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: Since the roof plate 6 covering the central portion of the screw 5 of the screw conveyor 2 in the horizontal radial direction is provided above the screw conveyor 2, it is possible to disperse or reduce the weight of the kneaded raw material m at the central portion of the screw 5 of the screw conveyor 2 in the horizontal radial direction, which is likely to be deposited at the highest position among the kneaded raw material m charged from above and deposited on the screw conveyor 2, and which is likely to increase as a result.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 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 object, one embodiment of the present invention provides a conveying device for raw materials to be mixed, which loads raw materials to be mixed including powdered or granular materials from above a screw conveyor having one or more screws, and conveys the raw materials to be mixed by the screw conveyor, and is characterized in that a roof plate covering the horizontal radial center of the screw in the screw conveyor is provided above the screw conveyor.

[0007] Furthermore, a further aspect of the present invention is characterized in that the roof plate has a mountain shape with the central part in the horizontal radial direction of the screw protruding upward, and the height between the lower end of the roof plate and the upper end of the screw is less than three times the outer diameter of the screw. Furthermore, a further aspect of the present invention is characterized in that the roof panel has multiple openings that penetrate vertically, the smallest dimension of the openings is at least five times the diameter of the powder or granular material, and the opening rate, which is the ratio of the opening area of ​​the openings to the area of ​​the upper or lower surface of the roof panel, is at least 60%. [Effects of the Invention]

[0008] According to the present invention, the weight of the raw materials to be mixed at the center of the horizontal radial direction of the screw of the screw conveyor, which tends to be the highest among the raw materials to be loaded from above and pile up on the screw conveyor, can be distributed or reduced, 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 a detailed explanatory view of the top of the roof panel of FIG. 2. [Figure 4] FIG. 3 is an explanatory diagram of the axial load of the screw conveyor depending on the height of the roof panel in FIG. 2. [Figure 5] FIG. 4 is an explanatory diagram of the axial load of the screw conveyor depending on the opening ratio of the openings in FIG. 3. [Figure 6] 4 is an explanatory diagram of the blocking rate of the openings in FIG. 3 depending on the opening dimensions. FIG. 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 (i.e., the diameter of the powder particles) by a pulverizer (not shown) and supplied as powder particles. 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 % of coal and 10 to 40 mass % of the iron source material. Iron ore is primarily used as the iron source material, but iron ore may be replaced by other iron source materials by-produced in steelworks, such as blast furnace dust, converter dust, or rolling mill sludge. Also, 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.

[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 roof plate 6 for receiving the raw material m is disposed above the screw conveyor 2 and at a location where the raw material m contacts, particularly at the center of the screw 5 in the horizontal radial direction of the screw conveyor 2. Because the weight of the raw material m is not applied below the portion where the roof plate 6 is disposed, the axial load of the screw 5 in that area can be reduced. In this example, the roof plate 6 is disposed so as to cover the tops of the two inner screws 5 in the left-right direction in FIG. 2(b), where the axial load is large. However, the axial load reduction effect can be obtained even if the screws 5 are not completely covered. Furthermore, the raw material m, which is ferro-coke, has a characteristic of contracting when pressure is applied and does not return to its original volume even when the pressure is reduced. Therefore, when the weight of the raw material m accumulated 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 of the screw 5. Therefore, if the weight of the screw 5 in the horizontal radial center of the screw conveyor 2, in other words the weight of the raw material m which tends to accumulate highest and become larger, can be dispersed and reduced, the consolidation of the raw material m in that area can be reduced, and it can be considered that the adhesion and growth of the raw material m due to consolidation can be avoided and the axial load of the screw 5 can be reduced.

[0016] The shape of the roof plate 6 is mountain-shaped, with the center of the screw 5 in the horizontal radial direction of the screw conveyor 2 projecting upward to prevent the raw material m from piling up on the roof plate 6 and to actively feed the raw material m between the two left-hand screws 5 and the two right-hand screws 5 in Figure 2(b). The greater the inclination angle of the mountain-shaped slope relative to the horizontal, the more likely the raw material m slides off the roof plate 6. This increases the amount of raw material m fed between the two left-hand screws 5 and the two right-hand screws 5. Therefore, the inclination angle of the mountain-shaped slope is set to ensure an appropriate amount of raw material m is fed. In this embodiment, the inclination angle of the slope relative to the horizontal is set to 30°. Furthermore, it is desirable that the length of the roof plate 6 in the screw axial direction covers the screw conveyor 2 from below the charging opening 10 to just before the constriction section 3a of the kneading hopper 3. Furthermore, if the height of the shingle 6 is defined as the vertical distance between the bottom end of the mountain-shaped shingle 6 and the top end of the screw 5, if the height of the shingle 6 is too large, the raw material m will also flow around above the two central screws 5 in Figure 2(b), which is thought to reduce the axial load on the screw 5. Figure 4 shows the relationship between the height of the shingle 6 and the axial load on the screw 5, expressed as a ratio of the height to the outer diameter of the screw 5. In the figure, the axial load without the shingle 6 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 driving 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 driving capacity. Therefore, the outer diameter of the screw 5 was used as a parameter when considering the axial load on the screw 5 as follows. Note that the "outer diameter" of the screw 5 refers to the diameter of the largest circle, including the blades, when viewed from the axial direction of the screw 5. In this example, when the height of the roof plate 6 is 3.5 times the screw outer diameter, the axial load on the screw 5 remains the same as when there is no roof plate 6. In contrast, when the height of the roof plate 6 is 1.5 times the screw outer diameter, the axial load on the screw 5 can be reduced by about 40% compared to when there is no roof plate 6.In this embodiment, if the height of the roof plate 6 is three times or less the screw outer diameter, the axial load of the screw 5 is reduced compared to when the roof plate 6 is not present, so the height of the roof plate 6 is specified at this height.

[0017] In this embodiment, we attempted to equalize the axial load of the four screws 5 by supplying an appropriate amount of raw material m to the horizontal, radial center of the screws 5 of the screw conveyor 2, i.e., the two screws 5 at the center in the left-right direction in Figure 2(b). Specifically, multiple relatively small openings 7 were formed in the horizontal, radial center of the screws 5 of the screw conveyor 2 of the mountain-shaped roof panel 6. Figure 3 shows an example of the openings 7 when they are circular holes. The openings 7 are through-holes that penetrate the roof panel 6 from top to bottom. In this embodiment, as described above, the coal is pulverized to a particle size of 3 mm or less, and the iron ore is pulverized to a particle size of 0.5 mm or less, so these materials fall through the openings 7 to the bottom of the roof panel 6. The amount of raw material m supplied to the two screws 5 at the center in the left-right direction in Figure 2(b) is determined by the opening ratio of the openings 7, which are formed in the horizontal, radial center of the screws 5 of the mountain-shaped roof panel 6, to the roof panel 6. The aperture ratio was defined as the ratio of the aperture area of ​​the opening 7 to the area of ​​the upper or lower surface of the roof panel 6. Figure 5 shows the relationship between the aperture ratio of the opening 7 relative to the area of ​​the roof panel 6 and the axial load of the screw 5. As described above, the axial load of the screw 5 was set to 100 when the roof panel 6 was not present. As is clear from the figure, if the aperture ratio of the opening 7 exceeds 60%, the effect of reducing the axial load on the screw 5 decreases. Therefore, in this embodiment, the aperture ratio of the opening 7 is set to 60% or less. Furthermore, if the aperture area of ​​the opening 7 itself is small, more specifically, if the minimum dimension of the opening 7 is small, the raw material m will clog the opening 7 and cause it to cease functioning. Figure 6 shows the relationship between the minimum dimension of the opening 7 and the occlusion rate (%) of the opening 7, where the particle size of the raw material m is (approximately) constant and the minimum dimension of the opening 7 relative to the particle size of the raw material m is expressed as the particle size ratio of the powder or granular material m. As is clear from the figure, if the minimum dimension of the opening 7 is less than three times the particle size, the clogging rate of the opening 7 increases significantly, increasing the risk of clogging, so in this embodiment, the minimum dimension of the opening 7 is specified to be at least five times the particle size of the powder or granular material that is the raw material m to be kneaded. Note that if the powder or granular material has an elliptical cross section, the major axis of the ellipse is taken as the diameter (particle size) of the powder or granular material.

[0018] 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.

[0019] In this embodiment, when the raw material m containing powder and granular material is charged from above the screw conveyor 2 equipped with one or more screws 5 and the raw material m is transported by the screw conveyor 2, a roof plate 6 is provided above the screw conveyor 2 to cover the central portion of the screw 5 in the horizontal radial direction of the screw 5 on the screw conveyor 2. This makes it possible to distribute or reduce the weight of the raw material m at the central portion of the screw 5 in the horizontal radial direction of the screw conveyor 2, which tends to be the highest among the raw material m charged from above and piled up on the screw conveyor 2, and as a result, tends to become large, and therefore the load on the drive source of the screw 5 can be reduced.

[0020] In addition, a mountain-shaped roof plate 6 is used in which the central portion in the horizontal radial direction of the screw 5 of the screw conveyor 2 protrudes upward, and the height between the lower end of the roof plate 6 and the upper end of the screw 5 is set to three times or less the outer diameter of the screw 5. This allows the raw materials m to slide outward from the central side in the horizontal radial direction of the screw 5 of the screw conveyor 2, which is prone to accumulation, and also prevents the sliding raw materials m from wrapping around to the central side in the horizontal radial direction of the screw 5 of the screw conveyor 2.

[0021] In addition, openings 7 penetrating the roof plates 6 from top to bottom are formed in the roof plates 6, the minimum dimension of the openings 7 being at least five times the diameter of the powder or granular material, and the opening ratio, which is the ratio of the opening area of ​​the openings 7 to the area of ​​the upper or lower surface of the roof plates 6, being at least 60%. This makes it possible to supply an appropriate amount of powder or granular material m to the horizontal radial center of the screws 5 in the screw conveyor 2, thereby equalizing the axial load on the multi-shaft screws 5. [Explanation of symbols]

[0022] 1. Conveyor device 2. Screw conveyor 3 Mixing hopper 4. Processing Unit 5 screws 6. Roof shingles 7 Openings 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 including powdered or granular materials from above a screw conveyor having one or more screws and conveys the raw materials to be mixed by the screw conveyor, characterized in that a roof plate covering the horizontal radial center of the screw of the screw conveyor is provided above the screw conveyor.

2. 2. A conveying device for kneaded raw materials as described in claim 1, characterized in that the roof plate has a mountain shape with the central part in the horizontal radial direction of the screw protruding upward, and the height between the lower end of the roof plate and the upper end of the screw is less than three times the outer diameter of the screw.

3. A mixed raw material conveying device as described in claim 1, characterized in that the roof plate has multiple openings that penetrate vertically, the smallest dimension of the openings is at least five times the diameter of the powder or granular material, and the opening rate, which is the ratio of the opening area of ​​the openings to the area of ​​the upper or lower surface of the roof plate, is at least 60%.

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