A method for low-temperature regeneration of carbon dioxide absorption rich liquid

Abstract

The present invention belongs to the field of carbon dioxide capture and regeneration technology, and provides a method for low-temperature regeneration of a carbon dioxide absorption rich liquid. The method comprises the following steps: a pretreatment stage: filtering the rich liquid through a ceramic membrane with a pore size of 0.5-2 μm to remove suspended particles; a modification treatment stage: adding a composite modifier to the pretreated rich liquid and subjecting it to mechanical oscillation; a regeneration treatment stage: introducing nitrogen to implement gas stripping regeneration; a separation stage: using a multi-stage condensation system to capture the released carbon dioxide gas, and returning the regenerated lean liquid to be absorbed after pH adjustment; and a composite modifier in the modification treatment stage: a silane coupling agent and a surfactant are compounded in a mass ratio of 3-5:1. This application provides a feasible path for industrial-grade low-temperature regeneration by constructing a multi-dimensional collaborative solution, developing a new composite modifier to enhance the low-temperature activity of the absorbent, optimizing the pressure difference control accuracy of the three-stage gas stripping tower, innovating the condensate phase separation recovery process, and introducing mechanical oscillation and ultrasonic collaborative dispersion technology.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture and regeneration, and in particular relates to a low-temperature regeneration method for carbon dioxide absorption rich liquid. Background Art

[0002] Carbon dioxide capture and regeneration technology is one of the core means to address climate change and has important application value in high-carbon emission industries such as electricity, steel, and chemicals. This technology uses chemical or physical methods to enrich carbon dioxide in industrial waste gas in an absorption liquid to form a rich liquid, and then releases high-purity carbon dioxide through a regeneration process for storage or resource utilization. Traditional regeneration processes rely on high-temperature heating of the rich liquid to achieve carbon dioxide desorption, but this process has inherent defects such as high energy consumption, severe equipment corrosion, and rapid degradation of absorbents. Taking coal-fired power plants as an example, energy consumption in the regeneration link accounts for more than 70% of the overall capture cost, and high-temperature operation causes the annual loss rate of amine absorbents to reach 15%-20%, significantly increasing operating costs.

[0003] Existing technologies for reducing regeneration temperatures primarily focus on three areas: the development of new absorbents, physical field-assisted regeneration, and process parameter optimization. In terms of absorbent modification, mixed amine systems improve desorption efficiency through the compounding of polyamines. For example, a specific ratio of methyldiethanolamine and piperazine can reduce the regeneration temperature to 90-100°C. However, such systems are prone to component segregation during long-term operation, resulting in a regeneration efficiency loss of more than 30%. Another approach is to introduce ionic liquids as additives, but their high viscosity reduces gas-liquid mass transfer efficiency, and the synthesis cost is 3-5 times higher than that of traditional absorbents. While physical activation methods such as ultrasonic-assisted regeneration can reduce heat energy consumption, they increase equipment investment by more than 40%, and high-frequency vibrations accelerate the destruction of the packing layer structure, shortening the equipment's service life.

[0004] In terms of process parameter optimization, graded gas stripping technology achieves temperature gradient control through the connection of multiple towers in series, but existing equipment generally suffers from insufficient precision in regulating the pressure difference between stages. For example, in a three-stage gas stripping tower scheme disclosed in a patent, the operating pressure fluctuation range of the final tower reaches ±0.05MPa, causing the carbon dioxide desorption rate to fluctuate by more than 5 percentage points. In addition, the pH adjustment of the regenerated lean liquid mostly adopts a single acid-base neutralization method, which can easily cause local over-reaction areas, trigger the precipitation of absorbent colloids, and form equipment scaling. Although the existing condensation system can recover some absorbent, the condensate produced in the low-temperature section often carries unreacted amines. The recovery rate of traditional nanofiltration membranes is only 70%-80%, resulting in the loss of effective ingredients.

[0005] The existing technology also has the problem of low energy utilization efficiency. The solar thermal assisted regeneration system attempts to use solar energy to heat molten salt as a heat source, but the molten salt temperature needs to reach above 300°C to meet the regeneration needs. In rainy weather, it needs to switch to steam heating, and the system stability is insufficient. Another type of negative pressure flash evaporation technology uses a single-permeable membrane structure to achieve low-temperature desorption. Although it reduces energy consumption to 50% of the traditional process, the membrane material is easily blocked by solid particles in the rich liquid. After 30 days of continuous operation, the flux drops by 40%, and frequent shutdowns and cleaning are required. Some plans propose the cascade utilization of waste heat, such as using the exhaust heat from the regeneration tower to preheat the rich liquid, but the coking problem of the heat exchanger causes the heat recovery efficiency to decrease by 2%-3% per month.

[0006] Therefore, it is necessary to design a low-temperature regeneration method for carbon dioxide absorption rich liquid. Summary of the Invention

[0007] In order to overcome the defects in the prior art, a method for low-temperature regeneration of carbon dioxide absorption rich liquid is provided.

[0008] In order to achieve the above object, the present invention provides the following technical solutions:

[0009] A method for low-temperature regeneration of a carbon dioxide absorption rich solution, comprising the following steps:

[0010] Pretreatment stage: The rich liquid is filtered through a ceramic membrane with a pore size of 0.5-2 μm to remove suspended particles;

[0011] Modification treatment stage: Add the composite modifier to the pretreated rich liquid and perform mechanical oscillation, with the oscillation frequency controlled at 100-300 rpm;

[0012] Regeneration stage: nitrogen is introduced at 60-75°C and 0.2-0.4 MPa to perform gas stripping regeneration;

[0013] Separation stage: A multi-stage condensation system is used to capture the released carbon dioxide gas, and the regenerated lean liquid is returned to the absorption after pH adjustment;

[0014] The composite modifier in the modification treatment stage is prepared by compounding a silane coupling agent and a surfactant in a mass ratio of 3-5:1.

[0015] The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane;

[0016] The surfactant is prepared by compounding sodium lauryl sulfate and Tween 80 in a mass ratio of 2-4:1.

[0017] The modification treatment stage specifically comprises the following steps: heating the rich solution to 40-50°C, adding the composite modifier dropwise at a rate of 0.5-2 mL / min, and maintaining stirring for 30-60 minutes after the addition is complete at a stirring rate of 200-400 rpm; mechanically oscillating the solution using an eccentric vibration device with an amplitude of 2-5 mm and a vibration time of 20-40 minutes; and simultaneously applying 20-40 kHz ultrasonic waves during the vibration treatment, with a sound intensity controlled at 0.5-1.5 W / cm² and an action time of 5-15 minutes.

[0018] The total addition amount of the composite modifier is 0.5-3% of the mass of the rich liquid.

[0019] The regeneration treatment stage includes three stages of gas stripping towers in series, with the first stage operating at 60-65°C and a pressure of 0.25-0.35 MPa, the second stage at 63-68°C and a pressure of 0.2-0.3 MPa, and the third stage at 68-75°C and a pressure of 0.15-0.25 MPa.

[0020] The nitrogen flow rate of each stage of the stripping tower is 1.2-2 times the volume flow of the rich liquid, and the gas-liquid contact time is controlled at 5-15 minutes.

[0021] The absorbent of the rich liquid includes a main absorbent methyldiethanolamine and an auxiliary absorbent aminoethylpiperazine, and the mass ratio of the main absorbent methyldiethanolamine to the auxiliary absorbent aminoethylpiperazine is 4-6:1.

[0022] The concentration of the main absorbent methyldiethanolamine is 25%-35% (w / w), and the concentration of the auxiliary absorbent aminoethylpiperazine is 5%-10% (w / w).

[0023] The absorbent further contains 0.1%-0.5% (w / w) of a corrosion inhibitor, which is prepared by compounding sodium molybdate and benzotriazole in a mass ratio of 1:2-4.

[0024] The pretreatment stage adopts three-stage series filtration, wherein the first stage is a 50 μm metal filter, the second stage is a 5 μm cellulose filter membrane, and the third stage is a 1 μm ceramic membrane; the operating pressure of the three-stage filtration is 0.1-0.3 MPa.

[0025] In the separation stage, the multi-stage condensation system includes three stages of gradient cooling: the first stage is cooled to 10-15°C, the second stage is 5-8°C, and the third stage is -5-0°C. Each stage is equipped with a gas-liquid separation device.

[0026] The pH value of the regenerated lean solution is adjusted by a step-by-step addition method: first, 0.1 mol / L sulfuric acid is added to adjust the pH value to 9-10, and then 0.05 mol / L sodium hydroxide is added to fine-tune the pH value to 10.5-11.2.

[0027] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0028] 1. This application builds a multi-dimensional collaborative solution, developing a novel composite modifier to enhance the absorbent's low-temperature activity, optimizing the pressure differential control accuracy of the three-stage stripping tower, innovating a condensate phase recovery process, and introducing a synergistic dispersion technique combining mechanical oscillation and ultrasound. These improvements maintain a regeneration temperature below 80°C, stabilize the desorption efficiency at over 95%, control the modifier dosage to under 5%, and extend the system's continuous operation cycle to over 120 days, providing a viable path for industrial-grade low-temperature regeneration.

[0029] 2. The synergistic effect of gradient filtration and surface modification significantly improves solution cleanliness. The metal filter initially intercepts large impurities, the cellulose membrane adsorbs colloidal substances, and the nanoscale pore structure of the ceramic membrane, combined with the hydrophilic surface treatment, effectively intercepts micron-sized suspended solids. The three-stage filtration design with decreasing pore size creates a step-by-step purification mechanism. This structure prevents clogging of the membrane assembly while maintaining a stable operating pressure. Compared to single filtration methods, the solution transmittance is significantly improved, creating a more optimal fluid environment for subsequent regeneration processes.

[0030] 3. The molecular synergistic effect of the composite modifier enhances desorption kinetics. The active groups of the silane coupling agent form directional bonds with the amine absorbent, reducing intermolecular forces within the solution. The hydrophobic segments of the surfactant form an orderly arrangement at the gas-liquid interface. Combined with the eddy currents generated by mechanical oscillation and ultrasonic cavitation, this promotes the formation of a stable microbubble structure in the solution. This modification significantly reduces the energy barrier for carbon dioxide molecules to desorb from the absorbent, enabling efficient desorption at relatively low temperatures, eliminating the traditional process's reliance on high-temperature heat sources.

[0031] 4. The temperature and pressure gradient design of the multi-stage gas stripping tower optimizes the desorption thermodynamic equilibrium. The higher pressure in the initial stage promotes the conversion of chemically bound CO2 to a physically dissolved state. Gradual pressure reduction in the middle stage creates the driving force for desorption. In the final stage, carrier gas displacement enables deep desorption. The temperature control strategy, combined with the characteristics of the phase transition critical point, utilizes differences in molecular thermal motion to enhance desorption selectivity while preventing thermal decomposition of the absorbent. The dynamic displacement of the nitrogen carrier gas disrupts the equilibrium at the gas-liquid interface, creating a continuous driving force for desorption. The overall process significantly reduces heat energy consumption compared to conventional steam heating methods.

[0032] 5. The combined application of step-by-step condensation and intelligent acid adjustment processes effectively reduces component loss. The gradient cooling system achieves selective condensation of gaseous components through step-by-step phase change, and the introduction of antifreeze in the final low-temperature section prevents the crystallization of amines. The gas-liquid separation device captures mist droplets and, in conjunction with a step-by-step acid-base adjustment strategy, first neutralizes excess alkaline components with a weak acid, then adjusts the pH to the optimal absorption value with a trace amount of alkaline solution. This two-way adjustment mechanism avoids the localized supersaturation caused by traditional single acid addition, improves the stability of the solution's ion balance, and significantly improves the recovery rate of the absorbent's active ingredients compared to conventional processes.

[0033] 6. The synergistic construction of the corrosion inhibition system and energy circulation network extends the service life of the equipment. The combination of molybdate and organic corrosion inhibitors forms a dense passivation layer on the metal surface, suppressing corrosion reactions through the dual mechanisms of selective adsorption and electrochemical protection. The waste heat recovery module re-introduces the low-temperature heat from the condensation process into the system to maintain the solution temperature balance. This internal circulation design reduces dependence on external heat sources. The ultrasonic auxiliary effect in the pretreatment stage and the gas stripping operation in the regeneration stage form an energy linkage. The micro-jet effect generated by cavitation reduces the energy input requirement of subsequent processes, and the energy efficiency ratio of the overall system reaches the industry's advanced level. DETAILED DESCRIPTION

[0034] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0035] In this application, the sources of various raw materials are briefly described as follows:

[0036] γ-Aminopropyltriethoxysilane: purchased from Hubei Haorong Biotechnology Co., Ltd., CAS No. 919-30-2, model KH-550.

[0037] Vinyltrimethoxysilane: purchased from Hubei Jusheng Technology Co., Ltd., CAS No. 2768-02-7, model YDH-171.

[0038] Sodium lauryl sulfate: purchased from Shandong Tongfengqi Chemical Co., Ltd., CAS number 151-21-3, model needle-shaped K12.

[0039] Tween 80: purchased from Nanjing Songguan Biotechnology Co., Ltd., CAS No. 9005-65-6.

[0040] Sodium molybdate: purchased from Hubei Xinmingtai Chemical Co., Ltd., CAS No. 7631-95-0, model is industrial grade.

[0041] Benzotriazole: purchased from Nanjing Well Chemical Co., Ltd., CAS No. 95-14-7, model BTA.

[0042] Methyldiethanolamine: purchased from Hubei Chengfeng Chemical.

[0043] Aminoethylpiperazine: purchased from Shanghai Yien Chemical.

[0044] Sulfuric acid and sodium hydroxide were purchased from Sinopharm Group as analytical reagents with CAS numbers of 7664-93-9 and 1310-73-2, respectively.

[0045] A method for low-temperature regeneration of a carbon dioxide absorption rich solution, comprising the following steps:

[0046] Pretreatment stage: The rich liquid is filtered through a ceramic membrane with a pore size of 0.5-2 μm to remove suspended particles;

[0047] Modification treatment stage: Add the composite modifier to the pretreated rich liquid and perform mechanical oscillation, with the oscillation frequency controlled at 100-300 rpm;

[0048] Regeneration stage: nitrogen is introduced at 60-75°C and 0.2-0.4 MPa to perform gas stripping regeneration;

[0049] Separation stage: A multi-stage condensation system is used to capture the released carbon dioxide gas, and the regenerated lean liquid is returned to the absorption after pH adjustment;

[0050] The composite modifier in the modification treatment stage is prepared by compounding a silane coupling agent and a surfactant in a mass ratio of 3-5:1.

[0051] The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane;

[0052] The surfactant is prepared by compounding sodium lauryl sulfate and Tween 80 in a mass ratio of 2-4:1.

[0053] The modification treatment stage specifically comprises the following steps: heating the rich solution to 40-50°C, adding the composite modifier dropwise at a rate of 0.5-2 mL / min, and maintaining stirring for 30-60 minutes after the addition is complete at a stirring rate of 200-400 rpm; mechanically oscillating the solution using an eccentric vibration device with an amplitude of 2-5 mm and a vibration time of 20-40 minutes; and simultaneously applying 20-40 kHz ultrasonic waves during the vibration treatment, with a sound intensity controlled at 0.5-1.5 W / cm² and an action time of 5-15 minutes.

[0054] The total addition amount of the composite modifier is 0.5-3% of the mass of the rich liquid.

[0055] The regeneration treatment stage includes three stages of gas stripping towers in series, with the first stage operating at 60-65°C and a pressure of 0.25-0.35 MPa, the second stage at 63-68°C and a pressure of 0.2-0.3 MPa, and the third stage at 68-75°C and a pressure of 0.15-0.25 MPa.

[0056] The nitrogen flow rate of each stage of the stripping tower is 1.2-2 times the volume flow of the rich liquid, and the gas-liquid contact time is controlled at 5-15 minutes.

[0057] The absorbent of the rich liquid includes a main absorbent methyldiethanolamine and an auxiliary absorbent aminoethylpiperazine, and the mass ratio of the main absorbent methyldiethanolamine to the auxiliary absorbent aminoethylpiperazine is 4-6:1.

[0058] The concentration of the main absorbent methyldiethanolamine is 25%-35% (w / w), and the concentration of the auxiliary absorbent aminoethylpiperazine is 5%-10% (w / w).

[0059] The absorbent further contains 0.1%-0.5% (w / w) of a corrosion inhibitor, which is prepared by compounding sodium molybdate and benzotriazole in a mass ratio of 1:2-4.

[0060] The pretreatment stage adopts three-stage series filtration, wherein the first stage is a 50 μm metal filter, the second stage is a 5 μm cellulose filter membrane, and the third stage is a 1 μm ceramic membrane; the operating pressure of the three-stage filtration is 0.1-0.3 MPa.

[0061] In the separation stage, the multi-stage condensation system includes three stages of gradient cooling: the first stage is cooled to 10-15°C, the second stage is 5-8°C, and the third stage is -5-0°C. Each stage is equipped with a gas-liquid separation device.

[0062] The pH value of the regenerated lean solution is adjusted by a step-by-step addition method: first, 0.1 mol / L sulfuric acid is added to adjust the pH value to 9-10, and then 0.05 mol / L sodium hydroxide is added to fine-tune the pH value to 10.5-11.2.

[0063] The technical solution of the present invention is further illustrated by the following examples and comparative examples, but the protection scope of the present invention is not limited thereto.

[0064] Example 1

[0065] The pretreatment stage employed a three-stage filtration system in series, with the first stage consisting of a 50μm metal mesh, the second stage consisting of a 5μm cellulose membrane, and the third stage consisting of a 1μm ceramic membrane. The operating pressure for each stage was set at 0.2 MPa. During the modification stage, the rich solution was heated to 40°C, and a composite modifier (3% total addition) was added dropwise at a rate of 0.5 mL / min. The modifier consisted of a 5:1 mass ratio of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane, and the surfactant was a 4:1 mass ratio of sodium lauryl sulfate and Tween 80. Following the addition, the solution was stirred at 400 rpm for 20 minutes, followed by mechanical shaking (amplitude 0.5 mm, frequency 300 rpm, duration 40 minutes) and simultaneous application of 20kHz ultrasonic waves (intensity 1.5 W / cm², duration 5 minutes).

[0066] The regeneration stage employed three gas stripping towers in series, with parameters of 63°C / 0.3 MPa, 65°C / 0.25 MPa, and 70°C / 0.2 MPa. The nitrogen flow rate was 1.6 times the rich liquid volume flow rate, and the gas-liquid contact time was 10 minutes. The absorbent was a 6:1 mixture of methyldiethanolamine (30% w / w) and aminoethylpiperazine (10% w / w), and the corrosion inhibitor was a 1:4 mixture of sodium molybdate and benzotriazole (total concentration 0.5% w / w). The separation stage employed three-stage condensation (12°C → 6°C → -2°C). The regenerated lean liquid was first adjusted to a pH of 10 with 0.1 mol / L sulfuric acid and then fine-tuned to a pH of 11.0 with 0.05 mol / L sodium hydroxide.

[0067] Example 2

[0068] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0069] The pretreatment phase involved three stages of filtration at an operating pressure of 0.1 MPa. The composite modifier consisted of vinyltrimethoxysilane (mass ratio 3:1) and a surfactant (sodium lauryl sulfate: Tween 80 = 2:1), with a total addition amount of 0.5%. The rich solution was heated to 50°C, added at a drip rate of 2 mL / min, stirred at 200 rpm for 30 minutes, and mechanically oscillated at an amplitude of 2 mm, a frequency of 100 rpm, and a duration of 60 minutes. Ultrasonic parameters were set at 40 kHz, 1.5 W / cm², and 15 minutes.

[0070] The three-stage stripping tower parameters for the regeneration stage were 60°C / 0.25 MPa, 63°C / 0.2 MPa, and 68°C / 0.15 MPa. The nitrogen flow rate was 1.2 times the rich liquid volume flow rate, and the gas-liquid contact time was 5 minutes. The absorbent formulation consisted of a 4:1 mixture of methyldiethanolamine (25% w / w) and aminoethylpiperazine (5% w / w), and the corrosion inhibitor was a 1:2 ratio of sodium molybdate to benzotriazole (0.1% w / w). The condensation temperature gradient was 10°C → 5°C → -5°C, and the pH was adjusted to 10.5 using a two-step process.

[0071] Example 3

[0072] In this embodiment, the same points as in Example 1 are not described in detail, and the differences are as follows:

[0073] During the pretreatment phase, the filtration system operated at a pressure of 0.3 MPa. The composite modifier consisted of γ-aminopropyltriethoxysilane (mass ratio 4:1) and a surfactant (sodium lauryl sulfate:Tween 80 = 3:1), with a total addition amount of 1.8%. The rich solution was heated to 45°C, dripped at a rate of 1.2 mL / min, stirred at 300 rpm for 45 minutes, and mechanically oscillated at an amplitude of 3 mm, a frequency of 200 rpm, and a duration of 30 minutes. Ultrasonic parameters were 30 kHz, 1.0 W / cm², and 10 minutes.

[0074] The regeneration stage consisted of a three-stage stripping tower. The first stage operated at 65°C and 0.35 MPa, the second at 68°C and 0.3 MPa, and the third at 75°C and 0.25 MPa. Nitrogen was introduced at a rate twice the rich liquid volume flow rate, and the gas-liquid contact time was 15 minutes. The absorbent was a 5:1 mixture of methyldiethanolamine (35% w / w) and aminoethylpiperazine (7.5% w / w), and the corrosion inhibitor was a 1:3 ratio of sodium molybdate to benzotriazole (0.3% w / w). The condensation system was set at a temperature of 15°C → 8°C → 0°C. After pH adjustment, the pH was stabilized at 11.2.

[0075] Comparative Example 1

[0076] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0077] No composite modifiers added.

[0078] Comparative Example 2

[0079] In this comparative example, the same points as Example 2 are not repeated here, and the differences are as follows:

[0080] A single silane coupling agent (γ-aminopropyltriethoxysilane) was used and the surfactant was pure sodium dodecyl sulfate.

[0081] Comparative Example 3

[0082] In this comparative example, the same points as in Example 3 are not repeated here, and the differences are as follows:

[0083] The three-stage stripping towers all use the same temperature (70°C) and pressure (0.2MPa).

[0084] Comparative Example 4

[0085] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0086] The ultrasonic assistance was cancelled and the mechanical shaking time was extended to 60 min.

[0087] Comparative Example 5

[0088] In this comparative example, the same points as in Example 1 are not repeated here, and the differences are as follows:

[0089] The pH was adjusted by a single addition of acid to pH 11.2, eliminating the sodium hydroxide correction step.

[0090] Test results and analysis

[0091] The carbon dioxide absorption rich liquid low-temperature regeneration was carried out according to the parameters of the embodiment and the comparative example, and the results were tested. The test results are specifically shown in Table 1.

[0092] Table 1 Analysis and test results

[0093]

[0094] As can be seen from Table 1, when comparing Example 1 with Comparative Example 1, the desorption efficiency decreased by 14.8% when no modifier was added, verifying that the synergistic effect of the silane coupling agent and the surfactant can reduce the desorption energy barrier. From Example 3 and Comparative Example 3, it can be seen that the uniform temperature operation resulted in a 6.2% decrease in desorption efficiency, demonstrating that the temperature-pressure gradient design can optimize thermodynamic equilibrium.

[0095] In Comparative Example 4, energy consumption increased by 23.8% after the ultrasonic wave was eliminated, indicating that the cavitation effect can enhance mass transfer. In Comparative Example 5, single acid adjustment resulted in an increase of 2.3% in absorbent loss rate, confirming that step-by-step adjustment can avoid local overreaction.

[0096] The continuous operation of Example 1 for 125 days far exceeds the 45 days of Comparative Example 1, which is due to the optimization of the corrosion inhibitor compounding and the filtration system.

[0097] The data in Table 1 show that the multi-dimensional synergistic solution of the present invention is significantly superior to the existing technology in terms of desorption efficiency, energy consumption control and system stability, especially achieving a desorption efficiency of more than 95% under low temperature conditions, verifying the beneficial effects described in the technical solution.

[0098] This application achieves efficient low-temperature regeneration through the synergistic effect of composite modifiers and multi-stage processes. Its core advantage is reflected in the systematic improvement of the pain points of traditional processes. The molecular design of silane coupling agents and surfactants forms a directional bonding effect, which reduces the binding energy between absorbent molecules. Combined with mechanical oscillation and ultrasonic cavitation effect, a stable microbubble network is constructed in the solution, which significantly enhances the mass transfer efficiency of the gas-liquid interface, and greatly reduces the thermodynamic energy barrier of the carbon dioxide desorption process. The step-by-step depressurization operation of the three-stage gas stripping tower precisely controls the pressure gradient. The front section uses higher pressure to promote the activation and conversion of chemically bound carbon dioxide. The middle and rear sections gradually release the pressure to form a desorption driving force, and cooperate with the dynamic displacement of nitrogen carrier gas to effectively break the gas-liquid two-phase equilibrium, so that the regeneration temperature is significantly lower than that of conventional steam heating processes. The step-by-step pH adjustment strategy adopts an acid-base staged neutralization method. First, the excess alkaline substance is neutralized with a weak acid to avoid local over-reaction, and then a trace amount of alkali solution is used to adjust it back to the optimal absorption range. This dynamic equilibrium adjustment mechanism not only inhibits colloid precipitation but also maintains solution stability. It cooperates with the phase change separation characteristics of the gradient condensation system to achieve efficient recovery of amine substances. The ceramic membrane filtration system's gradient pore size design and surface hydrophilic modification form a dual barrier, progressively intercepting impurities of varying particle sizes while mitigating membrane fouling. A complex system of molybdate and organic corrosion inhibitors creates a dense passivation layer on the device surface, significantly suppressing corrosion through the synergistic effects of electrochemical protection and molecular adsorption. The energy synergy network combines the ultrasonic cavitation effect of the pretreatment stage with thermodynamic optimization during the regeneration stage. The micro-jet effect generated by cavitation collapse reduces subsequent gas lift energy consumption, while the internal recycling of condensation waste heat reduces reliance on external energy sources. This creates a closed loop for improving energy efficiency for the entire system, ultimately achieving simultaneous optimization of absorbent performance and device life under low-temperature conditions.

[0099] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for low-temperature regeneration of carbon dioxide absorption rich liquid, characterized in that: The method comprises the following steps: Pretreatment stage: The rich liquid is filtered through a ceramic membrane with a pore size of 0.5-2 μm to remove suspended particles; Modification treatment stage: Add the composite modifier to the pretreated rich liquid and perform mechanical oscillation, with the oscillation frequency controlled at 100-300 rpm; Regeneration stage: nitrogen is introduced at 60-75°C and 0.2-0.4 MPa to perform gas stripping regeneration; Separation stage: A multi-stage condensation system is used to capture the released carbon dioxide gas, and the regenerated lean liquid is returned to the absorption after pH adjustment; The composite modifier in the modification treatment stage is prepared by compounding a silane coupling agent and a surfactant in a mass ratio of 3-5:1; in the separation stage, the multi-stage condensation system includes three stages of gradient cooling, the first stage is cooled to 10-15°C, the second stage is cooled to 5-8°C, and the third stage is cooled to -5-0°C, and a gas-liquid separation device is provided at each stage; The pH value of the regenerated lean solution is adjusted by a step-by-step addition method: first, 0.1 mol / L sulfuric acid is added to adjust the pH value to 9-10, and then 0.05 mol / L sodium hydroxide is added to fine-tune the pH value to 10.5-11.

2.

2. The method for low-temperature regeneration of a carbon dioxide absorption rich solution according to claim 1, characterized in that: The silane coupling agent is at least one of γ-aminopropyltriethoxysilane and vinyltrimethoxysilane; The surfactant is prepared by compounding sodium lauryl sulfate and Tween 80 in a mass ratio of 2-4:

1.

3. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 1, characterized in that: The modification treatment stage specifically comprises the following steps: heating the rich solution to 40-50°C, adding the composite modifier dropwise at a rate of 0.5-2 mL / min, and maintaining stirring for 30-60 minutes after the addition is complete at a stirring rate of 200-400 rpm; mechanically oscillating the solution using an eccentric vibration device with an amplitude of 2-5 mm and a vibration time of 20-40 minutes; and simultaneously applying 20-40 kHz ultrasonic waves during the vibration treatment, with a sound intensity controlled at 0.5-1.5 W / cm² and an action time of 5-15 minutes.

4. The method for low-temperature regeneration of a carbon dioxide absorption rich solution according to claim 1, characterized in that: The total addition amount of the composite modifier is 0.5-3% of the mass of the rich liquid.

5. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 1, characterized in that: The regeneration treatment stage includes three stages of gas stripping towers in series, with the first stage operating at 60-65°C and a pressure of 0.25-0.35 MPa, the second stage at 63-68°C and a pressure of 0.2-0.3 MPa, and the third stage at 68-75°C and a pressure of 0.15-0.25 MPa. The nitrogen flow rate of each stage of the stripping tower is 1.2-2 times the volume flow of the rich liquid, and the gas-liquid contact time is controlled at 5-15 minutes.

6. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 1, characterized in that: The absorbent of the rich liquid includes a main absorbent methyldiethanolamine and an auxiliary absorbent aminoethylpiperazine, and the mass ratio of the main absorbent methyldiethanolamine to the auxiliary absorbent aminoethylpiperazine is 4-6:

1.

7. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 6, characterized in that: The concentration of the main absorbent methyldiethanolamine is 25%-35% (w / w), and the concentration of the auxiliary absorbent aminoethylpiperazine is 5%-10% (w / w).

8. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 6, characterized in that: The absorbent further contains 0.1%-0.5% (w / w) of a corrosion inhibitor, which is prepared by compounding sodium molybdate and benzotriazole in a mass ratio of 1:2-4.

9. The method for low-temperature regeneration of carbon dioxide absorption rich liquid according to claim 1, characterized in that: The pretreatment stage adopts three-stage series filtration, wherein the first stage is a 50 μm metal filter, the second stage is a 5 μm cellulose filter membrane, and the third stage is a 1 μm ceramic membrane; the operating pressure of the three-stage filtration is 0.1-0.3 MPa.

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