How to use converter gas

Abstract

This paper discloses a new technology for obtaining hydrogen and carbon dioxide using converter gas, and then separating and recovering the carbon dioxide. [Solution] The method for utilizing converter gas according to the present disclosure comprises a reaction step of obtaining a reformed gas containing carbon dioxide and hydrogen by reacting the converter gas with water vapor, and a separation step of separating the carbon dioxide and hydrogen contained in the reformed gas. The method for separating carbon dioxide and hydrogen in the separation step includes at least one of the following: a chemical absorption method using a carbon dioxide absorbent, a cryogenic separation method, and a physical adsorption method using a gate-type porous coordination polymer.

Description

[Technical Field]

[0001] This application discloses a method for utilizing converter gas. [Background technology]

[0002] Technologies have been developed that utilize exhaust gas from the steelmaking process to obtain a mixed gas containing hydrogen and carbon dioxide, and then separate and recover carbon dioxide from this mixed gas while using the hydrogen as fuel. For example, Patent Document 1 discloses a technology in which carbon monoxide contained in blast furnace gas is converted into carbon dioxide and hydrogen by a water-gas shift reaction, and then carbon dioxide is separated and recovered by a pressure swing adsorption method. Patent Document 2 also discloses a technology in which carbon monoxide contained in converter gas is converted into carbon dioxide and hydrogen by a water-gas shift reaction, and then carbon dioxide is separated and recovered by a decarboxylation process. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2017-189750 [Patent Document 2] Japanese Patent Application Publication No. 58-009801 [Overview of the project] [Problems that the invention aims to solve]

[0004] This invention discloses a novel technology for obtaining hydrogen and carbon dioxide using converter gas, and then separating and recovering the carbon dioxide. [Means for solving the problem]

[0005] The technology of this disclosure includes several aspects as follows: <Aspect 1> A method for utilizing converter gas, A reaction step involves reacting the converter gas with steam to obtain a reformed gas containing carbon dioxide and hydrogen. A separation step for separating carbon dioxide and hydrogen contained in the reformed gas, It has, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, Chemical absorption method using carbon dioxide absorbent solution, Cryogenic separation method, and Physical adsorption method using gate-type porous coordination polymers, including at least one of the following: Methods of using converter gas. <Aspect 2> A method for utilizing converter gas according to Embodiment 1, It has a storage process for storing the separated carbon dioxide underground. Methods of using converter gas. <Aspect 3> A method for utilizing converter gas according to embodiment 1 or 2, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned chemical absorption method Includes, The carbon dioxide absorbent is an amine solution. Methods of using converter gas. <Aspect 4> A method for utilizing converter gas according to any of the embodiments 1 to 3, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned cryogenic separation method including, Methods of using converter gas. <Aspect 5> A method for utilizing converter gas according to any of embodiments 1 to 4, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned physical adsorption method including, Methods of using converter gas. <Aspect 6> A method for utilizing converter gas according to any of the embodiments 1 to 5, The above reaction process is carried out in multiple stages. The reaction temperature in the first stage is between 300°C and 400°C. The reaction temperature in the final stage is 180°C or higher and 200°C or lower, Method for utilizing converter gas. <Aspect 7> The method for utilizing converter gas according to any one of Aspects 1 to 6, wherein a blast furnace gas treatment step of removing nitrogen from blast furnace gas to obtain nitrogen-removed blast furnace gas containing carbon monoxide and carbon dioxide, a mixing step of mixing the nitrogen-removed blast furnace gas and the converter gas to obtain a mixed gas, comprising in the reaction step, the mixed gas and the steam are reacted to obtain the reformed gas containing carbon dioxide and hydrogen. Method for utilizing converter gas.

Effects of the Invention

[0006] According to the technique of the present disclosure, it is possible to obtain hydrogen and carbon dioxide using converter gas, and then separate and recover carbon dioxide.

Brief Description of the Drawings

[0007] [Figure 1] An example of the method for utilizing converter gas is shown. [Figure 2] An example of the method for utilizing converter gas is shown. [Figure 3] This is a diagram for explaining the phase change in the physical adsorption method using a gate-type porous coordination polymer. [Figure 4A] The adsorption behavior of general adsorbents such as activated carbon is shown. [Figure 4B] The adsorption behavior of the gate-type porous coordination polymer is shown.

Modes for Carrying Out the Invention

[0008] 1. Regarding the conventional ironmaking process To achieve carbon neutrality, it is necessary to concentrate and recover carbon dioxide contained in exhaust gases from the steelmaking process. Currently, exhaust gases from the steelmaking process have a carbon dioxide concentration of about 5-25% by volume, with the majority being components other than carbon dioxide. Converter gas (LDG), which contains high concentrations of carbon monoxide and carbon dioxide, is distributed and supplied to multiple combustion facilities within the steelworks and used as fuel; in other words, carbon dioxide is emitted from multiple small-scale emission sources in a diluted state. As described above, the concentration of carbon dioxide in exhaust gases from the steelmaking process is low, and recovery (concentration) operations require large-scale facilities and land, as well as consuming a great deal of energy, making them extremely uneconomical.

[0009] 2. Issues to be resolved Because steel mills have existing production facilities and infrastructure, installing carbon dioxide concentration and capture equipment requires the removal and preparation of existing facilities or the acquisition of new land. Furthermore, to improve the economic efficiency of carbon dioxide concentration and capture, it is necessary to pursue reductions in the footprint (land area) per unit of actual carbon dioxide captured, after subtracting the new carbon dioxide emissions associated with the capture operation.

[0010] 3. The technology disclosed herein To solve the above problems, the inventors have diligently researched technologies for concentrating and recovering carbon dioxide contained in exhaust gas from steelmaking processes, and have completed the following method for utilizing converter gas. The method for utilizing converter gas according to the embodiment will be described below with reference to the drawings, but the technology of this disclosure is not limited to the following embodiments.

[0011] As shown in Figures 1 and 2, the method of utilizing converter gas according to one embodiment is: Reaction step S1 involves reacting converter gas with steam to obtain a reformed gas containing carbon dioxide and hydrogen. Separation step S2 separates carbon dioxide and hydrogen contained in the reformed gas, It has the following characteristics. Here, the method for separating carbon dioxide and hydrogen in separation step S2 is: Chemical absorption method using carbon dioxide absorbent solution, Cryogenic separation method, and Physical adsorption method using gate-type porous coordination polymers, It includes at least one of the following.

[0012] 3.1 Reaction Process Reaction step S1 includes reacting converter gas with steam to obtain a reformed gas containing carbon dioxide and hydrogen.

[0013] 3.1.1 Converter gas Converter gas (LDG) is the gas discharged from the converter 10 during the molten iron refining process using the converter 10, as shown in Figures 1 and 2. Compared to coke oven gas (COG) and blast furnace gas (BFG), converter gas is characterized by a higher total concentration of carbon monoxide and carbon dioxide. The total proportion of carbon monoxide and carbon dioxide in the converter gas is, for example, 70% to 90% by volume, and may be 80% to 85% by volume. The proportion of carbon monoxide in the converter gas is, for example, 55% to 75% by volume, and may be 60% to 70% by volume. The proportion of carbon dioxide in the converter gas is, for example, 10% to 25% by volume, and may be 15% to 20% by volume.

[0014] The converter gas may contain carbon monoxide and carbon dioxide, as well as other components. Examples of these other components include oxygen, nitrogen, and hydrogen. The proportion of these other components in the converter gas may be, for example, 10% to 25% by volume, or 15% to 20% by volume.

[0015] The converter gas may be one from which dust and other particles have been removed. That is, reaction step S1 may include removing at least a portion of the dust contained in the converter gas, and reacting the dust-removed converter gas with water vapor. Dust removal may be carried out by a known dust removal device (not shown).

[0016] 3.1.2 Reaction between converter gas and water vapor In reaction step S1, a reformed gas containing carbon dioxide and hydrogen is obtained by reacting converter gas with water vapor. The reaction in reaction step S1 may be, for example, a so-called water-gas shift reaction. That is, in reaction step S1, a reformed gas containing carbon dioxide and hydrogen may be obtained by bringing converter gas and water vapor into contact to produce a water-gas shift reaction (CO + H2O → CO2 + H2). In this way, hydrogen and carbon dioxide can be produced by reacting carbon monoxide contained in the converter gas with water vapor. In reaction step S1, the amount of water vapor relative to the converter gas can be appropriately adjusted according to the amount of converter gas and the concentration of carbon monoxide contained in the converter gas. In reaction step S1, for example, the converter gas and water vapor can be reacted by bringing the converter gas at a predetermined temperature into contact with water vapor in the presence of a catalyst. More specifically, as shown in Figures 1 and 2, converter gas and steam may be supplied from the inlet to the inside of a reactor packed with a catalyst in a reforming apparatus 20, causing a reaction between the converter gas and steam (for example, the water-gas shift reaction described above) to occur in the reactor, and the reformed gas may be obtained from the outlet of the reactor. The catalyst may be various metal oxide catalysts such as iron oxide-chromium oxide catalysts or zinc oxide-copper oxide catalysts. In Figures 1 and 2, a configuration in which converter gas and steam are supplied separately to the reforming apparatus 20 is illustrated, but a mixed gas of converter gas and steam may also be supplied to the reforming apparatus 20.

[0017] In reaction step S1, the reaction temperature between the converter gas and water vapor can be appropriately controlled. If the reaction temperature is too low, the reaction rate will be slow. On the other hand, if the reaction temperature is too high, the reverse reaction may become dominant. For example, when a water-gas shift reaction is produced by contacting converter gas and water vapor, since this water-gas shift reaction is an exothermic reaction, the reaction can be made to proceed more efficiently by appropriately cooling the reactor. That is, in reaction step S1, the reaction temperature between the converter gas and water vapor may be controlled while cooling the reactor with a cooling mechanism. When a water-gas shift reaction is employed in reaction step S1, the reaction temperature may be, for example, 300°C or more and 400°C or less. Note that "reaction temperature" in the water-gas shift reaction refers to the temperature of the converter gas and water vapor in contact with the catalyst in the catalytic reactor. In this application, this reaction temperature is assumed to be substantially the same as the temperature of the catalyst packed bed, and this reaction temperature can be determined by directly or indirectly measuring the temperature of the catalyst packed bed.

[0018] In reaction step S1, the reaction between the converter gas and steam may be carried out in multiple stages. "Carried out in multiple stages" means that the reaction between the converter gas and steam is carried out through multiple reactors. When the reaction between the converter gas and steam is carried out in multiple stages, the carbon dioxide concentration of the gas may increase with each stage. When the reaction between the converter gas and steam is carried out in multiple stages, the reaction temperatures in each stage may be the same or different. In particular, when a water-gas shift reaction is employed in reaction step S1, the water-gas shift reaction proceeds more efficiently when the reaction temperature in the first stage is higher than the reaction temperature in the final stage. In one embodiment, the reaction temperature in the first stage of reaction step S1 may be, for example, 300°C to 400°C, and the reaction temperature in the final stage may be 180°C to 200°C. The reaction step S1 may be carried out in two to ten steps, two to six steps, two to five steps, or two to four steps.

[0019] 3.1.3 Reformed gas As described above, in reaction step S1, carbon dioxide and hydrogen are produced by reacting a converter gas, mainly composed of carbon monoxide and carbon dioxide, with water vapor. That is, the reformed gas contains carbon dioxide originally contained in the converter gas, as well as carbon dioxide and hydrogen produced by the reaction. The total proportion of carbon dioxide and hydrogen in the reformed gas is, for example, 80% to 95% by volume, or 85% to 95% by volume. The proportion of carbon dioxide in the reformed gas is, for example, 40% to 60% by volume, or 45% to 55% by volume. The proportion of hydrogen in the reformed gas is, for example, 35% to 50% by volume, or 40% to 45% by volume.

[0020] The reformed gas may contain carbon dioxide and hydrogen, as well as other components. Examples of these other components include carbon monoxide, water vapor, oxygen, and nitrogen. By allowing the water-gas shift reaction to proceed sufficiently, the carbon monoxide concentration in the reformed gas approaches 0%. The proportion of carbon monoxide in the reformed gas may be, for example, between 0% and 5% by volume. The proportion of other components in the reformed gas, besides carbon dioxide, hydrogen, and carbon monoxide, may be, for example, 15% or less by volume, or 5% or less by volume.

[0021] 3.2 Separation process The separation step S2 includes separating carbon dioxide and hydrogen contained in the reformed gas. As shown in Figures 1 and 2, the separation step S2 may be carried out in various types of separation devices 30. However, the method for separating carbon dioxide and hydrogen in the separation step S2 shall include at least one of the following: chemical absorption using a carbon dioxide absorbent, cryogenic separation, and physical adsorption using a gate-type porous coordination polymer. In other words, the separation device 30 is at least one of the following: a chemical absorption device having a carbon dioxide absorbent, a cryogenic separation device having a compressor and a cooling device, and a physical adsorption device having a gate-type porous coordination polymer.

[0022] 3.2.1 Chemical absorption method using carbon dioxide absorbent solution The method for separating carbon dioxide and hydrogen in separation step S2 may include a chemical absorption method using a carbon dioxide absorbent. The chemical absorption method using a carbon dioxide absorbent is a method of chemically absorbing carbon dioxide from the reformed gas into the carbon dioxide absorbent by contacting the reformed gas with the carbon dioxide absorbent. The carbon dioxide absorbent is a solution containing components capable of chemically absorbing carbon dioxide. The carbon dioxide absorbent may be, for example, an amine solution. When the reformed gas is contacted with the amine solution, the carbon dioxide contained in the reformed gas chemically combines with the amine, for example, as an amine carbonate and is incorporated into the solution. The type of amine, the concentration of the amine, and the type of solvent in the amine solution are not particularly limited. In particular, the carbon dioxide absorption efficiency tends to be higher when at least one of monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, methylpiperazine, aminomethylpropanol, isopropylaminomethanol, methylaminoethanol, and diethylaminomethanol is used as the amine. The amine concentration in the amine solution and the type of solvent constituting the amine solution are not particularly limited. In a chemical absorption method using a carbon dioxide absorbent, the carbon dioxide absorbent may or may not be heated. The temperature of the carbon dioxide absorbent may be, for example, 20°C to 70°C, 30°C to 60°C, or 40°C to 50°C.

[0023] When carbon dioxide contained in reformed gas is absorbed and separated by chemical absorption, the higher the carbon dioxide concentration in the reformed gas, the greater the amount of carbon dioxide absorbed per unit of absorbent solution. This reduces the footprint (land area) and reaction tower volume required for implementing the chemical absorption method, thereby lowering equipment costs. Furthermore, it reduces the heating energy required to desorb carbon dioxide from the absorbent solution, thus lowering fuel costs for heating the absorbent solution. In this embodiment, as described above, a converter gas containing high concentrations of carbon monoxide and carbon dioxide is reacted with steam to obtain a reformed gas containing high concentrations of carbon dioxide and hydrogen. Thus, by performing chemical absorption using a carbon dioxide absorbent solution on a reformed gas with a high carbon dioxide concentration, it is possible to efficiently separate and recover carbon dioxide while reducing the footprint, energy costs, and equipment costs.

[0024] Furthermore, carbon dioxide absorbed into a liquid by chemical absorption can be recovered by vaporizing it through heating. For example, if carbon dioxide is chemically absorbed as an amine carbonate using an amine solution, heating the amine carbonate to a temperature between 90°C and 120°C will preferentially vaporize the carbon dioxide from the amine carbonate, allowing it to be recovered as high-concentration carbon dioxide.

[0025] 3.2.2 Cryogenic separation method The method for separating carbon dioxide and hydrogen in separation step S2 may include cryogenic separation. Cryogenic separation utilizes the difference in boiling points of gases to separate carbon dioxide and hydrogen contained in the reformed gas through compression, low-temperature liquefaction, etc. The pressure and temperature of the reformed gas when separating carbon dioxide and hydrogen in the reformed gas by cryogenic separation are not particularly limited. Cryogenic separation allows for the liquefaction of carbon dioxide and the recovery of high-concentration CO2 by distillation separation.

[0026] As mentioned above, the reformed gas obtained by reforming converter gas has a high carbon dioxide concentration. By performing cryogenic separation on such a high-concentration reformed gas, it is possible to efficiently separate and recover carbon dioxide while keeping the footprint, energy costs, and equipment costs down. Cryogenic separation equipment can reduce the footprint by about half compared to separation equipment using the pressure swing adsorption (PSA) method, which uses zeolite as a gas separation material. Furthermore, by reforming the converter gas to increase the carbon dioxide concentration, the equipment can be made smaller and equipment costs can be reduced compared to directly producing liquefied carbon dioxide from converter gas or the combustion exhaust gas of converter gas by cryogenic separation, and the energy consumption in the liquefaction process can be significantly reduced.

[0027] 3.2.3 Physical adsorption method using gate-type porous coordination polymers The method for separating carbon dioxide and hydrogen in separation step S2 may include a physical adsorption method using a gate-type porous coordination polymer (gate-type PCP). As shown in Figure 3, the physical adsorption method using gate-type PCP is a method of separating and recovering carbon dioxide by using a material that undergoes a phase change from a non-adsorbent phase to an adsorbent phase by adsorbing carbon dioxide, and a phase change from an adsorbent phase to a non-adsorbent phase by releasing carbon dioxide. Specifically, there is a separation system that uses a pressure swing adsorption method with gate-type PCP as a gas separation material.

[0028] The adsorption behavior of common physical adsorbents such as activated carbon is a type I behavior, as shown in Figure 4A. As gas pressure increases, the amount of gas adsorbed increases; as gas pressure decreases, the amount of gas adsorbed decreases. In other words, the amount of gas adsorbed responds to gas pressure in a Langmuir-type manner, and the adsorption isotherm coincides with the desorption isotherm. When adsorbing and separating carbon dioxide using adsorbents exhibiting type I adsorption behavior, it is necessary to increase the pressure to high levels for adsorption and to decrease the pressure to low levels (high vacuum) for desorption, resulting in high energy consumption for gas separation and recovery. Furthermore, since the adsorption phenomenon of type I adsorption materials is usually exothermic, there is a problem that the adsorption capacity decreases due to the heat generated.

[0029] In contrast, as shown in Figure 4B, the gate-type PCP exhibits non-Type I adsorption characteristics, where the gas pressure and gas adsorption amount do not show a Langmuir-type response, due to the change in structure in response to the gas pressure. For example, when adsorbing carbon dioxide using a gate-type PCP, adsorption of carbon dioxide can be completed rapidly and quickly when the partial pressure of carbon dioxide exceeds a certain level. When desorbing carbon dioxide from a gate-type PCP, it is not necessary to reduce the pressure to a high vacuum, and desorption can be completed rapidly and quickly at a pressure below a certain level. In this embodiment, as described above, the reformed gas obtained by reforming the converter gas has a high carbon dioxide concentration, that is, a high partial pressure of carbon dioxide. By performing physical adsorption using a gate-type PCP on such a reformed gas with a high carbon dioxide concentration, it can be said that carbon dioxide can be efficiently separated from the reformed gas rapidly and quickly. As a result, energy costs and other factors can be significantly reduced.

[0030] For example, gate-type PCPs described in Japanese Patent Publication No. 4141789, Japanese Patent Publication No. 7176683, and Japanese Patent Application Publication No. 2022-182180 are preferably used. Specific examples of patent gate-type PCPs applicable in this embodiment include, for example, those shown below.

[0031] A gate-type PCP according to one embodiment may have a one-dimensional chain structure. For example, the gate-type PCP may be a metal complex represented by the formula: [G(H)2(I)] (wherein G is a transition metal ion, H is a first ligand, and I is a second ligand), or a metal complex represented by the formula: G2(J)3(L3)4 (wherein G is a transition metal ion, J is a ligand, and L is a monovalent counterion).

[0032] A gate-type PCP according to one embodiment may be of a two-dimensional layered type. The two-dimensional layered gate-type PCP refers to a PCP in which the PCP network structure has a two-dimensional layered structure, and this structure is formed by stacking via weak interactions such as van der Waals forces and hydrogen bonds. The two-dimensional layered gate-type PCP has the characteristic that volume expansion occurs only in a specific direction (the direction in which the interlayer space expands), compared to a three-dimensional flexible PCP. Examples of the two-dimensional layered gate-type PCP include a PCP in which Kagome-like two-dimensional network structures are stacked (Kagome-type PCP). The Kagome-type PCP may be represented by the formula: [DE] (wherein D is a divalent transition metal ion, and Cu 2+ , Zn 2+ , Ru 2+ , Rh 2+ , Mo 2+ and Cr 2+ is at least one selected from the group consisting of, and E is an isophthalate ion which may have a substituent).

[0033] The two-dimensional layered gate-type PCP may be those shown below. (1) A PCP represented by the formula: [M(OOC-R-COO)]2 (wherein M is Cu 2+ , Zn 2+ , Ru 2+ , Rh 2+ , Mo 2+ and Cr 2+ is one or more divalent metal ions selected from the group consisting of, and R is a divalent aromatic group in which the two COOH groups are in a meta positional relationship). (2) A PCP composed of copper ions and isophthalate ions having an azide group as a substituent (3) PCP composed of copper ions and isophthalate ions with a benzyloxy group substituent. (4) PCP composed of zinc ions or copper ions and isophthalate ions (5) PCP composed of copper ions and isophthalate ions or isophthalate ions substituted with an ethoxy group. (6) Formula: [Cu2(pyridine-3,5-dicarboxylate)2] n PCP represented by (7) Formula: (MA) n PCP (wherein M represents any metal and A represents a carboxylate with difunctional value) (8) PCPs having a multilayered network structure collectively known as ELM: for example, (8-1) ELM-11 ([Cu(bpy)2(BF4)2](bpy=4,4'-bipyridine)) (8-2) ELM-11 containing OTf ions instead of BF4 (8-3) ELM-13 contains CF3BF3 ions instead of BF4. (8-4) ELM-12 / 3 contains both CF3BF3 ions and OTf ions instead of BF4. (8-5) ELM-31 containing Ni ions instead of copper ions ELM-31 containing (8-6)Co ions (8-7) ELM-31b([Ni(bp1p)2(BF4)2] contains Ni ions instead of copper ions and 1,4-bis(4-pyridyl)benzene (bp1p) instead of the bpy ligand.

[0034] A gate-type PCP according to one embodiment may have a three-dimensional network. Examples of such gate-type PCPs include PCPs collectively referred to as MIL or DUT. MIL is represented as "MIL" in Non-Patent Documents 1 and 2 below. DUT is a PCP represented by Ni2(26ndca)2-Dabco (wherein 26ndca is 2,6-naphthalenedicarboxylic acid and Dabco is 1,8-diazabicyclooctane). [Non-Patent Literature 1] Vos et al., Microporous and mesoporous materials (2009) 221 [Non-Patent Literature 2] Kaskel et al., Advanced Engineering Materials (2009) 93

[0035] 3.3 Other processes As described above, in this embodiment, by combining the reaction step S1 and the separation step S2, hydrogen and carbon dioxide (reformed gas mainly composed of hydrogen and carbon dioxide) can be obtained using the converter gas, and then the carbon dioxide can be separated and recovered. The method of using the converter gas according to this embodiment may include other steps in addition to the reaction step S1 and the separation step S2 described above. An example of other steps will be described below.

[0036] 3.3.1 Storage Process As shown in Figures 1 and 2, a method for utilizing converter gas according to one embodiment may include a storage step S3 for storing the carbon dioxide separated by the separation step S2 underground. The carbon dioxide separated by the separation step S2 can be transported by pipeline or the like, or liquefied and stored in tanks or the like before being transported and buried in a suitable storage location for underground storage. As described above,

[0037] 3.3.2 Hydrogen Utilization Process As described above, in the converter gas utilization method according to this embodiment, in reaction step S1 the converter gas is reformed to obtain a reformed gas containing high concentrations of carbon dioxide and hydrogen, and then in separation step S2 the carbon dioxide and hydrogen of the reformed gas are separated by a predetermined separation method. In other words, according to the method according to this embodiment, high concentrations of hydrogen can be recovered. Such high concentrations of hydrogen can be suitably used for various applications in the steelmaking process. That is, as shown in Figures 1 and 2, the converter gas utilization method according to one embodiment may also have a hydrogen utilization step S4 in which the hydrogen separated in separation step S2 is used as a reducing agent or fuel in the steelmaking process.

[0038] 3.3.3 Utilization of Blast Furnace Gas As shown in Figure 2, in the method of using converter gas according to one embodiment, the reformed gas may be obtained by using converter gas and blast furnace gas. Specifically, the method of using converter gas according to one embodiment is: A blast furnace gas treatment step S11 removes nitrogen from blast furnace gas to obtain nitrogen-removed blast furnace gas containing carbon monoxide and carbon dioxide. Mixing step S12 involves mixing the nitrogen-removed blast furnace gas and the converter gas to obtain a mixed gas. It may also contain [unspecified substance]. In this case, in the reaction step S1 described above, a reformed gas containing carbon dioxide and hydrogen is obtained by reacting the mixed gas with water vapor.

[0039] 3.3.3.1 Blast Furnace Gas Treatment Process Blast furnace gas (BFG), as shown in Figure 2, is the gas discharged from the blast furnace 40 during the steelmaking process using the blast furnace 40. Blast furnace gas has a higher nitrogen concentration than coke oven gas (COG) and converter gas (LDG), and also has the second highest combined concentration of carbon monoxide and carbon dioxide after converter gas. Depending on the type of reducing agent used in the blast furnace process, blast furnace gas may contain hydrogen at a certain concentration or higher. It is believed that by removing nitrogen from such blast furnace gas and mixing it with converter gas, a mixed gas containing higher concentrations of carbon monoxide and carbon dioxide can be obtained. The proportion of nitrogen in blast furnace gas may be, for example, 40% to 60% by volume, or 45% to 55% by volume. The proportion of carbon monoxide in blast furnace gas may be, for example, 15% to 30% by volume, or 20% to 25% by volume. The proportion of carbon dioxide in the blast furnace gas may be, for example, 15% to 30% by volume, or 20% to 25% by volume. The proportion of hydrogen in the blast furnace gas may be, for example, 2% to 6% by volume, or 3% to 5% by volume.

[0040] In the blast furnace gas treatment process S11, nitrogen is removed from the blast furnace gas. The removal of nitrogen from the blast furnace gas may be carried out by a known nitrogen removal device 50. For example, nitrogen can be selectively separated and removed from the blast furnace gas by physical adsorption using an adsorbent or by selective gas separation using a molecular sieve. The proportion of nitrogen in the nitrogen-removed blast furnace gas may be, for example, 40 volume% or less, or 35 volume% or less. The proportion of carbon monoxide in the nitrogen-removed blast furnace gas may be, for example, 12 volume% or more and 20 volume% or less, or 14 volume% or more and 18 volume% or less. The proportion of carbon dioxide in the nitrogen-removed blast furnace gas may be, for example, 12 volume% or more and 20 volume% or less, or 14 volume% or more and 18 volume% or less. The proportion of hydrogen in the nitrogen-removed blast furnace gas may be, for example, 20 volume% or more and 40 volume% or less, or 25 volume% or more and 35 volume% or less.

[0041] 3.3.3.2 Mixing process In the mixing step S12, the nitrogen-removed blast furnace gas and the converter gas are mixed to obtain a mixed gas. The mixing ratio of the nitrogen-removed blast furnace gas and the converter gas is not particularly limited. The method of mixing the nitrogen-removed blast furnace gas and the converter gas is also not particularly limited and can be done by a known mixing device 60. For example, the mixed gas can be obtained by combining the nitrogen-removed blast furnace gas and the converter gas using piping or the like.

[0042] In the embodiment shown in Figure 2, except that reaction step S1 is performed using a mixed gas, the process is the same as in the embodiment shown in Figure 1, allowing for the separation of carbon dioxide and hydrogen contained in the reformed gas obtained by reforming blast furnace gas and converter gas, and enabling the separation and recovery of high concentrations of carbon dioxide.

[0043] 3.4 Others Furthermore, when biocoal is used as the carbon material in the converter process, carbon monoxide generated by the heating reaction of biocoal will be incorporated into the converter gas. In this case, the carbon dioxide separated and recovered by the technology of this disclosure can be carbon negative, resulting in substantially negative carbon dioxide emissions.

[0044] 3.5 Summary As described above, the technology of this disclosure makes it possible to reduce the footprint per unit of actual carbon dioxide recovery by reforming and pre-concentrating converter gas, which contains high concentrations of carbon monoxide and carbon dioxide and is emitted in large quantities during the steelmaking process, by reacting it with water vapor. Furthermore, by separating carbon dioxide and hydrogen from the reformed gas obtained by the reaction of converter gas and water vapor using a specific separation method, carbon dioxide can be separated and recovered even more efficiently. For example, converter gas containing hydrogen: 2 vol%, CO: 65 vol%, and CO2: 18 vol%, can be reformed at 100 Nm³ 3 By contacting the mixture with water vapor at a flow rate of / h and carrying out a water-gas shift reaction in two stages at 400°C and 200°C, a reformed gas containing H2: 40% by volume, CO: 0% by volume, and CO2: 50% by volume is produced at 165 Nm³. 3 It can be obtained at a flow rate of / h. 50% of the reformed gas is carbon dioxide, 40% is hydrogen, and only about 10% is other gases, allowing for efficient separation and recovery of carbon dioxide and hydrogen in subsequent separation processes. [Explanation of Symbols]

[0045] 10 Converter 20 Modification device 30 Separation device 40 Blast Furnace 50 Nitrogen removal equipment 60 Mixing equipment

Claims

1. A method for utilizing converter gas, A reaction step involves reacting the converter gas with steam to obtain a reformed gas containing carbon dioxide and hydrogen. A separation step for separating carbon dioxide and hydrogen contained in the reformed gas, It has, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, Chemical absorption method using carbon dioxide absorbent solution, Cryogenic separation method, and Physical adsorption method using gate-type porous coordination polymers, Including at least one of the following: Methods of using converter gas.

2. A method for utilizing converter gas according to claim 1, It has a storage process for storing the separated carbon dioxide underground. Methods of using converter gas.

3. A method for utilizing converter gas according to claim 1, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned chemical absorption method Includes, The carbon dioxide absorbent is an amine solution. Methods of using converter gas.

4. A method for utilizing converter gas according to claim 1, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned cryogenic separation method including, Methods of using converter gas.

5. A method for utilizing converter gas according to claim 1, The method for separating carbon dioxide and hydrogen in the aforementioned separation step is, The aforementioned physical adsorption method including, Methods of using converter gas.

6. A method for utilizing converter gas according to any one of claims 1 to 5, The above reaction process is carried out in multiple stages. The reaction temperature in the first stage is between 300°C and 400°C. The reaction temperature in the final stage is between 180°C and 200°C. Methods of using converter gas.

7. A method for utilizing converter gas according to any one of claims 1 to 5, A blast furnace gas treatment process involves removing nitrogen from blast furnace gas to obtain nitrogen-removed blast furnace gas containing carbon monoxide and carbon dioxide. A mixing step is to mix the nitrogen-removed blast furnace gas and the converter gas to obtain a mixed gas, Includes, In the reaction step, the mixed gas and the water vapor are reacted to obtain the reformed gas containing carbon dioxide and hydrogen. Methods of using converter gas.

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