JP5018157B2 - Rotating chute for bellless type furnace top charging equipment for blast furnace - Google Patents

Description

  The present invention relates to a turning chute of a bell-less furnace top charging device for a blast furnace.

  In the blast furnace, the iron source ore and the reducing material coke (hereinafter these ores and coke are collectively referred to as raw materials) are layered alternately by the charging equipment installed at the top of the furnace. It is inserted.

  And by burning and consuming the coke in front of the tuyere with heated air blown from the tuyere existing in the lower part of the furnace, the charging material is heated by the rising gas while gradually descending from the top of the furnace. Through the reduction reaction, the ore melts into pig iron and is discharged from the lower part of the furnace.

  In actual operation, there are various modes of operation such as blowing pulverized coal from the tuyere with the heated air, but continuous operation in countercurrent by charging the raw material from the top of the furnace and blowing air from the tuyere. Is the basic principle.

  In the operation of a blast furnace, it is important to efficiently perform the reduction reaction of the ore and to suppress the ventilation resistance of the gas rising in the furnace to a low level. These operations to control the reaction efficiency and ventilation resistance in the blast furnace include the control of the ore layer thickness and coke layer thickness at the top of the blast furnace furnace, and the radial distribution control of the coke and ore particle size, that is, charging. It is object distribution control.

  By the way, in recent blast furnaces, instead of the bell type charging device, the bellless type charging device equipped with a swirl chute with a greater degree of freedom of charge distribution control is used as the raw material charging device provided at the top of the furnace. Has been. The reason for this is that the swivel chute can control the distribution of various charges compared to the bell-type charging device by changing the rotation speed and the inclination angle with respect to the vertical downward direction.

  In the blast furnace equipped with the bell-less charging device, as shown in FIG. 13, the raw material charged into the furnace is conveyed to the top of the furnace by the belt conveyor 1 and temporarily stored in the top hopper 2. When the raw material 7 stored in the furnace top hopper 2 is charged into the blast furnace 6, it passes through the lower part of the furnace top hopper 2 and moves to the collecting hopper 3. The raw material 7 that has moved to the collecting hopper 3 falls on the vertical chute 4 provided at the lower center of the collecting hopper 3, passes through the turning chute 5 provided at the outlet, and is charged into the blast furnace 6.

  At that time, the raw material is accelerated in the furnace radial direction by gravity and centrifugal force in the turning chute, and has an angle with respect to the downward cross section of the turning chute by the action of the Coriolis force by the turning movement of the turning chute. Move while swinging up. Accordingly, the raw material that has left the turning chute is charged into the blast furnace while drawing a locus determined from the position and speed when the turning chute is released.

However, in blast furnace operation, as disclosed in Patent Document 1 and Patent Document 2, the layer structure formation phenomenon of the charge varies depending on disturbance factors such as the gas flow in the furnace and the descending situation of the raw material in the furnace. Because it receives, it tends to become unstable. In particular, in a blast furnace equipped with a bell-less charging device, it is directly affected by the discharge behavior of the raw material from the top hopper that supplies the raw material. Even if the physical properties (configuration, cold strength, etc.) are controlled uniformly, there is always some variation. For this reason, especially in the furnace center part with a small charging area, it becomes a disturbance factor which appears as a big fluctuation | variation of the layer thickness of a charging raw material, and there exists a tendency for instability to increase.
Japanese Patent Publication No. 7-5941 Japanese Patent No. 2828098

  It is therefore necessary to absorb such fluctuations and optimize the charge distribution. Therefore, in recent years, the resistance to ventilation in the furnace has been increasing due to the high pulverized coal ratio operation and the deterioration of the raw materials, and the importance of the optimization of the charge distribution control is increasing more and more.

As such a charging device for optimizing the distribution of the charged material, a technique of providing a repulsion plate at the tip of the turning chute has been proposed. Patent Document 3 discloses a method of improving the controllability of the charge distribution by providing a repulsion plate at the tip of the turning chute and bringing the drop trajectory of the raw material close to vertical drop.
Japanese Utility Model Publication No. 5-37948

Similarly, in Patent Document 4, a rebound plate or a half-divided conical rebound plate is provided at the tip of the swivel chute so as to collide only with the upper layer flow of the raw material. A method of improving controllability of the charge distribution by disposing a polygonal repulsion plate at the tip of the turning chute is disclosed. Furthermore, Patent Document 6 discloses a method for improving the controllability of the charge distribution by providing a repulsion plate with which the raw material collides with the tip of the turning chute and an auxiliary chute having side plates on both sides thereof.
JP-A-9-249907 JP-A-11-29805 JP-A-11-1709

According to the techniques disclosed in these Patent Documents 3 to 6, it is possible to control the fall trajectory of the charge.
Non-Patent Document 1 discloses a cylindrical conical turning chute. Even with such a turning chute, the fall trajectory of the charge can be controlled.
Toshiyuki Nasu, “Ishikawajima Harima Technical Report” Vol. 26 (1986), pp. 57-60

  However, all of the above-mentioned techniques provide a heavy load at the tip of the turning chute, so that the load on the turning drive device is large, and depending on the inclination angle of the turning chute, it does not collide with the repulsion plate provided at the tip of the turning chute. There is a case.

  Further, the technology of Non-Patent Document 1 is that the resistance at the tip of the turning chute is large due to the tapered shape, and if the charging speed exceeds a certain limit, the raw material is opened at the opening of the raw material supply unit from the vertical chute to the turning chute. Overflow, clogging, etc. occurred, and there was a limit as a means for controlling the charge distribution.

  Problems to be solved by the present invention are that, in the techniques disclosed in Patent Documents 3 to 6 and Non-Patent Document 1, the mechanical load on the swing drive device increases, and depending on the tilt angle of the swing chute, There is a case where it cannot be controlled so that the fall width of the sheet becomes small. In addition, in the technique disclosed in Non-Patent Document 1, when the charging speed exceeds a certain limit, overflow of the raw material or clogging occurs at the opening of the raw material supply unit from the vertical chute to the turning chute. It is.

  In order to solve the above-mentioned problems, the present invention focuses on reducing the width in the furnace radial direction (hereinafter referred to as the “falling width”) of the dropping trajectory of the raw material, and various studies are made on the shape of the turning chute. It was made based on the repeated results, and the summary is as follows.

The swivel chute of the bellless type furnace top charging device for the blast furnace of the present invention,
The distribution of charges such as stabilization of the deposition shape of the material at the top of the blast furnace layer and localization of the deposition position of a specific material without requiring significant capital investment and without causing overflow or clogging of the charged material. To optimize
It has a grooved cross section with an open top,
The main feature is that it is composed of a base end portion having a uniform cross-sectional shape and size, and a tip end portion that gradually becomes smaller in cross section than the base end portion. .

  In the present invention, since a heavy object such as a repulsion plate is not provided at the tip of the turning chute, the load on the turning drive device can be reduced, and the cost can be reduced. In addition, the present invention has a swing-up angle suppression and deceleration mechanism near the tip of the turning chute, and does not cause overflow or clogging of the charged material, and has the effect of suppressing the fall width regardless of the inclination angle of the turning chute. Can be obtained, and can contribute to the optimization of the charge distribution.

Hereinafter, after explaining the basic concept of the present invention, the best mode for carrying out the present invention will be described in detail with reference to FIGS.
In the present invention, the inventors conducted an actual furnace filling investigation, a model experiment, etc. with respect to the width of the raw material particle group when the raw material passes through a conventional swivel chute having a groove-shaped cross section with an open top. This is based on the knowledge obtained.

  The raw material discharged from the vertical chute with a certain width reaches the turning chute and rebounds or collides with other raw material particles. Accordingly, as shown in FIG. 2 (b), the width of the raw material particle group is increased in the vicinity of the proximal end of the swirl chute, but the cross section has a groove type structure as it moves toward the distal end of the swirl chute. Therefore, the width of the raw material particle group is once reduced. However, if the raw material particles further move toward the tip side of the swirl chute, the contribution of the Coriolis force increases as the turning radius increases. Will increase.

  Accordingly, the inventors consider two areas, a region in which the width of the raw material particle group in the swirling chute is once reduced and a region in which the width of the raw material particle group is subsequently increased, reducing the width of the raw material particle group in the latter increasing region, Considering a shape that aligns the direction of particle velocity at the time of separation, the present invention described below was established.

  That is, as shown in FIG. 1, the turning chute of the present invention has a uniform shape and size in the cross section in the turning chute 11 having an open upper part and a groove-type cross section symmetrical to the vertical direction. The proximal end portion 12 and the distal end side portion 13 whose section is gradually smaller than that of the proximal end portion 12 are configured.

  In the invention example 1 in FIG. 1B, the cross section of the tip end portion 13 is made part of an ellipse so that the elliptical vertical radius R2 at the tip of the turning chute is smaller than the horizontal radius R1. In addition, the shape is gradually changed toward the tip.

  Further, in the invention example 2 of FIG. 1C, the cross section of the distal end side portion 13 is a part of a sector shape having a horizontal radius R0 of the proximal end side portion 12 of the turning chute 11 as a radius. The swing angle control unit 13b is formed on both sides of the circumferential portion 13a having the center angle 2θp, and the center angle 2θp is gradually decreased toward the tip.

  In the turning chute 11 (Invention Example 1) of the present invention shown in FIG. 1B, the ratio of the elliptical horizontal radius R1 of the tip to the horizontal radius R0 of the base end side portion is 0.7 or more. It is desirable to make it 0 or less. It is desirable that the ratio of the elliptical vertical radius R2 of the tip to the horizontal radius R1 be 0.3 or more and 0.6 or less. Further, it is desirable that the center angle θe of the elliptical tip is 220 ° or more and 280 ° or less. Furthermore, it is desirable that the dimensionless length L2 / L of the tip side portion length L2 with respect to the total turning chute length L is 0.3 or more and 0.7 or less.

  Further, in the turning chute 11 (Invention Example 2) of the present invention shown in FIG. 1 (c), the central angle 2θp at the boundary between the base end side portion 12 and the front end side portion 13 is 180 °, and the central angle 2θp of the front end is set. Is preferably 40 ° to 160 °. Further, it is desirable that the ratio Hp / R0 of the height Hp of the swing angle control part 13b formed in the tip end portion 13 to the radius R0 is 0.35 or more. Furthermore, it is desirable that the dimensionless length L2 / L of the tip side portion length L2 with respect to the total turning chute length L is 0.3 or more and 0.7 or less.

  In the present invention, by having the base end side portion 12 having the structure as described above, in the wide region from when the raw material particles are supplied from the vertical chute to when the width of the raw material particle group is once reduced, Prevents spills and overflows. Further, it becomes possible to effectively reduce the width of the raw material particle group using the groove type structure.

  In addition, in the present invention, the path of the raw material particle group is localized by making the cross section of the tip side portion 13 an elliptical shape or a part of a fan shape and gradually reducing the cross sectional area of the tip of the swivel chute toward the tip. The density of the raw material particles is increased, and the width is reduced by decelerating by collision and friction between the raw material particles.

  Further, by adopting such a cross-sectional shape of the tip of the turning chute, the raw material particles are prevented from swinging up due to the Coriolis force near the tip. In addition, by making the cross-section of the tip a part of an ellipse or a sector, the cross-sectional area can be increased compared to a shape that is simply rounded and squeezed, so there is no overflow or clogging of raw materials and it is more effective. In addition, it is possible to suppress the material falling width.

The details that have led to the establishment of the present invention will be described below.
The present invention is made by a numerical simulation based on a model experiment and a discrete element method. The numerical simulation based on the discrete element method is a calculation method in which a good correspondence is confirmed between the experimental result and the particle group motion.

  FIG. 3 shows a numerical simulation based on the discrete element method when the raw material in the furnace top hopper 2 is charged through the collecting hopper 3 and the vertical chute 4 from a conventional swirl chute having a groove-shaped cross section with an open top. It shows the motion state of the raw material.

  The inventors, by means of this numerical simulation, have used the semi-cylindrical shape of the same size from the base end side to the tip end side as shown in FIG. And the relationship between the falling width of the raw material was considered. Here, the size of the turning chute used in the numerical simulation is as shown in Table 1 below.

  FIG. 4 shows the explanation and distribution of the swing angle of the raw material in the conventional turning chute. On the base end side of the conventional swivel chute, the width of the raw material particle group is temporarily reduced immediately after being supplied from the vertical chute due to the action of the groove-type structure. Swings up and has a swing angle in the range of approximately 30 ° to 90 ° at the tip.

  FIG. 5 shows the movement state of the raw material separated from the conventional swivel chute by distinguishing the swing angle. From FIG. 5, it is considered that the raw material having a larger swing angle at the tip of the turning chute of the raw material has a larger reach distance, and the variation in the swing angle at the tip of the turning chute of the raw material is considered as a controlling factor of the fall width. Therefore, it is considered that the fall width of the raw material can be suppressed by suppressing the variation in the swing angle at the tip of the turning chute of the raw material.

  The inventors have taken into account such a phenomenon, and have established the above-described swivel chute according to the present invention in order to suppress variations in the swing angle of the raw material in the swivel chute and prevent overflow and clogging.

  Next, the results of verifying the effectiveness of the present invention through model experiments and numerical simulation based on the discrete element method will be described. A model experiment was conducted on the turning chutes as shown in Tables 2 and 3 below, and a numerical simulation based on the discrete element method was performed on this system.

  FIG. 6 is a view showing the result of the fall width at the stock level of the charged material for the turning chute of the present invention and the conventional turning chute. From FIG. 6, it can be seen that when the turning chute of the present invention is used, the fall width of the charged material can be significantly suppressed as compared with the case where the conventional turning chute is used. Here, the fall width of the charged material is based on the definition of the following formula 1. The stock level is the height of the charge surface where the charge raw material falls.

  Next, in order to optimize the turning chute of the present invention in an actual blast furnace, the tip shape of the turning chute was changed as shown in Tables 4 to 14 below, and a numerical simulation based on the discrete element method was performed.

  In an actual blast furnace, since the distribution control of the charged material in units of several hundreds of millimeters in the radial direction of the furnace is required, the present invention is based on a reduction of 20% with respect to the fall width of the conventional swivel chute shown in Table 1. The significance of the effect of was judged.

  First, the result of Invention Example 1 (FIG. 1B) in which the tip side portion 13 of the turning chute 11 is part of an ellipse will be described.

  FIG. 7 shows the ratio (R2 / R1) of the vertical radius R2 to the horizontal radius R1 at the tip of the turning chute of Invention Example 1 shown in Tables 4 to 6 and the fall width of the raw material charged from the turning chute 11. FIG.

  If the radius ratio (R2 / R1) at the tip of the swivel chute is too small, the swing-up angle due to Coriolis force increases, and the direction of the speed of the raw material particles at the tip of the swivel chute is not aligned or detached before reaching the tip. As a result, the material fall width increases.

  On the other hand, if the radius ratio (R2 / R1) is increased too much, the effect becomes small as it approaches the shape of a conventional semi-cylindrical turning chute. As a result of the numerical simulation, a significant effect was obtained when the radius ratio (R2 / R1) of the turning chute tip was 0.3 or more and 0.6 or less.

  In addition, if the ratio (R1 / R0) of the oval horizontal radius R1 to the horizontal radius R0 of the base end side portion at the tip of the turning chute is too small, the swing angle due to the Coriolis force increases, The direction of the speed of the raw material particles is not aligned. In addition, the material fall width increases due to separation before reaching the tip. As a result of the numerical simulation, a significant effect was obtained when the ratio (R1 / R0) was 0.7 or more and 1.0 or less.

Next, FIG. 8 shows the relationship between the central angle θe at the tip of the turning chute of the invention example 1 shown in Tables 7 and 8 and the fall width of the charge.
When the central angle is 180 °, some of the raw material particles exceed 180 ° due to swinging up due to the Coriolis force, so that they are separated before reaching the tip. However, if the center angle is further increased, the falling width decreases because the separation of the raw material particles can be prevented until the tip is reached. When the central angle exceeds 220 °, a significant effect is obtained.

  However, if the central angle is too large, particles existing in the vicinity of the open area at the top cause contact with each other, disturbing the particle arrangement, and a minimum value of the fall width is obtained when the central angle is between 240 ° and 260 °. Indicated. If the center angle is too large, the effect of wall friction increases, and depending on the charging speed (volume flow rate of the raw material), the possibility of overflow and clogging increases. It is necessary. According to the result of the numerical simulation, it was found that a significant effect can be obtained if the center angle of the cross-section of the turning chute tip is selected between 220 ° and 280 °.

Next, FIG. 9 shows the relationship of the fall width of the charge when the turning chute tip shape change start position of Invention Example 1 described in Table 9 and Table 10 is changed.
The longer the tip side portion of the turning chute of Invention Example 1 is, the more the fall width of the charge is reduced. When the dimensionless length of the tip side portion exceeds 0.3, a significant effect is obtained. However, if the distal end side portion is made too long, that is, if the dimensionless length of the distal end side portion exceeds 0.5, the effect of reducing the raw material width at the proximal end portion is not sufficient, so the effect of reducing the falling width of the raw material It turns out that it is in a saturation tendency. Therefore, according to the result of the numerical simulation, it was found that a significant effect can be obtained if the dimensionless length L2 / L of the tip side portion of the turning chute of the invention example 1 is 0.3 to 0.7.

  From the results shown in Tables 4 to 10 and FIGS. 7 to 9, by appropriately selecting the tip shape of the turning chute as an elliptical part as in the invention example 1 shown in FIG. It was found that the effect of suppressing an increase in the fall width of the raw material due to the action of Coriolis force can be obtained.

  Next, the result of Invention Example 2 (FIG. 1C) in which the tip side portion 13 of the turning chute 11 is part of a sector will be described.

  FIG. 10 is a diagram showing the relationship between the central angle 2θp of the fan-shaped circumferential portion at the tip of the turning chute of the invention example 2 described in Tables 11 and 12 and the fall width of the raw material charged from the turning chute 11. .

  If the central angle 2θp at the tip of the swivel chute is made too small, the raw material particles spread to the upper side of the swivel chute along the swing-up angle control unit by the Coriolis force, and the separation point of the raw material particles at the tip of the swivel chute and the direction of speed Will not be aligned, or part of the material will easily overflow from the top, increasing the raw material fall width.

  On the other hand, if the central angle 2θp is too large, the effect becomes small as it approaches the shape of a conventional semi-cylindrical turning chute. As a result of the numerical simulation, a significant effect was obtained when the central angle 2θp of the tip of the turning chute was 80 ° to 160 °.

  The effect increases as the dimensionless length L2 / L of the turning chute tip portion increases. As shown in the numerical simulation results under the conditions described in Table 13 (FIG. 11), charging is performed from the ratio (L2 / L) and the turning chute when the central angle 2θp of the turning chute tip is 120 °. This can also be seen in relation to the falling width of the raw material. From this, it can be seen that if the ratio (L2 / L) is 0.33 or more, a significant effect can be obtained.

  However, as in the case of Invention Example 1 in which the cross section of the swivel chute tip side is part of an ellipse, the tip side portion is made too long, that is, the dimensionless length of the tip side portion exceeds about 0.5. As a result, the effect of reducing the width of the raw material at the base end side portion is not sufficient, and the effect of reducing the falling width of the raw material is saturated. Therefore, according to the result of the numerical simulation, it was found that a significant effect can be obtained if the dimensionless length of the tip side portion of the turning chute in Invention Example 2 is set to 0.3 to 0.7.

  FIG. 12 shows the ratio (Hp / R0) between the height Hp of the swing-up angle control part at the tip side portion of the turning chute and the horizontal radius R0 at the base end side of the turning chute shown in Table 14 and the turning chute. It is the figure which showed the relationship of the fall width of the raw material charged from.

  If the ratio (Hp / R0) is made too small, a part of the raw material particles that are swung up are not dammed up, and are separated from the swivel chute before reaching the tip of the swivel chute, so that the effect of suppressing the material fall width becomes small. . As a result of the numerical simulation, a significant effect was obtained when the ratio (Hp / R0) was 0.35 or more and 1.0 or less.

  From the results shown in Tables 11 to 14 and FIGS. 10 to 12, by appropriately selecting the tip shape of the turning chute as a part of a sector like the invention example 2 shown in FIG. It was found that the effect of suppressing an increase in the fall width of the raw material due to the action of the Coriolis force can be obtained.

  The present invention is not limited to the above example, and it goes without saying that the embodiments may be changed as appropriate within the scope of the technical idea described in each claim.

It is a figure explaining the structure of the turning chute | shoot of this invention, (a) is a front view, (b) (c) is a right view. (A) is a perspective view of the conventional turning chute, (b) is a conceptual diagram of the width | variety of the raw material particle group in the conventional turning chute. It is the figure which showed the motion state of the raw material at the time of charging from the conventional turning chute by the numerical simulation based on the discrete element method, (a) is the figure which showed from the furnace top hopper to the vertical chute, (b) It is the figure which showed until it is inserted from a turning chute through a vertical chute. (A) is explanatory drawing of the raising angle of the raw material in a turning chute, (b) is the figure which showed distribution of the raising angle of the raw material in the conventional turning chute. It is the figure which distinguished and showed the movement state of the raw material which detach | leaved from the conventional turning chute by the magnitude of a swing-up angle. It is the figure which showed the result of the fall width | variety of the charging material about the turning chute of this invention, and the conventional turning chute. It is a figure which shows the relationship (R2 / R1) with respect to the horizontal direction radius R1 of the vertical direction radius R2 of the turning chute tip of invention example 1 described in Table 4-Table 6, and the fall width of the raw material charged from a turning chute. is there. It is a figure which shows the relationship between central angle (theta) in the turning chute front end cross section of the example 1 of invention described in Table 7 and Table 8, and the fall width | variety of a charging material. It is a figure which shows the relationship of the fall width | variety of a charging material when the turning chute tip shape change start position of the invention example 1 described in Table 9 and Table 10 is changed. It is the figure which showed the relationship between the center angle 2thetap of the fan-shaped circumference part in the turning chute tip of Invention Example 2, and the fall width of the raw material charged from a turning chute. It is a figure which shows the relationship of the fall width | variety of a charging material when the turning chute tip shape change start position of the invention example 2 described in Table 13 is changed. The ratio (Hp / R0) between the height Hp of the swing-up angle control unit at the tip side portion of the turning chute and the horizontal radius R0 at the base end side of the turning chute shown in Table 14 is charged from the turning chute. It is the figure which showed the relationship of the fall width | variety of the raw material. It is a schematic explanatory drawing of a bell-less type blast furnace charging device.

Explanation of symbols

6 Blast furnace 11 Turning chute 12 Base end side portion 13 Tip end portion 13a Fan-shaped circumferential portion 13b Swing-up angle control unit

Claims (2)

A swivel chute for a bellless furnace top charging device for a blast furnace,
It has a grooved cross section with an open top,
It is composed of two parts, a base end part having a uniform shape and size of the cross section, and a tip end part gradually reducing the cross section from the base end part ,
The tip side portion of the turning chute is
Belle furnace bell-less whose cross section is part of an ellipse and whose shape gradually changes toward the tip so that the elliptical radius R2 of the tip of the turning chute is smaller than the radius R1 in the horizontal direction Slewing chute of the furnace top charging device,
Oval at the tip of the swivel chute,
The ratio R1 / R0 of the horizontal radius R1 to the horizontal radius R0 of the base end side portion is set to 0.7 or more and 1.0 or less,
The ratio R2 / R1 of the vertical radius R2 to the horizontal radius R1 is 0.3 to 0.6,
The elliptical central angle θe at the tip of the turning chute is 220 ° or more and 280 ° or less,
The dimensionless length L2 / L of the tip end portion length L2 with respect to the total swivel chute length L, 0.3 or more, the blast furnace bell-less furnace ItadakiSo inserting apparatus according to claim to Rukoto and 0.7 Swivel chute. A swivel chute for a bellless furnace top charging device for a blast furnace,
It has a grooved cross section with an open top,
It is composed of two parts, a base end part having a uniform shape and size of the cross section, and a tip end part gradually reducing the cross section from the base end part,
The tip side portion of the turning chute is
Some cross section of the fan-shaped,
A swing-up angle control part is formed on both sides of the circumferential part of the sector-shaped central angle 2θp, and the center angle 2θp is gradually reduced toward the tip. A swivel chute,
The central angle 2θp at the boundary between the proximal end portion and the distal end portion of the turning chute is 180 °, and the central angle 2θp at the distal end of the turning chute is gradually 40 ° to 160 ° toward the tip. And reducing the central angle 2θp,
The ratio Hp / R0 of the height Hp of the swing angle control unit and the horizontal radius R0 of the pivot chute proximal end portion is 0.35 or more,
The dimensionless length L2 / L of the tip end portion length L2 with respect to the total swivel chute length L, 0.3 or more, bell-less furnace ItadakiSo inserting apparatus for blast furnace you characterized in that 0.7 or less Swivel chute.