Blast furnace blower equipment and blast furnace operation method

Abstract

The blower assembly of the present invention comprises an outer flow hole disposed on the outermost side of the interior of the blower assembly and an inner flow hole disposed on the inner side of the outer flow hole, wherein the inner flow hole has two or more independent flow paths, and the two or more independent flow paths are spaced apart from the inner surface of the blower assembly. The method of operating a blast furnace according to the present invention utilizes the blower assembly of the blast furnace to blow a low-oxygen concentration gas, a high-oxygen concentration gas having a higher oxygen concentration than the low-oxygen concentration gas, and a reducing agent into the blast furnace from the blower assembly, blow the low-oxygen concentration gas from the outer flow hole, blow the high-oxygen concentration gas and the reducing agent from the inner flow hole, and blow the high-oxygen concentration gas and the reducing agent separately from the two or more independent flow paths.

Description

Technology Field

[0001] The present invention relates to a blower opening facility for a blast furnace and a method of operating the blast furnace using said blower opening facility. Background Technology

[0002] Recently, against the backdrop of global environmental issues, there is a strong demand for the reduction of carbon dioxide (CO2) emissions. Consequently, in the operation of blast furnaces installed within steel mills, it is required to reduce the amount of newly input carbon raw materials by improving reaction efficiency or recycling regenerated gas.

[0003] In a typical blast furnace, hot air (air heated to approximately 1200°C) is blown into the furnace from a tuyere as a blower gas. The oxygen in this hot air reacts with the carbon in the reducing agent, coke or pulverized coal, to produce carbon monoxide (CO) gas or hydrogen (H2) gas. The iron oxide in the iron ore charged into the furnace is reduced by these carbon monoxide and hydrogen gases, and carbon dioxide is generated through a reduction reaction in which oxygen is converted from iron oxide to carbon monoxide.

[0004] As a technology for reducing carbon dioxide emissions during the operation of a blast furnace that occurs in this way, a technology has been proposed to reduce the amount of newly introduced reducing agent by reforming carbon monoxide or carbon dioxide contained in byproduct gases emitted from a blast furnace, etc., to produce hydrocarbons such as methane or ethanol, and then introducing the produced hydrocarbons back into the blast furnace as reducing agents. As a technology to minimize the amount of newly introduced reducing agent into the blast furnace by maximizing the use of these regenerated reducing agents, for example, Patent Document 1 proposes using oxygen gas as a blower gas.

[0005] For injecting blowing gas into the blast furnace, a blower port formed on the lower side wall of the blast furnace body (1) shown in FIG. 1 is used. The blower port equipment of the blast furnace is constructed by assembling multiple parts, such as a blow pipe (2), a small blower port (3), an injection lance (4), a bending pipe (6), a straight pipe (7), a large blower port (8), and a blower port support metal fitting (9), as shown in FIG. 2, for example. Since the interior of the blower port is under high pressure conditions of about 400 kPa, the connecting parts of each part of the blower port are sealed to prevent leakage of the gas flowing inside.

[0006] In addition, as shown in FIG. 3, the leading portion of the blast furnace's tuyere is exposed to an environment where high-temperature molten pig iron and molten slag flow down along with high-temperature gas generated by the combustion of coke, etc. The blower gas blown into the coke-filled bed inside the blast furnace from the leading portion of the tuyere (3) causes the coke in front of the tuyere to swirl and burn due to its kinetic energy, forming a space of about 1m from the end of the tuyere to the inside of the furnace called a raceway (5). Due to the formation of the raceway (5), the location where the highest temperature of the combustion reaction occurs and the dropping area of ​​the high-temperature molten material fall from the leading portion of the tuyere to the inside of the blast furnace, thereby creating a state in which the heat load of the leading portion of the tuyere is suppressed.

[0007] As shown in Patent Documents 2 to 5, technologies have been developed to improve reaction efficiency by promoting stirring contact between an auxiliary reducing agent and oxygen. All of these are in the form of mixing an auxiliary reducing agent and a small amount of oxygen gas added as an auxiliary agent into the heated air from a blowing lance in an operation where the blowing gas is based on heated air. Prior art literature

[0008] International Publication No. 2021 / 106579 Pamphlet Japanese Published Patent Application No. Hei 6-330113 Japanese Published Patent Application No. Hei 11-12613 International Publication No. 2018 / 180892 Pamphlet Japanese Published Patent Application No. 2013-19006 The problem to be solved

[0009] In the conventional equipment configuration of the tuyeres' section of a blast furnace, if oxygen gas came into direct contact with the connection points of each tuyer's component, there was a slight possibility that highly oxidizing, high-oxygen concentration gas could leak from the connection points. Furthermore, if high-oxygen concentration gas leaked, there was a risk of causing operational troubles, such as equipment damage resulting from abnormal combustion.

[0010] The present invention, made in consideration of the above-mentioned problem, aims to provide a blast furnace blower facility capable of suppressing leakage of high oxygen concentration gas from a blower connection part in a blast furnace blower facility using a high oxygen concentration gas mainly composed of oxygen as a blower gas, and a method of operating a blast furnace using said blower facility. means of solving the problem

[0011] The gist of the present invention is as follows.

[0012] (1) The air outlet has an outer circulation hole positioned at the outermost peripheral side of the interior, and an inner circulation hole positioned at the inner peripheral side of the outer circulation hole.

[0013] The above inner flow passage has two or more independent flow paths, and

[0014] A blast furnace blower system characterized in that the above two or more independent channels are spaced apart from the inner surface of the blower.

[0015] (2) The above air outlet is equipped with a blower outlet and a blow pipe, and

[0016] An injection pipe is disposed inside the above air blower port and on the inner circumference side of the above blow pipe, spaced apart from the above air blower port, and

[0017] The outer flow hole is disposed between the above blower port and the above blow pipe and the above injection pipe, and

[0018] The blower opening of the blast furnace described in (1), wherein the inner flow hole is arranged inside the blower pipe.

[0019] (3) The joint between the blower and the blow pipe is a sliding butt fitting structure, the blower installation of the blast furnace described in (2).

[0020] (4) In the inner flow channel, at least one of the two or more independent flow channels has a constricted shape facing downstream, a blast furnace blower facility described in any one of (1) to (3).

[0021] (5) A blower opening facility of a blast furnace described in any one of (2) to (4), wherein the clearance between the blower opening and the blower pipe is 20% or more of the inner diameter of the blower opening.

[0022] (6) The above blower pipe is a blower pipe of a blast furnace described in any one of (2) to (5) having a water cooling mechanism.

[0023] (7) The blower pipe is connected to the blower pipe at the rear end of the blower pipe, and is a blower pipe facility of a blast furnace described in any one of (2) to (6).

[0024] (8) A blower opening for a blast furnace described in any one of (2) to (7), having a mixing promotion structure having a connecting section in which at least two of the two or more independent flow paths are connected at the outlet of the blower pipe.

[0025] (9) A method of operating a blast furnace using a blower opening facility of a blast furnace as described in any one of (1) to (8) above,

[0026] In the above blast furnace, a low-oxygen concentration gas, a high-oxygen concentration gas having a higher oxygen concentration than the low-oxygen concentration gas, and a reducing agent are blown in from the above tuyere, and

[0027] The above low-oxygen concentration gas is blown in from the above outer flow hole, and

[0028] The above high oxygen concentration gas and the above reducing agent are blown in from the inner circulation hole, and

[0029] A method of operating a blast furnace characterized by separately injecting the above high oxygen concentration gas and the above reducing agent from two or more independent flow paths.

[0030] (10) The gas flow rate of the high oxygen concentration gas is 180 m / s or more in the downstream part of the blower and 60 m / s or less in the upstream part of the blower, in the method of operating the blast furnace described in (9).

[0031] (11) The above reducing agent comprises at least one of blast furnace gas, coke oven gas, ammonia, carbon monoxide, hydrogen, methane, ethane, ethylene, acetylene, propane, propylene, propine, butane, butene, butyne, methanol, ethanol and dimethyl ether, in the method of operating a blast furnace as described in (9) or (10). Effects of the invention

[0032] According to the present invention, in a blower port facility of a blast furnace using a high oxygen concentration gas mainly composed of oxygen as a blower gas, a blower port facility of a blast furnace capable of suppressing leakage of the high oxygen concentration gas from a blower port connection part, and a method of operating the blast furnace using said blower port facility can be provided. Brief explanation of the drawing

[0033] Figure 1 is a schematic cross-sectional view illustrating the structure of a blast furnace. Figure 2 is a schematic cross-sectional view illustrating the structure of a conventional blast furnace air intake facility. Figure 3 is a drawing to explain the structure of the leading part of the blast furnace air intake facility. FIG. 4 is a schematic cross-sectional view for explaining the structure of a blower opening facility of a blast furnace according to one embodiment of the present invention. Figure 5 is a partial schematic cross-sectional view to explain the structure of the leading part of the air outlet equipment of Figure 4. FIG. 6a is a partial cross-sectional view showing a first example of a mixing-promoting structure. FIG. 6b is a partial cross-sectional view showing a second example of a mixing-promoting structure. FIG. 6c is a partial cross-sectional view showing a third example of a mixing-promoting structure. FIG. 6d is a partial cross-sectional view (left view) showing a fourth example of a mixing-promoting structure and a cross-sectional view (right view) orthogonal to the extension direction of the blower pipe. FIG. 6e is a partial cross-sectional view (left view) showing the fifth example of a mixing-promoting structure and a cross-sectional view orthogonal to the direction of the blower pipe (right view). Specific details for implementing the invention

[0034] (Form for carrying out the invention)

[0035] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0036] <Blast Furnace Air Inlet Equipment>

[0037] A blower port facility for a blast furnace according to one embodiment of the present invention will be described. The blower port facility of this embodiment is used in an operation for blowing blower gas (mainly using high oxygen concentration gas) and a reducing agent into the blast furnace.

[0038] The air outlet facility of the present embodiment may be an air outlet facility used in a blast furnace as shown in FIG. 1, for example. The air outlet facility is positioned on the lower side wall of the blast furnace body (1). FIG. 4 is a schematic cross-sectional view for explaining the structure of the air outlet facility of a blast furnace according to one embodiment of the present invention. FIG. 5 is a partial schematic cross-sectional view for explaining the structure of the leading portion of the air outlet facility of FIG. 4.

[0039] As shown in FIGS. 4 and 5, the air outlet equipment of the present embodiment is equipped with a blow pipe (2), a small air outlet (3), a bending pipe (6), a large air outlet (8), an air outlet receiving fitting (9), and an intake pipe (10). The air outlet equipment of the present embodiment is equipped with an air outlet, and the air outlet is equipped with a small air outlet (3), a blow pipe (2), and an intake pipe (10). In addition, a raceway (5) is formed at the end of the air outlet.

[0040] The blow pipe (2) is a pipe for guiding low-oxygen concentration gas derived from the bending pipe (6) to the blower port (3). It is preferable that the blow pipe (2) be made of a heat-resistant material. As shown in the illustration, the blow pipe (2) has its front end connected to the rear end of the blower port (3) inside the main blower port (8).

[0041] The blower port (3) is a pipe that guides the blowing gas guided from the blow pipe (2) into the furnace. The blower port (3) is positioned in a protruding state within the blast furnace and comes into direct contact with the atmosphere inside the blast furnace.

[0042] The bending pipe (6) is a pipe that directs the blowing gas to the blow pipe (2).

[0043] The bending pipe (6), the blow pipe (2), and the blower nozzle (3) are connected in this order. In this embodiment, the joint between the blower nozzle (3) and the blow pipe (2) is a sliding butt joint structure. That is, when joining the blower nozzle (3) and the blow pipe (2), instead of using a rigid connection such as a bolt fastening, each connection is configured as a sliding butt joint with a smooth spherical surface to firmly press them together, and when displacement of the blower nozzle (3) occurs, gas leakage prevention and displacement absorption are possible through the sliding motion of the spherical surface. Likewise, in this embodiment, the joint between the blow pipe (2) and the bending pipe (6) is also a sliding butt joint structure.

[0044] According to this configuration, even with thermal expansion and contraction caused by temperature fluctuations in the high-temperature region of the blast furnace exceeding 2000℃, displacement can be absorbed by the sliding motion of the spherical surface (while preventing gas leakage), thereby preventing damage to the equipment.

[0045] The large air blower (8) cantilever-supports the rear end of the small air blower (3) at its front end. The inner diameter of the front end of the large air blower (8) and the outer diameter of the rear end of the small air blower (3) are almost the same. The large air blower (8) and the small air blower (3) may be formed with a sliding butt joint structure as described above, or they may be fixed using fasteners such as bolts.

[0046] The air intake receiving member (9) supports the rear end of the large air intake (8) at its front end, thereby securely fixing the small air intake (3) and the large air intake (8) to the lower side wall of the blast furnace body (1). As shown in the illustration, the inner diameter of the front end of the air intake receiving member (9) and the outer diameter of the rear end of the large air intake (8) are nearly the same.

[0047] The blower pipe (10) is a pipe for blowing blower gas and reducing agent into the furnace. The blower pipe (10) is connected to the blower pipe (2) at the rear end of the blower pipe (2). In this embodiment, the blower gas mainly uses a high oxygen concentration gas.

[0048] As shown in FIGS. 4 and 5, the air blower system is equipped with an outer flow hole (13) positioned on the outermost side of the interior of the air blower and a blower pipe (10) positioned on the inner side of the outer flow hole (13). Inside the air blower (3), a blower pipe (10) is also positioned on the inner side of the blow pipe (2), spaced apart from the air blower (3). An outer flow hole (13) is positioned between the air blower (3), the blow pipe (2), and the blower pipe (10). An inner flow hole is positioned inside the blower pipe (10). The inner flow hole has two or more independent flow paths. In this example, the two or more independent flow paths are an intermediate flow path (12) positioned on the inner side of the outer flow path (13) and a central flow path (11) positioned on the inner side of the intermediate flow path (12). In this example, the two or more independent flow paths are double-walled pipe structures, but they may be triple-walled pipe structures or multi-walled pipe structures, or, for example, may be configured by arranging multiple single pipes.

[0049] The intermediate flow hole (12) and the central flow hole (11) are installed at any location outside the furnace from the tip of the blower, and the gas ejected from each flow hole at the tip of the blower pipe (10) is mixed gas and can be blown into the furnace.

[0050] The outer circulation hole (13) is a hole through which a low-oxygen concentration gas is circulated. "Low-oxygen concentration" refers to an oxygen concentration such that the equipment is not destroyed even when in contact with the air outlet equipment or surrounding equipment outside the air outlet, and for example, it is preferable for the oxygen concentration to be 35% or less (0 to 35%). The low-oxygen concentration gas may be, for example, air or other gases (such as nitrogen gas (even nitrogen gas that does not contain any oxygen)). Additionally, a reducing agent may be circulated through the outer circulation hole (13). Since the low-oxygen concentration gas and the reducing agent do not cause abnormal oxidation even at high temperatures, they may be heated to high temperatures and blown in.

[0051] The inner flow channel is a hole for circulating a high oxygen concentration gas or a reducing agent with a higher oxygen concentration than the low oxygen concentration gas (circulated by the outer flow channel (13)). "High oxygen concentration" is, for example, preferably an oxygen concentration of more than 35% (more than 35% and less than or equal to 100%). Since high oxygen concentration gas may cause abnormal oxidation of the flow channel piping if heated to a high temperature, it is preferable to circulate it at a temperature of 800°C or lower, and it is more preferable to circulate it at room temperature. The inner flow channel has at least two independent flow channels (in this example, two flow channels: the intermediate flow channel (12) and the central flow channel (11)) through which the high oxygen concentration gas and the reducing agent are circulated from separate flow channels. By allowing the high oxygen concentration gas and the reducing agent to flow from separate flow channels, it is possible to prevent operational troubles such as ignition and abnormal combustion within the flow channels.

[0052] The intermediate flow channel (12) is a hole for circulating high oxygen concentration gas, which has a higher oxygen concentration than the low oxygen concentration gas.

[0053] The central circulation hole (11) is a hole through which a reducing agent is circulated. As the reducing agent, a solid reducing agent or a gaseous reducing agent may be used. It is particularly preferable to use a gaseous reducing agent, and in this case, the reducing agent preferably includes at least one of blast furnace gas, coke oven gas, ammonia, carbon monoxide, hydrogen, methane, ethane, ethylene, acetylene, propane, propylene, propine, butane, butene, butyne, methanol, ethanol, and dimethyl ether. When using a solid reducing agent, granular reducing agents such as pulverized coal or waste plastic may be used.

[0054] Here, in the air outlet facility of the present embodiment, the two or more independent passages (in this example, the intermediate passage (12) and the central passage (11)) are spaced apart from the inner surface (15) of the air outlet. In this example, an outer passage (13), which is another passage (a passage for circulating low-oxygen concentration gas), is interposed between the two or more independent passages and the inner surface (15) of the air outlet.

[0055] The following describes the effects of the blower system of the blast furnace of the present embodiment.

[0056] The blower opening of the blast furnace in this embodiment is provided with an outer flow opening (13) positioned on the outermost side of the inside of the blower opening and an inner flow opening positioned on the inner side of the outer flow opening (13). The inner flow opening has two or more independent flow paths (in this example, an intermediate flow path (12) and a central flow path (11)), and the two or more independent flow paths are spaced apart from the inner surface (15) of the blower opening.

[0057] In this configuration, a low oxygen concentration gas is blown in from the outer flow channel (13), a high oxygen concentration gas and a reducing agent are blown in from the inner flow channel, and the high oxygen concentration gas and a reducing agent are blown in separately from the two or more independent flow channels. As a result, the flow channel through which the high oxygen concentration gas is blown in is spaced apart from the inner surface (15) of the air outlet, so the high oxygen concentration does not come into contact with the inner surface (15) of the air outlet (for example, even if it leaks from the flow channel, it comes into contact with the inner surface (15) of the air outlet after being mixed with the low oxygen concentration gas), and the leakage of the high oxygen concentration gas from the connection part of the air outlet component, which is prone to gas leakage, can be suppressed, thereby avoiding troubles such as equipment damage caused by abnormal combustion.

[0058] In this way, according to the blast furnace blower facility of the present embodiment, in a blast furnace blower facility that uses a high oxygen concentration gas mainly composed of oxygen as the blower gas, leakage of the high oxygen concentration gas from the blower connection part can be suppressed.

[0059] In particular, when the joint between the blower port (3) and the blow pipe (2) is a sliding butt joint structure, as described above, the effect of preventing damage to the equipment by absorbing displacement due to thermal expansion and contraction caused by temperature fluctuations is obtained, while the problem of leakage of high oxygen concentration gas from the connection part of the blower port component becomes significant. Therefore, in such cases, the configuration of the blower port equipment of this embodiment is particularly effective.

[0060] In addition, as described in the example, since the inner flow channel has two or more independent flow channels (in this example, the intermediate flow channel (12) and the central flow channel (11)), the high oxygen concentration gas and the reducing agent can be flowed from separate flow channels, thereby preventing operational troubles such as ignition and abnormal combustion within the flow channels.

[0061] As a specific configuration, the blower is provided with a blower (3) and a blow pipe (2), and a blowing pipe (10) is disposed spaced apart from the blower (3) and also on the inner side of the blow pipe (2) inside the blower (3). An outer flow hole (13) is disposed between the blower (3), the blow pipe (2), and the blowing pipe (10), and an inner flow hole is disposed inside the blowing pipe (10).

[0062] Here, when a high oxygen concentration gas is used as the blower gas for a blast furnace, the gas flow rate at the end of the blower port is reduced compared to the case of conventional air blowing by the amount of nitrogen not included in the blower. As a result, a raceway (5) of sufficient size is not formed, and the dropping area of ​​the high-temperature molten material approaches the tip of the blower port, which may cause frequent damage to the blower port. Therefore, in order to form a raceway (5) of sufficient size and suppress the heat load of the blower port, it is desirable to reduce the cross-sectional area of ​​the high oxygen concentration gas flow path and increase the discharge gas flow rate into the blast furnace. On the other hand, since the high oxygen concentration gas has high oxidizing power, if the cross-sectional area of ​​the high oxygen concentration gas flow path of the blower pipe (10) is simply reduced and the gas flows at a high velocity, there is a risk of causing damage to the piping equipment due to abnormal oxidation of the piping caused by friction.

[0063] Therefore, as shown in FIGS. 4 and 5, in the inner flow channel, it is preferable that at least one of the two or more independent flow channels (in this example, the intermediate flow channel (12)) has a contracted shape facing downstream.

[0064] By configuring it in this way, the flow velocity of the high oxygen concentration gas on the upstream side is not excessively large to prevent damage to the piping equipment, while on the downstream side, the flow velocity of the high oxygen concentration gas is sufficiently large to form a raceway of sufficient size to suppress the heat load of the air outlet and prevent damage to the air outlet.

[0065] More specifically, it is desirable to ensure that the flow velocity of the high oxygen concentration gas is 60 m / s or less in the upstream section and 180 m / s or more and 250 m / s or less in the downstream section. By keeping the oxygen flow velocity in the upstream section at 60 m / s or less, troubles such as abnormal oxidation of the piping due to friction can be suppressed, while, by keeping the flow velocity in the downstream section at 180 m / s or more, a raceway can be formed more reliably, and by keeping it at 250 m / s or less, the problem of the pipe pressure drop becoming excessively high and the inability to flow a sufficient amount of gas can be suppressed.

[0066] As an example, the "upstream section" can be positioned upstream of the tip of the blow pipe (2), and thus, the flow velocity of the high oxygen concentration gas can be set to 60 m / s or less at the upstream side of the tip of the blow pipe (2). Also, as an example, the "downstream section" can be positioned at the tip of the blower nozzle (3), and the flow velocity of the high oxygen concentration gas at that position can be set to 180 m / s to 250 m / s.

[0067] In order to achieve suitable high oxygen concentration gas flow rate conditions as described above, it is preferable that the hole through which the high oxygen concentration gas is circulated (in this example, the intermediate flow hole (12)) has a contracted shape facing downstream, as described above. In this example, as shown in the illustration, the intermediate flow hole (12) has a large cross-sectional area section on the upstream side and a small cross-sectional area section on the downstream side (which has a smaller cross-sectional area than the large cross-sectional area section), and the two are smoothly connected. It is preferable that the cross-sectional area of ​​the large cross-sectional area section be at least three times the cross-sectional area of ​​the small cross-sectional area section, and more preferable that it be at least four times. As shown in FIG. 5, the connection location (connection area) between the large cross-sectional area section and the small cross-sectional area section is preferably located inside the air blower (3) from the perspective of reducing the flow rate of the high oxygen concentration gas. In the urban example, the cross-sectional area of ​​each of the large area section and the small area section is nearly constant, but either or both of the large area section and the small area section may have a shape in which the cross-sectional area gradually decreases toward the downstream side.

[0068] The gas flow rate of the high oxygen concentration gas varies depending on the operating conditions of the blast furnace, but if the operating conditions are minor, there is no problem if the cross-sectional area of ​​the flow path is optimized as described above. However, if the operating conditions change significantly, it becomes impossible to maintain appropriate flow rate conditions with the same blower equipment. In that case, it is advisable to optimize the flow path cross-sectional area of ​​the high oxygen concentration gas flow path by changing the equipment. Since the cross-sectional area of ​​the flow path can be easily changed when using a detachable blower pipe (10), it is advisable to prepare blower pipes (10) of multiple shapes in anticipation of changes in operating conditions and to use them by appropriately switching them according to the operating conditions. In addition, in FIG. 5, if there is a concern that the blower nozzle (3) may be damaged due to the influence of high-temperature molten material, etc. (e.g., when the cooling water temperature of the blower nozzle rises abnormally), a low-oxygen concentration gas such as high-temperature air, reducing gas, or nitrogen gas may be flowed through the outer flow channel (13), and the cross-sectional area of ​​the flow path of the low-oxygen concentration gas may be reduced by adjusting the outer diameter of the tip of the blower pipe (10) and the inner diameter of the blower nozzle (3), and the discharge gas velocity of the blower nozzle may be increased to secure a large space for the raceway (5) shown in FIG. 3, thereby moving the dropping area of ​​the high-temperature molten material away from the tip of the blower nozzle toward the inside of the furnace. Accordingly, it is possible to reduce the heat load received by the tip of the blower nozzle (3).

[0069] Here, it is preferable that the clearance between the blower nozzle (3) and the blower pipe (10) (gap at the tip (see double arrow in FIG. 5)) be 20% or more of the inner diameter of the blower nozzle (3) (inner diameter at the tip).

[0070] The position of the blower (3) changes due to heat fluctuations inside the blast furnace or physical collisions caused by raw materials inside the blast furnace. At this time, the blower (3) and the blower pipe (10) are spaced apart, but if the displacement of the blower (3) is excessively large, there is a possibility that the blower (3) and the blower pipe (10) will come into contact. If the blower (3) and the blower pipe (10) come into contact, a large force is applied to the blower pipe (10) through which the high oxygen concentration gas flows, and there is a risk that the flow path of the high oxygen concentration gas will be damaged and the high oxygen concentration gas will leak. Therefore, in order to prevent the blower (3) from coming into contact with and being damaged by the blower pipe (10) when the blower (3) changes, it is appropriate to design the blower (3) with sufficient clearance between the inner surface (15) of the blower (3) and the blower pipe (10). Since it is assumed that the blower (3) may undergo a maximum displacement of 20% of the inner diameter of the blower (3) due to the influence of thermal expansion and contraction of surrounding equipment, the clearance between the blower (3) and the blower pipe (10) is preferably 20% or more of the inner diameter of the blower (3), and more preferably 30% or more. In order to secure the clearance between the blower (3) and the blower pipe (10) while also securing the appropriate conditions for the cross-sectional area of ​​the high oxygen concentration gas flow path, regarding the contraction shape of the high oxygen concentration gas flow path, the connection location (connection area) between the large area section and the small cross-sectional area section should be placed upstream of the blower (3), for example, inside the blow pipe (2), from the perspective of securing the above clearance. Accordingly, it becomes possible to sufficiently maintain the clearance between the blower (3) and the blower pipe (10) throughout the entire interior of the blower (3). In addition, from the perspective of achieving both the reduction of the flow rate of the high oxygen concentration gas and the securing of the above clearance, it is preferable that the connection location (connection area) between the large area section and the small area section be near the tip of the blow pipe (2).

[0071] It is preferable that the blower pipe (10) has a water cooling mechanism (14). In this example, the water cooling mechanism (14) is a hole through which cooling water can flow and is adjacent to the outer flow hole (13). In addition, in this example, the water cooling mechanism (14) has a forward path and a reverse path, and the forward path and the reverse path are separated by a wall. By installing such a water cooling mechanism (14), even if heated air is flowed through the outer flow hole (13), for example, the blower pipe (10) can be protected, and the effect of suppressing abnormal oxidation can be further enhanced.

[0072] As described in the example, the blower pipe (10) is connected to the blow pipe (2) at the rear end of the blow pipe (2). The blower pipe (10) attached to the rear end of the blow pipe (2) can be configured to be detachable by forming an attachment part. By appropriately replacing the blower pipe (10) with one in which the thickness of the flow path of each flow hole is appropriately set so as to have a flow path cross-sectional area that satisfies the appropriate conditions for gas flow rate, the gas flow rate conditions can be optimized even when the operating conditions of the blast furnace change.

[0073] In addition, it is preferable that the blower unit be equipped with a mixing-promoting structure that mixes the high oxygen concentration gas and the reducing agent inside the blower pipe (10). Such a mixing-promoting structure preferably has a connecting section in which at least two of the two or more independent flow paths are connected at the outlet of the blower pipe. Accordingly, by promoting the mixing of the high oxygen concentration gas and the reducing agent and mixing them inside the blower pipe (10), the combustibility of the reducing agent can be improved. Since the gas volume increases due to combustion expansion when the combustibility of the reducing agent is improved, the size of the raceway (5) can be further increased, making it possible to further suppress the thermal load of the blower unit. In particular, it is preferable to form such a mixing-promoting structure at the tip of the blower pipe (10).

[0074] Figures 6a to 6e show specific examples of mixing-promoting structures.

[0075] In the example shown in FIG. 6a, the flow path of the injection pipe (10) is made into a double pipe structure. As described above, the outer side can be made into an intermediate flow hole (12) and the inner side into a central flow hole (11). At this time, as shown in the illustration, the tip of the pipe (inner pipe of the double pipe) placed at the boundary between the central flow hole (11) and the intermediate flow hole (12) is positioned upstream of the tip of the injection pipe (10). With this configuration, the mixing of the reducing agent flowing into the central flow hole (11) and the high oxygen concentration gas flowing into the intermediate flow hole (12) is initiated at the upstream side of the injection pipe (10), thereby promoting the mixing of the reducing agent and the high oxygen concentration gas inside the injection pipe (10).

[0076] In the example shown in Fig. 6b, in addition to the structure shown in Fig. 6a, a taper is formed on the inner surface of the outer circumference of the inner tube of the double tube, with the diameter narrowing towards the downstream side. With this configuration, the outer flow (high oxygen concentration gas) collides inwardly with the inner flow (reducing agent), thereby further promoting the mixing of the outer flow and the inner flow.

[0077] In the example shown in Fig. 6c, in addition to the structure shown in Fig. 6a, the outer surface of the tip of the inner tube of the double tube is cut so that the outer flow path expands toward the downstream side. With this configuration, the outer flow collides inwardly with the inner flow, thereby further promoting the mixing of the outer and inner flows.

[0078] In the examples shown in FIG. 6d and FIG. 6e, in addition to the structure shown in FIG. 6a, the outer flow path is made porous by blocking a portion of the outer flow path (4 to 8 locations in the circumferential direction) (8 locations in the example of FIG. 6d, and 4 locations in the example of FIG. 6e). Accordingly, turbulence is enhanced, and the mixing of the outer flow and the inner flow is further promoted. Furthermore, by forming a through hole connecting the central flow hole (11) and the intermediate flow hole (12) in the inner tube of the double pipe at a location upstream of the part where the flow path is blocked, the mixing of the outer flow and the inner flow can be further promoted. Also, in the examples of FIG. 6d and FIG. 6e, the locations where the flow path is blocked are spaced at equal intervals around the circumference, but the flow path can also be blocked at different intervals around the circumference.

[0079] <Blast Furnace Operation Method>

[0080] Next, a method for operating a blast furnace according to one embodiment of the present invention will be described. The method for operating a blast furnace according to this embodiment can be implemented, for example, in a blast furnace equipped with a blower facility of the embodiment described above. Since an embodiment of such a blower facility has already been described, a further description will be omitted.

[0081] In the method of operating a blast furnace of the present embodiment, a low oxygen concentration gas, a high oxygen concentration gas with a higher oxygen concentration than the low oxygen concentration gas, and a reducing agent are blown into the blast furnace from a blower port, the low oxygen concentration gas is blown in from an outer flow port (13), the high oxygen concentration gas and the reducing agent are blown in from an inner flow port, and the high oxygen concentration gas and the reducing agent are blown in separately from two or more independent flow paths (for example, an intermediate flow port (12) and a central flow port (11)).

[0082] According to the method of operating a blast furnace of the present embodiment, the flow path through which the high oxygen concentration gas is blown is spaced apart from the inner surface (15) of the blower port, so that the high oxygen concentration gas does not come into contact with the inner surface (15) of the blower port (for example, even if it leaks from the flow path, it comes into contact with the inner surface (15) of the blower port after being mixed with the low oxygen concentration gas), thereby suppressing the leakage of the high oxygen concentration gas from the connection part of the blower port component where gas leakage is likely to occur, and thus avoiding troubles such as equipment damage caused by abnormal combustion.

[0083] Thus, according to the method of operating a blast furnace of the present embodiment, in a blast furnace blower facility that uses a high oxygen concentration gas mainly composed of oxygen as the blower gas, leakage of the high oxygen concentration gas from the blower connection part can be suppressed.

[0084] In particular, when the joint between the blower port (3) and the blow pipe (2) is a sliding butt joint structure, as described above, the effect of preventing damage to the equipment by absorbing displacement due to thermal expansion and contraction caused by temperature fluctuations is obtained, while the problem of leakage of high oxygen concentration gas from the connection part of the blower port becomes significant. Therefore, in such cases, the method of operating the blast furnace of this embodiment is particularly effective.

[0085] In addition, as described in the example, since the inner flow channel has two or more independent flow channels (in this example, the intermediate flow channel (12) and the central flow channel (11)), the high oxygen concentration gas and the reducing agent can be flowed from separate flow channels, thereby preventing operational troubles such as ignition and abnormal combustion within the flow channels.

[0086] As described above, it is desirable to ensure that the flow rate of the high oxygen concentration gas is 60 m / s or less in the upstream section and 180 m / s or more and 250 m / s or less in the downstream section. By keeping the oxygen flow rate in the upstream section at 60 m / s or less, troubles such as abnormal oxidation of the piping due to friction can be suppressed, and on the other hand, by keeping the flow rate in the downstream section at 180 m / s or more, a raceway (5) can be formed more reliably, and by keeping it at 250 m / s or less, the pipe pressure drop can be kept from becoming excessively high and preventing a sufficient amount of gas from flowing.

[0087] As an example, the upstream section can be positioned upstream of the tip of the blow pipe (2), and thus, the flow velocity of the high oxygen concentration gas upstream of the tip of the blow pipe (2) can be 60 m / s or less. Also, as an example, the downstream section can be positioned at the tip of the blower nozzle (3), and the flow velocity of the high oxygen concentration gas at said position can be 180 m / s to 250 m / s.

[0088] As with the above, in the method of the present embodiment, a solid reducing agent or a gaseous reducing agent may be used as the reducing agent. It is particularly preferable to use a gaseous reducing agent, and in this case, the reducing agent preferably comprises at least one of blast furnace gas, coke oven gas, ammonia, carbon monoxide, hydrogen, methane, ethane, ethylene, acetylene, propane, propylene, propine, butane, butene, butyne, methanol, ethanol, and dimethyl ether. When using a solid reducing agent, granular reducing agents such as pulverized coal or waste plastic may be used. Explanation of the symbols

[0089] 1: Therefore, Roche, 2: Blowpipe, 3: Lawsuit blower, 4: Blowing Lance, 5: Raceway, 6: Bent pipe, 7: Intuition, 8: Large air vent, 9: Air vent receiving fitting, 10: Intake pipe, 11: Central distribution channel, 12: Intermediate distributor, 13: External circulation hole, 14: Water cooling devices, 15: Inner surface of the air vent

Claims

Claim 1 A blast furnace blower system characterized by having an outer flow hole disposed on the outermost side of the interior of the blower and an inner flow hole disposed on the inner peripheral side of the outer flow hole, wherein the inner flow hole has two or more independent flow paths and the two or more independent flow paths are spaced apart from the inner surface of the blower. Claim 2 A blast furnace blower facility according to claim 1, wherein the blower is provided with a small blower and a blow pipe, and an injection pipe is disposed spaced apart from the small blower and on the inner circumference side of the blow pipe, and an outer flow hole is disposed between the small blower and the blow pipe and the injection pipe, and an inner flow hole is disposed inside the injection pipe. Claim 3 In paragraph 2, the joint between the blower port and the blow pipe is a sliding butt fitting structure, in the blower port facility of a blast furnace. Claim 4 A blower opening facility of a blast furnace according to any one of claims 1 to 3, wherein, in the inner flow passage, at least one of the two or more independent flow passages has a constricted shape facing downstream. Claim 5 A blast furnace blower facility according to Article 2 or Article 3, or Article 4 dependent on Article 2 or Article 3, wherein the clearance between the blower port and the blower pipe is 20% or more of the inner diameter of the blower port. Claim 6 Paragraph 2, Paragraph 3, or Paragraph 5, or Paragraph 4 dependent on Paragraph 2 or 3, wherein the blower pipe is a blower opening facility of a blast furnace having a water cooling mechanism. Claim 7 Paragraph 2 or 3 or 5 or 6, or Paragraph 4 dependent on Paragraph 2 or 3, wherein the blower pipe is connected to the blow pipe at the rear end of the blow pipe, a blower opening facility of a blast furnace. Claim 8 A blower opening facility of a blast furnace having a mixing-promoting structure having a conduction section connecting at least two of the two or more independent flow paths at the outlet section of the blower pipe, wherein, in the case of Article 2 or Article 3 or Article 5 or Article 6 or Article 7, or Article 4 dependent on Article 2 or Article 3. Claim 9 A method of operating a blast furnace using a blower port facility of a blast furnace described in any one of claims 1 to 8, wherein, in the blast furnace, a low-oxygen concentration gas, a high-oxygen concentration gas having a higher oxygen concentration than the low-oxygen concentration gas, and a reducing agent are blown in from the blower port, the low-oxygen concentration gas is blown in from the outer flow port, the high-oxygen concentration gas and the reducing agent are blown in from the inner flow port, and the high-oxygen concentration gas and the reducing agent are blown in separately from two or more independent flow paths. Claim 10 A method of operating a blast furnace according to claim 9, wherein the gas flow rate of the high oxygen concentration gas is 180 m / s or more in the downstream portion of the blower port and 60 m / s or less in the upstream portion of the blower port. Claim 11 A method of operating a blast furnace according to claim 9 or 10, wherein the reducing agent comprises at least one of blast furnace gas, coke oven gas, ammonia, carbon monoxide, hydrogen, methane, ethane, ethylene, acetylene, propane, propylene, propine, butane, butene, butyne, methanol, ethanol, and dimethyl ether.

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