JP3522511B2 - Blast furnace operation method - Google Patents

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 stabilization and efficiency of operation of a blast furnace after burning, and by blowing auxiliary fuel such as coal, heavy oil, natural gas or the like from tuyere, High O / C that reduces coke usage
The present invention relates to a method for operating a blast furnace, which enables stable and early transition to operation.

[0002]

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

On the other hand, in recent years, the operation of a blast furnace has been carried out in the conventional all-coke operation (all reducing materials are installed as coke from the top of the furnace) for the purpose of drastically reducing fuel costs, reducing the burden on the coke oven, and extending the life of the furnace. In addition to the charging of coke from the top of the furnace, the operation of blowing auxiliary fuel such as pulverized coal, heavy oil, and natural gas from the blast furnace tuyeres is being started. Among the operations of this blast furnace,
In order to maximize the cost merit, in order to stabilize and improve the operation of the blast furnace after the start of firing, the auxiliary fuel such as pulverized coal is blown into the ore.
(O) and coke (C) deposit weight ratio Ore / Coke (hereinafter simply referred to as O / C) is 5.0 or more, and it is important to shift to high O / C operation early and stably. Has become a problem.

However, in a high O / C operation by blowing pulverized coal 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, so that the blast furnace In the raw material deposition situation, local high O / C portions are easily generated in the blast furnace radial direction or the circumferential direction. The generation of such a local high O / C portion causes a stagnation in the temperature rise and reduction of the ore, which hinders the smooth melting and dropping. This phenomenon is further promoted by a decrease in the amount of gas rising in the bed due to the increase in the ore thickness due to the high O / C and the decrease in the coke layer thickness. This phenomenon is due to the fact that in blast furnace operation, the ventilation resistance in the blast furnace is increased, the gas flow in the center of the blast furnace in particular decreases, and on the contrary, the gas flow on the furnace wall side rises, causing the amount of heat loss from the furnace wall. The disadvantage is that In addition, fluctuations in furnace heat due to fluctuations in these gas flows in the furnace are
Occurrence of operational troubles that hinder productivity and O / C is 5.0
Problems such as the inability to make stable and early transitions to the above high O / C operations will occur.

Generally, in a blast furnace, an operator changes the position of an armor plate (movable armor) and 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 heat load of the furnace body 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-making raw material charge cannot be grasped sufficiently accurately, the control amount by the charging means is changed and The distribution (thickness) of the charge bed must be controlled by a trial-and-error method in which a changing operation is further performed according to the fluctuation trend of the gas flow distribution. That is, when the control amount of the charging means is changed, the distribution of the charging material layer is changed, and the gas flow distribution is changed accordingly, so that the distribution of the charging material layer is a kind of parameter. Therefore, under the present circumstances, if the parameter is not sufficiently grasped, the control amount of the charging means and the result of the gas flow distribution cannot be promptly and reliably corresponded. For this reason, it is not easy to match the actual gas flow distribution with the distribution desired for the furnace conditions, such as by strengthening the gas flow in the center of the furnace, and in order to obtain the target gas flow distribution, it is necessary to use a long-term equipment. It was necessary to adjust the distribution of the contents. And this is
After the start-up of the blast furnace, the O / C cannot be stably and early transferred to the high O / C operation of 5.0 or more, which is a major cause of time consuming.

In order to solve such a problem, conventionally, in Japanese Patent Laid-Open No. 2-182815, etc., the state of gas flow distribution in the furnace radial direction is determined by a knowledge engineering system that represents the state of gas flow distribution by a triangular diagram. Based on the online data at this time, a method of carrying out a charge distribution prediction model calculation under a plurality of conditions and selecting an optimal tilt pattern of the distribution chute from the calculation result has been proposed.

However, in the method disclosed in Japanese Patent Laid-Open No. 2-182815, the hit rate of the controlled variable greatly depends on the accuracy of the charge distribution prediction model. As in this prior art, by simply expressing the gas flow distribution state with a triangular diagram, 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.

[0008] The reason is that the O / C ratio rises, and finally the high O / C ratio rises as the wind blows from the initial stage of the blast furnace firing and the start of blowing in auxiliary fuel such as pulverized coal (PC). Under the C condition, the operation shifts to high pulverized coal blowing operation, but in this case, more ore layers with a smaller repose angle than the coke layer are stacked on the coke terrace, so the stacking condition becomes unstable and the coke layer Collapse and a large amount of ore flow toward the center of the furnace are likely to occur. As a result, the reproducibility of the deposition profile for each charging charge tends to decrease.
Therefore, in order to reduce the ventilation resistance in the blast furnace and strengthen the gas flow in the center of the blast furnace, in order to obtain the necessary gas flow distribution,
It is necessary to take into account the destabilization phenomenon such as coke collapse that occurs in the actual furnace, and to carry out practical charge control. Nevertheless, the method disclosed in Japanese Patent Laid-Open No. 2-182815 does not take into consideration the destabilization phenomenon such as coke collapse that occurs in the actual furnace.

To solve this problem, Japanese Patent Laid-Open No. 9-111321
In the gazette, etc., the correlation between the ore / coke layer thickness ratio in the radial direction in the reactor, which was obtained in advance from past actual furnace data, and the correlation with these charging conditions are 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 layer 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 O / C change, such as the initial start-up of the blast furnace.

[0010]

However, in this conventional technique, since the data of the actual furnace in the past are used, the adaptation to the initial stage of the firing and start of the blast furnace is performed under the condition that the same furnace top equipment is used. Applicable only when are the same. Therefore, if the conditions such as the furnace top equipment are changed due to the blast furnace refurbishment, it is necessary to collect the actual furnace data again after the start of firing, and the O / C is 5.0 or higher at an early stage.
It is difficult to shift to C operation.

Moreover, in this conventional technique, only the bellless strength ratio and the layer thickness ratio of the ore / coke layer are obtained as past actual furnace data, and iron ore raw material granules such as ore and coke are alternately laminated. In this case, the air permeability of the mixed layer (closest packed layer) of coke and ore having a high packing density, which occurs between the coke layer and the ore layer, cannot be accurately grasped and reflected in the control. Therefore, in these conventional techniques, since the thickness of the mixed layer is not taken into consideration, the control of the thickness of the mixed layer becomes insufficient, uneven flow occurs in the uneven portion of the thickness of the mixed layer, and the ventilation state in the furnace is However, there are some areas where the ventilation resistance becomes locally high, and the temperature and gas flow distribution inside the furnace become uneven, which tends to adversely affect the operation of the furnace, such as reduction reactions, and the O / C is higher than 5.0. Stable and early transition to O / C operation cannot be done or it will take time.

In view of these problems of the prior art, the present invention prevents the local generation of high O / C at the time of firing and starting the blast furnace, and strengthens the gas flow in the center of the blast furnace to improve the O / C. But
It is an object of the present invention to provide a blast furnace operation method capable of stably and early shifting to a high O / C operation of 5.0 or higher.

[0013]

In order to achieve the above object, the method of operating a blast furnace according to the present invention is one in which ore and coke are sequentially charged into a blast furnace at the time of raw material filling before firing and starting of the blast furnace. When the charge layer is formed by the above process, the weight ratio of ore (O) and coke (C) in the uppermost layer of the charge layer is
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 and a mixed layer of ore and coke and coke are formed from the high O / C charge layer. , And the O / C of 5.0 is obtained by calculating the air flow resistance of these high-O / C-charged layers. The distribution conditions of the charge in the furnace in the above high O / C operation are determined in advance, and the distribution of the charge after firing is controlled based on this condition, and the high O / C of O / C of 5.0 or more is controlled.
It is to shift to C operation.

The inventors of the present invention, whether using the various models of the gas flow distribution state as in the above-mentioned prior art or using past actual furnace data, have a high O / C operation of 5.0 or more. Accurately ascertain the ventilation resistance of the ore or coke charge layer, especially the mixed layer of coke and ore with a high packing density (closest packed layer) that occurs between the coke layer and the ore layer. Otherwise, the accurate ventilation of the charge layer in the radial or circumferential direction in the furnace, which is the relationship between the O / C of the charge layer and the ventilation resistance in high O / C operation with O / C of 5.0 or more. The resistance distribution could not be grasped, and as a result, the distribution state of the charge layer after firing was set up to prevent the local generation of high O / C and strengthen the gas flow in the center of the blast furnace. It was discovered that such control cannot be performed.

That is, iron ore raw material powders such as iron ore and coke are alternately charged into the blast furnace from the top of the blast furnace to form a multi-layered charge layer. At this time, the particle size of the ore is very small compared with the particle size of the coke and has a high density, so when the ore is charged on the sedimentary layer of the coke, the ore flowing into the central part of the furnace is Shaving off the upper layer of the coke layer,
It deposits while being entrained inside the ore layer, causing destabilization phenomena such as coke collapse, and between the coke layer and the ore layer, a mixed layer of coke and ore with a high packing density (closest packing layer)
Is formed.

This mixed layer is inferior in air permeability to the coke layer and the ore layer and has a great influence on 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 situation in the blast furnace, local high O / C portions in the blast furnace radial direction or the circumferential direction are likely to occur. Therefore, in high O / C operation,
It is important to understand the generation status of the mixed layer of coke and ore having a high packing density and control the thickness of the mixed layer in the radial direction or the circumferential direction of the furnace.

Therefore, in the present invention, in order to accurately control the distribution state of the charge layer after the start of firing, the O / C of 5.
High O / C of 0 or higher
Permeability (ventilation resistance) including intentionally forming an O / C charge layer and including a mixed layer of coke and ore in the high O / C charge layer
Is characterized in advance. And these O / C
Based on the air flow resistance value of the collected high O / C charge layer
O / C is 5.0 or more.The distribution condition of the charge in the furnace in high O / C operation is determined in advance, and the distribution of the charge layer after firing is controlled based on this condition, and the O / C is 5.0 or more. It is also characterized by an early transition to high O / C operations.

[0018]

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

Then, the ventilation resistance of the sample layer with a high O / C charge can be determined from the measured values of each layer structure as a ventilation resistance coefficient in the known gas pressure loss formula. More specifically, for example, the gas pressure loss formula (empirical formula) of Ergun, which expresses the gas pressure loss in the axial direction of the packed bed of isothermal and uniform particle size, is used. The resistance coefficient can be calculated. This Ergun's gas pressure loss equation is the pressure loss ΔP of the charging layer (packed bed) of layer thickness L is ΔP / L = − (f ₁ + f
₂ G) G, (where f ₁ and f ₂ are the ventilation resistance coefficient of the charging layer, G:
Gas mass velocity [kgf / (m ² · bed · s)]). Therefore, the ventilation resistance of the sample layer of high O / C charge is determined as f ₁ (laminar flow region) to f ₂ (turbulent flow region) of this equation. The ventilation resistance coefficient of the high O / C charging layer in the present invention is dominated by the turbulent flow region, and f ₂ is used as a representative value for the sake of simplicity. This ventilation resistance coefficient f ₂ is represented by f ₂ = 1.75 (1−ε) / g _c ρ _g φ d _p ε ³ in the Ergun gas pressure loss formula (where ε: sampling charge layer) Porosity of each layer, g _c : Gravity conversion coefficient [kg ・ m / kgf ・ s ² ], ρ _g : Gas density in the blast furnace [kgf / m ³ ], φ: Grain shape factor of each sample layer
(Flatness), φ = surface area of a sphere having a volume equal to the volume of the particle / surface area of the particle, and when the particle is a sphere, φ = 1,
Flat particles are φ ≤ 1, d _p : Particle size [m] of ore and coke in the collected charge layer, and harmonic mean diameter when particle size distribution is present.
d _p '= (Σ X _i / d _pf ) ^-1 , where X _i is each particle size d _pf
Weight fraction or volume fraction of [m]). 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, in the case where the high-O / C loading layer is composed of three layers, an ore layer, a mixed layer of ore and coke, and a coke layer, the ventilation resistance coefficient f ₂ of each of
Then, the air flow resistance coefficient f ₂ is weight-averaged from the layer thickness ratios of to, and the air flow resistance coefficient of the sample layer with a high O / C charge is defined as f ₂ .

As described above, the air flow resistance coefficient (air flow resistance) of a specific sampled high O / C charge layer is required. However, in the present invention, a high O / C charge layer having different O / C is used. , It is necessary to collect each of the multiple charge layers and obtain the ventilation resistance coefficient of multiple high O / C sample charge layers. Therefore, in the present invention, when ore and coke are sequentially charged into the blast furnace to form a charge layer, the O / C is different at the uppermost stage of the charge layer.
It is necessary to form more than one type of high O / C charge layer and to collect the charge layer having at least the ore layer, the mixed layer of ore and coke, and the coke layer, respectively, in the as-deposited state. Even if only the ore layer or the coke layer, which does not include the mixed layer of the coke and the ore having a high packing density (closest packing layer) between the coke layer and the ore layer, is obtained to obtain the ventilation resistance, the present invention The intended ventilation resistance of the high O / C charge layer cannot be grasped accurately. In addition, by simply obtaining the air flow resistance of a single high O / C charge layer, it is possible to obtain a high O / C with an O / C of 5.0 or higher.
The relationship between the O / C of the charge layer in the operation and the air flow resistance in the blast furnace, that is, the air flow resistance of the high O / C charge layer in the radial direction or the inner circumferential direction of the furnace in the high O / C operation The distribution cannot be obtained accurately.

In order to make the O / C of the high-O / C charging layer different, the O / C of the charging-target charging layer should be changed in the circumferential direction in the blast furnace so that Forming different O / C target charge layers in different directions, or forming and collecting O / C target charge layers at the same site in the blast furnace, and then discharging them to obtain different O It is preferable that the O / C of the high O / C charge layer is varied in the radial direction in the blast furnace by repeatedly forming and collecting the charge layer to be sampled for / C. This makes it possible to accurately determine the distribution of the air flow 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 high-O / C-charged layer and the ore of the high-O / C-charged layer in the radial direction in the furnace
From the distribution of the layer thickness ratio of coke, the accurate ventilation resistance distribution of the high O / C charge layer simulating the high O / C operation in the radial direction or the circumferential direction of the furnace is understood. The distribution of the ore / coke layer thickness ratio in the furnace radial direction or in the furnace circumferential direction is
It can be determined by actually measuring the ore / coke layer thickness ratio of the high O / C charging layer obtained by sampling a plurality of cases from the furnace radial direction or the furnace circumferential direction. The distribution of the ore / coke layer thickness ratio is measured by a conventional method, for example, JP-A-9-111321.
It is also possible to measure the surface profile and particle size distribution of the charge layer with a profile meter installed at the top of the blast furnace, as in Japanese Patent Publication No. Due to instability of the attachment state (collapse of coke layer and inflow of a large amount of ore toward the center of the furnace)
Accurate ore / coke layer thickness ratio distributions cannot be measured due to the poor reproducibility of the deposition profile for each charge. Therefore, the accurate distribution of the ore / coke layer thickness ratio in the furnace radial direction or in the furnace circumferential direction is
It is also a great advantage of the present invention that it can be obtained by actual measurement of the sample layer of high O / C charge.

And, a high O / C simulating this high O / C operation
Considering the charging material conditions assumed in actual high O / C operation from the distribution of air flow resistance in the charge layer, the local in the furnace radial and circumferential directions during high O / C operation are considered. To prevent the generation of high O / C and to increase the gas flow in the center of the blast furnace, determine the distribution conditions of the charge layer after start-up and during high O / C operation, and after start-up Controls the distribution of the charge layer. This control method is performed by using a known furnace top charging device such as changing the stroke of the armor plate or the tilting pattern of the bellless distribution chute for controlling the radial charge distribution in the furnace. .

As a method for collecting the charge layer to be collected in the actual blast furnace as it is in a deposited state, the present applicants have filed a patent application as Japanese Patent Application No. 8-250278.
It is preferable to use a sampling method of a granular material deposit and a sampling jig. In this method, a pipe is erected in advance at the intended collection site of the granular material deposit, and then the granular material is deposited at the intended collection site, and then the binder is applied to the periphery of the pipe from the opening provided in the pipe. This is a sampling method in which the powder particles are injected into the charge layer for sampling and the particles are joined together, and then the pipe is pulled up to collectively pull up the layered granular material deposit around the pipe, which is the sampling purpose.

With reference to FIG. 3, the method of collecting the high O / C charge layer according to the present invention using the method of Japanese Patent Application No. 8-250278 will be specifically described. First, in Fig. 3, the sampling jig is basically a pipe 1 longer than the thickness of the target sampling charge layer and a pipe on the charging layer provided at the tip of the long pipe 1. A stable spear-shaped anchor portion 5 and a flange (bottom plate) 6 provided above the anchor portion 5, at each target sampling charge layer position in the longitudinal direction of the pipe 1.
Along with the openings 2, 3 and 4 for discharging the binder, a plurality of protrusions (studs) 7 are provided around the pipe 1 at regular intervals in the radial direction of the furnace. This protrusion 7
Has the effect of increasing the adhesion between the pipe and the target collection charge layer and holding the target collection charge layer against the impact of pulling up the pipe, or the shock of subsequent measurement or handling. Demonstrate.

The openings 2, 3, 4 provided in the pipes
Is a mixed layer C2 of ore and coke, and a coke layer C, respectively.
1. The thickness of the charge layer of the ore layer C3 is calculated, and the binder to be injected is provided at a position above each layer so as to uniformly permeate the target charge layer. As a concrete example, a mixed layer C of ore and coke, which is the most important to collect,
The opening 2 corresponding to 2 has a coke charge layer thickness of L
Then, the pipe position from the flange 6 to 1.2 L is provided, and the opening 3 corresponding to the coke layer is provided at the pipe position from the flange 6 to 0.8 L.

Next, a sampling method using this sampling jig will be described. Low O / during start-up of blast furnace
The ore and coke of C are sequentially charged into the blast furnace to form a charge layer, and a pipe 1 as a sampling jig is placed at a target sampling site on the charging layer C0 accumulated in the furnace. The charge layer C
By embedding the anchor portion 5 in the 0, the charge layer C
Stand at a right angle to 0 (tilt at a certain angle to the radial direction of the furnace) (in Fig. 3, the pipe is shown to be upright for convenience). Then, the uppermost layer (low O /
C coke (C) and pig iron, assuming a high O / C operation that transitions after the start-up of blast furnace firing in the C-charging layer C0)
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. Then, the charging is stopped at the time when the high-O / C-charging layer for each sampling purpose of the coke layer C1, the mixed layer C2 of ore and coke, and the ore layer C3 is formed.

Next, after confirming the setting status, a resin injection operation is started. The resin injecting operation is performed by using a pump (not shown) outside the furnace through which a resin, which is a powdery or granular material binder, is passed from above the pipe of arrow A directly to the pipe port 10 or through a tube connected to the pipe port 10. It is pumped into the pipe and injected into the target charge layer around the pipe through the openings 2, 3 and 4 provided in the pipe, and allowed to penetrate into the granular material, and after a while, the resin is cured, Join the particles together. Here, if the tensile strength of the charge layer including the collected closest packed layer portion is 50 N / mm ² or more, and the bending strength is 80 N / mm ² or more, the collected charge layer has a layer thickness of It is preferable because strength and hardness that can withstand measurement tests such as distribution, particle size distribution, porosity, and shape factor measurement can be secured. Also, when the binder is a liquid resin containing a curing agent, the Rockwell hardness (according to JIS K7202) of the solidified resin of the collected charge layer is HRM5.
If it is 0 or more, the strength can be secured.

At the same time, above the charging layer (above the ore layer C3), toward the periphery of the pipe 1, the metal frame 8 is provided.
Is set, and the metal frame 8 is used as a resin liquid reservoir, and the binder is injected into the charging layer from above. When the resin permeates and hardens between the granular materials and the above-mentioned strength required for sampling is obtained, the pipe 1 is attached to the locking portion 9 provided at the upper end of the pipe with a wire or the like, and, for example, on the furnace top. Use a hoist installed to pull up, and pull up together with the target charge layer around the pipe. In this method, as described above, the pipe opening ratio, the resin viscosity, etc. can be adjusted sufficiently, so that the resin does not spread outside the range of the intended charge layer (cross flow of the resin), and the surroundings are relatively smooth. The target collection charge layer can be pulled up by separating it from the charge layer.

[0030]

EXAMPLES Next, examples of the present invention will be described. Inner volume 4
In a large 550 m ³ blast furnace, low O / C (O
Ore having a / C of 0 to 2.0) and coke were sequentially charged into the blast furnace to form a low O / C charge layer. Then, at the uppermost stage of the low O / C charging layer, C ₁ ↓ C ₂ ↓ O ₁ ↓ O ₂ ↓ using the movable armor under the charging conditions shown in Table 1 below.
A high O / C charge layer was formed by four batch charges (C: coke ,: O coke, numbers represent batch charge sequence). More specifically, C ₁ has the same layer thickness of 350 mm and C ₂ has a thickness of 650 mm, and only the O ₁ armor position is placed inside the furnace.
0mm (marked with X in Figure 1 and thin line), 450mm (marked with □ in Figure 1,
(Thick line), 650 mm (△ mark in Figure 1, dotted line)
The O ₁ drop position during O ₁ charging was sequentially moved to the inside of the furnace to change the O / C in the radial direction inside the furnace. In such batch charging, the distribution of the layer thickness ratio of ore and coke in the obtained high O / C charging layer is mainly determined by C ₂ and O ₂ .

[0031]

[Table 1]

By changing the positions of these O ₁ armors and changing the O / C in the radial direction in the furnace from the high O / C charging layer, as shown in FIG.
In the procedure shown in, the charge layers having the ore layer, the mixed layer of ore and coke, and the coke layer are sampled from the respective positions in the furnace radial direction, and the sampled charge layer X shown in FIG. ₁ was obtained. As shown in FIG. 4, the collected high O / C charge layer X ₁ is a coke layer C 1, a mixed layer C 2 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 charging layer, the porosity of the charging layer, the particle size of the particles, and the flatness of the particles were measured, and the collected high O / C was calculated from these measured values by the Ergun gas pressure loss equation. Coke layer C1 of the charge layer, mixed layer C2 of ore and coke,
The airflow resistance coefficient f ₂ of each ore layer C 3 is obtained, and the airflow resistance coefficient f ₂ is weighted averaged from each layer thickness ratio to obtain the sampling height.
The ventilation resistance coefficient f ₂ of the O / C charging layer was determined.

Ventilation resistance coefficient of the obtained high O / C charging layer
Figure 1 shows the distribution of f ₂ in the furnace radial direction. As you can see from Figure 1, the position of the movable armor is 250 mm (marked with × in Figure 1,
When the O ₁ drop position moves to the furnace wall side in the furnace radial direction with a thin line), the ventilation resistance around the furnace wall in the blast furnace is rising, and the central gas flow in the furnace is strengthened, It can be expected that the O / C can shift to high O / C operation of 5.0 or higher in a stable and early manner. On the contrary, the position of the movable armor is 650 mm (△ in Fig. 1).
(Marked, dotted line), the position where the O ₁ drop position is from the center in the radial direction of the furnace, the ventilation resistance around the furnace wall in the blast furnace decreases, weakening the central gas flow Accelerated, the shape of the cohesive zone in the furnace became W-shaped, the heat loss of the furnace wall increased and the furnace heat fluctuation occurred, causing operational troubles, and stable O / C with an O / C of 5.0 or higher. And it can be expected that the transition cannot be made early. This is because the extrusion position of the O ₁ armor, which is the underlayer of the O ₂ layer, causes the falling position of the O ₁ layer to move to the inside of the furnace, causing segregation of the ore grain size toward the furnace wall side, and the ventilation resistance around the furnace wall. This is because the value is decreasing.

Based on the air flow resistance distribution of the charge layer in the radial direction in the furnace, the central gas flow in the blast furnace was increased from the charge condition in the high O / C operation where the O / C was 5 or more. , To determine the distribution conditions of the radial load in the furnace in the high O / C operation with O / C of 5 or more, which suppresses the surrounding gas flow and does not produce a part with high local ventilation resistance, Based on this condition, after controlling the distribution state of the charge in the radial direction inside the furnace after the start-up of the blast furnace, the amount of pulverized coal injected was gradually increased to obtain a high O / C of 5.0 or higher. Shifted to C operation.

At this time, the tap ratio (t / day / m ³ ) and the pulverized coal ratio (k
g / t), coke ratio (kg / t), fuel ratio (kg / t), air flow (Nm ³ / m)
in) and enriched oxygen content (Nm ³ / min) over time are shown in Fig. 2.
As is clear from Fig. 2, the change in the amount of pulverized coal injected is
After burning for 15 days, the pulverized coal ratio is 50 kg / t, the pulverized coal ratio is 125 kg / t after 1 month, and the pulverized coal ratio is 170 kg / t after 1 year.Other tap ratio, coke ratio, fuel ratio, and air flow rate. Even in terms of the amount of enriched oxygen, the O / C was stable at an early stage one year after burning and stably.
It can be seen that has been shifted to a high O / C operation of 5.0 or higher. Moreover, it can be seen that these transitions are performed stably, as is clear from the change in the air flow rate.

Therefore, according to this embodiment, according to the blast furnace operating method of the present invention, when the blast furnace is turned on and started up,
From the overall blast furnace operation, a small amount of work is required to form and sample a high O / C charge layer that simulates or assumes O / C operation, and obtain the ventilation resistance of this sampled high O / C charge layer. By adding additional processes, it is possible to determine in advance stable operation conditions (charge distribution conditions in the furnace) in high O / C operation with an O / C of 5.0 or higher. It is demonstrated that a high O / C operation can be quickly and stably transferred.

[0037]

As described above, the method of operating a blast furnace of the present invention is particularly effective in a large blast furnace after firing and starting.
Especially 150 kg / t-O /
It enables C to shift to high O / C operation of 5.0 or higher at an early stage and stably. Moreover, this effect is industrially significant in that it can be easily achieved without significantly changing the conventional blast furnace operating method.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention and showing a distribution in a radial direction of a furnace of a ventilation resistance coefficient f ₂ of a collected high O / C charging layer.

FIG. 2 shows an embodiment of the present invention, in which the O /
It is explanatory drawing which shows the time-dependent change of a tap ratio, a pulverized coal ratio, a coke ratio, a fuel ratio, an air flow rate, and an enriched oxygen amount when C shifts to a high O / C operation of 5.0 or more.

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

FIG. 4 is an explanatory view showing a high O / C charging layer for sampling in the present invention.

[Explanation of symbols]

1: pipe, 2, 3, 4: pipe opening,
5: Anchor part, 6: Flange, 7: Protrusion (stud), 8: Metal frame, 9: Locking part,
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

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kentaro Nozawa, Kanazawa-cho, Kakogawa-shi, Hyogo 1 Kanazawa-machi, Kobe Steel Works, Ltd. Inside the Kakogawa Steel Works (72) Shunta Sakano, Kanazawa-machi, Kakogawa-shi, Hyogo Kobe Steel Works, Ltd. Kakogawa Works (56) Reference JP 58-34108 (JP, A) JP 63-230808 (JP, A) JP 54-37004 (JP, A) JP 4-350108 (JP, A) JP 10-90133 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C21B 5/00

Claims (5)

(57) [Claims] 1. When ore and coke are sequentially charged into a blast furnace to form a charge layer at the time of filling a raw material before firing and start-up of the blast furnace, the ore is provided at the uppermost stage of the charge layer.
(O) and coke (C) deposition weight ratio O / C is 5.0 or more,
And forming a high O / C charge layer having different O / C, and having at least an ore layer, a mixed layer of ore and coke and a coke layer from the high O / C charge layer, and O Multiple charge layers with different / C are collected in the piled state, and
By determining the ventilation resistance of the C charge layer, the O / C of 5.
The distribution condition of the charge in the furnace in high O / C operation of 0 or higher is determined in advance, and the distribution of the charge after firing is controlled based on this condition, and the high O / C of 5.0 or higher is controlled. C Blast furnace operation method characterized by shifting to operation. 2. A high O / C formed on the uppermost stage of the charging layer.
The method for operating a blast furnace according to claim 1, wherein the O / C of the charge layer differs in the radial direction in the blast furnace and / or the circumferential direction in the blast furnace. 3. The blast furnace operating method according to claim 1, wherein the ventilation resistance coefficient is obtained from the layer structure of the sampling charge layer. 4. The blast furnace operating method according to claim 1, wherein in the high O / C operation, pulverized coal of 150 kg / t-pig iron or more is blown into the blast furnace. 5. A pipe is erected in advance at the target collection site of the high O / C charge layer, and then the high O / C charge layer is deposited at the target collection site, and then a binder is applied around the pipe. High collection purpose
5. The target charge layer around the pipe is collected in a deposited state by injecting it into the O / C charge layer to bond the powdery particles together and then pulling up the pipe. The blast furnace operating method according to any one of claims.