Apparatus for producing reduced iron, system for producing reduced iron, and method for producing reduced iron

Abstract

To provide an apparatus for producing reduced iron with which uniform reduced iron can be obtained at high efficiency.SOLUTION: An apparatus 10 for producing reduced iron comprises a reduction furnace 11 having a furnace body 13 for air-tightly partitioning adjacent spaces, one or more first spaces 14 partitioned by the furnace body 13, and one or more second spaces 15 partitioned by the furnace body 13. The apparatus further comprises one or more burners 12 for supplying combustion gas to the first spaces 14, a material supplying path L1 for supplying the iron-oxide-containing material M to the second spaces 15, a fuel-gas supplying path L2 for supplying fuel gas to the burners 12, and a reducing-gas supplying path for supplying reducing gas to the second spaces 15. In the apparatus for producing reduced iron, the first spaces 14 are arranged in such a way as to be adjacent to the second spaces 15, and heat is transferred between the second spaces 15 and the first spaces 14 through the furnace body 13.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an apparatus for producing reduced iron, a system for producing reduced iron, and a method for producing reduced iron. [Background technology]

[0002] CO2 emissions from the steel industry account for approximately half of the total CO2 emissions from the industry as a whole, and there is a need to reduce these emissions. Iron is mainly produced using the indirect reduction method, which uses blast furnaces. The indirect reduction method produces iron by melting and reducing the raw iron ore, but it is known as a manufacturing method that emits a large amount of CO2. Currently, iron produced using the indirect reduction method, which uses blast furnaces, accounts for the majority of iron production.

[0003] On the other hand, direct steelmaking is known as a steelmaking method with low CO2 emissions. Direct steelmaking is a method in which iron ore is reduced in its solid state using a reducing agent such as natural gas or coal to obtain reduced iron. The reduced iron obtained by the direct steelmaking method is then fed into, for example, an electric furnace and melted.

[0004] As a method for producing reduced iron using the direct iron making method, for example, Patent Document 1 describes a method for producing reduced iron by reforming exhaust gas from a reduction furnace and natural gas in a reformer to generate a reducing gas mainly composed of carbon monoxide and hydrogen gas, and then blowing this reducing gas into a reduction furnace to reduce iron oxide in the reduction furnace.

[0005] Patent Document 2 describes a technology in which gas discharged from an electric furnace is recovered and combusted in the rear stage of the electric furnace, and the resulting combustion heat is stored in a heat storage material.

[0006] Non-Patent Document 1 compares methods for recovering high-temperature waste heat from the perspective of energy quality, i.e., "exergy," and discusses their advantages. Non-Patent Document 1 mentions that, from the perspective of effective energy utilization, it is preferable to utilize high-temperature waste heat in high-temperature endothermic reactions such as reduction reactions rather than simply supplying it for sensible heat utilization such as preheating.

[0007] Prior Art Document 3 discloses a stationary electric furnace equipped with a melting furnace, a preheating furnace, and a reducing furnace. In this stationary electric furnace, the melting furnace and the preheating furnace are connected to each other, and gas discharged from the melting furnace via the preheating furnace is recovered, unburned CO contained in the recovered gas is combusted in the space within the reducing furnace, and an iron oxide source is pre-reduced in the reducing furnace and then supplied to the melting furnace. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2017-088912 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-138068 [Patent Document 3] Special Publication No. 2016-509624 [Non-patent literature]

[0009] [Non-Patent Document 1] T. Akiyama et al., ISIJ International, Vol. 40 (2000), No. 3, pp. 286-291 Summary of the Invention [Problem to be solved by the invention]

[0010] The direct ironmaking process theoretically emits less CO2 and has a smaller environmental impact than the indirect reduction process (blast furnace). However, the production efficiency of the entire process is currently inferior to that of the blast furnace, and there is a demand for higher efficiency. The reduced iron production methods disclosed in Patent Documents 1 and 2 obtain the heat and reducing gas (CO, etc.) necessary for the reduction of iron ore by partially oxidizing fuel, which does not fully utilize thermal energy and is disadvantageous for the reduction reaction. Furthermore, in the electric furnace process, which is intended to be combined with the direct ironmaking process, the exhaust gas from the electric furnace, which contains latent heat and sensible heat, is released into the atmosphere without being utilized, resulting in a significant energy loss.

[0011] The fixed electric furnace disclosed in Patent Document 3 uses the combustion heat of the burner and the sensible heat of the exhaust gas discharged from the melting furnace (electric furnace) via a preheating furnace to form a reducing atmosphere in the reducing furnace, thereby improving energy efficiency. However, according to the technology disclosed in Patent Document 3, the reduction reaction and combustion are simultaneously carried out in a single space in the reducing furnace, resulting in an inhomogeneous reducing atmosphere (unevenness). Furthermore, the CO concentration contained in the exhaust gas from the electric furnace fluctuates depending on the operating state of the electric furnace, resulting in an unstable reducing atmosphere in the reducing furnace. Therefore, the technology disclosed in Patent Document 3 has the problem of not being able to produce uniform reduced iron.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a reduced iron manufacturing apparatus, a reduced iron manufacturing system, and a reduced iron manufacturing method that can obtain uniform reduced iron with high efficiency. [Means for solving the problem]

[0013] The present invention has the following configuration. [1] A furnace body that airtightly separates adjacent spaces; One or more first spaces defined by the furnace body; a reduction furnace having one or more second spaces defined by the furnace body; one or more burners for supplying combustion gas to the first space; a raw material supply path for supplying an iron oxide-containing raw material to the second space; a fuel gas supply path for supplying fuel gas to the burner; a reducing gas supply path that supplies a reducing gas to the second space, The first space is disposed adjacent to the second space, and heat is transferred between the second space and the first space via the furnace body. [2] The reduction furnace is a vertical furnace whose axial direction extends vertically, The first space and the second space are cylindrical spaces whose axial directions extend vertically, the burner is located at an upper end of the reducing furnace, and the combustion gas is supplied downward from above the first space, The apparatus for producing reduced iron according to [1], wherein the raw material supply path is connected to an upper part of the second space, and the iron oxide-containing raw material is supplied from above the second space. [3] the reducing gas supply path merges with the raw material supply path above the second space; The apparatus for producing reduced iron according to [2], wherein the iron oxide-containing raw material is entrained in the reducing gas and supplied from above the second space. [4] The reducing gas supply path is connected to a lower portion of the second space, The apparatus for producing reduced iron according to [2], wherein the reducing gas is supplied from below the second space. [5] a first exhaust gas recovery path that recovers the first exhaust gas discharged from the second space; a condenser located in the first exhaust gas recovery path and removing moisture from the first exhaust gas; a booster located on the secondary side of the condenser in the first exhaust gas recovery path, a base end of the first exhaust gas recovery path is connected to the second space on the opposite side to the reducing gas supply path, with the second space being sandwiched therebetween; The apparatus for producing reduced iron according to any one of [2] to [4], wherein an end of the first exhaust gas recovery path is connected to the second space on the same side as the reducing gas supply path. [6] When the horizontal cross section in the axial direction of the reduction furnace is viewed in plan, [5] The apparatus for producing reduced iron according to any one of [2] to [5], wherein in the reduction furnace, two or more of the first spaces are arranged adjacent to each other around the second space. [7] When the horizontal cross section in the axial direction of the reduction furnace is viewed in plan, The apparatus for producing reduced iron according to any one of [2] to [6], wherein the first space and the second space, each having an annular shape, are alternately arranged in a concentric manner in the reduction furnace. [8] The apparatus for manufacturing reduced iron according to any one of [2] to [7], wherein an outlet for reduced iron is located below the second space. [9] The apparatus for producing reduced iron according to any one of [1] to [8], An electric furnace, a second exhaust gas recovery path that recovers a second exhaust gas discharged from the electric furnace; a base end of the second exhaust gas recovery path communicating with the electric furnace and a tip end of the second exhaust gas recovery path communicating with the fuel gas supply path;

[10] The reduction furnace constituting the reduced iron manufacturing apparatus is connected to the electric furnace, [9] The system for producing reduced iron according to [9], wherein reduced iron is supplied from the reduction furnace to the electric furnace.

[11] A method for producing reduced iron by forming a high-temperature atmosphere by combustion in a burner and forming a reducing atmosphere with a reducing gas, supplying an iron oxide-containing raw material into the reducing atmosphere, and reducing the iron oxide-containing raw material in the reducing atmosphere heated by the high-temperature atmosphere, the high-temperature atmosphere and the reducing atmosphere are formed so as to be spatially separated from each other.

[12] The method for producing reduced iron according to

[11] , wherein the iron oxide-containing raw material is supplied into the reducing atmosphere from above the reducing atmosphere.

[13] The method for producing reduced iron according to

[11] or

[12] , wherein the residence time of the iron oxide-containing raw material in the reducing atmosphere is adjusted by at least one of the supply position and supply amount of the reducing gas into the reducing atmosphere.

[14] The method for producing reduced iron according to any one of

[11] to

[13] , wherein a part of the gas is recovered from the reducing atmosphere, moisture contained in the recovered gas is removed, the gas is pressurized, and the gas is supplied to the reducing atmosphere as part of the reducing gas.

[15] The method for producing reduced iron according to any one of

[11] to

[14] , wherein a portion of gas is recovered from the atmosphere in the electric furnace and supplied as a portion of the fuel gas to be supplied to the burner.

[16] The method for producing reduced iron according to

[15] , wherein the reduced iron obtained in the reducing atmosphere is supplied to the electric furnace. [Effects of the Invention]

[0014] According to the reduced iron manufacturing apparatus, the reduced iron manufacturing system, and the reduced iron manufacturing method of the present invention, uniform reduced iron can be obtained with high efficiency. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a block diagram schematically illustrating a configuration of a reduced iron production system according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a schematic diagram of a reduction furnace constituting an apparatus for producing reduced iron according to an embodiment of the present invention. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view showing a reduction furnace constituting an apparatus for producing reduced iron according to another embodiment of the present invention. [Figure 5] FIG. 4 is a cross-sectional view showing a reduction furnace constituting an apparatus for producing reduced iron according to another embodiment of the present invention. [Figure 6] FIG. 6 is a cross-sectional view taken along line BB in FIG. 5. [Figure 7] FIG. 3 is a cross-sectional view schematically illustrating a part of a reduced iron production system according to another embodiment of the present invention. [Figure 8] FIG. 10 is a block diagram showing a configuration of a reduced iron production system according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings used in the following description, the dimensions of the components may be shown at different scales to make them easier to see, and the dimensional ratios of the components may not be the same as in reality. Furthermore, the materials, dimensions, etc. exemplified in the following description are merely examples, and the present invention is not necessarily limited to them, and can be implemented with appropriate changes within the scope of the present invention. The symbol "to" indicating a range of values ​​means that the values ​​before and after it are included as the lower and upper limits.

[0017] [Reduced iron production system] First, a reduced iron production system 50 shown in FIG. 1 will be described as one embodiment of the present invention. FIG. 1 is a block diagram that schematically shows the configuration of a reduced iron production system according to one embodiment of the present invention.

[0018] As shown in FIG. 1, a reduced iron production system (hereinafter simply referred to as "production system") 50 of this embodiment is an apparatus that reduces an iron oxide-containing raw material in a reducing atmosphere to obtain reduced iron.

[0019] The manufacturing system 50 of this embodiment is generally configured to include a reduced iron manufacturing apparatus 10, an electric furnace 20, a gas supply facility 30, a solid supply facility 40, and paths L1 to L6 located between these facilities.

[0020] [Reduced iron manufacturing equipment] Fig. 2 is a cross-sectional view showing a reduction furnace constituting an apparatus 10 for producing reduced iron according to one embodiment of the present invention. Fig. 3 is a cross-sectional view showing the reduction furnace taken along line AA in Fig. 2. As shown in FIGS. 1 to 3, a reduced iron manufacturing apparatus (hereinafter simply referred to as "manufacturing apparatus") 10 includes a reduction furnace 11, one or more burners 12, and paths L1 to L5.

[0021] (reduction furnace) As shown in FIGS. 2 and 3, the reduction furnace 11 has a furnace body 13, one or more first spaces 14, and one or more second spaces 15. In this embodiment, the reduction furnace 11 will be described as an example of a cylindrical vertical furnace whose axial direction extends vertically.

[0022] The furnace body 13 functions as a partition wall that airtightly separates two or more adjacent spaces provided in the furnace body 13, and is structured to allow only heat exchange. The material (furnace material) constituting the furnace body 13 is not particularly limited as long as it has heat resistance, airtightness, and heat conductivity to withstand the high-temperature atmosphere formed by the combustion of the burner 12. Examples of such materials include metal materials such as stainless steel (e.g., SUS310S) and Inconel, and inorganic materials such as ceramics. Among these, stainless steel (SUS310S) is preferably used from the viewpoints of heat conductivity and processability.

[0023] The first space 14 is provided so as to penetrate the furnace body 13 from the upper end 11a to the lower end 11b of the reducing furnace 11. The first space 14 is a cylindrical space whose axial direction extends vertically. The first space 14 is a space where a high-temperature atmosphere is formed by combustion by the burner 12, as will be described later. In other words, the first space 14 is a combustion chamber.

[0024] The second space 15 is provided so as to penetrate the furnace body 13 from the upper end 11a to the lower end 11b of the reducing furnace 11. The second space 15 is a cylindrical space whose axial direction extends vertically. As will be described later, the second space 15 is a space where a reducing atmosphere for reducing the iron oxide-containing raw material is formed. In other words, the second space 15 is a reduction chamber.

[0025] An outlet 18 for the reduced iron P is located below the second space 15, and the obtained reduced iron P is recovered in a recovery section 19 located below the second space 15 (i.e., below the reduction furnace 11).

[0026] As shown in Fig. 3, the reducing furnace 11 is partitioned by a furnace body (partition wall) 13 into one or more first spaces 14 and one or more second spaces 15, each of which is independent from the other. More specifically, in the reducing furnace 11, the first spaces 14 and the second spaces 15 are partitioned and separated by the furnace body (partition wall) 13 extending in the axial direction of the reducing furnace 11. The first spaces 14 and the second spaces 15 are spaces that each extend in the axial direction of the reducing furnace 11 (i.e., the gas flow direction), and are arranged in the reducing furnace 11 side by side so as to be parallel to the axial direction of the reducing furnace 11. In this way, the first space 14, in which combustion is performed by the burner 12, and the second space 15, in which the iron oxide-containing raw material is reduced, are spatially separated from each other, so that only a reducing gas with high reducing power can be introduced into the second space 15, thereby improving the raw material reduction rate.

[0027] Furthermore, when the horizontal cross section of the reducing furnace 11 in the axial direction is viewed in plan, the reducing furnace 11 is arranged so that two or more first spaces 14 are adjacent to one second space 15. Furthermore, since the furnace body (partition wall) 13 of the reducing furnace 11 has heat conductivity, heat is transferred between the second space 15 and the first space 14 via the furnace body (partition wall) 13. As a result, as will be described later, when a reducing atmosphere is formed in the second space 15, the reducing atmosphere in the second space 15 can be heated from two or more directions in the circumferential direction by the high-temperature atmosphere formed in the first space 14. Therefore, the reducing atmosphere in the second space 15 can be made uniform. In the example shown in FIG. 3 , three first spaces 14 are arranged so as to be adjacent to one second space 15, and therefore the second space 15 is heated by heat transfer from the first spaces 14 in three directions in the circumferential direction.

[0028] (Burna) The burner 12 is located at the upper end 11a of the reducing furnace 11. The burner 12 is connected to the reducing furnace 11 with its tip facing downward so as to communicate with the first space 14. The burner 12 is connected to a fuel gas supply path L2, a combustion-supporting gas supply path L3, and a second exhaust gas recovery path L6 (described later). As a result, the burner 12 is supplied with fuel gas from the fuel gas supply path L2, a combustion-supporting gas such as oxygen from the combustion-supporting gas supply path L3, and electric furnace exhaust gas from the second exhaust gas recovery path L6. The burner 12 then supplies combustion gas obtained by burning these gases from above to below the first space 14. As a result, a high-temperature atmosphere is formed in each of the first spaces 14.

[0029] The connection between the burner 12 and each path is not particularly limited as long as the gas flowing through each path can be supplied to the burner 12. For example, each path may be directly connected to the burner 12, or two or more paths may be joined together and then connected to the burner 12.

[0030] (route) The raw material supply path L1 is located between the solid supply facility 40 and the reduction furnace 11 (i.e., the manufacturing apparatus 10), and is a path for supplying the iron oxide-containing raw material M stored in the solid supply facility 40 to the second space 15 of the reduction furnace 11. According to the present embodiment, the raw material supply path L1 is connected to an upper portion of the second space 15. As a result, the iron oxide-containing raw material M is supplied into the second space 15 from above the second space 15.

[0031] The iron oxide-containing raw material M is a powder having an average particle size of 0.001 to 1 mm, where the average particle size is a value measured by dynamic light scattering (DLS).

[0032] The iron oxide-containing raw material M introduced into the second space 15 falls vertically downward along the second space 15. The iron oxide-containing raw material M is reduced while moving through the second space 15. The resulting reduced iron P is collected in a collection section 19 located below the second space 15.

[0033] The recovery unit 19 prevents the reduced iron P from being reoxidized due to contact with the outside air and suppresses the release of sensible heat to the outside. The recovered reduced iron P can be transported and used, for example, in an electric furnace 20 or in another process.

[0034] The fuel gas supply path L2 is located between the gas supply facility 30 and the reduction furnace 11 (that is, the manufacturing apparatus 10), and is a path for supplying the fuel gas stored in the gas supply facility 30 to the burner 12. Examples of fuel gases include hydrocarbon gases such as natural gas and LP gas.

[0035] The combustion-supporting gas supply path L3 is located between the gas supply facility 30 and the reducing furnace 11 (that is, the manufacturing apparatus 10), and is a path for supplying the combustion-supporting gas stored in the gas supply facility 30 to the burner 12. An example of the combustion-supporting gas is oxygen (O2).

[0036] The reducing gas supply path L4 is located between the gas supply facility 30 and the reducing furnace 11 (i.e., the manufacturing apparatus 10), and is a path for supplying the reducing gas stored in the gas supply facility 30 to the second space 15 of the reducing furnace 11. Examples of reducing gases include hydrogen (H2) and ammonia (NH3).

[0037] 1 , the reducing gas supply path L4 merges with the raw material supply path L1 upstream of the reducing furnace 11, and the reducing gas is supplied to the second space 15 of the reducing furnace 11 via the reducing gas supply path L4 and the raw material supply path L1. In other words, because the reducing gas flows through the raw material supply path L1, the iron oxide-containing raw material M is entrained by the reducing gas and supplied to the second space 15 of the reducing furnace 11 from above. In this way, because the iron oxide-containing raw material M is entrained by the reducing gas, the iron oxide-containing raw material M remains in the reducing atmosphere for a longer period of time. This improves the efficiency of the reduction reaction.

[0038] The first exhaust gas recovery path L5 is located between the reducing furnace 11 (i.e., the manufacturing apparatus 10) and the raw material supply path L1, and is a path that recovers a portion of the gas in the reducing atmosphere on the outlet side (downstream side) of the second space, or a gas (first exhaust gas) discharged from the second space. The base end of the first exhaust gas recovery path L5 is connected to the opposite side of the second space 15 from the reducing gas supply path L4 (i.e., the outlet side (downstream side) of the second space 15). In addition, the tip of the first exhaust gas recovery path L5 is connected to the same side as the reducing gas supply path L4 (i.e., the inlet side (upstream side) of the second space 15). The first exhaust gas is a mixture of hydrogen, water vapor, and nitrogen.

[0039] The first exhaust gas recovery path L5 is provided with a condenser 16 and a booster 17, in that order from the primary side. The condenser 16 removes moisture such as water vapor contained in the first exhaust gas. The booster 17 pressurizes the first exhaust gas from which moisture has been removed, i.e., the mixed gas containing unreacted hydrogen as reducing gas, to a required pressure, and then supplies the first exhaust gas to the burner 12 again as part of the reducing gas.

[0040] (electric furnace) As shown in FIG. 1, the manufacturing system 50 of this embodiment includes an electric furnace 20 . The electric furnace (also called electric furnace) 20 melts raw materials such as iron scrap using discharge heat generated by arc discharge, removes impurities such as oxygen and nitrogen, and produces steel. The electric furnace 20 is not particularly limited, and a conventionally known structure can be used.

[0041] (Gas supply equipment) The manufacturing system 50 of this embodiment may include a gas supply facility 30 . The gas supply equipment 30 is a storage facility for fuel gas, combustion-supporting gas, and reducing gas used in the production system 50 (i.e., the production apparatus 10). The gas supply equipment 30 is not particularly limited, and conventionally known equipment (e.g., a gas cylinder, a gas production apparatus) can be used.

[0042] (Solid supply equipment) The manufacturing system 50 of this embodiment may include a solid supply facility 40 . The solid supply facility 40 is a storage facility for the iron oxide-containing raw material M used in the production system 50 (i.e., the production apparatus 10). The solid supply facility 40 is not particularly limited, and a conventionally known facility (e.g., a powder storage facility) can be used.

[0043] (route) The manufacturing system 50 of this embodiment includes a second exhaust gas recovery path L6. The second exhaust gas recovery path L6 is located between the electric furnace 20 and the manufacturing apparatus 10 (i.e., the reducing furnace 11). The second exhaust gas recovery path L6 is a path that recovers a portion of gas from the atmosphere inside the electric furnace 20 or the electric furnace exhaust gas (second exhaust gas) discharged from the electric furnace 20. The base end of the second exhaust gas recovery path L6 communicates with the inside of the electric furnace 20, and the tip end of the second exhaust gas recovery path L6 communicates with the fuel gas supply path L2. This allows the second exhaust gas containing oxygen and nitrogen inside the electric furnace 20 to be recovered and supplied again to the burner 12 as part of the fuel gas.

[0044] [Method of manufacturing reduced iron] Next, a method for producing reduced iron according to one embodiment of the present invention will be described using a reduced iron production system 50 shown in FIG. 1 as an example. The method for producing reduced iron of this embodiment (hereinafter simply referred to as the "production method") is a method for producing reduced iron P by forming a high-temperature atmosphere by combustion in a burner and forming a reducing atmosphere by a reducing gas, supplying iron oxide-containing raw materials M into the reducing atmosphere, and reducing the iron oxide-containing raw materials M in the reducing atmosphere heated by the high-temperature atmosphere, wherein the high-temperature atmosphere and the reducing atmosphere are formed so as to be spatially separated.

[0045] Specifically, first, fuel gas and electric furnace exhaust gas (second exhaust gas) as fuel and oxygen as combustion-supporting gas are introduced into a burner 2 installed in a first space (combustion chamber) 14 of the reducing furnace 11. Hydrogen or ammonia as reducing gas and the iron oxide-containing raw material M to be reduced are introduced into a second space (reduction chamber) 15 of the reducing furnace 11. Here, in the manufacturing apparatus 10 (i.e., the reducing furnace 11) constituting the manufacturing system 50 of this embodiment, the first space 14 serving as the combustion chamber and the second space 15 serving as the reduction chamber exist within the same reducing furnace 11, but are spatially separated from each other by the furnace body 13 as a partition wall, resulting in a structure that allows only heat exchange.

[0046] In addition to the electric furnace exhaust gas, fuel gas is added according to the required calorific value, and is introduced into the burner 2 together with a combustion-supporting gas for combustion (see FIG. 2). As a result, a high-temperature atmosphere is formed in the first space (combustion chamber) 14 of the reducing furnace 11 by the combustion gas from the burner 2. The first space 14, now in a high-temperature atmosphere, is heat-transferred to the second space (reduction chamber) 15, where heat is recovered.

[0047] The iron oxide-containing raw material M is continuously introduced into the second space (reduction chamber) 15 of the reduction furnace 11 through the raw material supply path L1. Furthermore, hydrogen or ammonia as a reducing agent is introduced into the second space (reduction chamber) 15 in the same direction as the raw material, i.e., the iron oxide-containing raw material M. This allows the raw material to come into contact with a reducing atmosphere formed by the reducing gas in the second space (reduction chamber) 15. More specifically, the iron oxide-containing raw material M is introduced vertically from above into the second space 15, which serves as the reduction chamber. The iron oxide-containing raw material M falls vertically downward through the second space 15. The second space 15, which serves as the reduction chamber, is heated and raised to a high temperature by heat transfer from the first space 14, which serves as the combustion chamber. The iron oxide-containing raw material M is reduced to reduced iron (metallic iron) P while moving within the reduction chamber, and is then collected in the collection section 19.

[0048] In the manufacturing method of this embodiment, the residence time of the iron oxide-containing raw material M in the reducing atmosphere can be adjusted by adjusting the supply position or supply amount of the reducing gas into the reducing atmosphere in the second space 15. Specifically, by introducing the reducing gas and the raw material from the same direction into the second space (reduction chamber) 15, the iron oxide-containing raw material M, which is the raw material, is entrained by the reducing gas, thereby lengthening the residence time of the iron oxide-containing raw material M in the reducing atmosphere. This improves the efficiency of the reduction reaction of the iron oxide-containing raw material M.

[0049] In the manufacturing method of this embodiment, the atmosphere on the outlet side of the second space 15, which is the reduction chamber, is a mixed gas of hydrogen, water vapor, and nitrogen, so this mixed gas can be recovered and the water vapor can be converted to water and removed in the downstream condenser 16. As a result, only the hydrogen-rich gas can be recovered, pressurized in the pressure booster 17, and then introduced into the second space 15, which is the reduction chamber, so that it can be reused as part of the reducing agent.

[0050] In the manufacturing method of this embodiment, it is possible to recover a portion of the gas from the atmosphere in the electric furnace 20 while it is operating and supply it as part of the fuel gas to be supplied to the burner 12. This makes it possible to reduce the consumption of the fuel gas to be supplied to the burner 12.

[0051] As described above, the manufacturing apparatus 10, manufacturing system 50, and manufacturing method of this embodiment use the reduction furnace 11 in which the first space 14 serving as a combustion chamber and the second space 15 serving as a reduction chamber are separated. This prevents the reducing gas supplied to the second space 15 serving as the reduction chamber from coming into contact with the combustion gas and being partially oxidized. This allows all of the reducing gas supplied to the second space 15 to be used for reducing the iron oxide-containing raw material M. Furthermore, carbon monoxide (CO) contained in the exhaust gas generated in the first space 14 serving as the combustion chamber does not come into contact with the iron oxide-containing raw material M. This stabilizes the concentration of the reducing gas in the second space 15 serving as the reduction chamber, thereby enabling uniform reduced iron P to be obtained.

[0052] Furthermore, according to the manufacturing apparatus 10, manufacturing system 50, and manufacturing method of this embodiment, two or more first spaces (combustion chambers) are arranged to surround the periphery of the second space (reduction chamber) 15. This allows heat from the combustion chamber to be uniformly transferred to the reduction chamber, thereby forming a uniform reducing atmosphere in the second space 15, which serves as the reduction chamber. Therefore, uniform reduced iron P can be obtained.

[0053] Furthermore, according to the manufacturing apparatus 10, manufacturing system 50, and manufacturing method of this embodiment, the reducing gas and the raw material are introduced into the second space (reduction chamber) 15 from the same direction, so that the raw material, i.e., the iron oxide-containing raw material M, is entrained by the reducing gas. This increases the residence time of the iron oxide-containing raw material M in the reducing atmosphere, thereby improving the efficiency of the reduction reaction of the iron oxide-containing raw material M.

[0054] Furthermore, according to the manufacturing apparatus 10, manufacturing system 50, and manufacturing method of this embodiment, a portion of gas can be recovered from the atmosphere in the electric furnace 20 while it is operating, and can be supplied as part of the fuel gas to be supplied to the burner 12. In this way, unused electric furnace exhaust gas (second exhaust gas) can be recovered and combusted by the burner 12, thereby recovering latent heat and sensible heat, resulting in excellent energy efficiency.

[0055] The technical scope of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0056] Specifically, in the manufacturing apparatus 10 of the above-described embodiment, as shown in FIGS. 1 and 2, the reducing gas supply path L4 is connected to the raw material supply path L1 above (upstream of) the reducing furnace 11, and the reducing gas is supplied to the second space 15 via the raw material supply path L1. However, the present application is not limited to this.

[0057] For example, as shown in FIG. 4, a configuration may be used in which a raw material supply path L1 is connected to the second space 15 from the upper end 11a side and a reducing gas supply path L4 is connected to the second space 15 from the lower end 11b side of the reducing furnace 11.

[0058] In the manufacturing apparatus, manufacturing system, and manufacturing method using the reducing furnace 11 of the configuration shown in Fig. 4, the reducing gas and the raw material are introduced into the second space (reduction chamber) 15 from opposite directions, causing the iron oxide-containing raw material M, which is the raw material, to collide with the reducing gas in the second space, thereby improving the efficiency of the reduction reaction of the iron oxide-containing raw material M. In addition, in the reducing furnace 11 of the configuration shown in Fig. 4, the falling speed of the iron oxide-containing raw material M falling from above the second space 15 into the second space 15 can be adjusted by changing the flow rate of the reducing gas introduced into the second space 15 from below, thereby adjusting the residence time of the iron oxide-containing raw material M in the reducing atmosphere. This makes it possible to control the reduction reaction time of the iron oxide-containing raw material M.

[0059] Furthermore, in the manufacturing apparatus 10 of the above-described embodiment, as shown in FIGS. 2 and 3 , the first space 14 and the second space 15 are each cylindrical, and when a horizontal cross section of the axial direction of the reducing furnace 11 is viewed in plan, the case where two or more first spaces 14 are arranged adjacent to each other around the second space 15 is used has been described as an example. However, the present application is not limited to this.

[0060] For example, as shown in FIGS. 5 and 6, a reduction furnace 111 may be used. 6, when the horizontal cross section of the reducing furnace 111 in the axial direction is viewed in plan, a cylindrical first space 114A is arranged in the center of the reducing furnace 111 so as to be coaxial with the central axis of the reducing furnace 111. Furthermore, an annular second space 115 is arranged concentrically with the first space 114A outside the first space 114A. Furthermore, an annular first space 114B is arranged concentrically with the first space 114A and the second space 115 outside the second space 115. That is, in the reducing furnace 111 used in this embodiment, the annular first spaces 114B and the second spaces 115 are arranged alternately in a concentric manner.

[0061] 5 and 6, the manufacturing apparatus, manufacturing system, and manufacturing method using the reducing furnace 111 have a structure in which the first space 114A, the second space 115, and the first space 114B are spatially separated from one another. This allows uniform reduced iron P to be obtained, similar to the case where the reducing furnace 11 of the above-described embodiment is used. Furthermore, the first space 114A is located inside the annular second space 115, and the first space 114B is located outside it. This allows heat from the combustion chamber to be uniformly transferred to the reduction chamber. This allows a uniform reducing atmosphere to be formed in the second space 115, which serves as the reduction chamber, similar to the case where the reducing furnace 11 of the above-described embodiment is used.

[0062] Furthermore, in the manufacturing system 50 and manufacturing method of the above-described embodiment, as shown in FIG. 1, a case has been described as an example in which a portion of gas is recovered from the atmosphere inside the electric furnace 20 and used as part of the fuel gas supplied to the burner 12 that constitutes the manufacturing apparatus 10, but the present application is not limited to this.

[0063] 7 and 8, a manufacturing system 150 may be used in which a reducing furnace 11 included in the manufacturing apparatus 10 is connected to an electric furnace 120. According to the manufacturing system 150 of this embodiment, reduced iron P obtained by the manufacturing apparatus 10 can be supplied from the reducing furnace 11 to the electric furnace 120.

[0064] Here, an example of the configuration of the manufacturing system 150 and the electric furnace 120 of this embodiment will be specifically described.

[0065] As shown in FIG. 7, the manufacturing system 150 of this embodiment includes the manufacturing apparatus 10 and an electric furnace 120.

[0066] The electric furnace 120 is generally configured to include a furnace body 21 and an electrode 22 that generates an arc. The electric furnace 120 melts the iron source (reduced iron P, other scrap, etc.) inside by the arc of the electrode 22.

[0067] At least the lower part of the furnace body 21 is made of a refractory material 24. This allows the furnace body 21 to store iron (molten steel) 23 melted by the electrodes 22.

[0068] An electrode 22 is provided above the furnace body 21 so as to penetrate the furnace body 21. The tip of the electrode 22 is provided so as to face the molten steel 23 in the space inside the furnace body 21.

[0069] An exhaust duct 25 is provided above the furnace body 21. This exhaust duct 25 allows the atmosphere inside the electric furnace 120 to be discharged to the outside of the furnace body 21 as electric furnace exhaust gas (second exhaust gas).

[0070] A second exhaust gas recovery path L6 is connected to the exhaust duct 25. This allows a portion of the gas from the atmosphere inside the electric furnace 120 or the electric furnace exhaust gas (second exhaust gas) discharged from the electric furnace 120 to be recovered and supplied to the burner 12 of the manufacturing apparatus 10. By burning the electric furnace exhaust gas (second exhaust gas) using the burner 12, the latent heat and sensible heat of the unused electric furnace exhaust gas (second exhaust gas) can be recovered.

[0071] Above the furnace body 21, the manufacturing apparatus 10 is connected so as to penetrate the furnace body 21. Specifically, an outlet 18 for reduced iron P provided at the lower end of the reduction furnace 11 constituting the manufacturing apparatus 10 is provided so as to communicate with the space inside the furnace body 21. This allows the reduced iron P manufactured by the manufacturing apparatus 10 to be supplied inside the furnace body 21. [Example]

[0072] The effects of the present invention will be explained below using experimental examples, but the present invention is not limited to the following descriptions in any way.

[0073] (Examples 1 to 3) As the reduced iron production system, a reduced iron production system 50 shown in Figs. 1 to 3 was used. In the reduced iron manufacturing apparatus, combustion gases including electric furnace exhaust gas, fuel, and oxygen gas were introduced via a burner into the first space, which was the combustion chamber. Furthermore, iron oxide-containing raw materials and hydrogen or ammonia as a reducing gas were introduced into the second space, which was the reduction chamber. Table 1 below shows the types of gases introduced into the reduced iron manufacturing apparatus, as well as the mass balance and energy balance in Examples 1 to 3.

[0074] In the production system 50, the exhaust gas discharged from the second space 15, which is the reduction chamber, is a mixed gas of hydrogen, nitrogen, and water vapor. Therefore, the water vapor contained in the mixed gas is removed by the condenser 16, and then the pressure is increased by the pressure booster 17, and the gas is reintroduced into the reduction chamber as part of the reduction gas.

[0075] Furthermore, when ammonia is used as the reducing gas, the exhaust gas discharged from the second space 15 contains nitrogen, and therefore the hydrogen partial pressure in the reduction chamber gradually decreases when the ammonia is reintroduced into the reduction chamber. In this case, a concentration control valve is provided between the condenser 16 and the pressure booster 17, and the hydrogen partial pressure in the process is kept constant by opening this concentration control valve as appropriate. In this way, reduced iron was obtained. Table 1 below shows the yields and reduction rates of reduced iron in Examples 1 to 3.

[0076] (Comparative Example 1) 1 to 3 was used as the reduced iron manufacturing system. In Comparative Example 1, it was assumed that a reduction furnace was used in which the first space 14 serving as the combustion chamber and the second space 15 serving as the reduction chamber were not spatially separated (i.e., the reducing gas was partially oxidized by the combustion gas), and reduced iron was obtained in the same manner as in Examples 1 to 3 except that carbon monoxide was used as the reducing gas, as shown in Table 2. The yield of reduced iron and the reduction rate of reduced iron in Comparative Example 1 are shown in Table 2 below.

[0077] (Comparative Examples 2 to 4) In Comparative Examples 2 to 4, a reduction furnace was used as a reduced iron production system in which the first space serving as a combustion chamber and the second space serving as a reduction chamber were not spatially separated. Iron oxide-containing raw materials and hydrogen or ammonia as a reducing gas were introduced into the reduction furnace. Electric furnace exhaust gas, fuel, and combustion gases of oxygen gas were also introduced into the reduction furnace. Table 2 below shows the types of gases introduced into the reduction furnace, as well as the mass balance and energy balance for Comparative Examples 2 to 4. In this way, reduced iron was obtained in the reduction furnace. Table 2 below shows the yields and reduction rates of reduced iron in Comparative Examples 2 and 3.

[0078] [Table 1]

[0079] [Table 2]

[0080] As shown in Table 1, uniform reduced iron was obtained in Examples 1 to 3. This is because the use of the reduction furnace 11 in which the first space 14 serving as the combustion chamber and the second space 15 serving as the reduction chamber are separated enables all of the reducing gas supplied to the second space 15 to be used for reducing the iron oxide-containing raw material M, and the concentration of the reducing gas in the second space 15 serving as the reduction chamber is stabilized.

[0081] In Example 1, hydrogen gas was used as the reducing gas, and reduced iron was obtained at a high reduction rate. In Example 2, ammonia was used as the reducing gas, and reduction was possible with a smaller amount of reducing gas than in Example 1. In Example 3, the calorific value of the electric furnace exhaust gas was different from that in Examples 1 and 2, and by introducing methane gas as fuel into the first space 14, which is the combustion chamber, performance (yield and reduction rate of reduced iron) equivalent to that in Example 1 was ensured.

[0082] As shown in Table 2, it was confirmed that the reduction rate in Comparative Example 1 was inferior to that in Example 1. This is because carbon monoxide used as the reducing gas has a lower reducing power than hydrogen or ammonia.

[0083] Furthermore, it was confirmed that the reduction rates were inferior in Comparative Examples 2 to 4 compared to Examples 1 to 3 under the same flow rate conditions. This is because the reducing gas was partially burned, which caused unevenness in the reducing gas concentration in the reducing furnace and resulted in inferior reducing power. Furthermore, it was confirmed that the yield of reduced iron decreased in Comparative Examples 2 to 4. This is because the temperatures in the combustion chamber and the reduction chamber became non-uniform, generating localized high-temperature fields, which caused the iron oxide-containing raw material to adhere to the inner walls, making it difficult to increase the amount of raw material input. [Explanation of symbols]

[0084] 10,110 Reduced iron manufacturing equipment (manufacturing equipment) 11 Reduction furnace 12 Burner 13 Furnace body (partition wall) 14 First space (combustion chamber) 15 Second space (reduction chamber) 16 Condenser 17 Booster 18 Outlet 19 Collection Department 20,120 electric furnace 30 Gas supply equipment 40 Solids supply equipment 50,150 Reduced iron production system (production system) L1 Raw material supply route (route) L2 fuel gas supply route L3 Combustion-supporting gas supply route L4 Reducing gas supply path L5 First exhaust gas recovery route L6 Second exhaust gas recovery route M Iron oxide-containing raw materials P reduced iron

Claims

1. A furnace body that airtightly separates adjacent spaces; One or more first spaces defined by the furnace body; a reduction furnace having one or more second spaces defined by the furnace body; one or more burners for supplying combustion gas to the first space; a raw material supply path for supplying an iron oxide-containing raw material to the second space; a fuel gas supply path for supplying fuel gas to the burner; a reducing gas supply path that supplies a reducing gas to the second space, The first space is disposed adjacent to the second space, and heat is transferred between the second space and the first space via the furnace body.

2. the reduction furnace is a vertical furnace whose axial direction extends vertically, the first space and the second space are cylindrical spaces whose axial directions extend vertically, the burner is located at an upper end of the reducing furnace, and the combustion gas is supplied downward from above the first space, The apparatus for producing reduced iron according to claim 1 , wherein the raw material supply path is connected to an upper portion of the second space, and the iron oxide-containing raw material is supplied from above the second space.

3. the reducing gas supply path merges with the raw material supply path above the second space, The apparatus for producing reduced iron according to claim 2 , wherein the iron oxide-containing raw material is supplied from above the second space while being entrained by the reducing gas.

4. the reducing gas supply path is connected to a lower portion of the second space, The apparatus for producing reduced iron according to claim 2 , wherein the reducing gas is supplied from below the second space.

5. a first exhaust gas recovery path that recovers the first exhaust gas discharged from the second space; a condenser located in the first exhaust gas recovery path and removing moisture from the first exhaust gas; a booster located on the secondary side of the condenser in the first exhaust gas recovery path, a base end of the first exhaust gas recovery path is connected to the second space on the opposite side to the reducing gas supply path, with the second space being sandwiched therebetween; The apparatus for producing reduced iron according to claim 2 , wherein an end of the first exhaust gas recovery path is connected to the second space on the same side as the reducing gas supply path.

6. When the horizontal cross section in the axial direction of the reduction furnace is viewed in plan, The apparatus for producing reduced iron according to claim 2 , wherein the reduction furnace includes two or more first spaces arranged adjacent to each other around the second space.

7. When the horizontal cross section in the axial direction of the reduction furnace is viewed in plan, The apparatus for producing reduced iron according to claim 2 , wherein the first space and the second space, each having an annular shape, are concentrically arranged alternately in the reduction furnace.

8. The apparatus for manufacturing reduced iron according to claim 2 , wherein a discharge port for reduced iron is located below the second space.

9. The apparatus for producing reduced iron according to any one of claims 1 to 8, An electric furnace, a second exhaust gas recovery path that recovers a second exhaust gas discharged from the electric furnace, a base end of the second exhaust gas recovery path communicating with the electric furnace and a tip end of the second exhaust gas recovery path communicating with the fuel gas supply path;

10. the reduction furnace constituting the reduced iron production apparatus is connected to the electric furnace, The system for producing reduced iron according to claim 9 , wherein reduced iron is supplied from the reduction furnace to the electric furnace.

11. 1. A method for producing reduced iron by forming a high-temperature atmosphere by combustion in a burner and forming a reducing atmosphere by a reducing gas, supplying an iron oxide-containing raw material into the reducing atmosphere, and reducing the iron oxide-containing raw material in the reducing atmosphere heated by the high-temperature atmosphere, the high-temperature atmosphere and the reducing atmosphere are formed so as to be spatially separated from each other.

12. The method for producing reduced iron according to claim 11, wherein the iron oxide-containing raw material is supplied into the reducing atmosphere from above the reducing atmosphere.

13. The method for producing reduced iron according to claim 11, wherein a residence time of the iron oxide-containing raw material in the reducing atmosphere is adjusted by at least one of a supply position and a supply amount of the reducing gas into the reducing atmosphere.

14. 12. The method for producing reduced iron according to claim 11, wherein a part of the gas is recovered from the reducing atmosphere, moisture contained in the recovered gas is removed, and the gas is then pressurized and supplied to the reducing atmosphere as a part of the reducing gas.

15. The method for producing reduced iron according to claim 11, wherein a part of the gas is recovered from the atmosphere in the electric furnace and supplied as a part of the fuel gas supplied to the burner.

16. The method for producing reduced iron according to claim 15, wherein the reduced iron obtained in the reducing atmosphere is supplied to the electric furnace.

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