JPS58136704A - Charging method of raw material to blast furnace - Google Patents

Abstract

PURPOSE:To control the grain size distributions of the raw materials to be supplied into a blast furnace as desired and to stabilize the operations of the furnace over a long period of time by regulating the depositing states of the raw materials in a relay storage tank and the bunker at the furnace top and discharging sequence with prescribed means. CONSTITUTION:In the stage of storing the charging raw materials to be discharged from plural raw material storage tanks 1 and a relay storage tank 3 into a bunker 6 at the furnace top with a charging conveyor 4, the depositing states of the charging raw materials in the tank 3 are regulated. Thereafter, depositing and/or discharging sequence is regulated with the flow regulating means on the bunker 6. The depositing states of the charging raw materials in the bunker 6 are regulated to the optimum grain size distributions in the radial direction of the furnace selected according to furnace conditions. Thus, the blast furnace is operated stably over a long period of time.

Description

[Detailed description of the invention]

This invention relates to a method for charging raw materials into a blast furnace, and particularly proposes a charging method suitable for obtaining an optimal particle size distribution in the radial direction of the furnace depending on the conditions inside the furnace. In the operation of a blast furnace, the radial distribution of the charges (ores, coke) at the top of the furnace is one of the main factors that directly controls the operating performance, such as furnace conditions and fuel ratio. be. Conventionally known adjustments to the charge distribution have been carried out mainly by adjusting the relationship between the coke layer thickness and the ore layer thickness in the radial direction. For example, a tank for temporary storage of raw materials at the top of the furnace (top bunker)
Using the same cylinder as an example, the amount of raw material discharged through the chute, the amount of raw material discharged from the beginning of discharge, By using the inclination of the rotating chute based on the time from The method was to adjust the thickness of the layer. It is generally believed that the radial charge distribution at the top of the blast furnace governs the radial syneresis distribution of the gas flow that ascends almost vertically within the furnace. In order to obtain the distribution, based on various information such as blast furnace operating results such as gas utilization rate, blowing pressure, and fuel ratio, as well as radial gas composition and gas temperature measured at the furnace top or shaft, the above-mentioned The charge distribution was controlled by changing the layer thickness ratio depending on the method. By the way, in a normally operated blast furnace, the raw material that falls onto the surface of the charge layer inside the furnace top slides toward the center because the shape of the surface of the charge layer is an inverted conical surface. Or have a tendency to roll and move. In particular, in the case of coke and sintered ore, the particle size range is large, so fine particles accumulate near the falling point, and coarse particles accumulate toward the central valley, so the movement direction Particle size segregation occurs in the (radial direction). Of course, this phenomenon is already known, but since the permeability of a raw material is determined by the average particle size and particle size distribution of the raw material, it is necessary to adjust the charge distribution by taking into account the above particle size segregation as well as the layer thickness distribution. is essential. However, although grain size segregation in the radial direction has been recognized as one of the important factors in adjusting the burden distribution, such grain size segregation is considered to be a calyx, and the layer thickness distribution is The charge distribution is controlled mainly by changing the
No efforts have been made to actively control grain size segregation. Conventionally, the particle size of the raw material discharged from the raw material storage tank was 1 per day.
It is customary for workers to take samples from the outlet at the bottom of the raw material storage tank several times and perform particle size analysis. Moreover, 1
In blast furnaces where charges are charged about 20 to 170 times/day, there is a large variation in the particle size of the calibration of the raw material storage tank, which has about 4 to 10 tanks, and there is also a large variation in particle size within the same tank. The above sampling was of little use in blast furnace operations.・In addition, the radial grain size segregation at the top of the furnace is
Another cause was a lack of recognition that it is as important as the conventionally known adjustment of layer thickness distribution in the radial direction. Based on the results of operational tests and various investigations in actual blast furnaces, the present invention is based on the knowledge that it is not necessarily possible to obtain the best operational results only by adjusting the radial layer thickness distribution of conventional ores and coke. This technology was developed based on the fact that good operational results were obtained by adjusting the grain size changes over time (in the order of discharge) of charges such as sintered ore discharged from the furnace top bunker. In other words, in addition to the conventionally established layer thickness distribution control in the radial direction of the furnace, the material accumulation state or discharge state in the relay storage tank or the top bunker can be adjusted to achieve the desired particle size distribution in the radial direction within the furnace according to the furnace conditions. This technology aims to meet the demand for optimal particle size segregation control by maintaining conditions convenient for charging. The configuration □, which is the gist of the present invention that can meet the above-mentioned demands, stores the charging material consisting of a plurality of raw material storage tanks and relay storage tanks in the -H furnace top bunker via the charging conveyor, and then stores it inside the furnace. When charging, it is important to store the above-mentioned charging material in the form necessary to achieve the optimum particle size distribution in the radial direction of the furnace, which is selected according to the furnace conditions, at least in the piled state of the charged material in the top bunker. The main feature lies in the method of charging raw materials into the blast furnace. FIG. 1 is a diagram showing a raw material charging system of a blast furnace equipped with a bellless charging device. A fixed amount of ores such as sinter or coke is cut out onto a collection belt conveyor 2 from a plurality of raw material storage tanks 11, and is temporarily stored in a relay storage tank 8 during transportation. At this time, within the relay storage barrel 8, a phenomenon of particle size segregation, which is often observed when supplying and discharging granular raw materials, usually occurs. FIG. 2 shows an example of sampling measurement results regarding particle size fluctuations of sintered ore discharged from raw material storage tank l. In normal blast furnace operation, 8 to 10 tanks of raw material storage tank l...
- The charged raw material discharged from the group is supplied into the relay storage tank 3, but each raw material storage tank 1... usually takes into consideration the remaining amount level and accumulation state in the tank, and 5 to 50 tons of raw materials are discharged from the group. Although the particle size of the raw material supplied to the relay storage tank 8 changes over time during discharge (differences due to the order of discharge), the particle size of the raw material supplied to the relay storage tank 8 is controlled to be within the particle size range shown in Figure 8 (a). It changes as shown by and (b). As a result, the particle size of the raw material discharge 711 discharged from the relay storage tank 8 also fluctuates. Therefore, it is transported by the charging conveyor 4 toward the blast furnace and placed in the furnace top bunker 6.
When the charging material supplied to the blast furnace is charged into the furnace, it is directly affected by the particle size fluctuations that have occurred up to that point, which makes it difficult to maintain stable blast furnace operation. . In order to avoid such phenomena, the present inventors encountered an interesting and significant blast furnace operation phenomenon. As shown in (a) and (b) of Fig. 4, the collision plate 7 installed in the top bunker 6 is located directly below the falling position shown in (b), and the other is as shown in (a). I experienced a phenomenon in which the deposition and discharge conditions of raw materials changed depending on the location, and there was a clear difference in operational performance. When the collision plate 7 is in the position shown in (a) and (b) of Fig. 4, (a) is defined as the 1st period and (b) is the 1st period, and the furnace top gas is calculated as the blast furnace operating results for each period. The component distribution is the sixth
The gas utilization rate (CO2/(CO+CO□)
X100 (%)) was good, and as a result, low fuel ratio operation could be performed. In order to investigate the change in particle size of the charging material made up of the top bunker 6 at this time, a model experiment was conducted, and the results showed that, as shown in Figure 6, there were differences in particle size fluctuation depending on the order of discharge. I found out. From the above results, the particle size of the charging material charged from the top bunker 6 to the top of the furnace constantly changes over time, and the particle size distribution formed during deposition in the top bunker 6 and the time of discharge It was found that the temperature changes in a certain pattern depending on the movement state of the raw material in the storage tank. Therefore, the present inventors proposed a method for adjusting the deposition state and discharge state in the bunker, which was disclosed in Japanese Patent Application Laid-Open No. 56-108808. We conducted an experiment and were able to establish a means of adjustment here. Next, this will be specifically explained through an experiment using a scale model of 171O. The results of the experiment are shown in Figure 8.9. FIG. 7 shows the presence or absence of a gutter-like inverted V-shaped chute 8 in the relay storage tank 8 and the presence or absence of a rectifier plate 7 in the furnace top bunker 6 at the stage of conveying from the relay storage tank 8 to the furnace top bunker 6. This shows the difference in the state of accumulation depending on the size. Note that the chute 8 is formed so that the charged raw material passes through the chute 8 (in the direction of the arrow), falls from both ends thereof, and is deposited in the tank. When this chute 8 is used, the sediment profile in the tank is deposited in an inverted conical shape with a concave center.The rectifying plate 7 installed above the outlet in the furnace top bunker 6 is a set of two plates. Now, the change in particle size when the raw material is discharged from the relay storage tank 8 is made to correspond to A and E corresponding to K in Fig. 7 (a) and (b). As shown in FIG. 8, there is a significant difference in overall fluctuations between the two □ at the initial, middle, and final stages of discharge. This is because the conditions of raw material loading in the relay storage tank 6 are different between A and E. For example, in case A, the transported raw materials are piled up in a mountain shape with a high center at the time of charging. At this time, grains of average size are located at the bottom of the cypress, while fine grains are deposited in the center, and coarse grains are deposited on the tank wall side. To explain this in more detail, if the particles in the above-mentioned piled state are discharged to the bottom of the relay storage tank 8, the change in particle size over time during discharge on the charging conveyor 4 is as shown in Fig. 8. (As shown in the figure below, at the beginning of the discharge, particles with an average diameter are cut out, then in the middle stage 1, the fine particles in the center are discharged, and at the end, the coarse particles on the side of the tank wall are cut out.) 〇On the other hand, in the case (E) of Fig. 7 (B) where the center is concave, if this is discharged onto the charging conveyor 4, the initial stage of discharge is Coarse grains are preferentially cut out, followed by fine grains on the tank wall I11!1 in the middle, then gradually average-sized grains, and finally coarse grains thinly deposited on the top layer. By changing the deposition state in the tank in this way, it is possible to automatically adjust the particle size change in the order of discharge, and the present invention will eventually address this point. In addition, in order to adjust the deposition state, for example, an inverted V-shaped chute 9 as shown in FIG. A rotatable collision plate 10 is provided at the collision plate 10, and the raw material is placed on the collision plate 10 before being supplied onto the chute 9, or the collision plate 10 is retracted as shown in FIG. Drop port 9a
It is also possible to drop it from a section to create the same piled state as before. Furthermore, as shown in FIGS. 12 and 18, the collision plate 11 forming a stone box that is slidably suspended horizontally above the furnace top bunker 6 may be used in place of the above-mentioned rotation. 1 The present invention focuses on the fact that by adjusting the deposition state in the tank as described above, the particle size distribution of the next deposited layer after discharge can be controlled, and this is applied to the furnace top bunker 6. This method is designed to control the particle size distribution of the incoming material. B-H in Fig. 9 shows that the stacking state of the raw material in the relay storage tank 8 is changed, the raw material is cut out normally and charged into the furnace top bunker 6 and deposited, and its area is changed to improve the I made some adjustments. However, for Experimental Example D1H,
Change the deposition state again as shown in Figure 7 (E),
This is an example in which the rectifying plates are arranged as shown in C and G. As can be seen from these results, it can be seen that the discharge status of fine particles and coarse particles changes depending on the shape of the rectifying plate and the accumulation state within the bunker. For example, if we take condition B as an example, the deposits inside the bunker will accumulate in the order of discharge from the relay storage tank 8 mentioned above, and when this is discharged, particles with an average diameter under the rectifying plate 7 will be deposited first, and then the particles with an average diameter under the rectifying plate will be The fine grains near the plate 7 are gradually discharged, and then the coarse grains above the cypress are gradually discharged. At least a storage tank like this. 112 It is easy to adjust the particle size distribution of the contents in the blast furnace by adjusting the deposition state in the basin or by installing a current plate either alone or in an appropriate combination. In addition, during actual blast furnace operation, the seventh
When attempting to change the pattern of discharge particle size fluctuation in order to obtain stable operation using the means shown in the figure, the charge material bunker is placed on the outlet side of the relay storage tank 8 or the inlet side of the top bunker 6. It is necessary to know in advance the change in particle size based on the order in which the particles are charged. For this reason, the particle size of the raw material discharged from the relay storage tank 8 is measured using a non-contact raw material particle size measurement method. This measurement method is performed by directly photographing the surface of the raw material layer with a TV camera, etc., and processing the image using an image processing device.
Alternatively, take a sample of a part of the raw material at the point where it is discharged, transfer it using another conveyor or other transport means, set up an appropriate place for the raw material to fall, and photograph the raw material particles with a TV camera or the like in an independent state without overlapping. However, a method is used in which the particle size is measured by image processing using an image processing device, and a method in which a laser transmitter/receiver is provided on the charging conveyor 4 and the distance between the laser transmitter and the receiver is measured. As described above, the change in the particle size of the charging raw material made up of the relay storage tank 8 is measured by a non-contact method, and based on the value, the current plate 7 installed in the relay storage tank 8 or the furnace top bunker 6 is Alternatively, use the inverted V chute 8.9 to prepare for charging so that the stacked state of charging material in the furnace top bunker 6 exhibits a desired grain size in the furnace radial direction when it is charged into the furnace. This is possible. As an extension of the present invention, even if the measurement of the particle size change is carried out on the collection conveyor 2 after the raw material storage tank and the accumulation state of the built-in raw material in the relay storage tank 8 is adjusted, the change in the particle size in the final furnace Although it is possible to adjust the particle size distribution at the top of the furnace, this method is most effective when carried out in conjunction with the adjustment of the deposition conditions in the top bunker 6. Bunker 6 volumetrically 100,771' (ore charge volume 140
An example is shown below in which the bellless blast furnace of t) was operated with ore having a particle size of 5 to 50 mm charged therein. Inside the relay storage tank! Figure 11

When the particle size change on the charging conveyor was measured using a non-contact particle size measuring device using a laser when the particles were discharged in the accumulated state shown in [A], it was found that they were in the BIIw state shown in Fig. 14. Ta. Then, the raw material was discharged inside the furnace top bunker by using a rectifier plate with a small area as shown in FIG. 7C. The particle size change at that time is 8 in Figure 15.
1 As shown by @, the fine grains were distributed toward the wall and the coarse grains were distributed toward the center of the furnace. At that time, the gas distribution was as shown by the Bl line in FIG. 16, and the operating condition of the blast furnace was such that the central flow was too strong and unstable. Therefore, the material was discharged by moving the collision plate 10 to change the deposition state in the relay storage tank as shown in FIG. 11. At this time, the particle size change of the discharged raw material is B! in Figure 14! Like a border, Figure 7 G
The particle size of the particles discharged from the furnace top bunker changed as shown in Bs@ in Fig. 15. As a result, the particle size on the furnace wall side is slightly larger than the former, and the particle size on the furnace center side is slightly smaller than the former.The gas distribution in this state is BfA I! in Figure 16. @! The operating conditions of the blast furnace have become stable, with the distribution shown in the figure below. However, after that, the particle size of the raw material on the discharge side of the relay storage tank became smaller. At this time, the furnace top gas distribution became as shown by line 88 in Figure 16, and the change in exhaust particle size became line Ba' in Figure 14. It was discharged as a large area like this. The particle size change at this time is as shown in the Ba line in Figure 15. Compared to the previous state, slightly coarser grains are distributed on the furnace wall side and slightly coarser grains are also distributed on the furnace center side, and the gas distribution is as shown in Figure 16. As a result, the operating conditions of the blast furnace could be stabilized over a long period of time with a distribution as shown in the Bg line. In this way, the present invention adjusts the stacking state of the charging raw material in the relay storage tank, and subsequently measures the particle size on the conveyor after discharge using a non-contact measuring means, and determines the stacking state of the charging raw material in the furnace top (15) bunker. The deposition and/or discharge order is controlled by rectifying means in the bunker so that the particles have the required form to achieve the optimum particle size distribution in the radial direction of the furnace, which is selected based on the particle size measurement results and the behavior of the gas distribution in the furnace. Charging is carried out while adjusting the circumference and adjusting the change in particle size over time during discharge. In the above example, the method of measuring the particle size on the outlet side of the relay storage tank to adjust the deposition condition and the order of discharge from the furnace top bunker was mainly described. Needless to say, even more fine-grained raw material charging and operation can be achieved by arbitrarily combining various storage tank accumulation conditions, adjustment of discharge order, particle size measurement, etc. As explained above, according to the present invention, the particle size distribution of the raw material supplied into the furnace can be adjusted to any level according to the operating conditions by adjusting the accumulation state of the raw material in the relay storage tank or the furnace top bunker and the discharge order. It is effective in stabilizing blast furnace operation over a long period of time. Moreover, it is possible to change the charging method in response to changes in various operational orientations, such as low fuel ratio operation and high iron output ratio operation, which are adopted depending on the socio-economic (16) situation at the time. It is possible to perform stable blast furnace operation even if the operating orientation changes. Furthermore, since the present invention measures the particle size in advance on the conveyor, the measurement results can be fed back to the raw material rectification process to arbitrarily adjust the particle size of the raw material supplied to the raw material storage tank l to a range suitable for the operation. I can do it. Therefore, it becomes easy to maintain stable blast furnace operation for a long period of time.

[Brief explanation of drawings]

Figure 1 is a route map of a raw material charging facility with a bellless charging device, Figure 2 is a graph showing the particle size distribution at the time of raw material discharge, and Figure 8 (
Figure 4 (a) and (b) are graphs showing the particle size distribution of raw materials supplied to the relay storage tank and the change in particle size in the order of discharge. Figure 6 is a graph of the top gas component distribution. Figure 6 is a graph showing the pattern of particle size change during discharge from the top bunker. Figures 7 (a) and (b) are the relay storage tank and the top bunker. Route map showing examples of various raw material accumulation states in Figure 8 (A),
(B) is a graph of particle size change of particles discharged from the relay storage tank. Figures 9 (A) and (B) are graphs of particle size change of particles discharged from the top bunker. Figures 1O and 11 (A), ( (b) is a route map showing the relationship between the chute in the storage tank, the raw material flow, and the deposition state, and (a) and (b) in Figures 12 and 18 respectively show the relationship between the chute in the storage tank, the raw material flow, and the deposition state. Fig. 14 is a graph of particle size change of the raw material discharged from the relay storage tank in the example of the present invention, Fig. 15 is a graph of particle size change of the raw material discharged from the furnace top bunker in the example, and Fig. 16 is the example. It is a graph showing the distribution of furnace top gas components at . Patent Applicant Kawasaki Steel Co., Ltd. Ward ~ Law Figure 15 ￥; is lL:q ------8゜-・-day 2 83 26-

Claims (1)

[Scope of Claims] 1. When charging raw materials consisting of a plurality of raw material storage tanks and relay storage tanks is stored in a furnace top bunker via a charging conveyor and then charged into the furnace, at least Material charging for a blast furnace, characterized in that the charging material is stored in a form necessary to achieve the optimum particle size distribution in the radial direction of the furnace, which is selected according to the furnace conditions, so that the piled state of the material is stored in the top bunker of the furnace. Method. & In a method in which charging raw materials consisting of a plurality of raw material storage tanks and relay storage tanks are once stored in a top bunker via a charging conveyor and then charged into the furnace, the accumulation state of the input raw materials in the relay storage tanks is first checked. and subsequently, a rectifying means in the bunker so that the deposition state of the charged raw material in the bunker of the furnace is in the form necessary to achieve the optimum particle size distribution in the radial direction of the furnace selected according to the furnace conditions. A method for charging raw materials into a blast furnace, characterized in that charging is carried out while adjusting the order of deposition and/or discharge and adjusting the change in particle size over time during discharge.