Fluidized bed-based carbon dioxide capture and utilization method

Abstract

The invention discloses a carbon dioxide trapping and utilizing method based on a fluidized bed. Carbon dioxide-containing gas enters an adsorption reactor to be in contact with a catalyst and is adsorbed by the catalyst to become purified gas, the purified gas is discharged after being subjected to dust removal, the catalyst adsorbing CO2 enters a conversion reactor to be in contact with reducing gas and is returned to the adsorption reactor after being reduced, and reaction product gas in the conversion reactor leaves from the conversion reactor. The method comprises the following steps: firstly exchanging heat with circulating gas, then cooling, dedusting and boosting, dividing into two streams, sending out one stream as product gas, and mixing the other stream as circulating gas with reducing gas after exchanging heat with reaction product gas to enter a conversion reactor for recycling. By using the method disclosed by the invention, in-situ adsorption and conversion reaction of CO2 adsorption and conversion can be realized under approximate temperature and pressure conditions, so that the energy utilization rate can be fully improved, the emission reduction cost can be effectively reduced, and high energy consumption of trapping cooling / conversion heating can be avoided.

Description

Technical Field

[0001] The present invention relates to a fluidized bed-based carbon dioxide capture and utilization method for capturing carbon dioxide from gas and converting and utilizing the carbon dioxide in situ. Background Art

[0002] Carbon capture, utilization and storage (CCUS) is the most important technical path to address global climate change and control greenhouse gas emissions. 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 formed a variety of technical methods for CO2 capture, utilization and storage based on its own industry characteristics.

[0003] At present, the focus of large-scale research on carbon capture is on the power industry. Among them, the chemical absorption capture method for flue gas after combustion in coal-fired power plants is a relatively mature technology. However, high-temperature flue gas requires step-by-step heat exchange to be absorbed at low temperatures, and its solvent cost is high and the regeneration energy consumption is high, which causes the energy consumption of coal-fired power plants to increase by about 30%. At the same time, the captured CO2 is stored off-site, which requires high transportation costs, and safety hazards are also questioned. The adsorption method is also relatively mature in technology, but it is generally only used for working conditions with a certain gas composition. The capacity and CO2 selectivity of the adsorbent are low, the cost is high, and it is generally only used for low-temperature gas. The membrane method usually cannot achieve a high degree of separation and requires multiple stages and / or recycling, which leads to increased complexity, energy consumption and cost. At the same time, impurities in the gas may also cause blockage. After the above methods are captured, only high-concentration CO2 gas is obtained, and subsequent transportation and utilization are also issues worthy of attention. The development of CO2 capture and conversion technology into high-value-added chemicals is the key.

[0004] In recent years, with the strong support of the Chinese government, enterprises, scientific research institutions and universities have jointly participated in a series of studies on supporting policies, relevant theories and key technologies, established a professional research team, and achieved a number of results and progress. The specific situation of major domestic industrial pilot and demonstration projects is as follows: The CO2 capture demonstration project launched by Huaneng Group in Shanghai Shidongkou Second Power Plant in December 2009 used CO2 capture technology with independent intellectual property rights, with an annual CO2 capture scale of 120,000 tons and a captured CO2 purity of more than 99.5%. Part of the captured CO2 is used in the food processing industry after passing through the refining system, and the rest is used in industrial production. When the capture device was put into operation, it was the largest flue gas CO2 capture device in the world for coal-fired power plants. 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 above technologies focus on CO2 capture and do not involve conversion and subsequent utilization. The research on CO2 capture and conversion in the published patents is mostly focused on catalysts. Since CO2 capture is a highly exothermic reaction and the conversion process is a highly endothermic reaction, the temperature and heat control of the reaction process is extremely critical. The design of the process and the type of reactor are the key to determining whether the technology is feasible. For highly endothermic and exothermic reactions, the measures usually taken include: using coils to take heat / supplement heat, using direct combustion heating, etc. These methods have some problems in CO2 capture and conversion. When using coils to take heat / supplement heat, on the one hand, as the capture / conversion process switches, the coil absorbs heat for a while and takes heat for a while, which makes it difficult to control; on the other hand, due to the uneven reaction in the catalyst bed, it is difficult to avoid local overheating / overcooling. The direct fuel gas heating method often has the problem of gas overheating after combustion. Taking the commonly used CaO / CaCO3 adsorbent as an example, when the temperature is greater than 850-900°C, the adsorbent will melt and sinter, and 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] CN202110287520.5 discloses a method for reducing carbon monoxide synthesis gas with a high-temperature molten heat carrier, carbon dioxide and carbon powder. The method uses carbon dioxide and carbon powder to absorb the sensible heat and latent heat emitted by the high-temperature heat carrier and heat it to the reduction temperature to instantly reduce it to carbon monoxide high-energy synthesis gas, and uses the high-temperature volumetric heat capacity of carbon dioxide to circulate heat exchange on the granulated high-temperature heat carrier. The whole process is long and has a large pressure drop. The process temperature changes frequently between 50℃ and 1500℃. The drastic temperature change will inevitably bring energy consumption problems; and the longer process will bring about the problem of pressure drop. Usually, the flue gas pressure is low, and the large pressure drop also limits the use of this technology.

[0008] CN201821322948.9 discloses a catalytic reaction device, the lower part of which is provided with a methane + water vapor hydrogen production catalyst to produce hydrogen, the middle part is fed with carbon dioxide, the upper part is provided with a carbon dioxide hydrogenation catalyst, carbon dioxide reacts with hydrogen, and carbon monoxide gas is produced at the top. The main problem with this patent is that, first, carbon dioxide hydrogenation is a strong endothermic reaction, and every 5% reaction of equivalent proportions of CO2 and H2 will cause a temperature drop of about 150°C. Under the type of this reactor, the reaction is actually unsustainable and will soon terminate due to temperature reduction; second, the reactor does not involve carbon capture, but is only a carbon dioxide hydrogenation reactor.

[0009] CN201410202280.4 discloses a method based on manganese and lanthanide metal catalysts to hydrogenate carbon dioxide to generate carbon monoxide by reverse water gas reaction. The main problems of this patent are similar to those of CN201821322948.9. First, the hydrogenation of carbon dioxide is a strong endothermic reaction. Every 5% reaction of equivalent proportions of CO2 and H2 will cause a temperature drop of about 150°C. Under the type of this reactor, the reaction is actually unsustainable and will soon terminate due to the temperature drop; second, this reactor does not involve carbon capture, but is only a carbon dioxide hydrogenation reactor.

[0010] At present, the patents and documents published at home and abroad are concentrated on CO2 capture and CO2 hydrogenation reverse water gas reaction research, while there are few studies on CO2 capture and in-situ conversion. Efficient capture of CO2 at high temperature and in-situ conversion of captured CO2 into synthesis gas products to facilitate the subsequent synthesis of light olefins and other chemical products with high added value can not only fully improve energy utilization and effectively reduce emission reduction costs, but also avoid high energy consumption of capture cooling / conversion heating, solve the high cost of purification and transportation of CO2 after capture, and the safety hazards caused by storage, which is expected to improve the feasibility and economy of the entire CO2 emission reduction process, and is of great significance. Summary of the invention

[0011] In view of the deficiencies of the above-mentioned background technology, the present invention provides a method for capturing and utilizing carbon dioxide based on a fluidized bed, which captures carbon dioxide from high-temperature gas and converts it into synthesis gas (synthesis gas herein and hereinafter refers to CO or a mixture of CO and H2) in situ.

[0012] A method for capturing and utilizing carbon dioxide based on a fluidized bed, characterized by comprising the following steps:

[0013] 1) The carbon dioxide-containing gas enters the adsorption reactor and contacts the catalyst. The carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst and becomes purified gas. The purified gas is discharged after dust removal. The catalyst after adsorbing CO2 enters the conversion reactor;

[0014] 2) The reducing gas enters the conversion reactor after being heated. In the conversion reactor, the reducing gas contacts and reacts with the catalyst after adsorbing CO2. The catalyst after adsorbing CO2 is reduced and then returns to the adsorption reactor. The reaction product gas in the conversion reactor leaves the conversion reactor, first exchanges heat with the circulating gas, and then is cooled, dust-removed, and pressurized by the circulating fan and is divided into two streams, one of which is sent out as the product gas and the other as the circulating gas. The circulating gas exchanges heat with the reaction product gas and is mixed with the reducing gas before entering the conversion reactor for recycling.

[0015] The adsorption reactor and the conversion reactor are both fluidized bed reactors.

[0016] The reducing gas refers to a gas that can react with CO2 to generate a product gas, and the catalyst in the adsorption reactor is a material with carbon dioxide adsorption and catalytic conversion functions.

[0017] The reducing gas is one or a mixture of two or more of H2, CH4 and C2H6, or a mixed gas of an inert gas (such as nitrogen) and one or a mixture of two or more of H2, CH4 and C2H6. When these gases are introduced into the conversion reactor, the following reaction occurs:

[0018] CO2+2H2=CO+H2O+H2 or CO2+H2=CO+H2O

[0019] CO2+CH4=2CO+2H2

[0020] 2CO2+C2H6=4CO+3H2

[0021] The catalyst in the adsorption reactor of the present invention is preferably a material such as CaO, MgO or K2O loaded with one or more active components of Co, Ni and lanthanide metals. The above materials can be formed by extrusion, sintering, etc., and can also be combined with Al2O3, etc. to make a core-shell structure composite.

[0022] The reaction temperature of the adsorption reactor is between room temperature and 800°C, preferably in the range of 600 to 750°C.

[0023] The adsorption reaction of the present invention is an exothermic reaction, and the conversion reaction is an endothermic reaction. There is a certain temperature difference between the two reactors. The amount of catalyst entering the conversion reactor from the adsorption reactor should be sufficient to bring all the adsorption reaction exothermic heat from the adsorption reactor to the catalytic reactor; after regeneration, the corresponding amount of catalyst returns to the adsorption reactor from the conversion reactor.

[0024] The reaction temperature of the conversion reactor is 100-950°C, preferably in the range of 600-800°C.

[0025] After leaving the conversion reactor, the reaction product gas of the present invention is first heat exchanged with the circulating gas, then cooled to room temperature to 400°C, preferably in the temperature range of 100 to 200°C, and then dusted and pressurized by a circulating fan.

[0026] The circulating gas volume of the present invention is preferably in accordance with the above-mentioned calculated value. When the circulating gas volume is less than the above-mentioned calculated value, the heat difference can also be supplemented by setting a heater.

[0027] The outlet gas of the circulating fan described in the present invention is divided into two streams, one of which is sent out as product gas, and the other is used as circulating gas, which is circulated and sent to the conversion reactor for use. The amount of product gas sent out is the amount of synthesis gas generated by the removal of CO2 conversion reaction; the circulating gas volume A (t / h) should be obtained by calculation, and the main related parameters include: conversion reaction endothermic load A1 (kW), reactor heat dissipation loss A2 (kW), total heat release of the catalyst bed in the conversion stage A3 (kJ), switching cycle of the conversion reaction A4 (h), and heat difference A5 (kJ / kg) of the reactor unit inlet and outlet gas. The calculation formula is as follows:

[0028] A=[(A1+A2)*3600-A3 / A4] / A5

[0029] Among them: the endothermic load of the conversion reaction A1 (kW), the heat dissipation loss of the reactor A2 (kW), the total heat release of the catalyst bed in the conversion stage A3 (kJ), the switching cycle of the conversion reaction A4 (h), and the heat difference between the inlet and outlet gas of the reactor unit A5 (kJ / kg).

[0030] In the present invention, the carbon dioxide-containing gas preferably enters the adsorption reactor after being pressurized and heat exchanged, and preferably the carbon dioxide-containing gas enters the adsorption reactor after heat exchange with purified gas.

[0031] In the present invention, the adsorption reactor may preferably be provided with a replenishing facility, and the circulating catalyst may be provided with a degassing tank, a receiving tank, a sliding valve, etc.

[0032] The present invention does not impose any limitation on the type of reactor, and a coaxial fluidized bed or other types of fluidized beds may also be used.

[0033] The present invention can also be equipped with a gas turbine etc. in order to recover the flue gas / synthesis gas pressure energy.

[0034] It is impossible for the present invention to fully and completely describe all implementation forms. Those skilled in the art can make appropriate extensions and modifications based on the present invention.

[0035] Compared with the prior art, the advantages of the present invention are: 1) the carbon dioxide adsorption and conversion of the present invention are completed in situ under similar temperature and pressure conditions, which can not only fully improve the energy utilization rate and effectively reduce the emission reduction cost, 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 caused by storage; 2) the reaction heat is transferred between reactors through catalyst circulation, thereby realizing the in-situ coupled utilization of heat in the adsorption exothermic / conversion endothermic process, and achieving energy saving and emission reduction effects; 3) the temperature of the reactor in the conversion process can be controlled by the gas circulation volume, and at the same time, no new impurity components are introduced, and no additional heating is required in the middle of the reaction; 4) the catalyst is convenient to replenish and unload, and there is no need to worry about problems such as catalyst deactivation in the reactor; 5) the process is simple, easy to operate and maintain, low investment, and small footprint.

[0036] The present invention will be further described in detail below with the accompanying drawings and specific embodiments, but the scope of the present invention is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the process flow of a method for capturing and utilizing carbon dioxide based on a fluidized bed according to the present invention.

[0038] Figure 2 This is an application flow chart of a fluidized bed-based carbon dioxide capture and utilization method of the present invention.

[0039] The reference numerals shown in the figures are:

[0040] 1. Heating furnace, 2. Flue gas waste heat boiler, 3. Flue gas booster / turbine unit, 4. Flue gas-purified gas heat exchanger, 5. Adsorption reactor, 5-1. Reactor riser, 5-2. Cyclone separator, 5-3. Degassing tank for catalyst to be regenerated, 5-4. Inclined pipe to be regenerated, 5-5. Slide valve to be regenerated, 6. Conversion reactor, 6-1. Receiving tank, 6-2. Conversion reactor riser, 6-3. Degassing tank for regenerated catalyst, 6-4. Cyclone separator, 6-5. Regeneration inclined pipe, 6-6. Regeneration slide valve, 6-7 Catalyst balance line, 7. Purified flue gas waste heat boiler, 8. Purified flue gas dust collector, 9. Chimney, 10. Synthesis gas / circulating gas heat exchanger, 11. Synthesis gas waste heat boiler, 12. Synthesis gas dust collector, 13. Circulating fan, 14. Circulating gas heater, 15. Catalyst replenishing facility, 16. Catalyst replenishing tank.

[0041] 101. Flue gas (containing carbon dioxide), 102. Feed gas to adsorption reactor, 103. Exit gas from adsorption reactor, 104. Purified gas, 105. Catalyst.

[0042] 111. Reaction product gas, 112. Catalyst, 113. Product gas, 114. Circulating gas, 115. Hot circulating gas, 116. Reducing gas, 117. Conversion reactor feed gas, 118. New catalyst, 119. Transport air. DETAILED DESCRIPTION

[0043] like Figure 1 As shown, a method for capturing and utilizing carbon dioxide based on a fluidized bed comprises the following steps:

[0044] 1) The carbon dioxide-containing gas is the feed gas 102 of the adsorption reactor. The feed gas 102 of the adsorption reactor enters the adsorption reactor 5 and contacts the catalyst in the adsorption reactor. The carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst. The outlet gas 103 of the adsorption reactor is dedusted by the flue gas precipitator 8 and becomes the purified gas 104 for discharge. The catalyst 105 removed by the flue gas precipitator 8 can be recycled or discharged as solid waste. The catalyst after adsorbing CO2 in the adsorption reactor 5 enters the conversion reactor 6 through the waiting inclined pipe 5-4;

[0045] 2) The reducing gas 116 enters the conversion reactor 6 after being heated. In the conversion reactor 6, the reducing gas 116 contacts and reacts with the catalyst after adsorbing CO2. The catalyst after adsorbing CO2 is reduced and then returns to the adsorption reactor 5 through the regeneration inclined pipe 6-5. The reaction product gas 111 in the conversion reactor 6 leaves the conversion reactor 6, first exchanges heat with the circulating gas 114, and then cools to room temperature to 400°C through the synthesis gas waste heat boiler 11, preferably to a temperature range of 100 to 200°C, and then is separated into two streams after being dedusted by the synthesis gas dust collector 12 and pressurized by the circulation fan 13, one stream is sent out of the device as the product gas 113, and the other stream is sent out as the circulation gas 114. The circulation gas 114 and the reaction product gas 111 are heat exchanged through the synthesis gas / circulation gas heat exchanger 10, and after heat exchange, they are mixed with the reducing gas 116 as the hot circulation gas 115, and then heated by the circulation gas heater 14 as the conversion reactor feed gas 117 and enter the conversion reactor 6;

[0046] The adsorption reactor 5 and the conversion reactor 6 are both fluidized bed reactors.

[0047] The reaction temperature of the adsorption reactor is between room temperature and 800°C, preferably in the range of 600 to 750°C.

[0048] The reaction temperature of the conversion reactor is 100-950°C, preferably in the range of 600-800°C.

[0049] The reducing gas refers to a gas that can react with CO2 to generate a product gas, and the catalyst in the adsorption reactor is a material with carbon dioxide adsorption and catalytic conversion functions.

[0050] The present invention is further described below in conjunction with specific examples. The examples are only implementation methods of the present invention under certain specific conditions and should not be regarded as limiting the protection content of the present invention.

[0051] Example

[0052] For detailed procedures, see Figure 2 .

[0053] 1) The high-temperature flue gas 101 flow rate at the outlet of a heating furnace 1 is 3300m 3 n / h, the flue gas composition is as follows:

[0054] Flue gas composition v％ <![CDATA[CO2]]> 22.98 <![CDATA[H2O]]> 5.9 <![CDATA[N2]]> 64.97 <![CDATA[O2]]> 6.15

[0055] The flue gas temperature is 1200°C and the flue gas pressure is normal pressure. After taking heat from the flue gas waste heat boiler 2, the flue gas is cooled to 200°C, and after being pressurized to 0.6MPaG by the flue gas booster / turbine unit 3, it is heat-exchanged with the adsorption reactor outlet gas 103 to 600°C in the flue gas-purified gas heat exchanger 4, and then enters the reactor riser 5-1 of the adsorption reactor 5 as the adsorption reactor feed gas 102.

[0056] 2). The feed gas 102 of the adsorption reactor is mixed with the regenerated catalyst from the conversion reactor 6 in the reactor riser 5-1, and is separated by settling in the adsorption reactor. The temperature of the catalyst and gas after the reaction rises to 750°C. The flue gas after CO2 removal is removed by the cyclone separator 5-2 to remove the entrained catalyst, and then leaves the adsorption reactor 5 from the top as the adsorption reactor outlet gas 103; the catalyst after CO2 adsorption is degassed by the catalyst degassing tank 5-3, and then enters the conversion reactor 6 through the inclined pipe 5-4. The amount of catalyst from the adsorption reactor 5 to the conversion reactor 6 is 30t / h, and the amount of catalyst is adjusted by the slide valve 5-5 set on the inclined pipe 5-4.

[0057] 3). The outlet gas 103 of the adsorption reactor is heat exchanged with the flue gas at the outlet of the flue gas booster / turbine unit 3 by the flue gas / purified gas heat exchanger 4, and then recovered by the purified flue gas waste heat boiler 7, and cooled to 150°C, and then dedusted by the purified flue gas dust collector 8, and discharged as purified gas 104 through the chimney 9. The catalyst 105 removed by the dust collector 8 can be recycled or discharged as solid waste.

[0058] 4). The catalyst to be regenerated in the adsorption reactor 5 enters the receiving tank 6-1 through the inclined pipe 5-4 to be regenerated, and enters the conversion reactor 6 through the conversion reactor riser 6-2 together with the conversion reactor feed gas 117. In the riser 6-2, the catalyst is regenerated, and gas-solid separation is achieved in the conversion reactor 6. The reaction product gas 111 leaves the conversion reactor 6 after dust removal by the cyclone separator 6-4. The regenerated catalyst is degassed by the regeneration catalyst degassing tank 6-3 and returns to the adsorption reactor 5 along the regeneration inclined pipe 6-5. The flow rate of the regenerated catalyst is controlled by the regeneration slide valve 6-6 arranged on the regeneration inclined pipe 6-5. The conversion reactor 6 is also provided with a catalyst balance line 6-7 for balancing the catalyst level in the reactor.

[0059] 5) The reaction product gas 111 at the outlet of the conversion reactor 6 is heat exchanged by the synthesis gas / circulation gas heat exchanger 10, enters the synthesis gas waste heat boiler 11 to recover heat, and then cools to 150°C, and then passes through the synthesis gas dust collector 12 to remove the catalyst carried, and then the synthesis gas 111 is pressurized to 0.3MPaG by the circulation fan, of which 1810m 3 n / h as product gas 113 for external delivery, 17540m 3 n / h as circulating gas 114, the circulating gas 114 is used as hot circulating gas 115 after heat exchange in the synthesis gas circulating gas heat exchanger 10, and the hot circulating gas 115 is heated by 1210m 3 n / h is mixed with hydrogen as the reducing gas 116, and then heated to 730°C by the circulating gas heater 14, and then returns to the receiving tank 6-1 as the conversion reactor feed gas 117 and enters the conversion reactor 6.

[0060] 6) The catalyst 112 removed by the synthesis gas dust collector 12 can be recycled or discharged as solid waste. The device is also equipped with a catalyst replenishing facility 15, which sends new catalyst 118 into the catalyst replenishing tank 16 through the conveying air 119, and then further sent to the conversion reactor 6.

[0061] 7). The adsorption reactor 5 and the conversion reactor 6 are filled with a CaO-based catalyst, which is formed into a sphere with a microporous structure by sintering CaO and Al2O3, and the surface and pore surface are impregnated with metal catalytic active components such as Co and Ni.

[0062] 8). The expected composition of the product gas 113 is as follows:

[0063]

[0064]

[0065] The flue gas treated by this embodiment can reduce CO2 emissions by 10,000 t / a, while producing 11,910 t / a of synthesis gas as a by-product.

Claims

1. A method for capturing and utilizing carbon dioxide based on a fluidized bed, characterized in that The steps include: 1) The carbon dioxide-containing gas enters the adsorption reactor and contacts the catalyst. The carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst and becomes purified gas. The purified gas is discharged after dust removal. The catalyst after adsorbing CO2 enters the conversion reactor; 2) The reducing gas enters the conversion reactor after being heated. In the conversion reactor, the reducing gas contacts and reacts with the catalyst after adsorbing CO2. The catalyst after adsorbing CO2 is reduced and then returns to the adsorption reactor. The reaction product gas in the conversion reactor leaves the conversion reactor, first exchanges heat with the circulating gas, and then is cooled, dust-removed, and pressurized by a circulating fan and is divided into two streams, one of which is sent out as the product gas and the other as the circulating gas. The circulating gas exchanges heat with the reaction product gas and is mixed with the reducing gas before entering the conversion reactor for recycling; The adsorption reactor and the conversion reactor are both fluidized bed reactors; The reducing gas refers to a gas that can react with CO2 to generate a product gas, and the catalyst in the adsorption reactor is a material with carbon dioxide adsorption and catalytic conversion functions.

2. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1, characterized in that: The reducing gas is one or a mixture of two or more of H2, CH4 and C2H6, or a mixed gas of an inert gas and one or a mixture of two or more of H2, CH4 and C2H6.

3. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 2, characterized in that: The inert gas is nitrogen.

4. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1, characterized in that: The catalyst is CaO, MgO or K2O loaded with one or more active components of Co, Ni and lanthanide metals.

5. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1, characterized in that: The reaction temperature of the adsorption reactor is between room temperature and 800°C, and the reaction temperature of the conversion reactor is between 100°C and 950°C.

6. A method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1 or 5, characterized in that: The reaction temperature of the adsorption reactor is 600-750°C.

7. A method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1 or 5, characterized in that: The reaction temperature of the conversion reactor is 600-800°C.

8. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1, characterized in that: In the step 2), the reaction product gas leaves the conversion reactor, exchanges heat with the circulating gas, is cooled to room temperature to 400° C., is dusted, and is pressurized by a circulating fan before being divided into two streams.

9. A method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1 or 8, characterized in that: In the step 2), the reaction product gas leaves the conversion reactor, exchanges heat with the circulating gas, is cooled to 100-200° C., and is separated into two streams after dust removal and pressure increase by a circulating fan.

10. The method for capturing and utilizing carbon dioxide based on a fluidized bed according to claim 1, characterized in that: In the step 1), the carbon dioxide-containing gas is heat exchanged with the purified gas and then enters the adsorption reactor.

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