Blast Furnace Accessories and Operation Methods

Abstract

The blast furnace operation method of the present invention involves blowing in blast gas and reducing materials through the tuyeres; the reducing materials contain a hydrocarbon-hydrogen mixture; the blast furnace operation method includes: preheating the hydrocarbon-hydrogen mixture to generate a high-temperature hydrocarbon-hydrogen mixture; and blowing the high-temperature hydrocarbon-hydrogen mixture through the tuyeres of the blast furnace. The blast furnace equipment of the present invention includes: a preheating device for preheating the hydrocarbon-hydrogen mixture to generate a high-temperature hydrocarbon-hydrogen mixture; and a blowing device having a hydrocarbon-hydrogen mixture supply section for introducing the high-temperature hydrocarbon-hydrogen mixture into the tuyeres.

Description

[Technical Field]

[0001] This invention relates to an auxiliary device for a blast furnace and a method for operating a blast furnace. [Previous Technology]

[0002] In recent years, against the backdrop of global environmental issues, there has been a strong demand to reduce carbon dioxide (CO2) emissions. Therefore, the operation of blast furnaces located in ironmaking plants is also required to be carried out at a low reducing feed ratio (low RAR).

[0003] In a typical blast furnace, hot air (air heated to approximately 1200°C) is blown into the furnace through the tuyeres as the blast gas. Thereupon, the oxygen in the hot air reacts with the coke or pulverized coal used as reducing materials to produce carbon monoxide (CO) gas or hydrogen (H2) gas. This carbon monoxide or hydrogen gas reduces the iron ore charged into the blast furnace. Furthermore, carbon dioxide is produced during the reduction reaction of the iron ore. Additionally, the blast gas system, which blows gas into the blast furnace through the tuyeres, plays a role in gasifying the pulverized coal or coke within the blast furnace.

[0004] As a technology for reducing carbon dioxide emissions during the operation of such a blast furnace, the following technology has been proposed: the carbon monoxide or carbon dioxide contained in the by-product gas discharged from the blast furnace is modified to generate hydrocarbons such as methane or ethanol, and the generated hydrocarbons are reintroduced into the blast furnace as reducing materials.

[0005] For example, Patent Document 1 discloses "an operating method of a blast furnace, characterized by comprising: step (A), which is to separate and recover CO2 and / or CO from a mixed gas containing CO2 and / or CO; step (B), which is to add hydrogen to the CO2 and / or CO separated and recovered in step (A) to convert CO2 and / or CO into CH4; step (C), which is to separate and remove H2O from the gas that has passed through step (B); and step (D), which is to blow the gas that has passed through step (C) into the blast furnace".

[0006] Patent document 2 discloses "a blast furnace operation method, characterized in that: CO2 is separated from the exhaust gas of a combustion furnace that uses blast furnace gas as part or all of the fuel, the separated CO2 is converted into methane, and the obtained reducing gas is blown into the blast furnace".

[0007] Patent document 3 discloses "a method of operating a blast furnace, comprising: a step of generating regenerated methane gas from by-product gas discharged from the blast furnace; and a step of blowing air gas and reducing raw materials into the blast furnace from the tuyeres of the blast furnace; wherein the method of operating the blast furnace uses oxygen as the air gas, and at least a portion of the reducing raw materials uses the regenerated methane gas".

[0008] Patent document 4 discloses "a method of operating a blast furnace, comprising: a step of generating regenerated methane gas using by-product gas discharged from the blast furnace; and a step of blowing air gas and reducing raw materials into the interior of the blast furnace from the tuyeres of the blast furnace; wherein the method of operating the blast furnace uses oxygen as the air gas, and at least a portion of the reducing raw materials uses the regenerated methane gas, and the oxygen and / or the regenerated methane gas are preheated before being blown into the interior of the blast furnace from the tuyeres of the blast furnace".

[0009] Non-Patent Document 1 discloses the structure of a blast furnace simulation model capable of reproducing the operating state of a blast furnace. [Prior Art Documents] [Patent Documents]

[0010] Patent Document 1: Japanese Patent Application Publication No. 2011-225969; Patent Document 2: Japanese Patent Application Publication No. 2014-005510; Patent Document 3: International Publication No. 2021 / 106578; Patent Document 4: International Publication No. 2021 / 131866 [Non-Patent Documents]

[0011] Non-patent literature 1: Sato et al., Kawasaki Steel Technical Bulletin, vol.29 (1997), pp.30-36 [Summary of the Invention]

[0012] (Problem to be solved by the invention) In the technologies of Patent Documents 1 and 2, if the amount of methane blown into the blast furnace as a reducing agent becomes a certain amount or more, it may sometimes cause operational failures such as insufficient heat transfer in the lower part of the blast furnace, increased pressure loss, and poor slag discharge. Therefore, in order to achieve stable operation, it is necessary to limit the amount of methane blown in, thereby limiting the effect of reducing carbon dioxide emissions.

[0013] In the technology of Patent Document 3, oxygen is used instead of hot air (hot blast) as the blower gas. Hereinafter, a general blast furnace using hot blast as the blower gas will be referred to as a hot blast furnace, and a blast furnace using oxygen as the blower gas will be referred to as an oxygen blast furnace. In the technology of Patent Document 3, by using an oxygen blast furnace instead of a hot blast furnace, the temperature at the tuyeres can be appropriately controlled even when a large amount of methane is blown in, thereby significantly reducing carbon dioxide emissions. However, the requirements for suppressing carbon dioxide emissions have been significantly increased, and it is difficult to obtain a carbon dioxide reduction effect sufficient to meet these requirements.

[0014] Furthermore, in the technology of Patent Document 4, oxygen, instead of hot air (hot blast), is used as the blower gas, and the oxygen and / or regenerated methane gas are preheated before being blown into the blast furnace from the tuyeres. In the technology of Patent Document 4, by preheating the oxygen and / or regenerated methane gas, the amount of heat required by the blast furnace for burning carbon such as coke is replaced by the sensible heat of the oxygen and / or regenerated methane gas, thus reducing the amount of carbon burned and significantly reducing carbon dioxide emissions. However, if methane is heated to a high temperature, thermal decomposition will occur, carbon will be released and adhere to the piping, causing piping blockage and operational instability. Therefore, in order to achieve stable operation, it is not easy to preheat the regenerated methane gas to a high temperature, and the heat that can be supplied as the sensible heat of methane gas is also limited. As a result, it is difficult to obtain a carbon dioxide reduction effect sufficient to meet social needs.

[0015] This invention was developed in view of the above-mentioned situation, and its purpose is to provide an operation method for a blast furnace and auxiliary equipment for the blast furnace, which can suppress the thermal decomposition of hydrocarbons and further reduce the emission of carbon dioxide from the blast furnace. (Technical means to solve the problem)

[0016] The inventors have repeatedly conducted intensive research in order to achieve the above-mentioned objective. As a result, they discovered that by preheating a mixed gas containing hydrocarbons and hydrogen and then blowing it into the vent, the reducing material blown into the vent can be preheated to a high temperature, and the thermal decomposition of hydrocarbons such as methane can also be suppressed.

[0017] The main structure of the present invention is as follows. (1) A method of operating a blast furnace, wherein air gas and reducing material are blown in from the tuyeres; characterized in that: the reducing material contains a hydrocarbon-hydrogen mixed gas, and the method of operating the blast furnace includes: a step of preheating the hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas, and a step of blowing the high-temperature hydrocarbon-hydrogen mixed gas in from the tuyeres of the blast furnace.

[0018] (2) The blast furnace operation method described in (1) above, wherein the hydrocarbon-hydrogen mixed gas is a methane-hydrogen mixed gas.

[0019] (3) The blast furnace operation method described in (1) or (2) above, wherein the amount of hydrogen contained in the hydrocarbon-hydrogen mixture is 10% or more and 80% or less by volume relative to the total amount of hydrocarbon and hydrogen.

[0020] (4) The blast furnace operation method described in any one of (1) to (3) above, wherein at least a portion of the hydrocarbon-hydrogen mixed gas is a regenerated hydrocarbon gas synthesized by using blast furnace gas discharged from the blast furnace as raw material.

[0021] (5) The blast furnace operation method described in any of (1) to (4) above, wherein the ratio of hydrocarbons from the regenerated hydrocarbon gas to the hydrocarbons contained in the hydrocarbon-hydrogen mixture is 80% by volume or more.

[0022] (6) The blast furnace operation method described in any of (1) to (5) above, wherein more than 90% by volume of the hydrocarbon-hydrogen mixed gas is preheated before being blown into the blast furnace from the tuyeres.

[0023] (7) The blast furnace operation method described in any of (1) to (6) above, wherein the preheating temperature of the hydrocarbon-hydrogen mixed gas is 500°C or higher.

[0024] (8) The blast furnace operation method described in any of (1) to (7) above, wherein the air supply gas is oxygen with an oxygen concentration of 80% or more by volume.

[0025] (9) The blast furnace operation method described in any one of (1) to (8) above, wherein the ratio of the amount of the hydrocarbon-hydrogen mixed gas blown in to the amount of the reducing material blown in is 90 wt% or more.

[0026] (10) A blast furnace auxiliary equipment, characterized in that it comprises: a preheating device for preheating the aforementioned hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas; and a blowing device having a hydrocarbon-hydrogen mixed gas supply section for introducing the aforementioned high-temperature hydrocarbon-hydrogen mixed gas into a tuyer. (11) The blast furnace auxiliary equipment as described in (10) above further comprises a mixing device for mixing hydrocarbon gas and hydrogen gas to generate a hydrocarbon-hydrogen mixed gas. (Effects compared to prior art)

[0027] According to the present invention, a method for operating a blast furnace and blast furnace auxiliary equipment can be provided, which can suppress the thermal decomposition of hydrocarbons and further reduce the emission of carbon dioxide from the blast furnace.

Implementation Method

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. For convenience, embodiments of the equipment attached to the blast furnace will be described first.

[0030] <Blast Furnace Auxiliary Equipment> Figure 1A is a schematic diagram showing the configuration of a blast furnace equipped with blast furnace auxiliary equipment according to one embodiment of the present invention. As shown in Figure 1A, the blast furnace 1 includes a tuyer 2 and blast furnace auxiliary equipment. The blast furnace auxiliary equipment of this embodiment includes: a mixing device 10, a preheating device 11, and a blowing device 3. In this example, the blast furnace auxiliary equipment further includes: a first dehydration device 4, a preheated gas generation device for the furnace body 5, a preheated gas blowing device for the furnace body 6, a CO2 separation device 7, a regenerated hydrocarbon gas synthesis device 8, and a second dehydration device 9.

[0031] As blast furnace 1, ordinary materials can be used. In this example, blast furnace 1 includes: a furnace body for charging raw materials, and tuyeres 2 for blowing blast gas and reducing materials into the furnace body. In the furnace body, sintered ore, iron ore, coke, and granular materials (hereinafter also referred to as ore raw materials) are charged from the top of the furnace (not shown). In this invention, as shown in this example, blast furnace 1 is preferably an oxygen blast furnace. In other words, it is preferable to use oxygen as the blast gas. When hot air (air heated to about 1200°C) is used as the blast gas, since the combustion gas contains about 50% by volume nitrogen which does not contribute to the combustion reaction, the flame temperature in the tuyeres is not likely to reach a high temperature. Therefore, if a large amount of reducing materials containing hydrocarbons such as methane is blown in, there is a risk of a decrease in the flame temperature (hereinafter also referred to as the tuyeres front temperature) in the tuyeres front area, leading to operational malfunctions. On the other hand, by using oxygen as the blast gas, the mixing of nitrogen, which is not conducive to the combustion reaction, can be suppressed, thus allowing for a higher tuyere tip temperature compared to using hot blast. Furthermore, as described below, by preheating the reducing material containing hydrocarbons such as methane to a high temperature, the tuyere tip temperature can also be increased. Through these two effects, the tuyere tip temperature can be maintained at a suitable range of 2000°C or higher, enabling stable operation. However, in this invention, the blast furnace is not limited to an oxygen-blast furnace; it can also be a hot blast furnace.

[0032] The tuyeres 2 are used to blow blast gas and reducing materials into the furnace body. The tuyeres 2 are located on the lower side wall of the blast furnace body. If blast gas and reducing materials are blown in through the tuyeres 2, a wind path zone is formed in front of the tuyeres 2. The blast gas system blown into the blast furnace 1 through the tuyeres can play a role in gasifying the injected reducing materials or coke in the blast furnace 1. The carbon monoxide gas or hydrogen gas produced by the reaction of the blast gas with the reducing materials or coke is used to reduce the ore raw materials charged into the blast furnace 1 to produce molten iron. The tuyeres 2 can be composed of blowing pipes, small tuyeres, large tuyeres, and bends.

[0033] The blowing device 3 is a device for introducing at least the reducing material (in this example, the reducing material and oxygen as the blower gas) into the tuyeres 2 of the blast furnace 1. In this embodiment, the reducing material contains a hydrocarbon-hydrogen mixture. The blowing device 3 has a hydrocarbon-hydrogen mixture supply section, which introduces the high-temperature hydrocarbon-hydrogen mixture (for example, preheated methane-hydrogen mixture) used as the reducing material into the tuyeres 2. In this example, it also has a blower gas supply section, which is configured to introduce blower gas (in this example, oxygen) into the tuyeres 2.

[0034] Figure 2A is a schematic diagram showing an example of the blowing device 3. In the example shown in Figure 2A, the blowing device 3 has a coaxial multi-tube configuration, which has a central tube 31 and an outer tube 33. The internal flow path of the central tube 31 is a hydrocarbon-hydrogen mixed gas supply section (path), which introduces a high-temperature hydrocarbon-hydrogen mixed gas (in an example, a preheated methane-hydrogen mixed gas). Furthermore, the annular pipe between the central tube 31 and the outer tube 33 is a supply air gas supply section (path), which introduces supply air gas (in this example, oxygen).

[0035] Figure 2B is a schematic diagram showing another example of the blowing device 3. In the example shown in Figure 2B, the blowing device 3 has a coaxial multi-tube configuration, which includes a central tube 31, an outer tube 33, and an inner tube 32 disposed between the central tube 31 and the outer tube 33. The inner flow path of the central tube 31 is a solid supply section (path), which introduces other blown-in reducing materials such as pulverized coal or waste plastic. Furthermore, the annular pipe between the central tube 31 and the outer tube 33 is a hydrocarbon-hydrogen mixed gas supply section (path), which introduces a high-temperature hydrocarbon-hydrogen mixed gas (for example, a preheated methane-hydrogen mixed gas). Furthermore, the annular pipe between the inner tube 32 and the outer tube 33 is a supply air gas supply section (path), which introduces supply air gas (in this example, oxygen).

[0036] Furthermore, when room temperature oxygen is used as the air supply gas, the flammability becomes poor. Therefore, it is preferable to make the ejection part of the outer pipe of the oxygen air supply gas supply section (path) constituting the blowing device 3 into a porous structure to promote the mixing of the oxygen air supply gas and the blown-in reducing material.

[0037] The first dehydration device 4 is a device for removing condensate. That is, during the reduction process of the ore raw material, carbon dioxide is generated. This carbon dioxide, along with unreacted carbon monoxide or hydrogen, is discharged as a byproduct gas from the top of the blast furnace. The top of the blast furnace is under high pressure conditions of approximately 2 to 4 atmospheres. Therefore, the blast furnace gas, as a byproduct gas discharged from the top of the blast furnace, expands and cools upon returning to atmospheric pressure, causing water vapor to condense, thus producing condensate. The first dehydration device 4 can remove this condensate.

[0038] The preheating gas generating device 5 for the furnace body is a device that generates preheating gas (hereinafter referred to as "preheating gas for the furnace body") to be blown into the furnace body of the blast furnace 1. Furthermore, if the oxygen concentration in the blast gas increases, the amount of gas in the furnace decreases, and the possibility of insufficient heating of the charge in the upper part of the blast furnace is higher. In this case, by blowing preheating gas into the furnace body of the blast furnace 1, the heating inside the furnace can be promoted. Therefore, in this embodiment, for example, a portion of the blast furnace gas downstream of the first dehydration device 4 is heated to, for example, 800°C to 1000°C using the preheating gas generating device for the furnace body, and then blown into the furnace body of the blast furnace by the preheating gas blowing device for the furnace body to promote the heating inside the furnace. Here, the preheating method for the preheating gas generating device 5 for the furnace body is not particularly limited. It can be: a method of partially burning a portion of the blast furnace gas using a burner, or a method of indirect heating using heat exchange with an electric heater. The preheating gas for the furnace body is not necessarily limited to the gas from which the blast furnace gas has been heated. For example, it can also be generated by preheating hydrogen, carbon monoxide, nitrogen, etc. supplied from the outside. On the other hand, in this invention, the blast furnace is not limited to a blast furnace with oxygen supply, but can also be a hot blast blast furnace with a lower oxygen concentration in the supply air. Therefore, it may not necessarily have a device for blowing preheating gas into the furnace body.

[0039] The furnace body preheating gas blowing device 6 is a device that blows the aforementioned furnace body preheating gas into the blast furnace 1. For example, as described above, it can be configured to blow a portion of the blast furnace gas downstream of the preheated first dehydration device 4 into the furnace body of the blast furnace 1. When the lower end of the belly of the blast furnace 1 is set to 0 and the height from the lower end of the belly to the charge line is set to 1, the blowing height of the furnace body preheating gas is ideally 0.5 or less. If the blowing position is set higher, the distance for heat exchange between the furnace body preheating gas and the raw materials in the furnace is shorter, and the heating effect obtained by the furnace body preheating gas cannot be fully obtained.

[0040] The regenerated hydrocarbon gas synthesis apparatus 8 is an apparatus that uses at least a portion of the blast furnace gas to synthesize regenerated hydrocarbon gas. In this embodiment, the regenerated hydrocarbon gas synthesis apparatus 8 is configured to generate regenerated hydrocarbon gas (in this example, regenerated methane gas). In this example, if at least a portion of the blast furnace gas is introduced into the regenerated hydrocarbon gas synthesis apparatus 8, the carbon dioxide and carbon monoxide contained in the blast furnace gas will react with hydrogen in the regenerated hydrocarbon gas synthesis apparatus 8 to generate regenerated hydrocarbon gas (in this example, regenerated methane gas). On the other hand, in this invention, the hydrocarbon gas (in this example, methane gas) may also be externally prepared hydrocarbon gas (in this example, external methane gas), therefore the blast furnace auxiliary equipment of this invention may not necessarily have a regenerated hydrocarbon gas synthesis apparatus 8.

[0041] The hydrogen used to generate regenerated hydrocarbon gas (e.g., regenerated methane gas) can be supplied from an external source. Preferably, the hydrogen is generated using a method that minimizes the production of carbon dioxide, such as water electrolysis. Furthermore, examples of externally supplied hydrogen include: hydrogen produced by reforming hydrocarbons such as natural gas using steam reforming; hydrogen obtained by gasifying liquefied hydrogen; and hydrogen produced by dehydrogenating organic hydrides.

[0042] Furthermore, the hydrogen used to generate the regenerated hydrocarbon gas (e.g., regenerated methane gas) may not be a gas with a hydrogen concentration of 100% by volume. However, in order to improve the purity of the hydrocarbons in the generated regenerated hydrocarbon gas, it is preferable to use a gas with a higher hydrogen concentration, specifically, hydrogen gas with a hydrogen concentration of 80% by volume or more. More preferably, the hydrogen concentration is 90% by volume or more, and even more preferably 95% by volume or more. The hydrogen concentration may also be 100% by volume. Examples of residual gases other than hydrogen include CO or CO2, H2S, CH4, N2, etc.

[0043] Figure 1B is a schematic diagram showing the configuration of a blast furnace with a variation of the blast furnace auxiliary equipment. The CO2 separation unit 7 is a device that separates only carbon dioxide gas from the blast furnace gas. In the example shown in Figure 1B, only the carbon dioxide gas separated from the blast furnace gas by the CO2 separation unit 7 is introduced into the regenerated hydrocarbon gas synthesis unit 8. This reduces the volume of gas fed into the regenerated hydrocarbon gas synthesis unit 8, thereby miniaturizing the regenerated hydrocarbon gas synthesis unit 8. In this case, for example, as shown in Figure 1B, the residual gas after separating carbon dioxide gas from the blast furnace gas (hereinafter also referred to as "separated residual gas") can be combined with the blast furnace gas supply pipeline to the ironmaking plant. Furthermore, the separated residual gas mainly contains carbon monoxide and hydrogen, and sometimes contains nitrogen or argon, etc.

[0044] The second dehydration unit 9 is a device for removing condensate from the regenerated hydrocarbon gas (in this example, regenerated methane gas). By cooling the regenerated hydrocarbon gas (in this example, regenerated methane gas) generated in the regenerated hydrocarbon gas synthesis unit 8 to below the boiling point of water, the water vapor in the regenerated hydrocarbon gas condenses. According to the second dehydration unit 9, the condensate in this regenerated hydrocarbon gas can be removed.

[0045] In this invention, the CO2 separation device 7, the regenerated hydrocarbon gas synthesis device 8, and the second dehydration device 9 do not necessarily have to be adjacent to the blast furnace 1. For example, the following regenerated hydrocarbon gas can also be used, which is supplied to the outside of the blast furnace gas, and carbon dioxide is separated from the blast furnace gas by the external CO2 separation device 7, and then generated by reacting carbon dioxide with hydrogen supplied from the outside in the external regenerated hydrocarbon gas synthesis device 8.

[0046] The mixing device 10 is an apparatus for mixing hydrocarbon gas and hydrogen gas to generate a hydrocarbon-hydrogen mixed gas. The hydrocarbon gas can be, for example, produced as methane gas. In this example, it is generated by the regenerated hydrocarbon gas synthesis device 8 and dehydrated by the second dehydration device 9 to obtain regenerated methane gas. The hydrocarbon gas is not limited to methane gas; for example, ethane gas, propane gas, butane gas, ethylene gas, propylene gas, etc., can also be used. Furthermore, the hydrocarbon gas does not need to contain only one type of hydrocarbon; it can be a mixture of two or more types of hydrocarbons. In this example, since the hydrocarbon gas is methane gas, the hydrocarbon-hydrogen mixed gas is a mixture of methane gas and hydrogen gas (hereinafter also referred to as "methane-hydrogen mixed gas").

[0047] Here, the hydrocarbon gas (e.g., methane gas) used in the mixture with hydrogen can be hydrocarbon gas (e.g., methane gas) supplied from other pipelines, depending on the operation of the ironworks (hereinafter also referred to as "external hydrocarbon gas" (or "external methane gas" in the case of methane gas)). However, if it is a regenerated hydrocarbon gas generated by using by-product gases (blast furnace gases, etc.) from the ironworks as raw material gases, the carbon dioxide reduction effect can be further improved. Examples of external hydrocarbon gases include hydrocarbon gases from fossil fuels.

[0048] In this invention, it is preferable that at least a portion of the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is a regenerated hydrocarbon gas (in this example, a regenerated methane gas) synthesized by using blast furnace gas discharged from the blast furnace as raw material. Therefore, as shown in this embodiment, the blast furnace auxiliary equipment preferably includes a regenerated hydrocarbon gas synthesis device 8.

[0049] The hydrogen used for mixing can be supplied from an external source, but the hydrogen production method is preferably one that produces as little carbon dioxide as possible, such as water electrolysis. Furthermore, examples of externally supplied hydrogen include: hydrogen produced by reforming hydrocarbons such as natural gas using steam reforming; hydrogen obtained by gasifying liquefied hydrogen; and hydrogen produced by dehydrogenating organic hydrides. Also, the hydrogen does not necessarily have to be a gas with a hydrogen concentration of 100% by volume; it is preferable to use a gas with a higher hydrogen concentration, specifically, hydrogen with a hydrogen concentration of 80% by volume or more. More preferably, the hydrogen concentration is 90% by volume or more, and even more preferably 95% by volume or more. A hydrogen concentration of 100% by volume is also acceptable. Examples of residual gases other than hydrogen include CO or CO2, H2S, CH4, and N2.

[0050] The preheating device 11 is an apparatus for preheating a hydrocarbon-hydrogen mixture to generate a high-temperature hydrocarbon-hydrogen mixture. In this example, the hydrocarbon-hydrogen mixture is a methane-hydrogen mixture. The preheating device 11 is not particularly limited, but it is ideal to perform heating without changing the gas composition. Examples include: an electric heater that preheats the hydrocarbon-hydrogen mixture by heating the heating element with electricity and utilizing heat exchange between the heating element and the hydrocarbon-hydrogen mixture; or a gas furnace that preheats the hydrocarbon-hydrogen mixture by burning fuel to generate high-temperature combustion gas and utilizing heat exchange between the combustion gas and the hydrocarbon-hydrogen mixture.

[0051] If the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is directly partially combusted, a portion of the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) will be converted into CO2 and H2O. After being blown into the blast furnace, it will react with the coke and excessively consume the coke, which is not ideal. Furthermore, regarding the energy input for heating, a method that does not produce CO2 during energy generation and heating is more ideal. If it is an electric heater, it is more ideal to use renewable electricity obtained through solar power generation, etc. If it is a gas-fired furnace, it is more ideal to use non-fossil fuels such as hydrogen produced by water electrolysis.

[0052] The preheating temperature is not particularly limited, for example, it can be set to 500°C or higher. The reason is that by setting it to 500°C or higher, carbon dioxide emissions can be further reduced. For the same reason, the preheating temperature is more preferably set to 600°C or higher, and even more preferably set to 800°C or higher. Therefore, the preheating device 11 can heat the hydrocarbon-hydrogen mixture to a more preferably 500°C or higher, more preferably 600°C or higher, and even more preferably 800°C or higher.

[0053] The effects of the blast furnace auxiliary equipment of this embodiment will be explained below. As described above, the blast furnace auxiliary equipment of this embodiment includes: a mixing device 10 for mixing hydrocarbon gas and hydrogen gas to generate a hydrocarbon-hydrogen mixed gas, a preheating device 11 for preheating the hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas, and a blowing device 3 having a hydrocarbon-hydrogen mixed gas supply section for introducing the high-temperature hydrocarbon-hydrogen mixed gas into the tuyeres. According to this configuration, firstly, a hydrocarbon-hydrogen mixed gas (in this example, a methane-hydrogen mixed gas) can be obtained by the mixing device 10. Then, the hydrocarbon-hydrogen mixed gas (in this example, a methane-hydrogen mixed gas) can be preheated by the preheating device 11 to obtain a high-temperature hydrocarbon-hydrogen mixed gas (in this example, a preheated methane-hydrogen mixed gas). Then, the blowing device 3 can be used to blow this high-temperature hydrocarbon-hydrogen mixed gas (in this example, a preheated methane-hydrogen mixed gas) from the tuyeres 2 into the blast furnace 1. In the blast furnace auxiliary equipment of this embodiment, since the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is preheated, the amount of heat required by blast furnace 1 for burning carbon such as coke is replaced by the sensible heat of the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture). Therefore, the amount of carbon burned, such as coke, is reduced, and carbon dioxide emissions are reduced. Here, if we illustrate this with the case where the hydrocarbon-hydrogen mixture is a methane-hydrogen mixture, the thermal decomposition reaction of methane occurs to the right via the reaction CH4C + 2H2. If a predetermined amount of H2 is added, according to Le Chatelier's principle, the above reaction tends to proceed to the left, and the reaction to the right can be suppressed, thus suppressing the thermal decomposition of CH4. Therefore, carbon precipitation can also be suppressed. This principle applies even if the hydrocarbon is other than methane, such as ethylene or propane. As described above, the blast furnace auxiliary equipment according to this embodiment can suppress the thermal decomposition of hydrocarbons and further reduce the emission of carbon dioxide from the blast furnace. Furthermore, a gas mixture of hydrocarbon gases such as coke oven gas and hydrogen can also be used, so the blast furnace auxiliary equipment of the present invention may not necessarily include a mixing device 10.

[0054] <Operating Method of Blast Furnace> Next, an example of an operating method for a blast furnace according to one embodiment of the present invention will be described. Although not particularly limited, the operating method of the blast furnace in this embodiment can be described as an operating method for a blast furnace equipped with the auxiliary equipment of the blast furnace described in the above embodiment. Since such auxiliary equipment has already been described in the above embodiment, it will be used in the description of the operating method of the blast furnace, and a further description will be omitted.

[0055] The blast furnace operation method of this embodiment is a blast furnace operation method in which blast gas and reducing materials are blown in through tuyeres 2. In the blast furnace operation method of this embodiment, sintered ore or lump ore, granules, coke, etc. (not shown) as raw materials are charged into the blast furnace 1 from the top of the furnace. Furthermore, blast gas (oxygen in this example) and reducing materials are blown into the blast furnace 1 through tuyeres 2 located at the bottom. The reducing materials contain a hydrocarbon-hydrogen mixture. Furthermore, the gas blown into the blast furnace 1 from the tuyeres can play a role in gasifying the blown reducing materials or coke in the blast furnace 1. The carbon monoxide or hydrogen produced by the reaction of the blast gas with the blown reducing materials or coke can reduce the ore raw materials charged into the blast furnace 1 to produce molten iron.

[0056] The method of this embodiment includes the steps of preheating the hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas, and the steps of blowing the high-temperature hydrocarbon-hydrogen mixed gas into the tuyeres of the blast furnace. Furthermore, the method of this embodiment also includes the step of preparing the hydrocarbon-hydrogen mixed gas before preheating it. Each step will be explained below.

[0057] In the method of this embodiment, a hydrocarbon-hydrogen mixed gas is first prepared. The hydrocarbon-hydrogen mixed gas contains hydrocarbon gas and hydrogen gas. As shown in the above embodiment, the hydrocarbon-hydrogen mixed gas is preferably prepared as a methane-hydrogen mixed gas.

[0058] As shown in the above embodiment, the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is preferably prepared by generating regenerated hydrocarbon gas and mixing it with hydrogen. That is, preferably, at least a portion of the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is regenerated hydrocarbon gas (in this example, regenerated methane gas) synthesized by using blast furnace gas discharged from the blast furnace as raw material. Furthermore, when at least a portion of the hydrocarbon-hydrogen mixture uses regenerated hydrocarbon gas, the step of mixing hydrocarbon gas with hydrogen is not necessary. In addition to blast furnace gas and hydrogen for synthesis, hydrogen for mixing can also be supplied in advance as raw material gas for the generation step of regenerated hydrocarbon gas, thereby directly generating the hydrocarbon-hydrogen mixture in the generation step of regenerated hydrocarbon gas. On the other hand, a hydrocarbon-hydrogen mixed gas can also be prepared by, for example, feeding it in from the outside. In this case, a blast furnace auxiliary equipment different from the blast furnace auxiliary equipment in the above embodiment can be used (one that does not have the first dehydration device 4, the regenerated hydrocarbon gas synthesis device 8, the second dehydration device 9, and the mixing device 10). Hereinafter, as shown in the above embodiment, the case of preparing a hydrocarbon-hydrogen mixed gas by generating regenerated hydrocarbon gas and mixing it with hydrogen gas will be described.

[0059] The generation of the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is as described in the above embodiment. Preferably, the proportion of hydrocarbons from the regenerated hydrocarbon gas (in this example, regenerated methane gas) contained in the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is set to 80% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more. This is because increasing the proportion of hydrocarbons from the regenerated hydrocarbon gas results in a higher CO2 reduction effect. Furthermore, ideally, the proportion of hydrocarbons from the regenerated hydrocarbon gas contained in the mixed hydrocarbon gas is set to 80% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more. Alternatively, the total amount of hydrocarbon gas can be regenerated hydrocarbon gas, excluding external hydrocarbon gas. The reason is that as the amount of external hydrocarbon gas increases, the amount of CO2 discharged from the furnace top that is converted into regenerated hydrocarbon gas for reuse decreases, while the amount of CO2 discharged to the outside increases. By reducing the proportion of external hydrocarbon gas in the hydrocarbon-hydrogen mixture and increasing the proportion of regenerated hydrocarbon gas, a higher CO2 reduction effect can be achieved.

[0060] The hydrocarbon concentration (methane concentration) of the hydrocarbon gas (e.g., methane gas) containing at least one of regenerated hydrocarbon gas (e.g., regenerated methane gas) and external hydrocarbon gas (e.g., external methane gas) is preferably set to 80% by volume or more. That is, if the hydrocarbon concentration of the hydrocarbon gas is low, the amount of gas blown into the blast furnace increases, which may increase the pressure loss of the blast furnace and reduce productivity. Furthermore, if the hydrocarbon concentration of the hydrocarbon gas is low, the reduction efficiency of iron ore in the blast furnace may also deteriorate, resulting in operational failures. Therefore, the hydrocarbon concentration of the hydrocarbon gas is preferably set to 80% by volume or more. The hydrocarbon concentration of the hydrocarbon gas is more preferably 90% by volume or more, and even more preferably 95% by volume or more. The hydrocarbon concentration of the hydrocarbon gas may also be 100% by volume. For the same reason, the hydrocarbon concentration of both the regenerated hydrocarbon gas and the external hydrocarbon gas is also preferably set to 80% by volume or more. The hydrocarbon concentrations of the regenerated hydrocarbon gas and the external hydrocarbon gas are preferably 90% by volume or more, and more preferably 95% by volume or more. The hydrocarbon concentrations of the regenerated hydrocarbon gas and the external hydrocarbon gas can also be 100% by volume. Furthermore, the remaining gases other than hydrocarbons in the hydrocarbon gas, regenerated hydrocarbon gas, and external hydrocarbon gas may include, for example, impurity gases such as carbon monoxide, carbon dioxide, hydrogen, hydrocarbons, and nitrogen. Also, when the hydrocarbon concentration of the regenerated hydrocarbon gas decreases, for example, by reducing the proportion of regenerated hydrocarbon gas in the hydrocarbon gas while increasing the proportion of external hydrocarbon gas with a higher hydrocarbon concentration, the hydrocarbon concentration of the hydrocarbon gas can be maintained at a high level.

[0061] The ratio of hydrogen content in the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) to the total amount of hydrocarbons (in this example, methane) and hydrogen is preferably 10% by volume or more and 80% by volume or less. By setting it to 10% by volume or more, the thermal decomposition of hydrocarbons (in this example, methane) can be sufficiently suppressed when preheated to high temperatures. Furthermore, by setting it to 80% by volume or less, the amount of hydrocarbons (in this example, methane) contained in the hydrocarbon-hydrogen mixture can be ensured, especially when using regenerated hydrocarbon gas (in this example, regenerated methane gas), it can achieve a sufficient CO2 reduction effect. For the same reason, the ratio of hydrogen content in the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) to the total amount of hydrocarbons (in this example, methane) and hydrogen is preferably 20% by volume or more and 70% by volume or less.

[0062] In this invention, the hydrocarbon gas (in this example, methane gas) may not necessarily include regenerated hydrocarbon gas (in this example, regenerated methane gas), and the total amount may be set as external hydrocarbon gas. In this case, blast furnace auxiliary equipment different from the blast furnace auxiliary equipment of the above embodiment (without the first dehydration device 4, the regenerated hydrocarbon gas synthesis device 8, and the second dehydration device 9) can be used. Furthermore, the mixing step of hydrocarbon gas and hydrogen gas is not necessary; even if a gas containing hydrocarbons and hydrogen is supplied from the outside as a hydrocarbon-hydrogen mixed gas, the effects of this invention can still be obtained.

[0063] In the method of this embodiment, the hydrocarbon-hydrogen mixture (in this example, a methane-hydrogen mixture) is then preheated using a preheating device 11 to generate a high-temperature hydrocarbon-hydrogen mixture (in this example, a preheated methane-hydrogen mixture).

[0064] Furthermore, it is preferable that at least 90% by volume of the hydrocarbon-hydrogen mixture is preheated before being blown into the blast furnace from the tuyeres 2. The reason for this is that by setting it to at least 90% by volume, carbon dioxide emissions can be further reduced.

[0065] As described above, the preheating temperature is not particularly limited, for example, it can be set to 500°C or higher. This is because setting it to 500°C or higher can further reduce carbon dioxide emissions. For the same reason, the preheating temperature is more preferably set to 600°C or higher, and even more preferably to 800°C or higher. Furthermore, it is preferable to set the preheating temperature to 1200°C or lower, thereby suppressing the thermal decomposition of hydrocarbons.

[0066] Here, it is preferable that the delivery piping between the preheating device 11 and the blowing device 3 is adequately insulated to minimize heat loss. Furthermore, when heat loss in the delivery piping cannot be avoided, the preheating temperature in the preheating device 11, taking into account heat loss, can be set to a temperature higher than the limit temperature at which the hydrocarbon is introduced into the blowing device 3. Also, to suppress the thermal decomposition of hydrocarbons, the preheating temperature is preferably below 1200°C.

[0067] In the method of this embodiment, a high-temperature hydrocarbon-hydrogen mixed gas is then blown in from the tuyeres of the blast furnace.

[0068] Here, the ratio of the amount of hydrocarbon-hydrogen mixed gas (in this example, methane-hydrogen mixed gas) blown into the blast furnace to the amount of reducing material blown into the furnace is preferably 90 wt% or more. This is because by setting it to 90 wt% or more, a higher CO2 reduction effect can be achieved. Furthermore, the amount of other reducing materials blown into the blast furnace is preferably 10 wt% or less relative to the total amount of reducing materials containing hydrocarbon gas (in this example, methane gas) and hydrogen.

[0069] The oxygen concentration of the blast gas is not particularly limited. Even hot blast (oxygen concentration 21-30%) used in conventional blast furnaces can achieve the effects of the present invention. However, from the viewpoint of reducing carbon dioxide emissions by blowing in a large amount of hydrocarbon-hydrogen mixed gas, an oxygen concentration of 50% by volume or more is preferred. The blast gas is preferably oxygen, and the oxygen concentration is preferably 80% by volume or more, more preferably 90% by volume or more, and even more preferably 95% by volume or more, and particularly preferably 100% by volume. The reason for this is that by sufficiently increasing the oxygen concentration in the oxygen, when blowing in a large amount of reducing raw materials containing hydrocarbons, it is possible to ensure a sufficient tuyere tip temperature to prevent operational malfunctions.

[0070] The effects of the operation method of the blast furnace according to this embodiment will be explained below. The operation method of the blast furnace according to this embodiment includes the steps of preheating the hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas, and blowing the high-temperature hydrocarbon-hydrogen mixed gas into the tuyeres of the blast furnace. According to the operation method of the blast furnace according to this embodiment, since the hydrocarbon-hydrogen mixed gas (in this example, a methane-hydrogen mixed gas) is preheated, the amount of heat required by the blast furnace 1 for burning carbon such as coke is replaced by the sensible heat of the hydrocarbon-hydrogen mixed gas (in this example, a methane-hydrogen mixed gas). Therefore, the amount of carbon burned, such as coke, is reduced, and the amount of carbon dioxide emissions can be reduced. Here, if the hydrocarbon-hydrogen mixed gas is an example of a methane-hydrogen mixed gas, the thermal decomposition reaction of methane occurs by the reaction CH4C + 2H2 proceeding to the right. If a predetermined amount of H2 is added, according to Le Chatelier's principle, the above reaction tends to proceed to the left, while the reaction to the right is suppressed, thus inhibiting the thermal decomposition of CH4. Therefore, it also inhibits carbon precipitation. This principle applies even if the hydrocarbon is other than methane, such as ethylene or propane. As described above, the blast furnace operation method according to this embodiment can suppress the thermal decomposition of hydrocarbons and further reduce carbon dioxide emissions from the blast furnace. [Example]

[0071] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to any of the following embodiments.

[0072] The inventive examples and comparative examples of this embodiment are shown in Tables 1 to 4. The inventive examples and comparative examples are based on the prediction of operating specifications for an operation with a production rate of approximately 8700 t / d in a blast furnace with a furnace volume of 4300 m3, using a blast furnace simulation model and basic reaction analysis of hydrocarbon-hydrogen mixed gas. Comparative Example 1 is an example of a conventional blast furnace in which hot blast and pulverized coal are blown in from the tuyeres. Comparative Example 2 is an example in which methane is blown in from the tuyeres at room temperature (25°C) without heating. In Examples 1 (Table 1), 2 (Table 2), and 3 (Table 3) other than Comparative Examples 1 and 2, the hydrocarbon gas is set as regenerated methane gas with a methane concentration of 100%, and the hydrogen gas is set as hydrogen gas with a hydrogen concentration of 100%. A methane-hydrogen mixed gas is used as the hydrocarbon-hydrogen mixed gas, and no other reducing materials are used. The methane-hydrogen mixture system was preheated in its entirety at temperatures of 500°C, 800°C, and 1200°C. Only the methane-hydrogen mixture was used as the feedstock for reduction. In Example 4 (Table 4), the hydrocarbon gas was regenerated ethane gas with a 100% ethane concentration, and the hydrogen gas was hydrogen gas with a 100% hydrogen concentration. An ethane-hydrogen mixture was used as the hydrocarbon-hydrogen mixture, and no other feedstock was used. The ethane-hydrogen mixture system was preheated in its entirety at a temperature of 500°C. Only the ethane-hydrogen mixture was used as the feedstock for reduction.

[0073] The configuration and use of the blast furnace simulation model are the same as those described in Non-Patent Document 1. It has been confirmed that this blast furnace simulation model can accurately reproduce the actual operation of a blast furnace, and it can be assumed that when the actual operation takes place in a blast furnace, the same results as this simulation model can be obtained. Furthermore, in the basic reaction analysis of the methane-hydrogen mixture and the ethane-hydrogen mixture, the detailed chemical reaction calculation software Cantera, capable of performing basic reaction analysis, is used. It has been confirmed that, through basic reaction analysis, the actual thermal decomposition behavior of methane and ethane can be better reproduced, and it can be assumed that when the methane-hydrogen mixture is preheated in the reducing material preheating unit, the same results can be obtained.

[0074] In this embodiment, assuming the process configuration shown in FIG1B, after separating CO2 from the blast furnace gas discharged from the top of the blast furnace, the CO2 reacts with hydrogen to generate regenerated methane gas or regenerated ethane gas, which is then mixed with hydrogen and preheated before being blown in through the tuyeres. The preheating of the methane-hydrogen mixture is performed using an electric heater. The preheating gas system used in the furnace body is generated by recovering and dehydrating the blast furnace gas discharged from the top of the blast furnace, then partially burning it with oxygen, and then mixing it with the blast furnace gas before combustion. Furthermore, the preheating device and the blowing device are adequately insulated, and the preheating temperature is the same as the blowing temperature. The thermal decomposition behavior of the preheated methane-hydrogen mixture or ethane-hydrogen mixture at this temperature after 4 seconds is predicted by basic reaction analysis, and the amount of thermal decomposition of methane or ethane is compared. The less thermal decomposition during preheating, the more carbon precipitation during preheating can be suppressed.

[0075] The simulation results show that when the CO2 emission is less than 1100 kg / t, the CO2 reduction effect is set to "good", and when it is above 1100 kg / t, it is set to "poor". Furthermore, by comparing with the benchmark example (conditions where methane or ethane is preheated without mixing with hydrogen), the thermal decomposition rate of methane or ethane after 4 seconds at each preheating temperature of 500°C, 800°C, and 1200°C is evaluated. When the decomposition rate is less than 1, the inhibition of thermal decomposition of methane or ethane is set to "good"; when the decomposition rate is above 1, the inhibition of thermal decomposition of methane or ethane is set to "poor".

[0076] [Table 1] [Table 1] Example 1 Comparative example 1 Comparative example 2 Comparative Example 3 (Benchmark Example) Invention Examples 1 Invention Examples 2 Invention Examples 3 Iron output t / d 8710 8725 8688 8685 8672 8685 coke ratio kg / t 328 347 316 316 334 316 pulverized coal kg / t 179 0 0 0 0 0 Regenerated methane kg / t 0 148 172 167 71 147 external methane kg / t 0 0 0 0 0 20 H2 kg / t 0 0 0 2 35 2 Regenerated methane Nm 3 / t 0 207 241 234 99 206 external methane Nm 3 / t 0 0 0 0 0 28 H2 Nm 3 / t 0 0 0 26 397 26 H2 / (Regenerated Methane + External Methane + H2) × 100 % - 0 0 10 80 10 Preheated methane-hydrogen mixture The ratio of those volume% 0 0 100 100 100 100 methane-hydrogen mixed gas preheating temperature ℃ - - 500 500 500 500 Supply air volume Nm 3 / t 965 0 0 0 0 0 oxygen supply Nm 3 / t 52 328 323 320 267 320 Supply air oxygen concentration volume% 25 100 100 100 100 100 air supply temperature ℃ 1164 25 25 25 25 25 Air supply and moisture absorption g / Nm 3 - Air 20 0 0 0 0 0 Air outlet front end temperature ℃ 2119 2003 2001 1992 2003 1992 Slag ratio kg / t 321 308 306 306 307 306 Preheating gas injection rate for the furnace body Nm 3 / t 0 598 601 601 602 601 CO2 emissions kg / t 1570 1100 1004 1004 1059 1059 Methane thermal decomposition rate (ratio to baseline) - - - 1.00 0.97 0.61 0.97 CO2 reduction effect bad bad good good good good Methane thermal decomposition inhibition effect - - bad good good good

[0077] [Table 2] [Table 2] Example 2 Comparative Example 4 (Benchmark Example) Invention Example 4 Iron output t / d 8709 8680 coke ratio kg / t 283 293 pulverized coal kg / t 0 0 Regenerated methane kg / t 193 138 external methane kg / t 0 0 H2 kg / t 0 17 Regenerated methane Nm 3 / t 270 193 external methane Nm 3 / t 0 0 H2 Nm 3 / t 0 193 H2 / (Regenerated Methane + External Methane + H2) × 100 % 0 50 The ratio of preheated components in a methane-hydrogen mixture volume% 100 100 methane-hydrogen mixed gas preheating temperature ℃ 800 800 Supply air volume Nm 3 / t 0 0 oxygen supply Nm 3 / t 313 282 Supply air oxygen concentration volume% 100 100 air supply temperature ℃ 25 25 Air supply and moisture absorption g / Nm 3 -Air 0 0 Air outlet front end temperature ℃ 2000 2014 Slag ratio kg / t 302 303 Preheating gas injection rate for the furnace body Nm 3 / t 599 601 CO2 emissions kg / t 899 929 Methane thermal decomposition rate (ratio to baseline) - 1.00 0.89 CO2 reduction effect good good Methane thermal decomposition inhibition effect bad good

[0078] [Table 3] [Table 3] Example 3 Comparative Example 5 (Benchmark Example) Invention Example 5 Iron output t / d 8750 8667 coke ratio kg / t 228 234 pulverized coal kg / t 0 0 Regenerated methane kg / t 220 165 external methane kg / t 0 0 H2 kg / t 0 twenty one Regenerated methane Nm 3 / t 309 231 external methane Nm 3 / t 0 0 H2 Nm 3 / t 0 231 H2 / (Regenerated Methane + External Methane + H2) × 100 % 0 50 The ratio of preheated components in a methane-hydrogen mixture Volume % 100 100 Methane-hydrogen mixture preheating temperature ℃ 1200 1200 air supply volume Nm 3 / t 0 0 air oxygen supply Nm 3 / t 290 256 Supply air oxygen concentration Volume % 100 100 air supply temperature ℃ 25 25 Air supply and moisture absorption g / Nm 3 - Air 0 0 Air outlet front end temperature ℃ 2016 1991 Slag ratio kg / t 294 295 Preheating gas injection rate for the furnace body Nm 3 / t 597 602 CO2 emissions kg / t 723 741 Methane thermal decomposition rate (ratio to baseline) - 1.00 0.85 CO2 reduction effect good good Methane thermal decomposition inhibition effect bad good

[0079] [Table 4] [Table 4] Example 4 Comparative Example 6 (Benchmark Example) Invention Example 6 Iron output t / d 8781 8726 coke ratio kg / t 277 282 pulverized coal kg / t 0 0 Regenerated ethane kg / t 182 156 external ethane kg / t 0 0 H2 kg / t 0 10 Regenerated ethane Nm 3 / t 136 116 external ethane Nm 3 / t 0 0 H2 Nm 3 / t 0 116 H2 / (Regenerated Ethane + External Ethane + H2) × 100 % 0 50 The ratio of preheated components in an ethane-hydrogen mixture volume% 100 100 Ethane-hydrogen mixed gas preheating temperature ℃ 500 500 Supply air volume Nm 3 / t 0 0 oxygen supply Nm 3 / t 300 287 Supply air oxygen concentration volume% 100 100 air supply temperature ℃ 25 25 Air supply and moisture absorption g / Nm 3 - Air 0 0 Air outlet front end temperature ℃ 2204 2132 Slag ratio kg / t 293 297 Preheating gas injection rate for the furnace body Nm 3 / t 594 598 CO2 emissions kg / t 878 894 Ethane thermal decomposition rate (ratio to baseline) - 1.00 0.95 CO2 reduction effect good good Ethane thermal decomposition inhibition effect bad good

[0080] As shown in Tables 1 to 4, it can be seen that the invention can achieve both the CO2 reduction effect and the inhibition of thermal decomposition of methane or ethane, but in the comparative example, neither of them is sufficient. [Simplified Explanation of the Diagram]

[0028] FIG1A is a schematic diagram showing the configuration of a blast furnace equipped with blast furnace auxiliary equipment according to one embodiment of the present invention. FIG1B is a schematic diagram showing the configuration of a blast furnace equipped with blast furnace auxiliary equipment according to a variation. FIG2A is a schematic diagram showing an example of a blow-in device. FIG2B is a schematic diagram showing another example of a blow-in device.

Claims

1. A method for operating a blast furnace, wherein blast gas and reducing materials are blown in through a tuyer; characterized in that the reducing materials contain a hydrocarbon-hydrogen mixture, and the method for operating the blast furnace includes: The steps of preheating the above-mentioned hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas, and blowing the above-mentioned high-temperature hydrocarbon-hydrogen mixed gas into the tuyeres of the above-mentioned blast furnace; the ratio of the amount of hydrogen contained in the above-mentioned hydrocarbon-hydrogen mixed gas to the total amount of hydrocarbons and hydrogen is 10% by volume or more and 80% by volume or less; the preheating temperature of the above-mentioned hydrocarbon-hydrogen mixed gas is 500°C or more.

2. The operating method of the blast furnace as requested in item 1, wherein, The aforementioned hydrocarbon-hydrogen mixture is a methane-hydrogen mixture.

3. The operating method of the blast furnace as requested in item 1 or 2, wherein, At least a portion of the aforementioned hydrocarbon-hydrogen mixture is a regenerated hydrocarbon gas synthesized from blast furnace gas discharged from the aforementioned blast furnace as raw material.

4. The operating method of the blast furnace as requested in item 1 or 2, wherein, The proportion of hydrocarbons from the regenerated hydrocarbon gas is 80% or more, relative to the hydrocarbons contained in the aforementioned hydrocarbon-hydrogen mixture.

5. The operating method of the blast furnace as requested in item 1 or 2, wherein, More than 90% by volume of the aforementioned hydrocarbon-hydrogen mixed gas is preheated before being blown into the aforementioned blast furnace from the aforementioned tuyeres.

6. The operating method of the blast furnace as requested in item 1 or 2, wherein, The oxygen concentration in the air supply system is above 80% by volume.

7. The operating method of the blast furnace as requested in item 1 or 2, wherein, The ratio of the amount of the aforementioned hydrocarbon-hydrogen mixed gas blown in to the amount of the aforementioned reducing material blown in is 90 wt% or more.

8. A blast furnace auxiliary device, characterized in that it comprises: a preheating device for preheating the aforementioned hydrocarbon-hydrogen mixed gas to generate a high-temperature hydrocarbon-hydrogen mixed gas; a blowing device having a hydrocarbon-hydrogen mixed gas supply section for introducing the aforementioned high-temperature hydrocarbon-hydrogen mixed gas into a tuyer; and a mixing device for mixing the aforementioned hydrocarbon gas and hydrogen gas to generate a hydrocarbon-hydrogen mixed gas; wherein the mixing device is configured to set the amount of hydrogen contained in the aforementioned hydrocarbon-hydrogen mixed gas to a ratio of 10% by volume or more and 80% by volume or less relative to the total amount of hydrocarbon and hydrogen; and wherein the preheating device is configured to set the preheating temperature of the aforementioned hydrocarbon-hydrogen mixed gas to 500°C or more.

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