Method and system for regenerating carbon dioxide absorption liquid and carbon capture and applications thereof

Abstract

This invention relates to the field of carbon dioxide capture technology, and discloses a method and system for regenerating carbon dioxide absorbent and capturing carbon, as well as their applications. The method includes: regenerating the carbon dioxide absorbent in a regeneration device; returning a portion of the regenerated gas to the regeneration device; and purifying the remaining portion. Specifically, based on the total weight of the regenerated gas, the content of the portion of regenerated gas is 20-90 wt%, and the content of the remaining portion is 10-80 wt%. This method significantly reduces the energy consumption for regenerating the carbon dioxide absorbent and significantly improves the regeneration efficiency. Furthermore, the system uses a heat exchanger instead of a traditional regeneration tower and reboiler, saving equipment space.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, specifically to a method and system for regenerating carbon dioxide absorbent and capturing carbon, and their applications. Background Technology

[0002] The amine method for capturing carbon dioxide from flue gas is currently the most widely used and mature method, but it is currently facing a bottleneck in energy consumption. In recent years, research has focused on novel solvents, including homogeneous absorbents and two-phase absorbents. Homogeneous absorbents are mostly water-based or non-aqueous solvents, and their ability to reduce energy consumption during carbon dioxide regeneration is limited. Two-phase absorbents, also known as phase change absorbents, form two distinct phases after absorbing carbon dioxide: a CO2-rich phase and a CO2-poor phase. This phase change phenomenon allows for absorbent regeneration and recycling by desorbing only the CO2-rich phase, significantly reducing the amount of solvent requiring heating and thus effectively lowering operating costs.

[0003] Furthermore, phase change absorbents exhibit high absorption rates and good cycle stability during absorption, making them more practical and economical for industrial applications. Phase change solvents are mostly non-aqueous systems, characterized by high viscosity in the rich phase and the ability to be regenerated without heating to the system's boiling point. Currently, the regeneration of phase change solvents utilizes catalytic regeneration enhancement commonly used in homogeneous alkanolamine systems and ordinary thermal regeneration methods.

[0004] CN115282732A provides a novel CO2 absorbent that uses an alcohol solvent system instead of a traditional water solvent system. The lower rich phase is desorbed and regenerated by at least one of heating and stripping. The desorption temperature is 80-120℃ and the desorption pressure is 0.8-1.1 bar. CO2 is collected during desorption for later use.

[0005] CN110813059A discloses a novel method for regenerating carbon dioxide capture solvents. By adding a precipitant and a co-precipitant, the rich solution can be regenerated without an external heat source, while simultaneously mineralizing and fixing carbon dioxide. Compared with traditional thermal regeneration processes, this invention has advantages such as low energy consumption, low equipment investment and pump operating costs, and low lean solution temperature.

[0006] CN117619105A provides a method for regenerating a carbon dioxide chemical absorbent, which mainly utilizes a modified catalyst to regenerate the absorbent after it has absorbed carbon dioxide.

[0007] CN102580466B provides a novel high-efficiency carbon dioxide removal and purification system for power plant flue gas. It adopts a two-step carbon dioxide regeneration technology and uses a mixed solvent of ethanolamine and methanol to capture carbon dioxide. This achieves a two-step carbon dioxide regeneration process, which involves methanol removal before regeneration and ethanolamine carbonate regeneration. It makes full use of the waste heat of flue gas and the condensation heat of methanol, reduces regeneration energy consumption, and effectively lowers the regeneration temperature, thus achieving efficient capture of carbon dioxide from power plants.

[0008] CN113198188A provides a falling film reboiler for CO2 desorption, which can improve heat and mass transfer efficiency by forming a uniform film and reducing the thickness of the liquid film, providing steam power for the CO2 desorption process and reducing the regeneration energy consumption of the CO2 capture system.

[0009] CN111203073B discloses a desorption device for a flue gas CO2 capture system. This device, through a variable-diameter desorption tower design, reduces the tower diameter at the top packing section, increases the liquid spray density and empty tower gas velocity, enhances gas-liquid heat transfer, and improves the recovery of latent heat of moisture in the regenerated gas. Simultaneously, the stripping reboiler provided by this invention utilizes film phase change heat transfer, saving space in the desorption tower's gas-liquid separation process, improving the uniformity of the liquid entering the heat exchange tubes, and ensuring the heat exchange efficiency of the falling film reboiler.

[0010] However, existing patented technologies mainly target phase change solvent formulations and traditional regeneration methods such as regeneration towers and reboilers. These methods suffer from problems such as insufficient heat exchange in the rich liquid phase after carbon dioxide absorption and high energy consumption during the regeneration of the lean carbon dioxide absorbent. To address these issues, a method and system for regenerating carbon dioxide absorbent and carbon capture, along with their applications, are needed. Summary of the Invention

[0011] The purpose of this invention is to overcome the problems of high energy consumption and low regeneration efficiency of carbon dioxide absorbent in the prior art, and to provide a method and system for regenerating carbon dioxide absorbent and carbon capture, as well as their applications.

[0012] To achieve the above objectives, the present invention provides a method for regenerating carbon dioxide absorbent, characterized in that the method includes: regenerating the carbon dioxide absorbent in a regeneration device, returning a portion of the regenerated gas obtained after regeneration to the regeneration device, and purifying the remaining portion; wherein, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of regenerated gas is 20-90 wt%, and the content of the remaining portion of regenerated gas is 10-80 wt%.

[0013] A second aspect of the present invention provides a method for carbon capture, characterized in that the method comprises:

[0014] (1) A gas containing carbon dioxide is fed into an absorption device containing a carbon dioxide absorbent liquid, and the absorbent liquid is brought into contact with the absorbent liquid therein; (2) The rich liquid in step (1) is used to regenerate the carbon dioxide absorbent liquid in a regeneration device, and a portion of the regenerated gas obtained after regeneration is returned to the regeneration device, and the remaining portion is purified; wherein, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of the regenerated gas is 20-90 wt%, and the content of the remaining portion of the regenerated gas is 10-80 wt%; the absorbent liquid, the regeneration method, and the regeneration temperature are the same as those described in the first aspect of the present invention.

[0015] A third aspect of the present invention provides a carbon capture system, characterized in that the system includes an absorption device, a phase separator, a regeneration device, and a gas-liquid separator;

[0016] The absorption device is used to send the gas containing carbon dioxide into the absorption device containing carbon dioxide absorption liquid, and contact the gas with the absorption liquid to obtain carbon dioxide absorption liquid.

[0017] The phase separator is connected to the outlet of the absorption device and is used to separate the carbon dioxide absorption liquid to be regenerated.

[0018] The regeneration device is connected to the outlet of the phase separator and is used to regenerate the carbon dioxide absorbent. The regeneration device is equipped with a return pipe so that a portion of the regenerated gas obtained after regeneration is returned to the regeneration device.

[0019] The gas-liquid separator is used to purify the remaining portion of the regenerated gas obtained from the regeneration device.

[0020] The fourth aspect of the present invention provides the application of at least one of the methods described in the first aspect, the second aspect, and the third aspect of the present invention in reducing the regeneration energy consumption of lean regenerated carbon dioxide absorbent.

[0021] The technical solution described above has the following beneficial effects:

[0022] (1) The system provided by the present invention uses a heat exchanger to replace the traditional regeneration tower and reboiler, which saves equipment space and reduces equipment investment.

[0023] (2) The method for regenerating carbon dioxide absorbent provided by the present invention utilizes the heat and stripping capacity of the regenerated gas to supply acid gas for regeneration of the rich liquid; and uses steam condensate to reduce the viscosity of the rich liquid, thereby reducing the difficulty of transporting the solvent in the pump. This significantly reduces the regeneration energy consumption under the same capture rate, and improves the regeneration efficiency and the efficiency of the rich phase transport pump. Attached Figure Description

[0024] Figure 1This is a schematic diagram of a method for regenerating carbon dioxide absorbent in a preferred embodiment of the present invention.

[0025] Figure 2 This is a schematic diagram of the segmented tube heat exchanger in this invention.

[0026] Explanation of reference numerals in the attached figures

[0027] Figure 1 In the middle, 1 is the absorption tower; 2 is the steam-condensate heat exchanger; 3 is the phase separator; 4 is the lean-rich liquid heat exchanger; 5 is the regenerated gas heat exchanger; 6 is the heat pump; 7 is the gas-liquid separator; 8 is the regeneration tower; 9 is the reboiler; a is steam; b is condensate 1; c is condensate 2; Y is a portion of the regenerated gas; Z is the remaining portion of the regenerated gas.

[0028] Figure 2 In the diagram, 1, 2, and X represent the number of distributors. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] As mentioned above, the present invention provides a method for regenerating carbon dioxide absorbent, characterized in that the method includes: regenerating carbon dioxide absorbent in a regeneration device, returning a portion of the regenerated gas obtained after regeneration to the regeneration device, and purifying the remaining portion; wherein, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of regenerated gas is 20-90 wt%, and the content of the remaining portion of regenerated gas is 10-80 wt%.

[0031] In some embodiments of the present invention, preferably, the absorbent is selected from non-aqueous absorbents, and more preferably from solutions formed by organic amines and organic solvents.

[0032] In some embodiments of the present invention, preferably, the organic amine is selected from at least one of organic primary amines, organic secondary amines, and organic tertiary amines, and more preferably from monoethanolamine, diethanolamine, diethylene glycolamine, 1-dimethylamino-2-propanol, n-propanolamine, dimethylethanol, dihydroxyethylethylenediamine, piperazine, N,N-diethylethanolamine, and triethylenetetramine.

[0033] In some embodiments of the present invention, preferably, the organic solvent is selected from at least one of 1,4-dioxane, butanol, 1-propanol, pentanol, ethanol and sulfolane, and more preferably from 1,4-dioxane, ethanol and sulfolane.

[0034] In some embodiments of the present invention, preferably, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of the regenerated gas is 70-85 wt%, and the content of the remaining portion of the regenerated gas is 15-30 wt%.

[0035] In some embodiments of the present invention, preferably, the viscosity of the absorbent at 40°C is 10-7000 mPa·s, more preferably 10-3600 mPa·s.

[0036] In some embodiments of the present invention, preferably, the content of the organic amine is 50-95 wt%, more preferably 60-80 wt%, based on the total weight of the solution.

[0037] In some embodiments of the present invention, preferably, the regeneration method includes regenerating the carbon dioxide absorbent by exchanging heat with steam only through a heat exchanger, without passing through a regeneration tower and a reboiler, to obtain the regenerated carbon dioxide and the regenerated carbon dioxide absorbent.

[0038] In this invention, the steam is selected from a gas phase that can exchange heat with the carbon dioxide absorbent liquid. For example, it can be selected from industrial boilers, thermal power plants and solar steam generators (the steam pressure after de-cooling and depressurization is 0.4 MPa and the temperature is 130°C or above).

[0039] In some embodiments of the present invention, preferably, the regeneration temperature is 95-115°C, more preferably 100-105°C.

[0040] In some embodiments of the present invention, preferably, the purification process involves condensing the remaining portion to 30-50°C. The purification process can be carried out in a regeneration gas separator, such as a gas-liquid separator.

[0041] A second aspect of the present invention provides a method for carbon capture, characterized in that the method comprises:

[0042] (1) A gas containing carbon dioxide is fed into an absorption device containing a carbon dioxide absorbent liquid and brought into contact with the absorbent liquid therein to obtain a carbon dioxide absorbent liquid (rich liquid).

[0043] (2) The rich liquid in step (1) is regenerated in a regeneration device to regenerate carbon dioxide absorbent. A portion of the regenerated gas obtained after regeneration is returned to the regeneration device, and the remaining portion is purified. The content of the portion of the regenerated gas is 20-90 wt%, and the content of the remaining portion of the regenerated gas is 10-80 wt%, based on the total weight of the regenerated gas obtained after regeneration. The absorbent, the regeneration method, and the regeneration temperature are the same as those described in the first aspect of the present invention.

[0044] In some embodiments of the present invention, preferably, the gas containing carbon dioxide (raw material gas) includes 8-16v% CO2, 5-10v% water vapor, 60-90v% nitrogen and 3-7v% oxygen.

[0045] In some embodiments of the present invention, preferably, the temperature of the absorption device is 30-60°C, more preferably 40-50°C.

[0046] In some embodiments of the present invention, preferably, the method for preparing the rich liquid in step (1) includes sending a gas containing carbon dioxide into an absorption device containing a carbon dioxide absorbent, contacting the absorbent therein, drawing out the resulting liquid from the absorption device, and obtaining the rich liquid after heat exchange and phase separation.

[0047] In some embodiments of the present invention, the heat exchange temperature is 60-100°C, preferably 65-95°C.

[0048] In some embodiments of the present invention, the phase separation temperature is 60-100°C, preferably 65-80°C.

[0049] According to a preferred embodiment of the present invention, the method further includes at least one of the following steps:

[0050] a. Separate the material after it comes into contact with the absorbent to separate the carbon dioxide absorbent to be regenerated;

[0051] b. Heat exchange is performed between the separated carbon dioxide absorbent to be regenerated and the regenerated carbon dioxide absorbent.

[0052] c. Return the regenerated carbon dioxide absorbent to step (1) as the absorbent.

[0053] A third aspect of the present invention provides a carbon capture system, characterized in that the system includes an absorption device, a phase separator, a regeneration device, and a gas-liquid separator;

[0054] The absorption device is used to send the gas containing carbon dioxide into the absorption device containing carbon dioxide absorption liquid, and contact the gas with the absorption liquid to obtain carbon dioxide absorption liquid.

[0055] The phase separator is connected to the outlet of the absorption device and is used to separate the carbon dioxide absorption liquid to be regenerated.

[0056] The regeneration device is connected to the outlet of the phase separator and is used to regenerate the carbon dioxide absorbent. The regeneration device is equipped with a return pipe so that a portion of the regenerated gas obtained after regeneration is returned to the regeneration device.

[0057] The gas-liquid separator is used to purify the remaining portion of the regenerated gas obtained from the regeneration device.

[0058] In some embodiments of the present invention, preferably, the system does not include a regeneration tower and a reboiler, and the cooling medium is preferably steam.

[0059] In some embodiments of the present invention, preferably, the regeneration device includes a regeneration gas heat exchanger.

[0060] In some embodiments of the present invention, preferably, the absorption device is an absorption tower. The operating conditions of the absorption device may include countercurrent contact absorption of gas and liquid at atmospheric pressure within a packed tower.

[0061] In some embodiments of the present invention, preferably, a steam-condensate heat exchanger is provided on the pipe connecting the phase separator and the absorption device, for cooling the carbon dioxide absorbent discharged from the absorption device by means of condensate. The phase separation method of the phase separator may include static separation or techniques such as ultrasonication, bubbling, or electric current to promote stratification. The operating conditions may include: a temperature of 50-100℃, preferably 60-80℃; and a time of 5-120 minutes, preferably 10-60 minutes.

[0062] In some embodiments of the present invention, in order to recover heat from the regenerated carbon dioxide absorbent (lean solution), preferably, a lean-rich solution heat exchanger is provided on the pipeline connecting the regeneration device and the phase separator, for exchanging heat between the carbon dioxide absorbent to be regenerated separated by the phase separator and the regenerated carbon dioxide absorbent.

[0063] In some embodiments of the present invention, preferably, a heat pump is provided in the return pipe.

[0064] In some embodiments of the present invention, preferably, the operating conditions of the gas-liquid separator may include: a temperature of 10-80°C, preferably 20-60°C; a time of 5-180 minutes, preferably 10-60 minutes; and the ratio of the volume of the liquid to the total volume of the gas-liquid separator is not greater than 2 / 3.

[0065] In some embodiments of the present invention, preferably, the regenerated gas heat exchanger is selected from a shell-and-tube heat exchanger, and more preferably a segmented shell-and-tube heat exchanger.

[0066] In some embodiments of the present invention, preferably, the segmented tube heat exchanger is divided into 1-6 segments, more preferably 2-4 segments (e.g., ...). Figure 2 (As shown).

[0067] In some embodiments of the present invention, preferably, the absorption tower, steam condensate heat exchanger, phase separator, lean and rich liquid heat exchanger, shell and tube heat exchanger and gas-liquid separator are connected in sequence.

[0068] In some embodiments of the present invention, preferably, the regeneration device is connected to the absorption device, so that the regenerated carbon dioxide absorbent (lean solution) is returned to the absorption device as absorbent.

[0069] The fourth aspect of the present invention provides the application of at least one of the methods described in the first aspect, the second aspect, and the third aspect of the present invention in reducing the regeneration energy consumption of lean regenerated carbon dioxide absorbent.

[0070] The present invention will be described in detail below through embodiments. In the following embodiments, the relative parameters of regeneration energy consumption are calculated by the amount of steam used and the total amount of CO2 in the regeneration gas; the regeneration efficiency is the ratio of the difference in acid gas volume between the rich liquid and the lean liquid to the acid gas volume in the rich liquid; unless otherwise specified, all raw materials are commercially available products, and all devices operate at atmospheric pressure.

[0071] Example

[0072] like Figure 1 As shown, carbon dioxide capture is performed according to the following steps:

[0073] (1) The raw gas (CO2 content is 12.56v%, other components include water vapor 7.85v%, nitrogen 73.9v%, oxygen 5.6v%) is flue gas directly emitted from the chimney. After being washed by the water washing tower, it enters the absorption tower 1. In the absorption tower 1, it is contacted with a non-aqueous solution (a mixture of 60wt% N,N-diethylethanolamine, 30wt% triethylenetetramine and 10wt% pentanol). The contact temperature is 45°C, so that the CO2 in the raw gas is transferred to this solution.

[0074] (2) The carbon dioxide absorbent liquid after absorbing CO2 is drawn out from the bottom of the absorption tower and enters the phase separator 3 (70°C) through the steam condensate heat exchanger 2. The solution stays in the phase separator for 10 minutes. The rich liquid of the absorbent liquid obtained by phase separation enters the lean-rich liquid heat exchanger 4 (the hot end temperature of 4 is 95°C), and then enters the regeneration gas heat exchanger 5 (the number of distributors is X) to exchange heat with steam a (0.4MPa, 130°C) to regenerate CO2 in the rich liquid (the temperature of the regeneration gas heat exchanger 5 is 115°C).

[0075] (3) The regenerated gas portion (proportion Y) is sent back to the heat exchanger 5 via the heat pump 6, and the other portion (proportion Z) is sent to the regenerated gas separator (gas-liquid separator 7) where it is cooled to 40°C by circulating water and the liquid is separated to obtain high-concentration CO2 gas, which is then sent to the compression section.

[0076] (4) The water and solvent obtained from the regenerated gas separator are returned to the lean liquid outlet of the lean-rich liquid heat exchanger. The regenerated lean liquid first recovers heat through the lean-rich liquid heat exchanger, mixes with the lean liquid obtained after phase separation, and then cools down through the lean liquid cooler before being returned to the absorption tower for recycling.

[0077] Comparative Example

[0078] The method of comparison has the following steps:

[0079] (1) The raw gas (CO2 content is 12.56v%, other components include water vapor 7.85v%, nitrogen 73.9v%, oxygen 5.6v%) is flue gas directly emitted from the chimney. After being washed by the water washing tower, it enters the absorption tower 1. In the absorption tower 1, it is contacted with a non-aqueous solution (a mixture of 60wt% N,N-diethylethanolamine, 30wt% triethylenetetramine and 10wt% pentanol). The contact temperature is 45°C, so that the CO2 in the raw gas is transferred into the solution.

[0080] (2) The carbon dioxide absorbent liquid after absorbing CO2 is drawn out from the bottom of the absorption tower and enters the phase separator (temperature 70°C). It then enters the phase separator 3 (70°C) through the steam condensate heat exchanger 2. The solution stays in the phase separator for 10 minutes. The rich liquid of the absorbent liquid obtained by phase separation enters the lean-rich liquid heat exchanger 4 (temperature 95°C) and then enters the regeneration tower 8 (temperature 115°C) and reboiler 9 (temperature 115°C, 0.4MPa 130°C steam a provides the heat source). Through the action of gas stripping and heating, the CO2 in the rich liquid is regenerated.

[0081] (3) The regenerated gas is cooled to 40°C by circulating water and the liquid is separated to obtain high-concentration CO2 gas, which is then sent to the compression section.

[0082] (4) The water and solvent obtained from the regenerator separator are returned to the bottom of the regeneration tower 8. The regenerated lean liquid first recovers heat through the lean-rich liquid heat exchanger 4, mixes with the lean liquid obtained after phase separation, and then cools down through the lean liquid cooler (installed on the pipeline from the lean-rich liquid heat exchanger 4 to the absorption tower 1) before being returned to the absorption tower 1 for recycling.

[0083] The regeneration methods, whether steam condensate heat exchangers are used, the number of distributors, and the proportions Y and Z for each embodiment and comparative example are shown in Table 1.

[0084] Table 1

[0085]

[0086]

[0087] As can be seen from the results in Table 1, the embodiments using the technical solution of the present invention have significantly better effects compared with the comparative examples, such as not needing to use a regeneration tower and reboiler to regenerate the carbon dioxide absorbent, lower regeneration energy consumption, and higher regeneration efficiency.

[0088] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for regenerating carbon dioxide absorbent, characterized in that, The method includes: regenerating carbon dioxide absorbent in a regeneration unit, returning a portion of the regenerated gas obtained after regeneration to the regeneration unit, and purifying the remaining portion; Wherein, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of regenerated gas is 20-90 wt%, and the content of the remaining portion of regenerated gas is 10-80 wt%.

2. The method according to claim 1, wherein, The absorbent is selected from non-aqueous absorbents, preferably from solutions formed by organic amines and organic solvents; Preferably, the organic amine is selected from at least one of organic primary amines, organic secondary amines, and organic tertiary amines, and more preferably from at least one of monoethanolamine, diethanolamine, diethylene glycolamine, 1-dimethylamino-2-propanol, n-propanolamine, dimethylethanol, dihydroxyethylethylenediamine, piperazine, N,N-diethylethanolamine, and triethylenetetramine. Preferably, the organic solvent is selected from at least one of 1,4-dioxane, butanol, 1-propanol, pentanol, ethanol, and sulfolane, and more preferably from at least one of 1,4-dioxane, ethanol, and sulfolane. Preferably, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of the regenerated gas is 70-85 wt%, and the content of the remaining portion of the regenerated gas is 15-30 wt%.

3. The method according to claim 1 or 2, wherein, The viscosity of the absorbent at 40°C is 10-7000 mPa·s, preferably 10-3600 mPa·s; Preferably, the organic amine content is 50-95 wt%, more preferably 60-80 wt%, based on the total weight of the solution.

4. The method according to any one of claims 1-3, wherein, The regeneration method includes regenerating the carbon dioxide absorbent by exchanging heat with steam only through a heat exchanger, without passing through a regeneration tower and a reboiler, and obtaining carbon dioxide and regenerated carbon dioxide absorbent after regeneration.

5. The method according to claim 1 or 4, wherein, The regeneration temperature is 95-115℃, preferably 100-105℃; And / or, the purification process is carried out by condensing the remaining portion to 30-50°C.

6. A method for carbon capture, characterized in that, The method includes: (1) A gas containing carbon dioxide is sent into an absorption device containing a carbon dioxide absorbent liquid and brought into contact with the absorbent liquid to obtain a carbon dioxide absorbent liquid. (2) Regenerate the carbon dioxide absorbent in step (1) in the regeneration device, return a portion of the regenerated gas obtained after regeneration to the regeneration device, and purify the remaining portion. Wherein, based on the total weight of the regenerated gas obtained after regeneration, the content of the portion of the regenerated gas is 20-90 wt%, and the content of the remaining portion of the regenerated gas is 10-80 wt%. The absorbent, the regeneration method, and the regeneration conditions are the same as those in the method described in any one of claims 1-5.

7. The method according to claim 6, wherein, The method further includes at least one of the following steps: a. Separate the material after it comes into contact with the absorbent to separate the carbon dioxide absorbent to be regenerated; b. Heat exchange is performed between the separated carbon dioxide absorbent to be regenerated and the regenerated carbon dioxide absorbent. c. Return the regenerated carbon dioxide absorbent to step (1) as the absorbent.

8. A carbon capture system, characterized in that, The system includes an absorption unit, a phase separator, a regeneration unit, and a gas-liquid separator. The absorption device is used to send the gas containing carbon dioxide into the absorption device containing carbon dioxide absorption liquid, and contact the gas with the absorption liquid to obtain carbon dioxide absorption liquid. The phase separator is connected to the outlet of the absorption device and is used to separate the carbon dioxide absorption liquid to be regenerated. The regeneration device is connected to the outlet of the phase separator and is used to regenerate the carbon dioxide absorbent. The regeneration device is equipped with a return pipe so that a portion of the regenerated gas obtained after regeneration is returned to the regeneration device. The gas-liquid separator is used to purify the remaining portion of the regenerated gas obtained from the regeneration device.

9. The system according to claim 8, wherein, The system does not include a regeneration tower and a reboiler; Preferably, the regeneration device is a regeneration gas heat exchanger, and the cooling medium is steam; Preferably, the absorption device is an absorption tower; Preferably, a steam-condensate heat exchanger is installed on the pipe connecting the phase separator and the absorption device to cool the carbon dioxide absorption liquid discharged from the absorption device through condensate. Preferably, a lean-rich liquid heat exchanger is provided on the pipeline connecting the regeneration device and the phase separator to exchange heat between the carbon dioxide absorbent to be regenerated separated by the phase separator and the regenerated carbon dioxide absorbent. Preferably, a heat pump is installed in the return pipe.

10. The system according to claim 9, wherein the regenerated gas heat exchanger is selected from a shell-and-tube heat exchanger, preferably a segmented shell-and-tube heat exchanger; Preferably, the segmented tube heat exchanger is divided into 1-6 segments, more preferably 2-4 segments.

11. The system according to claim 9 or 10, wherein, The absorption tower, steam-condensate heat exchanger, phase separator, lean-rich liquid heat exchanger, shell-and-tube heat exchanger, and gas-liquid separator are connected in sequence. Preferably, the regeneration device is connected to the absorption device, so that the regenerated carbon dioxide absorbent is returned to the absorption device as an absorbent.

12. The application of the method according to any one of claims 1-7 and / or the system according to any one of claims 8-11 in reducing the regeneration energy consumption of lean regenerated carbon dioxide absorbent.

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