JP6102495B2 - Blast furnace raw material charging device and blast furnace raw material charging method - Google Patents

Description

  The present invention relates to a raw material charging apparatus for a blast furnace and a raw material charging method for a blast furnace. In particular, the present invention relates to a raw material charging apparatus for a blast furnace and a raw material charging method for a blast furnace that reduce variations in discharge of charges from an eccentric type furnace top hopper.

  Due to the recent deterioration of resources, there is a demand for a wide variety of charges used in blast furnaces. In such an environment, in order to achieve high output and low reducing material ratio operation, development of a charge distribution control technology with higher accuracy than before is expected.

In order to stably operate a large blast furnace, it is important to ensure the permeability of reducing gas in the blast furnace.
The air permeability of the blast furnace is because the radial ventilation resistance distribution is formed by (1) the distribution of the ore and coke layer thickness ratio (hereinafter referred to as O / C) in the radial direction and (2) the radial particle size distribution. The controls (1) and (2) are important.

  In a blast furnace, a charging method is generally used in which ore and coke are sequentially charged into the furnace to form an ore layer and a coke layer. It is effective to secure a constant central flow in order to ensure the gas permeability of the gas in the blast furnace, and create an appropriate coke layer in the furnace. Moreover, since the ore layer forms a cohesive zone (softening and melting region of ore at 1200 to 1400 ° C.) having a high pressure loss in the furnace, it is important to create an appropriate cohesive zone.

  Here, the ore is mainly sintered ore, but also includes pellets, lump ore and auxiliary materials. It is important that these various raw materials have different particle sizes and densities, and ores with different properties are controlled and uniformly charged into the furnace.

  On the other hand, in recent years, an ore / small coke mixed charging method in which a small coke (approximately 10 to 40 mm) is mixed and charged in an ore has been adopted in a blast furnace. By mixing small coke with the ore, the air permeability of the ore layer is improved and the productivity is improved, and at the same time, the ore and small coke particles are brought close to each other to improve the ore reducibility and improve the blast furnace. The purpose is to reduce the reducing material ratio.

  Since various ores or small coke mixed with ore layers have different particle sizes and densities, there is a problem that segregation of the ore layers is caused when charged in a blast furnace.

As a method for controlling the distribution of charges, in recent large-scale blast furnaces, a chute is provided at the top of the furnace and the elevation angle can be changed, and this chute is used to charge the raw material into the furnace in a ring shape. A swivel chute-type raw material charging device is employed (hereinafter referred to as a bellless blast furnace).
Various raw materials charged in the blast furnace have different particle sizes and densities. For example, raw materials with small particle sizes and raw materials with large densities remain at the falling position on the charged surface, and raw materials with large particle sizes The raw material having a low density rolls down the charged material surface and easily deposits in the furnace center and in the vicinity of the furnace wall. In addition, coke having a lower density than ore is repelled by the ore charged thereafter and easily rolls and accumulates in the center of the furnace.

  In the bell-less blast furnace, the blast furnace raw material transported by the charging conveyor is temporarily stored in the furnace top hopper and then charged into the furnace by a turning chute. Due to the difference in particle size and density, segregation of the blast furnace raw material also occurs in the furnace top hopper. The blast furnace raw material is charged into the furnace without sufficiently mixing different types of raw materials at the timing of discharge from the furnace top hopper due to the difference in particle size and density.

When discharged from the furnace top hopper and charged into the furnace by a swivel chute, segregation of the raw material occurs in the radial direction of the furnace due to the difference in the particle size and density of the raw material.
Therefore, it is important to control (1) and (2) above, that is, the O / C distribution and the particle size distribution in the radial direction in consideration of the respective particle sizes and densities corresponding to the types of blast furnace charging materials. is there.

  On the other hand, the top hopper of a bell-less blast furnace is generally arranged in parallel and has a hopper structure in which the discharge port is eccentric from the hopper center. This eccentric hopper structure needs to cope with the above-mentioned because the material segregation at the time of discharging is promoted as compared with the concentric hopper.

  In the raw material charging method in which the raw material to be supplied to the blast furnace is charged so that the coke layer and the coke mixed ore layer are alternately deposited, the particle size of the coke mixed in the coke mixed ore layer is set as follows. The relative ore ratio value is set within a range of 0.8 to 1.2 in the entire radial direction in the furnace within a range of 1.1 to less than 1.4 times the particle size, and The coke mixed ore layer is deposited such that the proportion of the coke in the coke mixed ore layer is 10 vol% or more in volume ratio, and the average layer thickness in the furnace portion of the coke mixed ore layer is 400 mm or more. There is a description of a method for charging raw materials into a blast furnace (Patent Document 1).

  In a bell-less blast furnace with a center-feed type bell-less furnace top charging device in which an upper bunker and a lower bunker are arranged in two upper and lower stages, raw materials are charged from the top of the furnace and coke layers and coke mixed ore layers are alternately deposited. In order to form the coke mixed ore layer, the particle size of coke mixed in the coke mixed ore layer is 1.3 times or more the particle size of the ore when performing the raw material charging to be performed, After charging the upper bunker with ore and subsequently charging the ore and coke, the raw material in the upper bunker is charged into the lower bunker, and the raw material discharged from the lower bunker is passed through a turning chute. There is a description of a raw material charging method into a bell-less blast furnace, characterized in that it is charged into a blast furnace (Patent Document 2).

  Also, in a bellless blast furnace having a center-feed type bellless furnace top charging device in which an upper bunker and a lower bunker are arranged in two stages, a coke layer and a coke mixed ore layer are alternately loaded from the top of the furnace. And the coke mixed ore layer is mixed with the coke mixed ore layer, the particle size of the coke is 0.2 times or more than the particle size of the lump coke charged as the coke layer, and In order to form a coke mixed ore layer with a particle size of less than 1.3 times the ore particle size, ore and coke are charged in the upper bunker, and then the upper A material charging method for a bell-less blast furnace, characterized in that a raw material in a bunker is charged into the lower bunker, and a raw material discharged from the lower bunker is charged into a blast furnace through a turning chute. Is (Patent Document 3).

Japanese Patent No. 4770222 JP 2010-133008 A JP 2010-215949 A

The inventions described in Patent Documents 1 to 3 relating to mixed charging of ore and coke having different particle sizes and densities have the following problems. That is,
According to Patent Document 1, the coke mixed ore layer makes the relative ore ratio in the furnace radial direction uniform if the particle size of the coke is within a range of 1.1 to less than 1.4 times the particle size of the ore. Suppose you can.
However, the blast furnace charge distribution varies depending on the charging device and the charging method, there is no description of the charging device and the charging method, and there is a problem that the scope of application of the document is unclear. .

The description of Patent Document 2 sets the particle size of the mixed coke to 1.3 times or more of the particle size of the ore, and the description of Patent Document 3 sets the particle size of the mixed coke to the particle size of the lump coke. Compared to 0.2 times or more and less than 1.3 times the particle size of the ore, the mixture discharged from the top bunker is added to the top bunker by first adding the ore and then the mixed coke. This is to reduce the fluctuation of the coke ratio.
However, the ratio of the mixed coke discharged from the furnace top bunker varies depending on the charging device and the charging method. Patent Documents 2 and 3 both describe the center-feed type bellless furnace top charging device. There is a problem of being limited.

  The subject of the present invention is to reduce the variation in discharge of the charge from the eccentric type top hopper when charging the blast furnace charge having different particle size and density of the raw material in the bell-less blast furnace, A blast furnace raw material charging device and a blast furnace raw material charging method for controlling the distribution of radial charges.

  In the eccentric hopper top of a bell-less blast furnace, the present inventors analyzed the characteristics of the deposit accumulation when charging various brands of blast furnace charges with different particle sizes and densities. Investigation was performed using a 1/20 scale test apparatus. As a result, it was found that by controlling the damper angle at the entrance and the lower part of the eccentric type furnace top hopper, the raw materials can be uniformly mixed and charged into the furnace. The present invention is based on these findings.

The gist of the present invention is as follows.
(1) A raw material charging device for a bell-less blast furnace having a charging belt conveyor, a furnace top hopper and a turning chute,
The furnace top hopper is an eccentric type furnace top hopper,
At the top of the eccentric type furnace top hopper, there is an upper damper capable of adjusting the angle with respect to the vertical line ,
A bellless blast furnace raw material charging apparatus comprising a lower damper capable of adjusting an angle with respect to a vertical line at a lower portion of the eccentric type furnace top hopper.
(2) The raw material of the bell-less blast furnace in which the blast furnace charging raw material transported by the charging belt conveyor is temporarily stored in the furnace top hopper, and the blast furnace charging raw material discharged from the furnace top hopper is charged into the blast furnace by a turning chute. A charging method,
Using an eccentric type furnace top hopper as the furnace top hopper,
A step of controlling the raw material charging position from the charging conveyor to the eccentric type furnace top hopper using an upper damper,
A method for charging a raw material in a bell-less blast furnace, wherein a step of controlling a raw material discharge order from the eccentric type furnace top hopper using a lower damper is performed.
(3) In the step (2), the step of controlling the raw material charging position to the eccentric type furnace top hopper using the upper damper supplies the raw material to the center part of the eccentric type furnace top hopper. The raw material charging method for the described bell-less blast furnace.
(4) The step of controlling the raw material discharge order from the eccentric type furnace top hopper using a lower damper delays the discharge of the raw material at the center of the eccentric type top hopper (2 ) Or the raw material charging method for the bell-less blast furnace according to (3).

  In the bell-less blast furnace, when charging a blast furnace charge having different particle sizes and densities of raw materials, the variation in discharge of the charge from the eccentric type top hopper is reduced, and the furnace radial direction It is possible to control the distribution of charges.

The blast furnace feed transportation system is shown. An eccentric furnace top hopper of 1/20 model is shown. The raw material charging method to an eccentric type furnace top hopper of 1/20 model is shown. The deviation at the discharge of sintered ore from the 1/20 model eccentric type top hopper is shown. The deviation at the time of discharging alumina from the eccentric hopper top of the 1/20 model is shown. The deviation at the time of discharge of coke from the eccentric type top hopper of 1/20 model is shown. The deviation at the time of discharge from the eccentric hopper top of the 1/20 model is shown.

(About eccentric type furnace top hopper)
Fig. 1 shows the material transport system for the blast furnace. The ore or coke is weighed from the ore tank 1 or the coke tank 2, cut out, and charged into the surge hopper 4 by the transport conveyor 3. Thereafter, the charged material is temporarily stored in the furnace top hopper 6 by the charging conveyor 5 and then charged into the blast furnace 8 by the turning chute 7 according to the charging command.

Here, the furnace top hopper 6 is a hopper for temporarily storing a charge that is weighed for each brand and ready for charging and waiting for a charging command to the blast furnace. In general, two types of top hoppers are installed so that the blast furnace command can be met. The structure of the hopper is generally an eccentric type top hopper in which the discharge port is brought as close as possible to the blast furnace shaft core side and the hopper center and the discharge port of the hopper are eccentric.

  When ore is charged into the furnace hopper 6 by the charging belt conveyor 5, the fine ore stays at the dropping point, but the coarse ore rolls down to the side wall of the furnace hopper 6 and segregates in the hopper. To do. When cutting from the top hopper, the fine ore just above the discharge port is discharged first, and the coarse ore brand on the side wall of the top hopper is discharged with a delay. As a result, the raw material charged into the blast furnace changes in time series depending on the brand and particle size, which makes it difficult to control the distribution of the blast furnace charge.

(Experiment with an eccentric top hopper of 1/20 model)
The present inventor conducted a segregation experiment of the charged material by a 1/20 model eccentric type top hopper.
Fig. 2 shows an eccentric type top hopper of 1/20 model. The center of the eccentric type furnace top hopper and the center of the hopper discharge port are eccentric by 80 mm. An upper damper 9 was installed at the upper part of the eccentric type furnace top hopper, and a lower damper 10 was installed at the lower part. The upper damper 9 is a segregation control device that collides with the ore falling into the hopper from the raw material conveyor and changes the falling position of the ore. The lower damper 10 is a segregation control device that is above the discharge port and changes the flow of ore from the hopper.
Table 1 shows the raw materials used in the experiment. For each raw material, a raw material having the same particle size as that of the raw material used in the actual furnace was used, and the pellets were substituted with alumina spheres having relatively close densities and shapes. The actual furnace OB (ore layer thickness) was assumed to be 115 t / charge, the pellet ratio was 9.8%, and the small coke ratio was 3.7% (35 kg / t).

  FIG. 3 shows a raw material charging method to an eccentric type furnace top hopper of a 1/20 model. Two batches of ore were charged, and alumina, fine sinter, coarse sinter, and small coke were placed in this order on the raw material conveyor, and the small coke was deposited to a length of 36% from the beginning.

(Experimental result)
Fig. 4 shows the deviation during discharge of sintered ore from the eccentric hopper top of the 1/20 model. The horizontal axis indicates the relative discharge time when the total discharge time is 1. The vertical axis represents the relative average particle size of the sintered ore when the average particle size of the sintered ore is 1. A thin line is a case where the upper damper 9 and the lower damper 10 are not installed, and a broken line is a case where the upper damper 9 is installed, its angle is + 10 °, and the lower damper 10 is not installed. A thick line is a case where the angle of the upper damper 9 is + 10 ° and the angle of the lower damper 10 is −20 °. Here, the angle of the upper damper 9 is + 10 ° is a case where the angle of the upper damper 9 is set to 10 ° with respect to the vertical line so as to receive the ore with respect to the ore flow from the raw material conveyor ( Figure 2). Moreover, the angle of the lower damper 10 being −20 ° is a case where the angle of the lower damper 10 is set to 20 ° on the opposite side of the vertical line from the upper damper 9 (FIG. 2).

  The time-series segregation of the relative average particle size of the sintered ore discharged from the eccentric type top hopper is the smallest in the thick line with the upper damper 9 angle + 10 ° and the lower damper 10 angle −20 °. Was the case. Here, when the angle of the upper damper 9 was set to + 10 °, the ore falling from the raw material conveyor into the hopper collided with the upper damper 9 and dropped to a position substantially in the center of the furnace top hopper. Moreover, when the angle of the lower damper 10 was −20 °, the discharge of the raw material immediately above the discharge port was hindered, and the funnel flow was suppressed.

  FIG. 5 shows the deviation at the time of discharging alumina from the eccentric hopper top of the 1/20 model. FIG. 6 shows the deviation at the time of discharging the small coke from the eccentric top hopper of the 1/20 model. The deviation at the time of discharge of alumina and small coke was the smallest in the case of a thick line in which the angle of the upper damper 9 was + 10 ° and the angle of the lower damper 10 was −20 °.

The angle of the upper damper 9 of the eccentric furnace top hopper of 1/20 model is changed to -40 ° + 10 °, + 40 °, and when the lower damper 10 is not present and the angle of the lower damper 10 is -40 °, -20 ° , 0 °, + 20 °, and + 40 °. FIG. 7 shows the standard deviation of the relative average particle diameter of the sintered ore and the standard deviation of the alumina weight at the time of discharge. When the angle of the upper damper 9 was + 10 ° and the angle of the lower damper 10 was −20 °, the standard deviation of the relative average particle diameter of the sintered ore and the standard deviation of the alumina weight at the time of discharge were the smallest.
When the angle of the upper damper 9 was set to + 10 °, the ore falling from the raw material conveyor into the hopper collided with the upper damper 9 and dropped to a position approximately at the center of the furnace top hopper. It was confirmed that the raw material segregation in the blast furnace can be reduced by feeding the raw material into the central part of the eccentric type top hopper by controlling the upper dumper. Moreover, when the angle of the lower damper 10 was −20 °, the discharge of the raw material immediately above the discharge port was hindered, and the funnel flow was suppressed. It was confirmed that the material segregation in the blast furnace can be reduced by delaying the discharge of the material at the center of the eccentric type top hopper.

  In the bell-less blast furnace, when charging a blast furnace charge having different particle sizes and densities of raw materials, the variation in discharge of the charge from the eccentric type top hopper is reduced, and the furnace radial direction It can be used to control the distribution of charges.

DESCRIPTION OF SYMBOLS 1 ... Ore tank, 2 ... Coke tank, 3 ... Transport conveyor, 4 ... Surge hopper, 5 ... Charge conveyor, 6 ... Furnace top hopper, 7 ... Swirling chute, 8 ... Blast furnace, 9 ... Upper damper, 10 ... Lower damper .

Claims (4)

A raw material charging device for a bell-less blast furnace having a charging belt conveyor, a furnace top hopper and a turning chute,
The furnace top hopper is an eccentric type furnace top hopper,
At the top of the eccentric type furnace top hopper, there is an upper damper capable of adjusting the angle with respect to the vertical line ,
A bellless blast furnace raw material charging apparatus comprising a lower damper capable of adjusting an angle with respect to a vertical line at a lower portion of the eccentric type furnace top hopper. A raw material charging method for a bell-less blast furnace, in which a blast furnace charging raw material transported by a charging belt conveyor is temporarily stored in a furnace top hopper, and the blast furnace charging raw material discharged from the furnace top hopper is charged into a blast furnace by a turning chute. Because
Using an eccentric type furnace top hopper as the furnace top hopper,
A step of controlling the raw material charging position from the charging conveyor to the eccentric type furnace top hopper using an upper damper,
A method for charging a raw material in a bell-less blast furnace, wherein a step of controlling a raw material discharge order from the eccentric type furnace top hopper using a lower damper is performed.   The bellless according to claim 2, wherein the step of controlling the raw material charging position to the eccentric type furnace top hopper using an upper damper feeds the raw material to the center of the eccentric type furnace top hopper. Raw material charging method for blast furnace.   The step of controlling the raw material discharge order from the eccentric type furnace top hopper using a lower damper delays the discharge of the raw material at the center of the eccentric type top hopper. Item 4. A raw material charging method for a bell-less blast furnace according to item 3.