JP2005060797A - Method for charging material to blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for charging a material to a blast furnace equipped with bell-less charging equipment, wherein material deposition configuration can be precisely controlled in the radial direction of the furnace to decrease fluctuation in the material deposition configuration in the radial direction of the furnace. <P>SOLUTION: A deposition layer of a single batch of the material is formed in the furnace by setting the amount of material charge per turn of a charging chute according to the tilting angle of the charging cute. Here, the amount of the material charge per turn of the charging chute is changed according to the tilting angle of the charging chute at least once during the charging of a single batch. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a raw material charging method for a blast furnace equipped with a bell-less charging device.

  FIG. 1 shows a schematic diagram of the top of a blast furnace equipped with a bell-less charging device.

  This blast furnace has a swivelable charging chute 3 in the upper part of the furnace body 1, and has a vertical chute 4, a collecting hopper 5, a flow control gate 6, a furnace top bunker 7 and the like at the top of the furnace. One or a plurality of blast furnace top bunkers 7 equipped with such a charging device are disposed in the furnace body 1, and one batch or a plurality of furnace top bunkers 7 have one batch of coke or ore. And other raw materials.

  Raw materials such as coke and ore are discharged from the lower part of the furnace top bunker 7 and flow on the swirling charging chute 3 via the raw material charging passage including the flow control gate 6, the collecting hopper 5, the vertical chute 4 and the like. A raw material deposition layer is formed in the furnace by charging into the furnace.

  By the way, in order to charge one batch of raw material into the furnace, the upper seal valve 8A installed above the furnace top bunker 7 and the raw material charging passage between the flow control gate 6 and the collecting hopper 5 were installed. The lower seal valve 8B is appropriately operated. A series of operations for charging one batch of raw materials into the furnace, including such operations, is hereinafter referred to as one batch raw material charging operation. Generally, the raw material charging into the blast furnace is executed in units of the above-described one-batch raw material charging operation.

  In FIG. 1, the code | symbol 9 shows the flow of the raw material charged into the furnace from the charging chute 3 set to tilting angle (theta). Reference numeral 10 indicates the in-furnace raw material deposition surface before the one-batch raw material charging operation, and r indicates the position in the furnace radial direction starting from the furnace center.

  In the above one-batch raw material charging operation, the raw material for one batch is charged so that the charging chute 3 is charged into the furnace while turning a predetermined number of times according to the type of raw material. The opening degree of the flow control gate 6 is adjusted for each type. At that time, the number of turns of the charging chute 3 per unit time (hereinafter also referred to as charging chute rotation speed B (turning / min)) is made constant.

  In addition, the number of turns of the charging chute is counted from the start of charging, and the tilt angle θ of the charging chute is set in advance for each turn. As shown in Table 1, the tilt angle θ of the charging chute corresponds to the charging position on a one-to-one basis, so that each raw material is set in advance for each rotation of the charging chute from the charging start time. It is intended to form the same raw material accumulation shape for each raw material every time in the furnace by charging at the charged position. The transition of the charging position for each turn of the charging chute from the starting point of the charging chute is called a charging pattern.

つまり、従来の高炉への原料装入方法では、１バッチ原料装入操作中、すなわち、装入開始時から装入終了時までの全旋回にわたり、流調ゲート６の開度が１バッチ分の原料に応じて決めた所定値に設定され、装入シュートから流下する、単位時間当たりの原料流下量Ａ（ｔ／ｍｉｎ）を一定とするようにされ、炉周方向の原料堆積形状の変動を抑制している。

That is, in the conventional raw material charging method to the blast furnace, the opening degree of the flow control gate 6 is equivalent to one batch during one batch raw material charging operation, that is, over the entire turn from the start of charging to the end of charging. It is set to a predetermined value determined according to the raw material, the raw material flow amount A (t / min) per unit time flowing down from the charging chute is made constant, and the fluctuation of the raw material deposition shape in the furnace circumferential direction is controlled. Suppressed.

  Here, in the operation of the blast furnace, keeping the gas flow in the furnace constant leads to a stable operation, so that the raw material deposition layer in the furnace is required to have a predetermined deposition shape.

For example, as a raw material charging method to the blast furnace, by changing the tilt angle θ in a predetermined direction for each turn of the charging chute, fluctuation of the ratio of ore layer thickness / coke layer thickness and fluctuation of gas flow in the furnace Have been proposed (Patent Documents 1 and 2).
Japanese Patent Laid-Open No. 2001-140009 JP 2001-262207 A

  However, in the above-described conventional raw material charging method to the blast furnace, it is difficult to finely control the raw material deposition shape in the furnace radial direction due to the following problems.

  Problems in the conventional raw material charging method for a blast furnace will be described with reference to FIG.

  FIG. 2 is a schematic diagram showing a deposition shape of one batch of the raw material deposition layer 11 when one batch of raw material charging operation is executed by a conventional raw material charging method into a blast furnace. In FIG. 2, reference numerals 11 </ b> A and 11 </ b> B indicate ring-shaped deposits formed by turning the charging chute 1. When the tilt angle θ is set large, a ring-shaped deposit 11A on the furnace wall side is formed, and when the tilt angle θ is set small, a ring-shaped deposit 11B on the furnace center side is formed.

  Here, the tilting angle θ is an angle formed by the vertically downward direction and the flow direction of the raw material of the charging chute, and an angle θ formed by the furnace center lower side and the chute surface of the charging chute 3 in FIGS. The angle shown as.

  In the conventional raw material charging method to the blast furnace, the opening degree of the flow control gate 6 is set to a predetermined value determined according to the raw material for one batch during one batch raw material charging operation, The raw material charging amount (t / swivel) (hereinafter, the amount of raw material charged from the charging chute 3 is expressed by mass) is kept constant, and the charging chute rotation speed B (swing / min) is constant. 1 batch raw material charging operation is performed. That is, the raw material charging amount C (t / turn) per turn of the charging chute = the raw material flow rate A (t / min) / chute rotation speed B (turn / min) per unit time = constant, One batch raw material charging operation is performed with a charging pattern determined according to the raw material for the batch.

  Therefore, in the above-described conventional method of charging the raw material into the blast furnace, the opening degree of the flow control gate 6 is set to a predetermined value determined according to the raw material for one batch regardless of the tilt angle θ of the charging chute 3. The raw material charging amount per turn of the charging chute is kept constant.

  For this reason, when the ring-shaped deposit 11A formed on the furnace wall side by the raw material per turn of the charging chute is compared with the ring-shaped deposit 11B formed on the furnace center side, a ring is formed on the furnace wall side. The raw material is charged in a wide range because the ring diameter of the ring-shaped deposit 11B is large, and the material is deposited relatively thin, whereas the ring diameter of the ring-shaped deposit 11A is small and the ring circumference is short on the furnace center side. Since the same amount of raw material as the furnace wall side is charged, the material is deposited relatively thick. Therefore, as shown in FIG. 2, the longitudinal cross-sectional shape of the ring-shaped deposit formed by turning the charging chute 1 is different between the furnace center side and the furnace wall side.

  Therefore, in the conventional raw material charging method to the blast furnace, the charging chute is swiveled multiple times at the same tilt angle θ on the furnace wall side or the charging position change pitch is set small, while the furnace center portion Radius formed by one batch raw material charging operation by setting the charging position change pitch on the side and setting the charging pattern such as using the effect that the charged raw material flows in the furnace radial direction However, the conventional method of charging the raw material into the blast furnace is still different in the raw material deposition shape in the longitudinal section between the furnace center side and the furnace wall side. Therefore, it was difficult to further reduce the fluctuation of the material deposition shape in the furnace radial direction.

  The difference in the raw material deposition shape as seen in the longitudinal section between the furnace center side and the furnace wall side will be schematically described with reference to FIG. On the furnace wall side, there are many ring-shaped deposits per unit length in the radial direction of the furnace, and in this part, the variation in the thickness of the raw material deposition layer in the furnace radial direction is relatively small. The number of ring-shaped deposits existing per unit length in the direction is small, and the ring-shaped deposits having clear peaks are in the form of raw material deposits discretely existing in the furnace radial direction.

  When the next batch of raw material charging operation is performed on the raw material deposition surface as seen on the furnace center side, the layer thickness of the raw material deposition layer for one batch also greatly varies in the radial direction of the furnace. In some cases, the flow of gas in the furnace tends to become unstable, making it difficult to perform stable operation. Further, in the conventional raw material charging method to the blast furnace, it is difficult to finely control the raw material deposition shape in the radial direction of the furnace.

  The present invention is to solve the above-mentioned problems of the prior art, and it is possible to finely control the material deposition shape in the furnace radial direction and to reduce the fluctuation of the material deposition shape in the furnace radial direction. It aims at providing the raw material charging method to a blast furnace provided with a bell-less type charging device.

The present inventors have obtained the knowledge that the above-mentioned problems can be solved by reducing the longitudinal cross-sectional shape difference of ring-shaped deposits formed at different positions in the furnace radial direction, and have completed the present invention.
1. While turning the charging chute, each turn, holding the tilt angle of the charging chute at a set angle, charging the furnace through the charging chute and depositing the raw material in the furnace In the raw material charging method for forming a layer in a blast furnace equipped with a bell-less charging device, when forming a batch of the raw material accumulation layer in the furnace, the tilt angle of the charging chute is set to be vertically downward. When the angle formed by the flow direction of the raw material of the incoming chute is defined as W _i and W _j , respectively, θ _i <θ, where W _i and W _j are the raw material charging amounts per rotation of the charging chute at the tilt angle θ _i θ _j of the charging chute. _j
When W _i ≦ W _j
In addition, when the raw material for one batch is charged, the raw material charging amount per rotation of the charging chute is set so that the raw material charging amount per rotation of the charging chute is changed at least once. The raw material charging method to the blast furnace characterized by this.

  According to the present invention, the control of the material deposition shape in the furnace radial direction can be performed more finely, and the fluctuation of the material deposition shape in the furnace radial direction can be reduced. As a result, blast furnace operation can be stabilized and blast furnace charging raw material conditions can be relaxed.

  Hereinafter, the case where the present invention is applied to a blast furnace having a bell-less charging apparatus as shown in FIG. 3 will be described. 3 that are the same as those in FIGS. 1 and 2 are given the same reference numerals, and descriptions thereof are omitted.

  In the raw material charging method to the blast furnace of the present invention, the raw material charging amount per one turn of the charging chute at least once during the raw material charging operation for one batch, corresponding to the tilt angle θ of the charging chute 3. To change. In order to change the raw material charging amount per turning of the charging chute, the set value of the opening degree of the flow control gate 6 provided in the raw material charging passage extending from the lower part of the furnace top bunker 7 to the upper part of the collecting hopper 5 is changed. Can be done.

  More specifically, the opening degree of the flow adjustment gate is set so that the opening degree of the flow adjustment gate 6 becomes wider during one batch of raw material charging operation (also referred to as one batch raw material charging operation). If the set value is changed, the amount of the raw material passing through the flow control gate 6 can be increased, so that the raw material charging amount per one turn of the charging chute increases, and on the contrary, the opening degree of the flow control gate 6 is increased. If the set value of the opening of the flow adjustment gate is changed so as to be narrower, the amount of raw material passing through the flow adjustment gate 6 can be reduced, and the amount of raw material charged per turn of the charging chute can be reduced. Can do.

  Thus, in the raw material charging method to the blast furnace of the present invention, the raw material charging amount per one turn of the charging chute can be changed by changing the set value of the opening degree of the flow control gate 6. In addition, it is possible to change the raw material charging amount per turn of the charging chute at an appropriate number of times during one batch raw material charging operation, that is, without requiring large equipment modification. Therefore, it is preferable.

  For example, the tilt angle θ of the charging chute 3 is maintained at a preset angle for each turn, and the raw material is charged into the furnace via the charging chute 3 while turning the charging chute 3. The furnace top bunker 7 was weighed continuously with a load cell or the like during the one batch raw material charging operation for forming the raw material deposition layer therein, and detected at the timing of each turn of the charging chute. Since the raw material charge per turn of the charging chute can be obtained from the measured value of the weight loss of the flow, the opening value of the flow control gate is set so that the raw material charge per turn of the charging chute differs. Can be decided.

  Moreover, in the raw material charging method to the blast furnace of the present invention, the tilt angle for changing the raw material charging amount per one turn of the charging chute is determined in advance. This makes it possible to change the raw material charging amount per turn of the charging chute with a predetermined radial position in the furnace as a boundary. At that time, the setting value of the opening degree of the flow control gate is changed so that the amount of raw material charged per turn of the charging chute is smaller on the furnace center side than on the furnace wall side.

  However, even if the set value of the opening degree of the flow adjustment gate is the same, the amount of the raw material passing through the flow adjustment gate 6 varies depending on the raw material. Therefore, in setting the raw material charging amount per rotation of the charging chute corresponding to the tilt angle θ of the charging chute 3, depending on the type of raw material such as coke, ore or mixed raw material of coke and ore, Each determines the amount of change in the set value of the opening of the flow control gate.

  The raw material charging method to the blast furnace of the present invention corresponds to the tilt angle θ of the charging chute 3 when forming a batch of raw material deposition layer in the furnace, at least once during one batch raw material charging operation. Has changed the raw material charging amount per turn of the charging chute, so that the raw material charging amount per turn of the charging chute is smaller when the tilt angle θ is smaller than when the tilt angle θ is large. can do.

  For example, in the schematic view for explaining the raw material charging method of the present invention shown in FIG. 3, the furnace wall side from the furnace wall to the intermediate position P in the furnace radial direction, and the intermediate position P to the furnace center. When changing the raw material charge amount per turn of the charging chute on the furnace center side up to the furnace center side, it can be made smaller than the raw material charge amount per turn of the charging chute on the furnace wall side. . In this case, since the amount of raw material charged per turn of the charging chute is less on the furnace center side where the furnace circumference is shorter than on the furnace wall side where the furnace circumference is longer, at different positions in the radial direction of the furnace. The longitudinal cross-sectional shape difference of the ring-shaped deposition formed can be made small. As a result, the raw material charging method to the blast furnace according to the present invention can finely control the raw material deposition shape in the furnace radial direction as compared with the conventional method, so the fluctuation of the raw material deposition layer thickness in the furnace radial direction Can be reduced.

  In the present invention, as in the conventional case, when forming a batch of raw material deposition layer in the furnace, the tilt angle θ of the charging chute 3 is held at a preset angle for each turn, While turning the chute 3, the raw material is charged into the furnace through the charging chute 3, and a raw material deposition layer is formed in the furnace. For the raw material deposition layer for one batch, a charging position corresponding to the tilt angle θ of the charging chute 3 is set in advance, and a predetermined number of turns, for example, a charging pattern of about 5 to 20 times is set. Then, it can be formed by performing a one-batch raw material charging operation. At that time, in the present invention, the chute rotational speed B (turn / min) of the charging chute 3 is constant in the total number of turns.

  In FIG. 3, the code | symbol 12 shows the raw material deposition layer for 1 batch formed in the furnace by the raw material charging method of this invention mentioned above. Reference numerals 12A and 12B respectively denote a ring-shaped deposition on the furnace wall side and a ring-shaped deposition on the furnace center side formed by turning the charging chute 1.

  Referring to FIG. 3, one batch of the raw material deposition layer 12 formed in the furnace by the raw material charging method of the present invention is the raw material deposition layer 11 formed by the conventional raw material charging method shown in FIG. It can be seen that the material deposition surface is flat on the furnace center side and that the fluctuation of the material deposition shape in the furnace radial direction can be reduced. According to the raw material charging method of the present invention, the longitudinal cross-sectional shape of the ring-shaped deposit 12B on the furnace center side can be set to the same thickness as the ring-shaped deposit on the furnace wall side, and the ring-shaped deposit is densely formed on the furnace center side. It is also possible to adopt a charging pattern arranged in a row.

  In the raw material charging method of the present invention described above, for example, when the set value of the opening of the flow adjustment gate is changed in accordance with the tilt angle of the charging chute, it passes through the flow adjustment gate 6 per unit time before and after that. The amount of raw material to be fed, that is, the raw material flow rate A (t / min) per unit time changes, and in the present invention, the chute rotation speed B (swing / min) of the charging chute 3 is the total number of turns. Since the feed amount per turn of the charging chute is C (t / turn) = A (t / min) / B (turn / min), the set value of the opening of the flow control gate is set to be constant. It can be seen that the raw material charge per turn of the charging chute can be changed before and after the change.

  Moreover, in the raw material charging method of the present invention described above, the number of times of changing the raw material charging amount per one turn of the charging chute in correspondence with the tilt angle θ of the charging chute 3 during one batch raw material charging operation. It is not limited, and it can be explained that by setting the number of times to 2 or more, it is possible to finely control the material deposition shape in the furnace radial direction as compared with the case where the number is only one. Absent.

  In the best mode for carrying out the present invention, in the method of charging a raw material into a blast furnace equipped with a bell-less charging device, it corresponds to the tilt angle of the charging chute when forming a batch of raw material deposition layer in the furnace. Therefore, since the amount of raw material charged per turn of the charging chute is changed at least once during the raw material charging operation for one batch, the raw material deposition shape is more finely controlled in the furnace radial direction than in the past. In addition, since the fluctuation of the raw material deposition shape in the furnace radial direction can be reduced, the flow of the gas in the furnace is stabilized more than before.

The present invention described above was applied to a blast furnace having a 5150 m ³ bell-less charging device.

  Coke and ore were alternately charged into the furnace by one batch raw material charging operation, and blast furnace operation was performed. At that time, the raw material was charged into the furnace by a conventional raw material charging method and the blast furnace operation was performed, and then the blast furnace operation was performed by applying the raw material charging method of the present invention. Tables 2 to 5 show the raw material charging patterns for one batch. Conventional raw material charging patterns are shown in Tables 2 and 3, and raw material charging patterns to which the present invention is applied are shown in Tables 4 and 5, respectively. The relationship between the charging position in this blast furnace and the tilt angle θ of the charging chute is the same as in Table 1 above. In both raw material charging methods, coke was charged in the furnace for 32 tons and ore in the furnace for 128 tons by one batch raw material charging operation.

  In the conventional raw material charging method, during one batch raw material charging operation, the raw material charging amount per turn of the charging chute was made constant regardless of the tilt angle θ of the charging chute 3. On the other hand, in the raw material charging pattern to which the present invention is applied, the intermediate position P in the furnace radial direction for changing the raw material charging amount per turn of the charging chute during one batch raw material charging operation is the coke charging pattern. Between the charging positions 6 and 7, in the ore charging pattern, the charging position 6 is set, and the tilt angle θ for each turn on the furnace center side from the intermediate position P in the furnace radial direction is changed to the tilt angle θ. The charging position corresponding to one-to-one was changed to the minimum pitch. On the furnace center side, the amount of raw material charged per turn of the charging chute was less than that on the furnace wall side.

このようにして高炉操業を行った間の高炉操業状況を図４に示す。操業状況を表す炉内圧損（送風圧力−炉頂圧力）、溶銑温度および溶銑中Ｓｉ濃度について、それぞれ一日の平均値を取って図４中にプロットした。

FIG. 4 shows the blast furnace operation status during the blast furnace operation. With respect to the pressure loss in the furnace (blasting pressure-top pressure), the hot metal temperature, and the Si concentration in the hot metal representing the operation status, the average values for each day were taken and plotted in FIG.

  From the transition of the operation status shown in FIG. 4, after 20 days when the raw material charging method of the present invention was applied, the operating status was compared with the case where the blast furnace operation was performed by the conventional raw material charging method before that. It can be seen that the fluctuation of each value to be expressed is small and the blast furnace operation is more stable.

  This is because the material deposition shape can be controlled more finely in the radial direction of the furnace by the material charging method of the present invention, and in particular, the material deposition shape on the furnace center side from the middle of the furnace to the furnace center can be made flat. As a result, the difference in the material deposition shape between the furnace center side and the furnace wall side can be reduced, so that the flow of gas in the furnace can be kept more constant. by. If such stable operation can be continued, the blast furnace charging raw material conditions can be relaxed.

It is a schematic diagram which shows the principal part of the blast furnace to which this invention is applied. It is a schematic diagram explaining the problem in the conventional method. It is a schematic diagram explaining the raw material charging method to the blast furnace of this invention. It is a graph which shows the effect by this invention compared with the conventional method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Furnace body 2 Furnace wall 3 Charge chute 4 Vertical chute 5 Collective hopper 6 Flow control gate 7 Furnace top bunker 8A Upper seal valve 8B Lower seal valve 9 Flow of charged material 10 In the furnace before 1 batch raw material charging operation Raw material deposition surface 11 Raw material deposition layer for one batch according to the conventional method 12 Raw material deposition layer for one batch according to the method of the present invention 11A, 11B, 12A, 12B Ring-shaped deposition θ Tilt angle of charging chute P Furnace intermediate position

Claims (1)

While the charging sheet is swiveled, the raw material is charged into the furnace via the charging sheet while maintaining the tilt angle of the charging sheet at a set angle for each turn. In the raw material charging method for forming a raw material deposition layer into a blast furnace equipped with a bell-less charging device, the tilt angle of the charging sheet is set vertically downward when forming the raw material deposition layer for one batch in the furnace. Is the angle formed by the flow direction of the raw material of the charging sheet and the charging amount of the raw material per turn of the charging sheet at the tilt angles θ _i and θ _j of the charging sheet as θ _i and W _j , respectively. _i <θ _j
When W _i ≦ W _j
And setting the raw material charging amount per swivel of the charging sheet so as to change the raw material charging amount per swirling of the charging sheet at least once when charging the raw material for one batch. A method for charging raw materials into a blast furnace.

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