Method and system for reducing degradation loss of flue gas carbon capture absorption solvent

Abstract

The invention relates to the field of carbon dioxide capture, and discloses a method and system for reducing degradation loss of a flue gas carbon capture absorption solvent, and the method comprises the following steps: carrying out gas stripping deoxygenization on an absorption solvent rich solution to obtain oxygen-containing stripped gas and a spent absorption solution; the method comprises the following steps: carrying out gas stripping and deoxygenization on a CO2-rich absorption solvent rich solution after absorption, regenerating a to-be-regenerated absorption solution to obtain regenerated gas and an absorption solvent barren solution, and extracting the regenerated gas by using oxygen-containing stripping gas at the same time. The oxygen physically dissolved in the rich solution of the absorption solvent is regenerated, the oxygen concentration in the absorption solvent is reduced, the possible degradation reaction is further reduced, the regenerated gas during regeneration is extracted by using the obtained oxygen-containing stripping gas, the regeneration operation temperature is reduced by reducing the operation pressure during regeneration, and the regeneration efficiency is improved. The degradation reaction rate is reduced, so that the purpose of reducing the degradation loss of the flue gas carbon capture absorption solvent is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon dioxide capture, and in particular to a method and system for reducing degradation loss of flue gas carbon capture absorption solvent. Background Art

[0002] The combustion of fossil resources is currently the main way for humans to obtain energy. The flue gas produced by the combustion of fossil resources is currently the main source of CO2 emissions, accounting for more than 70% of the total CO2 emissions. Therefore, the use of carbon dioxide capture, utilization and storage (CCUS) technology to treat flue gas has become the focus of attention of various industries.

[0003] According to the different CO2 separation principles, CO2 capture technology can be divided into four types: absorption, adsorption, membrane separation and cryogenic distillation. At present, the absorption method represented by organic amines is the most widely used technology in the field of flue gas carbon capture. During the use of organic amines, degradation reactions will occur, causing them to be continuously consumed, resulting in high capture costs. Therefore, reducing the degradation loss of flue gas carbon capture absorption solvents has become an urgent problem to be solved in this field.

[0004] CN01138009.8 discloses an antioxidant for inhibiting the oxidative degradation of low partial pressure CO2 recovery solvent, wherein the antioxidant is a metal oxide and its salts.

[0005] CN202010898314.3 discloses a class of α-amino acid salt absorbents for capturing carbon dioxide, including α-amino acid salts, a dissolution-promoting solvent, an absorbent and water. The volume ratio of the α-amino acid salt is 15%-40%, the volume ratio of the dissolution-promoting solvent is 5%-15%, and the volume ratio of the absorbent is 2%-8%.

[0006] CN201710219069.7 discloses a new method for inhibiting solution degradation and high viscosity of the carrier phase during the process of removing acidic gases by a phase-change absorbent. The antioxidant and degradation effects are achieved by adding a certain proportion of alcohol or water to the main absorbent (organic amine and polyether). When the phase-change absorbent is homogeneous, the additive can be well dissolved therein and play a protective role. After the phase-change absorbent removes acidic gases, the solution forms a carrier phase and an organic phase. The additive can still be dissolved in the two-phase solution in a phase equilibrium manner, respectively, and plays a good protective role for both the organic phase and the carrier phase.

[0007] As can be seen from the above, the existing technologies mainly focus on how to reduce the oxidative degradation of solvents. There are two specific paths: one is to add antioxidants, and the other is to develop solvents with better antioxidant properties. There is very little research on reducing the degradation of carbon capture solvents from a process perspective. Summary of the invention

[0008] The purpose of the present invention is to overcome the problem of the prior art that the flue gas carbon capture absorption solvent is easily degraded and causes solvent loss, and to provide a method and system for reducing the degradation loss of the flue gas carbon capture absorption solvent. The method deoxidizes and regenerates the absorption solvent rich liquid by gas stripping, and extracts during regeneration, thereby reducing the oxygen concentration in the absorption solvent and reducing the operating temperature of the regeneration reaction, thereby significantly reducing the degradation loss of the flue gas carbon capture absorption solvent, and has broad application prospects.

[0009] In order to achieve the above object, the first aspect of the present invention provides a method for reducing the degradation loss of flue gas carbon capture absorption solvent, which comprises the following steps:

[0010] (1) stripping and deoxygenating the absorption solvent-rich liquid to obtain oxygen-containing stripping gas and an absorption solution to be produced;

[0011] (2) regenerating the absorption solution to be regenerated to obtain a regenerated gas and an absorption solvent-lean solution, wherein the regenerated gas is simultaneously stripped using the oxygen-containing stripping gas.

[0012] A second aspect of the present invention provides a system for reducing degradation loss of flue gas carbon capture absorption solvent, wherein the system includes a gas lift deoxygenation tower, a regeneration tower, and a venturi injector, wherein the gas lift deoxygenation tower has a liquid inlet at the top, an air inlet at the bottom, and an absorption solvent rich liquid outlet at the bottom, wherein the absorption solvent rich liquid outlet is connected to the regeneration tower, the air outlet at the top of the regeneration tower is connected to the feed port of the venturi injector, and the air flow inlet of the venturi injector is connected to the gas lift gas outlet at the top of the gas lift deoxygenation tower.

[0013] The above technical scheme adds a gas stripping and deoxygenation step, firstly, the CO2-rich absorption solvent rich liquid after absorption is subjected to gas stripping and deoxygenation, so that the oxygen physically dissolved in the absorption solvent rich liquid is regenerated, thereby reducing the oxygen concentration in the absorption solvent and further reducing the possible degradation reaction, and then the obtained oxygen-containing stripping gas is used to extract the regeneration gas during regeneration, and the regeneration operating temperature is reduced by reducing the operating pressure during regeneration to reduce the degradation reaction rate, thereby achieving the purpose of reducing the degradation loss of the flue gas carbon capture absorption solvent. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of the process of Example 1;

[0015] Figure 2 This is a schematic diagram of the process of Comparative Example 1.

[0016] Description of Reference Numerals

[0017] 1-pretreatment tower; 2-absorption tower; 3-regeneration tower; 4-gas stripping and deoxygenation tower; 5-CO2 compressor; 6-CO2 gas ejector; 7-demister; 8-heat exchanger; 9-lean liquid pump; 10-lean liquid cooler; 11-regeneration gas condensation separator; 12-rich liquid pump; 13-water washing pump; 14-water washing water cooler; 15-fan; 16-reboiler; 17-pretreatment pump; 18-pretreatment cooler; 19-Venturi ejector; 101-raw flue gas; 102-purified gas; 103-product gas; 104-CO2 reflux pipe. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] In the present invention, the "absorption solution to be produced" refers to the absorption solvent-rich solution after O2 is stripped.

[0020] A first aspect of the present invention provides a method for reducing the degradation loss of flue gas carbon capture absorption solvent, comprising the following steps:

[0021] (1) stripping and deoxygenating the absorption solvent-rich liquid to obtain oxygen-containing stripping gas and an absorption solution to be produced;

[0022] (2) regenerating the absorption solution to be regenerated to obtain a regenerated gas and an absorption solvent-lean solution, wherein the regenerated gas is simultaneously stripped using the oxygen-containing stripping gas.

[0023] In some embodiments of the present invention, preferably, external CO2 is used as the stripping gas during the stripping deoxygenation process; wherein the pressure of the stripping deoxygenation is 0.6-2.5 MPaA, preferably 0.8-1.5 MPaA. The CO2 pressure during stripping deoxygenation affects the size of bubbles formed by jet regeneration, thereby affecting the gas-liquid contact area, and further affecting the separation effect. The CO2 pressure can be any value within the numerical range of any two of 0.6 MPaA, 1.0 MPaA, 1.5 MPaA, 2.0 MPaA, and 2.5 MPaA, and can also be any value within the numerical range of any two of 0.8 MPaA, 1.0 MPaA, 1.2 MPaA, and 1.5 MPaA.

[0024] In some embodiments of the present invention, preferably, the pressure during regeneration is 10-50 kPaA, preferably 20-40 kPaA. The pressure during regeneration affects the regeneration operating temperature, and further affects the degradation rate of the absorption solvent. The pressure during regeneration can be any value within the numerical range of any two of 10 kPaA, 20 kPaA, 30 kPaA, 40 kPaA, and 50 kPaA, and can also be any value within the numerical range of any two of 20 kPaA, 25 kPaA, 30 kPaA, 35 kPaA, and 40 kPaA.

[0025] In some embodiments of the present invention, preferably, after the extraction, the gas obtained is a carbon capture product.

[0026] In some embodiments of the present invention, preferably, the carbon capture product is used for the gas stripping and deoxygenation.

[0027] In some embodiments of the present invention, preferably, in the process of gas stripping deoxygenation, the amount of added CO2 used is 1-20wt% of the carbon capture product. In the process of gas stripping deoxygenation, CO2 is used as gas stripping gas, and part of the carbon capture product can also be recycled as gas stripping gas. At this time, the amount of added gas CO2 is 1-20wt% of the total amount of the carbon capture product. The greater the reflux amount of carbon dioxide of the carbon capture product, the better the effect of gas stripping deoxygenation, but it will cause the loss of product gas pressure, the compression work will increase, and the amount of refluxed CO2 is too large, and the effect of increasing the gas stripping effect is not obvious. Therefore, within the above range, the amount of CO2 used in gas stripping deoxygenation can account for any value within the numerical range of any two of 1wt%, 5wt%, 10wt%, 15wt%, and 20wt% of the total amount of the carbon capture product, and the product pressure loss can be relatively small under the premise of ensuring the effect of gas deoxygenation.

[0028] A second aspect of the present invention provides a system for reducing the degradation loss of flue gas carbon capture absorption solvent, such as Figure 1 As shown, the system includes a gas stripping deoxygenation tower 4, a regeneration tower 3, and a venturi ejector 19, wherein the gas stripping deoxygenation tower 4 has a liquid inlet at the top, an air inlet at the bottom, and an absorption solvent rich liquid outlet at the bottom, wherein the absorption solvent rich liquid outlet is connected to the regeneration tower 3, the air outlet at the top of the regeneration tower 3 is connected to the feed port of the venturi ejector 19, and the air flow inlet of the venturi ejector 19 is connected to the gas stripping gas outlet at the top of the gas stripping deoxygenation tower 4.

[0029] In some embodiments of the present invention, preferably, the discharge port of the venturi ejector is connected to a CO2 reflux pipe, and the other end of the CO2 reflux pipe is connected to the gas inlet at the lower part of the gas stripping deoxygenation tower. The gas coming out of the venturi ejector is the carbon capture product, and the obtained carbon capture product is used as the gas for gas stripping deoxygenation without the need for additional gas supply.

[0030] In some embodiments of the present invention, preferably, the CO2 refluxed to the gas stripping deoxygenation tower through the CO2 reflux pipe is used for gas stripping deoxygenation, and the amount of added CO2 used in the gas stripping deoxygenation process is 1-20wt% of the amount of carbon capture product discharged from the venturi ejector.

[0031] In some embodiments of the present invention, preferably, the pressure at the top of the regeneration tower 3 is set to 10-50 kPaA, preferably 20-40 kPaA.

[0032] In some embodiments of the present invention, preferably, the air inlet at the lower part of the gas stripping deoxygenation tower is used to supply CO2, and the pressure of the incoming CO2 is set to 0.6-2.5 MPaA, preferably 0.8-1.5 MPaA.

[0033] In some embodiments of the present invention, preferably, an absorption tower is further included, and the liquid outlet of the absorption tower is connected to the liquid inlet of the gas stripping deoxygenation tower.

[0034] Preferably, the diameter of the gas stripping deoxygenation tower is 1 / 10-4 / 5 of the diameter of the absorption tower, preferably 3 / 10-3 / 5. The selection of the tower diameter affects the gas-liquid distribution and thus affects the separation effect. The diameter of the gas stripping deoxygenation tower can be any value within the numerical range of any two of 1 / 10, 1 / 5, 3 / 10, 2 / 5, 5 / 10, 3 / 5, 7 / 10, and 4 / 5 of the diameter of the absorption tower.

[0035] Preferably, the height of the gas stripping deoxygenation tower is 1 / 6-2 / 3 of the height of the absorption tower, preferably 1 / 3-1 / 2. The selection of the tower height affects the mass transfer area, and thus affects the separation effect. The height of the gas stripping deoxygenation tower can be any value within the numerical range of any two of 1 / 6, 1 / 5, 1 / 4, 1 / 3, and 2 / 3 of the height of the absorption tower, and can also be any value within the numerical range of any two of 1 / 3, 2 / 5, and 1 / 2.

[0036] Combination Figure 1 , the system working process of the present invention is described as follows:

[0037] The raw flue gas 101 enters the absorption tower 2 after being impurity-removed and cooled in the pretreatment tower 1, and contacts with the lean absorption solvent in the absorption zone of the absorption tower 2, so that the CO2 in the raw flue gas is transferred to the absorption solvent, and a rich absorption solvent liquid enriched with CO2 is obtained; the rich absorption solvent liquid is drawn out from the bottom of the absorption tower 2, and enters the gas stripping deoxygenation tower 4 through the rich liquid pump 12, and the CO2 gas injector 6 in the gas stripping deoxygenation tower 4 sprays high-concentration CO2, and the high-concentration CO2 contacts with the rich absorption solvent liquid in reverse, and the high-concentration CO2 gas is used to strip the O2 in the rich absorption solvent liquid, and oxygen-containing stripping gas and absorption solution to be generated are obtained;

[0038] The absorption solution to be regenerated after stripping of O2 is sent to the regeneration tower 3 after heat exchange in the heat exchanger 8. The regeneration tower 3 is heated by the reboiler 16. The CO2 in the absorption solution to be regenerated is regenerated by stripping and heating to obtain regenerated gas and absorption solvent lean liquid. During the regeneration, the oxygen-containing stripping gas is defogged by the demister 7 and sent to the venturi ejector 19 at the top of the regeneration tower 3 to extract the regenerated gas in the regeneration tower 3 to obtain a carbon capture product. A part of the carbon capture product is compressed and pressurized (CO2 compressor 5) and sent to the gas stripping deoxygenation tower 4 for gas stripping and deoxygenation, and most of it is sent to the subsequent liquefaction unit as product gas 103;

[0039] After the absorption solvent lean liquid is drawn out from the bottom of the regeneration tower 3, it is sent to the lean liquid pump 9 after heat exchange in the heat exchanger 8, cooled in the lean liquid cooler 10, and then enters the absorption tower 2 for recycling. The liquid in the bottom of the pretreatment tower 1 is drawn out by the pretreatment pump 17, cooled by the pretreatment cooler 18, and then re-enters the pretreatment tower 1 for recycling.

[0040] The flue gas that has come into contact with the lean absorption solvent in the absorption zone of the absorption tower 2 further ascends through the gas lift cap and enters the lower part of the washing zone of the absorption tower 2, and after coming into contact with the washing liquid, the purified gas 102 is obtained and discharged from the top of the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the washing zone for circulation.

[0041] The method and system provided by the present invention have the following advantages:

[0042] (1) No need to change the solvent formula or consume antioxidants, the degradation loss of flue gas carbon capture solvent can be significantly reduced by simply optimizing the process flow;

[0043] (2) By bringing the pressurized high-concentration CO2 gas into contact with the absorbent solvent rich liquid, the acid gas load in the absorbent solvent rich liquid entering the regeneration tower can be increased, thereby increasing the driving force of the regeneration reaction and reducing the difficulty of the regeneration reaction;

[0044] (3) By extracting the regenerated gas, the operating temperature of the regeneration tower can be reduced, and waste hot water can be used for heating during regeneration, thereby reducing the regeneration energy consumption cost.

[0045] Example 1

[0046] Taking the composite amine solvent as the absorption solvent as an example, the absorption solvent comes from MA-2 of Sinopec Nanjing Chemical Research Institute Co., Ltd. Figure 1 The process flow shown, the method of capturing flue gas carbon and degrading the universal absorption solvent is as follows:

[0047] (1) After the raw flue gas 101 is treated by the pretreatment tower 1, the flue gas is sent from the top of the pretreatment tower 1 to the bottom of the absorption tower 2 through the fan 15. The liquid at the bottom of the pretreatment tower 1 is pumped out by the pretreatment pump 17 and cooled by the pretreatment cooler 18 before re-entering the pretreatment tower 1 to contact with the newly entered raw flue gas 101 to remove impurities and cool the raw flue gas 101;

[0048] (2) The pretreated flue gas contacts the lean absorption solvent in the absorption zone of the absorption tower 2, so that the CO2 in the flue gas is transferred to the absorption solvent to obtain a rich absorption solvent solution rich in CO2. The flue gas further ascends in the absorption tower 2 and enters the lower part of the washing zone of the absorption tower 2 through the gas lift cap. After contacting with the washing liquid, the purified gas 102 is obtained and discharged from the top of the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the washing zone for recycling;

[0049] (3) The CO2-rich absorption solvent rich liquid is drawn out from the bottom of the absorption tower 2 and sent to the liquid inlet of the gas stripping deoxygenation tower 4 by the rich liquid pump 12. The gas inlet at the lower part of the gas stripping deoxygenation tower 4 is connected to the CO2 reflux pipe 104. The refluxed CO2 is ejected through the gas ejector 6. The refluxed CO2 contacts the absorption solvent rich liquid, so that the oxygen therein is transferred to the CO2 to obtain oxygen-containing stripping gas and absorption solution to be generated;

[0050] The diameter of the gas stripping deoxygenation tower 4 is 1 / 5 of the diameter of the absorption tower 2, and the tower height is 1 / 6 of the height of the absorption tower 2. The amount of CO2 entering the gas stripping deoxygenation tower 4 is 2% of the amount of carbon capture products, and the pressure is 0.6MPaA.

[0051] (4) The regenerated absorption solution flows out from the absorption solvent rich liquid outlet at the bottom of the gas stripping deoxygenation tower 4, is heated by the heat exchanger 8 and then sent to the regeneration tower 3. The regeneration tower 3 is heated by the reboiler 16 to regenerate the CO2 in the regenerated absorption solution to obtain regenerated gas and absorption solvent lean liquid;

[0052] The oxygen-containing stripping gas obtained at the top of the gas stripping deoxygenation tower 4 is sent to the gas flow inlet of the venturi ejector 19 after the entrained droplets are removed by the demister 7. The regeneration gas in the regeneration tower 3 enters the feed port of the venturi ejector. The regeneration gas in the regeneration tower 3 is extracted by the oxygen-containing stripping gas, so that the pressure of the regeneration tower top 3 is maintained at 45kPaA. The combined gas of the regeneration gas and the oxygen-containing stripping gas, i.e., the carbon capture product, is obtained from the discharge port of the venturi ejector 19. The obtained carbon capture product is condensed and separated from the liquid by the regeneration gas condensation separator 11 to obtain a high-concentration CO2 gas. After being pressurized by the compressor 5, 98wt% is used as the product gas 103 to go to the subsequent liquefaction unit, and 2wt% is sent to the gas stripping deoxygenation tower 4 through the CO2 reflux pipe 104;

[0053] (5) The regenerated absorption solvent lean liquid is drawn out from the bottom of the absorption tower 3, firstly recovers heat through the heat exchanger 8, then is cooled through the lean liquid cooler 10, and then is returned to the absorption zone of the absorption tower 2 for recycling.

[0054] It is calculated that using the method of this embodiment, the degradation loss of the absorption solvent is about 44% of that of Comparative Example 1.

[0055] Example 2

[0056] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0057] Example 3

[0058] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0059] Example 4

[0060] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0061] Example 5

[0062] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0063] Example 6

[0064] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0065] Example 7

[0066] The method of Example 1 is used, except that the CO2 reflux amount, reflux pressure, the diameter and height of the gas stripping deoxygenation tower 4, and the regeneration pressure of the regeneration tower 3 are different, as shown in Table 1.

[0067] Table 1 Parameters of each embodiment

[0068]

[0069]

[0070] Comparative Example 1

[0071] like Figure 2 As shown, the absorption solvent is the same as in Example 1, and the specific process is as follows:

[0072] (1) The raw flue gas 101 treated by the pretreatment tower 1 is sent from the top of the pretreatment tower 1 to the bottom of the absorption tower 2 through the fan 15. The liquid at the bottom of the pretreatment tower 1 is pumped out by the pretreatment pump 17 and cooled by the pretreatment cooler 18 before re-entering the pretreatment tower 1 to contact with the newly entered raw flue gas 101 to remove impurities and cool the raw flue gas 101.

[0073] (2) The pretreated flue gas contacts the lean absorption solvent in the absorption zone of the absorption tower 2, so that the CO2 in the flue gas is transferred to the absorption solvent to obtain a rich absorption solvent solution rich in CO2. The flue gas further ascends in the absorption tower 2 and enters the lower part of the washing zone of the absorption tower 2 through the gas lift cap. After contacting with the washing liquid, the purified gas 102 is obtained and discharged from the absorption tower 2. The washing liquid is pumped out of the washing zone by the water washing pump 13, cooled by the water washing water cooler 14, and then enters the upper part of the absorption zone for recycling;

[0074] (3) The absorption solvent-rich liquid enriched with CO2 is drawn out from the bottom of the absorption tower 2, heated by the heat exchanger 8, and sent to the regeneration tower 3. The CO2 in the rich liquid is regenerated by gas stripping and heating at normal pressure;

[0075] (4) The regenerated CO2 gas is condensed and the liquid is separated by the regeneration gas condensation separator 11 to obtain a high-concentration CO2 gas. After being pressurized by the compressor 5, all of it is sent to the subsequent liquefaction unit as the product gas 103. The regenerated absorbent lean liquid is drawn out from the kettle of the regeneration tower 3, firstly recovered the heat by the heat exchanger 8, then cooled by the lean liquid cooler 10, and returned to the absorption area of ​​the absorption tower 2 for recycling.

[0076] Comparative Example 2

[0077] The process is carried out in the same manner as in Example 1, except that the diameter and height of the gas stripping deoxygenation tower are different.

[0078] Comparative Example 3

[0079] The process is carried out in the same manner as in Example 1, except that the diameter and height of the gas stripping deoxygenation tower are different.

[0080] The absorption solvent loss results of Examples 1-7 and Comparative Examples 1-3 are shown in Table 2.

[0081] Table 2 Absorption solvent loss

[0082] serial number <![CDATA[Degradation loss (kg / t CO2)]]> Degradation loss (% of the loss in comparative example 1) Comparative Example 1 0.6 / Comparative Example 2 0.402 67 Comparative Example 3 0.373 62 Example 1 0.264 44 Example 2 0.156 26 Example 3 0.066 11 Example 4 0.114 19 Example 5 0.084 14 Example 6 0.316 53 Example 7 0.088 15

[0083] It can be seen that by adopting the method provided by the present invention, the degradation loss of the absorption solvent is much lower than the degradation loss in Comparative Example 1 which does not adopt the method provided by the present invention, especially in Examples 3, 5 and 7, the degradation loss of the absorption solvent is only 0.066-0.114 kg / t CO2, which is only 11-15% of that in Comparative Example 1. This is because the reflux CO2 pressure, the tower diameter and tower height of the gas stripping deoxygenation tower, and the pressure settings of the regeneration tower are more reasonable, and their synergistic effect promotes the regeneration of the regenerated solvent and reduces the degradation loss of the absorption solvent.

[0084] In contrast, compared with Example 1, the tower diameters and tower heights of Comparative Examples 2 and 3 are either too large or insufficient, which affects the separation effect, and the degradation loss rates are even lower than those of Example 1 of the present invention.

[0085] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for reducing the degradation loss of flue gas carbon capture absorption solvent, characterized in that: The following steps are involved: (1) stripping and deoxygenating the absorption solvent-rich liquid to obtain oxygen-containing stripping gas and an absorption solution to be produced; (2) regenerating the absorption solution to be regenerated to obtain a regenerated gas and an absorption solvent-lean solution, wherein the regenerated gas is simultaneously stripped using the oxygen-containing stripping gas.

2. The method according to claim 1, characterized in that In the process of gas stripping and deoxygenation, external CO2 is used as the gas stripping gas; wherein the pressure of the gas stripping and deoxygenation is 0.6-2.5MPaA, preferably 0.8-1.5MPaA.

3. The method according to claim 1 or 2, characterized in that: The regeneration pressure is 10-50 kPaA, preferably 20-40 kPaA.

4. The method according to claim 2 or 3, characterized in that: After the extraction, the obtained gas is a carbon capture product; Preferably, the carbon capture product is used for the gas stripping and deoxygenation; Preferably, during the gas stripping and deoxygenation process, the amount of added CO2 used is 1-20 wt% of the carbon capture product.

5. A system for reducing degradation loss of flue gas carbon capture absorption solvent, characterized in that: The system includes a gas stripping deoxygenation tower, a regeneration tower, and a venturi ejector. The gas stripping deoxygenation tower has a liquid inlet at the top, an air inlet at the bottom, and an absorption solvent rich liquid outlet at the bottom, wherein the absorption solvent rich liquid outlet is connected to the regeneration tower; the air outlet at the top of the regeneration tower is connected to the feed port of the venturi ejector, and the air flow inlet of the venturi ejector is connected to the gas stripping gas outlet at the top of the gas stripping deoxygenation tower.

6. The system according to claim 5, characterized in that The discharge port of the venturi ejector is connected with a CO2 reflux pipe, and the other end of the CO2 reflux pipe is connected with the air inlet at the lower part of the gas stripping deoxygenation tower.

7. The system according to claim 6, characterized in that The CO2 refluxed to the gas stripping deoxygenation tower through the CO2 reflux pipe is used for gas stripping deoxygenation, and the amount of the added CO2 used in the gas stripping deoxygenation process is 1-20wt% of the amount of the carbon capture product discharged from the venturi ejector.

8. The system according to any one of claims 5 to 7, characterized in that: The pressure at the top of the regeneration tower is set to 10-50 kPaA, preferably 20-40 kPaA.

9. The system according to any one of claims 5 to 8, characterized in that: The air inlet at the lower part of the gas stripping deoxygenation tower is used for CO2 to enter, and the pressure of the entering CO2 is set to 0.6-2.5MPaA, preferably 0.8-1.5MPaA.

10. The system according to any one of claims 5 to 9, characterized in that: The system further comprises an absorption tower, the liquid outlet of the absorption tower being connected to the liquid inlet of the gas stripping deoxygenation tower; Preferably, the diameter of the gas stripping deoxygenation tower is 1 / 10-4 / 5 of the diameter of the absorption tower, preferably 3 / 10-3 / 5; Preferably, the height of the gas stripping deoxygenation tower is 1 / 6-2 / 3 of the height of the absorption tower, preferably 1 / 3-1 / 2.

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