CN113423844A

CN113423844A - Method for charging raw material into bell-less blast furnace and method for operating blast furnace

Info

Publication number: CN113423844A
Application number: CN202080013727.7A
Authority: CN
Inventors: 小笠原泰志; 佐藤健; 市川和平
Original assignee: JFE Steel Corp
Current assignee: JFE Steel Corp
Priority date: 2019-02-15
Filing date: 2020-01-30
Publication date: 2021-09-21
Also published as: BR112021015745A2; EP3896177A4; EP3896177B1; KR102635629B1; WO2020166347A1; JP6943339B2; KR20210113339A; EP3896177A1; JPWO2020166347A1

Abstract

The invention provides a method for charging raw materials into a bell-less blast furnace, which can charge raw materials into a specified position in the furnace without hindering productivity, and a blast furnace operation method using the method. A method of charging a blast furnace with a raw material without a bell, comprising rotating a distribution chute for charging a blast furnace with an iron source raw material and a carbonaceous material, wherein the distribution chute has a rebound plate inclined downward in a conveying direction of the distribution chute at a front end of the distribution chute, and a rotation speed of the distribution chute is higher than 10 rpm.

Description

Method for charging raw material into bell-less blast furnace and method for operating blast furnace

Technical Field

The present invention relates to a method for charging a raw material into a bell-less blast furnace for the purpose of reducing the reduced material ratio of the blast furnace, and a method for operating the blast furnace using the method for charging a raw material.

Background

In the blast furnace operation, coke and an iron source material are generally alternately charged as a charge material from the upper part of the blast furnace. Coke is used as a reducing material and as a fuel. The iron source raw material is iron-containing oxides such as sintered ore, pellet ore, lump ore and the like. In the following description, the iron source material is generally referred to as "ore". The coke layer and the ore layer are alternately formed in the furnace of the blast furnace to form a raw material accumulation layer. Simultaneously with the hot air sent out from the tuyere at the lower part of the blast furnace, auxiliary fuels such as coal powder, tar and the like are blown in.

In order to maintain stable operation of the blast furnace, it is necessary to ensure good ventilation of the raw material layer to the gas flowing from the lower portion of the furnace toward the upper portion of the furnace, thereby stabilizing the gas flow in the furnace. Stabilization of the furnace gas flow is achieved by ensuring stable core gas flow and furnace wall gas flow. The air permeability of the raw material stacking layer is greatly influenced mainly by the properties, particle size and charging amount of coke and ore. Further, the method of charging the charged material from the furnace top, that is, the distribution of the charged material charged into the furnace, is greatly affected. In the following description, the distribution of the contents is referred to as "distribution of the contents".

Conventionally, control of the distribution of the mass ratio of the coke layer to the ore layer in the radial direction of the blast furnace has been most frequently used for the control of the distribution of the charged material. In the following description, the mass ratio of the Coke layer to the Ore layer is referred to as "Ore/Coke". Blast furnaces are classified into bell-less blast furnaces or bell-type blast furnaces according to the form of a raw material charging apparatus. In either case of the bell less blast furnace or the bell blast furnace, it is effective to reduce the value of [ Ore/Coke ] in the furnace center portion in order to obtain a particularly stable gas flow.

In recent years, high-iron extraction ratio, high-pulverized coal ratio, and low-fuel ratio operations have been performed. In such an operation, the amount of ore charged is large relative to the amount of coke. In the following description, such operating conditions are referred to as "high O/C conditions". In the blast furnace operation under the "high O/C condition", the ratio of the ore layer having a large air flow resistance in the raw material buildup layer becomes high, and therefore the pressure loss in the upper part of the furnace increases. As a result, air leakage, unstable lowering of the contents, hanging of the contents, sliding, and the like are likely to occur. Due to such a phenomenon, stable operation of the blast furnace is greatly hindered, and productivity is significantly reduced. Therefore, in order to achieve stable operation under high O/C conditions, more precise control (Ore/Coke) is required.

Patent document 1 discloses the following method: when the distance from the furnace center in the furnace radial direction is defined as r (m) and the furnace radius of the furnace mouth is defined as Rt (m), the furnace area in the furnace radial direction is defined as r/Rt ≦ 0.20: a first region, r/Rt is more than 0.20 and less than or equal to 0.80: second region, 0.80 < r/Rt: the third region is controlled so as to have a charging distribution such that [ Lo/(Lc + Lo) ] (where Lo is the ore layer thickness and Lc is the coke layer thickness) satisfies the following conditions (a) to (d).

(a) Average value of the first region: less than 0.5

(b) Average value of the second region: 0.6 or more and less than 0.9

(c) Average value of the third region: 0.4 or more and less than 0.8

(d) Mean value of the first region < mean value of the third region < mean value of the second region

In this method, the reduction efficiency of the entire blast furnace is improved by increasing [ Lo/(Lc + Lo) ] of the second region while ensuring the air permeability in the blast furnace in the first and third regions.

However, bell-less charging devices having a distribution chute are widely used as a mechanism for charging a raw material from a furnace top. The bell-less charging device can adjust the falling position and the accumulation amount of the raw material in the radial direction of the furnace by changing the tilting angle and the rotating speed of the distribution chute, thereby controlling [ Ore/cake ]. The inclination angle of the distribution chute is the angle formed by the vertical direction and the angle of the raw material flowing on the chute surface of the distribution chute.

In order to deposit the raw material at a predetermined position in the furnace, it is effective to reduce the deposition width of the raw material charged into the furnace. Patent document 2 discloses the following method: the linear velocity V of the distribution chute tip is set to a predetermined value or less determined according to the properties of the charged raw material, thereby reducing the deposit width.

Patent document 1: japanese patent laid-open publication No. 2018-193579

Patent document 2: japanese patent laid-open publication No. 2003-328018

In recent years, it has been found that the [ Ore/Coke ] in the center portion is reduced and the ventilation is far from stabilized by forming a reflow ribbon in an inverted V-shape in the operation under the high O/C condition. It is sometimes necessary to reduce [ Ore/Coke ] in the furnace wall to ensure ventilation and increase [ Ore/Coke ] in the middle to improve the reduction efficiency of the entire furnace. Therefore, it is necessary to stably and reliably deposit the raw material from the furnace top to a predetermined position in the furnace through the distribution chute.

In order to deposit the raw material at a predetermined position in the furnace, it is necessary not only to reduce the deposition width of the raw material disclosed in patent document 2, but also to suppress collapse of the raw material deposited at the predetermined position. Therefore, it is necessary to reduce the stacking width and to rationalize the rotation speed of the distribution chute when the raw material is charged, while suppressing the collapse of the raw material stacked at a predetermined position.

Disclosure of Invention

The reduction in the tip speed of the distribution chute disclosed in patent document 2 leads to an increase in the loading time, and therefore may hinder productivity. The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for charging a raw material into a bell-less blast furnace, which can charge the raw material into a predetermined position in the furnace without impairing the productivity, and a method for operating the blast furnace using the method for charging a raw material.

The features of the present invention for solving the above problems are as follows.

[1] A method for charging raw material into a bell-less blast furnace, comprising rotating a distribution chute to charge an iron source raw material and a carbonaceous material into the blast furnace, wherein,

the distribution chute has a rebound plate inclined downward in the conveying direction of the distribution chute at the front end of the distribution chute, and the rotation speed of the distribution chute is higher than 10.0 rpm.

[2] The raw material charging method for a bell-less blast furnace according to [1], wherein,

the distribution chute has a rotational speed of 12.0rpm or more.

[3] The raw material charging method for a bell-less blast furnace according to [2], wherein,

the tilt angle of the distribution chute is set to 1.36 alpha or more with respect to an angle alpha determined by a distance d from the rotation center of the distribution chute to the level of raw material accumulation in the furnace at the start of raw material charging, a furnace mouth radius Ro, and the following expression (1),

tanα＝Ro/d…(1)。

[4] the raw material charging method for a bell-less blast furnace according to [1], wherein,

the distribution chute has a rotation speed of 14.0rpm or more.

[5] The raw material charging method for a bell-less blast furnace according to [4], wherein,

the tilt angle of the distribution chute is set to 1.41 alpha or more with respect to an angle alpha determined by a distance d from the rotation center of the distribution chute to the level of raw material accumulation in the furnace at the start of raw material charging, a furnace mouth radius Ro, and the following expression (1),

Tanα＝Ro/d…(1)。

[6] a method for operating a blast furnace, wherein,

charging an iron source material and a carbon material into the blast furnace according to the method for charging a raw material for a bell-less blast furnace according to any one of [1] to [5 ].

In the method for charging raw material into a bell-less blast furnace according to the present invention, the ore and the carbonaceous material are charged into the blast furnace at a rotation speed of the distribution chute which is higher than 10.0 rpm. This makes it possible to increase the deposition angle of the carbonaceous material in the furnace wall peripheral portion without impairing the productivity, and also to reduce the deposition width. As a result, the area of the region where [ Ore/Coke ] is reduced in the furnace wall portion can be reduced, so that the gas utilization rate of the blast furnace is improved, and the operation with a low reduced material ratio and a low Coke ratio is realized.

Drawings

Fig. 1 is a schematic diagram showing an outline of a modeling apparatus 10.

Fig. 2 is a perspective and cross-sectional view of the front end of the dispensing chute 18 including the rebounding panel 22.

Fig. 3 is a graph showing the weight distribution obtained by the loading experiment.

Fig. 4 is a schematic cross-sectional view of a model apparatus 30 used for coke stacking angle measurement experiments.

Fig. 5 is a schematic view showing the state of the furnace when starting charging of the raw material.

Detailed Description

The inventors of the present invention used an internal volume of 5,005m to confirm that coke in a bell-less blast furnace falls from a distribution chute³The coke charging experiment was carried out using a model apparatus 10 having a ratio of 1/17.8 for a blast furnace having a throat diameter of 11.2 m. Fig. 1 is a schematic diagram showing an outline of a modeling apparatus 10.

The mould apparatus 10 has a furnace top bin 12, a collection hopper 16, a distribution chute 18 and a sampling box 24. The top bunker 12 has three hoppers 14 for receiving coke and ore. A gate for allowing the stored raw material to be discharged is provided at a lower portion of each hopper 14. The collecting hopper 16 feeds the raw material discharged from the top silo 12 to a distribution chute 18. The distribution chute 18 has a chute 20 and a rebound board 22. The sampling boxes 24 are arranged radially in 4 directions with a position corresponding to the center of rotation of the distribution chute 18 as the center. Each sampling box 24 has a plurality of receiving portions 26 divided at 20mm intervals from the center side toward the outside.

The height of the sampling box 24 is set so that the opening of the upper portion of the sampling box 24 is at a level of 424mm vertically downward from the center position of the tilting/rotation of the distribution chute 18. Since the diameter of the furnace opening of the model apparatus 10 was 630mm, the level difference corresponded to 0.67 times the diameter of the furnace opening.

Fig. 2 is a perspective and cross-sectional view of the front end of the dispensing chute 18 including the rebounding panel 22. Fig. 2 (a) is a perspective view, and fig. 2 (b) is a sectional view. When the conveying direction of the distribution chute 18 is set to the direction of the arrow 21 in fig. 2 (b), the rebound plate 22 is provided at the front end of the distribution chute 18 so as to be inclined downward with respect to the conveying direction.

The rebounding panel 22 is provided such that, when the conveying direction of the chute 20 is set to be parallel to the horizontal, the distance (L in fig. 2 (b)) from the front end of the chute 20 to the rebounding panel 22 in the horizontal direction is 70 mm. The inclination angle (θ of fig. 2 (b)) of the rebound plate 22 is 23 ° with respect to the horizontal direction. When the angle of the rebounding panel 22 is changed, the length of the rebounding panel 22 is adjusted so as not to change the distance in the horizontal direction from the chute 20 to the rebounding panel 22.

The coke charging experiment using the mold apparatus 10 was performed by the following procedure. First, 3kg of coke having a particle size of 2.0mm to 2.8mm was charged into the top bunker 12. The opening of the top bunker 12 was adjusted so that 3kg of coke was discharged in 17 seconds. Next, the door is opened, coke is discharged from the top silo 12 to the collection hopper 16, and the coke is dropped via the distribution chute 18. The coke falling from the distribution chute 18 is received in the receiving portion 26 of the sampling tank 24. Coke is an example of a carbon material.

The weight of the coke contained in each storage part 26 of the sampling tank 24 is measured, and the weight distribution in the radial direction of the falling coke is calculated. Fig. 3 is a graph showing the weight distribution obtained by the loading experiment. In fig. 3, the horizontal axis represents the position (mm) in the radial direction from the center, and the vertical axis represents the cumulative weight frequency (%). The cumulative weight frequency is defined as the ratio of the weight of coke reaching the center side from the position separated from the center by a predetermined distance to the total coke weight.

In the loading experiment, the position where the cumulative weight frequency was 50% was defined as the main flow falling position, and the interval in the radial direction where the cumulative weight frequency was from 5% to 95% was defined as the falling width. The tilt angle of the distribution chute 18 was adjusted so that the furnace wall position 424mm vertically downward from the center of tilt/rotation coincides with the cumulative weight frequency of 95%, that is, 315mm from the furnace center.

The loading experiment was performed by setting the length of the chute 20 of the distribution chute 18 to 240mm and the rotation speed of the distribution chute 18 to 42.2, 50.6, and 59.1 rpm. Since the model equipment 10 is a 1/17.8 ratio of the real blast furnace, if the froude number is constant as a condition under which the trajectory of the raw material falling from the distribution chute 18 becomes similar to that of the real blast furnace, the rotational speed of 42.2rpm in the model equipment 10 corresponds to the rotational speed of 10.0rpm of the real blast furnace. The rotation speed of 50.6rpm in the model apparatus 10 corresponds to the rotation speed of 12.0rpm in the real-machine blast furnace. The rotation speed 59.1rpm in the model apparatus 10 corresponds to the rotation speed 14.0rpm of the real-machine blast furnace. The loading experiment was performed with and without the rebound plate 22 installed. The experimental conditions and results are shown in table 1 below.

[ Table 1]

As shown in table 1, when the distribution chute 18 having the rebounding panel 22 attached to the tip end thereof was used, the falling width of the coke decreased with the increase in the rotation speed. On the other hand, in the case of using a distribution chute to which the rebounding panel 22 is not attached at the leading end, the falling width of the coke increases with the increase in the rotation speed. From this result, it was confirmed that the falling width of the coke can be reduced by using the distribution chute 18 having the rebounding panel 22 attached to the front end and charging the coke at a rotation speed of the distribution chute 18 higher than 42.2 rpm.

Next, a coke stacking angle measurement experiment will be described. FIG. 4 is a schematic cross-sectional view of a model device 30 used in a coke stacking angle measurement experiment. The mould apparatus 30 has a top silo 12, a collection hopper 16, a distribution chute 18 and a mould furnace 32 with a mouth diameter of 630 mm. The top bunker 12, the collection hopper 16 and the distribution chute 18 are the same as those used in the mould apparatus 10. In the bank angle measurement experiment, first, a bank plane with an inclination angle of 16 ° is produced in the model furnace 32. Thereafter, the coke is dropped onto the deposition surface through the distribution chute 18 by the same procedure as in the charging experiment, and the deposition angle of the coke deposited near the furnace wall is measured. The inclination angle of the distribution chute 18 is adjusted within a range of 285-325 mm from the furnace center at a main flow falling position of 424mm vertically downward from the center of inclination/rotation. The main stream falling position was measured by performing a coke charging experiment using the model apparatus 10. The results are shown in tables 2 and 3 below.

[ Table 2]

[ Table 3]

As shown in table 2, when the distribution chute 18 having the rebounding plate 22 attached to the tip thereof was used, the coke deposition angle was extremely large in the tilt angle under the same rotation speed. When the main flow falling position is separated from the wall surface toward the center side, the number of particles of the coke colliding with the wall surface is small, and therefore the bank angle becomes small. When the falling position of the main stream is close to the wall surface, the number of particles of the coke colliding with the wall surface is large, the rebound from the wall surface is large, and the deposition angle of the coke is also small. In this way, the deposition angle of the coke becomes smaller as the main flow falling position is away from the wall surface, and the deposition angle of the coke becomes smaller as the main flow falling position is closer to the wall surface.

When the rotation speed of the distribution chute 18 is high, the main flow falling position at which the deposition angle becomes a very large inclination angle changes toward the furnace wall side. In the case of increasing the rotational speed, centrifugal force acts on the coke flowing in the distribution chute 18, and therefore the coke falls farther, than in the case of a lower rotational speed. As described above, even if the main flow falling position is the same, the falling width becomes smaller when the rotation speed is high than when the rotation speed is low, and therefore the number of particles of the coke which collide with the oven wall before reaching the deposition surface is reduced. Therefore, when the rotation speed is high, the main flow falling position at which the deposition angle of coke becomes an extremely large inclination angle changes toward the furnace wall side, as compared with the case of a low rotation speed.

When the rotation speed is high, the deposition angle of coke becomes large even if the main stream falling position is on the furnace center side. This is considered to be because the speed of the coke particles in the horizontal direction is increased by increasing the rotational speed, and even if the main flow falling position is the furnace center side, the coke particles colliding with the deposition surface move toward the furnace wall side, thereby increasing the deposition angle of the coke. When the maximum values of the deposition angle of coke under the same rotation speed are compared at the respective rotation speeds, the maximum value of the deposition angle increases as the rotation speed increases.

On the other hand, as shown in table 3, when the distribution chute to which the rebound board 22 is not attached to the tip end is used, the maximum value of the heap angle under the same rotation speed condition becomes smaller as the rotation speed increases. This is considered to be because the increase in the rotational speed increases the radial falling width, so that coke is deposited sparsely.

In this manner, it was confirmed that when the distribution chute 18 having the rebounding panel 22 attached to the tip end thereof is used, the deposition angle of the coke can be increased by increasing the rotation speed of the distribution chute 18. From the results, it was confirmed that the deposition angle of coke in the vicinity of the furnace wall can be increased by using the distribution chute 18 having the rebounding plate 22 attached to the tip thereof and charging the coke at a rotation speed of the distribution chute 18 higher than 42.2 rpm.

The reason why the deposition angle of the coke in the vicinity of the furnace wall becomes large is considered to be that the falling width of the coke in the radial direction becomes small due to the increase in the rotational speed of the distribution chute 18, and the coke is densely deposited in a specific region in the radial direction.

Next, the same loading experiment was performed by changing the chute length of the distribution chute 18 for the purpose of confirming the influence of the chute length of the distribution chute 18. The results are shown in table 4 below. The charging experiment was carried out under the condition that the inclination angle is in the range of 285-325 mm from the furnace center at the main flow falling position of 424mm vertically downward from the rotation and inclination center, and the accumulation angle of the coke is extremely large.

[ Table 4]

Experimental No	40	41	42	43	44	45
							Rotational speed (rpm)	42.2	50.6	59.1	42.2	50.6	59.1
Chute length (mm)	220	220	220	260	260	260
							Rebound board (with/without)	Is provided with	Is provided with	Is provided with	Is provided with	Is provided with	Is provided with
Angle of inclination (°)	56.5	55.0	53.5	53.0	51.5	50.0
							Falling width (-)	112	105	101	87	82	77
Coke fill front stack angle (°)	16.3	16.5	16.7	16.4	16.2	16.6
							Coke loading back stacking angle (°)	25.8	28.7	28.0	26.7	29.3	29.5

As shown in table 4, when the chute length of the distribution chute was shortened from 240mm to 220mm, the falling width of the coke was increased and the deposition angle of the coke was decreased as compared with the case of using the distribution chute having the chute length of 240mm shown in table 1. However, even when a distribution chute having a chute length of 220mm is used, the falling width of coke becomes smaller and the coke deposition angle near the oven wall becomes larger by setting the rotation speed of the distribution chute to 50.6rpm or more than by setting the rotation speed to 42.2 rpm.

When the chute length of the distribution chute is increased from 240mm to 260mm, the falling width of the coke becomes smaller and the deposition angle of the coke becomes smaller than in the case of using a distribution chute having a chute length of 240 mm. When a distribution chute having a chute length of 260mm is used, the falling width of coke becomes smaller and the coke deposition angle near the furnace wall becomes larger by setting the rotation speed of the distribution chute to 50.6rpm or more than that in the case of setting the rotation speed to 42.2 rpm. From the results, it was confirmed that the falling width of the coke and the stacking angle of the coke were slightly affected by the change in the chute length of the distribution chute, but the falling width of the coke could be reduced and the stacking angle of the coke could be increased without changing the tendency by setting the rotation speed faster than 42.2 rpm.

The method for charging a raw material into a bell-less blast furnace according to the present invention is based on the results of the above-described coke charging experiment. The rotational speeds of the distribution chute 18 in the model device 10 and the model device 30 were 42.2rpm, 50.6rpm, and 59.1rpm, which are equivalent to the rotational speeds of the distribution chute in the real-machine blast furnace, 10.0rpm, 12.0rpm, and 14.0 rpm. Therefore, in the method for charging raw material into a bell-less blast furnace according to the present embodiment, the distribution chute having the rebounding plate inclined downward at the tip thereof with respect to the conveying direction of the distribution chute is used, and the ore and the carbonaceous material are charged into the blast furnace at a rotation speed of the distribution chute higher than 10.0 rpm. This makes it possible to increase the deposition angle of the carbonaceous material charged into the wall of the blast furnace without impairing the productivity, and to reduce the falling width thereof. As a result, the area of the region where [ Ore/Coke ] is lowered can be reduced in the furnace wall of the blast furnace, thereby improving the gas utilization efficiency of the blast furnace and realizing the operation of the blast furnace with a low reduced material ratio and a low Coke ratio.

The rotation speed of the distribution chute is preferably 12.0rpm or more. Thus, the coke deposition angle of the furnace wall can be increased as compared with the case where the rotation speed is set to less than 12.0rpm, and the reduced material ratio and the coke ratio in the blast furnace operation can be further reduced as shown in examples described later.

More preferably, the rotation speed of the distribution chute is 14.0rpm or more. Thus, compared with the case where the rotation speed is set to less than 14.0rpm, the coke deposition angle of the furnace wall portion can be increased, and the reduced material ratio and the coke ratio during the blast furnace operation can be further reduced.

Further, if the distance from the center position of the tilting/rotation of the distribution chute to the raw material accumulation level in the furnace at the start of charging the raw material is shortened, the distance from the front end of the chute to the accumulation surface is reduced, and the falling width of the coke is further reduced. However, in order to make the main flow falling position reach the furnace wall, the tilt angle needs to be increased. When the inclination angle is increased, the falling width of the main stream falling position toward the furnace wall side becomes large when the deposition surface of the raw material is lowered. Therefore, it can be said that the operation of the blast furnace is susceptible to the fluctuation of the raw material deposition level in the furnace at the start of charging the raw material. From this viewpoint, it is preferable that the distance from the center position of the tilting/rotation of the distribution chute to the raw material accumulation level in the furnace at the start of the raw material charging is 0.60 times or more the radius of the furnace opening. Here, the raw material deposition level in the furnace at the start of charging of raw material means a level of a deposition surface of raw material in the furnace at the time of starting charging of raw material from the distribution chute.

Fig. 5 is a schematic view showing the state of the furnace when starting charging of the raw material. The level of the deposition surface of the raw material in the furnace at the start of charging the raw material will be described with reference to fig. 5.

In the blast furnace, the deposition surface of the raw material is not horizontal, but in the blast furnace operation, in order to determine the timing of starting the charging of the raw material, for example, a detection mechanism such as a depth finder for detecting the level of the deposition surface of the raw material in the vicinity of the furnace wall is used. The detection means detects that the level of the deposition surface has fallen to a predetermined level, and starts charging a predetermined amount of the raw material at the detected timing. Thereby, the level of the deposition surface in the furnace is controlled to be within a predetermined range. Therefore, in the present embodiment, the level of the deposition surface of the raw material in the furnace at the start of charging the raw material is defined as the horizontal plane 40 among the levels of the deposition surface of the raw material in the vicinity of the furnace wall detected by the detection means. In the embodiment to be described below, the inclination angle of the distribution chute 18 is represented by a distance d from the center position 42 of the inclination/rotation of the distribution chute to the horizontal plane 40, which is the level of the deposition surface of the raw material in the furnace at the start of the raw material charging, a furnace mouth radius Ro, and an angle α defined by the following expression (1). The tilt angle of the distribution chute in the present embodiment is an angle formed by the conveyance direction of the raw material by the distribution chute 18 and the vertically downward direction.

Tanα＝Ro/d…(1)

Examples

Next, examples will be explained. Using an internal volume of 5,005m³A blast furnace with a furnace mouth diameter of 11.2 m. The ore is discharged from the ore storage tank and stored in the top hopper, and the coke is discharged from the coke storage tank and stored in the other top hopper. Further, the ore and the coke are alternately discharged to a distribution chute having a rebounding panel, and the ore and the coke are accumulated in the blast furnace, thereby performing a blast furnace operation.

In comparative example 1, the chute length of the distribution chute having the rebounding panel was set to 4.2m, and a vertical downward distance of 7.55m from the center of rotation and tilting of the distribution chute was set to a raw material deposition level in the furnace at the start of raw material charging, so that the ore and coke were deposited in the blast furnace. At this time, the angle defined by the distance d from the center position of the tilting/rotation of the distribution chute to the level of the deposition surface of the raw material in the furnace at the start of the raw material charging, the furnace mouth radius Ro, and (1) above was 36.6 °.

When charging coke, charging is started after the tilting angle of the chute is set to 54.5 degrees, and charging is performed by sequentially reducing the tilting angle until coke is deposited on the center of the furnace with the rotating speed set to 10.0-14.0 rpm.

In the invention examples 1 to 15, the blast furnace operation was performed by setting the chute length of the distribution chute having the rebounding panel to 4.2m and setting the vertical downward 7.55m from the center position of the tilting/rotation of the distribution chute as the raw material deposition level in the furnace at the start of the raw material charging, and depositing the ore and coke in the blast furnace.

In the invention examples 1 to 15, the angle α defined by the distance d from the center position of tilting/rotation of the distribution chute to the level of the deposition surface of the raw material in the furnace at the start of charging the raw material, the furnace mouth radius Ro, and the above (1) was also 36.6 °.

When coke is charged, the tilt angle of the distribution chute at the start of charging is sequentially decreased in accordance with the increase in the rotation speed, and after the start of charging, the tilt angle is sequentially decreased to charge the coke until the coke is accumulated in the center of the furnace. The rotating speed of the distribution chute is 10.5-14.0 rpm. In the present invention example, the operation conditions and the operation results of the comparative example are shown in tables 5 and 6 below. After charging the coke, profile data (profile data) of the charged material was obtained, and the coke deposition angle of the furnace wall portion was calculated from the inclination angle of 1.8m from the furnace wall in the profile data.

[ Table 5]

[ Table 6]

In comparative example 1, the coke falling width at the raw material deposition level in the furnace at the start of charging of the raw material was large, and the coke deposition angle of the furnace wall portion was small at 26.1 °, whereas in inventive examples 1 to 15, the coke deposition angle of the furnace wall portion was changed to 26.5 ° or more. As a result, the area of the region where [ Ore/Coke ] was reduced in the furnace wall portion was reduced, the gas utilization rate in the entire furnace was improved, and the reducing agent ratio and the Coke ratio in invention examples 1 to 15 were reduced as compared with comparative example 1.

In invention examples 4 to 15 in which the distribution chute rotation speed was 12.0rpm or more, when the same rotation speed was used, the coke deposition angle of the furnace wall portion was increased and the reduced material ratio and the coke ratio were decreased by setting the inclination angle of the distribution chute to 1.36 α or more compared to the inclination angle of the distribution chute of less than 1.36 α. From the results, it was confirmed that the reduced material ratio and the coke ratio in the blast furnace operation could be further reduced by setting the rotation angle of the distribution chute to 1.36 α or more.

Further, in invention examples 13 to 15 in which the rotation speed of the distribution chute was 14.0rpm or more, the coke deposition angle of the furnace wall portion was increased and the reduced material ratio and the coke ratio were decreased by setting the inclination angle of the distribution chute to 1.41 α or more, as compared with the inclination angle of the distribution chute to less than 1.41 α. From the results, it was confirmed that the reduced material ratio and the coke ratio in the blast furnace operation can be further reduced by setting the rotation angle of the distribution chute to 1.41 α or more.

Description of the reference numerals

10 … model equipment; 12 … furnace roof bins; 14 … hopper; 16 … collecting hopper; 18 … distribution chute; 20 … chute; 21 … arrows; 22 … resilient sheet; 24 … sample box; 26 … a housing portion; 30 … model equipment; 32 … model furnace; 40 … horizontal plane; 42 … center position.

Claims

1. A method for charging a bell-less blast furnace with a raw material, comprising rotating a distribution chute to charge an iron source raw material and a carbonaceous material into the blast furnace,

the distribution chute has a springback plate at the front end of the distribution chute which is inclined downwards in relation to the conveying direction of the distribution chute,

the distribution chute was rotated at a speed of more than 10.0 rpm.

2. The method of charging a raw material into a bell-less blast furnace according to claim 1,

the distribution chute has a rotational speed of 12.0rpm or more.

3. The method of charging a raw material into a bell-less blast furnace according to claim 2,

the tilt angle of the distribution chute is set to 1.36 alpha or more with respect to an angle alpha determined by a distance d from the rotation center of the distribution chute to the raw material accumulation level in the furnace at the start of charging of the raw material, a furnace mouth radius Ro, and the following expression (1),

tanα＝Ro/d…(1)。

4. the method of charging a raw material into a bell-less blast furnace according to claim 1,

the distribution chute has a rotational speed of 14.0rpm or more.

5. The method of charging a raw material into a bell-less blast furnace according to claim 4,

the tilt angle of the distribution chute is set to 1.41 alpha or more with respect to an angle alpha determined by a distance d from the rotation center of the distribution chute to the raw material accumulation level in the furnace at the start of charging of the raw material, a furnace mouth radius Ro, and the following expression (1),

Tanα＝Ro/d…(1)。

6. a method for operating a blast furnace, wherein,

the charging method of a bell-less blast furnace according to any one of claims 1 to 5, wherein an iron source material and a carbon material are charged into the blast furnace.