JP2009062576A - Method and apparatus for charging raw material into blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and an apparatus for charging raw materials into a blast furnace with which in a bell-less blast furnace having swinging chute, an ore layer thickness ratio is lowered in only narrow range near the furnace wall part, and in this way, gas flowing amount in only narrow range near the furnace wall part is increased and a gas utilizing rate to the whole blast furnace can be improved and also, the environmental gas flowing amount can be controlled. <P>SOLUTION: The method for charging the raw materials into the blast furnace, is performed as the followings, that when the raw materials are charged into the blast furnace by using the bell-less charging apparatus having the swinging chute, the raw materials are charged into near the furnace wall in the blast furnace under state that becomes cokes at the upper part and ores at the lower part in the swinging chute. Further, the apparatus for charging the raw materials into the blast furnace, has a furnace top bunkers 1,2 and a vertical chute 4, and a collecting hopper 3 for charging the raw materials into the swinging chute 5 through the vertical chute 4 by receiving the raw materials dropped down from the furnace top bunkers 1,2 and an auxiliary bunker 7, and the discharging hole of the auxiliary bunker 7 is positioned on the center axis of the vertical chute 4 in the collecting hopper 3. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a blast furnace raw material charging method in a bellless blast furnace having a bellless charging apparatus, and more particularly to a raw material charging method and a raw material charging apparatus into a blast furnace suitable for controlling a gas flow in the vicinity of a furnace wall.

  The blast furnace is a huge counter-current moving bed reactor, and proper charge lowering and gas flow control in the furnace are important for stable operation. On the other hand, especially in recent years, from the viewpoint of environmental problems, blast furnace operation is directed to low-reducing material ratio operation, but in this case, the reduction of coke ratio increases the airflow resistance in the furnace and passes through the furnace. The amount of gas to be reduced decreases, and the furnace top temperature decreases. It is known that when the furnace top temperature decreases, the furnace wall temperature decreases, making it difficult for zinc to be discharged outside the furnace, and zinc adheres to the furnace wall and forms a furnace wall deposit. If the amount of the deposit on the furnace wall becomes excessive, there is a problem that the stable operation is hindered due to the instability of the charge drop due to the disturbance of the furnace wall profile and the increase of the gas flow velocity accompanying the reduction of the effective cross-sectional area. Furthermore, if the furnace wall deposits peel and fall and reach the lower part of the furnace, the furnace heat may decrease, causing serious troubles such as cooling.

  Therefore, especially during operation with a low reductant ratio, the adhesion of zinc to the furnace wall is suppressed, and the gas flow in the vicinity of the furnace wall is increased to prevent the furnace wall from lowering temperature in order to promote the discharge to the outside of the furnace. It is important to do. Generally, the ventilation resistance is small at a portion where the ratio of ore layer thickness / coke layer thickness in the blast furnace (hereinafter referred to as ore layer thickness ratio) is small, and gas tends to flow easily. Therefore, conventionally, coke is concentrated in the vicinity of the furnace wall portion to ensure the air permeability of the furnace wall portion.

  However, in order to reduce the ore layer thickness ratio in order to reduce the ventilation resistance in the vicinity of the furnace wall, when the coke charging position in the furnace is concentrated in the vicinity of the furnace wall, in the normal method, in the vicinity of the furnace wall It is not possible to independently control only a narrow range, and the ore layer thickness ratio in a wide range around the furnace wall is lowered. As a result, the gas utilization rate of the entire blast furnace decreases, and the amount of coke used increases. Therefore, it is important to reduce the ore layer thickness ratio only in a very narrow region near the furnace wall.

  As a raw material charging device for charging raw materials into a blast furnace, a bell type was widely adopted, but instead of a bell type, a furnace without a bell provided with a turning chute in the furnace A top charging device has been developed and used, and is called a bellless charging device.

  The bell-less charging device has a “parallel hopper type” with raw material hoppers (top bunker) installed in parallel and a raw material hopper in two upper and lower stages, and a port from the upper hopper to the lower hopper. It is known that there is a “center feed type” in which materials are supplied via the like.

  Even when charging the raw material using such a bell-less charging device, when depositing the charge, the angle of repose of coke and ore becomes the factor that determines the shape of the deposit, and the shape of the deposit exceeds the angle of repose. It is difficult to make the ore layer thickness ratio only in a very narrow region near the furnace wall.

When the raw material is charged using the bell-less charging device, a gas flow near the furnace wall in the blast furnace is provided by arranging a cylindrical member along the outer periphery of the furnace port on the raw material charging deposition surface at the top of the blast furnace. A method of independently controlling only the above has been proposed (for example, see Patent Document 1).
JP 2005-314771 A

  With the method described in Patent Document 1, due to the presence of the cylindrical member, the deposition shape of the raw material is not affected by the angle of repose, and the ore layer thickness ratio can be reduced only in a very narrow region near the furnace wall. However, since the range of the area where the peripheral gas flow rate can be increased is determined by the location where the cylindrical member is installed, when changing the operating conditions, the size of the cylindrical member should be changed to match the required gas flow rate. There is a problem that the degree of freedom in controlling the peripheral gas flow rate is small.

  Therefore, the object of the present invention is to solve such a problem of the prior art and reduce the ore layer thickness ratio of only a narrow region near the furnace wall in the bell-less blast furnace having the swivel chute, thereby To provide a raw material charging method and a raw material charging device for a blast furnace that can increase the gas flow rate only in a narrow region, improve the gas utilization rate of the entire blast furnace, and control the peripheral gas flow rate. .

  Another object of the present invention is to provide a raw material charging method and a raw material charging apparatus for a blast furnace capable of continuing a stable operation especially during operation with a low reducing material ratio by controlling the gas flow rate in the vicinity of the furnace wall. There is to do.

The features of the present invention for solving such problems are as follows.
(1) When charging raw materials into a blast furnace using a bellless charging device having a swivel chute, the raw material is placed near the furnace wall of the blast furnace in a state where the upper part is coke and the lower part is ore in the swirl chute. A raw material charging method for a blast furnace, characterized by charging.
(2) The material is characterized in that the material falling radius position (Rf) from the turning chute is 0.8 to 1.0 in a dimensionless radius (Rf / R0) that is dimensionless by the furnace radius (R0). The raw material charging method to the blast furnace as described in (1).
(3) A raw material charging device used in the raw material charging method for a blast furnace according to (1) or (2), wherein the bell-less charging device has a plurality of furnace top bunker and a vertical chute at the bottom. A collecting hopper for receiving the material falling from the furnace top bunker and charging the material into the swivel chute via the vertical chute, and an auxiliary bunker, and the discharge port of the auxiliary bunker is located in the collecting hopper A raw material charging apparatus for a blast furnace, which is located on a central axis of a vertical chute.

  According to the present invention, coke can be deposited only in a narrow region near the furnace wall, the ore layer thickness ratio of only the narrow region near the furnace wall is reduced, and only the gas flow rate near the furnace wall is independent. Can be increased. In addition, since a high gas flow rate can be secured stably only in the vicinity of the furnace wall, a high gas utilization rate can be achieved in other regions. Therefore, the gas utilization rate in the whole blast furnace can be improved, and thereby the amount of coke used can be reduced.

  In the present invention, when a raw material is charged into a blast furnace using a bell-less charging device having a swirl chute, the raw material is placed near the furnace wall of the blast furnace so that the upper part in the swirl chute is coke and the lower part is ore. Insert. The upper raw material in the swivel chute falls to the furnace wall side, and the lower raw material falls closer to the furnace center, but the flow of the raw material on the furnace wall side toward the furnace center is due to the presence of the raw material that has dropped closer to the furnace center. It is suppressed. That is, the flow according to the angle of repose of the coke charged to the furnace wall side is suppressed, and the coke can be deposited in a narrow region on the furnace wall side.

  In addition, as coke which is a raw material of the upper part in a rotation chute | shoot here, it is desirable to use coke normally charged from the top of a furnace, such as lump coke, small and medium lump coke, and iron interior type coke.

  The material dropping position from the turning chute is a dimensionless radius (Rf / R0) in which the material falling radius position (Rf) on the material charging surface in the blast furnace is made dimensionless by the furnace radius (R0). It is preferable that it is 0.8-1.0.

  In order to charge the raw material near the furnace wall of the blast furnace with the upper part in the swivel chute being coke and the lower part being ore as described above, in the bell-less blast furnace having the bell-less charging device, from the top of the blast furnace When charging ore and coke into the blast furnace, the bell-less charging device has a plurality of furnace top bunker and vertical chutes at the bottom, swivels through the vertical chutes receiving raw material falling from the furnace bunker It is possible to use a collecting hopper for charging raw materials into the chute and an auxiliary bunker, in which the discharge port of the auxiliary bunker is located on the central axis of the vertical chute in the collecting hopper.

  When using the bell-less charging device with the above-mentioned auxiliary bunker, when ore is charged from the top bunker into the collecting hopper, the auxiliary bunker is used at the same time as ore charging or during charging of the ore into the furnace. The coke is put on the central axis of the vertical chute in the collecting hopper, charging into the blast furnace is started via the turning chute, and the charging of the coke from the auxiliary bunker is completed by the end of the ore charging. Thereby, the raw material can be charged into the blast furnace in such a state that the upper part in the turning chute is coke and the lower part is ore. In other words, the charge from the top bunker (ore ore) is passed through a turning chute using a charging system different from the top bunker used for normal charging. At the same time, it is charged into the blast furnace periphery.

  A part of the coke charged from the top of the furnace is charged using a charging system that is different from the furnace top bunker used for normal charging. At the same time, it can be charged to the blast furnace periphery, and the coke is deposited only in the narrow area near the furnace wall, so the ore layer thickness ratio in only the narrow area near the furnace wall is reduced, and the Only the gas flow rate can be increased independently. In addition, since a high gas flow rate can be secured stably only in the vicinity of the furnace wall, a high gas utilization rate can be achieved in other regions. Thereby, since the gas utilization rate in the whole blast furnace can be improved, the amount of coke used can be reduced.

An experiment for confirming the effect of the present invention was conducted using a 1/18 scale model of a 5,000 m ³ blast furnace. 1 and 2 are schematic diagrams of the experimental apparatus used. FIG. 1 shows a case where the furnace top charging device (bellless charging device) of the present invention having an auxiliary bunker as a charging device from another system is used, and FIG. 2 shows a conventional furnace top charging device (bellless charging device). This is a case of using an input device.

  A conventional raw material charging method in the case of using the apparatus of FIG. 2 will be described. In the conventional method, coke and ore are charged separately. For example, coke is charged into the furnace top bunker 1, ore is charged into the furnace top bunker 2, and the ports installed at the bottom of the furnace top bunker 1 and 2 are opened and closed. Then, the coke or ore is charged into the collecting hopper 3, and the raw material is charged into the blast furnace 6 by the turning chute 5 through the vertical chute 4. After the charge is charged into the furnace, it flows from the charged position to the inside of the furnace and accumulates. Therefore, it is difficult to concentrate coke only in the vicinity of the furnace wall. FIG. 3 shows the state of coke deposition when the conventional raw material charging method of FIG. 2 is used. According to FIG. 3, the coke a charged into the blast furnace from the turning chute is accumulated in a wide area b on the furnace wall 8 side.

  On the other hand, in the present invention, coke and ore can be charged simultaneously by using an auxiliary bunker 7 which is a charging device from another system as shown in FIG. That is, when ore is charged, coke is segregated to the upper part of the ore in the turning chute 5 by the auxiliary bunker 7, so that the coke is charged to the furnace wall side and is deposited in the vicinity of the furnace wall as it is. FIG. 4 shows the state of deposition when the raw material charging method of the present invention using the apparatus of FIG. 1 is used. According to FIG. 4, since ore c, which is the original charging raw material, is deposited inside the furnace of coke a, it is suppressed that coke a charged by auxiliary bunker 7 flows into the furnace, and the furnace wall portion It is possible to intensively deposit in a narrow area d on the furnace wall side only in the vicinity.

  As an experiment using a scale model, the relationship between the falling radius position (Rf) of the charged raw material and the deposition width (t) of the dropped raw material was examined. By changing the angle of the turning chute, the dropping position into the furnace was set to a dimensionless radius of 0.7, 0.8, and 0.9, and the raw material was charged 6 turns at the set dropping position. After charging, the model was cut in half and the cross section was observed to measure the coke deposit width in the radial direction. In the conventional method using the raw material charging apparatus shown in FIG. 2, the ore was charged 6 turns after the coke was charged 6 turns. In the method of the present invention using the raw material charging apparatus shown in FIG. 2, the charging of coke was started by the auxiliary bunker simultaneously with the timing of charging the ore, and charging was completed after charging 6 turns. FIG. 5 shows the relationship between the drop position (Rf / R0) indicated by the dimensionless radius made non-dimensional with the furnace radius (R0) and the deposition width (t / R0) indicated by the dimensionless radius in the model experiment.

  According to FIG. 5, the effect of reducing the deposition width by the method of the present invention compared to the conventional method is that the charge drop position on the charging surface when charging into the furnace is a dimensionless radius of 0.8 or more. And the effect becomes remarkable. When loaded into a drop position with a dimensionless radius of less than 0.8, there is no difference in the deposition width between the conventional method and the method of the present invention, and the charge is placed because the drop position is inside the furnace. It is possible to deposit a wide range from the furnace wall and to concentrate coke in the vicinity of the furnace wall. Therefore, when carrying out the method of the present invention using the auxiliary bunker, it is desirable to charge the furnace wall side as much as possible, and the charging should be performed at a dimensionless radius of 0.8 to 1.0. Is preferred.

  As an experiment using a scale model, the wind speed at each radial position (r) in the furnace was measured. The measurement results are shown in FIGS. In the conventional method shown in FIG. 6, the ore is charged three times at a tilt angle at which the dimensionless radius (r / R0) of the coke dropping position is 0.85, and after completion, the ore is charged with a dimensionless radius of 0.85. After charging 3 turns, the inside of the furnace was charged sequentially. In the method of the present invention shown in FIG. 7, at the same time when charging starts at an inclination angle at which the dimensionless radius of the ore falling position is 0.85, the coke is charged 3 turns by the auxiliary bunker, and even after the completion of charging the coke. The ore was continuously charged into the furnace as it was.

  Compared with the conventional method shown in FIG. 6, in the method of the present invention shown in FIG. 7, although there is almost no difference in the wind speed from the central part to the intermediate part, the wind speed is increased particularly in the vicinity of the furnace wall part. Thereby, since the area | region where a gas utilization factor is low can be controlled to the narrow area | region near a furnace wall part, it turns out that the gas utilization factor of the whole blast furnace can be improved.

  Examples of the present invention will be described below.

Here, an example is shown in which the present invention is applied to a blast furnace that operates at an internal volume of 5000 m ³ , a coke ratio of 370 kg / t, a pulverized coal injection amount of 130 kg / t, and a reducing material ratio of 500 kg / t. Using a bell-less charging device with an auxiliary bunker, similar to that shown in FIG. 1, when charging ore with a turning chute, charging starts at an inclination angle with a dimensionless radius of 0.85 at the ore falling position At the same time, 3 turns of coke was charged from the auxiliary bunker, and the ore was charged into the furnace as it was after the completion of coke charging. Table 1 shows the operation specifications with the case of the conventional operation not using the auxiliary bunker as a conventional example, and the case where the above-described charging method of the present invention is applied as an example of the present invention.

  In FIG. 5, the measurement result of the gas utilization rate in the radial position (dimensionalless radius: r / R0) of the blast furnace of a prior art example and the example of this invention is shown. Compared to the conventional example, in the case of the present invention example, the region where the gas utilization rate in the vicinity of the furnace wall (r / R0≈1.0) is reduced is reduced. As a result, the gas utilization rate of the entire blast furnace was improved, and the coke ratio and reducing material ratio could be reduced.

The schematic diagram of the experimental apparatus (furnace top charging apparatus which has the charging apparatus from another system | strain) used by this invention. The schematic diagram of the experimental apparatus (conventional method furnace top charging apparatus) used by this invention. Schematic diagram of coke accumulation (conventional method). Schematic diagram of the state of coke deposition (method of the present invention). The graph which shows the relationship between the fall position of a raw material, and the deposition width. Graph showing the relationship between the radial position of the blast furnace and the wind speed (conventional method). The graph which shows the relationship between the radial position of a blast furnace, and a wind speed (invention method). The graph which shows the relationship between the radial position of a blast furnace and a gas utilization factor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace top bunker 2 Furnace top bunker 3 Collective hopper 4 Vertical chute 5 Turning chute 6 Blast furnace 7 Auxiliary bunker 8 Furnace wall a Coke b Wide area c Ore d Narrow area on the furnace wall side

Claims (3)

  When charging raw materials into a blast furnace using a bell-less charging device with a swivel chute, the raw material is charged near the furnace wall of the blast furnace so that the upper part is coke and the lower part is ore inside the swirl chute. A method for charging raw materials into a blast furnace.   2. The raw material fall radius position (Rf) from the turning chute is 0.8 to 1.0 as a dimensionless radius (Rf / R0) made dimensionless by the furnace radius (R0). The raw material charging method to the blast furnace as described in 1.   The raw material charging apparatus used in the raw material charging method to the blast furnace according to claim 1 or 2, wherein the bell-less charging apparatus has a plurality of furnace top bunkers and a vertical chute at the bottom, A collecting hopper that receives the material falling from the top bunker and charges the swivel chute through the vertical chute, and an auxiliary bunker, and the discharge port of the auxiliary bunker is the outlet of the vertical chute in the collecting hopper A raw material charging device for a blast furnace, which is located on a central axis.

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