Raw material loading device and raw material loading method

Abstract

A raw material charging device according to one aspect of the present invention is a raw material charging device for charging an oxidized iron raw material into a shaft furnace body, and is characterized by comprising: a plurality of charging hoppers for storing the oxidized iron raw material to be charged into the shaft furnace body; a central raw material dispersion pipe having one end connected to at least one of the plurality of charging hoppers and the other end arranged at a position including the center in a plan view within the internal space of the shaft furnace body; and a plurality of peripheral raw material dispersion pipes having one end connected to another of the plurality of charging hoppers and the other end arranged around the other end of the central raw material dispersion pipe.

Description

[Technical Field]

[0001] The present invention relates to a raw material charging device and a raw material charging method. This application claims priority to Japanese Patent Application No. 2024-059749, filed on April 2, 2024, the contents of which are incorporated herein by reference. [Background technology]

[0002] The shaft furnace method for producing reduced iron (DRI) is a representative example of a direct reduction process for producing reduced iron from an oxidized iron raw material. This process is primarily widespread in regions where natural gas is inexpensive (oil-producing countries). Here, we will explain the outline of the DRI process using a shaft furnace. First, an oxidized iron raw material (e.g., iron oxide pellets) is charged into the shaft furnace from above, and a reducing gas is injected into the shaft furnace from below. The reducing gas is heated to a predetermined temperature (e.g., approximately 900–950°C) and then injected into the shaft furnace. The reducing gas then reduces the oxidized iron raw material in the shaft furnace. This direct reduction process produces reduced iron. The reduced iron is discharged from the bottom of the shaft furnace and cooled. A top gas (exhaust gas) containing hydrogen gas, CO gas, water vapor, and CO2 gas is discharged from the top of the shaft furnace. After the water vapor is removed from the top gas, the hydrogen gas and CO2 gas in the top gas are reused as part of the feed gas. In some cases, CO2 gas is removed from the furnace gas after water vapor has been removed.

[0003] The reducing gas used in shaft furnaces is obtained by reforming raw material gases containing carbon (such as natural gas or coke oven gas) with steam, CO2 gas, oxygen gas, etc. Alternatively, the raw material gas can be used as the reducing gas in shaft furnaces without reforming it. The main components of reducing gas are hydrogen gas (H2), CO gas (CO), and methane gas (CH4).

[0004] The oxidized iron raw material is charged into the shaft furnace through a dispersion pipe from a charging hopper installed at the furnace top. The ends (openings) of the dispersion pipe in the shaft furnace are arranged evenly in the circumferential direction in a plan view (here, the plane means a plane perpendicular to the height direction of the shaft furnace; the same applies hereinafter) so that the oxidized iron raw material is uniformly dispersed in the shaft furnace (Patent Documents 1 and 2).

[0005] However, because the reducing gas is injected from the side of the shaft furnace, the reducing gas flow rate within the shaft furnace is not necessarily uniform. Specifically, the reducing gas flow rate at the center and its vicinity in a planar view of the shaft furnace is smaller than the reducing gas flow rate near the wall surfaces of the shaft furnace. For this reason, as disclosed in Patent Document 3, a technique for biasing the particle size distribution of the oxidized iron raw material in a planar view has been proposed. In the technique disclosed in Patent Document 3, the particle size of the oxidized iron raw material charged at the center and its vicinity in a planar view of the shaft furnace is made larger than the particle size of the oxidized iron raw material charged near the wall surfaces of the shaft furnace. This makes it easier for the reducing gas to flow to the center and its vicinity in a planar view of the shaft furnace, thereby making the distribution of the reducing gas flow rate within the shaft furnace uniform. Therefore, it is possible to reduce the variation in the quality of the reduced iron discharged from the center and its vicinity in a planar view of the shaft furnace and the quality of the reduced iron discharged near the wall surfaces. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japan Utility Model Publication No. 53-96004 [Patent Document 2] Japanese Patent Publication No. 55-69210 [Patent Document 3] Japanese Patent Publication No. 07-146080 Summary of the Invention [Problem to be solved by the invention]

[0007] The technology disclosed in Patent Document 3 is useful because it can bias the particle size distribution of the oxidized iron raw material in a plan view. However, the present inventors have studied this technology in detail and found that there is room for further improvement. In addition, the present inventors have considered that a technology that can vary the distribution of the properties of the oxidized iron raw material in a plan view is necessary to further increase the flexibility of shaft furnace operation. It is believed that if the distribution of the properties in a plan view can be varied, the metallization rate of the oxidized iron raw material can be improved.

[0008] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a new and improved raw material charging device and raw material charging method that can change the distribution of properties of the oxidized iron raw material in a planar view, and increase the metallization rate of the oxidized iron raw material, particularly in the center of the shaft furnace body, thereby improving the metallization rate of the oxidized iron raw material as a whole. [Means for solving the problem]

[0009] The gist of the present invention is as follows. (1) A raw material charging device according to one aspect of the present invention is a raw material charging device for charging an oxidized iron raw material into a shaft furnace body, comprising: a plurality of charging hoppers for storing the oxidized iron raw material to be charged into the shaft furnace body; a central raw material dispersion pipe having one end connected to at least one of the plurality of charging hoppers and the other end arranged at a position including the center in a plan view within the internal space of the shaft furnace body; and a plurality of peripheral raw material dispersion pipes having one end connected to another of the plurality of charging hoppers and the other end arranged around the other end of the central raw material dispersion pipe. A cylindrical member provided inside the shaft furnace body; Equipped with The other end of the central raw material dispersion pipe is arranged inside the cylindrical member in a plan view, and the other ends of the plurality of peripheral raw material dispersion pipes are arranged outside the cylindrical member in a plan view, and the position of the other end of the central raw material dispersion pipe in the height direction is lower than the position of the other end of the peripheral raw material dispersion pipe in the height direction. It is characterized by: (2) Another aspect of the present invention is a raw material charging method according to the above (1). A raw material charging method using the raw material charging device described in The iron oxide raw material is charged into the central and peripheral parts of the shaft furnace body, and the charging surface of the iron oxide raw material charged into the central part is lower than the charging surface of the iron oxide raw material charged into the peripheral part. ( 3 ) the above( 2The raw material charging method described in the above may include charging the iron oxide raw material inside and outside a cylindrical member provided in the furnace of the shaft furnace body, and the charging surface of the iron oxide raw material inside the cylindrical member may be the charging surface of the iron oxide raw material to be charged in the center portion, and the charging surface of the iron oxide raw material outside the cylindrical member may be the charging surface of the iron oxide raw material to be charged in the peripheral portion. ( 4 ) the above( 2 ) or ( 3 The raw material charging method described in (1) may include charging the iron oxide raw material in the central and peripheral parts of the shaft furnace body, and charging the iron oxide raw material in the central part with a particle size larger than the particle size of the iron oxide raw material charged in the peripheral part. ( 5 ) the above( 2 )~( 4 ) The raw material charging method described in any one of the above may include charging the iron oxide raw material into the center and peripheral parts of the shaft furnace body, and charging the iron oxide raw material into the center at a temperature higher than that of the iron oxide raw material charged into the peripheral part. [Effects of the Invention]

[0010] According to the present invention, the distribution of properties of the oxidized iron raw material in a planar view can be varied, the metallization rate of the oxidized iron raw material in the center of the shaft furnace body can be increased, and the metallization rate of the oxidized iron raw material as a whole can be improved. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side cross-sectional view schematically showing an example of a raw material charging device according to a first embodiment of the present invention. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3] FIG. 4 is a side cross-sectional view schematically showing an example of a raw material charging device according to a second embodiment of the present invention. [Figure 4] FIG. 10 is a side cross-sectional view schematically showing an example of a raw material charging device according to a third embodiment of the present invention. [Figure 5] 5 is a cross-sectional view of FIG. 4 taken along line B-B. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0013] <1. First embodiment> (1-1. Raw material charging device) First, the configuration of a raw material charging apparatus 1A according to a first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a side cross-sectional view that schematically shows an example of a raw material charging apparatus 1A according to the first embodiment. Figure 2 is a cross-sectional view (plan view) taken along line AA in Figure 1.

[0014] The raw material charging device 1A is provided at the upper end of the shaft furnace body 10. The shaft furnace body 10 is known.

[0015] The raw material charging device 1A includes raw material tanks 100, 110, a raw material conveying device 120, multiple charging hoppers 20a, 20b, a central raw material dispersion pipe 30, multiple peripheral raw material dispersion pipes 40, a switching damper 130, and multiple pressure equalizing hoppers 140.

[0016] The raw material tank 100 stores an iron oxide raw material 50a, and the raw material tank 110 stores an iron oxide raw material 50b. The iron oxide raw materials 50a and 50b are known iron oxide raw materials, such as iron oxide pellets. The iron oxide raw materials 50a and 50b have different properties. In the first embodiment, the iron oxide raw materials 50a and 50b have different particle sizes. More specifically, the particle size of the iron oxide raw material 50a is larger than the particle size of the iron oxide raw material 50b. In other words, the particle sizes of the iron oxide raw materials stored in the raw material tank 100 and the raw material tank 110 are different, and the particle size of the iron oxide raw material 50a is larger than the particle size of the iron oxide raw material 50b.

[0017] In this case, the oxidized iron raw material may be classified using a sieve with a predetermined mesh size (e.g., 18 mm), with the oxidized iron raw material remaining on the sieve being the oxidized iron raw material 50a, and the oxidized iron raw material that falls through the sieve being the oxidized iron raw material 50b. Furthermore, an upper limit on the particle size of the oxidized iron raw material 50a may be determined. For example, the oxidized iron raw material 50a may be classified using a sieve with a predetermined mesh size (e.g., 20 mm), and the oxidized iron raw material 50a that falls through the sieve may be used. Similarly, a lower limit on the particle size of the oxidized iron raw material 50b may be determined. For example, the oxidized iron raw material 50b may be classified using a sieve with a predetermined mesh size (e.g., 16 mm), and the oxidized iron raw material 50b that remains on the sieve may be used. In this case, the particle size of the oxidized iron raw material 50a will be 18 mm or more and less than 20 mm, and the particle size of the oxidized iron raw material 50b will be 16 mm or more and less than 18 mm.

[0018] The raw material conveying device 120 conveys the oxidized iron raw material 50a or the oxidized iron raw material 50b to the switching damper 130. The switching damper 130 distributes the oxidized iron raw material 50a or the oxidized iron raw material 50b conveyed from the raw material conveying device 120 to the charging hopper 20a or the charging hopper 20b. Specifically, the switching damper 130 distributes the oxidized iron raw material 50a to the charging hopper 20a and distributes the oxidized iron raw material 50b to the charging hopper 20b. The oxidized iron raw material 50a and the oxidized iron raw material 50b are loaded onto the raw material conveying device 120 and conveyed to the switching damper 130 at different times. The flow direction of the oxidized iron raw material 50a is switched by the switching damper 130 to the direction of the charging hopper 20a, so that the oxidized iron raw material 50a is charged into the charging hopper 20a. The flow direction of the oxidized iron raw material 50b is switched by the switching damper 130 to the direction of the charging hopper 20b, and the oxidized iron raw material 50b is charged into the charging hopper 20b.

[0019] The charging hopper 20a is arranged coaxially with the central axis 11 (see FIG. 2) of the shaft furnace body 10. The charging hopper 20a stores the oxidized iron raw material 50a. Four charging hoppers 20b are provided around the charging hopper 20a at equal intervals (90 degree intervals in a plan view). The charging hoppers 20b store the oxidized iron raw material 50b.

[0020] The central raw material dispersion pipe 30 is provided between the shaft furnace body 10 and the charging hopper 20a. One end 30a of the central raw material dispersion pipe 30 is connected to the charging hopper 20a (one charging hopper), and the other end 30b is arranged at a position including the center 11 in a plan view in the internal space of the shaft furnace body 10 (see FIG. 2). The other end 30b being arranged at a position including the center 11 in a plan view in the internal space of the shaft furnace body 10 means that the other end 30b is arranged so as to include the central axis of the shaft furnace body 10 in the height direction inside the end 30b in a plan view. In this embodiment, the central axis of the central raw material dispersion pipe 30 in the length direction and the central axis of the shaft furnace body 10 in the height direction substantially coincide with each other. The central raw material dispersion pipe 30 charges the oxidized iron raw material 50a stored in the charging hopper 20a into the center 11 of the shaft furnace body 10 and its vicinity in a plan view.

[0021] The peripheral raw material dispersion pipes 40 are installed between the internal space of the shaft furnace body 10 and each charging hopper 20b. One end 40a of each peripheral raw material dispersion pipe 40 is connected to the charging hopper 20b, and the other end 40b is located around the other end 30b of the central raw material dispersion pipe 30 (see FIG. 2). As shown in FIG. 2, the other ends 40b of the peripheral raw material dispersion pipes 40 are arranged at equal intervals (90-degree intervals) along the circumferential direction. The positions of the ends 40b of the peripheral raw material dispersion pipes 40 in a plan view can be determined by prior experiments or calculations, etc., depending on the characteristics of the oxidized iron raw materials 50a and 50b, so as to obtain a desired distribution of properties in a plan view. Note that the properties referred to here refer to airflow resistance. For example, by changing the airflow resistance in the radial direction of the shaft furnace body 10, the gas distribution in the radial direction can be changed, thereby increasing the amount of gas in the center, where gas distribution has traditionally been low. The ability to vary the distribution of properties of the oxidized iron raw material in a plan view makes it possible to improve the gas utilization efficiency, suppress reduction disintegration of the oxidized iron raw materials 50a and 50b, and suppress stacking. It also makes it possible to improve the metallization rate.

[0022] The peripheral raw material dispersion pipe 40 charges the oxidized iron raw material 50b to the peripheral portion (peripheral portion of the oxidized iron raw material 50a) in a plan view of the shaft furnace body 10. Therefore, the oxidized iron raw material 50a is charged at the center 11 and its vicinity in a plan view of the shaft furnace body 10, and the oxidized iron raw material 50b is charged around the oxidized iron raw material 50a.

[0023] In the first embodiment, four sets of the charging hopper 20b and the peripheral raw material dispersion pipe 40 are provided at 90-degree intervals around the set of the charging hopper 20a and the central raw material dispersion pipe 30, but the present invention is not limited to this example. For example, four peripheral raw material dispersion pipes 40 may extend from one charging hopper 20b. Alternatively, two peripheral raw material dispersion pipes 40 may extend from each of two charging hoppers 20b. In either case, it is preferable that a plurality of peripheral raw material dispersion pipes 40 are arranged at equal intervals in the circumferential direction in a plan view.

[0024] The pressure equalizing hopper 140 is provided in the central raw material dispersion pipe 30 and the peripheral raw material dispersion pipe 40, and maintains the internal pressure of these dispersion pipes uniform.

[0025] As described above, in the raw material charging apparatus 1A according to this embodiment, the oxidized iron raw materials 50a stored in the charging hopper 20a are charged into the center 11 or its vicinity in a plan view of the shaft furnace body 10 via the central raw material dispersion pipe 30, and the oxidized iron raw materials 50b stored in the charging hopper 20b are charged into the periphery of the oxidized iron raw materials 50a in a plan view of the shaft furnace body 10 via the peripheral raw material dispersion pipe 40. Here, simply changing the properties of the oxidized iron raw materials 50a stored in the charging hopper 20a and the properties of the oxidized iron raw materials 50b stored in the charging hopper 20b can change the distribution of properties of the oxidized iron raw materials 50a and 50b in a plan view. Examples of the properties of the oxidized iron raw materials 50a and 50b include particle size and temperature, which will be described later. Other properties include the components and brands of the oxidized iron raw materials 50a and 50b. Therefore, the distribution of properties of the oxidized iron raw materials 50a and 50b in a plan view can be changed.

[0026] <1-2. Raw material charging method> Next, an example of a raw material charging method using the above-described raw material charging apparatus 1A will be described. In this raw material charging method, the particle size of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is set larger than the particle size of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. In other words, the particle size of the oxidized iron raw material 50a stored in the raw material tank 100 is set larger than the particle size of the oxidized iron raw material 50b stored in the raw material tank 110. When the oxidized iron raw material 50a is transported from the raw material tank 100 to the switching damper 130, the switching damper 130 distributes the oxidized iron raw material 50a to the charging hopper 20a. When the oxidized iron raw material 50b is transported from the raw material tank 110 to the switching damper 130, the switching damper 130 distributes the oxidized iron raw material 50b to the charging hopper 20b. As a result, the particle size of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is made larger than the particle size of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. In other words, in this raw material charging method, the oxidized iron raw material is charged into the central and peripheral parts of the shaft furnace body 10, and the oxidized iron raw material 50a having a particle size larger than the particle size of the oxidized iron raw material 50b charged into the peripheral part is charged into the central part. That is, the particle size of the oxidized iron raw material 50a at and near the center 11 in a plan view of the shaft furnace body 10 is made larger than the particle size of the oxidized iron raw material 50b charged around the oxidized iron raw material 50a. The particle size adjustment method is as described above. There are no particular restrictions on the magnitude of the difference in particle size, as long as it is set to maximize the effect (reduction of variation in the quality of reduced iron) described below. The central part here refers to a part including the central axis of the shaft furnace body 10 in the height direction in a plan view, and the peripheral part refers to a part of the shaft furnace body 10 that is outside the central part. The ratio of the central part to the peripheral part in a plan view is not particularly limited as long as the desired properties of the oxidized iron raw material in a plan view can be obtained.

[0027] As described above, the reducing gas is injected from the side of the shaft furnace body 10. Therefore, when the particle size distribution of the oxidized iron raw materials is uniform in a plan view, the reducing gas flow rate at the center 11 and its vicinity in a plan view of the shaft furnace body 10 is smaller than the reducing gas flow rate near the wall surfaces of the shaft furnace body 10. Therefore, in this embodiment, the particle size of the oxidized iron raw materials 50a at the center 11 and its vicinity in a plan view of the shaft furnace body 10 is set larger than the particle size of the oxidized iron raw materials 50b charged around the oxidized iron raw materials 50a. This makes it easier for the reducing gas to flow through the center 11 and its vicinity in a plan view of the shaft furnace body 10, thereby making the distribution of the reducing gas flow rate in the shaft furnace uniform. Therefore, it is possible to reduce the variation in the quality of the reduced iron discharged from the center 11 and its vicinity in a plan view of the shaft furnace body 10 and the quality of the reduced iron discharged from the vicinity of the wall surfaces, thereby improving the quality of the reduced iron.

[0028] 2. Second embodiment (2-1. Raw material charging device) Next, the configuration of a raw material charging apparatus 1B according to a second embodiment will be described with reference to Fig. 3. Fig. 3 is a side cross-sectional view that schematically shows an example of a raw material charging apparatus 1B according to the second embodiment. The raw material charging apparatus 1B according to the second embodiment is configured by adding a raw material preheating device 115 to the raw material charging apparatus 1A according to the first embodiment.

[0029] The raw material preheating device 115 is provided below the raw material tank 100 and preheats the oxidized iron raw material 50a discharged from the raw material tank 100 before loading it onto the raw material conveying device 120. The heating temperature by the raw material preheating device 115 can be measured, for example, by providing a thermometer such as a thermocouple in the raw material preheating device 115. The operation of the other devices in the raw material charging device 1B is the same as that of the raw material charging device 1A. Therefore, the temperature (surface temperature) of the oxidized iron raw material 50a is higher than the temperature (surface temperature) of the oxidized iron raw material 50b. In the second embodiment, the oxidized iron raw material 50a is heated before being stored in the charging hopper 20a. However, the oxidized iron raw material 50a may be heated in the charging hopper 20a or while passing through the central raw material dispersion pipe 30. The means for heating the oxidized iron raw material 50a is not particularly limited and may be, for example, an electric heater. In the second embodiment, the oxidized iron raw material 50a has different characteristics from the oxidized iron raw material 50b, and therefore has a different temperature. In other words, the temperatures of the oxidized iron raw material stored in the raw material tank 100 and the raw material tank 110 are different, and the temperature of the oxidized iron raw material 50a is higher than the temperature of the oxidized iron raw material 50b. The oxidized iron raw material 50a is preheated to, for example, 600°C to 800°C. The temperature of the oxidized iron raw material 50b is room temperature, for example, 0 to 50°C.

[0030] (2-2. Raw material charging method> Next, an example of a raw material charging method using the above-mentioned raw material charging apparatus 1B will be described. In this raw material charging method, the temperature of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is made higher than the temperature of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. That is, the oxidized iron raw material 50a stored in the raw material tub 100 is first preheated in the raw material preheating device 115. Then, when the oxidized iron raw material 50a is transported from the raw material tub 100 to the switching damper 130, the switching damper 130 distributes the oxidized iron raw material 50a to the charging hopper 20a. When the oxidized iron raw material 50b is transported from the raw material tub 100 to the switching damper 130, the switching damper 130 distributes the oxidized iron raw material 50b to the charging hopper 20b. As a result, the temperature of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is made higher than the temperature of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. In other words, in this raw material charging method, the oxidized iron raw material is charged into the central and peripheral parts of the shaft furnace body 10, and the oxidized iron raw material 50a is charged into the central part at a higher temperature than the oxidized iron raw material 50b charged into the peripheral part. That is, the temperature of the oxidized iron raw material 50a at and near the center 11 in a plan view of the shaft furnace body 10 is made higher than the temperature of the oxidized iron raw material 50b charged around the oxidized iron raw material 50a. The preheating method for the oxidized iron raw material 50a is as described above. There are no particular restrictions on the preheating temperature, as long as it is set to maximize the effect (reduction of quality variation of reduced iron) described below. The oxidized iron raw material 50a is heated to, for example, 600°C to 800°C.

[0031] As described above, the reducing gas is injected from the side of the shaft furnace body 10. Therefore, when the particle size distribution of the oxidized iron raw materials is uniform in a plan view, the reducing gas flow rate at the center 11 and its vicinity in a plan view of the shaft furnace body 10 is smaller than the reducing gas flow rate near the wall surface of the shaft furnace body 10. In other words, the temperature of the oxidized iron raw materials charged at the center 11 and its vicinity in a plan view of the shaft furnace body 10 is unlikely to rise.

[0032] Therefore, in this embodiment, the temperature of the oxidized iron raw materials 50a at and near the center 11 in a plan view of the shaft furnace body 10 is set higher than the temperature of the oxidized iron raw materials 50b charged around the oxidized iron raw materials 50a. This makes it possible to make the temperature distribution of the oxidized iron raw materials 50a, 50b in the shaft furnace uniform. Therefore, it is possible to reduce the variation in quality of the reduced iron discharged from and near the center 11 in a plan view of the shaft furnace body 10 and the reduced iron discharged near the wall surface, thereby improving the quality of the reduced iron.

[0033] The raw material charging method according to the first embodiment may be combined with the raw material charging method according to the second embodiment. That is, the particle size of the oxidized iron raw material 50a may be made larger than the particle size of the oxidized iron raw material 50b, and then the oxidized iron raw material 50a may be preheated. This makes it possible to more effectively obtain the above-mentioned effects.

[0034] 3. Third Embodiment (3-1. Raw material charging device) Next, the configuration of a raw material charging apparatus 1C according to a third embodiment will be described with reference to Figures 4 and 5. Figure 4 is a side cross-sectional view that schematically shows an example of the raw material charging apparatus 1C according to the third embodiment. Figure 5 is a B-B cross-sectional view (plan view) of Figure 4. Note that Figure 5 also shows a view of the other end 40b of the peripheral raw material dispersion pipe 40 projected onto the B-B cross-section. The raw material charging apparatus 1C according to the third embodiment is the raw material charging apparatus 1A according to the first embodiment, equipped with a cylindrical member 60.

[0035] As shown in Fig. 4, the raw material charging apparatus 1C differs from the raw material charging apparatus 1A in that it is equipped with a tubular member 60. The tubular member 60 is provided inside the shaft furnace body 10, and as shown in Fig. 5, it is preferable that the position of the central axis in a plan view coincides with the center 11 of the shaft furnace body 10 in a plan view. The position of the central axis in a plan view coincides with the center 11 of the shaft furnace body 10 in a plan view means that the tubular member 60 is arranged inside the tubular member 60 so as to include the center 11 in the height direction of the shaft furnace body 10 in a plan view. The cylindrical member 60 has a function of preventing the oxidized iron raw materials 50b from being loaded in the peripheral portion and flowing into the center portion. The shape of the cross section perpendicular to the central axis of the cylindrical member 60 is not particularly limited and may be circular, elliptical, polygonal, or the like. However, in order to charge the oxidized iron raw materials 50a, 50b symmetrically about the center of the shaft furnace body 10 in the planar cross section, the shape of the cross section perpendicular to the central axis of the cylindrical member 60 is preferably circular or regular polygonal. As described above, various shapes may be used for the cross section perpendicular to the central axis of the cylindrical member 60. Therefore, the central axis of the cylindrical member 60 refers to the geometric central axis.

[0036] Furthermore, the other end 30b of the central raw material dispersion pipe 30 is disposed inside the cylindrical member 60 in a side view and a plan view, and the other ends 40b of the multiple peripheral raw material dispersion pipes 40 are disposed outside the cylindrical member 60 in a side view and a plan view. Therefore, the oxidized iron raw material 50a discharged from the central raw material dispersion pipe 30 is charged inside the cylindrical member 60, and the oxidized iron raw material 50b discharged from the peripheral raw material dispersion pipe 40 is charged outside the cylindrical member 60. The cylindrical member 60 can suppress mixing of the oxidized iron raw material 50a and the oxidized iron raw material 50b. The height position of the other end 30b of the central raw material dispersion pipe 30 and the height position of the other end 40b of the peripheral raw material dispersion pipe 40 may be the same. However, it is preferable that the height position of the other end 30b of the central raw material dispersion pipe 30 be lower than the height position of the other end 40b of the peripheral raw material dispersion pipe 40. In this case, the charging surface 51a of the oxidized iron raw materials 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is lower than the charging surfaces 51b of the oxidized iron raw materials 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. For example, the position of the apex of the charging surface 51a of the oxidized iron raw materials 50a (the portion directly below the other end 30b of the central raw material dispersion pipe 30) is lower than the position of the apex of the charging surface 51b of the oxidized iron raw materials 50b (the portion directly below the other end 40b of the peripheral raw material dispersion pipe 40). In other words, the height from the charging surface 51a of the oxidized iron raw materials 50a to the inlet 12 for the reducing gas can be lower than the height from the charging surface 51b of the oxidized iron raw materials 50b to the inlet 12 for the reducing gas. Here, the charging surface 51a of the oxidized iron raw material 50a is the upper end surface of the stack of oxidized iron raw materials 50a formed in the shaft furnace body 10, and the charging surface 51b of the oxidized iron raw material 50b is the upper end surface of the stack of oxidized iron raw materials 50b formed in the shaft furnace body 10. The charging surfaces 51a and 51b can be measured, for example, by sounding or an ultrasonic distance meter. Both the charging surfaces 51a and 51b are mountain-shaped surfaces. Therefore, the boundary between the charging surface 51a and the charging surface 51b, and the boundary between one charging surface 51b and another charging surface 51b, are valley-shaped portions between adjacent mountain-shaped surfaces. This makes it possible to distinguish each charging surface 51a and 51b.

[0037] This allows the reducing gas to flow more easily through the center 11 and its vicinity in a plan view of the shaft furnace body 10, thereby making it possible to uniformly distribute the flow rate of the reducing gas within the shaft furnace. This reduces the variation in the quality of the reduced iron discharged from the center 11 and its vicinity in a plan view of the shaft furnace body 10 and the quality of the reduced iron discharged from the vicinity of the wall surface.

[0038] The appropriate height from the apex of the charging surface 51b of the oxidized iron raw materials 50b to the reducing gas inlet 12 differs depending on the shape of the shaft furnace, the amount of gas, etc., but is preferably about 5 to 20% lower than the height from the apex of the charging surface 51a of the oxidized iron raw materials 50a to the reducing gas inlet 12. This allows the above-mentioned effects to be obtained.

[0039] (3-2. Raw material charging method) Next, an example of a raw material charging method using the above-mentioned raw material charging apparatus 1C will be described. In this raw material charging method, the height position of the other end 30b of the central raw material dispersion pipe 30 is set lower than the height position of the other end 40b of the peripheral raw material dispersion pipe 40. Furthermore, the other end 30b of the central raw material dispersion pipe 30 is arranged inside the cylindrical member 60 in side and plan views. Furthermore, the other end 40b of the peripheral raw material dispersion pipe 40 is arranged outside the cylindrical member 60 in side and plan views. In this state, the oxidized iron raw material 50a is charged into the shaft furnace body 10 from the central raw material dispersion pipe 30, and the oxidized iron raw material 50b is charged into the shaft furnace body 10 from the peripheral raw material dispersion pipe 40. As a result, the charging surface 51a of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 is made lower than the charging surface 51b of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. In other words, in this raw material charging method, the oxidized iron raw material is charged into the central and peripheral parts of the shaft furnace body 10, and the charging surface of the oxidized iron raw material 50a charged into the central part is made lower than the charging surface of the oxidized iron raw material 50b charged into the peripheral parts.

[0040] This allows the reducing gas to flow more easily through the center 11 and its vicinity in a plan view of the shaft furnace body 10, thereby making it possible to uniformly distribute the flow rate of the reducing gas within the shaft furnace. This reduces the variation in the quality of the reduced iron discharged from the center 11 and its vicinity in a plan view of the shaft furnace body 10 and the quality of the reduced iron discharged from the vicinity of the wall surface.

[0041] The third embodiment may be combined with the first or second embodiment. In this case, the above-mentioned effects can be obtained more effectively. When the third embodiment is combined with the first or second embodiment, the height direction of the charging surface 51a of the oxidized iron raw material 50a charged into the shaft furnace body 10 from the central raw material dispersion pipe 30 may be aligned with the height direction of the charging surface 51b of the oxidized iron raw material 50b charged into the shaft furnace body 10 from the multiple peripheral raw material dispersion pipes 40. In this case, the cylindrical member 60 makes it more difficult for the raw materials at each charging position to mix, and an improved effect can be expected.

[0042] In the above-described embodiment, four charging hoppers 20b are provided around the charging hopper 20a at equal intervals (90-degree intervals in a plan view), but the arrangement of the charging hoppers 20b is not limited to this. Three or more charging hoppers 20b may be provided. Furthermore, as long as the ends 40b of the peripheral raw material dispersion pipes 40 connected to the charging hoppers 20b are arranged at equal intervals (90-degree intervals) along the circumferential direction, the peripheral raw material dispersion pipes 40 may be bent or inclined, and the positions of the charging hoppers 20b connected to the ends 40a of the peripheral raw material dispersion pipes 40 may be arranged at any positions. The positions of the charging hoppers 20b and the shape of the peripheral raw material dispersion pipes 40 can be determined experimentally. The arrangement of the charging hopper 20a is similar to the arrangement of the charging hopper 20b. As long as the end 30b of the central raw material dispersion pipe 30 is arranged at a position that includes the center 11 in a plan view within the internal space of the shaft furnace body 10, the central raw material dispersion pipe 30 may be bent or inclined, and the position of the charging hopper 20a connected to the end 30a of the central raw material dispersion pipe 30 may be arranged at any position. [Example]

[0043] <1. Comparative Example> In the raw material charging device 1A according to the first embodiment, a shaft furnace with a diameter of approximately 7 m was assumed, in which the oxidized iron raw material 50b was charged into the shaft furnace body 10 only through the peripheral raw material dispersion pipe 40. Hydrogen was used as the reducing gas, and the injection temperature was 950°C. The furnace top pressure was approximately 50 KPa, and the average particle size of the oxidized iron raw material 50b was 13 mm. As a result of a numerical analysis using a two-dimensional numerical model, the metallization rate of the reduced iron was 94.7%.

[0044] <2. Example 1> In the raw material charging device 1A according to the first embodiment, oxidized iron raw materials 50a and 50b were charged into the shaft furnace body 10 through the central raw material dispersion pipe 30 and the peripheral raw material dispersion pipe 40. The average particle size of the oxidized iron raw materials 50a was set to less than 16 mm. Other conditions were the same as those in Comparative Example 1. As a result of a two-dimensional model analysis, the metallization rate of the reduced iron was 97.1%, which was higher than that of Comparative Example 1. This is thought to be because the quality of the reduced iron discharged from the center 11 and its vicinity in a plan view of the shaft furnace body 10 was improved, and the variation in the quality of the reduced iron was reduced.

[0045] <3. Example 2> In the raw material charging device 1B according to the second embodiment, oxidized iron raw materials 50a and 50b were charged into the shaft furnace body 10 through the central raw material dispersion pipe 30 and the peripheral raw material dispersion pipe 40. The preheating temperature of the oxidized iron raw material 50a was 800°C. The oxidized iron raw material 50b was at room temperature. Other conditions were the same as those in Example 1. As a result of a two-dimensional model analysis, the metallization rate of the reduced iron was 97.7%, which was higher than that in Example 1. This is thought to be because the quality of the reduced iron discharged from the center 11 and its vicinity in a plan view of the shaft furnace body 10 was improved, and the variation in the quality of the reduced iron was reduced.

[0046] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these examples. It is clear that a person skilled in the art to which the present invention pertains can conceive of various modifications and alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. [Explanation of symbols]

[0047] 1A, 1B, 1C Raw material charging equipment 10 Shaft furnace body 20a, 20b Charging hopper 30 Core material dispersion tube 40 Peripheral raw material dispersion pipe 50a, 50b Iron oxide raw materials 51a, 51b charging surface 60 Cylinder member

Claims

1. A raw material charging device for charging iron oxide raw materials into a shaft furnace body, A plurality of charging hoppers for storing iron oxide raw materials to be charged into the shaft furnace body; A central raw material dispersion pipe, one end of which is connected to at least one of the plurality of charging hoppers, and the other end of which is arranged at a position including the center in a plan view in the internal space of the shaft furnace body; a plurality of peripheral raw material dispersion pipes each having one end connected to another of the plurality of charging hoppers and the other end disposed around the other end of the central raw material dispersion pipe; a cylindrical member provided inside the shaft furnace body, the other end of the central raw material dispersion pipe is disposed inside the cylindrical member in a plan view, the other ends of the plurality of peripheral raw material dispersion pipes are disposed outside the cylindrical member in a plan view, A raw material charging device characterized in that the height position of the other end of the central raw material dispersion pipe is lower than the height position of the other end of the peripheral raw material dispersion pipe.

2. A raw material charging method using the raw material charging device according to claim 1, A raw material charging method characterized by charging oxidized iron raw materials into the center and peripheral parts of a shaft furnace body, and making the charging surface of the oxidized iron raw materials charged into the center lower than the charging surface of the oxidized iron raw materials charged into the peripheral part.

3. 3. The raw material charging method according to claim 2, wherein the oxidized iron raw material is charged into the inside and outside of a cylindrical member installed in the shaft furnace body, the charging surface of the oxidized iron raw material inside the cylindrical member is the charging surface of the oxidized iron raw material charged in the center portion, and the charging surface of the oxidized iron raw material outside the cylindrical member is the charging surface of the oxidized iron raw material charged in the peripheral portion.

4. 4. The raw material charging method according to claim 2, wherein the oxidized iron raw material having a particle size larger than that of the oxidized iron raw material charged in the peripheral portion is charged in the central portion.

5. 4. The raw material charging method according to claim 2, wherein the oxidized iron raw material charged in the central portion has a temperature higher than that of the oxidized iron raw material charged in the peripheral portion.