JPH08302407A - Operating method of furnace - Google Patents

Abstract

PURPOSE: To activate the core part in furnace in starting the operation when the air-blowing is stopped in the case where any abnormality is diagnosed in the core part. CONSTITUTION: A hollow tube 4 on a metallic rod is driven in a core part of furnace from a tuyere 5 when the air-blowing is stopped in a blast furnace, the air-blowing is started while the hollow tube 4 or the metallic rod is left in the core part, and the hot gas is fed therein to activate a core part 6 and/or a hearth. The core part and/or the hearth is efficiently activated through the combination with the furnace core measuring method. In addition, the air volume in the air-blowing branch tube of each tuyere 5 is measured by an airflow meter of the air-blowing branch tube installed on each tuyere 5, and the circumferential balance of the core part is evaluated by the mean air volume of the air-blowing branch tube to more efficiently activate the core part 6 and/or the hearth.

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, in which the state of the furnace core is measured during operation, and if there is a sign of modulation, the furnace core is activated when the air is blown up and when air is blown up. .

[0002]

2. Description of the Related Art A blast furnace for iron making can produce a large amount of pig iron and has a high thermal efficiency of 90%. Therefore, the mainstream of pig iron production is still maintained. However, since the blast furnace is a huge countercurrent moving bed, it has problems in productivity, production elasticity, etc., and further improvement of controllability is desired in order to secure a stable production amount and hot metal quality. ing. On the other hand, in the blast furnace, from the viewpoint of strengthening the cost competitiveness of the iron source, cheap raw fuel operation and high pulverized coal ratio operation are being implemented. Under the above-mentioned operation, the powder ratio of ore / coke increases, and the powder ratio in the lower part of the furnace containing unburned char increases, which makes it difficult to secure air permeability and liquid permeability of the furnace core. Therefore, establishment of an effective furnace core activation technique is desired.

As a method for activating the core when the air permeability and liquid permeability of the core are lowered, there are several core activation methods other than the conventional fuel ratio increase and steam addition. It is disclosed. JP-A-6-93319 and JP-A-6-93319
In Japanese Patent No. 93320, the characteristics of the furnace core portion are measured through a plurality of tuyere for each wind break to determine the state of the furnace core portion, and a hollow pipe is inserted from the tuyere in the vicinity of a required heating portion. A method is disclosed in which a vent is provided in the core by sampling coke in the core. Also, Japanese Patent Application No. 6-8378
According to the publication No. 3, the core powder ratio is measured at rest or during operation, and when the powder ratio is 20% or more, a hollow pipe is inserted from a tuyere in the vicinity of the heating-required / powder-removed portion to form coke in the core. A method for providing a hollow vent hole in the furnace core by sampling is proposed.

[0004]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
19, Japanese Patent Application Laid-Open No. 6-93320, Japanese Patent Application No. 6-
In the method shown in No. 83783, that is, the method of taking out the coke in the core by the tuyere coke sampling and providing a hollow vent hole in the furnace core, the passage of the cavity in the core formed by the tuyere coke sampling is performed. There is no guarantee that the pores will be reliably maintained when the air is blown up. Therefore, in the above method, the heating effect and the powder removal effect of the coke-metal slag in the core caused by blowing a part of the high-temperature gas into the core of the core vary, and the effect is as expected and the effect is expected. Small cases occur.

In view of such conventional problems, the present invention surely forms hollow vent holes in the bird's nest and the core surface layer, which adversely affect the permeability of the core, The object of the present invention is to solve the above-mentioned problems by efficiently blowing hot air at high temperature.

[0006]

Means for Solving the Problems That is, the present invention has been made to solve the above-mentioned problems, and the gist thereof is (1) a hollow pipe from a tuyere to a core of a blast furnace when the wind is off. It is characterized in that the air is blown into the furnace core, air is blown up while the hollow pipe remains inside the furnace core, and the air is blown from the hollow pipe into the furnace core. (2) When the blast furnace is in a blast, a gold rod is driven into the furnace core from the tuyere, air is blown up while the gold rod remains in the furnace core, the gold rod is melted, and a vent hole is formed in the furnace core. Is formed, and the air is blown into the furnace core through the ventilation holes.

(3) When the core state is measured during operation of the blast furnace or while the wind is off and it is determined that the core state is poor, the hollow pipe is inserted from the tuyere into the core when the blast furnace is off. It is characterized in that the air is blown into the furnace core while the air is blown into the furnace core while the hollow pipe is left inside the furnace core. Further, (4) when the core state is measured during the operation of the blast furnace or during idle time, and when it is determined that the core state is poor, a gold rod is driven into the core from the tuyere when the blast furnace is idle,
Blast start-up with the gold rod remaining in the furnace core,
It is characterized in that the gold rod is melted to form a vent hole in the furnace core, and air is blown into the furnace core through the vent hole. Also,
(5) In the above (3), the relative air flow amount of each air duct measured by the air flow amount of each tuyere was measured by the air flow amount meter of each air duct installed in each tuyere during the operation of the blast furnace, and the relative air flow amount of the air flow was divided by the average air flow amount.
It is characterized in that a tuyere of 9 or less is detected, and a hollow pipe is driven into the furnace core from a tuyere having a relative air flow amount of 0.9 or less and / or a tuyere in the vicinity thereof when the blast furnace is in a blast. .

(6) In the above (4), a relative blast branch pipe obtained by measuring the blast tributary air volume of each tuyere with a blast tributary air flow meter installed for each tuyere during blast furnace operation and dividing by the average blast tributary air volume A tuyere with an air volume of 0.9 or less is detected, and when the blast furnace is inactive, the relative blast branch pipe air volume of 0.9 or less and / or
Alternatively, it is characterized in that a gold rod is driven into the furnace core from a tuyere in the vicinity thereof. (7) In the above (1), (3) or (5), the air is blown from the tip of the hollow pipe and / or the hole opened in the hollow pipe. Further, (8) the above (1) or (3) or (5)
Alternatively, in (7), a metal pipe containing a ceramic sleeve is used as the hollow pipe.

[0009]

In the present invention, when the blast furnace is in a blast, the hollow pipe is driven into the furnace core from the tuyere by a portable driving device.
This hollow pipe is composed of powder and As
In order to excavate the bird's nest, which is a shell of coke using h as a binder, and the area with poor air permeability in the surface layer of the furnace core, it is normally used in the furnace core with a small amount of high-temperature gas flow from the tuyere when the blast is started. The blown hot air of 800 ° C to 1300 ° C can be blown directly and forcibly through the hollow pipe. The hot air blown into the furnace core reacts with the coke in the furnace core to consume the powder coke, and at the same time becomes a CO-rich reducing gas near 2000 ° C., which heats the coke in the furnace core and simultaneously holds up in the furnace core. Dissolves the metal slag that is playing.

By heating the coke in the furnace core, the solution loss reaction of the powder coke in the furnace core also proceeds, so that the heating and powder removal in the core can be reliably advanced. Therefore, the air permeability and liquid permeability of the furnace core are improved. As mentioned above, 800 ° C to 1 that is blown from the tuyere when the air blow is started
Hot air at 300 ° C can be blown directly and forcibly through this hollow pipe in 3
It is estimated to be around 0 minutes. That is, within about 30 minutes after blowing air, 800 ° C to 1 ° C from the tuyere into which the hollow pipe was driven.
Hot air of 300 ° C. is blown into the core of 100 to 200 Nm ³ / min.

In the present invention, since hollow pipes are driven from several tuyeres, 800 ° C. to 1 ° C. within about 30 minutes after blowing air.
Hot air at 300 ° C. is blown into the core of 20,000 to 30,000 Nm ³ and reacts with the coke in the core to consume the powder coke, and at the same time, the high temperature gas of around 2000 ° C. generated the coke in the core. The temperature is raised and the melt is heated and fused to improve air permeability and liquid permeability. Even after the hollow pipe melts and disappears, the shape of the cavity formed in the core is maintained for 1 to several days. Therefore, the core of the high temperature gas around 2000 ℃ generated by reacting with the coke in the raceway The air permeability to the inside is ensured to some extent, and the furnace core can be quickly activated by heating and removing powder in the furnace core.

The above-mentioned effect of improving the core is also exhibited by driving a gold rod instead of the hollow pipe. In this case, a gold rod driven into the furnace core from the tuyere generated hot air of 800 ° C. to 1300 ° C. blown from the tuyere when the air was blown up by reacting with coke in the raceway.
It is heated and melted by a high temperature gas of around 00 ° C to form a hollow vent hole in the furnace core, and a part of the high-temperature reducing gas flows into the hollow vent hole formed in the furnace core to form coke in the furnace core.・
The metal slag is heated and the core improvement effect is exhibited.

From the viewpoint of the core improvement effect, the number of tuyere for digging a hollow pipe or a gold rod into the furnace core is required to be at least 4 or more, and the larger the number of tuyere for digging into the core, the greater the effect of improving the core. . The number of tuyere that can be used to excavate a hollow pipe or a gold rod into the furnace core during rest time depends on the rest time.
The maximum number of tuyere that can be excavated when the time is less than 30 is 30. In addition, the minimum driving depth of the hollow pipe or gold rod is 2 m because it is necessary to excavate the bird's nest and the area with poor air permeability of the core surface layer, and the driving depth is 2 m to 7 m.
It is desirable to set it in the range of m.

The hollow pipe or the gold rod driven into the core of the furnace is always exposed to a temperature range of about 1400 ° C. even when the wind is off, so that it is likely to buckle. Therefore, it is desirable to use, as the material of the hollow pipe or the gold rod, a material having high strength at high temperature, such as SUS304 or SUS304 or higher.

By carrying out the method of the present invention periodically when the blast furnace is in a blast, the core will be heated regularly during a blast, so that the instability of the operation due to the core is prevented. can do. Although the core improvement effect of the method of the present invention is certain, hollow pipes or gold rods are excavated into the core from a large number of tuyere every time the wind is blown off, and the work load during the wind blow is large and the cost is increased. . The state of the core, that is, the air permeability and liquid permeability of the core vary depending on the operating conditions and raw fuel conditions, and the air permeability and liquid permeability of the core are not always poor. Therefore, the invention described above may be carried out when the air permeability and liquid permeability of the furnace core are deteriorated, and it is not necessary to carry out the invention every time when the wind blows. For that purpose, it is necessary to be able to measure the state of the furnace core and evaluate it accurately.

As a method of measuring the state of the furnace core, a known method can be applied. For example, a method of inserting a probe with a thermocouple into the furnace core from the tuyere to measure the temperature, a method of inserting a probe with an optical fiber into the furnace core from the tuyere to measure the temperature with a radiation thermometer, and a hollow Insert the probe of the pipe from the tuyere into the core and collect the core coke,
History temperature or powder ratio of the coke (for example, 3 mm
How to determine the percentage) of the following coke or composition of the slag taken as above coke sampling, for example, Al ₂ O ₃ / Al of CaO values and average slag are charged into the blast furnace ₂ O ₃ / CaO, A method of indirectly determining the activity of the furnace core by comparing the two, or a method of determining the activity of the furnace core from the insertion resistance value when inserting the probe from the tuyere is used. it can. The above measurement method is basically carried out during a blast, but it can also be carried out during operation in a blast furnace with a cored sonde that allows sampling and temperature measurement during operation.

In the method for measuring the state of the core according to the above-mentioned known method, it is impossible to know the state of the core during the operation because the measurement is performed when the wind is down. In addition, since information other than temperature information requires several days for analysis, there is a high possibility that timely core improvement actions will be delayed. With a blast furnace equipped with a core sonde, the core condition (powder ratio, temperature) during operation can be measured, but since the measurement is from only one tuyere, the condition of the entire core can be evaluated. There is a big problem in accuracy. Therefore, if the circumferential balance of the furnace core can be measured during operation,
The overall condition of the core can be evaluated accurately and in a timely manner, improving the accuracy of the core activation technology.

In the present invention, the relative air flow amount is used as an index for measuring the circumferential balance in the core state during operation. Here, the relative blast-branch air volume is a value obtained by dividing the blast-branch air volume of each tuyere by the average blast-branch air volume, and the average blast-branch air volume is a value obtained by dividing the blast volume by the number of tuyere. There is no problem in the air permeability and liquid permeability of the furnace core when the relative blast branch pipe air volume exceeds 0.9, but when the relative blast tributary air volume decreases, especially the relative blast tributary air volume becomes 0.9 or less. In this case, the air permeability and liquid permeability of the core corresponding to the tuyere will be significantly reduced, and there is a high possibility that the air permeability and liquid permeability of the entire core will eventually be reduced. Therefore, the relative air flow amount of the branch pipe is 0.
If it is 9 or less, it is necessary to take measures to improve the air permeability and liquid permeability of the furnace core.

In the present invention, a hollow pipe is driven into the furnace core from a tuyere having a relative air flow amount of 0.9 or less and a tuyere in the vicinity of the tuyere by a portable pipe driving device. Since this hollow pipe excavates the bird's nest formed in the interior of the raceway and the area with poor air permeability of the furnace core surface layer, the tuyere is usually placed inside the furnace core with a small amount of high-temperature gas flow when starting up the blast. It is possible to directly and forcibly blow hot air of 800 to 1300 ° C. blown from the through the hollow pipe. The hot air blown into the furnace core reacts with the coke in the furnace core to consume the powdered coke, and at the same time becomes a high temperature gas of around 2000 ° C., which heats the coke in the furnace core and simultaneously holds it up in the furnace core. Dissolve metal slag. Since the solution loss reaction of the powder coke in the furnace core also progresses due to the heating of the coke in the furnace core, it is possible to reliably perform the heating and powder removal in the core. Therefore, the air permeability and liquid permeability of the furnace core are improved, and the relative air flow amount of the relative air blow branch pipe, which was 0.9 or less, is significantly improved.

The above-mentioned effect of improving the core is also exhibited by driving a gold rod instead of the hollow pipe. In this case, a gold rod driven into the furnace core from the tuyere generated hot air of 800 ° C. to 1300 ° C. blown from the tuyere when the air was blown up by reacting with coke in the raceway.
After being heated and melted by the high temperature gas of around 00 ° C, a part of the high temperature gas flows into the vent holes of the cavity formed in the core, and the coke, metal and slag in the core are heated to improve the core improvement effect. Is demonstrated.

When the hollow pipe is driven into the core from the tuyere, the material of the tip cap and the position of the hole to be opened at the tip of the hollow pipe are changed depending on the portion of the core to be heated. The efficiency of the core improvement effect can be increased. The material of the tip cap, which is attached so that coke does not enter from the tip of the hollow pipe when driving the hollow pipe from the tuyere, is used when the main purpose is to heat the core in front of the hollow pipe driven into the core. It is desirable to use STPG (ordinary steel) having low high temperature strength so that the tip cap melts at the time when the driving of the hollow pipe is completed.

Here, when it is judged that the heat level in the hearth is insufficient due to a decrease in some indicators indicating the heat level of the hearth, for example, when the temperature of the bottom of the hearth tends to decrease, or the amount of S entering the blast furnace In the case where the desulfurization rate, which indicates the ratio of the amount of S discharged into the slag, and the slag rate, which indicates the ratio of the slag time within the tapping time, are low, the furnace below the hollow pipe driven into the core The main purpose is to heat the floor.

When the main purpose is to heat the hearth portion below the hollow pipe driven into the furnace core, dozens of holes vertically downwardly opened within a range of 1 m from the tip of the hollow pipe, 800-13 blown from the tuyere when the blast is set up
Since it is necessary to blow hot air of 00 ° C in the direction of the hearth, it is necessary to prevent the cap at the tip from melting even at the start of blowing air. The material of the tip cap is SUS304 or SUS304, which has high high temperature strength. It is desirable to use those of the above quality. The diameter of the hole is preferably as large as possible, but 10 to 20φ is an appropriate range considering the strength of the hollow pipe. The number of holes is preferably set so that the open area of the holes is in the range of 0.5 to 3 times the inner diameter cross-sectional area of the hollow pipe.

The hollow pipe driven into the furnace core is cooled in the portion inside the raceway from the tuyere by the intake of air from the tuyere while the air is resting, but in the portion inside the furnace core, it is cooled to 1300 to air. Due to the reaction heat of the coke at 1400 ° C., there is a high possibility that it will be melted during a blast. Even if the hollow pipe driven into the furnace core melts, the cavity in the furnace core is likely to be maintained but may disappear. In that case, 800 to 1300 ℃, which is blown from the tuyere when the air blow is started
It becomes difficult to surely blow the hot air into the furnace core through the hollow pipe, and the furnace core heating effect is halved. Therefore, it is possible to improve the heat resistance strength after driving into the core.
It is necessary to maximize the effect of heating the core according to the present invention.

In the case of a metal pipe containing a ceramic sleeve, the SUS pipe guarantees high-temperature strength when driving into the furnace core, and the heat resistance strength after driving into the furnace core is guaranteed by the ceramic sleeve. Therefore, the cavity in the furnace core is guaranteed by the ceramic sleeve even after the air blow is started.
800-1300 ℃, which is blown from the tuyere when the blow-up is started
The hot air can be blown into the furnace core reliably and for a long time through the hollow pipe. The material of the ceramic sleeve is a heat resistant temperature of 1600 ° C or higher and a bending strength of 1
At 000 kg / cm ² , it is necessary to finally melt and discharge it as a slag component out of the furnace.
A ceramic sleeve of the type l ₂ O ₃ / SiO ₂ is desirable. In addition to the metal pipe in which the ceramic sleeve is installed, a metal pipe having a castable coating on the inner surface or the outer surface can be used.

When a tuyere with a relative blast branch pipe air volume of 0.9 or less is detected, the relative blast tributary air flow rate is increased in order to improve the core portion in front of the tuyere which has poor air permeability and liquid permeability. 0.
Drive a hollow pipe or a gold rod through tuyere 9 or less. Then, if possible, it is desirable to improve the furnace core portion in front of the tuyere where the relative air flow amount is 0.9 or less and the air permeability and liquid permeability are poor, and the vicinity thereof. In that case, the relative blast branch air volume is 0.9 or less and the adjacent tuyere, that is, the relative blast branch air volume is 0.9 or less in both directions. It is preferable to drive a hollow pipe or a gold rod from at least one tuyere since the amount of air blown to the furnace core can be further increased.

Here, the hot air is high temperature air or gas heated in a hot air stove blown from the tuyere of the blast furnace. The temperature range of hot air is 800 to 13 for the following reasons.
00 ° C is desirable. The hot air burns the coke in the furnace core through a hollow pipe driven into the furnace core to form a high-temperature reducing gas, but in order to keep the temperature above 2000 ° C, the lower limit temperature of the hot air is 800 ° C. Is. When the temperature of the hot air becomes 1300 ° C. or higher, the reducing gas temperature generated by burning the coke in the furnace core through the hollow pipe driven into the furnace core becomes too high, and the SiO in the ash in the coke becomes too hot.
Volatilize ₂ to worsen the air permeability of the furnace core.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A concrete description will be given below based on the embodiments shown in the drawings. (Example 1) The inner volume is 4000 m ³ or more and the number of tuyere is 38.
In the large-scale blast furnace of this book, hollow pipes 4 are driven into the core of the furnace from a total of 6 tuyeres, including tuyeres to be replaced and arbitrary tuys, every time the wind blows. It is. First, using a portable pipe driving device 1 and a pipe driving jig 2 for driving a combination of an air hammer and hydraulic pressure, a hollow pipe 4 having a length of 2 m and having a cap 3 for preventing intrusion of furnace core coke at the tip is installed. It was driven into the furnace core 6 from the tuyere 5. Next, a hollow pipe 7 with a length of 1 m
After the tip of was connected to the end of the hollow pipe 4, it was driven in, and the hollow pipe was driven to a depth of 3 m from the furnace wall.
In the figure, 9 is a raceway and 10 is a bird's nest.

Here, the joint portion of the pipe 4 having a length of 2 m at the tip portion and the hollow pipe 7 having a length of 1 m is hollowed by cutting as shown in FIG. 2 so that the fitting is successful. The wall thickness was changed so that the pipe 7 was thicker. The material of the cap 3 at the tip is STP so that it melts when the hollow pipe is driven to a depth of 3 m from the furnace wall.
G (normal steel) was used. Then, so that the hot air of 800 to 1300 ° C. blown from the tuyere at the time of start-up of the blown air is blown directly and forcibly into the furnace core, at the time of completion of driving the pipe, there is a button 8 in the gap between the hollow pipe and the tuyere. Packed.
By carrying out the method of the present invention, the core was improved, and as shown in FIG. 3, fluctuations in load drop such as slip and wind pressure fluctuations, which were many before the method of the present invention, were reduced, and the operating state was stabilized. Also, when a gold rod is driven into the furnace core instead of the hollow pipe 7 at the time of rest, as shown in FIG. 3, fluctuations in the load such as slip and fluctuations in wind pressure change at a low level, and the hollow pipe is driven. Almost the same effect as the core improvement effect was obtained.

(Example 2) In a large blast furnace having an inner volume of 4000 m ³ or more and 38 tuyeres, ^three tuyeres having a relative air flow rate of 0.9 or less were detected during operation, and It was judged that the breathability and liquid permeability had deteriorated. Therefore, at the next blast furnace blast, the tuyeres with a relative blast tributary air volume of 0.9 or less at three locations and the tuyere in the vicinity thereof, that is, the tuyeres on both sides of the tuyere with the relative blast tributary air volume of 0.9 or less. Hollow pipes were driven into the furnace core from a total of nine tuyere by the method as shown in FIG. Using a portable pipe driving device 1 and a driving jig 2 for driving a combination of an air hammer and hydraulic pressure, first, a cap 3 for preventing intrusion of core coke is installed at a tip having a length of 2 m. The hollow pipe 4 was driven into the furnace core 6 from the tuyere 5.

Next, the end of the hollow pipe 7 having a length of 1 m was connected to the end of the hollow pipe 4 and then driven, and the hollow pipe was driven to a depth of 3 m from the furnace wall. Here, the joint portion between the pipe 4 having a length of 2 m at the tip and the hollow pipe 7 having a length of 1 m is shown in FIG.
As shown in, the wall thickness was changed by cutting. The material of the cap at the tip was STPG (normal steel) so that it melts when the hollow pipe is driven to a depth of 3 m from the furnace wall. Then, so that the hot air of 800 to 1300 ° C. blown from the tuyere at the time of start-up of the blown air is blown directly and forcibly into the furnace core, at the time of completion of driving the pipe, there is a button 8 in the gap between the hollow pipe and the tuyere. Packed.

The start-up of blast after a break has been steadily progressing, and 3
As shown in Fig. 4, the relative blast tributary air volume of the tuyere where the relative blast tributary air volume of 0.9 or less was significantly improved one day after the blast was started, and in all cases, it became around 1 and the core was activated. Headed for the direction. As a result, as shown in FIG. 5, load drop fluctuations such as slips and wind pressure fluctuations, which were common before the wind breaks, tended to decrease after the start of the wind breaks, and the operating conditions were stabilized. Also, when a gold rod is driven into the furnace core instead of the hollow pipe 7 when there is no wind, as shown in FIGS. 4 and 5, fluctuations in the load such as slips and fluctuations in wind pressure change at a low level. The effect of improving the core was almost the same as when the pipe was driven.

(Example 3) In a large blast furnace having an inner volume of 4000 m ³ or more and 38 tuyere, four tuyere with a relative blast branch pipe air volume of 0.9 or less were detected. Further, the desulfurization rate was in the 70% range and the slag removal rate was in the 60% range, and it was judged that the air permeability and liquid permeability of the furnace core were deteriorated due to insufficient heat in the hearth.
Therefore, at the next blast furnace blast, the tuyere at the four locations with relative blast branch airflow of 0.9 or less and the tuyere near it, that is, the tuyere on both sides of the tuyere with relative blast branch airflow of 0.9 or less. Of 1
Hollow pipes were driven into the furnace core from two tuyere by the method as shown in FIG. First, using a portable pipe driving device 1 and a driving jig 2 for driving a combination of an air hammer and hydraulic pressure, first, as shown in FIG. 6, ten holes of 10 to 15φ are formed in one direction within a range of 1 m from the tip. The hollow pipe 4 having a length of 2 m, which was opened as described above, was driven into the furnace core portion 6 from the tuyere 5 with the cap 3 for preventing the intrusion of the furnace core coke installed at the tip of the hollow pipe 4 so as to face vertically downward. .

Next, the end of the hollow pipe 7 having a length of 1.5 m was connected to the end of the hollow pipe 4 and then driven, and the hollow pipe was driven to a depth of 3.5 m from the furnace wall. Here, the joint portion of the pipe 4 having a length of 2 m at the tip and the hollow pipe 7 having a length of 1.5 m is thickened by cutting as shown in FIG. 2 so that the fitting is successful. Was changed. The material of the cap at the tip was SUS304, which was the same material as the hollow pipe so that the cap at the tip did not melt even when the air was blown up. Then, at the time when the driving of the pipe is completed, the button 8 is placed in the gap between the hollow pipe and the tuyere so that the hot air of 800 to 1300 ° C. blown from the tuyere at the time of starting the air blow is blown directly and forcibly into the furnace core. Stuffed.

The start-up of the blown air after a break has been steadily increasing, and
As shown in FIG. 7, the relative blast branch air volume of the tuyere where the relative blast branch air volume of 0.9 or less is significantly improved from one day after the start of the blast, and is about 1 in each case, as shown in FIG. In addition, there was a tendency for load fluctuations such as slips and wind pressure fluctuations, which were common before the wind blew. Then, as shown in FIG. 8, the temperature of the bottom brick of the furnace bottom, which had been decreasing from one week after the start of air blowing to before the rest of the air, began to rise, and one month later, the temperature level at the time of favorable conditions was reached, The wick has been activated. As a result, the slag was discharged smoothly at the same time as the hot metal, and the slag ratio, which shows the ratio of slag discharged within the tapping time, was improved from 60% to 80%, and the desulfurization ratio was also increased.
In addition, the temperature of the bottom wall of the furnace bottom decreased with the rise of the temperature of the bottom brick of the furnace bottom, and it was possible to suppress the annular flow, which is the main factor of shortening the furnace life.

(Example 4) In a large blast furnace having an internal volume of 4000 m ³ or more and 38 tuyere, four tuyere with a relative air flow amount of 0.9 or less were detected. Further, the desulfurization rate was in the 70% range and the slag removal rate was in the 60% range, and it was judged that the air permeability and liquid permeability of the furnace core were deteriorated due to insufficient heat in the hearth.
Therefore, at the next blast furnace blast, the tuyere at the four locations with relative blast branch airflow of 0.9 or less and the tuyere near it, that is, the tuyere on both sides of the tuyere with relative blast branch airflow of 0.9 or less. Of 1
A hollow pipe containing a ceramic sleeve was driven into the furnace core from two tuyere by the method shown in FIG.
Using a portable pipe driving device 1 and a driving jig 2 for driving a combination of an air hammer and hydraulic pressure, first, a ceramic sleeve 11 having a ceramic sheet 12 as a cushion material as shown in FIG.
The hollow metal pipe 4 was driven into the furnace core 6 from the tuyere 5.

Next, the end of a hollow pipe 7 having a length of 1.5 m was connected to the end of a hollow metal pipe 4 containing a ceramic sleeve, and then the pipe was driven in, and the hollow pipe was driven to a depth of 3.5 m from the furnace wall. . Here, the joint portion of the pipe 4 having a length of 2 m at the tip and the hollow pipe 7 having a length of 1.5 m is thickened by cutting as shown in FIG. 2 so that the fitting is successful. Was changed. Then, at the time when the driving of the pipe is completed, the button 8 is placed in the gap between the hollow pipe and the tuyere so that the hot air of 800 to 1300 ° C. blown from the tuyere at the time of starting the air blow is blown directly and forcibly into the furnace core. Stuffed.

The presence of the ceramic sleeve in the furnace core was confirmed from the tuyere even after 2 hours from the start of the air blowing after the rest of the air. As shown in FIG. Bottom brick temperature reached a temperature level at the time of favorable conditions, and the furnace core was activated in a short time of 1/3 to 1/4 as compared with when the hollow pipe without the ceramic sleeve was driven into the furnace core. . As a result, the discharge of slag at the same time as the hot metal became smooth in a short period of time, the slag ratio indicating the ratio of slag discharged within the tapping time was improved from 60% to 80%, and the desulfurization ratio was also increased. In addition, the temperature of the bottom wall of the furnace bottom decreased with the rise of the temperature of the bottom brick of the furnace bottom, and it was possible to suppress the annular flow, which is the main factor of shortening the furnace life.

[0039]

According to the method of the present invention, a hollow pipe or a gold rod is driven in periodically from the tuyere at the time of rest to increase the flow rate of high-temperature gas around 2000 ° C into the core of the furnace at the time of start-up of blast. As a result, it is possible to reliably perform heating and powder removal inside the furnace core, always maintain good air permeability and liquid permeability of the furnace core, and maintain stable operation. Further, when the core state can be evaluated by combining it with a known method for measuring the core state, the present invention can be applied only when the state of the core is poor, so that the core can be activated efficiently. Can be converted. Furthermore, when the relative air flow amount of each tuyere can be measured, the circumferential balance of the furnace core can be evaluated during the operation, so that the furnace core can be activated more efficiently.

When the method of the present invention is carried out, there is a problem that the amount of tapped metal decreases for a long period of time because the operation for increasing the fuel ratio is continued for a long time as in the conventional case, or the reactor condition cannot be rebuilt early. Can be completely eliminated. As in the case of operations using cheap raw fuel and high pulverized coal ratio operation in the future, the pulverization of ore and coke will increase, and the powder rate in the lower part of the furnace including unburned char will increase, increasing the air permeability of the core. Stable operation can be maintained even when it is difficult to secure liquid permeability. Further, when the method of the present invention is carried out, the annular flow can be eliminated, so that it is not necessary to suppress the fuel rise and the amount of tapping as a countermeasure for the annular flow, so that the controllability of the blast furnace can be improved.

[Brief description of drawings]

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

FIG. 2 is an explanatory view showing the connection of hollow pipes for driving the furnace core.

FIG. 3 is a transition chart of operating indexes before and after the implementation of the method (1) and (2) of the present invention.

FIG. 4 is a diagram showing a change in relative air flow amount of a branch pipe before and after carrying out the methods (5) and (6) of the present invention.

FIG. 5 is a transition chart of the operation index before and after the implementation of the method (5), (6) of the present invention.

FIG. 6 is a view showing hole positions of a hollow pipe for heating a hearth.

FIG. 7 is a diagram showing changes in relative air flow amount of a branch pipe before and after carrying out the method (7) of the present invention.

FIG. 8 is a transition chart of the operation index before and after the implementation of the method (7) of the present invention.

FIG. 9 shows a hollow pipe with a ceramic sleeve inside.

FIG. 10 is a transition chart of the operation index before and after the implementation of the method (8) of the present invention.

[Explanation of symbols]

 1 Portable pipe driving device 2 Pipe driving jig 3 Cap 4 Hollow pipe 5 Tuyere 6 Reactor core 7 Hollow pipe 8 Button 9 Raceway 10 Bird's nest 11 Ceramic sleeve 12 Ceramic sheet 13 Ceramic board

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takashi Kumaoka 1 Kimitsu, Kimitsu-shi, Chiba Nippon Steel Corporation Stock of Kimitsu Steel Co., Ltd.

Claims (8)

[Claims] 1. A hollow pipe is driven into a furnace core from a tuyere when the blast furnace is at rest, air is blown up while the hollow pipe remains in the furnace core, and the hollow pipe is blown into the furnace core. A blast furnace operating method characterized by that. 2. When the blast furnace is in a blast, a gold rod is driven into the furnace core from the tuyere, blowing is started with the gold rod remaining in the furnace core, the gold rod is melted, and a vent hole is formed in the furnace core. Is formed, and air is blown into the furnace core through the ventilation holes. 3. When the state of the core is measured during operation of the blast furnace or while the wind is off, and when it is determined that the state of the core is poor, a hollow pipe is driven into the core of the blast furnace from the tuyere when the air is off. Blow start-up with the hollow pipe left inside the furnace core,
A blast furnace operating method, characterized in that air is blown into the furnace core from the hollow pipe. 4. The state of the core is measured during operation of the blast furnace or during the idle time, and when it is determined that the state of the core is poor, a gold rod is driven into the core from the tuyere when the blast furnace is idle, A blast furnace operating method characterized in that air blowing is started with the gold rod remaining in the furnace core, the gold rod is melted to form a vent hole in the furnace core, and air is blown from the vent hole into the furnace core. . 5. A tuyere having a relative blast airflow amount of 0.9 or less obtained by measuring the blast airflow amount of each tuyere with a blast airflow meter installed at each tuyere during blast furnace operation and dividing by the average airflow amount Is detected, and the relative air flow amount of the relative blow branch pipe is 0.
The blast furnace operating method according to claim 3, wherein the hollow pipe is driven into the core from 9 or less tuyere and / or the tuyere in the vicinity thereof. 6. A tuyere having a relative blast branch air volume of 0.9 or less obtained by measuring the blast tributary air volume of each tuyere with a blast tributary air flow meter installed for each tuyere during blast furnace operation and dividing by the average blast tributary air volume Is detected, and the relative air flow amount of the relative blow branch pipe is 0.
The blast furnace operating method according to claim 4, wherein a gold rod is driven into the core from 9 or less tuyere and / or a tuyere in the vicinity thereof. 7. The blast furnace operating method according to claim 1, 3 or 5, wherein the air is blown from a tip of the hollow pipe and / or a hole opened in the hollow pipe. 8. The blast furnace operating method according to claim 1, wherein the hollow pipe is a metal pipe having a ceramic sleeve provided therein.