JPH11140517A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operational method of a blast furnace which stabilizes operation at the time of starting up the firing of the blast furnace and can stably shift into high O/C operation having >=5.0 O/C in a short time. SOLUTION: In the uppermost step of charged material layer at the time of filling the raw material before starting up the firing of the blast furnace, the high O/C charged material layer having >=5.0 O/C piled wt. ratio of ore (O) and coke (C) and different O/C, is formed. Plural charged material layers having different O/C are sampled as the piling condition from the high O/C charged material layer, and the charged material distributing condition in the furnace in the high O/C operation having >=5.0 O/C is pre-decided by obtaining the gas permeable resistance in those sampled high O/C charged material layers. Based on this condition, the distribution of the charged material after firing is controlled and the blast furnace operation is shifted into the high O/C operation having >=5.0 O/C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for operating a blast furnace, which contributes to the stabilization and efficiency of the operation of a blast furnace after burning, by blowing auxiliary fuel such as coal, heavy oil, or natural gas from the tuyeres. High O / C reduces coke usage
The present invention relates to a blast furnace operation method capable of shifting to operation stably and early.

[0002]

2. Description of the Related Art In the blast furnace method in the steelmaking industry, iron ore (mixture of iron ore, sintered ore, pellets, limestone, etc.) and ironmaking raw material particles such as coke are sequentially charged into a furnace. A layer is formed, and a high-temperature heat source gas is circulated from the lower part of the furnace to cause an iron reduction reaction. For this reason, it is important to control the gas distribution in the furnace to ensure the reduction reaction, and to control the distribution of the charged layer of the ironmaking raw material and the filling state, which greatly affects the gas distribution, in an economically stable operation. It is important to continue.

On the other hand, in recent years, the operation of a blast furnace has been carried out in a conventional all-coke operation (all of the reducing material is installed as coke from the top of the furnace for the purpose of greatly reducing the fuel cost, reducing the load on the coke oven, and extending the life of the furnace, etc.). Method), in addition to charging coke from the top of the furnace, the operation has been shifted to injecting auxiliary fuel such as inexpensive pulverized coal, heavy oil, or natural gas from the blast furnace tuyere. Among the operations of this blast furnace,
In order to maximize the cost merit, and to stabilize and improve the efficiency of the operation after the blast furnace is started, inject auxiliary fuel such as pulverized coal to ore
It is important to quickly and stably shift to high O / C operation where the weight ratio Ore / Coke (hereinafter simply referred to as O / C) of (O) and coke (C) is 5.0 or more. Is an important issue.

[0004] However, in the high O / C operation by pulverized coal injection of 150 kg / t-pig iron or more, the ratio of coke to ore decreases, and the weight ratio O / C of ore to coke increases. In the raw material deposition situation, a local high O / C portion is likely to be generated in the blast furnace radial direction or the circumferential direction. The occurrence of such a locally high O / C portion causes a rise in the temperature of the ore and a stagnation of the reduction, which hinders smooth melting and dripping. This phenomenon is further promoted by a decrease in the amount of gas rising in the bed due to the increase in the thickness of the ore and the decrease in the thickness of the coke due to the increase in O / C. This phenomenon is caused by the fact that in the blast furnace operation, the gas flow resistance inside the blast furnace is increased and the gas flow especially at the center of the blast furnace is reduced, and conversely the gas flow on the furnace wall side is increased, and the heat loss from the furnace wall Is disadvantageously increased. Furnace heat fluctuations due to fluctuations in these furnace gas flows are:
Operational troubles hinder productivity and O / C is 5.0
Problems such as the inability to shift to the above-mentioned high O / C operation stably and early occur.

[0005] Generally, in a blast furnace, an operator changes the position of an armor plate (movable armor) or the tilting pattern of a bellless distribution chute based on information from various sensors installed in the blast furnace. By controlling the distribution (thickness) of the charge, the gas flow distribution in the furnace and the furnace heat load are controlled. However, since the quantitative relationship between the gas flow distribution obtained from the sensor information and the control amount by the charging means of the iron raw material charge cannot be grasped sufficiently accurately, the control amount by the charging means was changed, and The distribution (thickness) of the charge layer must be controlled by a trial-and-error method that further changes the gas flow distribution according to the fluctuation trend. That is, when the control amount of the charging means is changed, the distribution of the charged layer changes, and the gas flow distribution changes accordingly, whereby the distribution of the charged layer is a kind of parameter. Therefore, if these parameters cannot be sufficiently grasped, at present, it is not possible to quickly and reliably correspond between the control amount of the charging means and the result of the gas flow distribution. For this reason, it is not easy to match the actual gas flow distribution with a desirable distribution for the furnace condition, for example, by strengthening the gas flow in the center of the furnace. Adjustment of the distribution of the inputs was necessary. And this is
After starting up the blast furnace, it is not possible to transition to a high O / C operation with an O / C of 5.0 or more stably and early, and this is a major cause that takes time.

In order to solve such a problem, Japanese Patent Application Laid-Open No. HEI 2-182815 and the like have conventionally determined a gas flow distribution state in a radial direction in a furnace by using a knowledge engineering system in which a gas flow distribution state is represented by a triangular diagram. A method has been proposed in which a charge distribution prediction model calculation is performed under a plurality of conditions based on the online data at this time, and an optimum distribution chute tilt pattern is selected from the calculation results.

However, according to the method disclosed in Japanese Patent Application Laid-Open No. 2-182815, the hit rate of the control amount largely depends on the accuracy of the model for predicting the distribution of charged objects. By simply representing the gas flow distribution state with a triangular diagram as in this prior art, the accuracy of the charge distribution prediction model cannot be obtained, and the direction of the charge distribution action over a long period of time cannot be obtained. Cannot be clarified.

The reason for this is that the O / C ratio rises, especially with the increase of wind from the early stage of the blast furnace burning and the start of auxiliary fuel injection such as pulverized coal (PC). The operation shifts to high-pulverized coal injection under condition C. In this case, the ore layer with a smaller angle of repose is stacked on the coke terrace compared to the coke layer, so the stacking condition becomes unstable and the coke layer Collapse and a large amount of ore flowing toward the furnace center are likely to occur. As a result, the reproducibility of the deposition profile for each charge tends to decrease.
Therefore, in order to lower the ventilation resistance in the blast furnace and to strengthen the gas flow in the center of the blast furnace, in order to obtain the necessary gas flow distribution,
It is necessary to control practical charges by taking instability phenomena such as coke collapse occurring in the actual furnace. Nevertheless, the method disclosed in Japanese Patent Application Laid-Open No. 2-182815 does not take into account any instability phenomena such as coke collapse occurring in the actual furnace.

In order to solve this problem, Japanese Patent Application Laid-Open No. Hei 9-111321
In this publication, the correlation between the ore / coke layer thickness ratio in the furnace radial direction previously obtained from past actual furnace data and these charging conditions is used, and the layer thickness expected at the time of charging change is used. Techniques have been proposed to change the ore / coke charging conditions when there is a difference between the ratio and the actual thickness ratio. The purpose of this technology is to quickly and accurately select the required gas flow distribution in the furnace according to the furnace conditions after the change of O / C, such as in the initial stage of burning and starting the blast furnace.

[0010]

However, in this prior art, since the actual furnace data in the past is used, the adaptation of the blast furnace to the initial stage of the start-up of the blast furnace is performed under the condition that the same furnace top equipment is used. Is only applicable if are identical. Therefore, if the conditions of the furnace top equipment are changed due to the blast furnace renovation, it is necessary to collect the actual furnace data again after the start-up of the blast furnace.
It is difficult to shift to C operation.

Moreover, in this prior art, only the bellless strength ratio and the ore / coke layer thickness ratio are obtained as past actual furnace data. In this case, it is not possible to accurately grasp the permeability of a mixed layer of coke and ore having a high packing density (closest packed layer) generated between the coke layer and the ore layer and reflect the permeability in control. Therefore, in these prior arts, since the thickness of the mixed layer is not taken into account, the control of the thickness of the mixed layer becomes insufficient, and a drift occurs in a portion where the thickness of the mixed layer is uneven, and the ventilation state in the furnace is reduced. In other words, there are areas where the ventilation resistance locally increases, and the temperature and gas flow distribution in the furnace become non-uniform, which tends to have an adverse effect on the furnace operation, such as reduction reactions, and a high O / C of 5.0 or more. It will not be possible to shift to O / C operation stably and early and it will take time.

In view of the above problems of the prior art, the present invention prevents local high O / C from occurring when a blast furnace is fired and started, enhances the gas flow in the center of the blast furnace, and reduces the O / C. But
It is an object of the present invention to provide a blast furnace operating method capable of stably and early shifting to a high O / C operation of 5.0 or more.

[0013]

In order to achieve the above object, a method for operating a blast furnace according to the present invention comprises the steps of charging ore and coke sequentially into a blast furnace at the time of charging the raw materials before starting the blast furnace. In forming the charge layer by depositing, at the top of the charge layer, the weight ratio of the ore (O) and the coke (C)
A high O / C charge layer having an O / C of 5.0 or more and different O / C is formed, and at least an ore layer, a mixed layer of ore and coke, and a coke layer are formed from the high O / C charge layer. Layers with different O / Cs were collected in the as-deposited state, and the ventilation resistance of these sampled high O / C layers was determined. The charge distribution conditions in the furnace in the high O / C operation described above are determined in advance, and the distribution of the charge after burning is controlled based on these conditions, so that the O / C is at least 5.0.
C operation.

[0014] The present inventors use a high O / C operation having an O / C of 5.0 or more, regardless of whether various models of the gas flow distribution state are used as in the above-mentioned prior art or whether past actual furnace data is used. Accurately grasps the air flow resistance of the bed of ore or coke, etc., which is assumed to have a high density, especially the mixed layer of coke and ore with high packing density (closest packed bed) generated between the coke layer and the ore layer Otherwise, accurate ventilation of the charge layer in the furnace radial or circumferential direction, which is the relationship between the O / C of the charge layer and the ventilation resistance in high O / C operations with an O / C of 5.0 or more. Since the resistance distribution cannot be grasped, as a result, the distribution state of the charge layer after the start-up of the burn-up to prevent local high O / C generation and enhance the gas flow in the center of the blast furnace is accurately determined. It was found that no proper control was possible.

[0015] That is, raw materials of iron ore such as iron ore and coke are charged alternately into the blast furnace from the top of the blast furnace to form a multilayered charge layer. At this time, the ore's particle size is very small compared to the coke's particle size, and because of its high density, the ore flowing into the center of the furnace when charging the ore onto the coke sedimentary layer, Scraping off the upper layer of the coke layer,
A layer of coke and ore with a high packing density (closest packed layer) is formed between the coke layer and the ore layer, causing instability such as coke collapse and the like.
Is formed.

This mixed layer has poorer air permeability than the coke layer and the ore layer, and greatly affects the gas distribution in the furnace. As mentioned above, especially in high O / C operation, the ratio of coke to ore decreases, and the weight ratio of ore to coke O / C
Therefore, in the raw material deposition state in the blast furnace, a local high O / C portion in the blast furnace radial direction or the circumferential direction is easily generated. Therefore, in high O / C operation,
It is important to grasp the state of formation of a mixed layer of coke and ore having a high packing density and to control the thickness of the mixed layer in the radial direction or circumferential direction of the furnace.

Therefore, according to the present invention, in order to accurately control the distribution state of the charge layer after the start-up of the blast furnace, the O / C is preferably set to 5.
O / C higher than 0
The air permeability (airflow resistance) including the mixed layer of coke and ore in the high O / C charge layer by intentionally forming the O / C charge layer
Is obtained in advance. And these O / C
Based on the airflow resistance of the different sampling height O / C charge layers,
The distribution condition of the charge in the furnace in the high O / C operation with O / C of 5.0 or more is determined in advance, and based on this condition, the distribution of the charge layer after burning is controlled, and the O / C is 5.0 or more. It is also characterized by an early shift to high O / C operation.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The airflow resistance of the collected high O / C charge layer may be measured directly by measuring the airflow resistance of the sampled charge layer. By grasping it, it can be obtained more easily and accurately. That is, the ventilation resistance of the sample layer at the sampled high O / C charge layer, as the layer structure of the charge layer, porosity,
It can be determined by measuring the particle size and particle shape factor (flatness of particles).

The gas flow resistance of the sample layer at the sampled high O / C can be determined from the measured values of the respective layer structures as a gas flow resistance coefficient in a known gas pressure loss formula. More specifically, for example, the gas pressure loss equation (empirical formula) of Ergun, which expresses the gas pressure loss in the axial direction of a packed bed having a uniform particle size at an isothermal temperature, is used to aerate the high O / C charge layer. The resistance coefficient can be calculated. The gas pressure loss equation of Ergun expresses the pressure loss ΔP of the charge layer (packed bed) having a layer thickness L by ΔP / L = − (f ₁ + f
₂ G) G, (where f ₁ , f ₂ : airflow resistance coefficient of the charge layer, G:
Expressed by the mass velocity of gas [kgf / (m ² · bed · s)]. Therefore, the ventilation resistance of the sampled high O / C charge layer is determined as f ₁ (laminar flow region) to f ₂ (turbulent flow region) in this equation. Airflow resistance coefficient of the high O / C charge layer in the present invention, the turbulent flow region is dominant, for convenience, it calculates a f ₂ as the representative value. The gas flow resistance coefficient f ₂ is represented by f ₂ = 1.75 (1−ε) / g _c ρ _g φ d _p ε ³ in the above-mentioned Ergun gas pressure loss equation (where ε: Porosity of each layer, g _c : Gravity conversion coefficient [kg ・ m / kgf ・ s ² ], ρ _g : Density of gas in blast furnace [kgf / m ³ ], φ: Particle shape coefficient of each layer of sampling charge layer
In (flatness), φ = surface area of sphere with volume equal to the volume of particle / surface area of particle.When particle is sphere, φ = 1,
Flat particles are φ ≦ 1, d _p is the particle diameter [m] of the ore and coke in the sampled bed, and the harmonic mean diameter if it has a particle size distribution.
d _p '= (Σ X _i / d _pf ) ^-1 , where X _i is the particle size d _pf
[m] weight fraction or volume fraction). Incidentally, the ventilation resistance coefficient f ₁ is f ₁ = 150 (1−ε) ² μ / g _c ρ _g d _p ² φ ²
ε ³ , (where μ: viscosity of gas in blast furnace [kgf / m · s])
It is represented by For example, when the sampled high O / C charge layer is composed of three layers of an ore layer, a mixed layer of ore and coke, and a coke layer, the airflow resistance coefficient f ₂ of each of
The calculated, and weighted average of these airflow resistance coefficient f ₂ from each of the layer thickness ratio of ~, the airflow resistance coefficient of collecting high O / C charge layer and f _2.

As described above, the airflow resistance coefficient (airflow resistance) of a specific sampled high O / C charge layer is determined, but in the present invention, a high O / C charge layer having a different O / C is used. In addition, it is necessary to collect a plurality of charge layers, and to determine the ventilation resistance coefficient of the plurality of high O / C sample charge layers. For this reason, in the present invention, when ore and coke are sequentially charged into a blast furnace to form a charged layer, the O / C differs at the uppermost stage of the charged layer.
It is necessary to form more than one type of high O / C charge layers and to collect charge layers having at least an ore layer, a mixed layer of ore and coke, and a coke layer as they are deposited. Even if the ore layer or the coke layer alone is sampled without the mixed layer (closest packed layer) of the coke and the ore having a high packing density between the coke layer and the ore layer, and the airflow resistance is obtained, Cannot accurately grasp the ventilation resistance of the intended high O / C charge layer. In addition, simply determining the airflow resistance of a single high O / C charge layer will result in a high O / C
The relationship between the O / C of the charge layer in operation and the ventilation resistance in the blast furnace, i.e., the ventilation resistance of the high O / C charge layer in the radial direction or the circumferential direction in the furnace during high O / C operation. The distribution cannot be determined accurately.

In order to make the O / C of the high O / C charge layer different, the O / C of the charge layer to be sampled is changed in the circumferential direction of the blast furnace so as to change the O / C of the charge layer. Either form an O / C target charge layer with different O / C in the direction, or form and collect O / C target target charge layer at the same site in the blast furnace and discharge it to obtain a different O / C. It is preferable to repeat the formation and sampling of the charge layer for / C to be sampled again so that the O / C of the high O / C charge layer varies in the radial direction in the blast furnace. This makes it possible to accurately determine the distribution of the ventilation resistance of the high O / C charge layer in the furnace radial direction and / or the furnace inner circumferential direction.

Next, the ventilation resistance coefficient of the specific sampled high O / C charge layer and the ore /
From the distribution of the coke layer thickness ratio, the accurate ventilation resistance distribution of the high O / C charge layer simulating the high O / C operation in the furnace radial direction or in the furnace circumferential direction is determined. The distribution of the ore / coke thickness ratio in this furnace radial direction or furnace circumferential direction is
It can be determined by actually measuring the ore / coke layer thickness ratio of a high O / C charge layer sampled from the furnace radial direction or the furnace circumferential direction. The measurement of the distribution of the ore / coke layer thickness ratio is performed by a conventional method, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-111321.
As disclosed in Japanese Unexamined Patent Publication (Kokai) No. H10-209, a method of measuring the surface profile and the particle size distribution of the charge layer using a profile meter provided at the top of the blast furnace is also conceivable. Due to the instability of the slag condition (collapse of the coke layer and inflow of a large amount of ore toward the furnace center)
The ore / coke layer thickness ratio distribution cannot be measured accurately due to the reduced reproducibility of the deposition profile for each charge. Therefore, the exact distribution of the ore / coke layer thickness ratio in the furnace radial direction or in the furnace circumferential direction
It is also a great advantage of the present invention that it can be determined by actual measurement of the sample O / C charge layer.

The high O / C simulating this high O / C operation
From the distribution of the ventilation resistance of the charge layer, considering the charging material conditions assumed in the actual high O / C operation, the local and radial directions in the furnace and the circumferential direction during the high O / C operation are considered. Determine the distribution conditions of the charge layer after start-up and high-O / C operation to prevent the generation of high O / C parts and increase the gas flow in the center of the blast furnace, and after start-up To control the distribution of the charge layer. This control method is performed using a known furnace top charging apparatus such as changing the stroke of the armor plate or the tilting pattern of the bellless distribution chute to control the radial charge distribution in the furnace. .

As a method of collecting the charge layer to be collected in the actual blast furnace as it is in a deposited state, the present applicant has filed a patent application as Japanese Patent Application No. 8-250278.
It is preferable to use a sampling method and a sampling jig for the particulate matter deposit. According to this method, after a pipe is erected in advance at a target collection site of a particulate matter deposit, the powder is deposited at the target collection site, and thereafter, a binder is supplied from an opening provided in the pipe around the pipe. This is a collecting method in which the granular materials are combined by being injected into a charge layer for the purpose of collection, and thereafter, the pipe is pulled up to collect and collect the layered granular material deposits to be collected around the pipe.

Referring to FIG. 3, a method of collecting a high O / C charge layer according to the present invention using the method described in Japanese Patent Application No. 8-250278 will be specifically described. First, in FIG. 3, the sampling jig is basically composed of a pipe 1 that is longer than the thickness of the target sampling charge layer and a pipe on the charge layer provided at the tip of the long pipe 1. And a flange (bottom plate) 6 provided above the anchor part 5 at the position of each intended sampling charge layer in the longitudinal direction of the pipe 1.
Openings 2, 3, and 4 for discharging the binder are provided, and a plurality of projections (studs) 7 are provided around the pipe 1 at regular intervals in the radial direction of the furnace. This projection 7
Has the effect of increasing the adhesion between the pipe and the target sampling charge layer or retaining the target sampling charge layer against the impact of lifting the pipe or the impact of later measurement or handling. Demonstrate.

The openings 2, 3, 4 provided in the pipe
Is a mixed layer of ore and coke C2 and a coke layer C
1. The thickness of the charge layer of the ore layer C3 is calculated, and the binder to be injected is provided at a corresponding position above each layer so as to uniformly penetrate the target charge layer. As a specific example, a mixed layer C of ore and coke which is most important to collect
2 corresponds to the charge layer thickness of coke L
Then, the opening 3 corresponding to the coke layer is provided at a pipe position of 0.8 L from the flange 6, respectively.

Next, a sampling method using the sampling jig will be described. Low O /
The ore C and coke are sequentially charged into a blast furnace to form a charge layer, and a pipe 1 serving as a sampling jig is placed at a target sampling site on a charge layer C0 deposited in the furnace. , The charge layer C
0 by embedding the anchor portion 5 in the charge layer C
0 (tilted at a certain angle with respect to the radial direction of the furnace), it is erected at a substantially right angle (in FIG. 3, the pipe is shown to be upright for convenience). Then, the top stage of the charge layer (low O /
C on the charge bed C0), the coke (C) and pig iron
A high O / C charge layer having a weight ratio O / C to (O) of 5.0 or more is formed by sequentially charging ore and coke into a blast furnace. The charging is stopped when the respective high-purpose O / C charge layers of the coke layer C1, the mixed layer of ore and coke C2, and the ore layer C3 are formed.

Next, after confirming the setting status, the operation of resin injection is started. The resin injecting operation is carried out by injecting resin, which is a particulate binder, from above the pipe indicated by the arrow A, directly into the pipe port 10 or through a tube connected to the pipe port 10 by a pump (not shown) outside the furnace. Into the target charge layer around the pipe through the openings 2, 3, and 4 provided in the pipe, and penetrate between the powders and granules. After a while, the resin is hardened. Combine the granules together. Here, the tensile strength of the charge layer comprising harvested close-packed layer portion 50 N / mm ² or more, the bending if strength is 80 N / mm ² or more, the collected charge layer, the layer thickness It is preferable because strength and hardness that can withstand measurement tests such as distribution, particle size distribution, porosity, and shape coefficient measurement can be ensured. When the binder is a liquid resin containing a curing agent, the Rockwell hardness (according to JIS K7202) of the solidified resin in the collected charge layer is HRM5.
If it is 0 or more, the strength can be secured.

At the same time, a metal frame 8 is placed above the charge layer (above the ore layer C3) toward the periphery of the pipe 1.
Is installed, and the binder is injected into the charge layer also from above, using the metal frame 8 as a resin liquid pool. At the time when the resin has penetrated and hardened between the granular materials and the strength required for sampling has been obtained, the pipe 1 is attached to a locking portion 9 provided at the upper end of the pipe with a wire or the like. The pipe is lifted by the installed crane, etc., and the target charge layer around the pipe is pulled up. In this method, as described above, since the pipe opening ratio, the resin viscosity, and the like can be sufficiently adjusted, the resin is less likely to spread out of the range of the target charge layer (the lateral flow of the resin), and the surrounding area is relatively smooth. , And the target harvested charge layer can be lifted.

[0030]

Next, embodiments of the present invention will be described. Internal volume 4
In a large 550 m ³ large blast furnace, low O / C (O
The ore and the coke (0 / 2.0) were charged into the blast furnace to form a low O / C charge layer. Then, at the uppermost stage of the low O / C charge layer, using a removable armor under the charge conditions shown in Table 1 below, C ₁ ↓ C ₂ ↓ O ₁ ↓ O ₂ ↓
A high O / C charge layer was formed by four batch charges (C: coke,: O coke, numbers indicate batch charge order). More specifically, C ₁ is 350 mm, C ₂ is the same thickness of 650 mm, only the furnace inside Bojishon of O ₁ armor, 25
0 mm (X mark, thin line in Fig. 1 described later), 450 mm (D mark in Fig. 1,
(Thick line), 650 mm (marked with △ in Figure 1, dotted line)
O ₁ to O ₁ drop position of Sonyutoki, by migrating sequentially furnace interior, changing the radial O / C in the furnace. In such a batch charge, the distribution of the ore to coke layer thickness ratio of the obtained high O / C charge layer is mainly determined by C ₂ and O ₂ .

[0031]

[Table 1]

By changing the position of the O ₁ armor and changing the O / C in the furnace in the radial direction, the high O / C charge layer was used as shown in FIG.
In the manner shown in FIG. 4, a charge layer having an ore layer, a mixed layer of ore and coke, and a coke layer was respectively collected from each position in the furnace radial direction, and a collected charge layer X shown in FIG. ₁ was obtained. The collected high O / C charge layer X _1, as shown in FIG. 4, the coke layer C1, mixed layer C2 of ore and coke,
It has a charge layer of ore layer C3. And the sampling height O /
C As the layer structure of the charge layer, the porosity of the charge layer, the particle size of the particles, and the flatness of the particles were measured, and from these measured values, the sampling height O / C was determined by the Ergun gas pressure loss equation. A coke layer C1 of a charge layer, a mixed layer C2 of ore and coke,
Determined each airflow resistance coefficient f ₂ ore layer C3, and weighted average of these ventilation resistance coefficient f ₂ from each of the layer thickness ratio, taken high
The ventilation resistance coefficient f ₂ of the O / C charge layer was determined.

Obtained sample height O / C Permeation resistance coefficient of the charge layer
the f _2, the distribution of the furnace radial direction shown in FIG. As can be seen from Fig. 1, the position of the movable armor is 250 mm (x mark in Fig. 1,
When the O ₁ drop position shifts to the furnace wall side in the furnace radial direction at (thin line), the ventilation resistance around the furnace wall in the blast furnace has increased, and the center gas flow in the furnace has been strengthened, It is expected that stable and early transition to high O / C operation with O / C of 5.0 or more will be possible. Conversely, the position of the movable armor is 650 mm (△ in Fig. 1).
When the O ₁ drop position (marked and dotted line) is located from the center in the furnace radial direction, the ventilation resistance around the furnace wall in the blast furnace decreases, the center gas flow is weakened, and the surrounding gas flow is reduced. It is promoted and the cohesive zone inside the furnace becomes W-shaped, heat loss of the furnace wall increases and furnace heat fluctuates, causing operation troubles and stable O / C operation with O / C of 5.0 or more. And it can be anticipated that it will not be possible to move early. This is because the O ₁ armor, which is the base layer of the O ₂ layer, is extruded, causing the O ₁ layer to fall down to the inside of the furnace, causing ore segregation to the furnace wall side, and the ventilation resistance around the furnace wall. This is because the value has decreased.

Based on the distribution of the ventilation resistance of the charge layer in the radial direction in the furnace, the central gas flow in the blast furnace is increased while the charge condition in the high O / C operation with O / C of 5 or more is increased. , Determine the distribution condition of the charge in the furnace radial direction in high O / C operation with O / C of 5 or more such that the surrounding gas flow is suppressed and the local high ventilation resistance does not appear. Based on this condition, after controlling the distribution of the charge in the furnace in the radial direction after the blast furnace was started, the blowing amount of pulverized coal was gradually increased, and the high O / C ratio of O / C was 5.0 or more. Shifted to C operation.

At this time, the tapping ratio (t / day / m ³ ) and pulverized coal ratio (k
g / t), coke ratio (kg / t), fuel ratio (kg / t), air flow (Nm ³ / m
in) and the time-dependent changes of the oxygen-enriched amount (Nm ³ / min) are shown in FIG.
As is clear from Fig. 2, the change in the amount of pulverized coal
15 days after burning, pulverized coal ratio was 50 kg / t after 15 days, pulverized coal ratio was 125 kg / t after January, and pulverized coal ratio was 170 kg / t after 1 year.Other tapping ratio, coke ratio, fuel ratio, and air volume Even from the oxygen enriched amount, O / C
It can be seen that has shifted to high O / C operation of 5.0 or higher. In addition, it can be seen that these transitions are performed stably, as is apparent from changes in the amount of air blown.

Therefore, from this embodiment, it can be seen that the blast furnace operating method according to the present invention allows a
Forming and collecting a high O / C charge layer simulating or assuming O / C operation, and finding the ventilation resistance of the sampled high O / C charge layer. Only by adding processes, it is possible to determine in advance stable operating conditions (conditions of charge distribution in the furnace) in high O / C operation with O / C of 5.0 or more, and O / C of 5.0 or more. Demonstrates that early and stable transition to high O / C operation is possible.

[0037]

As described above, the method for operating a blast furnace according to the present invention is particularly suitable for a large blast furnace,
In particular, O / O with a high pulverized coal injection rate of 150 kg / t
Enables early and stable transition to high O / C operation with C of 5.0 or higher. Moreover, the industrial significance is significant in that this effect can be easily achieved without greatly changing the conventional blast furnace operation method.

[Brief description of the drawings]

[1] shows an embodiment of the present invention, the collected high O / C airflow resistance coefficient of the charge layer f _2, it is an explanatory diagram showing the distribution of furnace radial direction.

FIG. 2 shows an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing temporal changes in tapping ratio, pulverized coal ratio, coke ratio, fuel ratio, blown air amount, and enriched oxygen amount when shifting to a high O / C operation in which C is 5.0 or more.

FIG. 3 is an explanatory diagram showing a method for collecting a high O / C charge layer in the present invention.

FIG. 4 is an explanatory diagram showing a sample height O / C charge layer in the present invention.

[Explanation of symbols]

1: pipe, 2, 3, 4: pipe opening,
5: anchor portion, 6: flange, 7: projection (stud), 8: metal frame, 9: locking portion,
10: Pipe inlet, C0: low O / C charge layer, C1: coke layer, C2: mixed layer of ore and coke, C3: ore layer, X, X _1: collecting charge layer

Continued on the front page (72) Inventor Kentaro Nozawa 1 Kanazawacho, Kakogawa City, Hyogo Prefecture Inside the Kobe Steel Works Kakogawa Works (72) Inventor Shunta Sakano 1 Kanazawacho Kakogawa City, Hyogo Prefecture Kobe Steel Corporation Kakogawa Works Inside the steelworks

Claims (5)

[Claims] 1. An ore and a coke are sequentially charged into a blast furnace at the time of raw material charging before the blast furnace is fired and started.
(O) and the coke (C) weight ratio O / C is 5.0 or more,
And forming a high O / C charge layer having a different O / C, comprising at least an ore layer, a mixed layer of ore and coke, and a coke layer from the high O / C charge layer; A plurality of charge layers with different / C were collected as they were deposited, and
O / C is calculated by determining the ventilation resistance of the C charge layer.
The charge distribution condition in the furnace in the high O / C operation of 0 or more is determined in advance, and the distribution of the charge after burning is controlled based on this condition, so that the O / C is 5.0 or more. C Blast furnace operation method characterized by shifting to operation. 2. A high O / C formed at the uppermost stage of the charge layer.
The blast furnace operation method according to claim 1, wherein the O / C of the charge layer is different in a radial direction in the blast furnace and / or a circumferential direction in the blast furnace. 3. The blast furnace operating method according to claim 1, wherein a ventilation resistance coefficient is obtained from a layer structure of the sampling charge layer. 4. The blast furnace operating method according to claim 1, wherein pulverized coal of 150 kg / t-pig iron or more is blown into the blast furnace in the high O / C operation. 5. A pipe is erected in advance at a target collection site of the high O / C charge layer, and then a high O / C charge layer is deposited at the target collection site. Harvest purpose
5. The target charge layer around the pipe is collected as it is by collecting the target charge layer around the pipe by injecting the powder into the O / C charge layer to bind the granular materials together, and then pulling up the pipe. A blast furnace operating method according to any one of the preceding claims.