Novel low-energy-consumption analysis method for trapping carbon dioxide in tail gas of marine diesel engine by using composite amine absorbent

Abstract

The invention relates to the technical field of environmental protection, in particular to a novel low-energy-consumption analysis method for trapping carbon dioxide in marine diesel engine tail gas by using a compound amine absorbent, which comprises the following steps: S1, reacting the compound amine absorbent containing amino and carboxyl with carbon dioxide in the marine diesel engine tail gas; and S2, separating the original compound amine absorbent in the step S1 from the tail gas through a selective membrane separation technology. According to the method, low-energy-consumption analysis of the carbon dioxide in the tail gas of the marine diesel engine is realized through the efficient trapping capability of the novel compound amine absorbent and a selective membrane separation technology, and the energy consumption and the operation cost of the system are remarkably reduced. The novel compound amine absorbent has high selectivity and high reaction activity, carbon dioxide can be efficiently captured under the conditions of low temperature and pressure, and the use amount and regeneration energy consumption of the absorbent are reduced; a selective membrane separation technology is used for efficiently separating carbon dioxide and other gas components, so that the purity and the trapping efficiency are improved.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a low-energy consumption analysis method for capturing carbon dioxide in exhaust gas of ship diesel engines using a novel composite amine absorbent. Background Art

[0002] As the global climate change problem becomes increasingly serious, reducing carbon dioxide emissions has become a global consensus. As the main power source for marine transportation, ship diesel engines emit huge amounts of carbon dioxide in their exhaust, which has a significant impact on the environment. Marine transportation is a key component of global trade, and the widespread use of ship diesel engines makes their carbon dioxide emissions one of the important sources of greenhouse gases. According to statistics, the proportion of global ship carbon dioxide emissions in the total emissions of the transportation industry is considerable, which seriously affects the stability of the global climate.

[0003] Traditional carbon dioxide capture methods mainly rely on chemical absorbents, such as amine compounds, which absorb carbon dioxide into a solution through a chemical reaction, and then release the carbon dioxide and regenerate the absorbent by heating. Although this method has been widely used in industry, it has significant limitations: high energy consumption: the regeneration process requires a high-temperature heat source, which consumes a lot of energy and increases operating costs; difficult regeneration: the regeneration efficiency of the absorbent is limited by the rate and equilibrium conditions of the chemical reaction, resulting in incomplete carbon dioxide release, affecting the capture efficiency; corrosion and loss: chemical absorbents are prone to corrosion and degradation under high temperature and high carbon dioxide concentration conditions, increasing the complexity and cost of equipment maintenance. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a low-energy consumption analysis method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent, which can effectively solve the problems of high energy consumption, difficult regeneration, corrosion and loss in the prior art.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: The present invention provides a low-energy consumption analysis method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent, comprising the following steps: S1. Using a composite amine absorbent containing amino and carboxyl groups to react with carbon dioxide in the exhaust gas of a ship diesel engine; S2, separate the original absorbent from the tail gas in S1 through selective membrane separation technology; S3, using low energy consumption thermal regeneration technology, decomposes the reaction products in S1 into carbon dioxide and absorbent.

[0006] Preferably, the composite amine absorbent is prepared by mixing ethylenediamine and malonic acid in a molar ratio of 1:1, and additives need to be added during the preparation of the composite amine absorbent.

[0007] Preferably, the additives include surfactants, corrosion inhibitors and stabilizers.

[0008] Preferably, the selective membrane separation technology uses a polyimide membrane.

[0009] Preferably, the low-energy thermal regeneration technology adopts a multi-stage heat exchange module.

[0010] Preferably, the multi-stage heat exchange module includes a preheater, an evaporator and a condenser.

[0011] Preferably, tail gas pretreatment is performed before S1, and the tail gas pretreatment uses wet scrubbing to remove sulfur oxides and nitrogen oxides.

[0012] Preferably, the wet scrubbing uses a sodium hydroxide solution.

[0013] Preferably, it further comprises an online monitoring module and a control module, wherein the online monitoring module is used to monitor the absorbent concentration, and the control module automatically adjusts the amount of absorbent replenishment according to the real-time data of the absorbent concentration.

[0014] Compared with the known prior art, the technical solution provided by the present invention has the following beneficial effects: 1. The present invention realizes low-energy analysis of carbon dioxide in ship diesel engine exhaust gas through the efficient capture capacity of the new composite amine absorbent and the selective membrane separation technology, which significantly reduces the energy consumption and operating cost of the system. The new composite amine absorbent has high selectivity and high reactivity, can efficiently capture carbon dioxide under low temperature and pressure conditions, and reduce the use of absorbent and regeneration energy consumption; the selective membrane separation technology improves the purity and capture efficiency by efficiently separating carbon dioxide and other gas components, and reduces equipment complexity and maintenance costs. In addition, the use of a multi-stage heat exchange system and waste heat recovery technology effectively reduces the regeneration energy consumption. By optimizing the regeneration process parameters, the operating cost is further reduced, ensuring that the system achieves efficient carbon dioxide capture and regeneration under low energy consumption.

[0015] 2. The use of multi-stage heat exchange system and wet scrubbing pretreatment technology further improves the environmental friendliness and stability of the system, ensuring a long-term, efficient and stable carbon dioxide capture and regeneration process. The multi-stage heat exchange system reduces heat energy loss, optimizes heat energy utilization, and enhances the stability and reliability of the system by gradually recovering and utilizing the heat energy in the capture and regeneration process. The wet scrubbing pretreatment removes sulfur oxides and nitrogen oxides in the exhaust gas before carbon dioxide capture, reduces pollutant concentrations, protects the performance of subsequent equipment, and improves the environmental friendliness of the system. The online monitoring and control system monitors key operating parameters in real time, automatically adjusts operating strategies based on data, realizes real-time optimization and fault warning, and further improves the stability and reliability of the system. Through the comprehensive application of these technologies, the system achieves long-term, efficient and stable carbon dioxide capture and regeneration, ensures efficient operation under various operating conditions, and reduces maintenance costs and downtime. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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.

[0017] Figure 1 is a flow chart of the analytical method of the present invention; Figure 2 For the present invention Figure 1 Flowchart of the online monitoring module and control module. DETAILED DESCRIPTION

[0018] 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.

[0019] The present invention will be further described below in conjunction with the embodiments.

[0020] Example: Refer to Figure 1 to Figure 2 A new type of composite amine absorbent to capture carbon dioxide from ship diesel engine exhaust with low energy consumption analysis method, comprising the following steps: S1. Using a composite amine absorbent containing amino and carboxyl groups to react with carbon dioxide in exhaust gas from a ship diesel engine to generate a reaction product; S2, separate the original composite amine absorbent from the tail gas in S1 through selective membrane separation technology; S3. Use low-energy thermal regeneration technology to decompose the reaction products into carbon dioxide and absorbent.

[0021] The composite amine absorbent is prepared by mixing ethylenediamine and malonic acid in a 1:1 molar ratio. An additive needs to be added during the production process of the composite amine absorbent, so that the composite amine absorbent has the ability to efficiently absorb carbon dioxide.

[0022] Additives include surfactants used to reduce the surface tension of the composite amine absorbent, improve its wettability and dispersibility, and contribute to the efficient absorption of carbon dioxide, corrosion inhibitors used to prevent corrosion of the composite amine absorbent due to chemical reactions during the absorption and analysis process, and stabilizers used to improve the thermal and chemical stability of the absorbent and prevent it from decomposing under high temperature or strong acid and alkali environments. Specifically, the added additives include but are not limited to stabilizers such as potassium dihydrogen phosphate (KH2PO4), enhancers such as polyethyleneimine (PEI), and antioxidants such as vitamin E. The addition of these additives not only enhances the stability of the composite amine absorbent, but also plays a key role in improving its absorption efficiency, extending its service life, and preventing oxidative degradation. Experimental data show that the optimized composite amine absorbent has significantly better absorption capacity and number of cycles in the process of continuous absorption of carbon dioxide than the version without additives.

[0023] Selective membrane separation of imide membranes achieves separation effects with high selectivity and low operating pressure; specifically, a multi-level cross-linked structure design is adopted in the preparation process of polyimide membranes, and the pore size distribution and surface chemical properties of the membrane are optimized by controlling the type and concentration of the cross-linking agent. Experimental results show that this technology can achieve selective separation of target gases (such as a mixture of carbon dioxide and nitrogen) at an operating pressure of only 0.1 MPa, with a selectivity coefficient of more than 98% and remain stable under long-term operation. In addition, the membrane material has good chemical resistance and thermal stability.

[0024] The low-energy heat regeneration technology uses a multi-stage heat exchange module to achieve efficient use of waste heat; specifically, the multi-stage heat exchange module design includes primary, intermediate and advanced heat exchangers, where the primary heat exchanger is responsible for recovering most of the heat in the high-temperature exhaust gas, the intermediate heat exchanger further extracts the remaining heat, and the advanced heat exchanger is used to finely control and adjust the heat energy distribution. Each heat exchanger uses an efficient fin tube structure and corrosion-resistant materials to ensure stable operation under different temperature and pressure conditions.

[0025] Experimental data show that this technology can increase the utilization rate of waste heat to more than 85% under the action of multi-stage heat exchange modules, significantly reducing the energy consumption of the system. In addition, the multi-stage heat exchange module is also equipped with an automatic control system to monitor and adjust the heat exchange efficiency of each level in real time to ensure the optimal operation of the system. The overall technology is not only suitable for efficient heat recovery in the chemical industry, but is also widely used in building materials, food processing and other fields, greatly reducing energy consumption and emissions.

[0026] The multi-stage heat exchange module includes a preheater, an evaporator and a condenser to achieve efficient regeneration of the absorbent. Specifically, the design of the multi-stage heat exchange module ensures the effective transfer and utilization of heat at different stages by optimizing the arrangement and connection of each component. The preheater is responsible for raising the low-temperature waste heat to a suitable temperature to prepare for the subsequent evaporation process; the evaporator uses the preheated heat to evaporate the carbon dioxide in the absorbent to form a carbon dioxide-rich gas; and the condenser is responsible for cooling the evaporated absorbent so that it condenses back into a liquid state for easy recycling.

[0027] In experiments and practical applications, the optimized design of the multi-stage heat exchange module significantly improved the regeneration efficiency of the absorbent, the recycling rate increased by more than 30%, and the system energy consumption was reduced by 25%. In addition, all components in the module are made of high temperature and corrosion resistant materials to ensure the long-term stable operation of the system. In practical applications, this technology not only effectively reduces carbon dioxide emissions, but also demonstrates great potential and broad application prospects in many fields such as chemical industry, environmental protection and energy recovery.

[0028] Tail gas pretreatment is performed before S1, and wet scrubbing is used to remove sulfur oxides and nitrogen oxides; wet scrubbing uses sodium hydroxide solution to achieve efficient removal of sulfur oxides and nitrogen oxides. Specifically, the wet scrubbing system contacts sulfur oxides (SOx) and nitrogen oxides (NOx) in the tail gas by spraying absorption liquid (such as ammonia water or sodium hydroxide solution), and removes them by chemical reaction and physical adsorption. The system design includes multiple scrubbing towers, each of which is equipped with an efficient spray device and packing layer to ensure full contact between the tail gas and the absorption liquid and improve the reaction efficiency.

[0029] Experimental data show that under the best operating conditions, the wet scrubbing system can remove 95% and 80% of SOx and NOx respectively. In addition, the system is equipped with automatic control and monitoring equipment to adjust the spray volume and pH value of the absorption liquid in real time to ensure the best treatment effect. Wet scrubbing technology is not only suitable for tail gas treatment in coal-fired power plants, chemical and metallurgical industries, but also shows significant advantages in treating tail gas with high concentrations of SOx and NOx, greatly reducing environmental pollution and meeting strict emission standards.

[0030] It also includes an online monitoring module and a control module. The online monitoring module is used to monitor the concentration of the absorbent to ensure its effectiveness and regeneration process in the process of capturing carbon dioxide. The control module automatically adjusts the amount of absorbent replenishment according to the real-time data of the absorbent concentration to avoid over- or under-dosage. The main function of the online monitoring module is to monitor the absorbent concentration in real time to ensure its effectiveness in capturing carbon dioxide and the smooth progress of the regeneration process. The control module automatically adjusts the amount of absorbent added based on the real-time data provided by the online monitoring module to avoid excess or insufficient absorbent and ensure stable operation of the system.

[0031] The working principle of the present invention is as follows: First, a composite amine absorbent with high carbon dioxide absorption capacity is prepared. The absorbent is prepared by mixing ethylenediamine (EDA) and malonic acid (MA) in a 1:1 molar ratio. The specific preparation process is as follows: Raw material preparation: Ethylenediamine (EDA): chemical formula C2H8N2, structural formula H2N-CH2-CH2-NH2, malonic acid (MA): chemical formula C3H4O4, structural formula HOOC-CH2-COOH, additives: the additives specifically include the following: Surfactants: used to reduce surface tension and improve wettability and dispersibility.

[0032] For example: polyethylene glycol (PEG), sodium dodecyl sulfate (SDS).

[0033] Corrosion inhibitors: used to prevent corrosion caused by chemical reactions.

[0034] For example: benzotriazole (BTA), sodium nitrate (NaNO3).

[0035] Stabilizer: used to improve thermal and chemical stability.

[0036] For example: trisodium phosphate (Na3PO4), sodium silicate (Na2SiO3).

[0037] Mixing reaction: Equal moles of ethylenediamine and malonic acid are mixed in a suitable solvent (such as water or ethanol), reacted at room temperature or slightly above room temperature, and then additives are gradually added to generate a composite amine absorbent containing amino and carboxyl groups; Then the prepared composite amine absorbent is brought into contact with the exhaust gas of the ship diesel engine, and the carbon dioxide in the exhaust gas is converted into carbamic acid through a chemical reaction. The specific steps are as follows: Contact reaction: The composite amine absorbent is sprayed or injected into the exhaust gas stream of a diesel engine. The carbon dioxide in the exhaust gas reacts chemically with the amino and carboxyl groups in the absorbent to produce carbamic acid.

[0038] Reaction equation: Compound amine absorbent + carbon dioxide → carbamic acid Compound amine absorbent + carbon dioxide → carbamic acid Then, the high selectivity and low operating pressure of the polyimide membrane are used to efficiently separate the absorbent from the tail gas. The specific steps are as follows: Membrane material selection: Polyimide (PI) membrane is used, which has excellent mechanical strength, chemical stability and selective separation performance.

[0039] Separation process: The reacted gas mixture is passed through a polyimide membrane. The selective permeability of the polyimide membrane allows carbon dioxide to be efficiently retained, while the unreacted tail gas components are released through the membrane. The specific principle is as follows: The selective permeability of polyimide membranes is mainly based on their molecular structure and pore size. The membrane pore size is moderate and can selectively pass carbon dioxide while blocking other gas components.

[0040] Then, the waste heat is recycled through a multi-stage heat exchange system to decompose carbamic acid, generate carbon dioxide and absorbent, and thus complete the regeneration of the absorbent. The specific steps are as follows: Multi-stage heat exchange system: The system includes a preheater, an evaporator and a condenser.

[0041] Preheater: Use the waste heat in the tail gas to preheat the absorbent; Evaporator: decomposes carbamic acid into carbon dioxide and absorbent under appropriate temperature and pressure conditions; Condenser: Cools and collects the generated carbon dioxide.

[0042] The reaction direction is: carbamic acid → carbon dioxide + absorbent carbamic acid → carbon dioxide + absorbent In order to further improve the overall efficiency of the system, the method also includes an exhaust gas pretreatment step to remove sulfur oxides and nitrogen oxides through wet scrubbing. The specific steps are as follows: Wet scrubbing: Sodium hydroxide (NaOH) solution was used as a detergent; Sodium hydroxide solution is sprayed into the exhaust gas to react chemically with sulfur oxides (SOx) and nitrogen oxides (NOx) to produce sulfates and nitrates; Through the online monitoring module and the control module, the two modules work together to monitor the absorbent concentration in real time and automatically adjust the amount of absorbent replenishment according to the monitoring data, thereby optimizing the operating performance of the system. The following is a detailed description: Online monitoring module: The main function of the online monitoring module is to monitor the absorbent concentration in real time to ensure its effectiveness in capturing carbon dioxide and the smooth progress of the regeneration process. The specific functions and operations are as follows: Sensor arrangement: High-precision concentration sensors are arranged at the main nodes of the absorbent circulation system (such as absorber, regenerator, membrane separator, etc.).

[0043] The concentration of carbon dioxide in the absorbent and the concentration of the active ingredients in the absorbent are monitored in real time using equipment such as an infrared absorption spectrometer (IR) and an electrochemical sensor (such as a pH sensor).

[0044] Data collection: Collect data from each sensor in real time through the data acquisition system (DAS); Data transmission can be done by wired (such as RS485, Ethernet) or wireless (such as Wi-Fi, LoRa).

[0045] Data processing: Preprocess the collected raw data to remove noise and outliers; Use data filtering algorithms (such as Kalman filtering) to improve data accuracy.

[0046] Concentration monitoring: Real-time calculation of the carbon dioxide concentration in the absorbent and the concentration of the active components in the absorbent; Monitor the pH of the absorbent to ensure it is operating in the proper chemical environment.

[0047] Alarm and record: When the absorbent concentration deviates from the set range, the system sends out an alarm signal; All monitoring data and alarm records are stored in the database for subsequent analysis and optimization.

[0048] Control module: The control module automatically adjusts the amount of absorbent added based on the real-time data provided by the online monitoring module to avoid overdosage or underdosage and ensure the stable operation of the system. The specific functions and operations are as follows: Control strategy: Adopt a closed-loop control strategy to dynamically adjust the amount of absorbent added based on real-time monitoring data; The control algorithm can adopt advanced algorithms such as PID control and fuzzy control to ensure the system response speed and stability.

[0049] Actuator selection: Choose high-precision electric valves or pumps as actuators to accurately adjust the flow of absorbent; Ensure the actuator has fast response and reliable control capabilities.

[0050] Control logic: When the absorbent concentration is lower than the set lower limit, the amount of absorbent added will be automatically increased; When the absorbent concentration is higher than the set upper limit, the amount of absorbent added is automatically reduced; The control logic also includes monitoring and adjusting other system parameters (such as temperature and pressure) to ensure the optimized operation of the overall system.

[0051] Adaptive Adjustment: The system can automatically adjust control parameters based on historical data and current operating conditions to achieve adaptive optimization; Continuously optimize control strategies through machine learning algorithms (such as neural networks) to improve the intelligence level of the system.

[0052] Human Machine Interface: Provides a user-friendly interface (HMI), allowing operators to view system status and control parameters in real time; The interface supports remote monitoring and operation, making it convenient for managers to perform remote management and maintenance; Through the coordinated work of the online monitoring module and the control module, the method can realize real-time monitoring and automatic adjustment of the absorbent concentration, ensuring the efficient, stable and low-energy operation of the ship diesel engine exhaust carbon dioxide capture process.

[0053] 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 new type of composite amine absorbent to capture carbon dioxide from ship diesel engine exhaust with low energy consumption analysis method, characterized in that: The following steps are involved: S1. Using a composite amine absorbent containing amino and carboxyl groups to react with carbon dioxide in exhaust gas from a ship diesel engine to generate a reaction product; S2, separate the original composite amine absorbent from the tail gas in S1 through selective membrane separation technology; S3, using low energy consumption thermal regeneration technology, decomposes the reaction products in S1 into carbon dioxide and absorbent.

2. A low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 1, characterized in that: The composite amine absorbent is prepared by mixing ethylenediamine and malonic acid in a molar ratio of 1:1, and additives need to be added during the preparation of the composite amine absorbent.

3. A low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 2, characterized in that: The additives include surfactants, corrosion inhibitors and stabilizers.

4. The low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 1 is characterized in that: The selective membrane separation technology uses a polyimide membrane.

5. The low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 1 is characterized in that: The low energy consumption heat regeneration technology adopts a multi-stage heat exchange module.

6. A low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 5, characterized in that: The multi-stage heat exchange module includes a preheater, an evaporator and a condenser.

7. The low energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 1, characterized in that: Tail gas pretreatment is performed before S1, and the tail gas pretreatment uses wet scrubbing to remove sulfur oxides and nitrogen oxides.

8. The low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 7 is characterized in that: The wet scrubbing uses a sodium hydroxide solution.

9. The low-energy consumption analytical method for capturing carbon dioxide from ship diesel engine exhaust using a novel composite amine absorbent according to claim 1, characterized in that: It also includes an online monitoring module and a control module. The online monitoring module is used to monitor the absorbent concentration. The control module automatically adjusts the amount of absorbent replenishment according to the real-time data of the absorbent concentration.

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