Method for injecting reducing gas into a blast furnace and blast furnace

Abstract

The present invention discloses a method with which it is possible to easily control the flow rate of a reducing gas when the reducing gas is blown into the inside of a blast furnace, and with which it is also possible to stably blow the reducing gas into the blast furnace even in cases where the slag or the like flows back into a hot air tuyere. A method for blowing a reducing gas into a blast furnace according to the present disclosure comprises: blowing hot air into the inside of the blast furnace from a hot air tuyere which is provided below the lower end of the shaft of the blast furnace and above the taphole; and blowing a reducing gas into the inside of the blast furnace from a reducing gas blowing port which is provided below the lower end of the shaft of the blast furnace and above the taphole. Here, the reducing gas functions as a reducing material inside the blast furnace. The reducing gas blowing port is provided separately from the hot air tuyere, and the height position P1 of the center of the reducing gas blowing port is located above the height position P2 of the center of the hot air tuyere.

Description

Technical Field

[0001] This application discloses a method for injecting reducing gas into a blast furnace and a blast furnace.

Background Art

[0002] In the ironmaking process, reduction of CO2 emissions has been under consideration. For example, when producing pig iron in a blast furnace, reducing gas such as hydrogen gas may be used in place of a part of coke or the like as a reducing material. As a method for injecting reducing gas into a blast furnace, Patent Document 1 discloses a method in which a lance for injecting reducing gas is arranged in the flow path of a hot blast tuyere, and the reducing gas is injected through the lance and the tuyere. Although it is not assumed to inject reducing gas, Patent Document 2 discloses a method in which a fuel injection lance is inserted into the wall surface of a hot blast tuyere, and pulverized coal as fuel is injected into the blast furnace through the fuel injection lance.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] As disclosed in Patent Document 1, when a lance is placed inside a hot blast tuyer, the lance diameter must be kept below a certain size depending on the shape and size of the hot blast tuyer. Therefore, if a large amount of reducing gas is blown in through a lance placed inside the hot blast tuyer, the flow velocity of the reducing gas will exceed the speed of sound. In this respect, there is room for improvement in the conventional technology regarding the control of the flow velocity of the reducing gas. Furthermore, in the conventional technology, if the furnace conditions of the blast furnace become unstable and molten slag or the like flows back into the hot blast tuyer, it becomes difficult to stably blow reducing gas into the blast furnace. From these viewpoints, the present application discloses a technology that allows for easy control of the flow velocity of the reducing gas when blowing reducing gas into the inside of a blast furnace, and that increases the likelihood of stably blowing reducing gas into the blast furnace even if slag or the like flows back into the hot blast tuyer. [Means for solving the problem]

[0005] This application discloses several embodiments as means for solving the above-mentioned problems. <Aspect 1> A method for injecting reducing gas into a blast furnace, Hot air is blown into the interior of the blast furnace from a hot air tuyeres located below the lower end of the blast furnace shaft and above the taphole, This includes injecting reducing gas into the interior of the blast furnace from a reducing gas injection port located below the lower end of the blast furnace shaft and above the taphole, The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The aforementioned reducing gas inlet is provided separately from the aforementioned hot air vent, The height position P1 of the center of the reducing gas inlet is above the height position P2 of the center of the hot air tuyere. Method for injecting reducing gas into a blast furnace. <Aspect 2> A blast furnace, A hot air tuyere is provided below the lower end of the blast furnace shaft and above the taphole, A reducing gas injection port is provided below the lower end of the blast furnace shaft and above the taphole, It has, The reducing gas blown into the blast furnace from the reducing gas inlet is a gas that functions as a reducing agent inside the blast furnace. The aforementioned reducing gas inlet is provided separately from the aforementioned hot air vent, The height position P1 of the center of the reducing gas inlet is above the height position P2 of the center of the hot air tuyere. Blast furnace. [Effects of the Invention]

[0006] According to the technology disclosed herein, when injecting reducing gas into the interior of a blast furnace, the flow rate of the reducing gas can be controlled, and even if slag or the like flows back into the hot air tuyer, it is possible to stably inject the reducing gas into the blast furnace. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram provides a general overview of the blast furnace's configuration. Some components of the blast furnace are omitted from the diagram. [Figure 2A] This diagram schematically shows an example of the positional relationship between the hot air tuyeres and the reducing gas inlet in a blast furnace. [Figure 2B] This diagram schematically shows an example of the positional relationship between the hot air tuyeres and the reducing gas inlet in a blast furnace. [Figure 3] This is a schematic diagram illustrating the location where slag reaches when it flows back into the hot air nozzle. [Modes for carrying out the invention]

[0008] The following describes one embodiment of the reducing gas injection method into a blast furnace and the blast furnace according to this disclosure. However, the reducing gas injection method into a blast furnace and the blast furnace according to this disclosure are not limited to the following embodiment.

[0009] 1. Method for injecting reducing gas into a blast furnace As shown in Figure 1, the method for injecting reducing gas into a blast furnace 10 according to one embodiment is: Hot air is blown into the interior of the blast furnace 10 from a hot air tuyere 13 provided below the lower end 11ax of the shaft of the blast furnace 10 and above the tapping spout 12, and reduced gas is blown into the interior of the blast furnace 10 from a reduced gas injection port 14 provided below the lower end 11ax of the shaft of the blast furnace 10 and above the tapping spout 12. The reduced gas is a gas that functions as a reducing agent inside the blast furnace 10. The reduced gas injection port 14 is provided separately from the hot air tuyere 13. The height position P1 of the center of the reduced gas injection port 14 is above the height position P2 of the center of the hot air tuyere 13.

[0010] 1.1 Hot Air Tuyere The blast furnace 10 has a hot air tuyere 13 below the lower end 11ax of the shaft and above the tapping spout 12. The "lower end of the shaft" refers to the boundary between the shaft 11a and the belly (bosh) 11b. The "shaft" refers to the part above the belly 11b, and usually, the furnace diameter increases from top to bottom. The "belly" refers to the part below the shaft and above the tuyere (bosch) 11c, and usually, the furnace diameter is the largest. The furnace diameter (diameter) of the belly 11b may be, for example, 5 m or more and 20 m or less, or 10 m or more and 18 m or less. The "tapping spout" refers to the molten iron tapping spout provided at the lower part of the blast furnace 10. The "hot air tuyere" refers to a nozzle for blowing hot air into the blast furnace. The blast furnace 10 may have a hot air tuyere 13 below the lower end 11bx of the belly and above the tapping spout 12, or may have a hot air tuyere 13 below the lower end 11cx of the tuyere and above the tapping spout 12.

[0011] The structure of the hot blast tuyere 13 is well-known. For example, the hot blast tuyere 13 may have a water-cooled structure. The hot blast tuyere 13 can be connected to a hot blast stove outside the blast furnace 10 via a hot blast pipe or the like. In other words, the blast furnace 10 can be configured such that hot blast is blown into the blast furnace 10 from the hot blast stove through the hot blast pipe and the hot blast tuyere 13. The diameter of the hot blast tuyere 13 (the equivalent diameter of the circle of the opening facing the inside of the blast furnace 10, the nozzle diameter) may be, for example, 20 mm or more and 400 mm or less, or 40 mm or more and 300 mm or less.

[0012] The number of hot blast tuyeres 13 provided in the blast furnace 10 is not particularly limited and can be determined according to the internal volume of the blast furnace. A plurality of hot blast tuyeres 13 can be arranged in the circumferential direction of the blast furnace 10. In other words, in the blast furnace 10, in a top view, a plurality of hot blast tuyeres 13 can be arranged in the circumferential direction. Usually, the height position P2 of the center of each of the plurality of hot blast tuyeres 13 is the same.

[0013] 1.2 Reduction gas injection port The blast furnace 10 has a reduction gas injection port 14 below the lower end 11ax of the shaft and above the tapping hole 12. Thereby, the reduction reaction can proceed efficiently inside the blast furnace 10. Also, when the reduction gas injection port 14 is provided in the vicinity of the hot blast tuyere in the height direction of the furnace below the lower end 11ax of the shaft and above the tapping hole 12, it is unlikely that the discharge of molten iron and slag will be hindered by the reduction gas injection port 14.

[0014] There is no particular limitation on the shape of the reduction gas injection port 14. The reduction gas injection port 14 may be, for example, a tuyere (nozzle). The reduction gas injection port 14 can be defined by a metal (e.g., copper) or a refractory.

[0015] In the blast furnace 10, molten iron and slag may drip into the reducing gas inlet 14. Also, when hydrogen gas is injected as a reducing gas from the reducing gas inlet 14 to reduce the amount of carbon material added, the amount of heat inside the blast furnace 10 decreases, and the reducing gas itself may be heated to compensate for the heat. In this case, it is difficult to cool the reducing gas inlet 14 with the reducing gas. In this regard, a water cooling structure may be provided around the reducing gas inlet 14 (or inside the wall of the tuyere if the reducing gas inlet 14 is a tuyere) to suppress melting or erosion of the metal or refractory material defining the reducing gas inlet 14.

[0016] The reducing gas inlet 14 can be connected to an external reducing gas supply source of the blast furnace 10 via a reducing gas supply channel or the like. In other words, the blast furnace 10 can be configured so that reducing gas is injected into the interior of the blast furnace 10 from a reducing gas supply source via a reducing gas supply channel and the reducing gas inlet 14. There are no particular restrictions on the form of the reducing gas supply source or the reducing gas supply channel.

[0017] In this embodiment, it is important that the reducing gas inlet 14 is provided separately from the hot air tuyere 13. When the reducing gas inlet 14 is provided separately from the hot air tuyere 13, it is possible to increase the diameter of the reducing gas inlet 14 regardless of the shape and size of the hot air tuyere 13. This makes it possible to control the flow velocity of the reducing gas to less than the speed of sound, even when a large amount of reducing gas is injected from the reducing gas inlet 14. Assuming that a large amount of reducing gas is injected into the interior of the blast furnace 10 through the reducing gas inlet 14, the diameter of the reducing gas inlet 14 (the diameter equivalent to the circle of the opening facing the interior of the blast furnace 10) may be, for example, 30 mm or more and 400 mm or less, or 60 mm or more and 100 mm or less. Alternatively, the diameter of the reducing gas inlet 14 may be 0.15% or more and 8% or less, or 0.5% or more and 3% or less, of the diameter of the furnace belly 11b. Alternatively, the diameter of the reducing gas inlet 14 may be 7.5% to 200% of the diameter of the hot air nozzle 13.

[0018] The number of reducing gas inlets 14 provided in the blast furnace 10 is not particularly limited. For example, multiple reducing gas inlets 14 may be arranged in the circumferential direction of the blast furnace. In other words, in the blast furnace 10, multiple reducing gas inlets 14 may be arranged in the circumferential direction when viewed from above. The height position P1 of the center of each of the multiple reducing gas inlets 14 may be the same.

[0019] 1.3 Positional relationship between the hot air nozzle and the reducing gas inlet In this embodiment, it is important that the height position P1 of the center of the reducing gas inlet 14 is above the height position P2 of the center of the hot air tuyere 13. According to our new findings, if the height position P1 of the center of the reducing gas inlet 14 is the same as or lower than the height position P2 of the center of the hot air tuyere 13, and slag or the like flows back into the hot air tuyere 13, then slag or the like is likely to flow back into the reducing gas inlet 14 as well. In other words, slag or the like flows back not only into the hot air tuyere 13 but also into the reducing gas inlet 14, making it difficult to stably inject reducing gas from the reducing gas inlet 14 into the blast furnace 10. On the other hand, if the height position P1 of the center of the reducing gas inlet 14 is above the height position P2 of the center of the hot air tuyere 13, then even if slag or the like flows back into the hot air tuyere 13, backflow of slag or the like into the reducing gas inlet 14 can be avoided. As a result, the likelihood of stably injecting reducing gas from the reducing gas inlet 14 into the blast furnace 10 increases. In particular, when the height position P1 of the center of the reducing gas inlet 14 is above the upper end of the hot air tuyere 13, backflow of slag and other substances into the reducing gas inlet 14 is even more easily avoided.

[0020] Figures 2A and 2B show the case where the height position P1 of the center of the reducing gas inlet 14 is above the height position P2 of the center of the hot air tuyere 13. As shown in Figure 2A, the center of the reducing gas inlet 14 may be located directly above the center of the hot air tuyere 13. That is, the position of the center of the reducing gas inlet 14 in the circumferential direction of the blast furnace 10 may be the same as the position of the center of the hot air tuyere 13. Also, as shown in Figure 2B, the center of the reducing gas inlet 14 may be located diagonally above the center of the hot air tuyere 13. That is, in the circumferential direction of the blast furnace 10, the center of the reducing gas inlet 14 may be located at a different position from the center of the hot air tuyere 13. For example, when multiple hot air tuyeres 13 are provided in the circumferential direction of the blast furnace 10, the position of the reducing gas inlet 14 in the circumferential direction of the blast furnace 10 may be located between the multiple hot air tuyeres 13.

[0021] The length L between the height position P1 at the center of the reducing gas inlet 14 and the height position P2 at the center of the hot air tuyere 13 is greater than 0 mm. This length L may be, for example, greater than 0 mm and 3000 mm or less, or greater than 0 mm and 300 mm or less.

[0022] 1.4 Hot air The hot air blown in from the hot air tuyer 13 may consist of, for example, air, or oxygen-enriched air. The temperature of the hot air is, for example, 1000°C or higher. The temperature of the hot air may be between 1000°C and 2000°C, between 1000°C and 1700°C, between 1000°C and 1500°C, or between 1000°C and 1300°C. The flow velocity of the hot air in the hot air tuyer 13 (the flow rate of the hot air (m) 3 / s) / Opening area of ​​the outlet of the hot air nozzle 13 (m 2 )) may be adjusted according to the operating conditions of the blast furnace 10. In one embodiment, the hot air flow velocity may be the flow velocity V1 described later.

[0023] 1.5 Reducing gas The reducing gas injected from the reducing gas inlet 14 is a gas that functions as a reducing agent inside the blast furnace 10. That is, even if a gas does not function as a reducing agent before being injected into the blast furnace 10, if it can generate a reducing agent (reducing component) inside the blast furnace 10 by thermal decomposition or other means, it is included in the term "reducing gas" as used in this application. Examples of such reducing gases include at least one selected from hydrogen gas, hydrocarbon gases (e.g., methane gas), carbon monoxide gas, ammonia gas, and alcohol gases (e.g., methanol gas and ethanol gas). In addition, in the technology of this disclosure, at least one selected from coke oven gas (COG), converter gas (LDG), blast furnace gas (BFG), natural gas (NG), and synthesis gas (Syngas) may be used as the reducing gas. These reducing gases may be used individually or in combination of two or more types. The temperature of the reducing gas blown in from the reducing gas inlet 14 may be, for example, 0°C to 2000°C or 25°C to 1500°C. Also, as described above, in this embodiment, the reducing gas inlet 14 is provided separately from the hot air tuyere 13, which allows for the flow velocity (flow rate (m) of the reducing gas to be controlled. 3 / s) / Opening area of ​​the outlet of the reducing gas inlet 14 (m 2 The velocity can be controlled to be less than the speed of sound. That is, the velocity of the reducing gas at the reducing gas inlet 14 is less than the speed of sound. It is known that the "speed of sound" depends not only on the type of gas but also on the temperature of the gas. The "speed of sound" can be determined by calculation or other means depending on the type and temperature of the gas injected into the blast furnace 10. In one embodiment, the velocity of the reducing gas may be the velocity V2 described later.

[0024] 1.6 Flow velocity of hot air and flow velocity of reducing gas The flow velocity V1 of the hot air blown in from the hot air tuyeres 13 is not particularly limited, but for example, if the flow velocity V1 is between 100 m / s and 1000 m / s, and more particularly between 200 m / s and 400 m / s, the operation of the blast furnace 10 is more likely to be stabilized. Also, the flow of reducing gas blown in from the reducing gas inlet 14 FastV2 is not particularly limited, but for example, the flow Fast When V2 is between 100 m / s and 1000 m / s, and more particularly between 200 m / s and 800 m / s, the ventilation inside the blast furnace 10 is stable, and the in-furnace reduction reaction proceeds stably.

[0025] 1.7 Other Gases Other gases may be injected along with the reducing gas from the reducing gas inlet 14. Examples of other gases include inert gases such as nitrogen gas.

[0026] 2.Blast furnace The technology disclosed herein has aspects not only as a method for injecting reducing gas into a blast furnace, but also as a blast furnace itself. That is, as shown in Figure 1, a blast furnace 10 according to one embodiment is A hot air tuyere 13 is provided below the lower end 11ax of the shaft of the blast furnace 10 and above the taphole 12, The blast furnace 10 has a reducing gas inlet 14 located below the lower end 11ax of the shaft and above the taphole 12. The reducing gas blown into the blast furnace 10 from the reducing gas inlet 14 is a gas that functions as a reducing agent inside the blast furnace 10. The reducing gas inlet 14 is provided separately from the hot air nozzle 13. The height position P1 at the center of the reducing gas inlet 14 is located above the height position P2.

[0027] As described above, in the blast furnace 10, the reduction gas inlet 14 is provided separately from the hot air tuyere 13, which improves the controllability of the reduction gas flow rate. Furthermore, in the blast furnace 10, the height position P1 of the center of the reduction gas inlet 14 is higher than the height position P2 of the center of the hot air tuyere 13, which increases the likelihood that reduction gas can be stably injected into the blast furnace 10 from the reduction gas inlet 14 even in situations where slag or the like flows back into the hot air tuyere 13.

[0028] 3. Supplement In the operation of the blast furnace 10, for example, iron ore (iron oxide) and coke are charged into the blast furnace 10 from the top, while hot air is blown into the blast furnace 10 from a hot blast furnace outside the blast furnace 10 via hot air pipes and hot air tuyeres 13, and reducing gas is blown into the blast furnace from a reducing gas supply source outside the blast furnace 10 via a reducing gas flow path and reducing gas inlet 14. The coke and other materials supplied into the blast furnace 10 are burned to generate reducing gas. The iron oxide is reduced and dissolved by the reducing gas produced by the combustion of the coke and other materials, and by the reducing gas blown in from the reducing gas inlet 14, to obtain molten iron. The molten iron is tapped out from a tap 12 located at the bottom of the blast furnace 10. In this embodiment, by blowing reducing gas into the blast furnace 10 via the reducing gas inlet 14, the amount of carbon-containing reducing material such as coke used can be reduced accordingly. As a result, CO2 emissions can be reduced. The blast furnace 10 can take on various configurations as long as it is capable of producing pig iron as described above. For example, the blast furnace 10 may have other tuyeres and inlets in addition to the hot air tuyeres 13 and reducing gas inlets 14 described above. In addition, other reducing gas inlets may be located at the same height as the hot air tuyeres 13, or below the hot air tuyeres 13, in the blast furnace 10. As the configuration of the blast furnace 10 other than the hot air tuyeres 13 and reducing gas inlets 14 is known in the art, a detailed explanation is omitted here.

[0029] 4. Effects As described above, according to this embodiment, by injecting reducing gas into the blast furnace 10 through a reducing gas inlet 14 provided separately from the hot air tuyere 13, the flow velocity of the reducing gas can be controlled to less than the speed of sound. Furthermore, since the height position P1 of the center of the reducing gas inlet 14 is located above the height position P2 of the center of the hot air tuyere 13, the likelihood of stably injecting reducing gas into the blast furnace 10 from the reducing gas inlet 14 is increased, even in situations where slag or the like flows back into the hot air tuyere 13. [Examples]

[0030] The present invention will be further described below with reference to examples, but the present invention is not limited to the following examples. The present invention allows for the adoption of various conditions without departing from its gist and insofar as it achieves its objective. In the following examples, the case in which hydrogen gas is used as the reducing gas is illustrated, but the type of reducing gas is not limited thereto.

[0031] 1. Examination of hydrogen gas flow velocity Using a simulation model, the required hydrogen injection rate per hydrogen gas inlet was estimated for a blast furnace with an average production rate of 12,000 t / d, assuming a reduction rate of 30% or more in carbon consumption per unit of production, based on a hydrogen injection temperature of 600°C. The hydrogen gas flow velocity was calculated from the estimated required hydrogen injection rate and the hydrogen gas inlet diameter. A "○" was used to indicate that the calculated flow velocity was slower than the speed of sound in a hydrogen atmosphere, while a "×" was used to indicate that it was faster than the speed of sound. The speed of sound in a hydrogen atmosphere at 600°C is approximately 1269 m / s. The calculation results are shown in Table 1 below.

[0032] [Table 1]

[0033] As is clear from the results shown in Table 1, conventional lances (lances built into the hot air tuyeres) cannot inject hydrogen gas at a flow rate below the speed of sound. In other words, conventional lances have limitations on the flow rate of hydrogen gas injected into the blast furnace, and cannot sufficiently reduce the carbon consumption per unit of fuel. In contrast, when injecting hydrogen gas through a large-diameter nozzle (for example, a reducing gas nozzle provided separately from the hot air tuyeres), an inner diameter of 60 mm at 1 atmosphere and 80 mm even at furnace pressure allows for the injection of hydrogen gas at a flow rate below the speed of sound. Inner diameters of 60 mm and 80 mm are not significantly different from the inner diameters of hot air tuyeres provided in blast furnaces, and can be used without problems in blast furnaces. Furthermore, increasing the temperature of hydrogen makes the speed at which sound is reached even faster. That is, by increasing the temperature of hydrogen, it is possible to inject hydrogen gas at a flow rate below the speed of sound even when the diameter of the nozzle is reduced. However, even if the hydrogen temperature is increased, it was confirmed that reducing the diameter of the inlet to the conventional lance diameter makes it difficult to control the hydrogen gas flow rate to below the speed of sound.

[0034] From the above, it can be said that by injecting reducing gas into the blast furnace not through a lance built into the hot air tuyer, but through a reducing gas injection port (for example, a reducing gas injection tuyer) provided separately from the hot air tuyer, the flow velocity of the reducing gas can be controlled to below the speed of sound.

[0035] 2. Investigation of slug return performance An investigation into the occurrence of slag return to the blast furnace tuyeres revealed that slag return caused blockage of the tuyeres eight times over the past 10 years. Further investigation was then conducted into the height reached by the slag during slag return. Specifically, as shown in Figure 3, the opening of the blast furnace tuyere was divided into four sections vertically, and the number of times the slag reached each section—"top," "upper middle," "lower middle," and "bottom"—was investigated. The results are shown in Table 2 below.

[0036] [Table 2]

[0037] As shown in Table 2, over the past 10 years, slag reached the "lowest part" of the hot air tuyere opening 5 times due to slag return, reached the "lower center" of the hot air tuyere opening 2 times, reached the "upper center" of the hot air tuyere opening 1 time, and reached the "highest part" of the hot air tuyere opening 0 times.

[0038] Based on the above, when reducing gas is injected from a reducing gas inlet (for example, a reducing gas injection inlet) that is separate from the hot air tuyere, if the height position P1 of the center of the reducing gas injection inlet is higher than the height position P2 of the center of the hot air tuyere, it is possible to increase the likelihood of stably injecting reducing gas into the blast furnace from the reducing gas injection inlet, even in situations where slag or other materials flow back into the hot air tuyere.

[0039] 3. Summary In summary, the following methods (1) and blast furnace (2) allow for easy control of the reducing gas flow rate when injecting reducing gas into the blast furnace, and increase the likelihood of stably injecting reducing gas into the blast furnace from the reducing gas injection nozzle, even in situations where slag or other materials flow back into the hot air tuyeres.

[0040] (1) A method for injecting reducing gas into a blast furnace, Hot air is blown into the interior of the blast furnace from a hot air tuyeres located below the lower end of the blast furnace shaft and above the taphole, This includes injecting reducing gas into the interior of the blast furnace from a reducing gas injection port located below the lower end of the blast furnace shaft and above the taphole, The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The aforementioned reducing gas inlet is provided separately from the aforementioned hot air vent, The height position P1 of the center of the reducing gas inlet is above the height position P2 of the center of the hot air tuyere. Method for injecting reducing gas into a blast furnace.

[0041] (2) A blast furnace, A hot air tuyere is provided below the lower end of the blast furnace shaft and above the taphole, A reducing gas injection port is provided below the lower end of the blast furnace shaft and above the taphole, It has, The reducing gas blown into the blast furnace from the reducing gas inlet is a gas that functions as a reducing agent inside the blast furnace. The aforementioned reducing gas inlet is provided separately from the aforementioned hot air vent, The height position P1 of the center of the reducing gas inlet is above the height position P2 of the center of the hot air tuyere. Blast furnace. [Explanation of Symbols]

[0042] 10 blast furnace 11a shaft 11b Hearth (Berry) 11c Morning Glory (Bosch) 12 Taphead 13 Hot air nozzle 14. Reducing gas inlet

Claims

1. A method for injecting reducing gas into a blast furnace, Hot air is blown into the interior of the blast furnace from a hot air tuyeres located below the lower end of the blast furnace shaft and above the taphole, This includes injecting reducing gas into the interior of the blast furnace from a reducing gas injection port located below the lower end of the blast furnace shaft and above the taphole, The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The reducing gas inlet is not built into the hot air tuyere, but is provided separately from the hot air tuyere. The height position P of the center of the aforementioned reducing gas injection port. １ However, the height position P of the center of the hot air nozzle ２ It is located above, The flow velocity of the reducing gas blown in from the aforementioned reducing gas inlet is 100 m / s or more and 1000 m / s or less. Method for injecting reducing gas into a blast furnace.

2. A method for injecting reducing gas into a blast furnace according to Claim 1, In the circumferential direction of the blast furnace, the center of the reducing gas inlet is located at a different position from the center of the hot air tuyere. Method for injecting reducing gas into a blast furnace.

3. A blast furnace, A hot air tuyere is provided below the lower end of the blast furnace shaft and above the taphole, A reducing gas injection port is provided below the lower end of the blast furnace shaft and above the taphole, It has, The reducing gas blown into the blast furnace from the reducing gas inlet is a gas that functions as a reducing agent inside the blast furnace. The reducing gas inlet is not built into the hot air tuyere, but is provided separately from the hot air tuyere. The height position P of the center of the aforementioned reducing gas injection port. １ However, the height position P of the center of the hot air nozzle ２ It is located above, The flow velocity of the reducing gas blown in from the aforementioned reducing gas inlet is 100 m / s or more and 1000 m / s or less. Blast furnace.

4. A blast furnace according to claim 3, In the circumferential direction of the blast furnace, the center of the reducing gas inlet is located at a different position from the center of the hot air tuyere. Blast furnace.

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