An apparatus and method for directly capturing carbon dioxide from the air and recovering the capture liquid.

Abstract

This invention relates to the field of carbon dioxide capture technology, and particularly to an apparatus and method for directly capturing carbon dioxide from the air and recovering the capture liquid. The invention utilizes a thin-layer moving bed to spray droplets of a lean capture liquid and achieve carbon dioxide capture through air convection. When the carbonate concentration in the capture liquid reaches a certain value, it is defined as a rich capture liquid. The lean capture liquid is recovered using an electrolytic process. A specific structure and connection relationship achieve good interaction, enabling efficient, rapid, low-energy, and controllable absorption of carbon dioxide from the air under low partial pressure (440–460 ppm). This achieves high-efficiency, large-scale carbon dioxide capture and allows for continuous production of high-purity hydrogen and carbon dioxide products. The capture liquid is reused, realizing an integrated capture and desorption system design. Using 0.5 MkOH as the lean capture liquid, a 600m³… 3 Under the condition of / h induced draft, it is converted into a rich liquid after 13h, and the average CO2 concentration at the outlet is 380ppm, which is 80ppm lower than the CO2 concentration in the inlet air.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of carbon dioxide capture, in particular to a device and method for directly capturing carbon dioxide from air and recovering a capture liquid. BACKGROUND

[0002] Carbon capture and storage and utilization (CCUS) technology is an important strategic choice to achieve the double carbon goal, and has made great progress under the promotion of relevant policies, establishing a large number of industrial-level technology demonstration projects. However, CCUS technology is mainly applied to large fixed carbon sources such as power plants and chemical enterprises, etc., and cannot meet the emission reduction demand of distributed carbon sources with a total emission of nearly 50%. On the other hand, CCUS technology is limited by site selection and cannot achieve flexible on-site storage or resource utilization. The transportation link from capture to backend processing will generate additional costs. In summary, due to the limitations of CCUS technology, a new capture technology is urgently needed to meet the capture and utilization of distributed carbon dioxide.

[0003] Direct air carbon capture (DAC) is an advanced negative carbon technology that directly reduces the concentration of CO2 in the atmosphere. Compared with CCUS, DAC devices have no geographical restrictions and have significant flexibility advantages, but face the challenges of low CO2 concentration in capture efficiency and cost. The CO2 concentration in the air is generally around 440-460 ppm, which is much lower than the CO2 emission concentration of fixed carbon sources (the CO2 concentration in coal-fired power plant flue gas is generally 10-20 vol.%), which puts high requirements on the design of DAC equipment, the adsorption, selectivity and adsorption capacity of adsorbents, etc. In addition, the thermodynamic energy consumption of the DAC process is calculated to be as high as 1.6 GJ / tCO2, which is more than 3 times the energy consumption of coal-fired power plant flue gas CCUS capture. However, alkaline liquid capture not only exhibits good absorption capacity, but also has low electrolysis regeneration energy consumption, which can be coupled with renewable energy to power the system. When using alkaline liquid capture, absorption and electrolysis desorption occur gradually in two units, and if absorption and desorption are concentrated in one unit and performed sequentially, the operation efficiency is higher, which is expected to reduce the system cost.

[0004] However, most of the current research focuses on how to directly reduce more CO2, compared with the slow progress of the integrated system device for absorption and desorption. Patent CN102527191A discloses a carbon dioxide recovery equipment and method, mainly using solution to absorb carbon dioxide, but the equipment has large floor area, resulting in low operability and popularization; Canada Carbon Engineering company also uses solution to absorb carbon dioxide in air, but the regeneration process needs to heat the absorption material to 900 DEG C, and the heat energy consumption is too high. Therefore, the existing DAC technology and application method still have the key bottlenecks of non-compact equipment system, gas mass transfer and recovery reaction selectivity, and need to be improved. SUMMARY

[0005] The purpose of the present application is to solve the problems in the background art, and provide a device and method for directly capturing carbon dioxide from air and recovering capture liquid, which has the characteristics of wide applicability and low cost.

[0006] The technical scheme of the present application is a device for directly capturing carbon dioxide from air and recovering capture liquid, which comprises a collection system and an electrolysis system. The collection system comprises a thin-layer moving bed, an air inlet, a fan and a capture liquid storage tank.

[0007] The capture liquid storage tank is located at the bottom of the thin-layer moving bed, and is filled with capture liquid. One side of the capture liquid storage tank is provided with a pipeline connected to the middle part of the thin-layer moving bed, and the end of the pipeline is provided with a spray head. A water pump and a throttle valve are connected in series on the pipeline. The other side is provided with two spiral conveying pipes connected with the electrolysis system. The fan is installed at the upper part of the thin-layer moving bed.

[0008] The bottom of the thin-layer moving bed is provided with a plurality of air inlets. The fan blows air into the thin-layer moving bed through the air inlets. The water pump and the throttle valve pump out the capture liquid and spray it downward in the middle part of the thin-layer moving bed to capture carbon dioxide in the air. The top of the thin-layer moving bed is provided with an air outlet, and the purified air after capturing CO2 is discharged outward through the air outlet.

[0009] The electrolysis system comprises a power supply and an electrolysis cell. The electrolysis cell comprises a cathode electrolysis cell and an anode electrolysis cell. The cathode electrolysis cell and the anode electrolysis cell are connected in communication, and a proton exchange membrane is arranged at the communication part. A platinum mesh electrode is arranged in the cathode electrolysis cell. An iridium tantalum electrode is arranged in the anode electrolysis cell. Cathode gas outlets and anode gas outlets are reserved on the cathode electrolysis cell and the anode electrolysis cell respectively.

[0010] The power supply is an ITECH power supply, which provides a constant current for the electrolysis cell.

[0011] The anode electrolytic cell is provided with a feeding port, and the cathode electrolytic cell is provided with a discharging port.

[0012] Preferably, a demister is arranged on the air blower, and the demister is fixed on the thin-layer moving bed through flanges.

[0013] Preferably, an air outlet is arranged on one side of the air outlet, and the air outlet is connected with a gas analyzer to detect the concentration of carbon dioxide in the air.

[0014] Preferably, the thin-layer moving bed is made of acrylic material, the shell diameter of the thin-layer moving bed is 220-340 mm, the inner cylinder diameter is 210-330 mm, the thickness is 5 mm, and the total height is 1.6-2.8 m.

[0015] Preferably, the capture liquid in the capture liquid storage tank is potassium hydroxide solution, and the concentration of the solution is 0.5-1 M.

[0016] Preferably, the discharging end of the capture liquid storage tank is provided with an ion spectrum generator for detecting the concentration of carbonate, and the capture liquid is introduced into the electrolytic system when the concentration of carbonate reaches 80% of the initial capture liquid alkali concentration.

[0017] Preferably, the electrolytic cell is an H-shaped electrolytic cell, and the proton exchange membrane is a CMTE homogeneous ion exchange membrane.

[0018] A method for directly capturing carbon dioxide from air and recovering capture liquid, comprising the following specific steps:

[0019] S1, the air blower extracts air vertically through the air inlet into the thin-layer moving bed, and contacts with the capture liquid spray to collect CO2;

[0020] S2, the purified air after capturing CO2 vertically passes through the thin-layer moving bed, and is discharged from the air outlet through the air blower and the demister;

[0021] S3, the capture liquid is sprayed from top to bottom and then enters the capture liquid storage tank, and then the capture liquid is re-introduced into the thin-layer moving bed reaction section through the water pump, the throttle valve and the spray head;

[0022] S4, when the concentration of carbonate reaches 80% of the initial capture liquid alkali concentration, the capture liquid is introduced into the anode electrolytic cell for electrolysis;

[0023] S5, the capture liquid after the CO2 is resolved is injected into the capture liquid storage tank of the thin-layer moving bed for recycling.

[0024] Preferably, the cathode cell solution obtained by electrolysis of the electrolytic cell under a constant current of 300 mA for 2 h is the capture lean liquid.

[0025] Compared with the prior art, the present application has the following beneficial technical effects:

[0026] The device provided by the present application directly captures carbon dioxide at low partial pressure (440-460 ppm) by using a thin-layer moving bed to spray alkali liquor, and recovers the capture liquor by coupling an electrolysis system, thereby realizing continuous, closed-loop, efficient and large-scale application of air carbon capture. The single-stage capture rate of CO2 is 20-25%, the cyclic capture rate is close to 100%, and 100% pure H2 product and CO2 / O2 product can be produced. The capture lean liquor (KOH) is obtained without impurities, avoiding the use of additional chemicals or the generation of chemical waste, and the whole process is environmentally friendly. In addition, through repeated cyclic operation of the electrolysis system, concentrated capture liquor is obtained, which significantly reduces the energy consumption for evaporating the solvent, thereby greatly reducing the energy consumption for producing concentrated capture liquor. At the same time, the device has compact equipment arrangement, small land occupation, no waste solid and waste liquid discharge, and can reduce equipment investment and carbon dioxide capture cost. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a device structure schematic diagram of direct air carbon capture and recovery of capture liquor of the present application;

[0028] Figure 2 is a schematic diagram of the change of CO2 concentration in the outlet air under different air inlet amounts using 0.25M potassium hydroxide capture liquor of the present application;

[0029] Figure 3 is a schematic diagram of the change of CO2 concentration in the outlet air under different air inlet amounts using 0.5M potassium hydroxide capture liquor of the present application;

[0030] Figure 4 is the CO2 concentration range and average value of the outlet air of the thin-layer moving bed of the direct air carbon capture of the present application;

[0031] Figure 5 is the process of electrolysis of the capture liquor and the change of the solution concentration of the present application.

[0032] The drawings show that: 1, air inlet; 2, gas analyzer; 3, pipeline; 4, throttle valve; 6, water pump; 7, air outlet; 8, demister; 9, air induction fan; 10, flange; 11, thin-layer moving bed; 12, spray head; 13, air inlet; 14, capture liquor; 15, ion spectrum generator; 16, ITECH power supply; 17, anode gas outlet; 18, iridium tantalum electrode; 19, anode electrolysis cell; 20, proton exchange membrane; 21, cathode gas outlet; 22, platinum mesh electrode; 23, cathode electrolysis cell. DETAILED DESCRIPTION

[0033] Example 1

[0034] AsFigure 1 As shown, the present invention proposes an apparatus for directly capturing carbon dioxide from the air and recovering the capture liquid, which includes a collection system and an electrolysis system. The collection system includes a thin-layer moving bed 11, an air intake 1, an exhaust fan 9, and a capture liquid storage tank.

[0035] The trapping liquid storage tank is located at the bottom of the thin-layer moving bed 11, and the trapping liquid storage tank is filled with trapping liquid 14; a pipe 3 connected to the middle of the thin-layer moving bed 11 is provided on one side of the trapping liquid storage tank, and a nozzle 12 is provided at the end of the pipe 3; a water pump 6 and a throttle valve 4 are connected in series on the pipe 3; and an induced draft fan 9 is installed on the upper part of the thin-layer moving bed 11.

[0036] Several air inlets 13 are provided at the bottom of the thin-layer moving bed 11; the induced draft fan 9 draws air into the thin-layer moving bed 11 through the air inlets 13; the water pump 6 and the throttle valve 4 draw out the collecting liquid 14 and spray it downward in the middle of the thin-layer moving bed 11 to capture carbon dioxide in the air; the top of the thin-layer moving bed 11 is provided with an air outlet 7, and the purified air after capturing CO2 is discharged to the outside through the air outlet 7.

[0037] In this invention, the collecting liquid 14 in the thin-layer moving bed 11 can be recycled. After the collecting liquid 14 collects CO2 to a certain concentration, it is fed into the electrolysis system for electrolysis. The electrolyzed collecting liquid 14 is then sent back to the thin-layer moving bed 11.

[0038] Example 2

[0039] like Figure 1 As shown, the electrolysis system includes a power source and an electrolytic cell; the electrolytic cell includes a cathode electrolytic cell 23 and an anode electrolytic cell 19; the cathode electrolytic cell 23 and the anode electrolytic cell 19 are connected, and a proton exchange membrane 20 is provided at the connection point; a platinum mesh electrode 22 is provided in the cathode electrolytic cell 23; an iridium-tantalum electrode 18 is provided in the anode electrolytic cell 19; a cathode gas outlet 21 and an anode gas outlet 17 are respectively reserved on the cathode electrolytic cell 23 and the anode electrolytic cell 19.

[0040] The power supply is an ITECH power supply 16, which provides a constant current to the electrolytic cell;

[0041] The anode electrolytic cell 19 is provided with a feed inlet, and the cathode electrolytic cell 23 is provided with a discharge outlet. The feed inlet is connected to the discharge end of the collection liquid storage tank in the thin-layer moving bed 11 through a spiral conveying conduit; the discharge outlet is connected to the feed end of the collection liquid storage tank in the thin-layer moving bed through a spiral conveying conduit.

[0042] In this invention, the electrolysis device is the main equipment for converting the rich solution into the lean solution; the electrolysis device is equipped with a power supply, an electrolysis cell and a gas collection device; wherein, the electrolysis cell is preferably an H-type electrolysis cell, the rich solution is introduced into the anode of the electrolysis cell and electrolyzed, and the lean solution is obtained from the cathode.

[0043] In the embodiment, the diameter of the thin-layer moving bed 11 shell is preferably 220-340 mm; the diameter of the thin-layer moving bed 11 inner cylinder is preferably 210-330 mm; the thickness of the thin-layer moving bed 11 is preferably 5 mm; and the height of the thin-layer moving bed 11 is preferably 1.6-2.8 m. In the embodiment, air is vertically passed through the thin-layer moving bed 11 to adsorb CO2, thereby realizing CO2 capture under the condition of 0.3 kPa-1 kPa ultra-low pressure drop, and an axial flow induced draft fan 9 with large flow and low wind pressure head can be used.

[0044] In the embodiment, the liquid in the capture liquid storage tank can be pumped into the spray head 12 by the water pump 6 through the inlet pipe 3 to capture carbon dioxide in the form of spray. In the present application, the number of spray heads 12 is not unique, and the number can be set without interfering with the working process of each other in the gas-liquid convection space by using methods well known to those skilled in the art. The bottom of the thin-layer moving bed 11 is preferably provided with a discharge port, which is communicated with the feed inlet of the electrolytic cell through a screw conveying pipe.

[0045] In the embodiment, the CO2 capture liquid is preferably a potassium hydroxide solution, and more preferably a commercial product of the Mcrin Company (Shanghai, China); and the CO2 capture liquid is preferably 95% analytically pure, and more preferably 99.99% electronic grade pure. The source of the CO2 capture liquid is not particularly limited, and commercially available products well known to those skilled in the art can be used.

[0046] In the embodiment, the power supply of the electrolytic device is preferably an IT6833A power supply of the ITECH company, and the power supply setting of the electrolytic device is preferably a constant current power supply, including 100 mA, 200 mA and 300 mA. The anode electrode is preferably an IrO2 electrode, and more preferably a 2×3 cm 2 electrode plate. The cathode electrode is preferably a platinum mesh electrode 22, and more preferably a 2.5×2.5 cm 2 electrode plate. The proton exchange membrane 20 is preferably a CMTE homogeneous ion exchange membrane of the Selemion company.

[0047] Embodiment 3

[0048] The present application also provides a method for directly capturing carbon dioxide from air, which uses the device in Embodiment 1 and Embodiment 2, and includes the following steps:

[0049] The air is drawn by the air fan 9 to pass through the air inlet 13 into the thin layer moving bed 11, and contacts the spray of the capture liquid to collect CO2. The purified air after capturing CO2 vertically passes through the thin layer moving bed 11, and is discharged from the air outlet 7 through the air fan 9 and the demister 8. The spray of the alkali liquid is sprayed from top to bottom, and then enters the capture liquid storage tank. The capture liquid 14 is re-introduced into the reaction section of the thin layer moving bed 11 through the water pump 6, the throttle valve 4 and the spray head 12, until the concentration of the carbonate reaches a certain value, and the capture rich liquid is introduced into the electrolytic cell for anode electrolysis. The capture liquid 14 after desorption of CO2 enters the capture liquid storage tank of the thin layer moving bed 11, and is transported to the upper spray head 12 through the water pump 6 and the pipeline 3 for recycling. When the concentration of the carbonate in the capture rich liquid reaches 80% of the initial concentration of the capture liquid alkali, the capture rich liquid is introduced into the electrolysis system. The cathode cell solution obtained by electrolysis of the electrolytic cell under a constant current of 300 mA for 2 hours is the capture lean liquid.

[0050] In the present application, the method for directly capturing carbon dioxide from air is divided into two processes as a whole:

[0051] (1) Absorption process: the air is introduced into the capture device by the air fan 9 (such as the axial flow fan known to those skilled in the art) with high air volume, and is in gas-solid contact with the downwardly sprayed alkali capture liquid, so that the alkali capture liquid is in full contact with the air, and the carbon dioxide is absorbed with high efficiency;

[0052] (2) Electrolysis process: when the concentration of the carbonate in the capture rich liquid reaches 80% of the initial concentration of the capture liquid alkali, the capture rich liquid is introduced into the electrolysis system, and the CO2 is released and the capture lean liquid is recovered by electrolysis.

[0053] In the present application, the inlet air is preferably air containing 200-600 ppm of CO2, and the present application does not have special restrictions on the source thereof. In the present application, after the above-mentioned absorption process, the purified air containing 100-400 ppm of CO2 vertically passes through the thin layer moving bed 11, and is discharged from the top through the air fan 9.

[0054] Example 4

[0055] Please refer to Figures 2-3 , Figure 2 A schematic diagram of the change of the CO2 concentration in the outlet air under different air inlet volumes using 0.25M potassium hydroxide capture lean liquid is provided for the embodiment of the present application; Figure 3 A schematic diagram of the change of the CO2 concentration in the outlet air under different air inlet volumes using 0.5M potassium hydroxide capture lean liquid is provided for the embodiment of the present application;

[0056] The 1L sample was taken at the end of each hour, the 2 THA100S infrared gas analyzer was fed with 250ml / min air, and the CO2 concentration data was measured for 4 minutes. It was found that, at the same alkali concentration, the higher the wind speed, the shorter the capture time; at the same wind speed, the higher the alkali concentration, the longer the time to reach the same absorption level. And all the capture effects follow a rule, the initial CO2 capture level in the air is limited by the lower bicarbonate concentration in the capture liquid, and the CO2 capture level increases with time, but in the last 2 hours, due to the low concentration of alkali, it cannot achieve a high CO2 capture level.

[0057] Please refer to Figure 4 , Figure 4 The CO2 concentration range and weighted average value at the outlet of the device under various concentration parameters and wind speed parameters. In the present application, 0.5M potassium hydroxide capture liquid 14 per liter can collect 9-11g of CO2. The device provided in the present application realizes the continuous operation of the process of capturing carbon dioxide from air to produce capture liquid, and the CO2 capture rate is 70%-90%, and the purity of the produced CO2 product is 50%-60%.

[0058] Example 5

[0059] Please refer to Figure 5 , Figure 5 A capture liquid electrolysis image provided by the embodiment of the present application, the optimal CMTE membrane is selected from four kinds of cation exchange membranes, electrolysis is carried out at 100mA, 200mA and 300mA, the higher the current intensity, the shorter the electrolysis time. Taking the change diagram of the anode and cathode potassium ion concentration of the capture rich liquid electrolyzed at a constant current of 300mA as an example, the potassium ion concentration was measured in the ICP spectrometer after every 30min. It was found that during the whole electrolysis process, the cathode potassium ion concentration increased from 0.01mg / ml to 30mg / ml, and the anode potassium ion concentration decreased from 34mg / ml to 5mg / ml.

[0060] The cathode gas outlet 21 of the electrolysis device is pure H2, and the anode gas of the electrolysis device is an O2 / CO2 gas mixture.

[0061] Example 6

[0062] Under the action of axial flow fan, air containing 462 ppm CO2 is introduced into the thin layer moving bed, and is contacted with downwardly sprayed alkaline trapping liquid for CO2 adsorption. Purified air (containing 380 ppm CO2) after trapping CO2 vertically passes through the draft fan 9 and the demister 8, and is discharged from the air outlet 7 at the top. The trapping rich liquid after absorbing CO2 flows from top to bottom, enters the anode electrolytic cell 19 through the discharge port, the discharge pipe and the screw conveying pipe, and is electrolyzed for 3 h by a constant current of 300 mA. H2, O2 and CO2 are resolved from the trapping rich liquid to realize enrichment. At the same time, H2 is collected from the cathode outlet to obtain H2 product with a purity of 100%. The mixed gas of CO2 and O2 is collected from the anode outlet. The trapping lean liquid after desorption is again introduced into the trapping liquid storage tank through the electrolytic cell discharge port and the screw conveying pipe, is lifted to the spray head 12 by the water pump 6, and is recycled. The utilization rate of the trapping liquid of the device for directly trapping carbon dioxide from air is 97.5%, and the single-pass CO2 trapping rate is 25%.

[0063] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited thereto. Various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A device for recovering a capture fluid from direct capture of carbon dioxide from air, comprising a collection system and an electrolysis system, characterized in that, The collecting system comprises a thin-layer moving bed, an air outlet, an air blower and a trapping liquid storage tank. The trapping liquid storage tank is located at the bottom of the thin-layer moving bed and is filled with trapping liquid. A pipeline connected to the middle part of the thin-layer moving bed is arranged at one side of the trapping liquid storage tank, and a nozzle is arranged at the end of the pipeline. A water pump and a throttle valve are arranged in series on the pipeline. Two spiral conveying pipes connected to the electrolysis system are arranged at the other side of the trapping liquid storage tank. The air blower is installed at the upper part of the thin-layer moving bed. Air inlets are arranged at the bottom of the thin-layer moving bed. The air blower draws air which enters the thin-layer moving bed through the air inlets.

2. A device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, characterized in that, The water pump draws the trapping liquid out and sprays it downward in the middle part of the thin-layer moving bed to trap carbon dioxide in the air.

3. The device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, characterized by, An air outlet is arranged at the top of the thin-layer moving bed, and the purified air after trapping CO2 is discharged outward through the air outlet.

4. The device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, wherein The electrolysis system comprises a power supply and an electrolytic cell.

5. The device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, wherein The electrolytic cell comprises a cathode electrolytic cell and an anode electrolytic cell.

6. The device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, wherein The cathode electrolytic cell and the anode electrolytic cell are connected in communication, and a proton exchange membrane is arranged at the communication position.

7. The device for capturing carbon dioxide from air directly to recover a capture liquid according to claim 1, wherein A platinum mesh electrode is arranged in the cathode electrolytic cell.

8. A method of recovering a capture liquid from direct capture of carbon dioxide from air, characterized by, An iridium tantalum electrode is arranged in the anode electrolytic cell. Cathode gas outlets and anode gas outlets are respectively reserved on the cathode electrolytic cell and the anode electrolytic cell. The power supply is an ITECH power supply which provides a constant current for the electrolytic cell. An inlet is arranged on the anode electrolytic cell, and an outlet is arranged on the cathode electrolytic cell. The inlet is connected to the outlet end of the trapping liquid storage tank in the thin-layer moving bed through a spiral conveying pipe. The outlet is connected to the inlet end of the trapping liquid storage tank in the thin-layer moving bed through a spiral conveying pipe.

9. The method of claim 8, wherein the method further comprises, A demister is arranged on the air blower, and the demister and the air blower are fixed on the thin-layer moving bed through flanges. An air outlet is arranged at one side of the air outlet, and the air outlet is connected to a gas analyzer to detect the concentration of carbon dioxide at the air outlet. The thin-layer moving bed is made of acrylic material. The shell diameter of the thin-layer moving bed is 220-340 mm, the inner cylinder diameter is 210-330 mm, the thickness is 5 mm, and the total height is 1.6-2.8 m. The trapping liquid in the trapping liquid storage tank is potassium hydroxide solution, and the solution concentration range is 0.5-1 M. The outlet end of the trapping liquid storage tank is provided with an ion spectrum generator for detecting the concentration of carbonate. When the carbonate concentration of the trapping liquid reaches 80% of the initial trapping liquid alkali concentration, the trapping liquid is introduced into the electrolysis system. The electrolytic cell is an H-shaped electrolytic cell, and the proton exchange membrane is a CMTE homogeneous ion exchange membrane. The device of any one of claims 1-7 comprises the following specific steps: S1, the air blower draws air to enter the thin-layer moving bed through the air inlets, and the air contacts the trapping liquid spray to collect CO2; S2, the purified air after trapping CO2 vertically passes through the thin-layer moving bed, and is discharged from the air outlet through the air blower and the demister; S3, the trapping liquid is sprayed from top to bottom and then enters the trapping liquid storage tank, and then the trapping liquid reenters the thin-layer moving bed reaction section through the water pump, the throttle valve and the nozzle; S4, when the carbonate concentration reaches 80% of the initial trapping liquid alkali concentration, the trapping liquid is introduced into the anode electrolysis of the electrolytic cell; S5, the trapping liquid after the CO2 is resolved is injected into the trapping liquid storage tank of the thin-layer moving bed for recycling. The cathode cell solution obtained by electrolysis of the electrolytic cell under a 300 mA constant current power supply for 2 h is the trapping lean liquid.

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