JPH05195026A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To keep the constant production and the constant coke ratio by removing stuck material when powdery iron source injected in a tuyere sticks to a refractory heat-insulating ring set in the tuyere and the cross-sectional area of the tuyere is reduced, and recovering back the reduced cross-sectional area of the tuyere to the original state. CONSTITUTION:In order to melt and remove the stuck material 3 developed at the refractory heat-insulating ring by utilizing combustion heat of the pulverized coal injected into the inner part of a blast furnace together with the powdery iron source, the tip part of an injecting burner 1 is shifted to near the stack material, and also by using the burner 1 cutting the tip part to the diagonal direction, the combustion flame is made to directly contact with the stack material. Even in the case the stack material is developed in any position of the refractory heat-insulating ring, the stuck material can be removed by advancing/retreating and rotating the burner.

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 a powdery iron source is stably blown into a blast furnace from a tuyere to stably reduce and melt the blast furnace to stabilize productivity. ..

[0002]

2. Description of the Related Art In recent blast furnace operations, low silicon operations have been aimed at from the viewpoint of improving the quality in the subsequent steel making process or economical efficiency. As a typical operation mode of this kind, there is a method of blowing a powdered iron source such as iron oxide powder or reduced iron powder from the tuyere together with pulverized coal, which is disclosed in Japanese Patent Laid-Open No. 57-137402. ing.

A powdered iron source such as iron oxide powder and reduced iron powder blown into the blast furnace is reduced to a metallic state by a reduction reaction, and the hot metal in the blast furnace and reaction formula 2 (Fe
O) + [Si] = 2 [Fe] + (SiO ₂ ) to reduce the silicon content in the hot metal. When the blast furnace operation is stable, the amount of iron ore charged from the top of the blast furnace can be reduced by the amount of the powdery iron source blown from the tuyere. Usually, iron ore charged from the top of the furnace is agglomerated to maintain the air permeability in the furnace,
The use of an inexpensive powdered iron source in place of iron ore that requires pretreatment is also effective in increasing the economic efficiency of blast furnace operation.

[0004]

In the conventional blast furnace operation, the powdery iron source blown from the tuyere is reduced and melted into hot metal in a region called a raceway where coke swirls and burns. Usually, the powdery iron source is blown into the tuyere through a burner attached to the blower branch pipe portion. A straight pipe is used as this burner, and the distance between its tip and the tuyere tip is fixed, so that it remains unchanged even if the amount of powdered iron source blown in or the preliminary reduction rate of powdered iron source changes. is there.

However, when the amount of the powdered iron source blown in increases or the preliminary reduction rate of the powdered iron source increases, the powdered iron source adheres to the refractory heat insulating ring installed in the tuyere and tuyere. Reduce the cross-sectional area. Refractory insulation ring is made of SiO ₂ , Al ₂ O
₃ , made of refractory material such as SiC, ZrO _2, etc., and installed to reduce the amount of heat removed from the water-cooled copper tuyere. In addition, it also prevents the tuyere from being attacked by the blown powdery iron source and prevents tuyere damage.

When the tuyere cross-sectional area is reduced in this way, the blower pressure rises, the power consumption of the blower increases, and the blower limit is easily reached so that the blower amount must be reduced. , The production volume will decrease. If the installation of refractory heat insulating rings is stopped to prevent an increase in blast pressure, the amount of heat removed from the tuyere will increase, which will substantially reduce the blast temperature and increase the fuel consumption of the blast furnace. Since tuyere damage is more likely to occur, the blast furnace must be temporarily stopped, resulting in a decrease in production.

The reason why the powdery iron source adheres to the refractory heat insulating ring is that FeO in the iron source is melted and SiO ₂ in the ring is
It is to react with Al ₂ O ₃ and ZrO ₂ to form a compound. Therefore, when the pre-reduction rate of the powdery iron source becomes high or the powdered iron source blowing amount increases, FeO increases, and as a result, the amount of deposit formation increases. For this reason, the amount of powdered iron source blown cannot be increased above a certain value, and the pre-reduction rate of the powdered iron source cannot be increased above a certain value either. There was a limit to the increase in production volume.

Therefore, the present invention removes the deposits when the powdery iron source blown into the tuyere adheres to the refractory heat insulating ring installed in the tuyere to reduce the cross-sectional area of the tuyere. It is an object of the present invention to provide a method capable of returning a tuyere cross-sectional area that has been reduced to an original state and maintaining a constant production amount and a constant coke ratio.

[0009]

In order to achieve the above object, the present invention has a blast furnace operating method in which a powdery iron source and pulverized coal are blown into the interior of a blast furnace from a tuyere to cut the tip obliquely. It is characterized in that a blower burner is used to move the burner forward and backward and rotate in the blower branch pipe.

[0010]

The point of the present invention is to remove the deposits formed on the refractory heat insulating ring by using the combustion heat of the pulverized coal blown into the blast furnace together with the powdery iron source. In order to do so, it is necessary to efficiently apply the combustion heat of pulverized coal to the deposits.Move the tip of the blowing burner near the deposits, use a burner with the tip cut diagonally, and rotate this burner. So that the combustion flame is in direct contact with the deposit. The relationship between the deposit formation position of the refractory heat insulating ring and the operation method of the burner in the present invention will be described below.

1 to 6 (FIGS. 1 and 4 are views (a))
FIG. 6 is a diagram showing a situation when a tuyere is seen through a peephole.
FIG. 1 shows a case where the deposit is generated in the center of the right. The burner is rotated so that the diagonal cut of the burner is on the right side, and the burner is advanced to bring its tip closer to the deposit.
Reference numeral 1 is a burner, 2 is a tuyere observation cross section, and 3 is a deposit.
(B) is a vertical cross-sectional view of the tuyere at this time, and 4 is a tuyere and 5 is a blower branch pipe. FIG. 2 shows the case where the deposit is generated in the upper right, the burner is rotated so that the slanted cut of the burner is on the top, and the burner is advanced to bring its tip closer to the deposit. FIG. 3 shows the case where the deposit is generated at the lower right, and the burner is rotated so that the diagonal cut of the burner is at the bottom, and the burner is advanced to bring its tip closer to the deposit.

FIG. 4 shows a case in which the deposit is generated in the left center. The burner is rotated so that the diagonal cut of the burner lies on the left side, and the burner is retracted to bring the tip thereof closer to the deposit. FIG. 6B is a vertical cross-sectional view of the tuyere at this time. FIG. 5 shows the case where the deposit is generated at the upper left, and the burner is rotated so that the diagonal cut of the burner is on the top, and the burner is retracted so that the tip of the burner approaches the deposit. FIG. 6 shows the case where the deposit is generated at the lower left, and the burner is rotated so that the diagonal cut of the burner is at the bottom.
At the same time, the burner is retracted so that its tip approaches the deposit.

As described above, no matter where the deposit is formed on the refractory heat insulating ring, the deposit can be melted and removed by moving the burner forward and backward and rotating. In the operating method of the present invention, a person may directly look into the inside of the tuyere peephole portion and manually move the burner forward and backward and rotate it. Alternatively, a movable camera may be attached to the tuyere peephole portion in the instrument room. It is also possible to perform remote monitoring and remotely move the burner forward and backward and rotate it.

[0014]

EXAMPLES The features of the present invention will be specifically described below with reference to Table 1 by examples.

[0015]

[Table 1]

In Example 1, when a pulverized coal ratio of 50 kg / t was blown, a powdered iron source preliminarily reduced by 30% was also blown,
This is an example of operation in which a person directly looks into the interior from the tuyere peep hole and manually moves the burner forward and backward to rotate and rotate it to suppress adhesion, and as a result, a powdery iron source of 50 kg / t can be stably injected. .. On the other hand, in Comparative Example 1, when a normal straight burner was fixed and blown at a pulverized coal ratio of 50 kg / t, only 40 kg / t of a powdery iron source preliminarily reduced by 30% could be blown because of deposit formation. Here is an example. Comparing Example 1 with Comparative Example 1, the production amount of Example 1 is higher and the coke ratio is also lower.

In Example 2, when a pulverized coal ratio of 100 kg / t was blown in, a 50% pre-reduced powdery iron source was also blown in at the same time, and a mobile camera was attached to the tuyere peephole for remote monitoring in the instrument room. As a result, the burner was moved forwards and backwards and rotated by remote control to suppress the adhesion, resulting in a stable powder iron source of 100 kg / t.
This is an example of operation that has achieved blowing. On the other hand, in Comparative Example 2, a normal straight burner is fixed and the pulverized coal ratio is 100 kg.
This is an example of operation in which only 80 kg / t of the powdery iron source preliminarily reduced by 50% was blown due to the formation of deposits when it was blown in at / t. Comparing Example 2 with Comparative Example 2, Example 2
Has a higher production volume and a lower coke ratio.

In Example 3, when a pulverized coal ratio of 120 kg / t was blown, a powdery iron source preliminarily reduced by 80% was also blown in at the same time, and a person directly looked into the inside from the tuyere peep hole portion, and the burner was manually operated remotely. This is an example of operation in which 200 kg / t of the powdery iron source could be stably injected as a result of advancing and reversing and rotating the steel to suppress adhesion. On the other hand, in Comparative Example 3, when a normal straight burner was fixed and blown at a pulverized coal ratio of 120 kg / t, a powdery iron source preliminarily reduced by 80% was generated at a rate of 160 k due to deposit formation.
This is an example of operation in which only g / t could be blown. Comparing Example 3 with Comparative Example 3, the production amount of Example 3 is higher and the coke ratio is also lower.

[0019]

As described above, according to the present invention, a blower burner attached to the blower branch pipe whose tip is cut obliquely is used, and the burner is moved forward and backward and rotated in the blower branch pipe. , The refractory heat-insulating ring installed in the tuyere can be melted to remove deposits from the powdered iron source, and the increase in blast pressure due to the reduction in the tuyere cross-sectional area can be prevented, so the production volume and coke ratio can be kept constant. As a result, a stable hot metal supply can be achieved.

[Brief description of drawings]

FIG. 1 (a) is a view showing a state of an adhering substance and a burner according to the present invention when a tuyere is seen through a peephole portion, and FIG. 1 (b) is a longitudinal sectional view of the tuyere portion at this time.

FIG. 2 is a diagram showing a state of an adhered matter and a burner according to the present invention when a tuyere is seen through a peephole.

FIG. 3 is a diagram showing a state of an adhered matter and a burner according to the present invention when a tuyere is seen through a peephole,

FIG. 4 (a) is a view showing a state of an adhered substance and a burner in the present invention when a tuyere is seen through a peephole portion, and FIG. 4 (b) is a vertical cross-sectional view of the tuyere portion at this time.

FIG. 5 is a diagram showing a state of an adhered matter and a burner according to the present invention when a tuyere is seen through a peephole.

FIG. 6 is a view showing a state of an adhered matter and a burner according to the present invention when a tuyere is seen through a peephole,

[Explanation of symbols]

 1 burner 2 cross section of tuyere observation 3 adhering matter 4 tuyere 5 blower branch pipe

Claims (1)

[Claims] 1. A blast furnace operating method in which a pulverized iron source and pulverized coal are blown into a blast furnace from a tuyere, a blow burner having a beveled tip is used, and the burner is moved forward and backward in a blower branch pipe. A blast furnace operating method characterized by rotating.