Ironmaking process coupled with carbon capture and in situ conversion, system and applications thereof

Abstract

This invention discloses a method, system, and application of ironmaking that couples carbon capture and in-situ conversion. The method employs a dual-functional composite material for adsorption and catalysis, comprising an adsorbent component and a catalytic component. The adsorbent component is a regenerable CO2 adsorbent, and the catalytic component is a catalyst capable of catalyzing in-situ hydrogenation conversion. The method includes the following steps: capturing carbon from coal gas using a CO2 adsorbent to obtain decarbonized coal gas; regenerating the CO2 adsorbent to release CO2, and simultaneously, under the action of the catalyst, performing in-situ hydrogenation conversion on the released CO2 to obtain CO2 converted gas; mixing the decarbonized coal gas and the CO2 converted gas to form a mixed gas, which is then injected into a metallurgical reactor for smelting. This invention effectively solves the problem of large-scale CO2 consumption by coupling CO2 capture and conversion utilization with the ironmaking system, realizing carbon recycling and hydrocarbon coupling reduction in the ironmaking system, and effectively reducing carbon emissions from the ironmaking system.

Description

Technical Field

[0001] This invention relates to the field of low-carbon ironmaking technology, and in particular to an ironmaking method, system, and application that couples carbon capture and in-situ conversion. Background Technology

[0002] The steel industry accounts for approximately 15% of the country's total carbon emissions, making it the largest carbon emitter among manufacturing sectors. Currently, blast furnace-converter long-process steelmaking accounts for about 90% of crude steel production in my country. Therefore, developing low-carbon technologies for long-process steelmaking centered on blast furnaces is crucial for carbon emission reduction in the steel industry. Simultaneously, developing new gas-based direct reduction shaft furnace processes is also of great significance in the context of a future energy system primarily powered by hydrogen.

[0003] Carbon capture, utilization, and storage (CCUS) technology is the most direct means of carbon reduction and a fundamental technology for achieving carbon neutrality in blast furnace ironmaking processes that heavily utilize coal and coke. For gas-based vertical shaft furnace processes, since the furnace charge contains carbon, the top gas also contains a certain concentration of CO2, requiring CCUS technology as a supplementary carbon reduction method. Although CCUS technology has significant carbon reduction capabilities, its high energy consumption limits its application in the steel industry. Traditional amine-based carbon capture technology requires first lowering the temperature of the carbon-containing gas source for CO2 capture, and then raising the temperature for desorption. This technology wastes gas heat and increases desorption energy consumption significantly. Furthermore, limited by the market size of CO2 itself and related products, the captured and separated CO2 still lacks effective large-scale utilization pathways, further restricting the development of CCUS technology in the steel industry. Therefore, developing low-energy carbon capture technology that couples waste heat utilization of carbon-containing gases with CO2 capture in steel enterprises, and combining it with large-scale CO2 utilization technology, is a key issue for carbon emission reduction in the long process of blast furnace-converter and the short process of vertical shaft furnace-electric furnace. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an ironmaking method, system and application that couples carbon capture and in-situ conversion. By combining the low-energy carbon capture technology that couples the utilization of waste heat from carbon-containing gases in steel enterprises with CO2 capture, and with large-scale CO2 utilization technology, carbon emission reduction can be achieved in processes such as blast furnace-converter and vertical shaft furnace-electric furnace.

[0005] To achieve the above and other related objectives, the first aspect of the present invention provides an ironmaking method coupling carbon capture and in-situ conversion. The method employs an adsorption-catalysis bifunctional composite material for carbon capture and in-situ conversion. The adsorption-catalysis bifunctional composite material includes an adsorbent component and a catalytic component. The adsorbent component is a regenerable CO2 adsorbent, and the catalytic component is a catalyst capable of catalyzing an in-situ hydrogenation conversion reaction. The method includes the following steps:

[0006] CO2 adsorption: Carbon capture of coal gas is achieved through CO2 adsorbent to obtain decarbonized coal gas;

[0007] CO2 conversion: The CO2 adsorbent that has adsorbed CO2 is regenerated to release CO2. At the same time, under the action of the catalyst, the released CO2 is hydrogenated in situ to obtain CO2 conversion gas, which contains CO and / or methane.

[0008] The decarbonized coal gas is mixed with CO2 conversion gas to form a mixed gas, which is then injected into a metallurgical reactor for smelting.

[0009] In some embodiments, the gas is selected from at least one of blast furnace gas, vertical shaft furnace gas, converter gas, and coke oven gas.

[0010] In some embodiments, the gas is discharged from a metallurgical reactor.

[0011] In some embodiments, before using a CO2 adsorbent to capture carbon in the coal gas, the method further includes: subjecting the coal gas to dust removal and / or desulfurization purification treatment. The dust removal treatment is selected from dry dust removal methods, and the desulfurization purification treatment is a medium-temperature desulfurization purification treatment, wherein the purification temperature is 150–200°C. Using dry dust removal and medium-temperature desulfurization purification treatment can effectively avoid the loss of waste heat from the coal gas.

[0012] In some embodiments, before carbon capture of the coal gas using a CO2 adsorbent, the method further includes: heating the coal gas, preferably heating the coal gas to 200-800°C; more preferably, after dust removal and / or desulfurization purification treatment of the coal gas, and before carbon capture of the coal gas using a CO2 adsorbent, the coal gas is heated.

[0013] In some embodiments, before using a CO2 adsorbent to capture carbon from the coal gas, the method further includes: pressure regulation of the coal gas, preferably adjusting the coal gas pressure to 0.1 to 0.3 MPa; more preferably, after dust removal and / or desulfurization purification of the coal gas, and before using a CO2 adsorbent to capture carbon from the coal gas, pressure regulation of the coal gas is performed.

[0014] In some embodiments, the pressure regulating process is as follows: a portion of the gas is pressure regulated and then mixed with another portion of the gas, and the pressure of the mixed gas is controlled to be 0.1 to 0.3 MPa.

[0015] In some embodiments, the method further includes: carbon capture of a portion of the gas, and feeding the remaining gas into a gas pipeline network. The gas entering the gas pipeline network can be used by the entire plant.

[0016] In some embodiments, the method further includes: employing at least two reactors arranged in parallel, each reactor being filled with the adsorption-catalytic bifunctional composite material; and alternately introducing coal gas and hydrogen into each reactor to perform carbon capture and in-situ conversion. Preferably, the number of reactors is determined based on the time required for carbon capture and in-situ conversion, and the carbon capture rate and conversion rate are kept the same. The carbon capture rate is the sum of the maximum theoretical capture times required by all reactors performing carbon capture within the same time period divided by the number of all reactors performing carbon capture, and the conversion rate is the sum of the maximum theoretical conversion times required by all reactors performing in-situ conversion within the same time period divided by the number of all reactors performing in-situ conversion.

[0017] In some embodiments, the temperature of both the CO2 adsorption and CO2 conversion processes is maintained at a certain value between 200 and 800°C, with a fluctuation range of ±20°C.

[0018] In some embodiments, the method further includes: heat exchange between the reactors, utilizing the heat released during the CO2 adsorption process to provide endothermic energy for the CO2 conversion process; preferably, the reactors are all made of highly thermally conductive materials, and the reactors are close together, exchanging heat through the highly thermally conductive materials, wherein the highly thermally conductive materials are selected from at least one of highly thermally conductive metallic materials, graphite materials, and ceramic materials, wherein the highly thermally conductive metallic materials are selected from any one of copper, aluminum, iron and their alloys, and the ceramic materials are selected from at least one of silicon carbide (SiC) ceramics and silicon nitride (Si3N4) ceramics.

[0019] In some embodiments, the method further includes: maintaining the temperature of each reactor at a certain value of 200 to 800°C, with a fluctuation range of ±20°C, by means of external heat dissipation and / or heating supplementation during heat exchange.

[0020] In some embodiments, during the CO2 conversion process, hydrogen gas is introduced as a reducing agent for CO2 conversion, and the temperature of the introduced hydrogen gas is controlled between 200 and 800°C.

[0021] In some embodiments, before the mixed gas is injected into the metallurgical reactor, the mixed gas is heat-exchanged with hydrogen to increase the hydrogen temperature; if the hydrogen temperature does not reach 200–800°C after heat exchange, the hydrogen is further heated to raise its temperature to 200–800°C. Increasing the hydrogen temperature through heat exchange between the mixed gas and hydrogen allows for the recovery and utilization of waste heat from the high-temperature mixed gas, thereby improving energy efficiency.

[0022] In some embodiments, the hydrogen gas introduced is generated by water electrolysis; preferably, after the hydrogen gas is generated by water electrolysis, the hydrogen gas is heated to 200-800°C and then introduced into the reactor.

[0023] In some embodiments, the oxygen produced during the water electrolysis hydrogen production process is introduced into a metallurgical reactor to provide oxygen-enriched conditions, or used in other processes within the steel enterprise.

[0024] In some embodiments, the mixed gas is stored in a gas storage device before it is injected into the metallurgical reactor. This can help maintain the stability of the reducing gas conditions, composition and volume, and avoid affecting the stable operation of the metallurgical reactor.

[0025] In some embodiments, the mixed gas is pressurized and / or heated before being injected into a metallurgical reactor for smelting; preferably, the pressure of the mixed gas after pressurization is 0.6 to 0.8 MPa, and the temperature of the mixed gas after heating is 950 to 1250°C.

[0026] In some embodiments, the metallurgical reactor is selected from at least one of a blast furnace, a gas-based vertical shaft furnace, and a fluidized bed reactor.

[0027] In some embodiments, the adsorption-catalytic bifunctional composite material further includes a support for loading the adsorption component and the catalytic component, wherein the support is selected from at least one of Al2O3, MgO, and aluminum magnesium hydrotalcite [MgAl(OH)3CO3].

[0028] In some embodiments, the adsorbent component is selected from at least one of MgO and CaO.

[0029] In some embodiments, the catalytic component is selected from at least one of Cu, Ni, Co, and Ru.

[0030] In some embodiments, the CO2 capture rate of the adsorption-catalysis bifunctional composite material is ≥90%, and the CO2 conversion rate is ≥80%.

[0031] A second aspect of the present invention provides an ironmaking system coupling carbon capture and in-situ conversion, comprising a carbon capture and conversion reaction device and a metallurgical reactor. The carbon capture and conversion reaction device includes at least two reactors arranged in parallel. Each reactor is filled with an adsorption-catalysis dual-functional composite material. Coal gas and hydrogen are alternately introduced into each reactor to carry out carbon capture and in-situ conversion, forming decarbonized coal gas and CO2 conversion gas. The decarbonized coal gas and CO2 conversion gas are mixed to form a mixed gas, which is injected into the metallurgical reactor.

[0032] In some embodiments, the system further includes a gas dust removal device and / or a gas purification device, wherein the gas dust removal device is used to remove dust from the gas before it is introduced into the reactor, and the gas purification device is used to desulfurize and purify the gas before it is introduced into the reactor.

[0033] In some embodiments, the system further includes a gas heating device for heating the gas before it is introduced into the reactor; preferably, the gas heating device is disposed between the gas dust removal device and the carbon capture and conversion reaction device, or the gas heating device is disposed between the gas purification device and the carbon capture and conversion reaction device.

[0034] In some embodiments, the system further includes a gas pipeline network, wherein the gas is discharged from a metallurgical reactor, and a portion of the gas discharged from the metallurgical reactor enters the carbon capture and conversion reactor, while the other portion is sent to the gas pipeline network.

[0035] In some embodiments, the system further includes a pressure regulating device for regulating the pressure of the gas before it is introduced into the reactor. Preferably, the pressure regulating device includes a gas inlet and a first gas outlet, the gas inlet being connected to the gas outlet of the gas dust removal device, or the gas inlet being connected to the gas outlet of the gas purification device; the first gas outlet is connected to the gas inlet of the gas heating device. More preferably, the pressure regulating device further includes a second gas outlet, the second gas outlet being connected to the gas inlet of the gas pipeline network.

[0036] In some embodiments, the system further includes a heat exchange device for exchanging heat between the mixer and hydrogen to increase the temperature of the hydrogen; preferably, the heat exchange device is disposed between the heat exchange device and the carbon capture and conversion reaction device.

[0037] In some embodiments, the system further includes a hydrogen heating device for heating hydrogen; preferably, the hydrogen heating device is disposed between the heat exchange device and the carbon capture and conversion reaction device.

[0038] In some embodiments, the system further includes a water electrolysis device for producing hydrogen by electrolyzing water; preferably, the water electrolysis device includes a hydrogen outlet connected to the hydrogen inlet of the heat exchange device.

[0039] In some embodiments, the water electrolysis device further includes an oxygen outlet connected to the metallurgical reactor to provide oxygen-enriched conditions by introducing oxygen generated from water electrolysis into the metallurgical reactor.

[0040] In some embodiments, the system further includes a gas delivery device for delivering gas to the reactor and controlling the type of gas delivered to each reactor, the gas including coal gas and hydrogen; preferably, the gas delivery device includes a coal gas inlet, a hydrogen inlet and a plurality of gas outlets, the coal gas inlet being connected to the outlet of the coal gas heating device, and the hydrogen inlet being connected to the outlet of the heat exchange device or the hydrogen heating device.

[0041] In some embodiments, the system further includes a gas holder disposed between the carbon capture and conversion reactor and the metallurgical reactor, for storing the decarbonized gas and CO2 conversion gas. The gas holder serves two purposes: storing the mixed gas and acting as a buffer zone to maintain stable reducing gas conditions, composition, and volume, thus preventing any impact on the stable operation of the metallurgical reactor.

[0042] In some embodiments, the system further includes a jetting device for injecting the mixed gas into the metallurgical reactor; preferably, the jetting device is disposed between the gas holder and the metallurgical reactor.

[0043] In some embodiments, the blowing device includes a pressurizing device and / or a mixed gas heating device, wherein the pressurizing device is used to pressurize the mixed gas and the mixed gas heating device is used to heat the mixed gas.

[0044] A third aspect of the present invention provides the application of the method according to the first aspect and / or the system according to the second aspect in the field of ironmaking.

[0045] As described above, the ironmaking method, system, and application of the present invention, which couples carbon capture and in-situ conversion, have the following beneficial effects:

[0046] 1. This invention effectively solves the problem of large-scale CO2 consumption by coupling the CO2 capture and conversion system with the ironmaking system, realizes carbon cycling and hydrocarbon coupling reduction in the ironmaking system, and effectively reduces carbon emissions from the ironmaking system.

[0047] 2. This invention combines the utilization of waste heat from coal gas with carbon capture. By capturing carbon under medium-high temperature (200-800℃) conditions, the waste heat from coal gas is effectively utilized, while avoiding the energy loss caused by the conventional alkanolamine solution decarbonization process which requires cooling absorption followed by heating desorption.

[0048] 3. By using a dual-functional composite material for adsorption and catalysis, this invention can integrate the CO2 capture and conversion process into the same reactor, greatly simplifying the carbon capture and utilization process. By setting up multiple reactors in parallel and exchanging heat with each other, the exothermic process of capture and the endothermic process of conversion can be matched, thereby improving energy utilization efficiency. Attached Figure Description

[0049] Figure 1 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in one embodiment of the present invention.

[0050] Figure 2 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0051] Figure 3 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0052] Figure 4 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0053] Figure 5 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0054] Figure 6 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0055] Figure 7 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0056] Figure 8 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0057] Figure 9 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0058] Figure 10 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0059] Figure 11 The diagram shows the layout of an ironmaking system that couples carbon capture and in-situ conversion in another embodiment of the present invention.

[0060] Figure 12 The diagram shows the layout of the ironmaking system that couples carbon capture and in-situ conversion in Embodiment 1 of the present invention.

[0061] Figure 13 The diagram shows the layout of the ironmaking system that couples carbon capture and in-situ conversion in Embodiment 2 of the present invention.

[0062] Figure 14 The diagram shows the layout of the ironmaking system that couples carbon capture and in-situ conversion in Embodiment 3 of the present invention.

[0063] Explanation of reference numerals in the attached drawings: 1. Gas dust removal device; 2. Gas purification device; 3. Pressure regulating device; 4. Gas pipeline network; 5. Gas heating device; 6. Gas conveying device; 7. Hydrogen heating device; 8. Carbon capture and conversion reaction device; 9. Heat exchange device; 10. Water electrolysis device; 11. Gas holder; 12. Pulse injection device; 13. Metallurgical reactor. Detailed Implementation

[0064] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the figures provided in the following embodiments are only schematic illustrations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0065] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0066] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0067] One embodiment of the present invention provides an ironmaking method coupling carbon capture and in-situ conversion. The method employs a bifunctional adsorption-catalytic composite material for carbon capture and in-situ conversion. The bifunctional adsorption-catalytic composite material includes an adsorbent component and a catalytic component. The adsorbent component is a regenerable CO2 adsorbent, and the catalytic component is a catalyst capable of catalyzing an in-situ hydrogenation conversion reaction. The method includes the following steps:

[0068] CO2 adsorption: Carbon capture of coal gas is achieved through CO2 adsorbent to obtain decarbonized coal gas;

[0069] CO2 conversion: The CO2 adsorbent that has adsorbed CO2 is regenerated to release CO2. At the same time, under the action of a catalyst, the released CO2 is hydrogenated in situ to obtain CO2 conversion gas, which contains CO and / or methane.

[0070] Decarbonized coal gas is mixed with CO2 conversion gas to form a mixed gas, which is then injected into a metallurgical reactor for smelting.

[0071] In one specific embodiment, the coal gas is discharged from the metallurgical reactor, which includes, but is not limited to, blast furnaces, gas-based vertical shaft furnaces, fluidized bed reactors, etc., and the coal gas includes, but is not limited to, blast furnace gas, vertical shaft furnace gas, converter gas, coke oven gas, etc.

[0072] The in-situ hydrogenation conversion reactions in this embodiment of the invention are carbon dioxide methanation and / or reverse water-gas shift reaction. Carbon dioxide methanation refers to the reaction in which hydrogen reduces carbon dioxide to methane and water in the presence of a catalyst; its chemical equation is: CO2 + 4H2 → CH4 + 2H2O. The reverse water-gas shift reaction is used to convert CO2 to CO; its chemical equation is: CO2 + H2 → CO + H2O. Generally, this reaction requires high temperature and a catalyst. The products obtained from the above two CO2 conversion reaction types are different; one or a combination of both can be used, depending on the type of metallurgical reactor and its smelting requirements.

[0073] In one specific embodiment, the adsorption-catalytic bifunctional composite material further includes a support for loading the adsorption component and the catalytic component, the support including but not limited to Al2O3, MgO, aluminum magnesium hydrotalcite [MgAl(OH)3CO3], etc.

[0074] In one specific embodiment, the adsorbent component includes, but is not limited to, MgO, CaO, etc., and the catalytic component includes, but is not limited to, Cu, Ni, Co, Ru, etc.

[0075] In one specific embodiment, the CO2 capture rate of the adsorption-catalysis bifunctional composite material is ≥90%, and the CO2 conversion rate is ≥80%.

[0076] In one specific embodiment, the temperature of both the CO2 adsorption and CO2 conversion processes is maintained at a certain value between 200 and 800°C, with a fluctuation range of ±20°C.

[0077] In the above embodiments, the coal gas first undergoes CO2 adsorption. After the CO2 adsorbent has adsorbed a certain amount of CO2, preferably to the point of adsorption saturation, the CO2 adsorbent is regenerated. CO2 conversion occurs simultaneously during the CO2 desorption process. The decarbonized coal gas and the CO2-converted gas are mixed and injected into a metallurgical reactor for smelting. This invention combines the utilization of coal gas waste heat with carbon capture. By capturing carbon under medium- and high-temperature conditions, the waste heat of the coal gas is effectively utilized. By using a dual-functional composite material for adsorption and catalysis, the CO2 capture and conversion processes can be integrated into the same reactor, greatly simplifying the carbon capture and utilization process. By coupling CO2 capture and conversion utilization with the ironmaking system, the problem of large-scale CO2 consumption is effectively solved, realizing carbon recycling and hydrocarbon coupling reduction in the ironmaking system, and effectively reducing carbon emissions from the ironmaking system.

[0078] In another embodiment of the present invention, before using a CO2 adsorbent to capture carbon in the coal gas, the method further includes: subjecting the coal gas to dust removal and / or desulfurization purification treatment. Dust removal treatment refers to removing dust from the blast furnace gas, and desulfurization purification treatment refers to removing organic and inorganic sulfur from the blast furnace gas. Preferably, the dust content of the coal gas after dust removal treatment is ≤1 mg / m³. 3 When the total sulfur content in the coal gas is >10 mg / m³ 3 At that time, the coal gas is desulfurized and purified, and the total sulfur content in the coal gas after desulfurization is ≤10mg / m³. 3 Furthermore, the gas dust removal method is selected from dry dust removal to avoid the loss of gas waste heat. Specific dust removal methods include, but are not limited to, cyclone dust removal, electrostatic dust removal, ceramic high-temperature dust removal, and media filtration dust removal. The desulfurization and purification treatment is medium-temperature desulfurization and purification treatment. During medium-temperature desulfurization and purification treatment, the purification temperature is 150-200℃ to avoid the loss of gas waste heat.

[0079] In another embodiment of the present invention, if the gas temperature has not reached the preset temperature for carbon capture and conversion, before using a CO2 adsorbent to capture carbon in the gas, the method further includes: heating the gas, preferably to 200-800°C; more preferably, after dust removal and / or desulfurization purification treatment of the gas, and before using a CO2 adsorbent to capture carbon in the gas, the gas is heated to raise its temperature to the temperature required for carbon capture and conversion. Since the reaction temperatures required for the above-mentioned carbon dioxide methanation reaction and the reverse water-gas shift reaction are different, the specific reaction temperature is determined according to the type of CO2 conversion reaction.

[0080] In another embodiment of the present invention, before using a CO2 adsorbent to capture carbon in the coal gas, the method further includes: pressure regulation of the coal gas, preferably adjusting the coal gas pressure to 0.1 to 0.3 MPa; more preferably, after dust removal and / or desulfurization purification treatment of the coal gas, and before using a CO2 adsorbent to capture carbon in the coal gas, pressure regulation of the coal gas is performed.

[0081] In one specific embodiment, the pressure regulating process is as follows: a portion of the gas is pressure regulated and then mixed with another portion of the gas, and the pressure of the mixed gas is controlled to be 0.1 to 0.3 MPa.

[0082] In another embodiment of the present invention, the method further includes: carbon capture of a portion of the gas, and feeding the remaining gas into a gas pipeline network. The gas entering the gas pipeline network can be used by the entire plant.

[0083] In another embodiment of the present invention, the method further includes: employing at least two reactors arranged in parallel, each reactor being filled with an adsorption-catalytic bifunctional composite material; and alternately introducing coal gas and hydrogen into each reactor to perform carbon capture and in-situ conversion. Preferably, the number of reactors is determined based on the time required for carbon capture and in-situ conversion, and the carbon capture rate and conversion rate are kept the same. The carbon capture rate is the sum of the maximum theoretical capture times required by all reactors performing carbon capture within the same time period divided by the number of all reactors performing carbon capture, and the conversion rate is the sum of the maximum theoretical conversion times required by all reactors performing in-situ conversion within the same time period divided by the number of all reactors performing in-situ conversion. For example, assuming each reactor is filled with an adsorption-catalytic bifunctional composite material of the same composition and loading amount, the maximum theoretical capture time for carbon capture and the maximum theoretical conversion time for in-situ conversion are the same for each reactor. In this case, when the maximum theoretical capture time equals the maximum theoretical conversion time, the number of reactors is a multiple of 2, with half of the reactors alternating with the other half for carbon capture and in-situ conversion. When the maximum theoretical capture time is twice the maximum theoretical conversion time, the number of reactors is a multiple of 3, with two-thirds of the reactors alternating with the other one-third for carbon capture and in-situ conversion. The maximum theoretical capture time is the time required for the adsorption-catalytic bifunctional composite material in a reactor to reach saturation with adsorbed CO2, and the maximum theoretical conversion time is the time required for the adsorption-catalytic bifunctional composite material in a reactor to completely release and convert the adsorbed CO2.

[0084] In one specific embodiment, the loading method of the adsorption-catalysis bifunctional composite material in the reactor can be selected as dual-bed mode, multi-bed mode, physical mixing mode, and integrated mode.

[0085] In another embodiment of the present invention, the method further includes: heat exchange between the reactors, utilizing the heat released during the CO2 adsorption process to provide endothermic energy for the CO2 conversion process; preferably, the reactors are all made of highly thermally conductive materials, and the reactors are placed close together (see reference). Figures 1 to 14 The reactor uses high thermal conductivity materials for heat exchange. These materials include, but are not limited to, high thermal conductivity metals, graphite, and ceramics. High thermal conductivity metals include, but are not limited to, copper, aluminum, iron, and their alloys. Ceramic materials include, but are not limited to, silicon carbide (SiC) ceramics and silicon nitride (Si3N4) ceramics. More preferably, the sidewalls of the reactor are all made of high thermal conductivity materials, so that when the reactors are placed together, they can exchange heat with each other through the sidewalls made of high thermal conductivity materials.

[0086] In the above embodiments, matching the exothermic capture process with the endothermic conversion process can effectively improve energy utilization efficiency.

[0087] In another embodiment of the present invention, the method further includes: while exchanging heat, maintaining the temperature of each reactor at a certain value of 200 to 800°C by external heat dissipation and / or heating supplementation, with a fluctuation range of ±20°C.

[0088] In another embodiment of the present invention, during the CO2 conversion process, hydrogen gas is introduced as a reducing agent for CO2 conversion, and the temperature of the introduced hydrogen gas is controlled at 200-800°C.

[0089] In another embodiment of the present invention, before the mixed gas is injected into the metallurgical reactor, the mixed gas is heat-exchanged with hydrogen to increase the hydrogen temperature; if the hydrogen temperature does not reach 200-800°C after heat exchange, the hydrogen is further heated to increase its temperature to 200-800°C. By increasing the hydrogen temperature through heat exchange between the mixed gas and hydrogen, the waste heat of the high-temperature mixed gas can be recovered and utilized, thereby improving energy utilization efficiency.

[0090] In one specific embodiment, the hydrogen gas introduced is generated by water electrolysis; preferably, after the hydrogen gas is generated by water electrolysis, it is heated to 200–800°C before being introduced into the reactor. Additionally, the oxygen generated during the water electrolysis hydrogen production process can be introduced into a metallurgical reactor to provide oxygen-enriched conditions, or used in other process steps within steel enterprises.

[0091] In another embodiment of the present invention, the mixed gas is stored in a gas storage device before it is injected into the metallurgical reactor. This can maintain the stability of the reducing gas conditions, composition and volume, and avoid affecting the stable operation of the metallurgical reactor.

[0092] In another embodiment of the present invention, the mixed gas is pressurized and / or heated before being injected into a metallurgical reactor for smelting; preferably, the pressure of the mixed gas after pressurization is 0.6 to 0.8 MPa, and the temperature of the mixed gas after heating is 950 to 1250°C.

[0093] Combination Figure 1 As shown, one embodiment of the present invention provides an ironmaking system that couples carbon capture and in-situ conversion, including a carbon capture and conversion reaction device 8 and a metallurgical reactor 13. The carbon capture and conversion reaction device 8 includes at least two reactors arranged in parallel. Each reactor is filled with a dual-function composite material for adsorption and catalysis. Coal gas and hydrogen are alternately introduced into each reactor to carry out carbon capture and in-situ conversion, forming decarbonized coal gas and CO2 conversion gas. The decarbonized coal gas and CO2 conversion gas are mixed to form a mixed gas, which is injected into the metallurgical reactor 13.

[0094] Combination Figure 2As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a gas dust removal device 1 and / or a gas purification device 2. The gas dust removal device 1 is used to remove dust from the gas before it is introduced into the reactor, and the gas purification device 2 is used to desulfurize and purify the gas before it is introduced into the reactor.

[0095] Combination Figure 3 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a gas heating device 5, which is used to heat the gas before it is introduced into the reactor; preferably, the gas heating device 5 is disposed between the gas dust removal device 1 and the carbon capture and conversion reaction device 8, or the gas heating device 5 is disposed between the gas purification device 2 and the carbon capture and conversion reaction device 8.

[0096] Combination Figure 4 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a gas pipeline network 4, with the gas discharged from the metallurgical reactor 13. Part of the gas discharged from the metallurgical reactor 13 enters the carbon capture and conversion reaction device 8, and the other part is sent to the gas pipeline network 4.

[0097] Combination Figure 5 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a pressure regulating device 3, which is used to regulate the pressure of the gas before it is introduced into the reactor. Preferably, the pressure regulating device 3 includes a gas inlet and a first gas outlet. The gas inlet is connected to the gas outlet of the gas dust removal device 1, or the gas inlet is connected to the gas outlet of the gas purification device 2; the first gas outlet is connected to the gas inlet of the gas heating device 5. More preferably, the pressure regulating device 3 further includes a second gas outlet, which is connected to the gas inlet of the gas pipeline network 4.

[0098] Combination Figure 6 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a heat exchange device 9, which is a place where the mixer exchanges heat with hydrogen to increase the temperature of the hydrogen; preferably, the heat exchange device 9 is disposed between the heat exchange device 9 and the carbon capture and conversion reaction device 8.

[0099] Combination Figure 7 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a hydrogen heating device 7, which is used to heat hydrogen; preferably, the hydrogen heating device 7 is disposed between the heat exchange device 9 and the carbon capture and conversion reaction device 8.

[0100] Combination Figure 8As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a water electrolysis device 10, which is used to produce hydrogen by electrolyzing water; preferably, the water electrolysis device 10 includes a hydrogen outlet, which is connected to the hydrogen inlet end of the heat exchange device 9.

[0101] Combination Figure 8 As shown, in another embodiment of the present invention, based on the above embodiment, the water electrolysis device 10 further includes an oxygen outlet, which is connected to the metallurgical reactor 13 to introduce the oxygen generated by water electrolysis into the metallurgical reactor 13 to provide oxygen-rich conditions.

[0102] Combination Figure 9 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a gas conveying device 6, which is used to convey gas to the reactor and control the type of gas conveyed to each reactor. The gas includes coal gas and hydrogen. Preferably, the gas conveying device 6 includes a coal gas inlet, a hydrogen inlet and a plurality of gas outlets. The coal gas inlet is connected to the gas outlet of the coal gas heating device 5, and the hydrogen inlet is connected to the gas outlet of the heat exchange device 9 or the hydrogen heating device 7.

[0103] Combination Figure 10 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a gas holder 11. The gas holder 11 is disposed between the carbon capture and conversion reaction device 8 and the metallurgical reactor 13, and is used to store decarbonized gas and CO2 conversion gas. The gas holder 11 can store the mixed gas on the one hand, and on the other hand, it can serve as a buffer zone to maintain the stability of the reducing gas conditions, composition and volume, and avoid affecting the stable operation of the metallurgical reactor 13.

[0104] Combination Figure 11 As shown, in another embodiment of the present invention, based on the above embodiment, the system further includes a jetting device 12, which is used to jet the mixed gas into the metallurgical reactor 13; preferably, the jetting device 12 is disposed between the gas holder 11 and the metallurgical reactor 13.

[0105] In one specific embodiment, the blowing device 12 includes a pressurizing device and / or a mixed gas heating device, wherein the pressurizing device is used to pressurize the mixed gas and the mixed gas heating device is used to heat the mixed gas.

[0106] The present invention will be further described below with specific embodiments. It should also be understood that the following embodiments are only for specific illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the present invention are within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the appropriate range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0107] Example 1

[0108] Ironmaking methods and systems based on blast furnace gas self-circulation and intermediate-temperature methanation reaction

[0109] This embodiment uses a 1400m... 3 The blast furnace will be used as an example for explanation. Tables 1 and 2 show the raw material conditions and main technical indicators of the blast furnace, respectively.

[0110] Table 1 Grade of ore fed into the blast furnace

[0111] FeO <![CDATA[Fe2O3]]> TFe other 7.14％ 74.35％ 57.60％ 18.51％

[0112] Table 2 Main Technical Indicators of Blast Furnace

[0113] Focal ratio Coal ratio fuel ratio wind temperature Blower oxygen enrichment rate 342kg / thm 165kg / thm 507kg / thm 1200℃ 5％

[0114] like Figure 12 As shown, this embodiment employs an ironmaking system that couples carbon capture and in-situ conversion. Based on a conventional blast furnace system, a new carbon capture and in-situ conversion system is added, including: a gas dust removal device 1, a pressure regulating device 3, a gas heating device 5, a gas conveying device 6, a hydrogen heating device 7, a carbon capture and conversion reaction device 8, a heat exchange device 9, a water electrolysis device 10, a gas holder 11, a blowing device 12, and a metallurgical reactor 13. The metallurgical reactor 13 is a blast furnace, and the gas is blast furnace gas. Due to the high sulfur content in the blast furnace gas, a gas purification device 2 is added. The ironmaking method of coupling carbon capture and in-situ conversion will now be specifically described in conjunction with the raw material conditions and main technical indicators of the conventional blast furnace in Tables 1 and 2 and the above system.

[0115] After the blast furnace gas is discharged from the blast furnace, the dust content is ≤1mg / m³ after being removed by the gas dust removal device 1. 3 The gas then enters the gas purification unit 2 for desulfurization and purification at a temperature of 150–200℃. After purification, the total sulfur content of the gas is ≤10 mg / m³. 3 The composition of the blast furnace gas after passing through the gas dust removal device 1 and the gas purification device 2 is shown in Table 3.

[0116] Table 3 Composition of purified blast furnace gas

[0117] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[N2]]> 25.7％ 25.2％ 3.2％ 45.9％

[0118] The purified blast furnace gas has a temperature of approximately 150℃. Part of it enters directly into the gas heating device 5, while the other part enters the pressure regulating device 3 for pressure regulation. The pressure-regulated blast furnace gas mixes with the blast furnace gas that directly enters the gas heating device 5. After mixing, the blast furnace gas pressure is maintained at 0.2 MPa, and the gas flow rate is 18,000 Nm³. 3 / h. The gas heating device 5 heats the blast furnace gas to 240℃. The heated blast furnace gas is then fed into the reactor of the carbon capture and conversion reaction device 8. The adsorption components in the reactor adsorb CO2 from the blast furnace gas, achieving a decarbonization efficiency of 96%. After adsorption saturation, the gas conveying device 6 switches the gas path, delivering 26,100 Nm³ of gas. 3 H2 heated to 240℃ by hydrogen heating device 7 is introduced into the adsorption-saturated reactor, where CO2 is converted into methane via a methanation reaction with a conversion rate of 95% and a selectivity of 99%. The carbon capture and conversion reactor 8 consists of two reactors connected in parallel, alternating between adsorption and conversion processes to ensure continuous gas processing. The reactor temperature is maintained at 240±20℃, and the pressure at 0.2MPa. The decarbonized coal gas produced by the two reactors is mixed with the CO2 conversion gas and then enters the heat exchanger 9 for waste heat recovery, reducing the temperature to 70℃ before entering the gas holder 11. The composition of the decarbonized coal gas, CO2 conversion gas, and mixed gas is shown in Table 4.

[0119] Table 4 Composition of Decarbonized Coal Gas, CO2 Converted Gas, and Mixed Gas

[0120] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[N2]]> <![CDATA[CH4]]> <![CDATA[Decarbonized coal gas (13599 Nm 3 / h)]]> 33.7％ 1.3％ 4.2％ 60.8％ -- <![CDATA[CO2 conversion gas (13981 Nm 3 / h)]]> 0.6％ 1.6％ 68.5％ -- 29.3％ <![CDATA[Mixed gas (27580 Nm 3 / h)]]> 16.9％ 1.4％ 36.8％ 30.0％ 14.9％

[0121] The mixed gas in gas holder 11 is pressurized and heated by injection device 12, with the pressure rising to 0.7 MPa and the temperature to 950℃, before being injected into the blast furnace. The electrolysis water device 10 produces 13064 Nm³ of gas. 3 O2 is introduced into the blast furnace at a rate of / h to provide oxygen-rich conditions for smelting. The injected mixed gas replaces part of the coke and coal in the blast furnace, reducing the blast furnace fuel ratio and thus effectively reducing carbon emissions from the blast furnace ironmaking system.

[0122] For the 1400m in this embodiment 3 The blast furnace has a mixed gas injection rate of 189 Nm³ per ton of iron. 3 / t, after the injection of mixed gas, the blast furnace coke ratio is 316 kg / t iron, the coal ratio is 126 kg / t iron, and the fuel ratio is 442 kg / t iron.

[0123] Therefore, by adopting an ironmaking system that couples carbon capture and in-situ conversion, the solid fuel ratio can be reduced by 65 kg / t of iron, the direct carbon reduction ratio is 12.8%, and carbon emissions per ton of iron can be reduced by about 181 kg.

[0124] Example 2

[0125] Ironmaking methods and systems based on converter gas circulation and high-temperature reverse water-gas shift reaction

[0126] This embodiment uses a 1400m... 3 Taking a blast furnace as an example, the raw material conditions and main technical indicators of the blast furnace are the same as in Example 1. Figure 13 As shown, this embodiment employs an ironmaking system that couples carbon capture and in-situ conversion. Based on a conventional blast furnace system, a new carbon capture and in-situ conversion system is added, including: a gas dust removal device 1, a pressure regulating device 3, a gas heating device 5, a gas conveying device 6, a hydrogen heating device 7, a carbon capture and conversion reaction device 8, a heat exchange device 9, a water electrolysis device 10, a gas holder 11, a blowing device 12, and a metallurgical reactor 13. The metallurgical reactor 13 is a blast furnace, and the gas is converter gas. The ironmaking method of coupling carbon capture and in-situ conversion will now be specifically described in conjunction with the raw material conditions and main technical indicators of a conventional blast furnace as shown in Tables 1 and 2, and the above system.

[0127] The gas dust removal treatment method is the same as in Example 1. The composition of converter gas after dust removal is shown in Table 5.

[0128] Table 5 Composition of converter gas after dust removal

[0129] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[N2]]> 45.5％ 18.8％ 1.5％ 34.2％

[0130] After dust removal, the converter gas temperature is approximately 400℃. Part of it directly enters the gas heating device 5, while the other part enters the pressure regulating device 3 for pressure regulation. The pressure-regulated converter gas mixes with the converter gas that directly enters the gas heating device 5. After mixing, the converter gas pressure is maintained at 0.1 MPa, and the gas flow rate is 18,000 Nm³. 3 / h. Gas heating device 5 heats the converter gas to 800℃. The heated converter gas is then fed into a reactor in carbon capture and conversion reaction device 8. The adsorption components in the reactor adsorb CO2, achieving a decarbonization efficiency of 97%. After adsorption saturation, 16,400 Nm³... 3 H2 heated to 800℃ by hydrogen heating device 7 is introduced into the adsorption-saturated reactor, where CO2 is converted to CO via a reverse water-gas shift reaction, achieving a conversion rate of 80% and a selectivity of 95%. The carbon capture and conversion reactor 8 consists of two reactors connected in parallel, alternating between adsorption and conversion processes to ensure continuous gas processing. The reactor temperature is maintained at 800±20℃, and the pressure at 0.1MPa. The decarbonized gas and CO2-converted gas produced by the two reactors are mixed and cooled to 70℃ by heat exchange device 9 before entering the gas holder 11. The composition of the decarbonized gas, CO2-converted gas, and mixed gas is shown in Table 6.

[0131] Table 6 Composition of Decarbonized Coal Gas, CO2 Converted Gas, and Mixed Gas

[0132] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[N2]]> <![CDATA[CH4]]> <![CDATA[Decarbonized coal gas (14636 Nm 3 / h)]]> 55.4％ 0.7％ 1.8％ 42.1％ -- <![CDATA[CO2 conversion gas (16757 Nm 3 / h)]]> 15.4％ 3.9％ 79.9％ -- 0.8％ <![CDATA[Mixed gas (31393 Nm 3 / h)]]> 34.0％ 2.4％ 43.5％ 19.7％ 0.4％

[0133] The heating and pressurization process for the mixed gas in gas holder 11 is the same as in Example 1. The 8206 Nm³ produced by the water electrolysis device 10... 3 / h of O2 is introduced into the blast furnace to provide oxygen-rich conditions for smelting.

[0134] For the 1400m in this embodiment 3 The blast furnace has a mixed gas injection rate of 215 Nm³ per ton of iron. 3 / t, after the injection of mixed gas, the blast furnace coke ratio is 322 kg / t iron, the coal ratio is 135 kg / t iron, and the fuel ratio is 457 kg / t iron.

[0135] Therefore, by adopting a blast furnace ironmaking system that couples medium- and high-temperature carbon capture and in-situ conversion, the solid fuel ratio can be reduced by 50 kg / t of iron, the direct carbon reduction ratio is 9.9%, and carbon emissions per ton of iron can be reduced by about 140 kg.

[0136] Example 3

[0137] Ironmaking methods and systems based on vertical shaft furnace top gas self-circulation and high-temperature reverse water-gas shift reaction

[0138] This embodiment uses a gas-based vertical shaft furnace with an annual production capacity of 500,000 tons of direct reduced iron as an example for illustration. Figure 14 As shown, this embodiment employs an ironmaking system that couples carbon capture and in-situ conversion, comprising: a gas dust removal device 1, a pressure regulating device 3, a gas heating device 5, a gas conveying device 6, a hydrogen heating device 7, a carbon capture and conversion reaction device 8, a heat exchange device 9, a water electrolysis device 10, a gas holder 11, a blowing device 12, and a metallurgical reactor 13. The metallurgical reactor 13 is a vertical shaft furnace, and the gas is top gas from the vertical shaft furnace. The ironmaking method that couples carbon capture and in-situ conversion will now be described in detail with reference to the above system.

[0139] The gas dust removal treatment method is the same as in Example 1. The composition of the gas at the top of the vertical furnace after dust removal is shown in Table 7.

[0140] Table 7 Composition of the top gas of the vertical furnace after dust removal

[0141] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[CH4]]> <![CDATA[N2]]> 36.9％ 31.1％ 14.3％ 1.3％ 16.4％

[0142] After dust removal, the temperature of the gas at the top of the vertical shaft furnace is approximately 280℃. Part of it directly enters the gas heating device 5, while the other part enters the pressure regulating device 3 for pressure regulation. The pressure-regulated converter gas mixes with the converter gas that directly enters the gas heating device 5. After mixing, the pressure of the gas at the top of the vertical shaft furnace is maintained at 0.2 MPa, and the gas flow rate is 18,000 Nm³. 3 / h. The gas heating device 5 heats the top gas of the vertical furnace to 800℃. The heated top gas is then fed into a reactor of the carbon capture and conversion reaction device 8. The adsorption components in the reactor adsorb CO2, achieving a decarbonization efficiency of 97%. After adsorption saturation, 27,200 Nm³ / h... 3 H2 heated to 800℃ by hydrogen heating device 7 is introduced into the adsorption-saturated reactor, where CO2 is converted to CO via a reverse water-gas shift reaction, achieving a conversion rate of 82% and a selectivity of 95%. The carbon capture and conversion reactor 8 consists of two reactors connected in parallel, alternating between adsorption and conversion processes to ensure continuous gas processing. The reactor temperature is maintained at 800±20℃, and the pressure at 0.2MPa. The decarbonized gas and CO2-converted gas produced by the two reactors are mixed and cooled to 70℃ by heat exchange device 9 before entering the gas holder 11. The composition of the decarbonized gas, CO2-converted gas, and mixed gas is shown in Table 8.

[0143] Table 8 Composition of Decarbonized Coal Gas, CO2 Converted Gas, and Mixed Gas

[0144] CO <![CDATA[CO2]]> <![CDATA[H2]]> <![CDATA[N2]]> <![CDATA[CH4]]> <![CDATA[Decarbonized coal gas (12504 Nm 3 / h)]]> 52.6％ 1.3％ 20.6％ 23.6％ 1.9％ <![CDATA[CO2 conversion gas (27526 Nm 3 / h)]]> 15.6％ 3.6％ 80.0％ -- 0.8％ <![CDATA[Mixed gas (40030 Nm 3 / h)]]> 27.2％ 2.9％ 61.5％ 7.4％ 1.1％

[0145] The heating and pressurization of the mixed gas in gas holder 11 is the same as in Example 1, and it is then injected into the vertical furnace as partial reducing gas, wherein H2 / CO = 2.3. The electrolytic water device 10 produces 13575 Nm³ of gas. 3 / h of O2 is used in processes such as electric arc furnace steelmaking and steel processing.

[0146] This embodiment achieves the recycling of reducing carbon resources CO and CH4 and non-reducing carbon resources CO2 in the top gas of the vertical furnace by adopting an ironmaking system that couples carbon capture and in-situ conversion, thereby reducing the carbon emissions of the ironmaking system.

[0147] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for ironmaking that couples carbon capture and in-situ conversion, characterized in that, The method employs a dual-functional composite material for adsorption and catalysis to capture and convert carbon in situ. The adsorption-catalytic bifunctional composite material includes an adsorption component, a catalytic component, and a support for loading the adsorption component and the catalytic component; the adsorption component is a regenerable CO2 adsorbent selected from at least one of MgO and CaO; the catalytic component is a catalyst capable of catalyzing in-situ hydrogenation conversion reactions selected from at least one of Cu, Ni, Co, and Ru; and the support is selected from aluminum-magnesium hydrotalcite. The method includes the following steps: CO2 adsorption: Carbon capture of coal gas is achieved through CO2 adsorbent to obtain decarbonized coal gas; CO2 conversion: The CO2 adsorbent that has adsorbed CO2 is regenerated to release CO2. At the same time, under the action of the catalyst, the released CO2 is hydrogenated in situ to obtain CO2 conversion gas, which contains CO and / or methane. The temperature of both the CO2 adsorption and CO2 conversion processes is maintained at a certain value between 200 and 800℃, with a fluctuation range of ±20℃. The decarbonized coal gas is mixed with CO2 conversion gas to form a mixed gas, which is then injected into a metallurgical reactor for smelting. The method further includes: employing at least two reactors connected in parallel, each reactor being filled with the adsorption-catalytic bifunctional composite material; alternately introducing coal gas and hydrogen into each reactor to perform carbon capture and in-situ conversion; heat exchange between the reactors, utilizing the heat released during the CO2 adsorption process to provide endothermic energy for the CO2 conversion process; the reactors are all made of highly thermally conductive materials, and the reactors are placed close together, exchanging heat through the highly thermally conductive materials; Before using CO2 adsorbent to capture carbon in coal gas, the coal gas is subjected to dust removal and desulfurization purification treatment. The coal gas dust removal treatment method is selected from dry dust removal, and the desulfurization purification treatment is medium-temperature desulfurization purification treatment. During the medium-temperature desulfurization purification treatment, the purification temperature is 150~200℃.

2. The method according to claim 1, characterized in that, The method further includes at least one of the following operations (I) to (V): (I) The gas is heated before using a CO2 adsorbent to capture carbon in the gas; (II) Before using CO2 adsorbent to capture carbon in coal gas, the coal gas is pressure regulated; (III) A portion of the gas is carbon captured, and the remaining gas is sent into the gas pipeline network; (IV) Before the mixed gas is injected into the metallurgical reactor, the mixed gas is stored in a gas storage device; (V) The mixed gas is pressurized and / or heated before being injected into the metallurgical reactor for smelting.

3. The method according to claim 1, characterized in that: In the CO2 conversion process, hydrogen gas is introduced as a reducing agent for CO2 conversion.

4. The method according to claim 3, characterized in that: Before the mixed gas is injected into the metallurgical reactor, the mixed gas is heat-exchanged with hydrogen to increase the temperature of the hydrogen.

5. An ironmaking system coupling carbon capture and in-situ conversion, characterized in that: The system includes a carbon capture and conversion reactor and a metallurgical reactor. The carbon capture and conversion reactor comprises at least two reactors connected in parallel. Each reactor is filled with a dual-functional composite material for adsorption and catalysis. Coal gas and hydrogen are alternately introduced into each reactor to perform carbon capture and in-situ conversion, forming decarbonized coal gas and CO2 conversion gas. Heat exchange occurs between the reactors, utilizing the heat released during CO2 adsorption to provide endothermic energy for the CO2 conversion process. The reactors are all made of highly thermally conductive materials and are located close together, exchanging heat through these materials. The decarbonized coal gas and CO2 conversion gas are mixed to form a mixed gas, which is then injected into the metallurgical reactor. The adsorption-catalytic bifunctional composite material includes an adsorption component, a catalytic component, and a support for loading the adsorption component and the catalytic component; the adsorption component is a regenerable CO2 adsorbent selected from at least one of MgO and CaO; the catalytic component is a catalyst capable of catalyzing in-situ hydrogenation conversion reactions selected from at least one of Cu, Ni, Co, and Ru; and the support is selected from aluminum-magnesium hydrotalcite. The system also includes a gas dust removal device and a gas purification device; the gas dust removal device is used to perform dry dust removal treatment on the gas before it is introduced into the reactor; the gas purification device is used to perform medium-temperature desulfurization purification treatment on the gas before it is introduced into the reactor, wherein the purification temperature during the medium-temperature desulfurization purification treatment is 150~200℃.

6. The system according to claim 5, characterized in that, The system also includes at least one of the following devices: a gas heating device, a gas pipeline network, a pressure regulating device, a heat exchange device, a hydrogen heating device, an electrolysis water device, a gas conveying device, a gas holder, and a jetting device; The gas heating device is used to heat the gas before it is introduced into the reactor; The coal gas is discharged from the metallurgical reactor. Part of the coal gas discharged from the metallurgical reactor enters the carbon capture and conversion reaction device, and the other part is sent to the coal gas pipeline network. The pressure regulating device is used to regulate the pressure of the gas before it is introduced into the reactor. The heat exchange device is a place where the mixed gas and hydrogen exchange heat to increase the temperature of the hydrogen. The hydrogen heating device is used to heat hydrogen. The water electrolysis device is used to produce hydrogen by electrolyzing water. The gas delivery device is used to deliver gas to the reactor and to control the type of gas delivered to each reactor, the gas including coal gas and hydrogen. The gas holder is located between the carbon capture and conversion reaction device and the metallurgical reactor, and is used to store the decarbonized gas and CO2 conversion gas. The injection device is used to inject the mixed gas into the metallurgical reactor.

7. The application of the method according to any one of claims 1 to 4 and / or the system according to any one of claims 5 to 6 in the field of ironmaking.

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