Kneading material conveying device

Abstract

To provide a conveying device of a kneaded raw material capable of reducing a load of a drive source of a screw when conveying the kneaded raw material by a screw conveyor.SOLUTION: When the kneaded material m is charged from above the screw conveyor 2 including the one or more screws 5 and the kneaded material m is conveyed by the screw conveyor 2, the height of the kneaded material m accumulated above the screw conveyor 2 is detected by the level meter 9, and the arithmetic processing device 4 controls the operating state of the motor-operated valve 8 provided in the charging port (charging path) 10 to adjust the charging amount of the kneaded material m so that the height of the kneaded material m detected by the level meter 9 becomes a predetermined height. By this constitution, the wt. of the kneaded raw material (m) charged from above to be accumulated on the screw conveyor 2 can be reduced.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a conveying device for mixed raw materials, for example, a device for conveying mixed raw materials in a process for producing ferro-coke. [Background technology]

[0002] To efficiently operate a blast furnace, it is common to charge coke, which is produced by carbonizing coal in a coke oven, into the blast furnace. Coke in a blast furnace serves various purposes, including as a spacer to improve ventilation within the furnace, as a reducing agent, and as a heat source. In recent years, a technique for producing ferrocoke for metallurgy by mixing coal with iron ore has been developed, as described in, for example, Patent Document 1, from the perspective of improving the reactivity of coke. It is considered optional whether the ferrocoke raw material is rich in coal or rich in iron ore, but in either case, it must be agglomerated using a molding machine. Agglomeration methods include adding a binder to the raw material and molding it at room temperature to about 250°C, and thermoplastically melting the coal at a high temperature of 250°C or higher and molding it using the caking properties of the coal without adding a binder. One known example of the former method is kneading coal, iron ore, and a binder in a kneader and then molding at room temperature, as described in, for example, Patent Document 2, as described below. As the latter method, for example, as described in Patent Document 3, a method is known in which coal and iron ore are mixed, rapidly heated to 250°C or higher, and molded under pressure. The molded agglomerates are carbonized in a carbonization furnace to produce ferro-coke. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-15700 [Patent Document 2] Japanese Patent Application Publication No. 64-81889 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-53986 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, the production of ferro-coke involves the mixing process for mixing raw materials, the transporting process for transporting the mixed raw materials to a molding machine, the molding process for agglomerating the raw materials, and the carbonization process for carbonizing the agglomerated materials to obtain the ferro-coke product. Among these processes, the transporting method in the transporting process is generally a screw conveyor, which is easy to ensure airtightness, because the raw materials are hot and volatile gases such as CO are generated. A screw conveyor generally has one or more screws, and the mixed raw materials are loaded (fed) onto the screw conveyor from above and transported in the direction of the screw's forward movement by the rotating one or more screws. However, the mixed raw materials loaded from above pile up on the screw conveyor, which poses a problem: their own weight increases the load on the motor (drive source) that drives the screw.

[0005] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a conveying device for kneaded raw materials that can reduce the load on the screw drive source when transporting the kneaded raw materials using a screw conveyor. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, one embodiment of the present invention provides a raw material conveying device for kneading raw materials, which is a raw material conveying device for kneading raw materials that is loaded from above a screw conveyor having one or more screws and transports the raw material by the screw conveyor, and is equipped with: a level meter that detects the height of the raw material piled up above the screw conveyor; an electric valve that is provided in the loading path of the raw material above the screw conveyor and is capable of adjusting the loading amount of the raw material; and a control device that controls the operating state of the electric valve so that the height of the raw material detected by the level meter becomes a predetermined height.

[0007] In a further aspect of the present invention, the predetermined height is equal to or greater than two times and less than six times the outer diameter of the screw. [Effects of the Invention]

[0008] According to the present invention, by setting the height of the raw materials to be mixed that are loaded from above and piled up on the screw conveyor to a predetermined height, it is possible to reduce the weight of the piled raw materials to be mixed, thereby reducing the load on the screw drive source. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic configuration diagram of a ferro-coke production facility to which an embodiment of a conveying device for mixed raw materials is applied. [Figure 2] FIG. 2 is a detailed view of the screw conveyor installation of FIG. 1. [Figure 3] FIG. 3 is an explanatory diagram of a control sequence when the motor-operated valve in FIG. 2 is an on-off valve or a rotary valve. [Figure 4] FIG. 3 is an explanatory diagram of the axial load of the screw conveyor and the number of times the conveyor breaks down depending on the height of the raw material to be mixed in FIG. 2. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of a ferro-coke production facility to which a raw material conveying device is applied will be described in detail with reference to the drawings. The embodiment shown below is an example of an apparatus and a method for embodying the technical idea of ​​the present invention, and the technical idea of ​​the present invention is not limited to the embodiment described below.

[0011] FIG. 1 is a schematic diagram illustrating an embodiment of a ferro-coke production facility. In this ferro-coke production facility, ferro-coke is produced using a binder. The iron source material, which is a mixing material for ferro-coke, is supplied from an iron source material supply unit 11, coal from a coal supply unit 12, and a binder from a binder tank 13. The iron source material and coal are pulverized to a predetermined particle size by a pulverizer (not shown) and supplied as granular materials. For example, the coal is pulverized to a particle size of 3 mm or less, and the iron source material is pulverized to a particle size of 0.5 mm or less. For example, the blending ratio is 60 to 90 mass % coal and 10 to 40 mass % iron source material. Iron ore is primarily used as the iron source material, but iron source materials by-produced in steelworks, such as blast furnace dust, converter dust, and rolling mill sludge, may be used instead. Different brands of iron ore and coal may be used. In this embodiment, iron ore is used as the iron source material.

[0012] The pulverized raw materials supplied from the respective supply sections 11 and 12 are charged (input) into the kneader 14, and a binder from a binder tank 13 is added to the kneader 14. The binder is added from the binder tank 13 at the same time as the coal and iron ore are charged into the kneader 14, or while the coal and iron ore are being mixed by the kneader 14. Commonly used binders include soft pitch (SOP), asphalt pitch (ASP), and ferrotar (a by-product produced during the carbonization process of ferro-coke), and these binders can be used alone or in combination of two or more. The raw materials kneaded in the kneader 14 are charged (input) into a kneading hopper 3 located upstream of the conveying device 1 in the conveying direction. The upstream portion of the conveying device 1 in the conveying direction is located below the kneading hopper 3. The kneading hopper 3 has a charging port 10 for the raw material to be mixed at its top, and the raw material to be mixed is charged through this charging port 10 from above the conveying device 1. As will be described later, a screw conveyor 2 is used for the conveying device 1. The raw material to be mixed is conveyed by the conveying device 1 to an outlet 17 on the downstream side in the conveying direction, and is charged (feed) from the outlet 17 into a double roll molding machine 15. The double roll molding machine 15 is a high-pressure molding machine, and the charged (feed) raw material is molded under high pressure. The molded coal molded by the double roll molding machine 15 is charged (feed) into a carbonization furnace 16. At this time, the molded coal is passed through a sieve (not shown), and the oversized coal is charged (feed) into the carbonization furnace 16, while the undersized coal is reused as raw material.

[0013] The operating state of each piece of equipment in this ferro coke manufacturing facility is controlled by a processing device 4 such as a process computer. The processing device 4 is configured with a computer system similar to a personal computer and has advanced processing functions. Specifically, it is configured with a processor that controls the processing and a storage device that stores data, information, programs, etc. The processing performed by the processing device 4 is realized, for example, by the processor executing a computer program stored in the storage device. In this embodiment, the processing device 4 constitutes a control device that controls the height of the mixed raw material m piled up above the screw conveyor 2.

[0014] FIG. 2 is an explanatory diagram of the screw conveyor 2 and kneading hopper 3, which are the conveying device 1 of FIG. 1; FIG. 2(a) is a front cross-sectional view, and FIG. 2(b) is a right cross-sectional view. In this embodiment, a screw conveyor 2 equipped with four screws 5 arranged horizontally is used as the conveying device 1. In the screw conveyor 2, raw material is conveyed between two synchronously rotating screws 5 in the direction of the screws 5's forward movement, i.e., to the left in this example in FIG. 2(a). In this example, the raw material is conveyed by being caught between the two screws 5 on the left side and the two screws 5 on the right side in FIG. 2(b). The raw material m charged into the kneading hopper 3 through the charging port 10 is piled up in a mountain shape on the screws 5 of the screw conveyor 2 within the kneading hopper 3, as indicated by the two-dot chain line in the figure. The piled up raw material m is highest directly below the charging port 10, generally at the center of the horizontal diameter of the screws 5 of the screw conveyor 2. The higher the height of the raw material m piled up above the screw 5, the greater the weight of the raw material m below, and this weight increases the load (hereinafter simply referred to as axial load) on a drive source (not shown) such as a motor that rotates the screw 5. Therefore, in the example of Figure 2, the axial load on the two inner screws 5 in the left-right direction in Figure 2(b) is large. The upper part of the kneading hopper 3 is narrowed down to about the height of the screw conveyor 2 itself ahead in the conveying direction of the raw material m, and the height of the raw material m piled up on the screw 5 is narrowed down by this narrowed section 3a.

[0015] In this embodiment, a motor-operated valve 8 is provided in the charging path for the raw material m charged from above the screw conveyor 2, specifically in the charging port 10, to adjust the amount of raw material m charged. The motor-operated valve 8 may be, for example, an on-off valve (ON / OFF valve) that opens and closes the charging port 10 or a rotary valve that can increase or decrease the amount of raw material m charged. A level meter 9 is provided on the top plate of the mixing hopper 3 near the charging port 10 to detect the height of the raw material m piled up above the screw conveyor 2. The level meter 9 in this embodiment is preferably capable of detecting the pile height of the raw material m in a non-contact manner, and examples of such level meter 9 include a laser level meter and an ultrasonic level meter. The arithmetic processing unit 4 controls the operating state of the motor-operated valve 8 based on the height of the raw material m detected by the level meter 9, thereby adjusting the height of the raw material m piled up above the screw conveyor 2 to a predetermined height. In this way, by controlling the height of the raw material m piled up above the screw conveyor 2, the weight of the raw material m at the position of the screw conveyor 2 can be controlled, thereby making it possible to reduce the axial load of the screw 5.

[0016] Furthermore, the ferro-coke raw material m has a consolidation characteristic in that its volume shrinks when pressure is applied and does not return to its original volume even when the pressure is reduced. Therefore, as the weight of the raw material m piled up on the screw conveyor 2 increases, the consolidation of the raw material m is promoted, which causes the raw material m to stick and grow, increasing the axial load on the screw 5. Therefore, if the weight of the raw material m piled up above the screw conveyor 2 can be reduced, the consolidation of the raw material m in that area can be reduced, preventing the raw material m from sticking and growing due to consolidation and reducing the axial load on the screw 5. Furthermore, depending on the transport capacity of the raw material m by the screw conveyor 2, the pile of raw material m piled up above the screw conveyor 2 moves in the transport direction (sometimes lowering) as the raw material m is transported by the screw conveyor 2. This pile of the raw material m is clamped in the narrowed portion 3a of the kneading hopper 3, and this clamping also promotes consolidation of the raw material m. In this embodiment, the height of the pile of the raw material m in the narrowed portion 3a can be adjusted, so that the consolidation of the raw material m in this portion can be reduced, and the axial load of the screw 5 can also be reduced.

[0017] FIG. 3 shows the sequence (processing flow) for controlling the operating state of the motor-operated valve 8, which is controlled by the arithmetic processing unit 4. Here, the height of the raw material m detected by the level meter 9 is set to an L level (lower limit), an H level (adjustment value), and an HH level (upper limit), in ascending order, and an example of control of the on-off valve and rotary valve is described. When controlling the pile height of the raw material m by adjusting the amount of raw material m charged in this way, it is extremely difficult to maintain a constant height. Therefore, the height of the raw material m is controlled to fall within a predetermined range. The oval arrow in the right half of the figure indicates the transition in the height of the raw material m. In this embodiment, as shown in FIG. 2(a), the level meter 9 is located further ahead of the charging port 10 in the direction of movement of the pile of raw material m.

[0018] For example, if the motor-operated valve 8 is an on-off valve, when the on-off valve is opened and the height of the raw material m is being charged, the on-off valve is closed if the height of the raw material m exceeds the HH level. Even if the on-off valve is closed, the charging of the raw material m is not immediately stopped, so the height of the raw material m detected by the level meter 9 provided ahead of the moving direction of the pile of raw material m continues to increase slightly. However, as the pile of raw material m moves, the height of the raw material m detected by the level meter 9 gradually decreases. In this example, even if the height of the raw material m falls below the HH level and then below the H level, the on-off valve remains closed. Then, when the height of the raw material m falls below the L level, the on-off valve is opened. Even if the on-off valve is opened, the charging of the raw material m does not start immediately, so the height of the raw material m continues to decrease slightly. When the charging of the raw material m is resumed, the height of the raw material m increases, but the on-off valve remains open even when the height of the raw material m exceeds the L level and then exceeds the H level. When the height of the raw material m again exceeds the HH level, the on-off valve is closed.

[0019] On the other hand, if the motor-operated valve 8 is a rotary valve, for example, the amount of raw material m charged can be increased or decreased by controlling the rotary valve at two speeds, normal speed and low speed. Of course, if the rotary valve is stopped, the amount of raw material m charged will be zero. Here, when the rotary valve is controlled at normal speed and a large amount of raw material m is charged, if the height of the raw material m exceeds the H level, the rotary valve is switched to low speed control to reduce the amount of raw material m charged. Thereafter, if the height of the raw material m exceeds the HH level, the rotary valve is stopped and the amount of raw material m charged is set to zero. Even if the rotary valve is stopped and controlled, the charging of the raw material m is not immediately stopped, so the height of the raw material m continues to increase slightly as the pile of raw material m moves. However, thereafter, the height of the mixed raw material m detected by the level meter 9 gradually decreases, and when this height of the mixed raw material m falls below the HH level and then below the H level, the rotary valve is controlled to a low speed so that the mixed raw material m is charged little by little. Even if the mixed raw material m is added little by little, the pile of mixed raw material m continues to move, and as a result, the detected height of the mixed raw material m continues to decrease. Then, when this height of the mixed raw material m falls below the L level, the rotary valve is controlled to a normal speed. When the rotary valve is controlled to a normal speed, a large amount of mixed raw material m is charged, so the detected height of the mixed raw material m exceeds the L level relatively quickly. Then, when the height of the mixed raw material m exceeds the H level, the rotary valve is switched back to low speed control.

[0020] When the amount of raw material m charged above the screw conveyor 2 is increased or decreased in this manner, as shown in Figure 2(a), the pile of raw material m piled above the screw conveyor 2 has high and low points. Where the height of the pile of raw material m piled above the screw conveyor 2 is high, the weight of the raw material m on the screw 5 increases, and the axial load also increases. On the other hand, at the low points (saddles) of the pile of raw material m piled above the screw conveyor 2, there is a risk of the raw material m running out in the next molding process. In this example, "running out" refers to the inability to deliver a sufficient amount of raw material m to the molding process, which makes it impossible to mold coal into molded coal of the desired shape or dimensions. Therefore, if the number of runouts occurs frequently, the rate of acceptable ferro-coke products decreases, resulting in a poor yield.

[0021] FIG. 4 shows the relationship between the height of the mixed raw material m piled above the screw conveyor 2, expressed as a ratio to the outer diameter of the screw 5, and the axial load of the screw 5 and the number of load breaks during the molding process. In the figure, the axial load when the height of the mixed raw material m piled above the screw conveyor 2 is not controlled is set to 100. Generally, the larger the outer diameter of the screw 5, the higher the conveying capacity of the screw conveyor 2, and therefore a drive source with higher drive capacity is used. In this embodiment, it is desirable to reduce the load on the drive source of the screw 5 by an amount commensurate with the drive source's original drive capacity. Therefore, the outer diameter of the screw 5 was used as a parameter when considering the axial load of the screw 5 as described below. Note that the "outer diameter" of the screw 5 refers to the diameter of the largest circle, including the blades, as viewed from the axial direction of the screw 5. In this example, when the height of the mixed raw material m is 6 times the screw outer diameter, the axial load of the screw 5 remains the same as when the height is not controlled. In contrast, if the height of the raw material m is 5 times the screw outer diameter ratio, the axial load on the screw 5 can be reduced compared to when the height is not controlled, so if the height of the raw material m is less than 6 times the screw outer diameter ratio, a axial load reduction effect can be expected. On the other hand, if the height of the raw material m is less than 2 times the screw outer diameter ratio, there is a concern that the load will run out frequently and the yield will deteriorate. Therefore, if the height of the raw material m is 2 times or more the screw outer diameter ratio, the yield decrease can be avoided. For the above reasons, the height of the raw material m piled up above the screw conveyor 2 is specified to be 2 times or more and less than 6 times the screw outer diameter, and preferably 3 times or more and 5 times or less.

[0022] The above describes the raw material conveying device for ferro coke production equipment according to the embodiment, but the present invention is not limited to the configuration described in the above embodiment and various modifications are possible within the scope of the present invention. For example, in the above embodiment, the raw material to be mixed was described only as a raw material for ferro coke production, but the raw material conveying device of the present invention can be similarly applied to raw materials other than this raw material. The raw material conveying device of the present invention can be applied to any raw material to be mixed as long as it contains at least powder or granular material. Furthermore, the number of screws 5 in the screw conveyor 2 is not limited to four, and it is sufficient to have one or more screws 5 functioning as the screw conveyor 2.

[0023] In this embodiment, when the raw material m is charged from above the screw conveyor 2 equipped with one or more screws 5 and transported by the screw conveyor 2, the level meter 9 detects the height of the raw material m piled up above the screw conveyor 2, and the arithmetic processing device 4 controls the operating state of the motor-operated valve 8 provided at the charging port (charging path) 10 to adjust the amount of raw material m charged from above the screw conveyor 2 so that the height of the raw material m detected by the level meter 9 becomes a predetermined height. This reduces the weight of the raw material m charged from above and piled up on the screw conveyor 2, thereby reducing the load on the drive source of the screw 5.

[0024] In addition, by setting the height of the raw material m piled up above the screw conveyor 2 to be more than two times but less than six times the outer diameter of the screw 5, it is possible to reduce the load on the driving source of the screw 5 while preventing the raw material m from running out of load for the next process. [Explanation of symbols]

[0025] 1. Conveyor device 2. Screw conveyor 3 Mixing hopper 4. Processing unit (controller) 5 screws 6. Roof shingles 7 Openings 8 Motor-operated valve 9 Level Meter 10 charging port m Mixed raw materials

Claims

1. A conveying device for conveying raw materials to be mixed, which charges raw materials to be mixed from above a screw conveyor having one or more screws and transports the raw materials by the screw conveyor, characterized in that it comprises: a level meter that detects the height of the raw materials piled up above the screw conveyor; an electric valve that is provided in the charging path of the raw materials to be mixed above the screw conveyor and is capable of adjusting the amount of the raw materials to be charged; and a control device that controls the operating state of the electric valve so that the height of the raw materials detected by the level meter becomes a predetermined height.

2. 2. The conveying device for kneading raw material according to claim 1, wherein the predetermined height is equal to or greater than two times but less than six times the outer diameter of the screw.

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