JP2009299155A - Apparatus and method for charging raw material to bell-less blast furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for charging a raw material to a bell-less blast furnace with which in the case of charging the raw materials into the blast furnace by using a center-feeding type raw material charging apparatus provided with an upper part hopper 1 and a lower part hopper 2 connected with a plurality of ports 3, a granular distribution in the exhausted raw material can accurately be controlled. <P>SOLUTION: The apparatus for charging the raw material to a bell-less blast furnace transfers the raw materials in the upper part hopper 1 to the lower part hopper 2 through the ports 3 by opening/closing the ports 3 and charges the raw materials in the lower hopper 2 into the blast furnace 9, wherein the ports 3 have the inclination of the dropping direction into the center direction of the lower part hopper 2 to the raw materials dropped into the ports 3 so that each raw material dropped position in the lower part hopper 2 from the upper part hopper 1 becomes the center part in the range of 0-0.3 the maximum non-dimensional radius of the lower part hopper 2. Using this apparatus for charging the raw material, the particle size distribution in a raw material accumulated layer in the lower part hopper 2 is controlled and the particle size distribution of the raw material discharged from the lower part hopper 2 into the blast furnace 9 is controlled and thus the particle size distribution of the raw material in the radius direction in the blast furnace 9 is controlled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a raw material charging apparatus and a raw material charging method for a bell-less blast furnace having a center-feed type bell-less furnace top charging apparatus in which a raw material hopper is arranged in two stages at the top and bottom of the furnace.

  As a raw material charging device for a blast furnace, a bell type was widely adopted, but instead of a bell type, there is a type of furnace top charging device that does not have a bell provided with a distribution chute that turns inside the furnace. It has been developed and used and is called a bell-less charging device.

  The bell-less charging device has a “parallel hopper type” in which raw material hoppers are installed in parallel and a raw material hopper that is installed in two stages, upper and lower, via ports etc. from the upper hopper to the lower hopper. It is known that there is a “center feed type” that supplies materials. An example of a center-feed type bell-less charging device is shown in FIG.

  FIG. 5 shows an example of a conventional center-feed type bell-less charging device, in which the bottom surface of the upper hopper 1 and the top of the lower hopper 2 are connected by four pipes 3. A turning chute 4 is installed at the top of the upper hopper 1, and the raw material charged from the top charging port of the upper hopper 1 is charged toward the side wall in the upper hopper 1 using a charging belt conveyor 5 or the like. The pipe 3 has a gate portion 6 that can be opened and closed by a mechanism such as a seal valve. The lower hopper 2 moves the raw material into the interior, raises the pressure in the hopper to the same level as the pressure in the furnace, then opens the lower discharge port 7 and turns, using a distribution chute 8 or the like whose rotation radius can be changed. The raw material is charged into the blast furnace 9 while controlling the charging position.

  In general, the center-feed type bell-less charging device is structurally simple compared to the parallel hopper type device, so the capital investment is low, and the cost for charging the charged material into the furnace is low. There is an advantage that the circumferential deviation is small and the distribution can be performed almost uniformly (see, for example, Patent Document 1).

  On the other hand, if a raw material charging device with two hoppers at the top and bottom like the center-feed type bellless device is used, the furnace height tends to be high, and the height of the device is used for reasons such as diverting existing equipment. Therefore, it is necessary to increase the diameter of the upper and lower two hoppers to secure the internal volume.

  However, by increasing the diameters of the upper and lower hoppers, the coarse and fine grains in each hopper when the raw material is received into the upper hopper or when the raw material is charged from the upper hopper to the lower hopper. The tendency to segregate is promoted. This is due to the classification effect on the slope of the raw material deposited in the hopper, and the coarse-grained raw material is more likely to roll than the fine-grained raw material, so that particle size segregation occurs in the hopper.

  When the raw material finally segregated in the lower hopper is charged into the furnace using a chute or the like, for example, as shown in FIG. The particle size distribution of the discharged raw material becomes small.

  In the blast furnace, the gas flow control in the furnace is important for stable operation, and it is directed to a sharp central flow and an appropriate furnace wall flow. When the furnace wall is sequentially charged from the furnace wall side to the center side, the coarse-grained raw material and the fine-grained raw material are deposited from the furnace wall to the middle part. As a result, it becomes difficult for gas to flow to the center, and excessive gas flows to the furnace wall, which greatly hinders stable operation of the blast furnace. Moreover, since the raw material particle size distribution in the radial direction in the furnace becomes nonuniform, it becomes difficult to control the gas flow distribution in the furnace only by the raw material charging amount.

In order to eliminate the non-uniformity of the discharged raw material particle size distribution at the time of raw material charging when using the center-feed type bell-less charging device as described above, a hollow cylinder is arranged in the lower hopper to A technology for changing the distribution of the discharged particle size when discharging to a “flat pattern, no particle size change” (see, for example, Patent Document 2 and Patent Document 3), and a plurality of ports connecting the upper hopper and the lower hopper In some cases, there is a technique for controlling the discharge particle size distribution by providing a time difference in the timing of opening each port (for example, see Patent Document 4).
JP 58-58211 A Japanese Patent Laid-Open No. 61-157604 JP-A-6-33122 JP 2005-154867 A

  Although the techniques of Patent Documents 2 to 4 are excellent techniques, in the method described in Patent Document 2, at least a device for vertically moving the hollow cylinder in the lower hopper, a structure for closing the upper end opening of the hollow cylinder, and a hollow cylinder A device for closing the upper end opening is required, the hopper structure is very complicated, and maintenance is also a problem.

  In Patent Document 3, the above structure is aimed to be simplified, but it is effective only when there is one port connecting the upper hopper and the lower hopper. In the raw material charging apparatus having a plurality of ports, Lacks effectiveness.

  In addition, the method described in Patent Document 4 for a raw material charging apparatus having a plurality of ports is a technique that controls the discharge particle size by changing the timing of opening each port, and is a very excellent technique that does not require major modification of equipment. However, it is desirable to further uniform the discharge particle size distribution. By providing a time difference in the opening timing of each port, for example, an emission particle size distribution as shown in FIG. 7 can be obtained, but in this case, it is not possible to prevent the raw material from becoming finer at the end of discharge. In addition, since the raw material charging time from the upper hopper to the lower hopper increases as a result of shifting the opening order of the ports, this technology can be used when it is desired to shorten the raw material charging time by increasing the operating rate. Is not desirable.

  Accordingly, an object of the present invention is to solve such problems of the prior art, and to load raw materials into a blast furnace using a center feed type raw material charging apparatus having an upper hopper and a lower hopper connected by a plurality of ports. It is an object of the present invention to provide a raw material charging apparatus and a raw material charging method for a bell-less blast furnace capable of accurately controlling the particle size distribution of the discharged raw material.

The features of the present invention for solving such problems are as follows.
(1) Using the upper hopper and the lower hopper connected by a plurality of ports, the raw material in the upper hopper is transferred to the lower hopper via the port by opening and closing the port, and the lower hopper A raw material charging device for charging the raw material in the blast furnace,
The raw material dropped into the port so that each raw material falling position from the upper hopper in the lower hopper is a central portion in the range of 0 to 0.3 in the maximum dimensionless radius of the lower hopper. A raw material charging apparatus for a bell-less blast furnace, which has an inclination in a direction of dropping toward the center of the lower hopper.
(2) The particle size distribution of the material discharged from the lower hopper into the blast furnace is controlled by controlling the particle size distribution in the material deposition layer in the lower hopper using the material charging device described in (1). Thus, the raw material charging method for the bell-less blast furnace, wherein the raw material particle size distribution in the radial direction in the blast furnace is controlled.

  According to the present invention, in a raw material charging apparatus having two upper and lower hoppers connected by a plurality of ports, charging into the lower hopper through the ports without complicating the internal structure of the hopper compared to the conventional method. Since the falling position of the raw material can be in the vicinity of the center of the lower hopper, it is possible to control the particle size distribution in the raw material deposition layer in the lower hopper, thereby controlling the discharge particle size distribution of the raw material charged into the furnace. . As a result, the gas flow in the blast furnace is controlled to enable more efficient blast furnace operation.

  In the raw material charging apparatus used in the present invention, at least two hoppers of an upper hopper and a lower hopper are connected by a plurality of ports (tubes), and the raw material in the upper hopper is opened through the ports by opening the ports. Vertical two-stage bellless charging with a port that connects the upper and lower hoppers at an angle where the drop position of the raw material charged through the port into the lower hopper is near the center of the lower hopper. Device. That is, the raw material dropped into the port is the lower hopper so that each raw material falling position from the upper hopper in the lower hopper is a central portion in the range of 0 to 0.3 in the maximum dimensionless radius of the lower hopper. It has an inclination in the direction of falling in the center direction. One embodiment of such a bellless blast furnace raw material charging apparatus is shown in FIG.

  In FIG. 1, the bottom part of the upper hopper 1 and the top part of the lower hopper 2 are connected by four ports 3. A turning chute 4 is installed at the top of the upper hopper 1, and the raw material charged from the top charging port of the upper hopper 1 is charged toward the side wall in the upper hopper 1 using a charging belt conveyor 5 or the like. The port 3 has a gate portion 6 that can be opened and closed by a mechanism such as a seal valve. The lower hopper 2 moves the raw material into the interior, raises the pressure in the hopper to the same level as the pressure in the furnace, then opens the lower discharge port 7 and turns, using a distribution chute 8 or the like whose rotation radius can be changed. The raw material is charged into the blast furnace 9 while controlling the charging position. The port 3 has an inclination in the direction in which the raw material dropped into the port falls in the central direction of the lower hopper, and thereby the raw material dropping position is set to a central portion in the range of 0 to 0.3 in the maximum dimensionless radius of the lower hopper. To do. The arrow shown with a dotted line is a raw material flow direction. Compared with the case of the conventional raw material charging apparatus shown in FIG. 5, the raw material falls to the center of the lower hopper.

  Such a raw material charging apparatus of the present invention can be manufactured at a low cost by modifying a conventional facility. Of course, the apparatus of the present invention can be installed when constructing a new facility.

  In the present invention, by controlling the particle size distribution in the raw material deposition layer in the lower hopper using the above raw material charging device, the particle size distribution of the raw material discharged from the lower hopper into the blast furnace is controlled, and the distribution chute is The raw material particle size distribution in the radial direction in the blast furnace can be finally controlled by using the raw material.

  An embodiment of the present invention using the apparatus of FIG. 1 will be described. In FIG. 1, the raw material charged from the top charging port of the upper hopper 1 using the charging belt conveyor 5 is charged toward the side wall of the upper hopper 1 by the turning chute 4. When the charged raw material is deposited in the upper hopper 1, a slope is formed and rolling occurs, and coarse grains that are easy to roll are distributed more in the periphery of the upper hopper 1 and segregation occurs. When the gate portion 6 is opened, the raw material in the upper hopper 1 falls and is transferred to the lower hopper 2. At this time, the angle of the port 3 connecting the upper hopper 1 and the lower hopper 2 is changed to the raw material flowing in the port 3. Is set to be near the center of the lower hopper 2, the particle size distribution in the deposited layer of the raw material falling to the lower hopper 2 is controlled. The particle size distribution of the raw material in the lower hopper in this case will be described with reference to FIGS.

  FIG. 2 schematically shows the particle size distribution in the raw material deposition layer in the lower hopper when the conventional raw material charging apparatus shown in FIG. 5 is used. The raw material supplied from the upper hopper 1 into the lower hopper 2 is deposited at the lower portion of each port 3, and a particle size distribution in the raw material deposition layer is generated at a plurality of points. That is, the raw material from the upper hopper falls at the tip of the arrow indicated by the dotted line indicating the flow direction of the raw material in FIG. As known from the Miwa formula, when particles with different particle sizes (coarse and fine) are mixed, the longer the distance (rolling distance) the particles flow after falling, the more the coarse and fine particles are separated. The segregation effect is increased, and the longer the distance from the drop position, the higher the proportion of coarse particles. Therefore, as shown in FIG. 8, at the initial stage when the raw material is supplied from the upper hopper 1 into the lower hopper 2, the raw material charging surface is 14, and coarse grains are concentrated in the central portion having a long rolling distance. Will do. As the supply of the raw material to the lower hopper 2 continues and the charging surface rises toward the charging surface 15, the difference in the rolling distance between the central portion and the inner wall surface becomes smaller. However, as a whole, the lower hopper 2 The raw material deposited in the vicinity of the inner wall surface tends to have a smaller proportion of coarse particles than the raw material deposited in the center. As a result, the particle size distribution in the lower hopper as a result is shown in FIG. 2. As shown in FIG. 2, coarse particles gather at the bottom of the deposited layer, and the coarse particles 10, medium particles 11, and fine particles 12 in the raw material deposited layer particle size. Distribution occurs. Coarse grains 10 a are deposited on the inner wall 13 side of the lower bunker 2, coarse grains 10 b are deposited at the center position, fine grains 12 are deposited at the top of the deposited layer, and intermediate grains 11 are deposited at intermediate points between the fine grains 12 and the coarse grains 10. This deposited layer is dispensed in the order of coarse particles 10b → medium particles 11 → fine particles 12 → coarse particles 10a in accordance with funnel follow-up when dispensed from the lower hopper 2.

  FIG. 3 schematically shows the particle size distribution in the raw material deposition layer in the lower hopper 2 when the raw material charging apparatus of the present invention is used. Since the raw material deposition layers supplied from the upper hopper 1 into the lower hopper 2 coincide at the bottom position of the lower bunker 2 and the raw material deposition layers supplied from the upper hopper 1 are merged, they are generated at the bottom of the deposition layer. Coarse grains 10 are generated only along the inner wall 13 of the lower hopper 2, as shown in FIG. 3, the center part is fine grains 12, the coarse grains 10 are along the inner wall 13 of the lower hopper 2, and both are in the middle region. The particle size distribution in the raw material deposition layer in the lower hopper 2 in which the medium grains 11 having an intermediate grain size are deposited is obtained. When this deposited layer is paid out from the lower hopper 2, it is paid out in the order of fine grains 12 → medium grains 11 → coarse grains 10 in the central region in accordance with the funnel follow.

  After transferring the raw material in the upper hopper 1 into the lower hopper 2, the gate portion 6 is closed, the pressure in the lower hopper 2 is increased to the same level as the pressure in the blast furnace 9, the lower discharge port 7 is opened, and the distribution chute is opened. The raw material is charged into the blast furnace 9 by (rotating chute) 8. When charging the raw material into the blast furnace 9, the center of the furnace is also provided around the furnace wall while adjusting the mass of the charged raw material by adjusting the angle (tilt angle) of the distribution chute 8 with respect to the vertical direction and turning. It is also possible to charge the battery. Normally, the raw material is charged around the furnace wall, and the tilt angle is changed stepwise while turning the distribution chute, and the latter half is charged into the furnace center. Therefore, in the conventional charging method that does not use the method of the present invention, the particle size distribution in the deposited layer of the raw material in the lower hopper 2 is formed as shown in FIG. 10b-> medium grain 11-> fine grain 12-> coarse grain 10a-coarse particles at the beginning of discharge, fine particles at the end of discharge, and coarse particles and fine particles having a particle size smaller than the coarse particles discharged at the beginning Since the harmonic average particle size at the end of discharge decreases, the raw material is charged in the vicinity of the furnace wall, fine particles are charged in the center, coarse particles in the periphery of the furnace wall, and fine particles in the center. By doing so, there is a demerit that the flow around the furnace wall becomes strong, heat loss increases, and the ventilation in the blast furnace deteriorates due to the collapse of the central flow. On the other hand, when the method of the present invention is used, since the particle size distribution in the deposited layer of the raw material in the lower hopper 2 is formed as shown in FIG. 3, fine particles 12 → medium particles 11 → coarse particles 10 Coarse grains and fine grains are discharged at the end of discharge. By using a distribution chute, the raw material is charged from the periphery of the blast furnace to the center of the furnace. Can be charged.

  Using the same equipment as shown in FIG. 1, the angle of the four ports connecting the upper hopper and the lower hopper is set so that the falling position of the raw material flowing through the port is in the vicinity of the lower hopper. The particle size distribution of the discharged raw material when charging was measured. The results are shown in FIG.

  According to FIG. 4, it becomes possible to control the discharge particle size distribution so that the initial particle size is small and the final particle size is large, and the raw materials adjusted for this particle size distribution are sequentially charged from the furnace periphery to the center. By doing so, it was found that sharp central flow and moderate peripheral flow can be controlled, which can contribute to stable operation of the blast furnace.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic of the longitudinal cross-section which shows one Embodiment of the raw material charging device of this invention. Explanatory drawing which shows the raw material particle size distribution in a lower hopper (conventional example). Explanatory drawing which shows the raw material particle size distribution in a lower hopper (invention example). The graph which shows the discharge raw material particle size distribution from a raw material charging device (invention example). The figure which shows an example of a center feed type bell-less charging device. The graph which shows the discharge raw material particle size distribution from a raw material charging device (conventional example). The graph which shows the discharge raw material particle size distribution from a raw material charging device (conventional example). Explanatory drawing which shows the raw material flow in the lower hopper of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Upper hopper 2 Lower hopper 3 Port 4 Turning chute 5 Loading belt conveyor 6 Gate part 7 Lower discharge port 8 Distribution chute 9 Blast furnace 10 (10a, 10b) Coarse grain 11 Medium grain 12 Fine grain 13 Inner wall 14 Raw material charging surface 15 Raw material charging surface

Claims (2)

Using the upper hopper and the lower hopper connected by a plurality of ports, the raw material in the upper hopper is transferred to the lower hopper via the port by opening and closing the port, and the raw material in the lower hopper is transferred to the lower hopper. A raw material charging device for charging a blast furnace,
The raw material dropped into the port so that each raw material falling position from the upper hopper in the lower hopper is a central portion in the range of 0 to 0.3 in the maximum dimensionless radius of the lower hopper. A raw material charging apparatus for a bell-less blast furnace, which has an inclination in a direction of dropping toward the center of the lower hopper.   By controlling the particle size distribution in the raw material deposition layer in the lower hopper using the raw material charging device according to claim 1, the particle size distribution of the raw material discharged from the lower hopper into the blast furnace is controlled, thereby 2. A raw material charging method for a bell-less blast furnace, characterized by controlling a raw material particle size distribution in a radial direction in the blast furnace.

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