A direct air capture CO2 system and process combining solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption.

Abstract

This invention discloses a direct air CO2 capture system and process combining solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption, comprising a solid-phase CO2 concentration section and a liquid-phase CO2 absorption-desorption section. This invention addresses the direct air CO2 capture process by using a honeycomb rotary concentrator loaded with a solid-phase CO2 adsorbent to achieve rapid adsorption of low-concentration CO2 from the air. The CO2 adsorbed by the hot nitrogen is then desorbed by a low-temperature rotary concentrator, increasing the CO2 concentration in the nitrogen to 0.5-10%. The nitrogen then enters a packed absorption tower sprayed with a chemical absorbent, where CO2 is captured again. The purified nitrogen is then recycled back to the rotary concentrator to desorb the adsorbed CO2, thus completing the adsorption-desorption cycle. The absorbent after CO2 absorption enters a desorption tower for desorption. The desorbed CO2, after cooling and washing, yields CO2 with a purity of over 99%. This invention overcomes the problems of low efficiency, high energy consumption, and unstable adsorbents in traditional DAC capture processes, achieving efficient direct air CO2 capture and obtaining high-purity CO2 products.

Description

Technical Field

[0001] This invention belongs to the field of gas capture, specifically relating to a direct air capture CO2 system and process that combines solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption. Background Technology

[0002] Direct Air Capture (DAC), as one of the core pathways of negative emission technologies, breaks through the dependence of traditional carbon capture technologies on large-scale stationary emission sources. It does not require coupling with industrial facilities or power plants and can directly separate CO2 from the atmosphere or distributed emission sources at any location, significantly improving the flexibility of carbon capture scenarios. Furthermore, the DAC process avoids the corrosive effects of high-concentration acidic gases (such as SO2 and NOx) and heavy metal pollutants on materials used in traditional flue gas treatment.

[0003] Liquid-phase chemical adsorption-desorption (CHD) is a mature method widely used in carbon capture due to its high adsorption rate, high adsorption capacity, and relatively low desorption temperature. However, it also faces significant limitations when applied to direct air CO2 capture. Because the concentration of CO2 in the atmosphere is extremely low, a large amount of air needs to be processed to capture sufficient CO2, leading to high solvent evaporation losses and absorbent degradation. Furthermore, the low CO2 loading rate of the absorbent significantly increases the energy consumption for CO2 desorption, resulting in a substantial increase in the unit cost of CO2 capture.

[0004] Current mainstream direct air capture of CO2 employs an absorption route using calcium hydroxide alkaline solution. This route relies on a high-temperature (>900℃) thermal regeneration process. The stringent desorption conditions not only result in significant heat energy consumption but also lead to performance degradation of the hygroscopic absorbent and water loss. Temperature-swing / pressure-swing adsorption (TSA) methods based on solid adsorbents suffer from similar drawbacks. They are limited by key challenges such as airflow resistance and pressure drop in the adsorption unit, insufficient desorption motive force, and competitive adsorption of water molecules. Furthermore, the power consumption of the fan generated by air flowing through the dense adsorption layer, the thermodynamic losses during the high-temperature / vacuum regeneration process, the additional energy consumption from water molecule desorption, and the condensation that clogs the adsorption channels all contribute to increased system operating costs. In addition, current solid-phase absorbent capture technologies struggle to obtain high-purity CO2, limiting the direct resource utilization of CO2 at the downstream end.

[0005] Currently, the CO2 capture cost of commercial direct air capture projects is generally higher than $600 per ton. Such a high economic cost significantly restricts the large-scale application of this technology. Therefore, it is urgent to reduce costs and increase efficiency through new process integration optimization and technology upgrades. Summary of the Invention

[0006] To address the aforementioned technical problems in existing technologies, this invention provides a relay-style direct air CO2 capture technology that combines solid-phase honeycomb rotor adsorbent concentration and liquid-phase chemical absorbent adsorption-desorption, leveraging the advantages of high throughput and high adsorption rate for low-concentration CO2 in solid-phase adsorbents, as well as the advantages of fast CO2 desorption rate and low energy consumption in liquid-phase absorbents. First, a honeycomb rotor loaded with solid-phase CO2 adsorbent rapidly adsorbs low-concentration CO2 from the air. Then, a hot nitrogen low-temperature desorption rotor desorbs the adsorbed CO2, increasing the desorbed CO2 concentration to 0.5%-10%. The 0.5%-10% CO2 then enters a liquid-phase chemical absorption spray tower for capture. The purified nitrogen is recycled back to the honeycomb rotor desorption zone, while the high-CO2-load liquid absorbent enters the desorption tower, where the chemically absorbed CO2 is released under thermal action, resulting in CO2 gas with a concentration of over 99%. This invention achieves low-energy, rapid, and continuous capture of air CO2 through staged relay capture and concentration.

[0007] The specific technical solution adopted in this invention is as follows:

[0008] A direct air CO2 capture system combining solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption, comprising a solid-phase rotary concentrator system and a liquid-phase chemical adsorption-desorption system;

[0009] The solid-phase rotary concentrator system includes an adsorption rotary device, an air fan, a regeneration gas heater, and an inlet and outlet gas heat exchanger. The adsorption rotary device is equipped with a honeycomb rotary adsorbent, which includes a honeycomb rotary wheel and a solid adsorbent loaded on the honeycomb rotary wheel. It includes an adsorption zone, a cold blowing zone, and a desorption zone. When the adsorption rotary device rotates, the solid adsorbent inside it continuously circulates from the adsorption zone to the regeneration and desorption zone, then to the cold blowing zone, and then back to the adsorption zone.

[0010] The air fan is connected to the adsorption zone by a pipeline;

[0011] The circulating carrier gas is blown into the inlet of the cold blowing zone after passing through the cold channel of the inlet and outlet gas heat exchanger. The outlet of the cold blowing zone is connected to the inlet of the desorption zone through a pipeline via a regeneration gas heater. The outlet of the desorption zone discharges enriched gas rich in CO2. After passing through the hot channel of the inlet and outlet gas heat exchanger, the enriched gas is sent to the liquid phase chemical adsorption and desorption system to recover the CO2 in it, and the desorbed CO2 circulating carrier gas is reused to form a circulating loop of the circulating carrier gas.

[0012] Furthermore, the system of the present invention also includes an air filter, wherein the air delivered by the air blower is filtered through the air filter to remove solid impurities before being blown into the adsorption zone.

[0013] In this invention, the solid-phase CO2 enrichment section involves pressurizing air via an air fan and bringing it into contact with the honeycomb rotor adsorbent in the adsorption zone. Carbon dioxide is adsorbed by the solid adsorbent loaded on the honeycomb rotor, and the carbon dioxide-free exhaust gas is discharged back into the atmosphere. The carbon dioxide-loaded honeycomb rotor adsorbent rotates to the desorption zone under the drive of the rotor, where it comes into contact with regeneration gas nitrogen heated by a regeneration gas heater. Under thermal action, carbon dioxide desorbs from the solid adsorbent, and the desorbed carbon dioxide mixes with the nitrogen to form enriched gas. After desorption, the honeycomb rotor adsorbent rotates to the cooling zone under the drive of the rotor and is cooled by cooling gas. It then rotates back to the adsorption zone, repeating the above process.

[0014] Furthermore, the liquid-phase chemical adsorption-desorption system includes a concentrated gas blower, a spray-packed absorption tower, a buffer tank, a rich liquid pump, and a rich liquid regeneration system. The hot channel outlet of the inlet and outlet gas heat exchanger is connected to the lower air inlet of the spray-packed absorption tower via a pipeline through the concentrated gas blower. Liquid absorbent is introduced into the upper liquid inlet of the spray-packed absorption tower. The circulating carrier gas for desorbing CO2 is discharged from the gas outlet at the top of the spray-packed absorption tower and introduced into the cold channel of the gas heat exchanger. The CO2-rich absorbent solution at the bottom of the spray-packed absorption tower is first discharged into the buffer tank, and then pumped out by the rich liquid pump and sent to the rich liquid regeneration system for heating and desorbing CO2, so that the desorbed CO2 liquid absorbent can be reused, forming a circulation loop for the liquid absorbent.

[0015] Furthermore, the rich liquor regeneration system includes a rich-lean liquor heat exchanger, a lean liquor cooler, a desorption tower, a bottom pump, a flash tank, a lean liquor pump, and a compressor. The outlet of the rich liquor pump is connected to the upper inlet of the desorption tower via a pipeline through the cold channel of the rich-lean liquor heat exchanger. A bottom reboiler is installed at the bottom of the desorption tower. The bottom outlet of the desorption tower is connected to the middle inlet of the flash tank via the bottom pump. The top outlet of the flash tank is connected to the lower inlet of the desorption tower via a pipeline through the compressor. Under the operation of the compressor, the flash tank is kept under negative pressure to facilitate flash evaporation. The bottom outlet of the flash tank is connected to the upper inlet of the spray packing absorption tower via a pipeline through the lean liquor pump, the hot channel of the rich-lean liquor heat exchanger, and the lean liquor cooler.

[0016] In this invention, the liquid-phase CO2 absorption and desorption section involves enriched nitrogen gas being pressurized by a enriched gas blower and introduced into a spray-packed absorption tower. It then comes into countercurrent contact with the liquid-phase absorbent to complete carbon dioxide absorption. The nitrogen gas, freed from carbon dioxide, is discharged from the top of the spray-packed absorption tower and returned to the adsorption rotor as regeneration gas. After countercurrent contact between the liquid-phase absorbent and the enriched gas, the CO2-rich absorbent is pumped into a lean-rich-lean heat exchanger. After heat exchange, it enters the top of the desorption tower, where it is heated by the reboiler at the bottom. As the temperature rises, CO2 desorbs and is discharged from the top of the desorption tower. After desorption, the CO2 load in the rich CO2 absorbent decreases, forming a lean CO2 absorbent. This lean absorbent is pumped into a lean-rich-lean heat exchanger and, after heat exchange, enters the top of the spray-packed absorption tower, where it again comes into countercurrent contact with the enriched nitrogen gas, repeating the above process.

[0017] The hot gas desorption solid-phase adsorbent scheme of the present invention avoids the problem of decreased adsorption performance caused by adsorbent pore blockage due to traditional steam desorption, and reduces the energy consumption of heating for adsorbent dehydration.

[0018] In this invention, air is concentrated from 400 ppm to 0.5%-10% by a solid-phase adsorption rotor. The concentrated gas with a carbon dioxide concentration of 0.5%-10% is captured by liquid-phase chemical absorption, and a desorption tower desorbs more than 99% high-purity CO2.

[0019] After being discharged from the spray-packed absorption tower, the regenerated nitrogen gas first enters the inlet and outlet gas heat exchanger to exchange heat with the enriched gas, and then enters the rotor cooling zone to exchange heat, which greatly reduces the load on the regenerated gas heater.

[0020] A direct air capture process for CO2 using a combination of solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption, wherein a honeycomb rotary adsorbent is disposed within the adsorption rotary device, the honeycomb rotary adsorbent comprising a honeycomb rotary wheel and a solid adsorbent loaded on the honeycomb rotary wheel, and the adsorption rotary device comprising an adsorption zone, a cold blowing zone, and a desorption zone, the method comprising the following steps:

[0021] S1: An air blower draws in ambient air and delivers it. First, solid impurities are removed by an air filter. At room temperature, the air enters the adsorption zone and comes into full contact with the solid adsorbent inside. CO2 in the air is efficiently adsorbed onto the solid adsorbent. The purified air after CO2 removal is discharged into the atmosphere. The solid adsorbent in the adsorption zone after adsorbing CO2 rotates with the rotor to the desorption zone.

[0022] S2: The recirculating carrier gas for CO2 desorption from the liquid phase chemical adsorption-desorption system first undergoes heat exchange through the cold channel of the inlet and outlet gas heat exchanger, and then is blown into the cold blowing zone to cool the solid adsorbent inside. It is then heated to 180-220°C by the regeneration gas heater to form high-temperature regeneration gas. The regeneration gas is then introduced into the desorption zone to desorb CO2 from the solid adsorbent inside. The CO2 in the regeneration gas is concentrated to form concentrated gas. After heat exchange through the hot channel of the inlet and outlet gas heat exchanger, the concentrated gas enters the liquid phase chemical adsorption-desorption system for chemical absorption and desorption. The CO2 in the concentrated gas is removed by chemical absorption and reformed into the recirculating carrier gas, which is then reused in the cold channel of the inlet and outlet gas heat exchanger, forming a loop for CO2 concentration and desorption of the recirculating carrier gas.

[0023] Further, the circulating carrier gas is N2, the CO2 concentration of the enriched gas in step S2 is 0.5%-10%, preferably 1%-5%, the temperature of the circulating carrier gas after heat exchange through the cold channel of the inlet and outlet gas heat exchanger is 60-75℃, and the temperature of the enriched gas after heat exchange through the hot channel of the inlet and outlet gas heat exchanger is 45-55℃.

[0024] Furthermore, the chemical absorption and desorption operations include the following steps:

[0025] 1) The enriched gas enters the lower part of the spray packing absorption tower under the pressure of the enriched gas blower, while the liquid absorbent is introduced from the upper part of the spray packing absorption tower. The gas and liquid phases come into countercurrent contact, and the CO2 in the enriched gas is absorbed by the liquid absorbent. The circulating carrier gas after removing CO2 is discharged from the top of the absorption tower and is reused.

[0026] 2) The CO2-rich absorbent at the bottom of the absorber is first discharged into a buffer tank, then pumped out by the rich liquid pump and sent to the cold channel of the lean-rich liquid heat exchanger for heat exchange and temperature rise. After that, it enters the desorption tower for heating and desorption. At the same time, the absorbent at the bottom of the desorption tower is pumped into the flash tank by the bottom pump. The negative pressure in the flash tank is maintained by the compressor. The CO2-rich desorbed gas after flashing is reintroduced into the lower part of the desorption tower. The desorbed gas is discharged from the top of the desorption tower and collected.

[0027] 3) The lean CO2 absorbent at the bottom of the flash tank is pumped by the lean liquid pump to the hot channel of the lean-rich liquid heat exchanger for heat exchange and cooling. Then it is further cooled to 30-45℃ by the lean liquid cooler and re-enters the upper part of the spray packing absorption tower to contact the enriched gas in a countercurrent flow to complete the absorption and desorption cycle.

[0028] Further, in step 1), the CO2 concentration of the circulating carrier gas discharged from the top of the absorption tower is below 0.5%; in step 2), the CO2-rich absorbent is heated to 75-85°C by a lean-rich liquid heat exchanger and then sent into the desorption tower for heating and desorption at a temperature of 90-100°C; in step 3), the CO2-lean absorbent is cooled to 50-60°C by a lean-rich liquid heat exchanger.

[0029] Furthermore, the loading of the solid adsorbent on the honeycomb rotor is 20%-50%, and the solid adsorbent is one of the amine-functionalized solid-phase adsorbents, such as amine-functionalized alkaline polymer porous resins and amine-functionalized ionic liquid porous materials. Alternatively, the solid adsorbent is one or more of the non-amine-functionalized solid-phase adsorbents, such as zeolites, activated carbon, metal-organic frameworks (MOFs), mesoporous silica, and carbon nanomaterials.

[0030] Furthermore, the liquid-phase absorbent is one or more organic amine compounds whose active ingredient is monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, 2-amino-2-methyl-1-propanol, triethylenetetramine, etc. Alternatively, the liquid-phase absorbent is an amino-functionalized ionic liquid whose active ingredient is a quaternary ammonium nitrogen heterocyclic ionic liquid, etc.

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1) The honeycomb solid-phase rotor concentration replaces traditional solid-phase adsorption, allowing CO2 adsorption and thermal regeneration to occur simultaneously in different regions, thus replacing the traditional intermittent solid-phase adsorption method. This continuous operation characteristic enables the CO2 capture process to proceed uninterruptedly, maintaining high-flux absorption of solid-phase air while operating continuously, significantly increasing the efficiency of air CO2 capture and concentration.

[0033] 2) Low-temperature desorption using a liquid-phase chemical absorption desorption tower replaces direct steam desorption with solid-phase desorption, avoiding the drawback of steam condensate clogging the pores and significantly reducing the efficiency of solid adsorbents. At the same time, it leverages the advantages of liquid-phase adsorption and desorption, such as fast cycle, high collection efficiency, and high purity of desorbed gas. It also reduces steam consumption, significantly reduces the latent heat of steam condensation, and reduces the sensible heat of cyclic heating. The overall energy consumption is reduced by more than 60% compared with the existing solid-phase air direct collection method.

[0034] 3) The innovative process of using a solid-phase rotor for CO2 enrichment combined with liquid-phase chemical absorption for relay capture can gradually increase the CO2 concentration in the air, giving full play to the advantages of solid-phase and liquid-phase capture technologies, reducing the energy consumption and cost of air capture of CO2, and greatly expanding the application scenarios and flexibility of carbon capture.

[0035] 4) Using nitrogen as the carrier for regeneration gas and enrichment gas enables the internal circulation of nitrogen in solid-phase adsorption and liquid-phase absorption in series, avoiding contact between solid-phase adsorbent and liquid-phase adsorbent and oxygen at high temperatures, reducing the oxidative degradation rate of adsorbent and absorbent, and reducing absorbent loss.

[0036] 5) The use of nitrogen circulation technology not only makes full use of nitrogen, but also significantly reduces the volatilization of liquid absorbent, thereby reducing the pollution to the atmosphere caused by the volatilization of carbon capture absorbent. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a direct air carbon dioxide capture system based on solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption linkage according to the present invention;

[0038] Figure 2 This is a flowchart illustrating the direct air carbon dioxide capture process of the present invention, which combines solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption.

[0039] In the diagram: 1. Air fan, 2. Air filter, 3. Adsorption zone, 4. Desorption zone, 5. Regeneration gas heater, 6. Inlet and outlet gas heat exchanger, 7. Cooling zone, 8. Concentrated gas fan, 9. Spray packed absorption tower, 10. Buffer tank, 11. Rich liquid pump, 12. Lean and rich liquid heat exchanger, 13. Lean liquid cooler, 14. Desorption tower, 15. Bottom pump, 16. Flash tank, 17. Lean liquid pump, 18. Compressor, 19. Amine escape control tower. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0041] Example: As attached Figure 1-2 As shown, a direct air CO2 capture system combining solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption includes a solid-phase rotary concentrator system and a liquid-phase chemical adsorption-desorption system.

[0042] The solid-phase rotary concentrator system includes an adsorption rotary device, an air fan 1, an air filter 2, a regeneration gas heater 5, and an inlet and outlet gas heat exchanger 6. The adsorption rotary device contains a honeycomb rotor loaded with solid adsorbent. The adsorption rotary device includes an adsorption zone 3, a cold blowing zone 7, and a desorption zone 4. As the adsorption rotary device rotates, the solid adsorbent inside continuously circulates from the adsorption zone to the regeneration / desorption zone, then to the cold blowing zone, and back to the adsorption zone.

[0043] Air blower 1 is connected to adsorption zone 3 via air filter 2 through a pipeline. The air delivered by air blower 1 is filtered by air filter 2 to remove solid impurities and then blown into adsorption zone 3.

[0044] The circulating carrier gas is blown into the inlet of the cold blowing zone 7 after passing through the cold channel of the inlet and outlet gas heat exchanger 6. The outlet of the cold blowing zone 7 is connected to the inlet of the desorption zone 4 through the regeneration gas heater 5 via a pipeline. The outlet of the desorption zone 4 discharges enriched gas rich in CO2. After passing through the hot channel of the inlet and outlet gas heat exchanger 6, the enriched gas is sent to the liquid phase chemical adsorption and desorption system to recover the CO2 therein, and the recirculated carrier gas with desorbed CO2 is reused to form a circulating loop of the recirculated carrier gas.

[0045] The liquid-phase chemical adsorption-desorption system includes a concentrated gas blower 8, a spray-packed absorption tower 9, a buffer tank 10, a rich liquid pump 11, and a rich liquid regeneration system. The hot channel outlet of the inlet and outlet gas heat exchanger 6 is connected to the lower air inlet of the spray-packed absorption tower 9 via a pipeline through the concentrated gas blower 8. Liquid absorbent is introduced into the upper liquid inlet of the spray-packed absorption tower 9. The circulating carrier gas for desorbing CO2 discharged from the gas outlet at the top of the spray-packed absorption tower 9 is introduced into the cold channel of the gas heat exchanger 6. The CO2-rich absorbent solution at the bottom of the spray-packed absorption tower 9 is first discharged into the buffer tank 10, and then pumped out by the rich liquid pump 11 and sent to the rich liquid regeneration system for heating and desorbing CO2, so that the desorbed CO2 liquid absorbent can be reused, forming a circulation loop for the liquid absorbent.

[0046] The rich liquor regeneration system includes a rich-lean liquor heat exchanger 12, a lean liquor cooler 13, a desorption tower 14, a bottom pump 15, a flash tank 16, a lean liquor pump 17, and a compressor 18. The outlet of the rich liquor pump 11 is connected to the upper inlet of the desorption tower 14 via a pipeline through the cold channel of the rich-lean liquor heat exchanger 12. A heater is installed in the lower part of the desorption tower 14. The bottom outlet of the desorption tower 14 is connected to the middle inlet of the flash tank 16 via the bottom pump 15. The top outlet of the flash tank 16 is connected to the lower inlet of the desorption tower 14 via a pipeline through the compressor 18. Under the operation of the compressor 18, the flash tank 16 is kept under negative pressure to promote desorption. The bottom outlet of the flash tank 16 is connected to the upper inlet of the spray packing absorption tower 9 via a pipeline through the lean liquor pump 17, the hot channel of the rich-lean liquor heat exchanger 12, and the lean liquor cooler 13.

[0047] Comparison Figure 1 The top outlet of the desorption tower 14 is also connected to an amine escape control tower 19 via a pipeline. The amine escape control tower 19 is a condensation device for the absorbent components. The desorbed gas is discharged from the top of the desorption tower 14, cooled by the amine escape control tower 19, and the droplets of the absorbent components are condensed and refluxed. The uncondensed pure CO2 is sent to a storage tank for sealing.

[0048] Example 1: In Example 1 of this invention, the liquid absorbent is an ionic liquid low-water absorbent. The preparation process is feasible. Imidazole (Im) and an equimolar amount of tetramethylammonium hydroxide ([N1111][OH]) solution are stirred at 60°C for 24 hours. The OH⁻ ions provided by tetramethylammonium hydroxide undergo a proton transfer reaction with imidazole to generate imidazole-onium anions ([Im]⁻). The imidazole-onium anions ([Im]⁻) react with the tetramethylammonium hydroxide cations ([N1111]). + This forms an amino-functionalized ionic liquid low-water absorbent with the structure [N1111][Im].

[0049] The honeycomb rotor base is a porous, honeycomb-shaped corrugated medium made of ceramic fiber, purchased from Wuxi Desert Dehumidification Equipment Factory. The solid adsorbent in Example 1 of this invention is an amine-functionalized resin adsorbent, specifically IRA-900 resin, sourced from DuPont, USA. Its composition is a macroporous styrene-divinylbenzene copolymer with quaternary ammonium groups [-N(CH3)3OH] on an anion exchange resin, model IRA-900. The steps for loading the solid adsorbent onto the honeycomb rotor are as follows:

[0050] S1: IRA-900 resin is packed in a chromatography column. Using column chromatography, an excess of 5wt% NaOH / ethanol solution is passed through the chromatography column to perform ion exchange and convert the resin into a hydroxyl form.

[0051] S2: Elute the resin in the chromatography column with an excess of 5 wt% imidazole / ethanol solution. The purpose is to introduce amino groups onto the resin through ion exchange. The excess imidazole / ethanol solution is to ensure complete ion exchange between imidazole and the resin.

[0052] S3: The resin obtained in step S2 is repeatedly washed with ethanol, then dried under vacuum at 80°C for 24 hours, and then the adsorbent resin is ground into fine powder of 1-3 nm.

[0053] S4: The fine powder from step S3 is mixed with water and an inorganic binder, acidic silica sol (mass fraction 30%), in a mass ratio of 50% / 45% / 5% to form an adsorbent slurry.

[0054] S5: Immerse the honeycomb rotor base wheel in the adsorbent slurry obtained in step S4, then remove the honeycomb rotor base wheel from the slurry. The unadhered adsorbent slurry will fall off naturally. Then immerse the honeycomb rotor base wheel in the adsorbent slurry again. Repeat this process multiple times until the mass of the adsorbent slurry loaded on the honeycomb rotor base wheel reaches 70% of the mass of the honeycomb rotor base wheel. Dry with hot air at 120℃ to promote gelation and remove water and binder, so that the bonding strength is increased to ≥5.0N / cm and the pores of the material are fully exposed, thus producing a solid-phase rotor loaded with amine functionalized resin, which is the honeycomb rotor adsorbent.

[0055] A direct air capture process for CO2 using solid-phase rotary concentrators and liquid-phase chemical adsorption-desorption (see...) Figure 2 ), including the following steps:

[0056] 1) The CO2 content in the air is 400 ppm, and the air fan 1 draws in an air flow rate of 1000 m³ / h. 3 / h, by first passing through an air filter to remove dust particles and other impurities, the CO2 is then blown into the adsorption zone 3 of the adsorption rotor device, where it comes into full contact with the amine-functionalized resin adsorbent loaded on the honeycomb rotor. CO2 is captured by the amine-functionalized resin adsorbent at 25°C and stored in the pores of the adsorbent. The carbon dioxide load of the amine-functionalized resin adsorbent is increased from 0.3 mol / kg to the saturated absorption load of 1.3 mol / kg.

[0057] The CO2 concentration of the purified gas after acid removal discharged from adsorption zone 3 is 40 ppm, which is released into the atmosphere. The CO2 absorption efficiency is 90%.

[0058] 2) After adsorbing CO2, the amine-functionalized resin adsorbent on the honeycomb rotor in adsorption zone 3 rotates to desorption zone 4. 200°C regeneration gas from regeneration gas heater 5 is introduced into desorption zone 4 to purge the adsorbent inside. CO2 is released from the solid-phase adsorbent through heat exchange combined with desorption heat absorption. The regeneration gas is then blown out at 80°C, increasing the mixed CO2 concentration to 2% to form enriched gas, thus increasing the CO2 concentration by 50 times. After passing through the hot channel of outlet heat exchanger 6, the temperature drops to 50°C and is then introduced into the chemical absorption / desorption section.

[0059] In the solid-phase rotary concentrator process, the rotation of the rotor allows the adsorption, desorption, and cooling of the solid absorbent to occur simultaneously, ensuring the continuity of the concentration process. Furthermore, by concentrating high-throughput air, the CO2 concentration is increased, enabling the application of high-efficiency liquid-phase chemical absorption, significantly reducing the reaction time, increasing the circulation load, and decreasing the regeneration energy consumption of the chemical absorption method.

[0060] 3) The enriched gas at 50℃ is pressurized by the enriched gas blower 8 at 170 m 3A flow rate of 500 L / h enters the lower part of the spray-packed absorption tower 9, while a liquid absorbent at 40°C is simultaneously introduced from the upper part of the tower. The liquid absorbent spray rate is 500 L / h, and it comes into countercurrent contact with the enriched gas within the tower, allowing for thorough heat exchange. The CO2 in the enriched gas is absorbed by the liquid absorbent, and the purified gas forms a circulating carrier gas that is released from the top of the tower. The CO2 concentration in the released circulating carrier gas is 0.2%, and the absorption efficiency of the tower is 90%. At the bottom of the spray-packed absorption tower 9, an ionic liquid rich solution with a CO2 load of 1.5 mol / kg at 50°C is formed. After being buffered by the buffer tank 10, it is pumped by the rich solution pump 11 to the cold channel of the lean-rich solution heat exchanger 12 for heat exchange and temperature increase to 85°C before entering the desorption tower 14.

[0061] 4) Under the action of the reboiler at the bottom of the desorption tower 14, the temperature inside the desorption tower 14 is raised to 95℃, and CO2 is removed from the rich ionic liquid. At the same time, the absorbent at the bottom of the desorption tower 14 is pumped into the flash tank 16 through the bottom pump 15. Under the action of the compressor 18, the flash tank 16 forms a negative pressure of 20 kPa, and the absorbent at the bottom of the tower is further desorbed in it, forming a lean liquid with a CO2 load of 0.5 mol / kg after desorption.

[0062] The desorbed gas is discharged from the top of the desorption tower 14, cooled by the amine escape control tower 19, and the droplets of the absorbent component are condensed and refluxed. The pure CO2 is sent to the storage tank for sealing.

[0063] The lean liquor with a CO2 load of 0.5 mol / kg at the bottom of flash tank 16 is pumped by lean liquor pump 17 to the hot channel of lean-rich liquor heat exchanger 12 for heat exchange and cooling to 55°C. It is then further cooled to 40°C by lean liquor cooler 13 before re-entering the top of the spray-packed absorption tower 9 to contact the concentrated gas counter-currently, completing the absorption-desorption cycle. Using an ionic liquid low-aqueous absorbent allows for desorption at a low temperature of 90°C, significantly reducing desorption energy consumption.

[0064] 5) After the concentrated gas comes into countercurrent contact with the liquid absorbent in the spray-packed absorption tower 9, the circulating carrier gas is released from the top of the spray-packed absorption tower 9 and used as cooling gas for the honeycomb rotor adsorbent. The circulating gas first undergoes heat exchange through the cold channel of the inlet and outlet heat exchanger 6, raising its temperature to 70°C. It is then blown into the cold blowing zone 7 to cool the solid-phase adsorbent inside, while the circulating gas is further heated. It is then heated to 200°C by the gas heater 5 to form regeneration gas, which enters the solid-phase rotor regeneration zone to desorb the amine-functionalized resin. The regeneration gas is concentrated to form concentrated gas, which is then returned to the liquid phase for absorption. The entire solid-phase desorption zone is in a nitrogen circulation loop, which not only significantly reduces the amine escape problem, which is generally difficult to handle in traditional chemical absorption methods, but also reduces the degradation problem of the solid-phase adsorbent. Furthermore, the heat exchange network significantly reduces the system's heating requirements, achieving a significant improvement over the high energy consumption of pure solid-phase air capture.

[0065] According to the experimental procedure of Example 1 of this invention, under stable operation for 12 hours, when nitrogen was used as the carrier gas in the circulating gas operation, no decrease in the adsorption or absorption performance of CO2 by either the solid-phase adsorbent (i.e., the amine-functionalized resin adsorbent loaded on the honeycomb rotor) or the liquid-phase absorbent (i.e., the ionic liquid low-water absorbent) was detected. The adsorption or absorption performance was determined by the CO2 capture performance. For example, the CO2 adsorption performance of the solid-phase adsorbent was evaluated by the change in CO2 concentration in the concentrated gas over time. The CO2 absorption performance of the liquid-phase absorbent was evaluated by the CO2 absorption efficiency within the spray-packed absorption tower 9.

[0066] However, according to the experimental process of Embodiment 1 of the present invention, when oxygen is used as the carrier gas in the circulating gas operation after 200 hours of stable operation, the adsorption performance of the solid phase adsorbent decreases by about 20%-25%, and the adsorption performance of the liquid phase adsorbent decreases by about 2%-5%.

[0067] Therefore, the nitrogen circulation of the present invention can significantly suppress the oxidative degradation rate of solid-phase adsorbents and liquid-phase absorbents, and improve the lifespan of adsorbents and absorbents.

[0068] In addition, regarding the experimental performance of CO2 capture and desorption, the process conditions of Example 1 of this invention were compared with the experimental data published in the existing literature "KZ House, AC Baclig, M. Ranjan, EA van Nierop, J. Wilcox, & H.J. Herzog, Economic and energetic analysis of capturing CO2 from ambient air, Proc.Natl. Acad. Sci. USA 108 (51) 20428-20433". The process effects of direct air capture and desorption of CO2 are compared between the two. Table 1 shows the comparison of the process effects of the two methods.

[0069] Table 1 Comparison of the effects of direct air capture-CO2 desorption processes

[0070] .

[0071] In Table 1, total energy consumption and comprehensive cost refer to the total energy consumption and total cost of capturing and desorbing 1 ton of CO2, respectively.

[0072] The formula for calculating CO2 capture efficiency is shown in equation (1):

[0073] .

[0074] φ is the carbon dioxide capture rate, in percentages (%).

[0075] Q out : Airflow rate at the outlet of the DAC capture system under standard conditions, in m³ / s 3 / h;

[0076] C m,out : Carbon dioxide mass concentration in the outlet air of the DAC capture system under standard conditions, in g / m³ 3 ;

[0077] Q in : Inlet airflow of the DAC capture system under standard conditions, in m³ / s 3 / h;

[0078] C m,in : Carbon dioxide mass concentration in the inlet air of the DAC capture system under standard conditions, in g / m³ 3 .

[0079] The formula for calculating the total energy consumption of CO2 direct air capture and thermal desorption regeneration is shown in equation (2):

[0080] .

[0081] SE e The electricity required to capture 1 ton of CO2 is expressed in kW·h / tCO2; specifically in this invention, SE e The energy consumption mainly depends on the power consumption of the air blower 1, regeneration gas heater 5, enrichment gas blower 8, lean liquor cooler 13 and lean liquor pump 17.

[0082] SE r The energy consumed by the DAC capture system to heat and desorb the captured CO2 after capturing 1 ton of CO2 is measured in GJ / tCO2. Specifically, in this invention, SE... r The energy consumption mainly depends on the electricity consumption of the rich liquid pump 11, the reboiler of the desorption tower 14, the bottom pump 15, the compressor 18, and the amine escape control tower 19.

[0083] SE: Total heat consumption per unit of carbon dioxide in the capture system, which is the total energy consumed in capturing and desorbing 1 ton of carbon dioxide, expressed in GJ / tCO2.

[0084] In addition, the existing liquid phase absorption method for direct air capture has high theoretical energy consumption and no implementation cases. According to theoretical data, the total energy consumed to capture and desorb 1 ton of carbon dioxide is more than 30 GJ / t, and the total cost of capturing and desorbing 1 ton of CO2 is more than $600 / t.

[0085] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A direct air CO2 capture system combining solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption, characterized in that... This includes a solid-phase rotary concentrator system and a liquid-phase chemical adsorption-desorption system; The solid-phase rotary concentrator system includes an adsorption rotary device, an air fan (1), a regeneration gas heater (5), and an inlet and outlet gas heat exchanger (6). The adsorption rotary device is equipped with a honeycomb rotary adsorbent, which includes a honeycomb rotary wheel and a solid adsorbent loaded on the honeycomb rotary wheel. The adsorption rotary device includes an adsorption zone (3), a cold blowing zone (7), and a desorption zone (4). When the adsorption rotary device is rotating, the solid adsorbent inside it continuously circulates from the adsorption zone to the regeneration and desorption zone, then to the cold blowing zone, and then back to the adsorption zone. The air fan (1) is connected to the adsorption zone (3) by a pipeline; The circulating carrier gas is blown into the inlet of the cold blowing zone (7) after passing through the cold channel of the inlet and outlet gas heat exchanger (6). The outlet of the cold blowing zone (7) is connected to the inlet of the desorption zone (4) through the regeneration gas heater (5) by a pipeline. The outlet of the desorption zone (4) discharges CO2-rich enriched gas. After passing through the hot channel of the inlet and outlet gas heat exchanger (6), the enriched gas is sent to the liquid phase chemical adsorption and desorption system to recover the CO2 therein, and the CO2-desorbed circulating carrier gas is reused to form a circulating loop of the circulating carrier gas. The liquid phase chemical adsorption-desorption system includes a concentrated gas blower (8), a spray packing absorption tower (9), a buffer tank (10), a rich liquid pump (11), and a rich liquid regeneration system. The hot channel outlet of the inlet and outlet gas heat exchanger (6) is connected to the lower air inlet of the spray packing absorption tower (9) by a pipeline through the concentrated gas blower (8). The liquid absorbent is introduced into the upper liquid inlet of the spray packing absorption tower (9). The circulating carrier gas for desorbing CO2 is discharged from the gas outlet at the top of the spray packing absorption tower (9) and introduced into the cold channel of the inlet and outlet gas heat exchanger (6). The rich CO2 absorbent in the bottom of the spray packing absorption tower (9) is first discharged into the buffer tank (10), and then pumped out by the rich liquid pump (11) and sent to the rich liquid regeneration system for heating and desorbing CO2. The desorbed liquid absorbent is reused to form a circulation loop of liquid absorbent. The rich liquor regeneration system includes a rich-lean liquor heat exchanger (12), a lean liquor cooler (13), a desorption tower (14), a bottom pump (15), a flash tank (16), a lean liquor pump (17), and a compressor (18). The outlet of the rich liquor pump (11) is connected to the upper inlet of the desorption tower (14) via a pipeline through the cold channel of the rich-lean liquor heat exchanger (12). A bottom reboiler is installed at the bottom of the desorption tower (14). The bottom outlet of the desorption tower (14) is connected to the flash tank via the bottom pump (15). The middle inlet of the evaporator (16) is connected, and the top outlet of the flash evaporator (16) is connected to the lower inlet of the desorption tower (14) via a pipeline through the compressor (18). Under the operation of the compressor (18), the flash evaporator (16) is kept under negative pressure to facilitate flash evaporation. The bottom outlet of the flash evaporator (16) is connected to the upper inlet of the spray packing absorption tower (9) via a pipeline through the lean liquid pump (17), the hot channel of the lean and rich liquid heat exchanger (12), and the lean liquid cooler (13).

2. The direct air CO2 capture system based on solid-phase rotary concentrator and liquid-phase chemical adsorption-desorption as described in claim 1, characterized in that... It also includes an air filter (2), and the air delivered by the air blower (1) is filtered through the air filter (2) to remove solid impurities and then blown into the adsorption zone (3).

3. The direct air carbon dioxide capture process of the system as described in claim 1, characterized in that... The adsorption rotor device is equipped with a honeycomb rotor adsorbent, which includes a honeycomb rotor and a solid adsorbent loaded on the honeycomb rotor. The adsorption rotor device includes an adsorption zone (3), a cold blowing zone (7), and a desorption zone (4). The process Includes the following steps: S1: The air blower (1) draws and delivers ambient air, first passing it through the air filter (2) to remove solid impurities, and then enters the adsorption zone (3) at room temperature to fully contact the solid adsorbent inside it. CO2 in the air is efficiently adsorbed onto the solid adsorbent, and the purified air after removing CO2 is discharged into the atmosphere. The solid adsorbent in the adsorption zone (3) after adsorbing CO2 rotates with the rotor to the desorption zone (4). S2: The circulating carrier gas for desorbing CO2 from the liquid phase chemical adsorption-desorption system first undergoes heat exchange through the cold channel of the inlet and outlet gas heat exchanger (6), and then is blown into the cold blowing zone (7) to cool the solid adsorbent inside. It is then heated to 180-220°C by the regeneration gas heater (5) to form high-temperature regeneration gas. The regeneration gas is then introduced into the desorption zone (4) to desorb CO2 from the solid adsorbent inside. The CO2 in the regeneration gas is concentrated to form concentrated gas. After the concentrated gas flows through the hot channel of the inlet and outlet gas heat exchanger (6) for heat exchange, it enters the liquid phase chemical adsorption-desorption system for chemical absorption and desorption. The CO2 in the concentrated gas is removed by chemical absorption and then reformed into the circulating carrier gas, which is then reused in the cold channel of the inlet and outlet gas heat exchanger (6) to form a circulating loop for CO2 concentration and desorption of the circulating carrier gas.

4. The process as described in claim 3, characterized in that... The circulating carrier gas is N2, the CO2 concentration of the enriched gas in step S2 is 0.5%-10%, the temperature of the circulating carrier gas after heat exchange through the cold channel of the inlet and outlet heat exchanger (6) is 60-75℃, and the temperature of the enriched gas after heat exchange through the hot channel of the inlet and outlet heat exchanger (6) is 45-55℃.

5. The process as described in claim 4, characterized in that... In step S2, the CO2 concentration of the enriched gas is 1%-5%.

6. The process as described in claim 3, characterized in that... The chemical absorption and desorption operations include the following steps: 1) The enriched gas enters the lower part of the spray packing absorption tower (9) under the pressure of the enriched gas blower (8), and at the same time, the liquid phase absorbent is introduced from the upper part of the spray packing absorption tower (9). The gas and liquid phases are in countercurrent contact. The CO2 in the enriched gas is absorbed by the liquid phase absorbent and the CO2-removed circulating carrier gas is discharged from the top of the spray packing absorption tower (9). This circulating carrier gas is reused. 2) The CO2-rich absorbent liquid at the bottom of the spray-packed absorber (9) is first discharged into the buffer tank (10), and then pumped out by the rich liquid pump (11) and sent to the cold channel of the lean-rich liquid heat exchanger (12) for heat exchange and temperature rise. Then it enters the desorption tower (14) for heating and desorption. At the same time, the absorbent liquid at the bottom of the desorption tower (14) is pumped into the flash tank (16) through the bottom pump (15). The negative pressure in the flash tank (16) is maintained by the compressor (18). The CO2-rich desorbed gas after flashing is reintroduced into the lower part of the desorption tower (14). The desorbed gas is discharged from the top of the desorption tower (14) and collected. 3) The lean CO2 absorbent at the bottom of the flash tank (16) is pumped to the hot channel of the lean and rich liquid heat exchanger (12) by the lean liquid pump (17) for heat exchange and cooling. Then it is further cooled to 30-45°C by the lean liquid cooler (13) and re-enters the upper part of the spray packing absorption tower (9) to contact the enriched gas in a countercurrent flow to complete the absorption and desorption cycle.

7. The process as described in claim 3, characterized in that... Step 1) The CO2 concentration of the circulating carrier gas discharged from the top of the self-spraying packed absorber (9) is below 0.5%. Step 2) The rich CO2 absorbent is heated to 75-85℃ by heat exchanger (12) and then sent to the desorption tower (14) for heating and desorption. The heating and desorption temperature is 90-100℃. Step 3) The lean CO2 absorbent is cooled to 50-60℃ by heat exchanger (12).

8. The process as described in claim 3, characterized in that... The loading of the solid adsorbent on the honeycomb rotor is 20%-50%, and the solid adsorbent is one of the following: amine-functionalized alkaline polymer porous resin, amine-functionalized ionic liquid porous material, zeolite, activated carbon, metal-organic framework, mesoporous silica, and carbon nanomaterials.

9. The process as described in claim 6, characterized in that... The effective component of the liquid absorbent is an organic amine compound or an amino-functionalized ionic liquid. The organic amine compound is one or more of monoethanolamine, diethanolamine, methyldiethanolamine, piperazine, 2-amino-2-methyl-1-propanol, and triethylenetetramine. The amino-functionalized ionic liquid is a quaternary ammonium nitrogen heterocyclic ionic liquid.

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