System and method for carbon dioxide collection and recycling

Abstract

A system for carbon dioxide collection and recycling according to an embodiment comprises: a sensible heat recovery unit for recovering sensible heat to generate steam; a carbon dioxide collection unit for collecting carbon dioxide; a water electrolysis unit for generating hydrogen; and a methanol synthesis unit for synthesizing methanol, wherein carbon dioxide can be collected from by-product gas containing carbon dioxide to be recycled in various forms, and carbon dioxide emissions can be reduced.

Description

Carbon dioxide capture and resource recovery system and method

[0001] The present invention relates to a carbon dioxide capture and resource recovery system and method, and more specifically, to a carbon dioxide capture and resource recovery system and method capable of capturing carbon dioxide from byproduct gases generated in a steelmaking process and utilizing it as a resource.

[0002] The FINEX (Fine Iron ore Reduction) process is a technology that produces molten iron through facilities called fluidized bed furnaces and melting furnaces without putting iron ore and coal into a blast furnace.

[0003] FIG. 1 is a conceptual diagram illustrating an iron ore reduction process, for example, the FINEX process. Iron ore is fed into a fluidized bed furnace (2), and coal is fed into a melting furnace (3) to generate reducing gas used for reducing iron ore. The fluidized bed furnace (2) reduces the iron ore in the first stage. The iron ore reduced in the first stage is reduced in the melting furnace (3) in the second stage. Thus, molten iron can be produced.

[0004] Meanwhile, some of the carbon dioxide-containing byproduct gas generated during the iron ore reduction process is supplied to a CO2PSA unit (4) that selectively adsorbs carbon dioxide, and the carbon dioxide is removed. The gas from which carbon dioxide has been removed is then supplied to a fluidized bed (2) and used in the iron ore reduction process.

[0005] In addition, a byproduct gas containing carbon dioxide is generated during the iron ore reduction process. The carbon dioxide-containing byproduct gas passes through a cooling unit (5) and is supplied to a power plant (6) for power generation. At this time, the tail gas containing high concentrations of carbon dioxide discharged from the CO2PSA unit (4) is supplied to the power plant (6) along with the carbon dioxide-containing byproduct gas and is used for power generation. In this way, the carbon dioxide-containing byproduct gas is utilized for power generation in the iron ore reduction process.

[0006] Recently, as there is a demand for reducing greenhouse gas emissions in the industrial sector, interest is growing in the development of carbon capture technologies and technologies to utilize carbon dioxide as a resource in various forms, particularly in industries such as steel and power generation.

[0007] As a related prior art, there is Korean Patent Publication No. 10-2022-0027498 (published on March 8, 2022), which discloses a carbon dioxide co-electrolysis system utilizing waste heat.

[0008] The objective of the present invention is to provide a carbon dioxide capture and resource recovery system capable of capturing carbon dioxide from byproduct gas containing carbon dioxide and utilizing it as a resource.

[0009] Another objective of the present invention is to provide a carbon dioxide capture and resource recovery system capable of capturing carbon dioxide from carbon dioxide-containing byproduct gas generated in the iron ore reduction process of a steelmaking process (e.g., FINEX process, etc.) and utilizing it as a resource.

[0010] Another objective of the present invention is to provide a carbon dioxide capture and resource utilization method capable of capturing carbon dioxide from carbon dioxide-containing byproduct gas and utilizing it as a resource.

[0011] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0012] According to one aspect of the present invention for achieving the above-mentioned objective, a carbon dioxide capture and resource recovery system is provided that captures carbon dioxide from a byproduct gas containing carbon dioxide and can utilize it as a resource.

[0013] A carbon dioxide capture and resource recovery system according to one embodiment includes a sensible heat recovery unit that recovers sensible heat from a carbon dioxide-containing byproduct gas to generate steam, a carbon dioxide capture unit that receives a portion of the steam generated from the sensible heat recovery unit and captures carbon dioxide from the carbon dioxide-containing byproduct gas, a water electrolysis unit that receives a portion of the steam generated from the sensible heat recovery unit and generates hydrogen, and a methanol synthesis unit that synthesizes methanol by reacting the carbon dioxide captured from the carbon dioxide capture unit with the hydrogen generated from the water electrolysis unit.

[0014] A carbon dioxide capture and resource recovery system according to one embodiment includes a first steam supply line that supplies a portion of the steam generated in the sensible heat recovery unit to the carbon dioxide capture unit, and a second steam supply line that supplies a portion of the steam generated in the sensible heat recovery unit to the water electrolysis unit.

[0015] According to one embodiment, the carbon dioxide capture unit comprises a capture unit that captures carbon dioxide contained in the byproduct gas by bringing a carbon dioxide-containing byproduct gas and an absorbent liquid that absorbs carbon dioxide into countercurrent contact, and a regeneration unit that separates carbon dioxide and regenerates the absorbent liquid by applying regeneration energy to the absorbent liquid that has captured carbon dioxide. The regenerated absorbent liquid may be supplied to the capture unit.

[0016] According to one embodiment, in the carbon dioxide capture unit, the gas from which carbon dioxide has been removed while passing through the capture unit can be provided as a heat source for a power plant.

[0017] According to one embodiment, in the carbon dioxide capture unit, the absorbent liquid that absorbs carbon dioxide comprises at least one selected from ammonia water, amine-based and inorganic salt absorbent liquids.

[0018] According to one embodiment, some of the steam generated in the sensible heat recovery unit can be supplied to the carbon dioxide capture unit and used as a regenerative energy source for the absorption liquid.

[0019] According to one embodiment, the steam used as a regenerative energy source for the absorbent liquid in the carbon dioxide capture unit may lose heat after being used as a regenerative energy source and be converted into Boiled Feed Water (BFW). The Boiled Feed Water may be recirculated to the Sensible Heat Recovery Unit and used to generate steam.

[0020] According to one embodiment, the carbon dioxide-containing byproduct gas may include at least one of FINEX byproduct gas, blast furnace gas (BFG), converter gas (LDG), FINEX tail gas (FTG), and power generation flue gas.

[0021] According to one embodiment, the methanol synthesis unit comprises: a mixing unit that mixes carbon dioxide captured in the carbon dioxide capture unit and hydrogen generated in the water electrolysis unit to produce a mixed gas; a first compression unit that compresses the mixed gas first; a first cooling unit that cools the mixed gas that is cooled first; a second compression unit that compresses the mixed gas that is cooled first; a second cooling unit that cools the mixed gas that is cooled second; a third compression unit that compresses the mixed gas that is cooled second; a methanol synthesis reaction unit that performs a reaction to synthesize methanol from carbon dioxide and hydrogen in the mixed gas that is compressed third; and a separation and purification unit that separates and purifies the synthesized methanol.

[0022] According to one embodiment, the reactor for synthesizing methanol may be a fixed-bed type tubular reactor.

[0023] According to one embodiment, the catalyst used in the reaction for synthesizing methanol comprises at least one selected from the group consisting of Cu, Zn, Au, Pd, Ni, Pt, Zr, Rh, and combinations thereof.

[0024] According to one embodiment, the reaction for synthesizing the methanol may be carried out at 250°C to 280°C and 50 barg to 90 barg.

[0025] A carbon dioxide capture and resource recovery system according to one embodiment further includes a coke oven into which carbon dioxide captured in the carbon dioxide capture unit is blown. The coke oven can increase the flow rate of coke oven gas (COG) used as a raw material for power generation by utilizing the captured carbon dioxide.

[0026] A carbon dioxide capture and resource recovery system according to one embodiment further includes a synthesis gas generation unit that generates synthesis gas using carbon dioxide captured in the carbon dioxide capture unit as a raw material.

[0027] According to one embodiment, the reactor that generates the synthesis gas may be a fixed-bed type tubular reactor.

[0028] According to one embodiment, the synthesis gas generating unit can produce synthesis gas through a complex reforming reaction. The raw materials for the complex reforming reaction include carbon dioxide (CO2), methane (CH4), and water (H2O). The catalyst for the complex reforming reaction comprises at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof.

[0029] According to one embodiment, the synthesis gas generating unit can produce synthesis gas through a dry reforming reaction. The raw materials for the dry reforming reaction include carbon dioxide (CO2) and methane (CH4). The catalyst for the dry reforming reaction comprises at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof.

[0030] According to one embodiment, the synthesis gas generating unit can produce synthesis gas through a reverse water-gas shift reaction. The raw materials for the reverse water-gas shift reaction include carbon dioxide (CO2) and hydrogen (H2). The catalyst for the reverse water-gas shift reaction comprises at least one selected from the group consisting of Cu, Ni, Co, Pt, Ti, Pd, Ru, Au, Ce, Rh, and combinations thereof.

[0031] According to another aspect of the present invention, a carbon dioxide capture and resource recovery system is provided that captures carbon dioxide from a carbon dioxide-containing byproduct gas generated in an iron ore reduction process of a steelmaking process (e.g., FINEX process, etc.) and can utilize it as a resource.

[0032] A carbon dioxide capture and resource recovery system according to one embodiment comprises: a fluidized bed furnace into which iron ore is fed and which reduces the iron ore in a primary manner; a melting furnace into which coal is fed and which generates a reducing gas used in the iron ore reduction process and which reduces the iron ore in a secondary manner to produce molten iron; a CO2 PSA unit that receives a portion of the carbon dioxide-containing byproduct gas generated in the iron ore reduction process to remove carbon dioxide and provides the gas from which carbon dioxide has been removed to the iron ore reduction process; and a power plant that generates electricity by receiving a portion of the carbon dioxide-containing byproduct gas generated in the iron ore reduction process and / or the carbon dioxide-containing gas provided by the CO2 PSA unit.

[0033] It includes a sensible heat recovery unit that recovers sensible heat from a carbon dioxide-containing byproduct gas discharged from the above fluidized bed to generate steam, a carbon dioxide capture unit that receives a portion of the steam generated from the sensible heat recovery unit and captures carbon dioxide from the carbon dioxide-containing byproduct gas, a water electrolysis unit that receives a portion of the steam generated from the sensible heat recovery unit and generates hydrogen, and a methanol synthesis unit that synthesizes methanol by reacting the carbon dioxide captured by the carbon dioxide capture unit with the hydrogen generated by the water electrolysis unit.

[0034] A carbon dioxide capture and resource recovery system according to one embodiment further includes a coke oven into which carbon dioxide captured in the carbon dioxide capture unit is blown, and a synthesis gas generation unit that generates synthesis gas using the carbon dioxide captured in the carbon dioxide capture unit as a raw material.

[0035] According to another aspect of the present invention, a carbon dioxide capture and resource utilization method is provided, which captures carbon dioxide from a byproduct gas containing carbon dioxide and utilizes it as a resource.

[0036] A carbon dioxide capture and resource recovery method according to one embodiment comprises: a sensible heat recovery step for generating steam by recovering sensible heat from a carbon dioxide-containing byproduct gas; a carbon dioxide capture step for capturing carbon dioxide from the carbon dioxide-containing byproduct gas by receiving a portion of the steam generated in the sensible heat recovery step; a water electrolysis step for generating hydrogen by receiving a portion of the steam generated in the sensible heat recovery step; and a methanol synthesis step for synthesizing methanol by reacting the carbon dioxide captured in the carbon dioxide capture step with the hydrogen generated in the water electrolysis step.

[0037] A carbon dioxide capture and resource utilization method according to one embodiment further includes a coke oven blowing step for blowing carbon dioxide captured in the carbon dioxide capture step into a coke oven, and a synthesis gas generation step for generating synthesis gas using the carbon dioxide captured in the carbon dioxide capture step as a raw material.

[0038] Specific details of other embodiments are included in the specific details and drawings for carrying out the invention.

[0039] According to various embodiments of the present invention, one or more of the following effects are present.

[0040] First, steam can be produced by recovering sensible heat during the capture of carbon dioxide from byproduct gases in steelmaking processes, particularly the FINEX process. Producing steam through sensible heat recovery offers the advantage of reducing energy costs associated with carbon capture by utilizing recycled heat, thereby lowering the overall cost of carbon capture.

[0041] Second, the gas is returned to the power plant after carbon dioxide capture, which has the advantage of maintaining or even increasing power generation without a decrease. This is because the calorific value per unit flow rate of the gas increases after carbon dioxide capture and removal.

[0042] Third, methanol—specifically low-carbon methanol—can be synthesized using captured carbon dioxide and electrolyzed hydrogen and sold to external customers. Accordingly, this offers advantages in reducing carbon dioxide emissions from the steelworks and generating revenue from CCU (Carbon Capture and Utilization) products.

[0043] Fourth, when the captured carbon dioxide is blown into a coke oven, the amount of coke oven gas (COG) can be increased. Accordingly, there are advantages such as increased power generation and reduced external power consumption, and as a result, a reduction in carbon dioxide emissions can be expected.

[0044] Fifth, the captured carbon dioxide can be used for synthesis gas production and as a reducing gas in the steelmaking process. Accordingly, the amount of coal injected can be reduced, and as a result, a reduction in carbon dioxide emissions can be expected.

[0045] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0046] Figure 1 is a conceptual diagram illustrating a steelmaking process, for example, the FINEX process.

[0047] FIG. 2 is a conceptual diagram briefly illustrating a carbon dioxide capture and resource recovery system according to one embodiment.

[0048] FIG. 3 is a conceptual diagram briefly illustrating the detailed configuration and process of a sensible heat recovery unit according to one embodiment.

[0049] FIG. 4 is a conceptual diagram briefly illustrating the detailed configuration and process of a carbon dioxide capture unit according to one embodiment.

[0050] FIG. 5 is a conceptual diagram briefly illustrating the detailed configuration and process of a water electrolysis unit according to one embodiment.

[0051] FIG. 6 is a conceptual diagram briefly illustrating the detailed configuration and process of a methanol synthesis unit according to one embodiment.

[0052] FIG. 7 is a conceptual diagram illustrating the difference in the flow rate of coke oven gas (COG) increasing in process (a) before carbon dioxide is blown into the coke oven and process (b) after carbon dioxide is blown into the coke oven according to one embodiment.

[0053] FIG. 8 is a conceptual diagram illustrating the composite reforming reaction (a), dry reforming reaction (b), and reverse water-gas shift reaction (c) of a synthesis gas generation unit according to one embodiment.

[0054] FIG. 9 is a flowchart illustrating a carbon dioxide capture and resource recovery method according to one embodiment.

[0055] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below but may be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims. Throughout the specification, the same reference numerals refer to the same components.

[0056] Although terms such as "first," "second," etc., are used to describe various components, it goes without saying that these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may also be the second component.

[0057] Throughout the specification, unless specifically stated otherwise, each component may be singular or plural.

[0058] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0059] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0060] Singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may be omitted or additional components or steps may be included.

[0061] Throughout the specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less unless specifically stated otherwise.

[0062] Hereinafter, a carbon dioxide capture and resource recovery system and a carbon dioxide capture and resource recovery method according to various embodiments will be described in detail with reference to the attached drawings.

[0063] [Overall Configuration of the Carbon Dioxide Capture and Recovery System]

[0064] FIG. 2 is a conceptual diagram briefly illustrating a carbon dioxide capture and resource recovery system according to one embodiment.

[0065] A carbon dioxide capture and resource recovery system (1) according to one embodiment includes a sensible heat recovery unit (10), a carbon dioxide capture unit (20), a water electrolysis unit (30), a methanol synthesis unit (40), a coke oven (50), and a synthesis gas generation unit (60).

[0066] The sensible heat recovery unit (10) recovers sensible heat from carbon dioxide-containing byproduct gas.

[0067] Here, sensible heat refers to thermal energy used solely for temperature changes without phase changes when heating or cooling a substance.

[0068] The sensible heat recovery unit (10) recovers sensible heat from a high-temperature carbon dioxide-containing byproduct gas to generate steam.

[0069] According to one embodiment, the carbon dioxide-containing byproduct gas may be a high-temperature carbon dioxide-containing byproduct gas generated in the FINEX process.

[0070] However, carbon dioxide-containing byproduct gas is not necessarily limited to carbon dioxide-containing byproduct gas generated in the FINEX process.

[0071] Accordingly, according to various embodiments, the carbon dioxide-containing byproduct gas may be any one of blast furnace gas (BFG), converter gas (LDG), FINEX tail gas (FTG), or power generation flue gas generated from combustion furnaces, heating furnaces, power plants, etc.

[0072] The carbon dioxide capture unit (20) captures carbon dioxide from carbon dioxide-containing byproduct gas.

[0073] The carbon dioxide capture unit (20) can receive a portion of the steam generated in the sensible heat recovery unit (10) and use it as a regenerative energy source for the absorption liquid when capturing carbon dioxide.

[0074] The water electrolysis unit (30) generates hydrogen by water electrolysis.

[0075] The water electrolysis unit (30) can receive some of the steam generated in the sensible heat recovery unit (10), and uses the supplied steam as a raw material to produce hydrogen.

[0076] The methanol synthesis unit (40) synthesizes methanol by reacting carbon dioxide captured in the carbon dioxide capture unit (20) with hydrogen generated in the water electrolysis unit (30).

[0077] The coke oven (50) can increase the flow rate of coke oven gas (COG) by blowing in carbon dioxide collected in the carbon dioxide collection unit (20).

[0078] Accordingly, the power generation of the power plant (6) can be increased due to the increased effect of coke oven gas (COG).

[0079] The synthesis gas generation unit (60) generates synthesis gas using carbon dioxide captured in the carbon dioxide capture unit (20) as a raw material.

[0080] According to a preferred embodiment, the carbon dioxide capture and resource recovery system (1) can be applied to an iron ore reduction facility, specifically a FINEX facility, which includes a fluidized bed furnace (2), a melting furnace (3), a CO2 PSA section (4), and a power plant (6).

[0081] Referring to FIG. 2, the fluidized bed (2) can receive the input of iron ore and reduce the iron ore in the first stage.

[0082] In the melting furnace (3), coal is fed in, and a reducing gas used in the reduction process of iron ore is generated, and the iron ore that has been reduced once is reduced twice to produce molten iron.

[0083] The CO2 PSA unit (4) can receive a portion of the carbon dioxide-containing byproduct gas generated in the iron ore reduction process and selectively separate the carbon dioxide to remove carbon dioxide from the gas. In this process, the gas from which carbon dioxide has been removed can be supplied to the iron ore reduction process.

[0084] The power plant (6) generates electricity by receiving a portion of the carbon dioxide-containing byproduct gas generated from the reduction process of iron ore and the high-concentration carbon dioxide-containing gas emitted from the CO2 PSA unit (4).

[0085] Hereinafter, detailed configurations included in the carbon dioxide capture and resource recovery system (1) according to various embodiments will be described in more detail.

[0086] [Sensible Heat Recovery Unit]

[0087] FIG. 3 is a conceptual diagram briefly illustrating the detailed configuration and process of a sensible heat recovery unit according to one embodiment.

[0088] The sensible heat recovery unit (10) recovers sensible heat from high-temperature byproduct gas, namely carbon dioxide-containing byproduct gas, to generate steam. Sensible heat refers to thermal energy that is used only for temperature changes without phase changes when heating or cooling a substance.

[0089] According to one embodiment, the carbon dioxide-containing byproduct gas may be a high-temperature byproduct gas generated in the FINEX process.

[0090] In addition, according to various embodiments, the carbon dioxide-containing byproduct gas may be any one of blast furnace gas (BFG), converter gas (LDG), FINEX tail gas (FTG), or power generation flue gas generated from a combustion furnace, heating furnace, power plant, etc.

[0091] Some of the steam generated by the sensible heat recovered from the sensible heat recovery unit (10) is supplied to the carbon dioxide capture unit (20) and can be used as a renewable energy source for the carbon dioxide capture process (i.e., a renewable energy source for the absorption liquid for carbon dioxide capture).

[0092] To this end, preferably, a first steam supply line (11) may be further included to supply some of the steam generated in the sensible heat recovery unit (10) to the carbon dioxide capture unit (20).

[0093] In addition, another portion of the steam generated by the sensible heat recovered from the sensible heat recovery unit (10) can be supplied to the water electrolysis unit (30) and used as a raw material for the water electrolysis process that generates hydrogen.

[0094] To this end, preferably, a second steam supply line (12) may be further included to supply some of the steam generated in the sensible heat recovery unit (10) to the water electrolysis unit (30).

[0095] Meanwhile, the steam supplied through the first steam supply line (11) can be converted into Boiled Feed Water (BFW) after losing heat following use as a renewable energy source for carbon dioxide capture absorption liquid. In other words, the steam can be converted into a state where its temperature has dropped after losing heat, i.e., Boiled Feed Water (BFW). Meanwhile, the converted Boiled Feed Water can be re-supplied to the Sensible Heat Recovery Unit (10) and used for steam generation. At this time, it is preferable to produce steam in the Sensible Heat Recovery Unit (10) by making up the Boiled Feed Water (BFW) in an amount equal to the steam supplied to the water electrolysis unit (30) and used.

[0096] [Carbon Capture and Storage Unit]

[0097] FIG. 4 is a conceptual diagram briefly illustrating the detailed configuration and process of a carbon dioxide capture unit according to one embodiment.

[0098] The carbon dioxide capture unit (20) can capture carbon dioxide from carbon dioxide-containing byproduct gas.

[0099] The carbon dioxide capture unit (20) can receive a portion of the steam generated in the sensible heat recovery unit (10) and use it as a regenerative energy source for the absorption liquid when capturing carbon dioxide.

[0100] According to one embodiment, the carbon dioxide capture unit (20) may include a capture unit (21) capable of capturing carbon dioxide by receiving a carbon dioxide-containing byproduct gas, and a regeneration unit (22) for regenerating an absorption liquid used to capture carbon dioxide.

[0101] Preferably, the capture unit (21) can bring the carbon dioxide-containing byproduct gas and the absorbent liquid that absorbs carbon dioxide into counter-current contact. Accordingly, the carbon dioxide contained in the byproduct gas can be captured in the absorbent liquid.

[0102] Preferably, the regeneration unit (22) can receive the absorbent solution that has captured carbon dioxide while passing through the capture unit (21) and apply regeneration energy. Accordingly, the absorbent solution that has captured carbon dioxide is separated from the carbon dioxide while passing through the regeneration unit (22) and can be regenerated into an absorbent solution that can be reused in the capture unit (21).

[0103] Meanwhile, the gas from which carbon dioxide has been removed after passing through the capture unit (21) in the carbon dioxide capture unit (20) can be supplied to the power plant (6) (see FIG. 2) and provided as a heat source necessary for power generation.

[0104] According to one embodiment, the absorbent liquid that captures carbon dioxide, i.e., selectively absorbs carbon dioxide in the carbon dioxide capture unit, may include at least one selected from ammonia water, amine-based (e.g., MEA, MDEA, etc.) and inorganic salt absorbent liquid.

[0105] And some of the steam generated in the aforementioned sensible heat recovery unit (10) (see FIG. 2) can be supplied to the carbon dioxide capture unit (20) and used as a regenerative energy source for the absorption liquid for carbon dioxide capture. At this time, after being used as a regenerative energy source for the absorption liquid, the steam can be cooled and converted into Boiled Feed Water (BFW). The Boiled Feed Water can be supplied back to the sensible heat recovery unit (10) and generate steam.

[0106] With reference to FIG. 4, the carbon dioxide capture and absorption liquid regeneration process in the carbon dioxide capture unit (20) will be briefly described. First, a byproduct gas containing carbon dioxide and an absorption liquid for carbon dioxide capture are brought into contact with a counter current in the capture process. In the capture process, the absorption liquid chemically absorbs carbon dioxide. The absorption liquid that has absorbed (or captured) carbon dioxide can be separated from the carbon dioxide by regeneration energy applied in the regeneration process. After regeneration, the absorption liquid can be supplied back to the capture process and used for the absorption (or capture) of carbon dioxide.

[0107] Meanwhile, the gas from which carbon dioxide has been removed during the capture process can be used as a heat source for power plants. As such, there are no adverse side effects, such as a reduction in power generation, during the carbon dioxide capture and separation process.

[0108] In addition, the absorbent solution used for carbon dioxide capture may be ammonia water, amine-based (e.g., MEA, MDEA, etc.), inorganic salt absorbent solution, etc. According to a preferred embodiment, it is preferable to use ammonia water as the absorbent solution. Using ammonia water as the absorbent solution can lower the separation temperature between the absorbent solution and carbon dioxide, thereby reducing energy costs. However, it is not limited thereto, and various other absorbent solutions suitable for carbon dioxide capture can be used without limitation.

[0109] Meanwhile, the regeneration energy required for the regeneration of the absorbent liquid can be generated from steam in the sensible heat recovery unit (10) (see FIG. 3). According to one embodiment, the absorbent liquid can be regenerated by indirectly heat-exchanging the absorbent liquid with steam.

[0110] At this time, the steam from which heat has been removed after being used as renewable energy is converted back into Boiled Feed Water (BFW) and supplied to the Sensible Heat Recovery Unit (10) (see FIG. 3) and can be used to generate steam.

[0111] [Water Electrolysis]

[0112] FIG. 5 is a conceptual diagram briefly illustrating the detailed configuration and process of a water electrolysis unit according to one embodiment.

[0113] The water electrolysis unit (30) receives a portion of the steam generated in the sensible heat recovery unit (10) (see FIG. 2) and uses the steam as a raw material to produce hydrogen.

[0114] Steam (H2O) generated through the sensible heat recovery unit (10) (see FIG. 2) can produce hydrogen (H2) through the water electrolysis process shown in FIG. 5 using the following [Equation 1].

[0115] [Equation 1]

[0116]

[0117] According to a preferred embodiment, hydrogen (H2) can be produced using renewable energy or based on grid power. According to one embodiment, the water electrolysis unit (30) may include a high-temperature water electrolysis stack (31). The hydrogen (H2) generated in the water electrolysis unit (30) can be supplied to the methanol synthesis unit (40) and used as a raw material for synthesizing low-carbon methanol.

[0118] [Methanol Synthesis Department]

[0119] FIG. 6 is a conceptual diagram briefly illustrating the detailed configuration and process of a methanol synthesis unit according to one embodiment.

[0120] The methanol synthesis unit (40) synthesizes methanol by reacting carbon dioxide captured in the carbon dioxide capture unit (20) with hydrogen generated in the water electrolysis unit (30).

[0121] Referring to FIG. 6, a methanol synthesis unit (40) according to one embodiment may include a mixing unit (41), a first compression unit (42), a first cooling unit (43), a second compression unit (44), a second cooling unit (45), a third compression unit (46), a methanol synthesis reaction unit (47), and a separation and purification unit (48).

[0122] The mixing unit (41) can produce a mixed gas by mixing carbon dioxide collected in the carbon dioxide collection unit (20) and hydrogen generated in the water electrolysis unit (30).

[0123] The first compression unit (42) can compress the mixed gas first.

[0124] The first cooling unit (43) can first cool the first compressed mixed gas.

[0125] The second compression unit (44) can compress the first cooled mixed gas a second time.

[0126] The second cooling unit (45) can secondarily cool the secondarily compressed mixed gas.

[0127] The third compression unit (46) can compress the second cooled mixed gas a third time.

[0128] The methanol synthesis reaction unit (47) can perform a reaction to synthesize methanol from carbon dioxide and hydrogen in the above tertiary compressed mixed gas.

[0129] The separation and purification unit (48) can separate and purify the synthesized methanol.

[0130] According to one embodiment, the reactor for synthesizing methanol in the methanol synthesis unit (40) may use a fixed-bed type tubular reactor.

[0131] According to one embodiment, the catalyst used in the reaction for synthesizing methanol in the methanol synthesis unit (40) may include at least one selected from the group consisting of Cu, Zn, Au, Pd, Ni, Pt, Zr, Rh, and combinations thereof.

[0132] According to one embodiment, the reaction for synthesizing methanol in the methanol synthesis unit (40) can be carried out at 250°C to 280°C and 50 barg to 90 barg.

[0133] With reference to FIG. 6, the process of the methanol synthesis unit (40) will be briefly described. FIG. 6 shows the process of low-carbon methanol synthesis using carbon dioxide and hydrogen. The methanol catalytic reaction is an intense exothermic reaction. Therefore, in order to maintain a constant reaction temperature, Boiled Feed Water (BFW) is supplied to the walls of the reactor to produce steam, which can then be utilized in the steelmaking process. To satisfy high pressure conditions, multi-stage compression (e.g., 1st to 3rd compression) can be performed. During the final compression (e.g., 3rd compression), the temperature of the mixed gas may rise. The mixed gas with the risen temperature can be supplied to the methanol synthesis reactor without cooling to perform the synthesis reaction and satisfy the reaction temperature conditions.

[0134] [Increased Composition of Coke Oven Gas (COG)]

[0135] FIG. 7 is a conceptual diagram illustrating the difference in the flow rate of coke oven gas (COG) increasing in process (a) before carbon dioxide is blown into the coke oven and process (b) after carbon dioxide is blown into the coke oven according to one embodiment.

[0136] The coke oven (50) can increase the flow rate of coke oven gas (COG) by blowing in carbon dioxide collected in the carbon dioxide collection unit (20).

[0137] Accordingly, the power generation of the power plant (6) can be increased due to the increased effect of coke oven gas (COG).

[0138] Referring to Fig. 7, the effects before and after injecting carbon dioxide collected in the carbon dioxide collection unit (20) (see Fig. 2) into the coke oven (50) are shown.

[0139] FIG. 7(a) shows the case before carbon dioxide is injected into the coke oven (50) and the amount of coke oven gas (COG) is not increased. In the coke oven (50), coal is carbonized to produce coke, and coke oven gas (COG) is generated. The coke oven gas (COG) can be used to generate electricity in the power plant (6).

[0140] Figure 7 (b) shows that the amount of coke oven gas (COG) increased after carbon dioxide was blown into the coke oven (50).

[0141] When the captured carbon dioxide is blown into the coke oven (50), a reverse-Boudouard reaction (see Equation 2 below) occurs using the attached carbon present on the wall of the coke oven (50) and the uncollected heat, producing CO. As a result, the flow rate of the coke oven gas (COG) is increased.

[0142] [Equation 2]

[0143]

[0144] The increased amount of coke oven gas (COG) is used in the furnace process, and some of it can be supplied to a power plant (6) (see FIG. 2) to be used as fuel for power generation.

[0145] Accordingly, increasing the flow rate of coke oven gas (COG) leads to an increase in power generation, which can reduce the amount of electricity received from external sources. As a result, carbon dioxide generated during the steelmaking process can be reduced.

[0146] [Synthetic Gas Generation Unit]

[0147] FIG. 8 is a conceptual diagram illustrating the composite reforming reaction (a), dry reforming reaction (b), and reverse water-gas shift reaction (c) of a synthesis gas generation unit according to one embodiment.

[0148] The synthesis gas generation unit (60) generates synthesis gas using carbon dioxide captured in the carbon dioxide capture unit (20) as a raw material.

[0149] According to one embodiment, a fixed-bed type tubular reactor may be used to generate synthesis gas in the synthesis gas generation unit (60).

[0150] Referring to Figure 8, a synthesis gas process using captured carbon dioxide as a raw material is shown.

[0151] Referring to FIG. 8(a), a synthesis gas generating unit (60) according to one embodiment can produce synthesis gas through a composite reforming reaction.

[0152] According to one embodiment, the raw materials for the composite reforming reaction may include carbon dioxide (CO2), methane (CH4), and water (H2O).

[0153] According to one embodiment, the catalyst for the composite reforming reaction may include at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof. The reaction conditions may be carried out at a temperature of 700°C to 1000°C and a pressure of 5 barg to 25 barg.

[0154] The combined reforming reaction to produce synthesis gas using captured carbon dioxide can follow [Equation 3] below.

[0155] [Equation 3]

[0156]

[0157] Referring to Fig. 8(b), a synthesis gas generating unit (60) according to one embodiment can produce synthesis gas through a dry reforming reaction.

[0158] According to one embodiment, the raw materials for the dry reforming reaction may include carbon dioxide (CO2) and methane (CH4).

[0159] According to one embodiment, the catalyst for the dry reforming reaction may include at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof. The reaction conditions may be carried out at a temperature of 700°C to 1000°C and a pressure of 5 barg to 25 barg.

[0160] The dry reforming reaction to produce synthesis gas using captured carbon dioxide can follow [Equation 4] below.

[0161] [Equation 4]

[0162]

[0163] Referring to Fig. 8 (c), a synthesis gas generating unit (60) according to one embodiment can produce synthesis gas through a reverse water-gas shift reaction.

[0164] According to one embodiment, the raw materials for the reverse water-gas shift reaction may include carbon dioxide (CO2) and hydrogen (H2).

[0165] According to one embodiment, the catalyst for the reverse water-gas shift reaction may include at least one selected from the group consisting of Cu, Ni, Co, Pt, Ti, Pd, Ru, Au, Ce, Rh, and combinations thereof. The reaction conditions may be carried out at a temperature of 300°C to 800°C and a pressure of 1 barg to 20 barg.

[0166] The reverse water-gas shift reaction that produces synthesis gas using captured carbon dioxide can follow [Equation 5] below.

[0167] [Equation 5]

[0168]

[0169] Hereinafter, a carbon dioxide capture and resource recovery method will be described. The carbon dioxide capture and resource recovery method can be performed using the carbon dioxide capture and resource recovery system (1) described above.

[0170] [Carbon Capture and Recovery Methods]

[0171] FIG. 9 is a flowchart illustrating a carbon dioxide capture and resource recovery method according to one embodiment.

[0172] A carbon dioxide capture and resource recovery method according to one embodiment may include a sensible heat recovery step (S10), a carbon dioxide capture step (S20), a water electrolysis step (S30), a methanol synthesis step (S40), a coke oven injection step (S50), and a synthesis gas generation step (S60).

[0173] The sensible heat recovery step (S10) is a process step that recovers sensible heat from carbon dioxide-containing byproduct gas to generate steam (see FIG. 3).

[0174] The carbon dioxide capture step (S20) is a process step for capturing carbon dioxide from carbon dioxide-containing byproduct gas by supplying a portion of the steam generated in the sensible heat recovery step (S10) (see FIG. 4).

[0175] The water electrolysis step (S30) is a water electrolysis process step that generates hydrogen by receiving a portion of the steam generated in the sensible heat recovery step (S10) (see FIG. 5).

[0176] The methanol synthesis step (S40) is a process step for synthesizing methanol by reacting carbon dioxide captured in the carbon dioxide capture step (S20) with hydrogen generated in the water electrolysis step (S30) (see FIG. 6).

[0177] The coke oven blowing step (S50) is a process step in which carbon dioxide captured in the carbon dioxide capture step (S20) is blown into a coke oven (see FIG. 7).

[0178] The synthesis gas generation step (S60) is a process step for generating synthesis gas using carbon dioxide captured in the carbon dioxide capture step (S20) as a raw material (see FIG. 8).

[0179] [Table 1] below shows the change in carbon dioxide generation, i.e., the carbon dioxide reduction effect, when a carbon dioxide capture and resource recovery system and method according to one embodiment are applied to a FINEX facility.

[0180]

[0181] CO2 is generated by the use of boiler feedwater (BFW) in the sensible heat recovery stage (S10). In the carbon dioxide capture stage (S20), CO2 generation due to electricity usage is reduced, and CO2 is reduced through CO2 removal. CO2 is generated by electricity consumption in the water electrolysis stage (S30). CO2 is generated by electricity consumption in the methanol synthesis stage (S40). In the coke oven injection stage (S50), CO2 is reduced by the reduction in the amount of water used due to the increase in coke oven gas (COG). In the synthesis gas generation stage (S60), CO2 is generated by the use of electricity and methane, etc., during the production of synthesis gas. Additionally, a CO2 reduction effect can be achieved by using synthesis gas as a reducing gas in the steelmaking process to reduce coal consumption. According to Table 1, a CO2 reduction effect of approximately 223 tons per day can be expected.

[0182] As described above, according to various embodiments, steam can be produced by recovering sensible heat during the capture of carbon dioxide from byproduct gases in a steelmaking process, particularly in the FINEX process. By producing steam through sensible heat recovery, the cost of captured energy can be reduced by using the regenerated heat from carbon dioxide capture, thereby reducing the cost of carbon dioxide capture.

[0183] In addition, according to various embodiments, the gas after carbon dioxide capture is returned to the power plant, so that the power generation is maintained or increased without decrease. This is because the calorific value per unit flow rate of the gas increases after carbon dioxide capture and removal.

[0184] Furthermore, according to various embodiments, methanol, specifically low-carbon methanol, can be synthesized using captured carbon dioxide and electrolyzed hydrogen and sold to external customers. Accordingly, this is advantageous for reducing carbon dioxide emissions from steel mills and generating revenue from CCU (Carbon Capture and Utilization) products.

[0185] In addition, according to various embodiments, when captured carbon dioxide is blown into a coke oven, the amount of coke oven gas (COG) can be increased. Accordingly, there are advantages such as increased power generation and reduced external power consumption, and as a result, carbon dioxide emissions can be reduced.

[0186] In addition, according to various embodiments, the captured carbon dioxide can be used for synthesis gas production and as a reducing gas for the steelmaking process. Accordingly, the amount of coal injected can be reduced, and as a result, carbon dioxide emissions can be reduced.

[0187] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while describing the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. A sensible heat recovery unit that recovers sensible heat from carbon dioxide-containing byproduct gas to generate steam; A carbon dioxide capture unit that receives a portion of the steam generated in the above-mentioned sensible heat recovery unit and captures carbon dioxide from carbon dioxide-containing byproduct gas; A water electrolysis unit that generates hydrogen by receiving a portion of the steam generated in the above-mentioned sensible heat recovery unit; and A methanol synthesis unit that synthesizes methanol by reacting carbon dioxide captured in the carbon dioxide capture unit with hydrogen generated in the water electrolysis unit; A carbon dioxide capture and resource recovery system including 2. In Paragraph 1, A first steam supply line that supplies a portion of the steam generated in the above sensible heat recovery unit to the above carbon dioxide capture unit; and A second steam supply line that supplies a portion of the steam generated in the above-mentioned sensible heat recovery unit to the above-mentioned water electrolysis unit; A carbon dioxide capture and resource recovery system including 3. In Paragraph 1, The above carbon dioxide capture unit is, A capture unit that captures carbon dioxide contained in the byproduct gas by bringing the byproduct gas containing carbon dioxide into counter-current contact with an absorbent liquid that absorbs carbon dioxide; and A regeneration unit that applies regeneration energy to the absorbent solution that has captured carbon dioxide to separate the carbon dioxide and regenerate the absorbent solution; is included. The above-mentioned regenerated absorption solution is supplied to the above-mentioned capture unit, Carbon dioxide capture and recovery system.

4. In Paragraph 3, In the above carbon dioxide capture unit, the gas from which carbon dioxide has been removed while passing through the capture unit is provided as a heat source for the power plant. Carbon dioxide capture and recovery system.

5. In Paragraph 3, In the above carbon dioxide capture unit, An absorbent solution that absorbs carbon dioxide comprises at least one selected from ammonia water, amine-based and inorganic salt absorbent solutions, Carbon dioxide capture and recovery system.

6. In Paragraph 3, Some of the steam generated in the above sensible heat recovery unit is supplied to the above carbon dioxide capture unit and used as a regenerative energy source for the absorption liquid, Carbon dioxide capture and recovery system.

7. In Paragraph 6, The steam used as a regenerative energy source for the absorbent liquid in the above-mentioned carbon dioxide capture unit is cooled after use as a regenerative energy source and converted into Boiled Feed Water (BFW), and The above boiler feedwater is recirculated to the above sensible heat recovery unit and used for steam generation, Carbon dioxide capture and recovery system.

8. In Paragraph 1, The above methanol synthesis unit is, A mixing unit that mixes carbon dioxide captured in the carbon dioxide capture unit and hydrogen generated in the water electrolysis unit to produce a mixed gas; A first compression unit for primary compressing the above mixed gas; A first cooling unit for first cooling the above-mentioned first compressed mixed gas; A second compression unit that secondarily compresses the above first-cooled mixed gas; A second cooling unit for secondarily cooling the above secondarily compressed mixed gas; A third compression unit that compresses the above secondarily cooled mixed gas for the third time; A methanol synthesis reaction unit that performs a reaction to synthesize methanol from carbon dioxide and hydrogen in the above-mentioned tertiary compressed mixed gas; and A separation and purification unit for separating and purifying the synthesized methanol above; A carbon dioxide capture and resource recovery system including 9. In Paragraph 1, The reactor for synthesizing the above methanol is a fixed-bed type tubular reactor, Carbon dioxide capture and recovery system.

10. In Paragraph 1, The catalyst used in the reaction for synthesizing the methanol above comprises at least one selected from the group consisting of Cu, Zn, Au, Pd, Ni, Pt, Zr, Rh, and combinations thereof, and The reaction for synthesizing the methanol above is carried out at 250°C to 280°C and 50 barg to 90 barg, Carbon dioxide capture and recovery system.

11. In Paragraph 1, It further includes a coke oven into which carbon dioxide captured in the carbon dioxide capture unit is blown; The above coke oven is, Using the captured carbon dioxide above to increase the flow rate of coke oven gas (COG) used as a power generation fuel, Carbon dioxide capture and recovery system.

12. In Paragraph 1, A synthesis gas generation unit that generates synthesis gas using carbon dioxide captured in the above-mentioned carbon dioxide capture unit as a raw material; A carbon dioxide capture and resource recovery system that further includes 13. In Paragraph 12, The reactor that generates the above synthesis gas is a fixed-bed type tubular reactor, Carbon dioxide capture and recovery system.

14. In Paragraph 12, The above synthesis gas generation unit produces synthesis gas through a complex reforming reaction, The raw materials for the above complex reforming reaction include carbon dioxide (CO2), methane (CH4), and water (H2O), and The catalyst for the above composite reforming reaction comprises at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof. Carbon dioxide capture and recovery system.

15. In Paragraph 12, The above synthesis gas generation unit produces synthesis gas through a dry reforming reaction, The raw materials for the above dry reforming reaction include carbon dioxide (CO2) and methane (CH4), and The catalyst for the above dry reforming reaction comprises at least one selected from the group consisting of Ni, Mg, Ca, Cr, Co, Ce, Fe, Zn, Zr, La, and combinations thereof. Carbon dioxide capture and recovery system.

16. In Paragraph 12, The above synthesis gas generation unit produces synthesis gas through a reverse water-gas shift reaction, The raw materials for the above reverse water-gas shift reaction include carbon dioxide (CO2) and hydrogen (H2), and The catalyst for the above-mentioned reverse water-gas shift reaction comprises at least one selected from the group consisting of Cu, Ni, Co, Pt, Ti, Pd, Ru, Au, Ce, Rh, and combinations thereof. Carbon dioxide capture and recovery system.

17. In Paragraph 1, A fluidized bed furnace into which iron ore is fed and which primarily reduces the iron ore; and A melting furnace into which coal is fed, in which reducing gas used in the iron ore reduction process is generated, and in which iron ore is secondarily reduced to produce molten iron; A carbon dioxide capture and resource recovery system that further includes 18. In Paragraph 17, A CO2 PSA unit that receives a portion of the carbon dioxide-containing byproduct gas generated in the iron ore reduction process, removes carbon dioxide, and supplies the gas from which carbon dioxide has been removed to the iron ore reduction process; and A power plant that generates electricity by receiving a portion of the carbon dioxide-containing byproduct gas generated in the iron ore reduction process and / or the carbon dioxide-containing gas supplied from the CO2 PSA unit; A carbon dioxide capture and resource recovery system that further includes 19. Sensible heat recovery step for generating steam by recovering sensible heat from carbon dioxide-containing byproduct gas; A carbon dioxide capture step that captures carbon dioxide from a carbon dioxide-containing byproduct gas by receiving a portion of the steam generated in the above sensible heat recovery step; A water electrolysis step that generates hydrogen by receiving a portion of the steam generated in the above sensible heat recovery step; and A methanol synthesis step for synthesizing methanol by reacting the carbon dioxide captured in the carbon dioxide capture step with the hydrogen generated in the water electrolysis step; A carbon dioxide capture and resource utilization method including 20. In Paragraph 19, A coke oven blowing step for blowing carbon dioxide captured in the above carbon dioxide capture step into a coke oven; and A synthesis gas generation step that generates synthesis gas using carbon dioxide captured in the above carbon dioxide capture step as a raw material; A carbon dioxide capture and resource recovery method including further

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