JPH0565517A - Method for operating blast furnace - Google Patents

Abstract

PURPOSE:To provide an operational method of blast furnace achieving the stable operation by directly heating the furnace core part in the blast furnace to raise the temp. therein. CONSTITUTION:At the time of stopping the blasting in the blast furnace 1 operation, a metallic pipe 4 having plural openings in the longitudinal direction of the side face is inserted in the furnace from a tuyere 3 and gas is fed into the furnace from the above metallic pipe 3. But, in the above metallic pipe 3, finally, a means for inserting this pipe into the furnace is separated at the connecting part with a means for feeding the gas and left into the furnace.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blast furnace operating method for achieving stable operation by directly heating and raising the temperature of the core of a blast furnace.

[0002]

2. Description of the Related Art The state of a blast furnace changes depending on the quality of reducing ore and the easiness of pulverizing ore, coke and the like. Also
Phenomena such as slips and blow-throughs may occur suddenly, which deteriorates the furnace conditions. Further, in recent years, a low Si operation has been aimed at in order to reduce the burden of the steelmaking process. Therefore, when the combustion ratio is lowered and the furnace heat is lowered, cooling is likely to occur due to fluctuations in the furnace conditions.

When the reactor condition deteriorates due to these things,
The O / C ratio (ore / coke) is lowered to operate and the furnace condition is recovered. However, when the furnace conditions are not good, uneven flow of the gas in the furnace often occurs, blow-through frequently occurs, and it often takes time to recover. Moreover, most of the heat generated in front of the tuyere is consumed for heating the charge above the tuyere, and the lower part is not directly heated, so it takes a long time to heat up when the lower part of the furnace cools. There is a problem that the amount of tapped iron decreases during this period.

As a means for solving this problem, the applicant of the present application has previously disclosed in Japanese Patent Laid-Open No. 2-85309 that the furnace core is directly blown while the temperature of the furnace core is lowered during the operation of the blast furnace while the tuyere is blown. The technique of heating and raising the temperature is disclosed. This is because, as described above, the conventional means for lowering the O / C has a poor quick effect for recovering the cooling of the furnace core, so that oxygen gas, oxygen-enriched air, compressed air or a heating gas thereof, or Fuel such as combustible gas or coke burned by these is blown directly toward the core of the furnace by using the tuyere. Plasma heating may be used as the heating means, and a lance may be inserted from other than the tuyere.

[0005]

This method is an effective method for rebuilding the furnace condition when the reactor core is cooled or the circumferential balance is disturbed and the reactor condition goes into a bad state. However, the lance needs to be inserted with the tuyere blown, the structure is complicated due to water cooling, and the pressure of the blast furnace charge must be endured at high temperature, so the cost is considerably high. In particular, if it is installed at any number of places around the blast furnace, the economic burden will increase. The present invention is intended to easily achieve the same effect as that of the technique disclosed in JP-A-2-85309 at a lower cost.

[0006]

Means for Solving the Problems The present invention is intended to solve the above problems, and a metal tube having a plurality of holes along the lengthwise direction of the side is installed from the tuyere to the inside of the furnace when the blast furnace is in a still wind. Gas is fed into the furnace by the metal pipe, but the metal pipe finally separates the means for inserting into the furnace or the means for feeding gas and the connecting portion into the furnace. It is characterized by being left behind. In addition, the range in which the metal tube has holes corresponds to the range of the inactive part of the furnace core during its use, and it is also characterized in that the metal tube is inserted at multiple locations around the blast furnace. is there.

[0007]

In the present invention, the metal pipe is inserted from the tuyere when the blast furnace operation is in a blast, and FIG. 1 is a sectional view of a part of the blast furnace 1 showing this situation. The air tube 6 is connected to the metal tube 3 and inserted from the tuyere 2, and the air tube 6 is pushed by the pushing device 5,
The metal tube 3 reaches the furnace core 4. In this case, according to the experience of the present inventors, it is possible to insert a metal tube having a diameter of, for example, about 100 mm to the furnace core portion only by applying a pushing force without taking any special excavation means.

FIG. 2 is a vertical cross-sectional view showing the metal tube 3 and the air supply tube 6, the metal tube 3 is closed at its front end, but a plurality of holes 7 are opened along the longitudinal direction of the side surface. When the core of the blast furnace is cooled and becomes inactive, its position may be the surface layer, the center, or the whole position. In the method of the present invention, the insertion depth of the metal tube is adjusted according to the symptoms at the time of use to determine the range in which the hole 7 is formed in the metal tube 3 so that the gas can be fed to necessary places without waste and the core Can be activated. Further, the metal tube may have a required portion in the shape of a wire mesh. In this case, a reinforcing material can be placed inside the metal tube to maintain the strength.

The metal tube 3 is inserted into a predetermined position by the pusher 5, and then the gas feeding is started through the air feeding tube 6 as it is. After the gas feeding is completed, when the pusher 5 retracts, it is automatically separated at the connecting portion 8 with the air feeding pipe 6. In other words, it is just a mating and can be removed freely. Since the metal tube is finally left in the furnace, it is preferable that the entire length of the metal tube fits in the blast furnace. If the length is outside the furnace, this part needs to be treated after use.

Further, a relatively short metal tube 3 is used, which is pushed by the pusher 5 and then evacuated before or during the start of gas feeding, and the air feeding tube 6 is detached and the tip end is tuyed. It is also possible to feed gas by retracting it to the vicinity. Once the pipe is inserted, the filling rate of the coke is lowered even if the pipe is removed, so that the gas can be sufficiently supplied to the metal pipe 3 even when the metal pipe 3 and the air supply pipe 6 are separated. This method uses a metal tube 3
This is preferable for protection of the air pipe 6 when the length is short.

In the above, the case where the means for inserting the metal tube 3 into the furnace and the air supply tube 6 as the means for sending the gas are the same is shown, but it goes without saying that they may be different. That is, the metal tube 3 is pushed in by a pushing rod different from the air feeding pipe 6,
This is a method of extracting it and inserting the rear air supply pipe 6.

Heat-resistant steel having high strength at high temperature is desirable as the material of the metal tube, but in the method of the present invention, the metal tube is finally left in the blast furnace, and is inexpensive in consideration of the time to be used. It is also possible to use ordinary steel.
During the insertion operation and before the start of use, a small amount of a cooling gas such as nitrogen is allowed to flow to cool the metal pipe, so that a plain steel pipe can also be sufficiently used. In the case of heat-resistant steel, Cr, Ni, etc. enter the hot metal, but the quantity is small and it does not pose a problem. It should be noted that the metal tube 3 itself is softened or melted by the heat in the furnace, but even in this case, the space where the metal tube was passed is not immediately filled with coke and the space is not blocked, so that the gas The delivery can continue quite effectively.

Air, oxygen-enriched air, oxygen or the like is used as the gas to be fed to the furnace core through the metal tube. Oxygen in these gases reacts with the coke in the furnace core to generate heat. In this case, it is still effective to heat the gas to raise its temperature, and plasma heating is also used as the heating means. The gas supply from the metal tube is started before the blast furnace blows off air.
Normally, after inserting the metal tube, gas is continuously fed.
As a result, it is possible to effectively heat and raise the temperature of the furnace core and recover the cooling.

Although it is possible to continue the gas supply even after starting the air blowing from the tuyere of the blast furnace, the raceway portion becomes extremely hot, so when continuing the gas feeding, the air blowing branch pipe of the tuyere is shut off. There is a need to.

It goes without saying that the gas feeding by inserting the metal tube as described above can be simultaneously performed at several places around the blast furnace. The method of the present invention, as described above, when the blast furnace is blown out due to poor furnace conditions during operation, it is not only carried out before reopening the blast furnace, but when the operation is resumed after a long break, the amount of tapping It is also effective as a means to enable the rapid start-up.

[0016]

[Example] A JIS standard SUS430 stainless steel pipe having an outer diameter of 100 mm and a length of 5.5 m, which has a large number of holes extending over a range of 2.5 m from the tip, is inserted from a tuyere by an inserting machine when there is no wind. did. The insertion depth is such that the front end of the metal tube is 50 cm deeper than the tuyere tip.

Air heated to plasma at 1800 ° C. as a gas was blown into this at 50 N cubic meters / min.
The furnace core temperature was 1120 ° C. as measured by a temperature probe equipped with an optical fiber, but the temperature could be raised to 1450 ° C. by feeding gas for 25 minutes. After that, the ventilation from the tuyere was resumed, but the furnace condition was in good condition.

[0018]

According to the present invention, when an inactive portion is formed due to cooling of the core portion of the blast furnace, gas can be directly fed to provide heat to quickly restore the furnace condition. Since a metal pipe having no water cooling structure is used as a gas blowing pipe, it becomes a consumable item, but it is left as it is in the furnace and there is no need to collect it, so that the cost is eventually reduced. Further, by setting the range of the holes formed on the side surface of the metal tube to the range of the inactive portion of the furnace core during use, it is possible to efficiently and intensively heat the necessary portion.

[Brief description of drawings]

1 is a cross-sectional view of a portion of a blast furnace illustrating the method of the present invention.

FIG. 2 is a vertical sectional view of a metal pipe and an air supply pipe used in the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Morimasa Ichida 20-1 Shintomi, Futtsu City, Chiba Nippon Steel Corp. Central Research Division

Claims (3)

[Claims] 1. A metal tube having a plurality of holes along the lengthwise direction of its side is inserted into the furnace from the tuyere at the time of blast furnace operation with no wind.
The gas is fed into the furnace by the metal tube, but the metal tube is finally left in the furnace by being separated from the means for inserting the gas into the furnace or the joint with the means for feeding the gas. A method for operating a blast furnace, which is characterized in that 2. The method of operating a blast furnace according to claim 1, wherein the range in which the metal tube is perforated corresponds to the range of the inactive portion of the furnace core during its use. 3. The blast furnace operating method according to claim 1, wherein the metal pipes are inserted at a plurality of locations around the blast furnace.