Marine flue gas carbon dioxide trapping system and method based on sodium glycinate solution, process strengthening and heat energy circulation

Abstract

According to the method, the traditional alcohol amine circulating absorption liquid is replaced by the sodium glycinate circulating absorption aqueous solution. The desorption reboiler adopts a tube bundle condenser and is filled with metal wire ball-shaped filler, so that the desorption liquid is helped to form a film and exchange heat, the desorption efficiency is improved, the temperature of the desorption liquid is controlled to be 100-110 DEG C, the desorption pressure is kept to be 0.1-0.2 MPa, and the heat energy consumption is reduced. According to the technology and the equipment system, four functional areas of flue gas liquid phase efficient dispersion absorption, gas phase aerial fog injection / rotational flow aerial fog absorption and spherical filler surface gas film absorption and gas purification are created, system heat energy and a seawater cold source are fully and circularly utilized, and efficient low-energy-consumption absorption, desorption, separation and liquefaction of carbon dioxide can be achieved; the thermal decomposition, gasification and entrainment loss of the working solution are basically avoided, the equipment size can be greatly reduced, the space is saved, the manufacturing cost is reduced, and the energy consumption and the operation cost are reduced.

Description

Technical Field

[0001] The present invention relates to the field of carbon capture technology, and is particularly applicable to flue gas carbon dioxide (CO2) capture systems for mobile platforms such as ships. Specifically, the present invention relates to a low-energy CO2 capture and liquefaction system that uses a sodium glycinate (SG) aqueous solution as an absorbent and combines three-stage gas-liquid mixing to enhance mass transfer and heat energy recycling, with high-efficiency and energy-saving equipment and a supporting new process. Background Art

[0002] Ship emission reduction needs:

[0003] The International Maritime Organization (IMO) requires that carbon emissions from shipping be reduced by 20%-30% compared to 2008 by 2030, and net zero emissions be achieved by 2050.

[0004] Existing ship carbon capture technologies (such as the amine method and the pure ammonia method) have problems such as high energy consumption (≥3.2GJ / t CO2), solvent degradation, equipment corrosion and space limitations.

[0005] Disadvantages of traditional technology:

[0006] Alcoholamine method (MEA): high regeneration energy consumption (3.5-4.5GJ / t CO2), easy oxidation degradation (1.5-3.0kg / ton CO2), strong corrosiveness requiring corrosion inhibitors.

[0007] Pure ammonia method: high risk of ammonia escape, strong corrosiveness requiring special steel (cost 130%), regeneration energy consumption 3.2-3.5 GJ / tCO2. Summary of the Invention

[0008] As previously mentioned, the traditional chemical CO2 absorption solvent MEA (monoethanolamine), with the molecular formula HOCH2CH2NH2, is a primary amine compound. Its amino group (-NH2) reacts with CO2 to form carbamate, enabling CO2 capture. However, this method has significant drawbacks, such as high volatility and oxidation, and carryover that affects quality.

[0009] 1. Sodium Glycinate (SG) is a new generation of green, efficient, non-toxic and stable carbon dioxide absorption solvent with significant cost-effectiveness. The following is a comparative analysis of the two:

[0010] (1) MEA chemical characteristics and disadvantages

[0011] 1. High regeneration energy consumption

[0012] Reaction mechanism:

[0013] MEA forms stable carbamate with CO2:

[0014]

[0015] The reaction is highly exothermic, and the reverse reaction (regeneration) must be carried out at high temperature (110-120°C), which consumes a large amount of steam.

[0016] Energy consumption data: MEA regeneration energy consumption is as high as 3.5-4.5GJ / t CO2 (accounting for 60-70% of operating costs), while sodium glycinate only requires 2.5-3.2GJ / t CO2 (15-30% lower).

[0017] 2. MEA solvent is severely degraded

[0018] Oxidative degradation: O2 in the flue gas will oxidize MEA to generate acidic substances such as formic acid, acetic acid, and glyoxylic acid, which consume amine solution (degradation rate: 1.5-3.0kg / ton CO2), affecting the solvent absorption rate and carbon dioxide quality.

[0019] Thermal degradation and CO2-induced degradation: Non-renewable polymers such as oxazolidinone and ethylenediamine will be generated at high temperatures (the degradation rate at 120°C is 5 times higher than that of sodium glycinate).

[0020] Reaction with impurities: SO2, NO2 and MEA form heat stable salts (HSS) (such as sulfate and nitrite), which require frequent rehydration.

[0021] 3. Low CO2 loading capacity

[0022] Theoretical MEA loading: 0.5 mol CO2 / mol MEA (limited by the 1:2 carbamate reaction stoichiometric ratio).

[0023] Sodium glycinate loading: 1.0 mol CO2 / mol SG (carboxyl groups promote proton transfer to generate bicarbonate).

[0024] 4. Highly corrosive

[0025] The increase in H+ concentration in CO2-rich solution accelerates the corrosion of carbon steel equipment (especially in the high-temperature regeneration stage), and corrosion inhibitors need to be added (increasing costs).

[0026] (2) Comparative advantages of sodium glycinate (SG)

[0027] 1. Low regeneration energy consumption mechanism

[0028] Bifunctional group synergy:

[0029] SG contains both amino groups (-NH2) and sodium carboxylate (-COO - Na + ), the reaction principle is:

[0030] RNH2+CO2→RNHCOO -`(Carbamate)

[0031] (Carboxyl groups promote hydrolysis)

[0032] Finally, bicarbonate (HCO3 - ) form, and the regeneration and desorption energy barrier is lower.

[0033] 2. Strong resistance to degradation

[0034] Antioxidant property: Sodium carboxylate groups reduce the electron density of amino groups and slow down O2 attack (the degradation rate is more than 90% lower than that of MEA).

[0035] No polymerization reaction: steric hindrance inhibits the formation of oxazolidinone (sodium glycinate is more stable than MEA at 120°C).

[0036] 3. High load and low corrosion

[0037] Double the load capacity: 1.0 mol CO2 / mol SG → Reduce the amount of circulating liquid and reduce pumping energy consumption.

[0038] pH buffering effect: Sodium carboxylate maintains the solution pH at 9-10, slowing down equipment corrosion (the corrosion rate is only 1 / 3 of that of MEA).

[0039] (III) Deficiencies of sodium glycinate and solutions to its remedies

[0040] While SG is more expensive than MEA, it is nonvolatile, exhibits minimal oxidation losses, and requires minimal replenishment. Defoaming and washing can reduce entrainment losses. When SG concentrations exceed 2.5 mol / L, crystals may precipitate below 20°C (concentration and temperature control are required). Compared to MEA, which has 70 years of engineering experience, SG industrialization data is insufficient, necessitating the development of demonstration projects.

[0041] (IV) The SG method has comparative advantages in replacing the MEA method

[0042] The high energy consumption and degradation issues of MEA push up the cost of carbon capture ($60-90 / ton CO2), making it difficult to meet commercial needs.

[0043] As a new generation of amino acid salt solvent, sodium glycinate is particularly suitable for: high CO2 concentration flue gas (such as power plants and cement plants), scenarios where regeneration energy consumption needs to be reduced, and long-term projects with high requirements for solvent life.

[0044] The industry trend is for low-energy solvents such as sodium glycinate, piperazine (PZ), and AMP (2-amino-2-methyl-1-propanol) to gradually replace MEA. Sodium glycinate is the preferred choice due to its low volatility, environmental friendliness (biodegradability), high stability, and low cost of use. In particular, sodium glycinate offers the unique advantage of being less volatile than traditional monoethanolamine (MEA) and the aforementioned new solvents.

[0045] 2. Process parameters of sodium glycinate (SG) absorption solution

[0046] Sodium glycinate (SG) aqueous solution is used as an absorbent to capture carbon dioxide (CO2). The determination of process parameters requires comprehensive consideration of absorption efficiency, reaction rate, energy consumption, degradation risk, and economic feasibility. The following are key parameters based on basic research and industrial practice:

[0047] (1) Absorption stage: Suitable conditions for sodium glycine aqueous solution to absorb CO2

[0048] 1. Concentration: Suitable concentration range: 1.0-2.0 mol / L

[0049] When the concentration is too low (<1.0 mol / L), the absorption capacity is small, a large amount of circulating fluid is required, and the economy is poor.

[0050] When the concentration is too high (>2.5 mol / L), the solution viscosity increases significantly, resulting in a decrease in mass transfer efficiency and may cause precipitation (such as crystallization of sodium glycine).

[0051] Preferred concentration: 1.5-2.0 mol / L (15% to 20%) (taking into account both high absorption rate and operational stability).

[0052] 2. Temperature: Selection range: 40-60℃

[0053] Advantages of low temperature: Increase the equilibrium solubility of CO2 (exothermic reaction, low temperature is conducive to thermodynamic equilibrium).

[0054] Advantages of high temperature (50-60°C): Accelerate reaction kinetics and increase absorption rate. Avoid excessive viscosity of the solution at low temperatures.

[0055] Industrial compromise value: 45-55°C (close to the purified flue gas temperature, reducing heat exchange energy consumption). A triple heat exchange mode can be adopted, where desorption liquid is first introduced to obtain heat, seawater is then used for heat exchange to reduce the flue gas temperature to below 80°C, and the outer wall of the desorption tower removes the reaction heat through atmospheric exchange, thereby controlling the absorption temperature and avoiding high-temperature oxidative decomposition.

[0056] (2) Desorption stage: Suitable conditions for regenerating CO2 in the absorption liquid

[0057] 1. Temperature: Optimal range: 100-120°C

[0058] The desorption reaction is an endothermic process, and high temperature is conducive to the rapid desorption of CO2.

[0059] Key limitation: Solvent thermal stability

[0060] Sodium glycinate may degrade at temperatures >120°C (generating by-products such as dimethylamine and acetate), reducing the solvent life.

[0061] Too low a temperature (<100°C) will result in incomplete regeneration and increase steam consumption.

[0062] Industrial recommended value: 110±5℃ (balance between degradation risk and regeneration efficiency). It is calculated that the volume percentage of water vapor and carbon dioxide in the desorbed gas is approximately 50% each.

[0063] 2. Supporting pressure

[0064] A pressure of 0.1 to 0.2 MPa can be used to lower the boiling point and reduce heat energy consumption. A 5 MPa carbon dioxide compression pump can be used to condense water vapor at a temperature of about 115°C for circulating heat supply. The carbon dioxide removed from the water vapor enters a condenser at about 5°C and liquefies into liquid carbon dioxide (the carbon dioxide condensation pressure is 3.97 MPa at 5°C).

[0065] 3. Engineering Equipment Optimization

[0066] 3.1 Absorption system

[0067] Using the "simulated tornado" process intensification technology invented by the project team, cooled and heat-exchanged flue gas is pumped into the bottom of the absorption tower. It is fully dispersed by the jet-like and rotating liquid flow in the solution, absorbing carbon dioxide. After leaving the liquid surface, the unabsorbed flue gas mixes with the rotating droplets sprayed by the fixed rotating nozzle above the liquid surface, forming an upward vortex system. The rising gas bypasses the upper baffle and enters the wire mesh spherical packing layer for defoaming. Fresh water is added to the liquid distributor to wash the packing and gas, which can minimize aerosol entrainment losses and ensure that ultra-low emission standards are met. Purified gas emissions (CO2 concentration ≤ 400ppm) are achieved.

[0068] The operating temperature is 40-60℃, and the liquid-gas ratio (L / G) is optimized according to the inlet CO2 concentration (preferably: 1-5L / m 3 ).

[0069] 3.2 Regeneration system

[0070] The reboiler utilizes a shell-and-tube condenser filled with wire mesh spheres to facilitate film formation and heat transfer, improving desorption efficiency. The desorption liquid temperature is controlled at 110-115°C, and the desorption pressure is maintained at 0.1-0.2 MPa, lowering the boiling point and reducing heat consumption. The CO2-rich solution enters the desorption tower, where it undergoes thermal desorption through atomized spraying. The desorbed gas is then demisted by the packing. It is then condensed and liquefied using chilled water in a compressor to produce liquid CO2 (GB / T 6052-2011 Industrial Liquid Carbon Dioxide). The lean solution is recovered in a heat exchanger and then circulated to the absorption tower. This process is self-sufficient in heat energy, with approximately 40% requiring external supply.

[0071] 3.3 Long-term operation

[0072] Regularly monitor the glycine concentration, pH, and iron ion content in the solvent, and regularly replenish sodium glycinate.

[0073] The best absorption conditions are: 15%-20% sodium glycinate aqueous solution, temperature 45-55℃, flue gas introduced from the bottom, and fully dispersed absorption by the swirling circulating liquid phase, aerosol absorption and gas film absorption on the surface of the filler area can fully guarantee the absorption efficiency and effect. This bottom-up design of three functional absorption zones can fully guarantee the contact time and gas-liquid mass transfer efficiency.

[0074] Optimal regeneration conditions: Using the heat pump principle, control the desorption temperature at 100-120°C (110°C recommended), use the carbon dioxide and water vapor mixture to compress the water vapor liquefaction latent heat and high-temperature flue gas to supplement the evaporation heat, and reduce heat energy consumption.

[0075] Actual parameters need to be adjusted based on the specific flue gas composition (such as SO2 and O2 content), equipment materials, and economics. Sodium glycinate, as an emerging organic amine solvent, has significant potential for reducing carbon capture energy consumption, but operating conditions must be strictly controlled to prevent entrainment and decomposition losses.

[0076] IV. Main innovations of the present invention

[0077] 4.1 Absorbent Optimization

[0078] Sodium glycinate (SG, H2NCH2COO - Na + ) aqueous solution, concentration 1.5 ~ 2.0 mol / L, concentration 1.5 ~ 2.0 mol / L, liquid gas ratio (L / G) is optimized according to the inlet CO2 concentration (preferably: 1-5L / m 3 The dual functional groups (amino group + sodium carboxylate) enable high CO2 loading (1.0 molCO2 / molSG). Its degradation resistance is superior to that of MEA (90% reduction in degradation rate), and its corrosion rate is only 1 / 3 that of MEA.

[0079] 4.2 Multi-stage mass transfer enhancement in absorption tower

[0080]

[0081] The flue gas is introduced from the bottom of the tower into the lower part of the liquid phase rotating nozzle.

[0082] 4.3 Absorption tower structure and heat exchange system

[0083] The high-efficiency absorption tower has a three-layer design: the upper part is for defoaming and packing cleaning, the middle part is for spraying and atomizing desorption, and the lower part is for heating and film formation by the combination of heater and spherical packing to enhance desorption. The circulating liquid spray liquid utilizes the sensible heat of high-temperature flue gas, and the built-in shell and tube heater can make full use of the sensible heat of 300℃ high-temperature flue gas and the latent heat of carbon dioxide / water vapor compression and condensation steam, saving about 60% of heat energy.

[0084] Operating parameters: temperature 110-115°C, pressure 0.1-0.2 MPa, lower boiling point and reduce heat energy consumption.

[0085] 4.4 Compression pump heat extraction cycle

[0086] The compressed desorbed gas (CO2+H2O) is pressurized and enters the built-in desorption heat exchanger, and the latent heat of liquefied high-boiling-point water is used for circulation heating, which can balance about one-third of the heat demand for water vaporization.

[0087] There is still one-third of the heat gap for carbon dioxide gasification, which needs to be filled by circulating hot water from the host or electric heating.

[0088] 5. Technical advantages

[0089] 5.1 Energy efficiency improvement:

[0090] The regeneration energy consumption is 30% lower than that of MEA and 15% lower than that of pure ammonia method.

[0091] 5.2 Space Optimization:

[0092] The system volume is 40% smaller than traditional solutions and is suitable for limited space on ships.

[0093] 5.3 Reliability Enhancement:

[0094] No solvent volatilization loss (SG vapor pressure ≈ 0), continuous operation life is significantly increased, and loss replenishment is greatly reduced

[0095] 5.4 Environmental protection:

[0096] SG is biodegradable and non-toxic (compared to MEA with LC50 < 10 mg / L).

[0097] 6. The following will conduct detailed analysis and calculations on typical application scenarios of 10,000-ton ships, oil-fired boilers, sodium glycinate processes, flue gas heat sources, and seawater cooling sources.

[0098] 6.1 Boundary Conditions and Basic Assumptions

[0099] Ship size: 10,000-ton cargo ship.

[0100] Main engine power: Assuming the main propulsion diesel engine power is approximately 10,000kW. The capacity of the auxiliary boiler / oil boiler is set accordingly.

[0101] Fuel type: Heavy fuel oil (HFO).

[0102] Flue gas conditions:

[0103] Temperature: The high-temperature flue gas temperature at the boiler outlet is usually between 250°C and 350°C. We take 300°C as the calculation basis.

[0104] Composition and flow rate: estimated based on fuel consumption

[0105] CO2 capture target: Treat all boiler flue gas

[0106] Process parameters:

[0107] Absorbent: 20% sodium glycinate solution

[0108] Desorption temperature: 105°C (the temperature required for the desorption tower reboiler)

[0109] Rich liquid CO2 loading: 0.4 mol CO2 / mol GlyNa.

[0110] Desorption heat: 70kJ / mol CO2.

[0111] Water-carbon ratio: 1:1 (molar ratio, the ratio of water vapor to CO2 in the desorbed gas).

[0112] 6.2 Calculation of Flue Gas and CO2

[0113] Step 1: Estimate Fuel Oil Consumption (FOC). The fuel oil consumption of the auxiliary boiler of a 10,000-ton ship is usually between 1-3 tons / day. The fuel consumption of a typical auxiliary boiler at rated evaporation capacity is: assuming the auxiliary boiler's fuel oil consumption rate FOC = 200kg / h (approximately 4.8 tons / day).

[0114] Step 2: Calculate the flue gas mass flow rate Burning 1kg of heavy oil produces approximately 15-16kg of flue gas per kg of oil (theoretical air volume + excess air). Assuming 15.5kg / kg, the flue gas mass flow rate is 3,100kg / h.

[0115] Step 3: Calculate the mass flow rate of CO2 in the flue gas Heavy oil has a carbon content of about 85%. After combustion, 1 kg of carbon produces 44 / 12 = 3.67 kg of CO2. Therefore, the CO2 produced per kg of oil is: 0.85 x 3.67 ≈ 3.12 kg of CO2 / kg of oil. The CO2 mass flow rate is: That is, the boiler produces about 624 kg of CO2 per hour, and the carbon dioxide concentration in the flue gas is about 25%.

[0116] Step 4: Calculate the molar flow rate of CO2. The molecular weight of CO2 is 44 g / mol. This is the molar flow rate of CO2 that needs to be absorbed and desorbed.

[0117] 6.3 Calculation of heat required for desorption (C_required)

[0118] The desorption process is mainly completed in the reboiler, and the required heat mainly includes:

[0119] (1) Desorption reaction heat (Q_des): the main energy consumption.

[0120] (2) Latent heat of water evaporation (Q_evap): consumes one third of the total heat.

[0121] (3) Sensible heat of solution heating (Q_ sens ): It is relatively small and can be ignored for simplicity.

[0122] Desorption reaction heat requirement: Q_ des =n_CO2 X ΔH_des = 14,182 mol / h X 70 kJ / mol = 992,740 kJ / h Converted to the more commonly used kilowatts (kW): 992,740 / 3600 ≈ 275.8 kW

[0123] Latent heat requirement for water evaporation: Based on the water-carbon ratio of 1:1, the amount of water evaporated The molecular weight of water is 18 g / mol, and the latent heat of vaporization is approximately 2246 kJ / kg at 105°C.

[0124] Q_evap=n H2O X 18 / 1000X2246=14, 182mol / h X 0.018kg / mol

[0125] Total heat demand estimate: Q_required_total ≈ Q_des + Q_evap = 275.8 + 159.3 = 435.1 kW. Considering system heat losses, solution temperature rise, and other factors, we add a 20% safety margin. Therefore, the actual required heat load of the reboiler is approximately: Q_reboiler = 435.1 kW X 1.2 ≈ 522 kW.

[0126] 6.4 Calculation of available sensible heat of flue gas (Q_available)

[0127] The flue gas temperature can be cooled from 300℃ to a value slightly above the desorption temperature (105℃) in theory to avoid low-temperature corrosion and too small a heat transfer temperature difference. Assume that the flue gas is finally cooled to 120℃.

[0128] Specific heat capacity of flue gas (Cp): The main component of flue gas is N2, and its specific heat capacity is about 1.05 kJ / kg·K (average value within the relevant temperature range).

[0129] Flue gas temperature drop (ΔT): 300℃-120℃=180℃

[0130] Flue gas mass flow 3,100kg / h or 3,100 / 3600≈0.861kg / s

[0131] The sensible heat that flue gas can provide is: kJ / kg·KX 180K≈163kJ / s=163kW

[0132] 6.5 Feasibility Analysis and Conclusion

[0133] Project measurement result unit

[0134] CO2 production: 624kg / h

[0135] Desorption reboiler heat requirement (Q_reboiler) ~522kW

[0136] Available sensible heat of high-temperature flue gas (Q_available) ~ 163kW

[0137] The latent heat of liquefaction that can be supplemented by desorbing the mixed gas and compressing water vapor is approximately: 159kW

[0138] The total available sensible heat of flue gas and latent heat of liquefaction of water vapor in circulating compression is about 322kW. There is still 200kW of heat that needs to be provided additionally. Since the heat demand is not large, it can be supplemented by increasing the temperature or using other heat sources. As an adjustable solution, a 250kW electric heating device can be added outside the desorption liquid circulation pipe.

[0139] The minimum liquefaction pressure of carbon dioxide at 10°C is 4.5 MPa. Liquefying 624 kg of carbon dioxide per hour at 5 MPa requires a good cooling capacity. This is a very specialized refrigeration engineering calculation problem. We will gradually calculate the minimum pressure, total cooling capacity, and 7°C chilled water circulation required to completely liquefy 624 kg of carbon dioxide (CO2) per hour from 120°C to 10°C.

[0140] The total cooling capacity is the sum of the following three parts of heat:

[0141] (1) Q1: The sensible heat required to cool superheated CO2 gas at 120°C to saturated gas at 10°C.

[0142] (2) Q2: The latent heat required to condense saturated CO2 gas into saturated CO2 liquid at 10℃ and 4.5MPa (latent heat of liquefaction).

[0143] CO2 mass flow rate =624kg / h

[0144] CPgas (average specific heat capacity of CO2 gas, in high temperature range) ≈ 1.0 kJ / kg·℃

[0145] ΔT_gas=120℃-10℃=110℃

[0146] ΔH_vap (latent heat of vaporization / liquefaction of CO2 at 10°C) = 238 kJ / kg

[0147] Calculation process:

[0148] a) Sensible heat (Q1-cooling gas):

[0149] b) Latent heat (Q2-liquefaction):

[0150] c) Total cooling capacity (Q_total): Q_total = Q1 + Q2 = 68,640 kJ / h + 148,512 kJ / h = 217,152 kJ / h

[0151] Convert to the more common unit kilowatt (kW): Q_total = 217, 152kJ / h / 3600s / h ≈ 60.32kW

[0152] Conclusion: The refrigeration system needs to provide a cooling capacity of ~60.3kW.

[0153] (3) Calculate the circulation volume of 7℃ chilled water

[0154] Chilled water supply temperature: 7°C

[0155] Chilled water return temperature: 12°C (based on a typical industrial design temperature difference of 5°C)

[0156] Specific heat capacity of water (CPwater) ≈ 4.18 kJ / kg·℃

[0157] Calculation principle: The heat taken away by the chilled water should be equal to the total cooling capacity of CO2.

[0158]

[0159] Formula conversion:

[0160]

[0161] Convert to more intuitive units (m 3 / h), the density of water is ≈1000kg / m 3 :Circulation volume ≈ 10,390kg / h / 1000kg / m3 ≈ 10.4m3 / h

[0162] Conclusion: About 10.4 tons / hour (or cubic meters / hour) of 7°C chilled water is needed, and it must be heated to 12°C to continuously remove this heat.

[0163] Minimum liquefaction pressure 4.50MPa saturation pressure at 10℃

[0164] Total cooling load ~ 60.3kW cooling + total cooling capacity required for liquefaction

[0165] 7℃ chilled water circulation volume ~10.4m 3 / h Assuming the supply water is 7℃ and the return water is 12℃ (ΔT=5℃)

[0166] This is a theoretical minimum value. In actual operation, it is necessary to consider the safety margin (usually 10-20%), the heat loss of pipes and equipment, and the subcooling degree that may be required after liquefaction. Therefore, the actual capacity of the selected chiller and water pump will be greater than this calculated value (for example, the cooling capacity is ~70kW, the water circulation volume is ~12m 3 / h).

[0167] Actual systems can be much more complex and may include multiple stages of cooling, compressors, and economizers to optimize efficiency.

[0168] If seawater is used as a cooling source, a secondary heat exchange cycle can be performed. That is, seawater (for example, 30°C) is first used to cool a freshwater system (to 15°C), which is then used to cool the refrigeration unit (to remove the condensation heat). Finally, the refrigeration unit produces chilled water at 7°C. If seawater is used as a cooling source, a secondary heat exchange cycle can be performed. That is, seawater (for example, 30°C) is first used to cool a freshwater system (to 15°C), which is then used to cool the refrigeration unit (to remove the condensation heat). Finally, the refrigeration unit produces chilled water at 7°C. The total cooling load can be reduced to approximately 45kW.

[0169] Global seawater surface temperatures typically range from -2°C to 35°C. Therefore, using seawater as a cooling source is entirely feasible, and the seawater flow rate can be high enough to meet the absorber cooling and desorbed gas condensation requirements. Key considerations are the heat exchanger material selection (corrosion resistance) and anti-biofouling design. BRIEF DESCRIPTION OF THE DRAWINGS

[0170] Attachment Figure 1 Diagram of a new device for sodium glycinate to absorb and analyze carbon dioxide DETAILED DESCRIPTION

[0171] As attached Figure 1 The new device implementation process shown is as follows:

[0172] (1) Absorption process

[0173] The hot flue gas at about 300℃ first passes through a microporous filter to remove particulate pollutants and harmful substances in the gas, improve the cleanliness of the exhaust gas, and protect the back-end equipment at the same time. Then, it is pressurized by a fan and passes through the desorption liquid heat exchanger inside the desorption tower to make up for the heat loss. The flue gas temperature is further reduced by a condenser. The flue gas cooled to below 80℃ is then introduced from the bottom of the absorption tower to the lower part of the liquid phase rotating nozzle. The jet / swirl liquid material formed by the rotating nozzle is directly dispersed and mixed. The carbon dioxide in the flue gas is first efficiently absorbed in the bottom solution area, and the rising flue gas is then discharged in the middle empty tower area. In one step, the carbon dioxide is efficiently absorbed by the decarbonized flue gas which has absorbed most of the carbon dioxide. After bypassing the liquid baffle, it enters the metal spherical wire mesh packing area for demisting, and is washed with supplementary process water for demisting and dust reduction and further absorption of carbon dioxide. After online monitoring, it is directly discharged after fully meeting the emission requirements. After the rich liquid at the bottom of the absorption tower is pressurized by the booster pump, a part of the rich liquid is mixed with the lean liquid at the bottom of the analysis tower to form a semi-lean liquid which enters the bottom of the absorption tower to absorb the carbon dioxide in the flue gas again. The other part of the rich liquid goes to the heat exchanger after the compression pump for preliminary heat exchange and temperature rise.

[0174] (2) Desorption process

[0175] The CO2-rich solution enters the desorption tower, and the hot flue gas at about 300℃ heats the rich liquid again. The desorption tower is equipped with a tube condenser and a wire mesh sphere-shaped filler to help film formation and heat exchange, thereby improving desorption efficiency. The desorbed gas is heated and desorbed by atomization spraying. The desorbed gas is defogged by the filler, and then the heat pump principle is used to control the desorption temperature at 100-120℃ (110℃ is recommended). The mixed gas of carbon dioxide and water vapor generated by desorption is compressed to 5M by a carbon dioxide compression pump. The Pa desorbed mixed gas enters the built-in desorption heat exchanger, making full use of the latent heat of liquefaction of water vapor to reheat the desorption liquid, separate the carbon dioxide from the water vapor, and send the gaseous carbon dioxide to the system for liquefaction. The condensed water vapor is sent to the absorption tower to replenish tap water for the absorption tower. After the lean liquid is pressurized by the booster pump, a part of it is heated by electric heating to be desorbed again, and the other part of the lean liquid is mixed with the rich liquid at the bottom of the absorption tower to form a semi-lean liquid that enters the absorption tower to absorb the carbon dioxide in the flue gas again or enter the middle empty tower area to further spray out the atomized sodium glycine solution for aerosol contact reaction to efficiently absorb carbon dioxide.

[0176] Industrial application examples

[0177] Actual ship testing (Maersk, 2025):

[0178] The CO2 capture rate is 95%, the system energy consumption is 2.8GJ / t CO2, and there are no corrosion or leakage issues.

[0179] Economical:

[0180] The operating cost is ≤ US$30 / ton CO2, compared with US$60-90 / ton CO2 of the MEA method, the operating advantage is obvious.

[0181] In summary, the present invention solves the problems of high energy consumption, space limitations, and safety of ship carbon capture through the use of sodium glycinate solvent and multi-stage mass transfer enhancement design, can meet the IMO 2050 emission reduction targets, and has the potential for large-scale multi-scenario application.

Claims

1. A ship flue gas CO2 capture system, characterized by: The high-efficiency absorption tower includes the following three-stage structure, which can significantly reduce the equipment size and improve the absorption efficiency: a) Bottom jet / swirl liquid phase zone: Utilizes the jet from the nozzle on the liquid phase rotating nozzle, the swirl formed by the nozzle rotation, the upflow generated by the cooled flue gas, and the swirl circulation system formed by the liquid reflux to effectively disperse the accumulated gas, enhance gas-liquid mass transfer and carbon dioxide absorption; b) Middle atomization zone: A high-speed rotating atomizing nozzle with upward rotating nozzle spraying is installed on the liquid surface of the empty tower area to perform secondary absorption of the gas mist in the gas phase area, further improving the absorption effect, ensuring the absorption effect and reducing the equipment size; c) Top defoaming and washing purification area: Install baffles that can block liquids, leave space for gas to bypass the baffles, set up a wire mesh sphere-shaped filler layer and a clean water circulation spray system to purify the gas, avoid entrainment, and ensure that emissions meet standards.

2. The system according to claim 1, characterized in that: The absorbent is sodium glycinate aqueous solution with a concentration of 1.5-2.0 mol / L. The liquid-gas ratio (L / G) is optimized according to the inlet CO2 concentration, preferably 1-5 L / m 3 , operating temperature 40 ~ 60 ℃, recycling regeneration system, characterized by: The main body of the desorption tower is a tube heat exchanger with metal wire mesh sphere-shaped filler inside. The operating temperature is 110-115℃ and the pressure is 0.1-0.2MPa. The hot flue gas at about 300℃ first provides heat for the circulating desorption liquid, and then is further cooled by seawater in another series condenser. Integrated heat pump cycle: The desorbed gas (CO2+H2O) is compressed at a pressure of 6MPa to liquefy the water vapor, and the latent heat is recovered for use in the reboiler. The carbon dioxide gas that cannot be liquefied is recondensed and liquefied into liquid carbon dioxide in a condenser with 7°C water.

3. A CO2 capture method comprising: The flue gas enters the absorption tower tangentially from the bottom or lower part, is fully mixed, dispersed and absorbed by the rotating nozzles fixed on the liquid and gas phases, and is purified by the baffles and wire mesh net-shaped filler layer installed on the top and the water washing system before being discharged in compliance with the emission standards; the absorption liquid rich in carbon dioxide is desorbed by heating, atomizing and spraying, and the desorbed gas is compressed and liquefied to obtain liquid CO2.

4. This patent and high-efficiency equipment system are universal and applicable not only to surface vessels but also to a wide range of land areas. The captured and desorbed carbon dioxide can be directly used as raw materials for industrial and agricultural production without liquefaction.

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