A liquid-liquid-solid three-phase system continuous device for capturing co2 and method of use

Abstract

The application discloses a kind of continuous device and use method with reaction and separation function integration, for homogeneous solution absorption CO2 Generation liquid-liquid-solid three-phase phase change system self-control separation.The device mainly includes a homogeneous absorbent and the reaction phase change unit of contact with CO2 Gas, a liquid-liquid-solid three-phase separation unit and a self-control unit for maintaining phase interface balance.Reaction phase change unit can realize gas-liquid phase parallel flow sufficient reaction and phase change transfer process occurs at the top of reaction tower, and gas is purified;Phase separation unit makes the system separate entrained gas in falling liquid stable region, and solid phase slurry, lower liquid phase and upper liquid phase are discharged by pump or overflow device, and recycled after regeneration and mixing;Stable three-phase interface is realized by the self-control unit of light intensity and pressure difference signal feedback.The application realizes that reaction absorption and phase transfer three-phase separation are continuously carried out in integrated device, equipment operation is simple, compact structure, shorten process flow, and can greatly reduce carbon capture cost.

Description

Technical Field

[0001] This invention belongs to the field of gas separation or purification technology based on chemical phase change absorption, specifically relating to a continuous liquid-liquid-solid three-phase system device and its usage method for capturing CO2. Background Technology

[0002] Since the beginning of the 20th century, rapid urbanization and industrial capacity have had a significant impact on the climate, including global warming and ocean acidification caused by massive carbon dioxide emissions. In 2022, the 27th Conference of the Parties to the United Nations Framework Convention on Climate Change adopted the Sharm el-Sheikh Implementation Plan, reiterating the long-term goal of the Paris Agreement to limit the rise in global average temperature to well below 2°C above pre-industrial levels. It also emphasized that, given the current situation where fossil fuels cannot be completely abandoned, carbon capture technology is a key technological means to achieve the Paris Agreement's temperature control goals.

[0003] Chemical solvent absorption is one of the more mature industrial methods for CO2 enrichment. Essentially, this method involves the chemical reaction between an alkaline solution and CO2 gas for absorption, followed by high-temperature desorption to achieve CO2 enrichment and solvent regeneration. Currently, alkanolamine solutions and organic amine solutions are widely used to treat CO2 emissions from large stationary sources such as power plants, oil refineries, chemical plants, and cement plants. However, due to the high water content of these absorbents, the sensible heat and latent heat of vaporization during high-temperature desorption consume a large amount of heat, resulting in high energy consumption for capture and regeneration. The high cost of capture is a major factor restricting the large-scale industrial application of traditional carbon capture technologies globally.

[0004] To reduce energy consumption and capture costs in the CO2 regeneration process, CO2 capture technology using phase change absorbents has attracted widespread attention and favor from researchers. Compared with traditional alkanolamine absorbents and organic amine absorbents, the advantages of phase change absorbents are: as the amount of CO2 absorbed by the absorbent in the gas phase increases, the solution load increases, and the homogeneous absorbent will gradually transform into a CO2-rich phase and a CO2-poor phase. If the CO2 content in the poor phase is low, it can be directly recycled. Only the CO2-rich phase needs to be desorbed to achieve solvent regeneration and recycling, thus significantly reducing the amount of regeneration solution and solvent vaporization, thereby reducing the energy consumption of the regeneration system.

[0005] Currently, phase change absorbent systems mainly include mixed amine systems, mixed amine-organic solvent systems, organic amine-organic solvent-water systems, and amino acid salt-organic solvent-water systems. Under specific conditions, these systems can transform from homogeneous solutions into liquid-liquid, liquid-solid, or liquid-liquid-solid phase systems. Notably, among these phase change systems, liquid-liquid-solid three-phase phase change absorbents exhibit lower regeneration energy consumption and better water balance control in treating wet flue gas, demonstrating significant application potential. Current research primarily focuses on process validation and energy consumption assessment. However, the development of proprietary equipment for treating phase change systems, involving multiphase reactions and separations, differs significantly from traditional processes and equipment, and there is a lack of reports on such development. Liquid-liquid phase change absorbents are mainly organic amine systems. Although they have low energy consumption and can be referenced from traditional phase separation equipment, they still suffer from problems such as poor phase stability, complex phase composition, and solvent loss due to organic amine degradation and escape. Liquid-liquid-solid systems based on ionic alkali metal salt systems have significant advantages. Their processes can generally be completed step-by-step by absorption equipment to achieve phase transfer, transport of the multiphase system, and phase separation of the liquid-liquid-solid system. However, this process has problems such as long flow, complex operation, and susceptibility to failure of multiphase system transport equipment. Therefore, developing equipment and process technologies suitable for liquid-liquid-solid phase change absorbents is of great significance for promoting the development and industrial application of carbon capture technology. Currently, publicly available carbon dioxide capture systems or equipment for phase change absorbents are limited to systems undergoing liquid-liquid or liquid-solid phase changes, and the phase change and phase separation processes are completed in different devices. The system processes are complex, increasing the difficulty of operation and capture costs, and cannot achieve integrated and optimized treatment of liquid-liquid-solid three-phase phase change systems.

[0006] To this end, we propose a continuous device and method for using liquid-liquid-solid three-phase systems, which is an integrated automatic control device that integrates processes such as reaction absorption, phase transfer, and phase separation, and achieves low-energy and high-efficiency CO2 capture. Summary of the Invention

[0007] The purpose of this invention is to provide a continuous liquid-liquid-solid three-phase system device and method for capturing CO2, so as to solve the shortcomings and deficiencies of the prior art mentioned in the background art. At the same time, it proposes to integrate the three steps of CO2 absorption reaction, liquid-liquid-solid phase transfer process and three-phase separation into an integrated device for continuous operation, so as to achieve simple operation, compact structure and shorten process flow, thereby solving the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a continuous liquid-liquid-solid three-phase system device for capturing CO2, characterized in that the device includes a reaction phase change unit in which a homogeneous absorbent contacts a CO2-containing gas, a liquid-liquid-solid three-phase separation unit, and an automatic control unit for maintaining phase interface equilibrium.

[0009] The phase change reaction unit includes an absorption reaction tower, an absorbent storage tank, a liquid inlet pump, a liquid distributor, a gas disperser, and a CO2 analyzer. The reaction tower is a cylindrical tower section placed inside the phase separator and not sealed at both ends. Its height is determined by the CO2 gas throughput and the characteristics of the phase change absorbent used. The gas disperser is an adjustable rotating disk with an aperture of 5-50 micrometers, placed at the bottom of the reaction tower. The annular gap area between the disk disperser and the reaction tower is 1 / 10 to 1 / 8 of the cross-sectional area of ​​the reaction tower. The liquid distributor is an annular pipe with an inner opening, located 50-200 mm above the gas disperser. The aperture size varies to ensure uniform distribution of the outflowing liquid.

[0010] The three-phase separation unit includes a phase separator, a downcomer, a liquid phase diversion baffle, an upper liquid phase overflow outlet, a lower liquid phase outlet and a lower liquid phase pump, a solid phase slurry outlet and a screw pump; the phase separator is a cylindrical tower with a tapered bottom, the cone angle being 30~60 degrees. o The bottom is connected to the first inlet of an adjustable-speed screw pump; the downcomer is connected to the top end cap of the phase separator and forms an open annular cavity with the phase separator cylinder, the height of which is 1 / 8 to 1 / 3 of the height of the reaction tower. The top is provided with a balance vent hole. An overflow liquid downflow annular channel is formed between the annular cavity wall and the inner side of the reaction tower body. The outer diameter of the channel is 1.3 to 1.8 times the diameter of the reaction tower; the liquid phase diversion baffle is an arc-shaped baffle that forms a liquid phase stabilization zone with the phase separator cylinder. After being discharged by the pump, the liquid enters the second inlet of the screw pump.

[0011] The stabilized phase interface automatic control unit includes a laser emitter-receiver device, a differential pressure transmitter installed at the liquid outlet and the top of the tower, a differential pressure transmitter installed at the slurry outlet and the top of the tower, and frequency converters for the lower liquid phase and slurry pumps. It controls the feed pump to maintain the phase change process at the top of the reaction tower through the laser system light intensity signal, and maintains the stability and continuous operation of the liquid-liquid-solid three-phase interface through differential pressure signal feedback to the delivery pump.

[0012] As a further preferred embodiment of the present invention, the absorption reaction tower comprises two parts: a fixed section and an adjustable height section. The height of the adjustable section is adjusted by a movable sleeve and a traction motor, and the adjustable height is 1 / 10 to 1 / 5 of that of the fixed height section.

[0013] As a further preferred embodiment of the present invention, the laser emission-receiver device is installed outside the phase separator and 50-100 mm below the upper liquid phase outlet, and a coaxial glass sight glass is installed in the horizontal direction of the phase separator, the downcomer and the reaction tower.

[0014] In addition, the present invention provides a method for using a continuous liquid-liquid-solid three-phase system device for capturing CO2, characterized in that the absorbent used in the absorbent storage tank of the device is a homogeneous solution, which may include one of the following systems: amino acid salt-organic solvent-water or organic amine-organic solvent-water. After absorbing CO2, it can undergo a phase change to form a liquid-liquid-solid three-phase system, and after being regenerated and desorbed from CO2, it can be mixed with the upper liquid phase to restore it to a homogeneous solution.

[0015] The present invention provides a method for using a continuous liquid-liquid-solid three-phase system device for capturing CO2, comprising the following steps:

[0016] Phase change absorption is achieved through gas-liquid co-flow reaction: Gas containing a certain concentration of CO2 enters the bottom of the absorption reaction tower through a bottom rotating gas disperser. The homogeneous liquid in the absorbent storage tank is pumped into a circular liquid distributor by a feed pump. The absorbent flows into the reaction tower through the inner channel of the circular ring and comes into contact with the rising microbubbles in a co-flow. It fully absorbs CO2 as it moves upward along the reaction tower section. By adjusting the gas-liquid flow rate and the height of the adjustable section of the reaction tower, a phase transfer process occurs at the top outlet of the reaction tower. The phase change process can be fed back by the light intensity signal of the installed laser emission-reception device. The purified gas is discharged from the device after being detected by a CO2 analyzer.

[0017] Separating entrained gas using an overflow downcomer annular channel: The solution that undergoes phase change at the top of the reaction tower to form a liquid-liquid-solid system flows downward through the overflow into the downcomer annular channel of the phase separator, while simultaneously separating the entrained gas phase in the system;

[0018] Sedimentation separation is achieved through the main chamber of the phase separator: After the system enters the main chamber of the phase separator through the annular channel descending zone, the channel cross-section increases and sedimentation separation occurs. The upper liquid phase enters the annular chamber, and tiny bubbles are discharged from the top of the chamber through the balance vent. The upper liquid phase is continuously discharged through the overflow device and directly returned to the absorbent storage tank for recycling. The lower liquid phase, which has a stable interface, is discharged by a pump through a liquid phase diversion baffle and enters the second inlet of the screw pump. The pump flow rate is controlled by the pressure difference signal installed at the liquid phase outlet and the top of the tower. The solid-containing slurry is discharged through the spiral outlet at the bottom of the conical tower. The slurry discharge rate is determined by the motor screw speed controlled by the liquid surface pressure difference signal, thus maintaining the stability of the phase interface.

[0019] The desorption effect is improved by using a spiral mixing mechanism to mix the lower liquid phase and the solid-containing slurry into the regenerator: the solid-containing slurry and the lower liquid phase enter the first and second inlets of the spiral pump respectively, are fully mixed in the pump chamber and continuously output to the regenerator. The slurry with high CO2 load and the lower liquid phase desorb CO2 in the system in the regenerator by heating with steam, microwave or electric heating to obtain CO2 gas with high purity. The homogeneous solution with low CO2 load obtained at the regenerator outlet is discharged into the absorbent storage tank.

[0020] Phase change absorbent circulation: The regenerated solid slurry and the lower liquid phase (i.e., the homogeneous solution with low CO2 load) are thoroughly mixed with the upper liquid phase, and the absorbent system is restored to a single homogeneous solution, which is then fed into the reaction tower by the feed pump for recycling as a phase change absorbent.

[0021] The present invention provides a continuous liquid-liquid-solid three-phase system device and method for capturing CO2, which has the following beneficial effects and advantages compared with the prior art:

[0022] (1) The device integrates three steps, namely CO2 absorption reaction, liquid-liquid-solid phase transfer process and three-phase separation, into one integrated device, which has a compact structure and shortens the process flow.

[0023] (2) The height of the absorption reaction tower of the device is adjustable within a certain range based on the laser light intensity signal, ensuring that the phase change transfer process takes place at the top of the reaction tower under different operating conditions, and the phase change process is easy to adjust.

[0024] (3) The device is equipped with a stable phase interface automatic control unit, which can maintain the stability of the liquid-liquid-solid three-phase interface and operate continuously. The equipment is simple to operate and has a high degree of automation.

[0025] (4) The lower liquid phase and the solid slurry are mixed by a spiral and then fed into the regenerator to desorb CO2, which improves the stability of the transport process, improves the regeneration effect of the enriched phase, reduces the regeneration energy consumption, and can significantly reduce the carbon capture cost. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in some embodiments are briefly introduced. Obviously, the accompanying drawings described below are only used for describing some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the accompanying drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of a continuous liquid-liquid-solid three-phase system device for capturing CO2 according to the present invention.

[0028] Figure 2 This is a schematic diagram of the top of the fixed section and the adjustable height section of the absorption reaction tower of the present invention.

[0029] Figure 3 This is a schematic diagram of the gas and liquid distributor at the bottom of the absorption reaction tower of the present invention.

[0030] The reference numerals in the attached figures are explained as follows:

[0031] 1- CO2 analyzer, 2- Upper liquid overflow outlet, 3- Laser emitter-receiver device, 4- Absorption reaction tower, 5- Phase separator, 6- Liquid distributor, 7- Absorbent storage tank, 8- Inlet pump, 9- Purified gas outlet, 10- Balance vent, 11- Downcomer, 12- Phase separator annular cavity, 13- Gas disperser, 14- Lower liquid outlet, 15- CO2-containing gas inlet, 16- Slurry outlet (i.e., first inlet of screw pump), 17- Screw pump, 18- Second inlet of screw pump, 19- Lower liquid pump, 20- Liquid phase diversion baffle, 21- Regenerator, 22- Adjustable tower section traction motor, 23- Adjustable section moving sleeve of reaction tower. Implementation

[0032] To provide a clearer understanding of the technical solutions and beneficial effects of the present invention, the technical solutions and implementation methods of the present invention will be further described in detail below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The specific embodiments described herein are merely used to explain the content and implementation methods of the present invention, and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] This invention provides, for example Figure 1-3 The device shown is a continuous liquid-liquid-solid three-phase system device for capturing CO2. The device includes an absorption reaction phase change unit in which a homogeneous absorbent contacts CO2-containing gas, a liquid-liquid-solid three-phase separation unit, and an automatic control unit for maintaining phase interface equilibrium.

[0034] Specifically, the absorption reaction phase change unit of the present invention includes an absorption reaction tower (4), an absorbent storage tank (7), a liquid inlet pump (8), a liquid distributor (6), a gas disperser (13), and a CO2 analyzer (1); the reaction tower is a cylindrical tower section placed inside the phase separator (5) and not closed at both ends, and its height is determined by the amount of CO2 gas to be processed and the characteristics of the phase change absorbent used; the gas disperser (13) is an adjustable rotating stainless steel sintered disc with an aperture of 5 micrometers to 50 micrometers, placed at the bottom of the reaction tower, and the annular gap area between it and the reaction tower is 1 / 10 to 1 / 8 of the cross-sectional area of ​​the absorption reaction tower; the liquid distributor (6) is an annular stainless steel tube with an inner hole, the outer diameter of the stainless steel tube is equal to the inner diameter of the absorption reaction tower, and it is located 50 to 200 mm above the gas disperser (13).

[0035] Specifically, the three-phase separation unit of this invention includes a phase separator (5), a downcomer (11), a liquid phase diversion baffle (20), an upper liquid phase overflow outlet (2), a lower liquid phase outlet (14), a lower liquid phase pump (19), a solid phase slurry outlet (16), and a screw pump (17); the phase separator is a gravity settling cylindrical tower with a tapered bottom, the inclination angle of the bottom cone being 30~60 degrees. o The bottom outlet is connected to the first inlet of the adjustable speed spiral pump (17), and the speed of the spiral pump is controlled by the variable frequency motor; the downcomer is a cylindrical pipe, which is connected to the top end cap of the phase separator. This structure has a dual function: 1) the downcomer and the phase separator cylinder form an open annular cavity (12) at the bottom, the height of which is 1 / 8 to 1 / 3 of the height of the reaction tower. The top is provided with a balance vent hole (10) for the liquid phase in the three-phase system to clarify and separate and for the tiny bubbles to gather and escape; 2) the downcomer wall and the inner side of the reaction tower form an annular channel for the phase change solution to overflow and settle for primary separation and entrainment of the gas phase. The outer diameter of the downcomer is 1.3 to 1.8 times the diameter of the reaction tower; the liquid phase diversion baffle (20) is an arc-shaped baffle that forms a phase interface stability zone with the phase separator cylinder. The lower liquid phase, i.e. the intermediate phase liquid, is discharged by the pump and enters the second inlet (18) of the spiral pump.

[0036] Specifically, the phase interface self-control unit of the present invention includes a laser emitter-receiver device (3), a differential pressure transmitter installed at the liquid outlet (14) and the top of the tower, a differential pressure transmitter installed at the slurry outlet (16) and the top of the tower, and frequency converters for the lower liquid phase and slurry pumps. The feed pump (8) is controlled by the light intensity signal of the laser system to maintain the phase change process at the top of the reaction tower, and the liquid-liquid-solid three-phase interface is kept stable and continuously operated by the differential pressure signal feedback pump.

[0037] As a further preferred embodiment of the present invention, the absorption reaction tower (4) comprises two parts: a fixed section and an adjustable height section (23). The adjustable section is a movable sleeve installed on the top of the cylindrical fixed section. The adjustable height is achieved by the movable sleeve (23) and the traction motor (22). The adjustable height is 1 / 10 to 1 / 5 of the fixed height section.

[0038] As a further preferred embodiment of the present invention, the laser emission-receiver device is installed outside the phase separator and 50-100 mm below the upper liquid phase outlet, and a coaxial glass sight glass is installed in the horizontal direction of the phase separator, the downcomer and the reaction tower.

[0039] The specific specifications, proportions, and models of the device components involved in the embodiments of this invention are as follows:

[0040] The nominal diameter ratio of the absorption reaction tower (4), the downcomer (11), and the phase separator (5) is 2:3:4;

[0041] The ratio of the height of the downcomer to the height of the reaction tower is 1:4;

[0042] The height of the absorption reaction tower (4) is adjustable to 1 / 8 of the height of the fixed section;

[0043] The model of the screw pump (17) is: GPG-GDM-1800RPM, made of polytetrafluoroethylene;

[0044] The models of the liquid pumps (8 and 19) are: MG-XK magnetic drive gear pump, gear material PEEK;

[0045] The laser emitter-receiver device (3) is model TP100, with a wavelength of 350-1100nm and a power of <100mW;

[0046] The differential pressure transmitter model is: 3151 series intelligent differential pressure transmitter, 4-20mA;

[0047] The specifications of the CO2 analyzer (1) are: online infrared gas analyzer 0-100% CO2;

[0048] The model of the liquid distributor (6) is: stainless steel circular tube with an inner hole, and the diameter range of the gradually changing hole is 2-6mm;

[0049] The gas disperser (13) is a stainless steel sintered disc with an aperture of approximately 15 micrometers.

[0050] The present invention also provides a method of using a continuous liquid-liquid-solid three-phase system device for capturing CO2. Specifically, the method is implemented in the above-mentioned continuous liquid-liquid-solid three-phase system device. The absorbent used in the absorbent storage tank (7) of the device is a homogeneous absorbent solution, which may include a system of amino acid salt-organic solvent-water or organic amine-organic solvent-water. After absorbing CO2, it can undergo a phase change to form a liquid-liquid-solid three-phase system. Moreover, after desorbing CO2 by the regenerator (20) and mixing with the upper liquid phase, it can be restored to a homogeneous solution.

[0051] Specifically, the homogeneous absorbent solution of this invention can be one of the following systems: a water-deficient potassium glycine / dimethyl sulfoxide solution, a water-deficient potassium proline alcohol ether solution, or an organic polyamine / piperazine / alcohol solution.

[0052] Specifically, the present invention provides a method for using a continuous liquid-liquid-solid three-phase system device for capturing CO2, comprising the following steps:

[0053] Phase change absorption by gas-liquid co-flow reaction: Gas containing a certain concentration of CO2 enters the bottom of the absorption reaction tower (4) through the bottom rotating gas disperser (13). Liquid in the absorbent storage tank (7) is pumped into the annular liquid distributor (6) by the feed pump. The absorbent flows into the inner body of the reaction tower through the inner hole of the annular liquid distributor and comes into contact with the rising microbubbles in parallel flow. It fully absorbs CO2 along the upper part of the reaction tower. By adjusting the gas-liquid flow rate and the height of the adjustable section of the reaction tower, the absorbent undergoes a phase transfer process at the top outlet of the reaction tower. The phase change process can be fed back by the light intensity signal of the installed laser emission-receiver device (3). The purified gas is discharged from the device after being detected by the CO2 analyzer (1).

[0054] Separating entrained gas using the overflow downcomer annular channel: The solution that undergoes phase change at the top of the absorption reaction tower (4) to form a liquid-liquid-solid system flows downward through the overflow into the downcomer annular channel of the phase separator, while simultaneously separating the entrained gas phase in the system;

[0055] Sedimentation separation using the main chamber of the phase separator: After the system enters the main chamber of the phase separator from the annular channel descending zone, the channel cross-section increases and sedimentation separation occurs. The upper liquid phase enters the annular chamber (12), and tiny bubbles are discharged from the top of the chamber through the balance vent (10). The upper liquid phase is continuously discharged through the overflow device and directly returned to the absorbent storage tank (7) for recycling. The lower liquid phase with a stable interface is discharged by the pump through the liquid phase diversion baffle (20) and enters the second inlet (18) of the screw pump. The pump flow rate is controlled by the pressure difference signal between the liquid phase outlet (14) and the top of the tower. The solid slurry is discharged through the conical bottom outlet (16) by a screw. The slurry discharge speed is determined by the motor screw speed controlled by the liquid surface pressure difference signal, maintaining the stability of the phase interface.

[0056] The desorption effect is improved by using a spiral mixing mechanism to mix the lower liquid phase and the solid slurry into the regenerator: the solid slurry and the lower liquid phase enter the first and second inlets of the spiral pump (17) respectively, are fully mixed in the pump chamber and continuously output to the regenerator. The slurry with high CO2 load and the lower liquid phase desorb CO2 in the system in the regenerator by heating with steam, microwave or electric heating to obtain CO2 gas with high purity. The homogeneous solution with low CO2 load obtained at the regenerator outlet is discharged into the absorbent storage tank.

[0057] Phase change absorbent circulation: The regenerated solid slurry and the lower liquid phase (i.e., the homogeneous solution with low CO2 load) are thoroughly mixed with the upper liquid phase, and the absorbent system is restored to a single homogeneous solution. It is then fed into the reaction tower by the feed pump (8) for circulation as a phase change absorbent.

[0058] The above descriptions are merely some specific embodiments of the technical features of the present invention, and not all embodiments, and therefore should not be construed as limiting the scope of implementation of the present invention. Once those skilled in the art obtain the basic inventive concept of the present invention, they can make other changes and modifications to these embodiments. Therefore, any modifications, equivalent substitutions, or alterations made by those skilled in the art within the spirit and technical scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A liquid-liquid-solid three-phase system continuous device for capturing CO2, characterized in that, The device comprises a reaction phase change unit in which a homogeneous absorbent contacts CO2 gas, a liquid-liquid-solid three-phase separation unit, and a self-control unit for maintaining phase interface balance; The reaction phase change unit comprises an absorption reaction tower (4), an absorbent storage tank (7), a liquid inlet pump (8), a liquid distributor (6), a gas disperser (13), and a CO2 analyzer (1); the reaction tower is a tower section placed inside the phase separator (5) and not closed at both ends, and its height is determined by the gas processing capacity and the characteristics of the phase change absorbent; the gas disperser (13) is a rotating disc with a pore size of 5-50 microns and adjustable rotating speed, which is placed at the bottom of the reaction tower, and the annular area between the reaction tower and the gas disperser is 1 / 10-1 / 8 of the cross-sectional area of the reaction tower; the liquid distributor (6) is a circular ring with holes on the inner side, and is located 50-200 mm above the gas disperser (13); The three-phase separation unit comprises a phase separator (5), a downcomer (11), a liquid phase shunt baffle (20), an upper liquid phase overflow outlet (2), a lower liquid phase outlet (14) and a lower liquid phase pump (19), a solid phase slurry outlet (16) and a screw pump (17); the phase separator is a cylindrical tower body with a taper at the bottom, the taper angle is 30-60 o The bottom is the first inlet of the adjustable speed screw pump (17) connected with the solid phase slurry outlet (16); the downcomer is connected with the top head of the phase separator and forms an open annular cavity (12) at the lower part of the phase separator cylinder, the height of the cavity is 1 / 8-1 / 3 of the height of the reaction tower, the top is provided with a balance vent hole (10), the annular cavity wall and the inner side of the reaction tower body form an overflow liquid descending annular channel, the outer diameter of the channel is 1.3-1.8 times of the diameter of the reaction tower; the liquid phase shunt baffle (20) is an arc baffle which forms a liquid phase stabilization zone with the phase separator cylinder, and the liquid is discharged into the second inlet (18) of the screw pump after being pumped out; The phase interface self-control unit comprises a laser emission-receiving device (3), a differential pressure transmitter installed at the lower liquid phase outlet (14) and the top of the tower, a differential pressure transmitter installed at the slurry outlet (16) and the top of the tower, a lower liquid phase and slurry pump frequency converter, and a laser system light intensity signal for controlling the feed pump (8) to maintain the phase change process at the top of the reaction tower, and a differential pressure signal feedback for conveying the pump to maintain the liquid-liquid-solid three-phase interface stable and continuous operation.

2. The liquid-liquid-solid three-phase system continuous device for capturing CO2 according to claim 1, characterized in that, The absorption reaction tower (4) comprises a fixed section and an adjustable height section (23), and the adjustable height section is realized by a movable sleeve (23) and a traction motor (22), and the adjustable height is 1 / 10-1 / 5 of the fixed height section.

3. A method of use of a liquid-liquid-solid three-phase system continuous apparatus for capturing CO2, characterized in that, The method is realized by using the liquid-liquid-solid three-phase system continuous device for capturing CO2 according to claims 1-2, characterized in that the absorbent used in the absorbent storage tank (7) is a homogeneous absorbent solution, which can include one of the systems of amino acid salt-organic solvent-water, organic amine-organic solvent-water, and after absorbing CO2, the system generates a phase change to form a liquid-liquid-solid three-phase system, and after desorbing CO2 in the regenerator (20), the system can recover into a homogeneous solution in the absorbent storage tank.

4. A method of using a liquid-liquid-solid three-phase system continuous device for capturing CO2 according to claims 1-3, characterized in that, The method comprises the following steps: The gas-liquid co-current reaction absorption phase change is realized by the following steps: the gas containing a certain concentration of CO2 enters the bottom of the absorption reaction tower (4) from the bottom rotating gas disperser (13), the liquid in the absorbent storage tank (7) is pumped into the circular ring liquid distributor (6) by the feed pump, the absorbent flows into the reaction tower through the inner side hole of the circular ring and co-currently contacts with the rising micro-bubbles, fully absorbs CO2 along the reaction tower section upward, and by adjusting the gas-liquid flow and the adjustable height of the reaction tower, the absorbent generates a phase transition process at the outlet of the top of the reaction tower; the phase change process can be fed back by the light intensity signal of the installed laser emission-receiving device (3), and the purified gas is discharged after detection by the CO2 analyzer; The overflow downcomer annular channel is used to separate the entrained gas: the solution of the liquid-liquid-solid system formed by the phase change at the top of the reaction tower flows downward in the annular channel downcomer area of the phase separator, and the gas phase entrained in the system is separated at the same time. The system is separated by the main cavity of the phase separator: the system enters the main cavity of the phase separator from the annular channel downcomer area, and is separated by the increase of the channel section. The upper liquid phase enters the annular cavity (12), and the micro-bubbles are discharged from the balance vent hole (10) at the top of the cavity. The upper liquid phase is continuously discharged by the overflow device and directly returns to the absorbent tank for recycling. The lower liquid phase with stable interface is discharged by the pump from the liquid phase outlet (14) and enters the second inlet (18) of the screw pump. The pump flow is controlled by the pressure difference signal between the lower liquid phase outlet (14) and the top of the tower. The slurry containing solid is discharged from the conical tower bottom outlet (16) by screw, and the slurry discharge speed is determined by the motor screw speed controlled by the liquid level pressure difference signal, so as to maintain the stability of the phase interface. The lower liquid phase and the slurry containing solid are mixed by the screw to enter the regenerator to improve the desorption effect: the slurry containing solid and the lower liquid phase enter the first and second inlets of the screw pump (17) respectively, are fully mixed in the pump cavity, and are continuously output to the regenerator. The slurry containing high-load CO2 and the lower liquid phase are desorbed in the regenerator by heating methods such as steam, microwave or electricity to obtain CO2 gas with high purity. The low-load CO2 homogeneous solution is discharged from the regenerator outlet and enters the absorbent tank. The phase change absorbent cycle: the regenerated slurry containing solid and the lower liquid phase, i.e. the low-load CO2 homogeneous solution, are fully mixed with the upper liquid phase, the absorbent system returns to a single homogeneous solution, and is input into the reaction tower by the feed pump (8) as a phase change absorbent for recycling.

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