JP7700764B2 - Apparatus and method for producing raw materials for blast furnaces - Google Patents

Description

The present invention relates to an apparatus and method for producing raw materials for blast furnaces, such as molded coke, particularly ferrocoke, used in blast furnaces.

In recent years, the steel industry has been required to reduce the amount of CO2 gas generated in order to prevent global warming. For this reason, it is urgent to reduce the use of fossil fuels. In the steel industry, molten iron is produced in blast furnaces by reducing iron ore with carbon (coke produced by carbonizing coal in a coke oven). In order to reduce the coke consumption, technology is being developed to use ferro-coke as a raw material for blast furnaces. Ferro-coke is made by mixing a certain amount of iron ore with coal, forming it into agglomerates, and then carbonizing it to disperse fine metallic iron particles in the coke. It is a molded coke in which the catalytic action of metallic iron increases the reactivity of the coke.

A method using a vertical carbonization furnace has been proposed as a method for carbonizing ferro-coke. Patent Document 1 discloses a vertical carbonization furnace having a carbonization zone at the top and a cooling zone at the bottom. The method for producing ferro-coke in a vertical carbonization furnace includes a charging process in which a molded material consisting of a carbon-containing material and an iron-containing material is charged into the vertical carbonization furnace using a charging device, a carbonization process in which heated gas is blown into the carbonization zone and the molded material is carbonized to produce ferro-coke, a cooling process in which cooling gas is blown into the cooling zone to cool the ferro-coke, an in-furnace gas discharge process in which furnace gas is discharged from an outlet at the top of the vertical carbonization furnace, and a ferro-coke discharge process in which ferro-coke is discharged from the bottom of the cooling zone.

In the carbonization process, the molded products are heated by blowing low-temperature gas into the furnace through a low-temperature gas blowing tuyeres in the middle of the carbonization zone, and high-temperature gas into the furnace through a high-temperature gas blowing tuyeres in the lower part of the carbonization zone. In the cooling process, the ferro-coke is cooled by blowing cooling gas into the cooling gas blowing tuyeres in the lower part of the cooling zone.

Here, in order to increase the production volume of ferro-coke, it is necessary to increase the volume of the vertical carbonization furnace. Generally, the charge material is charged at an angle using an inclined charging chute, but since the heating gas and cooling gas are injected in the depth direction of the vertical carbonization furnace (parallel to the horizontal component of the charge material charging direction), the internal dimension in the depth direction must be kept below a certain level in order for the gas to penetrate to the center of the furnace. Therefore, vertical carbonization furnaces are designed with an internal dimension that is longer in the furnace width direction (the direction perpendicular to the depth direction in the cross section of the carbonization furnace) than in the depth direction, ensuring a large volume.

Patent Document 2 also discloses a method for uniformly loading (transporting) materials, which involves providing a dispersion guide section with an inclined surface that slopes radially downward from the center of the width of the transport path toward the exit side, thereby dispersing the materials radially.

JP 2011-57970 A JP 2011-162271 A

The molded material is fed to the carbonization furnace through a chute. During this process, the molded material breaks down when it collides with the wall of the chute, and some of it becomes powder. In other words, the molded material contains granular material and powder that is smaller in volume than the granular material.

The powder settles through the gaps between the granules. Therefore, the molded product is supplied to the carbonization furnace in two separate layers: a granular layer (upper layer) and a powder layer (lower layer). In other words, the granular layer is supplied to the carbonization furnace in a state where it is located above the powder layer. Therefore, when the granular material is supplied to the carbonization furnace from the chute, it is piled up farther than the powder, and the powder is piled up on the chute side.

When the molded material is fed into the carbonization furnace, a slope of the pile is formed according to the angle of repose. Therefore, when the powder reaches the slope of the pile, it moves along the slope to the opening side of the chute and comes to rest. In particular, when the powder reaches the top of the slope of the pile, the slope becomes steeper, so the powder tends to move further toward the opening side of the chute. In contrast, the granular material moves farther than the powder, so most of it reaches near the top of the pile. In other words, the granular material is fed evenly onto the slope of the pile.

In this way, the granular material of the molded product and the powder tend to accumulate in biased positions in the dry distillation furnace. Therefore, when the powder accumulates in a biased position, the breathability of that area becomes worse than other areas. In areas where the powder accumulates in a biased position, the amount of heated gas supplied decreases due to the deterioration of breathability, and the molded product supplied to that area may suffer defects such as poor dry distillation.

Even if the bulk material guide unit described in Patent Document 2 is used when feeding the molded material into the dry distillation furnace, it is not possible to prevent such powder from accumulating in a biased position. For this reason, there is a need to improve the above problem.

The present invention has been made to solve the above problems, and aims to provide a blast furnace raw material manufacturing device and a blast furnace raw material manufacturing method that can improve the quality and productivity of blast furnace raw materials such as ferro coke.

In order to achieve the above object, the present invention provides
[1] A raw material manufacturing apparatus for a blast furnace which produces raw material for a blast furnace by carbonizing a charge containing a carbon-containing material charged into a carbonization furnace, the raw material manufacturing apparatus having a recovery device which sucks up and recovers powder from the charge charged into the carbonization furnace inside the carbonization furnace.
[2] The recovery device is provided on a side wall portion of the carbonization furnace that is above the top of the pile of charge materials accumulated in the carbonization furnace.
[3] A blast furnace raw material manufacturing apparatus as described in [1] above, further comprising a charging chute connected to a side wall portion at the top of the carbonization furnace for charging the charge material into the carbonization furnace, the recovery device being located in a side wall portion below the charging chute among the side wall portions in which the charging chute is provided, and at least a portion of the recovery device being located in a position overlapping with the charging chute when viewed from the top-bottom direction of the carbonization furnace.
[4] A blast furnace raw material manufacturing apparatus as described in [2] above, further comprising a charging chute connected to a side wall portion at the top of the carbonization furnace for charging the charge material into the carbonization furnace, the recovery device being provided in a side wall portion lower than the charging chute among the side wall portions in which the charging chute is provided, and at least a portion of the recovery device being provided in a position overlapping with the charging chute when viewed from the top-bottom direction of the carbonization furnace.
[5] The blast furnace raw material manufacturing apparatus according to the above [1], wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less.
[6] The apparatus for producing raw materials for a blast furnace according to the above [2], wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less.
[7] The apparatus for producing raw materials for a blast furnace according to the above [3], wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less.
[8] The apparatus for producing raw materials for a blast furnace according to the above [4], wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less.
[9] The blast furnace raw material manufacturing apparatus according to the above [3], further comprising a charging gate provided in the charging chute for temporarily retaining the charging material.
[10] The blast furnace raw material manufacturing apparatus according to the above [4], further comprising a charging gate provided in the charging chute for temporarily retaining the charging material.
[11] A method for producing raw materials for a blast furnace using the apparatus for producing raw materials for a blast furnace according to any one of [1] to [10] above.

According to the present invention, the powder of the molded particles and powder contained in the carbon-containing material charged into the carbonization furnace is recovered, and the molded particles are carbonized to produce raw material for the blast furnace. This makes it possible to improve the quality and productivity of raw material for the blast furnace.

FIG. 1 is a schematic side view showing an example of a conventional vertical carbonization furnace. FIG. 2 is a side cross-sectional view showing the top of a carbonization furnace as a blast furnace raw material manufacturing apparatus according to the present invention. FIG. 4 is a diagram for explaining recovery of powder by a recovery device. FIG. 11 is a diagram showing the correlation between the molding suction rate and powder removal rate and the gas flow rate in the recovery device.

The present invention will be explained below through the embodiments of the present invention, taking as an example the case of producing ferro-coke, a type of molded coke made by mixing a certain amount of iron ore with coal and agglomerating it. The drawings are schematic and may differ from the actual product. In addition, the following embodiments are illustrative of devices and methods for embodying the technical ideas of the present invention, and are not intended to specify the configuration as described below. In other words, the technical ideas of the present invention can be modified in various ways within the technical scope described in the claims.

With reference to Figure 1, the configuration of a vertical carbonization furnace 100 as a conventional blast furnace raw material manufacturing device will be described. Figure 1 shows a schematic side view of a vertical carbonization furnace 100. In the following description, "charge" is not limited to "molded products containing a carbon-containing material and an iron-containing material" for producing ferro coke, but may also include "molded products containing a carbon-containing material." In other words, it is sufficient if the molded products contain at least a carbon-containing material. "Charge" includes "molded products" and "powder" attached to or separated from the "molded products." In addition, "raw materials for blast furnaces" means "coke" including ferro coke.

The vertical carbonization furnace 100 has a charging chute 10, a charging gate 20, a diffusion section 30, and a carbonization furnace body 70. First, the charging material including molded materials containing carbon-containing materials (coal) and iron-containing materials (iron ore) is supplied to the charging chute 10 provided above the carbonization furnace body. The charging material is temporarily accumulated inside the charging chute 10 (midway through the charging chute 10) by closing the charging gate 20 (see the dashed line in the figure). The charging material passes through the inside of the charging chute 10 toward the carbonization furnace body 70 by opening the charging gate 20 (shown by a solid line in the figure). The charging material is dispersed so as to spread inside the charging chute 10 by passing through the diffusion section 30 of the charging chute 10. After passing through the inside of the charging chute 10, the charging material is deposited inside the carbonization furnace body 70. The charge material forms a mountain shape inside the carbonization furnace body 70 according to the angle of repose.

As described above, the charge material charged into the carbonization furnace body 70 is separated into two layers, a molded material layer (upper layer) and a powder layer (lower layer), inside the charging chute 10 before it reaches the carbonization furnace body 70. Therefore, as shown in FIG. 1, the charge material charged into the carbonization furnace body 70 falls into the inside of the carbonization furnace body 70 while separating into the molded material layer 40 and the powder layer 50. Therefore, the charge material 60 accumulated inside the carbonization furnace body 70 is in a state in which the molded material and the powder are unevenly distributed. Due to this uneven distribution, in the conventional vertical carbonization furnace 100, the gas flow inside the carbonization furnace body 70 becomes uneven, causing problems such as poor carbonization of the molded material.

2 is a side cross-sectional view showing the furnace top of the carbonization furnace 1 as the blast furnace raw material manufacturing apparatus of the present invention. As shown in FIG. 2, the charging chute 10 is connected to one of the side walls 80, 81 of the furnace top of the carbonization furnace 1 that face each other in the depth direction S of the carbonization furnace 1. A recovery device 90 is connected to the side wall 80 below the charging chute 10 in the side wall 80 and above the top DMtop of the molded material DM (hereinafter referred to as the deposit) deposited inside the carbonization furnace 1. The recovery device 90 is configured to suck and recover the powder contained in the molded material charged into the carbonization furnace 1 from the charging chute 10. Specifically, the side wall 80 has a suction hole 91 that penetrates the side wall 80 in the thickness direction, and the recovery device 90 is connected to the suction hole 91 via a suction pipe 92. The powder contained in the molded material will be described later.

The shape of the suction hole 91 can be, for example, a circle or a rectangle, and in the example shown here, it is a rectangle. Other cross-sectional shapes of the suction tube 92 may be cylindrical or angular. The inner dimensions of the suction hole 91 or the diameter of the inscribed circle of the suction hole 91, and the inner dimensions of the suction tube 92 or the diameter of the inscribed circle of the suction tube 92 are set to be larger than the particle size of the powder so that the powder can move inside them. In addition, the inner dimensions of the suction hole 91 or the diameter of the inscribed circle of the suction hole 91, and the inner dimensions of the suction tube 92 or the diameter of the inscribed circle of the suction tube 92 are preferably set to an inner diameter of about the particle size of the molded product, and more preferably set to an inner diameter of about 1.5 times the particle size of the molded product.

The gas flow rate in the suction hole 91 and suction pipe 92 by the recovery device 90 is preferably set to 10 m/s or more and 22 m/s. If the gas flow rate is less than 10 m/s, it may not be possible to suction and recover the powder, and if the gas flow rate is higher than 22 m/s, there is a possibility that the molded product will be recovered in addition to the powder, so this is to avoid these. The recovery device 90 only needs to be configured to be able to suction the powder together with the gas inside the dry distillation furnace 1 within the above-mentioned gas flow rate range.

In addition, the suction holes 91 are preferably provided at a position where at least a portion of the suction holes 91 and the charging chute 10 overlap each other in the width direction (not shown) of the carbonization furnace 1 when viewed from the top and bottom of the carbonization furnace 1. This is to ensure that the powder that is charged into the carbonization furnace 1 from the charging chute 10 and falls can be reliably sucked in and collected. In addition, the number of suction holes 91 is not limited, but if the carbonization furnace 1 is provided with multiple charging chutes 10, it is preferable to provide at least one suction hole 91 for each charging chute 10. Multiple suction holes 91 may be provided at regular intervals across the entire width of the charging chute 10 in the width direction (not shown) of the carbonization furnace 1.

The recovery device 90 may be driven by a control device or an operator (not shown), and may be configured to stop its operation. Since the recovery device 90 sucks in the powder together with the gas, a separation device (not shown) may be provided in the suction pipe 92 to separate and recover the gas and powder. If a separation device is provided, the separated and recovered powder may be molded by a molding device and charged into the inside of the dry distillation furnace 1.

Next, the operation and effect of the blast furnace raw material manufacturing apparatus configured as described above will be explained with reference to FIG. 3. A batch of molded products is transported by a transport device (not shown) to the charging chute 10 with the charging gate 20 closed. As described above, part of the molded products becomes powder during the transport process, and the powder moves to the bottom of the molded products through the gaps between the molded products. Therefore, inside the charging chute 10, the molded product layer 40 and the powder layer 50 are separated into two layers.

Then, the charging gate 20 is opened, and the molded material is charged into the carbonization furnace 1, which is located at a lower position than the charging chute 10. The charging gate 20 may be opened by an operator, or by providing an actuator that opens and closes the charging gate 20 and a control device (not shown) that controls the operation of the actuator. If a control device is provided, the actuator may be driven to open the charging gate 20, for example, at a preset time interval or as a trigger of a signal input to the control device from outside.

Suction by the recovery device 90 begins almost simultaneously with the opening of the charging gate 20. The recovery device 90 may start suctioning as described above by an operator or a control device. For example, the opening of the charging gate 20 may be used as a trigger to drive the recovery device 90. The molded material that passes through the charging gate 20 passes over the diffusion section 30, and is dispersed so as to spread inside the charging chute 10 and is charged into the inside of the carbonization furnace 1. At this time, since the molded material is charged from a position higher than the powder, it falls toward the side wall section 81 rather than the powder.

In contrast, the powder falls toward the side wall portion 80. Since the recovery device 90 is driven, the powder that falls from the charging chute 10 is sucked up and recovered by the recovery device 90, as shown in FIG. 3. This prevents powder from accumulating inside the carbonization furnace 1, and mainly the molded products are charged and accumulated to form the deposit DM. In other words, it is possible to prevent or suppress the uneven accumulation of powder on the charging chute 10 side inside the carbonization furnace 1. Therefore, it is possible to suppress the deterioration of the air permeability inside the deposit DM caused by the uneven accumulation of powder on the charging chute 10 side.

When one batch of molded materials has been loaded into the carbonization furnace 1, the loading gate 20 is closed to cut off communication between the loading chute 10 and the carbonization furnace 1, and suction by the recovery device 90 is stopped. These operations may be performed by an operator as described above, or by a control device that controls the operating state of the loading gate 20 and the recovery device 90. Alternatively, the time that has elapsed since the loading gate 20 was opened may be measured by a timer (not shown), and when the elapsed time exceeds a preset time, the loading gate 20 may be closed and suction by the recovery device 90 may be stopped.

Therefore, with the blast furnace raw material manufacturing apparatus configured as described above, the gas permeability is almost uniform throughout the carbonization furnace 1, and the variation in the degree of carbonization of the molded products and molded product particles can be suppressed. As a result, the variation in the quality of the ferro coke can be suppressed, and high-quality ferro coke can be obtained, which in turn improves the productivity of ferro coke.

Next, an example carried out to confirm the action and effect of the present invention will be described. In this example, a test device simulating the blast furnace raw material manufacturing equipment shown in FIG. 2 was used. The charging chute used was the same shape as that installed in the blast furnace raw material manufacturing equipment shown in FIG. 2. A recovery box likened to a carbonization furnace was installed on the outlet side of the charging chute. In addition, a suction hole of a recovery device configured almost the same as the suction hole 91 of the recovery device 90 described above was connected to the lower side of the part of the side wall surface of the recovery box to which the charging chute was connected. In other words, the powder recovery efficiency was investigated when raw materials including molded objects and powder were charged inside the recovery box likened to the carbonization furnace 1.

25 kg of raw materials containing molded products and powder were charged into the recovery box through the charging chute. While the raw materials were being charged, the recovery device continuously sucked in the gas in the recovery box and the powder being charged through the charging chute. The ratio of powder to the raw materials charged into the recovery box was 10%, and the ratio of molded products was 90%. In this example, for convenience, particles with a diameter of 20 mm or more were defined as "molded products", and particles with a diameter of less than 20 mm were defined as "powder".

The gas flow rate in the suction pipe of the recovery device was then changed to investigate the suction rate of the molded products and the powder removal rate by the recovery device. After the raw materials were completely loaded into the recovery box, suction by the recovery device was stopped. The molded product suction rate was expressed as a percentage (mass%), calculated by dividing the mass of the molded products sucked in by the recovery device by the mass of the raw materials loaded into the recovery box from the loading chute. The powder removal rate was expressed as a percentage (mass%), calculated by dividing the mass of the powder removed by the recovery device by the mass of the raw materials loaded into the recovery box from the loading chute.

Figure 4 shows the correlation between the molded product suction rate and powder removal rate and the gas flow rate in the recovery device. As shown in Figure 4, it was observed that the powder removal rate increases rapidly as the gas flow rate in the recovery device gradually increases from 0 m/s. When the gas flow rate is approximately 10 m/s or more, the increase in the powder removal rate is observed to be slower than when the gas flow rate is less than 10 m/s. On the other hand, the molded product suction rate is 0% up to a gas flow rate of 22 m/s, but it is observed to increase rapidly when the gas flow rate exceeds this. From this result, it can be seen that it is preferable to set the gas flow rate in the recovery device to 10 m/s or more and 22 m/s or less. On the other hand, when the gas flow rate is less than 10 m/s, the powder cannot be sufficiently recovered, and when the gas flow rate is higher than 22 m/s, the molded product becomes mixed in with the product recovered by the recovery device, which is not preferable.

REFERENCE SIGNS LIST 1 Carbonization furnace as a raw material manufacturing device for a blast furnace 10 Charging chute 20 Charging gate 30 Diffusion section 40 Molded material layer 50 Powder layer 70 Carbonization furnace body 80, 81 Side wall section 90 Recovery device 91 Suction hole 92 Suction pipe DM Deposit DMtop Top of deposit

Claims (7)

A blast furnace raw material producing apparatus for producing blast furnace raw material by carbonizing a charge containing a carbon-containing material charged into a carbonization furnace,
A recovery device that sucks and recovers powder among the materials charged into the carbonization furnace inside the carbonization furnace ;
A charging chute connected to a side wall portion at the top of the carbonization furnace for charging the charge material into the carbonization furnace ,
The recovery device is a side wall portion below the charging chute among the side wall portions on which the charging chute is provided, and is disposed in a position where at least a portion of the recovery device overlaps with the charging chute when viewed from the vertical direction of the carbonization furnace . The blast furnace raw material manufacturing apparatus according to claim 1, wherein the recovery device is provided on a side wall portion of the carbonization furnace that is above the top of the pile of the charge material accumulated in the carbonization furnace. The blast furnace raw material manufacturing apparatus according to claim 1, wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less. The blast furnace raw material manufacturing apparatus according to claim 2, wherein the gas flow velocity in the recovery device is 10 m/s or more and 22 m/s or less. 2. The apparatus for producing raw material for a blast furnace according to claim 1 , further comprising a charging gate provided in the charging chute for temporarily retaining the charging material. 3. The apparatus for producing raw material for a blast furnace according to claim 2 , further comprising a charging gate provided in the charging chute for temporarily retaining the charging material. A method for producing raw material for a blast furnace, comprising the steps of: producing raw material for a blast furnace by using the apparatus for producing raw material for a blast furnace according to any one of claims 1 to 6 ;

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