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

Abstract

Disclosed is a method by which it is possible to suppress drift of a reducing gas when a reducing gas having a low specific gravity is blown into the interior of a blast furnace.　A method for blowing a reducing gas into a blast furnace according to the present disclosure comprises: blowing hot air into the interior of the blast furnace from a hot air tuyere provided below the lower end of the shaft of the blast furnace and above a tap hole; and blowing the reducing gas into the interior of the blast furnace through a reducing gas blowing lance that is provided in the wall surface of the hot air tuyere and that has an opening at the tip end of the hot air tuyere. The reducing gas functions as a reducing material in the interior of the blast furnace, and the specific gravity of the reducing gas is lower than the specific gravity of the hot air. The height position P1 of the center of the opening of the reducing gas blowing lance is the same as the height position P2 of the center of the hot air tuyere, or is below the height position P2.

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, it may be possible to use a reducing gas such as hydrogen gas instead 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 hot air flow path or the wall surface of the hot air tuyere, and the reducing gas is injected through the lance. Although not assuming the injection of reducing gas, Patent Document 2 discloses a method in which a fuel injection lance is inserted into the wall surface of the hot air tuyere, and pulverized coal as a fuel is blown into the blast furnace through the fuel injection lance.

Prior Art Documents

[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 blowing reducing gas into the blast furnace via a reducing gas injection lance, which is provided within the wall surface of the hot air tuyere and has an opening at the tip of the hot air tuyere. The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air. The height position P1 of the center of the opening of the reducing gas blowing lance is the same as the height position P2 of the center of the hot air nozzle, or is located below the height position P2. Method for injecting reducing gas into a blast furnace. <Aspect 2> A method for injecting reducing gas into a blast furnace according to Embodiment 1, The aforementioned height position P1 is located below the aforementioned height position P2. Method for injecting reducing gas into a blast furnace. <Aspect 3> A method for injecting reducing gas into a blast furnace according to embodiment 1 or 2, The reducing gas includes hydrogen gas. Method for injecting reducing gas into a blast furnace. <Aspect 4> 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 blowing lance is provided within the wall surface of the hot air nozzle and has an opening at the tip of the hot air nozzle, It has, The reducing gas blown into the blast furnace from the reducing gas injection lance is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air blown into the blast furnace from the hot air tuyeres. The height position P1 of the center of the opening of the reducing gas blowing lance is the same as the height position P2 of the center of the hot air nozzle, or is located below the height position P2. Blast furnace. <Aspect 5> A blast furnace according to embodiment 4, The aforementioned height position P1 is located below the aforementioned height position P2. Blast furnace. <Aspect 6> A blast furnace according to embodiment 4 or 5, The reducing gas includes hydrogen gas. Blast furnace. [Effects of the Invention]

[0006] According to the technology of this disclosure, when a reducing gas with a low specific gravity is injected into the interior of a blast furnace via a reducing gas injection lance, thermal damage to the reducing gas injection lance can be suppressed, and uneven flow of the reducing gas can be suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] This diagram provides a schematic example of a blast furnace configuration. Some components of the blast furnace are omitted from the diagram. [Figure 2] Another schematic example of the configuration of the lance tip at the tip of a hot air tuyer is shown. [Figure 3A]An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is schematically shown. [Figure 3B] An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is schematically shown. [Figure 3C] An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is schematically shown. [Figure 4] Schematically shows the positional relationship between the hot blast tuyere and the lance opening for each of the prior example, Examples 1 to 3, and Comparative Examples [1 to 2].

Embodiments for Carrying Out the Invention

[0008] 7 Hereinafter, a method for injecting reducing gas into a blast furnace and an embodiment of a blast furnace according to the present disclosure will be described. However, the method for injecting reducing gas into a blast furnace and the blast furnace according to the present disclosure are not limited to the following embodiments.

[0009] 1. Method for Injecting Reducing Gas into a Blast Furnace As shown in FIG. 1, a method for injecting reducing gas into a blast furnace 10 according to an embodiment includes blowing hot blast into the interior of the blast furnace 10 from a hot blast tuyere 13 provided below the lower end 11ax of the shaft of the blast furnace 10 and above the tapping spout 12, and injecting reducing gas into the interior of the blast furnace 10 from a reducing gas injection lance 14 provided in the wall surface of the hot blast tuyere 13 and having an opening 14a at the tip 13a of the hot blast tuyere 13. The reducing gas is a gas that functions as a reducing agent inside the blast furnace 10. The specific gravity of the reducing gas is smaller than the specific gravity of the hot blast. The height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is the same as the height position P2 of the center of the hot blast tuyere 13 or exists below the height position P2.

[0010] 1.1 Hot Blast Tuyere The blast furnace 10 has hot air tuyeres 13 located below the lower end of the shaft 11ax and above the tapping port 12. The "lower end of the shaft" refers to the boundary between the shaft 11a and the furnace belly (belly) 11b. The "shaft" refers to the part above the furnace belly 11b, where the furnace diameter usually increases from top to bottom. The "furnace" refers to the part below the shaft and above the bellows (bosch) 11c, where the furnace diameter is usually the largest. The furnace diameter (diameter) of the furnace belly 11b may be, for example, 5m to 20m, or 10m to 18m. The "tapping port" refers to the molten iron tapping port located at the bottom of the blast furnace 10. The "hot air tuyeres" refer to nozzles for blowing hot air into the blast furnace. The blast furnace 10 may have hot air tuyeres 13 located below the lower end 11bx of the furnace belly and above the taphole 12, or it may have hot air tuyeres 13 located below the lower end 11cx of the bellows and above the taphole 12.

[0011] The configuration of the hot air tuyere 13 is well known. For example, the hot air tuyere 13 may have a water-cooled structure. The hot air tuyere 13 may be connected to a hot air furnace outside the blast furnace 10 via a hot air pipe or the like. In other words, the blast furnace 10 may be configured so that hot air is blown into the interior of the blast furnace 10 from the hot air furnace via the hot air pipe and the hot air tuyere 13. The diameter of the hot air tuyere 13 (the diameter 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 air 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. Multiple hot air tuyeres 13 may be arranged in the circumferential direction of the blast furnace 10. In other words, in the blast furnace 10, multiple hot air tuyeres 13 may be arranged in the circumferential direction when viewed from above. Typically, the height position P2 of the center of each of the multiple hot air tuyeres 13 is the same.

[0013] 1.2 Reducing gas injection lance The blast furnace 10 has a reducing gas injection lance 14. The reducing gas injection lance 14 may 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 may 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 a reducing gas injection lance 14. There are no particular restrictions on the form of the reducing gas supply source or the reducing gas supply channel.

[0014] In this embodiment, it is important that the reducing gas injection lance 14 is provided within the wall surface of the hot air tuyere 13. The phrase "reducing gas injection lance provided within the wall surface of the hot air tuyere" does not mean that the lance is embedded within the wall surface of the hot air tuyere all the way to the tip of the lance, as shown in Figure 1. For example, as shown in Figure 2, it also includes configurations in which at least a part of the lance is in contact with the inside of the wall surface of the hot air tuyere while being exposed within the flow path of the hot air tuyere. That is, as long as the reducing gas injection lance can be cooled by the water cooling structure inside the hot air tuyere (as long as thermal damage to the lance can be suppressed), at least a part of the circumference of the lance may be exposed within the flow path of the hot air tuyere, such as when at least a part of the entire circumference of the lance is located inside the wall surface of the hot air tuyere. From the viewpoint of further suppressing thermal damage to the reducing gas injection lance, it is preferable that the entire circumference of the reducing gas injection lance is provided within the wall surface of the hot air tuyere. Furthermore, in this embodiment, the reducing gas injection lance 14 has an opening 14a at the tip 13a of the hot air tuyere 13, and is configured to inject reducing gas into the blast furnace 10 from the opening 14a. "Reducing gas injection lance having an opening at the tip of the hot air tuyere" means that the reducing gas injection lance has an opening at or near the tip of the hot air tuyere. In this embodiment, it is not necessary for the tip surface of the hot air tuyere and the lance opening to be flush (the tip of the lance does not reach the tip of the hot air tuyere). That is, "having an opening at the tip of the hot air tuyere" includes not only the form in which the tip surface of the hot air tuyere and the lance opening are flush (the tip of the lance reaches the tip of the hot air tuyere), but also the form in which the tip of the lance reaches near the tip of the hot air tuyere. Specifically, if the distance from the tip of the lance to the tip of the hot air tuyere is 0 mm or more and 50 mm or less, the lance is considered to "have an opening at the tip of the hot air tuyere". Thus, in this embodiment, since the reducing gas injection lance 14 is provided within the wall surface of the hot air tuyere 13, the reducing gas injection lance 14 is less likely to be exposed to hot air. Furthermore, even if it is exposed to hot air, the reducing gas injection lance 14 can be cooled by the water cooling structure within the wall surface of the hot air tuyere 13, thereby suppressing thermal damage to the reducing gas injection lance 14.

[0015] The diameter of the opening 14a of the reducing gas injection lance 14 (the circular diameter of the opening facing the inside of the blast furnace 10) may be, for example, 10 mm or more and 50 mm or less, or 20 mm or more and 30 mm or less. Alternatively, the diameter of the opening 14a of the reducing gas injection lance 14 may be 0.05% or more and 0.8% or less, or 0.1% or more and 0.5% or less, of the diameter of the hot air tuyere 13.

[0016] The number of reducing gas injection lances 14 provided in the blast furnace 10 is not particularly limited. For example, at least one reducing gas injection lance 14 may be provided in at least one hot blast tuyere 13 provided in the blast furnace 10. In other words, if the blast furnace 10 has multiple hot blast tuyeres 13, only some of the multiple hot blast tuyeres 13 may have reducing gas injection lances 14, or all of them may have reducing gas injection lances 14. Also, one reducing gas injection lance 14 may be provided for one hot blast tuyere 13, or multiple reducing gas injection lances 14 may be provided. The height positions P1 of the centers of each opening 14a of the multiple reducing gas injection lances 14 may be the same or different from each other.

[0017] 1.3 Positional relationship between the hot air nozzle and the opening of the reducing gas blowing lance In this embodiment, it is important that the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is the same as the height position P2 of the center of the hot air tuyere 13, or is located below the height position P2. According to our new findings, if the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is located above the height position P2 of the center of the hot air tuyere 13, the reducing gas injected from the reducing gas injection lance 14 tends to rise along the wall surface of the blast furnace 10, causing uneven flow of the reducing gas inside the blast furnace 10. In contrast, if the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is the same as the height position P2 of the center of the hot air tuyere 13, or is located below the height position P2, the amount of reducing gas flowing below the hot air inside the blast furnace 10 increases, and the amount of reducing gas rising along the wall surface decreases, making it easier for the reducing gas to reach the radial center (furnace center) inside the blast furnace 10. As a result, the uneven flow of reducing gas inside the blast furnace 10 is suppressed, and the utilization efficiency of the reducing gas is improved. In particular, the effect of suppressing the uneven flow of reducing gas becomes even more pronounced when the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is lower than the height position P2 of the center of the hot air tuyere 13.

[0018] Figures 3A and 3B show an example where the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is lower than the height position P2 of the center of the hot air tuyere 13. As shown in Figure 3A, the center of the opening 14a of the reducing gas injection lance 14 may be located directly below the center of the hot air tuyere 13. That is, the position of the center of the opening 14a of the reducing gas injection lance 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 3B, the center of the opening 14a of the reducing gas injection lance 14 may be located diagonally below the center of the hot air tuyere 13. That is, in the circumferential direction of the blast furnace 10, the center of the opening 14a of the reducing gas injection lance 14 may be located at a different position from the center of the hot air tuyere 13.

[0019] Figure 3C shows the case where the height position P1 of the center of the opening 14a of the reducing gas blowing lance 14 is the same as the height position P2 of the center of the hot air tuyere 13. As shown in Figure 3C, the opening 14a of the reducing gas blowing lance 14 may be provided next to the hot air tuyere 13.

[0020] 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.

[0021] 1.5 Reducing gas The reducing gas injected from the reducing gas injection lance 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 the like, it is included in the term "reducing gas" as used in this application. Furthermore, the specific gravity of the reducing gas is less than the specific gravity of the hot air injected into the blast furnace 10 from the hot air tuyere 13. Examples of such reducing gases include at least one selected from hydrogen gas, hydrocarbon gas (e.g., methane gas), carbon monoxide gas, and ammonia gas. In particular, when the reducing gas includes hydrogen gas, an even greater effect can be expected from the technology of this disclosure. The temperature of the reducing gas injected from the reducing gas injection lance 14 may be, for example, 0°C to 2000°C or 25°C to 1500°C. In this embodiment, the flow velocity (flow rate (m) of the reducing gas at the opening 14a of the reducing gas injection lance 14 3 / s) / Opening area of ​​the outlet of the reducing gas blowing lance 14 (m2 )) may, for example, be less than or equal to the speed of sound at the operating temperature of each reducing gas. In one embodiment, the flow velocity of the reducing gas blown in from the reducing gas blowing lance 14 may be the flow velocity V2 described later.

[0022] 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 100 m / s or more and 1000 m / s or less, and more particularly 200 m / s or more and 400 m / s or less, the uneven flow of reducing gas inside the blast furnace 10 is more easily suppressed. Also, the flow velocity V2 of the reducing gas blown in from the reducing gas injection lance 14 is not particularly limited, but for example, if the flow velocity V2 is 100 m / s or more and 1000 m / s or less, and more particularly 200 m / s or more and 800 m / s or less, the ventilation inside the blast furnace 10 is stabilized, and the in-furnace reduction reaction proceeds stably.

[0023] 1.7 Other Gases Other gases may be blown in along with the reducing gas from the reducing gas injection lance 14. Examples of other gases include inert gases such as nitrogen gas.

[0024] 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 system includes a reducing gas blowing lance 14 provided within the wall surface of the hot air tuyere 13 and having an opening 14a at the tip portion 13a of the hot air tuyere 13. The reducing gas blown into the blast furnace 10 from the reducing gas injection lance 14 is a gas that functions as a reducing agent inside the blast furnace 10. The specific gravity of the reducing gas is less than the specific gravity of the hot air blown into the blast furnace 10 from the hot air tuyeres 13. The height position P1 of the center of the opening 14a of the reducing gas blowing lance 14 is the same as the height position P2 of the center of the hot air nozzle 13, or is located below the height position P2.

[0025] As described above, in the blast furnace 10, the effect of suppressing the uneven flow of reducing gas is considered to be further enhanced when the height position P1 is located below the height position P2. Furthermore, the effect of the technology of this disclosure is considered to be further enhanced when the reducing gas contains hydrogen gas.

[0026] 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 a hot blast pipe and hot blast tuyeres 13, and reducing gas is blown into the blast furnace 10 from a reducing gas supply source outside the blast furnace 10 via a reducing gas flow path and reducing gas injection lance 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 injected from the reducing gas injection lance 14, to obtain molten iron. The molten iron is discharged from a tap port 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 injection lance 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 lances in addition to the hot air tuyeres 13 and reducing gas injection lances 14 described above. Also, in the blast furnace 10, other reducing gas injection lances may be located above the hot air tuyeres 13. As the configuration of the blast furnace 10 other than the hot air tuyeres 13 and reducing gas injection lances 14 is known in the art, a detailed explanation is omitted here.

[0027] 4. Effects As described above, according to this embodiment, the reducing gas injection lance 14 is provided within the wall surface of the hot air tuyere 13, thereby suppressing thermal damage to the lance. Furthermore, according to this embodiment, the height position P1 of the center of the opening 14a of the reducing gas injection lance 14 is the same as, or lower than, the height position P2 of the center of the hot air tuyere 13, thereby suppressing uneven flow of reducing gas inside the blast furnace 10. [Examples]

[0028] 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.

[0029] Using a simulation model, the hydrogen concentration difference between the furnace wall at the top surface of the blast furnace interior container and the center of the furnace was compared while changing the injection position of the reducing gas. Specifically, the hydrogen concentration difference was determined for each of the following prior examples, Examples 1-3, and Comparative Examples 1-2.

[0030] Prior Example: As shown in "Prior Example" in Figure 4, the lance was inserted into the hot air flow path (outside the wall surface) of the hot air tuyere so that the center of the opening at the tip of the lance was located at the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0031] Example 1: As shown in "Example 1" in Figure 4, the lance was inserted into the wall of the hot air tuyere so that the center of the opening at the tip of the lance was located directly below the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0032] Example 2: As shown in "Example 2" of Figure 4, the lance was inserted into the wall of the hot air tuyere so that the center of the opening at the tip of the lance was located diagonally below the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0033] Example 3: As shown in "Example 3" in Figure 4, the lance was inserted into the wall of the hot air tuyere so that the height of the center of the opening at the tip of the lance was the same as the height of the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0034] Comparative Example 1: As shown in "Comparative Example 1" in Figure 4, the lance was inserted into the wall of the hot air tuyere so that the center of the opening at the tip of the lance was positioned diagonally above the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0035] Comparative Example 2: As shown in "Comparative Example 2" in Figure 4, the lance was inserted into the wall of the hot air tuyere so that the center of the opening at the tip of the lance was positioned directly above the center of the opening of the hot air tuyere. Hot air was blown in from the hot air tuyere, and hydrogen gas was blown in from the lance.

[0036] The results are shown in Table 1 below.

[0037] [Table 1]

[0038] As is clear from the results shown in Table 1, when the height of the center of the opening of the reducing gas injection lance is the same as or lower than the height of the center of the hot air tuyere, as in the prior example and Examples 1-3, there was almost no difference in hydrogen concentration at the uppermost surface of the blast furnace interior container. This is thought to be because the hydrogen gas and hot air were sufficiently mixed at the tuyere level, and the hydrogen was dispersed together with the hot air in the furnace. However, as in the prior example, when the tip of the reducing gas injection lance is not in contact with the wall surface of the hot air tuyere, and the entire circumference of the lance is exposed within the flow path of the hot air tuyere, the lance is prone to thermal damage from the hot air. In this respect, the prior example has issues regarding the durability of the lance. In contrast, as in Examples 1-3, this issue can be solved by arranging the reducing gas injection lance inside the wall surface of the hot air tuyere (at least a part of the entire circumference of the lance is positioned inside the wall surface of the hot air tuyere). In other words, from the viewpoint of achieving both suppression of uneven flow of reducing gas and suppression of thermal damage to the lance, Examples 1-3 are more advantageous than the prior example.

[0039] On the other hand, as in Comparative Examples 1 and 2, when the height of the center of the opening of the reducing gas injection lance was higher than the height of the center of the hot air tuyeres, a large difference in hydrogen concentration was observed between the furnace center and the furnace wall at the uppermost surface of the blast furnace interior container. This is thought to be because the specific gravity of hydrogen gas is lower than that of air (hot air), and the hydrogen gas was not pushed by the hot air blown in from the hot air tuyeres, but rather flowed preferentially along the furnace wall.

[0040] From the above, it can be said that by installing a reducing gas injection lance inside the wall of the hot air tuyere, thermal damage to the lance can be suppressed. Furthermore, when a reducing gas injection lance is installed inside the wall of the hot air tuyere, and the opening of the lance is positioned at the tip of the hot air tuyere, and reducing gas is injected from the lance, it can be said that uneven flow of reducing gas inside the blast furnace can be suppressed if the height position P1 of the center of the lance opening is the same as the height position P2 of the center of the hot air tuyere, or is lower than height position P2.

[0041] In summary, the following methods (1) and blast furnace (2) can suppress thermal damage to the reducing gas injection lance and reduce the flow of the reducing gas when injecting a reducing gas with a low specific gravity into the blast furnace.

[0042] (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 blowing reducing gas into the blast furnace via a reducing gas injection lance, which is provided within the wall surface of the hot air tuyere and has an opening at the tip of the hot air tuyere. The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air. The height position P1 of the center of the opening of the reducing gas blowing lance is the same as the height position P2 of the center of the hot air nozzle, or is located below the height position P2. Method for injecting reducing gas into a blast furnace.

[0043] (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 blowing lance is provided within the wall surface of the hot air nozzle and has an opening at the tip of the hot air nozzle, It has, The reducing gas blown into the blast furnace from the reducing gas injection lance is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air blown into the blast furnace from the hot air tuyeres. The height position P1 of the center of the opening of the reducing gas blowing lance is the same as the height position P2 of the center of the hot air nozzle, or is located below the height position P2. Blast furnace. [Explanation of Symbols]

[0044] 10 blast furnace 11 Hearth belly 12 Taphead 13 Hot air nozzle 13a Tip 14. Reducing gas injection lance 14a aperture

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 blowing reducing gas into the blast furnace via a reducing gas injection lance, which is provided within the wall surface of the hot air tuyere and has an opening at the tip of the hot air tuyere. The distance from the tip of the reducing gas blowing lance to the tip of the hot air nozzle is 0 mm or more and 50 mm or less. The reducing gas is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air. The height position P of the center of the opening of the reduction gas blowing lance. １ However, the height position P of the center of the hot air nozzle ２ It is the same as, or the height position P. ２ Located below, Method for injecting reducing gas into a blast furnace.

2. A method for injecting reducing gas into a blast furnace according to claim 1, The height position P １ However, the aforementioned height position P ２ Located below, Method for injecting reducing gas into a blast furnace.

3. A method for injecting reducing gas into a blast furnace according to claim 1 or 2, The reducing gas includes hydrogen gas. Method for injecting reducing gas into a blast furnace.

4. A blast furnace, A hot air tuyeres are provided below the furnace wall of the blast furnace and above the taphole, A reducing gas blowing lance is provided within the wall surface of the hot air nozzle and has an opening at the tip of the hot air nozzle, It has, The distance from the tip of the reducing gas blowing lance to the tip of the hot air nozzle is 0 mm or more and 50 mm or less. The reducing gas blown into the blast furnace from the reducing gas injection lance is a gas that functions as a reducing agent inside the blast furnace. The specific gravity of the reducing gas is less than the specific gravity of the hot air blown into the blast furnace from the hot air tuyeres. The height position P of the center of the opening of the reduction gas blowing lance. １ However, the height position P of the center of the hot air nozzle ２ It is the same as, or the height position P. ２ Located below, Blast furnace.

5. A blast furnace according to claim 4, the height position P １ is located below the height position P ２ and exists below the height position P Blast furnace.

6. A blast furnace according to claim 4 or 5, The reducing gas includes hydrogen gas. Blast furnace.

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