JP2002363622A - Method for operating blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operating method for a blast furnace in which raising of the temperature in the side wall on a furnace bottom can easily be restrained. SOLUTION: The side wall temperatures at the furnace bottom are measured with a plurality of thermometers set in the side wall on the furnace bottom of the blast furnace, and a synthetic resin material having the calorie less than that of pulverized fine coal and the decomposition heat larger than that of the pulverized fine coal, is injected from a nozzle positioned at the upper part of the side wall on the furnace bottom in the direction where the measured temperature exceeds a preset control value.

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 capable of efficiently suppressing a rise in temperature at the bottom wall of a blast furnace.

[0002]

2. Description of the Related Art In recent years, the technology for repairing a blast furnace furnace body has been advanced, and the portion above the tuyere can be repaired regularly even in a working blast furnace to maintain the furnace body. Has become. However, the lower part of the blast furnace below the tuyere (hereinafter simply referred to as the “furnace lower part”) is
Due to the presence of slag, it is not possible to repair the lower part of the furnace during operation.

Therefore, the life of a blast furnace is determined by the degree of wear of the refractory bricks in the lower part of the furnace. Therefore, it is extremely important to suppress the wear of the bricks in the lower part of the furnace from the viewpoint of extending the life of the blast furnace, and various measures have been taken conventionally.

[0004] For example, thermometers are installed at a plurality of locations on the bottom wall of a blast furnace to continuously measure the temperature of the bottom wall of the furnace, and when the measured temperature exceeds a control value, a blade located above the measurement location is located. Titanium-containing ore is blown from the mouth to increase the viscosity of the hot metal and reduce the flow velocity of the hot metal to suppress brick wear. The diameter of the tuyere can be reduced to reduce the amount of hot metal dripped onto the furnace bottom in that direction.

In Japanese Patent Publication No. 59-10968, a change in the thickness of the solidified layer of hot metal formed on the inner surface of the refractory is estimated by measuring the heat flux at a plurality of locations on the furnace bottom. When the thickness becomes less than a predetermined thickness, a blast furnace that reduces the amount of air blown by mixing nitrogen gas and the like at the tuyere corresponding to the position of the solidified layer, grows the solidified layer, and prevents erosion of refractories. A method of operation is disclosed.

[0006] Further, the furnace bottom temperature and the furnace bottom side wall temperature are measured at a plurality of locations on the circumference of the blast furnace, and when the temperature of any one of them rises, the amount of air blown from the tuyere above that location is measured. An operation method for controlling erosion of a hearth brick by controlling a hot air control valve provided in a blower branch pipe (see Japanese Patent Laid-Open No.
No. 0-243207), and an operation method for reducing the amount of hot metal dropped into the furnace bottom and the temperature of the hot metal dropped by blowing water or steam from the tuyere while reducing the amount of air blown from the tuyere (Japanese Patent Laid-Open No. Hei 10-72607). Has been performed conventionally, and the effect has been confirmed.

However, these methods have the following disadvantages.

First, the method of injecting titanium-containing ore from the tuyeres has a risk of increasing the cost and hindering the operation of the blast furnace.

In the method of reducing the amount of air blown by reducing the tuyere diameter or by blowing nitrogen gas or the like from the tuyere, or by using a hot air control valve, in the recent high pulverized coal blowing operation, , The flammability of the pulverized coal will be reduced in the direction in which the air volume is reduced,
There is a concern that the balance may be lost in the circumferential direction of the blast furnace. If the blowing of pulverized coal is stopped in the direction in which the amount of blown air is reduced to avoid the above-mentioned imbalance, the temperature in front of the tuyere rises in the same direction, so that the balance in the circumferential direction is also impaired. There is a risk.

[0010] Further, when a hot air control valve is used or nitrogen gas is blown, it is necessary to install equipment for that purpose, which increases equipment costs. Also in the method of blowing water or steam from the tuyere, it is premised that the method is used in combination with the hot air control valve, so that an increase in equipment cost cannot be avoided.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of such a situation, and an object of the present invention is to reduce the efficiency of a portion of the furnace bottom side wall where bricks are expected to be worn due to a rise in temperature. It is an object of the present invention to provide a method for operating a blast furnace which can suppress the rise of temperature easily and in a relatively short time.

[0012]

Means for Solving the Problems To solve the above-mentioned problems, the present inventors have invented a synthetic resin material having a smaller calorific value than pulverized coal but having a larger heat of decomposition than pulverized coal instead of blowing pulverized coal from tuyeres. Injection can lower the temperature in front of the tuyere, thereby reducing the amount of hot metal dripped onto the furnace bottom, lowering the dropping hot metal temperature and suppressing the rise in the temperature of the furnace bottom side wall. Various studies were repeated based on this. As a result, RPF (Refuse Paper and Plastic FRP) made by extruding waste plastic and industrial waste paper as raw materials
uel) found that, as shown in Table 1, it satisfies the above conditions and can be used as a synthetic resin material for alternative blowing.

[0013]

[Table 1] The present invention has been made based on such findings, and the gist of the invention lies in the following blast furnace operating method.

The temperature of the furnace bottom wall is measured by a plurality of thermometers installed on the furnace bottom wall of the blast furnace, and the temperature is measured at a temperature higher than a predetermined control value. A method of operating a blast furnace in which a synthetic resin material having a smaller calorific value than pulverized coal and a decomposition heat larger than pulverized coal is blown from a nozzle.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for operating a blast furnace according to the present invention will be described in detail.

As described above, a feature of the method of the present invention is that the tuyere located above the place where the furnace bottom side wall temperature has increased is
The point is that a synthetic resin material having a calorific value smaller than pulverized coal and a decomposition heat larger than pulverized coal is blown through a nozzle. When such a synthetic resin material is blown from the tuyere, the temperature in front of the tuyere decreases, and the temperature of the gas flowing upward from the tuyere decreases. It is lower than that. Therefore, it is considered that the temperature of the furnace bottom side wall is lower in the direction in which the synthetic resin material is blown than in the other directions, and it is possible to suppress an increase in the temperature of the furnace bottom side wall.

To verify this, the present inventors tried a simulation using a blast furnace three-dimensional mathematical model disclosed in Japanese Patent No. 0333466. This model is
A model that analyzes the phenomena occurring in the blast furnace by solving the various reactions in the blast furnace using the difference method, using the input distribution data and the amount of hot air and auxiliary fuel injected from the tuyere as input data. It is. Table 2 shows the preconditions for the simulation.

[0018]

[Table 2] FIG. 1 is a diagram showing a part of a calculation mesh in a simulation, and is a diagram showing tuyere levels when divided into 24 in the height direction. It was divided into six in the circumferential direction. In FIG. 1, TY1 to TY6 each represent a tuyere. In the calculation,
Assuming that the furnace bottom side wall temperature increased between the tuyere TY3 and TY4, a simulation of switching the pulverized coal blown from TY3 and TY4 to a synthetic resin material was performed.

Table 3 shows the results of the simulation. In Table 3, Case 1 is a reference (base) for injecting only pulverized coal. The pulverized coal injection amount (mass) in Case 1 was set to 100%. Case 2
7, the pulverized coal injection was stopped at the tuyeres TY3 and TY4, and the RPF shown in Table 1 was used as a synthetic resin instead of the pulverized coal injected in the case 1 by 90 to 1
This is the case where the air is blown in the range of 30%. In cases 2 to 7, the tuyere front temperature, the dropping hot metal temperature, and the furnace bottom side wall temperature are:
Based on the temperature at the time of pulverized coal injection, it was shown as a comparative value (difference). The hot metal dropping amount ratio is a change ratio in the upper portions of the tuyeres TY3 and TY4.

[0020]

[Table 3] From the results shown in Table 3, when switching the pulverized coal injection to the injection of synthetic resin material, as described below,
The conditions necessary for lowering the dropping hot metal temperature and the hot metal dropping amount and lowering the furnace bottom side wall temperature can be confirmed.

As shown in Table 3, the amount of synthetic resin injected was 100% of the amount of pulverized coal injected (Case 3).
Or, when it is set to 110% (case 4), the dropping hot metal temperature becomes lower than in the case of pulverized coal injection (case 1), and the furnace bottom side wall temperature decreases. When the injection amount is increased to 114% (Case 5), the dropping hot metal temperature becomes the same as in the case of pulverized coal injection (Case 1), but the furnace bottom side wall temperature still shows a tendency to decrease. However, if the injection amount of the synthetic resin material is further increased to 120% or more (case 6) or more, the dropping amount of hot metal drops, but the dropping hot metal temperature rises more than when pulverized coal is blown, and the furnace bottom wall temperature decreases. Can not be.

On the other hand, if the blowing amount of the synthetic resin material is reduced to, for example, 90% with respect to the blowing amount of pulverized coal,
Excessive decrease in the hot metal temperature due to the decrease in the injected fuel becomes more remarkable than the effect due to the decrease in the amount of heat required for the decomposition of the synthetic resin material, and the cohesive zone is excessively decreased. The simulation results show that unless the amount of synthetic resin injected is more than 90% of the amount of pulverized coal injected, FeO will be present at the tuyere level, leading to a decrease in furnace heat, which is not preferable. .

Next, when blowing synthetic resin material,
The effect of the calorific value and the heat of decomposition of the synthetic resin material on the dropping hot metal temperature was simulated under the conditions shown in Table 2 using the same mathematical model as described above. that time,
The amount of synthetic resin injected is the same as that of pulverized coal, and the heat of decomposition of synthetic resin is the same as that of pulverized coal and only the amount of heat generated is changed. The case where only the decomposition heat was changed was examined.

The results are shown in FIG. 2 and FIG. FIG. 2 shows a case where the heat of decomposition of the synthetic resin material is the same as that of the pulverized coal. From this figure, the heat value of the synthetic resin material is the same as the heat value of the pulverized coal (in this case, 33600 × 10 ³ J / kg). If there is, the comparison value of the dropping hot metal temperature is the same as the case of pulverized coal injection,
Although it is 0 ° C., the dropping hot metal temperature decreases as the calorific value of the pulverized coal becomes smaller, and it can be seen that the dropping hot metal temperature decreases by about 20 ° C. due to a decrease of 8000 × 10 ³ J / kg.

Further, FIG. 3 in the case same as the calorific value is pulverized coal synthetic resin material, the decomposition heat decomposition heat of the pulverized coal of the synthetic resin material from FIG. (In this case, 420 × 10 3 ^{J /} kg ), The dropping hot metal temperature decreases, and the heat of decomposition is 820 × 1 which is 400 × 10 ³ J / kg larger than pulverized coal.
It can be seen that the dropping hot metal temperature drops by more than 10 ° C. at 0 ³ J / kg. When the heat of decomposition of the synthetic resin material is further increased to 1600 × 10 ³ J / kg, the temperature of the dropped hot metal drops by about 40 ° C.

The broken line shown in FIG. 2 indicates the heat of decomposition of the synthetic resin material.
Is 600 × 10 more than that of pulverized coal ³J / kg size
Simulation (when the dropping hot metal temperature drops by about 30 ° C)
This is the result of the action. The broken line shown in FIG.
The calorific value of the fat material is 8600 × 10 compared to pulverized coal³J / kg
Spots when the temperature is large (dropping hot metal temperature rises about 20 ° C)
This is the result of the simulation. From these results, the synthetic tree
Even if the calorific value of the fat material is larger than that of pulverized coal,
Is large enough for pulverized coal (for example, in the case of FIG. 3
Then, about 1100 × 10³J / kg or more
B), it can be said that the dropping hot metal temperature decreases.

In the operation method of the present invention, as described above,
Although a synthetic resin material having a calorific value smaller than that of pulverized coal and having a heat of decomposition larger than that of pulverized coal is blown, the above-mentioned FIG.
According to the results shown in FIG. 3 and FIG. 3, even if a synthetic resin material that does not simultaneously satisfy the above condition and uses one of the conditions is used, the dropping hot metal temperature can be reduced in calculation. However, it is difficult to accurately judge how large or small the heat of decomposition of the synthetic resin material or the calorific value is compared to pulverized coal, or if it is small, the dropping hot metal temperature can be lowered, and it cannot be considered in the simulation. It is considered that the intended effect may not be improved due to disturbances in the blast furnace such as unloading failure.

Therefore, the synthetic resin material to be blown in place of the pulverized coal in the operation method of the present invention uses a synthetic resin material having a smaller calorific value and a larger heat of decomposition than the pulverized coal. How small the calorific value is compared to pulverized coal,
There is no particular limitation as to how large the heat of decomposition is, but the calorific value is 3600 to 86
It is preferably 00 × 10 ³ J / kg smaller and the heat of decomposition is preferably 400 to 1300 × 10 ³ J / kg larger than pulverized coal.

Examples of such a synthetic resin material include the RPFs shown in Table 1 above. In addition, the deplasticized waste plastic shown in Table 1 has a higher decomposition heat than pulverized coal, but has a large calorific value, and thus cannot be used.

Table 3 shows the amount of synthetic resin material blown.
As described based on the results shown in (1), there is an appropriate range. Therefore, it is preferable to know in advance the appropriate blowing amount of the synthetic resin material to be used according to the operating conditions at the time of use. RPF was used as the synthetic resin material, and under the premise shown in Table 2, the blowing amount of pulverized coal was 100
In the case of (parts by mass), the amount is preferably more than 90 and less than 120 (all parts by mass).

As a method of blowing the synthetic resin material, a method may be adopted in which a nozzle for blowing is provided for each tuyere, and the nozzle is blown from the nozzle together with the carrier gas as in the case of blowing pulverized coal. A dedicated nozzle may be used, or when pulverizing the synthetic resin material, the pulverized coal may be blown from the pulverized coal blowing nozzle without being blown.

In carrying out the operation method of the present invention,
Thermometers are installed at several points on the bottom wall of the blast furnace, and the temperature of the bottom wall is measured with these thermometers. If the measured temperature exceeds a predetermined control value, the From the nozzle attached to the tuyere
The synthetic resin material is blown as described above.

The "predetermined control value" means, for example, a furnace bottom side wall temperature which is empirically recognized as being unfavorable in operation or furnace body management when the value exceeds the value in blast furnace operation. Good. Further, if there is another temperature determined based on a rational basis, it may be used. The “control value” may be the measured value of the furnace bottom side wall temperature itself, or may be used when the change width or the change speed of the measured value is used as the control value.

"Tuyere located above the temperature rising point" means that if the temperature of the furnace bottom side wall rises above the control value in one place (that is, one thermometer rises), (In this case, “directly above” refers to the azimuth from the center of the blast furnace and refers to the range of ± 3 °) when there is a tuyere. When there is no tuyere directly above, These are two tuyeres located on both sides of the temperature rise location and adjacent to the location. In addition, when there are a plurality of places where the temperature rises (the thermometers at a plurality of places rise), that is, when the places where the temperature rises are spread in an arc shape, both ends of the arc portion are sandwiched between the both ends of the arc portion. The term refers to two adjacent tuyeres and a tuyere located between them.

[0035]

EXAMPLE An operation experiment was carried out using a test blast furnace having an inner volume of 3 m ³ shown in FIG. 4, and the change in the furnace bottom side wall temperature after switching from pulverized coal injection to synthetic resin injection was measured.

As a method of the experiment, raw ore and coke were cut out alternately from the ore hopper 1 and the coke hopper 2 shown in FIG. 4 and charged alternately in layers in the furnace. And only synthetic resin (using RPF) is blown from two of the tuyeres 3 through a synthetic resin blowing nozzle 4 attached to them, and the remaining tuyeres 3 Only the pulverized coal was blown through the pulverized coal blowing nozzle 5 attached thereto, thereby bringing the apparatus into a steady state. At this time, the blown amount of the pulverized coal is set at 1 of the blown amount of the synthetic resin material (the blown amount per tuyere) so that the furnace bottom side wall temperature below the tuyere 3 into which the pulverized coal is blown increases. Doubled. In addition,
The exhaust gas was discharged from the gas outlet 6, and the generated hot metal and slag were periodically extracted from the tap hole 7.

After that, the blowing of the pulverized coal was switched to the blowing of the synthetic resin material, the temperature of the furnace bottom side wall was measured with a thermometer attached to the furnace bottom side wall, and the tuyere (from which the synthetic resin material was blown in from the beginning) The time required to lower the temperature to the furnace bottom side wall below the “synthetic resin material injection tuyere” was measured.

For comparison, when the hot air control valve is closed and the air flow rate is set to 0 (Comparative Example 1) for the tuyere in which pulverized coal is blown, the opening degree of the hot air control valve is also reduced. And the steam from the tuyere
In the case where g / min was blown (Comparative Example 2), the furnace bottom side wall temperature was measured in the same manner, and the time required for lowering the furnace bottom side wall temperature below the synthetic resin material blowing tuyere was measured.

Table 4 shows the results.

[0040]

[Table 4] As shown in Table 4, in the operation method of the present invention, after switching from pulverized coal blowing to synthetic resin material blowing, the temperature of the furnace bottom side wall below the synthetic resin material blowing tuyere dropped in 4 hours. In contrast, Comparative Example 1 requires 8 hours,
In Comparative Example 2, the time was 4 hours. The method of Comparative Example 2 was equivalent to the method of the present invention in terms of the effect of lowering the furnace bottom side wall temperature, but it can be said that the method of the present invention is advantageous from the viewpoint of equipment cost.

[0041]

According to the blast furnace operating method of the present invention, it is possible to easily suppress a rise in temperature at the bottom wall of the furnace and to suppress the wear of bricks. Cost burden on equipment and operation is also small.

[Brief description of the drawings]

FIG. 1 is a diagram showing a part of a calculation mesh in a simulation of a blast furnace three-dimensional mathematical model in the operation method of the present invention.

FIG. 2 is a diagram showing a result of a simulation of the operation method of the present invention, showing a relationship between a calorific value and a dropping hot metal temperature when a synthetic resin material having the same decomposition heat as pulverized coal is used.

FIG. 3 is a diagram showing a result of a simulation of the operation method of the present invention, showing a relationship between the decomposition heat and the dropping hot metal temperature when a synthetic resin material having the same calorific value as pulverized coal is used.

FIG. 4 is a longitudinal sectional view showing a configuration of a test blast furnace used in the example.

[Explanation of symbols]

 1: Ore hopper 2: Coke hopper 3: Tuyere 4: Synthetic resin material injection nozzle 5: Pulverized coal injection nozzle 6: Gas outlet 7: Tap hole

Claims (1)

[Claims] 1. A furnace bottom side wall temperature is measured by a plurality of thermometers installed on a blast furnace bottom side wall, and the measured temperature exceeds a predetermined control value. A method for operating a blast furnace, wherein a synthetic resin material having a calorific value smaller than that of pulverized coal and a decomposition heat larger than pulverized coal is blown from an attached nozzle.