Reduction furnace and 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 smooth the flow of raw materials and suppress or prevent clogging of holes in a dispersion member. [Background technology]

[0002] The blast furnace process requires various auxiliary facilities such as coke manufacturing facilities and sintered ore manufacturing facilities, etc. In addition, there is a problem that environmental pollution occurs due to substances discharged from the auxiliary facilities, and the cost of equipment to prevent environmental pollution rises.

[0003] Therefore, a method of producing molten iron directly using fine iron ore (fine iron ore), which accounts for more than 80% of the world's ore production, is used. Such molten iron production facilities include a fluidized bed reduction furnace that reduces the fine iron ore to produce reduced iron, and a melting device that melts the reduced iron from the fluidized bed reduction furnace to produce molten iron.

[0004] The fluidized-bed reduction reactor includes a vessel and a dispersion member having a plurality of holes through which a gas can pass. The dispersion member is disposed inside the vessel, a reducing gas is supplied to the lower side of the dispersion member, and fine iron ore is charged to the upper side of the dispersion member.

[0005] When the reducing gas is supplied to the lower side of the dispersion member, the reducing gas passes through a plurality of holes provided in the dispersion member and is sprayed to the upper side. The reducing gas sprayed to the upper side in this manner causes the fine iron ore above the dispersion member to flow. The fine iron ore reacts with the reducing gas while flowing, and is thereby reduced to produce reduced iron.

[0006] In order for the fine iron ore and the reducing gas to react smoothly inside the fluidized-bed reduction reactor, the inside of the fluidized-bed reduction reactor must be kept at a predetermined temperature or higher. However, since the reaction between the fine iron ore and the reducing gas is predominantly an endothermic reaction, there is a risk that the temperature inside the fluidized-bed reduction reactor will drop during the reduction reaction. To solve this problem, a burner is provided in the fluidized-bed reduction reactor to generate a flame and heat the fluidized-bed reduction reactor. In this case, the burner is provided above the dispersion member.

[0007] On the other hand, if the temperature of the flame emitted from the burner is too high, the fine iron ore particles may melt and become entangled with each other. If the fine iron ore particles become entangled and form agglomerates, the flow of the fine iron ore may not be smooth. This may result in a jam phenomenon in which the fine iron ore does not flow or only flows slightly.

[0008] In addition, if the flame temperature is too high or the distance between the burner and the dispersing member is short, the temperature of the dispersing member becomes high. In such a case, the fine iron ore particles melt and become entangled with each other due to the heat of the dispersing member, which causes the holes of the dispersing member to become clogged. If the holes of the dispersing member become clogged, the reducing gas cannot pass through, which causes the flow of the fine iron ore above the dispersing member to be hindered. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Korean Patent Publication No. 10-2007-0068210 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention 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 holes in a dispersion member.

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

[0013] In order to achieve the above object, a reducing furnace according to an embodiment of the present invention is characterized in that it comprises: a vessel having an internal space capable of accommodating a raw material containing iron ore and a reducing gas; a dispersion member having 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, and for generating a flame inside the vessel.

[0014] The height of the burner is adjusted according to the target flow rate of the reducing gas, and the diameter (d or ) and the flow rate of the reducing gas (u or ) may be used.

[0015] The height at which the burners are disposed is set to a depth l at which the reducing gas penetrates into the raw material layer made of the raw material supplied above the dispersion member. j It may be equal to or higher than 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 extension direction of the main body such that the distance between the nozzles gradually decreases as the nozzles approach one end of the main body.

[0017] The inclination angle of each of the plurality of nozzles may be 20° to 45°.

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

[0019] In order to achieve the above object, the method for producing reduced iron of the present invention is to use a target flow rate of a reducing gas to be supplied to a vessel of a reduction furnace, and to adjust the height H of a burner based on a dispersion member disposed inside the vessel. b and determining a distance above the dispersion member based on the determined installation height H b the steps of: disposing a burner in the vessel so that the raw material contains iron ore; supplying the raw material containing iron ore to the upper side of the dispersion member; passing a reducing gas through holes in the dispersion member to flow the raw material above the dispersion member; generating a flame inside the vessel using the burner; and reducing the raw material by reacting the raw material with the reducing gas.

[0020] In the method for producing reduced iron, the burner is disposed at a height H b Before the step of determining, a step of determining a target flow rate of the reducing gas, and a step of calculating a diameter (d or ) to determine the flow rate (u or ) determining

[0021] The burner installation height H b The step of determining the diameter (d or ) and the flow rate of the reducing gas (u or ) to determine the depth l of the reducing gas penetrating into the raw material layer above the dispersion member. j and a step of predicting the predicted penetration depth l j The burner installation height H b and determining

[0022] The depth l of the reduction gas permeating into the raw material layer j The process of predicting the diameter (d or ), the flow rate of the reducing gas (u or), the density of the reducing gas (ρ g ), density of raw material particles (ρ s ), the particle size of the raw material particles (d p ), and the dynamic viscosity of the reducing gas (μ) are used to calculate the penetration depth of the reducing gas (l j ) may be included in the method.

[0023] In the method for producing reduced iron, the burner is disposed at a height H b Let the predicted penetration depth l j The method may include a step of determining the range within which the height is equal to or greater than the height of the top of the raw material layer and is equal to or less than the height of the top of the raw material layer.

[0024] The process of generating a flame inside a container using the burner may include the steps of: supplying an oxidizer to each of a plurality of nozzles provided on the burner; spraying an oxidizer from each of the plurality of nozzles to form an oxidizer stream; colliding the plurality of oxidizer streams with each other to diffuse the oxidizer stream; and reacting the oxidizer stream with a reducing gas to generate a flame.

[0025] The step of spraying the oxidizer from each of the plurality of nozzles may include a step of spraying the oxidizer from each of the plurality of nozzles in such a manner that the oxidizer has an inclined flow that gradually approaches a diametric center of the burner as it moves away from the burner.

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

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

[0028] The reducing gas may include hydrogen (H2) gas. Effect of the Invention

[0029] According to the present invention, it is possible to suppress or prevent the dispersion member from being heated to a high temperature by the heat of the flame generated by the burner. Also, it is possible to generate a flame with a lower temperature than in the past. Therefore, it is possible to suppress or prevent the aggregation caused by melting of the raw material particles, and thus it is possible to suppress or prevent the formation of a congestion layer. Therefore, it is possible to smoothly flow the raw material inside the reducing furnace.

[0030] Furthermore, while suppressing or preventing the formation of a congestion layer, sufficient heat can be applied to the raw material and reducing gas to ensure that the reduction reaction occurs smoothly. [Brief description of the drawings]

[0031] [Figure 1] 1 is a diagram showing a schematic diagram of a molten iron manufacturing facility according to the present invention; [Diagram 2] FIG. 1 is a diagram showing a reduction furnace of the present invention. [Diagram 3] FIG. 2 is an enlarged cross-sectional view showing a part of the reduction furnace. [Figure 4] FIG. 2 is a front cross-sectional view of the burner of the present invention. [Diagram 5] FIG. 2 is a plan view of the burner of the present invention. [Figure 6] FIG. 2 is a diagram illustrating the flow of an oxidant sprayed from a burner according to the present invention. [Figure 7] FIG. 2 is a schematic diagram of an experimental reduction furnace. [Figure 8] The results are obtained by measuring the horizontal temperature at a given height in an experimental reduction furnace. [Figure 9] 13 shows the results of measuring the temperature in a region from the dispersion member to a predetermined height above in an experimental reduction furnace. [Figure 10] This shows the temperature distribution by height inside a vessel of an experimental reduction furnace when a first type of burner with one nozzle was installed in the vessel to generate a flame. [Figure 11]13 shows the temperature distribution by height inside a vessel of an experimental reduction furnace when a second type burner equipped with first and second nozzles was disposed in the vessel to generate a flame. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] The present invention will be described in more detail below with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. 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 describe the embodiments of the present invention, and the same numerals in the drawings indicate the same components.

[0033] FIG. 1 is a diagram that shows a schematic diagram of a molten iron manufacturing facility of the present invention.

[0034] 1 , the molten iron manufacturing facility of the present invention includes a reduced iron manufacturing apparatus 2000 having a reduction section 2100 capable of manufacturing reduced iron, and a melting apparatus 3000 capable of melting reduced iron. The molten iron manufacturing facility may also include a raw material supplying apparatus 1000 arranged to supply raw materials to the reduction section 2100, and an exhaust gas supplying line 4000 arranged to connect the melting apparatus 3000 and the reduction section 2100 so that exhaust gas discharged from the melting apparatus 3000 can be supplied to the reduction section 2100.

[0035] The molten iron manufacturing facility may further include a molding device (not shown) that molds the reduced iron in a powder state produced in the reduced iron manufacturing apparatus 2000.

[0036] The raw material supplying device 1000 is disposed so as to be able to supply the raw material to the reduction section 2100. Here, the raw material may include iron ore, and the iron ore may include fine iron ore having a particle size exceeding 0 mm and equal to or less than 0 mm, i.e., fine iron ore. The raw material supplying device 1000 may include, for example, a reservoir capable of storing the raw material. The raw material may be stored in the internal space of the reservoir for a long period of time, or the raw material may be temporarily stored before being supplied to the reduced iron manufacturing apparatus 2000. Such a reservoir may include, for example, a hopper.

[0037] The smelting apparatus 3000 receives the reduced iron supplied from the reduced iron manufacturing apparatus 2000 and melts the supplied reduced iron. At this time, the smelting apparatus 3000 may treat finely powdered reduced iron, or may treat reduced iron prepared by agglomerating the finely powdered reduced iron in a molding apparatus.

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

[0039] When the reduced iron is melted in the melting apparatus 3000, gas is generated, and the gas contains at least one of the combustible components CO (carbon monoxide) and CH4 (methane). The above-mentioned CO (carbon monoxide) and CH4 (methane) are components that can be reduced with iron ore. For this reason, the gas (hereinafter, exhaust gas) generated and discharged in the melting apparatus 3000 is recovered and supplied to a reduction section of the reduced iron manufacturing apparatus. Then, in the reduced iron manufacturing apparatus, the iron ore is reduced using the exhaust gas supplied from the melting apparatus 3000. At this time, the exhaust gas discharged from the melting apparatus 3000 may be supplied to the reduction section 2100 via an exhaust gas supply line 4000.

[0040] The melting apparatus 3000 has been described above as being equipped with an electric furnace. However, the present invention is not limited thereto, and the melting apparatus 3000 may be equipped with a melter-gasifier. A coal packed bed made of coal is formed inside the melter-gasifier. Reduced iron and auxiliary materials are charged into the melter-gasifier, and oxygen is blown in through a number of air ports provided on the outer wall. Therefore, the coal packed bed is burned by the blown in oxygen, and the reduced iron is melted to produce molten iron. Exhaust gas generated during the production of molten iron from the melter-gasifier may be supplied to the reduction section 2100 through the exhaust gas supply line 4000.

[0041] The reduced iron manufacturing apparatus 2000 includes a reduction unit 2100 that reduces iron ore to manufacture reduced iron. The reduced iron manufacturing apparatus 2000 may also include a hydrogen gas supply unit 2200 that supplies a reducing gas containing hydrogen to the reduction unit 2100.

[0042] First, the hydrogen gas supply unit 2200 will be described. The hydrogen gas supply unit 2200 supplies hydrogen gas, which is a reducing gas for reducing the raw material, i.e., iron ore, to the reduction unit 2100. Meanwhile, 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 be a means provided to process the by-products generated and discharged in the reduction unit 2100 to produce hydrogen gas, and to supply the 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 receive the by-products and extract hydrogen gas, a supply pipe 2230 arranged to connect the extractor 2220 and the reduction unit 2100 so as to supply the 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 to heat the hydrogen gas generated in the extractor 2220. The hydrogen gas supply unit 2200 may further include a dust collector 2250 arranged in 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 disposed in the exhaust pipe 2210 so as to be positioned between the extractor 2220 and the reduction section 2100. The dust collector 2250 may be, for example, a wet dust collector that collects dust by a wet method. Needless to say, the dust collector 2250 is not limited to the above-mentioned example, and a wide variety of means capable of collecting dust from by-products can be adopted.

[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. The extractor 2220 may be a means for 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 an adsorbent, but the extractor 2220 may use a carbon molecular sieve capable of adsorbing a hydrogen component as an adsorbent in order to extract hydrogen gas from the by-products containing various gases in addition to hydrogen gas. At this time, the hydrogen component adsorbed to the adsorbent can be desorbed and extracted as hydrogen gas, and the extractor 2220 may extract hydrogen gas from the by-products by repeatedly adsorbing and desorbing 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 iron ore in the reduction unit 2100. That is, 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 referred to as a "reducing gas" that reduces the iron ore.

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

[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. In addition, since hydrogen gas is generally very expensive, there is a problem in that it is costly to purchase hydrogen gas separately and supply it to the reduction unit 2100. However, in the embodiment, hydrogen gas is extracted from the by-product discharged from the reduction unit 2100 and is supplied again to the reduction unit 2100 to be used as the reducing gas. That is, the by-product generated in the reduction unit 2100 is reused. This makes it possible to reduce the cost of producing reduced iron.

[0049] In the above, it has been described that the hydrogen gas supply unit 2200 is provided to post-treat or reform the by-products discharged from the reduction unit 2100 to produce hydrogen gas and supply the hydrogen gas to the reduction unit 2100. However, the hydrogen gas supply unit 2200 may be provided to supply separately provided hydrogen gas to the reduction unit 2100 without reusing the by-products discharged from the reduction unit 2100. In this 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 an extension path of the supply pipe 2230 to heat the hydrogen gas.

[0050] In this way, the process of producing reduced iron by reducing iron ore using hydrogen gas and producing molten iron by melting the reduced iron may be a process called a "hydrogen reduction iron-making process". In the hydrogen reduction iron-making process, hydrogen gas is supplied to the reduction section 2100 to reduce the raw materials, and the hydrogen gas reacts with the iron ore to generate water or steam, but does not generate carbon dioxide. Therefore, when hydrogen gas is supplied to the reduction section 2100 to reduce the raw materials, there is an effect that carbon emissions can be reduced. That is, the hydrogen reduction iron-making process in which only hydrogen gas is supplied to the reduction section 2100 to reduce the raw materials, or a gas mixture of exhaust gas discharged from the melting device 3000 and hydrogen gas is supplied to the reduction section 2100 to reduce the raw materials, has an effect of reducing carbon emissions compared to the process in which only exhaust gas is used to reduce the raw materials.

[0051] Needless to say, the embodiment is applicable not only to a hydrogen reduction ironmaking process in which only hydrogen gas is supplied to the reduction section 2100, or a mixture of exhaust gas discharged from the melting apparatus 3000 and hydrogen gas is supplied to the reduction section 2100, but also to a general ironmaking process in which only exhaust gas discharged from the melting apparatus 3000 is supplied to the reduction section 2100.

[0052] The reduction unit 2100 reduces raw materials to produce reduced iron. That is, the reduction unit 2100 receives raw materials including iron ore from the raw material supply device 1000, and reacts the iron ore with a reducing gas to produce reduced iron. Here, the reducing gas supplied to the reduction unit 2100 may contain at least one of the hydrogen gas supplied from the hydrogen gas supply unit 2200 and the exhaust gas discharged from the melting device 3000.

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

[0054] The reduction unit 2100 may include a reduction furnace that produces reduced iron while flowing raw materials. A single reduction furnace may be provided, or multiple reduction furnaces may be provided to effectively reduce low-grade iron ore or fine iron ore having a low iron content. In this way, when multiple reduction furnaces are provided, the reduction unit 2100 may include multiple raw material transport pipes 2111a-2111c and multiple gas transport pipes 2112a-2112c that are arranged to connect the multiple reduction furnaces 2100a-2100d to each other.

[0055] As described above, a plurality of reduction furnaces 2100a-2100d may be provided. The plurality of reduction furnaces 2100a-2100d may be connected to each other so that the raw materials can be transferred sequentially as shown in FIG. 1. The number of the reduction furnaces 2100a-2100d is not particularly limited, but the reduction unit 2100 may be provided with four reduction furnaces (first to fourth reduction furnaces 2100a-2100d) in order to sufficiently reduce the raw materials. When the reduction unit 2100 includes four reduction furnaces 2100a-2100d, the reduction unit 2100 may include three raw material transport pipes 2111a-2111c and three gas transport pipes 2112a-2112c.

[0056] The first reduction furnace 2100a of the first to fourth reduction furnaces 2100a to 2100d may be connected to the raw material supplying device 1000 and the exhaust pipe 2210 of the hydrogen gas supplying unit 2200. That is, the raw material supplying device 1000 is disposed so as to be connected to the first reduction furnace 2100a, and therefore the raw material discharged from the raw material supplying device 1000 is charged into the first reduction furnace 2100a. Then, the exhaust pipe 2210 of the hydrogen gas supplying unit 2200 is connected to the first reduction furnace 2100a. Therefore, by-products discharged from the first reduction furnace 2100a are discharged through the exhaust pipe 2210.

[0057] At least one of the supply pipe 2230 of the hydrogen gas supply unit 2200 and the exhaust gas supply line 4000 is connected to the fourth reduction furnace 2100d of the first to fourth reduction furnaces 2100a to 2100d. 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 of the melting apparatus 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 provided to connect the first to fourth reduction furnaces 2100a to 2100d. That is, a first raw material transport pipe 2111a is provided between the first reduction furnace 2100a and the second reduction furnace 2100b, a second raw material transport pipe 2111b is provided between the second reduction furnace 2100b and the third reduction furnace 2100c, and a third raw material transport pipe 2111c is provided between the third reduction furnace 2100c and the fourth reduction furnace 2100d. Therefore, the raw materials supplied to the first reduction furnace 2100a and reduced primarily are supplied to the second reduction furnace 2100b via the first raw material transport pipe 2111a, the raw materials secondarily reduced in the second reduction furnace 2100b are supplied to the third reduction furnace 2100c via the second raw material transport pipe 2111b, and the raw materials tertiarily reduced in the third reduction furnace 2100c are supplied to the fourth reduction furnace 2100d via the third raw material transport pipe 2111c. Then, the raw materials fourthly reduced in the fourth reduction furnace 2100d, i.e., reduced iron, are supplied to the melting apparatus 3000.

[0059] Gas transport pipes 2112a to 2112c are provided to connect the first to fourth reduction furnaces 2100a to 2100d. That is, a first gas transport pipe 2112a is provided between the fourth reduction furnace 2100d and the third reduction furnace 2100c, a second gas transport pipe 2112b is provided between the third reduction furnace 2100c and the second reduction furnace 2100b, and a third raw material transport pipe 2111c is provided between the second reduction furnace 2100b and the first reduction furnace 2100a. Therefore, the reducing gas supplied to the fourth reduction furnace 2100d is transported to the second to fourth reduction furnaces 2100a to 2100d in sequence 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 carrier pipe 2112a, the reducing gas supplied to the third reduction furnace 2100c is supplied to the second reduction furnace 2100b via the second gas carrier 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 carrier 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 carrier pipes 2112a to 2112c may include not only the reducing gas supplied to the fourth reduction furnace 2100d, but also gas generated during the reduction reaction in each reduction furnace.

[0060] Fig. 2 is a diagram showing a reducing furnace according to an embodiment of the present invention, and Fig. 3 is an enlarged cross-sectional view showing a part of the reducing furnace.

[0061] 1 and 2, each of the first to fourth reduction furnaces 2100a to 2100d may include a container 2110 having an internal space (reduction space) capable of accommodating raw materials and reducing the raw materials, and a dispersion member 2120 having a plurality of holes 2122 through which a reducing gas can pass and disposed inside the container 2110. Also, the first to fourth reduction furnaces 2100a to 2100d may further include a cyclone 2140 disposed so that at least a portion of the cyclone 2140 is positioned inside the container 2110 and collects fine powder.

[0062] Some of the first to fourth reducing furnaces 2100a to 2100d may be provided with a burner 2130 that generates a flame. In this case, the burner 2130 is preferably provided in a reducing furnace located at the central end of the first to fourth reducing furnaces 2100a to 2100d, i.e., a reducing furnace other than the first and fourth reducing furnaces 2100a and 2100d. For example, the burner 2130 may be provided in at least one of the second and third reducing furnaces 2100b and 2100c. Needless to say, all of the first to fourth reducing furnaces 2100a to 2100d may be provided with the burner 2130. Also, at least one of the first and fourth reducing furnaces 2100a and 2100d located at both ends may be provided with the burner 2130.

[0063] 1, a description will be given of an example in which the second and third reduction furnaces 2100b, 2100c of the first to fourth reduction furnaces 2100a to 2100d are equipped with a burner 2130. Here, the second reduction furnace 2100b and the third reduction furnace 2100c have the same configuration, and the second and third reduction furnaces 2100b, 2100c are different from the first and fourth reduction furnaces 2100a to 2100d in that a burner 2130 is further provided in each of them.

[0064] Therefore, hereinafter, following the description of the reducing furnace, the second reducing furnace 2100b, which is one of the reducing furnaces equipped with burners, will be described as an example with reference to Figures 2 and 3. Descriptions of the first reducing furnace 2100a, the third and fourth reducing furnaces 2100c, 2100d will be omitted. The second reducing furnace 2100b described later may be simply referred to as the "reducing furnace 2100b."

[0065] 2 and 3, the reduction furnace 2100b may include a container 2110 having an internal space (reduction space) capable of accommodating a raw material and reducing the raw material, a dispersion member 2120 having a plurality of holes 2122 through which a reducing gas can pass and disposed inside the container 2110, and a burner 2130 disposed in 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 that at least a portion thereof is positioned inside the container 2110 and collects fine powder.

[0066] The dispersion member 2120 includes a plate-shaped body 2121 having a predetermined area and a plurality of holes 2122 provided in the body 2121 so that the gas can 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 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. Therefore, 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] A gas conveying pipe 2112b may be connected to the lower part of the container 2110 so as to communicate with the lower space of the dispersion member 2120, and a raw material conveying pipe 2111a may be connected to the upper space of the dispersion member 2120. Therefore, a reducing gas is supplied to the lower space of the dispersion member 2120 in the internal space of the container 2110, and raw materials are supplied to the upper space of the dispersion member 2120. At this time, the raw materials supplied to the inside of the container 2110 are loaded on the upper part of the dispersion member 2120. The reducing gas supplied to the lower space of the dispersion member 2120 passes through a plurality of holes 2122 of the dispersion member 2120 and moves to the upper side of the dispersion member 2120 or is sprayed thereon. The reducing gas sprayed to the upper side of the dispersion member 2120 causes the raw materials on the upper side of the dispersion member 2120 to flow. That is, the raw material particles on the upper side of the dispersion member 2120 flow due to the upward flow of the reducing gas passing through the multiple holes 2122 of the dispersion member 2120. Then, while flowing above the dispersion member 2120, the raw material reacts with the reducing gas and is reduced.

[0068] In the reduction furnace 2100b, a reduction reaction occurs between at least one of the hydrogen gas supplied from the hydrogen gas supply unit 2200 and the exhaust gas discharged from the melting device 3000 and supplied from the exhaust gas supply line 4000 and raw materials including iron ore. At this time, the reaction between the iron ore and hydrogen gas and the reaction between the iron ore and carbon monoxide (CO) contained in the exhaust gas are endothermic reactions. Therefore, there is a risk that the temperature inside the reduction furnace 2100b will drop due to the endothermic reaction, which causes a reduction in the reduction rate of the raw materials. Therefore, in order to ensure a smooth reduction reaction, it is necessary to adjust the temperature inside the reduction furnace 2100b to a predetermined temperature or higher. Therefore, a burner 2130 is disposed in the container 2110 to generate a flame F to heat the inside of the container 2110. The burner 2130 may be a means for blowing an oxidizing agent including oxygen (O) into the inside of the container 2110 and generating a flame F by a combustion reaction. The specific structure and shape of the burner 2130 will be described 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 are melted by the high heat of the dispersion member 2120 and entangled with each other, which may cause the holes 2122 of the dispersion member 2120 to become clogged. If the holes 2122 become clogged, the reducing gas cannot pass through, which causes a problem that the flow of the raw material above the dispersion member 2120 is not performed smoothly. If the flow of the raw material is not smooth, the reduction rate of the raw material decreases.

[0070] Therefore, the distance between the dispersion member 2120 and the burner 2130 is optimized. In other words, the burner 2130 is disposed at an optimized height. At this time, the burner 2130 is disposed so as to be positioned above the dispersion member 2120. For this reason, the distance between the dispersion member 2120 and the burner 2130 is defined as the "height of the burner 2130" or the "disposition height of the burner 2130."

[0071] When disposing the burner 2130 in the container 2110, the height at which the burner 2130 should be disposed is first determined, and the burner 2130 is disposed at the determined height. b ) may be determined according to the flow rate of the reducing gas to be supplied to the reducing furnace 2100b. More specifically, the installation height H b is the diameter (d or ) and 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] The burner installation height H is as follows: b A method for determining the above will now be described in more detail.

[0073] The height H at which the burner 2130 should be disposedb In determining the depth l of penetration of the reducing gas into the raw material layer above the dispersion member 2120, the flow rate of the reducing gas to be supplied to the reduction furnace 2100b is used. j Then, the calculated penetration depth l j is used to determine the height H at which the burner 2130 should be disposed. b Determine.

[0074] First, the depth to which the reducing gas penetrates into the raw material layer will be described with reference to Figures 2 and 3. Raw materials including iron ore are supplied into the container 2110 of the reduction furnace 2100b and loaded on the upper side of the dispersion member 2120 as shown in Figure 3. Therefore, the raw materials are piled up to a predetermined thickness on the upper side of the dispersion member 2120, and hereinafter, the raw materials piled up to a predetermined thickness on the upper side of the dispersion member 2120 will be referred to as a "raw material layer". The raw materials on the upper side of the dispersion member 2120 flow due to the reducing gas sprayed from below, so the raw material layer may also mean a fluidized layer.

[0075] The reducing gas supplied to the lower side of the dispersion member 2120 passes through a plurality of holes 2122 of the dispersion member 2120 and is sprayed onto the upper side where the raw material layer is located. As a result, the reducing gas permeates into the raw material layer above the dispersion member 2120. At this time, the reducing gas is sprayed up to a predetermined distance from the upper surface of the dispersion member 2120. In other words, the reducing gas permeates into the raw material layer above the dispersion member 2120, but to a predetermined depth. Here, the permeation depth l of the reducing gas is j is based on the top surface of the dispersion member 2120.

[0076] Depth l of reduction gas penetration into the raw material layer j In order to derive or predict, first, the flow rate of the reducing gas to be supplied to the reducing furnace 2100b, i.e., the container 2110 is determined. In other words, a target flow rate of the reducing gas to be supplied to the container is determined. Here, the target flow rate of the reducing gas may be determined by at least one of the amount of the raw material to be supplied to the reducing furnace 2100b, the volume of the container 2110 of the reducing furnace 2100b, and a target reduction rate.

[0077] The flow rate of the reducing gas to be supplied to the reducing furnace 2100b varies depending on at least one of the diameter of the holes 2122 of the dispersion member 2120 and the flow rate of the reducing gas to be supplied to the reducing furnace. For example, when the reducing gas is supplied at a predetermined target flow rate, the flow rate of the reducing gas (u or The higher the diameter (d or ) is reduced, and the flow rate of the reducing gas (u or The lower the diameter of the hole (d or The flow rate of the reducing gas may be adjusted by expanding the diameter of the nozzle.

[0078] Therefore, when the flow rate of the reducing gas to be supplied to the reduction furnace 2100b is determined, the determined flow rate of the reducing gas and the diameter (d or ) to determine the flow rate (u or ) to determine

[0079] Flow rate of reducing gas (u or Once the depth l of the reducing gas permeating into the raw material layer is determined, j More specifically, the depth l of the reduction gas penetrating into the raw material layer is predicted. j may vary depending on the flow rate of the reducing gas to be supplied to the container 2110. That is, the penetration depth l j is the diameter (d or ) and the flow rate (u or More specifically, the penetration depth l of the reducing gas may be determined according to j is the diameter (d or ) and the flow rate of the reducing gas (u or ), the density of the reducing gas (ρ g ), the dynamic viscosity of the reducing gas (μ), the particle density of the raw material (ρ s ) and the particle diameter of the raw material (d p ) may be determined.

[0080] More specifically, the diameter (d or ), the flow rate of the reducing gas (u or ), the density of the reducing gas (ρ g ), the dynamic viscosity of the reducing gas (μ), the particle density of the raw material (ρ s ) and the particle diameter of the raw material (d p ) is applied to the following formula 1 to calculate the depth l of the reduction gas penetrating into the raw material layer. j may be calculated.

[0081]

number

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

[0083] Here, the density of the reducing gas (ρ g ) 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 melting device 3000 is used as the reducing gas supplied to the reducing furnace 2100b, the density (ρ g ) and dynamic viscosity (μ) are applied.

[0084] In addition, the particle density of the raw material (ρ s ) and the particle diameter of the raw material (dp ) is determined according to the raw material to be supplied to the reduction furnace 2100b for producing reduced iron, and is a known value. That is, the particle density (ρ s ) and particle diameter (d p ) and apply them.

[0085] By this method, the penetration depth of the reducing gas l j In other words, the depth l of penetration of the reducing gas supplied to the reduction furnace 2100b into the raw material layer during the production process of reduced iron can be calculated. j It may be to predict.

[0086] Using formula 1, the depth l of the reducing gas penetrating into the raw material layer is calculated. j Once calculated, the calculated penetration depth l j is used to determine the height H at which the burner 2130 should be disposed. b At this time, the installation height H b is the calculated penetration depth l j And the height of the raw material layer H m It is determined as follows (see relation 1). Here, the height of the raw material layer H m The height H of the raw material layer may be the distance from the upper surface of the dispersion member 2120 to the upper surface of the raw material layer. m is the height H of the upper surface of the raw material bed before the reducing gas is supplied to the reduction furnace 2100b and before the raw material flows. m may be also possible.

[0087] [Equation 1] l j ≦H b ≦H m Equation 1

[0088] The following is the installation height H of the burner 2130. b A more specific example will be used to explain how to determine the calculated penetration depth l. j is 580 mm, and the height of the raw material bed when the raw material is supplied to the reduction furnace is 650 mm, the installation height H of the burner 2130 isb For example, the burner installation height H b may be determined to be 600 mm.

[0089] Burner 2130 installation height H b In determining the calculated penetration depth l j And the height of the raw material layer H m In order to determine the penetration depth l within the following range, j And the height of the raw material layer H m The range of "equipped height or less" is sometimes referred to as "installation height condition."

[0090] Installation height H b Once the determined installation height H b That is, the burner 2130 is disposed at a position where the distance from the dispersion member 2120 is determined. b In other words, the burner 2130 is disposed above the dispersion member 2120, and the distance from the upper surface of the dispersion member 2120 to the determined installation height H b At this time, the distance between the center of the burner 2130 in the diametric direction and the upper surface of the dispersion member 2120 is determined as the installation height H b It is preferable to arrange the burner 2130 so that the value of

[0091] On the other hand, the installation height H of the burner 2130 b If the distance between the burner 2130 and the dispersion member 2120 is too low and the 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 be stagnated. In other words, there is a risk that a congestion layer may be formed, and there is a concern that the congestion layer may become thick. 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. Conversely, if the installation height H of the burner 2130 is too low and the 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 be stagnated. In other words, there is a risk that a congestion layer may be formed, and there is a concern that the congestion layer may become thick. 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. 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 material may not occur smoothly. That is, in the case of the raw material located near the dispersion member 2120, the temperature may be low and the reaction with the reducing gas may not occur or may not occur sufficiently. In other words, the temperature of the raw material particles flowing above the dispersion member 2120, i.e., the fluidized bed, may be low and the reduction reaction may not occur sufficiently.

[0092] However, in the embodiment, the arrangement height H b Determine the installation height H b The burner 2130 is disposed in the upper part of the dispersion member 2120. This allows the raw material to flow smoothly without stagnation, while allowing the raw material to undergo a sufficient reduction reaction. That is, the heat of the flame F generated by the burner 2130 can be suppressed or prevented from heating the dispersion member 2120 to a high temperature, and the raw material particles can be suppressed or prevented from melting at a position close to the dispersion member 2120 and becoming entangled or agglomerated. This can suppress or prevent the raw material particles from not flowing or from stagnating in a state of low flow on the upper side of the dispersion member 2120 due to the heat of the dispersion member 2120. In other words, it can suppress or prevent the formation of a congestion layer in which the raw material particles do not flow or are accumulated in a state where the flow is suppressed. In addition, sufficient heat can be applied to the raw material and the reducing gas to allow the reduction reaction to occur smoothly.

[0093] Therefore, the installation height H of the burner 2130 determined by the method according to the embodiment b can be explained as a height that allows the raw material to be sufficiently reduced while suppressing or preventing the formation of a congestion layer.

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

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

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

[0097] As described above, the nozzles 2132a, 2132b may be provided in a plurality, for example, two nozzles (first and second nozzles 2132a, 2132b). Each of the first and second nozzles 2132a, 2132b extends in the extension 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, 2132b, one end and the other end, which are both ends in the extension direction, are open. Each of the first nozzle 2132a and the second nozzle 2132b may have an inner diameter of, for example, 15 mm to 20 mm, and more specifically, may be 16 mm to 19 mm. Needless to say, the inner diameter of each of the first and second nozzles 2132a, 2132b can be changed in various ways.

[0098] One end of each of the first and second nozzles 2132a and 2132b is an opening (hereinafter, a spray port) through which the oxidant is discharged or sprayed to the outside. The other end of each of the first and second nozzles 2132a and 2132b is an opening (hereinafter, a flow inlet) through which the oxidant flows inside. Here, an oxidant supply unit (not shown) may be connected to the other end of each of the first and second nozzles 2132a and 2132b. The oxidant supply unit may include a reservoir in which the oxidant is stored, a supply pipe connected to the first and second nozzles 2132a and 2132b to supply the oxidant, and an adjuster disposed in the supply pipe and capable of adjusting at least one of the supply flow rate and flow speed of the oxidant.

[0099] The oxidizing agent may contain oxygen (O), and the content of oxygen (O) in the total amount of the oxidizing agent may be 50 wt% or more and less than 100 wt%. The oxidizing agent may further contain a non-oxidizing substance in addition to oxygen (O), and the content of the non-oxidizing substance in the total amount of the oxidizing agent may be more than 0 wt% and less than 50 wt%. The non-oxidizing substance may contain nitrogen (N2). That is, the oxidizing agent may contain oxygen (O) and nitrogen (N2), and the content of oxygen (O) in the total amount of the oxidizing agent may be 50 wt% or more and less than 100 wt%, and the content of nitrogen (N2) may be more than 0 wt% and less than 50 wt%.

[0100] The reason why the oxidizing agent is not composed of 100% oxygen (O) but is prepared so as to further contain a non-oxidizing substance in addition to oxygen (O) is to lower the temperature of the flame generated by the combustion of the oxidizing agent inside the reducing furnace 2100b. That is, if the oxidizing agent is composed of 100% oxygen (O), there is a risk that the temperature of the flame formed inside the reducing furnace 2100b by the combustion reaction of the oxidizing agent is too high, and a congestion layer is formed, and there is a concern that a thick congestion layer is formed.

[0101] When the oxidizing agent is sprayed from each of the first nozzle 2132a and the second nozzle 2132b, the flow velocity is preferably adjusted to 80 m / sec to 100 m / sec.

[0102] The first nozzle 2132a and the second nozzle 2132b are provided so as to intersect each other, not in parallel. In this case, the first and second nozzles 2132a and 2132b may be provided so as to approach the center in the diameter direction of the main body 2131 as they progress from the other end to the one end. In other words, the first nozzle 2132a and the second nozzle 2132b may be provided so that the distance between them gradually becomes shorter as they progress from the other end to the one end.

[0103] In other words, the first and second nozzles 2132a, 2132b may be provided so as to be inclined or tilted. To explain this more specifically, an imaginary line connecting the center of one end of the main body 2131 in the diametric direction and the center of the other end in the diametric direction is defined as a "reference line L. c ". An imaginary line connecting one end and the other end of the first nozzle 2132a is defined as the "first nozzle extension line L n1 ", and a virtual line connecting one end and the other end of the second nozzle 2132b is defined as a "second nozzle extension line L n2 In providing the first and second nozzles 2132a and 2132b, the first and second nozzle extension lines L n1 , L n2 is the reference line L c The first and second nozzles 2132a and 2132b are not parallel to each other but are arranged to intersect with each other. n1 , L n2 is the reference line L c More specifically, the first and second nozzles 2132a and 2132b are arranged such that the included angles θ1 and θ2 formed by the first and second nozzle extension lines L n1 , L n2 is the reference line L c The first nozzle 2132a and the second nozzle 2132b are arranged so that the included angles θ1 and θ2 formed with the reference line L are 20° to 45°. c 4. Alternatively, the two may be provided symmetrically with respect to each other.

[0104] In this manner, each of the first and second nozzles 2132a, 2132b is aligned with the reference line L c Since the first and second nozzles 2132a and 2132b are arranged to intersect with the reference line L, rather than being parallel to the reference line L, c It can be explained that the first nozzle 2132a and the second nozzle 2132b are provided so as to be inclined with respect to each other. Also, the first nozzle 2132a and the second nozzle 2132b are not provided in parallel with each other but to intersect with each other. For this reason, it can be explained that the first nozzle 2132a is provided so as to be inclined with respect to the second nozzle 2132b, and the second nozzle 2132b is provided so as to be inclined with respect to the first nozzle 2132a.

[0105] The first and second nozzles 2132a, 2132b are inclined so that the distance between them decreases as they move toward one end of the body, in order to collide and disperse the oxidizers sprayed from the first and second nozzles 2132a, 2132b. Referring to FIG. 6, the oxidizers OM1, OM2 discharged from the nozzles of the first and second nozzles 2132a, 2132b are sprayed forward of the nozzles. At this time, the oxidizers OM1, OM2 discharged from the nozzles of the first and second nozzles 2132a, 2132b move in such a way that they have a flow approaching the center in the diameter direction of the burner 2130 as they move away from the nozzles. Therefore, the oxidizer sprayed from the first nozzle 2132a and the oxidizer sprayed from the second nozzle 2132b collide with each other at a location a predetermined distance forward from one end of the burner 2130. In this manner, after the oxidant sprayed from each of the first and second nozzles 2132a and 2132b collide with each other, the oxidant is widely dispersed.

[0106] The oxidizer sprayed from each of the first and second nozzles is sprayed in the shape of a stream having a predetermined width. Therefore, the flow of the oxidizer sprayed from each of the first and second nozzles with a predetermined width is defined as an "oxidizer stream." To explain the collision again in a manner reflecting this, the oxidizer stream emitted from the first nozzle 2132a and the oxidizer stream emitted from the second nozzle 2132b collide in front of the burner. After the multiple oxidizer streams collide, the oxidizer stream diffuses as shown in FIG. 6. That is, the multiple oxidizer streams collide with each other and merge to form one stream, which diffuses widely. Therefore, the width of the oxidizer stream becomes wider after the collision.

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

[0108] Flame F width W F may vary depending on the width of the oxidizer stream sprayed from the nozzles 2132a, 2132b. That is, the narrower the oxidizer stream, the narrower the width W of the flame F. F The narrower the oxidizer stream, the wider the flame width W F In addition, when the oxidizer is sprayed at the same flow rate, the width W of the flame F is F The narrower the flame width W, the higher the flame temperature and the F The wider the width W of the flame F, the lower the temperature of the flame. F The narrower the width W of the flame F, the greater the amount of oxidizer contained in the flame F, and therefore the combustion reaction occurs within a narrow range, resulting in the heat being concentrated. FThe wider the area, the less oxidizer is contained in the flame F, and the combustion reaction occurs over a wider area, so that heat is not concentrated but diffused widely, resulting in a lower flame temperature.

[0109] Here, the temperature of the flame F is the temperature of the flame at a given width W F The temperature of the flame F may mean the highest temperature in the flame F having a width direction. The temperature of the flame F is highest at its width direction center. Therefore, the temperature of the flame F means the temperature at the width direction center. A low temperature of the flame F means that the highest temperature, which is the temperature at the width direction center, is relatively low, and a high temperature of the flame F means that the highest temperature, which is the temperature at the width direction center, is relatively high.

[0110] Therefore, in the embodiment, in order to form a flame with a lower temperature than the conventional one, a burner capable of forming a flame with a wider width than the conventional one is provided. That is, a multi-hole burner 2130 capable of colliding the sprayed oxidizer to widely diffuse the oxidizer is provided. In other words, as described above, a plurality of nozzles 2132a, 2132b capable of spraying the oxidizer from each are provided, and each nozzle 2132a, 2132b is inclined so as to approach the center in the diameter direction of the main body 2131 as it proceeds toward one end of the main body 2131. As a result, the oxidizer streams sprayed from each of the plurality of nozzles 2132a, 2132b collide with each other, and the oxidizer stream is widely diffused. Therefore, a combustion reaction occurs in the oxidizer stream having a wide width, so that a wide flame can be formed. And, as a result, the temperature of the flame can be lowered compared to the conventional one. That is, the temperature of the flame emitted from the multi-hole burner 2130 having the multiple nozzles 2132a, 2132b as in the embodiment is lower than that of the flame emitted from a conventional single-hole burner having one nozzle.

[0111] When the burners 2130 are disposed 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, and the easier it is for a congestion layer to be formed, and the thickness of the congestion layer may be thick. Conversely, the lower the temperature of the flame F emitted from the burner 2130, the lower the temperature of the dispersion member 2120, and the harder it is for a congestion layer to be formed, and even if a congestion layer is formed, the thickness of the congestion layer is thin. For this reason, by generating a flame with a low temperature using the burner 2130 as in the embodiment, it is possible to suppress or prevent the congestion layer from being formed above the dispersion member 2120. As a result, the raw material above the dispersion member 2120 can be smoothly flowed by the reducing gas, and the reduction rate of the raw material can be improved. In other words, it is possible to sufficiently reduce the raw material charged in the reduction furnace 2100b.

[0112] In the above, the burner 2130 has been described as having two nozzles 2132a and 2132b. However, the present invention is not limited to this, and the number of nozzles may be variously more than two.

[0113] On the other hand, the first nozzle 2132a and the second nozzle 2132b are aligned with the reference line L c When the inclination angles θ1, θ2 of at least one of the first nozzle 2132a and the second nozzle 2132b are less than 20° or more than 45°, the oxidant streams may not collide with each other or the amount of collision may be insufficient. That is, when the inclination angles θ1, θ2 of at least one of the first nozzle 2132a and the second nozzle 2132b are less than 20° or more than 45°, the oxidant streams blown from the first nozzle 2132a and the oxidant streams blown from the second nozzle 2132b may not collide with each other or the amount of collision may be reduced. In such a case, a flame F with a narrow width may be formed due to insufficient diffusion of the oxidant stream, and the temperature of the flame F may become high. Therefore, the angles θ1, θ2 of the first and second nozzles 2132a, 2132b are adjusted to 20° to 45°.

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

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

[0116] On the other hand, if the flow velocity of the oxidant sprayed from at least one of the first and second nozzles 2132a and 2132b is less than 80 m / s, the oxidant stream sprayed from the first nozzle 2132a and the oxidant stream sprayed from the second nozzle 2132b may not collide with each other or the amount of collision may be reduced. Also, if the flow velocity of the oxidant sprayed from at least one of the first and second nozzles 2132a and 2132b exceeds 100 m / s, the flame temperature may be high, which may promote the formation of a congestion layer. Therefore, it is preferable to adjust the flow velocity of the oxidant sprayed from the first and second nozzles 2132a and 2132b to 80 m / s to 100 m / s.

[0117] Fig. 7 is a schematic diagram of an experimental reducing furnace. Fig. 8 shows the results of measuring the temperature in the horizontal direction at a predetermined height in the experimental reducing furnace. Fig. 9 shows the results of measuring the temperature in the region from the dispersion member to a predetermined height above in the experimental reducing furnace.

[0118] Here, Fig. 8(a) and Fig. 9(a) show the experimental results when a burner with one nozzle (single-hole burner) was installed in an experimental reducing furnace to generate a flame, while Fig. 8(b) and Fig. 9(b) show the experimental results when a burner according to the embodiment, i.e., a burner with multiple nozzles (multi-hole burner), was installed in an experimental reducing furnace to generate a flame.

[0119] First, the experimental reducing furnace will be described with reference to Fig. 7. The experimental reducing furnace shown in Fig. 7 has a similar configuration to the actual reducing furnace shown in Fig. 2. That is, the experimental reducing furnace includes a container 21, a dispersion member 22 having a plurality of holes through which the reducing gas can pass, and a burner that generates a flame.

[0120] In the experiment to obtain the results shown in Figures 8 and 9, a first type burner equipped with one nozzle was placed in a container and the second type burner was placed in the container. When placing the first type burner and the second type burner, respectively, and carrying out the experiment, the first type burner and the second type burner were placed at the same height. For this reason, the first type burner and the second type burner will be described with the same reference numeral "23a".

[0121] First, an experiment using the first type of burner 23a will be described. The first type of burner 23a is disposed in the container. At this time, the height H of the burner 23a is b1 was disposed so as to be located at a position 350 mm above the dispersion member 22. 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. At this time, hydrogen gas was used as the reducing gas. Next, the temperature inside the container 21 was measured. At this time, the height H at which the first type burner 23a was disposed was 100 mm. b1The temperature was measured in the horizontal direction at a distance of 350 mm from the surface of the substrate, and the results are shown in Fig. 8(a). The temperature was also measured in a predetermined region above the dispersion member 22, and the results are shown in Fig. 9(a).

[0122] Next, an experiment was carried out using the second type burner 23a. At this time, the installation height H b1 is the height H of the first type burner 23a described above. b1 Similarly, the height H at which the second type burner 23a was disposed was set to 350 mm. Then, an oxidizing agent was supplied to the second type 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 oxidizing agent and reducing gas supplied were the same as those in the experiment using the first type burner 23a. Next, the height H at which the second type burner 23a was disposed was set to 350 mm. b1 The temperature was measured in the horizontal direction at a distance of 350 mm from the surface of the substrate, and the results are shown in Fig. 8(b). The temperature was also measured in a predetermined region above the dispersion member 2120, and the results are shown in Fig. 9(b).

[0123] Comparing (a) and (b) of FIG. 8, the width W of the flame generated by the first type burner 23a at the same position is F1 The width W of the flame generated by the second type of burner 23a is F2 More specifically, when comparing the widths of the flames at positions horizontally away from the first and second types of burners 23a by an amount corresponding to the first distance D1, the width W of the flame generated by the first type of burner 23a is F1 (FIG. 8(a)) the width W of the flame generated by the second type burner 23a is F2 (b) of FIG. 8 is even wider. This shows that when the burner 2130 according to this embodiment is used, the width of the flame can be increased.

[0124] Comparing (a) and (b) of FIG. 9, the temperature of the dispersion member 22 in (b) of FIG. 9 is lower than that in (a) of FIG. 9. More specifically, the temperature of the dispersion member 22 located at a position corresponding to the second distance D2 in the horizontal direction from the first type burner 23a is high at about 1500°C. In contrast, the temperature of the dispersion member 22 located at a position corresponding to the second distance D2 in the horizontal direction from the second type burner 23a is low at about 1100°C. This shows that the temperature of the dispersion member 2120 can be lowered when the burner 2130 according to the embodiment is used.

[0125] Fig. 10 shows the temperature distribution by height inside the vessel when a first type burner having one nozzle is disposed in the vessel of an experimental reduction furnace and a flame is generated, and Fig. 11 shows the temperature distribution by height inside the vessel when a second type burner having first and second nozzles is disposed in the vessel of an experimental reduction furnace and a flame is generated. Here, the second type burner may be the burner according to the embodiment.

[0126] First, with reference to FIG. 7, the experiments performed to obtain the results in FIG. 10 will be described.

[0127] For the experiment, two first type burners were provided, and the two first type burners were positioned at different heights in the container 21. In this case, the first type burner placed at a relatively lower height is referred to as the first burner 23a, and the first type burner placed at a relatively higher height than the first burner 23a is referred to as the second burner 23b. In this case, the first burner 23a was located 350 mm above the dispersion member 22 at a height H b1 The second burner 23b is positioned at a height H b2An oxidizing agent was supplied to each of the first and second burners 23a, 23b of the first 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 temperature inside the container 21 was measured. At this time, the temperature inside the container 21 was measured at a height H at which the first burner 23a of the first type was disposed. b1 The temperature was measured in the horizontal direction at a height (350 mm) where the first type second burner 23b is disposed (600 mm), and the result is shown in Figure 10(a). The temperature was also measured in the horizontal direction at a height (600 mm) where the first type second burner 23b is disposed, and the result is shown in Figure 10(b). Then, the temperature was measured in the horizontal direction at a height below the first and second burners 23a, 23b and 100 mm above the dispersion member 22, and the result is shown in Figure 10(c).

[0128] In the same manner as this method, an experiment was carried out to obtain the results shown in FIG. 11. That is, two second-type burners were provided for the experiment, and the two second-type burners were disposed in the container at different heights. In this case, the second-type burner disposed at a relatively lower height is referred to as the first burner 23a, and the second-type burner disposed 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 is disposed at a height H 350 mm above the dispersion member 22. b1 The second burner 23b of the second type is disposed at a height H b2 An oxidizing agent was supplied to each of 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 height H at which the first burner 23a of the second type was disposed was b1 The temperature was measured horizontally at a height H (350 mm) from the center of the burner 23a, and the results are shown in FIG. 11(a). b2The temperature was measured in the horizontal direction at a height (600 mm) below the first and second burners 23a, 23b and 100 mm above the dispersion member 22, and the result is shown in Figure 11(c).

[0129] Referring to Fig. 10(a) regarding the temperature distribution in the horizontal direction, the temperature of the first region A1, which is the region at the height where the first type first burner 23a is disposed, is higher than the temperature of the second region A2, which is the region facing the lower side of the first type second burner 23b. Conversely, referring to Fig. 10(b), the temperature of the second region A2, which is the region at the height where the first type second burner 23b is disposed, is higher than the temperature of the first region A1, which is the region facing the upper side of the first type first burner 23a.

[0130] 11(a), the temperature distribution in the horizontal direction is similarly higher in the first region A1, which is the region at the height where the first burner 23a of the second type is disposed, than in the second region A2, which is the region facing the second burner 23b of the second type on the upper side. Conversely, with reference to FIG. 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 disposed, is higher than in the first region A1, which is the region facing the first burner 23a of the second type on the upper side.

[0131] This shows that the closer to the burner in the vertical direction, the higher the temperature.

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

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

[0134] This shows that the temperature of the dispersion member and its surroundings can be reduced when using the second type burner equipped with multiple nozzles and capable of colliding with the oxidizer, i.e., the burner according to the embodiment, under temperature conditions at the same height, compared to the first type burner (conventional burner) equipped with one nozzle, the temperature can be reduced when using the burner according to the embodiment.

[0135] In the embodiment, as described above, the height H of the burner 2130 bThe burner 2130 is disposed at an optimized distance from the dispersion member 2120. This can suppress or prevent the dispersion member 2120 from being heated to a high temperature by the heat of the flame F emitted from the burner 2130. This can suppress or prevent the raw material particles from melting near the dispersion member 2120 and becoming entangled or aggregated. This can suppress or prevent the formation of a congestion layer above the dispersion member 2120, and therefore the raw material can flow smoothly inside the reduction furnace. In addition, sufficient heat can be applied to the raw material and the reducing gas to cause the reduction reaction to occur smoothly.

[0136] The burner 2130 including the nozzles 2132a and 2132b can be used to lower the temperature of the flame F. That is, the burner 2130 according to the embodiment uses the nozzles 2132a and 2132b arranged at an angle so as to cross each other to spray the oxidant, thereby colliding and diffusing the oxidant. This makes it possible to widen the width of the oxidant stream sprayed in front of the burner 2130, thereby forming a flame F with a low temperature. This makes it possible to prevent the dispersion member 2120 and the raw material from being heated to an excessively high temperature by the high-temperature flame. This makes it possible to suppress the agglomeration due to the melting of the raw material particles, thereby making it possible to suppress or prevent the formation of a congestion layer. This makes it possible to smoothly flow the raw material inside the reduction furnace 2100b. [Industrial Applicability]

[0137] According to the present invention, it is possible to suppress or prevent the dispersion member from being heated to a high temperature by the heat of the flame generated by the burner. Also, it is possible to generate a flame with a lower temperature than in the past. Therefore, it is possible to suppress or prevent the aggregation caused by melting of the raw material particles, and thus it is possible to suppress or prevent the formation of a congestion layer. Therefore, it is possible to smoothly flow the raw material inside the reducing furnace.

Claims

1. A container having an internal space capable of accommodating a raw material including iron ore and a reducing gas; a dispersion member provided inside the container and having a plurality of holes through which the reducing gas can pass; 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 to the inside of the vessel, the burner generating a flame inside the vessel; A reduction furnace comprising:

2. The height of the burner is adjusted according to the target flow rate of the reducing gas, and the diameter (d ｏｒ ) and the flow rate of the reducing gas (u ｏｒ 2. The reducing furnace according to claim 1, wherein the height is determined using at least one of the following:

3. The height at which the burners are disposed is determined based on the depth (l) at which the reducing gas penetrates into the raw material layer made of the raw material supplied above the dispersion member. ｊ 2. The reducing furnace according to claim 1, wherein the height of the raw material layer is equal to or greater than the height of the upper portion of the raw material layer.

4. The burner is A main body extending in one direction; A plurality of nozzles are disposed inside the body so as to extend in an extension direction of the body and to be spaced apart from each other gradually shorter toward one end of the body; The reduction furnace according to claim 1, further comprising:

5. 5. The reducing furnace according to claim 4, wherein each of the plurality of nozzles is inclined at an angle of 20° to 45°.

6. 5. The reduction furnace according to claim 4, wherein the plurality of nozzles are provided symmetrically with respect to a center in a diameter direction of the main body.

7. Using the target flow rate of the reducing gas to be supplied to the vessel of the reduction furnace, the burner installation height (H ｂ ) and The distance upward from the dispersion member is determined as the determined placement height (H ｂ ) positioning a burner in the vessel such that supplying a raw material containing iron ore to an upper side of the dispersion member; passing a reducing gas through holes in the dispersion member to cause the raw material above the dispersion member to flow; generating a flame inside the vessel using said burner; a step of reacting the raw material with a reducing gas to reduce the raw material; A method for producing reduced iron, comprising:

8. The burner installation height (H ｂ determining a target flow rate of the reducing gas before the step of determining a target flow rate of the reducing gas; The determined target flow rate of the reducing gas and the diameter (d ｏｒ ) to determine the flow rate (u ｏｒ ) and The method for producing reduced iron according to claim 7, comprising:

9. The burner installation height (H ｂ The process of determining The diameter of the hole (d ｏｒ ) and the flow rate of the reducing gas (u ｏｒ ) to determine the depth (l) of the reducing gas penetrating into the raw material layer above the dispersion member. ｊ ) and The predicted penetration depth (l ｊ The burner installation height (H ｂ ) and The method for producing reduced iron according to claim 8, comprising:

10. The depth (l) of the reduction gas permeating into the raw material layer ｊ The process of predicting the diameter (d ｏｒ ), the flow rate of the reducing gas (u ｏｒ ), the density of the reducing gas (ρ ｇ ), density of raw material particles (ρ ｓ ), the particle size of the raw material particles (d ｐ ), the dynamic viscosity of the reducing gas (μ) is used to calculate the penetration depth (l ｊ 10. The method for producing reduced iron according to claim 9, further comprising the step of calculating:

11. The burner installation height (H ｂ ) to the predicted penetration depth (l ｊ 10. The method for producing reduced iron according to claim 9, further comprising a step of determining the height of the raw material layer within a range of at least the height of the upper part of the raw material layer.

12. The step of generating a flame inside the container using the burner includes: supplying an oxidizer to each of a plurality of nozzles provided on the burner; spraying an oxidizer from each of the plurality of nozzles to form an oxidizer stream; a step of colliding a plurality of the oxidant streams with each other to diffuse the oxidant streams; reacting the oxidant stream with a reducing gas to produce a flame; The method for producing reduced iron according to claim 7, comprising:

13. The step of spraying an oxidizer from each of the plurality of nozzles includes:

13. The method for producing reduced iron according to claim 12, further comprising a step of spraying the oxidant from each of the plurality of nozzles in such a manner that the oxidant has an inclined flow that gradually approaches a center in a diameter direction of the burner as it moves away from the burner.

14. The oxidizing agent is oxygen (O) and nitrogen (N ２ 13. The method for producing reduced iron according to claim 12, further comprising the step of:

15. The method for producing reduced iron according to claim 12, further comprising the step of adjusting a flow velocity of the oxidant sprayed from each of the plurality of nozzles to 80 m / sec to 100 m / sec.

16. The reducing gas is hydrogen (H ２ 16. The method for producing reduced iron according to claim 7, further comprising the step of:

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