JPH05255717A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To recover a cold state in a short term and to restore the productivity at early time by charging high temp. and a large quantity of heat from an iron tapping hole and a tuyere part just above the iron tapping hole when the cooling develops caused by the flooding of water and shortage of the furnace heat in a blast furnace. CONSTITUTION:When the cold state is occurred, plasma torches 5 are inserted from the iron tapping hole 4 and the tuyere part 3 just above the iron tapping hole to blow either one of high temp. of nitrogen, air and oxygen. Further, a temporary iron tapping hole is disposed between the iron tapping hole 4 and the tuyere part 3 just above the iron tapping hole, and the plasma torches 5 are inserted from the temporary iron tapping hole and the tuyere part 3 just above the iron tapping hole, and by energizing between both torches plasma arcs are generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in the operation of charging iron ore and coke from the top of a blast furnace, blowing hot air or hot air and auxiliary fuel from the tuyere, and extracting molten pig iron from the taphole. The present invention relates to a blast furnace operating method for promptly recovering a cold state when the cold state occurs due to inundation in the furnace or lack of heat in the furnace.

[0002]

2. Description of the Related Art In blast furnace operation, hot air or hot air and auxiliary fuel are blown from the tuyere to blow hot metal. However, as an alternative to coke, a cheap, highly combustible, high calorific value fuel is used. (Pulverized coal, petroleum, heavy oil, naphtha, etc.) is blown from the tuyere to reduce the hot metal production cost and improve the productivity, and the technique is disclosed in Japanese Patent Publication No. 40-23763. In particular, in recent years, pulverized coal injection has become the mainstream in terms of price, which greatly contributes to fuel ratio reduction (cost reduction) and productivity improvement.

The auxiliary fuel blown in this way burns in the blast furnace instead of a part of the coke, and due to its good combustibility and high calorific value, it produces a large amount of reducing gas at high temperature and is efficient. Various reduction reactions. Therefore, the iron ore charged from the top of the furnace is rapidly reduced to a metal state and is melted to form high-temperature hot metal, so that the furnace heat of the blast furnace is high and the productivity is improved.

[0004]

In the conventional blast furnace operation, however, the cooling plate, tuyere, and stave cooler that cool the furnace body and bricks of the furnace body of the blast furnace are damaged, and a large amount of water enters the furnace. When a sudden furnace heat shortage occurs as a result of a large amount of iron ore being dropped due to the deposits that have formed on the furnace wall or the iron ore being charged incorrectly, the molten pig iron generated in the furnace solidifies and appears. In addition to being unable to extract from the pig iron, when the amount of air blown for the purpose of resting is reduced, these molten pig iron flows back to the tuyere and blast branch pipes and solidifies, making it impossible to blow air. This state is called cooling of the blast furnace, and the production volume becomes zero, and it takes a long time to recover.

The reason why the recovery takes a long time is that the work of melting the molten pig iron solidified in the furnace, the tuyere portion and the blast branch pipe and causing the molten pig iron to flow out from the tap hole must rely on human power. That is, insert an iron pipe into which oxygen has flowed into the solidified molten slag portion (tuyere and taphole), and perform the work of sequentially melting the solidified molten slag by the combustion heat of the pipe tip by oxygen. ..

When the taphole and the tuyere directly above the taphole communicate with each other by these operations, hot air is blown from the tuyere just above the taphole, and the heat of combustion of the coke in the furnace is generated by the hot air. The solidified molten iron slag of is gradually dissolved and allowed to flow out from the tap hole. If the outflow of molten pig iron from the taphole is smooth, the tuyere immediately above the taphole is sequentially melted. If the normal taphole and the tuyere directly above the taphole cannot be contacted, install a temporary taphole between the tuyere and the normal taphole, and first connect the temporary taphole and the tuyere. In order to achieve the above, the melting work by the combustion heat of the pipe described above is performed.

The dissolution of the solidified molten pig iron is human-powered,
Since the heat of combustion of the iron pipe due to oxygen and oxygen is small for melting, as described above, it takes a long time to recover cooling, and it is not uncommon to take one month or two months. Therefore, the present invention, when cooling occurs in the blast furnace, by automatically injecting a large amount of heat required for melting the solidified molten pig iron into the furnace, recovery of the cooling state in a short period of time, The purpose is to restore production at an early stage.

[0008]

Means for Solving the Problems The present invention is to solve the above problems, in which iron ore and coke are charged in layers from the furnace top, and hot air or hot air and auxiliary fuel are blown from the tuyere, In the blast furnace operating method for extracting molten pig iron from the taphole,
When cooling occurs due to inundation of the furnace or lack of heat in the furnace, insert a plasma torch from the taphole and the tuyere directly above the taphole, and blow hot nitrogen, air, or oxygen into the furnace. Is characterized by. In addition, a temporary taphole is installed between the taphole and the tuyere directly above the taphole, and when coldness occurs, insert the plasma torch from the taphole and the tuyere directly above the taphole. And a plasma arc is generated by energizing between the torches.

[0009]

[Action]

As an example of applying a plasma torch to a blast furnace, as disclosed in Japanese Patent Application Laid-Open No. 57-51207, a large amount of water is generated in the blast furnace and the hearth (the tuyere which is the object of the present invention is Area that exists below the section and the taphole)
There is a technique of injecting heat into the hearth with a plasma torch when it cools and solidifies, but it does not refer to the treatment of molten hot metal, the area to be inserted is different, and as in the present invention, early cooling is possible. It is not intended for recovery.

The method of inserting the plasma torch into the furnace according to the present invention is shown in the sectional views of a part of the blast furnace shown in FIGS. FIG. 1 shows a case in which the plasma torch is inserted through the taphole and the tuyere directly above the taphole. In FIG. 1, 1 is a blast furnace skin, 2 is a brick, 3 is a tuyere directly above the taphole, 4 is a taphole, and 5 is a plasma torch. It is effective that the plasma torch is inserted and melted simultaneously from the taphole and the tuyere directly above the taphole, but the plasma torch may be inserted and melted one by one.

In FIG. 2, a temporary taphole is installed between the taphole and the tuyere directly above the taphole, and a plasma torch is inserted from this extra taphole and the tuyere directly above the taphole. Indicate the case.
In FIG. 2, 6 indicates a temporary tap hole. Also in this case, it is effective that the plasma torches are simultaneously inserted and melted from the temporary taphole and the tuyere directly above the taphole, but they may be inserted one by one and melted.

The plasma torch used in FIGS. 1 and 2 is a non-transfer type and has a structure in which an anode and a cathode are provided in one torch, but as shown in FIG. If the distance between the tuyere and the tuyere directly above the taphole is short, insert a transitional plasma torch from the temporary taphole and the tuyere directly above the taphole as shown in Fig. A method of generating a plasma arc by energizing between them is also possible. In FIG. 3, 7 is an anode and 8 is a cathode.

The gas used in the plasma torch of FIGS. 1 and 2 is nitrogen, air or oxygen. In the case of nitrogen, a large amount of heat is injected to melt the solidified molten pig iron. In the case of oxygen, in addition to this, O ₂ + C
= CO ₂ , O ₂ + 2C = 2CO The amount of heat generated by the gasification reaction of coke can be used for melting.

Further, the temperature of the gas is 1,200 when the melt solidifies.
Since it occurs from 0 ° C, it is necessary to set the temperature to 1200 ° C or higher, and the effect is greater at higher temperatures, but 1400 to 2000 ° C is usually used in consideration of the problem of heat resistance of the probe. Since a large amount of heat is injected at a high temperature, the solidified molten pig iron is melted in a short time, which is very effective. As the gas in FIG. 3, any of nitrogen, air, and oxygen can be used, but the gas temperature is preferably as high as possible because there is no problem with the heat resistance of the probe, and normally 2000-
Use 3000 ° C. In this case, the dissolution of the solidified molten pig iron is further promoted.

[0016]

EXAMPLES The features of the present invention will be specifically described below with reference to examples. Table 1 shows the operation results of the blast furnace according to the present invention in comparison with the conventional method. The target blast furnace is a medium-sized blast furnace with an internal volume of 3000 m ³ , and iron ore and ordinary metallurgical coke were charged in layers from the top of the furnace at a ratio of O / C = 4.2, and the pre-tuyere frame temperature was 2180 ° C (air blowing). Temperature 1200 ℃, blast humidity 25g /
Nm ³ -air, oxygen-enriched amount 0.013Nm ³ / Nm ³
-Air, oxygen enrichment ratio 1.0%, pulverized coal injection amount 100
g / Nm ³ -air) while maintaining 6000 t of hot metal
/ Manufactured per day.

[0017]

[Table 1]

Example 1 A large number of cooling plates for cooling the furnace bricks of the blast furnace were damaged, and a large amount of water entered the furnace. The molten pig iron flowed back into the tuyere and became cold. As shown in FIG. 1, a plasma torch 5 of 2 MW was simultaneously inserted from the taphole 4 and the tuyere 3 directly above the taphole, and nitrogen at 2000 ° C. was blown at 25 Nm ³ / min to produce the taphole 4 This is an example of an operation in which the tuyere 3 directly above the taphole is in contact.

Example 2 Since many tuyere cooling the furnace body of a blast furnace were damaged and a large amount of water entered the furnace, the furnace heat was rapidly lost, and all the blades were decompressed for resting air. The molten pig iron flowed back into my mouth and became cold. As shown in FIG. 1, a 1.8 MW plasma torch was simultaneously inserted from the taphole 4 and the tuyere 3 directly above the taphole,
The air at 1700 ° C was blown at 30 Nm ³ / min, and the taphole and the tuyere directly above the taphole were contacted, but the two could not be contacted. Therefore, as shown in FIG. 2, a temporary taphole 6 is installed between the taphole 4 and the tuyere 3 directly above the taphole, and the temporary taphole and the tuyere immediately above the taphole are simultaneously opened. Insert a 1.8 MW plasma torch 5 and add 1700 ° C air to 30 Nm
^After blowing in ³ / min, the temporary taphole and the tuyere directly above the taphole were contacted, but both were able to contact each other. Then again,
A 1.8 MW plasma torch was inserted from the taphole and the tuyere directly above the taphole at the same time, and air at 1700 ° C. was supplied to 30 Nm ³
/ This is an example of operation in which air is blown in and the taphole and the tuyere directly above the taphole are connected.

Example 3 Since deposits formed on the furnace wall of the blast furnace fell off at once,
The heat of the furnace was rapidly lost, and the debris flowed back to all tuyere during the depressurization due to the breeze, resulting in cooling. As shown in Figure 1,
Insert a 1.5 MW plasma torch at the same time from the taphole and the tuyere directly above the taphole, and add 1400 ° C oxygen to 30 Nm ³
/ Blowed in for a minute, and tried to contact the taphole and the tuyere directly above the taphole, but it was not possible to contact them. Therefore, as shown in Fig. 2, a temporary taphole is installed between the taphole and the tuyere immediately above the taphole, and the temporary taphole and the tuyere directly above the taphole are 1.5 MW at the same time. The plasma torch was inserted, and 1400 ° C. oxygen was blown at 30 Nm ³ / min, and when the temporary taphole and the tuyere directly above the taphole were contacted, they were able to contact each other.
Then, again insert a 1.5 MW plasma torch from the taphole and the tuyere directly above the taphole, and inject oxygen of 1400 ° C at 30 Nm ³ / min, and tap the taphole and the tuyere directly above the taphole. This is an example of an operation in which the department was contacted.

Example 4 A large amount of iron ore was charged due to a failure of the weighing machine for charging iron ore into the blast furnace, the heat of the furnace was rapidly lost, and the molten iron slag was spread to all tuyere during depressurization for the rest of the wind. Ran back and became cold. As shown in FIG. 1, one plasma torch (2 MW) was alternately inserted from the taphole and the tuyere directly above the taphole, and 1900
This is an example of operation in which nitrogen at 30 ° C was blown at 30 Nm ³ / min to connect the taphole and the tuyere directly above the taphole.

Example 5 A large number of stave coolers cooling the furnace bricks of the blast furnace were damaged, and a large amount of water entered the furnace, so that the furnace heat was rapidly lost, and all of the heat was lost during depressurization for resting air. The molten pig iron flowed back into the tuyere and became cold. As shown in Fig. 1, a plasma torch of 1 MW was inserted simultaneously from the taphole and the tuyere directly above the taphole, and nitrogen at 2000 ° C was blown at 15 Nm ³ / min, and the taphole and immediately above the taphole. I tried to contact the tuyere, but I couldn't get in touch with them. Therefore, as shown in FIG. 3, a temporary taphole 6 is installed between the taphole 4 and the tuyere 3 directly above the taphole, and the temporary taphole and the tuyere immediately above the taphole are simultaneously opened. Anode 7
Then, the cathode 8 was inserted, and electricity was passed between both torches to generate a plasma arc. With this, nitrogen of 3000 ° C. is 10 Nm ³ /
It was decided that a minute was blown in, and when the temporary taphole and the tuyere directly above the taphole were contacted, they were able to contact each other. Then, again, 1MW from the taphole and the tuyere directly above the taphole
Insert a plasma torch and insert nitrogen at 2000 ℃ to 15N
This is an example of operation in which m ³ / min was blown in and the taphole and the tuyere directly above the taphole were contacted. In each case, the recovery period for chilling is shorter and the amount of production reduction is smaller than that of the comparative example.

Comparative Example A large number of cooling boards cooling the furnace bricks of the blast furnace were damaged, and a large amount of water entered the furnace, resulting in rapid loss of furnace heat.
During the decompression due to the breeze, the molten iron slag flowed back to all tuyere and became cold. Insert an iron pipe into which oxygen has flowed from the taphole and the tuyere directly above the taphole by human power, and perform work to successively melt the molten pig iron solidified by the combustion heat of the pipe tip due to oxygen. This is an example of operation by the conventional method in which the mouth and the tuyere directly above the taphole are connected. Compared with Example 1, the cooling recovery period is longer and the amount of production is reduced.

[0024]

As described above, in the present invention, when cooling occurs due to inundation in the furnace or lack of heat in the furnace, the plasma torch is inserted from the taphole and the tuyere immediately above the taphole, By blowing high-temperature nitrogen, air, and oxygen into the furnace, it is possible to inject a large amount of heat at a high temperature, so the solidified molten pig iron can be melted in a short time, the cooling recovery period is short, and the production volume is reduced. Also few. Therefore, stable hot metal supply is possible.

[Brief description of drawings]

FIG. 1 is a sectional view of a part of a blast furnace showing a method of inserting a plasma torch according to the present invention.

FIG. 2 is a sectional view of a part of a blast furnace showing a method of inserting a plasma torch according to the present invention.

FIG. 3 is a sectional view of a part of a blast furnace showing a method of inserting a plasma torch according to the present invention.

[Explanation of symbols]

 3 Tuyere directly above the tap hole 4 Tap hole 5 Plasma torch 6 Temporary tap hole

Claims (2)

[Claims] 1. Iron ore and coke are charged in layers from the furnace top, and hot air or hot air and auxiliary fuel are blown from the tuyere,
In the blast furnace operation method for extracting molten pig iron from the taphole, when cold is generated, a plasma torch is inserted from the taphole and the tuyere directly above the taphole to remove hot nitrogen, air, or oxygen. Blast furnace operation method characterized by blowing into the furnace. 2. Iron ore and coke are charged in layers from the furnace top, and hot air or hot air and auxiliary fuel are blown from the tuyere,
In the blast furnace operation method for extracting molten pig iron from the taphole, a temporary taphole is installed between the taphole and the tuyere directly above the taphole, and when the cold occurs, the taphole and the taphole are tapped. A blast furnace operating method characterized in that a plasma torch is inserted from the tuyere directly above the mouth and a plasma arc is generated by energizing between the torches.