Carbon dioxide capture and utilization method and apparatus thereof, and method for treating high-temperature flue gas of heating furnace

Abstract

A carbon dioxide capture and utilization method, which comprises: 1) introducing a carbon-dioxide-containing gas into a reactor filled with a catalytic material and a heat storage material, adsorbing carbon dioxide in the carbon-dioxide-containing gas by using the catalytic material, and discharging the resulting carbon-dioxide-depleted purified gas from the reactor; 2) changing the carbon-dioxide-containing gas into a preheated mixed recycle gas (8) containing a reducing gas (2) and a recycle gas (7-2), so as to react the mixed recycle gas (8) with the catalytic material in the reactor that has adsorbed the carbon dioxide; 3) performing heat exchange between the converted gas discharged from the reactor and the mixed recycle gas (8) so as to preheat the mixed recycle gas (8), and dividing the heat-exchanged converted gas into two streams, wherein one stream serves as a product gas (7-1) to be discharged from the system, and the other stream serves as the recycle gas (7-2) to be mixed with the reducing gas (2); and 4) changing the preheated mixed recycle gas (8) containing the reducing gas (2) and the recycle gas (7-2) into the carbon-dioxide-containing gas. Further provided are a carbon dioxide capture and utilization apparatus, and a method for treating high-temperature flue gas of a heating furnace. The method can sufficiently improve the energy utilization rate and effectively reduce the emission reduction cost, and achieve the in-situ coupling utilization of heat in the process of adsorption with heat release / conversion with heat absorption.

Description

Carbon dioxide capture and utilization method and device and method for treating high-temperature flue gas from heating furnace Technical Field

[0001] The present invention belongs to the field of chemical industry and relates to a carbon dioxide capture and utilization method and device for capturing carbon dioxide from gas and converting and utilizing it in situ, as well as a method for treating high-temperature flue gas from a heating furnace. Background Art

[0002] Carbon capture, utilization, and storage (CCUS) is the most important technological path for addressing global climate change and controlling greenhouse gas emissions. China has pledged to the world to "peak carbon emissions by 2030" and "achieve carbon neutrality by 2060." The Central Economic Work Conference listed it as one of the eight key tasks for 2021. This "new climate target" will trigger a huge change in my country's energy landscape. There are many sources of CO2 emissions in modern industrial production, such as cement, steel, electricity, coal chemical industry, and refineries, which are all major CO2 emitters. In response to the CO2 emission problem, various industries have conducted research and exploration on the capture, utilization, and storage of CO2. Each industry has developed a variety of CO2 capture, utilization, and storage technologies based on its own characteristics.

[0003] Currently, large-scale carbon capture research focuses on the power industry. Chemical absorption capture of post-combustion flue gas from coal-fired power plants is a relatively mature technology. However, high-temperature flue gas requires sequential heat exchange before it can be absorbed by solvents at low temperatures. Furthermore, the high cost and energy consumption of solvent regeneration increase energy consumption by approximately 30% for coal-fired power plants. Furthermore, off-site storage of captured CO2 incurs high transportation costs and raises concerns about safety risks. Adsorption is also technically mature, but is generally limited to conditions with a defined gas composition. The adsorbent capacity and CO2 selectivity are low, resulting in high costs and, generally, limited to low-temperature gases. Membrane methods generally lack a high degree of separation and require multiple stages and / or recycling, resulting in increased complexity, energy consumption, and cost. Furthermore, impurities in the gas can cause blockage. These capture methods only yield high-concentration CO2 gas, and subsequent transportation and utilization remain significant issues. Developing technologies to capture CO2 and convert it into high-value-added chemicals is key.

[0004] In recent years, with strong support from the Chinese government, enterprises, institutions, research institutes, and universities have jointly participated in a series of research projects focusing on supporting policies, relevant theories, and key technologies. A professional research team has been established, resulting in a number of achievements and progress. Details of major domestic industrial pilot and demonstration projects are as follows: Huaneng Group's CO2 capture demonstration project, launched in December 2009 at the Shanghai Shidongkou Second Power Plant, utilizes proprietary CO2 capture technology. The project captures 120,000 tons of CO2 annually, achieving a purity exceeding 99.5%. Part of the captured CO2 is used in a refining system for the food processing industry, while the remainder is used in industrial production. At the time of commissioning, the capture unit was the world's largest CO2 capture unit for coal-fired power plant flue gas. The 250MW IGCC unit of Huaneng Tianjin Green Coal Power was completed and put into operation in 2011, and the 400MW IGCC unit equipped with a CO2 capture device was completed in 2016. The demonstration project aims to research, develop, demonstrate and promote a coal-based power generation system with near-zero CO2 emissions, while significantly improving power generation efficiency and mastering the design, construction and operation technologies of large-scale coal gasification projects.

[0005] Currently, three companies have established pilot demonstrations of calcium cycle CO2 capture, including the 1.7MWth power plant flue gas CO2 capture demonstration system of La Pereda in Spain, the 1MWth power plant flue gas CO2 capture demonstration system of Darmstadt in Germany, and the 3kWth power plant flue gas CO2 capture pilot of ITRI Research Institute in Taiwan, China. All of them use a calcium cycle double fluidized bed cycle capture system to achieve CO2 capture and regeneration in flue gas.

[0006] All of the aforementioned technologies focus on CO2 capture, not conversion and subsequent utilization. Published patents on CO2 capture and conversion research primarily focus on catalysts. Because CO2 capture is a highly exothermic reaction and the conversion process is highly endothermic, temperature and heat control during the reaction is crucial. Process design and reactor type are crucial to the feasibility of the technology. Common approaches for highly endothermic and exothermic reactions include using coils for heat extraction / supplementation, direct combustion heating, and fluidized and moving beds. These methods present challenges for CO2 capture and conversion. Using coils for heat extraction / supplementation presents challenges in controlling the transition between capture and conversion, with the coils alternating between heat extraction and absorption. Furthermore, due to the uneven reaction within the catalyst bed, localized overheating / undercooling is difficult to avoid. Direct fuel gas heating often leads to post-combustion gas overheating. Taking the commonly used CaO / CaCO3 adsorbent as an example, when the temperature is greater than 850-900℃, the adsorbent will melt and sinter. The invention does not have any measures to prevent sintering; at the same time, inert gases such as N2 and impurity components introduced during the combustion process will also cause severe dilution of the product, resulting in a decrease in the effective gas concentration.

[0007] CN113148951B discloses a method for reducing carbon monoxide synthesis gas using a high-temperature molten heat carrier, carbon dioxide, and carbon powder. This method utilizes carbon dioxide and carbon powder to absorb the sensible and latent heat emitted by the high-temperature heat carrier, raising the temperature to the reduction temperature and instantly reducing it to carbon monoxide high-energy synthesis gas. The high-temperature volumetric heat capacity of carbon dioxide is then used to circulate heat exchange with the granulated high-temperature heat carrier. The entire process is lengthy, and the core equipment is similar to a fluidized bed, resulting in a large pressure drop. The process temperature fluctuates frequently between 50°C and 1500°C, and these drastic temperature changes inevitably lead to energy consumption issues. The lengthy process also leads to pressure drop issues. Flue gas pressure is typically low, and this large pressure drop also limits the use of this technology.

[0008] CN208865610U discloses a catalytic reaction apparatus with a methane + water vapor hydrogen production catalyst at the bottom to produce hydrogen, carbon dioxide introduced into the middle, and a carbon dioxide hydrogenation catalyst at the top. The carbon dioxide and hydrogen react to produce carbon monoxide gas at the top. The main problems with this patent are: first, carbon dioxide hydrogenation is a highly endothermic reaction. Every 5% reaction of equivalent CO2 and H2 causes a temperature drop of approximately 150°C. Under this reactor type, the reaction is actually unsustainable and quickly terminates due to the temperature drop; second, the reactor does not involve carbon capture and is simply a carbon dioxide hydrogenation reactor.

[0009] CN105080564B discloses a method based on manganese and lanthanide metal catalysts for hydrogenating carbon dioxide to produce carbon monoxide via a reverse water gas reaction. The main issues with this patent are similar to those with CN208865610U. First, carbon dioxide hydrogenation is a highly endothermic reaction. Every 5% reaction of equivalent CO2 and H2 results in a temperature drop of approximately 150°C. In this reactor configuration, the reaction is effectively unsustainable and quickly terminates due to the temperature drop. Second, this reactor does not involve carbon capture and is simply a carbon dioxide hydrogenation reactor.

[0010] Currently, published patents and literature, both domestically and internationally, focus on CO2 capture and the CO2 hydrogenation reverse water gas reaction, while research on CO2 capture and in-situ conversion is rare. Efficiently capturing CO2 at high temperatures and converting the captured CO2 into syngas products in situ, facilitating the subsequent synthesis of high-value-added light olefins and other chemical products, can significantly improve energy efficiency and effectively reduce emission reduction costs. This approach avoids the high energy consumption of cooling the capture process and heating the conversion process, addressing the high costs of post-capture CO2 purification and transportation, as well as the potential safety hazards associated with storage. This is expected to improve the feasibility and economic efficiency of the entire CO2 emission reduction process, and is of great significance.

[0011] All patent and non-patent literature, including but not limited to textbooks and journal articles, mentioned herein are incorporated by reference in their entirety.

[0012] Summary of the Invention

[0013] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and provide a carbon dioxide capture and utilization method, device and application thereof for capturing carbon dioxide from high-temperature gas containing carbon dioxide and converting it into synthesis gas in situ, while realizing the comprehensive utilization of the heat absorbed and released in this process.

[0014] To achieve the above-mentioned object of the invention, the first aspect of the present invention provides a method for capturing and utilizing carbon dioxide, comprising the following steps:

[0015] 1) introducing carbon dioxide-containing gas into a reactor filled with a catalytic material and a heat storage material, adsorbing carbon dioxide in the carbon dioxide-containing gas with the catalytic material, and discharging the resulting carbon dioxide-depleted purified gas from the reactor, wherein the catalytic material is a material having dual functions of carbon dioxide adsorption and catalytic conversion;

[0016] 2) switching the carbon dioxide-containing gas to a preheated mixed recycle gas comprising a reducing gas and a recycle gas, allowing the mixed recycle gas to react with a catalytic material adsorbing carbon dioxide in a reactor to regenerate the catalytic material and convert carbon dioxide, and discharging the resulting CO-containing conversion gas (hereinafter referred to as synthesis gas) from the reactor;

[0017] 3) exchanging heat between the reformed gas discharged from the reactor and the mixed circulating gas to preheat the mixed circulating gas, and dividing the reformed gas after heat exchange into two streams, one of which is discharged from the system as product gas, and the other is mixed with the reducing gas as circulating gas; and

[0018] 4) switching the preheated mixed circulating gas containing reducing gas and circulating gas to gas containing carbon dioxide,

[0019] 5) Repeat steps 1) to 4);

[0020] It is characterized in that the method is carried out in at least two reactors in switching operation, so that when the carbon dioxide adsorption process of step 1) is carried out in one reactor, the catalytic material regeneration and carbon dioxide conversion process of step 2) is carried out in another reactor.

[0021] The second aspect of the present invention provides a carbon dioxide capture and utilization device, in particular, a carbon dioxide capture and utilization device for implementing the carbon dioxide capture and utilization method described in the first aspect of the present invention, comprising: at least two reactors filled with catalytic materials and heat storage materials, a heat exchanger, a first feed pipeline, a second feed pipeline, a first discharge pipeline and a second discharge pipeline, the reactor being provided with a reactor outlet and an inlet, the reactor inlet being connected to the first feed pipeline and the second feed pipeline, the reactor outlet being connected to the first discharge pipeline and the second discharge pipeline, and the heat exchanger being arranged between the second discharge pipeline and the second feed pipeline.

[0022] The third aspect of the present invention provides a method for treating high-temperature flue gas at the outlet of a heating furnace, comprising: cooling and pressurizing the high-temperature flue gas at the outlet of the heating furnace, and then treating it as carbon dioxide-containing gas using the carbon dioxide capture and utilization method described in the first aspect of the present invention or the carbon dioxide capture and utilization device described in the second aspect of the present invention to obtain purified gas; preferably, the cooling and pressurization are carried out in the following manner: using a waste heat boiler to extract heat from the high-temperature flue gas, increasing the pressure using a booster, and then exchanging heat with the purified gas obtained after treatment.

[0023] According to the present invention, CO2 adsorption and conversion realize in-situ adsorption and conversion reactions under similar temperature and pressure conditions, thereby reducing carbon dioxide emissions and utilizing carbon dioxide in a low-cost manner, avoiding the high energy consumption of capture cooling / conversion heating and the high cost of purification and transportation of CO2 after capture, as well as the safety hazards caused by CO2 storage. The catalyst has its own heat storage function as a heat buffer, which can effectively prevent the reactor from overheating during the adsorption process. The reactor is inherently safe. The heat of the adsorption exothermic / conversion endothermic process can be coupled in situ to achieve energy-saving effects. The reactor can control the catalyst bed temperature in the regeneration mode through the circulation volume, without introducing new impurity components and without the need for additional heating in the middle of the reaction. The process is simple, can realize automatic sequential control, low pressure drop, easy operation and maintenance, low investment, small footprint, and strong adaptability.

[0024] Other features and advantages of the present application will be described in detail in the following description of the drawings and the detailed description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide further understanding of the present application and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present application, but do not constitute a limitation to the present application.

[0026] FIG1 is a simple flow chart of a method for capturing and utilizing carbon dioxide according to the present invention;

[0027] FIG2 is a catalyst bed type in which catalytic materials with adsorption / catalytic functions and heat storage materials are uniformly mixed according to the present invention;

[0028] FIG3 is another catalyst bed type in which the adsorption / catalytic material and the heat storage material are layered and filled according to the present invention;

[0029] FIG4 is a complete treatment process of sulfur-containing flue gas from the outlet of a heating furnace according to the present invention.

[0030] The reference numerals shown in the figures are:

[0031] 1. High-temperature flue gas, 2. Reducing gas, 3. Purified gas, 4. Synthesis gas, 5. Heat exchange synthesis gas, 6. Cooling synthesis gas, 7. Pressurized synthesis gas, 7-1. Product gas, 7-2 Circulating gas, 8. Mixed circulating gas, 9. Conversion reactor inlet gas, 11. Adsorption reactor, 12. Conversion reactor, 13. Catalyst bed, 13-1. Catalyst bed type in which adsorption / catalytic materials and heat storage materials are uniformly mixed, 13-2. Catalyst bed type in which adsorption / catalytic materials and heat storage materials are layered, 14. Heat exchanger, 15. Cooler, 16. Circulating compressor, 17. Heater, 111 - Heating furnace, 112 - Waste heat boiler, 113 - Booster, 114 - Desulfurization reactor, 115 - Flue gas heat exchanger, 116 - Purified flue gas waste heat boiler, 121-128 - Control valves.

[0032] Like or similar reference numbers identify like or similar parts throughout the several views of the drawings. DETAILED DESCRIPTION

[0033] The following is a detailed description of the specific embodiments of the present application. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present application and are not intended to limit the present application.

[0034] Any specific numerical value disclosed herein (including the endpoints of a numerical range) is not limited to the exact value of the numerical value, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Moreover, for a disclosed numerical range, any combination of the endpoints of the range, between the endpoints and the specific points in the range, and between the specific points can be used to generate one or more new numerical ranges, and these new numerical ranges should also be considered to be specifically disclosed herein.

[0035] When a component, element, or layer is referred to as being "on," "connected," "connected," or "coupled" to another element or layer, it may be directly on, connected, connected, or coupled to the other component, element, or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being directly on, "directly connected," "directly connected," or "directly coupled" to another element or layer, there may be no intervening elements or layers. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used herein, the term "and / or" includes any and all combinations of one or more of the associated enumerated items.

[0036] In the context of this application, carbon capture and utilization (CCU) is the process of capturing carbon dioxide and processing it for further use.

[0037] In the context of this application, the catalytic material has the dual functions of carbon dioxide adsorption and catalytic conversion.

[0038] In the context of this application, a thermal storage material is a material that is able to store thermal energy and release it when needed.

[0039] In the context of the present application, synthesis gas refers to a gas mixture comprising CO or comprising CO and H2 or comprising CO and water vapor. In the context of the present application, synthesis gas is also called reformed gas or reformed gas comprising CO.

[0040] In the context of this application, clean gas refers to gas produced after carbon dioxide-containing gas is depleted of carbon dioxide.

[0041] In the context of this application, an adsorption reactor is a reactor in which an adsorption reaction occurs, and a conversion reactor is a reactor in which a conversion reaction occurs. In the adsorption reactor, the catalytic material adsorbs carbon dioxide from the carbon dioxide-containing gas to produce a purified gas depleted in carbon dioxide. In the conversion reactor, the carbon dioxide adsorbed in the catalytic material reacts with a reducing gas to produce a conversion gas containing CO, while simultaneously regenerating the catalytic material so that it can be used in subsequent adsorption processes.

[0042] In the context of this application, ambient temperature is a temperature of about 20 to about 25°C.

[0043] Unless otherwise specified, the terms used herein have the same meaning as commonly understood by those skilled in the art. If a term is defined herein and its definition is different from the commonly understood meaning in the art, the definition herein shall prevail.

[0044] As described above, in a first aspect, the present application provides a method for capturing and utilizing carbon dioxide, comprising the following steps:

[0045] 1) introducing carbon dioxide-containing gas into a reactor filled with a catalytic material and a heat storage material, adsorbing carbon dioxide in the carbon dioxide-containing gas with the catalytic material, and discharging the resulting carbon dioxide-depleted purified gas from the reactor, wherein the catalytic material is a material having dual functions of carbon dioxide adsorption and catalytic conversion;

[0046] 2) switching the carbon dioxide-containing gas to a preheated mixed circulating gas comprising a reducing gas and a circulating gas, allowing the mixed circulating gas to react with the catalytic material adsorbed with carbon dioxide in the reactor to achieve regeneration of the catalytic material and conversion of carbon dioxide, and the resulting converted gas containing CO is discharged from the reactor;

[0047] 3) exchanging heat between the reformed gas discharged from the reactor and the mixed circulating gas to preheat the mixed circulating gas, and dividing the reformed gas after heat exchange into two streams, one of which is discharged from the system as product gas, and the other is mixed with the reducing gas as circulating gas; and

[0048] 4) switching the preheated mixed circulating gas containing reducing gas and circulating gas to gas containing carbon dioxide,

[0049] 5) Repeat steps 1) to 4);

[0050] It is characterized in that the method is carried out in at least two reactors in switching operation, so that when the carbon dioxide adsorption process of step 1) is carried out in one reactor, the catalytic material regeneration and carbon dioxide conversion process of step 2) is carried out in another reactor.

[0051] In some embodiments, the reaction temperature of step 1) is from room temperature to 800°C, preferably from 400 to 780°C, and more preferably from 600 to 750°C.

[0052] In some embodiments, the reaction temperature of step 2) is 100-950°C, preferably 400-900°C, more preferably 600-800°C.

[0053] Carbon dioxide adsorption and conversion are completed in situ under similar temperature and pressure conditions, avoiding the high energy consumption of capture cooling / conversion heating in traditional technologies.

[0054] In some embodiments, the mixed recycle gas that has undergone heat exchange in step 3) is further heated by a heater before entering the reactor;

[0055] and / or

[0056] The reformed gas that has undergone heat exchange in step 3) is cooled in a cooler and pressurized by a compressor, preferably a recycle compressor, before being split into two streams. In some embodiments, the cooler outlet temperature is between room temperature and 400°C, preferably between 100°C and 200°C. The heat exchange in step 3) fully utilizes the waste heat of the syngas and uses it to heat the mixed recycle gas.

[0057] In some embodiments, the reactor is provided with one or more catalyst beds, and the catalyst beds are filled with catalytic materials and heat storage materials. In some embodiments, the catalytic material and the heat storage material form a single catalytic heat storage composite material loaded in the catalyst bed. For example, the catalytic material is wrapped around the outside of the heat storage material to form a single catalytic heat storage composite material. Alternatively, the catalytic material and the heat storage material are evenly mixed and loaded into the catalyst bed; or the catalytic material layer and the heat storage material layer are alternately loaded in the catalyst bed, that is, a layer of catalytic material and a layer of heat storage material are loaded in layers. It is easy to imagine that a filling method of a layer of catalytic material to multiple layers of heat storage material or a layer of catalytic material to a layer of heat storage material can also be set.

[0058] In some embodiments, one or more heaters are provided between at least a portion of adjacent catalyst beds in the reactor to supplement heat to the reactor where carbon dioxide conversion reaction and catalytic material regeneration occur.

[0059] In some embodiments, the carbon dioxide-containing gas is a high-temperature carbon dioxide-containing gas, preferably a high-temperature flue gas containing carbon dioxide, more preferably a high-temperature flue gas from a cement plant, a steel plant, a power plant, a coal chemical plant, or a refinery. The temperature of the carbon dioxide-containing gas is 100°C to 900°C, preferably 500°C to 800°C, and more preferably 600°C to 750°C.

[0060] In some embodiments, the reducing gas refers to a gas that can react with CO2 to generate CO. Preferably, the reducing gas comprises one or more of H2, CH4 and C2H6, or comprises at least one of the above gases and an inert gas such as nitrogen, or is composed of the above substances.

[0061] In some embodiments, the reactor is first purged with an inert gas, such as nitrogen, before switching the feed, and then the subsequent steps are repeated alternately.

[0062] In some embodiments, the catalytic material comprises a catalytically active component and a carbon dioxide adsorption material. The catalytically active component is a component that can catalyze the reaction of carbon dioxide with a reducing gas, and the present invention does not particularly limit its specific components. For example, the catalytically active component includes Fe, Co, Ni, lanthanides, Ru, Cu, Pd, In, Rh, Ir, Pt, and compounds thereof, such as oxides, or a mixture of two or more of the above substances, or consists of the above substances. The carbon dioxide adsorption material is selected from alkaline earth metal oxides, preferably calcium oxide and magnesium oxide. In some embodiments, the catalytic material is selected from a carbon dioxide adsorption material loaded with one or more catalytically active components. In some embodiments, the heat storage material is selected from corundum, ceramics, mullite, zircon and cordierite. The catalytic material is preferably a CaO-based catalytic material. Wherein, the mass ratio of carbon dioxide adsorption material to catalytically active component is 1:0.1~0.5.

[0063] By using a thermal storage material, the heat generated during the adsorption process in the reactor in step 1) is stored and utilized in situ for the subsequent conversion reaction, achieving in-situ heat utilization and saving energy originally required for the conversion reaction. Furthermore, the use of a thermal storage material reduces the excessive increase in catalyst temperature caused by the heat generated during the adsorption process, thus avoiding the occurrence of "temperature runaway." During the conversion process, the use of a thermal storage material reduces the excessive decrease in gas temperature caused by the heat absorbed during the conversion process, which often leads to excessive pressure drop in the reactor.

[0064] As described above, the second aspect of the present invention provides a carbon dioxide capture and utilization device, in particular, a carbon dioxide capture and utilization device for implementing the carbon dioxide capture and utilization method described in the first aspect of the present invention, comprising: at least two reactors filled with catalytic materials and heat storage materials, a heat exchanger, a first feed pipeline, a second feed pipeline, a first discharge pipeline and a second discharge pipeline, the reactor being provided with a reactor outlet and an inlet, the reactor inlet being connected to the first feed pipeline and the second feed pipeline, the reactor outlet being connected to the first discharge pipeline and the second discharge pipeline, and the heat exchanger performing heat exchange between the second discharge pipeline and the second feed pipeline.

[0065] For the sake of clarity, each feature disclosed for the method in this application is also applicable to the disclosure for the device, and vice versa, unless a person skilled in the art considers it to be obviously unreasonable.

[0066] In some embodiments according to the second aspect, the device is provided with two or more reactors. When provided with more than two reactors,

[0067] Multiple reactors switch feeds simultaneously, or

[0068] Multiple reactors switch feeds independently.

[0069] In some embodiments according to the second aspect, when switching feeds between multiple reactors, the following switching method can be used:

[0070] Switch feed between one reactor and multiple other reactors,

[0071] Switching feeds between multiple reactors and one reactor, or

[0072] Feed switching is performed between multiple reactors.

[0073] In some embodiments according to the second aspect, valves are provided on the first feed line, the second feed line, the first discharge line, and the second discharge line; and / or

[0074] A switching valve capable of switching between two pipelines communicating therewith is provided at both the outlet and the inlet of the reactor.

[0075] In some embodiments according to the second aspect, the first feed pipeline is a carbon dioxide-containing gas feed pipeline, the second feed pipeline is a mixed circulating gas feed pipeline, the first discharge pipeline is a purified gas discharge pipeline, and the second discharge pipeline is a conversion gas discharge pipeline, and the second feed pipeline is connected to the reducing gas pipeline and the circulating gas pipeline, and the second discharge pipeline is connected to the product gas pipeline and the circulating gas pipeline.

[0076] According to some embodiments of the second aspect, the reactor includes one or more catalyst beds, each of which is loaded with a catalytic material and a thermal storage material. When multiple catalyst beds are present, one or more heaters are provided between at least some adjacent catalyst beds in the reactor. The catalytic material and thermal storage material are uniformly mixed and loaded into the catalyst bed, or alternately loaded into the catalyst bed.

[0077] In some embodiments according to the second aspect, the reactor is a fixed bed reactor. In some embodiments according to the second aspect, the reactor is provided with an inlet gas distributor at the inlet.

[0078] According to some embodiments of the second aspect, the carbon dioxide capture and utilization device further comprises a heater disposed on the second feed line and downstream of the heat exchanger, wherein the heater outlet is connected to the reactor inlet.

[0079] According to some embodiments of the second aspect, the carbon dioxide capture and utilization device further includes a cooler and a compressor, preferably a recycle compressor, on the second discharge line. The outlet of the heat exchanger is sequentially connected to the cooler and the compressor, preferably the recycle compressor. Downstream of the compressor, the second discharge line splits into two branches: one for the product gas line and the other for the recycle gas line. The recycle gas line merges with the reducing gas line and serves as a second feed line connected to the heat exchanger.

[0080] In the reactor of the present invention, for the sake of description, the reactor in which the adsorption reaction occurs is also referred to as the adsorption reactor, and the reactor in which the conversion reaction and catalytic material regeneration occur is referred to as the conversion reactor. The structures of the adsorption reactor and the conversion reactor are the same, and different names are used only for convenience of description. When the adsorption reactor and the conversion reactor regularly switch the feed and subsequent processes, the functions of the adsorption reactor and the conversion reactor are interchanged. The adsorption reactor and the conversion reactor are both fixed bed reactors, both single or multiple, and the catalyst bed is filled with a catalyst. The catalyst includes a catalytic material and a heat storage material. In some embodiments, the catalytic material includes a catalytically active component and a carbon dioxide adsorbent material. The catalytically active component is a component that can catalyze the reaction of carbon dioxide with a reducing gas, and the present invention does not impose any particular restrictions on its specific components. For example, the catalytically active component includes Fe, Co, Ni, lanthanides, Ru, Cu, Pd, In, Rh, Ir, Pt, and compounds thereof, such as oxides, or a mixture of two or more of the above substances, or consists of the above substances. The carbon dioxide adsorbent material is selected from alkaline earth metal oxides, preferably calcium oxide and magnesium oxide. In some embodiments, the catalytic material is selected from a carbon dioxide adsorbent material loaded with one or more catalytically active components. In some embodiments, the thermal storage material is selected from corundum, ceramic, mullite, zircon, and cordierite. The catalytic material and thermal storage material can be integrated by sintering, forming a core-shell structure composite, etc., or can be uniformly mixed and packed in a certain proportion or layered in the catalyst bed.

[0081] The reducing gas refers to a gas that can react with CO to produce CO, such as any one or more gas mixtures of H, CH, and C2H6, or a mixture of these gases with an inert gas (such as nitrogen). The reducing gas may also contain a small amount of other gases, including olefins and lower alkanes, as long as their content does not impair the conversion reaction occurring in the conversion reactor. These reducing gases react with the CO adsorbed by the catalytic material in the conversion reactor, regenerating the catalytic material so that it can continue to adsorb CO2 in the next cycle.

[0082] When these gases are introduced separately, the following reactions will occur: CO2+2H2=CO+H2O+H2 or CO2+H2=CO+H2O CO2+CH4=2CO+2H2 2CO2+C2H6=4CO+3H2

[0083] When the adsorption reactor and the conversion reactor of the present invention respectively use multiple reactors, they can be switched and operated simultaneously or independently one by one.

[0084] The catalyst described herein comprises a composite of a catalytic material with adsorption / catalytic functions and a thermal storage material in a specific ratio. During adsorption, the reaction is exothermic, and the thermal storage material stores heat to control the bed temperature. A higher proportion of thermal storage material results in a lower bed temperature rise, but also lower bed space utilization, and vice versa. The catalytic material and thermal storage material can be loaded into the catalyst bed by uniformly mixing them in a specific ratio, or by layering them in the catalyst bed, with one layer of catalytic material and one layer of thermal storage material. The ratio of catalytic material to thermal storage material determines the temperature rise of the gas before and after adsorption. In the absence of thermal storage material, for typical flue gases with a CO2 content of 5-20% by volume, the maximum temperature rise of the purified gas after adsorption can reach over 600°C compared to the CO2-containing gas before adsorption. A higher proportion of thermal storage material results in a lower temperature rise of the purified gas after adsorption. The specific ratio of catalytic material to thermal storage material can be determined based on a combination of considerations, including the reactor's design temperature, the inlet CO2-containing gas temperature, and the maximum temperature tolerance of the catalytic material. Typically, the recommended volume ratio of catalytic material to thermal storage material ranges from 5:1 to 1:10.

[0085] The adsorption reactor and conversion reactor of the present invention have a catalyst bed filled with a catalytic material amount A (m 3 ) is determined by the amount of carbon dioxide to be adsorbed A1 (t / h), the material adsorption capacity A2 (t / m 3 ) and the design switching time A3 (h), the specific calculation formula is as follows: A=A1xA3 / A2

[0086] Where: A1 represents the amount of carbon dioxide to be adsorbed;

[0087] A2 represents the adsorption capacity of the material;

[0088] A3 expresses the design switching time.

[0089] The amount of the heat storage material is determined by the inlet temperature of the carbon dioxide-containing gas, the gas composition and specific heat, the heat released by the adsorbed carbon dioxide reaction, the amount and specific heat of the catalytic material, the specific heat of the heat storage material, the heat loss of the reactor, the final temperature of the reactor bed that is desired to be controlled, etc.

[0090] The catalyst bed of the present invention is located in the reactor and can be filled in a single stage or in layers.

[0091] The material inlet and outlet modes of the reactor of the present invention can be bottom-in and top-out, top-in and bottom-out, side-in and side-out, periphery-in and middle-out, middle-in and periphery-out, etc.

[0092] The main purpose of the cooler of the present invention is to recover the heat of the synthesis gas and reduce the inlet temperature of the circulating fan. Under normal circumstances, the outlet temperature of the cooler is controlled to be room temperature to 400°C, and the preferred temperature range is 100-200°C.

[0093] The compressor of the present invention preferably has two outlet gas streams: one stream is delivered as product gas, and the other stream is used as recycle gas and circulated to the conversion reactor. The amount of product gas delivered is controlled based on the amount of decarburization or system pressure. The recycle gas volume (B (t / h)) should be calculated, with the main relevant parameters including: the endothermic load (B1) (kW) of the conversion reaction, the heat loss (B2) (kW) of the conversion reactor, the total heat release (B3) (kJ) of the catalyst bed during the conversion phase, the switching period (B4) (h) of the conversion reaction, and the heat difference (B5) (kJ / kg) between the inlet and outlet gas zones of the reactor.

[0094] The specific calculation formula is as follows: B=[(B1+B2)*3600-B3 / B4] / B5

[0095] Where: B1 represents the heat released by the heat storage material;

[0096] B2 represents the heat loss of the reactor;

[0097] B3 represents the heat absorbed during the conversion process;

[0098] B4 represents the total heat brought in by the inlet reducing gas;

[0099] B5 represents the total heat carried away by the outlet synthesis gas.

[0100] The circulating gas volume of the present invention is preferably based on the above-mentioned calculated value. When the circulating gas volume is less than the above-mentioned calculated value, the bed layer in the reactor should be arranged in sections, and heaters should be installed between the beds to make up for the heat difference.

[0101] The adsorption reactor and conversion reactor described in the present invention periodically switch feeds. The reactor switching time can be designed based on the material's adsorption capacity for timing control. Alternatively, the reactor operating mode can be switched online based on the CO2 content of the decarbonized gas. This switching can be achieved via valves installed on pipelines outside the reactors.

[0102] The present invention is applicable to the treatment of carbon dioxide-containing gases (such as high-temperature flue gas from heating furnaces), capturing CO2 from the carbon dioxide-containing gas and converting it into synthesis gas in situ. If the temperature of the gas to be treated is too high, it can be lowered to a suitable temperature range by means such as heat recovery; if the temperature is too low, it can be raised to a suitable temperature range by means such as heating.

[0103] The present invention also provides a method for treating high-temperature flue gas at the outlet of a heating furnace, comprising: cooling and pressurizing the high-temperature flue gas at the outlet of the heating furnace, and then treating the high-temperature flue gas as carbon dioxide-containing gas using the carbon dioxide capture and utilization method described in the first aspect of the present invention or the carbon dioxide capture and utilization device described in the second aspect of the present invention to obtain purified gas; preferably, the cooling and pressurization are carried out in the following manner: using a waste heat boiler to extract heat from the high-temperature flue gas, increasing the pressure using a booster, and then exchanging heat with the purified gas obtained after treatment.

[0104] Compared with the prior art, the advantages of the present invention are: 1. CO2 adsorption and conversion realize in situ adsorption and conversion reactions under similar temperature and pressure conditions, which can not only fully improve energy utilization and effectively reduce emission reduction costs, but also avoid the high energy consumption of capture cooling / conversion heating, and solve the high cost of purification and transportation of CO2 after capture, as well as the safety hazards brought by CO2 storage; 2. The reactor is inherently safe, and the catalyst has its own heat storage function as a heat buffer, which can effectively avoid the reactor from overheating during the adsorption process; 3. The in-situ coupled utilization of heat from the adsorption exothermic / conversion endothermic process can be realized to achieve energy saving and emission reduction effects; 4. The reactor can control the catalyst bed temperature in the regeneration mode through the circulation volume, without introducing new impurity components, and no additional heating is required in the middle of the reaction; 5. The process is simple, automatic sequential control can be realized, the pressure drop is low, it is easy to operate and maintain, the investment is low, the footprint is small, and the adaptability is strong.

[0105] The present invention will be further described below with reference to the accompanying drawings.

[0106] As shown in Figure 1, Figure 1 is a simple flow chart of a carbon dioxide capture and utilization method of the present invention. The high-temperature flue gas 1 enters the adsorption reactor 11 from the bottom through the control valve 121, and the control valve 122 is closed at this time. After the high-temperature flue gas 1 passes through the catalyst bed 13, the CO2 in the flue gas is adsorbed and removed, and the purified gas after decarbonization is discharged from the top of the adsorption reactor 11 through the control valve 123. At this time, the control valve 124 is closed. The adsorption reactor 11 and the conversion reactor 12 are equipped with a catalyst bed 13. After the catalytic material in the adsorption reactor 11 reaches the predetermined switching time / predetermined adsorption capacity, the control valve 121 is closed and the control valve 122 is opened to switch the feed of the adsorption reactor 11 to the preheated mixed circulating gas containing reducing gas and circulating gas, and correspondingly, the feed of the conversion reactor 12 is switched to the high-temperature flue gas 1. The mixed recycle gas reacts with the catalytic material adsorbing carbon dioxide within the adsorption reactor 11, regenerating the catalytic material and converting the carbon dioxide. The resulting synthesis gas 4 (converted gas containing CO) is discharged from the top outlet of the adsorption reactor 11 through control valve 124, at which point control valve 123 is closed. The heat required for the conversion process is at least partially provided by the thermal storage material. Synthesis gas 4 exchanges heat with mixed recycle gas 8 through heat exchanger 14. After heat exchange, synthesis gas 5 is recovered in cooler 15, resulting in cooled synthesis gas 6 that enters recycle compressor 16. Recycle compressor 16 raises the pressure of cooled synthesis gas 6, resulting in pressurized synthesis gas 7, which is divided into two streams: product gas 7-1 and recycle gas 7-2. Recycle gas 7-2 is mixed with reducing gas 2, heated as mixed recycle gas 8, and then heated in heater 17 before entering the conversion reactor 12 as conversion reactor inlet gas 9 through control valve 125. Control valve 126 is closed. After the conversion reactor inlet gas 9 passes through the catalyst bed 13, the saturated CO2 adsorbed on the bed is reduced to synthesis gas 4, and then discharged through the control valve 127 at the top of the conversion reactor 12. At this time, the control valve 128 is closed.

[0107] FIG2 is a catalyst bed type of the present invention in which a catalytic material with adsorption / catalytic functions and a heat storage body are uniformly mixed.

[0108] FIG3 shows a catalyst bed type of the present invention in which an adsorption / catalytic material and a heat storage body are layered and filled.

[0109] Figure 4 illustrates a process for treating high-temperature flue gas at the outlet of a heating furnace according to the present invention. After heat is extracted from the heating furnace 111 by the waste heat boiler 112, the gas is then pressurized by the booster 113 and desulfurized by the desulfurization reactor 114. The gas then exchanges heat with the purified gas 3 and enters the adsorption reactor 11 as the high-temperature flue gas 1 feed. The purified gas 3 then exits the adsorption reactor 11 after waste heat is recovered by the purified flue gas waste heat boiler 116. At this point, control valves 121, 123, 125, and 127 are open, while control valves 122, 124, 126, and 128 are closed. The subsequent process is the same as in Figure 1.

[0110] Example

[0111] The present invention will be further described below with reference to specific examples. The examples are merely implementation methods of the present invention under certain specific conditions and should not be considered as limiting the scope of protection of the present invention.

[0112] Example 1:

[0113] With high temperature flue gas containing carbon dioxide 330m 3 Take n / h as an example, the flue gas composition is as follows:

[0114] The flue gas temperature is 640°C and the flue gas pressure is 10 kPaG. See Figure 1 for the specific process.

[0115] 1) 640°C high-temperature flue gas 1 enters adsorption reactor 11 from below through control valve 121. Control valve 122 is closed. After passing through catalyst bed 13, CO2 in the flue gas is adsorbed and removed. The decarbonized purified gas 3 is heated to 727°C and discharged from the top of adsorption reactor 11 through control valve 123. The flue gas pressure is 3 kPa, with a pressure drop of approximately 7 kPa. Control valve 124 is closed.

[0116] 2) The adsorption reactor 11 and the conversion reactor 12 are equipped with a CaO-based catalyst bed. The core of the catalyst sphere is an Al2O3 sphere with a diameter of 3mm (Φ3) for heat storage. The catalyst is attached with a 1mm thick CaO sintered material sphere on the outside for CO2 adsorption. The outer surface is loaded with Ni active components for catalyzing the reaction of CO2 and H2. The total catalyst bed filling volume is 20m 3 .

[0117] The preparation method of CaO-based catalytic materials is to use the sol-gel method to prepare a composite material with a porous structure. While obtaining a composite material with high carbon dioxide adsorption capacity and stability, it also has high catalytic activity sites. The specific steps are as follows:

[0118] (1) Purchase Φ3 Al2O3 spheres.

[0119] (2) Calcium nitrate or calcium chloride and Fe salt as a catalytically active component, as well as Co and Ni salts (the salts may be in the form of chloride, nitrate or acetate) are sequentially added to an aqueous solution. After all components are fully dissolved, an organic template such as citric acid, ammonium citrate, oxalic acid or ammonium oxalate is added to obtain a mixed solution. The molar ratio of the calcium salt to the organic template is 1:1.5 to 3;

[0120] (3) stirring the mixed solution in step (2) to fully dissolve, allowing it to stand for 1 to 2 hours, and then heating it in a water bath at 60 to 90° C. and continuing to stir for 3 to 8 hours to obtain a translucent sol;

[0121] (4) applying the translucent sol in step (3) to the outer surface of the Φ3 Al2O3 sphere in step (1) to form a Φ5 composite sphere, and heating it at 100-150°C for 10-14 hours to obtain a xerogel after drying;

[0122] (5) calcining the dry gel in step (4) in a muffle furnace at a calcination temperature of 800-900° C. for 4 h to 8 h to obtain a finished catalytic material.

[0123] 3) The high-temperature synthesis gas 4 at the top outlet of the conversion reactor 12 is discharged through the control valve 127. At this time, the control valve 128 is closed and the flow rate of the synthesis gas 4 is 1754m 3 n / h, temperature 630℃, after heat exchange with mixed circulating gas 8 through heat exchanger 14, the temperature of heat exchange synthesis gas 5 drops to 260℃, and then after heat recovery through cooler 15, the temperature of cooled synthesis gas 6 drops to 150℃ and enters circulating compressor 16, which pressurizes cooled synthesis gas 6 from 30kPaG to 100kPaG. The pressurized synthesis gas 7 is divided into two paths, of which 7-1 product gas flow rate is 215m 3 n / h, sent out as product; circulating gas 7-2 flow rate 1870m 3 n / h, and 220m3 of hydrogen as reducing gas 2 3 After mixing, the mixed recycle gas 8 enters heat exchanger 14 and is heated to 618°C. The mixed recycle gas 8 is then heated to 730°C by heater 17 before entering the conversion reactor 12 as the conversion reactor inlet gas 9 via control valve 125. At this point, control valve 126 is closed. After passing through the catalyst bed 13, the CO2 adsorbed and saturated therein is reduced to synthesis gas 4, which is then discharged through control valve 127 at the top of the conversion reactor 12.

[0124] The expected composition of product gas 7-1 is as follows:

[0125] 4) After 2 hours, the reactor is purged with hot nitrogen, and control valves 121, 123, 125, and 127 are closed, while control valves 122, 124, 126, and 128 are opened. The feeds to the two reactors 11 and 12 are interchanged, and the cycle is then repeated according to the time sequence control.

[0126] The flue gas treated in this embodiment can reduce CO2 emissions by 1,187 t / a and produce 1,416 t / a of synthesis gas as a by-product.

[0127] Comparative Example 1:

[0128] The adsorption reaction described in the present invention is highly exothermic, while the conversion reaction is highly endothermic. The reaction rate is very high when the catalytic material adsorbs carbon dioxide. Without heat extraction, the adsorption reactor temperature would quickly rise to a temperature exceeding the melting point of CaO, causing the catalytic material to melt, destroying its microporous structure and deactivating it.

[0129] If heat is extracted from a fixed bed of catalytic material using heat exchange tubes, such as water or steam, the adsorption reaction is so rapid that the catalytic material reacts layer by layer, starting from the upstream, much like burning incense. Because the exothermic heat is concentrated and changes over time, the heat exchange tubes cannot achieve the desired heat transfer effect.

[0130] One possible solution is to use a shell-and-tube reactor. The shell-and-tube reactor is used as a comparative example for comparison.

[0131] Similarly, high-temperature flue gas containing carbon dioxide 330m 3 Take n / h as an example, the flue gas composition is as follows:

[0132] The flue gas temperature is 640℃ and the flue gas pressure is 10kPaG.

[0133] 1) The preparation method of the CaO-based catalytic material is similar to that of Example 1, except that the Al2O3 spheres are eliminated as the core / heat storage function part. The specific steps are as follows:

[0134] (1) Calcium nitrate or calcium chloride and Fe salt as a catalytically active component, as well as Co and Ni salts (the salts may be in the form of chloride, nitrate, or acetate) are sequentially added to an aqueous solution. After all components are fully dissolved, an organic template such as citric acid, ammonium citrate, oxalic acid, or ammonium oxalate is added to obtain a mixed solution. The molar ratio of the calcium salt to the organic template is 1:1.5.

[0135] (2) stirring the mixed solution in step (1) to fully dissolve it, letting it stand for 1 to 2 hours, and then heating it in a water bath at 60 to 90° C. and continuing to stir for 3 hours to obtain a translucent sol;

[0136] (3) heating the translucent sol in step (2) at 100-150° C. for 10 h, drying to obtain a xerogel, which is then processed into spheres with a diameter of 3-5 mm by an extrusion method or a ball rolling method;

[0137] (4) The dry gel in step (3) is calcined in a muffle furnace at a calcination temperature of 800-900° C. for 4 h to obtain a finished catalytic material.

[0138] 2) The catalytic material obtained in the above step 1) was loaded into a DN25 reaction tube with a filling height of 6m and 1600 reaction tubes. To ensure the heat transfer area, the outer wall of the reaction tube was made of finned tubes, which were divided into two groups and evenly installed in the two fixed bed reactors of the adsorption reactor and the conversion reactor. The ends of the finned tubes were connected to the two ends of the reactor through the pipe box, and the middle of the reaction tube formed a closed space with the reactor tank and the tank box plates at both ends.

[0139] 3) Due to the high reaction temperatures, the need to control the adsorption temperature between 600-750°C and the conversion reaction temperature between 600-800°C, high requirements are placed on the heat transfer medium outside the reaction tubes. This temperature exceeds the maximum operating temperature of common molten salts such as thermal oil and sodium nitrate. Using BaCl2 or other solvents would also pose serious corrosion issues. Therefore, Li2CO3 molten salt is selected as the heat transfer medium. After melting, it is loaded into the reactor and the tank space outside the reaction tubes is installed. A circulation pump is installed to ensure the molten salt flows between the two reactors for heat transfer, and an electric heater is installed on the heat-conducting molten salt circulation pipe.

[0140] 4) 640°C high-temperature flue gas enters the adsorption reactor from the bottom through a control valve. After passing through the pipe box and into the reaction tubes, the CO2 in the flue gas is adsorbed and removed. The temperature of the decarbonized purified gas rises, and the heat released by the reaction is transferred through the reaction tubes to the molten salt. After the reaction is complete, the flue gas temperature rises to 730°C, with a flue gas pressure drop of approximately 25 kPa during the reaction. During the reaction, the molten salt temperature rises from 630 to 680°C. A circulation pump and electric heater heat the molten salt to 750°C before entering the conversion reactor.

[0141] 5).720℃,220m 3 n / h of hydrogen enters the reaction tube of the conversion reactor through the pipe box, and the product synthesis gas flows out from the other end. The synthesis gas flow rate is 242m 3 n / h, temperature 600°C. The heat required for the reaction is provided by molten salt, and the temperature of the molten salt flowing out of the conversion reactor is reduced to 630°C.

[0142] The expected composition of the product gas is as follows:

[0143] 6) After 2 hours, the reactor is purged with hot nitrogen and the feed is exchanged through the control valve. The cycle is then repeated according to the time sequence control.

[0144] Due to the high price of Li2CO3 molten salt and the addition of a complete molten salt system, the equipment investment is expected to increase by more than 50% compared with Example 1. After industrial scale-up, the number of reaction tubes required will increase significantly, making subsequent operation and maintenance difficult.

[0145] The flue gas treated in this embodiment can reduce CO2 emissions by 1,187 t / a and produce 1,416 t / a of synthesis gas as a by-product.

[0146] Example 2:

[0147] Flue gas from outlet 111 of a heating furnace 100000m 3 Take n / h as an example, the flue gas composition is as follows:

[0148] The specific process is shown in Figure 4.

[0149] 1) Control valves 121, 123, 125, and 127 are open, and control valves 122, 124, 126, and 128 are closed. The flue gas temperature at the outlet of heating furnace 111 is 1100°C, and the flue gas pressure is 5 kPaG. After removing heat from waste heat boiler 112, the flue gas temperature drops to 200°C. It is then pressurized to 0.1 MPaG by booster 113 and desulfurized by desulfurization reactor 114. After heat exchange with purified gas 3 to 600°C, it enters adsorption reactor 11 as the high-temperature flue gas 1 that feeds adsorption reactor 11.

[0150] 2) 600°C high-temperature flue gas 1 enters adsorption reactor 11 from the bottom through control valve 121. After passing through catalyst bed 13, CO2 in the flue gas is adsorbed and removed. The decarbonized purified gas 3 is heated to 740°C and discharged from the top of adsorption reactor 11 through control valve 123. After heat exchange in flue gas heat exchanger 115 and heat recovery in purified flue gas waste heat boiler 116, it is discharged externally. During this process, the flue gas system pressure drop is approximately 8 kPa.

[0151] 3). The catalyst bed of the adsorption reactor 11 and the conversion reactor 12 is filled with Φ3x5 columnar alkaline earth metal oxide catalyst material and Φ3 Al2O3 spheres for heat storage; the total filling volume is 1600m 3 , the two materials each account for half.

[0152] The preparation method of the columnar alkaline earth metal oxide catalytic material with a diameter of 3 mm and a length of 5 mm (Φ3x5) is as follows:

[0153] (1) Calcium nitrate or calcium chloride and catalytically active components, including Fe salt, Co, Ni, and Ce salt (the salts may be in the form of chloride, nitrate, or acetate), are sequentially added to an aqueous solution. After all components are fully dissolved, ammonium citrate and ammonium oxalate are added to obtain a mixed solution. The molar ratio of the calcium salt to the organic template is 1:3.

[0154] (2) stirring the mixed solution in step (1) to fully dissolve it, letting it stand for 1 to 2 hours, and then heating it in a water bath at 60 to 90° C. and continuing to stir it for 8 hours to obtain a translucent sol;

[0155] (3) The translucent sol in step (2) is heated at 100-150° C. for 14 h. After drying, a dry gel is obtained, and then a Φ3x5 columnar material is obtained by extrusion.

[0156] (4) calcining the dry gel in step (3) in a muffle furnace at a calcination temperature of 800-900° C. for 8 h to obtain a finished catalytic material.

[0157] 4) The high-temperature synthesis gas 4 discharged from the top of the conversion reactor 12 through the control valve 127 has a flow rate of 900,000 m 3 n / h, temperature 630℃, after heat exchange with mixed circulating gas 8 through heat exchanger 14, the temperature of heat exchange synthesis gas 5 drops to 240℃, and then after heat recovery through cooler 15, the temperature of cooled synthesis gas 6 drops to 150℃ and enters circulating compressor 16, which increases the pressure of cooled synthesis gas 6 from 30kPaG to 100kPaG. The increased pressure synthesis gas 7 is divided into two paths, of which the flow rate of product gas 7-1 is 60000m 3 n / h, sent as product; circulating gas 7-2 flow rate 840000m 3 n / h, and methane 15000m3 as reducing gas 2 3 After mixing with n / h, it is used as mixed circulating gas 8, enters the heat exchanger 14 to exchange heat with the synthesis gas 4 and is heated to 610°C. The mixed circulating gas 8 is then heated to 730°C by the heater 17, and enters the conversion reactor 12 through the control valve 125 as the conversion reactor inlet gas 9. After passing through the catalyst bed 13, the saturated CO2 adsorbed on the bed is reduced to synthesis gas 4, and then discharged through the top of the conversion reactor 12.

[0158] The expected composition of product gas 7-1 is as follows:

[0159] 5) After 2 hours, the reactor is purged with hot nitrogen, and control valves 121, 123, 125, and 127 are closed, and control valves 122, 124, 126, and 128 are opened. The feeds to the adsorption reactor 11 and the conversion reactor 12 are interchanged. The cycle is then cycled sequentially according to the time sequence control.

[0160] The flue gas treated in this embodiment can reduce CO2 emissions by 27 t / h and produce 36 t / h of synthesis gas as a by-product.

[0161] Comparative Example 2:

[0162] Same as Comparative Example 1, this comparative example also uses a tubular reactor as a comparison, and the flue gas conditions are the same as

[0163] Example 2, that is, the flue gas at the heating furnace outlet is 100000m 3 Take n / h as an example, the flue gas composition is as follows:

[0164] 1). The preparation method of the Φ3x5 columnar alkaline earth metal oxide catalytic material is the same as that in Example 2.

[0165] 2) The catalytic material obtained in step 1) was loaded into DN25 reaction tubes, with a filling height of 6m and 484,800 reaction tubes. To ensure heat transfer area, the outer walls of the reaction tubes were finned. These tubes were divided into two groups and evenly installed in the adsorption reactor and the conversion reactor. The ends of the finned tubes were connected to the ends of the reactor via a pipe box. The middle of the reaction tubes, the reactor tank, and the tank box panels at both ends formed an enclosed space. To control equipment size, six adsorption reactors and six conversion reactors were installed, for a total of 12 reactors.

[0166] 3) 640°C high-temperature flue gas enters six adsorption reactors from the bottom through control valves. After passing through the pipe box and into the reaction tubes, the CO2 in the flue gas is adsorbed and removed. The temperature of the decarbonized purified gas rises, and the heat released by the reaction is transferred through the reaction tubes to the Li2CO3 molten salt. After the reaction is complete, the flue gas temperature rises to 730°C, with a flue gas pressure drop of approximately 35 kPa. During the reaction, the molten salt temperature rises from 630 to 680°C. It is then heated to 750°C by a circulation pump and a heating furnace before entering the conversion reactor.

[0167] 4).720℃,15000m 3 methane flows through a pipe box into the reaction tubes of the conversion reactor at a rate of n / h, and the product, syngas, flows out the other end at a temperature of 600°C. The heat required for the reaction is provided by molten salt, which is cooled to 630°C when it leaves the conversion reactor.

[0168] The expected composition of the product gas is as follows:

[0169] 5) After 2 hours, the reactor is purged with hot nitrogen and the feed is exchanged through the control valve. The cycle is then repeated according to the time sequence control.

[0170] The equipment investment for Comparative Example 2 is expected to increase by over 50% compared to Example 2. This comparative example requires nearly 500,000 reaction tubes. If a leak occurs in a tube, locating the leak point is extremely difficult, making subsequent inspection and maintenance of the equipment difficult. The flue gas pressure drop in Comparative Example 2 is 35 kPa, significantly higher than the 8 kPa in Example 2. Furthermore, energy consumption is expected to be over 40% higher than in Example 2.

[0171] The flue gas treated in this embodiment can reduce CO2 emissions by 27 t / h and produce 36 t / h of synthesis gas as a by-product.

[0172] The preferred embodiments of the present application are described in detail above. However, the present application is not limited to the specific details of the above embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the scope of protection of the present application.

[0173] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this application will not further describe various possible combinations.

[0174] In addition, the various implementation methods of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A method for capturing and utilizing carbon dioxide, comprising the following steps: 1) introducing a carbon dioxide-containing gas into a reactor filled with a catalytic material and a heat storage material, and using the catalytic material to adsorb carbon dioxide in the carbon dioxide-containing gas, and the obtained carbon dioxide-depleted purified gas is discharged from the reactor, wherein the catalytic material is a material having the dual functions of carbon dioxide adsorption and catalytic conversion; 2) switching the carbon dioxide-containing gas to a preheated mixed circulating gas containing reducing gas and circulating gas, allowing the mixed circulating gas to react with the catalytic material adsorbing carbon dioxide in the reactor to achieve regeneration of the catalytic material and conversion of carbon dioxide, and the resulting converted gas containing CO is discharged from the reactor; 3) exchanging heat between the reformed gas discharged from the reactor and the mixed circulating gas to preheat the mixed circulating gas, and dividing the reformed gas after the heat exchange into two streams, one of which is discharged from the system as product gas, and the other is mixed with the reducing gas as circulating gas; as well as 4) switching the preheated mixed circulating gas containing reducing gas and circulating gas to gas containing carbon dioxide, 5) Repeat steps 1) to 4); Characterized in that the method is carried out in at least two reactors in switching operation, so that when the carbon dioxide adsorption process of step 1) is carried out in one reactor, the catalytic material regeneration and carbon dioxide conversion process of step 2) is carried out in another reactor.

2. The method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The reaction temperature of step 1) is room temperature to 800°C, preferably 400 to 780°C, more preferably 600 to 750°C; and / or The reaction temperature of step 2) is 100-950°C, preferably 400-900°C, more preferably 600-800°C.

3. The method for capturing and utilizing carbon dioxide according to claim 1 or 2, characterized in that: In step 3), the mixed circulating gas after heat exchange is further heated by a heater before entering the reactor; and / or In step 3), the converted gas after heat exchange is cooled by a cooler and compressed by a compressor before being divided into two streams, preferably by a circulating compressor for pressurization. Preferably, the outlet temperature of the cooler is between room temperature and 400°C, preferably between 100 and 200°C.

4. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 3, characterized in that: One or more catalyst beds are arranged in the reactor, and the catalytic material and the heat storage material form a single catalytic heat storage composite material loaded in the catalyst bed, loaded in the catalyst bed after being uniformly mixed, or loaded in the catalyst bed in layers and alternately.

5. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 4, characterized in that: The reactor is provided with two or more catalyst beds filled with catalytic materials and heat storage materials. Preferably, one or more heaters are provided between at least some adjacent catalyst beds.

6. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 5, characterized in that: The carbon dioxide-containing gas is a high-temperature gas containing carbon dioxide, preferably a high-temperature flue gas containing carbon dioxide, and more preferably a high-temperature flue gas from a cement plant, a steel plant, a power plant, a coal chemical plant and a refinery, wherein the temperature of the carbon dioxide-containing gas is 100°C-900°C, preferably 500°C-800°C, and more preferably 600°C-750°C.

7. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 6, characterized in that: The reducing gas is a gas that can react with CO2 to generate CO, and preferably contains at least one of H2, CH4 and C2H6, or contains at least one of H2, CH4 and C2H6 and an inert gas.

8. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 7, characterized in that: The reactor was purged with an inert gas before each feed switch.

9. The method for capturing and utilizing carbon dioxide according to any one of claims 1 to 8, characterized in that: The catalytic material comprises a catalytically active component and a carbon dioxide adsorbing material, wherein the catalytically active component comprises Fe, Co, Ni, lanthanide elements, Ru, Cu, Pd, In, Rh, Ir, Pt, and compounds thereof, such as oxides, or a mixture of two or more of the above substances, or consists of the above substances, and the carbon dioxide adsorbing material is selected from alkaline earth metal oxides, preferably calcium oxide and magnesium oxide, and The heat storage material is selected from corundum, ceramic, mullite, zircon, cordierite and a mixture thereof.

10. A carbon dioxide capture and utilization device, in particular a carbon dioxide capture and utilization device for implementing the carbon dioxide capture and utilization method according to any one of claims 1 to 9, comprising: At least two reactors filled with catalytic materials and heat storage materials, a heat exchanger, a first feed pipeline, a second feed pipeline, a first discharge pipeline and a second discharge pipeline, the reactor is provided with a reactor outlet and an inlet, the reactor inlet is connected with the first feed pipeline and the second feed pipeline, the reactor outlet is connected with the first discharge pipeline and the second discharge pipeline, and the heat exchanger performs heat exchange between the second discharge pipeline and the second feed pipeline.

11. The carbon dioxide capture and utilization device according to claim 10, wherein: The first feed pipeline, the second feed pipeline, the first discharge pipeline and the second discharge pipeline are all provided with valves; and / or A switching valve capable of switching between two pipelines connected thereto is provided at the outlet and the inlet of the reactor.

12. The carbon dioxide capture and utilization device according to claim 10 or 11, wherein: The first feed pipeline is a carbon dioxide-containing gas feed pipeline, the second feed pipeline is a mixed circulating gas feed pipeline, the first discharge pipeline is a purified gas discharge pipeline, and the second discharge pipeline is a conversion gas discharge pipeline, and the second feed pipeline is connected to a reducing gas pipeline and a circulating gas pipeline, and the second discharge pipeline is connected to a product gas pipeline and a circulating gas pipeline.

13. The carbon dioxide capture and utilization device according to any one of claims 10 to 12, characterized in that: One or more catalyst beds are arranged in the reactor, and the catalytic material and the heat storage material form a single catalytic heat storage composite material which is loaded in the catalyst bed, uniformly mixed and loaded in the catalyst bed, or alternately loaded in the catalyst bed. Preferably, when a plurality of catalyst beds are provided, one or more heaters are provided between at least some of the adjacent catalyst beds.

14. The carbon dioxide capture and utilization device according to any one of claims 10 to 13, characterized in that: The reactor is a fixed bed reactor; and / or An air inlet distributor is provided at the inlet of the reactor.

15. The carbon dioxide capture and utilization device according to any one of claims 10 to 14, further comprising a heater provided on the second feed pipeline and located downstream of the heat exchanger.

16. The carbon dioxide capture and utilization device according to any one of claims 10 to 15, further comprising a cooler and a compressor, preferably a circulating compressor, connected to the second discharge pipeline and located downstream of the heat exchanger. Preferably, the compressor outlet is communicated with the product gas pipeline and the circulating gas pipeline respectively.

17. A method for treating high-temperature flue gas at a heating furnace outlet, comprising: The high-temperature flue gas at the outlet of the heating furnace is cooled and pressurized, and then treated as carbon dioxide-containing gas using the carbon dioxide capture and utilization method described in any one of claims 1 to 9 or the carbon dioxide capture and utilization device described in any one of claims 10 to 16 to obtain purified gas; Preferably, the cooling and pressurizing are performed in the following manner: heat is extracted from the high-temperature flue gas by a waste heat boiler, the pressure is increased by a booster, and then heat is exchanged with the purified gas obtained after treatment.

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