Carbon dioxide trapping and utilizing method and device and application thereof

Abstract

The invention discloses a method and a device for capturing and utilizing carbon dioxide and application of the method and the device. The method and the device are used for capturing CO2 from high-temperature gas containing carbon dioxide and converting the CO2 into synthesis gas in situ. The carbon dioxide-containing gas enters the adsorption reactor from an inlet of the adsorption reactor and passes through a catalyst bed layer of the adsorption reactor, carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst bed layer, and purified gas leaves the adsorption reactor from an outlet of the adsorption reactor; reducing gas and circulating gas are mixed to serve as mixed circulating gas, the mixed circulating gas exchanges heat with synthesis gas at an outlet of the conversion reactor, is heated by a heater, enters the conversion reactor from an inlet of the conversion reactor and passes through a catalyst bed layer of the conversion reactor, and carbon dioxide adsorbed on the catalyst bed layer of the conversion reactor is converted into synthesis gas. After leaving from an outlet of the conversion reactor, the synthesis gas firstly exchanges heat with mixed circulating gas, is cooled by a cooler and boosted by a circulating compressor, and is divided into two streams, one stream is taken as product gas to be sent out, and the other stream is taken as circulating gas to be mixed with reducing gas to be sent to the conversion reactor; feeding and subsequent procedures of the adsorption reactor and the conversion reactor are periodically switched. By means of the device, the energy utilization rate can be fully increased, the emission reduction cost is effectively reduced, and heat in-situ coupling utilization in the adsorption heat release / conversion heat absorption process can be achieved.

Description

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 and application thereof for capturing carbon dioxide from gas and converting and utilizing it in situ, while realizing comprehensive utilization of heat absorption and release in the process. 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 CO2 capture, utilization and storage, and each industry has formed a variety of CO2 capture, utilization and storage technical methods 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] Three companies in the world 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 project 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, using fluidized beds, moving beds, etc. These methods have some problems in CO2 capture and conversion. On the one hand, with the switching of the capture / conversion process, 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 heating method of fuel gas 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 the core equipment is similar to a fluidized bed, with a large pressure drop. The process temperature changes frequently between 50℃ and 1500℃, and the drastic temperature change will inevitably bring energy consumption problems; and the longer process will bring pressure drop problems. 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] The purpose of the present invention is to address the deficiencies of the above-mentioned prior art and to provide a method and device for capturing and utilizing carbon dioxide from high-temperature gas containing carbon dioxide and converting it in situ into synthesis gas (synthesis gas herein and hereinafter refers to CO or a mixture of CO and H2), as well as its application, while realizing the comprehensive utilization of the heat absorbed and released in this process.

[0012] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0013] A method for capturing and utilizing carbon dioxide, characterized in that the method comprises the following steps:

[0014] 1) The carbon dioxide-containing gas enters the adsorption reactor from the inlet of the adsorption reactor, passes through the catalyst bed of the adsorption reactor, and the carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst bed, and the purified gas leaves the adsorption reactor from the outlet of the adsorption reactor;

[0015] 2) The reducing gas is mixed with the circulating gas as the mixed circulating gas, and the mixed circulating gas exchanges heat with the synthesis gas at the outlet of the conversion reactor, and then enters the conversion reactor from the inlet of the conversion reactor after being heated by the heater, and is converted and regenerated through the catalyst bed of the conversion reactor. The carbon dioxide adsorbed on the catalyst bed of the conversion reactor is converted into synthesis gas. After the synthesis gas leaves the outlet of the conversion reactor, it first exchanges heat with the mixed circulating gas, and then is cooled by the cooler and pressurized by the circulating compressor, and then is divided into two streams, one of which is sent out as the product gas, and the other is sent as the circulating gas after being mixed with the reducing gas to the conversion reactor;

[0016] 3) The adsorption reactor and the conversion reactor are regularly switched for feeding and subsequent processes.

[0017] The present invention provides a method for capturing and utilizing carbon dioxide, and its further technical feature is that the adsorption reaction temperature is between room temperature and 800°C, preferably in the temperature range of 600 to 750°C.

[0018] The present invention provides a method for capturing and utilizing carbon dioxide, and its further technical feature is that the conversion reaction temperature is 100-950°C, preferably in the temperature range of 600-800°C.

[0019] The present invention provides a method for capturing and utilizing carbon dioxide, and its further technical feature is that the adsorption reactor and the conversion reactor are first purged with an inert gas before switching the feed, and then the subsequent steps are repeated alternately in sequence.

[0020] The present invention also provides a carbon dioxide capture and utilization device, characterized in that: the carbon dioxide capture and utilization device comprises an adsorption reactor, a conversion reactor, a heater, a heat exchanger, a cooler and a circulation compressor, the adsorption reactor is provided with a purified gas outlet and a carbon dioxide-containing gas inlet, the conversion reactor is provided with a conversion reaction gas inlet and a synthesis gas outlet, the synthesis gas outlet is connected to the heat exchanger, the cooler and the circulation compressor in sequence, the circulation compressor outlet is connected to the product gas pipeline and the circulation gas pipeline respectively, the circulation gas pipeline and the reducing gas pipeline are connected to the heater inlet through the heat exchanger after merging, and the heater outlet is connected to the conversion reaction gas inlet; the adsorption reactor and the conversion reactor are the same, and different names are used only for the convenience of description, the adsorption reactor and the conversion reactor are both fixed bed reactors, both include a catalyst bed and an air inlet distributor, the carbon dioxide-containing gas inlet and the conversion reaction gas inlet are both provided with an air inlet distributor, the catalyst bed is filled with catalytic materials and heat storage bodies, the catalyst bed is a single-layer arrangement or a multi-layer arrangement, and the adsorption reactor and the conversion reactor are both arranged with one or more reactors.

[0021] The present invention also provides an application of the above-mentioned carbon dioxide capture and utilization method to the high-temperature flue gas at the outlet of a heating furnace, which is characterized in that the high-temperature flue gas at the outlet of the heating furnace is subjected to heat extraction by a waste heat boiler, and then is pressurized by a booster, and then heat exchanged with the purified gas described in the above-mentioned carbon dioxide capture and utilization method, and is used as the carbon dioxide-containing gas described in the above-mentioned carbon dioxide capture and utilization method, and is processed using the above-mentioned carbon dioxide capture and utilization method.

[0022] The adsorption reactor and the conversion reactor described in the present invention 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 of which are single or multiple, and the catalyst bed is filled with a catalyst. The catalyst includes a catalytic material and a heat storage body. The catalytic material refers to a material with dual functions of carbon dioxide adsorption and catalytic conversion, such as a CaO material loaded with one or more active components such as Co, Ni and lanthanide metals; the heat storage body refers to a material with heat storage function, such as corundum, ceramics, mullite, zircon or cordierite, etc. The above-mentioned catalytic material and heat storage body can be made into one by sintering, core-shell structure composite, etc., or can be uniformly mixed and filled in a certain ratio or filled in layers in the catalyst bed.

[0023] The reducing gas in the present invention refers to a gas that can react with CO2 to generate a product gas, such as H2, CH4, C2H6, etc., specifically one or a mixture of two or more of these gases, or a mixed gas of an inert gas (such as nitrogen, etc.) and one or more of these gases. When these gases are introduced separately, the following reactions will occur:

[0024] CO2+2H2=CO+H2O+H2 or CO2+H2=CO+H2O

[0025] CO2+CH4=2CO+2H2

[0026] 2CO2+C2H6=4CO+3H2

[0027] When the adsorption reactor and the conversion reactor of the present invention respectively use a plurality of reactors, they can be switched for operation simultaneously or independently switched for operation one by one.

[0028] In the catalyst of the present invention, the catalytic material with adsorption / catalytic function and the heat storage body are compositely composed in a certain proportion. During adsorption, the reaction is an exothermic reaction, and the heat storage body is used to store heat to control the bed temperature; the higher the proportion of the heat storage body, the lower the bed temperature rise, but the effective space utilization rate of the bed is also lower, and vice versa. The filling method of the catalytic material and the heat storage body in the catalyst bed is: the catalytic material and the heat storage body are uniformly mixed in a certain proportion and then filled in the catalyst bed; or the catalytic material and the heat storage body are filled layer by layer in the catalyst bed, that is, a layer of catalytic material and a layer of heat storage body are filled in layers. The ratio of the catalytic material and the heat storage body determines the temperature rise of the gas before and after adsorption. When there is no heat storage body, the flue gas with a common CO2 content of 5 to 20v%, the highest temperature rise of the purified gas after adsorption can reach more than 600°C compared with the carbon dioxide-containing gas before adsorption. The higher the proportion of the heat storage body, the lower the temperature rise of the purified gas after adsorption. The specific ratio of the catalytic material and the heat storage body can be determined based on comprehensive considerations such as the design temperature of the reactor, the inlet carbon dioxide-containing gas temperature, and the maximum tolerance temperature of the catalytic material. Typically, the recommended volume ratio of catalyst material to thermal storage body ranges from 5:1 to 1:10.

[0029] The adsorption reactor and conversion reactor of the present invention have a catalyst bed layer 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:

[0030] A=A1xA3 / A2

[0031] Where: A1 represents the amount of carbon dioxide to be adsorbed;

[0032] A2 represents the adsorption capacity of the material;

[0033] A3 expresses the design switching time.

[0034] The amount of the heat storage body is determined by the inlet temperature of the carbon dioxide-containing gas, the gas composition and specific heat, the heat release of the adsorbed carbon dioxide reaction, the amount and specific heat of the catalytic material, the specific heat of the heat storage body, the reactor heat loss, the final temperature of the reactor bed that is desired to be controlled, etc.

[0035] The catalyst bed of the present invention is located in the reactor and can be filled in a single stage or in layers.

[0036] The adsorption reactor and conversion reactor of the present invention can adopt the type of 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.

[0037] 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. Usually, the outlet temperature of the cooler is controlled at room temperature to 400°C, preferably in the temperature range of 100 to 200°C.

[0038] The outlet gas of the circulating compressor of the present invention is divided into two streams, one of which is sent out as product gas, and the other is sent out as circulating gas to the conversion reactor for use. The amount of product gas sent out is controlled according to the decarbonization amount or system pressure; the circulating gas volume B (t / h) should be obtained by calculation, and the main related parameters include: the endothermic load of the conversion reaction B1 (kW), the heat loss of the conversion reactor B2 (kW), the total heat release of the catalyst bed in the conversion stage B3 (kJ), the switching cycle of the conversion reaction B4 (h), and the heat difference B5 (kJ / kg) of the unit inlet and outlet gas of the reactor.

[0039] The specific calculation formula is as follows:

[0040] B=[(B1+B2)*3600-B3 / B4] / B5

[0041] Where: B1 represents the heat released by the heat storage body;

[0042] B2 represents the heat loss of the reactor;

[0043] B3 represents the heat absorbed during the conversion process;

[0044] B4 represents the total heat brought in by the inlet reducing gas;

[0045] B5 represents the total heat carried away by the outlet synthesis gas.

[0046] The circulating gas volume of the present invention is preferably in accordance with the above calculated value. When the circulating gas volume is less than the above calculated value, the bed layer in the reactor should be arranged in sections, and heaters should be installed between the bed layers to make up for the heat difference.

[0047] The adsorption reactor and the conversion reactor of the present invention periodically switch the feed, and the reactor switching time can be designed according to the material adsorption capacity to perform timing control; the operation mode of the reactor can also be switched online according to the CO2 content of the gas after decarbonization. The above switching can be achieved by a valve on the pipeline outside the reactor.

[0048] The present invention is applicable to the treatment of carbon dioxide-containing gas (such as high-temperature flue gas from a heating furnace, etc.) to capture CO2 from the carbon dioxide-containing gas and convert it into synthesis gas in situ. When the temperature of the gas to be treated is too high, the temperature can be reduced to a suitable temperature range by recovering heat or the like; when the temperature is too low, the temperature can be raised to a suitable temperature range by heating or the like.

[0049] 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 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 heat of the adsorption exothermic / conversion endothermic process can be coupled in situ 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.

[0050] 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

[0051] Figure 1 It is a simple flow chart of a carbon dioxide capture and utilization method of the present invention;

[0052] Figure 2 The present invention is a catalyst bed type in which a catalytic material with adsorption / catalytic function and a heat storage body are uniformly mixed;

[0053] Figure 3 The present invention is a catalyst bed type in which a material with adsorption / catalytic function and a heat storage body are layered and filled;

[0054] Figure 4 The invention discloses a complete treatment process of sulfur-containing flue gas from the outlet of a heating furnace.

[0055] The reference numerals shown in the figures are:

[0056] 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 Circulation gas, 8. Mixed circulation gas, 9. Conversion reactor inlet gas, 11. Adsorption reactor, 12. Conversion reactor, 13. Catalyst bed, 13-1. Catalyst bed type in which materials with adsorption / catalytic functions and heat storage bodies are uniformly mixed, 13-2. Catalyst bed type in which materials with adsorption / catalytic functions and heat storage bodies are layered, 14. Heat exchanger, 15. Cooler, 16. Circulation 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 valve. DETAILED DESCRIPTION

[0057] like Figure 1 As shown, Figure 1 It is a simple flow chart of a method for capturing and utilizing carbon dioxide of the present invention.

[0058] Figure 2 The invention relates to a catalyst bed type in which a catalytic material with adsorption / catalytic function and a heat storage body are uniformly mixed.

[0059] Figure 3 The invention relates to a catalyst bed type in which materials with adsorption / catalytic functions and heat storage bodies are layered and filled.

[0060] like Figure 4 The figure shows a high-temperature flue gas treatment process at the outlet of a heating furnace according to the present invention.

[0061] 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.

[0062] Embodiment 1:

[0063] With high temperature flue gas containing carbon dioxide 330m 3 Take n / h as an example, the flue gas composition is as follows:

[0064] Flue gas composition v％ <![CDATA[CO2]]> 22.98 <![CDATA[H2O]]> 5.9 <![CDATA[N2]]> 64.97 <![CDATA[O2]]> 6.15

[0065] Flue gas temperature is 640℃, flue gas pressure is 10kPaG. For detailed process, please refer to Figure 1 .

[0066] 1). 640℃ high temperature flue gas 1 enters adsorption reactor 11 from the bottom through control valve 121, and control valve 122 is closed at this time. After high temperature flue gas 1 passes through catalyst bed 13, CO2 in flue gas is adsorbed and removed, and the purified gas 3 after decarbonization is heated to 727℃ and discharged from the top of adsorption reactor 11 through control valve 123, and control valve 124 is closed at this time.

[0067] 2). The adsorption reactor 11 and the conversion reactor 12 are equipped with a CaO-based catalyst bed. The catalyst core is a Φ3 Al2O3 sphere 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 active components such as Co and Ni for catalyzing the reaction of CO2 and H2. The total catalyst bed filling volume is 20m 3 .

[0068] 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, circulating compressor 16 pressurizes cooled synthesis gas 6 from 30kPaG to 100kPaG, and 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 n / h are mixed and enter the heat exchanger 14, where the temperature is raised to 618°C. The mixed circulating gas 8 is then heated to 730°C by the heater 17, and then enters the conversion reactor 12 through the control valve 125 as the conversion reactor inlet gas 9. At this time, the 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 top control valve 127 of the conversion reactor 12.

[0069] The expected composition of product gas 7-1 is as follows:

[0070] Element Composition, v% CO 24.35 <![CDATA[H2]]> 50.01 <![CDATA[CO2]]> 1.28 <![CDATA[H2O]]> 24.35 total 100

[0071] 4) After 2 hours, the reactor is purged with hot nitrogen, the control valves 121, 123, 125, 127 are closed, the control valves 122, 124, 126, 128 are opened, and the feeds of the two reactors 11 and 12 are exchanged. Then the cycle is repeated in sequence according to the timing control.

[0072] The flue gas treated by this embodiment can reduce CO2 emissions by 1187t / a, and produce 1416t / a of synthesis gas as a by-product.

[0073] Embodiment 2:

[0074] The flue gas at the outlet of a heating furnace 111 is 100000m 3 Take n / h as an example, the flue gas composition is as follows:

[0075] Flue gas composition v％ <![CDATA[CO2]]> 15 <![CDATA[H2O]]> 10 <![CDATA[N2]]> 69.997 <![CDATA[O2]]> 5 SOx 0.003

[0076] For detailed procedures, see Figure 4 .

[0077] 1). Control valves 121, 123, 125, 127 are open, and control valves 122, 124, 126, 128 are closed. The flue gas temperature at the outlet of the heating furnace 111 is 1100°C, and the flue gas pressure is 5kPaG. After the waste heat boiler 112 takes heat, the flue gas temperature drops to 200°C, and then it is pressurized to 0.1MPaG by the booster 113, and then desulfurized by the desulfurization reactor 114, and then heat-exchanged with the purified gas 3 to 600°C, and then it enters the adsorption reactor 11 as the feed high-temperature flue gas 1 of the adsorption reactor 11.

[0078] 2). The 600℃ high temperature flue gas 1 enters the adsorption reactor 11 from the bottom through the control valve 121. After passing through the catalyst bed 13, the CO2 in the flue gas is adsorbed and removed. The decarbonized purified gas 3 is heated to 740℃ and discharged from the top of the adsorption reactor 11 through the control valve 123. After heat exchange in the flue gas heat exchanger 115 and heat recovery in the purified flue gas waste heat boiler 116, it is discharged externally.

[0079] 3). The catalyst bed of the adsorption reactor 11 and the conversion reactor 12 is filled with Φ3 alkaline earth metal oxide microporous structure spheres, the surface of which is impregnated with CoO active groups and Φ3 Al2O3 spheres for heat storage; the total filling volume is 1600m 3 , the two types of spheres each occupy half.

[0080] 3) 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, circulating compressor 16 pressurizes cooled synthesis gas 6 from 30kPaG to 100kPaG, and the pressurized synthesis gas 7 is divided into two paths, of which the product gas 7-1 has a flow rate of 60000m 3 n / h, sent out as product; circulating gas 7-2 flow rate 840000m 3 n / h, and methane 15000m3 as reducing gas 23 After being mixed with n / h, it is used as the 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 then 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.

[0081] The expected composition of product gas 7-1 is as follows:

[0082] Element Composition, v% CO 48 <![CDATA[H2]]> 48 <![CDATA[CO2]]> 1 <![CDATA[CH4]]> 3 total 100

[0083] 4) After 2 hours, the reactor is purged with hot nitrogen, the control valves 121, 123, 125, 127 are closed, the control valves 122, 124, 126, 128 are opened, and the feeds of the adsorption reactor 11 and the conversion reactor 12 are interchanged. Then the cycle is carried out in sequence according to the time sequence control.

[0084] The flue gas treated by this embodiment can reduce CO2 emissions by 27 t / h, while producing 36 t / h of synthesis gas as a by-product.

Claims

1. A method for capturing and utilizing carbon dioxide, characterized in that: The method comprises the following steps: 1) The carbon dioxide-containing gas enters the adsorption reactor from the inlet of the adsorption reactor, passes through the catalyst bed of the adsorption reactor, and the carbon dioxide in the carbon dioxide-containing gas is adsorbed by the catalyst bed, and the purified gas leaves the adsorption reactor from the outlet of the adsorption reactor; 2) The reducing gas is mixed with the circulating gas as the mixed circulating gas, and the mixed circulating gas exchanges heat with the synthesis gas at the outlet of the conversion reactor, and then enters the conversion reactor from the inlet of the conversion reactor after being heated by the heater, and is converted and regenerated through the catalyst bed of the conversion reactor. The carbon dioxide adsorbed on the catalyst bed of the conversion reactor is converted into synthesis gas. After the synthesis gas leaves the outlet of the conversion reactor, it first exchanges heat with the mixed circulating gas, and then is cooled by the cooler and pressurized by the circulating compressor, and then is divided into two streams, one of which is sent out as the product gas, and the other is sent as the circulating gas after being mixed with the reducing gas to the conversion reactor; 3) Regularly switch the feed and subsequent processes between the adsorption reactor and the conversion reactor; The catalyst beds of the adsorption reactor and the conversion reactor are both filled with catalytic materials and heat storage bodies. The catalytic materials refer to materials having dual functions of carbon dioxide adsorption and catalytic conversion, and the heat storage bodies refer to materials having heat storage functions.

2. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The adsorption reaction temperature is between room temperature and 800°C; the conversion reaction temperature is between 100°C and 950°C.

3. A method for capturing and utilizing carbon dioxide according to claim 1 or 2, characterized in that: The adsorption reaction temperature is 600-750°C; the conversion reaction temperature is 600-800°C.

4. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The reducing gas refers to a gas that can react with CO2 to generate CO, specifically refers to one or a mixture of two or more of these gases, or a mixed gas of an inert gas and one or more of these gases.

5. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The adsorption reactor and the conversion reactor are first purged with an inert gas before switching the feed, and then the subsequent steps are repeated alternately in sequence.

6. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The outlet temperature of the cooler is between room temperature and 400°C.

7. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The catalytic material is a CaO material loaded with one or more than two active components of Co, Ni and lanthanide metals, and the heat storage body is corundum, ceramic, mullite, zircon or cordierite.

8. A method for capturing and utilizing carbon dioxide according to claim 4, characterized in that: The gases that can react with CO2 to generate CO are H2, CH4 and C2H6.

9. A method for capturing and utilizing carbon dioxide according to claim 1, characterized in that: The catalytic material and the heat storage body are uniformly mixed and then loaded into the catalyst bed; or the catalytic material and the heat storage body are loaded layer by layer in the catalyst bed, that is, a layer of catalytic material and a layer of heat storage body are loaded in layers.

10. A carbon dioxide capture and utilization device, used in the carbon dioxide capture and utilization method according to claim 1, characterized in that: The carbon dioxide capture and utilization device comprises an adsorption reactor, a conversion reactor, a heater, a heat exchanger, a cooler and a circulation compressor. The adsorption reactor is provided with an adsorption reactor outlet and an adsorption reactor inlet, and the conversion reactor is provided with a conversion reactor inlet and a conversion reactor outlet. The conversion reactor outlet is connected to the heat exchanger, the cooler and the circulation compressor in sequence, and the circulation compressor outlet is connected to the product gas pipeline and the circulation gas pipeline respectively. After the circulation gas pipeline and the reducing gas pipeline are merged, they are connected to the heater inlet through the heat exchanger, and the heater outlet is connected to the conversion reactor inlet. The adsorption reactor and the conversion reactor are the same. Both the adsorption reactor and the conversion reactor are fixed bed reactors and both include a catalyst bed. Air inlet distributors are provided at the adsorption reactor inlet and the conversion reactor inlet. Catalytic materials and heat storage bodies are filled in the catalyst bed. The catalyst bed is a single-layer arrangement or a multi-layer arrangement. The adsorption reactor and the conversion reactor are both arranged with one or more reactors.

11. A carbon dioxide capture and utilization device according to claim 10, characterized in that: When multiple adsorption reactors and conversion reactors are used, they can be switched for operation simultaneously or independently one by one.

12. The carbon dioxide capture and utilization device according to claim 10, characterized in that: Both the adsorption reactor and the conversion reactor adopt the bottom-in and top-out, top-in and bottom-out, side-in and side-out, periphery-in and middle-out, or middle-in and periphery-out type.

13. The carbon dioxide capture and utilization device according to claim 10, characterized in that: Heaters are provided between the catalyst beds of the adsorption reactor and the conversion reactor.

14. The application of the carbon dioxide capture and utilization method of claim 1 to high-temperature flue gas at the outlet of a heating furnace is characterized in that: The high-temperature flue gas at the outlet of the heating furnace is heated by the waste heat boiler and then pressurized by the booster. It is then heat exchanged with the purified gas described in claim 1 to be used as the carbon dioxide-containing gas described in claim 1 and is processed using the carbon dioxide capture and utilization method described in claim 1.

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