Blast furnace, method for operating blast furnace, and tuyere

Abstract

A method for operating a blast furnace having a tuyere, wherein: the tuyere has a tuyere main body, a gaseous reducing material blowing lance, and a solid reducing material blowing lance; the tuyere main body has a hot air flow path; the gaseous reducing material blowing lance has an outlet in the hot air flow path; and the solid reducing material blowing lance penetrates the tuyere main body.

Description

Blast furnace, blast furnace operating method, and tuyeres

[0001] This disclosure relates to a blast furnace, a method of operating a blast furnace, and a tuyeres. This application claims priority under Japanese Patent Application No. 2025-052916, filed in Japan on March 27, 2025, the contents of which are incorporated herein by reference.

[0002] In the iron and steel industry, the blast furnace method is the dominant process for producing pig iron. In the blast furnace method, blast furnace iron-based raw materials (raw materials containing iron oxide, mainly sintered ore; hereinafter simply referred to as "iron-based raw materials") and coke are alternately and layered into the blast furnace from the top, while hot air is blown into the blast furnace from tuyeres at the bottom. The hot air reacts with, for example, pulverized coal blown in with the hot air and the coke in the blast furnace to generate high-temperature reducing gas (in this case, mainly CO gas). In other words, the hot air gasifies the coke and pulverized coal. The reducing gas rises inside the blast furnace, heating and reducing the iron-based raw materials. The iron-based raw materials descend inside the blast furnace, being heated and reduced by the reducing gas. Subsequently, the iron-based raw materials melt and drip down the blast furnace while being further reduced by the coke. The iron-based raw materials are ultimately stored in the hearth as molten pig iron. The molten iron from the hearth is removed through the taphole and used in the next steelmaking process. Therefore, in the blast furnace method, carbon materials such as coke and pulverized coal are used as reducing agents.

[0003] By the way, in recent years, there has been much talk about preventing global warming, and carbon dioxide (CO2), one of the greenhouse gases, is being addressed. ２ Reducing CO2 emissions has become a social issue. As mentioned above, the blast furnace method uses carbon as a reducing agent, so a large amount of CO2 is emitted. ２ It generates gas. Therefore, the steel industry is CO2 ２ As one of the major industries in terms of gas emissions, we must respond to this societal demand. Specifically, there is an urgent need to further reduce the reducing agent ratio (amount of reducing agent used per ton of molten iron) in blast furnace operations.

[0004] Reducing agents play two roles in the furnace: generating heat to raise the temperature of the charge and reducing the iron-based raw materials. To reduce the reducing agent ratio, it is necessary to increase the reduction efficiency in the furnace. The reduction reaction in the furnace can be expressed by various reaction equations. Of these reduction reactions, the direct reduction reaction with coke (reaction equation: FeO + C → Fe + CO) is an endothermic reaction that involves a large amount of heat absorption. Therefore, minimizing the occurrence of this reaction is important in reducing the reducing agent ratio. Since this direct reduction reaction occurs in the lower part of the blast furnace, the iron-based raw materials must absorb CO and H before reaching the lower part of the furnace. ２ If iron-based raw materials can be sufficiently reduced with reducing gases such as those mentioned above, the amount of iron-based raw materials that are directly subject to reduction can be reduced.

[0005] When a large amount of hydrogen-based reducing gas is injected into the blast furnace from the tuyeres, the upper and lower parts of the furnace (the lower part here refers to the Sol Roth reaction (C + CO)) ２ →2CO) This is the region where the furnace temperature is higher than the starting temperature. The upper part of the furnace is the region above the lower part of the furnace. The thermal balance of the upper and lower parts changes significantly. Therefore, it is necessary to appropriately control the operating parameters so that the thermal balance of the upper and lower parts of the furnace is maintained. In other words, if a large amount of hydrogen-based reducing gas is blown into the blast furnace from the tuyere in order to enjoy a significant carbon reduction effect, the tuyere combustion temperature will decrease. If the oxygen enrichment rate is increased to suppress this decrease in tuyere combustion temperature, the heat flow ratio will increase. As a result, the furnace top gas temperature will decrease, falling below the lower limit of the furnace top gas temperature as an operational management standard, and there is a concern that this may lead to a significant delay in the heating of the charges in the upper part of the furnace and a deterioration of ventilation due to insufficient discharge of dust to the outside of the furnace.

[0006] Furthermore, if the reducing agent is replaced with a hydrogen-based reducing gas, resulting in a decrease in the reducing agent ratio, and operations are conducted in a way that reduces the amount of expensive coke charged, the thickness of the ore layer will increase compared to the thickness of the coke layer in the blast furnace. This raises concerns that the reduction gas concentration within the ore layer may decrease, leading to a significant decrease in furnace reaction efficiency and an increase in airflow resistance.

[0007] Herein, Patent Document 1 describes a method for injecting reducing agents into a blast furnace, characterized in that, when at least two types of reducing agents from solid reducing agents, liquid reducing agents, and gaseous reducing agents are injected into the blast furnace via lances provided through the blower pipe of the blast furnace, multiple lances are arranged in the same tuyer, different types of reducing agents are injected from each lance, and the lances are arranged so that the extensions of the injection directions of the multiple lances do not intersect with each other.

[0008] Furthermore, Patent Document 2 describes a blast furnace operation method in which a flammable reducing agent and a solid reducing agent are blown in from a tuyere via a lance, characterized in that the flammable reducing agent and the solid reducing agent are blown in with a double-pipe lance, the outlet flow velocity of the outer pipe of the double-pipe lance is set to 20 to 120 m / sec, and the oxygen excess rate of the air supplied to the tuyere is set to 0.7 to 1.3.

[0009] Furthermore, Patent Document 3 describes a device for adding hydrogen-containing raw materials into a blast furnace, wherein the end tip of the injection pipe for the hydrogen-containing raw material, which is partially inserted into a tuyere or blowpipe that supplies hot air into the furnace, has an end tip with an injection hole for the raw material, the end tip having a plurality of injection holes arranged in a vertical row at intervals in the vertical direction of the furnace, with the injection hole being approximately the center of the tuyere or blowpipe, each injection hole being equipped with a flow control valve, and the outer circumference of the portion of the injection pipe that is exposed into the tuyere or blowpipe has an insulating layer.

[0010] Japanese Patent No. 4997734, Japanese Patent Publication No. 2014-047390, Japanese Patent Publication No. 2012-521492

[0011] The invention described in Patent Document 1 is a reducing agent injection device for a blast furnace that injects pulverized coal using a lance-type device installed inside the tuyere. The inventions described in Patent Documents 2 and 3 do not assume the injection of gaseous reducing agent using a lance. Thus, the technologies disclosed in Patent Documents 1 to 3 involve installing a lance inside the tuyere to inject a reducing agent containing hydrogen-based reducing gas and pulverized coal. However, it has been found that the pulverized coal is difficult to disperse, and the gasification and combustion reactivity of the pulverized coal are reduced. Therefore, there was room to reduce the reducing agent ratio in the operation of the blast furnace. This disclosure has been made in view of the above circumstances, and the object of this disclosure is to provide a tuyere capable of reducing the reducing agent ratio, a blast furnace having the same, and a method for operating the blast furnace.

[0012] To solve the above problems, the present disclosure adopts the following configuration: (1) A blast furnace having a tuyere, wherein the tuyere comprises a tuyere body, a gaseous reducing agent injection lance, and a solid reducing agent injection lance, the tuyere body having a hot air passage, the gaseous reducing agent injection lance having an outlet in the hot air passage, and the solid reducing agent injection lance penetrating the tuyere body. (2) The blast furnace according to (1), wherein the outlet of the solid reducing agent injection lance is located at the tip of the tuyere. (3) A method for operating the blast furnace according to (1) or (2), wherein hot air is flowed through the hot air passage of the tuyere body, a gaseous reducing agent is blown out from the outlet of the gaseous reducing agent injection lance, and a solid reducing agent is blown out from the outlet of the solid reducing agent injection lance. (4) A tuyere used in a blast furnace, wherein the tuyere comprises a tuyere body, a gaseous reducing agent injection lance, and a solid reducing agent injection lance, wherein the tuyere body has a hot air passage, the gaseous reducing agent injection lance has an outlet within the hot air passage, and the solid reducing agent injection lance penetrates the tuyere body. (5) The tuyere according to (4), wherein the outlet of the solid reducing agent injection lance is located at the tip of the tuyere.

[0013] According to this disclosure, it is possible to provide a tuyeres, a blast furnace, and a method for operating the blast furnace that enable operation to further reduce the reducing agent ratio.

[0014] This is a schematic diagram of the blast furnace used in this embodiment. This is a cross-sectional view of a tuyere attached to the blast furnace used in this embodiment. This is a cross-sectional view of a modified example of the tuyere attached to the blast furnace used in this embodiment. This is a view of the tuyere in Figure 3, taken along the line IV-IV. This is a cross-sectional view of a tuyere attached to a blast furnace equipped with a conventional reducing agent injection lance. This is a diagram showing the evaluation results in the example.

[0015] In blast furnace operation, simply increasing the oxygen enrichment rate makes it difficult to simultaneously maintain the tuyere combustion temperature and the top gas temperature within the appropriate range. This is because the blast furnace process utilizes the exhaust gas (exhaust gas after the Sol-Roth reaction is completed in the lower furnace) after the heat balance in the lower furnace, where the reduction and thermal load are greatest, is established to establish the reduction and thermal balance in the upper furnace. In operation without injecting hydrogen-based reducing gas, the operation is performed with appropriate parameters so that the heat balance in the upper and lower furnaces is simultaneously satisfied. On the other hand, in operation with a large amount of hydrogen-based reducing gas injected into the blast furnace, the ore reduction rate becomes almost 100% at the fusion zone level, and the amount of molten reduction becomes almost zero, so the reduction and thermal load in the lower furnace is greatly reduced. Consequently, carbon consumption is reduced. However, when a large amount of hydrogen and pulverized coal are injected simultaneously, there is a concern that the gasification and combustion rate of pulverized coal will decrease because the reducing gas, which burns at a higher rate, burns preferentially over the pulverized coal.

[0016] The inventors of the present invention have conducted detailed studies on the technology of injecting hydrogen gas and pulverized coal into a blast furnace from a lance attached around the tuyeres. By reviewing the installation position of the injection device, they succeeded in finding a blast furnace capable of injecting pulverized coal in a dispersed manner. The following describes a blast furnace and its operating method that are embodiments of this disclosure. In this disclosure, "good dispersibility" of pulverized coal in the blast furnace means that the pulverized coal is spread out within the raceway. For example, it means that the distribution of pulverized coal is wide when the distribution of pulverized coal in the cross-section of the raceway is observed.

[0017] The blast furnace of this embodiment is a blast furnace having a tuyere, wherein the tuyere comprises a tuyere body, a gaseous reducing agent injection lance, and a solid reducing agent injection lance, the tuyere body having a hot air passage, the gaseous reducing agent injection lance having an outlet within the hot air passage, and the solid reducing agent injection lance penetrating the tuyere body. The solid reducing agent injection lance in this disclosure may be provided in the form of a port (through hole) in the tuyere body 6a. That is, the "lance" in this disclosure is a path through which the solid reducing agent flows, and may be in the form of a passage formed by creating a port in the tuyere body 6a.

[0018] Figure 1 shows a schematic diagram of the blast furnace 1 according to this embodiment. The blast furnace 1 in this embodiment is equipment for reducing iron ore and extracting molten pig iron. As shown in Figure 1, the core axis A, which is the central axis of the blast furnace 1, extends upward. The blast furnace 1 has a bottomed cylindrical shape centered on the core axis A. Although not specifically shown, iron-based raw materials and coke are charged into the blast furnace 1 alternately and in layers from the top 1a.

[0019] [Definition of Blast Furnace Direction] In this embodiment, the direction in which the core axis A extends (vertical direction), that is, the direction along the core axis A, is called the up-down direction. Of the up-down directions, the direction from the top 1a of the blast furnace 1 toward the bottom 1b is called the down-down direction, and the direction from the bottom 1b toward the top 1a is called the up-up direction.

[0020] Furthermore, the direction perpendicular to the core axis A is called the radial direction. Within the radial direction, the direction approaching the core axis A is called the inward radial direction, and the direction moving away from the core axis A is called the outward radial direction. Note that the direction moving inward in the radial direction is sometimes simply called the core direction. Also, the direction that circles around the core axis A is called the circumferential direction.

[0021] [Components of the blast furnace] The blast furnace 1 comprises a shaft section 2, a belly section 3, a Bosch section 4, and a hearth section 5. The shaft section 2, belly section 3, Bosch section 4, and hearth section 5 are arranged in this order from the top 1a of the furnace to the bottom 1b of the furnace.

[0022] The shaft section 2 has a tapered cylindrical shape that expands in diameter downwards. The shaft section 2 has a flared shape, with its diameter increasing downwards. The belly section 3 has a cylindrical shape that extends along the core axis A. The belly section 3 has a straight body shape, with its diameter remaining constant at each position in the vertical direction.

[0023] The Bosch section 4 has a tapered cylindrical shape that narrows in diameter downwards. The Bosch section 4 is tapered, with its diameter decreasing downwards. The hearth section 5 is located at the lower end of the blast furnace 1. The hearth section 5 is roughly cylindrical in shape. In the illustrated example, the inner diameter of the hearth section 5 decreases in stages downwards. The hearth section 5 is provided with a taphole (not shown). The pig iron produced in the blast furnace 1 is removed from the furnace through the taphole.

[0024] As shown in Figure 1, the blast furnace 1 is equipped with tuyeres 6 provided on the furnace wall of the hearth section 5. The blast furnace 1 is also equipped with a blower 10 and a hydrogen-based reducing gas supply system 25 connected to the tuyeres 6. The hydrogen-based reducing gas supply system 25 is equipped with a hydrogen-based reducing gas tank 30 and a heating device 31. Multiple tuyeres 6 are provided on the furnace wall of the hearth section 5 at intervals from each other in the circumferential direction of the furnace. In this embodiment, hot air supplied from the blower 10, an auxiliary reducing agent, and enriched oxygen gas, as well as hydrogen-based reducing gas supplied from the hydrogen-based reducing gas supply system 25, are blown into the furnace of the blast furnace 1 through the tuyeres 6. The hot air blown in through the tuyeres 6 reacts with the auxiliary reducing agent blown in through the tuyeres 6 and the coke in the furnace to generate high-temperature reducing gas (mainly CO gas in this case). That is, the hot air gasifies the coke and the auxiliary reducing agent. Examples of auxiliary reducing agents include pulverized coal, waste plastics, heavy oil, and propane gas. Note that auxiliary reducing agents may not be blown into the furnace. Although not specifically shown in the diagram, a cavity (combustion space) called a raceway (RW) is formed in front of the tuyeres 6 by the hot air blown in from the tuyeres 6.

[0025] Hydrogen-based reducing gases are gases that contain 30 mol% or more of H as an elemental component and exist as gases under standard conditions (0°C, 1 atm). For example, H ２Gas, unsaturated hydrocarbon gas (C ２ H ４ , C ２ H ２ , C ３ H ６ etc.), saturated hydrocarbon gas (CH ４ , C ２ H ６ , etc.), NH ３ gas, coke oven gas, city gas, natural gas, etc., and mixed gases thereof. The hydrogen-based reducing gas is particularly preferably H ２ gas, unsaturated hydrocarbon gas (C ２ H ４ , C ２ H ２ , C ３ H ６ etc.). H ２ gas does not contain carbon and does not cause a thermal decomposition reaction at the tuyere tip, so it is preferable from the viewpoint of reducing the unit consumption of carbon. Further, H ２ gas is preferable also from the viewpoint of air permeability in a blast furnace because the gas has low viscosity and density. Unsaturated hydrocarbon gas is preferable because it contains double bonds or triple bonds in gas molecules, so the combustion heat per 1 mol of oxygen is relatively large, and the unsaturated hydrocarbon gas serves as a heat source at the tuyere tip. It is more preferable that the elemental composition ratio of H in the hydrogen-based reducing gas is 50 mol% or more. Further, the hydrogen-based reducing gas may be a mixed gas with other gases (not impairing the effects of the present embodiment), such as N ２ gas). It is preferable that the hydrogen-based reducing gas is heated before being blown into the blast furnace 1. It is preferable that the hydrogen-based reducing gas is heated to, for example, 900°C or higher before being blown into the blast furnace 1. Therefore, the blast furnace 1 may be provided with a heating device 31 that heats the hydrogen-based reducing gas. The type of the heating device 31 is not particularly limited, and may be, for example, an electric heater or the like.

[0026] The hydrogen-based reducing gas and the generated reducing gas rise in the furnace and reduce the iron-based raw material and coke while heating them. While the iron-based raw material descends in the furnace, it is heated and reduced by the hydrogen-based reducing gas and the generated reducing gas. Thereafter, the iron-based raw material melts and drips down in the furnace while being further reduced by coke. The iron-based raw material is finally accumulated in the hearth portion 5 as molten pig iron (pig iron) containing, for example, slightly less than 5% by mass of carbon. The molten pig iron in the hearth portion 5 is taken out from the tap hole and supplied to the next steelmaking process.

[0027] In this case, not only the reducing gas generated by blowing the auxiliary reducing agent promotes the reduction of the iron-based raw material, but also the blowing of the hydrogen-based reducing gas promotes the reduction of the iron-based raw material. Therefore, the coke ratio (mass of coke required to produce 1 ton of molten pig iron) and the auxiliary reducing agent ratio (mass of auxiliary reducing agent required to produce 1 ton of molten pig iron, which is referred to as the pulverized coal ratio when the auxiliary reducing agent is pulverized coal) can be reduced, and the carbon consumption in the blast furnace 1 can be reduced.

[0028] <Structure of Tuyere 6> Next, the structure of the tuyere 6 used in the blast furnace 1 according to the present embodiment will be described. FIG. 2 is an enlarged cross-sectional view of the periphery of the tuyere 6 in FIG. 1. As shown in FIG. 2, the tuyere 6 includes a tuyere body 6a, a gaseous reducing agent injection lance 11, and a solid reducing agent injection lance 17. The tuyere body 6a has a hot air flow path 20. The gaseous reducing agent injection lance 11 is attached inside the hot air flow path 20. An injection port 11a of the gaseous reducing agent injection lance 11 is located inside the hot air flow path 20 of the tuyere body 6a. In the present specification, the end of the tuyere body 6a in the core direction in the tuyere 6 may be described and explained as the tip 6c of the tuyere body (or simply "tuyere tip").

[0029] Examples of gaseous reducing agents include hydrogen-based reducing gases. The solid reducing agent injection lance 17 penetrates the tuyere body 6a. The outlet 17a of the solid reducing agent injection lance 17 is connected to the hot air passage 20 of the tuyere body 6a. Examples of solid reducing agents include coke, pulverized coal, biomass, and waste plastics. The solid reducing agent is not particularly limited, but since it is injected into the blast furnace from the lance, it is preferable that the particle size is less than 1 mm. Furthermore, it is preferable to inject an inert gas containing nitrogen as a carrier gas for the solid reducing agent. The lance diameter of the solid reducing agent injection lance 17 is smaller than the lance diameter of the gaseous reducing agent injection lance 11. Specifically, the lance diameter R of the gaseous reducing agent injection lance 11 ｇａｓ R of the lance diameter of the solid reducing agent blowing lance 17 ｓｏｌｉｄ Relationship (R ｓｏｌｉｄ / R ｇａｓ Preferably, the ratio is 0.5 or less. In Figure 2, the solid reducing agent injection lance 17 is shown to be installed above the gas reducing agent injection lance 11, but it is sufficient that the outlet 17a of the solid reducing agent injection lance 17 is directed toward the central axis of the hot air flow path 20, and the solid reducing agent injection lance 17 may be installed at any position along the circumferential direction of the hot air flow path 20.

[0030] Note that, FIG. 5 shows a mode where an auxiliary reducing agent containing pulverized coal and a hydrogen-based reducing gas according to a prior art are blown into a blast furnace by a lance installed in a tuyere. In the prior art as shown in FIG. 5, the hydrogen-based reducing gas and pulverized coal are not mixed, and the pulverized coal is attracted into a high-speed hydrogen-based reducing gas flow, which makes it difficult for the pulverized coal to disperse in the raceway (RW).

[0031] In the present embodiment, a distance between an outlet 11a of a gas reducing agent blowing lance 11 and an outlet 17a of a solid reducing agent blowing lance 17 can be secured. This distance is larger than that in the prior art where the outlet 11a of the gas reducing agent blowing lance 11 and the outlet 17a of the solid reducing agent blowing lance 17 are both provided in the tuyere. Since the outlet 17a of the solid reducing agent blowing lance 17 is spaced apart from the outlet 11a of the gas reducing agent blowing lance 11, the effect that the pulverized coal blown from the solid reducing agent blowing lance 17 is attracted into the hydrogen-based reducing gas flow blown from the gas reducing agent blowing lance 11 is suppressed, so that hot air and the pulverized coal flow are easily mixed. Therefore, the pulverized coal is easily dispersed in the raceway, and the combustion rate of the pulverized coal can be increased.

[0032] (Modified Example of Tuyere 6) Next, a modified example will be described. FIG. 3 and FIG. 4 are a cross-sectional view and a view along arrow IV-IV, respectively, showing a modified example of the tuyere 6 attached to the blast furnace 1 according to the present embodiment. The modified example of the blast furnace 1 according to the present embodiment is a blast furnace 1 having a tuyere 6, wherein the tuyere 6 includes a tuyere main body 6a, a gas reducing agent blowing lance 11, and a solid reducing agent blowing lance 17, the tuyere 6 main body has a hot air flow path 20, the gas reducing agent blowing lance 11 has an outlet 11a in the hot air flow path 20, the solid reducing agent blowing lance 17 passes through the tuyere main body 6a, and the outlet 17a of the solid reducing agent blowing lance 17 is located at a tip 6c of the tuyere main body.In this embodiment, the tuyeres 6 has a configuration in which the outlet 17a of the solid reducing agent injection lance 17 is located at the tip 6c of the tuyeres body. That is, the pulverized coal blown out from the solid reducing agent injection lance 17 does not pass through the hot air passage 20 inside the tuyeres body 6a. With this configuration, the distance between the outlet 17a of the solid reducing agent injection lance 17 and the outlet 11a of the gaseous reducing agent injection lance 11 is increased, further mitigating the attraction of pulverized coal into the high-speed hydrogen-based reducing gas flow, and making it easier for the pulverized coal blown in from the solid reducing agent injection lance 17 to mix with the hot air. As a result, the pulverized coal is more easily dispersed within the RW, and the pulverized coal combustion rate is further improved. In addition, the pulverized coal does not come into contact with the inner wall 6b of the tuyeres body, making this a more preferable installation position for the solid reducing agent injection lance 17. For the reasons stated above, it is preferable that the outlet 11a of the gaseous reducing agent injection lance 11 and the outlet 17a of the solid reducing agent injection lance 17 are separated by 50 mm or more.

[0033] As described above, according to the tuyeres and blast furnaces of this embodiment, the installation position of the solid reducing agent injection lance 17 in the tuyeres 6 located at the bottom of the blast furnace 1 facilitates mixing of pulverized coal and hydrogen-based reducing gas injected into the blast furnace 1, making it easier for the pulverized coal to disperse within the RW. This improves the reactivity of gasification and combustion of pulverized coal within the blast furnace, improves the permeability and heat transfer properties of the reducing gas within the blast furnace, and enables more stable operation.

[0034] The present disclosure will be specifically described below with reference to examples. The effect of the tuyeres 6 attached to the blast furnace 1 according to this embodiment on the combustion rate of pulverized coal was evaluated by simulation. The calculation conditions are as shown in Table 1. Nitrogen gas was used as the carrier gas for the pulverized coal, and pure hydrogen gas was used as the hydrogen-based reducing gas. The injection temperature of the hydrogen-based reducing gas was set to 1000°C.

[0035]

[0036] The combustion rate of pulverized coal using the following injection methods was simulated under the calculation conditions shown in Table 1. The simulation results are shown in Figure 6. ・Pulverized coal lance (inside the hot air flow path): A conventional pulverized coal injection method (comparative example) where the pulverized coal injection lance and the gaseous reducing agent injection lance are located inside the hot air flow path, as shown in Figure 5. ・Pulverized coal lance (inside the tuyere): A method (Example 1) where pulverized coal is injected from inside the tuyere using a tuyere with a lance that penetrates the tuyere and where the outlet of the solid reducing agent injection lance is located in the hot air flow path, as shown in Figure 2. ・Pulverized coal lance (tip of the tuyere body): A method (Example 2) where pulverized coal is injected into the tip of the tuyere using a tuyere with a lance that penetrates the tuyere and where the outlet of the solid reducing agent injection lance is located at the tip of the tuyere body, as shown in Figures 3 and 4.

[0037] In Figure 6, the dispersibility of pulverized coal within the RW was evaluated by observing the distribution of pulverized coal passing through the cross-section of the RW. Figure 6 shows the distribution of pulverized coal passing through the cross-section of the central part of the RW, as confirmed by simulation. In this embodiment, the distribution of pulverized coal was evaluated in a cross-section perpendicular to the direction of airflow blown in from the tuyere, 500 mm from the tip of the tuyere, as the central part of the RW. In conventional pulverized coal lance-type blowing, it is thought that the pulverized coal was blown in near the high-speed hydrogen flow, and the pulverized coal was attracted to the high-speed hydrogen flow, resulting in poor dispersibility. Therefore, pulverized coal and O ２ CO ２ , H ２In the first example, the low frequency of contact with gasifying agents such as oxygen (O) made the gasification reaction less likely to proceed, resulting in a low fuel content for pulverized coal. On the other hand, as shown in Figure 6, in the pulverized coal lance type (inside the tuyeres) of Example 1, the dispersibility of pulverized coal was improved, and the distribution of pulverized coal was wider compared to the comparative example lance type. As a result, it is estimated that the gasification and combustion rate of pulverized coal improved by 2%. Furthermore, in the pulverized coal lance type (tip of the tuyeres body) of Example 2, the pulverized coal was blown in from an even greater distance from the high-speed hydrogen stream than in Example 1, resulting in improved dispersibility and an 8% improvement in the gasification and combustion rate of pulverized coal compared to the conventional lance type blowing method used in the comparative example. From these findings, it can be concluded that the blast furnace operation method according to this embodiment allows for easier reaction in the furnace and enables a reduction in the reducing agent ratio compared to the conventional pulverized coal lance blowing method used in the comparative example.

[0038] While preferred embodiments of the present disclosure have been described in detail above with reference to the attached drawings, the present disclosure is not limited to such examples. It is clear to any person with ordinary skill in the art to which the present disclosure pertains that various modifications or alterations may be conceived within the scope of the technical idea set forth in the claims, and these will naturally also be understood to fall within the technical scope of the present disclosure.

[0039] 1 Blast furnace 1a Furnace top 1b Furnace bottom 2 Shaft section 3 Belly section 4 Bosch section 5 Hearth section 6 Tuyere 6a Tuyere body 6b Inner wall of tuyere body 6c Tip of tuyere body 8 Tuyere opening 10 Blower 11 Gas reducing agent blowing lance 11a Outlet 17 Solid reducing agent blowing lance 17a Outlet 20 Hot air flow path 25 Hydrogen-based reducing gas supply system 30 Hydrogen-based reducing gas tank 31 Heating device S Center of tuyere opening

Claims

1. A blast furnace having a tuyere, wherein the tuyere comprises a tuyere body, a gas reducing agent injection lance, and a solid reducing agent injection lance, the tuyere body having a hot air passage, the gas reducing agent injection lance having an outlet within the hot air passage, and the solid reducing agent injection lance penetrating the tuyere body.

2. The blast furnace according to claim 1, wherein the outlet of the solid reducing agent injection lance is located at the tip of the tuyere.

3. A method for operating a blast furnace according to claim 1 or 2, wherein hot air is flowed through the hot air passage of the tuyere body, a gaseous reducing agent is blown out from the outlet of the gaseous reducing agent injection lance, and a solid reducing agent is blown out from the outlet of the solid reducing agent injection lance.

4. A tuyere for use in a blast furnace, wherein the tuyere comprises a tuyere body, a gas reducing agent injection lance, and a solid reducing agent injection lance, the tuyere body having a hot air passage, the gas reducing agent injection lance having an outlet within the hot air passage, and the solid reducing agent injection lance penetrating the tuyere body.

5. The tuyere according to claim 4, wherein the outlet of the solid reducing agent blowing lance is located at the tip of the tuyere body.

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