JP2011063836A - Turning chute in bell-less type raw material charging apparatus for blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turning chute in a raw material charging apparatus in a blast furnace with which even in a large-scaled blast furnace, the raw material can be reached near the furnace wall and regarding a layer thickness of the raw material charged into the blast furnace, even near the furnace wall, the distributing control in the radius direction can precisely be performed. <P>SOLUTION: The turning chute in the bell-less type raw material charging apparatus for blast furnace, having the characteristics, in which an assistant chute 4 for adjusting the dropping locus of the raw material flow flowing down the turning chute at the tip end part of the turning chute 2 is fixed, and the assistant chute 4 is provided with a rebounding plate for changing the raw material flow by colliding into the vertical direction and side plates for preventing the expansion into the side directions of the raw material flow, and the tip end portion of the turning chute 2 has the shape of more projecting at the tip end lower part of the turing chute than the tip end upper part of the turning chute, is used. It is desirable to set a lower end extending member in the turning chute at the tip end lower part of the turning chute 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a swivel chute used for a bell-less raw material charging apparatus installed at the top of a blast furnace.

  In the blast furnace, ore raw materials such as sintered ore and reducing materials are charged in layers from the top of the furnace, and high-temperature reducing gas generated by burning high-temperature air from the bottom of the furnace and burning coke is raised. It is a countercurrent reduction reactor. Therefore, the layer thickness distribution of the ore raw material and the reducing material charged in the furnace is very important for controlling the operation efficiency. Above all, heat loss to the furnace wall occurs, and ore raw materials and reducing materials are likely to fall down due to the formation of deposits. Control of the layer thickness of the material is very important.

  Since the blast furnace is axisymmetric, the object of controlling the layer thickness distribution is the radial distribution. In the bellless type raw material charging equipment that has become the mainstream in large blast furnaces in recent years, the raw material is poured off while turning a swirl chute shaped like a bowl around the furnace core, and the inclination (tilt angle) gradually increases. In other words, the raw material is sprinkled spirally from the peripheral side toward the center side and charged.

  However, in the charging method as described above, it is impossible to prevent the meandering of the raw material on the turning chute and the unexpected change in the drop position due to the change in the raw material charging speed and the raw material quality. Further, the width of the raw material flow discharged from the swivel chute widens before landing, and if the width is too wide with respect to the furnace radius, precise radial distribution control is difficult. Thus, for example, Patent Document 1 discloses a method of narrowing the fall trajectory to some extent by installing a fixed flat plate on the turning chute. Moreover, in patent document 2, the material fall controllability of a furnace shaft core part is installed by installing the auxiliary chute provided with the repulsion board and the side plate which prevents the spreading | diffusion of a raw material flow to the horizontal direction in the front-end | tip part of a turning chute. A turning chute with improved performance is disclosed.

Japanese Utility Model Publication No. 5-37948 JP-A-11-1709

  When the material falling flow from the swivel chute is made to collide with the plate attached to the tip as in Patent Documents 1 and 2 above, the drop control accuracy can be improved, but the material reaches the furnace wall due to the speed reduction accompanying the collision. It becomes difficult. On the other hand, blast furnaces continue to increase in size from the viewpoint of productivity, and the number of blast furnaces in which raw materials are difficult to reach the furnace wall is increasing. In the case of using a method of making the tilt angle close to horizontal in order to make the raw material reach the furnace wall, about 55 ° from the vertical is the limit in consideration of the smooth flow of the raw material. There is a means of using a turning chute with a long main body, but a too long turning chute is difficult to realize because the gear strength and motor power required for turning and tilting operations increase. In addition, the swivel chute is used in a high-temperature environment of several hundred degrees with flowing hard iron ore, so it can not be used while performing periodic replacement. The size is also limited by interference.

  As described above, it is difficult to perform precise radial distribution control on the layer thickness of the raw material charged in the blast furnace by using the conventional technology to reach the furnace wall in the large blast furnace. is there.

  Therefore, the object of the present invention is to solve such problems of the prior art, and even in a large blast furnace, the raw material can reach the vicinity of the furnace wall, and the layer thickness of the raw material charged into the blast furnace is Is to provide a swivel chute for a blast furnace raw material charging apparatus that enables precise radial direction distribution control even in the vicinity of the blast furnace.

The features of the present invention for solving such problems are as follows.
(1) An auxiliary chute that adjusts the dropping trajectory of the raw material flow that has flowed down the swivel chute is fixed to the tip of the swivel chute, and the auxiliary chute includes a repelling plate that collides with the raw material flow and changes the raw material flow in the vertical direction. A side plate that prevents the raw material flow from spreading in the lateral direction, and the tip portion of the turning chute has a shape in which the lower portion of the turning chute tip protrudes more than the upper portion of the turning chute tip. Rotating chute for bellless type raw material charging equipment for blast furnace.
(2) The turning chute of the bellless type raw material charging device for a blast furnace according to (1), wherein a turning chute lower end extending member is installed at a lower end of the turning chute.

  According to the present invention, a raw material can reach an accurate position near the furnace wall even in a large blast furnace without making the turning chute longer than necessary. Thereby, precise radial direction distribution control can be performed on the layer thickness of the raw material charged into the blast furnace, and the operation of the blast furnace becomes efficient.

The schematic of the turning chute which shows one Embodiment of this invention. The schematic of the turning chute which shows other one Embodiment of this invention. 1 is a schematic diagram of a scale model used in Example 1. FIG. (A) Raw material charging device as a whole, (b) Plan view of the turning chute portion, (c) Vertical sectional view of the turning chute portion The side view of the turning chute used in the Example. (A) Turning chute A, (B) Turning chute B, (C) Turning chute C The graph which shows the change of mass distribution by a turning chute. FIG. 5 is a schematic diagram of a scale model used in Example 2. The graph which shows the ratio of the thickness of the ore layer in each dimensionless radius position of a blast furnace. The graph of the simulation result which shows the effect of this invention.

  The turning chute according to the present invention is used in a blast furnace having a bellless type raw material charging device for charging a raw material into the furnace via the turning chute, and is charged into the furnace via the turning chute at the tip of the turning chute. The swivel chute is attached with an auxiliary chute that is a planar structure that contacts the upper surface of the raw material flow that is the flow of the raw material. The turning chute has a shape in which the lower part of the lower end of the turning chute protrudes. One embodiment of such a turning chute will be described with reference to FIG.

  FIG. 1 is a side view of the swirl chute in the raw material flow direction, and a protruding portion on the upper left side toward the paper surface is an attachment portion to the raw material charging device, which is the center of tilting. The right side of the sheet is the chute tip (raw material discharge part). The turning chute 2 has a shape in which the bottom surface at the lower end of the tip protrudes from the upper end of the tip of the turning chute. The turning chute 2 is bowl-shaped and has a shape in which the tip of the turning chute 2 is cut obliquely with respect to the length direction of the chute. The auxiliary chute 4 is directly fixed to the tip portion of the turning chute 2 without an elastic material. The auxiliary chute 4 adjusts the fall trajectory of the raw material flow that has flowed down the swivel chute 2. The auxiliary chute 4 is a repelling plate that collides with the raw material flow and changes the raw material flow in the vertical direction, and in the lateral direction of the raw material flow. And a side plate for preventing the spread of the. The interval between the side plates of the auxiliary chute 4 is preferably formed to be equal to the width of the tip portion of the turning chute or tapered toward the tip of the side plate. Moreover, it is preferable that a side plate has the length defined according to the target value of the fall width | variety of a raw material. The inclination angle of the rebound plate of the auxiliary chute 4 may be set as appropriate, but if the inclination angle is large, increasing the protrusion length of the bottom surface at the bottom of the tip may make it difficult to drop the raw material at the tip. The width and height of the front end of the front end are preferably 4.2 times or more of the average particle diameter of the charged raw material.

  Next, another embodiment of the present invention is shown in FIG. Considering that the swivel chute body is shared with existing spare parts inventory and other blast furnaces that use conventional swivel chutes, the shape of the swivel chute lower end protrudes more easily than the upper part of the swivel chute Is realized. As shown in FIG. 2, the same effect as the turning chute shown in FIG. 1 can be obtained by installing the turning chute lower end extending member 5 at the lower end of the turning chute 2.

  By using the swivel chute as described above, there is an effect that the swivel chute is substantially lengthened at the tip of the swivel chute (raw material discharge part), the flying distance of the charged raw material is extended, and more to the vicinity of the furnace wall. The raw material can be charged, and the distance between the lower end of the turning chute and the auxiliary chute is narrowed, so that the accuracy of the dropping position in the raw material charging can be increased.

In order to confirm the effect of the present invention, an experiment was performed using a 1 / 17.8 scale model of an actual volume 4400 m ³ blast furnace. An outline of the scale model is shown in FIG. FIG. 3A is the whole bell-less type raw material charging apparatus 1, FIG. 3B is a plan view of the swivel chute 2 portion, and FIG. 3C is a longitudinal sectional view of the swivel chute 2 portion. The turning chute length in the actual machine is 4.5m. In FIG. 3A, H1 is 435 mm.

  An experiment was performed using three types of swivel chutes A, B, and C. FIG. 4 shows a side view of the turning chutes A, B, and C in the raw material flow direction. In FIG. 4, the upper left part is the attachment part to the raw material charging device, and the right upper part is the tip (raw material discharge part) of the chute.

  The turning chute A has the same shape as that of a normal actual machine, and has a shape as shown in FIG. 4A in which the tip of the bowl-shaped chute is cut perpendicularly to the length direction of the chute.

  The turning chute B is the same as that described in Patent Document 2, and in addition to the turning chute A, a rebound plate that changes the raw material flow in the vertical direction by colliding the raw material flow with the tip of the turning chute, and the raw material It has an auxiliary chute 4 with a side plate that prevents the flow from spreading in the lateral direction. As shown in FIG. 4B, the inclination angle of the repulsion plate of the auxiliary chute 4 is 23 °.

  The turning chute C is the turning chute of the present invention, and has the same auxiliary chute 4 as the turning chute B. The difference from the turning chute B is that the bottom surface of the lower end of the turning chute protrudes from the upper portion of the turning chute tip. It is a shape as shown in FIG.4 (C) where the front-end | tip part of a bowl-shaped chute was cut | disconnected diagonally with respect to the length direction of a chute | shoot. As shown in FIG. 4C, the inclination angle of the repulsion plate of the auxiliary chute 4 is 23 °, and the angle of the tip portion of the turning chute 2 is 45 °.

  The scale material was poured while turning the turning chute 2, and the mass distribution of the scale material collected at each position (distance L from the center) of the sampling box 3 was compared. In any experiment, the tilt angle (θ) of the turning chute 2 in FIG. 3C was 52 ° from the vertical, the height H2 was 393 mm, and the turning speed was 8 rpm, the same as the actual machine.

  FIG. 5 shows the mass distribution of the pseudo raw material collected. According to FIG. 5, in the turning chute B, since the upper part of the raw material flow contacts the auxiliary chute 4, the mass ratio on the furnace wall side is slightly reduced compared to the turning chute A that does not have the auxiliary chute 4. It can be seen that the flight distance is shortened.

  On the other hand, in the turning chute C of the present invention, not only the flight distance is long, but also the fall range (peak width) is narrow, and it can be seen that highly accurate distribution control is possible. This is considered to be due to the fact that the flight distance is extended due to the effect of the swing chute becoming longer, and the drop width is narrowed because the distance between the lower end of the swing chute and the plate at the tip is reduced.

The effect of the present invention was confirmed by a model experiment. A scaled ore and scaled coke were charged into a 1 / 17.8 scale model of an internal volume 4400 m ³ blast furnace as shown in FIG. 6, and the ratio of the ore layer thickness to the coke layer thickness in the furnace radial direction was measured. Each dimensionless radial position of the blast furnace when the conventional turning chute (turning chute A of FIG. 4A) is used and when the turning chute of the present invention (turning chute C of FIG. 4C) is used. The ratio of the thickness of the ore layer to the sum of the thickness of the ore layer and the thickness of the coke layer (ore layer thickness / ore layer thickness + coke layer thickness) at (distance from the furnace axis / core radius) 7 shows.

  According to FIG. 7, “Ore layer thickness / Ore layer thickness + Coke layer thickness” is the same for either chute in the immediate vicinity of the furnace wall, but “Distance from core axis / Kore radius” In the range of 0.7 to 0.9, when the turning chute C according to the present invention is used, the ore layer thickness / ore layer thickness + coke is larger than when the conventional turning chute A is used. The “layer thickness” shows a large value, and a stable distribution as a whole can be formed. This is due to the following reason.

  In actual furnaces, a temperature drop in the furnace wall portion generates deposits (mainly zinc), thereby reducing the internal volume of the blast furnace and making the raw material drop unsatisfactory. Therefore, there is a lower limit temperature of the furnace wall portion in each blast furnace. As the ore layer thickness increases, the use efficiency of the reducing gas increases, but the temperature tends to decrease. Therefore, it is desirable to fix the ore layer thickness of the furnace wall portion at the upper limit.

  In the operation using the conventional swivel chute, the fall width of the raw material is wide, so in order to keep the ore layer thickness of the furnace wall part below the upper limit value, the ore layer thickness inside the furnace wall part must also be lowered. There wasn't. On the other hand, when the turning chute of the present invention is used, the fall width of the raw material is reduced, so that the range where the ore layer thickness is low can be suppressed only in the immediate vicinity of the furnace wall.

  In order to evaluate the influence of the change in the ore layer thickness distribution, a gas utilization rate was simulated. The results are shown in FIG.

  In the case of using the turning chute C of the present invention, the portion where the gas utilization rate is low is suppressed to a narrow range, so that the total gas utilization rate is 48.1 compared to the conventional operation using the turning chute A. From 4% to 49.7%. This improvement in the gas utilization rate corresponds to a reduction of the reducing material ratio of 5 kg / t, which can reduce the hot metal cost for the amount of the coke, and it can be seen that the operation can be made more efficient.

DESCRIPTION OF SYMBOLS 1 Raw material charging device 2 Turning chute 3 Sampling box 4 Auxiliary chute 5 Turning chute lower end extension member

Claims (2)

  An auxiliary chute that adjusts the dropping trajectory of the raw material flow that has flowed down the swivel chute is fixed to the tip of the swivel chute, the auxiliary chute includes a rebound plate that collides with the raw material flow and changes the raw material flow in the vertical direction, and a raw material flow And a side plate that prevents lateral spread of the swivel chute, and the tip portion of the swivel chute has a shape in which the lower end of the swivel chute tip protrudes more than the upper portion of the swivel chute tip. Rotating chute for bellless type raw material charging equipment for blast furnace.   The turning chute of the bellless type raw material charging apparatus for a blast furnace according to claim 1, wherein a turning chute lower end extending member is installed at a lower end of the turning chute.

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