JPH10298617A - Operation of blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blast furnace operational method which can improve the ventilation to the furnace core direction by a simple method, control gas flow in the furnace and execute the stable operation. SOLUTION: At the time of operating the blast furnace, a sonde provided with a load cell for measuring thrust at the time of inserting into the furnace, is inserted from a bosh part of the blast furnace above a tuyere 1 toward near the upper end of a raceway 2. When the average value of the thrust gradient at this time becomes <=80% of the average value of the thrust gradient of the sonde at the time of inserting similarly in the stopping of blasting, the sonde is inserted to further deep position and a raceway shell 9 formed from the bottom part of the raceway to the facing surface of the raceway is partially broken. By this method, the ventilation in the furnace core direction is improved and the gas flow in the furnace can be controlled.

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, and more particularly, to stabilizing the operation of a furnace by ascertaining the state of filling of inserts near the raceway from the furnace wall at the bottom of the furnace and maintaining this state. It relates to the blast furnace operation method to be designed.

[0002]

2. Description of the Related Art In the operation of a blast furnace, stable operation is often hindered by an increase or fluctuation of a blowing pressure or an abrupt increase in heat load in a furnace body (particularly, a lower part of the furnace). Therefore, maintenance of air permeability and reduction of furnace heat load are one of the important management items in daily operation management.

The causes of such an increase in the blowing pressure and a rapid increase in the thermal load in the lower part of the furnace include a gas flow in the raceway and a change in the lowering behavior of coke in the lower part of the furnace.

[0004] For example, when the charged state from the blast furnace wall to the vicinity of the raceway is in a sparse state, gas flows easily in that region, and the gas flow (furnace wall flow) near the furnace wall is dominant. And the heat load in the lower part of the furnace increases. In addition, particularly during the operation of injecting a large amount of pulverized coal, a raceway shell made of coke fines and slag is easily formed from the bottom of the raceway to the boundary of the raceway and a portion corresponding to the face of the tuyere. Air permeability in the core direction is impaired. At this time, the raceway develops upward and the furnace wall flow is promoted.

[0005] As means for improving the air permeability in the core direction, for example, in Japanese Patent Laid-Open No. 5-70814, when a core probe is pushed from the tuyere of a blast furnace and the pushing thrust at that time exceeds a control value, Heating means (hot gas, or fuel and supporting material, etc.) is supplied through a probe or a heating probe inserted in place of the probe to heat the core and activate the core to increase air permeability. A method for improvement is disclosed.

Japanese Patent Application Laid-Open No. 5-295410 discloses that the permeability of a blast furnace core deteriorates due to coke breeze,
When the reactor condition became unstable, iron materials such as scrap and granular iron were charged from the center of the furnace top, and carbon-unsaturated iron droplets were dropped into the core portion. A method is described in which the amount of coke breeze in the core part is reduced by carburizing the coke breeze to improve the poor air permeability.

[0007] However, if the above-mentioned conventional technique is to be implemented, it must be complicated in terms of equipment and structure, lacking in simplicity, and disadvantageous in terms of cost.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and has improved the air permeability in the direction of the reactor core by a simpler method to properly control the gas flow in the reactor. An object of the present invention is to provide a blast furnace operating method capable of performing a stable operation by controlling, suppressing an increase in heat load on a furnace wall, and extending the life of a blast furnace.

[0009]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventor first studied a method of measuring the charging state of the charge by measuring the thrust at the time of inserting the sound. As a result, as a means for measuring the thrust at the time of inserting the sonde, a sonde having a conical pressure receiving head at the tip used in the blast furnace operating method (Japanese Patent Application No. 8-342965) proposed by the present inventors was used. By applying the method of measuring the thrust at that time with a load cell by inserting it into the furnace from the blast furnace bosch part above the tuyere, it is possible to measure the filling state of the charge from the furnace wall to the vicinity of the upper end of the raceway Was confirmed.

Further, when the average value of the thrust gradient of the sonde is equal to or less than 80% of the average value of the thrust gradient at the time of calm, the sonde is inserted further deeply from the bottom of the raceway to the tuyere facing the raceway. The inventors have found that by partially destroying the formed raceway shell, it is possible to improve the air permeability in the core direction and to stabilize the operation of the blast furnace, and have accomplished the present invention. The average value of the thrust gradient of the sonde is defined as the insertion value for the change in the insertion depth of the sonde until the sonde is inserted into the furnace from the blast furnace bosh above the tuyere and reaches near the upper end of the raceway. The average value of the change in thrust.

The gist of the present invention resides in the following blast furnace operating method.

During operation of the blast furnace, when a sonde equipped with a load cell for measuring thrust during insertion into the furnace is inserted from the blast furnace Bosch section above the tuyere toward the vicinity of the upper end of the raceway, and inserted into the vicinity of the upper end. When the average value of the thrust gradient of the sonde becomes 80% or less of the average value of the thrust gradient of the sonde when it is inserted in the same manner as described above at the time of the calm, the sonde is inserted further deeply and from the bottom of the raceway. A method for operating a blast furnace, comprising partially destroying a raceway shell formed over a tuyere facing a tuyere of a raceway to improve air permeability in a core direction.

Here, the "average value of the thrust gradient of the sonde" is, as described above, the average value of the change of the insertion thrust with respect to the change of the insertion depth of the sonde. , The change of the insertion thrust with respect to each certain displacement is obtained, and these values are averaged. The “raceway shell formed from the bottom of the raceway to the tuyere of the raceway” refers to the fine coke or slag formed at the boundary of the raceway, as shown in FIG. 5 described later. This is a shell formed from the bottom of the raceway to the tuyere facing surface, that is, the part on the opposite side of the tuyere.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The blast furnace operating method of the present invention (hereinafter also referred to as the method of the present invention) will be specifically described.

First, a description will be given of the fact that it is possible to measure the charging state of the charge by measuring the thrust when inserting the sonde into the furnace.

FIG. 1 is a diagram schematically showing a gas flow depending on the charging state of charged particles, which is obtained by a two-dimensional flat plate model of a lower coke bed of a blast furnace.
This two-dimensional model has a width of 100 mm, a length of 500 mm, and a height of 900 mm.
The tuyere 1 protruding 1 mm and having an outer diameter of 13.8 mm is attached.

In the vicinity of the portion corresponding to the furnace wall of the two-dimensional model, three types of polypropylene particles having different porosity ε were filled, and the other regions were filled with polypropylene particles having the same porosity. Make up the system, tuyere 1
And air of 0.0244 m ³ / s was blown from the air to generate Raceway 2. FIG. 1A shows a case where the vicinity of the furnace wall is filled with polypropylene particles having a porosity ε = 0.5.
(B) is a case where polypropylene particles with a porosity ε = 0.6 are filled, and (c) is a case where polypropylene particles with a porosity ε = 0.7 are filled. When the charged state of the charge near the furnace wall is in a sparse state (when the polypropylene particles having a large porosity ε are filled near the furnace wall), the gas flow (see FIG. (Indicated by an arrow inside) indicates that the tendency of the furnace wall flow is large.

A sonde equipped with a load cell was inserted at a constant speed from the furnace wall of the two-dimensional model toward the upper end of the raceway, and the thrust at that time was measured by the load cell.

FIG. 2 is a diagram showing the relationship between the insertion depth of the sonde obtained at this time and the thrust at the time of insertion. Note that FIG.
(A) to (c) in FIG. 1 respectively correspond to (a), (b) and (c) in FIG.

As is apparent from this figure, the filling state of the charge (ie, the difference in the porosity of the polypropylene particles).
It was clearly confirmed that the magnitude of thrust at the time of insertion of the sonde and the average value of the thrust gradient were different. When the charged state of the charge near the furnace wall is in a sparse state (when polypropylene particles having a large porosity ε are filled near the furnace wall), the average value of the thrust gradient of the sonde becomes small.

FIG. 3 shows the results obtained using a hot blast furnace model apparatus (furnace height 5 m, hearth diameter 0.9 m, and furnace volume 3 m ³ ). FIG. 5 is a diagram schematically showing a relationship between an average value of a thrust gradient when the furnace wall is inserted up to and a furnace wall temperature immediately above a sonde insertion position (Bosch portion). In addition, the average value of the thrust gradient of the sonde on the horizontal axis was expressed as a ratio to the thrust gradient at the time of the calm.

According to the results shown in FIG. 3, the furnace wall temperature is higher as the average thrust gradient when the sonde is inserted from the furnace wall to the vicinity of the upper end of the raceway is smaller. Therefore,
The larger the average value of the thrust gradient at the time of inserting the sonde, the lower the furnace wall temperature, which is preferable for stable operation. In particular, when the average value of the thrust gradient measured during operation is 80% or less of the average value of the thrust gradient during a cold wind, the furnace wall temperature rapidly increases. Necessary to reduce body heat load.

As described above, it is possible to measure the filling state of the charge by measuring the thrust when the sonde is inserted into the furnace.
It is equipped with a load cell that can measure the thrust when inserted into the furnace.This sonde can be inserted into the furnace at an inclination angle that can measure the vicinity of the upper end of the raceway from the blast furnace Bosch section above the tuyere. is necessary.

As the sonde capable of measuring the thrust at the time of insertion into the furnace, a probe having a conical pressure receiving head at the tip end described in Japanese Patent Application No. 8-342965 is suitable. The reason for using a sonde equipped with a load cell is that it is inexpensive and easy to maintain.

The insertion of the sonde into the furnace from the blast furnace Bosch portion above the tuyere to the vicinity of the upper end of the raceway, that is, at an inclination angle at which the vicinity of the upper end of the raceway can be measured, will be described later. This is because, depending on the measured thrust gradient, the sonde is inserted deeper to partially destroy the raceway shell formed from the bottom of the raceway to the tuyere of the raceway. If a sonde is inserted into the furnace from the blast furnace bosh above the tuyere at an inclination angle that can measure near the upper end of the raceway, the tip of the sonde will cross the raceway boundary near the upper end of the raceway when the sonde is inserted deeper. This is because it can penetrate into the raceway, hit the raceway shell, and partially break it.
Note that the inclination angle and the installation position of the sonde may be the inclination angle and the installation position at which the vicinity of the height can be measured, using the height of the raceway predicted from the conventional operation experience as a guide.

The average value of the thrust gradient of the sonde is equal to 8 of the average value of the thrust gradient when the probe is inserted in the same manner as described above at the time of the calm.
When the sound becomes 0% or less, the sonde is inserted further deeply and the raceway shell is partially destroyed, as shown in FIG. As the raceway shell rises rapidly, by partially destroying the raceway shell, the air permeability in the direction of the core, which was hindered by the shell, was improved, and the gas flow in the furnace was properly controlled, and the furnace wall temperature was reduced. Can be restored to a normal value.

In the blast furnace operating method of the present invention, the above series of measurements and operations are performed during the operation of the blast furnace, and the effects are immediately reflected in the operation.

As described above, according to the method of the present invention, the air permeability in the core direction is improved, the gas flow in the furnace is appropriately controlled to stabilize the operation, and the heat load on the furnace wall is increased. The blast furnace life can be prolonged. In addition, the method can be easily implemented simply by using a sonde, and the cost is more advantageous than the conventional method described above.

[0029]

[Example] For a blast furnace with a furnace volume of 4800 m ³ ,
The operation was performed by the blast furnace operation method of the present invention.

The sonde used had an outer diameter of 8 as shown in FIG.
9.1 mm outer cylinder 3 and 17.3 mm outer diameter inner cylinder 4
The outer cylinder 3 is an air-cooled double pipe equipped with a load cell 5 for thrust measurement (maximum allowable load 2t). The tip of the sonde has a tip angle of 30.
A pressure receiving head 6 having a conical shape and a bottom surface of 45 mmφ was mounted.

As shown in FIG. 5, this sonde is passed through a blast furnace Bosch section (part A in FIG. 5) vertically above the tuyere 1 by 3 m at each of the four tuyere portions adjacent to each other, thereby forming a horizontal plane. It was installed so that it could be inserted in the direction of 60 degrees downward. By taking the inclination and installation position of the sonde in this way, it is possible to measure near the upper end of the raceway as described above, and the raceway shell can be partially broken when the sonde is inserted further deeply. it can.
FIG. 5 shows a raceway shell 9 formed from the bottom of the raceway 2 to the tuyere of the raceway.
Also shown.

Table 1 shows the specifications of the blast during operation.

[0033]

[Table 1]

During operation under these conditions, the furnace wall temperature increased by about 200 ° C. as compared with that during stable operation, and the sonde attached to the tuyere near the portion where the temperature was increased was moved to the upper end of the raceway boundary. It was inserted to the vicinity and the thrust gradient at that time was measured. At this time, since the average value of the thrust gradient was 70% of that during stable operation, the sonde was inserted further deeply to destroy the raceway shell.

FIG. 6 schematically shows the relationship between the insertion depth of the sonde and the thrust at this time. 6, the peak of the first thrust (labeled P ₁ in the figure) is a peak when the front end of the sonde passes through the raceway upper end (shown as P ₂ in the drawing) second peak race It is thought to indicate that Weschel was destroyed. Although the blowing pressure is also shown in FIG. 6, a sharp decrease in the blowing pressure was recognized in response to the destruction of the raceway shell (second peak).

One hour after the sonde was inserted as described above, the furnace wall temperature returned to the value at the time of stable operation. In addition, after the wind was shut off and the furnace was dismantled, it was confirmed that the raceway shell had been partially destroyed.

[0037]

According to the blast furnace operating method of the present invention, the air permeability in the direction of the core is improved, the gas flow in the furnace is appropriately controlled, the operation is stabilized, and the heat load on the furnace wall is increased. And prolong the life of the blast furnace. This method can be easily implemented simply by using a sonde, and is more advantageous in cost than the conventional method.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a gas flow depending on a charged state of charged particles, which is a result obtained by a two-dimensional flat plate model of a coke bed in a lower part of a blast furnace.

FIG. 2 is a diagram showing the relationship between the insertion depth of a sonde and the thrust at the time of insertion, obtained from a two-dimensional flat plate model of a coke bed in a lower part of a blast furnace.

FIG. 3 is a diagram schematically showing a relationship between an average value of a thrust gradient and a furnace wall temperature when a sonde is inserted from a furnace wall to a vicinity of an upper end of a raceway.

FIG. 4 is a diagram showing a schematic structure of a sonde.

FIG. 5 is a schematic explanatory view of a method for installing a sonde.

FIG. 6 is a diagram schematically showing a relationship between displacement of a sonde and thrust, obtained from an actual blast furnace.

[Explanation of symbols]

 1: Tuyere 2: Raceway 3: Outer cylinder 4: Inner cylinder 5: Load cell 6: Pressure receiving head 7: Furnace wall 8: Seal 9: Raceway shell

Claims (1)

[Claims] 1. During operation of a blast furnace, a sonde equipped with a load cell for measuring thrust at the time of insertion into the furnace is inserted from the blast furnace bosch portion above the tuyere to the vicinity of the upper end of the raceway, and inserted into the vicinity of the upper end. When the average value of the thrust gradient of the sonde at the time of the wind becomes 80% or less of the average value of the thrust gradient of the sonde when the windshield is inserted in the same manner as described above at the time of the calm, the sonde is inserted further deeply and the raceway is inserted. A method for operating a blast furnace, comprising partially destroying a raceway shell formed from a bottom portion to a tuyere-facing surface of a raceway to improve air permeability in a reactor core direction.