A device and method for adsorbing CO2 based on light-heat synergy low-carbon green modified biochar

Abstract

A device and method for CO2 adsorption using photo-thermal synergistic, low-carbon, green biochar modification. This method uses a modification reagent to induce the release of hydroxyl radicals, sulfate radicals, and nitrogen-hydrogen radicals under the synergistic effects of ultraviolet light and temperature, thereby modifying the biochar to produce highly active sites. The modified biochar enters a mixed reaction tower, where it undergoes an adsorption reaction with CO2-containing flue gas from a combustion device. The reacted biochar is separated by a baghouse and then re-entered into a photochemical-thermochemical synergistic modification tower for modification and regeneration. The combustion flue gas, after CO2 separation, is discharged into the atmosphere. The biochar in this device and method is recyclable, and the mixed reaction tower has a high gas-solid mass transfer rate, enabling efficient CO2 adsorption.

Description

Technical Field

[0001] The present invention relates to the field of capturing CO2 in combustion flue gas, and in particular to a device and method for adsorbing CO2 based on light-heat synergistic low-carbon green modified biochar. Background Art

[0002] Since the Industrial Revolution, fossil fuels have provided humanity with an irreplaceable source of energy. This use of fossil fuels inevitably produces greenhouse gases, leading to global warming, rising sea levels, and frequent natural disasters such as floods, droughts, and waterlogging, severely disrupting Earth's ecological balance. Consequently, CO2 capture, utilization, and storage (CCUS) has become a research hotspot in both science and industry, and the active research and development of technologies to reduce CO2 emissions from combustion flue gases is of great strategic significance.

[0003] As of now, the mainstream CO2 capture technologies developed at home and abroad mainly include membrane separation, liquid phase absorption, adsorption, oxygen-enriched combustion, low-temperature separation, chemical looping combustion, hydrothermal and photo / electrochemical methods.

[0004] Membrane separation, with its advantages of simplicity and zero waste generation, is a promising CO2 capture technology. However, it currently faces practical challenges, such as short membrane life and low separation purity. Low-temperature separation offers advantages such as simplicity, environmental friendliness, and suitability for large-scale processing, but suffers from high energy consumption and high-pressure operation, and is primarily used for separating high-concentration CO2. Liquid absorption captures CO2 using various organic solvents, such as alcoholamines, ammonia, and ionic liquids. The absorbent is then activated and regenerated through heating and desorption processes, allowing for CO2 separation. While this method theoretically allows for absorbent recycling, practical applications have been plagued by significant reagent loss and high regeneration energy consumption. Some reagents also corrode equipment. Oxygen-enriched combustion and chemical looping combustion capture and separation primarily rely on novel combustion conditions and methods, but these methods can impact existing combustion equipment and operating conditions, making them unsuitable for treating the vast inventory of traditional combustion equipment, such as boilers and kilns. Emerging carbon reduction technologies such as hydrothermal and photo / electrochemical methods are still in the laboratory exploration stage and are still some distance away from industrial application. The adsorption removal method has attracted active attention from domestic and international academic and engineering communities due to its advantages such as the recyclability of adsorbents and the generation of no waste liquid during the removal process. It has become one of the most promising CO2 capture technologies. The most widely used adsorption separation technology for CO2 is to use activated carbon as an adsorbent to adsorb CO2 from flue gas, and then regenerate the adsorbent and recover CO2 by heating and desorption. However, this technology has shortcomings such as extremely large activated carbon consumption and high application costs, making it impossible to achieve large-scale industrial application. The development of low-cost adsorbents is a key link in the application of this technology.

[0005] Biochar is a pyrolysis product derived from agricultural and forestry waste or organic industrial waste. It has the advantages of a wide source of raw materials, low cost and environmental friendliness. However, raw biochar that has not been activated and modified usually has the disadvantages of small specific surface area and poor active sites, making it difficult to obtain satisfactory CO2 adsorption capacity. In order to improve the CO2 adsorption performance of biochar, domestic and foreign scholars have used various physical and chemical activation / modification methods to improve the pore structure of biochar or induce active sites on the surface of biochar to produce a special high-activity surface. Activating biochar with high temperature or microwave in a special atmosphere can effectively improve the pore structure and specific surface area of ​​biochar, but the improvement of the crucial active sites is very limited. At present, most research work focuses on using various chemical methods to improve the surface active sites of biochar, and the most studied ideas mainly include: (1) using organic alcohol ammonium, ammonia or ionic liquid reagents for activation modification; (2) using various metal or non-metal elements for doping modification; (3) using strong acid or strong oxidant for oxidation modification. Although these activation modification methods can effectively increase the specific surface area or surface active sites of biochar, they all suffer from high costs, poor treatment effects, secondary pollution, or high energy consumption. Therefore, actively exploring and developing new, efficient, and green biochar modification methods is of great scientific and practical significance. Summary of the Invention

[0006] In order to overcome the above-mentioned development bottleneck, the present invention discloses a device and method for adsorbing CO2 based on light-heat synergistic low-carbon green modified biochar. The biochar used in the present invention is widely available, low-cost, and can be recycled, which can effectively solve the high cost problem in other methods. Secondly, the photochemical-thermochemical synergistic modification tower in the device, the gas-solid nozzle array inside it can effectively increase the rate of activation and modification of biochar; the suspended combustion flue gas nozzle at the top of the mixed reaction tower and the bottom combustion flue gas nozzle at the bottom can accelerate the gas-solid mass transfer rate, thereby improving the effect of capturing CO2. At the same time, the present invention uses dry removal technology, no wastewater or waste liquid is generated, and there is no risk of reagent leakage, so there is no secondary pollution.

[0007] The present invention is achieved through the following technical solutions:

[0008] A device for adsorbing CO2 based on light-heat synergistic low-carbon green modified biochar, characterized by: comprising a biochar feeding device, a modification reagent container, a photochemical-thermochemical synergistic modification tower, a modified biochar quantitative feeder, a bag separator, a mixing reaction tower, a combustion flue gas thermostat, and a combustion device;

[0009] The biochar feeding device is connected to the upper part of the photochemical-thermochemical synergistic modification tower, and the modification reagent container is connected to the lower part of the photochemical-thermochemical synergistic modification tower. The photochemical-thermochemical synergistic modification tower is provided with a gas-solid nozzle array at the bottom, a plurality of gravity heat pipes and ultraviolet lamps suspended on the inner wall of the top; a circulation bypass is provided on the side of the photochemical-thermochemical synergistic modification tower, one end of which is connected to the gas-solid nozzle array and the other end of which is introduced into the photochemical-thermochemical synergistic modification tower from the top; a first fan is provided on the circulation bypass, and the circulation direction provided by the circulation bypass is a top-to-bottom circulation flow; the outlet of the photochemical-thermochemical synergistic modification tower is connected to the mixed reaction tower through the modified biochar quantitative feeder and the second fan;

[0010] The mixed reaction tower is provided with a suspended combustion flue gas nozzle suspended at the top and a bottom combustion flue gas nozzle located at the bottom. The flue gas in the combustion device is temperature-regulated by the combustion flue gas thermostat and is divided into two pipes, which are respectively connected to the suspended combustion flue gas nozzle and the bottom combustion flue gas nozzle. The outlet of the mixed reaction tower is connected to the bag separator.

[0011] In the above solution, the bag separator is provided with a first outlet and a second outlet, the first outlet is connected to the photochemical-thermochemical synergistic modification tower, the second outlet leads to the atmosphere, and a fourth fan is provided on the pipeline of the second outlet.

[0012] In the above scheme, the photochemical-thermochemical synergistic modification tower is a modification reactor with a rectangular or circular cross-section, and the ultraviolet lamp tubes, gravity heat pipes, and nozzles in the gas-solid nozzle array are arranged in a rectangular array or a circular array.

[0013] In the above scheme, the ultraviolet lamp tubes and gravity heat pipes are both hoisted on the top of the photochemical-thermochemical synergistic modification tower, extending in the up and down directions and arranged alternately between the two; the ultraviolet lamp tubes and gravity heat pipes are arranged at equal intervals, and the spacing between adjacent ultraviolet lamp tubes is 5cm-80cm. The gravity heat pipe is arranged at the center of the ultraviolet lamp tube, and the center lines of the ultraviolet lamp tube and the gravity heat pipe are parallel to the axial center line of the photochemical-thermochemical synergistic modification tower. The effective wavelength of ultraviolet light is 150nm-290nm, the length of the ultraviolet lamp tube is 40cm-450cm, and the length of the gravity heat pipe remains the same as that of the ultraviolet lamp tube; the spacing between each nozzle in the gas-solid nozzle array ranges from 5cm to 30cm.

[0014] In the above scheme, the spacing between the bottom combustion flue gas nozzles ranges from 10cm to 60cm, the spacing between the suspended combustion flue gas nozzles is twice the spacing of the bottom combustion flue gas nozzles, the length of the vertical suspension pipe of the suspended combustion flue gas nozzle in the mixing reaction tower ranges from 100cm to 1500cm, and the combustion device is connected to the combustion flue gas thermostat through a third fan.

[0015] In the above scheme, the CO2 adsorption method of the device is characterized by comprising the following steps:

[0016] (1) Using flue gas waste heat and ultraviolet light to synergistically induce a modification reagent containing hydrogen peroxide (H2O2), persulfate (S2O8 2- ), ammonia (NH3·H2O), and one or more of the following: the modified reagent generates hydroxyl radicals (·OH), sulfate radicals (SO4 - ) and / or nitrogen-hydrogen radicals (·NH), which attack the surface of biochar to produce active sites, and complete the activation modification of biochar in the photochemical-thermochemical synergistic modification tower. The specific process is expressed as follows:

[0017]

[0018]

[0019]

[0020] n·OH+Biochar→Biochar-active sites (4)

[0021] nSO4· - +Biochar→Biochar-active sites (5)

[0022] nNH·+Biochar→Biochar-active sites (6)

[0023] (2) The modified biochar enters the mixed reaction tower and undergoes adsorption reaction with the flue gas containing CO2 from the combustion device in the mixed reaction tower. The active sites are used to adsorb and capture CO2 in the flue gas. The CO2 is desorbed by heating and recovered for storage or utilization. The specific process is expressed as follows:

[0024]

[0025]

[0026] The biochar that loses its active sites after adsorption is passed into a bag separator for separation, while the combustion flue gas after CO2 removal is discharged into the atmosphere.

[0027] In the above-mentioned method for adsorbing CO2, the biochar separated in the bag separator is re-introduced into the photochemical-thermochemical synergistic modification tower through the first outlet for recycling, and then modified and regenerated through equations (1)-(6) to regain the ability to adsorb CO2.

[0028] In the above-mentioned method for adsorbing CO2, the time for modifying the biochar in the photochemical-thermochemical synergistic modification tower is 10 min-180 min according to the different loss rates of the biochar during use, the modification temperature of the biochar needs to be maintained at 30°C-150°C, and the circulation rate of the circulation bypass is 20m 3 / h-600m 3 / h, the UV radiation intensity is 30μW / cm 2 -300μW / cm 2 The thermal radiation intensity of the gravity heat pipe is 50W / m 2 -600 W / m 2 .

[0029] In the above-mentioned method of adsorbing CO2, the reaction temperature in the mixed reaction tower needs to be maintained at 25°C-140°C, the inlet concentration of CO2 in the flue gas from the combustion device is not more than 60%, the residence time of biochar in the mixed reaction tower for removing CO2 is 10s-180s, the amount of combustion flue gas entering the bottom combustion flue gas nozzle accounts for 20%-30% of the total combustion flue gas volume, and the amount of combustion flue gas entering the suspended combustion flue gas nozzle accounts for 70%-80% of the total combustion flue gas volume.

[0030] In the above-mentioned method for adsorbing CO2, the biochar used is biochar obtained by cracking agricultural straw, or biochar obtained by cracking urban sludge, fruit peels and industrial organic waste; the agricultural straw is one or more of rice straw, wheat straw, cotton stalk, corn stalk, rice husk and corn cob; the amount of biochar added is 0.4kg-16kg per cubic meter of the volume of the photochemical-thermochemical synergistic modification tower, and the particle size of the biochar needs to be maintained at 0.02μm-1.2μm.

[0031] In the above-mentioned method for adsorbing CO2, the concentration of the modified reagent hydrogen peroxide (H2O2) needs to be maintained at 0.02mol / L-8.0mol / L, and the modified reagent persulfate (S2O8 2- ) needs to be maintained at a concentration of 0.01mol / L-5.0mol / L, the addition concentration of the modification reagent ammonia water (NH3·H2O) needs to be maintained at 0.01mol / L-5.0mol / L, and the addition amount of the modification reagent is 100g-5000g per cubic meter of the volume of the photochemical-thermochemical synergistic modification tower.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] First, the present invention uses cheap agricultural straw or organic waste to crack and prepare biochar, and adopts a technical solution of real-time modification of biochar to achieve the recycling of biochar. Compared with catalytic method and membrane separation method, the technology of the present invention has extremely low cost and green process. It has more advantages than other adsorption methods and is a low-cost CO2 adsorption device and method.

[0034] Secondly, the present invention describes a device and method for adsorbing CO2 based on light-heat synergistic low-carbon green modified biochar. The CO2 adsorption process is to use biochar to adsorb CO2 in combustion flue gas in a mixed reaction tower. The mixed reaction tower has an extremely strong gas-solid mass transfer rate, which is an order of magnitude higher than the traditional fixed bed and fluidized bed mass transfer rate, which can greatly improve the CO2 adsorption efficiency and reduce the reactor volume.

[0035] Thirdly, the dry removal technology used in the present invention does not produce any wastewater or waste liquid in the entire process, and there is no leakage of reagents. It avoids the treatment difficulties of large amounts of solid waste generated after the deactivation of membrane materials and catalysts in membrane separation and catalytic methods. Therefore, there is no secondary pollution, which is in line with the current green and sustainable development strategy proposed by the country.

[0036] Finally, the present invention utilizes flue gas waste heat and ultraviolet light to synergistically induce highly active free radicals to modify biochar, and adopts a low-energy mixed reaction tower to adsorb CO2. Since the ultraviolet radiation intensity is very low, and the gravity heat pipe quickly absorbs the waste heat in the flue gas and then radiates heat on its surface to form a light-heat synergistic activation effect with ultraviolet light, the energy consumption of this method is more than 3 orders of magnitude lower than that of low-temperature separation technology. Therefore, the energy consumption required for the operation of the entire device is extremely low, which has the beneficial effects of energy saving and low carbon. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is an overall schematic diagram of the photochemical-thermochemical synergistic modification tower modified biochar CO2 adsorption device.

[0038] Figure 2 It is a schematic diagram of the rectangular arrangement of the UV lamp, gravity heat pipe and nozzle in the photochemical-thermochemical synergistic modification tower.

[0039] Figure 3 It is a schematic diagram of the circular arrangement of the UV lamp, gravity heat pipe and nozzle in the photochemical-thermochemical synergistic modification tower.

[0040] Figure 4 It is a schematic diagram of the rectangular arrangement of the suspended combustion flue gas nozzles and the bottom combustion flue gas nozzles in the mixing reaction tower.

[0041] Figure 5 It is a schematic diagram of the circular arrangement of the suspended combustion flue gas nozzles and the bottom combustion flue gas nozzles in the mixing reaction tower.

[0042] In the figure: 1. Biochar feeding device, 2. First fan, 3. Circulation bypass, 4. Gas-solid nozzle array, 5. Modification reagent container, 6. Photochemical-thermochemical synergistic modification tower, 7. Gravity heat pipe, 8. UV lamp, 9. Modified biochar quantitative feeder, 10. Bag separator, 10-1. First outlet, 10-2. Second outlet, 11. Suspended combustion flue gas nozzle, 12. Mixing reaction tower, 13. Bottom combustion flue gas nozzle, 14. Combustion flue gas thermostat, 15. Combustion device, 16. Second fan, 17. Third fan, 18. Fourth fan. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below with reference to the specific embodiments of the drawings, but the protection scope of the present invention is not limited thereto.

[0044] like Figure 1 As shown, the device for adsorbing CO2 based on light-heat synergistic low-carbon green modified biochar according to the present invention includes a biochar feeding device 1, a modification reagent container 5, a photochemical-thermochemical synergistic modification tower 6, a modified biochar quantitative feeder 9, a bag separator 10, a mixing reaction tower 12, a combustion flue gas thermostat 14, and a combustion device 15.

[0045] The biochar feeding device 1 is connected to the upper part of the photochemical-thermochemical synergistic modification tower 6 and is used to transport biochar into the photochemical-thermochemical synergistic modification tower 6; the modification reagent container 5 is connected to the lower part of the photochemical-thermochemical synergistic modification tower 6 and provides the modification reagent to the photochemical-thermochemical synergistic modification tower 6;

[0046] The photochemical-thermochemical synergistic modification tower 6 is provided with a gas-solid nozzle array 4 at the bottom, a plurality of gravity heat pipes 7 and ultraviolet lamps 8 suspended on the top inner wall. Figure 2 or Figure 3 As shown in the figure, the spacing between each nozzle in the gas-solid nozzle array 4 is in the range of 5cm-30cm, the ultraviolet lamp tubes 8 and the gravity heat pipes 7 are arranged at equal intervals, the spacing between the ultraviolet lamp tubes 8 is 5cm-80cm, the gravity heat pipe 7 is arranged at the center of the ultraviolet lamp tube 8, the center line of the ultraviolet lamp tube 8 and the gravity heat pipe 7 is parallel to the axial center line of the photochemical-thermochemical synergistic modification tower 6, the effective wavelength of ultraviolet light is 150nm-290nm, the length of the ultraviolet lamp tube 8 is 40cm-450cm, and the length of the gravity heat pipe 7 remains the same as that of the ultraviolet lamp tube 8.

[0047] A circulation bypass 3 is provided on the side of the photochemical-thermochemical synergistic modification tower 6, one end of which is connected to the gas-solid nozzle array 4 and the other end of which is introduced into the photochemical-thermochemical synergistic modification tower 6 from the top. A first fan 2 is provided on the circulation bypass 3 to accelerate the flow rate in the circulation bypass pipe. The circulation direction provided by the circulation bypass 3 is a top-down circulation flow. Based on this circulation direction, the modification reagent and biochar are continuously sprayed upward from the gas-solid nozzle array 4, further accelerating the efficiency of biochar activation and modification.

[0048] Figure 1 The outlet of the photochemical-thermochemical synergistic modification tower 6 is connected to the mixed reaction tower 12 through the modified biochar quantitative feeder 9 and the second fan 16, and the activated modified biochar enters the mixed reaction tower 12. The second fan 16 is used to accelerate the speed of the activated modified biochar gas-solid mixture entering the modified biochar quantitative feeder 9;

[0049] The mixing reaction tower 12 is provided with a suspended combustion flue gas nozzle 11 suspended at the top and a bottom combustion flue gas nozzle 13 located at the bottom. The spacing between the bottom combustion flue gas nozzles 13 ranges from 10 cm to 60 cm. The spacing between the suspended combustion flue gas nozzles 11 is twice the spacing between the bottom combustion flue gas nozzles 13. The length of the vertical suspension pipe of the suspended combustion flue gas nozzle 11 in the mixing reaction tower 12 ranges from 100 cm to 1500 cm.

[0050] exist Figure 1 In the embodiment, the combustion device 15 is connected to the combustion flue gas temperature regulator 14 through the third fan 17, and the third fan 17 is used to accelerate the flue gas rate; the flue gas in the combustion device 15 is temperature-controlled by the combustion flue gas temperature regulator 14 and is divided into two pipes, which are respectively connected to the suspended combustion flue gas nozzle 11 and the bottom combustion flue gas nozzle 13;

[0051] The outlet of the mixed reaction tower 12 is connected to the bag separator 10, and the bag separator 10 is provided with a first outlet 10-1 and a second outlet 10-2. The first outlet 10-1 is connected to the photochemical-thermochemical synergistic modification tower 6. After the used biochar is separated in the bag separator 10, it is re-sent into the photochemical-thermochemical synergistic modification tower 6 through the first outlet 10-1 for reactivation and modification; the second outlet 10-2 leads to the atmosphere. A fourth fan 18 is provided on the pipeline of the second outlet 10-2. The flue gas treated with CO2 is accelerated to the atmosphere through the fourth fan 18.

[0052] like Figure 4 or Figure 5As shown, the bottom combustion flue gas nozzles 13 arranged in a rectangular or circular shape in the mixing reaction tower 12 spray the gas-solid mixture upward, while the suspended combustion flue gas nozzles 11 located at the top of the mixing reaction tower 12 can spray the gas-solid mixture laterally. The two work together to form a mixed or cross-spraying diffusion gas-solid mixture, further enhancing and improving the gas-solid mixing and mass transfer diffusion reaction rate.

[0053] The CO2 adsorption method based on the above device includes the following steps:

[0054] (1) Using flue gas waste heat and ultraviolet light to synergistically induce a modification reagent containing hydrogen peroxide (H2O2), persulfate (S2O8 2- ), ammonia (NH3·H2O), and one or more of the following: the modified reagent generates hydroxyl radicals (·OH), sulfate radicals (SO4 - ) and / or nitrogen-hydrogen radicals (·NH), which attack the surface of biochar to generate active sites, and the activation modification of biochar is completed in the photochemical-thermochemical synergistic modification tower 6. The specific process is expressed as follows:

[0055]

[0056]

[0057]

[0058] n·OH+Biochar→Biochar-active sites (4)

[0059] nSO4· - +Biochar→Biochar-active sites (5)

[0060] nNH·+Biochar→Biochar-active sites (6)

[0061] (2) The modified biochar enters the mixed reaction tower 12 and undergoes an adsorption reaction with the flue gas containing CO2 from the combustion device 15 in the mixed reaction tower 12. The active sites are used to adsorb and capture the CO2 in the flue gas. The CO2 is desorbed by heating and recovered for storage or utilization. The specific process is expressed as follows:

[0062]

[0063]

[0064] The biochar that has lost its active sites after adsorption is passed into the bag separator 10 for separation, while the combustion flue gas after the removal of CO2 is discharged into the atmosphere.

[0065] In the method for adsorbing CO2, the biochar separated in the bag separator 10 is re-introduced into the photochemical-thermochemical synergistic modification tower 6 through the first outlet 10-1 for recycling, and then modified and regenerated through equations (1)-(6) to regain the ability to adsorb CO2.

[0066] In the method for adsorbing CO2, the time for modifying the biochar in the photochemical-thermochemical synergistic modification tower 6 is 10 min-180 min according to the different loss rates of the biochar during use, the modification temperature of the biochar needs to be maintained at 30°C-150°C, and the circulation rate of the circulation bypass 3 is 20 m / s. 3 / h-600m 3 / h, the UV radiation intensity is 30μW / cm 2 -300μW / cm 2 The thermal radiation intensity of the gravity heat pipe is 50W / m 2 -600W / m 2 .

[0067] In this method of adsorbing CO2, the reaction temperature in the mixed reaction tower 12 needs to be maintained at 25°C-140°C, the inlet concentration of CO2 in the flue gas from the combustion device 15 is not more than 60%, the residence time of biochar in the mixed reaction tower 12 for removing CO2 is 10s-180s, the amount of combustion flue gas entering the bottom combustion flue gas nozzle 13 accounts for 20%-30% of the total combustion flue gas volume, and the amount of combustion flue gas entering the suspended combustion flue gas nozzle 11 accounts for 70%-80% of the total combustion flue gas volume.

[0068] In this method for adsorbing CO2, the biochar used is biochar obtained by cracking agricultural straw, or biochar obtained by cracking urban sludge, fruit peels and industrial organic waste; the agricultural straw is one or more of rice straw, wheat straw, cotton straw, corn straw, rice husk and corn cob; the amount of biochar added is 0.4kg-16kg per cubic meter of the volume of the photochemical-thermochemical synergistic modification tower 6, and the particle size of the biochar needs to be maintained at 0.02μm-1.2μm.

[0069] In the CO2 adsorption method, the concentration of the modified reagent hydrogen peroxide (H2O2) needs to be maintained at 0.02mol / L-8.0mol / L, and the modified reagent persulfate (S2O8 2-) needs to be maintained at a concentration of 0.01 mol / L-5.0 mol / L, the concentration of the modification reagent ammonia (NH3·H2O) needs to be maintained at 0.01 mol / L-5.0 mol / L, and the dosage of the modification reagent is 100 g-5000 g per cubic meter of the volume of the photochemical-thermochemical synergistic modification tower 6.

[0070] Example 1:

[0071] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 20μW / cm 2 and 254 nm, the addition concentration of the modifying reagent NH3 was 0.05 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.05 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition amount of the modifying reagent NH3 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 120 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg / cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 35.7%.

[0072] Example 2:

[0073] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 40μW / cm 2and 254 nm, the addition concentration of the modifying reagent NH3 was 0.05 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.05 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition amount of the modifying reagent NH3 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 120 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg / cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 42.2%.

[0074] Example 3:

[0075] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 40μW / cm 2 and 254 nm, the addition concentration of the modifying reagent NH3 was 0.1 mol / L, the addition concentration of the modifying reagent H2O2 was 0.2 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.1 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition amount of the modifying reagent NH3 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 120 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 56.8%.

[0076] Example 4:

[0077] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 60μW / cm 2and 254 nm, the addition concentration of the modifying reagent NH3 was 0.1 mol / L, the addition concentration of the modifying reagent H2O2 was 0.2 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.1 mol / L, the addition concentration of the modifying reagent H2O2 was 0.1 mol / L, the addition amount of the modifying reagent NH3 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 120 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 64.9%.

[0078] Example 5:

[0079] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 60μW / cm 2 and 254 nm, the addition concentration of the modifying reagent NH3 was 0.2 mol / L, the addition concentration of the modifying reagent H2O2 was 0.3 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.2 mol / L, and the addition concentration of the modifying reagent H2O2 was 0.1 mol / L. The addition amount of the modifying reagent NH3 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 120 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 60 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 76.0%.

[0080] Example 6:

[0081] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 80μW / cm 2and 254 nm, the addition concentration of the modifying reagent NH3 was 0.2 mol / L, the addition concentration of the modifying reagent H2O2 was 0.3 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.2 mol / L, and the addition concentration of the modifying reagent H2O2 was 0.1 mol / L. The addition amount of the modifying reagent NH3 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 180 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 0.5 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 84.5%.

[0082] Example 7:

[0083] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 80μW / cm 2 and 254 nm, the addition concentration of the modifying reagent NH3 was 0.2 mol / L, the addition concentration of the modifying reagent H2O2 was 0.3 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.2 mol / L, and the addition concentration of the modifying reagent H2O2 was 0.1 mol / L. The addition amount of the modifying reagent NH3 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 180 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 1.0 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 89.6%.

[0084] Example 8:

[0085] The modification temperature of the photochemical-thermochemical synergistic modification tower is 55°C, and the thermal radiation intensity of the gravity heat pipe is 100W / m 2 , the UV radiation intensity and wavelength are 80μW / cm 2and 254 nm, the addition concentration of the modifying reagent NH3 was 0.2 mol / L, the addition concentration of the modifying reagent H2O2 was 0.3 mol / L, the addition concentration of the modifying reagent Na2S2O8 was 0.2 mol / L, and the addition concentration of the modifying reagent H2O2 was 0.1 mol / L. The addition amount of the modifying reagent NH3 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower, the addition amount of the modifying reagent Na2S2O8 was 180 g per cubic meter of the photochemical-thermochemical synergistic modification tower, and the addition amount of the modifying reagent H2O2 was 100 g per cubic meter of the photochemical-thermochemical synergistic modification tower. The biochar was microwave steam-activated rice straw charcoal, the biochar concentration was 1.0 kg per cubic meter of the mixed reaction tower, and the operating temperature for CO2 adsorption in the mixed reaction tower was 25°C. The concentration of CO2 in the simulated combustion flue gas was 10%. The test results on a small experimental system are: the adsorption removal efficiency of CO2 in combustion flue gas is 92.8%.

[0086] In summary, among the eight embodiments described above, embodiment 8 has the best simultaneous removal effect and can be used as a preferred solution.

[0087] The examples described are embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A CO2 adsorption method based on light-heat synergistic low-carbon green modified biochar, characterized in that: The method is implemented based on a device for light-heat synergistic low-carbon green modified biochar adsorption of CO2, wherein the CO2 adsorption device comprises a biochar feeding device (1), a modification reagent container (5), a photochemical-thermochemical synergistic modification tower (6), a modified biochar quantitative feeder (9), a bag separator (10), a mixing reaction tower (12), a combustion flue gas temperature regulator (14), and a combustion device (15); The biochar feeding device (1) is connected to the upper part of the photochemical-thermochemical synergistic modification tower (6), and the modification reagent container (5) is connected to the lower part of the photochemical-thermochemical synergistic modification tower (6). The photochemical-thermochemical synergistic modification tower (6) is provided with a gas-solid nozzle array (4) at the bottom, a plurality of gravity heat pipes (7) and ultraviolet lamps (8) suspended on the inner wall of the top, and the ultraviolet lamps (8) and gravity heat pipes (7) are extended in the up-down direction and are arranged alternately. A circulation bypass (3) is provided on the side of the thermochemical synergistic modification tower (6), one end of which is connected to the gas-solid nozzle array (4) and the other end of which is introduced into the photochemical-thermochemical synergistic modification tower (6) from the top; a first fan (2) is provided on the circulation bypass (3), and the circulation direction provided by the circulation bypass (3) is a circulation flow from top to bottom; the outlet of the photochemical-thermochemical synergistic modification tower (6) is connected to the mixing reaction tower (12) through the modified biochar quantitative feeder (9) and the second fan (16); The mixing reaction tower (12) is provided with a suspended combustion flue gas nozzle (11) mounted on the top and a bottom combustion flue gas nozzle (13) located at the bottom. The flue gas in the combustion device (15) is temperature-controlled by a combustion flue gas temperature regulator (14) and then divided into two pipes, which are respectively connected to the suspended combustion flue gas nozzle (11) and the bottom combustion flue gas nozzle (13). The outlet of the mixing reaction tower (12) is connected to the bag separator (10). The CO2 adsorption method comprises the following steps: (1) Using flue gas waste heat and ultraviolet light to synergistically induce a modification reagent, wherein the modification reagent contains hydrogen peroxide, persulfate, and ammonia water. After being induced by ultraviolet light, the modification reagent generates active free radicals including hydroxyl radicals, sulfate radicals, and nitrogen-hydrogen radicals. The active free radicals attack the surface of biochar to generate active sites. The activation modification of biochar is completed in the photochemical-thermochemical synergistic modification tower (6). The specific process is represented by equations (1)-(6): (1) (2) (3) (4) (5) (6) Among them, Biochar is biochar, active sites are active sites; (2) The modified biochar enters the mixed reaction tower (12) and undergoes an adsorption reaction with the flue gas containing CO2 from the combustion device (15) in the mixed reaction tower (12). The CO2 in the flue gas is adsorbed and captured by the active sites, and the CO2 is desorbed by heating and recovered for storage or utilization. The specific process is expressed as follows: (7) (8) The biochar that loses its active sites after adsorption is passed into a bag separator (10) for separation, while the combustion flue gas after CO2 removal is discharged into the atmosphere.

2. The CO2 adsorption method according to claim 1, characterized in that: The biochar separated in the bag separator (10) is re-introduced into the photochemical-thermochemical synergistic modification tower (6) through the first outlet (10-1) for recycling, and then modified and regenerated according to equations (1)-(6) to regain the ability to adsorb CO2.

3. The CO2 adsorption method according to claim 1, characterized in that: According to the different loss rates of biochar during use, the time for biochar modification in the photochemical-thermochemical synergistic modification tower (6) is 10 min-180 min, the modification temperature of biochar needs to be maintained at 30°C-150°C, and the circulation rate of the circulation bypass (3) is 20m 3 / h - 600 m 3 / h, the UV radiation intensity is 30μW / cm 2 - 300μW / cm 2 The thermal radiation intensity of the gravity heat pipe is 50W / m 2 -600 W / m 2 .

4. The CO2 adsorption method according to claim 1, characterized in that: The reaction temperature in the mixed reaction tower (12) needs to be maintained at 25°C-140°C, the inlet concentration of CO2 in the flue gas from the combustion device (15) is not greater than 60%, the residence time of the biochar in the mixed reaction tower (12) for removing CO2 is 10s-180s, the amount of combustion flue gas entering the bottom combustion flue gas nozzle (13) accounts for 20%-30% of the total combustion flue gas volume, and the amount of combustion flue gas entering the suspended combustion flue gas nozzle (11) accounts for 70%-80% of the total combustion flue gas volume.

5. The CO2 adsorption method according to claim 1, characterized in that: The biochar used is biochar obtained by cracking agricultural straw, or biochar obtained by cracking urban sludge, fruit shells and industrial organic waste; the agricultural straw is one or more of rice straw, wheat straw, cotton straw, corn straw, rice husk and corn cob; the amount of biochar added is 0.4kg-16kg per cubic meter of the volume of the photochemical-thermochemical synergistic modification tower (6), and the particle size of the biochar needs to be maintained at 0.02μm-1.2μm.

6. The CO2 adsorption method according to claim 1, characterized in that: The addition concentration of the modifying reagent hydrogen peroxide needs to be maintained at 0.02 mol / L-8.0 mol / L, the addition concentration of the modifying reagent persulfate needs to be maintained at 0.01 mol / L-5.0 mol / L, and the addition concentration of the modifying reagent ammonia needs to be maintained at 0.01 mol / L-5.0 mol / L. The addition amount of the modifying reagent is 100g-5000g per cubic meter according to the volume of the photochemical-thermochemical synergistic modification tower (6).

7. The CO2 adsorption method according to claim 1, characterized in that: The bag separator (10) is provided with a first outlet (10-1) and a second outlet (10-2), the first outlet (10-1) is connected to the photochemical-thermochemical synergistic modification tower (6), the second outlet (10-2) leads to the atmosphere, and a fourth fan (18) is provided on the pipeline of the second outlet (10-2).

8. The CO2 adsorption method according to claim 1, characterized in that: The photochemical-thermochemical synergistic modification tower (6) is a modification reactor with a rectangular or circular cross-section. The ultraviolet lamp tube (8), the gravity heat pipe (7), and the nozzles in the gas-solid nozzle array (4) are arranged in a rectangular array or a circular array. The ultraviolet lamp tube (8) and the gravity heat pipe (7) are arranged at equal intervals, and the spacing between adjacent ultraviolet lamp tubes (8) is 5 cm to 80 cm. The gravity heat pipe (7) is arranged at the center of the ultraviolet lamp tube (8). The center lines of the ultraviolet lamp tube (8) and the gravity heat pipe (7) are parallel to the axial center line of the photochemical-thermochemical synergistic modification tower (6). The effective wavelength of ultraviolet light is 150 nm to 290 nm. The length of the ultraviolet lamp tube (8) is 40 cm to 450 cm. The length of the gravity heat pipe (7) is the same as that of the ultraviolet lamp tube (8). The spacing between adjacent nozzles in the gas-solid nozzle array (4) is 5 cm to 30 cm.

9. The CO2 adsorption method according to claim 1, characterized in that: The spacing between the bottom combustion flue gas nozzles (13) ranges from 10 cm to 60 cm, the spacing between the suspended combustion flue gas nozzles (11) is twice the spacing between the bottom combustion flue gas nozzles (13), the length of the vertical suspension pipe of the suspended combustion flue gas nozzles (11) in the mixing reaction tower (12) ranges from 100 cm to 1500 cm, and the combustion device (15) is connected to the combustion flue gas temperature regulator (14) through the third fan (17).

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