JP3247289B2 - 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 measures the state of a furnace core during the operation of a blast furnace or when the air is shut off, and activates the furnace core when starting up the air blow after the air shut off if there are signs of modulation. The present invention relates to a method for operating a blast furnace for improving the state of the core.

[0002]

2. Description of the Related Art A blast furnace for steelmaking can produce a large amount of pig iron,
Moreover, the thermal efficiency is as high as 90%. For this reason, the mainstream of pig iron production is maintained even today. However, since the blast furnace is a huge countercurrent moving bed, there are problems with productivity, production elasticity, etc., and further improvement in controllability is expected to ensure stable production and hot metal quality. It is rare. On the other hand, in the blast furnace,
From the viewpoint of strengthening the competitiveness of iron sources, operations using cheap raw fuels and operations with a high pulverized coal ratio are being implemented. Under such operations, the ore and coke are promoted to be powdered, the unburned char is generated, and the powder ratio at the lower part of the furnace increases, making it difficult to ensure the air permeability and liquid permeability of the furnace core. Cheap. Therefore,
It is desired to establish effective core activation technology.

[0003] As described above, the method of activating the core when the gas permeability and liquid permeability of the core of the blast furnace are reduced is not limited to the conventional method of increasing the fuel ratio or adding steam. Such a core activation method is disclosed. JP-A-6-0
In JP-A-93319 and JP-A-6-093320, it is necessary to measure the characteristics of the furnace core through a plurality of tuyeres every time the blast furnace is shut down, determine the state of the furnace core, and then require heating. A method is disclosed in which a hollow pipe is inserted into a furnace from a tuyere near a site to sample coke in a furnace core, thereby providing a vent in the furnace core.

Japanese Patent Application Laid-Open No. Hei 7-268416 discloses that a powder ratio of a furnace core portion is measured at the time of a cold wind or at the time of operation,
When the powder ratio is 20% or more, a hollow pipe is inserted into the furnace through a tuyere near a portion requiring heating and powder removal, and coke in the furnace core is sampled. A method of providing a ventilation hole has been proposed. On the other hand, Japanese Unexamined Patent Publication No. Hei 2-285013 discloses that a hot air control valve provided in a tuyere is operated to change the shape of a furnace core by changing the amount of air blown from the tuyere, thereby to change the shape of the furnace core / hearth. A method for improving liquid permeability is disclosed.

[0005]

SUMMARY OF THE INVENTION The above-mentioned JP-A-6-09
No. 3,319, JP-A-6-093320 and JP-A-7-268416, that is, by removing coke from the furnace core by sampling coke from the tuyere, a cavity is passed through the furnace core. The method of providing the air holes does not guarantee that the air holes in the hollow inside the furnace core formed by the coke sampling from the tuyere are reliably maintained at the time of starting the air blowing. Therefore, in this method, the effect of heating the coke, metal, and slag in the core by blowing a part of the high-temperature gas into the core and the effect of removing the powder are varied, and the expected effect is obtained. Also have a small effect.

On the other hand, a method disclosed in Japanese Patent Application Laid-Open No. 2-285013, that is, a method in which the amount of air blown from the tuyere is changed by a hot air control valve installed in each tuyere to change the shape of the furnace core. May take too much time before the liquid permeability of the core / hearth is improved. According to the conventional knowledge, it has been found that it takes 2 to 3 weeks or more to renew the core, and the time required for improving the liquid permeability of the core and the hearth by this technique is 1 hour. It is expected to last more than a month. Therefore, by operating the hot air control valve of each tuyere for a long period of time, the circumferential distribution of the air volume of each tuyere is unbalanced. It is not preferable for the operation of the blast furnace to unbalance the circumferential distribution of the air volume of each tuyere over such a long period.

[0007] Activation of the mandrel means to reduce the powder ratio in the mandrel and increase the mandrel temperature to improve the gas permeability and liquid permeability of the mandrel. From that point of view, the method of changing the shape of the furnace core and consequently improving the air permeability and liquid permeability of the furnace core and hearth is an indirect method, and its effect remains questionable. The present invention has been made in view of the problems of the conventional techniques described above, and has been developed in consideration of such problems as "bird's nest", which has an adverse effect on the air permeability and liquid permeability of the furnace core, that is, coke powder formed at the back of the raceway. Provided is a method for solving the above-described problems by reliably forming a hollow vent in a region where coke ash and slag are accumulated and a surface layer portion of a furnace core and efficiently blowing high-temperature hot air into the furnace core. It is intended to be.

[0008]

That is, the blast furnace operation method of the present invention has the following features. (1) When the blast furnace is operating or when the wind is shut down, the core state is measured,
When it is determined that the state of the furnace core is bad, when the blast furnace is closed, a hollow pipe is driven into the furnace core from the tuyere, and the blow-up is performed with the hollow pipe remaining in the furnace core. The air is blown into the core of the furnace, and the relative air flow in the tuyere into which the hollow pipe is driven is set to be 0.5 or more when the air flow is started. Then, one or two or more hot air control valves installed in the air ducts of tuyeres other than the tuyeres into which the hollow pipes are driven are throttled to control the air volume of the air ducts of each tuyere.

Alternatively, (2) measuring the state of the mandrel during operation of the blast furnace or when the wind is shut off, and if it is determined that the state of the mandrel is bad, driving a metal rod into the furnace core from the tuyere when the blast furnace is shut down. With the metal rod remaining in the furnace core, air is blown up, the metal rod is melted to form a vent in the furnace core, air is blown into the furnace core from the vent, and the blade is driven into the metal rod. In order to keep the relative air flow at the start of air blowing at the mouth (the value obtained by dividing the air flow at the air flow divided by the average air flow at the air flow) at least 0.5, the air flow into the air ducts at tuyeres other than the tuyere into which the metal rod is driven is set. The opening degree of one or more of the installed hot air control valves is reduced to control the air flow rate of the blowing branch pipe of each tuyere.

[0010] In particular, as a method for judging the state of the state of the mandrel, the temperature of the mandrel is measured by a probe during operation of the blast furnace or when the wind is shut off. A method of judging that the condition is bad, when the blast furnace is operated or when the wind is shut off, the powder ratio of the furnace core (for example, the weight ratio of coke having a particle size of 3 mm or less in all coke) is measured with a probe, and the powder ratio is 30%. In the above case, the method of determining that the state of the furnace core is bad, and measuring the thrust required when inserting the probe into the furnace core during operation of the blast furnace or when the wind is shut off, and when the thrust value is 5 t or more, the furnace The method of judging that the core condition is bad, measuring the insertion speed when inserting the probe into the furnace core during the operation of the blast furnace or when the wind is shut off, the insertion speed is 1400 ° C.
The method of determining that the core state is bad when the insertion speed is 0.7 times or less in the blast furnace, while operating the blast furnace, measure the air flow in each tuyere with the air flow meter installed in each tuyere. A method of judging that the core state is bad when there is a tuyere having a relative airflow volume of 0.9 or less, which is obtained by dividing the airflow volume by an average airflow volume, is effective.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, when a blast furnace is closed, a hollow pipe is driven into a furnace core from a tuyere by a portable driving device. In other words, this hollow pipe excavates the bird's nest formed in the back of the raceway and the poorly permeable area of the furnace core surface layer. Hot air of 800 to 1300 ° C. directly blown from the tuyere can be blown directly and forcibly through the hollow pipe. The hot air blown into the mandrel reacts with the coke in the mandrel and
It becomes a CO-rich reducing gas of 00 ° C., heats the coke in the furnace core and melts the metal slag held up in the furnace core. At the same time, since the solution loss reaction of the coke breeze in the mandrel also proceeds by heating the coke in the mandrel, the removal of the powder by heating the mandrel can be surely performed. Thereby, the gas permeability and liquid permeability of the furnace core are improved.

As described above, 800 blown from the tuyere
It is estimated that hot air of の 1300 ° C. can be blown directly and forcibly through this hollow pipe for about 30 to 60 minutes after the start of blowing. That is, after blowing 3
During about 0 to 60 minutes, hot air at 800 to 1300 ° C. was blown from the tuyere into which the hollow pipe was driven, at 100 to 200 Nm ^3.
/ Min should be blown into the furnace core. However, the outer diameter of the hollow pipe needs to be 100 mmφ or less in order to prevent damage to the tuyere due to contact with the tuyere (tuyere diameter: usually 140 to 150 mmφ) when driving the hollow pipe. The inner diameter of the pipe is 70
８０80 mmφ. Therefore, the amount of hot air blown from the tuyere into which the hollow pipe is actually driven into the furnace core through the hollow pipe is likely to be 50 Nm ³ / min or less, which is 0.3 or less in relative blow branch air flow. In order to improve the air permeability and liquid permeability of the furnace core as early as possible, it is desirable to blow a hot air volume of at least 0.5 relative blow air volume. This is because the relative airflow from the branch pipe is 0.
In the case of 4 or less, the amount of increase in the core temperature after the start of the blast is small, and the amount of increase in the core temperature after the start of the blast becomes only 100 ° C. or more when the relative blow branch air volume becomes 0.5 or more. .

Accordingly, in the present invention, the amount of hot air blown from tuyeres other than the tuyere into which the hollow pipe is driven is reduced, and the amount of hot air blown from tuyeres into which the hollow pipe is driven is secured. For that purpose, the opening degree of the hot air control valve installed in the air duct of the tuyere other than the tuyere into which the hollow pipe is driven is reduced. Here, it is necessary to reduce the opening degree of the hot air control valve until the relative air flow of the tuyere into which the hollow pipe is driven becomes 0.5 or more. The period during which the opening of the hot air control valve is reduced is between one day and several days. That is, even after the hollow pipe driven from the tuyere has melted and completely disappeared, the period in which the cavity formed in the furnace core is maintained continues.
In addition, when the hollow pipe driven from the tuyere melts and disappears completely, and the relative air flow of the tuyere into which the hollow pipe is driven becomes less than 1, the hot air control valve is returned to its original position. However, the time required to reach this point is about 30 to 60 minutes after the start of the air supply. The hot air control valve has various types such as a ball valve type and a butterfly valve type, and any type may be used.

In the present invention, a hollow pipe is usually driven from a plurality of tuyeres. Therefore, after the start-up ventilation starts 3
Hot air of 800-1300 ° C is generated between 0-60 minutes.
A high-temperature gas of about 2,000 ° C. generated by reacting with coke in the furnace core by blowing into the furnace core of 000 Nm ³ or more further raises the temperature of the coke in the furnace core, and also raises the temperature of the once solidified melt. Melts to improve air permeability and liquid permeability. Even after the hollow pipe melts and disappears, the shape of the cavity formed in the furnace core is maintained as it is for one to several days.
The gas permeability of the front and rear hot gases into the furnace core is ensured to some extent, and the furnace core can be quickly activated by heating and powder removal in the furnace core.

Such a furnace core improvement effect can also be achieved by driving a metal rod in place of the hollow pipe. In this case, the metal rod driven into the furnace core from the tuyere is heated and melted by a high-temperature gas of about 2000 ° C. generated by reacting with coke in the raceway, and a hollow vent is formed in the furnace core. You. After that, a part of the high-temperature reducing gas flows into the air holes of the cavities formed in the furnace core, and the coke, metal, and slag in the furnace core are heated, and a core improving effect is obtained.

From the viewpoint of the core improvement effect, the number of tuyeres for excavating the hollow pipe or the metal rod into the core is required to be at least four or more. Becomes larger. The number of tuyeres that can excavate a hollow pipe or a metal rod into the furnace core during the calm is different depending on the calm time, and the upper limit of the number of tuyeres that can be excavated when the calm time is 24 hours or less is at most 16 places. In addition, the minimum driving depth of the hollow pipe or the metal rod is 3 m because it is necessary to excavate a poorly permeable area between the bird's nest and the furnace core surface,
It is desirable that the actual driving depth is in the range of 3 to 7 m. The hollow pipe or the rod inserted into the furnace core is always exposed to a temperature close to 1400 ° C. even during a cold wind, and thus has a high possibility of buckling. Therefore, the material of the hollow pipe or the rod is of high quality with high temperature strength, for example, S
It is desirable to use a material having a high temperature strength equal to or higher than US304 or SUS304.

On the other hand, as a method of measuring the state of the furnace core, a known method can be applied. For example, at the time of cold, (1) a method of inserting a probe containing a thermocouple into the furnace core from the tuyere to measure the temperature, and (2) inserting a probe containing an optical fiber into the furnace core from the tuyere, (3) A hollow pipe probe is inserted into the furnace core from the tuyere to collect core coke, and the hysteresis temperature or powder ratio of the coke (for example, coke having a particle size of 3 mm or less) Weight ratio), or
(4) A method of determining the state (activity) of the furnace core from the insertion resistance and the insertion speed when inserting the probe from the tuyere into the furnace core can be implemented.

In (1), (2), and (3), when the core temperature is 1350 ° C. or less, in (3), the powder ratio of the furnace core is 30% or more, and in (4), the insertion thrust. (Resistance) is 5
When the insertion speed is not less than t or when the insertion speed is 0.7 times or less the insertion speed at a core temperature of 1400 ° C., it is possible to determine that the state of the core is poor. Further, as a measurement method during the operation of the blast furnace, there is a method of (5) determining from the relative air supply branch airflow obtained by dividing the air supply airflow at each tuyere by the average air supply airflow. Further, the blast furnace has a core mandrel that can perform sampling and temperature measurement during operation, and thus can measure the core temperature and the inserted thrust during operation. Also in this case, as in the case of the measurement at the time of calm, when the core temperature is 1350 ° C. or less, the powder ratio of the core part is 30% or more, the insertion thrust is 5 t or more, or the insertion speed is When the insertion speed at a temperature of 1400 ° C. is 0.7 times or less, or when there is a tuyere with a relative air flow rate of 0.9 or less in (5), it can be determined that the state of the furnace core is poor.

When the hollow pipe is driven from the tuyere, the material of the tip cap attached so that coke does not enter from the tip of the hollow pipe is to heat the furnace core in front of the hollow pipe driven into the furnace core. In the case of the main purpose, it is desirable to use STPG (normal steel) having a low high-temperature strength so that the tip cap is melted when the driving of the hollow pipe is completed.

Here, the hot air is high-temperature air or gas which is heated in a hot blast stove and blown from tuyere of a blast furnace. The temperature range of hot air is 800 to 13 for the following reasons.
00 ° C is desirable. That is, the hot air burns the coke in the furnace core through the hollow pipe driven into the furnace core to become a high-temperature reducing gas. The reducing gas temperature at that time is set to 200
In order to maintain the temperature at 0 ° C. or higher, the minimum temperature of hot air must be 800
° C. When the temperature of hot air exceeds 1300 ° C,
The temperature of the reducing gas generated by burning the coke in the furnace core through the hollow pipe driven into the furnace core becomes too high,
The SiO ₂ contained in the ash in the coke is volatilized to deteriorate the air permeability of the furnace core. Therefore, the upper limit temperature of the hot air is set to 1300 ° C.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific description will be given based on embodiments shown in the drawings. (Example 1) The inner volume is 4000 m ³ or more and the number of tuyeres is 38
In this large blast furnace, when the core temperature was measured with a probe at the time of the stall, the temperature was 1320 ° C. Since this temperature was 1350 ° C. or less, it was determined that the air permeability and liquid permeability of the furnace core were deteriorated. So, at the time of the calm,
In the manner shown in FIG. 1, eight tuyeres (No. 1, N
o. 9, No. 13, No. 19, no. 23, no.
29, No. 30, no. From 35), a hollow pipe was driven into the furnace core. That is, first, using a portable pipe driving device 1 and a driving jig 2 for driving by combining an air hammer and a hydraulic pressure, first, a cap 3 for preventing intrusion of core coke is provided at a tip thereof. The hollow pipe 4 was driven into the furnace core 6 from the tuyere 5. Next, the front end of the hollow pipe 7 having a length of 1 m was connected to the rear end of the hollow pipe 4 and then driven so that the front end of the hollow pipe 4 was at a depth of 3 m from the furnace wall.

The hollow pipe 4 having a tip portion of 2 m in length is used.
The joint portion between the pipe and the hollow pipe 7 having a length of 1 m was subjected to a cutting process as shown in FIG. 2 to change the wall thickness so that the fitting was successful. The material of the cap 3 for preventing the core coke from intruding is STPG so that it is melted when the hollow pipe 4 is brought into the depth of 3 m from the furnace wall.
(Ordinary steel). Further, the gap between the hollow pipe 7 and the tuyere 5 at the time of completion of the driving of the pipe so that the hot air of 800 to 1300 ° C. sent from the tuyere is directly and forcibly blown into the furnace core when the blower is started. Was filled with Bota 8.

As shown in FIG. 2, at the time of the start of the air blowing after the suspension of the wind, the 30 tuyeres (Nos. 2 to 8, No. 10 to 12, No. 14) other than the hollow pipe are driven. ~
18, No. 20-22, No. 24 to 28, no. 3
Nos. 1-34, no. The hot air control valves of Nos. 36 to 38) were squeezed so that the relative blowing airflow of the eight tuyeres into which the hollow pipe was driven was 0.5 or more. In this way, the start-up of the air supply after the wind shuts down smoothly, and as shown in FIG. 4, there were many fluctuations in the load such as slippage before the wind shuts down and fluctuations in the wind pressure tended to decrease after the wind shuts down. One month later, the core temperature at the time of the outage was 1460 ° C., which was 140 ° C. higher than the temperature of the core at the time of the previous outage. As a result, the discharge of slag became smooth at the same time as the hot metal, and the slag rate, which indicates the rate of slag discharge within the tapping time, was improved from 60% to 95%.

(Example 2) In a large blast furnace having an inner volume of 4000 m ³ or more and a tuyere number of 38, the insertion thrust required for inserting the probe into the core of the furnace at the time of wind shut down was measured to be 7 t. Was. Since this value was 5 t or more, it was determined that the gas permeability and liquid permeability of the furnace core were deteriorated. Therefore, at the time of the calm, a hollow pipe was driven into the furnace core from any ten tuyeres in the manner shown in FIG. That is, first, using a portable pipe driving device 1 and a driving jig 2 for driving by combining an air hammer and a hydraulic pressure, first, a cap 3 for preventing intrusion of core coke is provided at a tip thereof. The hollow pipe 4 was driven into the furnace core 6 from the tuyere 5. Then length 1
m after connecting the tip of the hollow pipe 7 to the rear end of the hollow pipe 4,
m depth.

A hollow pipe 4 having a tip portion of 2 m in length is used.
The joint between the hollow pipe 7 and the hollow pipe 7 having a length of 1 m was subjected to a cutting process as shown in FIG. 3 to change the wall thickness so that the fitting was successful. The material of the core 3 for preventing coke from entering the furnace core was STPG (normal steel) so that it was melted when the hollow pipe 4 was driven into the furnace wall to a depth of 3 m. Further, the gap between the hollow pipe 7 and the tuyere 5 at the time of completion of the driving of the pipe so that the hot air of 800 to 1300 ° C. sent from the tuyere is directly and forcibly blown into the furnace core when the blower is started. Was filled with Bota 8.

At the time of the start of the air supply after the end of the calm, the hot air control valves at the 28 tuyeres other than those at which the hollow pipes were driven were squeezed, and the relative blowing airflow at the 10 tuyeres at which the hollow pipes were driven was reduced. 0.5 or more. Thus,
As shown in FIG. 5, the start-up of the blast after the wind shuts off smoothly, and as shown in FIG. One month later, the thrust inserted into the furnace core when the wind was shut down was 3t, which was less than half that of the previous time when the wind was shut down. As a result, the discharge of slag becomes smooth at the same time as the hot metal, and the slag rate, which indicates the rate of slag discharge within the tapping time, is from 60% to 85%.
Improved.

(Example 3) In a large blast furnace having an inner volume of 4000 m ³ or more and 38 tuyeres, three tuyeres (No. 1, N
o. 9, No. 25) It was detected, and it was determined that the air permeability and liquid permeability of the furnace core were deteriorated. Therefore, when the blast furnace is closed next time, the tuyeres with three relative air blower airflows at 0.9 or less and the tuyeres near them, that is, the tuyeres with relative air blower airflows at 0.9 or less. A total of nine tuyeres (No. 38, No. 1, No. 2, No. 8, No. 6) of the tuyeres on both sides.
9, No. 10, No. 24, no. 25, no. 2
From 6), a hollow pipe was driven into the furnace core in the manner shown in FIG.

That is, a portable pipe driving device 1 for driving by first combining an air hammer and a hydraulic pressure.
First, a 2 m long hollow pipe 4 provided with a cap 3 for preventing ingress of furnace core coke at the tip was driven into the furnace core 6 from the tuyere 5 using the driving jig 2. Next, the tip of the hollow pipe 7 having a length of 1 m was connected to the rear end of the hollow pipe 4 and then driven so that the tip of the hollow pipe 4 had a depth of 3 m from the furnace wall.

The hollow pipe 4 having a tip portion of 2 m in length is used.
The joint between the hollow pipe 7 and the hollow pipe 7 having a length of 1 m was subjected to a cutting process as shown in FIG. 3 to change the wall thickness so that the fitting was successful. The material of the core 3 for preventing coke from entering the furnace core was STPG (normal steel) so that it was melted when the hollow pipe 4 was driven into the furnace wall to a depth of 3 m. Further, the gap between the hollow pipe 7 and the tuyere 5 at the time of completion of the driving of the pipe so that the hot air of 800 to 1300 ° C. sent from the tuyere is directly and forcibly blown into the furnace core when the blower is started. Was filled with Bota 8.

At the time of the start of air blowing after the suspension of the wind, 29 tuyeres (No. 3 to No. 3) except for driving the hollow pipe were used.
7, No. Nos. 11 to 23, No. The hot air control valves of Nos. 27 to 37) were squeezed so that the relative air blowing air volume at nine tuyeres into which hollow pipes were driven was 0.5 or more. Thus, the start-up of the blast after the cessation of the wind was smooth, and the relative blast-branch airflow of the three tuyeres whose relative blast-branch airflow was 0.9 or less was significantly improved one day after the blast-start. Both were around 1.0, and as shown in FIG. 6, the load fluctuation such as slip and the wind pressure fluctuation, which were often before the wind shuts down, showed a decreasing tendency after the wind shuts down. Then, one week after the start of the ventilation, the temperature of the bottom brick of the furnace bottom, which had been decreasing until before the closing of the wind, started to rise, and reached the temperature level at the time of good condition three weeks later, the furnace core was activated. I knew that The discharge of slag became smooth at the same time as the hot metal, and the slag rate, which indicates the rate of slag discharge within the tapping time, improved from 60% to 90%. In addition, the temperature of the bottom wall of the furnace rose along with the rise of the temperature of the bottom brick of the furnace bottom, and the annular flow, which is the main factor of shortening the life of the furnace, could be suppressed.

[0031]

According to the method of the present invention, when it is determined that the state of the core of the blast furnace is bad, a hollow pipe or a metal rod is driven into the tuyere when the blast furnace is closed, and a hollow pipe or a metal rod is driven when the blast is started. By narrowing the opening of the hot air control valve of the tuyere other than the tuyere, the flow rate of the high temperature gas of about 2000 ° C into the furnace core is greatly increased, thereby efficiently and promptly increasing the temperature of the furnace core and the core. The hearth can be activated.

By implementing the method of the present invention, it is possible to continue the operation for increasing the fuel ratio over a long period of time as in the prior art,
The problem that the tapping rate decreases over a long period of time because the furnace condition cannot be restored early can be completely solved. In the future, as at the time of operation using low-cost raw fuel and high pulverized coal ratio, the ore and coke will be pulverized, and the unburned char will increase the powder rate at the lower part of the furnace. The stable operation can be maintained even when it is difficult to ensure the air permeability and the liquid permeability of the liquid. Furthermore, since the annular flow can be eliminated by the present invention, it is not necessary to increase the fuel ratio or suppress the tapping amount as a countermeasure against the annular flow, so that the controllability of the blast furnace is improved.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a method of driving a hollow pipe into a furnace core according to the present invention.

FIG. 2 is a tuyere condition of a blast furnace used in an embodiment of the present invention and a hot air control valve (B) in which a throttle operation is performed in the first embodiment.
Explanatory diagram showing the positional relationship of

FIG. 3 is an explanatory view showing a connection state of hollow pipes for driving a furnace core.

FIG. 4 is a transition diagram of the operation index before and after the present invention is implemented in the first embodiment.

FIG. 5 is a transition diagram of an operation index before and after implementation of the present invention in a second embodiment.

FIG. 6 is a transition diagram of an operation index before and after implementation of the present invention in a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Portable pipe driving apparatus 2 Pipe driving jig 3 Cap 4 Hollow pipe (2 m) 5 Tuyere 6 Furnace core 7 Hollow pipe (1 m) 8 Button 9 Annular pipe A Tuyere into which hollow pipe or metal rod was driven Tuyere with narrow opening of hot air control valve

Continued on the front page (72) Inventor Masaaki Nakayama 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Inside the Kimitsu Works (72) Inventor Masahiro Toki 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Inside Kimitsu Works (72) Inventor Akihiko Shinotake 20-1 Shintomi, Futtsu-shi, Chiba Nippon Steel Corporation Technology Development Division (56) References JP-A-3-260004 (JP, A) JP-A-6 -122907 (JP, A) JP-A-8-302407 (JP, A) JP-A-63-118005 (JP, A) JP-A-9-170006 (JP, A) (58) Fields investigated (Int. . ^7, DB name) C21B 5/00 C21B 7/24

Claims (5)

(57) [Claims] 1. The furnace core state is measured during operation of the blast furnace or when the wind is shut off, and when it is judged that the furnace core state is bad, a hollow pipe is driven into the furnace core from the tuyere when the blast furnace is shut down. Ventilation start-up is performed with the hollow pipe remaining in the furnace core, and air is blown into the furnace core from the hollow pipe, and the relative air supply pipe air volume at the time of air supply startup of the tuyere into which the hollow pipe is driven (air supply pipe air volume) Is divided by the average air volume of the blower pipe) to be 0.5 or more, so that one or two or more hot air control valves installed in the blower pipes of tuyeres other than the tuyeres into which the hollow pipes are driven are installed. A blast furnace operation method characterized by controlling the air flow rate of each tuyere by narrowing the opening. 2. The state of the mandrel is measured during operation of the blast furnace or when the wind is shut off. If it is determined that the state of the mandrel is bad, a metal rod is driven into the furnace core from the tuyere when the blast furnace is shut down, Is blown up with the steel remaining in the furnace core, the metal rod is melted to form a vent hole in the furnace core, and air is blown into the furnace core from this vent hole and air is blown from the tuyere into which the metal rod is driven. It was installed in the tuyere of the tuyere other than the tuyere into which the metal rod was driven so that the relative blower pipe airflow at startup (the value obtained by dividing the air blower pipe airflow by the average blower pipe airflow) was 0.5 or more. A method for operating a blast furnace, characterized in that the opening degree of one or more hot air control valves is reduced to control the air flow rate of a blow branch pipe of each tuyere. 3. A probe for measuring the temperature and / or powder rate of the core at the time of operation of the blast furnace or when the air is shut off, and when the temperature of the core is at least 1350 ° C. or the powder rate is 3
The blast furnace operating method according to claim 1 or 2, wherein the core state is determined to be bad when the blast furnace state is 0% or more. 4. The thrust required for inserting the probe into the furnace core and / or the insertion speed at the time of operation of the blast furnace or when the wind is shut off is measured, and at least the thrust at the time of insertion is 5t or more. Or the speed at the time of insertion is furnace temperature 1400
3. The blast furnace operating method according to claim 1, wherein the furnace core state is determined to be bad when the insertion speed at 0.7 [deg.] C. is 0.7 times or less. 5. When operating a blast furnace, measure the air flow of each tuyere with an air blower air flow meter installed for each tuyere,
The blast furnace operating method according to claim 1 or 2, wherein when there is a tuyere having a relative air blowing branch air volume of 0.9 or less, which is obtained by dividing the average air blowing air volume, the blast furnace state is determined to be bad.