JP7343052B2 - Blast furnace raw material charging method - Google Patents

Description

The present invention relates to a method for charging raw materials into a blast furnace.

In a blast furnace, ore materials such as sintered ore, pellets, or lump ores and coke are normally charged in layers from above, forming an ore layer and a coke layer, as shown in Figure 1. The operation involves flowing high-temperature reducing gas upwards to obtain pig iron. Note that ore raw materials and coke are hereinafter also collectively referred to as raw materials. In the figure, numeral 1 is a blast furnace, 2 is a tuyere, 3 is an ore layer, 4 is a coke layer, and 5 is a cohesive layer.

In the operation of such a blast furnace, the flow of gas within the blast furnace affects the reduction efficiency of ore raw materials and the amount of heat dissipated to the outside of the blast furnace. Generally, in order to improve the reduction efficiency of ore raw materials and reduce the amount of heat dissipated to the outside of the blast furnace, it is considered desirable to flow more gas near the center of the blast furnace.

This is mainly due to the following two reasons.
(1) When the gas flow rate near the blast furnace wall increases, the amount of heat dissipated to the outside of the blast furnace increases and energy efficiency decreases.
(2) In the lower part of the blast furnace, the ore raw material charged into the blast furnace is heated and reduced by the reducing gas, and a cohesive zone is formed. The cohesive zone is a region in which cohesive layers, which have a rock-like structure in which particles of ore raw materials are fused to each other, and coke slits, in which coke exists alone, alternately exist. As described above, the fused layer has a rock-like structure in which the particles of the ore raw material are fused to each other, so the porosity within the layer is extremely low. On the other hand, the porosity of the coke slit is higher than that of the cohesive layer. Therefore, in the cohesive zone, gas flowing from vertically downward selectively flows through the coke slits. Here, when the amount of gas flowing near the center of the blast furnace increases, the height region of the cohesive zone expands. As a result, the number of coke slits in the cohesive zone increases, improving gas permeability.

In order to increase the gas flow rate near the center of the blast furnace, it is effective to arrange large grain raw materials near the center and arrange small grain raw materials near the furnace wall in the radial direction of the blast furnace.
This is because when comparing a packed bed of large-sized particles and a packed bed of small-sized particles, the former has a smaller total specific surface area of the packed particles. This is because the friction between the flowing gas and particles is reduced and the gas flow rate is increased.

Therefore, various techniques have been proposed to increase the gas flow rate near the center of the blast furnace by controlling the particle size distribution, layer thickness, etc. of the ore layer and coke layer formed in the blast furnace.

For example, in Patent Document 1,
``A method for charging materials into a blast furnace using a bellless type charging device equipped with a rotating chute and having bunkers arranged in parallel at the top of the furnace,
When charging the raw material into the blast furnace through the top bunker, which temporarily stores the raw material and discharges it to a rotating chute provided below,
In the case where a movable plate that can be freely tilted is provided in the top bunker, the raw material charged into the top bunker is made to collide with the movable plate, and the tip of the rotating chute is tilted from the periphery of the blast furnace toward the center. The operator operates the movable plate so that the falling direction of the raw material is in the direction of the discharge port of the furnace top bunker, and the falling position of the raw material charged into the furnace top bunker is set directly at the discharge port of the raw material. In the upper part of the furnace top bunker, due to the deposition characteristics of the raw materials, fine particles are collected near the outlet, and coarse particles are collected at a distance from there.
When tilting the tip of the swing chute from the center of the blast furnace toward the periphery, operate the movable plate so that the falling direction of the raw material is opposite to the discharge hole of the furnace top bunker. The falling position of the raw material charged into the bunker is made to be a side wall away from the discharge port, so that coarse grain raw materials collect near the discharge port and fine grains collect far from the discharge port,
A method for charging raw materials into a blast furnace using a top bunker and a bellless charging device, which is characterized by depositing coarse particles in the center of the blast furnace. ”
is proposed.

Patent No. 4591520

By the way, in a bell-less type blast furnace as shown in FIG. 2, a furnace top bunker for temporarily storing raw materials to be charged into the blast furnace is arranged at the furnace top portion of the blast furnace. Then, the flow rate adjustment gate is opened and the raw material discharged from the furnace top bunker is charged into the blast furnace via the collection hopper and the rotating chute. At this time, the radial tip position of the rotating chute may be changed (hereinafter also referred to as tilting) to adjust the falling position of the raw material in the radial direction of the blast furnace.
In the figure, numeral 6 is a furnace top bunker, 7 is a flow rate adjustment gate, 8 is a collecting hopper, and 9 is a rotating chute.

That is, when charging the raw material into the blast furnace, the rotating chute rotates at a constant speed in the circumferential direction of the blast furnace and tilts at regular intervals with the axis of the blast furnace as the rotation axis. Tilting methods are broadly divided into two types: forward tilting, which is when the blast furnace is tilted from near the wall of the blast furnace to the center of the blast furnace, and reverse tilting, where the tilting is from the center of the blast furnace to near the wall of the blast furnace. It is called charging.

Among these, reverse tilting charging has the effect of suppressing the raw material from flowing into the center of the blast furnace after the raw material is charged and deposited in the blast furnace. Therefore, compared with forward tilting charging, reverse tilting charging makes it easier to stabilize the shape of the raw material pile, which is advantageous in controlling the raw material particle size distribution in the blast furnace.

As mentioned above, from the perspective of increasing the gas flow rate near the center of the blast furnace, it is possible to place large-grained raw materials near the center in the radial direction of the blast furnace, and place small-grained raw materials near the wall of the blast furnace. It is effective to place In this specification, coke, ore (including agglomerated ore), and auxiliary raw materials such as limestone, which are charged from the top of the blast furnace, are collectively referred to as raw materials. For all of these raw materials, it is most preferable to place large particles in the center of the blast furnace, but among them, it is most preferable to place large particles in the center of the blast furnace. It is also effective to arrange particles of particle size. The furnace top bunker usually stores raw materials for one batch. Therefore, when reverse tilting charging is performed, it is preferable to set the raw material particle size distribution in the furnace top bunker such that a large number of large particle diameter raw materials are discharged at the initial stage of raw material discharge from the furnace top bunker.

In this regard, the technology of Patent Document 1 uses a tiltable movable plate (hereinafter also referred to as a segregation control plate) provided in the furnace top bunker to intentionally segregate the raw materials stored in the furnace top bunker. . This is intended to achieve a preferable raw material particle size distribution in the furnace top bunker depending on the tilting method.

However, the technique disclosed in Patent Document 1 cannot sufficiently realize a raw material particle size distribution in the furnace top bunker that is suitable for reverse tilting charging. In other words, when a certain number of large particle size raw materials are mixed in the raw material discharged from the top bunker during the middle to final stage of raw material discharge, and as a result, a certain number of large particle size raw materials are mixed near the furnace wall of the blast furnace. was there.

The present invention was developed in view of the above-mentioned current situation, and realizes a raw material particle size distribution in the furnace top bunker that is suitable for both forward tilting charging and reverse tilting charging, thereby making it possible to First, it is an object of the present invention to provide a method for charging raw materials into a blast furnace that can further improve air permeability and reduction efficiency by increasing the gas flow rate near the center of the blast furnace.

Now, the inventors have made extensive studies to achieve the above object.
First, the inventors investigated the reason why, in the technique of Patent Document 1, a sufficient raw material particle size distribution in the furnace top bunker suitable for reverse tilting charging may not be achieved in some cases.
Generally, from the viewpoint of compacting the collection hopper that receives the raw materials discharged from the furnace top bunker and from the viewpoint of strengthening particle size segregation within the bunker, the raw material discharge port of the furnace top bunker is placed in a horizontal plane as shown in Fig. 3. (in a vertical projection plane), it is arranged eccentrically from the center of the raw material storage section to the axial center side of the blast furnace. Note that FIG. 3 is a schematic diagram showing the arrangement of each part of the furnace top bunker when viewed from above in the vertical direction. In the figure, 6-1 is a raw material storage section, and 6-2 is a raw material discharge port.
Here, the eccentric direction is a direction from the center of the raw material storage section to the center of the raw material discharge port in a horizontal plane, and when viewed from above in the vertical direction, the direction rotated 90 degrees clockwise from the eccentric direction is the first direction. The direction rotated by 180 degrees is called the eccentric opposite direction, and the direction rotated by 270 degrees is called the second direction. Note that the raw material discharge port of the furnace top bunker is arranged eccentrically from the center of the raw material storage section toward the axis of the blast furnace in a horizontal plane (a plane projected in the vertical direction). Therefore, when the furnace top bunker is disposed at the top of the blast furnace, the eccentric direction is usually the same direction as the direction from the center of the raw material storage section to the axis of the blast furnace (hereinafter also referred to as the blast furnace axis direction).

When reverse tilting charging is performed using the technique of Patent Document 1, as shown in FIG. Hereinafter, the segregation control plate is operated so as to be near the eccentric opposite side wall. Therefore, the shape of the raw material accumulation layer in the furnace top bunker is such that the raw material deposition surface is vertical in the eccentric direction (from the opposite side wall to the eccentric side wall (hereinafter also referred to as eccentric side wall)). The direction is inclined downward. In the figure, 6-3 is a segregation control plate.

In this case, the raw material particle size distribution in the furnace top bunker and the raw material discharge order (draining time for each raw material storage position in the furnace top bunker) when discharging raw materials from the furnace top bunker were determined using a numerical simulation called the discrete element method. As a result of calculation, as shown in FIG. 5, more than half of the large-particle raw materials gather near the raw material discharge port, that is, in the area where the raw materials are discharged at the beginning of raw material discharge. However, most of the remaining large-grain raw materials are located in the first and second wall portions (hereinafter referred to as the first wall portion and the second wall portion) that are perpendicular to the eccentric direction of the top bunker. It was found that the raw material is located in the vicinity of the raw material discharge area, that is, in the area where the raw material is discharged from the middle to the final stage. In other words, it was found that due to this, when reverse tilting charging is performed, a certain number of large-grained raw materials are mixed near the furnace wall of the blast furnace.

Based on this point, the inventors further investigated and found that
・The falling position of the raw material charged into the furnace top bunker is distributed not only near the wall on the opposite side of the eccentricity but also near the first wall and the second wall,
・As a result, as shown in Figure 6, the shape of the raw material accumulation layer in the furnace top bunker can be changed so that the raw material is discharged not only from the wall on the opposite side of the eccentricity, but also from the first wall and the second wall. In other words, the shape of the raw material accumulation layer is made to be approximately conical.
We found that this is effective.
It was also discovered that this allows large-particle raw materials to be gathered more densely near the raw material discharge port.

The inventors consider the above reason as follows.
That is, large-particle raw materials tend to roll more easily on the deposition surface than small-particle raw materials. Therefore, by distributing the falling position of the raw material charged into the furnace top bunker not only near the wall on the opposite side of the eccentricity but also near the first wall and the second wall, the first wall and A raw material accumulation layer is formed that slopes vertically downward from the second wall toward the raw material discharge hole. Then, while the large-particle raw materials that are gradually charged roll on this stacking surface, the small-particle raw materials are deposited at the falling position, so that the large-particle raw materials can be more densely collected near the raw material discharge port.

Based on the above knowledge, the inventors determined that the falling position of the raw material charged into the furnace top bunker was not only near the wall on the opposite side of the eccentricity, but also near the first wall and the second wall. When considering ways to disperse the
・A structure with a raw material collision surface is placed inside the raw material storage part of the furnace top bunker,
・The shape of the raw material collision surface is changed downward from the top of the structure toward the end of the raw material collision surface in the opposite eccentric direction, and in the first and second directions perpendicular to the opposite eccentric direction and the vertical direction, respectively. tilt to,
We found that this is effective.

In addition, the inventors further investigated, and as shown in FIG.
- In addition to changing the shape of the raw material collision surface in the opposite direction of eccentricity, and in the first and second directions perpendicular to the opposite direction of eccentricity and the vertical direction, the raw material collision surface is also applied in the eccentric direction from the top of the structure. Inclined downward toward the edge of the surface, and
・By determining the raw material collision position in the structure (located inside the raw material storage section of the furnace top bunker) according to the tilting method when charging raw materials into the blast furnace, forward tilting charging and reverse tilting system It has been found that it is possible to realize a raw material particle size distribution in the furnace top bunker that is suitable for each case in which the furnace top bunker is used. In the figure, 6-4 is a structure, and 6-5 is a raw material collision surface.
The present invention was completed based on the above findings and further studies.

That is, the gist of the present invention is as follows.
1. A method for charging raw materials into a blast furnace, the method comprising:
The blast furnace has a furnace top bunker at the furnace top,
At least one of the furnace top bunkers is
a raw material storage section;
a raw material charging port for charging the raw material into the raw material reservoir from above the raw material reservoir;
a structure that is disposed inside the raw material storage section and has a raw material collision surface on which raw materials charged from the raw material charging port collide;
a raw material discharge port that discharges the raw material in the raw material storage section below the raw material storage section;
Equipped with
The raw material outlet is arranged eccentrically from the center of the raw material storage part in a horizontal plane,
Further, the raw material collision surface of the structure is arranged from the top of the structure at least in an eccentric direction, an opposite eccentric direction, and a first direction and a second direction perpendicular to the eccentric direction and a vertical direction, respectively. sloped downward toward the end of the raw material collision surface;
Furthermore, the method for charging raw materials into the blast furnace includes:
a storage step of charging the raw material into the raw material storage part from the raw material charging port of the furnace top bunker, causing the raw material to collide with the structure, and then storing the raw material in the raw material storage part; ,
A charging step of discharging the raw material stored in the raw material storage section from the raw material discharge port and charging the discharged raw material into the blast furnace via the rotating chute of the blast furnace,
A method for charging materials into a blast furnace, wherein a material collision position in the structure in the storage step is determined according to a tilting method in the charging step.
Here, the eccentric direction is a direction in which the raw material outlet is eccentric from the center of the raw material storage section in the horizontal plane. Moreover, the eccentricity opposite direction is a direction opposite to the eccentricity direction in the same horizontal plane.

2. 1, wherein the inclination angles α and α′ from the horizontal direction of the line connecting the top of the structure and the end of the raw material collision surface in the eccentric direction and the opposite direction to the eccentricity are 25 to 45 degrees, respectively; The method for charging raw materials into a blast furnace described in .

3. Inclination angles β and γ from the horizontal direction of the line segment connecting the top of the structure and the end of the raw material collision surface in the first direction and the second direction are 25 to 45 degrees, respectively; The method for charging raw materials into a blast furnace according to 1 or 2 above.

4. The raw material for a blast furnace according to any one of 1 to 3 above, wherein the top of the structure is located in a dimensionless distance (r/R) from the center of the raw material storage part in a range of 0 to 0.6 on a horizontal plane. How to charge.
Here, the dimensionless distance (r/R) is a value obtained by dividing the distance (r) from the center of the raw material reservoir in the horizontal plane by the inner radius (R) of the raw material reservoir.

According to the present invention, it is possible to realize a raw material particle size distribution in the furnace top bunker that is suitable for both forward tilting charging and reverse tilting charging.
As a result, during operation of the blast furnace, it is possible to increase the gas flow rate near the center of the blast furnace without using the tilting method, thereby further improving air permeability and reduction efficiency.
In addition, the present invention is excellent in terms of operability and maintainability because it does not require strict control or a complicated structure for that purpose.

It is a schematic diagram showing the gas flow in a blast furnace. It is a schematic diagram showing the procedure for charging raw materials into a blast furnace. FIG. 2 is a schematic diagram showing the arrangement of various parts of the furnace top bunker when viewed from above in the vertical direction. FIG. 2 is a schematic diagram showing the state of accumulation of raw materials in the furnace top bunker when charging the raw materials into the furnace top bunker (assuming reverse tilting charging) in which a segregation control plate is installed. (a) is a schematic diagram when viewed from the eccentric direction, and (b) is a perspective view. Particle size distribution of raw materials in the top bunker when charging raw materials (assuming reverse tilting charging) into the top bunker with a segregation control plate installed, and raw materials when discharging raw materials from the top bunker These are the results of a numerical simulation of the discharge order (discharge time for each raw material storage position in the furnace top bunker). It is a schematic diagram which shows the raw material accumulation situation in a furnace top bunker when performing reverse tilting charging. (a) is a schematic diagram when viewed from the eccentric direction, and (b) is a perspective view. It is a schematic diagram which shows the raw material accumulation situation in a furnace top bunker when performing forward tilting charging. (a) is a schematic diagram when viewed from the eccentric direction, and (b) is a perspective view. It is a schematic diagram showing an example of the point of storing raw material in a furnace top bunker by the raw material charging method of the blast furnace according to one embodiment of the present invention. It is a schematic diagram which shows an example of the shape (outer peripheral shape) from the top of a structure to the edge of a raw material collision surface. FIG. 2 is a schematic diagram showing an example of a structure installed inside a furnace top bunker. FIG. 3 is a schematic diagram showing a preferred area where the top of the structure is located. Regarding conditions 1 and 2, the particle size distribution of the raw material in the top bunker when charging the raw material into the top bunker assuming reverse tilting charging, and the time of discharging the raw material from the top bunker. These are the results of a numerical simulation of the raw material discharge order (discharge time for each raw material storage position in the furnace top bunker). FIG. 2 is a schematic diagram of the apparatus used in the model experiment. FIG. 2 is a schematic diagram showing the particle size distribution of raw materials (forward tilting charging) obtained by a model experiment. FIG. 2 is a schematic diagram showing the particle size distribution of raw materials (reverse tilting charging) obtained through a model experiment. It is a schematic diagram which shows the point of adjusting the raw material collision position in a structure.

The present invention will be explained based on the following embodiments.

A method for charging raw materials into a blast furnace according to an embodiment of the present invention is carried out in a blast furnace in which one or more furnace top bunkers are arranged at the top of the furnace,
a storage step of charging the raw material from the raw material charging port of the furnace top bunker, causing the raw material to collide with a structure of a predetermined shape, and then storing the raw material in the raw material storage section of the furnace top bunker;
The method includes a charging step of discharging the raw material stored in the raw material storage section of the furnace top bunker and charging the discharged raw material into the blast furnace through the rotating chute of the blast furnace.
Here, as shown in FIG. 2, the furnace top bunker is disposed at the top of the blast furnace to temporarily store raw materials to be charged into the blast furnace. The number of top bunkers installed at the top of the blast furnace is not particularly limited, and may be set as appropriate depending on the number of raw materials and the required volume of the top bunker, but it is usually 2 to 4. be.
Hereinafter, a furnace top bunker used in a method for charging raw materials for a blast furnace according to an embodiment of the present invention, and a storage process and a charging process for the method for charging raw materials for a blast furnace according to an embodiment of the present invention will be described.

[Top Bunker]
In the blast furnace raw material charging method according to an embodiment of the present invention, at least one of the furnace top bunkers is provided with a material as shown in FIG.
a raw material storage section;
a raw material charging port (not shown) for charging the raw material into the raw material reservoir from above the raw material reservoir;
a structure disposed inside the raw material storage section and having a raw material collision surface with which raw materials charged from the raw material charging port collide;
a raw material discharge port that discharges the raw material in the raw material storage section below the raw material storage section;
Use a furnace top bunker with a Preferably, the above-mentioned furnace top bunker is used for all the furnace top bunkers arranged at the furnace top of the blast furnace.
Note that the terms upper, lower, upper, and lower mean vertically upper, lower, upper, and lower, unless otherwise specified.

Here, the raw material charging port is arranged at the upper part of the raw material storage section. Although the position of the raw material charging port in the horizontal plane is not particularly limited, it is generally located on the axis side of the blast furnace (in the same direction as the raw material discharge port) from the center position of the raw material storage section.

Then, the raw material charged from the raw material charging port collides with the raw material collision surface of the structure placed inside the raw material storage section, falls into the raw material storage section, and is temporarily stored in the raw material storage section. Ru. Note that the raw material temporarily stored in the raw material storage section is usually for one batch. Further, the raw material storage section has a body section having a cylindrical shape, a truncated conical tube shape, or a combination thereof, and a diameter-reducing section whose diameter decreases toward the bottom.
Note that the maximum diameter (outer diameter) of the furnace top bunker is usually about 4,000 to 5,000 mm, and the height of the furnace top bunker is about 9,000 to 13,000 mm.

Then, in accordance with the operation of the blast furnace, the flow rate adjustment gate is opened, and the raw material is gradually discharged by its own weight from the raw material discharge port at the lower end of the reduced diameter part of the raw material storage section, and is then passed through the collection hopper and the rotating chute. , raw materials are charged into the blast furnace.

As shown in FIG. 3, the raw material discharge port is eccentric from the center of the raw material storage part in the horizontal plane, and normally, the distance between the centers of the raw material storage part and the raw material discharge port in the horizontal direction (eccentricity amount): A is the raw material The inner radius of the reservoir: 0.60 to 0.70 times R. Further, the inner radius B of the raw material discharge port is usually 0.10 to 0.30 times the inner radius R of the raw material storage section. Note that the center position and inner diameter of the raw material storage section are based on the installation height position of the top of the structure, which will be described later. Moreover, the center position and inner diameter of the raw material discharge port are based on the height position where it connects to the lower end of the raw material storage part. The same applies from here on.
In addition, in FIG. 3, an example was explained in which the horizontal cross section of the raw material storage part was circular, but in the case of a shape other than this, the center of the raw material storage part is the center of gravity of the horizontal cross section that has the largest area. In this case, the eccentric direction is a direction from the center of the raw material storage section that connects the center of the raw material discharge port and the center of the raw material storage section in the horizontal section (horizontal cross section with the largest area) toward the center of the raw material discharge port. , R is 1/2 of the length of the raw material storage section in the eccentric direction of the horizontal section.

In the method for charging materials into a blast furnace according to an embodiment of the present invention, the shape of the material collision surface of the structure is extremely important.
Specifically, as shown in FIG. 8, the shape of the raw material collision surface is changed at least in the eccentric direction, the opposite eccentric direction, the first direction and the second direction perpendicular to the eccentric direction and the vertical direction, respectively. It is important to incline downward from the top of the body (raw material collision surface) toward the end of the material collision surface.

That is, as described above, when reverse tilting charging is performed, as shown in FIG. and also dispersed near the second wall. As a result, the shape of the raw material accumulation layer in the furnace top bunker is tilted vertically downward toward the raw material discharge hole not only from the eccentric opposite side wall but also from the first wall and the second wall. In other words, it is important that the raw material deposition layer has a substantially conical shape. This allows large-particle raw materials to be gathered more densely near the raw material discharge port. Therefore, the shape of the raw material collision surface of the above structure (the outer peripheral shape of the vertical cross section) is changed from the top of the structure to the end of the raw material collision surface not only in the opposite direction of eccentricity but also in the first direction and the second direction. It is important to tilt downward toward the

In addition, when performing forward tilting charging, as shown in Fig. 7, the falling position of the raw material charged into the furnace top bunker is not only near the eccentric side wall (that is, near the raw material discharge port) but also at the first It is also dispersed near the wall and the second wall. As a result, the shape of the raw material accumulation layer in the furnace top bunker is tilted vertically downward not only from the eccentric side wall but also from the first wall and the second wall toward the opposite side wall. This is very important. As a result, large-particle raw materials are collected at a location away from the raw material discharge port. That is, large particle size raw material is discharged at the end of discharge from the furnace top bunker. Therefore, it is important that the shape of the raw material collision surface of the structure (the outer peripheral shape of the vertical cross section) is inclined downward from the top of the structure toward the end of the raw material collision surface also in the eccentric direction.

Here, in the eccentric direction and the direction opposite to the eccentricity, being inclined downward from the top of the structure toward the end of the raw material collision surface means that the structure is vertical at a position passing through the top of the structure, as shown in FIG. This means that when the cross section is viewed from the first direction, it is inclined downward from the top of the structure toward the end of the raw material collision surface. Similarly, sloping downward from the top of the structure toward the end of the raw material impingement surface in the first direction and the second direction means that the structure is at a position passing through the top of the structure, as shown in FIG. This means that when a vertical cross section is viewed from the eccentric direction, it is inclined downward from the top of the structure toward the ends of the raw material collision surfaces in the first direction and the second direction. Alternatively, it means that in the cross section along the first direction and the second direction of the structure, the raw material collision surface is inclined downward from the highest position toward the end.

Note that the raw material collision surface is the upper surface of the structure (the area of the structure when viewed from above). Therefore, the top of the structure is the highest position in the vertical direction of the material collision surface. Here, if there are a plurality of highest positions on the raw material collision surface, the point located at the farthest distance from the raw material discharge port in the eccentric direction among the highest positions is defined as the top. Also, members for fixing the structure shall be removed from the material collision surface. Note that the raw material collision surface may be composed of one continuous surface or may be composed of a plurality of surfaces.

Further, the inclination angles α and α' from the horizontal direction of the line segment connecting the top of the structure and the end of the raw material collision surface in the eccentric direction and the opposite direction to eccentricity are preferably 25 to 45 degrees, respectively. α and α′ are each more preferably 40 to 43°.

Further, it is preferable that the inclination angles β and γ from the horizontal direction of the line segment connecting the top of the structure and the end of the material collision surface in the first direction and the second direction are respectively 25 to 45 degrees. . β and γ are each more preferably 40 to 43°.

Similarly, from the top of the structure in the direction from the first direction, through the direction opposite to the eccentricity, to the second direction (direction between 90° and 270° clockwise from the eccentricity direction) to the raw material collision surface. It is also preferable that the shape from the top of the structure to the end of the structure be sloped downward from the top of the structure toward the end of the raw material collision surface. Suitable inclination angles from the horizontal direction of the straight line connecting the top of the structure and the end of the material collision surface in these directions are also the same as the above-mentioned inclination angles α, α', β, and γ.

Note that the shape (outer circumferential shape) from the top of the structure to the end of the raw material collision surface in each vertical cross section of the structure does not need to have a constant inclination regardless of the direction, but can be shaped so that the inclination changes variously. For example, as shown in FIG. 9, the shape may be an arc or a shape in which the slope changes stepwise.

In addition, a direction from the first direction, passing through the eccentric direction to the second direction (a direction between 0 to 90 degrees clockwise from the eccentric direction, and a direction between 270 degrees and 360 degrees, provided that the first direction The shape from the top of the structure to the end of the raw material collision surface in the direction (excluding the direction and the second direction) is not particularly limited.
For example, it may be inclined downward from the top of the structure toward the end of the raw material collision surface, similar to the opposite eccentric direction, the first direction, and the second direction. In this case, the shape of the structure may be, for example, a conical shape, an oblique conical shape, an elliptical conical shape, a shape in which a cone is attached to the top of a truncated cone (shape 1), or a halved cone shape, as shown in Fig. 10. Shapes in which two halves of an elliptical cone are pasted together with their cut surfaces (shape 2), dome shapes in which the collision surface of raw materials is spherical, polyhedral shapes such as square pyramids, hexagonal pyramids, and octagonal pyramids; these shapes can be made into any shape. It is a shape cut vertically at a certain position. Note that the interior of the structure may be hollow, and no member may be disposed on surfaces other than the raw material collision surface, such as the bottom surface and side surfaces. Furthermore, the above-mentioned shapes include those in which the shape is changed by providing a member on the bottom surface, etc., as long as the region of the raw material collision surface does not change.

In addition, the length a of the above structure (the distance between the ends of the raw material collision surfaces in the horizontal direction when the structure is viewed from the first direction) is equal to 0.000 mm of the inner radius: R of the raw material storage section. It is preferable to set it to 4 to 0.8 times (see FIG. 8; the same applies to the width and height of the structure described later). The width b of the above structure (the distance between the ends of the raw material collision surfaces in the horizontal direction when the structure is viewed from the eccentric direction) is 0.4 to 0.8 times the inner radius of the raw material storage part: R It is preferable that The height h (distance from the bottom end to the top of the raw material collision surface) of the above structure is preferably 0.47 to 1.0 times the length a of the structure.

Note that the shape of the structure may be symmetrical or asymmetrical in the first direction and the second direction.

Furthermore, regarding the installation position of the above structure in the horizontal direction, as shown in FIG. Preferably located within the range.
Here, the dimensionless distance (r/R) is the distance (r) from the center of the raw material storage section divided by the inner radius (R) of the raw material storage section on the horizontal plane (projection plane in the vertical direction). It is a value.

In addition, the installation position of the above structure in the vertical direction is not particularly limited, but the dimensionless height (h'/H) at the top of the structure is in the range of 0.75 to 0.85. It is preferable to keep it within.
Here, the dimensionless height (h'/H) is the distance (height) from the lower end of the furnace top bunker (the height position of the raw material discharge port) to the top of the structure in the vertical direction: h'. , the height of the furnace top bunker: the value divided by H.

Moreover, it is preferable that the above-mentioned structure is arranged so as to be symmetrical with respect to a vertical line passing through the center of the raw material storage section when viewed from the eccentric direction. However, as long as it is inclined downward from the top of the structure toward the ends in the first direction and the second direction, it does not have to be symmetrical.

In addition, the material of the above-mentioned structure is not particularly limited, and general steel or the like may be used. Furthermore, the method of installing the structure is not particularly limited. For example, a beam member may be fixed to the inner wall of the furnace top bunker with metal fittings or welding, and the above-mentioned structure may be fixed to this beam member with metal fittings or welding. Bye. Furthermore, the above structure may have a position adjustment mechanism for changing its position and an installation angle adjustment mechanism for changing its installation angle.

[Storage process]
In the storage step of the raw material charging method for a blast furnace according to an embodiment of the present invention, the raw material is charged into the raw material storage part from the raw material charging port of the furnace top bunker, the raw material is collided with the structure, and then the raw material is This is the process of storing the raw material in the raw material storage section.
In this step, it is important to determine (set) the raw material collision position in the structure according to the tilting method employed in the charging step, which will be described later.

As mentioned above, the preferable raw material particle size distribution in the top bunker differs depending on the tilting method. For example, in the case of reverse tilting charging, as shown in Fig. 6, the shape of the raw material accumulation layer in the top bunker can be changed not only from the eccentric opposite side wall but also from the first wall and the second wall. It is important to tilt downward in the vertical direction toward the raw material discharge port, in other words, to make the shape of the raw material accumulation layer substantially conical (to collect large-particle raw materials near the raw material discharge port). Therefore, in the case of reverse tilting charging, the material collision position in the structure is set to the side opposite to the eccentricity from the top of the structure.

On the other hand, in the case of forward tilting charging, as shown in FIG. It is important to incline vertically downward toward the side wall opposite the eccentricity. Therefore, in the case of forward tilting charging, the material collision position in the structure is set to the eccentric direction side with respect to the top of the structure.

Here, it is determined whether the raw material collision position in the structure is on the opposite eccentric direction side or the eccentric direction side, based on a representative position in the opposite eccentric direction of the raw material collision range in the structure body.
In other words, the collision position (range) of each particle of the raw material on the structure (raw material collision surface) when viewed from above in the vertical direction, with the top of the structure as the origin, the horizontal axis (X axis) is the structure in the opposite direction of eccentricity. Distance from the top of the body, distance from the top of the structure in the first direction with the vertical axis (Y axis) (distance in the opposite direction of eccentricity and in the first direction, positive value, eccentric direction and second direction) Plot the distance to (as a negative value). Then, the center of gravity position in the direction opposite to the eccentricity, that is, the average value in the direction opposite to the eccentricity (X coordinate) in the plot of the collision position of each particle is calculated as the representative position in the direction opposite to the eccentricity of the raw material collision range in the structure (hereinafter simply referred to as eccentricity (also referred to as the representative position in the opposite direction). Similarly, the center of gravity position in the first direction, that is, the average value in the first direction (Y coordinate) in the plot of the collision position of each particle is calculated as the representative position in the first direction of the raw material collision range in the structure ( (hereinafter also simply referred to as a representative position in the first direction).
For example, if the representative collision position in the opposite direction of eccentricity is a positive value (over 0), the raw material collision position in the structure is on the opposite side of eccentricity from the top of the structure, and the representative collision position in the opposite direction of eccentricity is If is a negative value (less than 0), the raw material collision position in the structure is on the eccentric direction side with respect to the top of the structure.

In the case of reverse tilting loading, it is preferable that the representative collision position in the opposite direction of eccentricity be in the range of a ₁ /4 to a ₁ /2. Here, _a1 is the distance between the top of the structure and the end of the raw material collision surface in the opposite direction of eccentricity (the distance between the top of the structure and the raw material collision surface in the opposite direction of eccentricity when the structure is viewed from the first direction) (see FIG. 8).
Further, in the case of forward tilting loading, it is preferable that the representative collision position in the opposite direction of eccentricity is in the range of -a ₂ /2 to -a ₂ /4. Here, _a2 is the distance between the top of the structure and the end of the raw material collision surface in the eccentric direction (the distance between the top of the structure and the end of the raw material collision surface in the eccentric direction when the structure is viewed from the first direction) (see FIG. 8).

Note that the collision range of the raw materials in the structure in the first direction is not particularly limited, but the representative position of the raw material collision range in the first direction in the structure (hereinafter referred to as "collision in the first direction") (also referred to as a representative position) is preferably in the range of -b/10 to b/10. Particularly preferably, the collision representative position in the first direction is 0.

Also, of the grains (number) of raw materials falling from the raw material charging port, 80% or more, preferably 90% or more of them collide with the structure (raw material collision surface) (i.e., the ratio of raw material collision with the structure) = [Number of raw materials colliding with the structure (raw material collision surface)] / [Number of raw materials charged into the furnace top bunker] x 100) so that it is 80% or more, preferably 90% or more), structure Adjust the material impact position in the body. The raw material impingement rate on the structure may be 100%.

The raw material collision position and raw material collision angle in the structure can be determined by, for example, providing a movable control plate 17 in the raw material flow path from the receiving hopper to the raw material charging port of the furnace top bunker, as shown in FIG. It can be adjusted by changing its position and angle. Note that FIG. 16 shows an example in which the raw material collision surface of the movable control plate 17 is fixed at right angles to the horizontal plane, and the movable control plate 17 is moved in the eccentric direction opposite to the eccentric direction of the furnace top bunker 6. However, it is not limited to this. For example, by making it possible to change the angle of the raw material collision surface of the movable control plate 17 and changing the position and angle, the raw material collision position and collision angle in the structure can be adjusted in more detail. can.

[Charging process]
In the above storage process, the raw material stored in the raw material storage section of the furnace top bunker is discharged from the raw material discharge port, and the discharged raw material is transferred to the blast furnace by reverse tilting charging or forward tilting charging through the rotating chute of the blast furnace. Insert it inside.
That is, when performing reverse tilting charging, the raw material is discharged from the furnace top bunker which has a raw material particle size distribution suitable for reverse tilting charging, and the discharged raw material is charged into the blast furnace.
On the other hand, when performing forward tilting charging, the raw material is discharged from the furnace top bunker with a raw material particle size distribution suitable for forward tilting charging, and the discharged raw material is charged into the blast furnace.
As a result, in both forward tilting charging and reverse tilting charging, the gas flow rate near the center of the blast furnace increases, improving air permeability and reduction efficiency.

Conditions other than those mentioned above are not particularly limited, and conventional methods may be followed.

The furnace top bunker is modeled according to the following conditions 1 and 2, and the raw material particle size distribution in the furnace top bunker when raw materials are charged inside each furnace top bunker, and when raw material is discharged from the furnace top bunker. The raw material discharge order (discharge time for each raw material storage position in the furnace top bunker) was calculated using the discrete element method.

・Condition 1 (invention example)
[Shape of the structure installed inside the furnace top bunker]
Inclination angle: α=42°, α′=42°, β=42°, γ=42°
Width: a = R x 0.5, length: b = R x 0.5, height: h = a x 0.5
[Installation position of the structure inside the furnace top bunker]
Position of the top of the structure: position r/R = 0.53 eccentrically from the center position of the raw material storage section Installation height of the top of the structure: h'/H = 0.82
[Location of raw material collision in the structure inside the furnace top bunker]
・For forward tilting loading: Eccentric direction side (Representative collision position in the opposite direction of eccentricity: -a ₂ /4, Representative collision position in the first direction: 0,
Raw material collision rate: 100%)
・In the case of reverse tilting loading, the opposite direction of eccentricity (representative collision position in the opposite direction of eccentricity: a _1/2 , representative collision position in the first direction: 0,
Raw material collision rate: 100%)

・Condition 2 (comparative example)
[Shape of the structure installed inside the furnace top bunker]
Plate-shaped (segregation control plate referred to in Patent Document 1)
Tilt angle:
・For forward tilting loading α=80°, β=0°, γ=0°
・In the case of reverse tilting charging α = 155° (α' = 25°), β = 0°, γ = 0°
Width: R x 0.31, Length: R x 1.0, Thickness: 160mm
[Installation position of the structure inside the furnace top bunker]
Center position of segregation control plate: position r/R = 0.37 eccentrically from the center position of the raw material storage section Installation height of center position of segregation control plate: h'/H = 0.42
[Location of raw material collision in the structure inside the furnace top bunker]
Approximate center position of segregation control plate, material collision rate: 100%
(Same as forward tilting charging and reverse tilting charging)

Furthermore, both the structures under Conditions 1 and 2 were arranged so as to be symmetrical with respect to a vertical line passing through the center of the raw material storage section when viewed from the eccentric direction.
Furthermore, the shapes of the raw material storage part, raw material charging port, and raw material discharge port of the furnace top bunker are the same for conditions 1 and 2 (R = 2350 mm, H = 12000 mm, raw material storage part and raw material discharge port) in accordance with the actual machine. Modeling was performed using center-to-center distance (eccentricity): A = R x 0.64, inner radius of raw material discharge port: B = R x 0.35).

Further, the raw material charging conditions were also the same for conditions 1 and 2. Specifically, the raw material here refers to ore, and the amount of raw material charged is equivalent to one batch. In addition, based on the particle size distribution of actual raw materials, the particle size was represented by three types: large particles, medium particles, and small particles, and the particle size ratio of large particles, medium particles, and small particles was set to 3.8 according to the actual raw material. :2.0:1.0. Furthermore, it was assumed that large particles, medium particles, and small particles each have the same mass. At this time, the same bunker was used for coke under conditions 1 and 2, and the charging conditions were also the same.
FIG. 12 shows representative evaluation results when reverse tilting charging was performed.

As shown in FIG. 12, under condition 1 (invention example), it was possible to realize a raw material particle size distribution in the furnace top bunker suitable for reverse tilting charging. That is, in the case of reverse tilting charging, large particles can be collected near the raw material discharge port and many large particles can be discharged at the initial stage of discharge from the furnace top bunker. Additionally, we were able to achieve a raw material particle size distribution in the top bunker that is suitable for forward tilting charging. That is, in the case of forward tilting charging, large particles can be collected at a position away from the raw material discharge port, and many large particles can be discharged at the end of discharge from the furnace top bunker.
On the other hand, under condition 2 (comparative example), in the case of reverse tilting charging, large particles could not be sufficiently collected near the raw material discharge port, and a material particle size distribution in the top bunker suitable for reverse tilting charging was achieved. I couldn't.

Furthermore, even when the shape of the structure is varied in the range of α = 25 to 45°, β = 25 to 45°, and γ = 25 to 45° based on the condition of Condition 1 (invention example), Almost the same results as under Condition 1 (invention example) were obtained. Also, when the position of the top of the structure was varied in the range of r/R=0 to 0.6, almost the same results as under Condition 1 (invention example) were obtained. Furthermore, when the shape of the structure was other than the above-mentioned oblique conical shape or elliptical conical shape, almost the same results as under Condition 1 (invention example) were obtained.

In addition, a model experiment was conducted to confirm the accuracy of the particle size distribution in the furnace top bunker based on the above numerical simulation.
That is, as shown in FIG. 13, furnace top bunker models corresponding to condition 1 (inventive example) and condition 2 (comparative example) of 1/17.8 size of the actual machine were manufactured. In the figure, numeral 10 is a charging belt conveyor, 11 is a furnace top bunker model, 12 is a collection hopper model, 13 is a sampling box, 14 is a roller conveyor, 15 is a belt conveyor for sampling box, and 16 is a segregation control plate model or structure. It is a body model.
Then, the raw material (ore in this case) was charged from the charging belt conveyor into the furnace top bunker model. The charging position of the raw material (the collision position of the raw material in the segregation control plate model and the structure model) was adjusted by changing the position of the charging belt conveyor. After charging, the valve of the discharge port connected to the lower end of the furnace top bunker model was opened, and the raw material was discharged from the discharge port. Then, the discharged raw materials were collected in multiple sampling boxes. At this time, the sampling box was gradually moved horizontally by a sampling box belt conveyor, and the discharged raw materials were separated in chronological order at regular intervals from the start of discharge to the end of discharge. Next, the raw materials collected in each sampling box are sieved, the average particle size of the raw materials collected in each sampling box is calculated, and the average particle size of all the raw materials before charging into the furnace top bunker model is calculated. By dividing, the dimensionless particle size of the raw material for each dimensionless discharge time was calculated. The results are shown in FIGS. 14 and 15.

From FIG. 14 and FIG. 15, data supporting the above numerical simulation results was obtained in the model experiment as well.
That is, under condition 1 (invention example), in the case of forward tilting charging, many large particles could be discharged at the end of discharge from the furnace top bunker. In addition, in the case of reverse tilting charging, many large particles could be discharged from the top bunker at the beginning of discharge.
On the other hand, under condition 2 (comparative example), in the case of reverse tilting charging, many large particles could not be discharged at the initial stage of discharge from the top bunker compared to condition 1 (invention example).

1: Blast furnace 2: Tuyere 3: Ore layer 4: Coke layer 5: Cohesive layer 6: Furnace top bunker 6-1: Raw material storage section 6-2: Raw material outlet 6-3: Segregation control plate 6-4: Structure 6-5: Raw material collision surface 6-6: Dispersion adjustment plate 7: Flow rate adjustment gate 8: Collection hopper 9: Rotating chute 10: Charging belt conveyor 11: Furnace top bunker model 12: Collection hopper model 13: Sampling box 14: Roller conveyor 15: Belt conveyor for sampling box 16: Segregation control plate model or structure model 17: Movable control plate

Claims (4)

A method for charging raw materials into a blast furnace, the method comprising:
The blast furnace has a furnace top bunker at the furnace top,
At least one of the furnace top bunkers is
a raw material storage section;
a raw material charging port for charging the raw material into the raw material reservoir from above the raw material reservoir;
a structure that is disposed inside the raw material storage section and has a raw material collision surface on which raw materials charged from the raw material charging port collide;
a raw material discharge port that discharges the raw material in the raw material storage section below the raw material storage section;
Equipped with
The raw material outlet is arranged eccentrically from the center of the raw material reservoir in a horizontal plane,
Further, the raw material collision surface of the structure is arranged from the top of the structure at least in an eccentric direction, an opposite eccentric direction, and a first direction and a second direction perpendicular to the eccentric direction and a vertical direction, respectively. sloped downward toward the end of the raw material collision surface;
Furthermore, the method for charging raw materials into the blast furnace includes:
a storage step of charging the raw material into the raw material storage part from the raw material charging port of the furnace top bunker, causing the raw material to collide with the structure, and then storing the raw material in the raw material storage part; ,
A charging step of discharging the raw material stored in the raw material storage section from the raw material discharge port and charging the discharged raw material into the blast furnace via the rotating chute of the blast furnace,
When the tilting method in the charging step is reverse tilting charging, the raw material collision position in the structure in the storage step is on the opposite side of the eccentricity from the top of the structure,
When the tilting method in the charging step is forward tilting charging, a material charging method for a blast furnace in which the material collision position in the structure in the storage step is on the eccentric direction side with respect to the top of the structure. .
Here, the eccentric direction is a direction in which the raw material outlet is eccentric from the center of the raw material storage section in the horizontal plane. Moreover, the eccentricity opposite direction is a direction opposite to the eccentricity direction in the same horizontal plane. The inclination angles α and α′ from the horizontal direction of the line segment connecting the top of the structure and the end of the raw material collision surface in the eccentric direction and in the opposite direction of the eccentricity are respectively 25 to 45 degrees. 1. The method for charging raw materials into a blast furnace according to 1. Inclination angles β and γ from the horizontal direction of the line segment connecting the top of the structure and the end of the raw material collision surface in the first direction and the second direction are 25 to 45 degrees, respectively; The method for charging raw materials into a blast furnace according to claim 1 or 2. The blast furnace according to any one of claims 1 to 3, wherein the top of the structure is located in a dimensionless distance (r/R) from the center of the raw material storage part in a range of 0 to 0.6 in a horizontal plane. Raw material charging method.
Here, the dimensionless distance (r/R) is a value obtained by dividing the distance (r) from the center of the raw material reservoir in the horizontal plane by the inner radius (R) of the raw material reservoir.

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