Method for producing reduced iron

Abstract

An object of the present invention is to suppress or prevent stagnation of the flow of the raw material and to suppress or prevent clogging of the holes in the dispersion member. [Solution] The present invention provides a method for producing a flame in a vessel, the method comprising: a vessel having an internal space capable of accommodating raw materials including iron ore and a reducing gas; a dispersion member provided with a plurality of holes through which the reducing gas can pass and disposed inside the vessel; and a burner disposed above the dispersion member at a height away from the dispersion member determined using a target flow rate of the reducing gas to be supplied inside the vessel, the burner generating a flame inside the vessel, the height of the burner being determined based on a diameter (d or ) and the flow rate of the reducing gas (u or ), and the depth (l j ) and is equal to or lower than the height of the top of the raw material layer.

Description

[Technical Field]

[0001] The present invention relates to a reduction furnace and a method for producing reduced iron, and more particularly to a reduction furnace and a method for producing reduced iron that can facilitate the flow of raw materials and prevent or suppress clogging of the pores of the dispersion material. [Background technology]

[0002] The blast furnace process requires various ancillary facilities, such as coke production equipment and sintering ore production equipment. Furthermore, environmental pollution occurs due to substances emitted from these ancillary facilities, leading to the disadvantage of high costs associated with pollution control equipment.

[0003] Therefore, a method is employed that directly uses powdered iron ore (powdered iron), which accounts for more than 80% of the world's ore production, to manufacture molten iron. Such molten iron manufacturing facilities are equipped with a fluidized bed reduction furnace that reduces powdered iron to produce reduced iron, and a melting apparatus that melts the reduced iron from the fluidized bed reduction furnace to produce molten iron.

[0004] The fluidized bed reduction furnace comprises a container and a dispersion member having multiple holes through which gas can pass. The dispersion member is placed inside the container, reducing gas is supplied to the lower side of the dispersion member, and powdered iron ore is charged to the upper side of the dispersion member.

[0005] When reducing gas is supplied to the lower side of the dispersion member, the reducing gas passes through multiple holes provided in the dispersion member and is blown upward. The reducing gas blown upward in this way causes the powdered iron ore on the upper side of the dispersion member to flow. As the powdered iron ore flows, it reacts with the reducing gas, thereby reducing the powdered iron ore and producing reduced iron.

[0006] For the powdered iron ore and reducing gas to react smoothly inside a fluidized bed reduction furnace, the internal temperature of the furnace must be maintained above a predetermined level. However, since the reaction between powdered iron ore and reducing gas is predominantly endothermic, there is a risk that the internal temperature of the fluidized bed reduction furnace may drop during the reduction reaction. To resolve this problem, a burner is installed inside the fluidized bed reduction furnace to generate a flame and heat the furnace. In this case, the burner is positioned above the dispersion member.

[0007] On the other hand, if the flame temperature from the burner is too high, the iron ore particles may melt and become entangled with each other. When the iron ore particles become entangled and form clumps, the flow of the iron ore is not smooth. As a result, a congestion phenomenon occurs where the iron ore does not flow at all, or only flows very slowly.

[0008] Furthermore, if the flame temperature is too high, or if the distance between the burner and the dispersion material is too short, the temperature of the dispersion material will also become too high. In such cases, the iron ore particles are melted by the heat of the dispersion material and become entangled with each other, which clogs the pores of the dispersion material. When the pores of the dispersion material become clogged, the reducing gas cannot pass through, resulting in the disadvantage that the flow of iron ore particles on the upper side of the dispersion material cannot proceed smoothly. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Korean Published Patent No. 10-2007-0068210 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] This invention was created in view of the above circumstances, and its purpose is to provide a reduction furnace and a method for producing reduced iron that can suppress or prevent stagnation of the flow of raw materials.

[0011] Another object of the present invention is to provide a reduction furnace and a method for producing reduced iron that can suppress or prevent clogging of the pores of the dispersion material.

[0012] Another object of the present invention is to provide a reduction furnace capable of lowering the flame temperature and a method for producing reduced iron. [Means for solving the problem]

[0013] To achieve the above objective, an embodiment of the present invention provides a reduction furnace comprising: a container having an internal space capable of containing raw materials including iron ore and reducing gas; a dispersion member disposed inside the container and having a plurality of holes through which the reducing gas can pass; and a burner disposed above the dispersion member and at a height determined using a target flow rate of reducing gas to be supplied into the container, for generating a flame inside the container.

[0014] The installation height of the burner is adjusted according to the target flow rate of the reducing gas, and the diameter of the holes (d) provided in the dispersion member is adjusted accordingly. or ) and the flow velocity of the reducing gas (u or The height may be determined using at least one of the following:

[0015] The height at which the burner is installed is the depth l to which the reducing gas penetrates into the raw material layer, which consists of the raw materials supplied above the dispersion member. j The above is acceptable, and the height may be less than or equal to the height of the top of the raw material layer.

[0016] The burner may comprise a main body extending in one direction, and a plurality of nozzles arranged inside the main body, extending in the direction of the main body's extension, such that the distance between them gradually decreases as they approach one end of the main body.

[0017] The angle at which each of the aforementioned nozzles is tilted may be between 20° and 45°.

[0018] The plurality of nozzles may be provided symmetrically with respect to the center in the diameter direction of the main body.

[0019] In order to achieve the above object, the method for producing reduced iron according to the present invention uses the target flow rate of the reducing gas to be supplied to the container of the reduction furnace, and the installation height H of the burner based on the dispersion member disposed inside the container b in the process of determining, and the separation distance from the dispersion member upward is the determined installation height H b in the process of disposing the burner in the container so as to be, the process of supplying the raw material containing iron ore above the dispersion member, the process of passing the reducing gas through the holes of the dispersion member to flow the raw material above the dispersion member, the process of generating a flame inside the container using the burner, and the process of reacting the raw material and the reducing gas to reduce the raw material.

[0020] The method for producing reduced iron includes, before the process of determining the installation height H of the burner b the process of determining the target flow rate of the reducing gas, and the process of determining the flow velocity u or of the reducing gas to be supplied to the container using the determined target flow rate of the reducing gas and the diameter d or of the holes provided in the dispersion member.

[0021] The process of determining the installation height H of the burner b includes the process of predicting the depth l or to which the reducing gas penetrates into the raw material layer above the dispersion member using the diameter d or of the holes and the flow velocity u j of the reducing gas, and the process of determining the installation height H j of the burner so as to be at a height equal to or greater than the predicted penetration depth l b .

[0022] The process of predicting the depth l j to which the reducing gas penetrates into the raw material layer uses the diameter d or of the holes and the flow velocity u or), density of reducing gas (ρ g ), density of raw material particles (ρ s ), particle size of raw material particles (d p ), the penetration depth of the reducing gas (l) is determined using the dynamic viscosity (μ) of the reducing gas. j This may include the process of calculating ).

[0023] The method for producing reduced iron is as follows: The burner is positioned at height H b the predicted penetration depth l j The above is true, and the process may include determining the value within a range that is less than or equal to the height of the top of the raw material layer.

[0024] The process of generating a flame inside the container using the burner may include the steps of supplying an oxidizing agent to each of a plurality of nozzles provided on the burner, blowing the oxidizing agent from each of the plurality of nozzles to form an oxidizing agent stream, causing the plurality of oxidizing agent streams to collide with each other to diffuse the oxidizing agent streams, and reacting the oxidizing agent streams with a reducing gas to generate a flame.

[0025] The process of spraying the oxidizing agent from each of the plurality of nozzles may include a process of spraying the oxidizing agent from each of the plurality of nozzles in such a way that the flow is inclined so that as it moves away from the burner, it gradually approaches the diametrical center of the burner.

[0026] The oxidizing agent may contain oxygen (O) and nitrogen (N2).

[0027] The method for producing reduced iron may include a step of adjusting the flow rate of the oxidizing agent sprayed from each of the plurality of nozzles to 80 m / sec to 100 m / sec.

[0028] The reducing gas may contain hydrogen (H2) gas. [Effects of the Invention]

[0029] According to the present invention, it is possible to suppress or prevent the dispersion material from being heated to a high temperature by the heat of the flame emitted from the burner. Furthermore, it is possible to generate a flame at a lower temperature than in the conventional method. As a result, it is possible to suppress or prevent aggregation due to the melting of raw material particles, thereby suppressing or preventing the formation of a congested layer. Consequently, the raw material can be allowed to flow smoothly inside the reduction furnace.

[0030] Furthermore, while suppressing or preventing the formation of congestion layers, sufficient heat can be applied to the raw materials and reducing gas to ensure that the reduction reaction proceeds smoothly. [Brief explanation of the drawing]

[0031] [Figure 1] This is a schematic diagram illustrating the molten iron manufacturing equipment of the present invention. [Figure 2] This is a diagram showing the reduction furnace of the present invention. [Figure 3] This is a cross-sectional view showing a magnified portion of the reduction furnace. [Figure 4] This is a front cross-sectional view of the burner of the present invention. [Figure 5] This is a plan view of the burner of the present invention. [Figure 6] This diagram illustrates the flow of the oxidizing agent sprayed from the burner of the present invention. [Figure 7] This is a schematic diagram of an experimental reduction furnace. [Figure 8] This is the result of measuring the horizontal temperature at a predetermined height in the experimental reduction furnace. [Figure 9] This is the result of measuring the temperature in the region from the dispersion material to a predetermined height above it in an experimental reduction furnace. [Figure 10] This result shows the temperature distribution at different heights inside an experimental reduction furnace when a first type of burner, equipped with a single nozzle, is placed inside the vessel to generate a flame. [Figure 11]This result shows the temperature distribution at different heights inside an experimental reduction furnace when a second type of burner, equipped with first and second nozzles, is placed inside the vessel and a flame is generated. [Modes for carrying out the invention]

[0032] The present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention is not limited in any way to the embodiments disclosed below and can be embodied in a variety of different forms, and these embodiments are provided merely to complete the disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention. In describing the present invention, the same reference numerals are used for the same components, and the drawings may be partially exaggerated in size to accurately illustrate embodiments of the present invention, and in the drawings, the same reference numerals refer to the same components.

[0033] Figure 1 is a schematic diagram showing the molten iron manufacturing equipment of the present invention.

[0034] As shown in Figure 1, the molten iron production equipment of the present invention comprises a reduced iron production apparatus 2000 equipped with a reduction section 2100 capable of producing reduced iron, and a melting apparatus 3000 capable of dissolving reduced iron. The molten iron production equipment may also include a raw material supply apparatus 1000 arranged to supply raw materials to the reduction section 2100, and an exhaust gas supply line 4000 arranged to connect the melting apparatus 3000 and the reduction section 2100 so as to supply exhaust gas discharged from the melting apparatus 3000 to the reduction section 2100.

[0035] Furthermore, the molten iron production equipment may include a molding device (not shown) for molding the reduced iron in powder form produced in the reduced iron production apparatus 2000.

[0036] The raw material supply device 1000 is arranged to supply raw materials to the reduction unit 2100. Here, the raw materials may include iron ore, and the iron ore may include fine iron ore powder, i.e., powdered iron ore, whose particle size is greater than 0 mm and less than or equal to 0 mm. The raw material supply device 1000 may, for example, be equipped with a storage container capable of storing the raw materials. The raw materials may be stored in the internal space of the storage container for a long period of time, or the raw materials may be temporarily stored there before being supplied to the reduced iron production device 2000. Such a storage container may, for example, be equipped with a hopper.

[0037] The dissolving apparatus 3000 receives reduced iron from the reduced iron production apparatus 2000 and dissolves the supplied reduced iron. At this time, the dissolving apparatus 3000 may be made of finely powdered reduced iron, or it may be made of reduced iron prepared by forming finely powdered reduced iron into agglomerates in a molding apparatus.

[0038] The melting apparatus 3000 may be, for example, a device that melts reduced iron using electric heat. That is, the melting apparatus 3000 may be a device that melts reduced iron using electrical energy. In addition, scrap iron or the like may be supplied to the melting apparatus 3000 in addition to reduced iron, and the melting apparatus 3000 may melt the reduced iron and scrap iron together. Such a melting apparatus 3000 may be equipped with an electric furnace having a melting space capable of melting reduced iron using electric heat. Such an electric furnace may be equipped with an electric furnace body 3100 having a melting space and an electrode rod 3200 in which at least a part is placed in the melting space so as to generate electric heat. When reduced iron is charged into the melting space of the electric furnace, the electric furnace applies power to the electrode rod 3200 to melt the reduced iron, thereby producing molten iron. The exhaust gas generated during the production of molten iron from the electric furnace may be supplied to the reduction unit 2100 via the exhaust gas supply line 4000.

[0039] When reduced iron is dissolved in the dissolution apparatus 3000, gas is produced, and this gas contains at least one of the flammable components CO (carbon monoxide) and CH4 (methane). The aforementioned CO (carbon monoxide) and CH4 (methane) are components that can be reduced with iron ore. Therefore, the gas produced and discharged in the dissolution apparatus 3000 (hereinafter referred to as exhaust gas) is recovered and supplied to the reduction section of the reduced iron production apparatus. In the reduced iron production apparatus, the exhaust gas supplied from the dissolution apparatus 3000 is used to reduce the iron ore. At this time, the exhaust gas discharged from the dissolution apparatus 3000 may be supplied to the reduction section 2100 via the exhaust gas supply line 4000.

[0040] The above describes the melting apparatus 3000 being equipped with an electric furnace. However, the present invention is not limited thereto, and the melting apparatus 3000 may also be equipped with a molten gasification furnace. Inside the molten gasification furnace, a coal-filled bed made of coal is formed. Reduced iron and auxiliary materials are introduced into the molten gasification furnace, and oxygen is blown in through numerous air vents arranged on the outer wall. As a result, the coal-filled bed is burned by the blown-in oxygen, and the reduced iron is melted to produce molten iron. The exhaust gas generated during the production of molten iron from the molten gasification furnace may be supplied to the reduction unit 2100 via the exhaust gas supply line 4000.

[0041] The reduced iron production apparatus 2000 includes a reduction unit 2100 for producing reduced iron by reducing iron ore. The reduced iron production apparatus 2000 may also include a hydrogen gas supply unit 2200 for supplying a reducing gas containing hydrogen to the reduction unit 2100.

[0042] First, let's describe the hydrogen gas supply unit 2200. The hydrogen gas supply unit 2200 supplies hydrogen gas, which is the reduction gas used to reduce the raw material, i.e., iron ore, to the reduction unit 2100. On the other hand, the by-products generated when the raw material is reduced in the reduction unit 2100 include water vapor, hydrogen gas, nitrogen gas, and carbon dioxide gas. The hydrogen gas supply unit 2200 may also be a means provided to process the by-products generated and discharged in the reduction unit 2100 to produce hydrogen gas and supply this hydrogen gas to the reduction unit 2100.

[0043] Such a hydrogen gas supply unit 2200 may include an exhaust pipe 2210 connected to the reduction unit 2100 so as to be able to discharge by-products generated in the reduction unit 2100, an extractor 2220 connected to the exhaust pipe 2210 so as to be able to extract hydrogen gas from the supplied by-products, a supply pipe 2230 arranged to connect the extractor 2220 and the reduction unit 2100 so as to be able to supply hydrogen gas extracted or generated in the extractor 2220 to the reduction unit 2100, and a heater 2240 arranged on the extension path of the supply pipe 2230 for heating the hydrogen gas generated in the extractor 2220. Furthermore, the hydrogen gas supply unit 2200 may further include a dust collector 2250 arranged on the exhaust pipe 2210 so as to be able to collect dust such as fine particles from the by-products.

[0044] The dust collector 2250 may be positioned in the exhaust pipe 2210 between the extractor 2220 and the reduction unit 2100. Alternatively, the dust collector 2250 may be a wet dust collector that collects dust by a wet method, for example. Needless to say, the dust collector 2250 is not limited to the examples described above, and a wide variety of means capable of collecting dust from by-products can be employed.

[0045] The extractor 2220 extracts hydrogen gas from the by-products discharged from the reduction unit 2100. As described above, the by-products discharged from the reduction unit 2100 include water vapor, hydrogen gas, nitrogen gas, and carbon dioxide gas. The extractor 2220 extracts hydrogen gas from the by-products supplied from the exhaust pipe 2210. Such an extractor 2220 may be a means of extracting hydrogen gas from the by-products by, for example, a pressure swing adsorption (PSA) method. That is, the pressure swing adsorption method extracts gas using the adsorption selectivity of each component to the adsorbent, but the extractor 2220 may use a carbon molecular sieve capable of adsorbing hydrogen components as an adsorbent in order to extract hydrogen gas from by-products that contain various gases in addition to hydrogen gas. In this case, the hydrogen component adsorbed on the adsorbent can be desorbed and extracted as hydrogen gas, and the extractor 2220 may extract hydrogen gas from the by-product by repeatedly performing the adsorption and desorption of the hydrogen component in this manner.

[0046] The hydrogen gas extracted in the extractor 2220 is supplied to the reduction unit 2100 via the supply pipe 2230. The hydrogen gas supplied to the reduction unit 2100 in this manner can be used to reduce the iron ore in the reduction unit 2100. In other words, the hydrogen gas supplied to the reduction unit 2100 reduces the iron ore. For this reason, the hydrogen gas supplied to the reduction unit 2100 can be called a "reducing gas" that reduces iron ore.

[0047] In the reduction unit 2100, the raw material containing iron ore is reacted with hydrogen gas extracted in the extractor 2220 to reduce the iron ore. At this time, since the reaction between iron ore and hydrogen gas is a strong endothermic reaction, the reaction efficiency can be improved by heating the hydrogen gas supplied to the reduction unit 2100 to a temperature of 800°C or higher, more preferably 850°C or higher. Therefore, a heater 2240 is positioned on the extension path of the supply pipe 2230 so as to be located between the extractor 2220 and the reduction unit 2100. The heater 2240 heats the hydrogen gas supplied from the extractor 2220, and the heated hydrogen gas is supplied to the reduction unit 2100 via the supply pipe 2230. A wide variety of means can be used to heat the hydrogen gas by direct heating or indirect heating.

[0048] In order to reduce all of the iron ore supplied to the reduction unit 2100, a sufficient amount of hydrogen gas must be supplied. Generally, hydrogen gas is very expensive, so there is a problem of high costs involved in purchasing hydrogen gas separately and supplying it to the reduction unit 2100. However, in this embodiment, hydrogen gas is extracted from the by-products discharged from the reduction unit 2100 and supplied back to the reduction unit 2100 to be used as reducing gas. In other words, the by-products generated in the reduction unit 2100 are reused. This makes it possible to reduce the cost of producing reduced iron.

[0049] The above has described how the hydrogen gas supply unit 2200 is provided to produce hydrogen gas by post-processing or reforming by-products discharged from the reduction unit 2100 and supplying it to the reduction unit 2100. However, the hydrogen gas supply unit 2200 may also be provided to supply hydrogen gas to the reduction unit 2100 without reusing the by-products discharged from the reduction unit 2100. In such a case, the hydrogen gas supply unit 2200 may be provided to include a reservoir in which hydrogen gas is stored, a supply pipe 2230 connecting the reservoir and the reduction unit, and a heater 2240 disposed on the extension path of the supply pipe 2230 to heat the hydrogen gas.

[0050] Thus, the process of producing reduced iron by reducing iron ore using hydrogen gas, and then producing molten iron by melting the reduced iron, may be called the "hydrogen reduction ironmaking process." In the hydrogen reduction ironmaking process, hydrogen gas is supplied to the reduction unit 2100 to reduce the raw material. The hydrogen gas reacts with the iron ore to produce water or steam, but does not produce carbon dioxide. Therefore, when hydrogen gas is supplied to the reduction unit 2100 to reduce the raw material, there is an effect of reducing carbon emissions. In other words, a hydrogen reduction ironmaking process in which only hydrogen gas is supplied to the reduction unit 2100 to reduce the raw material, or a mixture of exhaust gas discharged from the dissolution device 3000 and hydrogen gas is supplied to the reduction unit 2100 to reduce the raw material, has the effect of reducing carbon emissions compared to a process in which only exhaust gas is used to reduce the raw material.

[0051] Needless to say, the embodiment is applicable not only to hydrogen reduction ironmaking processes in which only hydrogen gas is supplied to the reduction unit 2100, or to general ironmaking processes in which exhaust gas discharged from the dissolving device 3000 is mixed with hydrogen gas and supplied to the reduction unit 2100, but also to general ironmaking processes in which only exhaust gas discharged from the dissolving device 3000 is supplied to the reduction unit 2100.

[0052] The reduction unit 2100 produces reduced iron by reducing the raw materials. Specifically, the reduction unit 2100 receives raw materials, including iron ore, from the raw material supply device 1000, and produces reduced iron by reacting the iron ore with a reducing gas. Here, the reducing gas supplied to the reduction unit 2100 may contain at least one of the following: hydrogen gas supplied from the hydrogen gas supply unit 2200 and exhaust gas discharged from the dissolution device 3000.

[0053] In describing the reduction unit 2100 below, the hydrogen gas supplied from the hydrogen gas supply unit 2200 and the exhaust gas supplied from the dissolution device 3000 to the reduction unit 2100 will be collectively referred to as "reducing gas."

[0054] The reduction unit 2100 may be equipped with a reduction furnace that produces reduced iron while the raw material is flowing. The reduction furnace may be provided as a single unit, but may be provided in multiple units to effectively reduce low-grade iron ore or powdered iron ore with a low iron content. In this case, where multiple reduction furnaces are provided, the reduction unit 2100 may be equipped with multiple raw material transport pipes 2111a to 2111c and multiple gas transport pipes 2112a to 2112c arranged to connect the multiple reduction furnaces 2100a to 2100d.

[0055] As mentioned above, there may be multiple reduction furnaces 2100a to 2100d. The multiple reduction furnaces 2100a to 2100d may be connected to each other so that the raw materials can be moved sequentially, as shown in Figure 1. The number of reduction furnaces 2100a to 2100d is not particularly limited, but in order to sufficiently reduce the raw materials, the reduction unit 2100 may be equipped with four reduction furnaces (first to fourth reduction furnaces 2100a to 2100d). When the reduction unit 2100 is equipped with four reduction furnaces 2100a to 2100d, the reduction unit 2100 may also be equipped with three raw material transport pipes 2111a to 2111c and three gas transport pipes 2112a to 2112c.

[0056] The exhaust pipe 2210 of the hydrogen gas supply unit 2200 may be connected to the first reduction furnace 2100a, one of the first to fourth reduction furnaces 2100a to 2100d. That is, the raw material supply unit 1000 is arranged to be connected to the first reduction furnace 2100a, and therefore the raw material discharged from the raw material supply unit 1000 is charged into the first reduction furnace 2100a. The exhaust pipe 2210 of the hydrogen gas supply unit 2200 is then connected to the first reduction furnace 2100a. As a result, by-products discharged from the first reduction furnace 2100a are discharged through the exhaust pipe 2210.

[0057] Of the first to fourth reduction furnaces 2100a to 2100d, the fourth reduction furnace 2100d is connected to at least one of the supply pipe 2230 of the hydrogen gas supply unit 2200 and the exhaust gas supply line 4000. Therefore, the hydrogen gas extracted in the extractor 2220 can be supplied to the fourth reduction furnace 2100d via the supply pipe 2230, and the exhaust gas from the dissolution device 3000 can be supplied to the fourth reduction furnace 2100d via the exhaust gas supply line 4000.

[0058] Raw material transport pipes 2111a to 2111c are arranged to connect the first to fourth reduction furnaces 2100a to 2100d. Specifically, the first raw material transport pipe 2111a is placed between the first reduction furnace 2100a and the second reduction furnace 2100b, the second raw material transport pipe 2111b is placed between the second reduction furnace 2100b and the third reduction furnace 2100c, and the third raw material transport pipe 2111c is placed between the third reduction furnace 2100c and the fourth reduction furnace 2100d. Therefore, the raw material supplied to the first reduction furnace 2100a and primarily reduced is supplied to the second reduction furnace 2100b via the first raw material transport pipe 2111a, the raw material secondarily reduced in the second reduction furnace 2100b is supplied to the third reduction furnace 2100c via the second raw material transport pipe 2111b, and the raw material tertiarily reduced in the third reduction furnace 2100c is supplied to the fourth reduction furnace 2100d via the third raw material transport pipe 2111c. Then, the raw material quaternarily reduced in the fourth reduction furnace 2100d, i.e., reduced iron, is supplied to the dissolution apparatus 3000.

[0059] Gas transport pipes 2112a to 2112c are arranged to connect the first to fourth reduction furnaces 2100a to 2100d. Specifically, the first gas transport pipe 2112a is placed between the fourth reduction furnace 2100d and the third reduction furnace 2100c, the second gas transport pipe 2112b is placed between the third reduction furnace 2100c and the second reduction furnace 2100b, and the third raw material transport pipe 2111c is placed between the second reduction furnace 2100b and the first reduction furnace 2100a. As a result, the reducing gas supplied to the fourth reduction furnace 2100d is sequentially transported to the second to fourth reduction furnaces 2100a to 2100d via the first to third gas transport pipes 2112a to 2112b. That is, the reducing gas supplied to the fourth reduction furnace 2100d is supplied to the third reduction furnace 2100c via the first gas transport pipe 2112a, the reducing gas supplied to the third reduction furnace 2100c is supplied to the second reduction furnace 2100b via the second gas transport pipe 2112b, and the reducing gas supplied to the second reduction furnace 2100b is supplied to the first reduction furnace 2100a via the third gas transport pipe 2112c. At this time, the gas supplied to the third reduction furnace 2100c, the second reduction furnace 2100b, and the first reduction furnace 2100a via the first to third gas transport pipes 2112a to 2112c may include not only the reducing gas supplied to the fourth reduction furnace 2100d, but also the gas generated during the reduction reaction in each reduction furnace.

[0060] Figure 2 shows a reduction furnace according to an embodiment of the present invention. Figure 3 is a cross-sectional view showing an enlarged portion of the reduction furnace.

[0061] As shown in Figures 1 and 2, each of the first to fourth reduction furnaces 2100a to 2100d may include a container 2110 capable of containing raw materials and having an internal space (reduction space) capable of reducing the raw materials, and a dispersion member 2120 disposed inside the container 2110, having a plurality of holes 2122 through which reducing gas can pass. It may also further include a cyclone 2140 disposed so as to be positioned at least partially inside the container 2110 to collect fine powder.

[0062] Furthermore, some of the first to fourth reduction furnaces 2100a to 2100d may be equipped with a burner 2130 that generates a flame. In this case, it is preferable that the burner 2130 is installed in the reduction furnace located at the central end of the first to fourth reduction furnaces 2100a to 2100d, that is, in a reduction furnace other than the first and fourth reduction furnaces 2100a and 2100d. For example, the burner 2130 may be installed in at least one of the second and third reduction furnaces 2100b and 2100c. Needless to say, all of the first to fourth reduction furnaces 2100a to 2100d may be equipped with a burner 2130. Also, at least one of the first and fourth reduction furnaces 2100a and 2100d located at both ends may be equipped with a burner 2130.

[0063] In the following explanation, we will use as an example, as shown in Figure 1, that the second and third reduction furnaces 2100b and 2100c, among the first to fourth reduction furnaces 2100a to 2100d, are equipped with burners 2130. Here, the second reduction furnace 2100b and the third reduction furnace 2100c have similar configurations, but the difference is that the second and third reduction furnaces 2100b and 2100c are further equipped with burners 2130 compared to the first and fourth reduction furnaces 2100a to 2100d.

[0064] Therefore, following the description of the reduction furnaces, we will use the second reduction furnace 2100b, which is one of the reduction furnaces equipped with a burner, as an example, referring to Figures 2 and 3. The descriptions of the first reduction furnace 2100a and the third and fourth reduction furnaces 2100c and 2100d will be omitted. The second reduction furnace 2100b, which will be described later, will sometimes be simply referred to as "reduction furnace 2100b".

[0065] As shown in Figures 2 and 3, the reduction furnace 2100b may include a container 2110 that can accommodate raw materials and has an internal space (reduction space) capable of reducing the raw materials, a dispersion member 2120 disposed inside the container 2110 and having a plurality of holes 2122 through which reducing gas can pass, and a burner 2130 disposed inside the container 2110 so as to be positioned above the dispersion member 2120 and generating a flame inside the container 2110. The reduction furnace 2100b may further include a cyclone 2140 disposed so as to be positioned at least partially inside the container 2110 to collect fine powder.

[0066] The dispersion member 2120 comprises a plate-shaped body 2121 having a predetermined area and a plurality of holes 2122 provided in the body 2121 to allow gas to pass through. For example, the dispersion member 2120 may be a plate-shaped perforated plate. Such a dispersion member 2120 is disposed inside the container 2110, but is disposed so as to partition the internal space of the container 2110 in the vertical direction. In this case, it is preferable that the dispersion member 2120 is disposed closer to the lower wall of the container 2110 than to the upper wall. For this reason, the internal space of the container 2110 may be partitioned into a space below the dispersion member 2120 and a space above the dispersion member 2120.

[0067] Furthermore, a gas transport pipe 2112b may be connected to the bottom of the container 2110 so as to communicate with the space below the dispersion member 2120, and a raw material transport pipe 2111a may be connected so as to communicate with the space above the dispersion member 2120. In this way, reducing gas is supplied to the space below the dispersion member 2120 within the internal space of the container 2110, and raw materials are supplied to the space above the dispersion member 2120. At this time, the raw materials supplied to the inside of the container 2110 are piled up on top of the dispersion member 2120. The reducing gas supplied to the space below the dispersion member 2120 moves to the upper side of the dispersion member 2120 by passing through the multiple holes 2122 of the dispersion member 2120, or is blown onto it. The raw materials on the upper side of the dispersion member 2120 then flow due to the reducing gas blown onto the upper side of the dispersion member 2120. In other words, the rising flow of reducing gas passing through the multiple holes 2122 in the dispersion member 2120 causes the raw material particles on the upper side of the dispersion member 2120 to flow. The raw material then reacts with the reducing gas and is reduced while flowing on the upper side of the dispersion member 2120.

[0068] In the reduction furnace 2100b, a reduction reaction occurs between the raw material containing iron ore and at least one of the hydrogen gas supplied from the hydrogen gas supply unit 2200 and the exhaust gas discharged from the dissolution device 3000 and supplied from the exhaust gas supply line 4000. At this time, the reaction between the iron ore and the hydrogen gas, and the reaction between the iron ore and the carbon monoxide (CO) contained in the exhaust gas are endothermic reactions. Therefore, the temperature inside the reduction furnace 2100b may drop due to the endothermic reaction, which will reduce the reduction rate of the raw material. For this reason, in order for a smooth reduction reaction, it is necessary to adjust the temperature inside the reduction furnace 2100b to a predetermined temperature or higher. Accordingly, a burner 2130 is placed in the container 2110 to generate a flame F and heat the inside of the container 2110. The burner 2130 may also be a means of generating a flame F by blowing an oxidizing agent containing oxygen (O) into the inside of the container 2110 and causing a combustion reaction. The specific structure and shape of the burner 2130 will be described again later.

[0069] On the other hand, the shorter the distance between the burner 2130 and the dispersion member 2120, the higher the temperature of the dispersion member 2120. This is because the shorter the distance between the burner 2130 and the dispersion member 2120, the shorter the distance between the flame F emitted from the burner 2130 and the dispersion member 2120. In such a case, the raw material particles may melt due to the high heat of the dispersion member 2120 and become entangled with each other, which may cause the pores 2122 of the dispersion member 2120 to become clogged. If the pores 2122 become clogged, the reducing gas cannot pass through, resulting in a problem where the flow of the raw material on the upper side of the dispersion member 2120 is not smooth. And if the flow of the raw material is not smooth, the reduction rate of the raw material decreases.

[0070] Therefore, the separation distance between the distribution member 2120 and the burner 2130 is optimized. In other words, the burner 2130 is positioned at the optimized height. At this time, the burner 2130 is positioned above the distribution member 2120. For this reason, the separation distance between the distribution member 2120 and the burner 2130 is defined as the "height of the burner 2130" or the "installation height of the burner 2130".

[0071] When installing the burner 2130 in the container 2110, the height at which it should be installed is determined first, and the burner 2130 is installed at the determined height. At this time, the height at which the burner 2130 should be installed (hereinafter referred to as installation height H) b ) may be determined according to the flow rate of reducing gas to be supplied to the reducing furnace 2100b. More specifically, the installation height H of the burner 2130 b The diameter (d) of the hole 2122 in the dispersion member 2120 or ) and the flow rate of the reducing gas to be supplied to the reducing furnace 2100b may be determined according to the flow rate of the reducing gas, which is determined by the flow velocity (m / sec) of the reducing gas to be supplied to the reducing furnace 2100b.

[0072] Below is the burner placement height H b Let's explain in more detail how to make that decision.

[0073] The height at which the burner 2130 should be installed is Hb In determining this, the flow rate of the reducing gas to be supplied to the reduction furnace 2100b is used to determine the depth to which the reducing gas penetrates the raw material layer above the dispersion member 2120. j The calculated infiltration depth l is then calculated. j The height H at which the burner 2130 should be installed is determined using this method. b To decide.

[0074] First, the depth to which the reducing gas penetrates the raw material layer will be explained based on Figures 2 and 3. As shown in Figure 3, the raw material containing iron ore is supplied into the container 2110 of the reduction furnace 2100b and stacked on top of the dispersion member 2120. Therefore, the raw material accumulates to a predetermined thickness on top of the dispersion member 2120, and hereafter, the layer formed by the accumulation of raw material to a predetermined thickness on top of the dispersion member 2120 will be referred to as the "raw material layer." Furthermore, since the raw material on top of the dispersion member 2120 flows in the reducing gas blown from below, the raw material layer may also refer to a fluidized bed.

[0075] The reducing gas supplied to the lower side of the dispersion member 2120 passes through multiple holes 2122 in the dispersion member 2120 and is blown onto the upper side where the raw material layer is located. Therefore, the reducing gas penetrates into the raw material layer above the dispersion member 2120. At this time, the reducing gas is blown up to a predetermined distance from the upper surface of the dispersion member 2120. That is, the reducing gas penetrates into the raw material layer above the dispersion member 2120, but to a predetermined depth. Here, the penetration depth of the reducing gas is l j This is based on the upper surface of the distributed member 2120.

[0076] The depth to which the reducing gas penetrates the raw material layer j To derive or predict this, first, the flow rate of reducing gas to be supplied to the reducing furnace 2100b, i.e., the container 2110, is determined. In other words, the target flow rate of reducing gas to be supplied to the container is determined. Here, the target flow rate of reducing gas may be determined by at least one of the following: the amount of raw material to be supplied to the reducing furnace 2100b, the volume of the container 2110 of the reducing furnace 2100b, and the target reduction rate.

[0077] The flow rate of reducing gas to be supplied to the reduction furnace 2100b will vary depending on at least one of the diameter of the holes 2122 in the dispersion member 2120 and the flow velocity of the reducing gas to be supplied to the reduction furnace. For example, when reducing gas is supplied at a predetermined target flow rate, the flow velocity of the reducing gas (u or The higher the ) the larger the diameter (d or ) reduces the diameter and the flow velocity of the reducing gas (u or The lower the ) the smaller the hole diameter (d or The flow rate of the reducing gas may be adjusted by increasing the diameter of the )

[0078] Therefore, once the flow rate of the reducing gas to be supplied to the reducing furnace 2100b is determined, the flow rate of the reduced gas and the diameter of the holes provided in the dispersion member 2120 (d or Using ), the flow rate (u) of the reducing gas to be supplied to container 2110 is determined. or ) will be decided.

[0079] Reduced gas flow velocity (u or Once the depth l of the reducing gas is determined, this is used to determine the depth to which the reducing gas penetrates the raw material layer. j To predict, more specifically, the depth to which the reducing gas penetrates the raw material layer. j This may vary depending on the flow rate of the reducing gas to be supplied to container 2110. That is, the penetration depth l of the reducing gas j The diameter (d) of the hole 2122 in the dispersion member 2120 or ) and the flow rate (u or ) may be determined according to the following: More specifically, the penetration depth l of the reducing gas j The diameter (d) of the hole 2122 in the dispersion member 2120 or ) and the flow velocity of the reducing gas (u or In addition to the density of the reducing gas (ρ g ), dynamic viscosity of the reducing gas (μ), particle density of the raw material (ρ) s ) and particle diameter of the raw material (d p ) may be determined by

[0080] More specifically, the diameter (d) of the hole 2122 in the dispersion member 2120 or ), reducing gas flow rate (u or ), density of reducing gas (ρ g ), dynamic viscosity of the reducing gas (μ), particle density of the raw material (ρ) s ) and particle diameter of the raw material (d p By applying ) to the following formula 1 and performing the calculation, the depth l to which the reducing gas penetrates the raw material layer can be determined. j You may calculate this.

[0081]

number

[0082] l j Penetration depth (m) d or : Diameter of the dispersion member pores (mm) u or : Flow velocity of reducing gas m / sec g:Gravity acceleration ρ g Density of reducing gas (kg / m³) 3 ) ρ s : Particle density of raw materials (kg / m³) 3 ) d p : Particle diameter of raw material (mm) μ: Dynamic viscosity of the reducing gas (N·sec / m³) 2 )

[0083] Here, the density of the reducing gas (ρ g The density (ρ) of the reducing gas and the dynamic viscosity (μ) of the reducing gas are determined according to the reducing gas used and are known values. That is, since at least one of the hydrogen gas from the hydrogen gas supply unit 2200 and the exhaust gas from the dissolution device 3000 is used as the reducing gas supplied to the reduction furnace 2100b, the density (ρ) of these gases g ) and dynamic viscosity (μ) are applied.

[0084] Also, the particle density of the raw material (ρ s ) and particle diameter of the raw material (dp The particle density (ρ) is determined according to the raw materials supplied to the reduction furnace 2100b for the production of reduced iron, and is a known value. That is, the particle density (ρ) is a physical property of the raw materials to be supplied to the reduction furnace 2100b. s ) and particle diameter (d p Understand and apply the appropriate methods.

[0085] By this method, the penetration depth of the reducing gas is j Calculating this, in other words, is the depth l to which the reducing gas supplied to the reducing furnace 2100b during the reduced iron production process penetrates the raw material layer. j It is also acceptable to make predictions.

[0086] Using Equation 1, the depth l to which the reducing gas penetrates the raw material layer. j Once calculated, the calculated infiltration depth l j The height H at which the burner 2130 should be installed is determined using this method. b Determine the placement height H. b The calculated infiltration depth l j Furthermore, the height H of the raw material layer m The following is determined (see relation 1). Here, the height H of the raw material layer m This could be the distance from the upper surface of the dispersion member 2120 to the upper surface of the raw material layer. And the height H of such a raw material layer m This is the height H of the upper surface of the raw material layer before reducing gas is supplied to the reduction furnace 2100b and before the raw materials begin to flow. m That's fine.

[0087] [Relationship 1] l j ≤H b ≤H m Relational equation 1

[0088] Below is the installation height H of the burner 2130. b Let's explain the method for determining the calculated infiltration depth l with a more specific example. j Assuming that the height is 580 mm and the height of the raw material layer when raw materials are supplied to the reduction furnace is 650 mm, the installation height H of the burner 2130b may be determined within the range of 580 mm to 650 mm (580 mm or more and 650 mm or less). For example, the installation height H of the burner b may be determined to be 600 mm.

[0089] When determining the installation height H of the burner 2130 b in order to be within the range of the calculated penetration depth l j or more and the height H of the raw material layer m or less, the range of "penetration depth l j or more and the height H of the raw material layer m or less" is sometimes referred to as the "installation height condition".

[0090] Once the installation height H b is determined, the burner 2130 is installed at the determined installation height H b That is, the burner 2130 is installed so that the separation distance from the dispersion member 2120 is the determined installation height H b In other words, the burner 2130 is installed above the dispersion member 2120, but is installed so that the separation distance from the upper surface of the dispersion member 2120 is the value of the determined installation height H b At this time, it is preferable to install the burner 2130 so that the separation distance between the center in the diameter direction of the burner 2130 and the upper surface of the dispersion member 2120 is the value of the determined installation height H b

[0091] On the other hand, if the installation height H of the burner 2130 b is too low and the separation distance between the burner 2130 and the dispersion member 2120 is too short, the flow of the raw material may not be smooth and may stagnate. That is, there is a risk of forming a stagnant layer, and there is concern that the stagnant layer may be thickly formed. This is because the shorter the separation distance between the burner 2130 and the dispersion member 2120, the shorter the distance between the flame F emitted from the burner 2130 and the dispersion member 2120. Conversely, the installation height H of the burner 2130 bIf the temperature is too high and the distance between the burner 2130 and the dispersion member 2120 is too long, the reduction reaction of the raw materials may not proceed smoothly. In other words, if the raw materials are located close to the dispersion member 2120, the temperature may be too low for the reaction with the reducing gas to occur, or it may not occur sufficiently. To put it another way, if the temperature of the raw material particles flowing above the dispersion member 2120, i.e., the fluidized bed, is too low, the reduction reaction may not occur sufficiently.

[0092] However, in this embodiment, the installation height H is determined by the method described above. b Determine the determined placement height H b A burner 2130 is installed. This allows the raw materials to flow smoothly without stagnation, while also enabling a sufficient reduction reaction. In other words, the heat from the flame F generated by the burner 2130 prevents the dispersion member 2120 from being heated to a high temperature, thereby preventing the raw material particles from melting and becoming entangled or agglomerated near the dispersion member 2120. This prevents the raw material particles from not flowing above the dispersion member 2120, or from stagnating with reduced flow, due to the heat of the dispersion member 2120. In other words, it prevents the formation of a congested layer where raw material particles do not flow or accumulate with suppressed flow. In addition, sufficient heat can be applied to the raw materials and reducing gas to ensure that the reduction reaction proceeds smoothly.

[0093] Therefore, the installation height H of the burner 2130 determined by the method according to the embodiment b This height can be explained as being sufficient to reduce the raw materials while suppressing or preventing the formation of congestion layers.

[0094] Figure 4 is a front cross-sectional view of the burner of the present invention. Figure 5 is a plan view of the burner of the present invention. Figure 6 is a diagram illustrating the flow of the oxidizing agent sprayed from the burner according to an embodiment of the present invention.

[0095] The burner 2130 comprises a main body 2131 extending in one direction, and a plurality of nozzles 2132a, 2132b, each extending in the direction of the main body 2131 and disposed inside the main body 2131.

[0096] The main body 2131 may be provided in a circular or cylindrical shape, as shown in Figure 5. Needless to say, the shape of the main body 2131 is not limited to this, and it may be provided in any shape as long as at least a part of it can be fitted into the container 2110 and multiple nozzles 2132a, 2132b can be arranged inside.

[0097] As mentioned above, the nozzles 2132a and 2132b are provided in multiple units, for example, two nozzles (first and second nozzles 2132a and 2132b) may be provided. Each of the first and second nozzles 2132a and 2132b extends in the extending direction of the main body 2131 and has an internal space through which the oxidizing agent can pass. In each of the first and second nozzles 2132a and 2132b, one end and the other end, which are the ends in the extending direction, are open. The inner diameter of each of the first nozzle 2132a and the second nozzle 2132b may be, for example, 15 mm to 20 mm, and more specifically, 16 mm to 19 mm. Needless to say, the inner diameters of the first and second nozzles 2132a and 2132b can be varied in various ways.

[0098] One end of each of the first and second nozzles 2132a and 2132b is an opening (hereinafter referred to as a spray port) from which the oxidizing agent is discharged or sprayed out. The other end of each of the first and second nozzles 2132a and 2132b is an opening (hereinafter referred to as an inlet) from which the oxidizing agent flows into the interior. Here, an oxidizing agent supply unit (not shown) may be connected to the other end of each of the first and second nozzles 2132a and 2132b. The oxidizing agent supply unit may include a reservoir in which the oxidizing agent is stored, a supply pipe connected to the first and second nozzles 2132a and 2132b to supply the oxidizing agent, and a regulator disposed in the supply pipe that can adjust at least one of the supply flow rate and flow velocity of the oxidizing agent.

[0099] The oxidizing agent may contain oxygen (O), and the oxygen (O) content in the total amount of the oxidizing agent may be 50 wt% or more and less than 100 wt%. Furthermore, the oxidizing agent may contain non-oxidizing substances in addition to oxygen (O), and the content of non-oxidizing substances in the total amount of the oxidizing agent may be greater than 0 wt% and less than 50 wt%. Furthermore, the non-oxidizing substance may contain nitrogen (N2). In other words, the oxidizing agent may contain oxygen (O) and nitrogen (N2), and the oxygen (O) content in the total amount of the oxidizing agent may be 50 wt% or more and less than 100 wt%, and the nitrogen (N2) content may be greater than 0 wt% and 50 wt% or less.

[0100] Thus, preparing the oxidizing agent to consist not of 100% oxygen (O) but also include non-oxidizing substances in addition to oxygen (O) is intended to lower the temperature of the flame produced when the oxidizing agent is burned inside the reduction furnace 2100b. In other words, if the oxidizing agent consists of 100% oxygen (O), there is a risk that the temperature of the flame formed inside the reduction furnace 2100b by the combustion reaction of the oxidizing agent will be too high, leading to the formation of a congested layer, and there is concern that a thick congested layer may form.

[0101] Furthermore, when spraying the oxidizing agent from the first nozzle 2132a and the second nozzle 2132b, it is preferable to adjust the flow velocity to 80 m / sec to 100 m / sec.

[0102] The first nozzle 2132a and the second nozzle 2132b are arranged to intersect each other, rather than being parallel. In this case, the first and second nozzles 2132a and 2132b may be arranged so that they approach the diametrical center of the main body 2131 as one moves from one end to the other. In other words, the first nozzle 2132a and the second nozzle 2132b may be arranged so that the distance between them gradually decreases as one moves from the other end to the other.

[0103] To put it another way, the first and second nozzles 2132a and 2132b may be provided so as to be inclined or tilted. To explain this more specifically, let us call a hypothetical line L that connects the diametrical center of one end of the main body 2131 to the diametrical center of the other end. c This is defined as "the extension line L of the first nozzle". Then, the imaginary line connecting one end and the other end of the first nozzle 2132a is defined as "the extension line L of the first nozzle". n1 The second nozzle extension line L is defined as "the second nozzle extension line L" and the imaginary line connecting one end and the other end of the second nozzle 2132b is defined as "the second nozzle extension line L" n2 It is defined as ". When providing the first and second nozzles 2132a and 2132b respectively, the extension lines L of the first and second nozzles n1 , L n2 The reference line L c They are positioned so as to intersect, rather than parallel, the first and second nozzles 2132a and 2132b, respectively, along the extension lines L of the first and second nozzles. n1 , L n2 The reference line L c The nozzles are positioned such that the angle between them, θ1 and θ2, is acute. More specifically, the first and second nozzles 2132a and 2132b are positioned along the extension lines L of the first and second nozzles. n1 , L n2 The reference line L c The nozzles are positioned such that the angle between them, θ1 and θ2, is between 20° and 45°. The first nozzle 2132a and the second nozzle 2132b are positioned along the reference line L c They may be provided so as to be symmetrical with respect to a reference point.

[0104] Thus, the first and second nozzles 2132a and 2132b are each connected to the reference line L c Because they are positioned to intersect rather than be parallel to the reference line L, the first and second nozzles 2132a and 2132b are aligned with the reference line L. c It can be explained that they are positioned to be inclined relative to the first nozzle 2132a. Furthermore, the first nozzle 2132a and the second nozzle 2132b are not parallel to each other, but intersect. For this reason, it can be explained that the first nozzle 2132a is positioned to be inclined relative to the second nozzle 2132b, and the second nozzle 2132b is positioned to be inclined relative to the first nozzle 2132a.

[0105] The first and second nozzles 2132a and 2132b are positioned so as they move toward one end of the main body, their separation distance from each other decreases, in order to cause the oxidizing agents sprayed from the first and second nozzles 2132a and 2132b to collide and diffuse. Referring to Figure 6, the oxidizing agents OM1 and OM2 discharged from the respective nozzles of the first and second nozzles 2132a and 2132b are sprayed in front of the nozzles. At this time, the oxidizing agents OM1 and OM2 discharged from the respective nozzles of the first and second nozzles 2132a and 2132b move in such a way that as they move away from the nozzles, they have a flow that approaches the diametrical center of the burner 2130. As a result, at a predetermined distance forward from one end of the burner 2130, the oxidizing agent sprayed from the first nozzle 2132a and the oxidizing agent sprayed from the second nozzle 2132b collide. Thus, after the oxidizing agent sprayed from the first and second nozzles 2132a and 2132b collide, the oxidizing agent diffuses widely.

[0106] The oxidizing agent sprayed from the first and second nozzles is sprayed in the shape of a stream with a predetermined width. For this reason, the flow of the oxidizing agent sprayed from the first and second nozzles with a predetermined width is defined as the "oxidizing agent stream". Reflecting this, the collision is explained again by the oxidizing agent stream emitted from the first nozzle 2132a and the oxidizing agent stream emitted from the second nozzle 2132b collide in front of the burner. After the collision of the multiple oxidizing agent streams, the oxidizing agent streams diffuse, as shown in Figure 6. That is, the multiple oxidizing agent streams collide and merge to form a single stream, which then diffuses widely. Therefore, the width of the oxidizing agent streams increases after the collision.

[0107] When the oxidizing agent is sprayed from the burner 2130 into the container 2110, a combustion reaction occurs between the oxidizing agent and the gas inside the container 2110, generating a flame. Specifically, at least one of the reducing gases supplied to the container 2110 (CO, H2, CH4) burns with the oxygen (O) in the oxidizing agent, generating a flame. The heat from the flame then heats the inside of the container 2110.

[0108] Flame F width W F This may vary depending on the width of the oxidizer stream sprayed from nozzles 2132a and 2132b. In other words, the narrower the width of the oxidizer stream, the wider the flame F W will be. F The narrower the oxidizer stream, the wider the flame width W. F The width is wide. Also, when the oxidizing agent is sprayed at the same flow rate, the width W of the flame F is wide. F The narrower the flame width W, the higher the flame temperature. F The wider the flame, the lower its temperature. This is because the width W of the flame F is... F The narrower the flame F, the greater the amount of oxidizing agent contained within it, and therefore, the combustion reaction occurs within a narrow range, causing heat to concentrate. In contrast, the width W of the flame F FThe wider the area, the less oxidizing agent is contained within the flame F, and the combustion reaction occurs over a wide area, causing the heat to diffuse widely without concentration, resulting in a lower flame temperature.

[0109] Here, the temperature of the flame F is defined as the predetermined width W. F The temperature of a flame F can sometimes refer to the highest temperature in that flame. The highest temperature in a flame F is at its center in the width direction. Therefore, the temperature of a flame F represents the temperature at its center in the width direction. Also, a low temperature of a flame F means that the highest temperature at its center in the width direction is relatively low, and a high temperature of a flame F means that the highest temperature at its center in the width direction is relatively high.

[0110] Therefore, in this embodiment, in order to form a flame at a lower temperature than in the conventional, a burner capable of forming a flame with a wider width than in the conventional is provided. That is, a porous burner 2130 is provided that can widely diffuse the sprayed oxidizer by causing it to collide with other elements. In other words, as described above, a plurality of nozzles 2132a and 2132b from which oxidizer can be sprayed are provided, and each nozzle 2132a and 2132b is inclined so that as it moves toward one end of the main body 2131, it approaches the diametrical center of the main body 2131. As a result, the oxidizer streams sprayed from each of the plurality of nozzles 2132a and 2132b collide with each other, thereby widely diffusing the oxidizer stream. Therefore, a combustion reaction occurs in the wide oxidizer stream, making it possible to form a wide flame. And as a result, the flame temperature can be lowered compared to the conventional. In other words, the flame temperature emitted from a multi-hole burner 2130 having multiple nozzles 2132a, 2132b, as in the embodiment, is even lower than the flame emitted from a conventional single-hole burner having one nozzle.

[0111] Furthermore, if the burner 2130 is positioned at the same height, the higher the temperature of the flame F emitted from the burner 2130, the higher the temperature of the dispersion member 2120, making it easier for a congestion layer to form, and potentially increasing the thickness of the congestion layer. Conversely, the lower the temperature of the flame F emitted from the burner 2130, the lower the temperature of the dispersion member 2120, making it difficult for a congestion layer to form, and even if a congestion layer is formed, its thickness will be thin. For this reason, by using a burner 2130 as in the embodiment to generate a low-temperature flame, it is possible to suppress or prevent the formation of a congestion layer on the upper side of the dispersion member 2120. This allows the raw material on the upper side of the dispersion member 2120 to flow smoothly due to the reducing gas, thereby improving the reduction rate of the raw material. In other words, it becomes possible for the raw material charged into the reduction furnace 2100b to be sufficiently reduced.

[0112] The above describes a burner 2130 equipped with two nozzles 2132a and 2132b. However, the present invention is not limited in any way, and the nozzles may be provided in a wide variety of numbers greater than two.

[0113] On the other hand, the first nozzle 2132a and the second nozzle 2132b each have a reference line L c If the angles θ1 and θ2 formed by the nozzles are less than 20° or greater than 45°, collisions between the oxidizer streams may not occur, or the amount of collisions may be insufficient. In other words, if the inclination angles θ1 and θ2 of at least one of the first nozzle 2132a and the second nozzle 2132b are less than 20° or greater than 45°, the oxidizer stream sprayed from the first nozzle 2132a and the oxidizer stream sprayed from the second nozzle 2132b may not collide, or the amount of collisions may be reduced. In such cases, a narrow flame F may be formed due to insufficient diffusion of the oxidizer stream, which may cause the temperature of the flame F to rise. Therefore, the angles θ1 and θ2 of the first and second nozzles 2132a and 2132b should be adjusted to 20° to 45°.

[0114] Then, by adjusting the angles θ1 and θ2 of the first and second nozzles 2132a and 2132b to 20° and 45°, the oxidizing agent streams sprayed from the first and second nozzles 2132a and 2132b are formed to be inclined. That is, the oxidizing agent streams sprayed from the first and second nozzles 2132a and 2132b are formed to be inclined so that they move away from one end of the main body 2131 and approach the center of the diameter of the main body 2131.

[0115] When spraying the oxidizing agent from the first nozzle 2132a and the second nozzle 2132b, the flow velocity of the oxidizing agent sprayed from each nozzle 2132a and 2132b is adjusted to 80 m / s to 100 m / s. By adjusting the flow velocity of the oxidizing agent sprayed from the first and second nozzles 2132a and 2132b to 80 m / s to 100 m / s in this way, the oxidizing agent streams sprayed from the first and second nozzles 2132a and 2132b can be made to collide with each other and diffuse.

[0116] On the other hand, if the flow velocity of the oxidizer sprayed from at least one of the first and second nozzles 2132a and 2132b is less than 80 m / s, there is a risk that the oxidizer stream sprayed from the first nozzle 2132a and the oxidizer stream sprayed from the second nozzle 2132b will not collide, or the amount of collision will be reduced. Also, if the flow velocity of the oxidizer sprayed from at least one of the first and second nozzles 2132a and 2132b exceeds 100 m / s, there is a risk that the flame temperature will be too high, promoting the formation of a congestion layer. Therefore, it is preferable to adjust the flow velocity of the oxidizer sprayed from the first and second nozzles 2132a and 2132b to between 80 m / s and 100 m / s.

[0117] Figure 7 is a schematic diagram of the experimental reduction furnace. Figure 8 shows the results of measuring the horizontal temperature at a predetermined height in the experimental reduction furnace. Figure 9 shows the results of measuring the temperature in the region from the dispersion member upwards to a predetermined height in the experimental reduction furnace.

[0118] Here, Figures 8(a) and 9(a) show the experimental results when a single-nozzle burner (single-hole burner) was installed in the experimental reduction furnace to generate a flame. Then, Figures 8(b) and 9(b) show the experimental results when a burner according to the embodiment, i.e., a multi-nozzle burner (multi-hole burner), was installed in the experimental reduction furnace to generate a flame.

[0119] First, the experimental reduction furnace will be described with reference to Figure 7. The experimental reduction furnace shown in Figure 7 is similar in configuration to the actual reduction furnace shown in Figure 2. Specifically, the experimental reduction furnace comprises a container 21, a dispersion member 22 having multiple holes through which reducing gas can pass, and a burner that generates a flame.

[0120] In the experiments to obtain the results shown in Figures 8 and 9, a first type of burner equipped with one nozzle was placed in the container, and then an experiment was conducted with a second type of burner placed in the container. When conducting the experiments with each type of burner, the first type of burner and the second type of burner were placed at the same height. For this reason, the same drawing reference numeral "23a" is used to describe both the first type of burner and the second type of burner.

[0121] First, we will describe the experiment using the first type of burner 23a. The first type of burner 23a is placed in the container. At this time, the placement height H of the burner 23a b1 The first type burner 23a was positioned 350 mm above the dispersion member 22. Then, an oxidizing agent was supplied to the first type burner 23a, and a reducing gas was supplied to the inside of the container 21 to generate a flame inside the container 21. Hydrogen gas was used as the reducing gas at this time. Next, the temperature inside the container 21 was measured. At this time, the height H of the first type burner 23a was measured. b1The temperature was measured horizontally at (350 mm), and the results are shown in Figure 8(a). In addition, the temperature of a predetermined area above the dispersion member 22 was measured, and the results are shown in Figure 9(a).

[0122] Next, the experiment was conducted using a second type of burner 23a. At this time, the installation height H of the second type of burner 23a was... b1 The height H of the first type burner 23a described above. b1 Similarly, the height was set to 350 mm. Then, an oxidizing agent was supplied to the second type of burner 23a, and hydrogen gas, which is a reducing gas, was supplied to the inside of the container 21 to generate a flame inside the container 21. At this time, the flow rates of the supplied oxidizing agent and reducing gas were the same as in the experiment using the first type of burner 23a. Next, the height H in which the second type of burner 23a is installed b1 The temperature was measured horizontally at (350 mm), and the results are shown in Figure 8(b). In addition, the temperature of a predetermined area above the dispersion member 2120 was measured, and the results are shown in Figure 9(b).

[0123] Comparing Figures 8(a) and 8(b), we can see the width W of the flame produced by the first type of burner 23a at the same location. F1 In contrast, the width W of the flame produced by the second type of burner 23a F2 The latter is even wider. To explain more specifically, if we compare the flame widths at a position corresponding to a first horizontal distance D1 from the first and second type burners 23a, the flame width W produced by the first type burner 23a is... F1 Compared to (Figure 8(a)), the flame width W produced by the second type of burner 23a F2 (Figure 8(b)) is even wider. From this, it can be seen that when using the burner 2130 according to the embodiment, the width of the flame can be widened.

[0124] Comparing Figures 9(a) and 9(b), the temperature of the dispersion member 22 is even lower in Figure 9(b) than in Figure 9(a). More specifically, the temperature of the dispersion member 22 located at a distance corresponding to the second horizontal distance D2 from the first type of burner 23a is high, at approximately 1500°C. In contrast, the temperature of the dispersion member 22 located at a distance corresponding to the second horizontal distance D2 from the second type of burner 23a is low, at approximately 1100°C. From this, it can be seen that when using the burner 2130 according to the embodiment, the temperature of the dispersion member 2120 can be lowered.

[0125] Figure 10 shows the temperature distribution at different heights inside the experimental reduction furnace when a first type of burner, equipped with one nozzle, is placed inside the furnace to generate a flame, and Figure 11 shows the temperature distribution at different heights inside the furnace when a second type of burner, equipped with first and second nozzles, is placed inside the furnace to generate a flame. Here, the second type of burner may be the burner according to the embodiment.

[0126] First, referring to Figure 7, we will explain the experiment conducted to obtain the results shown in Figure 10.

[0127] For the experiment, two first-type burners were set up and arranged in the container 21 at different heights. The first-type burner positioned at a relatively lower height is referred to as the first burner 23a, and the first-type burner positioned at a relatively higher height than the first burner 23a is referred to as the second burner 23b. The first burner 23a is positioned at a height H 350 mm above the dispersion member 22. b1 The second burner 23b is positioned and installed at a height H 600 mm above the distribution member 2120. b2They were positioned and arranged at the following height H. Then, an oxidizing agent was supplied to the first and second burners 23a and 23b of the first type, respectively, and a reducing gas was supplied to the inside of the container 21 to generate a flame inside the container 21. Here, hydrogen gas was used as the reducing gas. Next, the temperature inside the container 21 was measured. At this time, the first burner 23a of the first type was positioned at height H. b1 The temperature was measured horizontally at a height of 350 mm, and the results are shown in Figure 10(a). The temperature was also measured horizontally at a height of 600 mm where the second burner 23b of the first type is installed, and the results are shown in Figure 10(b). Furthermore, the temperature was measured horizontally at a height 100 mm above the first and second burners 23a and 23b, and above the dispersion member 22, and the results are shown in Figure 10(c).

[0128] An experiment to obtain the results shown in Figure 11 was conducted in a similar manner. Specifically, two second-type burners were set up for the experiment and arranged in the container at different heights. The second-type burner positioned at a relatively lower height is referred to as the first burner 23a, and the second-type burner positioned at a relatively higher height than the first burner 23a is referred to as the second burner 23b. The first burner 23a of the second type was positioned at a height H 350 mm above the dispersion member 22. b1 The second burner 23b of the second type is positioned and installed at a height H 600 mm above the distribution member 22. b2 They were positioned and installed at [location]. Then, an oxidizing agent was supplied to the first and second burners 23a and 23b of the second type, and a reducing gas was supplied to the inside of the container 21 to generate a flame inside the container 21. Here, hydrogen gas was used as the reducing gas. Next, the first burner 23a of the second type was installed at height H b1 The temperature was measured horizontally at (350 mm), and the results are shown in Figure 11(a). Furthermore, the second burner 23b of the second type is installed at height H. b2The temperature was measured horizontally at (600 mm), and the results are shown in Figure 11(b). The horizontal temperature was then measured at a height 100 mm above the first and second burners 23a and 23b, and above the dispersion member 22, and the results are shown in Figure 11(c).

[0129] Referring to Figure 10(a), the temperature in the horizontal direction of the temperature distribution is as follows: The temperature in the first region A1, which is the area at the height where the first burner 23a of the first type is installed, is higher than the temperature in the second region A2, which is the area opposite to the second burner 23b of the first type below it. Conversely, referring to Figure 10(b), the temperature in the second region A2, which is the area at the height where the second burner 23b of the first type is installed, is higher than the temperature in the first region A1, which is the area opposite to the first burner 23a of the first type above it.

[0130] Furthermore, referring to Figure 11(a) regarding the horizontal temperature distribution, similarly, the temperature of the first region A1, which is the region at the height where the first burner 23a of the second type is installed, is even higher than the temperature of the second region A2, which is the region opposite to the second burner 23b of the second type above it. Conversely, referring to Figure 11(b), the temperature of the second region A2, which is the region at the height where the second burner 23b of the second type is installed, is even higher than the temperature of the first region A1, which is the region opposite to the first burner 23a of the second type above it.

[0131] From this, we can see that the closer you are to the burner, using the vertical direction as a reference, the higher the temperature.

[0132] Figures 10(c) and 11(c) show the results of measuring the horizontal temperature distribution at a height where the first and second burners 23a and 23b are not installed, and where the distance from the dispersion member 2120 is short. Specifically, it shows the horizontal temperature distribution below the first burner 23a, which is relatively lower in height than the first and second burners 23a and 23b, and at a height 100 mm above the dispersion member 22.

[0133] First, referring to Figure 10(c), the temperature of the first region A1 facing the first burner 23a of the first type at a height of 100 mm above the dispersion member 22 is high, at approximately 1723°C (2000K) or higher. In contrast, referring to Figure 11(c), the temperature of the first region A1 facing the first burner 23a of the second type at a height of 100 mm above the dispersion member 22 is even lower than the temperature of the first region A1 in Figure 10(c). That is, the temperature of the first region A1 in Figure 11(c) is low, at 1650°C or lower.

[0134] From this, it can be seen that when using a second type of burner equipped with multiple nozzles, and a second type of burner equipped to allow the oxidizing agent to collide with the nozzles, i.e., the burner according to the embodiment, the temperature of the dispersion member and its surroundings can be lowered. In other words, under the same temperature conditions at the same height, the temperature can be lowered when using the burner according to the embodiment compared to when using a first type of burner equipped with a single nozzle (conventional burner).

[0135] In the embodiment, as described above, the height H of the burner 2130 bThe arrangement is optimized. Specifically, the burner 2130 is positioned at an optimized distance from the dispersion member 2120. This prevents or suppresses the dispersion member 2120 from being heated to a high temperature by the heat of the flame F emitted from the burner 2130. Consequently, it prevents or suppresses the raw material particles from melting and becoming entangled or agglomerated near the dispersion member 2120. This prevents or suppresses the formation of a congestion layer on top of the dispersion member 2120, and therefore allows the raw materials to flow smoothly inside the reduction furnace. In addition, sufficient heat can be applied to the raw materials and reducing gas to ensure that the reduction reaction proceeds smoothly.

[0136] Furthermore, by using a burner 2130 equipped with multiple nozzles 2132a and 2132b, the temperature of the flame F can be lowered. Specifically, the burner 2130 according to this embodiment uses multiple nozzles 2132a and 2132b, which are arranged to be inclined to intersect each other, to spray the oxidizing agent, causing it to collide and diffuse. As a result, the width of the oxidizing agent stream sprayed in front of the burner 2130 can be widened, thereby forming a lower-temperature flame F. Consequently, it is possible to prevent the dispersion member 2120 and the raw materials from being heated to excessively high temperatures by the high-temperature flame. This suppresses the clumping of raw material particles due to melting, thereby inhibiting or preventing the formation of a congested layer. Consequently, the raw materials can flow smoothly inside the reduction furnace 2100b. [Industrial applicability]

[0137] According to the present invention, it is possible to suppress or prevent the dispersion material from being heated to a high temperature by the heat of the flame emitted from the burner. Furthermore, it is possible to generate a flame at a lower temperature than in the conventional method. As a result, it is possible to suppress or prevent aggregation due to the melting of raw material particles, thereby suppressing or preventing the formation of a congested layer. Consequently, the raw material can be allowed to flow smoothly inside the reduction furnace.

Claims

1. The height of the burner relative to the dispersion member placed inside the container of the reduction furnace (H ｂ The process of determining ) and The distance from the aforementioned dispersion member to the upper part is determined by the arrangement height (H ｂ The process of arranging the burner in the container so that ) The process of supplying raw materials containing iron ore to the upper side of the dispersion member, A process of passing a reducing gas through the holes of the dispersion member to cause the raw material located above the dispersion member to flow, The process of generating a flame inside the container using the aforementioned burner, A process of reducing the raw material by reacting the raw material with a reducing gas, Includes, The installation height (H) of the aforementioned burner ｂ Before the process of determining the target flow rate of the reducing gas, The determined target flow rate of the reducing gas and the diameter of the holes provided in the dispersion member (d ｏｒ Using ), the flow rate (u) of the reducing gas to be supplied to the container is determined. ｏｒ This includes the process of determining ) The installation height (H) of the aforementioned burner ｂ The process of deciding ) is The diameter (d ｏｒ ), and the flow rate (u ｏｒ ) of the reducing gas are used to predict the depth (l ｊ ) to which the reducing gas penetrates the raw material layer above the dispersion member, and the process of The installation height (H) of the aforementioned burner ｂ ) is the predicted penetration depth (l ｊ This includes a process of determining the value within a range that is greater than or equal to the height of the top of the raw material layer, A method for producing reduced iron, characterized in that the target flow rate of the reducing gas is determined by at least one of the amount of raw material to be supplied to the reducing furnace, the volume of the vessel of the reducing furnace, and the target reduction rate.

2. The depth to which the reducing gas penetrates the raw material layer (l ｊ The process of predicting the diameter of the hole (d ｏｒ ), reducing gas flow rate (u ｏｒ ), density of reducing gas (ρ ｇ ), density of raw material particles (ρ ｓ ), particle size of raw material particles (d ｐ ), the penetration depth of the reducing gas (l) is determined using the dynamic viscosity (μ) of the reducing gas. ｊ A method for producing reduced iron according to claim 1, characterized by including a step of calculating ).

3. The process of generating a flame inside the container using the aforementioned burner is as follows: The process of supplying an oxidizing agent to each of the multiple nozzles provided in the burner, The process of forming an oxidizing agent stream by spraying the oxidizing agent from each of the aforementioned multiple nozzles, A process of diffusing oxidizing agent streams by causing multiple oxidizing agent streams to collide with each other, The process involves reacting the aforementioned oxidizing agent stream with a reducing gas to generate a flame, A method for producing reduced iron according to claim 1, characterized by including the following:

4. The process of spraying the oxidizing agent from each of the aforementioned multiple nozzles is as follows: The method for producing reduced iron according to claim 3, characterized in that the oxidizing agent sprayed from each of the plurality of nozzles has a flow that is inclined so that it gradually approaches the center of the burner in the diametrical direction as it moves away from the burner.

5. The oxidizing agent is oxygen (O) and nitrogen (N ２ A method for producing reduced iron according to claim 3, characterized by including ).

6. The method for producing reduced iron according to claim 3, characterized by including a step of adjusting the flow rate of the oxidizing agent sprayed from each of the plurality of nozzles to 80 m / sec to 100 m / sec.

7. The reducing gas is hydrogen (H ２ A method for producing reduced iron according to any one of claims 1 to 6, characterized by including a gas.

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