Blast furnace, tuyere for blast furnace, and method for supplying reducing gas to blast furnace

Abstract

Disclosed is a new technology for suppressing deviations in the concentration distribution of a reducing gas in a furnace radial direction inside a blast furnace when supplying reducing gas to the inside of the blast furnace. One embodiment of the technology according to the present disclosure is a blast furnace having a hot-air tuyere, said blast furnace characterized in that: the hot-air tuyere has a tuyere body, a reducing gas blow port, and a reducing gas blow lance; the tuyere body has a hot-air flow path; the reducing gas blow port penetrates the wall of the tuyere body; and the reducing gas blow lance has a blowout port within the hot-air flow path.

Description

Blast furnace, tuyere for blast furnace, and method for supplying reducing gas to blast furnace

[0001] The present application discloses a blast furnace, a tuyere for a blast furnace, and a method for supplying reducing gas to 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 supplying reducing gas to a blast furnace, Patent Documents 1 and 2 disclose 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 3 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. 5070706 Patent No. 5840202

[0004] When reducing gas is supplied into a blast furnace through hot blast tuyere, the concentration of the reducing gas is likely to become uneven in the radial direction inside the blast furnace.

[0005] The present application discloses the following multiple aspects as means for solving the above problems. <Aspect 1> A blast furnace having a hot blast tuyere, wherein the hot blast tuyere comprises a tuyere body, a reducing gas injection port, and a reducing gas injection lance, wherein the tuyere body has a hot blast flow path, the reducing gas injection port penetrates a wall of the tuyere body, and the reducing gas injection lance has an outlet within the hot blast flow path. <Aspect 2> The blast furnace of Aspect 1, wherein the outlet of the reducing gas injection port faces the hot blast flow path. <Aspect 3> The blast furnace of Aspect 1 or 2, wherein the height position P of the center of the outlet of the reducing gas injection port is １ The height position P of the center of the opening of the tuyere body ２ and the height position P of the center of the outlet of the reducing gas injection lance is higher than ３ The height position P of the center of the opening of the tuyere body２ a blast furnace located below the reducing gas injection port. <Aspect 4> The blast furnace of any of Aspects 1 to 3, wherein the reducing gas supplied from the reducing gas injection port and the reducing gas injection lance contains hydrogen gas. <Aspect 5> A method for supplying reducing gas to a blast furnace, comprising: supplying hot air into the interior of the blast furnace through a hot blast tuyere of the blast furnace, and supplying reducing gas into the interior of the blast furnace through a reducing gas injection port penetrating a wall of a tuyere body of the hot blast tuyere and a reducing gas injection lance having an outlet in a hot blast flow path of the hot blast tuyere. <Aspect 6> The method for supplying reducing gas to a blast furnace of Aspect 5, wherein reducing gas is supplied from the outlet of the reducing gas injection port to the hot blast flow path. <Aspect 7> The method for supplying reducing gas to a blast furnace of Aspect 5 or 6, wherein a height position P of the center of the outlet of the reducing gas injection port １ The height position P of the center of the hot air tuyere ２ and the height position P of the center of the outlet of the reducing gas injection lance is higher than ３ The height position P of the center of the hot air tuyere ２ a reducing gas supply port extending through a wall of the tuyere body, and a reducing gas injection lance having an outlet within the hot blast flow path. <Aspect 8> The method for supplying a reducing gas to a blast furnace according to any of Aspects 5 to 7, wherein the reducing gas includes hydrogen gas. <Aspect 9> A tuyere for a blast furnace, comprising: a tuyere body, a reducing gas injection port, and a reducing gas injection lance, wherein the tuyere body has a hot blast flow path, the reducing gas injection port penetrates a wall of the tuyere body, and the reducing gas injection lance has an outlet within the hot blast flow path.

[0006] According to the technology of the present disclosure, when reducing gas is supplied into the interior of a blast furnace, it is possible to suppress unevenness in the concentration of reducing gas in the radial direction of the interior of the blast furnace.

[0007] 1 is a schematic illustration of an example of the configuration of a blast furnace. Some components provided in the blast furnace are omitted. A schematic illustration of an example of the configuration of a tuyere body, reducing gas injection port, and reducing gas injection lance in a hot blast tuyere. The upper side of the paper corresponds to the furnace top side, and the lower side of the paper corresponds to the furnace bottom side. A schematic illustration of an example of the configuration of a tuyere body, reducing gas injection port, and reducing gas injection lance in a hot blast tuyere. The upper side of the paper corresponds to the furnace top side, and the lower side of the paper corresponds to the furnace bottom side. A schematic illustration of an example of the positional relationship between the opening of the tuyere body in a hot blast tuyere and the outlet of the reducing gas injection port. A schematic illustration of an example of the positional relationship between the opening of the tuyere body in a hot blast tuyere and the outlet of the reducing gas injection port. A schematic illustration of an example of the positional relationship between the opening of the tuyere body in a hot blast tuyere and the outlet of the reducing gas injection port. A schematic illustration of an example of the positional relationship between the opening of the tuyere body in a hot blast tuyere and the outlet of the reducing gas injection port. A schematic illustration of an example of the positional relationship between the opening of the tuyere body in a hot blast tuyere and the outlet of the reducing gas injection port. 1 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection port. FIG. 1 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 2 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 3 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 4 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 5 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 6 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 7 shows an example of a positional relationship between an opening of a tuyere body in a hot air tuyere and the outlet of a reducing gas injection lance. FIG. 8 shows simulation conditions. FIG. 9 shows simulation conditions. FIG. 10 shows hydrogen concentration distribution based on simulation results. FIG. 11 shows hydrogen concentration distribution based on simulation results. FIG. 12 shows hydrogen concentration distribution based on simulation results. FIG. 13 shows simulation conditions. FIG. 14 shows simulation conditions. FIG. 15 shows hydrogen concentration distribution based on simulation results. 1 shows the hydrogen concentration distribution based on the simulation results. 2 shows the hydrogen concentration distribution based on the simulation results. 3 shows the hydrogen concentration distribution based on the simulation results.

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

[0009] 1. Blast Furnace As shown in Fig. 1, a blast furnace 100 according to one embodiment has a hot blast tuyere 10. As shown in Figs. 2A and 2B, the hot blast tuyere 10 has a tuyere body 11, a reducing gas injection port 12, and a reducing gas injection lance 13. The tuyere body 11 has a hot blast flow path 11a. The reducing gas injection port 12 penetrates the wall of the tuyere body 11. The reducing gas injection lance 13 has an injection port 13ax in the hot blast flow path 11a.

[0010] In this application, the term "reducing gas injection port" refers to a reducing gas passage provided so as to penetrate the wall of the tuyere body, and the term "reducing gas injection lance" refers to a lance having an outlet in the hot air passage of the tuyere body without penetrating the wall of the tuyere body. The reducing gas injection lance may, for example, penetrate a blowpipe provided outside the furnace relative to the tuyere body.

[0011] 1.1 Hot Blast Tuyere As shown in FIG. 1 , the hot blast tuyere 10 is provided, for example, below the shaft lower end 101ax of the blast furnace 100 and above the tap hole 102. The "shaft lower end" refers to the boundary between the shaft 101a and the belly 101b. The "shaft" refers to the portion above the belly 101b, where the furnace diameter typically increases from top to bottom. The "belly" refers to the portion below the shaft and above the bosch 101c, where the furnace diameter typically is greatest. The furnace diameter (diameter) of the belly 101b 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 port provided at the bottom of the blast furnace 100. The "hot blast tuyere" refers to a nozzle for supplying hot air to the blast furnace. The blast furnace 100 may have a hot air tuyere 10 below the belly lower end 101bx and above the tap hole 102, or may have a hot air tuyere 10 below the morning glory lower end 101cx and above the tap hole 102.

[0012] The number of hot air tuyere 10 provided in the blast furnace 100 is not particularly limited, and can be determined depending on the internal volume of the blast furnace. In the blast furnace 100, a plurality of hot air tuyere 10 may be arranged in the circumferential direction of the blast furnace 100. In other words, in the blast furnace 100, a plurality of hot air tuyere 10 may 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 10 is ２ are the same.

[0013] 1.1.1 Tuyere Body The tuyere body 11 is a hollow member having a hot air flow path 11a. The upstream side of the hot air flow path 11a of the tuyere body 11 is connected to a blowpipe (not shown), and the downstream side of the hot air flow path 11a faces the interior of the blast furnace 100. The tuyere body 11 has an opening 11ax (hot air outlet) as an outlet of the hot air flow path 11a at the tip facing the interior of the blast furnace 100. The tuyere body 11 can be connected to a hot air stove outside the blast furnace 100 via a hot air pipe, a blowpipe, or the like. In other words, the blast furnace 100 can be configured so that hot air is supplied from the hot air stove to the interior of the blast furnace 100 via the hot air pipe, the blowpipe, and the tuyere body 11. The opening diameter of the tuyere body (the circle-equivalent diameter of the opening 11ax facing the inside of the blast furnace 100, 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.

[0014] 2A and 2B, the wall of the tuyere body 11 has, for example, an inner surface 11x facing the hot air flow path 11a, and an outer surface 11y and an end surface 11z facing the inside of the blast furnace 100. A reducing gas injection port 12, which will be described later, is provided so as to penetrate the wall. The tuyere body 11 may have a cooling water flow path inside the wall. This allows the tuyere body 11 and its surroundings to be cooled during operation of the blast furnace 100, thereby suppressing thermal damage and the like. The tuyere body 11 is made of a known material, for example, copper.

[0015] 1.1.2 Reducing Gas Injection Port The reducing gas injection port 12 can be connected to a reducing gas supply source 20 outside the blast furnace 100 via a reducing gas supply passage 21 or the like. In other words, the blast furnace 100 can be configured so that reducing gas is supplied from the reducing gas supply source 20 to the inside of the blast furnace 100 via the reducing gas supply passage 21 and the reducing gas injection port 12. There are no particular limitations on the configurations of the reducing gas supply source 20 and the reducing gas supply passage 21.

[0016] 2A and 2B , the reducing gas injection port 12 is provided so as to penetrate the wall of the tuyere body 11. For example, the reducing gas injection port 12 has a flow path 12a in the wall surface of the tuyere body 11 and has an outlet 12ax downstream of the flow path 12a. The length, longitudinal shape, opening shape, etc. of the flow path 12a of the reducing gas injection port 12 can be determined appropriately in consideration of the thickness of the wall of the tuyere body 11 and the water-cooling structure within the wall.

[0017] As shown in FIG. 2A , the outlet 12ax of the reducing gas injection port 12 may face the hot air flow path 11a. That is, the reducing gas injection port 12 may supply reducing gas so as to merge with the hot air flow path 11a. Alternatively, as shown in FIG. 2B , the outlet 12ax of the reducing gas injection port 12 may be provided on the end surface 11z of the tuyere body 11. That is, the reducing gas injection port 12 may supply reducing gas into the blast furnace 100 independently of the hot air flow path 11a. According to the findings of the present inventors, particularly when the outlet 12ax of the reducing gas injection port 12 faces the hot air flow path 11a (that is, when reducing gas is supplied from the outlet 12ax of the reducing gas injection port 12 to the hot air flow path 11a) as shown in FIG. 2A , the concentration distribution of the reducing gas in the radial direction of the blast furnace 100 can be made more uniform. In this case, there is no particular limitation on the distance from the center (centroid) of the downstream opening 11ax of the hot air flow path 11a to the center (centroid) of the outlet 12ax of the reducing gas blowing port 12. The distance may be, for example, 50 mm or more and 300 mm or less, or 75 mm or more and 150 mm or less.

[0018] The diameter (diameter of a circle with an area equivalent) of the outlet 12ax of the reducing gas injection port 12 may be, for example, 10 mm to 50 mm, or 20 mm to 30 mm. Alternatively, the diameter of the outlet 12ax of the reducing gas injection port 12 may be 10% to 50%, or 15% to 30% of the diameter of the opening 11ax of the tuyere body 11. When the outlet 12ax has such a diameter, it is easier to control the flow rate of the reducing gas.

[0019] The number of reducing gas injection ports 12 in the hot air tuyere 10 is not particularly limited. The number of reducing gas injection ports 12 provided in the hot air tuyere 10 may be one or more. The height position of the reducing gas injection port 12 provided in the hot air tuyere 10 is not particularly limited. The height position P １ This will be discussed later.

[0020] 1.1.3 Reducing Gas Injection Lance The reducing gas injection lance 13, like the reducing gas injection port 12, can be connected to a reducing gas supply source 20 outside the blast furnace 100 via a reducing gas supply passage 21 or the like. In other words, the blast furnace 100 can be configured so that reducing gas is supplied from the reducing gas supply source 20 to the inside of the blast furnace 100 via the reducing gas supply passage 21 and the reducing gas injection lance 13. There are no particular limitations on the configuration of the reducing gas supply source 20 or the reducing gas supply passage 21. The reducing gas supply source 20 and the reducing gas passage 21 connected to the reducing gas injection lance 13 may have the same configuration as the reducing gas supply source 20 and the reducing gas passage 21 connected to the above-mentioned reducing gas injection port 12, or may have a different configuration.

[0021] The reducing gas supply source connected to the reducing gas injection port 12 and the reducing gas injection lance 13 may be the same or different from each other. That is, reducing gas may be supplied from one reducing gas supply source to both the reducing gas injection port 12 and the reducing gas injection lance 13 via branch passages, or reducing gas may be supplied from one reducing gas supply source to the reducing gas injection port 12 and from another reducing gas supply source to the reducing gas injection lance 13.

[0022] 2A and 2B , the reducing gas injection lance 13 has a flow passage 13 a therein and an outlet 13 ax on the downstream side of the flow passage 13 a, and the outlet 13 ax may be disposed within the hot air flow passage 11 a. The length, longitudinal shape, opening shape, etc. of the reducing gas injection lance 13 can be determined appropriately in consideration of the shape of the hot air flow passage 11 a.

[0023] The outlet 13ax of the reducing gas injection lance 13 may be located within the hot air flow path 11a, and there is no particular limitation on the distance from the center (centroid) of the downstream opening 11ax of the hot air flow path 11a to the center (centroid) of the outlet 13ax of the reducing gas injection lance 13. The distance may be, for example, 50 mm or more and 300 mm or less, or 75 mm or more and 150 mm or less.

[0024] The diameter (diameter of a circle with an area equivalent) of the outlet 13ax of the reducing gas injection lance 13 may be, for example, 10 mm to 50 mm, or 20 mm to 30 mm. Alternatively, the diameter of the outlet 13ax of the reducing gas injection lance 13 may be 10% to 50%, or 15% to 30% of the diameter of the opening 11ax of the tuyere body 11. When the outlet 13ax has such a diameter, it is easier to control the flow rate of the reducing gas.

[0025] The number of reducing gas injection lances 13 in the hot blast tuyere 10 is not particularly limited. The number of reducing gas injection lances 13 provided in the hot blast tuyere 10 may be one or more. The height position of the reducing gas injection lance 13 provided in the hot blast tuyere 10 is not particularly limited. For example, the height position P ３ This will be discussed later.

[0026] 1.2 Height position of the opening of the tuyere body and each outlet As shown in FIG. 3A, the height position P of the center of the outlet 12ax of the reducing gas injection port 12 １ is the height position P of the center of the opening 11ax of the tuyere body 11 ２3B , when the opening 11ax of the tuyere body 11 is viewed from the front, a line L passing through the center of the opening 11ax and the center of the opening 11ax of the tuyere body 11 is aligned with the center of the opening 11ax of the tuyere body 11. １ is a vertical line L passing through the center of the opening 11ax. ２ With respect to angle θ １ The angle θ １ 3B illustrates an example in which the outlet 12ax is located on the left half side of the tuyere body 11, but the outlet 12ax may be located on the right half side of the tuyere body 11.

[0027] As shown in FIG. 3C, the height position P １ is the height position P of the center of the opening 11ax of the tuyere body 11 ２3D , when the opening 11ax of the tuyere body 11 is viewed from the front, a line L passing through the center of the opening 11ax and the center of the opening 11ax of the tuyere body 11 is aligned with the center of the opening 11ax of the tuyere body 11. １ is a vertical line L passing through the center of the opening 11ax. ２ With respect to angle θ ２ The angle θ ２ 3D illustrates an example in which the outlet 12ax is located on the left half side of the tuyere body 11, but the outlet 12ax may be located on the right half side of the tuyere body 11.

[0028] As shown in FIG. 3E, the height position P １ is the height position P of the center of the opening 11ax of the tuyere body 11 ２ For example, the center of the outlet 12ax of the reducing gas injection port 12 may be provided directly beside the center of the opening 11ax of the tuyere body 11. Note that, although Fig. 3E illustrates an example in which the outlet 12ax is located on the left half side of the tuyere body 11, the outlet 12ax may be located on the right half side of the tuyere body 11.

[0029] As shown in FIG. 4A, the height position P ３ is the height position P of the center of the opening 11ax of the tuyere body 11 ２4B , when the opening 11ax of the tuyere body 11 is viewed from the front, a straight line L passing through the center of the opening 11ax and the opening 11ax of the tuyere body 11 is aligned with the center of the opening 11ax of the tuyere body 11. The center of the opening 13ax of the reducing gas injection lance 13 may be located above the center of the opening 11ax of the tuyere body 11. For example, the center of the outlet 13ax of the reducing gas injection lance 13 may be located directly above the center of the opening 11ax of the tuyere body 11. That is, the position of the center of the outlet 13ax of the reducing gas injection lance 13 in the circumferential direction of the blast furnace 100 may be the same as the position of the center of the opening 11ax of the tuyere body 11. Alternatively, the center of the outlet 13ax of the reducing gas injection lance 13 may be located diagonally above the center of the opening 11ax of the tuyere body 11. That is, the position of the center of the opening 11ax of the reducing gas injection lance 13 may be different from the position of the center of the opening 11ax of the tuyere body 11. For example, as shown in FIG. 4B , when the opening 11ax of the tuyere body 11 is viewed from the front, a straight line L passing through the center of the opening 11ax and the center of the outlet 13ax is aligned with the center of the opening 11ax of the tuyere body 11. ３ is a vertical line L passing through the center of the opening 11ax. ２ With respect to angle θ ３ The angle θ ３ 4B illustrates an example in which the outlet 13ax is located on the right half side of the tuyere body 11, but the outlet 13ax may be located on the left half side of the tuyere body 11.

[0030] As shown in FIG. 4C, the height position P ３ is the height position P of the center of the opening 11ax of the tuyere body 11 ２4D , when the opening 11ax of the tuyere body 11 is viewed from the front, a line L passing through the center of the opening 11ax and the center of the opening 11ax of the tuyere body 11 is aligned with the center of the opening 11ax of the blast furnace 100. １ is a vertical line L passing through the center of the opening 11ax. ２ With respect to angle θ ４ The angle θ ４ 4D illustrates an example in which the outlet 13ax is located on the right half side of the tuyere body 11, but the outlet 13ax may be located on the left half side of the tuyere body 11.

[0031] As shown in FIG. 4E, the height position P ３ is the height position P of the center of the opening 11ax of the tuyere body 11 ２ For example, the center of the outlet 13ax of the reducing gas injection lance 13 may be provided so as to coincide with the center of the opening 11ax of the tuyere body 11, or may be provided directly beside the center of the opening 11ax.

[0032] According to the findings of the present inventors, when the height positions of the blowout ports 12ax, 13ax are divided into upper and lower positions, the distribution of the reducing gas concentration in the furnace radial direction inside the blast furnace 100 can be made more uniform. In this regard, in one embodiment, the height position P １ is the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３For example, in one embodiment, the height position P １ The height position P of the center of the opening 11ax of the tuyere body 11 ２ and the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３ The height position P of the center of the opening 11ax of the tuyere body 11 ２ In other words, when the tuyere body 11 is divided into an upper half and a lower half, the outlet 12ax of the reducing gas injection port 12 may be located at any position in the upper half, and the outlet 13ax of the reducing gas injection lance 13 may be located at any position in the lower half. Alternatively, in one embodiment, the height position P １ is the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３ For example, the height position P １ The height position P of the center of the opening 11ax of the tuyere body 11 ２ and the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３ The height position P of the center of the opening 11ax of the tuyere body 11 ２ In other words, when the tuyere body 11 is divided into an upper half and a lower half, the outlet 12ax of the reducing gas injection port 12 may be located at any position in the lower half, and the outlet 13ax of the reducing gas injection lance 13 may be located at any position in the upper half. Alternatively, in one embodiment, when the tuyere body 11 is divided into an upper half and a lower half, the outlet 12ax of the reducing gas injection port 12 and the outlet 13ax of the reducing gas injection lance 13 may both be located at any position in the upper half, and the height position P １ is the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３Alternatively, in one embodiment, when the tuyere body 11 is divided into an upper half and a lower half, the outlet 12ax of the reducing gas injection port 12 and the outlet 13ax of the reducing gas injection lance 13 may both be located at a position in the lower half, and the height position P １ is the height position P of the center of the blowout port 13ax of the reducing gas blowing lance 13 ３ may be at a different height position.

[0033] 1.4 Hot Air The hot air supplied from the hot air tuyere 10 into the blast furnace 100 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 opening 11ax of the tuyere body 11 may be appropriately adjusted depending on the operating conditions of the blast furnace 100, and may be, for example, 100 m / s or higher and 300 m / s or lower, or 200 m / s or higher and 250 m / s or lower.

[0034] 1.5 Reducing Gas Reducing gas is a gas that functions as a reducing agent inside the blast furnace 100. In other words, even if a gas does not function as a reducing agent before being supplied to the blast furnace 100, the term "reducing gas" as used herein includes any gas that can generate a reducing agent (reducing component) by thermal decomposition inside the blast furnace 100. Examples of such reducing gases include at least one selected from hydrogen gas, hydrocarbon gas (e.g., methane gas), carbon monoxide gas, ammonia gas, and alcohol gas (e.g., methanol gas or ethanol gas). In addition, in the technology disclosed herein, at least one selected from coke oven gas (COG), converter gas (LDG), blast furnace gas (BFG), natural gas (NG), and synthesis gas (Syngas) may be used as the reducing gas. These reducing gases may be used alone or in combination of two or more. In particular, when the reducing gas includes hydrogen gas, the technology disclosed herein is expected to be even more effective. The temperature of the reducing gas supplied from the reducing gas injection port 12 and the reducing gas injection lance 13 into the blast furnace 100 may be, for example, 0°C or higher and 2000°C or lower, or 25°C or higher and 1500°C or lower. In the present embodiment, the flow velocity of the reducing gas at the outlet 12ax of the reducing gas injection port 12 and the outlet 13ax of the reducing gas injection lance 13 may be, for example, lower than the sonic velocity at the operating temperature of each reducing gas. For example, the flow velocity of the reducing gas at each of the outlet 12ax of the reducing gas injection port 12 and the outlet 13ax of the reducing gas injection lance 13 may be 100 m / s or higher and 1000 m / s or lower. In particular, if the flow velocity is 200 m / s or higher and 800 m / s or lower, ventilation inside the blast furnace 100 is stabilized, and operation in which the reduction reaction in the furnace proceeds stably is likely to be achieved.

[0035] 1.6 Other Gases Other gases may be supplied together with the reducing gas from the reducing gas injection port 12 and the reducing gas injection lance 13. Examples of other gases include inert gases such as nitrogen gas.

[0036] 2. Method for Supplying Reducing Gas to a Blast Furnace The technology disclosed herein also has an aspect as a method for supplying reducing gas to a blast furnace. That is, a method for supplying reducing gas to a blast furnace 100 according to one embodiment includes: supplying hot air into the interior of the blast furnace 100 through a hot air tuyere 10 of the blast furnace 100; and supplying reducing gas into the interior of the blast furnace 100 through a reducing gas injection port 12 penetrating a wall of a tuyere body 11 of the hot air tuyere 10 and a reducing gas injection lance 13 having an outlet 13ax in a hot air flow path 11a of the hot air tuyere 10.

[0037] The details and preferred embodiments of the method for supplying hot air and reducing gas are as described above. For example, in the method for supplying reducing gas to the blast furnace 100 according to this embodiment, reducing gas may be supplied to the hot air flow path 11a from the outlet 12ax of the reducing gas blowing port 12. In addition, the height position P of the center of the outlet 12ax of the reducing gas blowing port 12 may be set to 0.05 mm. １ The height position P of the center of the opening 11ax of the tuyere body 11 ２ and the height position P ３ The height position P of the center of the opening 11ax of the tuyere body 11 ２ The reducing gas may be present below the temperature of the heating element. The reducing gas may contain hydrogen gas.

[0038] 3. Blast Furnace Tuyere The technology of the present disclosure also has an aspect as a blast furnace tuyere. The blast furnace tuyere corresponds to the hot air tuyere 10 described above. That is, the blast furnace tuyere 10 according to one embodiment has a tuyere body 11, a reducing gas injection port 12, and a reducing gas injection lance 13. Here, the tuyere body 11 has a hot air flow path 11a, the reducing gas injection port 12 penetrates the wall of the tuyere body 11, and the reducing gas injection lance 13 has an injection port 13ax within the hot air flow path 11a. Each configuration is as described above, and detailed description thereof will be omitted here.

[0039] 3. Supplementary Note: In the operation of the blast furnace 100, for example, iron ore (iron oxide), coke, etc. are charged into the interior of the blast furnace 100 from the top of the blast furnace 100, hot air is supplied into the interior of the blast furnace 100 from a hot stove outside the blast furnace 100 via a hot air pipe and hot air tuyere 10, reducing gas is supplied into the interior of the blast furnace 100 from a reducing gas supply source outside the blast furnace 100 via a reducing gas flow path and a reducing gas injection port 12, and reducing gas is supplied into the interior of the blast furnace 100 from a reducing gas supply source outside the blast furnace 100 via a reducing gas flow path and a reducing gas injection lance 13. The coke, etc. supplied into the interior of the blast furnace 100 is combusted to generate reducing gas. The reducing gas generated by the combustion of the coke, etc., and the reducing gas supplied from the reducing gas injection port 12 and the reducing gas injection lance 13 reduce and dissolve the iron oxide to obtain molten iron. The molten iron is tapped from a tap hole 102 provided at the bottom of the blast furnace 100. In this embodiment, reducing gas is supplied to the inside of the blast furnace 100 through the reducing gas injection port 12 and the reducing gas injection lance 13, so that the amount of carbon-containing reducing material such as coke used can be reduced accordingly. ２ The amount of generated carbon dioxide can be reduced. The blast furnace 100 can have various configurations as long as it is capable of producing pig iron as described above. For example, the blast furnace 100 may have other tuyere(s), ports, or lance(s) in addition to the above-described hot blast tuyere 10. Furthermore, the above-described hot blast tuyere 10 may have other ports, lances, or the like in addition to the above-described tuyere body 11, reducing gas injection port 12, and reducing gas injection lance 13. For example, the hot blast tuyere 10 may have a pulverized coal injection lance, or the like. The configuration of the blast furnace 100 other than the hot blast tuyere 10 is known in the art, and therefore will not be described in detail here.

[0040] 4. Effects As described above, according to the present embodiment, the reducing gas injection port 12 and the reducing gas injection lance 13 are used in combination as a means for supplying reducing gas into the interior of the blast furnace 100, and reducing gas is supplied from the multiple outlets 12ax, 13ax, which makes it possible to make the concentration distribution of the reducing gas in the radial direction of the interior of the blast furnace 100 more uniform than when reducing gas is supplied from only one outlet.

[0041] Furthermore, when the reducing gas injection port 12 and the reducing gas injection lance 13 are used in combination as a means for supplying reducing gas into the blast furnace 100, a larger amount of reducing gas can be supplied into the blast furnace 100, and the supply of reducing gas can be more easily stabilized, compared to when reducing gas is supplied in a single system. According to the inventor's findings, if the number of reducing gas injection ports provided in the hot blast tuyere is too large in order to supply a larger amount of reducing gas into the blast furnace, water cooling of the hot blast tuyere tends to be hindered, and if the number of reducing gas injection lances is too large, the amount of combustion of the reducing gas in the hot blast tuyere tends to increase, increasing the thermal load of the equipment. In contrast, by using the reducing gas injection port and the reducing gas injection lance in combination in the hot blast tuyere, a large amount of reducing gas can be supplied into the blast furnace even if the number of reducing gas injection ports and reducing gas injection lances is small, and therefore the above-mentioned problems are less likely to become apparent. Furthermore, by using the reducing gas injection port 12 and the reducing gas injection lance 13 in combination, it is possible to achieve both the advantageous effects of the port structure (for example, the tendency for the amount of reducing gas combustion in the hot air tuyere to be low) and the advantageous effects of the lance structure (for example, the ease of replacing the lance during operation).

[0042] The present invention will be further described below with reference to examples, but the present invention is not limited to these examples. The present invention allows for various conditions to be adopted as long as the object is achieved without departing from the gist of the invention. In the following examples, hydrogen gas is used as the reducing gas, but the type of reducing gas is not limited to this. In the examples shown below, the general-purpose thermal fluid analysis software FLUENT was used to perform a simulation taking into account gas flow, heat transfer, and chemical reactions, thereby evaluating the concentration of hydrogen molecules inside a blast furnace. In this simulation, the raceway region near the tuyere was treated as a cavity where no coke exists, and the coke-packed bed region in the blast furnace away from the raceway was treated as a porous medium. A standard k-ε model was used for turbulence analysis, a vortex dissipation model for gas combustion, and a coke O model were used. ２ , CO ２ , H ２Field's model was used for the gasification reaction of O.

[0043] 1. When hydrogen gas is supplied by one system Using simulation, the hydrogen concentration distribution in the furnace radial direction at a height of 12 m from the center of the tuyere in each of the following cases was confirmed: (1) When hydrogen is supplied into the hot blast channel only from the hydrogen injection port that penetrates the lower wall of the tuyere body (Fig. 5A) (2) When hydrogen is supplied into the hot blast channel only from the hydrogen injection port that penetrates the upper wall of the tuyere body (Fig. 5B) (3) When hydrogen is supplied only from a hydrogen injection lance that has an outlet inside the hot blast channel of the tuyere body (Fig. 5C) The flow rate of hydrogen gas supplied from the port / lance was 2615 Nm ３ / hr. Figure 6A shows the hydrogen concentration distribution in the case of (1) above, Figure 6B shows the hydrogen concentration distribution in the case of (2) above, and Figure 6C shows the hydrogen concentration distribution in the case of (3) above. The hydrogen concentration distribution was normalized by the average hydrogen mole fraction at a height of 12 m from the center of the tuyere.

[0044] 6A to 6C, it can be seen that the bias in the hydrogen concentration within the furnace varies depending on the means and position of supplying hydrogen gas. For example, in the case of (1) above, the hydrogen concentration is high between the furnace wall and the furnace center within the blast furnace. In addition, in the case of (2) above, the hydrogen concentration is high on the wall side and at the furnace center within the blast furnace. In addition, in the case of (3) above, the hydrogen concentration is high in the area close to the furnace wall between the furnace wall and the furnace center within the blast furnace. In other words, it is believed that by using multiple types of hydrogen gas injection means and / or multiple blowing positions in the hot blast tuyere, the hydrogen concentration distribution in the radial direction within the blast furnace can be averaged and uniformed.

[0045] 2. When hydrogen gas is supplied by two systems Using simulations, the following cases were confirmed: (4) When hydrogen is supplied into the hot blast flow path from each of two hydrogen injection ports penetrating the upper wall of the tuyere body (Fig. 7A); (5) When hydrogen is supplied from each of two hydrogen injection lances arranged inside the hot blast flow path of the tuyere body (Fig. 7B); (6) When hydrogen is supplied into the hot blast flow path from one hydrogen injection port penetrating the upper wall of the tuyere body and also from one hydrogen injection lance arranged inside the hot blast flow path of the tuyere body (Fig. 7C); (7) For reference, when (2) above is used (Fig. 7D), the hydrogen concentration distribution in the furnace radial direction at a height of 12 m from the center of the tuyere in each of the above cases was confirmed. The flow rate of hydrogen gas supplied was 4,270 Nm3 for the two systems in total for the above cases (4) to (6). ３ / hr, and in the case of (7) above, 4270 Nm ３ / hr. Figure 8A shows the hydrogen concentration distribution in the case of (4), Figure 8B shows the hydrogen concentration distribution in the case of (5), Figure 8C shows the hydrogen concentration distribution in the case of (6), and Figure 8D shows the hydrogen concentration distribution in the case of (7).

[0046] 8A to 8D, it can be seen that supplying hydrogen gas through two systems reduces the bias in the hydrogen concentration distribution in the radial direction inside the blast furnace compared to supplying hydrogen gas through a single system. In particular, as shown in Fig. 8C, it can be seen that the bias in the hydrogen concentration distribution in the radial direction inside the blast furnace is minimized when both the hydrogen injection port and the hydrogen injection lance are used in combination.

[0047] 3. Hydrogen Concentration Distribution in the Raceway When the hydrogen concentration distribution in the raceway was confirmed using a simulation, it was found that when hydrogen was supplied into the hot blast flow path from each of the two hydrogen injection ports penetrating the upper wall of the tuyere body as described above (4), the hydrogen concentration in the upper space of the raceway was high, and when hydrogen was supplied from each of the two hydrogen injection lances arranged inside the hot blast flow path of the tuyere body as described above (5), the hydrogen concentration in the lower part of the raceway was high, while when hydrogen was supplied from both the hydrogen injection port and the hydrogen injection lance as described above (6), the hydrogen mixing in the raceway was improved. In other words, when the hydrogen injection port and the hydrogen injection lance are used together, it is possible to promote mixing of the air blown from the raceway with the hydrogen gas, and it is thought that the hydrogen concentration inside the blast furnace is made uniform.

[0048] From the above results, it can be said that a blast furnace having the following configurations (i) to (iv) can suppress bias in the reducing gas concentration distribution in the furnace radial direction inside the blast furnace when reducing gas is supplied into the interior of the blast furnace. (i) A hot blast tuyere of the blast furnace has a tuyere body, a reducing gas injection port, and a reducing gas injection lance. (ii) The tuyere body has a hot blast flow path. (iii) The reducing gas injection port penetrates the wall of the tuyere body. (iv) The reducing gas injection lance has an outlet in the hot blast flow path.

[0049] REFERENCE SIGNS LIST 100 Blast furnace 10 Hot blast tuyere 11 Tuyere body 11a Hot blast flow path 11ax Opening 12 Reducing gas injection port 12a Flow path 12ax Outlet 13 Reducing gas injection lance 13a Flow path 13ax Outlet 20 Reducing gas supply source 21 Reducing gas supply flow path

Claims

1. A blast furnace having a hot blast tuyere, the hot blast tuyere having a tuyere body, a reducing gas injection port, and a reducing gas injection lance, the tuyere body having a hot blast flow path, the reducing gas injection port penetrating a wall of the tuyere body, and the reducing gas injection lance having an outlet within the hot blast flow path.

2. A blast furnace according to claim 1, wherein the outlet of the reducing gas injection port faces the hot blast flow path.

3. A blast furnace according to claim 1 or 2, wherein the height position P of the center of the blowout opening of the reducing gas blowing port １ The height position P of the center of the opening of the tuyere body ２ and the height position P of the center of the outlet of the reducing gas injection lance is higher than ３ The height position P of the center of the opening of the tuyere body ２ A blast furnace located below.

4. A blast furnace according to any one of claims 1 to 3, wherein the reducing gas supplied from the reducing gas injection port and the reducing gas injection lance contains hydrogen gas.

5. A method for supplying a reducing gas to a blast furnace, comprising: supplying hot air into the interior of the blast furnace through a hot air tuyere of the blast furnace; and supplying a reducing gas into the interior of the blast furnace through a reducing gas injection port that penetrates a wall of a tuyere body of the hot air tuyere and a reducing gas injection lance that has an outlet within a hot air flow path of the hot air tuyere.

6. A method for supplying reducing gas to a blast furnace according to claim 5, wherein reducing gas is supplied from the outlet of the reducing gas injection port to the hot blast flow path.

7. A method for supplying reducing gas to a blast furnace according to claim 5 or 6, wherein the height position P of the center of the blowout opening of the reducing gas blowing port １ The height position P of the center of the opening of the tuyere body ２ and the height position P of the center of the outlet of the reducing gas injection lance is higher than ３ The height position P of the center of the opening of the tuyere body ２ A method of supplying reducing gas to a blast furnace located below the 8. A method for supplying a reducing gas to a blast furnace according to any one of claims 5 to 7, wherein the reducing gas contains hydrogen gas.

9. A tuyere for a blast furnace, comprising: a tuyere body; a reducing gas injection port; and a reducing gas injection lance, wherein the tuyere body has a hot blast flow path, the reducing gas injection port penetrates a wall of the tuyere body, and the reducing gas injection lance has an outlet within the hot blast flow path.

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