JP2011140705A - Turning chute in bell-less type furnace-top charging apparatus for blast furnace and method for operating blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a turning chute which solves the problem of the conventional turning chute, without needing the large facility investment. <P>SOLUTION: There is disclosed the turning chute in the bell-less type furnace-top charging apparatus for blast furnace, wherein a repulsion plate inclined to downward from the tip-end part is provided on either one side of the left or the right side at the tip-end part of the turning chute of which the upper part is opened and which has a groove-type cross-sectional shape. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a turning chute of a bellless furnace top charging device for a blast furnace and a blast furnace operating method for charging a raw material through the turning chute.

  Blast furnace operation is performed by alternately charging iron raw materials such as iron ore, sintered ore, pellets, and coke from the top of the blast furnace furnace, and blowing hot air from the tuyeres at the bottom of the furnace. In the furnace, CO gas is generated by the reaction between coke and hot air at the tip of the tuyere, and the high-temperature furnace gas containing CO heats, reduces, and melts the descending iron raw material. During the dripping, the melt is reduced by coke and collected in the hot water reservoir, and is discharged from the outlet to the outside of the furnace at an appropriate time.

  Immediately before being melted and dripped, the iron raw material is in a soft and fused state and encloses coke to form a cohesive zone. Thus, in the blast furnace, the iron raw material charged from the top of the furnace is, in order from the top, a lump in a lump state, a fusion band in a softened fusion state, and a dripping band in a molten dripping state, The in-furnace gas generated at the tip of the tuyere at the lower part of the furnace is discharged from the top of the furnace to the outside of the furnace through the dripping band, the fusion band, and the massive band in order.

  The ventilation resistance in the blast furnace furnace is the largest in the cohesive zone, followed by the massive zone, and the smallest in the dripping zone. Therefore, if the shape of the cohesive zone in the blast furnace changes, the air permeability and gas utilization rate in the furnace will differ, so the shape of the cohesive zone in the blast furnace maintains the stable operation of the blast furnace. This is especially important.

  As described above, control of the cohesive zone in the blast furnace is important, and several methods for controlling the position and shape of the cohesive zone have been disclosed so far (see, for example, Patent Documents 1 and 2). .

  In Patent Document 1, the gas body obtained from one or a plurality of sondes and the solid temperature and the gas composition obtained from the measured values of the gas band and the lower side of the cohesive zone, which are charged in the blast furnace or lower part of the blast furnace. Is disclosed, and the distribution of the ratio (O / C) of the iron ore layer thickness to the coke layer thickness (O / C) and the particle size distribution in the radial direction of the blast furnace are disclosed so that the position becomes the optimum position.

In Patent Document 2, a gas sampling device is used to continuously measure and monitor the CO ₂ concentration at a certain height position at the bottom of the blast furnace to determine the position of the cohesive zone, and based on the determined position Thus, a blast furnace operating method for determining operating conditions to maintain the hot metal temperature in a desired range is disclosed.

  Thus, in order to operate the blast furnace stably, it is necessary to appropriately control the raw material distribution in the furnace top radial direction, that is, the particle size distribution and the layer thickness distribution of coke and iron raw material. In blast furnace operation, it is important to control the raw material distribution at the top of the furnace in a flexible and highly accurate manner so as to obtain an optimum distribution in the radial direction of the furnace in response to constantly changing furnace conditions.

  In recent blast furnaces, a bellless type furnace top charging device equipped with a turning chute with greater freedom of raw material distribution control is adopted, and the turning direction, turning speed and / or inclination angle of the turning chute is adjusted. By doing so, various raw material charging controls are performed (for example, refer to Patent Documents 3 to 11).

  Moreover, in order to improve the controllability of the material charging control by the turning chute, some proposals for improving the turning chute main body have been made (for example, see Patent Documents 12 to 14).

  Patent Document 12 discloses a reflection of a flat surface fixed to the tip of a chute body having a groove-shaped cross section with an open upper portion at a certain angle with a width wider than the groove width downward from the chute tip with respect to the falling direction. A swivel chute having a plate has been proposed.

  The swirling chute of Patent Document 12 can form a raw material falling flow that is thinner and wider than the conventional swirling chute, so that there is less resegregation of the raw material after charging, and the raw material deposited in the furnace Even if the next raw material is added to the inclined surface, the phenomenon that the deposited layer is broken hardly occurs. The turning chute disclosed in Patent Document 12 can stabilize the distribution of raw materials and the operation of the blast furnace.

  In Patent Document 13, a cone-type repulsion plate is provided on the top surface of the tip portion so as to be separated and collide only with the upper flow of the charge sliding down on the swivel chute, and the falling direction of the raw material charged from the swirl chute is set vertically. A turning chute that changes downward is proposed.

  The swivel chute disclosed in Patent Document 13 is provided with a small and light weight rebound plate at the tip. Basically, all raw materials are dropped vertically downward to achieve highly accurate and stable raw material distribution control. It is something to try.

  In Patent Document 14, a flat repulsion plate having a width wider than the bottom plate of the swivel chute main body is dropped at the tip of the trapezoidal cross-section swivel chute main body having an open top and a flat bottom plate. A turning chute that is fixed downward with respect to the direction and at a fixed angle with respect to the upper surface of the turning chute main body has been proposed.

  The turning chute of Patent Document 14 aims at highly accurate charge distribution control by greatly reducing the horizontal movement speed component force of the entire raw material group by collision with the repulsion plate.

Japanese Examined Patent Publication No. 63-61367 JP 2006-249501 A JP-A-11-209806 Japanese Patent Laid-Open No. 11-217604 Japanese Patent Laid-Open No. 11-217605 JP-A-11-269513 JP 2000-160214 A JP 2000-204406 A JP 2000-204407 A JP 2005-290511 A JP 2008-024997 A Japanese Utility Model Publication No. 05-37948 JP 09-249907 A JP 2000-234110 A

  In the raw material charging control, the effect of changing the fall trajectory downward from the parabola by attaching the repulsion plate to the tip of the swivel chute and causing the material falling from the tip of the swivel chute to collide with the flat plate type rebound plate. is there.

  However, since the repulsion plate is heavy, the swivel chute equipped with the repulsion plate becomes a heavier swivel chute than the conventional swivel chute, improving the mechanical strength of the swivel chute support mechanism, and the swivel chute control mechanism Therefore, it is necessary to increase the output of the tilting motor and the turning motor.

  In addition, since the rebound plate is fixed so that the falling raw material collides, it is impossible to change the charge so that the raw material does not hit the rebound plate during blast furnace operation. The degree of freedom is restricted. In order to secure the degree of freedom of the charging mode, a more complicated mechanism is required to attach the repulsion plate whose mounting angle can be adjusted during the operation of the blast furnace to the tip of the swivel chute. It is necessary to further improve the mechanical strength of the turning chute support mechanism and to increase the output of the tilting motor and the turning motor in the turning chute control mechanism.

  Therefore, an object of the present invention is to provide a turning chute that solves the problems in the conventional turning chute without requiring a large capital investment.

  In the present invention, various studies have been made on the structure of a turning chute that solves the above problems. As a result, if a repulsion plate inclined downward from the tip is provided on one of the left and right sides of the tip of the turning chute, the above-mentioned problems can be solved and the degree of freedom of the charging mode can be increased. I found it.

  The present invention has been made based on the above findings, and the gist thereof is as follows.

  (1) In a swivel chute of a bellless type furnace top charging device for a blast furnace, a repulsion plate that is inclined downwardly from the tip on either side of the left or right of the tip of the swivel chute having a groove-shaped cross-sectional shape with an open top A swivel chute for a bell-less furnace top charging device for a blast furnace.

  (2) In a turning chute of a bellless type furnace top charging device for a blast furnace, a repulsion plate inclined downward from the tip on either side of the left or right of the tip of the turning chute having a U-shaped cross-section with an open top A swivel chute for a bell-less furnace top charging device for a blast furnace.

  (3) The bellless furnace top loading for a blast furnace according to (1) or (2), wherein the turning chute is capable of changing a turning direction, a turning speed, and a tilt angle. Device swivel chute.

  (4) The bellless type furnace top loading for a blast furnace according to any one of (1) to (3), wherein the width of the rebound plate is 40 to 60% of the inner width of the tip of the turning chute. Device swivel chute.

  (5) The blast furnace according to any one of (1) to (4), wherein the attachment position of the rebound plate is a position where it intersects with an extension line on either the left end or the right end inside the turning chute. Swivel chute for bellless type furnace top charging equipment.

  (6) The bellless type top loading for a blast furnace according to any one of (1) to (5), wherein the mounting angle of the rebound plate is 15 to 45 ° downward with respect to the turning chute. Device swivel chute.

  (7) In the operation method of the blast furnace provided with the turning chute of the bellless type furnace top charging device for a blast furnace according to any one of (1) to (6), when the raw material is charged, the turning direction of the turning chute A method of operating a blast furnace, characterized by adjusting any one or two or more of the swirl speed and the tilt angle to adjust the deposition distribution of the raw material and control the gas flow in the furnace.

  According to the present invention, since the repulsion plate is provided only on one side of the tip of the turning chute, the repulsion plate can be reduced in size and weight, and the weight of the turning chute can be reduced. As a result, the mechanical strength of the turning chute support mechanism can be improved, and the increase in the equipment cost accompanying the increase in the output of the tilting motor and the turning motor in the turning chute control mechanism can be suppressed, and cost saving can be achieved.

  In addition, since the rebound plate is provided only on one side of the tip of the swivel chute, the degree of freedom to change the material fall trajectory is increased by changing the swivel direction and swivel speed, and finer material distribution control is performed compared to the conventional method. be able to. As a result, the distribution of raw materials in the blast furnace and the instability of furnace conditions due to poor raw material charging control are eliminated, the number of wind reductions can be reduced, and stable blast furnace operation can be continued. As the amount increases, the reducing material ratio decreases.

It is a figure which shows typically the aspect of the turning chute of this invention. It is a figure which shows the aspect of the raw material which flows on the turning chute of this invention. It is a figure which shows the relative relationship of the repulsion board and raw material in the front-end | tip of the turning chute of this invention. (A) shows the case where the repulsion plate is on the left side of the chute tip and the turning direction is the right direction (see arrow in the figure), and (b) shows the rebound plate on the left side of the chute tip, and the turning direction Indicates the left direction (see arrow in the figure). It is a figure which shows the fall locus | trajectory of the raw material which falls to a raw material deposition layer. (A) shows the fall locus | trajectory corresponding to the relative relationship shown to Fig.3 (a), (b) shows the fall locus | trajectory corresponding to the relative relationship shown in FIG.3 (b). A furnace in the case where the chute of the present invention is swung to the side without the repulsion plate (see FIG. 3A) and the case where the chute of the present invention is swung in the direction where the repulsion plate is present (see FIG. 3B) It is a figure which shows the gas temperature inside.

  Embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows an embodiment of the turning shot of the present invention. As shown in FIG. 1, the tip 4 of a swiveling and tilting chute body 1 disposed under a vertical chute 3 just below a discharge port of a hopper (not shown) is fixed downward with respect to the longitudinal direction of the swiveling chute. The repulsion plate 2 is fixed by a support member 5 at an inclination angle.

  Although FIG. 1 shows a U-shaped cross-section turning chute with an open top, the cross section of the present invention chute is not limited to the U-shaped. The present invention chute has only to have a predetermined groove type cross section and function as a chute.

  The repulsion plate 2 has a width that covers substantially half (the left half in FIG. 1) when the tip 4 of the chute body 1 is viewed from the longitudinal direction of the chute body 1. Naturally, the repulsion plate 2 may be attached only to the right side, and the present invention is characterized in that a repulsion plate inclined downward from the front end is provided on one of the left and right sides of the front end of the turning chute.

  The operation of the turning chute of the present invention (hereinafter sometimes referred to as “the present invention chute”) will be described with reference to FIGS.

  In FIG. 2, the aspect of the raw material which flows on this invention chute | shoot is shown. The raw material 6 discharged from the vertical chute slides down on the chute body 1 and freely falls in a parabola from the chute tip. During this time, the raw material 6 does not slide down the chute surface along the longitudinal central axis of the chute body 1, but moves up to one chute side according to the turning direction and speed of the chute, Fall from the tip of the chute.

  FIG. 2 shows the case where the turning chute turns left (see the arrow in the figure), but the raw material rises along the right chute side, and finally from the tip of the chute. It falls (see black part in the figure). In addition, if the turning speed is high, the degree of the raw material rises.

  FIG. 3 shows the relative relationship between the rebound plate and the raw material at the tip of the turning chute according to the present invention. FIG. 3 (a) shows a case where the rebound plate is on the left side of the chute tip and the turning direction is the right direction (see arrow in the figure), and FIG. 3 (b) shows the rebound plate on the left side of the chute tip. Yes, the case where the turning direction is the left direction (see the arrow in the figure) is shown.

  In the case of raw material charging that maintains the relative relationship between the rebound plate and the raw material shown in FIG. 3A, most of the raw material falls into the furnace after colliding with the repellent plate. On the other hand, in the case of raw material charging for maintaining the relative relationship between the rebound plate and the raw material shown in FIG. 3B, most of the raw material does not collide with the repellent plate and falls into the furnace.

  When the turning chute is turned, the degree of the raw material rising on one side of the chute depends on the turning speed of the turning chute. As a matter of course, the higher the turning speed, the larger the rising degree.

  FIG. 4 shows the fall trajectory of the raw material falling to the raw material deposition layer in the furnace. 4 (a) shows a material fall trajectory corresponding to the relative relationship shown in FIG. 3 (a), and FIG. 4 (b) shows a material fall trajectory corresponding to the relative relationship shown in FIG. 3 (b). Show.

  From FIG. 4, the raw material fall trajectory corresponding to FIG. 3 (a) falls more vertically than the raw material fall trajectory corresponding to FIG. 3 (b), and the dropping point moves to the furnace center. I understand that. That is, the fall trajectory shown in FIG. 4A is substantially the same as the fall trajectory when the repulsion plate is provided on the entire surface of the chute tip, and the fall trajectory shown in FIG. The fall trajectory is substantially the same as the fall trajectory when not provided in the case.

  As described above, by providing a rebound plate only on one side of the chute tip and adjusting the turning direction and speed of the chute, the rate at which the raw material collides with the repelling plate can be changed, and the falling trajectory of the raw material can be changed. Can be controlled.

  Thus, in the present invention, even if the mounting angle of the rebound plate is constant, the degree of freedom of the raw material charging mode is increased, and by controlling the turning direction and speed of the chute, and further, the tilt angle of the chute body The raw material distribution in the furnace can be accurately adjusted by changing the raw material trajectory, the falling angle, and the dropping position (charging position).

  Further, according to the chute of the present invention, even if the mounting angle of the rebound plate is constant, the material falling angle and landing point (charging position) can be changed, so that the raw material is the target position on the raw material deposition surface in the furnace. In addition, it can be reliably charged. These are significant effects based on the features of the present invention.

  According to the present invention, in addition to the above effects, the rebound plate provided at the tip of the turning chute does not need to cover the entire tip, so the rebound plate can be reduced in size and weight, and thus covers the entire tip. Compared to the conventional swivel chute in which a rebound plate is installed, not only the rebound plate body but also the overall weight including the attached members can be greatly reduced.

  As described above, if the increase in the weight of the turning chute can be suppressed, the turning chute can be stably operated without strengthening the support mechanism of the turning chute or increasing the output of the tilting motor. .

In an embodiment to be described later, a rebound plate at an angle of 30 degrees downward from the center so as to cover the left half (or right half) from the center of the chute body having a length of 1.0 m and a width of 0.5 m. However, the rebound plate of the chute of the present invention preferably has the following range.
(a) Width of rebound plate: 40-60% of inner width of tip of swivel chute
(b) Position where the rebound plate is attached: Position where it intersects with the extension line on either the left end or the right end inside the turning chute
(c) Rebound plate mounting angle: 15-45 ° downward with respect to the turning chute

  If the width of the repulsion plate is too large, an operation for reducing the amount of raw material that collides with the repulsion plate cannot be performed sufficiently, and the weight of the turning chute increases. On the other hand, if the width of the rebound plate is too small, the operation of increasing the amount of the raw material that collides with the rebound plate cannot be performed sufficiently.

  If a rebound plate smaller than the tip width of the swivel chute is located near the center axis of the swivel chute, the material flows out from both sides of the rebound plate, so the rebound plate is either the left end or the right end inside the swivel chute Install so as to cross the extension line.

  If the angle of the rebound plate is too large, the change of the material's fall trajectory when the swiveling direction or speed is changed becomes extreme, making it difficult to control the charging of the material with high accuracy and disturbing the uniformity of the material deposit layer. become. On the other hand, if the angle of the rebound plate is too small, the operation of applying the raw material to the repellent plate cannot be performed sufficiently, and the effect of the repellent plate is reduced.

  When the present invention chute is employed as a swivel chute for a bellless type furnace top charging apparatus for a blast furnace, one or two of the swirl direction, swirl speed, and tilt angle of the present chute is charged when the raw material is charged. By changing the above, the deposition distribution of the raw material can be adjusted, and the gas flow in the furnace can be controlled. The above control will be described.

  When segregating large raw material particles in the periphery of the furnace and increasing the gas flow in the periphery of the furnace, the present invention chute is swung to the side without the repulsion plate (see FIG. 3A). The tilt angle of the chute of the present invention is adjusted so that the in-furnace arrival point of the raw material becomes substantially the same.

  In order to suppress the particle size segregation in the periphery of the furnace and reduce the gas flow in the periphery of the furnace, the present invention chute is swung to the side where the rebound plate is located (see FIG. 3B). The tilt angle of the chute of the present invention is adjusted so that the in-furnace arrival point of the raw material becomes substantially the same.

  When the raw material collides with the rebound plate and falls, the fall trajectory is nearly vertical (see FIG. 4A), and the horizontal velocity component in the furnace wall direction is extremely small in the raw material fall speed. On the other hand, since the drop locus when the raw material falls without colliding with the repulsion plate almost draws a parabola, the horizontal velocity component in the furnace wall direction is large. This difference in the horizontal velocity component greatly affects the particle size segregation at the in-furnace point of the raw material.

  When the chute of the present invention is swung to the side without the rebound plate (see FIG. 3 (a)), most of the raw material collides with the rebound plate and drops along a vertical drop trajectory. Therefore, particle size segregation occurs from the arrival point of the raw material. That is, a raw material with a small particle size is deposited near the landing point of the raw material, and the coarse raw material rolls away from the landing point.

  Therefore, the coarse raw material is segregated outside the raw material arrival point, the air permeability in the periphery of the furnace is improved, and the amount of gas passing through the charge increases, so that the gas temperature rises.

  Conversely, if the chute of the present invention is swung in the direction of the rebound plate (see FIG. 3 (b)) and most of the raw material is dropped without colliding with the rebound plate, the horizontal velocity component in the drop speed is large. A point where the particle size of the raw material is minimized is formed outside the landing point of the raw material, and both the coarse-grained raw material and the fine-grained raw material move to the periphery of the furnace, and the particle size segregation is relatively reduced. . As a result, the gas flow in the furnace periphery is suppressed.

  A furnace in the case where the chute of the present invention is swung to the side without the repulsion plate (see FIG. 3A) and the case where the chute of the present invention is swung in the direction where the repulsion plate is present (see FIG. 3B) The gas temperature inside is shown in FIG. From FIG. 5, when the chute of the present invention is swung to the side where there is no rebound plate (see FIG. 3A), the air permeability at the periphery in the furnace is improved and the gas temperature is increased by about 50 ° C. I understand.

  In the prior art, the material landing point can be controlled by adjusting the tilt angle of the turning chute. However, according to the present invention chute, even if the tilt angle of the turning chute and the material landing point are the same, Since the horizontal speed component of the falling speed can be adjusted by controlling the turning direction and the turning speed, a suitable particle size segregation different from the conventional one can be selected during operation. This is also a remarkable effect of the chute of the present invention.

  In the blast furnace operation using the present chute, the blast furnace operation can be continued more stably by adjusting the condition of hot air blown from the tuyere together with the adjustment of the distribution of the raw material accumulation by the present chute.

  Next, examples of the present invention will be described. The conditions in the examples are one example of conditions used for confirming the feasibility and effects of the present invention, and the present invention is based on this one example of conditions. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
A rebound plate with a length of 1.0 m and a width of 0.5 m is installed at the tip of a turning chute with a length of 4.0 m and a width of 1.0 m at 30 ° downward so as to cover the left half from the center of the chute tip. The chute of the present invention was manufactured. The weight of the rebound plate is 500 kg, which is about half the weight of the rebound plate that covers the entire tip of the conventional chute.

The chute of the present invention was placed at the top of a bellless blast furnace having an internal volume of 3273 m ³ , and the blast furnace operation was performed while controlling the raw material charging. For comparison, a blast furnace operation (Comparative Example 1) using a turning chute without a repulsion plate and a blast furnace operation (Comparative Example 2) using a turning chute provided with a repulsion plate covering the entire front end were also performed.

  Table 1 shows the operation results of Examples of the present invention, Comparative Example 1 (no repulsion plate), and Comparative Example 2 (using a rebound plate covering the entire shoot tip of 1.0 m × 1.0 m) for one month. The average data is shown. In either case, the turning direction of the turning chute was changed as needed. Moreover, in any case, the turning speed was changed at any time within the range of 6 to 10 rpm.

  In the embodiment of the present invention, high-precision and stable material distribution control is performed, so that the stabilization of the blast furnace operation is achieved, and as shown in Table 1, the number of times of wind reduction is smaller than that of Comparative Example 1 (without repulsion plate). Significantly reduced, the amount of brewing increased, and the ratio of reducing material decreased.

  In the embodiment of the present invention in which the charging mode in which the raw material does not collide with the repelling plate can be selected, the degree of freedom of the charging mode is increased, so compared with Comparative Example 2 (covering the entire tip with the rebounding plate), Fine control is possible, and better operational results are obtained.

  As described above, according to the present invention, (p) the mechanical strength of the turning chute support mechanism is improved, and the increase in the equipment cost associated with the output of the tilting motor and the turning motor in the turning chute control mechanism is suppressed. Cost reduction can be achieved. (Q) The degree of freedom to change the material trajectory is increased by changing the turning direction and speed, and finer material distribution control than before can be performed. As a result, (r) the fluctuation of the raw material distribution in the blast furnace and the instability of the furnace condition due to poor raw material charging control are eliminated, the number of wind reductions is reduced, and stable blast furnace operation can be continued. As a result, the output amount increases and the reducing material ratio decreases. Therefore, the present invention has high applicability in the steel industry.

DESCRIPTION OF SYMBOLS 1 Chute body 2 Rebound plate 3 Vertical chute 3 'Tip of vertical chute 4 Tip 5 Support member 6 Raw material 7 Raw material deposit

Claims (7)

  In the turning chute of the bellless type furnace top charging device for a blast furnace, a repulsion plate inclined downward from the tip is provided on either one of the left and right sides of the tip of the turning chute having a groove-shaped cross-section with an open top. A swivel chute for a bellless furnace top charging device for blast furnaces.   In the swivel chute of the bellless type furnace top charging apparatus for blast furnace, a repulsion plate inclined downward from the tip is provided on either one of the left and right sides of the tip of the swivel chute having a U-shaped cross-section with an open top. A swivel chute for a bellless furnace top charging device for blast furnaces.   The swivel chute of a bellless type furnace top charging device for a blast furnace according to claim 1 or 2, wherein the swivel chute is capable of changing a turning direction, a turning speed, and a tilt angle.   The swivel chute of the bellless type furnace top charging device for a blast furnace according to any one of claims 1 to 3, wherein a width of the rebound plate is 40 to 60% of an inner width of a swivel chute tip. .   The bellless furnace for a blast furnace according to any one of claims 1 to 4, wherein the mounting position of the rebound plate is a position that intersects with an extension line of either the left end or the right end inside the turning chute. A turning chute for the top charging device.   The turning angle of the bellless type furnace top charging device for a blast furnace according to any one of claims 1 to 5, wherein a mounting angle of the repulsion plate is 15 to 45 ° downward with respect to the turning chute. .   In the operation method of the blast furnace provided with the turning chute of the bellless type furnace top charging device for a blast furnace according to any one of claims 1 to 6, when charging the raw material, the turning direction of the turning chute, the turning speed, And the blast furnace operating method characterized by adjusting any one or two or more of tilt angles, adjusting the deposition distribution of the raw material, and controlling the gas flow in the furnace.