JPH11172307A - Charging method of charged material into blast furnace when being difficult to form horizontal type terrace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging method of charged material at the time of being difficult to form a horizontal type terrace with the charged material layer of coke, ore, etc., in the furnace top part in a bell-less type blast furnace. SOLUTION: At the time of forming the horizontal type terrace with the charged material from the furnace wall side by adjusting a swing chute for charging the charged material into the blast furnace of bell-less, in the case that the formation of the necessary horizontal type terrace surface is difficult, coke is charged positively in a prescribed range of furnace center part of the blast furnace. At the time of being difficult to form the horizontal type terrace, the horizontal type terrace can surely be formed by executing the above method, and since the stability of the deposited shape of the charged material near the furnace wall can be secured and the stable peripheral gas flow in the circumferential direction can easily be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for charging a bell-less blast furnace when it is difficult to form a horizontal terrace with a layer of a charge such as coke or ore at the furnace top.

[0002]

2. Description of the Related Art Charge distribution control is one of the main control means in a blast furnace. Charge distribution control is the most commonly used and most important control means because it is the only means to determine the gas flow distribution and cohesive zone shape that govern the reaction heat transfer in the furnace. In a bellless blast furnace, the charge discharged from the tip of a charge chute (hereinafter referred to as a swirl chute) at the top of the blast furnace is dropped into the furnace. accumulate. Therefore, when the drop point is on the furnace wall side, the deposition profile of the charge is V-shaped, and when the drop point is away from the furnace wall side and inside the furnace, the deposition profile of the charge is M. Be a type.

[0003] In the conventional charging method, the deposition profile of both ore and coke is V-type or M-type, or V-type and M-type.
It becomes a combination of types. Thus, the gas flow distribution in the furnace and the shape of the cohesive zone are determined by the radial distribution of the ventilation resistance determined by the deposition profile. However, in the case of the V-shaped distribution, although the particle size segregation can be used to the maximum extent, it is suitable for strengthening the central flow. The material powder concentrates and accumulates near the furnace wall, which is highly likely to be a factor of the formation of deposits on the furnace wall.

In the case of the M-type distribution or the combination distribution of the V-type and the M-type, the ore and coke layers near the furnace wall are changed due to a change in the radial position of the charge apex caused by the variation of the falling trajectory. Since the thickness ratio (hereinafter, referred to as O / C) easily changes greatly, there is a large possibility that the gas flow near the furnace wall will become unstable.

FIG. 1 shows a V-shape and an M with a normal turning chute.
This shows the loading state of ore and coke in the case of the combination distribution of types, and even if the position of the turning chute is at the same position, the ore and coke fall off at the drop location, and due to the difference in the angle of repose It can be seen that the state of the charge layer to be deposited is different. Note that the dotted line shows the displacement of the charging position when charging coke, indicating that the charging position was slightly biased toward the inside of the furnace due to the difference in the wear of the turning chute and the type and grain size of coke. I have. For this reason, the coke amount on the furnace wall side is reduced, and an uneven charge layer is formed.

In such a state, the state of charge accumulation on the furnace wall becomes non-uniform, and this non-uniformity changes the air permeability in the furnace, causing abnormalities in the gas flow distribution in the furnace, especially in the peripheral gas flow. As a result, this causes abnormalities in the furnace situation, such as so-called unloading abnormalities and wall attachment. Therefore, it is possible to disperse the powder from the vicinity of the furnace wall as much as possible, and to make the fluctuation of the O / C near the furnace wall extremely small due to the change of the falling trajectory, and to form the charging layer surface in a horizontal terrace shape. desirable. That is, if the ideal type terrace as shown in FIG. 2 is formed, a charged layer having excellent uniformity can be obtained, and various obstacles caused by the disturbance of the charged layer can be overcome.

Conventionally, a technique for forming a horizontal terrace has been disclosed in, for example, Japanese Patent Application Laid-Open No. 6-145731. The technology requires special equipment, and the reciprocating motion at each circumferential position in the blast furnace is performed by means of a load leveling tool provided at a plurality of circumferential positions at the top of the furnace in the blast furnace. Extruding the charge on the wall side toward the furnace center,
In addition, a predetermined amount of a raw material flat portion is formed on the furnace wall by scraping. Therefore, the charge accumulation state in the furnace circumferential direction, particularly the charge accumulation state in the furnace wall portion, can be made uniform.

[0008] In such a conventional method, a device for stirring the charge at a plurality of positions in the circumferential direction of the top of the blast furnace is required, and as the size of the blast furnace increases, the required equipment scale becomes larger. Inevitably, it is hard to say that it is an excellent method from the viewpoint of cost. Accordingly, the present inventors have conducted intensive studies and attempted to develop the above-mentioned problems in order to achieve the formation of a horizontal terrace for both the target coke and the ore without special equipment. As a result, the above-mentioned object can be achieved by a simple method of simply operating the charging pattern of the charged material at the time of charging the blast furnace. Japanese Patent Application No. 9-269161, entitled “Horizontal Terrace of Blast Furnace Top Charged Material”. Forming method "(hereinafter referred to as the prior invention).

In summary, in a bellless blast furnace, the inclination angle of the surface of the furnace top charge layer is adjusted by ± 15 degrees with respect to the horizontal by adjusting the rotating chute for charging the charge in the blast furnace. Forming a terrace that falls within the range and that the tip of the terrace of the furnace top charge layer falls within the range of 0.1 to 0.6 from the wall of the blast furnace at a relative distance divided by the furnace radius; Is formed from the furnace wall side, and the charging pattern is adjusted by adjusting the charging pattern by the swirling chute in accordance with the charging of the charge. In addition, the charging operation and the terrace forming operation are performed in a method of forming a horizontal terrace of the blast furnace top charging by performing coke charging prior to ore charging.

[0010]

However, when the above-mentioned invention developed by the present inventors is practiced, a situation in which a desired horizontal terrace cannot be obtained sometimes occurs at an early stage of forming a horizontal terrace. found. Accordingly, the present inventors have conducted a number of studies to elucidate the reason.Under the current high pulverized coal injection operation, the upward flow of gas blown from the tuyere section that ascends the blast furnace shaft section. Non-uniformity and uneven flow around the blast furnace wall,
For example, as shown in FIG. 3, there is a case where the flow of the gas rising flow strongly occurs on the furnace wall side, and the effects of the prior application of the present invention in which the charged material is charged into the blast furnace from the periphery of the furnace wall are variously affected. In some cases, it may be difficult to smoothly deposit the charge on the periphery of the furnace wall.

[0011] Further, the rate of descent differs between the charge charged in the periphery of the furnace wall and the charge in the center of the furnace or / and between the furnace wall and the center. If very fast,
On the contrary, it was found to have a similar effect on the loading of the charge. An object of the present invention is to provide an appropriate means for stabilizing a descending speed of a charged material in order to equalize an ascending gas flow in a blast furnace when the above phenomenon occurs. Is what you do.

[0012]

The gist of the present invention lies in the following means. (1) In a bellless blast furnace, a required horizontal terrace surface is formed by forming a horizontal terrace from the blast furnace wall side by adjusting a rotating chute for charging a charge in the blast furnace. The method for charging a blast furnace charge when it is difficult to form a horizontal terrace inside the blast furnace, in which coke is positively charged into a predetermined area in the center of the blast furnace when difficulties arise. (2) The coke charged into the predetermined range of the central part of the blast furnace is only charged with coke separately from the normal charging. Material loading method.

(3) The blast furnace mounting in the case where it is difficult to form a horizontal terrace in the blast furnace according to (1) or (2), wherein a predetermined range of the center of the blast furnace is at least a region of 10% from the furnace center by a furnace opening radius. Packing method. (4) The blast furnace charging in the case where it is difficult to form a horizontal terrace in the blast furnace according to any one of (1) to (3), wherein the particle size of the coke charged into a predetermined range in the central portion of the blast furnace is 50 mm or more. Material loading method.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted various studies and studies on how to solve the above-mentioned conventional technical problems, and as a result, have found a solution as in the present invention. It is. As described in the section of “Problems to be Solved by the Invention”, when the gas ascending flow in the blast furnace is not uniform, the target blast furnace charge must be eliminated as soon as the uneven flow is eliminated. The formation of a horizontal terrace by the method requires time to form a stable horizontal terrace even if the charging method described in the invention of the prior application is adopted, and many inconveniences may occur in the operation of the blast furnace. .

The inventors of the present invention first introduced a large amount of coke having a low resistance to gas flow into the furnace center in order to suppress a rising gas flow flowing in a large amount around the blast furnace wall. A large part of the rising gas flow flowing around the furnace wall can be reduced in a short period of time by creating a part where the flow of the rising gas flow is easy at the center of the furnace and temporarily increasing the rising gas flow in that part. It was concluded that it was possible to prevent the gas flow in the entire furnace in a substantially uniform state, and to apply it when charging the blast furnace with the charge, which hindered the implementation of the invention of the earlier application. It has been confirmed that the present invention can be carried out without any problems, and the development of the present invention has been reached.

The method of charging coke to be charged into the center of the blast furnace is not particularly limited. However, the position of the swirling chute is set so that only the coke can be intentionally charged into the center of the furnace at the time of normal charging. The charging can be performed by adjusting the charging timing, the charging amount, and the like, and it is also possible to perform only the coke charging separately from the normal charging.

The charging range of the coke to be charged into the center of the blast furnace is preferably at least a region of 10% in the furnace opening radius from the center of the furnace, and the particle size of the coke is to reduce the resistance of the gas ascending flow. From a viewpoint, a particle size of 50 mm or more is preferable. The amount of coke charged to these blast furnace centers should be adjusted to maintain the overall charge O / C within a fixed range of the overall charge O / C.

When the rising gas flow in the blast furnace is unstable and non-uniform, it is possible to obtain a stable and uniform distribution of the rising gas flow by implementing the method of the present invention. According to the method, the horizontal terrace can be formed extremely easily by the charging method of the charging material described in the above-mentioned prior application invention.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention was carried out in a blast furnace in operation, and its effects were confirmed. The blast furnace that was operated was a bellless blast furnace having an internal volume of 3280 m ^{3 in} which pulverized coal was being injected. Since it was not formed, the implementation of the present invention was started. Therefore, at the time of charging the blast furnace charge with a normal swirling chute, an attempt was made to charge coke into the center of the blast furnace (about 10% of the furnace radius from the furnace center) separately from the normal charging. The particle size of the coke was about 70 mm (average particle size), and the charging was repeated 10 times (over about 2 hours). Can be stored in

As a confirmation of this effect, FIG. 4 shows a time series of changes in η _CO around the blast furnace wall due to the shaft sonde. It is clear from the figure that the change is small and stable after 2 hours by implementing the present invention.
The judgment of the formation state of the terrace described in the present invention is based on the detection result of the obtained deposition profile measured by the profile meter installed on the furnace top.

[0021]

As described above, according to the charging method of the present invention, the effect can be exhibited when it is difficult to form a horizontal terrace. After implementation of the present invention, the horizontal terrace can be reliably formed, and the stability of the deposited shape of the charge in the vicinity of the furnace wall can be ensured. Therefore, it is easy to form a stable peripheral gas flow in the circumferential direction. As a result, it became possible to maintain a significant advantage in blast furnace operation.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a state of accumulation of a charge by normal charging.

FIG. 2 is a view showing formation of an ideal horizontal terrace;

FIG. 3 is a diagram showing a situation in which rising gas is deflected and flows much on the furnace wall surface.

FIG. 4 is a diagram showing a change in η _CO around a furnace due to a shaft sonde before and after implementation of the present invention.

Claims (4)

[Claims] In a bellless blast furnace, when a swirling chute for charging a charge in a blast furnace is adjusted, when forming a horizontal terrace by a charge from the blast furnace wall side,
When it is difficult to form the required horizontal terrace, the coke is positively charged into a predetermined area in the center of the blast furnace. Method. 2. The horizontal terrace in a blast furnace according to claim 1, wherein the coke charged into a predetermined area in the central portion of the blast furnace is only charged with coke separately from the normal charging. Blast furnace charging method when forming is difficult. 3. A blast furnace horizontal terrace formation is difficult according to claim 1 or 2, wherein a predetermined range of the blast furnace central portion is at least a region of 10% in a furnace opening radius from the furnace center. Blast furnace charging method at the time. 4. A horizontal terrace in a blast furnace according to claim 1, wherein the particle size of the coke charged in a predetermined range in the central part of the blast furnace is 50 mm or more. Blast furnace charging method when forming is difficult.