Phase change capsule circulating heat management double-fixed bed CO2 capture system and process

Abstract

The invention discloses a double-fixed-bed CO2 capture system for phase change capsule circulating heat management. The system comprises a to-be-captured flue gas tank, a first fixed bed, a second fixed bed, a capsule heat exchange bin, a low-temperature heat pump, a first fan, a second fan, a carbon dioxide compressor and a carbon dioxide storage tank, by means of alternate adsorption and desorption operation of the double fixed beds and cooperation of circulating heat exchange of the phase change capsules, closed-loop strengthening of adsorption heat release, heat storage and regeneration heat release is achieved, carrying and stable supply of heat in time and space are achieved, the external energy supply requirement of the system is remarkably reduced while the adsorption efficiency is guaranteed, and the system stability and amplification feasibility are improved.

Description

Technical Field

[0001] This invention belongs to the fields of gas separation, energy chemical industry and energy conservation and environmental protection technology, and relates to a high-efficiency and low-energy-consumption capture technology for low-concentration carbon dioxide in coal-fired flue gas and industrial tail gas. Specifically, it relates to a dual fixed-bed CO2 capture system and process with phase change capsule cycle thermal management. Background Technology

[0002] Driven by global climate change and the "dual carbon" goal, carbon dioxide capture, utilization, and storage (CCUS) has become an important technological path for industrial emission reduction. Among existing CO2 capture processes, wet-process amine absorption is widely used, but it generally suffers from high regeneration energy consumption, equipment corrosion, and high operation and maintenance costs. In contrast, solid adsorption methods, due to their low theoretical energy consumption, lack of corrosion, and flexible operation, are considered one of the potential alternatives to wet-process amine absorption. However, existing potassium-based solid adsorbents still face two key bottlenecks in engineering applications: adsorption exotherm leading to bed temperature rise and capacity reduction: CO2 adsorption is accompanied by significant exotherm, and increased bed temperature reduces adsorption capacity and affects effective capture capacity and breakthrough time; pressure drop and parasitic energy consumption issues in fixed-bed high-flow-rate flue gas treatment: traditional fixed-bed reactors generate significant flow resistance and pressure drop when treating large volumes of flue gas, thus consuming a large amount of fan / compressor power, resulting in significant mass transfer limitations and parasitic energy consumption.

[0003] To address the aforementioned issues, existing research has proposed introducing phase change materials (PCMs) into adsorption systems for thermal management. PCMs can absorb a large amount of latent heat at approximately an isothermal temperature near the phase transition point, thereby suppressing temperature spikes, maintaining the bed within the optimal adsorption temperature range, and maximizing effective capacity. However, from an engineering perspective, the existing PCM-coupled adsorption approach still has room for further optimization: on the one hand, adsorption exothermics are characterized by "low-grade heat," and direct use for desorption regeneration often results in insufficient temperature gradient; on the other hand, the heat generated during adsorption and desorption processes is mismatched in time and space, making it difficult to stably recover and reuse heat for regeneration. Therefore, there is an urgent need for a process flow that can achieve continuous heat recovery, temperature gradient enhancement, and stable heating regeneration within a fixed-bed adsorption / desorption system to improve overall energy efficiency and economy. Summary of the Invention

[0004] To address the aforementioned issues, this invention discloses a dual-fixed-bed CO2 capture system and process for phase change capsule cyclic thermal management. By alternating adsorption and desorption operation of the dual fixed beds, combined with the cyclic heat exchange of the phase change capsules, a closed-loop enhancement of "adsorption heat release - heat storage - regeneration heat release" is achieved, realizing the "transportation" and stable supply of heat in time and space, thereby improving the system's stability and scalability.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: A dual-fixed-bed CO2 capture system with phase change capsule cycle thermal management includes a flue gas collection canister, a first fixed bed, a second fixed bed, a capsule heat exchange chamber, a low-temperature heat pump, a first fan, a second fan, a carbon dioxide compressor, and a carbon dioxide storage tank; wherein: The outlet of the flue gas canister to be captured is connected to the main flue gas pipeline in sequence through the flue gas canister throttle valve. The main flue gas pipeline is connected to the lower inlet of the first fixed bed and the second fixed bed through the first fixed bed flue gas throttle valve and the second fixed bed flue gas throttle valve respectively, so that the flue gas to be captured is adsorbed from bottom to top through the fixed bed. The first fixed bed and the upper part of the second fixed bed are respectively connected to the first heat exchanger and the second heat exchanger, and their opening and closing are controlled by throttling valves on the first and second fixed beds. The gas after heat exchange enters the carbon dioxide compressor for compression through the throttling valve of the carbon dioxide compressor. After compression, the carbon dioxide enters the carbon dioxide storage tank for storage, and the storage tank is connected to the system through the carbon dioxide storage tank throttling valve. The lower parts of the first fixed bed and the second fixed bed are respectively provided with independent carbon dioxide gas channels and capsule solid channels. The carbon dioxide throttling valves under the first and second fixed beds are connected in parallel to the carbon dioxide storage tank through the carbon dioxide storage tank throttling valve, which is used to introduce carbon dioxide gas into the corresponding fixed bed for purging and regeneration during the desorption stage. The capsule throttling valves under the first and second fixed beds are connected in parallel to the capsule heat exchange chamber, which is used to control the flow of phase change capsules between the fixed bed and the capsule heat exchange chamber. The capsule heat exchange chamber is connected to the capsule channels of the two fixed beds through the left valve and the right valve of the capsule heat exchange chamber, respectively, for heat recovery from the high-temperature capsules from the desorption bed; The capsule heat exchange chamber is connected to a low-temperature heat pump, and the heat is transferred to the low-temperature heat pump after heat exchange. The low-temperature heat pump forms a closed heat cycle with the system through the right valve and the left valve of the low-temperature heat pump. The dotted line represents the energy transfer loop. The recovered heat is raised to a higher temperature and then transported to the fixed bed in the desorption state to provide heat for desorption and regeneration. The first fan and the second fan are connected to the upper end of the two fixed beds through the first fan throttle valve and the second fan throttle valve, respectively. They are also connected to the left valve and the right valve of the capsule heat exchange chamber, respectively. After adsorption is completed, the phase change capsules in the fixed bed can be blown to the capsule heat exchange chamber, and in the next cycle stage, the heat-exchanged capsules can be transported to another fixed bed.

[0006] Furthermore, the first fixed bed and the second fixed bed adopt an alternating operation mode, in which one bed is in the adsorption mode and the other bed is in the desorption and regeneration mode. After a predetermined time is completed, the functions are switched by valve to realize the continuous capture operation of the system.

[0007] Furthermore, the first fixed bed is preloaded with adsorbent material and phase change capsules during the first cycle.

[0008] Furthermore, the carbon dioxide storage tank is initially filled with a certain amount of carbon dioxide.

[0009] Furthermore, the flue gas adsorption process in the system does not require a flue gas compression and venting unit. The flue gas flows through the fixed bed in a bottom-in, top-out manner, achieving low-resistance adsorption operation.

[0010] Furthermore, the desorption and regeneration stage uses pure carbon dioxide gas as the purging gas, without introducing nitrogen or inert gas, in order to improve desorption efficiency, avoid gas dilution, and make reasonable use of resources.

[0011] Furthermore, the capsule circulation channel and the gas channel are set independently, and the solid phase change capsule and the gas flow separately, avoiding the pressure drop increase and wear problems caused by gas-solid mixing.

[0012] Furthermore, the system adopts a modular or skid-mounted integrated structure, with each functional unit integrated and installed on the same base, which facilitates transportation, installation, and parallel expansion of multiple units.

[0013] Furthermore, the system also includes a heat management control unit, which monitors the bed temperature distribution and capsule outlet temperature in real time, and maintains the system's thermal balance by adjusting the power of the heat pump compressor and the speed of the capsule circulation pump through frequency conversion.

[0014] A dual-fixed-bed CO2 capture process with phase change capsule cycle thermal management includes the following steps: (1) Construct a dual fixed-bed adsorption system: Set up at least two alternating fixed-bed reactors, namely the first fixed bed and the second fixed bed, with honeycomb structured packing coated with potassium-based adsorbent in the bed; the system is equipped with flowable phase change capsules and heat pump units for heat recovery and upgrading. (2) Isothermal adsorption and in-situ heat storage: CO2-containing flue gas is introduced into the first fixed bed in the adsorption state, and at the same time, a phase change capsule in the cooling state is introduced into the honeycomb channel or gap of the fixed bed; the potassium-based adsorbent captures CO2 and releases the heat of reaction, and the phase change capsule absorbs the heat of reaction in-situ through solid-liquid phase change, thereby controlling the bed temperature within the preset adsorption temperature range. (3) Capsule separation and heat removal: When the first fixed bed is saturated with adsorption or the phase change capsule has completed the phase change, the phase change capsule carrying latent heat is separated from the first fixed bed and discharged to the external capsule heat exchange chamber. (4) Heat release and capsule regeneration: In the capsule heat exchange chamber, the phase change capsule releases latent heat to the evaporation side of the heat pump system and returns to the solid-state cooling state, and then returns to the adsorption step for recycling; (5) Heat pump heating and adsorbent regeneration: The heat pump unit uses the consumed electrical energy to raise the low-grade heat recovered from the phase change capsule to the regeneration temperature, and transports it to the second fixed bed in the desorption state to drive the potassium-based adsorbent to decompose and release high-concentration CO2, thereby realizing adsorbent regeneration.

[0015] Further, the honeycomb structured filler in step (1) is a silica honeycomb monomer, and the inner wall of its pores is coated with a K2CO3 / Al2O3 composite adsorbent; the mass ratio of K2CO3 to Al2O3 in the composite adsorbent is (3-5):3, preferably 4:3.

[0016] Furthermore, the coating method includes: mixing K2CO3 with aluminum sol to prepare a slurry, coating the slurry into the pores of the honeycomb carrier, and drying and calcining to form the final product; preferably, the coating is applied twice to maximize the adsorbent loading while ensuring the stability of the coating.

[0017] Furthermore, the phase change capsule described in step (1) is a core-shell structured microcapsule with a core material of paraffin and a phase change temperature set at 50-70°C, preferably 64°C, which matches the optimal adsorption activity temperature of the potassium-based adsorbent; the shell material is silicon dioxide or PMMA, which has wear resistance and high thermal conductivity.

[0018] Furthermore, in step (2), the preset adsorption temperature is 60±2℃; by adding phase change capsules to absorb the exothermic adsorption reaction, near-isothermal adsorption is achieved.

[0019] Furthermore, the capsule separation method described in step (3) utilizes the difference in flowability between the phase change capsule and the fixed-bed honeycomb packing, including one or more combinations of gravity sedimentation separation and pneumatic purging separation; the honeycomb structured packing is fixed, and the phase change capsule, as the mobile phase, flows through the honeycomb channels or flows in the gaps between the packing.

[0020] Furthermore, in step (5), the heat pump unit raises the heat from a low temperature of about 60°C to a high temperature of 100-150°C; the heat pump unit is a compression heat pump or an absorption heat pump, and the working fluid is selected to match the temperature rise requirement.

[0021] Furthermore, the high-concentration CO2 generated by desorption is collected and used as industrial feedstock for methanol synthesis or supplied externally as a protective gas.

[0022] The beneficial effects of this invention are as follows: This application achieves continuous carbon dioxide capture through alternating adsorption and desorption operation in dual fixed beds; it reduces system energy consumption by introducing a phase change capsule heat storage and release cycle to achieve efficient recovery and utilization of adsorption heat and regeneration heat; it uses a capsule heat exchange chamber and a low-temperature heat pump to recover system waste heat in synergy to improve heat quality and provide heat for the desorption process, thereby significantly reducing regeneration energy consumption; at the same time, it adopts pure carbon dioxide purging and an independent gas-solid channel structure to improve desorption efficiency and reduce system resistance, effectively improving carbon dioxide capture efficiency and economy. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a dual fixed-bed CO2 capture system with phase change capsule circulating thermal management according to an embodiment of the present invention.

[0024] List of identifiers in attached diagrams: 1. Throttling valve for the flue gas to be collected; 2. Throttling valve for the first fixed bed flue gas; 3. Throttling valve for the second fixed bed flue gas; 4. Throttling valve on the first fixed bed; 5. Throttling valve on the second fixed bed; 6. Carbon dioxide throttling valve under the first fixed bed; 7. Carbon dioxide throttling valve under the second fixed bed; 8. Capsule throttling valve under the first fixed bed; 9. Capsule throttling valve under the second fixed bed; 10. Throttling valve for the first fan; 11. Throttling valve for the second fan; 12. Left valve of the capsule heat exchange chamber; 13. 14. Right valve of capsule heat exchange chamber; 15. Right valve of low-temperature heat pump; 16. Left valve of low-temperature heat pump; 17. Throttling valve of carbon dioxide compressor; 18. Throttling valve of carbon dioxide storage tank; 19. Canister for collecting flue gas; 20. First heat exchanger; 21. Second heat exchanger; 22. First fixed bed; 23. Second fixed bed; 24. Capsule heat exchange chamber; 25. Low-temperature heat pump; 26. First fan; 27. Second fan; 28. Carbon dioxide compressor; 29. ​​Carbon dioxide storage tank. Detailed Implementation

[0025] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention.

[0026] As shown in the figure, the dual fixed-bed CO2 capture system with phase change capsule cycle thermal management according to the present invention includes a flue gas collection tank 18, a first heat exchanger 19, a second heat exchanger 20, a first fixed bed 21, a second fixed bed 22, a capsule heat exchange chamber 23, a low-temperature heat pump 24, a first fan 25, a second fan 26, a carbon dioxide compressor 27, and a carbon dioxide storage tank 28. Wherein: The lower inlet of the first fixed bed 21 is connected to the flue gas collection tank 18, the capsule heat exchange chamber 23, and the carbon dioxide storage tank 28. The upper inlet of the first fixed bed 21 is connected to the first fan 25 and the carbon dioxide compressor 27. The lower inlet of the second fixed bed 22 is connected to the flue gas collection tank 18, the capsule heat exchange chamber 23, and the carbon dioxide storage tank 28. The upper inlet of the second fixed bed 22 is connected to the second fan 26 and the carbon dioxide compressor 27. The lower part of the capsule heat exchange chamber 23 is connected to the first fan 25, the second fan 26, and the low-temperature heat pump 24. The upper part of the capsule heat exchange chamber 23 is connected to the first fixed bed 21 and the second fixed bed 22.

[0027] Before circulation, the first fixed bed 21 is loaded with adsorbent and phase change capsules. During the system reaction, the flue gas to be collected from the flue gas collection tank enters the first fixed bed 21 through throttling valves 1 and 2. The flue gas comes into contact with and is absorbed by the honeycomb adsorbent from bottom to top. The heat released by the adsorption reaction is absorbed by the phase change capsules, achieving near-isothermal adsorption. After the flue gas adsorption reaction is completed, the phase change capsules after phase change enter the capsule heat exchange chamber 23 through throttling valve 8 for heat exchange. The exchanged heat enters the low-temperature heat pump to raise the calorific value from about 60℃ to 100-150℃. The cooled capsules are blown to the upper inlet of the first fixed bed 21 by high-speed gas blown by the first fan, and re-enter the honeycomb adsorbent in the first fixed bed to prepare for the next adsorption.

[0028] Meanwhile, the adsorbent desorption reaction takes place in the second fixed bed 22. Pure CO2 enters the second fixed bed 22 from the carbon dioxide storage tank 28 via valves 17 and 7. The heat required for the desorption reaction is provided by the heat exchanged from the phase change capsule, which is then boosted by a heat pump. The CO2 generated by the desorption reaction and the introduced CO2 exit from the upper outlet of the second fixed bed 22 and enter the carbon dioxide compressor 27 for compression and storage via throttling valves 5 and 16.

[0029] The dual-fixed-bed circulating capture process includes two fixed beds filled with honeycomb adsorbent, a phase change capsule heat exchange chamber, a heat exchanger, and a low-temperature heat pump. During the adsorption stage, simulated flue gas containing 10 vol.% CO2 is introduced into the first fixed bed 21 at a temperature of 60°C. The reaction begins, adsorption heat is released, and the bed temperature tends to rise. At this time, the phase change capsules absorb heat and undergo phase change, locking the bed temperature at approximately 60°C. The outlet CO2 concentration is monitored, and gas flow is stopped when the breakthrough point is reached. During or after adsorption, the heat-absorbing capsules are removed from the bed and transported to the capsule heat exchange chamber 23 by gravity or airflow assistance. In the capsule heat exchange chamber 23, the capsules release latent heat to the heat pump side, cooling and solidifying. During the regeneration stage, the heat pump raises the temperature to 120°C using the recovered heat, generating high-temperature steam or hot air which is introduced into the second fixed bed 22. The adsorbent in the second fixed bed 22 desorbs upon heating, releasing high-purity CO2 and completing regeneration. In the second round of reaction, the second fixed bed 22 serves as the adsorption bed, and the first fixed bed 21 serves as the desorption bed.

[0030] The present invention describes a dual fixed-bed CO2 capture process with phase change capsule cyclic thermal management, which significantly reduces the system's external energy supply requirements while ensuring adsorption efficiency.

[0031] This process uses two fixed beds. The first fixed bed (adsorption bed) contains a potassium-based adsorbent and phase change capsules. CO2-containing gas enters the adsorption bed through a gas path, where it is captured by the adsorbent. The heat released during adsorption is absorbed by the phase change capsules, stabilizing the bed temperature at approximately 60°C, thus improving the adsorption efficiency (this temperature range matches the optimal adsorption temperature for K2COJ). After adsorption, the phase change capsules separate from the adsorbent material; the capsules enter a heat exchanger to release the absorbed heat, cooling themselves to approximately 20°C, and then return to the first fixed bed for the next round of heat absorption. The heat released from the heat exchanger serves as a low-grade heat source, which is then fed to the second fixed bed (desorption bed) via a cryogenic heat pump to provide heat for adsorbent desorption and regeneration, achieving continuous and stable regeneration. The high-concentration CO obtained from desorption can be supplied to downstream applications, such as methanol synthesis or as a protective gas.

[0032] This process achieves near-isothermal adsorption, improving effective capacity and breakthrough time. Utilizing the near-isothermal endothermic property of phase change capsules near the phase change point, it suppresses adsorption temperature spikes, maintaining the bed within the optimal adsorption temperature range (approximately 60°C), thus mitigating the problem of capacity reduction due to adsorption exothermics at its source. This invention converts adsorption exothermics into a recoverable heat source, which is recovered through a heat exchanger and then heated by a low-temperature heat pump for regeneration of the desorption bed, achieving a closed-loop enhancement of "adsorption exothermics – heat storage – regeneration exothermics". Simultaneously, the dual fixed-bed configuration allows adsorption and desorption to operate alternately or in parallel in different beds. Combined with the cyclic heat exchange of the phase change capsules, it achieves the "transportation" and stable supply of heat in time and space, thereby improving system stability and scale-up feasibility.

[0033] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A dual fixed-bed CO2 capture system with phase change capsule cycle thermal management, characterized in that: It includes a flue gas collection chamber, a first fixed bed, a second fixed bed, a capsule heat exchange chamber, a low-temperature heat pump, a first fan, a second fan, a carbon dioxide compressor, and a carbon dioxide storage tank; wherein: The outlet of the flue gas canister to be captured is connected to the main flue gas pipeline in sequence through the flue gas canister throttle valve. The main flue gas pipeline is connected to the lower inlet of the first fixed bed and the second fixed bed through the first fixed bed flue gas throttle valve and the second fixed bed flue gas throttle valve respectively, so that the flue gas to be captured is adsorbed from bottom to top through the fixed bed. The first fixed bed and the upper part of the second fixed bed are respectively connected to the first heat exchanger and the second heat exchanger, and are controlled to open and close through the throttling valve on the first fixed bed and the throttling valve on the second fixed bed; the gas after heat exchange enters the carbon dioxide compressor through the throttling valve of the carbon dioxide compressor for compression, and the compressed carbon dioxide enters the carbon dioxide storage tank for storage, and the storage tank is connected to the system through the throttling valve of the carbon dioxide storage tank. The lower parts of the first fixed bed and the second fixed bed are respectively provided with independent carbon dioxide gas channels and capsule solid channels. The carbon dioxide throttling valves under the first and second fixed beds are connected in parallel to the carbon dioxide storage tank through the carbon dioxide storage tank throttling valve, which is used to introduce carbon dioxide gas into the corresponding fixed bed for purging and regeneration during the desorption stage. The capsule throttling valves under the first and second fixed beds are connected in parallel to the capsule heat exchange chamber, which is used to control the flow of phase change capsules between the fixed bed and the capsule heat exchange chamber. The capsule heat exchange chamber is connected to the capsule channels of the two fixed beds through the left valve and the right valve of the capsule heat exchange chamber, respectively, for heat recovery from the high-temperature capsules from the desorption bed; The capsule heat exchange chamber is connected to a low-temperature heat pump, and the heat is transferred to the low-temperature heat pump after heat exchange. The low-temperature heat pump forms a closed heat cycle with the system through the right valve and the left valve of the low-temperature heat pump. The dotted line represents the energy transfer loop. The recovered heat is raised to a higher temperature and then transported to the fixed bed in the desorption state to provide heat for desorption and regeneration. The first fan and the second fan are connected to the upper end of the two fixed beds through the first fan throttle valve and the second fan throttle valve, respectively. They are also connected to the left valve and the right valve of the capsule heat exchange chamber, respectively. After adsorption is completed, the phase change capsules in the fixed bed can be blown to the capsule heat exchange chamber, and in the next cycle stage, the heat-exchanged capsules can be transported to another fixed bed.

2. The carbon dioxide capture process using the system described in claim 1, characterized in that, Includes the following steps: (1) Constructing a dual fixed-bed adsorption system: Set up at least two alternating fixed-bed reactors, namely the first fixed bed and the second fixed bed, with honeycomb structured packing coated with potassium-based adsorbent in the bed; the system is equipped with flowable phase change capsules and heat pump units for heat recovery and upgrading; (2) Isothermal adsorption and in-situ heat storage: CO2-containing flue gas is introduced into the first fixed bed in the adsorption state, and at the same time, the phase change capsules in the cooling state are introduced into the honeycomb channels or gaps of the fixed bed; the potassium-based adsorbent captures CO2 and releases the heat of reaction, and the phase change capsules absorb the heat of reaction in-situ through solid-liquid phase change, controlling the bed temperature within the preset adsorption temperature range; (3) Capsule separation and heat removal: When the first fixed bed is saturated or the phase change capsule has completed the phase change, the phase change capsule carrying latent heat is separated from the first fixed bed and discharged to the external capsule heat exchange chamber; (4) Heat release and capsule regeneration: In the capsule heat exchange chamber, the phase change capsule releases latent heat to the evaporation side of the heat pump system and returns to the solid-state cooling state, and then returns to the adsorption step for recycling; (5) Heat pump temperature rise and adsorbent regeneration: The heat pump unit uses the consumed electrical energy to raise the low-grade heat recovered from the phase change capsule to the regeneration temperature and transports it to the second fixed bed in the desorption state, driving the potassium-based adsorbent to decompose and release high-concentration CO2, thereby realizing adsorbent regeneration.

3. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, The honeycomb structured filler in step (1) is a silica honeycomb monomer, and the inner wall of its pores is coated with a K2CO3 / Al2O3 composite adsorbent; the mass ratio of K2CO3 to Al2O3 in the composite adsorbent is (3-5):

3.

4. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 3, characterized in that, The coating method includes: mixing K2CO3 with aluminum sol to prepare a slurry, coating the slurry into the pores of a honeycomb carrier, and then drying and calcining it to form a shape; the coating is performed twice.

5. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, The phase change capsule described in step (1) is a core-shell structured microcapsule with a core material of paraffin and a phase change temperature set at 50-70℃, which matches the optimal adsorption activity temperature of the potassium-based adsorbent; the shell material is silicon dioxide or PMMA.

6. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, In step (2), the preset adsorption temperature is 60±2℃; by adding phase change capsules to absorb the exothermic adsorption reaction, near-isothermal adsorption is achieved.

7. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, The capsule separation method described in step (3) utilizes the difference in flowability between phase change capsules and fixed-bed honeycomb packing, including one or more combinations of gravity sedimentation separation and pneumatic purging separation; the honeycomb structured packing is fixed, and the phase change capsules flow through the honeycomb channels or in the gaps between the packing as the mobile phase.

8. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, In step (5), the heat pump unit raises the heat from a low temperature of 60±2℃ to a high temperature of 100-150℃; the heat pump unit is a compression heat pump or an absorption heat pump.

9. The dual fixed-bed CO2 capture process with phase change capsule circulating thermal management according to claim 2, characterized in that, The high-concentration CO2 produced by desorption is collected and used as industrial feed gas for methanol synthesis or supplied externally as a protective gas.

10. The dual fixed-bed CO2 capture system with phase change capsule circulating thermal management according to claim 1, characterized in that, The system also includes a heat management control unit, which monitors the bed temperature distribution and capsule outlet temperature in real time, and maintains the system's thermal balance by adjusting the power of the heat pump compressor and the speed of the capsule circulation pump through frequency conversion.

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