JPH02236211A - Furnace top charging method in bellless blast furnace and apparatus thereof - Google Patents

Abstract

PURPOSE:To reduce deviation of charged material in circumferential direction and to obtain the ideal distribution of the charged raw material in radius direction by mutually colliding and joining the raw material from mutually facing two directions and dropping on a swinging chute. CONSTITUTION:A collecting chute 3 and a vertical chute 3a are arranged below a bunker 1 and the swinging chute is arranged below them. At the time of dividing the raw material flow 5 discharged from a bunker 1 into two parts and again joining them from mutually reverse directions by arranging straightening plate-like projections 10 in the collecting chute 3, etc., speed component of horizontal direction can be eliminated and the drop of the raw material from the vertical chute 3a to the swinging chute becomes almost only the component of vertical direction. Therefore, the deviation of distribution in the circumference direction of the raw material spread on the blast furnace is eliminated. Further, when the charged raw material piles in the furnace, the distribution in the radius direction of the raw material grain size becomes such an ideal distribution that fine grain at the furnace wall side and coarse grain at the furnace center side are charged.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a method and apparatus for top charging a bellless blast furnace. [Prior art 1] Figure 2 is a diagram showing an example of the occurrence of ore/coke (0/C) distribution deviation in the inner peripheral direction of the blast furnace, which is caused by charging raw materials into the blast furnace. The blast furnace charging equipment consists of a plurality of furnace top bunkers 1.2 installed opposite each other, a collecting chute 3, a vertical chute 3a, and a rotating chute 4 capable of changing direction. When raw materials are charged through this charging device, the following problems occur.

The raw material passing through the vertical chute 3a retreats through different falling routes within the vertical chute depending on which top bunker 1.2 it is discharged from, resulting in a drift. For this reason, the falling raw materials fall at different positions on the rotating chute 4, so the moving distance on the chute is di. d2. As a result, the travel time, material falling speed leaving the chute, and falling trajectory vary, and ultimately the deposition position in the furnace changes, resulting in a deviation in the distribution of the charge in the direction of the furnace circumference in the charge layer. In particular, this leads to deviations in the 0/C distribution as seen in the profile of FIG. As can be seen from the above explanation, if ore is cut from one of the two furnace top bunkers 1.2 and coke is cut from the other, and this continues alternately, a large deviation will occur in the 0/C distribution in the circumferential direction of the 5 furnaces. Cause. JP-A-62-56 as a technique for adjusting circumferential balance
There is 507. This technology allows the material to fall vertically into the rotating chute by collecting and discharging the material in the collecting chute. Therefore, although this method improves the balance in the circumferential direction, the following new problems arise. The radial distribution of the particle size of the charge in the blast furnace is finer on the furnace wall side and coarser on the furnace center side, which reduces the heat load from the furnace wall and stabilizes the tapped iron slag by activating the furnace core. A point is fine. In the bellless charging system, when charging raw materials, the rotating chute does not rotate, but instead charges from the furnace wall toward the center of the furnace. Therefore, in order to make the radial distribution of the particle size of the charge in the blast furnace finer on the furnace wall side and coarser on the furnace center side, the change over time of the particle size of the raw material falling from the vertical chute to the rotating chute is shown in Figure 5 ( As in a), the particle size needs to be small at the beginning and then increase as time passes. Figure 5 (
This is close to a) and is ideal. However, JP-A-62-565
Once the raw material discharged from the bunker is collected on the collecting chute as shown in Figure 5(b), the particle size of the raw material changes over time as it falls from the collecting chute to the rotating shete, as shown in Figure 5(b). However, it quickly becomes coarse and then gradually becomes finer again, which is not necessarily ideal. Furthermore, Japanese Patent Laid-Open No. 62-66084 discloses that a throttle valve is provided at the point where the raw material falls from the collection chute, and by adjusting the position of the throttle opening, the material falls into the rotating chute in a vertical direction. ．． However, it is necessary to change the orifice position depending on the type of raw material and the bunker to be discharged.In particular, since the raw material properties change sequentially, it is difficult to manage and adjust them, and as a result, vertical drop cannot be ensured. [Problems to be solved by the invention J Problems to be solved by the present invention are as follows. ■ Make the direction of the raw material flow into the rotating chute vertical, and align the falling position of the raw material flow with the center of rotation of the rotating chute. ■ By making the distribution characteristics of the extruded particle size from the beginning of discharge to the end of discharge from the hopper to the rotating chute as shown in Fig. 5(a) instead of as shown in Fig. 5(b), it is possible to To make the radial distribution of the particle size of the charged raw material finer on the furnace wall side and coarser on the furnace center side. ■ It must be possible to always ensure vertical fall, regardless of the type of raw material, which bunker it is discharged from, or even if the raw material properties change over time. The object of the present invention is to provide a method and apparatus for charging a bellless blast furnace, which can simultaneously satisfy the above three points. [Means for Solving the Problems 1] The technical means of the present invention for solving the above-mentioned problems is that the raw material discharged from the furnace top bunker is opposed to the above rotating chute.
It is characterized by colliding and merging with each other from different directions and dropping them onto a rotating chute. When the two flow directions are projected onto a horizontal plane, the angle of intersection between the two opposing directions is between 90° and 27°.
The direction should be 0°. In addition, the above method can be easily implemented by dividing the raw material discharged from each furnace top bunker and then recombining it. Note that if three or more top bunkers are provided and the same type of charge is simultaneously discharged from two bunkers and collided and merged, the number of bunkers will increase, but this can be easily and ideally implemented. be. In addition, as a device for suitably carrying out the above method, the discharged raw material is divided into two parts directly below each bunker discharge port in a collection chute provided between the top bunker discharge port and the rotating chute. Appropriate is a bell-less blast furnace charging device that is specially designed to have a chevron-shaped protrusion that forms a guiding path for guiding the raw material in the opposing falling direction.

[Sakukawa J] In the conventional method, when the blast furnace charging material is discharged from the bunker and flows through the collecting hopper, the presence of a horizontal velocity component causes poor circumferential balance.

Figure 1 is an explanatory diagram of the method of the present invention, and Figure 1 (a) is a plan view.
Figure 1(b) is a longitudinal cross-sectional view. Below the bunker I, there is a collecting chute 3i3 and a vertical shoe}-3a, and below that there is a rotating chute (not shown). By dividing the raw material flow 5 discharged from the bunker 1 into two and remerging them from opposite directions, the horizontal velocity component can be eliminated, and the material falling from the vertical chute 3 to the rotating chute is reduced to almost only the vertical component. Become. Therefore, the raw material supplied to the rotating chute and then spread into the blast furnace has no distribution deviation in the circumferential direction within the blast furnace.

The numerical value θ of the horizontal plane projection angle formed by two opposing directions is 180
degree is ideal, but even if this angle θ increases or decreases a little,
In the range of 90 to 270 degrees, the horizontal velocity component of the raw material flow can be significantly reduced. Figure 4 shows this angle θ and the deviation of the layer thickness of the blast furnace raw material in the circumferential direction. FIG. 3 is a perspective view showing a set sheet that can suitably achieve the above method. 10 protrusions inside the collection chute
Establish. This protrusion 10 is located directly below the discharge port of the bunker 1 and has the shape of a rectifying plate, thereby dividing the raw material discharged from the bunker to the left and right. Furthermore, the separated raw material flows rejoin from opposing directions toward the center of the collecting chute 3, so that they cancel out the horizontal components of the flows.
Since it falls vertically approximately at the center of the vertical chute 3a, dl. Since d2 becomes equal, there is no distribution deviation in the circumferential direction within the furnace. In addition, in the above method, the raw material discharged from the bunker does not accumulate anywhere until it is charged into the furnace, so the particle size of the raw material changes over time as it passes through the rotating chute, as shown in Figure 5 (a). It has become. Therefore, when the charged raw material was deposited in the furnace, the radial distribution of the raw material particle size was ideal, finer on the furnace wall side and coarser on the furnace center side. [Example] The present invention was tested by the following method. Furnace volume: 2584 m' Air flow rate: 3500 Nrn'/min Piercing ratio: 1.44 t/m'・d In the above blast furnace and its operation, the top charging device has a mountain-shaped structure on the collecting chute as shown in Figure 3. Using a bunker equipped with protrusions, the raw material discharged from one bunker was divided by the chevron-shaped protrusions, then merged again at an angle of 90° and dropped onto a rotating chute. Figure 6 shows the operational progress at that time. In addition, tests were conducted in the following blast furnaces.

Furnace capacity 4500rn' Air flow rate 5940Nrr? /min Tapping ratio 1.48t/rr?・d In the above blast furnace and its operation, a third
Using a collection chute with chevron-shaped protrusions as shown in the figure, the raw materials discharged from one bunker are divided by the chevron-shaped protrusions, and then merged again at an angle of 180" and dropped onto the rotating chute. The operation progress at that time is shown in Fig. 7. Still another example is shown. During operation, three top bunkers were installed in the top charging device, and the same type of charge was simultaneously discharged from the two bunkers and merged on the collecting sheet.At this time, any combination of bunkers could be used. The convergence angle of the raw material flow on the collecting chute is 120
I set it to ゜. Figure 8 shows the operational trends at that time. In all blast furnaces, by implementing the present invention, the deviation in the circumferential direction of the skin flow thermometers installed at eight locations in the circumferential direction was reduced, as shown in Figs. 6 to 8. In addition, S in hot metal
It is possible to suppress the fluctuations in i and the fluctuations in the tapping temperature,
Previously, an excessive heat source was provided to meet the specifications even at the lower end of the variation, that is, the lowest tapping temperature, but this has been reduced and the fuel ratio has been reduced. [Effect of the invention 1] The present invention reduces the deviation of the charge in the circumferential direction and achieves an ideal radial distribution of the particle size of the charge in the furnace, that is, a fine distribution on the furnace wall side and a coarse distribution on the furnace center side. As a result, it was possible to suppress fluctuations in Si in the hot metal and tap temperature, and also to reduce the fuel ratio.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a longitudinal cross-sectional view of the vicinity of the top of a bellless blast furnace, and FIG. 3 is a schematic perspective view of an embodiment.
Figure 4 is a graph showing the influence of the angle of counterflow,
FIG. 5 is a graph showing the change in particle size of the charged material over time as it falls from the vertical chute 3 to the rotating chute 4, and FIGS. 6 to 8 are graphs showing the effects of the present invention.

Claims (1)

[Claims] 1. A furnace top charging method for a bellless blast furnace, characterized in that raw materials discharged from a furnace top bunker collide and merge with each other from two opposing directions above a rotating chute, and then fall onto the rotating chute. 2. The method according to claim 1, wherein the two opposing directions are directions such that when the two flow directions are projected onto a horizontal plane, their intersection angle is 90° to 270°. 3. The method according to claim 1 or 2, wherein the raw materials discharged from each furnace top bunker are divided and then recombined. 4. The method according to any one of claims 1 to 2, characterized in that three or more furnace top bunkers are provided, and the same type of charges are simultaneously discharged from two bunkers and collided and merged. 5 Two discharged raw materials are placed directly under each bunker outlet in the collection chute provided between the top bunker outlet and the rotating chute.
1. A top charging device for a bellless blast furnace, characterized in that a chevron-shaped protrusion is provided to form a guide path that divides the raw material and then guides the divided raw material in opposing falling directions.