JPH0585826B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sintering machine used in a steel manufacturing process. In general, a so-called sintering machine for sintering fine ore to an appropriate size as raw material for a blast furnace in the steel manufacturing process is a so-called continuously moving grate downward suction type sintering machine equipped with one system of main exhaust pipes 7 as shown in Fig. 1. Dwight Lloyd type sintering machines are often used. In this Dwight Lloyd type sintering machine, the sintering raw material supply devices 3, 4 and the ignition furnace 2 are arranged at predetermined positions near the ore feeding section 1A of the pallet 1, which is a continuously moving grid, and the ore discharge section 1B at the other end. The pallets 1, which are connected in a chain, are driven in the direction of arrow 1D at a speed of 1 to 5 m/min by a sprocket wheel 1C of a sintering raw material feed section 1A. The sintering raw materials are stacked and charged onto the pallet 1, ignited by the ignition furnace 2, and then discharged through the air discharge branch pipes 6, 6 through the air boxes 5, 5, . . . arranged along the lower edge of the pallet 1. . . . Forced air is sucked downward through the main exhaust pipe 7, the dust collector 8, and the main exhaust fan 9, and sintering progresses while reaching the ore discharge section 1B. Conventionally, the ore feed section 1 of this Dwight Lloyd type sintering machine
Although the air volume distribution due to forced air intake between A and the ore discharge section 1B has a great influence on the operation of the Dwight Lloyd sintering machine, it is difficult to control it properly, so it is generally Sintered ore was produced by sintering by forced air intake with a constant suction negative pressure over the entire length in the longitudinal direction. However, in this conventional method, the air volume is excessive in the part of the sintered layer that has been fired and has good air permeability, and firing is performed with the minimum air volume, which is inferior from the viewpoint of energy saving. Furthermore, the firing cannot be arbitrarily controlled, and the upper layer of the sintered layer has the disadvantage of deterioration in quality and poor yield. Therefore, in order to solve the above-mentioned drawbacks, a method for producing sintered ore using air volume control (Japanese Patent Application Laid-Open No. 1983-1999) has been proposed.
118201) was proposed. This conventional method increases the amount of added moisture to improve air permeability, and then reduces the suction air volume at the initial stage of firing to improve the quality of the upper layer. Rapid cooling of the upper layer of the initial sintered ore was prevented, and cold strength and yield improved. The Dwight Lloyd type sintering machine used in this conventional method is one that controls the opening of dampers 11, 11... provided in each wind box as shown in Fig. 2, or one that controls the opening of dampers 11, 11... as shown in Fig. 3. A multi-fan system was proposed in which each wind box was equipped with exhaust fans 9B, 9B, etc. The former is damper 1
The air volume is controlled by opening and closing of 1, 11..., and the exhaust air energy (air volume x wind pressure) is not reduced.
It has the disadvantage of being uneconomical, and the latter requires a large number of 10 to 25 exhaust fans 9B, 9B..., resulting in high equipment costs, and furthermore, it is difficult to adopt due to physical constraints. Ivy. In addition, measures to improve the quality of the upper layer of sintered ore on pallet 1 include adding a large amount of coke to the upper layer, but a multistage charging method has been proposed as a method for segregation of coke in the layer thickness direction. It was done. However, this segregation charging method is determined by the mixing process of the sintering raw materials, etc., and this multistage charging method requires a separate line of mixing equipment for each layer instead of the conventional one line, which increases equipment costs. There was a drawback. The present invention was proposed to solve the above-mentioned drawbacks, and it reduces suction negative pressure as much as possible in the initial and final stages of calcination immediately after ignition, increases the suction negative pressure in the middle stage, and produces sintered ore at a low cost. The purpose of the present invention is to provide a sintering machine that can improve quality and yield, reduce exhaust air power, and efficiently recover sensible heat of sintered ore. The present invention is established based on the following findings. In the production of sintered ore, when forced air is drawn in at a constant suction negative pressure, the airflow resistance of the sintered layers stacked on pallet 1 is low in the early stage of sintering, so the amount of passing air increases, and the upper layer of about 100 mm thick has a sudden increase in air flow. Firing is performed, and the heat retention effect is not achieved, resulting in rapid cooling cracks and problems in terms of quality and yield. As a method for improving the quality of the upper layer of sintered ore on the pallet 1, the firing of the upper layer is progressed relatively slowly in order to prevent the high temperature holding time from decreasing due to rapid cooling of the upper layer. In other words, when firing the upper layer in the early stage immediately after ignition, the suction negative pressure should be reduced as much as possible, and in the final stage of firing, that is, just before or near the firing completion point, the ventilation resistance is reduced and the suction air volume increases. The method of reducing the suction negative pressure from the beginning and increasing the suction negative pressure in the medium term from the viewpoint of ensuring productivity will contribute to quality improvement and reduction of exhaust power. The gist of the present invention is to divide the wind box group into three in the longitudinal direction of the pallet of the sintering machine, and to control the suction negative pressure in response to the firing reaction of the sintered layer for each of the divided wind box groups. . DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments with reference to the drawings. In a Dwight Lloyd type sintering machine having one system of main exhaust pipes 7 as shown in Fig. 4, pallets 1 are used for the initial stage 1X, middle stage 1Y, and final stage 1Z of the firing reaction.
It is divided into three zones (,,) corresponding to the following. Sealing devices 11A, 11B are provided between the zones and at both ends thereof to prevent air leakage by eliminating communication between the zones or contact with outside air, and to maintain a suction negative pressure difference between the wind box groups 51, 52, 53. 11
C, 11D are arranged. Further, a partition plate 11 is provided on the main exhaust pipe 7 corresponding to the sealing devices 11B and 11C.
E, 11F is installed, divided into three in the same way, and the main exhaust pipe 7
Main exhaust pipes 7B and 7C of separate systems are connected to zone 7-2 and zone 7-3, respectively. Furthermore, the main exhaust pipe 7B has a dust collector 8B and a main exhaust fan 9.
It is connected to the desulfurizer 10A via the main exhaust pipe 7.
C is the desulfurizer 1 via the dust collector 8C and the main exhaust fan 9D.
Connected to 0B. With this, the wind box 5, 5...
..., the main exhaust pipe 7 is completely divided into the -th zone, and the wind box groups 51 and 53 of the first and second zones are respectively connected to separate low suction negative pressure main exhaust fans 9 and 9D, and the main exhaust pipe 7 of the second zone is The wind box group 52 is connected to the main exhaust fan 9C with high suction and negative pressure. In addition, when the main exhaust fans 9 and 9D are made to have the same suction negative pressure as shown in Fig. 6, two levels of suction negative pressure
Applied to the first implementation method of H ₁ and H ₃ , and further,
By making the main exhaust fan 9D have a lower suction negative pressure _H4 compared to the main exhaust fan 9, the 12th
The suction negative pressure distribution shown in the figure is obtained and applied to the second implementation method of three-level suction negative pressure. As a result, in addition to the effects achieved by the first implementation method, it is possible to reduce the exhaust air power and prevent the temperature of the sintered ore from decreasing. Next, an implementation method using this embodiment will be explained. As shown in Fig. 5, initial stage 1 of firing the sintering raw material
Since the ventilation resistance is low in X, the suction negative pressure is set low, the amount of suction air passing through the sintered layer is reduced, and gradual firing is achieved to obtain a heat retention effect.
In addition, in the so-called middle firing stage 1Y, from the end point of the initial firing stage 1X to the vicinity of the firing completion point, a wet zone is generated in the sintered raw material layer, so the ventilation resistance becomes high, which increases the suction negative pressure and reduces the suction air volume. Aim to increase. In this middle stage of firing 1Y, even if the suction negative pressure is increased, the passing air is preheated by the upper part of the sintered layer, and there is no problem in terms of heat retention effect, quality, or yield. Therefore, this middle period 1
In Y, the suction negative pressure is increased from the viewpoint of improving productivity. Furthermore, after the firing completion point, which is the end point of the middle stage Y, in the final stage 1Z, which reaches the ore discharge section 1B, firing is almost completed and the ventilation resistance has become low, and the suction increases as the ventilation resistance decreases. By lowering the negative pressure and reducing the suction air volume, it is not necessary to maintain or increase the suction air volume at the same level as in the normal operation of the conventional method. FIG. 6 shows the suction negative pressure distribution according to the first implementation method using this embodiment. In the initial firing stage 1X, that is, in the initial stage 1X immediately after ignition by the ignition furnace 2, a lower suction negative pressure _H1 is set compared to the suction negative pressure level _X2 of the conventional method, and in the middle stage of firing 1Y, the suction negative pressure H of the conventional method is set. Set a higher suction negative pressure _H3 compared to ₂ . In addition, in the final firing stage 1Z, the initial stage 1X
Set the same suction negative pressure _H1 . Next, the progress of firing in the sintered layer is conceptually shown in FIGS. 7 and 8 for each of the conventional method and the present method. In conventional methods, such as that shown in FIG. 7, the combustion and cooling processes proceed at a substantially constant rate. On the other hand, in the present method, as shown in FIG. 8, firing progresses at different speeds of the combustion and cooling processes in each of the initial stage 1X, middle stage 1Y, and final stage 1Z. At this time, in this implementation method,
Since the combustion and cooling processes of the upper layer of the sintered layer proceed slowly, the high temperature holding time can be extended compared to the conventional method, and as shown in Table 1, the quality and yield are improved. Furthermore, in the middle stage of firing 1Y, a high level of suction negative pressure _H3 is set to increase the reaction rate and improve productivity. Furthermore, the final stage of firing 1
In Z, the air permeability is good and the amount of exhaust air increases rapidly. Therefore, energy saving can be achieved by lowering the suction negative pressure to the _H1 level and reducing the amount of exhaust air. Furthermore, supercooling of the sintered ore is suppressed, and the temperature of the sintered ore in the ore discharge section 1B of the sintering machine can be increased. Therefore, the energy recovered by sensible heat recovery equipment in the next step (not shown) is increased. Furthermore, during the sintering process, the sulfur contained in the sintering raw materials, coke, etc. is oxidized as it burns and becomes SOx.
It is discharged as. This SOx emission pattern is shown in Figure 9 in this implementation method.
The part with high SOx concentration is mostly included in mid-phase 1Y, which is a high suction and negative pressure zone. This is consistent with the already proposed partial concentration desulfurization method using a Dwight Lloyd sintering machine equipped with a desulfurization device.
By desulfurizing the exhaust gas in mid-term 1Y, which is the high negative pressure zone, SOx can be removed with high efficiency, increasing the amount of SOx removed by the desulfurization equipment and reducing the amount of gas to be processed. can. Therefore, it is advantageous in terms of both pollution control and reduction of desulfurization costs. Next, the exhaust gas temperature distribution according to the present method and the conventional method is shown in FIG. 10, and the exhaust gas amount distribution is shown in FIG. 11. From this result, the exhaust air energy was calculated by integrating the product of the exhaust gas amount and suction negative pressure for each time, and the experimental results of quality and yield were determined as follows.
Shown in the table. However, the numbers in the table are average values. As is clear from Table 1, the exhaust air energy is reduced by about 9% in this method, and the yield of the upper layer, falling strength (SI), and reduction pulverization rate (RDI) are also lower in this method. The first implementation method using . In addition, ore discharge section 1B
The temperature of the sintered ore increased by approximately 40°C in the case of this method. Further, as is clear from Table 1, for the middle and lower layers, the yield, drop strength (SI), and reduction in powderization rate (RDI) were almost the same between the conventional method and the present method. Next, a second implementation method using an embodiment of the method of the present invention, in which three levels of suction negative pressure are set, will be described. FIG. 12 shows the suction negative pressure distribution. This implementation method is almost the same as the first implementation method with two levels of negative pressure _shown in _FIG . This will further reduce wind energy (exhaust wind power) and prevent a drop in sintered ore temperature. As explained above, the present invention reduces the exhaust power at low cost in the main exhaust fan, improves the quality and yield of sintered ore products, increases the amount of heat recovered by the sensible heat recovery equipment, and furthermore reduces the amount of SOx removed. This has the effect of greatly contributing to reducing the unit production of sintered ore, such as increasing the amount of carbon dioxide and reducing desulfurization costs. 【table】

[Brief explanation of the drawing]

Figure 1 is a configuration diagram of a conventional Dwight Lloyd sintering machine with one main exhaust pipe system, Figure 2 is an explanatory diagram of a conventional Dwight Lloyd sintering machine with an air volume damper control system, and Figure 3 is An explanatory diagram of a conventional multi-fan Dwight Lloyd sintering machine, FIG. 4 is a configuration diagram of an embodiment of the present invention, and FIG. 5 is an illustration of an implementation method using an embodiment of the present invention shown in FIG. A conceptual diagram, FIG. 6 is an explanatory diagram of the suction negative pressure distribution of the first implementation method using the embodiment of FIG. 4, FIG. 7 is an explanatory diagram of the state of the sintered layer according to the conventional method, and FIG. Figure 9 is an explanatory diagram of the state of the sintered layer according to the method shown in Figure 6. Figure 9 is an illustration of the exhaust gas temperature and SOx concentration distribution according to the method shown in Figure 6. Figure 10 is the exhaust gas temperature distribution according to the conventional method and the method shown in Figure 6. An explanatory diagram, FIG. 11 is an explanatory diagram of the exhaust gas amount distribution according to the implementation method of FIG. 6, and FIG. 12 is an explanatory diagram of the suction negative pressure distribution of the second implementation method using the embodiment of the present invention shown in FIG. It is. 1... Pallet, 5... Wind box, 6... Exhaust branch pipe, 7... Main exhaust pipe, 8B, 8C... Dust collector,
9,9B,9C,9D...Main exhaust fan, 51,5
2,53...Wind box group.

Claims (1)

[Claims] 1. A plurality of wind boxes arranged in the longitudinal direction of the pallet, a wind discharge branch pipe connected to each of the wind boxes, and the exhaust air from each wind discharge branch pipe is discharged through the main wind discharge pipe. In a sintering machine equipped with an air exhaust fan, the pallet is divided into three sections corresponding to the firing reaction of the sintering raw materials, and a sealing device is installed to prevent air leakage between the sections, and the main exhaust pipe is connected to the pallet. A sintering machine characterized in that the main exhaust pipe is divided into three sections corresponding to the sections, and an exhaust fan is provided for each section of the main exhaust pipe.