JP2003328018A - Method for charging raw material into bellless blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for controlling the distribution of a charged material, which sorts cheap charge materials of poor quality, charges them inside a furnace, and surely piles them in a desired range along a radial direction inside the furnace. <P>SOLUTION: The method for charging a raw material into the blast furnace, which charges an iron source raw material and a carbonaceous material to the inside of the furnace from a blast furnace top, is characterized by controlling the linear velocity V at a nose of a distribution chute, which is expressed by V=L×sinθ×ω [wherein L is a length (m) of the distribution chute; θ is a tilting angle (degree) of the distribution chute; and ω is the tangential velocity (rad/s) of the distribution chute], to a specified value determined in accordance with a type of the raw material, or less. The linear velocity at the nose of the chute in the above charge method is preferably 2.3 m/s or less. <P>COPYRIGHT: (C)2004,JPO

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 charge into a blast furnace, and more specifically, in a bellless blast furnace, in addition to charging an iron source material and a carbonaceous material, a different material is mainly used. The present invention relates to a charging method when charging with a turning chute.

[0002]

2. Description of the Related Art In blast furnace operation, it is a daily task to adjust the gas flow distribution in the radial direction of the furnace to maintain the efficiency or stability of the operation. From that point, control of the charge distribution is the most effective means. Is one. Further, in the recent blast furnace operation, not only productivity and efficiency but also optimal operation taking into consideration reduction of pig iron cost or total energy cost as a steel mill is a major issue.

From the viewpoint of controlling the amount of the charged material, the main problem can be regarded as the problem of distribution control for effectively utilizing the inferior raw material. Here, "poor quality raw material" means
An inexpensive charge whose physical and chemical properties such as particle size, strength, reducibility, and gasification reactivity (collectively referred to as "properties" below) are inferior to those of ordinary raw materials under the reaction conditions in a blast furnace. Say. It should be noted that in the following description, "different materials"
Also called.

Conventionally, such a raw material is often concentrated on the wall of the furnace. As a concrete method, the different raw materials are sorted in advance and another charging operation or charging means is performed. The so-called journal charging method has been applied in which the material is charged into the furnace. The point of distribution control at that time is to stably and surely deposit the heterogeneous material at a predetermined position in the furnace. Therefore, in the bellless blast furnace, conventionally, before charging the heterogeneous material, A charging method in which a flat charging surface is formed in the vicinity of the furnace wall and the raw material is deposited on this portion has been adopted.

Generally, most of the charge charged into the furnace from the top of the blast furnace is charged from the furnace wall portion in the radial direction of the furnace to the middle part of the furnace, so that the furnace is charged into the furnace. A deposition surface with a downward slope is formed from the wall part or the middle part of the furnace toward the center part of the furnace. Therefore, the following requirements are essential for stably and reliably depositing different kinds of raw materials at a predetermined position in the furnace.

[0006] 1) dropping the foreign material to a predetermined position, and 2) stopping the foreign material at that position without moving it from the dropping position.

Further, in order to satisfy the above requirement 2), the following techniques are required.

(A) Appropriately constructing the state of the charging surface at a predetermined position, and (b) suppressing the scattering of the charging material that has dropped to a predetermined position on the charging surface due to recoil.

From the above viewpoint, the conventional charging method will be described.

In Japanese Patent Application Laid-Open No. 61-227108, a bell-less type raw material charging device for charging and distributing raw material from a storage hopper into a furnace through a swirling chute in the furnace, is used for one batch from the storage hopper. The charging raw material is discharged according to the particle size, and the inclination angle of the turning chute in the furnace, the turning speed, and the discharging speed are controlled according to the area of each charging zone in the furnace to flatten the level of the furnace internal charging material. A method for controlling the radial particle size distribution is described.

Japanese Unexamined Patent Publication (Kokai) No. 62-290810 discloses a bellless blast furnace in which a plurality of types of iron sources and reducing agents having different particle sizes and properties are charged in a divided direction from the center of the furnace toward the wall of the furnace. In addition to controlling the tilt angle of the distribution chute, the shape tilt angle of the distribution chute and the number of turns at each tilt angle are controlled so that the deposition angle of the raw material surface after charging does not exceed 20 degrees. , A method for improving the controllability of the particle size distribution in the radial direction. Japanese Patent Laid-Open No. 195028/1993 includes a turning angle detector that detects the turning direction of a turning distribution chute and outputs a turning direction signal, and a turning speed pattern of the distribution chute for each turning direction of the distribution chute. Equipped with a swirl speed function generator that outputs a swirl speed reference signal according to the swirl direction signal, and controls the swirl speed of the distribution chute according to the swirl speed reference signal to eliminate the circumferential deviation of the contents inside the furnace. A possible charge distribution control device is described. However, in both the method described in JP-A-61-227108 and the method described in JP-A-62-290810, the charging surface is made flat by dropping the charging material after dropping. The focus is on suppressing the phenomenon of moving along the slope and merely presenting a method for satisfying the requirement (a). Also,
In the device described in Japanese Patent Laid-Open No. 195028/1993, the requirement (b) is not considered.

However, since the raw material to be charged has momentum when falling into the furnace, it causes a recoil phenomenon after it collides with the charging surface, and stops at a position different from the dropping position. However, since the deposited layer is formed, the above requirement (b) cannot be satisfied. This not only causes the deposition position of the different raw materials to be displaced from the desired position, but also unnecessarily expands the deposition range, resulting in a reduction in accuracy of distribution control.

In particular, when a charge having a property greatly different from that of a normal raw material is used as the different raw material, there is a great possibility that the operation of the blast furnace will be adversely affected. That is, in order to improve the distribution controllability of different raw materials, the above requirement (b)
It is absolutely necessary to take concrete measures to satisfy the above.

[0014]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention, not to mention inferior and inexpensive charging materials,
For example, iron source materials that have been sieved to a specific particle size to adjust the radial gas velocity distribution in the furnace or iron source materials with different reducibility and basicity to adjust the cohesive zone level in the radial direction. The charge for adjusting the condition in the furnace,
Sorted from normal iron source raw material or carbon material and charged into the furnace,
An object of the present invention is to provide a charging method with good distribution controllability, which enables reliable deposition in a desired radial range.

[0015]

Means for Solving the Problems In order to achieve the above-mentioned objects, the present inventors have studied the problems of the above-mentioned prior art and obtained the following findings.

A) The recoil phenomenon caused by the charge dropped from the chute into the furnace at the falling position on the furnace interior charge surface is generally the horizontal velocity of the charge when it falls into the furnace. It is dominated by the components (radial direction of swirl chute, ie, furnace radial direction, and tangential direction of swirl chute, ie, furnace circumferential direction).

B) The horizontal velocity component of the above a) is applied when the charged material leaves the tip of the chute, and does not change in the subsequent free fall process. Therefore, in order to increase the rate at which the charging material stops and accumulates at the falling point (hereinafter also referred to as “deposition yield at the falling point”), the horizontal velocity component when the raw material leaves the chute tip is suppressed as much as possible. Good. c) The radial velocity component and the tangential velocity component that make up the horizontal velocity component both change depending on the tilt angle of the distribution chute, but the tangential velocity component is approximately the same size as the radial component. The velocity component in the tangential direction is a factor that deteriorates the deposition yield at the dropping point of the charging material. d) If an upper limit value is set for the tip linear velocity of the distribution chute of the bellless type blast furnace, and the tilt angle and swirl speed of the distribution chute are selected to satisfy these values, the kinetic energy of the raw material when it lands on the charging surface is reduced. Among them, the energy provided by the turning motion of the distribution chute can be suppressed, and the deviation between the landing position and the deposition position due to recoil can be suppressed.

The present invention has been completed based on the above findings, and the gist thereof lies in the method described below.

(1) A method for charging a raw material for a bellless blast furnace, in which an iron source material and a carbonaceous material are charged into the furnace from the top of the blast furnace,
A raw material charging method for a bellless blast furnace, wherein the linear velocity V at the tip of the distribution chute represented by the following formula (1) is set to a predetermined value or less determined by the type of raw material. V = L × sin θ × ω (1) where, L: distribution chute length (m), θ: distribution chute tilt angle (degrees), ω: distribution chute rotation speed (rad / s).

(2) The method of charging a raw material for a bellless blast furnace according to the above (1), characterized in that a raw material having a physical or chemical property different from that of a normal raw material is sorted and charged. (3) The raw material charging method for a bellless blast furnace according to (1) or (2) above, wherein the linear velocity at the tip of the distribution chute is 2.7 m / s or less. In the present invention, the “raw material” includes an iron source raw material such as sinter, lump ore and pellets, and carbonaceous material such as coke and coal.

In the case of an iron source raw material, "ordinary raw material" means a particle size of 5 to 50 mm and a JIS reducibility: 60 to 75.
% And reduced powdering index: 30% to 50% are both satisfied. Further, in the case of carbonaceous material, the particle size is 30 to 10
0 mm and rotational strength (DI15150): 81-86
It means the one that satisfies%.

The term "raw materials having different physical or chemical properties" refers to raw materials having some or all of the above properties.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION In a bellless blast furnace, when raw materials are charged into a furnace by a distribution chute, the following steps are taken.

The raw material flows down in the distribution chute and reaches the tip of the chute. In this process, its behavior is affected by the following factors. That is, the falling speed when the hopper falls onto the distribution chute, the length of the distribution chute, the tilt angle of the distribution chute, the swirling speed of the distribution chute, the coefficient of friction between the chute and the raw material, and the like.

The raw material in the distribution chute is gravity,
The centrifugal force, the Coriolis force, and the frictional force with the inner surface of the distribution chute act, and as a result, each component of the moving speed when the raw material leaves the chute tip is determined.

After leaving the tip of the chute, the raw material makes a free-fall motion with the velocity at the time of detachment as the initial velocity, and falls onto the charging surface. The raw material charging method of the present invention will be described in detail below.

FIG. 1 is a schematic diagram for explaining the behavior of raw material dropping from a distribution chute, and FIG. 1 (a) is a side view,
The figure (b) shows a plan view. The raw material supplied from the furnace top bunker to the distribution chute flows downward on the inner surface of the distribution chute which is performing a swirling motion, and falls freely from the tip of the chute to reach the furnace interior entrance surface.

The inventors of the present invention conducted a charging experiment using a full-scale model of the bellless blast furnace charging device, analyzed the actual measurement data of the raw material drop trajectory from the tip of the distribution chute, and then removed the tip of the chute. The motion velocity of the charged particles was divided into the vertical component, radial component, and tangential component for comparison. Raw material: Sinter, Particle size: 5 to 50 mm, Outflow rate from chute: 1400 kg / s, Table 1 shows the results.

[0029]

[Table 1]

The reason why the raw material causes the recoil phenomenon at the dropping position in the furnace is that the raw material has a large horizontal velocity component at the time of dropping to the inner surface of the furnace. The recoil phenomenon at the dropping position deteriorates the controllability of the deposition surface shape of the charging material, that is, the distribution of charging material, which affects the gas flow velocity distribution in the furnace, and thus reduces the controllability of blast furnace operation. Becomes

This horizontal velocity component is applied when the charged material leaves the tip of the chute, and does not change in the subsequent free fall process. That is, in order to improve the deposition yield at the dropping point of the charged material, it is necessary to suppress the horizontal velocity component of the falling raw material at the time of leaving the tip of the chute as much as possible.

As shown in FIG. 1, the horizontal velocity component (Vh) can be decomposed into a radial velocity component (Vr) and a tangential velocity component (Vt). Here, the radial velocity component is roughly governed by the tilt angle (θ) of the distribution chute, and can be considered to be the velocity required to reach the predetermined position in the radial direction inside the furnace. When the tilting angle is constant, the directional velocity component is governed by the linear velocity at the tip of the distribution chute, and can be regarded as the peripheral velocity of the rotating body generated by turning the distribution chute.

Therefore, considering the results of Table 1 in consideration of this point, both the radial direction velocity component and the tangential direction velocity component forming the horizontal direction velocity component change depending on the tilt angle, but the tangential direction velocity component is The value is almost the same as the radial velocity component, and it can be understood that turning the distribution chute gives a factor that deteriorates the deposition yield at the dropping point of the charge.

Therefore, particularly when a small amount of raw material needs to be localized and deposited in a predetermined range in the furnace, the tangential velocity component is suppressed when charging different raw materials,
That is, it is effective to reduce the linear velocity at the tip of the distribution chute to a predetermined value or less determined by the properties of the raw material.

According to the investigation by the present inventors, the above-mentioned predetermined value is as follows.

[0036]     Iron source material: Particle size: 10 to 20 mm: 2.8 m / s,                       For 5 to 10 mm: 2.3 m / s,

[0037]

EXAMPLES Example 1 An experiment was carried out on a full-scale model of a bellless blast furnace charging device. In the experiment, the distribution chute length shown in Table 1 was 4.5 m, the distribution chute rotation speed was 8 rpm, and the distribution chute tilt angle was 45 degrees.
By selecting the experimental conditions that keep the radial velocity component and the vertical velocity component constant, and changing the linear velocity at the tip of the distribution chute, various tangential velocity components of the charge when the distribution chute is disengaged were used. It was

A colored tracer ore was charged on the simulated charging surface covered with the ore, and the deviation between the falling position and the center position of deposition (the position where the deposited layer thickness is maximum) and the charging amount were 80.
The deposition width including% was measured. [Conditions] Raw material: Ore, particle size: 5-10 mm, outflow rate from chute:
1400 kg / s, simulated charging surface: ore, particle size: 5 to 20 mm, charging surface shape: horizontal plane.

FIG. 2 is a schematic diagram for explaining the swirling motion of the distribution chute, and FIG. 3 is a diagram showing the influence of the chute tip speed on the in-furnace deposition distribution of different raw materials. According to the result of FIG. 3, the linear velocity at the tip of the distribution chute is 2.3 m /
By setting it to be s or less, the deviation between the drop position and the deposition center position is reduced, and the deposition width is reduced, so that it is possible to reliably deposit the different raw material at a desired position. (Example 2) [Conditions] Charging material: ore, particle size: 10 to 20 mm, outflow rate from chute: 1400 kg / s, simulated charging surface: ore, particle size: 5 to 20 mm, charging surface shape: horizontal Plane. FIG. 4 is a diagram showing the influence of the shoot tip speed on the distribution of the normal raw material in the furnace. According to the result of FIG. 4, by setting the linear velocity at the tip of the distribution chute to 2.8 m / s or less, the deviation between the drop position and the deposition center position is reduced, and the deposition width is reduced. Even in the case of, it is possible to surely deposit at a desired position.

[0040]

EFFECTS OF THE INVENTION According to the method of the present invention, in a bellless blast furnace, mainly inferior and inexpensive charging materials and the like are sorted into a normal iron source material or carbonaceous material and charged into the furnace, and the Since the gas can be reliably deposited in a desired range, the gas flow distribution in the radial direction of the blast furnace can be stabilized, and the cost minimum operation can be greatly contributed.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a material dropping behavior from a distribution chute, in which FIG. 1 (a) shows a side view and FIG. 1 (b) shows a plan view.

FIG. 2 is a schematic diagram illustrating a turning motion of a distribution chute.

FIG. 3 is a diagram showing the influence of the shoot tip speed on the deposition distribution of different raw materials in the furnace.

FIG. 4 is a diagram showing the influence of the shoot tip speed on the deposition distribution of normal raw material in a furnace.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kaoru Nakano             4-53 Kitahama, Chuo-ku, Osaka City, Osaka Prefecture             Sumitomo Metal Industries, Ltd. F-term (reference) 4K012 BC01

Claims (3)

[Claims] 1. A raw material charging method for a bellless blast furnace in which an iron source raw material and a carbonaceous material are charged into the furnace from the top of the blast furnace, and a linear velocity V at the tip of a distribution chute represented by the following formula (1) is A method for charging a raw material for a bellless blast furnace, which is set to a predetermined value or less determined by the properties of the raw material. V = L × sin θ × ω (1) where, L: distribution chute length (m), θ: distribution chute tilt angle (degrees), ω: distribution chute rotation speed (rad / s). 2. The method for charging a raw material for a bellless blast furnace according to claim 1, wherein a raw material having a physical or chemical property different from that of a normal raw material is sorted and charged. 3. The linear velocity at the tip of the distribution chute is 2.3 m.
/ S or less, the raw material charging method of the bellless blast furnace according to claim 1 or 2, characterized in that.