JPH05230509A - Raw material charging method and charging device for bell-less blast furnace - Google Patents

Abstract

PURPOSE:To provide the raw material charging method and device which improve discharge characteristics and exactly control the raw material grain size distribution in the radial direction in a furnace by classifying the raw materials to be charged into a lower hopper by grain sizes during operation while utilizing the natural classification and raw material discharge characteristics on the internal deposition surface of an upper hopper. CONSTITUTION:A hollow cylindrical partition wall 13a having a flow regulating body 13b is provided in the lower hopper 5 of a center feed type bell-less top charger of a single port system disposed with the raw material hoppers in two stages; upper and lower and a splashing preventive plate 13c is mounted around the upper part thereof to provide annular spacing parts S1, S2 where the raw materials can make mass flow between this plate and the hopper wall. The charging raw materials of different grain sizes from the upper hopper 2 are forcibly classified by the partition wall 13a, the flow regulating body 13b and the splashing preventive plate 13c within the lower hopper 5. The discharge into the furnace is executed by the mass flow in order of fine, middle and coarse grains to change the grain sizes for discharge with lapse of time as a 'monotonous increase pattern'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material charging method and apparatus for a bellless blast furnace.

[0002]

Prior Art and Problems to be Solved by the Invention
When charging raw materials into the blast furnace, in recent years, instead of using the method of opening and closing large bells and small bells, instead of using large bells or small bells, charging is done via a distribution chute that can be swung and tilted. A so-called bell-less furnace top charging device for distributing things into the furnace has been widely adopted. And this bellless furnace top charging device includes a "parallel hopper type" device in which furnace bunkers are installed in parallel, and a so-called "center feed type" device in which raw material hoppers are installed in two upper and lower stages. Recently, the latter center feed type device tends to be adopted.

As the center-feed type bellless furnace top charging device, as shown in FIG.
A single port center feed type bellless furnace top charging device is generally known. The operation of the bellless furnace top charging device will be described with reference to FIG. 6. The raw material conveyed to the furnace top by the charging conveyor 1 is charged into the upper hopper 2 and further from the upper hopper 2 to its bottom. It is loaded into the lower hopper 5 through the upper gate 3 provided in the. Next, through the raw material control gate 6, the lower hopper 5
The raw material discharged from the furnace is charged into the furnace through a distribution chute 9 which is swung and tilted by a distribution chute drive device 8.

The center-feed type device is structurally simpler than the parallel-hopper type device, the capital investment is low, and the charge can be distributed almost uniformly in the circumferential direction of the furnace. There are advantages.

However, the single-port center-feed bellless furnace top charging device shown in FIG. 6 has problems due to its structure, as described below.

FIG. 7 is a schematic diagram showing the discharge behavior of the raw materials in the upper and lower hoppers of a conventional single-port type center feed type bellless furnace top charging device. In FIG. 7, the raw material 10a charged into the upper hopper 2 by the charging conveyor 1 or the like is naturally classified on the conical raw material deposition surface in the hopper. Further, in the charging device, that is, in the hopper, fine particles A mainly composed of a raw material having a small particle diameter are provided. In the peripheral portion of the side wall, coarse particles C mainly composed of a raw material having a large particle diameter are provided. Medium grains B are deposited between the grains C.

Next, the upper gate 3 of the upper hopper 2 is opened, and the raw material 12 in the hopper 2 is fed to the lower hopper 5.
The discharge behavior of the raw material 10b at the time of discharging into the inside shows what is called a funnel flow type behavior, in which the fine particles A are discharged at the early stage of discharging, then the medium particles B are discharged, and the coarse particles C are discharged at the final stage of discharging.

FIG. 8 is a diagram schematically showing the change over time in the particle size when the raw material is discharged from the upper hopper 2. Since the raw materials are discharged in this order in the order of the fine particles A, the medium particles B, and the coarse particles C, the change with time of the particle size becomes a “monotonically increasing pattern”.
This tendency remarkably appears in the sinter having a larger particle size distribution range than coke. The horizontal axis in FIG. 8 is a dimensionless time expressed as 1.0 from the start to the end of the discharge of the raw material 12, and the vertical axis is the average particle size of the whole divided by the average particle size at each discharge time (that is, the average is 1.0). The ratio of coarse particles is high when 1.0 or more, and the ratio of fine particles is high when 1.0 or less).

The discharge of the raw material 12 from the upper hopper 2 is performed in a short time (6 to 7 T / sec in the sinter ore) with the upper gate 3 fully opened, so that the raw material 12 is discharged into the lower hopper 5. At the time of deposition, the classification (center portion: fine grains, side wall portion: coarse grains) at the time of material deposition, which occurred in the upper hopper 2, was not sufficiently performed, and as shown in FIG. Fine grain A'on the bottom layer, medium grain B'on it, and coarse grain C'on the top layer.
The deposit surface forms a gentle conical surface when compared with the upper level.

The discharge behavior of the raw material 10c charged into the furnace from the lower hopper 5 through the raw material control gate 6 exhibits a funnel flow type behavior similar to the discharge behavior from the upper hopper 2. That is, in the initial stage of discharging, the raw material a in the central portion of the hopper just above the raw material control gate 6 is discharged, then the raw material b in the portion adjacent thereto and finally the raw material c in the periphery of the side wall portion are discharged.

FIG. 9 is a diagram schematically showing the change over time in discharging the raw material. A coarse particle peak appears in the early stage of discharging, and gradually changes from coarse particles to fine particles after the middle stage of discharging, and around the hopper 5 at the final stage of discharging. Since the coarse particles remaining on the side wall are discharged, the particle size is slightly increased. This tendency appears strongly in the sintered ore as described above. Regarding coke, there is little change in particle size over time, and it becomes a slightly flat “flat pattern”.
Note that, in FIG. 9, the horizontal axis and the vertical axis are defined in the same manner as in the case of FIG.

As described above, the raw material charged into the furnace from the lower hopper 5 through the distribution chute 9 has many coarse particles in the initial stage of discharge, and gradually changes from coarse particles to fine particles. Therefore, the distribution chute 9 is swung from the furnace inner wall side toward the furnace core side,
In the internal swing distribution method in which the distribution of the charge is controlled by tilting, as shown in Fig. 11, the side grain 11b is charged on the inner wall side of the furnace, and the fine grain 11a is charged on the core side, and the particle size is segregated in the radial direction. Occurs.

The air permeability of the furnace interior insert 11 is mainly determined by its average particle size and particle size distribution, and the gas flow distribution is influenced by the layer thickness distribution of the furnace interior insert 11 and the radial particle size segregation. Therefore, in the blast furnace operation in which securing of the core flow is a major premise, the particle size distribution is such that the fine particles 11a are charged on the furnace inner wall side and the coarse particles 11b are charged on the furnace core side as shown in FIG. 5 (a). Is desirable. However, in the case of Fig. 11, the gas flow on the inner wall side of the furnace becomes stronger, the gas flow in the furnace core (core flow) becomes unstable, and an unstable furnace condition in which blow-through or slip is easily induced. Therefore, it is a major limitation for stable operation of the blast furnace.

From the above, the time course pattern of the grain size of the raw material from the lower hopper 5 is a desirable time course pattern of "monotonically increasing pattern".

In the prior art, in order to solve the problem that coarse particles are discharged in the initial stage of discharging the raw material, raw materials having different particle sizes are previously sorted and charged into the furnace (charge by particle size).
However, a method of adjusting the particle size distribution in the radial direction has been proposed (see Japanese Patent Publication No. 55-16203).

However, this method has the following problems. That is, since the raw materials are separately charged according to the particle size, the charging time per charge becomes long, and even if it is attempted to improve the productivity of the blast furnace, it may not be possible to follow it. Further, since the number of times of equalizing and exhausting pressure of the hopper increases, the amount of gas (N ₂ gas) required for that increases. Further, in order to secure raw materials having different particle sizes in advance, a sieving facility and a facility for individually storing these charges are required, and the facility cost for providing this facility is also increased.

As a method for suppressing the discharge of coarse particles in the initial stage of discharging the raw material from the lower hopper 5, the raw material discharging speed from the upper hopper 2 to the lower hopper 5 is reduced so that the deposited raw material is naturally stored in the lower hopper 5. Classification (center:
Fine grain, side wall portion: coarse grain) is performed, and the temporal pattern of the particle size of the raw material discharged from the lower hopper 5 is the "monotonically increasing pattern" as in the temporal pattern of the particle size of the raw material discharged from the upper hopper 2. There is also a method. However, with this method, the discharge time of the raw material becomes long, which leads to the extension of the furnace top time schedule, which may not be able to cope with the increase in the productivity of the blast furnace.

In addition to this, a hollow cylinder is installed in the lower hopper, and fine particles discharged from the upper hopper in the initial stage are charged into the hollow cylinder. In some cases, the raw material is moved upward for mass flow (see JP-A-61-157604). However, the inside of the lower hopper is high temperature, high pressure, and much dust, it is difficult to install a device for moving the inner cylinder, and even if it is installed, the maintenance is difficult and it is not practical.

Then, in the lower hopper, a cylinder (Japanese Patent Laid-Open No.
60-43414), and the above-mentioned JP-A-61-15
There are some which aim at the same effect as the 7604 publication. However, in this case, the fine particles that did not enter the cylinder repel the raw material deposited on the cylinder and are deposited on the wall side, and medium particles and coarse particles are deposited between the cylinder and the fine particles. The pattern of the particle size of the raw material discharged from the hopper 5 cannot be made a “monotonically increasing pattern”.

Further, a double cylinder is installed on the small bell, and fine particles in the inner cylinder, medium particles between the inner cylinder and the outer cylinder, and coarse particles outside the outer cylinder are forcibly charged, and the inner circle of the furnace is There is an attempt to evenly distribute the raw material in the circumferential direction (see Japanese Patent Publication No. 61-10526). However, in this case, the target is the bell blast furnace, and even if it is installed in the lower hopper 5 of the center feed type bellless blast furnace, fine particles fall straight from the upper hopper 2 into the inner cylinder, However, similar to Japanese Patent Laid-Open No. 60-43414, there is a large repulsion between the deposited raw material on the upper surface of the inner cylinder and the fine, medium and coarse particles charged later from the upper hopper 2.
Fine particles and medium particles, in particular, repel more than coarse particles.Therefore, coarse particles are charged between the inner and outer cylinders, and fine particles and medium particles are charged outside the outer cylinder. The pattern does not become a “monotonically increasing pattern”.

Further, there is a method in which a current plate is installed in the lower hopper 5 and the position is adjusted so that the raw material mass flows between the current plate and the hopper wall. However, since some of the raw material remains on the straightening vane, the deposition status of the raw material charged after the second time will change, and the fine particles initially fed from the upper hopper below the straightening vane will be changed. , Yields on the straightening vanes, and when the lower hopper 5 is charged into the furnace, the fine particles are not initially discharged, and the "monotonically increasing pattern" does not occur.

The present invention was devised in view of the above-mentioned circumstances, and its purpose is to utilize the classification naturally performed on the raw material depositing surface in the upper hopper and the discharge characteristics of the raw material from the upper hopper to make use of the lower hopper. The raw material charging method that can separate the raw material charged into the furnace according to the particle size during operation, improve the discharge characteristics of the raw material from the lower hopper, and accurately control the particle size distribution of the raw material in the radial direction inside the furnace. Another object of the present invention is to provide a raw material charging device for carrying out this raw material charging method.

[0023]

The present invention is a bellless blast furnace having a single-port type center feed type bellless furnace top charging device in which raw material hoppers are arranged in upper and lower two stages on the furnace top. The change in the particle size of the raw material with time can be controlled.

The gist of the present invention is described below (1)
The method of charging raw materials for the bellless blast furnace and the apparatus for charging raw materials of (2).

(1) When charging the raw material into the furnace by means of a single-port type center feed type bellless furnace top charging device in which the raw material hoppers are arranged in upper and lower two stages, first, in the lower hopper, The raw material is charged from the upper hopper into a central empty space formed by being partitioned by a coaxial cylindrical or polygonal tubular partition wall. At this time, first, the fine particles are charged into the central void, and then the raw material is overflowed from the central void and applied to the anti-scattering plate to deposit the medium particles downward and the coarse particles upward. Then, the state of deposition of the raw material in the lower hopper is controlled.

In this way, the raw material after charging and filling is opened by opening the gate at the bottom of the lower hopper,
After discharging the raw material in the central empty space, the flow velocity of the raw material around the partition wall is controlled by the substantially conical rectifier installed around the partition wall, and the rectifier between this rectifier and the slope below the hopper is controlled. A raw material charging method in a bellless blast furnace, characterized in that the raw material is discharged from the annular gap portion by mass flow and charged into the furnace.

(2) In the lower hopper of the single-port type center-feed type bellless furnace top charging device in which the raw material hoppers are arranged in the upper and lower stages, a partition wall having a cylindrical shape or a polygonal cylinder shape coaxial with the hopper axis In addition to this, a substantially conical rectifying body is provided around this partition wall, and the raw material at the time of discharging the raw material passes between the partition wall and the rectifying body and the lower slope of the lower hopper. A raw material charging apparatus in a bellless blast furnace, which is capable of and has an annular gap portion for mass flow.

[0028]

[Examples] Below, the above-mentioned "means for solving the problems"
A specific example of the raw material charging device of the present invention having the above-mentioned configuration, its function and effect, and the raw material charging method of the present invention performed using this raw material charging device will be described.

FIG. 1 is a schematic vertical sectional view showing an example of the constitution of the raw material charging apparatus of the present invention. In this figure, an upper seal valve 4 is provided above the lower hopper 5 for equalizing and discharging the hopper 5 so that raw materials can be charged into the furnace.
However, below the lower hopper 5, a raw material control gate 6 and a lower seal valve 7 for adjusting the flow rate of the raw material charged into the furnace are installed.

A cylindrical supporting beam 14a and a supporting beam blanket 15a are mounted in the lower hopper 5, and a cylindrical partition wall 13a coaxial with the axis of the hopper 5 is installed on the cylindrical supporting beam 14a. ing.

Between the lower end of the partition wall 13a and the slope of the lower portion of the hopper 5, there is secured an annular gap portion through which the raw material can pass. Further, a substantially conical rectifying body 13b is installed below the outer periphery of the partition wall 13a, and an appropriate annular gap portion is provided between the lower wall and the lower hopper so that the raw material is mass-flowed. There is. It should be noted that the gap may have a size that is, for example, about 6 times the maximum particle size of the filling material and the maximum particle size of the normal coke.

Further, a scattering prevention plate 13c is provided above the lower hopper 5. 2 is an enlarged vertical sectional view of the lower hopper 5 in the raw material charging apparatus shown in FIG.
Shows the three-dimensional view. In these figures, the partition wall 13
a and the rectifying body 13b are mounted in the lower hopper 5, and the partition wall 13a forms a cylindrical or ring-shaped void (a).

A gap S2 is provided between the lower end of the partition wall 13a and the lower slope of the hopper 5 (the conical surface 5a of the hopper 5) so that the raw material to be charged can pass therethrough. .. As for the work 13b, a gap S2 is provided between the work 13b and the sloped wall of the hopper so that the raw material can mass flow.

In this example, the raw material charging device in which the partition wall 13a and the rectifying body 13b are installed is shown, but the partition wall 13a and the rectifying body 13b may have a polygonal shape of 8 to 32, for example. A polygonal shape is preferable for the top. this is,
Since the partition wall 13a is impacted by the charging raw material from the upper hopper 2 and is abraded when the raw material flows down, it is necessary to attach a wear resistant liner, but since a liner on a flat plate is usually used, a polygonal shape is used. This is because it is easier to install.

The gap S3 between the shatterproof plate 13c and the partition wall 13a also needs to have a size corresponding to the particle size of the charging raw material, and the maximum particle size of the raw material to be charged (usually coke is Stable discharge of the raw material is possible by securing a size of about 6 times or more (having the maximum particle size). If this gap is too large, the materials will not be ejected in order as will be described later when it is ejected, and if it is too small, rack hanging will occur and there is a risk of blockage.

The size of the partition wall 13a may be determined so that the fine particles A charged from the upper hopper 2 can be stored in the space (a) formed by partitioning the partition walls. ..

Next, the procedure for carrying out the raw material charging method of the present invention using the raw material charging device and the behavior of the raw material in the lower hopper 5 at that time will be described with reference to FIG.

First, when charging the raw material into the lower hopper 5, the raw material control gate 6 at the bottom of the hopper 5 is closed, the upper seal valve 4 is opened, and then the upper gate 3 is fully opened. ..

The raw material for the upper hopper 2 is shown in FIG.
As described above, since the fine particles A are discharged in the order of the fine particles A, then the medium particles B, and the coarse particles C in the final stage, the fine particles A are surrounded by the partition wall 13a in the lower hopper 5 at first. It is loaded into the void (a) (see (a) in Fig. 4). Next, the medium particles B and the coarse particles C are discharged from the upper hopper 2 and overflow the vacant space (a) of the lower hopper 5 to overflow the partition wall 13a.
Pile up. (Medium particles are deposited under the coarse particles as shown in (b) and (c) of FIG. 4.) After that, the control gate 6
When is opened, the fine particles "a" in the void (a) immediately above the opening are preferentially discharged (see Fig. 4 (d)). Next, the discharge of the fine particles "a" is completed, and in the subsequent discharge, the raw material mainly composed of the medium particles "a" accumulated around the partition wall 13a becomes a mass flow to form the gap S.
2, S1 (see FIG. 2) is discharged (see FIG. 4).
(See (e)).

At the end of discharging, the raw material mainly composed of coarse grains "c" deposited around the side wall of the hopper 5 is discharged through S2 and S1 along the hopper surface 5a (Fig. (See (f) of 4).

FIG. 5 is a diagram schematically showing the time-dependent change in particle size when the raw material is discharged from the lower hopper 5. Fine particles are discharged in the initial stage of discharge, then medium particles are discharged, and finally coarse particles are discharged. Therefore, the “monotonically increasing pattern” similar to the case shown in FIG. 8 is obtained. The horizontal and vertical axes in FIG. 5 are shown in FIG.
The same as in the case of.

As described above, when the raw material charging method of the present invention is applied, the discharge pattern of the raw material charged into the furnace from the lower hopper 5 can be controlled during the operation, and the operation of the blast furnace can be controlled. Stability and operational range can be expanded.

[0043]

INDUSTRIAL APPLICABILITY In a bellless blast furnace having a single port type center feed type bellless furnace top charging device in which raw material hoppers are vertically arranged on the furnace top, the raw material is charged into the furnace by applying the method of the present invention. By doing so, the particle size distribution in the radial direction in the furnace can be accurately controlled. That is,
Since the particle size of the raw material discharged from the lower hopper has a "monotonically increasing pattern", when the raw material is charged into the furnace by the internal swing method, fine particles are deposited on the inner wall side of the furnace and coarse particles are deposited on the core side. Can be made

As a result, it becomes possible to properly control the gas flow distribution in the blast furnace, and the effects of stable operation of the blast furnace and reduction of fuel cost can be obtained. Further, such control of particle size distribution can be easily performed by using the apparatus of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic view showing a raw material charging device of the present invention in a single-port type center feed type bellless furnace.

FIG. 2 is an enlarged schematic view showing a lower hopper in the raw material charging device of the present invention.

FIG. 3 is a schematic perspective view showing a partition wall, a shatterproof plate, and a rectifying body according to the present invention.

FIG. 4 is a schematic view showing the behavior of the raw material in the lower hopper in the present invention.

FIG. 5 is a graph showing changes over time in the particle size discharged from the lower hopper into the furnace in the present invention.

FIG. 6 is a schematic view showing a conventional raw material charging device.

FIG. 7 is a schematic diagram showing a state of raw material deposition in the upper and lower hoppers of a conventional raw material charging apparatus.

FIG. 8 is a graph showing changes over time in the particle size discharged to the upper hopper.

FIG. 9 is a graph showing a change over time in the particle size discharged from the lower hopper into the furnace in the related art.

FIG. 10 is a schematic diagram showing a desirable state of deposition of raw materials in a furnace in a blast furnace operation.

FIG. 11 is a schematic view showing a state of raw material deposition in a furnace in a conventional blast furnace operation.

[Explanation of symbols]

1 ... Charging conveyor, 2 ... Upper hopper, 3 ... Upper gate, 4 ... Upper sealing valve, 5 ... Lower hopper, 5a ... Hopper surface, 6 ... Control gate, 7 ... Lower sealing valve,
13a ... partition wall, 13b ... rectifier, 13c ... scatter prevention plate, 14
a ... Cylindrical support beam, 15a ... Support beam blanket.

Claims (2)

[Claims] 1. A raw material charging method for charging a raw material into a furnace by means of a single-port type center feed type bellless furnace top charging device in which the raw material hoppers are installed in upper and lower two stages. Inside, a partition wall formed in the shape of a cylinder or a polygonal cylinder that is coaxial with the hopper axis is installed, and to the empty space in the center of the hopper that is partitioned by this partition wall, the raw material from the upper hopper Then, the raw material to be charged into the void in the central portion of the lower hopper is caused to overflow from the void in the central portion, and the overflowing raw material is provided at the upper peripheral position of the partition wall, The shatterproof plate, which is coaxial with the hopper axis and has a downwardly squeezed bottom, is applied to the shatterproof plate, and then the material applied to the shatterproof plate is passed between the shatterproof plate and the partition wall. Ring of The material is charged from the upper hopper into the lower hopper by passing through the gap and re-classifying around the partition wall in the order of thin, medium, and coarse from near the partition wall to the hopper wall side. Completion, then, by opening the gate of the bottom hopper bottom, first discharge the raw material in the central void, then the raw material adjacent to the central void, the lower slope of the lower hopper, Charge the raw material from the lower hopper into the furnace by passing through the annular gap between the rectifying body having a substantially conical shape provided on the partition wall and the lower end of the partition wall, and discharging. A method of charging raw materials for a bellless blast furnace characterized by: 2. An annular gap in the lower hopper of a single-port type center feed type bellless furnace top charging device in which the raw material hoppers are arranged in upper and lower two stages, and a raw material can pass through the lower surface of the hopper at the time of discharge. The partition wall is installed so that it can be formed with a cylindrical or polygonal cylindrical partition coaxial with the hopper shaft core, and an annular gap is formed in this partition wall where the raw material can mass flow with the sloped surface below the hopper. A substantially conical rectifying body that is provided so that it can be provided in an upper peripheral position of the partition wall so as to form an annular gap portion through which the raw material can pass when charging from the upper hopper with the partition wall. In addition, the raw material charging device for the bellless blast furnace is characterized by comprising a polygonal cylindrical anti-scattering plate that is concentric with the hopper axis and has a narrowed lower part.