Method for blowing reducing gas into 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

Method for injecting reducing gas into blast furnace and blast furnace

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

[0002] CO in the steelmaking process ２ Reducing emissions has been studied. For example, when producing pig iron in a blast furnace, a reducing gas such as hydrogen gas may be used in place of a portion of the reducing material, such as coke. 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 disposed in the hot blast flow path or wall surface of a hot blast tuyere, and reducing gas is injected through the lance. Although not intended 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.

[0003] Patent No. 4997734 Patent No. 5840202

[0004] When a lance is disposed in the flow path of a hot blast tuyere as disclosed in Patent Document 1, the lance is exposed to hot blast, raising concerns about thermal damage to the lance. Furthermore, when a reducing gas with a low specific gravity is injected into a blast furnace through a reducing gas injection lance provided in the hot blast tuyere, the reducing gas tends to rise along the wall surface of the blast furnace, resulting in uneven flow of the reducing gas. In the prior art, sufficient consideration has not been given to uneven flow of the reducing gas in a blast furnace. This application discloses a technology that can suppress thermal damage to the reducing gas injection lance and can suppress uneven flow of the reducing gas when a reducing gas with a low specific gravity is injected into the interior of a blast furnace.

[0005] The present application discloses the following multiple aspects as means for solving the above problems. <Aspect 1> A method for injecting reducing gas into a blast furnace, comprising: injecting hot air into the interior of the blast furnace from a hot blast tuyere provided below the lower end of the shaft of the blast furnace and above the tap hole; and injecting reducing gas into the interior of the blast furnace through a reducing gas injection lance provided within a wall surface of the hot blast tuyere and having an opening at a tip end of the hot blast tuyere, wherein the reducing gas is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot blast, and the height position P of the center of the opening of the reducing gas injection lance is １ The height position P of the center of the hot air tuyere ２ or the height position P ２ The method for injecting reducing gas into a blast furnace according to the first aspect, wherein the reducing gas is blown into the blast furnace at a height position P １ However, the height position P ２ a reducing gas injection lance provided within a wall surface of the hot blast tuyere and having an opening at a tip end of the hot blast tuyere, wherein the reducing gas injected from the reducing gas injection lance into the blast furnace is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot blast injected from the hot blast tuyere into the blast furnace, and the height position P of the center of the opening of the reducing gas injection lance is greater than the height position P of the hot blast tuyere. １ The height position P of the center of the hot air tuyere ２ or the height position P ２ A blast furnace according to Aspect 5, wherein the height position P １ However, the height position P ２Aspect 6 The blast furnace according to Aspect 4 or 5, wherein the reducing gas includes hydrogen gas.

[0006] According to the technology disclosed herein, when a reducing gas with a low specific gravity is injected into the inside of a blast furnace through 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.

[0007] 1 shows an example of the configuration of a blast furnace. Some components provided in the blast furnace are omitted. Another example of the configuration of the lance tip at the tip of the hot blast tuyere is shown. An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is shown. An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is shown. An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is shown. An example of the positional relationship between the hot blast tuyere and the reducing gas injection lance in a blast furnace is shown. The positional relationship between the hot blast tuyere and the lance opening for each of the preceding example, Examples 1 to 3, and Comparative Examples 1 and 2 is shown.

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

[0009] 1. Method of Injecting Reducing Gas into a Blast Furnace As shown in FIG. 1 , a method of injecting reducing gas into a blast furnace 10 according to one embodiment includes: injecting hot air into the interior of the blast furnace 10 from a hot blast tuyere 13 provided below the shaft lower end 11ax of the blast furnace 10 and above the tap hole 12; and injecting reducing gas into the interior of the blast furnace 10 from a reducing gas injection lance 14 provided within the wall surface of the hot blast tuyere 13 and having an opening 14a at the tip end 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 P of the center of the opening 14a of the reducing gas injection lance 14 is １ is the height position P of the center of the hot air tuyere 13 ２ or the height position P ２It exists below.

[0010] 1.1 Hot Blast Tuyere The blast furnace 10 has a hot blast tuyere 13 below the shaft lower end 11ax and above the tap hole 12. The "shaft lower end" refers to the boundary between the shaft 11a and the belly 11b. The "shaft" refers to the portion above the belly 11b, where the furnace diameter typically increases from top to bottom. The "belly" refers to the portion below the shaft and above the bosch 11c, where the furnace diameter typically is greatest. 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 "tap hole" refers to a molten iron tap hole provided at the bottom of the blast furnace 10. The "hot blast 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 belly lower end 11bx and above the tap hole 12, or may have a hot air tuyere 13 below the morning glory lower end 11cx and above the tap hole 12.

[0011] The configuration of the hot air tuyere 13 is 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 stove 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 stove via the hot air pipe and the hot air tuyere 13. The diameter of the hot air tuyere 13 (the circle-equivalent diameter of the opening facing the interior 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 tuyere 13 provided in the blast furnace 10 is not particularly limited, and can be determined depending on the internal volume of the blast furnace. In the blast furnace 10, a plurality of hot air tuyere 13 can be arranged in the circumferential direction of the blast furnace 10. In other words, in the blast furnace 10, a plurality of hot air tuyere 13 can be arranged in the circumferential direction when viewed from above. Usually, the height position P of the center of each of the plurality of hot air tuyere 13 is ２ is similar.

[0013] 1.2 Reducing Gas Injection Lance The blast furnace 10 has a reducing gas injection lance 14. The reducing gas injection lance 14 can be connected to a reducing gas supply source outside the blast furnace 10 via a reducing gas supply passage or the like. In other words, the blast furnace 10 can be configured so that reducing gas is injected from the reducing gas supply source into the interior of the blast furnace 10 via the reducing gas supply passage and the reducing gas injection lance 14. There are no particular limitations on the configuration of the reducing gas supply source or the reducing gas supply passage.

[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 "reducing gas injection lance provided within the wall surface of the hot air tuyere" does not necessarily have to be embedded in the wall surface of the hot air tuyere up to the tip of the lance as shown in FIG. 1 . It also includes, for example, a configuration in which at least a portion of the lance is exposed within the flow path of the hot air tuyere while contacting the inside of the wall surface of the hot air tuyere, as shown in FIG. 2 . That is, as long as at least a portion of the entire circumference of the reducing gas injection lance is located inside the wall surface of the hot air tuyere and the reducing gas injection lance can be cooled by the water-cooling structure within the hot air tuyere (as long as thermal damage to the lance can be suppressed), a portion of the entire circumference of the lance may be exposed within the flow path 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. 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 so that reducing gas is injected into the blast furnace 10 through the opening 14a. The phrase "a reducing gas injection lance having an opening at the tip of the hot air tuyere" means that the reducing gas injection lance opens at or near the tip of the hot air tuyere. In this embodiment, the tip surface of the hot air tuyere and the lance opening do not need to be flush with each other (i.e., the tip of the lance does not need to reach the tip of the hot air tuyere). That is, "having an opening at the tip of the hot air tuyere" includes not only a configuration in which the tip surface of the hot air tuyere and the lance opening are flush with each other (i.e., the tip of the lance reaches the tip of the hot air tuyere), but also a configuration in which the tip of the lance reaches near the tip of the hot air tuyere. Specifically, a lance is considered to have an "opening at the tip of the hot air tuyere" when 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. In this way, in this embodiment, the reducing gas injection lance 14 is provided within the wall surface of the hot air tuyere 13, so that the reducing gas injection lance 14 is less likely to be exposed to hot air, and 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, etc.

[0015] The diameter of the opening 14 a of the reducing gas injection lance 14 (the circle-equivalent diameter of the opening facing the inside of the blast furnace 10) may be, for example, 10 mm to 50 mm, or 20 mm to 30 mm. Alternatively, the diameter of the opening 14 a of the reducing gas injection lance 14 may be 0.05% to 0.8%, or 0.1% to 0.5% of the diameter of the hot blast 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, when the blast furnace 10 has a plurality of hot blast tuyere 13, only some of the plurality of hot blast tuyere 13 may have reducing gas injection lances 14, or all of the plurality of hot blast tuyere 13 may have reducing gas injection lances 14. Furthermore, 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 position P of the center of the opening 14a of each of the multiple reducing gas injection lances 14 １ may be the same as each other or may be different from each other.

[0017] 1.3 Positional relationship between the hot blast tuyere and the opening of the reducing gas injection lance In this embodiment, the height position P of the center of the opening 14a of the reducing gas injection lance 14 １ is the height position P of the center of the hot air tuyere 13 ２ or the height position P ２ According to the new findings of the present inventors, it is important that the center of the opening 14a of the reducing gas injection lance 14 is located below the height position P １ is the height position P of the center of the hot air tuyere 13 ２ If the height position P of the center of the opening 14a of the reducing gas injection lance 14 is higher than the height position P of the center of the opening 14a of the reducing gas injection lance 14, the reducing gas injected from the reducing gas injection lance 14 will tend to rise along the wall surface of the blast furnace 10, and the reducing gas will tend to flow unevenly inside the blast furnace 10. １ is the height position P of the center of the hot air tuyere 13 ２ or at the height position P ２When the reducing gas injection lance 14 is located below the height position P of the center of the opening 14a of the reducing gas injection lance 14, the amount of reducing gas flowing below the hot blast 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 the reducing gas inside the blast furnace 10 is suppressed, and the utilization efficiency of the reducing gas is improved. In particular, １ The height position P of the center of the hot air tuyere 13 ２ When the gas supply passage is located below the pressure vessel, the effect of suppressing the uneven flow of the reducing gas becomes more remarkable.

[0018] 3A and 3B, the height position P of the center of the opening 14a of the reducing gas injection lance 14 is １ is the height position P of the center of the hot air tuyere 13 ２ 3A shows an example in which the center of the opening 14a of the reducing gas injection lance 14 is located below the center of the hot blast tuyere 13. As shown in Fig. 3A, the center of the opening 14a of the reducing gas injection lance 14 may be located directly below the center of the hot blast 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 blast tuyere 13. Furthermore, as shown in Fig. 3B, the center of the opening 14a of the reducing gas injection lance 14 may be located obliquely below the center of the hot blast tuyere 13. That is, the center of the opening 14a of the reducing gas injection lance 14 may be located at a position different from the center of the hot blast tuyere 13 in the circumferential direction of the blast furnace 10.

[0019] 3C shows the height position P of the center of the opening 14a of the reducing gas injection lance 14. １ is the height position P of the center of the hot air tuyere 13 ２ 3C, the opening 14a of the reducing gas injection lance 14 may be provided beside the hot blast tuyere 13.

[0020] 1.4 Hot Air The hot air blown from the hot air tuyere 13 may be, 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 1000°C or higher and 2000°C or lower, 1000°C or higher and 1700°C or lower, 1000°C or higher and 1500°C or lower, or 1000°C or higher and 1300°C or lower. The flow velocity of the hot air at the hot air tuyere 13 (flow rate of the hot air (m ３ / s) / opening area of ​​the hot air tuyere 13 outlet (m ２ ) may be adjusted depending on the operation status of the blast furnace 10. In one embodiment, the flow velocity of the hot air may be a flow velocity V1 described later.

[0021] 1.5 Reducing Gas The reducing gas injected from the reducing gas injection lance 14 functions as a reducing agent inside the blast furnace 10. In other words, even if a gas does not function as a reducing agent before being injected into the blast furnace 10, the term "reducing gas" as used herein is included as long as it can generate a reducing agent (reducing component) inside the blast furnace 10 by thermal decomposition or the like. Furthermore, the specific gravity of the reducing gas is lower than the specific gravity of the hot air injected into the blast furnace 10 from the hot air tuyere 13. Examples of such reducing gas 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 contains hydrogen gas, the technology disclosed herein can be expected to be even more effective. The temperature of the reducing gas injected from the reducing gas injection lance 14 may be, for example, 0°C or higher and 2000°C or lower, or 25°C or higher and 1500°C or lower. In this embodiment, the flow velocity of the reducing gas at the opening 14a of the reducing gas injection lance 14 (flow rate of the reducing gas (m ３ / s) / opening area of ​​the outlet of the reducing gas injection lance 14 (m ２ ) may be, for example, equal to or less than the sonic velocity of each reducing gas at the temperature at which the reducing gas is used. In one embodiment, the flow velocity of the reducing gas injected from the reducing gas injection lance 14 may be a flow velocity V2, which will be described later.

[0022] 1.6 Hot Air Flow Velocity and Reducing Gas Flow Velocity The flow velocity V1 of the hot air blown from the hot air tuyere 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 particularly 200 m / s or more and 400 m / s or less, uneven flow of the reducing gas inside the blast furnace 10 is more likely to be suppressed. Furthermore, the flow velocity V2 of the reducing gas blown 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 particularly 200 m / s or more and 800 m / s or less, ventilation inside the blast furnace 10 is stable, resulting in operation in which the reduction reaction inside the furnace proceeds stably.

[0023] 1.7 Other Gases Other gases may be injected together 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 as a method for injecting reducing gas into a blast furnace, as well as aspects as a blast furnace itself. That is, as shown in FIG. 1 , a blast furnace 10 according to one embodiment has: a hot blast tuyere 13 provided below the shaft lower end 11ax of the blast furnace 10 and above the tap hole 12; and a reducing gas injection lance 14 provided within the wall surface of the hot blast tuyere 13 and having an opening 14a at the tip end 13a of the hot blast tuyere 13. The reducing gas injected 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 smaller than the specific gravity of the hot air injected into the blast furnace 10 from the hot blast tuyere 13. The height position P of the center of the opening 14a of the reducing gas injection lance 14 is １ is the height position P of the center of the hot air tuyere 13 ２ or the height position P ２ It exists below.

[0025] As described above, in the blast furnace 10, the height position P １ However, the height position P ２It is believed that the effect of suppressing the uneven flow of the reducing gas is further enhanced when the reducing gas is located below the pressure drop. Furthermore, it is believed that the effect of the technology of the present disclosure is further enhanced when the reducing gas contains hydrogen gas.

[0026] 3. Supplementary Information During operation of the blast furnace 10, for example, iron ore (iron oxide), coke, etc. are charged into the blast furnace 10 from the top thereof. Meanwhile, hot air is blown into the blast furnace 10 from a hot stove outside the blast furnace 10 via a hot blast pipe and hot blast tuyere 13. Furthermore, 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 a reducing gas injection lance 14. The coke, etc. supplied into the blast furnace 10 is combusted to generate reducing gas. The reducing gas generated by the combustion of the coke, etc., and the reducing gas injected from the reducing gas injection lance 14 reduce and melt the iron oxide to obtain molten iron. The molten iron is tapped from a tap hole 12 provided at the bottom of the blast furnace 10. In this embodiment, the reducing gas is injected into the inside of the blast furnace 10 through the reducing gas injection lance 14, so that the amount of carbon-containing reducing material such as coke used can be reduced accordingly. ２ The amount of generated iron can be reduced. The blast furnace 10 can have various configurations as long as it is capable of producing pig iron as described above. For example, the blast furnace 10 may have other tuyere(s) and lance(s) in addition to the above-described hot blast tuyere(s) 13 and reducing gas injection lance(s) 14. Furthermore, in the blast furnace 10, other reducing gas injection lance(s) may be present above the hot blast tuyere(s) 13. The configuration of the blast furnace 10 other than the hot blast tuyere(s) 13 and reducing gas injection lance(s) 14 is known in the art, and therefore will not be described in detail here.

[0027] 4. Effects As described above, according to this embodiment, the reducing gas injection lance 14 is provided inside the wall surface of the hot blast tuyere 13, so that thermal damage to the lance can be suppressed. Furthermore, according to this embodiment, the height position P １ The height position P of the center of the hot air tuyere 13 ２ or at the height position P ２By being located below this, it is possible to suppress uneven flow of the reducing gas inside the blast furnace 10.

[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 various conditions to be adopted as long as the object is achieved without departing from the gist of the present invention. In the following examples, hydrogen gas is used as the reducing gas, but the type of reducing gas is not limited to this.

[0029] Using a simulation model, the difference in hydrogen concentration between the furnace wall at the top surface of the blast furnace load and the center of the furnace was compared while changing the position where the reducing gas was injected. Specifically, the hydrogen concentration difference was determined for each of the following Prior Art Example, Examples 1 to 3, and Comparative Examples 1 and 2.

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

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

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

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

[0034] Comparative Example 1: As shown in "Comparative Example 1" in Figure 4, a lance was inserted into the wall surface 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 from the hot air tuyere, and hydrogen gas was blown from the lance.

[0035] Comparative Example 2: As shown in "Comparative Example 2" in Figure 4, a lance was inserted into the wall surface 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 from the hot air tuyere, and hydrogen gas was blown from the lance.

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

[0037]

[0038] As is clear from the results shown in Table 1, when the height position of the center of the opening of the reducing gas injection lance was the same as or lower than the height position of the center of the hot blast tuyere, as in the prior art example and Examples 1 to 3, almost no difference in hydrogen concentration was observed at the top surface of the blast furnace load. This is thought to be because hydrogen gas and hot blast were sufficiently mixed at the tuyere level, and hydrogen was dispersed along with the hot blast in the furnace. However, when the tip of the reducing gas injection lance does not contact the wall surface of the hot blast tuyere and the entire circumference of the lance is exposed within the flow path of the hot blast tuyere, as in the prior art example, the lance is prone to thermal damage due to the hot blast. In this regard, the prior art example has issues with lance durability. However, by arranging the reducing gas injection lance within the wall surface of the hot blast tuyere (at least a portion of the entire circumference of the lance is arranged inside the wall surface of the hot blast tuyere), as in Examples 1 to 3, this issue can be resolved. In other words, from the perspective of simultaneously suppressing the uneven flow of reducing gas and suppressing thermal damage to the lance, Examples 1 to 3 are more advantageous than the prior art example.

[0039] On the other hand, when the height position of the center of the opening of the reducing gas injection lance was higher than the height position of the center of the hot blast tuyere, as in Comparative Examples 1 and 2, a large difference in hydrogen concentration was observed between the furnace center and the furnace wall at the top surface of the contents inside the blast furnace. This is thought to be because the specific gravity of hydrogen gas is smaller than that of air (hot blast), and the hydrogen gas is not pushed by the hot blast blown in from the hot blast tuyere, and so the hydrogen gas flows preferentially along the wall side of the furnace.

[0040] From the above, it can be said that by providing a reducing gas injection lance within the wall surface of the hot blast tuyere, it is possible to suppress thermal damage to the lance. Furthermore, when a reducing gas injection lance is provided within the wall surface of the hot blast tuyere and the opening of the lance is arranged at the tip of the hot blast tuyere, and reducing gas is injected from the lance, the height position P １ is the height position P of the center of the hot air tuyere ２ or at the height position P ２ When the reducing gas is present below the pressure drop, it can be said that uneven flow of the reducing gas inside the blast furnace can be suppressed.

[0041] To summarize the above results, it can be said that the following method (1) and blast furnace (2) can suppress thermal damage to the reducing gas injection lance and also suppress uneven flow of the reducing gas when injecting a reducing gas with a low specific gravity into the inside of a blast furnace.

[0042] (1) A method of injecting reducing gas into a blast furnace, comprising: injecting hot air into the interior of the blast furnace from a hot air tuyere provided below a lower end of the shaft of the blast furnace and above a tap hole; and injecting reducing gas into the interior of the blast furnace through a reducing gas injection lance provided within a wall surface of the hot air tuyere and having an opening at a tip end of the hot air tuyere, wherein the reducing gas is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot air, and the height position P of the center of the opening of the reducing gas injection lance is １ The height position P of the center of the hot air tuyere ２ or the height position P ２ A method of injecting reducing gas into a blast furnace located below the

[0043] (2) A blast furnace, comprising: a hot blast tuyere provided below the lower end of the shaft of the blast furnace and above the tap hole; and a reducing gas injection lance provided within a wall surface of the hot blast tuyere and having an opening at a tip end of the hot blast tuyere, wherein the reducing gas injected from the reducing gas injection lance into the inside of the blast furnace is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot blast injected from the hot blast tuyere into the inside of the blast furnace, and the height position P of the center of the opening of the reducing gas injection lance is １ The height position P of the center of the hot air tuyere ２ or the height position P ２ A blast furnace located below.

[0044] 10 Blast furnace 11 Furnace belly 12 Taphole 13 Hot blast tuyere 13a Tip 14 Reducing gas injection lance 14a Opening

Claims

1. A method of injecting reducing gas into a blast furnace, comprising: 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 the tap hole; and injecting reducing gas into the interior of the blast furnace through a reducing gas injection lance provided within the wall surface of the hot air tuyere and having an opening at the tip of the hot air tuyere, wherein the reducing gas is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot air, and the height position P of the center of the opening of the reducing gas injection lance is １ The height position P of the center of the hot air tuyere ２ or the height position P ２ A method of injecting reducing gas into a blast furnace located below the 2. The method for injecting reducing gas into a blast furnace according to claim 1, wherein the height position P １ However, the height position P ２ A method of injecting reducing gas into a blast furnace located below the 3. A method for injecting a reducing gas into a blast furnace according to claim 1 or 2, wherein the reducing gas contains hydrogen gas.

4. A blast furnace comprising: a hot blast tuyere provided below the belly of the blast furnace and above the tap hole; and a reducing gas injection lance provided within the wall surface of the hot blast tuyere and having an opening at the tip of the hot blast tuyere, wherein the reducing gas injected from the reducing gas injection lance into the interior of the blast furnace is a gas that functions as a reducing agent inside the blast furnace, the specific gravity of the reducing gas is smaller than the specific gravity of the hot blast injected from the hot blast tuyere into the interior of the blast furnace, and the height position P of the center of the opening of the reducing gas injection lance is １ The height position P of the center of the hot air tuyere ２ or the height position P ２ A blast furnace located below.

5. A blast furnace according to claim 4, wherein the height position P １ However, the height position P ２ A blast furnace located below.

6. A blast furnace according to claim 4 or 5, wherein the reducing gas contains hydrogen gas.

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