Method for preventing formation of nitramine in carbon dioxide absorption process

Abstract

The invention relates to the technical field of carbon dioxide capture, in particular to a method for preventing formation of nitramine in a carbon dioxide absorption process, which comprises the following steps: S1, selecting a proper amine solvent, and replacing traditional monoethanolamine (MEA) or diethanolamine (DEA) with an improved amine solvent, such as an amino acid salt solution or chain alkylamine; the performance of the solvent is optimized, and an amine solvent which is excellent in long-term stability, easy to regenerate and good in thermodynamic property is selected. By optimizing the operation temperature and pressure, the side reaction is inhibited to the maximum extent, each absorption tower section is finely controlled by adopting a sectional absorption process, and the nitramine generation risk is further reduced; through comprehensive application of a novel amine solvent and a nitramine inhibitor and a combined strategy for optimizing operation conditions, an efficient, stable and environment-friendly carbon dioxide absorption method is provided, the absorption capacity is improved, and the excellent solvent regeneration performance and by-product control capacity are further provided.

Description

Technical Field

[0001] The invention relates to the technical field of carbon dioxide capture, and in particular to a method for preventing nitramines from being formed during the carbon dioxide absorption process. Background Art

[0002] As global attention to climate change increases and carbon reduction actions are carried out in depth, carbon dioxide absorption technology has flourished, among which chemical absorption is favored due to its high efficiency and flexibility. This method mostly uses amine absorbents (such as monoethanolamine, diethanolamine, methyldiethanolamine, etc.) to achieve efficient gas capture and separation by using the reversible chemical reaction between amine groups and carbon dioxide. However, the actual working conditions are complicated, and the absorption system is often mixed with impurity gases and faces a complex redox environment.

[0003] Carbon dioxide absorption is commonly used to reduce emissions and capture carbon dioxide to help mitigate global warming. However, when using amine compounds as solvents for carbon dioxide absorption, harmful byproducts such as nitramines may be formed. Nitramine compounds are known carcinogens, so it is crucial to prevent the formation of nitramines during the carbon dioxide capture process. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a method for preventing the formation of nitramines during the carbon dioxide absorption process, which can effectively solve the problem that when the prior art uses amine compounds as solvents for carbon dioxide absorption, harmful by-products such as nitramines, nitramine compounds and other known carcinogens may be formed.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a method for preventing the formation of nitramines during carbon dioxide absorption, comprising the following steps: S1, choose the appropriate amine solvent Use improved amine solvents, such as amino acid salt solutions or chain alkylamines instead of traditional monoethanolamine or diethanolamine; Optimize the performance of the solvent and select amine solvents with excellent long-term stability, easy regeneration and good thermodynamic properties; S2, adding nitramine inhibitor Selection of inhibitors: adding specific antioxidants and free radical scavengers to the absorption solvent, and nitramine inhibitors are selected as antioxidants; The proportion of inhibitor added is precisely controlled to ensure that it does not negatively affect the absorption performance of the solvent, and is dynamically adjusted based on the real-time monitoring of nitramine concentration; S3, Optimize operating conditions Precisely control the temperature and pressure, and determine the optimal operating temperature and pressure range of the absorption tower through reaction kinetics calculation and simulation to maximize the adsorption and desorption efficiency of the solvent while suppressing the occurrence of side reactions; The segmented absorption process deploys multiple absorption tower sections, each section is equipped with an independent control system to adjust the temperature and flow rate separately, so as to deal with the absorption characteristics and chemical reactions at different stages in a targeted manner; S4, online monitoring and control Monitor the gas composition at the outlet of the absorption tower to ensure timely detection of trace nitramines and their precursors; Automated feedback control, establishing intelligent control algorithms, automatically optimize operating conditions based on real-time monitoring data, such as adjusting the solvent circulation rate or the amount of inhibitor added, to achieve dynamic prevention and control.

[0006] S5, regular solvent regeneration and purification Regeneration method and equipment configuration: using advanced thermal regeneration system, combined with vacuum distillation or selective filtration technology to remove unstable components such as nitramines; Solvent performance testing and analysis: After each regeneration process, a comprehensive solvent performance test and chemical analysis is performed to ensure that no harmful components remain and to evaluate the overall absorption efficiency and status of the solvent.

[0007] According to the above method for preventing nitramine from being formed during carbon dioxide absorption, the improved solvent is selected from one of a chain alkylamine solution or an amino acid solution.

[0008] According to the above method for preventing the formation of nitramines during the carbon dioxide absorption process, the alkylamine is a methyldiethanolamine solution.

[0009] According to the above method for preventing the formation of nitramines during the carbon dioxide absorption process, the operating temperature of the absorption tower is maintained between 30-50°C.

[0010] According to the above-mentioned method for preventing the formation of nitramines during the carbon dioxide absorption process, the operating pressure range of the absorption tower is 1-3 MPa.

[0011] According to the above method for preventing nitramines from being formed during carbon dioxide absorption, when analyzing the gas composition at the outlet of the absorption tower, a highly sensitive gas chromatograph or mass spectrometer is used to analyze the gas composition at the outlet of the absorption tower in real time.

[0012] According to the above-mentioned method for preventing the formation of nitramines during the carbon dioxide absorption process, the concentrations of nitramines and precursors in the solvent are regularly detected using high-precision analytical equipment such as gas chromatography-mass spectrometry, and nitramines and their precursors are selectively oxidized and decomposed by adding an oxidant such as hydrogen peroxide to the solvent system to remove the existing nitramine precursor substances and the generated nitramine.

[0013] According to the above method for preventing nitramines from being formed during carbon dioxide absorption, the antioxidant is selected from vitamin C or di-tert-butylhydroxytoluene.

[0014] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects: The present invention replaces traditional monoethanolamine (MEA) or diethanolamine (DEA) with amino acid salt solution or chain alkylamine. The amino acid salt solution combines the dual characteristics of amine and alkaline metal salt and can absorb carbon dioxide with high efficiency.

[0015] The present invention optimizes the operating temperature and pressure to maximize the carbon dioxide absorption capacity and inhibit side reactions, and adopts a segmented absorption process to achieve fine control of each absorption tower section, thereby further reducing the risk of nitramine generation.

[0016] In the present invention, each regeneration stage is supplemented with solvent performance detection and analysis to ensure the activity and safety of the solvent. Gas chromatography-mass spectrometry provides accurate quantitative analysis of the nitramine concentration in the solvent. Adding an appropriate amount of hydrogen peroxide to the solvent can selectively oxidize and decompose the residual nitramine and its precursor.

[0017] In general, the present invention provides an efficient, stable and environmentally friendly carbon dioxide absorption method through the comprehensive application of new amine solvents, nitramine inhibitors and a combined strategy for optimizing operating conditions. It not only has improved absorption capacity, but also provides excellent solvent regeneration performance and by-product control capabilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 It is a schematic block diagram of the process of the present invention. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] The present invention will be further described below in conjunction with the embodiments.

[0022] Example: Refer to Figure 1 , a method for preventing the formation of nitramines during carbon dioxide absorption, comprising the steps of: S1, choose the appropriate amine solvent Improved amine solvents such as amino acid salt solutions or chain alkylamines are used to replace traditional monoethanolamine (MEA) or diethanolamine (DEA). Amino acid salt solutions combine the dual characteristics of amines and alkaline metal salts, can efficiently absorb carbon dioxide, while reducing volatility and reactivity, thereby reducing the formation of by-products such as nitramines. By selecting and using improved amine solvents such as amino acid salt solutions or chain alkylamines to replace traditional MEA or DEA, the use of amino acid salt solutions in this process significantly improves the system's carbon dioxide absorption capacity. Based on its dual characteristics, it reduces the volatility and reactivity of the solvent, thereby reducing the formation of nitramines.

[0023] Chain alkylamine uses methyldiethanolamine (MDEA), which has lower reactivity and higher selectivity, and can reduce the probability of nitramine formation. Methyldiethanolamine (MDEA) in chain alkylamine is an option with lower reactivity and higher selectivity, which further reduces the probability of nitramine formation.

[0024] The performance of the solvent is optimized. The selected amine solvent should have excellent long-term stability and easy regeneration as well as thermodynamic properties. The selected amine solvent should have excellent long-term stability and easy regeneration to reduce operating costs and solvent loss. The design of new solvents needs to consider thermodynamic properties so that they can effectively absorb carbon dioxide at lower temperatures and easily release the adsorbed carbon dioxide during the regeneration process.

[0025] S2, adding nitramine inhibitor Selection of inhibitors: adding specific antioxidants and free radical scavengers to the absorption solvent to inhibit the formation of nitramines. Vitamin C, as a water-soluble antioxidant, reacts with oxygen free radicals to generate harmless products, such as dehydroascorbic acid (DHA), thereby avoiding the attack of free radicals on amine substances. The generation of free radicals is usually a catalytic factor in the nitramine synthesis reaction. Therefore, vitamin C can significantly reduce the formation of nitramines by effectively eliminating these free radicals. Vitamin C has a strong electron supply capacity and can capture free radicals and prevent free radical chain reactions in the reaction, thereby maintaining the stability of the system and reducing the generation of potential harmful substances.

[0026] As a fat-soluble antioxidant, BHT can effectively reduce the formation of nitramines by preventing free radical chain reactions. BHT interrupts the free radical reaction chain by donating hydrogen atoms, preventing the expansion of free radicals, thereby reducing the chance of free radicals reacting with amines. Unlike water-soluble antioxidants (such as vitamin C), BHT is more suitable for reaction inhibition in fat-soluble media. Its stability and high efficiency in lipid systems make it a common choice in industrial applications.

[0027] In the process of inhibiting the formation of nitramines, the selection of inhibitors plays a key role. These compounds neutralize or eliminate the effects of free radicals, thereby reducing the reaction between amines and nitrates and inhibiting the formation of nitramines. Specific antioxidants and free radical scavengers are added to the absorption solvent to inhibit the formation of nitramines. Vitamin C, as a water-soluble antioxidant, reacts with oxygen free radicals to generate harmless products, thereby avoiding the attack of free radicals on amines to form nitramines. The fat-soluble antioxidant BHT interrupts the free radical chain reaction by delivering hydrogen atoms, further preventing the formation of nitramines.

[0028] The proportion of inhibitors added should be precisely controlled to ensure that there is no negative impact on the absorption performance of the solvent, and dynamic adjustments should be made based on the real-time monitoring of nitramine concentration. In practical applications, the proportion of inhibitors added needs to be precisely controlled to ensure that they can effectively inhibit the formation of nitramines without affecting the performance of the absorption solvent. Excessive inhibitors may interfere with the absorption capacity of the solvent or reduce the overall efficiency of the solvent. Therefore, when selecting and adding antioxidants, it is necessary to comprehensively consider the physical and chemical properties of the solvent, especially the balance between absorption performance and antioxidant capacity. By optimizing the concentration of inhibitors, the effectiveness of the solvent can be maintained while avoiding the formation of nitramines.

[0029] S3, Optimize operating conditions The temperature is precisely controlled as pressure. Through reaction kinetic calculation and simulation, the optimal operating temperature and pressure range of the absorption tower can be determined to maximize the adsorption and desorption efficiency of the solvent while suppressing the occurrence of side reactions. During the absorption process, it is usually necessary to accurately adjust the temperature by heating or cooling to ensure that the solvent can fully absorb the target substance in the adsorption stage and can efficiently release the adsorbed components in the desorption stage. Temperature control not only affects the adsorption and desorption rates of the solute, but also suppresses the occurrence of side reactions, such as the formation of nitramines. By simulating the behavior of reactants at different temperatures, the optimal temperature range can be found, thereby ensuring efficient solvent adsorption and desorption without side reactions.

[0030] By optimizing the operating temperature and pressure, we can significantly affect the adsorption and desorption efficiency of the solvent. Reaction kinetics simulation guides the temperature and pressure settings of the absorption tower to maximize the carbon dioxide absorption capacity and inhibit side reactions. Lower temperatures help reduce the formation of nitramines. It is generally recommended to keep the temperature between 30-50°C. Higher temperatures will accelerate the reaction between amine solutions and carbon dioxide, thereby increasing the risk of nitramine formation. Moderate pressure helps to increase the solubility of carbon dioxide, but excessive pressure may promote the formation of nitramines. Usually, a pressure between 1-3 MPa is ideal, which can effectively absorb carbon dioxide and reduce the formation of by-products.

[0031] Pressure also has an important influence on the operating performance of the absorption tower. Too high pressure may lead to excessive adsorption of the solvent and reduce the desorption efficiency; while too low pressure may lead to insufficient adsorption of the target substance and reduce the absorption efficiency. By calculating the adsorption and desorption rates under different pressures, the optimal range of operating pressure can be determined. Considering factors such as the physicochemical properties of the solvent, the vapor pressure of the target substance, and the reaction kinetics during the simulation process can help optimize the pressure operating conditions and ensure that the reaction system operates efficiently at an appropriate pressure.

[0032] The segmented absorption process deploys multiple absorption tower sections, each section is equipped with an independent control system to adjust the temperature and flow rate respectively, so as to deal with the absorption characteristics and chemical reactions at different stages in a targeted manner, so as to effectively reduce the risk of nitramine formation. Through the segmented design, the operating conditions of each section can be precisely adjusted, thereby effectively inhibiting side reactions, especially the formation of harmful compounds such as nitramine. In some absorption sections, low temperature and low pressure conditions may be required to reduce the formation of free radicals and the synthesis of nitramine; while in other sections, the desorption efficiency of the target substance can be improved by appropriately raising the temperature and increasing the flow rate. Through such targeted adjustment, not only the absorption efficiency of the solvent is improved, but also the risk of the formation of by-products such as nitramine is minimized. At the same time, the segmented absorption process is used to achieve fine control of each absorption tower section to further reduce the risk of nitramine formation.

[0033] S4, online monitoring and control Monitor the gas composition at the outlet of the absorption tower to ensure timely detection of trace nitramines and their precursors. When analyzing the gas composition at the outlet of the absorption tower, use a highly sensitive gas chromatograph or mass spectrometer, and analyze the gas composition at the outlet of the absorption tower in real time to ensure timely detection of trace nitramines and their precursors. Gas chromatography technology can effectively separate complex components in the gas. By combining with thermal conductivity detectors (TCDs) and flame ionization detectors (FIDs), it can detect trace amounts of nitramines in the gas composition. The advantages of gas chromatographs are good separation effects and high sensitivity, which are suitable for long-term monitoring. Mass spectrometers can provide higher qualitative and quantitative analysis capabilities, especially for nitramines and their precursors with complex structures and extremely low concentrations. Mass spectrometers can detect characteristic ions through mass-to-charge ratios (m / z) to accurately identify and analyze various compounds. The gas chromatograph-mass spectrometer combination technology performs well in complex gas analysis and is suitable for real-time monitoring of trace nitramines.

[0034] Automated feedback control, establish intelligent control algorithms, automatically optimize operating conditions based on real-time monitoring data, such as adjusting the solvent circulation rate or the amount of inhibitors added to achieve dynamic prevention and control. The solvent circulation rate directly affects the efficiency of adsorption and desorption. A lower circulation rate may cause the solvent to stay in the absorption tower for too long, thereby increasing the probability of side reactions. By real-time monitoring of the concentration of nitramines and precursor substances, the system can dynamically adjust the solvent circulation rate to operate within the most appropriate range, thereby reducing the occurrence of side reactions; according to the real-time monitoring of nitramine generation, the automated system can increase or decrease the dosage of antioxidants and free radical scavengers in a timely manner. For example, when the nitramine concentration increases, the system can automatically increase the dosage of inhibitors such as BHT and vitamin C to inhibit free radical reactions and prevent nitramine generation. Through this dynamic control, the absorption and desorption performance of the solvent can be accurately regulated to minimize the generation of by-products.

[0035] High-sensitivity gas chromatographs or mass spectrometers are used to perform real-time gas analysis at the outlet of the absorption tower. Through intelligent control algorithms, the system can automatically adjust operating conditions based on real-time monitoring data; this feedback mechanism ensures the system's dynamic response to uncontrollable factors, thereby efficiently managing nitramine generation.

[0036] S5, regular solvent regeneration and purification Regeneration method and equipment configuration, using advanced thermal regeneration system, combined with vacuum distillation or selective filtration technology, to remove unstable components such as nitramine, while recovering and improving the reuse capacity of solvents. To ensure efficient reuse of solvents and their low impact on the environment and equipment, the use of advanced thermal regeneration systems is the current trend. These systems heat the waste solvent to a specific temperature to effectively desorb dissolved impurities while maximizing the purity and effectiveness of the solvent. The regeneration process is usually combined with vacuum distillation technology to lower the boiling point of the solvent, reduce the risk of thermal decomposition, and further improve the solvent recovery rate. It is particularly suitable for solvents with higher boiling points.

[0037] In addition, the combination of selective filtration technology can efficiently remove specific pollutants. For example, for unstable components such as nitramine that may be generated in the solvent, special filtration media such as activated carbon filter membranes and ion exchange resins can be used to achieve a deep purification effect. Through this process, not only can harmful substances such as nitramine be removed, but the solvent's efficient adsorption capacity can also be restored, thereby extending the solvent's service life.

[0038] Solvent performance testing and analysis: After each regeneration process, a comprehensive solvent performance test and chemical analysis are carried out to ensure that there are no residual harmful components and to evaluate the overall absorption efficiency and status of the solvent. High-precision analytical equipment such as gas chromatography-mass spectrometry (GC-MS) is used regularly to detect the concentration of nitramines and precursors in the solvent. By adding oxidants such as hydrogen peroxide to the solvent system, nitramines and their precursors are selectively oxidized and decomposed to remove existing nitramine precursors and generated nitramines. In terms of solvent performance testing and analysis, gas chromatography-mass spectrometry (GC-MS) technology provides a high-precision analytical method that can quantitatively detect trace amounts of nitramines and their precursors in the solvent, and effectively decompose nitramines and their precursors through selective oxidation, thereby removing potential sources of pollution. This method can not only ensure the purity of the regenerated solvent, but also avoid the risk of nitramine formation and improve the operating stability of the entire system.

[0039] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preventing the formation of nitramines during carbon dioxide absorption, characterized in that The following steps are involved: S1, choose the appropriate amine solvent: Use improved amine solvents instead of monoethanolamine or diethanolamine; Optimize the performance of the solvent and choose amine solvents; S2, adding nitramine inhibitor: Selection of inhibitors: adding antioxidants and free radical scavengers to the absorption solvent, and selecting nitramine inhibitors as antioxidants; Control the proportion of inhibitor added and adjust it dynamically according to the real-time monitoring of nitramine concentration; S3, optimize operating conditions: Control temperature and pressure, and determine the optimal operating temperature and pressure range of the absorption tower through reaction kinetics calculation and simulation to maximize the adsorption and desorption efficiency of the solvent while inhibiting the occurrence of side reactions; The segmented absorption process deploys multiple absorption tower sections, each of which is equipped with an independent control system to adjust the temperature and flow rate respectively, and specifically handle the absorption characteristics and chemical reactions at different stages; S4, online monitoring and control: Monitor the gas composition at the outlet of the absorption tower and detect trace nitramines and their precursors in real time; Automated feedback control, establishing intelligent control algorithms to automatically optimize operating conditions based on real-time monitoring data; S5, regular solvent regeneration and purification: Regeneration method and equipment configuration, using a thermal regeneration system combined with vacuum distillation or selective filtration technology to remove nitramines; Solvent performance testing and analysis: After each regeneration, a comprehensive solvent performance test and chemical analysis is performed to detect the presence of residual harmful components and to evaluate the overall absorption efficiency and status of the solvent.

2. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: The improved solvent is selected from one of chain alkylamine solution and amino acid solution.

3. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 2, characterized in that: The alkylamine is prepared in the form of a methyldiethanolamine solution.

4. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: The operating temperature of the absorption tower is maintained between 30-50°C.

5. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: The operating pressure range of the absorption tower is 1-3 MPa.

6. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: Use a gas chromatograph or mass spectrometer to analyze the gas composition at the outlet of the absorption tower in real time.

7. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: The concentration of nitramine and its precursor in the solvent is regularly tested using gas chromatography-mass spectrometry equipment. By adding an oxidant such as hydrogen peroxide to the solvent system, nitramine and its precursor are selectively oxidized and decomposed to remove the existing nitramine precursor substances and the generated nitramine.

8. A method for preventing the formation of nitramines during carbon dioxide absorption according to claim 1, characterized in that: The antioxidant is selected from vitamin C or butylated hydroxytoluene.

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