Ship CO2 trapping system and method

Abstract

The invention provides a ship CO2 capture system and method, and relates to the technical field of CO2 capture. The ship CO2 trapping system comprises a rotary packed bed for absorption, a centrifugal phase splitter, a rotary packed bed for desorption, a steam condenser and a gas-liquid separator. The rotating packed bed for absorption and the rotating packed bed for desorption are in enhanced interphase contact through a centrifugal field, so that the size of the CO2 absorption / desorption device is reduced, the overall structure of the system is compact, and space-limited scenes such as a marine engine room and the like are perfectly adapted; the absorbent in the rotating packed bed is forcibly dispersed by centrifugal force, so that the liquid phase coalescence phenomenon caused by ship shaking is thoroughly eliminated, a relatively high gas-liquid interface updating rate is maintained, and mass transfer efficiency attenuation caused by phase separation in advance is avoided. According to the centrifugal phase splitter, rapid separation of a native barren solution and a rich solution is achieved through centrifugal acceleration, the phase splitting time is greatly shortened, and the size of the phase splitter is greatly reduced. And a desorption catalyst is introduced in the CO2 desorption stage, so that the desorption temperature is reduced, and the heat energy demand is greatly reduced.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture technology, and more particularly to a ship CO2 capture system and method. Background Technology

[0002] Ocean-going cargo ships rely on fossil fuels for power, and the CO2 emissions from their engine exhaust cause serious pollution to port cities and the marine environment. Ship CO2 exhaust treatment faces multiple challenges, including space constraints, energy consumption limitations, and fluctuating operating conditions.

[0003] Among numerous ship carbon reduction pathways, chemical absorption stands out as the most engineering-feasible technology in the short term due to its mature technology, high CO2 absorption rate, and minimal modification to existing ship structures. Phase-separated absorbents, as novel absorption media, are homogeneous before CO2 absorption. When CO2 reaches a certain load, liquid-liquid phase separation occurs, forming a CO2-rich phase and a CO2-free primary phase. During desorption, only the rich phase needs to be treated. However, the traditional packed towers (static packing) widely used in chemical absorption have limited mass transfer efficiency, resulting in large towers that are difficult to adapt to limited deck space. Furthermore, traditional packed towers have poor adaptability to operating conditions; changes in engine load easily lead to flooding or dry zones within the tower, and ship swaying disrupts the gas-liquid distribution within the tower, reducing mass transfer efficiency. This is particularly unsuitable in the confined space and highly dynamic shipboard environment. In addition, the application of chemical absorption to ships also faces energy consumption challenges: CO2 desorption in rich liquids is energy-intensive (>70% of total carbon capture energy consumption), and the ship's waste heat is far from sufficient to meet its needs, requiring additional fuel oil for heating. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a ship CO2 capture system and method. The system provided by this invention enables efficient mass transfer and stable operation in a dynamic environment for ship CO2 capture, and significantly reduces desorption energy consumption.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a ship CO2 capture system, comprising: A rotating packed bed 3 for absorption, comprising a CO2 tail gas inlet, a liquid inlet for phase-separated absorbent, a purified gas outlet, and a CO2-rich phase-separated absorbent outlet; The centrifugal phase separator 4 has an inlet connected to the outlet of the CO2-rich phase absorbent, and the centrifugal phase separator 4 also includes a rich liquid outlet and a native lean liquid outlet. A desorption rotating packed bed 9 is connected to the rich liquid outlet via a liquid inlet. A rich liquid preheater 8 is installed on the connecting pipeline between the centrifugal phase separator 4 and the desorption rotating packed bed 9. A desorption catalyst is coated on the rotating packing of the desorption rotating packed bed 9. The desorption rotating packed bed 9 also includes a desorbed gas outlet. A steam condenser 11 with its inlet connected to the outlet of the desorbed gas; A gas-liquid separator 12 with its inlet connected to the outlet of the steam condenser 11, the gas-liquid separator 12 also including a CO2 product outlet and a liquid phase outlet.

[0006] Preferably, the ship CO2 capture system further includes a mixer 14 with a liquid inlet connected to the original lean liquid outlet, the mixer 14 also includes a liquid outlet, the liquid outlet of the mixer 14 is connected to the phase-separated absorbent liquid inlet of the rotating packed bed 3 for absorption; an absorbent cooler 16 is provided on the connecting pipeline between the mixer 14 and the rotating packed bed 3 for absorption.

[0007] Preferably, the desorption rotating packed bed 9 further includes a liquid outlet and a steam inlet; the ship CO2 capture system further includes a reboiler 10 with a first liquid inlet connected to the liquid outlet of the desorption rotating packed bed 9, the reboiler 10 further includes a steam outlet and a second liquid inlet, the steam outlet of the reboiler 10 is connected to the steam inlet of the desorption rotating packed bed 9, and the second liquid inlet of the reboiler 10 is connected to the liquid phase outlet of the gas-liquid separator 12.

[0008] Preferably, the reboiler 10 further includes a desorption lean liquid outlet, which is connected to the stirring mixer 14; the connecting pipeline between the reboiler 10 and the stirring mixer 14, as well as the connecting pipeline between the centrifugal phase separator 4 and the rich liquid preheater 8, are all connected to the lean and rich liquid heat exchanger 7.

[0009] This invention provides a method for capturing CO2 from ships, utilizing the ship CO2 capture system described above, comprising the following steps: Ship CO2 exhaust gas and phase-separated absorbent are fed into the rotating packing bed 3 for absorption through the CO2 exhaust gas inlet and the phase-separated absorbent liquid inlet, respectively. Under the condition of rotation, gas-liquid mixing and CO2 absorption are carried out to obtain purified gas and CO2-rich phase-separated absorbent. The purified gas is discharged from the purified gas outlet. The CO2-rich phase-separating absorbent is discharged from the CO2-rich phase-separating absorbent outlet and enters the centrifugal phase separator 4, where it separates into phases under the action of centrifugal force, yielding original lean liquid and rich liquid respectively. The rich liquid is discharged through the rich liquid outlet, heated by the rich liquid preheater 8, and then enters the desorption rotating packed bed 9 through the liquid inlet. Under the centrifugal force generated by the rotation and the action of the desorption catalyst, CO2 is desorbed to obtain the desorbed gas. The desorbed gas is discharged through the desorbed gas outlet and enters the steam condenser 11 for condensation to obtain a gas-liquid mixture. The gas-liquid mixture enters the gas-liquid separator 12 for gas-liquid separation, yielding CO2 product and residual liquid phase respectively; the CO2 product is discharged from the CO2 product outlet of the gas-liquid separator 12, and the residual liquid phase is discharged from the liquid phase outlet.

[0010] Preferably, the original lean liquid enters the stirred mixer 14, is then cooled by the absorbent cooler 16, and is circulated to the absorbent liquid inlet of the rotating packed bed 3 for absorption.

[0011] Preferably, the CO2 desorption also produces desorption residue. The desorption residue and the residual liquid discharged from the gas-liquid separator 12 enter the reboiler 10 through the first liquid inlet and the second liquid inlet, respectively, for secondary heating and desorption to obtain desorption lean liquid and steam. The steam is discharged through the steam outlet of the reboiler 10 and enters the rotating packed bed 9 for desorption to mix with the rich liquid.

[0012] Preferably, after the desorbed lean solution and the rich solution exchange heat through the lean-rich solution heat exchanger 7, they enter the stirring mixer 14 to mix with the original lean solution.

[0013] Preferably, the rotational speed of the rotating packing in the absorption rotating packing bed 3 and the desorption rotating packing bed 9 is independently 100~3000 rpm.

[0014] Preferably, the centrifugal phase separator 4 has a centrifugal speed of 100~3000 rpm.

[0015] This invention provides a ship CO2 capture system, which has the following advantages compared with the prior art: The gas-liquid mass transfer efficiency is doubled: This invention features a rotating packed bed for absorption and a rotating packed bed for desorption. The rotating packed bed for absorption is used for gas-liquid mixing and CO2 absorption of ship CO2 exhaust gas and phase-separating absorbent, while the rotating packed bed for desorption is used for CO2 desorption in rich liquids. The rotating packed beds for absorption and desorption enhance interphase contact through a centrifugal field, enabling a reduction in the size of the CO2 absorption / desorption device and a compact overall system structure, perfectly suited for space-constrained environments such as ship engine rooms.

[0016] Stable operation in dynamic environment: The absorbent in the rotating packed bed is forcibly dispersed by centrifugal force, which completely eliminates the liquid phase aggregation caused by ship swaying, maintains a high gas-liquid interface renewal rate, and avoids the decline in mass transfer efficiency caused by premature phase separation.

[0017] Revolutionary improvement in phase separation efficiency: This invention features a centrifugal phase separator for phase separation to obtain primary lean and rich solutions. Based on the primary density difference of the absorbent, centrifugal acceleration is used to achieve rapid separation of the primary lean and rich solutions, significantly shortening the phase separation time and greatly reducing the volume of the phase separator.

[0018] Significantly reduced desorption energy consumption: This invention employs a phase-separated absorbent system, requiring only CO2 desorption in the rich liquid, directly reducing thermal energy and pumping power consumption. Furthermore, by introducing a desorption catalyst, the activation energy for CO2 desorption is lowered, resulting in a lower desorption operation temperature compared to conventional thermal regeneration, significantly reducing thermal energy requirements. Based on these low-temperature desorption characteristics, the carbon capture system can directly utilize the ship's low-temperature waste heat (engine exhaust or cylinder liner water waste heat) as a desorption heat source under specific conditions, eliminating the need for external steam or electric heating. When higher carbon capture rates are required, renewable energy sources such as solar and wind power can be used for heating, completely eliminating additional fuel consumption in the desorption process. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the ship CO2 capture system used in an embodiment of the present invention. Figure 1 In the middle, 1-engine, 2-denitrification pretreatment device, 3-rotating packed bed for absorption, 4-centrifugal phase separator, 5-original lean liquor pump, 6-rich liquor pump, 7-lean and rich liquor exchanger, 8-rich liquor preheater, 9-rotating packed bed for desorption, 10-reboiler, 11-steam condenser, 12-gas-liquid separator, 13-desorption lean liquor pump, 14-stirring mixer, 15-absorbent transfer pump, 16-absorbent cooler, 17-wind / solar energy utilization device, 18-seawater / air cooling device. Detailed Implementation

[0020] This invention provides a ship CO2 capture system, comprising: A rotating packed bed 3 for absorption, comprising a CO2 tail gas inlet, a liquid inlet for phase-separated absorbent, a purified gas outlet, and a CO2-rich phase-separated absorbent outlet; The centrifugal phase separator 4 has an inlet connected to the outlet of the CO2-rich phase absorbent, and the centrifugal phase separator 4 also includes a rich liquid outlet and a native lean liquid outlet. A desorption rotating packed bed 9 is connected to the rich liquid outlet via a liquid inlet. A rich liquid preheater 8 is installed on the connecting pipeline between the centrifugal phase separator 4 and the desorption rotating packed bed 9. A desorption catalyst is coated on the rotating packing of the desorption rotating packed bed 9. The desorption rotating packed bed 9 also includes a desorbed gas outlet. A steam condenser 11 with its inlet connected to the outlet of the desorbed gas; A gas-liquid separator 12 with its inlet connected to the steam condenser 11, the gas-liquid separator 12 also includes a CO2 product outlet and a liquid phase outlet.

[0021] Unless otherwise specified, all raw materials and equipment involved in this invention are commercially available products well known in the art.

[0022] The ship CO2 capture system provided by this invention includes a rotating packed bed 3 for absorption. In this invention, the rotating packed bed 3 for absorption includes a CO2 tail gas inlet, a phase-separated absorbent liquid inlet, a purified gas outlet, and a CO2-rich phase-separated absorbent (i.e., the phase-separated absorbent after CO2 absorption) outlet. The purified gas outlet can be directly connected to the atmosphere or connected to a water scrubbing tower. In this invention, the rotating packed bed 3 for absorption can be a counter-current, cross-flow, or baffled centrifugal rotating packed bed, characterized by the packing rotating with the shaft. The packing can be structured or loose, and its composition can be filamentous, mesh-like, perforated, porous foam-like, loose spherical, loose triangular, etc. In this invention, the rotating packing bed for absorption is used for gas-liquid mixing and CO2 absorption of ship CO2 exhaust gas and phase-separated absorbent. Under the shearing and stretching action generated by the rotating packing, the phase-separated absorbent is dispersed to form liquid filaments, liquid films and fine droplets. At the same time, ship CO2 exhaust gas is injected into the rotating packing area. In the strong turbulent centrifugal field formed in the rotating packing bed, the gas and liquid phases achieve efficient contact and mixing.

[0023] In this invention, the CO2 exhaust gas inlet is preferably connected to the pretreatment device 2, which is preferably a desulfurization and / or denitrification pretreatment device. This invention does not have any special requirements for the desulfurization and denitrification pretreatment device; any device well known in the art can be used.

[0024] The ship CO2 capture system provided by this invention includes a centrifugal phase separator 4 whose inlet is connected to the outlet of the CO2-rich phase-separating absorbent. In this invention, the centrifugal phase separator 4 also includes a rich liquid outlet and a primary lean liquid outlet. In this invention, the centrifugal phase separator is also called a centrifugal extractor, and a centrifugal extractor with a structure well-known to those skilled in the art can be used. Its main structure includes: a fixed outer shell, a turbine disk, a rotating drum, a light phase weir, a heavy phase weir, a motor, and a drive shaft. The working process is as follows: the mixed liquid (CO2-rich phase-separating absorbent) enters the rotating drum from the bottom and quickly rotates synchronously with the drum under the action of the turbine disk. At this time, the rotation generates centrifugal force, and the denser heavy phase gradually approaches the drum wall during the flow process, while the less dense light phase gradually moves away from the drum wall (closer to the center of the drum). Simultaneously, the light and heavy phases are guided by the light / heavy phase weirs at the top of the drum and flow out from the light phase outlet (i.e., the primary lean liquid outlet) and the heavy phase outlet (i.e., the rich liquid outlet), respectively, completing the separation process. In this invention, the centrifugal phase separator 4 functions as follows: by utilizing the density difference between the rich liquid component and the original lean liquid component in the liquid phase (i.e., the CO2-rich phase absorbent) obtained by CO2 absorption through the rotating packed bed 3, under the action of centrifugal force field, the rich liquid and the original lean liquid are rapidly separated into high CO2 concentration phase (rich liquid) and low CO2 concentration phase (original lean liquid).

[0025] In this invention, the ship CO2 capture system preferably includes a mixer 14 with a liquid inlet connected to the original lean liquid outlet. The mixer 14 preferably includes a liquid outlet, which is preferably connected to the phase-separated absorbent liquid inlet of the rotating packing bed 3 for absorption. An absorbent cooler 16 is preferably provided on the connecting pipeline between the mixer 14 and the rotating packing bed 3 for absorption.

[0026] The ship CO2 capture system provided by this invention includes a desorption rotating packed bed 9 with a liquid inlet connected to the rich liquid outlet. The rotating packing of the desorption rotating packed bed 9 is coated with a desorption catalyst. In this invention, the desorption rotating packed bed 9 also includes a desorbed gas outlet, and preferably includes a liquid outlet and a steam inlet. This invention does not have special requirements for the absorption rotating packed bed 3 and the desorption rotating packed bed 9; any rotating packed bed well-known to those skilled in the art can be used. The main structure includes rotating packing, a motor, a rotating shaft, a fixed outer shell, and a liquid distributor. The desorption rotating packed bed 9 can be a counter-current, cross-flow, or baffled centrifugal rotating packed bed, characterized by the packing rotating with the rotating shaft. The packing can be in the form of a structured or loose packing, and its composition can be filamentous, mesh-like, perforated plate-like, porous foam-like, loose spherical, loose triangular, etc. In this invention, a rich liquid preheater 8 is provided on the connecting pipeline between the centrifugal phase separator 4 and the desorption rotating packed bed 9, for heating the rich liquid flowing out of the absorption rotating packed bed 3.

[0027] In this invention, the rotating packed bed for desorption serves to: promote liquid dispersion, breaking the high-viscosity rich liquid into numerous droplets / liquid films, thereby increasing the surface area for gas-liquid contact. The rotating packed bed provides a highly efficient reaction interface for the catalyst, facilitating full contact between the amine liquid (i.e., the rich liquid) and the catalyst's active sites. Strong turbulence promotes the renewal of the amine liquid on the catalyst surface, preventing the active sites from being covered and reducing coking / contamination on the catalyst surface. Furthermore, the desorption catalyst can lower the activation energy, increase the desorption rate, reduce the CO2 desorption temperature, decrease the heat load on the reboiler, and reduce system power consumption. In the rotating packed bed, the requirement for low-temperature desorption matches the highly efficient mass transfer characteristics of the rotating packed bed, avoiding absorbent degradation caused by high temperatures.

[0028] The ship CO2 capture system provided by the present invention includes a steam condenser 11 whose inlet is connected to the outlet of the desorbed gas.

[0029] The ship CO2 capture system provided by this invention includes a gas-liquid separator 12 whose inlet is connected to the outlet of the steam condenser 11. The gas-liquid separator 12 further includes a CO2 product outlet and a liquid phase outlet. In this invention, the CO2 product outlet can be connected to a CO2 compression, storage, or utilization device.

[0030] In this invention, the ship CO2 capture system preferably includes a reboiler 10 connected to a first liquid inlet and a liquid outlet of the rotating packed bed 9 for desorption. In the rotating packed bed 9 for desorption, CO2 in the rich liquid is not completely desorbed. The reboiler 10 can reheat and desorb the incompletely desorbed liquid in the rotating packed bed for desorption, and the reboiler 10 utilizes an external heat source to ensure the CO2 desorption rate. In this invention, the reboiler 10 preferably includes a steam outlet and a second liquid inlet. The steam outlet of the reboiler 10 is preferably connected to the steam inlet of the rotating packed bed 9 for desorption, and the second liquid inlet of the reboiler 10 is preferably connected to the liquid phase outlet of the gas-liquid separator 12. In this invention, the reboiler 10 preferably includes a desorption lean liquor outlet, which is connected to the stirring mixer 14; the connecting pipeline between the reboiler 10 and the stirring mixer 14, and the connecting pipeline between the centrifugal phase separator 4 and the rich liquor preheater 8, are preferably connected to the lean-rich liquor heat exchanger 7. Specifically, the connecting pipeline between the centrifugal phase separator 4 and the rich liquor preheater 8 is connected to the rich liquor side of the lean-rich liquor heat exchanger 7, and the connecting pipeline between the reboiler 10 and the stirring mixer 14 is connected to the lean liquor side of the lean-rich liquor heat exchanger 7; the function of the lean-rich liquor heat exchanger 7 is to transfer the heat carried by the desorbed lean liquor to the rich liquor to be desorbed, thereby achieving cooling of the desorbed lean liquor and heating of the rich liquor.

[0031] In this invention, a primary lean liquor pump 5 is preferably installed on the connecting pipeline between the centrifugal phase separator 4 and the stirring mixer 14; a rich liquor pump 6 is preferably installed on the connecting pipeline between the centrifugal phase separator 4 and the lean-rich liquor heat exchanger 7; a desorption lean liquor pump 13 is preferably installed on the connecting pipeline between the lean-rich liquor heat exchanger 7 and the reboiler 10; and an absorbent transfer pump 15 is preferably installed on the connecting pipeline between the stirring mixer 14 and the absorbent cooler 16.

[0032] In this invention, it is preferable that engine waste heat utilization pipelines are also provided between the ship engine 1 and the reboiler 10, and between the ship engine 1 and the rich liquid heat exchanger 8.

[0033] The ship CO2 capture system provided by the present invention preferably includes a wind / solar energy utilization device 17 and a seawater / air cooling device 18. The wind / solar energy utilization device 17 is used to heat the reboiler 10 and the rich liquid heat exchanger 8, and the seawater / air cooling device 18 is used to cool the absorbent cooler 16 and the evaporator condenser 11.

[0034] This invention addresses the challenges of space constraints, energy limitations, and significant fluctuations in the volume of gas to be treated, as well as external disturbances, encountered on ships. It develops a CO2 capture system that utilizes a centrifugal field to enhance gas-liquid mass transfer and absorbent phase separation, while incorporating a desorption catalyst to reduce CO2 desorption temperature and energy consumption. This system effectively utilizes waste heat from the ship and overcomes the limitations of traditional packed towers and static phase separation tanks under space constraints and dynamic operating conditions. It provides a compact, efficient, and low-energy solution for ship carbon reduction, achieving high-efficiency mass transfer, rapid phase separation, and low-temperature, low-energy desorption. The system provided by this invention has a compact structure and can operate stably under conditions of space constraints, energy limitations, and fluctuations in engine exhaust flow and the external environment, significantly improving the applicability and economics of ship carbon capture.

[0035] This invention provides a method for capturing CO2 from ships, utilizing the ship CO2 capture system described above, comprising the following steps: Ship CO2 exhaust gas and phase-separated absorbent are fed into the rotating packing bed 3 for absorption through the CO2 exhaust gas inlet and the phase-separated absorbent liquid inlet, respectively. Under the condition of rotation, gas-liquid mixing and CO2 absorption are carried out to obtain purified gas and CO2-rich phase-separated absorbent. The purified gas is discharged from the purified gas outlet. The CO2-rich phase-separating absorbent is discharged from the CO2-rich phase-separating absorbent outlet and enters the centrifugal phase separator 4, where it separates into phases under the action of centrifugal force, yielding original lean liquid and rich liquid respectively. The rich liquid is discharged through the rich liquid outlet, heated by the rich liquid preheater 8, and then enters the desorption rotating packed bed 9 through the liquid inlet. Under the centrifugal force generated by the rotation and the action of the desorption catalyst, CO2 is desorbed to obtain the desorbed gas. The desorbed gas is discharged through the desorbed gas outlet and enters the steam condenser 11 for condensation to obtain a gas-liquid mixture. The gas-liquid mixture enters the gas-liquid separator 12 for gas-liquid separation, yielding CO2 product and residual liquid phase respectively; the CO2 product is discharged from the CO2 product outlet of the gas-liquid separator 12, and the residual liquid phase is discharged from the liquid phase outlet.

[0036] In this invention, ship CO2 exhaust gas and phase-separated absorbent are introduced into a rotating packing bed 3 for absorption through the CO2 exhaust gas inlet and the phase-separated absorbent liquid inlet, respectively. Under rotation, gas-liquid mixing and CO2 absorption are carried out to obtain purified gas and CO2-rich phase-separated absorbent. The purified gas is discharged from the purified gas outlet.

[0037] Before being introduced into the rotating packed bed 3 for absorption, the present invention preferably pre-treats the ship's CO2 exhaust gas through a pretreatment device 2 for desulfurization and / or denitrification. In the present invention, the volume fraction of CO2 in the ship's CO2 exhaust gas is preferably 2-10%.

[0038] In this invention, the phase-separating absorbent preferably includes one or more of N,N-dimethyl-1,3-propanediamine, monoethanolamine, N,N-dimethylethylenediamine, N-(2-aminoethyl)morpholine, 1-(3-aminopropyl)pyrrolidine, 3-diethylaminopropylamine, sulfolane, 1-(2-aminoethyl)pyrrolidine, N,N-dimethyl-1,3-diaminopropane, 3-(dibutylamine)propylamine, N-(3-aminopropyl)diethanolamine, and 1-(2-aminoethyl)piperidine. The phase-separating absorbent can also be prepared into a phase-separating absorbent solution by adding a solvent. This invention does not have special requirements for the solvent; any solvent well-known to those skilled in the art can be used. In the embodiments of this invention, the solvent used is sulfolane and water (volume ratio 6:4), and the concentration of the phase-separating absorbent solution is 2 mol / L. In this invention, the temperatures of the ship CO2 exhaust gas and the phase-separating absorbent are preferably 20~50℃, and the temperature inside the rotating packing bed 3 for absorption is preferably 20~60℃, or can be 40~60℃; the pressures of the ship CO2 exhaust gas, the phase-separating absorbent, and the rotating packing bed 3 for absorption are independently preferably 101~201 kPa, or can be 110~120 kPa; the rotation speed of the rotating packing inside the rotating packing bed 3 for absorption is preferably 100~3000 rpm, or can be 1000~1500 rpm; and the liquid-to-gas ratio (kg / kg) of the rotating packing bed 3 for absorption is preferably 0.2~2.0, or can be 0.3~1.5.

[0039] In this invention, the gas-liquid mixing and CO2 absorption process is as follows: Ship CO2 exhaust gas is introduced into the CO2 exhaust gas inlet of the rotating packed bed 3 for absorption, and the phase-separated absorbent is introduced into its phase-separated absorbent liquid inlet. The phase-separated absorbent is injected from the inner layer of the rotating packing 3 and, under the shearing and stretching action generated by the rotating packing, is dispersed to form liquid filaments, liquid films, and fine droplets. Simultaneously, ship CO2 exhaust gas (which can be co-current, counter-current, or cross-current) is injected into the rotating packing area. In the strongly turbulent centrifugal field formed within the rotating packed bed, the gas and liquid phases achieve efficient contact and mixing. During this process, CO2 is transferred from the gas phase to the liquid phase through selective chemical reactions, completing the absorption process. The purified gas after absorption leaves the rotating packed bed 3 for absorption and is discharged into the atmosphere after treatment by a water scrubbing tower or directly into the atmosphere. The CO2-rich phase-separated absorbent (i.e., the phase-separated absorbent after CO2 absorption) is discharged through the CO2-rich phase-separated absorbent outlet of the rotating packed bed 3 for absorption.

[0040] Existing phase-separating absorbents have many problems in marine applications: (1) premature phase separation may occur during gas-liquid contact, reducing the effective mass transfer area; (2) the phase-separating absorbent, especially the rich phase, has high viscosity, which can easily cause blockage of the packing in the packed tower, reducing the mass transfer efficiency; (3) the static phase separation process is time-consuming, and the required phase separation tank is large in volume and occupies a lot of space; in addition, the swaying of the ship will damage the phase interface, making phase separation more difficult. In contrast, the present invention uses a rotating packed bed for absorption. The phase-separating absorbent is violently sheared and stretched in the strong shear force and turbulence generated by the high-speed rotating packing (100~3000 rpm), forming an ultra-thin liquid film, liquid filaments and droplets, maintaining a homogeneous dispersion state. Centrifugal force forcibly inhibits droplet aggregation, ensuring that the absorbent maintains a high specific surface area homogeneous state during mass transfer, avoiding premature phase separation. Furthermore, the rotating packing (such as wire mesh) moves continuously, avoiding the deposition of high-viscosity liquid on the packing surface. The centrifugal force field drives the liquid to quickly update the interface, preventing local stagnation, effectively stripping high-viscosity liquid, and avoiding the blockage risk of traditional static packing. This invention uses a centrifugal phase separator to replace the settling tank. It utilizes the density difference between the rich liquid and the original lean liquid to achieve rapid phase separation under centrifugal acceleration (which is much higher than gravity). The centrifugal force field stabilizes the phase interface and is not affected by ship swaying, making the volume of the phase separator much smaller than that of a traditional tank.

[0041] After the CO2-rich phase-separating absorbent is formed, it is discharged from the CO2-rich phase-separating absorbent outlet and enters the centrifugal phase separator 4. Under the action of centrifugal force, it separates into the original lean liquid and the rich liquid.

[0042] In this invention, the centrifugal phase separator 4 preferably operates at a speed of 100-3000 rpm, or 2000-3000 rpm. The temperature inside the centrifugal phase separator 4 is preferably 20-40°C. In this embodiment, the temperature of the centrifugal phase separator 4 is room temperature. In this invention, after the phase-separating absorbent absorbs CO2, a high CO2 concentration phase (rich liquid) and a low CO2 concentration phase (original lean liquid) are obtained in the liquid-liquid phase separation (phase separation) within the centrifugal phase separator 4. The rich liquid is subsequently sent to a rotating packed bed 9 for desorption; the original lean liquid does not require desorption; the original lean liquid and the rich liquid are immiscible. Specifically, in this invention, the phase separation is achieved by utilizing the density difference between the rich liquid component and the original lean liquid component in the CO2-rich phase-separating absorbent within the centrifugal phase separator 4, under the action of a centrifugal force field, to achieve rapid stratification and separation of the rich liquid and the original lean liquid.

[0043] After the rich liquid is formed, the present invention discharges the rich liquid through the rich liquid outlet, heats it through the rich liquid preheater 8, and then enters the desorption rotating packed bed 9 through the liquid inlet. Under the centrifugal force generated by the rotation and the action of the desorption catalyst, CO2 is desorbed to obtain the desorbed gas.

[0044] In this invention, the rich liquid is preferably pumped by a rich liquid pump 6 to a lean-rich liquid heat exchanger 7 for heating, and then further heated by a rich liquid preheater 8 before entering the desorption rotating packed bed 9 through the liquid inlet. In this invention, the temperature of the rich liquid preheater is preferably 80-110°C.

[0045] The present invention does not have any special requirements for the desorption catalyst, and any desorption catalyst well known to those skilled in the art can be used, such as metal oxide solid acid catalysts, molecular sieve solid acid catalysts, organometallic frameworks and their derivatives, and nano-carbon materials. In the embodiments of the present invention, the desorption catalyst used is cerium dioxide (CeO2). The desorption catalyst can improve the CO2 removal efficiency and reduce the overall desorption temperature.

[0046] In this invention, the temperature inside the desorption rotating packing bed 9 is preferably 80~130℃, or 90~120℃; the pressure is preferably 101~201kPa, or 110~150kPa; and the rotation speed of the rotating packing is preferably 100~3000 rpm, or 1000~1500 rpm.

[0047] In this invention, the CO2 desorption process is as follows: in the rotating packed bed 9 for desorption, the rich liquid is dispersed into liquid filaments, liquid film and fine droplets by the violent breaking and dispersing action of the rotating packing, and CO2 is separated from the liquid phase to form desorbed gas and desorption residue.

[0048] After the desorbed gas is formed, it is discharged through the desorbed gas outlet and enters the steam condenser 11 for condensation to form a gas-liquid mixture.

[0049] After the gas-liquid mixture is formed, it enters the gas-liquid separator 12 for gas-liquid separation to obtain CO2 product (gas phase) and residual liquid phase respectively.

[0050] In this invention, the main component of the CO2 product is CO2 with a mass fraction >99%, and the main components of the residual liquid phase are condensate and some volatile amines. The CO2 product is discharged from the CO2 product outlet of the gas-liquid separator 12 and can be transported to subsequent compression, storage or utilization processes. The residual liquid phase is discharged from the liquid phase outlet.

[0051] In this invention, the desorption residue generated from CO2 desorption and the residual liquid discharged from the gas-liquid separator 12 preferably enter the reboiler 10 through the first liquid inlet and the second liquid inlet, respectively, for secondary heating and desorption to form a lean desorption solution and steam. The steam is discharged through the steam outlet of the reboiler 10 into the rotating packed bed 9 for desorption, where it mixes with the rich solution. In this invention, the temperature inside the reboiler is preferably 80~130℃ (the temperature inside the reboiler is higher than the temperature inside the rotating packed bed 9 for desorption). In the rotating packed bed 9 for desorption, the CO2 in the rich liquid is not completely desorbed. It flows from the liquid outlet of the rotating packed bed for desorption into the reboiler 10 for secondary heating and desorption. The reboiler 10 uses an external heat source to ensure the CO2 desorption rate. The liquid after being fully desorbed by the reboiler 10 is the desorption lean liquid, which flows out from the liquid outlet of the reboiler. The steam generated by the reboiler 10 enters the rotating packed bed 9 for desorption and mixes and contacts fully with the rich liquid, causing CO2 to be separated from the liquid phase. At this time, the gas after desorption by the rotating packed bed 9 for desorption is a mixture of desorbed CO2 and reboiler 10 steam.

[0052] In this invention, the rich liquid preheater 8 and reboiler 10 can utilize the waste heat of the ship's CO2 exhaust gas to transfer heat to the rich liquid, thereby achieving cooling of the CO2-containing exhaust gas and heating of the rich liquid; they can also utilize electrical energy to heat the rich liquid through the reboiler 10 and / or the rich liquid preheater 8, wherein the electrical energy can be derived from fuel oil power generation, solar power generation, wind power generation, etc.

[0053] After the primary lean solution is formed, it enters the stirred mixer 14, then is cooled by the absorbent cooler 16, and circulated to the absorbent liquid inlet of the rotating packed bed 3 for absorption. In this invention, the primary lean solution is preferably delivered to the stirred mixer 14 by the primary lean solution pump 5, and then delivered to the absorbent cooler 16 by the absorbent delivery pump 15.

[0054] In this invention, the desorbed lean liquid flows out from the liquid outlet of the reboiler 10 and is preferably transported by the desorbed lean liquid pump 13 to the lean-rich liquid heat exchanger 7 for heat exchange (cooled by heat exchange with the rich liquid). Then, it enters the stirring mixer 14 and is fully mixed with the original lean liquid (the original lean liquid is miscible with the desorbed lean liquid) to reform a homogeneous phase-separated absorbent. The reformed phase-separated absorbent is transported by the absorbent transfer pump 15 to the absorbent cooler 16 to be cooled to a suitable absorption temperature. Finally, it is circulated to the phase-separated absorbent liquid inlet of the rotating packed bed 3 for absorption to complete the entire absorption-desorption cycle.

[0055] In this invention, the cooling capacity required by the absorbent cooler 16 and the evaporator condenser 11 (i.e., the cooling capacity required for phase separation absorbent cooling and steam condensation) can be obtained from the seawater / air cooling device 18. The seawater / air cooling device 18 can use seawater as a cold source for cooling, or it can use ambient air for cooling (when sailing in a low-temperature environment, it can use low-temperature ambient air for natural cooling).

[0056] The CO2 capture method for ships provided by this invention utilizes a centrifugal field to enhance gas-liquid mass transfer and absorbent phase separation, and combines a desorption catalyst to reduce energy consumption. It is suitable for CO2 capture scenarios such as ships where space is limited, energy consumption is limited, and the gas to be treated and external disturbances fluctuate greatly.

[0057] Figure 1 This is a schematic diagram of the ship CO2 capture system used in an embodiment of the present invention. It includes a rotating packed bed for absorption 3, a centrifugal phase separator 4, a primary lean liquor pump 5, a rich liquor pump 6, a lean-rich liquor exchanger 7, a rich liquor preheater 8, a rotating packed bed for desorption 9, a reboiler 10, a steam condenser 11, a gas-liquid separator 12, a desorption lean liquor pump 13, a stirring mixer 14, an absorbent transfer pump 15, an absorbent cooler 16, a wind / solar energy utilization device 17, and a seawater / air cooling device 18. Its core consists of three centrifugal devices: the rotating packed bed for absorption 3, the centrifugal phase separator 4, and the rotating packed bed for desorption 9. Figure 1 The system shown includes a CO2 capture process for ships, comprising a CO2 absorption process, an absorbent centrifugal phase separation process, a CO2 desorption process, and a phase-separated absorbent recycling process. The specific processes are as follows: CO2 Absorption Process: CO2-containing ship engine exhaust gas (i.e., CO2 tail gas) is introduced into the gas inlet of the rotating packed bed 3 for absorption, while the phase-separating absorbent is introduced into its liquid inlet. The phase-separating absorbent is injected from the inner layer of the rotating packed bed 3 and dispersed into liquid filaments, liquid films, and fine droplets under the shearing and stretching action generated by the rotating packing. Simultaneously, the CO2 tail gas can be selectively injected into the rotating packed area in a co-current or counter-current manner. In the strong turbulent centrifugal field formed within the rotating packed bed, the gas and liquid phases achieve efficient contact and mixing. During this process, CO2 is transferred from the gas phase to the liquid phase through selective chemical reactions, completing the absorption process. The purified gas after absorption leaves the rotating packed bed 3, is treated by a water scrubbing tower, and is then discharged into the atmosphere. The liquid phase that has absorbed CO2 (rich in CO2 phase-separating absorbent) is discharged through the liquid outlet of the rotating packed bed 3 and enters the centrifugal phase separator 4.

[0058] Centrifugal phase separation process of the absorbent: After absorption, the CO2-rich phase-separated absorbent enters the centrifugal phase separator 4. Utilizing the density difference between the rich liquid component and the original lean liquid component, rapid stratification and separation of the rich liquid and the original lean liquid are achieved under the action of centrifugal force. The separated original lean liquid is pumped to the stirred mixer 14 via a pump (original lean liquid pump); the separated rich liquid is pumped to the subsequent desorption process via a pump (rich liquid pump 6).

[0059] CO2 desorption process: The rich liquid from the centrifugal phase separator 4 flows sequentially through the lean-rich liquid heat exchanger 7 (heated) and the rich liquid preheater 8 (further heated), and then enters the rotating packed bed 9 for desorption through the liquid inlet. Within the rotating packed bed 9, the rich liquid is violently broken and dispersed into liquid filaments, liquid films, and fine droplets by the rotating packing material, and then fully mixes and contacts with the steam generated by the reboiler, promoting the removal of CO2 from the liquid phase. The desorption catalyst coated on the rotating packing material improves the CO2 removal efficiency and lowers the overall desorption temperature. The mixture of desorbed CO2 and reboiler steam 10 is discharged from the gas outlet of the rotating packed bed and enters the steam condenser 11. The condensed gas-liquid mixture is separated in the gas-liquid separator 12: the gas phase (mainly CO2, mass fraction >99%) is transported to subsequent compression, storage, or utilization processes; the liquid phase (condensate and some volatile amines) is returned to the reboiler. In the rotating packed bed 9 for desorption, CO2 in the rich liquid is not completely desorbed and flows from the liquid outlet of the rotating packed bed 9 into the reboiler 10 for secondary heating and desorption. The liquid after sufficient desorption in the reboiler 10 is the desorption lean liquid, which flows out from the liquid outlet of the reboiler 10 and is sequentially transported by the desorption lean liquid pump 13 to the lean-rich liquid heat exchanger 7 (which exchanges heat with the rich liquid and is cooled) and the stirred mixer 14.

[0060] Phase-separated absorbent recirculation: In the stirred mixer 14, the original lean liquid from the centrifugal phase separator 4 is thoroughly mixed with the desorbed lean liquid from the desorption circuit to reform a homogeneous phase-separated absorbent. The reformed phase-separated absorbent is pumped (absorbent transfer pump 15) to the absorbent cooler 16 to adjust the temperature (cool to a suitable absorption temperature), and finally circulated to the liquid inlet of the rotating packed bed for absorption, completing the entire absorption-desorption cycle.

[0061] To further illustrate the present invention, the ship CO2 capture system and method provided by the present invention will be described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0062] Example 1 use Figure 1 The system shown performs CO2 capture from ships, and the process is as follows: (1) System operation steps Engine exhaust gas pretreatment: Before the CO2 absorption step, the engine exhaust gas needs to be pretreated for desulfurization and denitrification to obtain exhaust gas containing CO2 (CO2 volume fraction 2%~10%), and then it is passed to the rotating packed bed for absorption.

[0063] CO2 Absorption: The pretreated CO2-containing tail gas is introduced into the gas inlet of the rotating packed bed 3 for absorption via a gas pipeline. The phase-separating absorbent (solute is DMAPA (N,N-dimethyl-1,3-propanediamine), solvent is sulfolane and water, with a volume ratio of sulfolane to water of 6:4 and a solute molar concentration of 2 mol / L) is pumped into the liquid inlet of the rotating packed bed 3 for absorption, and is forcibly dispersed into liquid filaments, droplets, and liquid films under the action of high-speed rotating packing, making full contact with the pretreated CO2-containing tail gas. In the strongly turbulent and strongly sheared centrifugal field, the CO2 in the gas phase is transferred to the amine liquid through selective chemical reaction, and the purified tail gas is discharged into the atmosphere through the gas outlet.

[0064] Rich liquid phase separation: The liquid phase that has absorbed CO2 (rich CO2 absorbent) is discharged through the liquid outlet and enters the centrifugal phase separator 4. In the centrifugal phase separator 4, the solution is rapidly separated into rich liquid and original lean liquid according to the density difference. The rich liquid is sent to the desorption process, and the original lean liquid is sent to the stirring mixer 14.

[0065] CO2 Desorption: The rich liquor is heated sequentially by the rich-lean liquor heat exchanger 7 and the rich liquor preheater 8 before entering the rotating packed bed 9 for desorption. In the rotating packed bed, the rich liquor is dispersed and comes into countercurrent or cocurrent contact with the steam generated by the reboiler 10, resulting in rapid CO2 desorption. During desorption, the rotating packed bed is loaded with a catalyst (cerium dioxide (CeO2)) to lower the CO2 desorption temperature. The desorption product gas-liquid mixture flows into the steam condenser 11, and then into the gas-liquid separator 12. After condensate separation, the CO2 enters the compression / storage unit.

[0066] Secondary desorption in the reboiler: The incompletely desorbed rich liquor enters the reboiler 10 from the bottom of the rotating packed bed 9 for desorption, and is reheated by an external heat source to ensure the desorption rate. The desorbed lean liquor flowing out of the reboiler 10 is sent to the lean-rich liquor heat exchanger 7, where it exchanges heat with the rich liquor and then flows to the stirred mixer 14.

[0067] Solvent regeneration and circulation: In the stirred mixer 14, the original lean solution and the desorbed lean solution are mixed to form a fresh phase-separated absorbent. After being cooled to 20~40℃ by the absorbent cooler, it is returned to the rotating packed bed 3 for absorption, thus achieving circulation.

[0068] (2) Engineering conditions and parameters CO2 absorption section: tail gas temperature 30~50℃, operating temperature 40~60℃, pressure 110~120kPa, rotation speed of the rotating packing for absorption 1300~1500 rpm, liquid-to-gas ratio 0.8~1.0 (kg / kg).

[0069] Phase separation section: Centrifugal phase separator speed 2800~3000 rpm.

[0070] CO2 desorption section: operating temperature 110~120℃, pressure 110~120kPa, desorption rotary packing speed 1300~1500 rpm.

[0071] Heat source: Prioritize the use of waste heat from the engine (exhaust, cylinder liner water), supplemented by solar heating from the reboiler.

[0072] Cold source: Seawater is preferred for cooling.

[0073] This invention provides a low-energy CO2 capture system and method that utilizes centrifugal fields to enhance mass transfer and absorbent phase separation, desorption catalysts to lower desorption temperatures, and effectively utilizes waste heat from ships. The system has a compact structure and can operate stably under conditions of limited space, energy consumption, and fluctuations in engine exhaust flow and the external environment, significantly improving the applicability and economy of ship carbon capture.

[0074] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A ship CO2 capture system, characterized in that, include: A rotating packed bed (3) for absorption, the rotating packed bed (3) for absorption includes a CO2 tail gas inlet, a phase-separated absorbent liquid inlet, a purified gas outlet and a CO2-rich phase-separated absorbent outlet; The centrifugal phase separator (4) is connected to the outlet of the CO2-rich phase absorbent. The centrifugal phase separator (4) also includes a rich liquid outlet and a native lean liquid outlet. A desorption rotating packed bed (9) is connected to the liquid inlet and the rich liquid outlet. A rich liquid preheater (8) is provided on the connecting pipeline between the centrifugal phase separator (4) and the desorption rotating packed bed (9). A desorption catalyst is coated on the rotating packing of the desorption rotating packed bed (9). The desorption rotating packed bed (9) also includes a desorbed gas outlet. A steam condenser (11) whose inlet is connected to the outlet of the desorbed gas. A gas-liquid separator (12) with its inlet connected to the outlet of the steam condenser (11) is provided, and the gas-liquid separator (12) also includes a CO2 product outlet and a liquid phase outlet.

2. The ship CO2 capture system according to claim 1, characterized in that, The ship CO2 capture system also includes a mixer (14) with a liquid inlet connected to the original lean liquid outlet. The mixer (14) also includes a liquid outlet, and the liquid outlet of the mixer (14) is connected to the phase-separated absorbent liquid inlet of the rotating packing bed (3) for absorption. An absorbent cooler (16) is provided on the connecting pipeline between the mixer (14) and the rotating packing bed (3) for absorption.

3. The ship CO2 capture system according to claim 2, characterized in that, The desorption rotating packing bed (9) further includes a liquid outlet and a steam inlet; the ship CO2 capture system further includes a reboiler (10) with a first liquid inlet connected to the liquid outlet of the desorption rotating packing bed (9), the reboiler (10) further includes a steam outlet and a second liquid inlet, the steam outlet of the reboiler (10) is connected to the steam inlet of the desorption rotating packing bed (9), and the second liquid inlet of the reboiler (10) is connected to the liquid phase outlet of the gas-liquid separator (12).

4. The ship CO2 capture system according to claim 3, characterized in that, The reboiler (10) also includes a desorption lean liquid outlet, which is connected to the stirring mixer (14); the connecting pipeline between the reboiler (10) and the stirring mixer (14) and the connecting pipeline between the centrifugal phase separator (4) and the rich liquid preheater (8) are connected to the lean and rich liquid heat exchanger (7).

5. A method for capturing CO2 from a ship, characterized in that, The ship CO2 capture system according to any one of claims 1 to 4 includes the following steps: Ship CO2 exhaust gas and phase-separated absorbent are fed into the rotating packing bed (3) for absorption through the CO2 exhaust gas inlet and the phase-separated absorbent liquid inlet, respectively. Under the condition of rotation, gas-liquid mixing and CO2 absorption are carried out to obtain purified gas and CO2-rich phase-separated absorbent. The purified gas is discharged from the purified gas outlet. The CO2-rich phase-separating absorbent is discharged from the CO2-rich phase-separating absorbent outlet and enters the centrifugal phase separator (4). Under the action of centrifugal force, it separates into the original lean liquid and the rich liquid respectively. The rich liquid is discharged through the rich liquid outlet, heated by the rich liquid preheater (8), and then enters the desorption rotating packed bed (9) through the liquid inlet. Under the centrifugal force generated by the rotation and the action of the desorption catalyst, CO2 is desorbed to obtain the desorbed gas. The desorbed gas is discharged through the desorbed gas outlet and enters the steam condenser (11) for condensation to obtain a gas-liquid mixture; The gas-liquid mixture enters the gas-liquid separator (12) for gas-liquid separation, and CO2 product and residual liquid phase are obtained respectively; the CO2 product is discharged from the CO2 product outlet of the gas-liquid separator (12), and the residual liquid phase is discharged from the liquid phase outlet.

6. The method for capturing CO2 from ships according to claim 5, characterized in that, The original lean liquid enters the stirred mixer (14), then is cooled by the absorbent cooler (16), and is circulated to the absorbent liquid inlet of the rotating packed bed (3) for absorption.

7. The method for capturing CO2 from ships according to claim 6, characterized in that, The CO2 desorption also produces desorption residue. The desorption residue and the residual liquid discharged from the gas-liquid separator (12) enter the reboiler (10) through the first liquid inlet and the second liquid inlet, respectively, for secondary heating and desorption to obtain desorption lean liquid and steam. The steam is discharged through the steam outlet of the reboiler (10) and enters the desorption rotating packed bed (9) to mix with the rich liquid.

8. The method for capturing CO2 from ships according to claim 7, characterized in that, After the desorbed lean liquid and the rich liquid exchange heat through the lean-rich liquid heat exchanger (7), they enter the stirring mixer (14) and are mixed with the original lean liquid.

9. The method for capturing CO2 from a ship according to claim 5, characterized in that, The rotational speed of the rotating packing in the absorption rotating packing bed (3) and the desorption rotating packing bed (9) is independently 100~3000 rpm.

10. The method for capturing CO2 from a ship according to claim 5, characterized in that, The centrifugal phase separator (4) has a centrifugal speed of 100~3000 rpm.

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