JPH05331510A - Method for activating furnace core of blast furnace - Google Patents

Abstract

PURPOSE:To activate inactivated furnace core part by beforehand making fuel ratio before stopping blasting a specific value and also blowing coke combustion gas together with NaCl by the air into the furnace core part at the time of stopping the blasting, when the furnace core part of a blast furnace is inactivated. CONSTITUTION:In the case of becoming a bad furnace condition lowering the ventilation, because the furnace core part 5 at the tip part of a raceway of the blast furnace is inactivated, the fuel ratio is made to be >=600kg/ton of molten iron in >=10hr before stopping the blasting and also a coke combustion gas pipe 1 is inserted into the center of the furnace core part 5 from a tuyere at the time of stopping the blasting, and NaCl is blown in together with the air. Fine powdery coke 3 clogging the furnace core part 5 is burnt and by flowing out and removing high viscosity oxide of SiO2, Al2O3, etc., as the ash content of the coke as low m.p. molten slag with NaCl, the clogging in the furnace core part is eliminated and the ventilation is improved and the furnace core part 5 is activated and the furnace condition of the blast furnace is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace core activation technique.

[0002]

2. Description of the Related Art Inside a blast furnace, there is a so-called furnace core at the tip of a raceway in which mountain coke does not move much. If the air permeability of the furnace core deteriorates, that is, if the particle size of the coke forming the furnace core decreases or the voids in the furnace core decrease, the blower pressure increases, slips frequently occur, and the slag drainage deteriorates. cause.

There are various causes for such furnace core inactivity. For example, when coke is subjected to thermal shock in the raceway and its vicinity, or powder is generated when the cokes rub against each other, and the powder scatters in the vicinity, but the powder that has scattered to the core has slow movement of the core coke. Accumulating one after another and causing clogging. In addition, unburned pulverized coal that could not be burned in the tuyere during the operation of blowing pulverized coal from the tuyere also deposits on the core. In addition, the coke reacts with FeO and the like remaining in the slag in the furnace core, and the coke particle size decreases, but since the movement of the coke in the furnace core is slow, the decrease in particle size becomes large and Activate.

For the above-mentioned furnace core coke inactive region, the following attempts have conventionally been made to activate the furnace core. For example, a method of activating the core by selectively charging coke into the center of the furnace at the top of the blast furnace to reduce the ore layer thickness fraction in the center of the coke to a lower value than that in the other in the radial direction of the furnace (Japanese Patent Publication No. -9373). However, in this method, it took a long time for the core coke to be replaced and activated due to slow movement of the core coke.

Further, Japanese Patent Laid-Open No. 3-138306 discloses a method of activating a furnace core by charging a lance from a bosh of a blast furnace and directly charging coke into the furnace core. However, since the furnace core is already filled with coke, if a new coke is to be charged at that location, considerable pressure must be applied during charging, and coke powder is likely to be generated. Also, if the coke is not preheated, the heat of the surrounding melt will be robbed by the charging coke, causing the melt to solidify,
On the contrary, there is a risk of deteriorating the air permeability of the furnace core. Further, if the charged coke is to be preheated, it is necessary to newly install preheating equipment.

[0006]

SUMMARY OF THE INVENTION The present invention is intended to solve the above problems, and it is an object of the present invention to provide a method for reliably activating a blast furnace core in a short time.

[0007]

According to the present invention, when activating the inactivated blast furnace core coke region, a preliminary air blow 10
The fuel ratio was set to 600 kg / mol.ton or more from more than an hour ago, then the coke combustion gas pipe was charged from the tuyere of the blast furnace to the center of the core when there was no wind, and the coke combustion gas pipe was used together with air.
It is a blast furnace core activation method characterized by burning and extinguishing inactivated core coke by injecting NaCl.

[0008]

[Function] In order to bring the inactivated blast furnace core coke into the activated state, the core is not clogged, the particle size of the coke forming the furnace core is increased, and the molten material dripping inside the furnace It may be brought to a high temperature to such an extent that it does not solidify and its viscosity does not rise significantly. That is, the inactive furnace core coke may be burnt out, and the furnace core may be replaced with coke which has a small amount of fine powder and a large particle size and which is high in temperature.

Therefore, first, the fuel ratio is set to 600 kg / hot metal ton or more 10 hours or more before resting. As a result, the temperature distribution in the furnace changes greatly, and, for example, as shown in FIG. 2B, the high temperature portion above the tuyere level in FIG. 2A during normal operation spreads. FIG. 3 shows the movement of coke in the vicinity of the core, that is, the coke descending velocity vector 6, but the movement is slow in the core as already described. On the other hand, there is a large flow toward the raceway outside the furnace core, where the coke particle size is large and the amount of powder accumulation is small.

Here, as shown in FIG. 1 (a), if the coke combustion gas pipe 1 is charged from the tuyere of the blast furnace to the central portion 5 of the core and the core coke is burned by the gas to be extinguished, the unprecedented result is obtained. The coke in the active state disappears, and as shown in FIG. 1B, the furnace core is newly replaced with the dropping zone coke 2 which has been outside the furnace core. In other words, the core is activated by substituting high temperature coke with a large particle size and less powder accumulation.

Here, the fuel ratio is set to 600 k before 10 hours of rest.
If it is not more than g / hot metal ton, the high temperature part above the tuyere level will not spread much, and when the core coke is burnt out, it will not reach the low temperature part and activate the core. The inventors have made the following findings as a result of an experiment on the fuel ratio before the blast and when to increase the fuel ratio. That is, in the blast furnace, the slip frequency was 4 times / day on average when the core was inactivated during normal operation, but as shown in FIG.
It was found that the slip frequency after blowing was significantly lower than that before resting when NaCl was blown together with air at 0 kg / mol ton or more.

By the way, when coke is burned, ash remains. This ash is mainly composed of SiO ₂ and AlO ₃ , and if left as it is, it has a high melting point and will clog the furnace. However, in the present invention, when coke is burned, NaCl is blown in at the same time, so the ash becomes a slag with a low melting point and low viscosity,
It easily flows to the hearth and the risk of clogging can be prevented. It should be noted that the gas for burning the furnace core coke is sufficient in the atmosphere, but it is desirable to heat it to form warm air.

[0013]

EXAMPLES The present invention was carried out in a blast furnace having an internal volume of 2584 m ³ , a number of tuyeres of 30 and two tap holes. Fig. 5 shows the coke combustion gas pipe 1.
The one shown in was used. After the main body 1 is charged from the tuyere 8 to the center of the furnace during the quiescent air, the gas exhaust port 7 is opened and air is blown to inactivate the furnace core coke.
Reference numeral 9 is a gas streamline. FIG. 6 shows the operating state of the blast furnace before and after the present invention is carried out. Before the breeze, the core coke region of the blast furnace became inactive and slips occurred 10 times in 60 hours. Further, the ventilation resistance index (ΔP / V), which indicates the ventilation liquid permeability in the furnace, is high, indicating that the air permeability is poor.
The Si concentration in the hot metal was also high. Therefore, the fuel ratio was set to 600 kg / ton of hot metal 10 hours before the breeze. During the rest, the coke combustion gas pipe 1 was charged from the tuyere 8 and hot air was blown to burn and extinguish 80 m ³ of coke in bulk volume from the center of the furnace. At this time, the total amount of NaCl powder was 0.6 tons together with the blast.
Blown in.

After the resending wind, the furnace condition improved, no slip occurred thereafter, and the ventilation resistance index also decreased. As a result, the Si concentration in the hot metal also decreased. As described above, according to the present invention, the remarkable effect that the activation of the furnace core is achieved in a short time of about one day is achieved. FIG. 7 shows the operation transition of the blast furnace when the present invention was carried out for a long period of time. Prior to carrying out the present invention, since the core coke region entered inactively, slip often occurred and the air permeability in the furnace deteriorated, and the operating rate often decreased. Therefore, the present invention was implemented in period A in the figure. As a result, the occurrence of slip is extremely reduced, and the ventilation resistance in the furnace is also lower than before. In period B, the fuel ratio is 600kg /
In hot metal ton, in period C, the fuel ratio was set to 59 before 10 hours of rest.
This is a case where the present invention was carried out with 0 kg / ton of hot metal. As described above, the occurrence of slip and the in-furnace air permeability are not necessarily reduced.

[0015]

As described above, according to the present invention, the inactivated blast furnace core coke region is activated in a short time,
The ventilation resistance decreased, the number of slips decreased, and the Si content in the hot metal decreased, enabling stable operation over the long term.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a method for replacing core coke according to the present invention.

FIG. 2 is a cross-sectional view showing an example of the temperature distribution in the furnace during normal operation and when there is no air blow during implementation of the present invention.

FIG. 3 is an explanatory diagram showing the movement of coke in the vicinity of a furnace core and a raceway.

FIG. 4 is a graph showing a fuel ratio increasing condition before a breeze and a slip number after a resending wind.

FIG. 5 is a schematic view of a coke combustion gas pipe.

FIG. 6 is a graph showing blast furnace operating conditions before and after the present invention is carried out.

FIG. 7 is a graph showing an operation transition when the present invention is carried out for a long period of time.

[Explanation of symbols]

 1 Coke combustion gas pipe 2 Drip zone coke 3 Inert core coke 4 Fusing zone 5 Blow gas 6 Coke descent rate vector 7 Coke combustion gas outlet 8 Tuyere 9 Gas streamline 10 Furnace wall

Claims (1)

[Claims] 1. When activating the inactivated blast furnace core coke region, the fuel ratio is set to 60 at least 10 hours before the dead air.
0 kg / hot metal ton or more, then when the wind is off, insert a coke combustion gas pipe from the blast furnace tuyere to the center of the core, blow NaCl with air from the coke combustion gas pipe to inactivate the core coke A blast furnace core activation method characterized by: