriage 2. Inserted. The combustion lance 1 has a non-water-cooled single tube structure,
The air heated to 1800 ° C. by the plasma heating device 7 was blown into the furnace at 2500 N cubic meters / hr for about 1 hr. After that, the blast was restarted and it was possible to recover stable operation.

(Example 4) As a result of inserting a coke sampler from the tuyere and investigating the characteristics in the furnace core, the coke particle size of 3 mm or less was 30% or more, and the unmelted material (hot metal / slag) was 40%. %, Which reached the limit that hindered the operation, so core burning was performed. The method was carried out in the same manner as in Example 1, but the stable operation could not be restored, and a resting wind was entered. From the information of the coke sampler, when the core coke particle size was measured, the particle size of 3 mm or less was 10% or less, and the unmelted material (hot metal / slag) in the core was recovered to 30% or less, but the coke history temperature was 1200 ° C. or less. Since it was found that the furnace core combustion was performed again. As for the method, oxygen gas and pulverized coal were simultaneously blown into the furnace as in Example 2. As a result, stable operation could be restored.

[0024]

According to the present invention, since the sampler is directly inserted into the core to judge the core activity, it is possible to detect the abnormal condition of the furnace from the precursory stage and take a countermeasure. When it is determined that the furnace condition is not good, the heating fluid is directly supplied to the core or plasma heating is performed, so that the furnace condition can be recovered in a shorter time than the conventional method of increasing the fuel ratio.

[Simple Drawing Description]

FIG. 1 is a sectional view of a lower part of a blast furnace for explaining a core combustion method by burning fuel gas.

[Fig. 2] Relationship between the depth from the tuyere tip toward the center of the furnace, the coke grain size, the amount, and the furnace condition

[Figure 3] Relationship between the depth from the tuyere tip toward the center of the furnace, the amount of unmelted material (pig iron and slag), and the furnace condition

[Fig. 4] Relationship between depth from the tuyere tip toward the center of the furnace, coke history temperature, and furnace conditions

FIG. 5 is a cross-sectional view of the lower part of the blast furnace for explaining a furnace core combustion method by pulverized coal combustion while blowing air.

FIG. 6 is a cross-sectional view of a lower portion of a blast furnace for explaining a core combustion method by blowing heated air.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morimasa Ichida 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Corp. Central Research Division

Claims (3)

[Claims] 1. In a blast furnace operation for heating a core part in a blast furnace to stabilize the furnace condition, the blowing of air at a specific tuyere is stopped, and it is provided through the tuyere or on a furnace wall portion above the tuyere. A sampler is inserted through the opening / closing port to collect the core constituents deposited in the blast furnace hearth, and the particle size composition and amount of coke, which is the core constituent, the amount of ash, unmelted pig iron. Amount, unmelted slag amount, coke hysteresis temperature, or any one or more of the measured values is taken as a core activity index, and based on the core activity index, at least one tuyere or the wing that has stopped blowing air. A blast furnace operating method characterized in that a heating fluid is directly supplied into the furnace core through an opening / closing port provided above the port to burn the core component and air is blown from other tuyeres under a set blowing condition. .. 2. The blast furnace operating method according to claim 1, wherein a heating fluid is supplied into the furnace core and pulverized coal is blown into the furnace core. 3. In a blast furnace operation for heating a core part in a blast furnace to stabilize the furnace condition, the blowing of air at a specific tuyere is stopped and it is provided through the tuyere or on a furnace wall portion above the tuyere. A sampler is inserted through the opening / closing port to collect the core constituents deposited in the blast furnace hearth, and the particle size composition and amount of coke, which is the core constituent, the amount of ash, unmelted pig iron. Amount, unmelted slag amount, coke history temperature, or any one or more of the measured values is used as the core activity index, and based on the core activity index, the tuyere that has stopped blowing or the upper part of the tuyere. At least one electrode and a plasma torch are respectively inserted from the opening and closing ports provided in the, and the tips of the electrodes are brought into contact with the furnace core,
A blast furnace operating method characterized in that a furnace core component is heated and burned by a plasma torch, and air is blown from other tuyeres under set blowing conditions.