Supergravity carbon capture system and method for interstage cooling and cascade heat recovery ship

Abstract

The invention relates to a supergravity carbon capture system and method for an interstage cooling and cascade heat recovery ship, and relates to the technical field of ship design and tail gas treatment. A tail gas cooling unit; a supergravity absorption unit with interstage cooling; a pregnant solution cascade heat exchange unit; a supergravity desorption unit; a regeneration gas condensation dehydration unit; wherein the pregnant solution cascade heat exchange unit is used for gradually heating a pregnant solution by utilizing waste heat of main engine cylinder sleeve water, waste heat of tail gas, sensible heat of barren liquor and waste heat of steam condensate water, and the regenerated gas condensation dehydration unit comprises two stages of cooling devices which are respectively used for exchanging heat with the pregnant solution and exchanging heat with cooling water, so that multi-stage cooling treatment of regenerated gas is realized. The organic alcohol amine solution is used for absorbing carbon dioxide, interstage cooling is carried out to enhance the absorption efficiency, gradient heat recovery is carried out at the same time, energy consumption is reduced, the energy efficiency level of the system is improved, and the miniaturized and efficient process of the supergravity carbon capture system is achieved.

Description

Technical Field

[0001] This invention relates to the field of ship design and exhaust gas treatment technology, specifically a marine supergravity carbon capture system that applies interstage cooling and cascade heat recovery processes, suitable for the efficient capture and purification of carbon dioxide in exhaust gas. Background Technology

[0002] In the field of carbon capture in ship exhaust, traditional technologies mainly rely on chemical absorption combined with tower equipment. Typical systems use packed towers or plate towers as the core absorption equipment, achieving gas-liquid contact through the packing layers or plate structure within the tower. These tower devices usually require the construction of tall tower structures, which are difficult to install within the limited space of a ship. On the other hand, tower structures designed for limited space tend to have lower carbon dioxide absorption efficiency, affecting the long-term stable operation of the carbon capture system.

[0003] Current research on ship carbon capture technology focuses on two main aspects: energy consumption optimization and system integration. Regarding energy consumption, existing technologies generally use lean and rich liquid heat exchangers to recover some heat energy, but the degree of thermal integration is insufficient, and regeneration energy consumption remains high. In terms of system integration, existing solutions mostly adopt a decentralized layout, lacking synergistic optimization between functional modules, resulting in low overall system efficiency.

[0004] Hypergravity technology significantly enhances the mass transfer process through the strong centrifugal force field generated by rotation, reducing the height of traditional absorption towers from tens of meters to less than 5 meters, while simultaneously achieving an order-of-magnitude improvement in the volumetric mass transfer coefficient. Carbon capture systems based on hypergravity equipment are characterized by miniaturization, making them suitable for applications with limited space on ships. Although hypergravity has certain advantages for marine carbon capture processes, there are still areas for improvement regarding the application of advanced energy-saving processes in hypergravity carbon capture systems, the impact of the cyclic heat release of carbon capture systems on miniaturized equipment processes, and their compatibility with chemical absorption carbon capture processes and marine conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a marine supergravity carbon capture system that utilizes interstage cooling and cascade heat recovery technology. An organic alcohol amine solution is used in the supergravity reactor to absorb carbon dioxide from ship exhaust gas. After heating, the carbon dioxide desorption process begins within the supergravity reactor, achieving a miniaturized process design for the supergravity carbon capture system. Interstage cooling is employed in the absorption process, taking into account the characteristics of the absorption process and equipment, to enhance absorption efficiency and improve the long-term stability of the supergravity carbon capture system. For the heating and desorption process of the CO2-rich solution, considering the ship's environment and the heat flow characteristics within the system, the heat from ship exhaust gas, cylinder liner water, and various high-temperature fluids is fully utilized for cascade heat recovery, improving the thermal energy utilization efficiency of the marine supergravity carbon capture system, reducing energy consumption in the heating and desorption stages, and enhancing the overall energy efficiency of the marine supergravity carbon capture system.

[0006] To achieve the above objectives, the present invention provides a marine supergravity carbon capture system with interstage cooling and cascade heat recovery, comprising:

[0007] The exhaust gas pretreatment unit is used to remove dust, denitrify, and desulfurize ship exhaust gas.

[0008] An exhaust gas cooling unit is connected to the exhaust gas pretreatment unit and is used to cool the treated exhaust gas to a preset temperature.

[0009] A supergravity absorption unit with interstage cooling is connected to the exhaust gas cooling unit and is used to absorb carbon dioxide in the exhaust gas by chemical absorption.

[0010] The rich liquid cascade heat exchange unit is connected to the supergravity absorption unit with interstage cooling, and is used to perform cascade heat exchange on the rich liquid using multiple heat sources.

[0011] The supergravity desorption unit is connected to the rich liquid stepped heat exchange unit and is used to desorb carbon dioxide from the heated rich liquid.

[0012] The regenerated gas condensation and dehydration unit is connected to the ultragravity desorption unit and is used to condense and dehydrate the regenerated gas generated during the desorption process.

[0013] The rich liquid staged heat exchange unit utilizes the waste heat of the main engine cylinder liner water, the waste heat of the exhaust gas, the sensible heat of the lean liquid, and the waste heat of the steam condensate to gradually raise the temperature of the rich liquid. The regenerated gas condensation and dehydration unit includes two-stage cooling devices, which are used for heat exchange with the rich liquid and cooling water, respectively, to achieve multi-stage cooling treatment of the regenerated gas.

[0014] The present invention provides a marine supergravity carbon capture system with interstage cooling and cascade heat recovery, comprising an exhaust gas cooling device, an absorption device, a rich liquid treatment device, a heat recovery network, and an intelligent adjustment module; the exhaust gas cooling device is used to receive ship exhaust gas and gradually reduce the exhaust gas temperature through a water washing process; the absorption device includes a supergravity absorber with an internal interstage cooling structure, which locally cools the middle and lower sections of the supergravity absorber through the cooled rich liquid to maintain a suitable absorption temperature inside the equipment;

[0015] The heat recovery network includes a multi-stage heat exchange device for stepwise heating of the rich liquor, wherein: the waste heat of the cylinder liner water of the ship engine is used to initially heat the rich liquor; the rich liquor is divided into at least two streams, which are further heated by passing through a lean-rich liquor heat exchanger and a combination of a regenerated gas cooler-condensate heat exchanger, respectively, with a flow ratio of 1:1 to 6:1; the mixed rich liquor is then sequentially fed into a desorption centrifuge and a reboiler for CO2 desorption.

[0016] The intelligent adjustment module is used to optimize heat recovery efficiency in real time based on heat source monitoring data, including adjusting the flow ratio of the rich liquid stream and the steam distribution ratio.

[0017] Preferably, the exhaust gas cooling device includes a water washing tower and a washing liquid cooler. The top of the water washing tower is provided with a cooling washing liquid inlet, and the bottom is provided with an outlet for the washing liquid. The outlet washing liquid is cooled by the washing liquid cooler using a cold source and then returned to the top of the water washing tower to form a cycle, ensuring stable cooling of the exhaust gas.

[0018] Preferably, the top of the absorption device is sprayed with lean liquid, which flows sequentially through the lean-rich liquid heat exchanger, the lean liquid cooler, and the lean liquid filtration module to remove impurities and control the lean liquid temperature, while adjusting the absorbent concentration to meet the CO2 absorption requirements; the lean liquid cooler and the lean liquid filtration module can be arranged in two ways: split flow and parallel flow or series connection.

[0019] Preferably, the rich liquor treatment device includes a rich liquor buffer tank, a rich liquor pump, and a rich liquor cooler. The rich liquor after absorbing CO2 flows into the rich liquor buffer tank, and after being pressurized by the rich liquor pump, it is divided into two paths. One path is cooled by the rich liquor cooler using a cold source and then transported to the lower section of the absorption device for interstage cooling. The other path enters the cylinder liner water heat exchanger for preliminary heating.

[0020] Preferably, in the heat recovery network, the lean-rich liquid heat exchanger uses the heat from the high-temperature lean liquid to heat the rich liquid; the regenerated gas cooler uses the heat from the regenerated gas to heat the second stream of rich liquid in the first stage; and the condensate heat exchanger uses the latent heat of the superheated steam coming out of the reboiler to further heat the rich liquid.

[0021] Preferably, the desorption centrifuge and the reboiler work together to achieve the heating and desorption of the rich liquid. The desorbed CO2 is discharged from the bottom of the reboiler. The high-temperature lean liquid is discharged from the bottom of the reboiler and then cooled by passing through the lean-rich liquid heat exchanger and the lean liquid cooler in sequence. The cooled lean liquid is then filtered to remove impurities and purify the solution.

[0022] Preferably, it also includes an absorbent replenishment system for periodically replenishing fresh absorbent to maintain the efficiency of the absorbent; the purified lean liquid, the cooled lean liquid and the newly added absorbent are mixed and then enter the absorption supergravity machine for CO2 absorption, realizing the circulation of absorbent.

[0023] Preferably, the system also includes the regenerated gas cooler and the regenerated gas gas-liquid separator. The main component of the regenerated gas is CO2, which contains water vapor and a small amount of amine liquid. After being processed by the regenerated gas cooler and the regenerated gas gas-liquid separator, a small amount of amine absorbent and water are discharged from the bottom of the regenerated gas gas-liquid separator into a solution buffer tank, and the regenerated CO2 gas is discharged from the top of the regenerated gas gas-liquid separator and enters the CO2 compression liquefaction process.

[0024] The technical solution of the present invention also provides a marine ultragravity carbon capture method with interstage cooling and cascade heat recovery, comprising the following steps:

[0025] The ship's exhaust gas is introduced into the water washing tower to gradually reduce its temperature;

[0026] The cooled exhaust gas is pressurized using a pressurizing fan;

[0027] The pressurized exhaust gas is sent into the absorption supergravity machine and comes into full contact with the lean liquid sprayed from the top, so that the CO2 in the exhaust gas reacts with the absorption liquid to form a rich liquid.

[0028] The CO2-absorbed rich solution flows into the rich solution buffer tank;

[0029] The rich liquid is fed into the rich liquid cooler, and then the cooled rich liquid is transported to the middle and lower section of the absorption supergravity machine to locally cool the inside of the equipment and maintain a suitable absorption temperature.

[0030] Waste heat from the cylinder liner water of the ship's engine is used to preheat another rich liquid stream. The preheated rich liquid is divided into two streams. The first stream passes through the lean-rich liquid heat exchanger, where it is further heated by the heat from the high-temperature lean liquid. The second stream passes through the regenerated gas cooler and the condensate heat exchanger in sequence, where it is heated by the heat from the regenerated gas and the condensate from the steam, respectively. The flow ratio of the first stream to the second stream is adjusted to 1:1 to 6:1, and the two streams are mixed to form a rich liquid stream with a uniform temperature.

[0031] The heated rich liquid is sequentially fed into the desorption centrifuge and the reboiler, and the rich liquid is heated and decomposed to release CO2 by the heat of water vapor.

[0032] The steam supplied in the reboiler is partly generated from the waste heat of the ship's exhaust gas, and the other part is provided by a steam boiler or steam generator. The amount of steam generated from waste heat accounts for 10% to 50% of the total steam.

[0033] The high-temperature regenerated gas is cooled in multiple stages by passing through a rich liquid preheater and a regenerated gas cooler. A small amount of amine absorbent and water are separated by the regenerated gas-liquid separator, and finally regenerated CO2 gas is obtained.

[0034] After the lean liquor is discharged from the bottom of the reboiler, it is cooled sequentially by the lean-rich liquor heat exchanger and the lean liquor cooler. Part of the lean liquor is filtered through the lean liquor filter to remove impurities and purify the solution.

[0035] The present invention has the following beneficial technical effects:

[0036] This invention achieves significant technical and economic benefits through the organic integration of high-gravity technology, interstage cooling, and cascade heat recovery. Its carbon dioxide capture rate reaches over 95%. Simultaneously, the high-gravity carbon capture system, employing multiple energy-saving technologies, significantly reduces energy consumption. Compared to shipborne tower carbon capture systems with the same processing capacity, the system is characterized by miniaturization, lightweight design, and low energy consumption, greatly improving the economic efficiency of ship operations. In this invention, the interstage cooling process effectively controls the temperature rise during absorption, enhancing the system's long-term operational stability and operational flexibility, while the cascade heat recovery design fully utilizes the ship's waste heat, reducing external energy consumption and demonstrating excellent energy-saving and environmental benefits.

[0037] This invention addresses the pain points of traditional marine carbon capture systems, such as bulky equipment, high energy consumption, and installation difficulties within limited ship space, by integrating innovative marine process and carbon capture system design with interstage cooling and cascade heat exchange processes. Simultaneously, it improves the stability, marine adaptability, and energy efficiency of hypergravity carbon capture systems. The system uses a hypergravity device as its core absorption and desorption unit. The strong centrifugal force field generated by high-speed rotation significantly enhances the gas-liquid mass transfer process, tearing the liquid into micro-droplets. This allows for sufficient contact between the fluid and carbon dioxide under highly turbulent and high specific surface area conditions, greatly improving gas-liquid mass transfer efficiency and achieving miniaturization and high efficiency. Furthermore, this invention introduces a unique interstage cooling process: a portion of the rich liquid extracted from the lower part of the absorption hypergravity unit is cooled and then reintroduced to the lower part of the unit. This effectively removes the reaction heat generated during CO2 chemical absorption that is not promptly carried away, preventing a decrease in absorption efficiency due to temperature accumulation inside the unit. This significantly enhances the stability of the absorption process and the overall carbon capture efficiency, representing an innovative design for marine hypergravity carbon capture systems and equipment processes.

[0038] This invention constructs a deeply integrated cascaded heat recovery network tailored to the marine environment, significantly reducing system regeneration energy consumption. For the heating and desorption process of CO2-rich liquid, the system creatively divides into two streams and intelligently adjusts the flow rates (flow ratio range of 1:1-6:1), utilizing multiple low- and medium-grade heat sources for heating in stages: firstly, the rich liquid is preheated using waste heat from the main engine cylinder liner water (approximately 70-85℃); then, the first stream utilizes the sensible heat of the high-temperature lean liquid (90-115℃) after desorption for primary heating in the lean-rich liquid heat exchanger; the second stream is heated sequentially using waste heat from regeneration gas and steam condensate. Finally, the two streams of hot rich liquid at different temperatures are mixed and enter the regeneration supergravity chamber and desorption reboiler. The heat source of the reboiler also adopts the concept of cascade utilization. Part of it is supplied by steam generated from the waste heat of the ship's exhaust gas (accounting for 10%-50%), and the remainder is supplemented by an auxiliary steam generator. This makes full use of the heat energy inside the ship's power system and the supergravity carbon capture system, significantly reducing the consumption of additional energy for the ship. On the basis of the low energy consumption of the supergravity system, it further reduces the system's energy consumption, forming a highly efficient and energy-saving marine supergravity carbon capture system. Attached Figure Description

[0039] Figure 1 A schematic diagram of a marine supergravity carbon capture system module that applies interstage cooling and cascade heat recovery processes.

[0040] Figure 2 A schematic diagram of a marine supergravity carbon capture system that applies interstage cooling and cascade heat recovery processes.

[0041] Figure 3 This is a schematic diagram of a supergravity absorption process with interstage cooling (including a portion of the lean solution cooling and filtration process);

[0042] Figure 4 A schematic diagram of a cascade heat recovery process for heating the rich solution in a carbon capture system;

[0043] Figure 5 This is a schematic diagram of the cylinder liner water heat exchange process used in a carbon capture system.

[0044] Figure 6 This is a schematic diagram of the waste heat utilization and steam system for carbon capture systems.

[0045] Reference numerals: 1. Absorption centrifuge; 2. Regeneration centrifuge; 3. Pressurized blower; 4. Washing tank; 5. Rich liquid buffer tank; 6. Solution buffer tank; 7. Absorbent replenishment system; 8. Washing pump; 9. Rich liquid pump; 10. Lean liquid pump; 11. Absorbent pump; 12. Washing liquid cooler; 13. Waste heat utilization module for tail gas; 14. Rich and lean liquid heat exchanger; 15. Rich liquid preheater; 16. Condensate heat exchanger; 17. Reboiler; 18. Regeneration gas cooler; 19. Lean liquid cooler; 20. Rich liquid cooler; 21. Cylinder liner water heat exchanger; 22. Washing tower; 23. Decarbonized gas-liquid separator; 24. Lean liquid filter; 25. Regeneration gas-liquid separator; 26. Rich liquid transfer tank; 27. Lean liquid filtration module; 28. Rich liquid transfer pump; 29. ​​Rich liquid mixer; 30. Desorption centrifuge. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This invention proposes a novel marine supergravity carbon capture system. By integrating interstage cooling and cascade heat recovery processes, it solves the problems of large equipment size, high energy consumption, and difficult installation in traditional marine carbon capture systems, while significantly improving system stability and energy efficiency. The system utilizes supergravity equipment to enhance the gas-liquid mass transfer process, achieving equipment miniaturization and high efficiency. Interstage cooling effectively removes reaction heat, enhancing absorption efficiency. Simultaneously, a deeply integrated cascade heat recovery network is constructed, intelligently allocating the flow rates of the two flow paths (flow ratio 1:1 to 6:1), utilizing multiple heat sources such as main engine cylinder liner water waste heat, lean liquid sensible heat after desorption, regeneration gas waste heat, and steam condensate waste heat in stages. This significantly reduces system regeneration energy consumption, fully utilizing the ship's own power system and the internal heat energy of the carbon capture system, significantly reducing additional energy consumption, and forming a highly efficient and energy-saving marine carbon capture solution.

[0048] Example 1:

[0049] This embodiment discloses a macroscopic framework for a marine supergravity carbon capture system that applies interstage cooling and cascade heat recovery processes.

[0050] Figure 1 The main modular components of the present invention are shown, including an exhaust gas pretreatment unit, a waste heat utilization unit, an exhaust gas cooling unit, a supergravity absorption unit with interstage cooling, a liquid-rich cascade heat exchange unit, a supergravity desorption unit, and a regenerated gas condensation and dehydration unit.

[0051] The overall process begins with the pretreatment of ship exhaust gas. The exhaust gas pretreatment unit (located near the ship's exhaust emission port) is responsible for treating exhaust gas generated from different marine fuels. Because the composition of exhaust gas from different fuels varies significantly, the unit is equipped with dust removal, denitrification, and desulfurization devices to remove SOx / NOx and particulate matter from the exhaust gas. After treatment, the exhaust gas meets the requirements and enters the subsequent carbon capture system. The exhaust gas pretreatment unit is connected to other modules of the system via pipelines, and its gas pipeline outlet is directly connected to the exhaust gas cooling unit.

[0052] The waste heat recovery unit is connected to the exhaust gas pretreatment unit, and its main function is to utilize the waste heat from the ship's main engine exhaust gas (temperature typically 250–400°C) and the main engine cylinder liner water (temperature range 65°C–85°C). This unit recovers heat from the exhaust gas and cylinder liner water through a heat exchange device to optimize the overall energy efficiency of the system. The heat recovery process in the waste heat recovery unit is completed before the exhaust gas enters the cooling unit, providing partial heat source support for subsequent modules.

[0053] The exhaust gas cooling unit is located immediately after the exhaust gas pretreatment unit. Its core component is a water scrubbing tower, where the ship's exhaust gas, requiring desulfurization, is cooled to below 40°C through water washing to meet the gas-liquid reaction temperature requirements of the subsequent carbon capture process. The water scrubbing tower is equipped with a spray system and a packing layer to enhance gas-liquid contact and improve cooling efficiency. The outlet of the exhaust gas cooling unit is connected via piping to a high-gravity absorption unit with interstage cooling.

[0054] The supergravity absorption unit with interstage cooling utilizes an organic alcohol amine solution to fully absorb carbon dioxide from the exhaust gas through chemical absorption. Under supergravity conditions, gas-liquid mass transfer efficiency is significantly improved. Furthermore, to enhance absorption and reduce system power consumption, this unit employs interstage cooling. See the subsequent unit process description for details.

[0055] The rich liquor cascade heat exchange unit is located downstream of the absorption unit. Its main function is to heat the rich liquor using multiple heat sources within the system. Once the rich liquor is heated to above 100°C, it facilitates the subsequent desorption process. This unit fully utilizes various heat sources, including waste heat from ship exhaust, gas heat, cylinder liner water heat, lean liquor heat, and steam condensate heat. By precisely adjusting the flow rates of each heat source based on their characteristics, it achieves highly efficient cascade heat recovery. After being gradually heated within the heat exchange unit, the rich liquor is transported to the high-gravity desorption unit via pipelines.

[0056] The centrifugal desorption unit is the key module for carbon dioxide desorption in this system. The heated rich liquor first enters the first stage of the regenerating centrifugal turbine for initial desorption. The incompletely desorbed rich liquor is then sent to the reboiler. In the reboiler, steam heating fully releases the carbon dioxide from the rich liquor. The steam required for the reboiler comes from the waste heat boiler and steam generator. The desorbed rich liquor becomes lean liquor and is returned through pipelines to the rich liquor cascade heat exchange unit for heat exchange, thus achieving solution recycling.

[0057] The regeneration gas produced during desorption (mainly carbon dioxide, containing small amounts of water vapor and amine liquid) enters the regeneration gas condensation and dehydration unit. This unit is responsible for multi-stage cooling of the regeneration gas. The high-temperature gas first exchanges heat with the rich liquid, and then with cooling water, completing two-stage cooling. During the cooling process, water vapor and amine liquid condense and are separated into gas and liquid by a gas-liquid separator. The separated gas (mainly high-purity carbon dioxide) is discharged from the top of the separator and enters the subsequent CO2 compression and liquefaction process.

[0058] The entire system is centrally controlled via an electrical control box, which monitors and adjusts the operating parameters of each unit to ensure stable system operation. Furthermore, the modules are connected by a carefully designed piping system, forming a highly efficient and compact marine carbon capture system. The system fully utilizes the ship's own waste heat resources, combining high-gravity technology and cascade heat recovery processes to significantly reduce energy consumption and improve carbon dioxide capture efficiency, making it particularly suitable for ship exhaust gas treatment scenarios.

[0059] Example 2:

[0060] This embodiment, based on Embodiment 1, delves deeper into the specific details of system operation, elaborating on the physical and chemical processes within each module.

[0061] Reference Figure 2 The temperature range of conventional ship exhaust gas is 250–400℃. The exhaust gas first enters the exhaust gas waste heat utilization module 13 for heat recovery. The exhaust gas enters from the bottom of the water washing tower 22, is cooled by water washing, and then exits from the top, ultimately reducing the exhaust gas temperature to below 40℃ to meet the gas-liquid reaction temperature requirements of the subsequent carbon capture and absorption stage. The cooling washing liquid enters from the top of the water washing tower 22 and exits from the bottom. The washed liquid exiting the tower is buffered in the washing tank 4. The washed liquid exiting the tower is pressurized by the water washing pump 8 and returned to the top of the water washing tower 22, forming a cycle. In order to continuously ensure that the exhaust gas is stably cooled to below 40℃ during the water washing cycle, the washed liquid exiting the tower needs to be cooled using a cold source (seawater or cooling water) in the washing liquid cooler 12.

[0062] The exhaust gas is pressurized by the pressurizing fan 3 and then sent into the absorption centrifuge 1. In the absorption centrifuge 1, the exhaust gas reacts fully with the absorbent liquid (organic alcohol amine solution). CO2 in the exhaust gas reacts with the absorbent liquid and enters the absorbent solution to form a rich solution. The exhaust gas components other than CO2 are discharged from the top of the absorption centrifuge 1, passing through the decarbonization gas-liquid separator 23 for gas-liquid separation and ultimately achieving carbon venting. The absorbent liquid enters from the top of the absorption centrifuge 1, absorbs CO2 from the exhaust gas to form a rich solution, and flows into the rich solution buffer tank 5. Simultaneously, the rich solution a is pressurized by the rich solution pump 9 and then cooled to below 35°C using a cold source (seawater or cooling water) through the rich solution cooler 20. The cooled rich solution enters from the middle of the absorption centrifuge 1, performing interstage cooling inside the absorption centrifuge 1, and finally also collects in the rich solution buffer tank 5.

[0063] Rich solution b is pressurized by rich solution pump 9 and enters cylinder liner water heat exchanger 21 for initial heating. The heated rich solution is then divided into two streams for further heating: the first stream passes through lean-rich solution heat exchanger 14, utilizing the heat from the high-temperature lean solution (absorbent after CO2 removal, 90–115°C) to heat the rich solution; the second stream passes sequentially through rich solution preheater 15 and condensate heat exchanger 16, utilizing the heat from regenerated gas and steam condensate to heat the rich solution. The flow ratio of the first and second streams can be intelligently adjusted based on heat source monitoring data, with a ratio of 1:1 to 6:1; the flow ratio of rich solution a to rich solution b is 1:8 to 1:1; the heated rich solutions are then mixed and enter the regeneration supergravity machine 2.

[0064] In the regeneration centrifuge 2, the heated rich liquor decomposes and releases CO2. The rich liquor then enters the reboiler 17, where it is further heated by the heat of steam, promoting CO2 desorption. The desorbed high-temperature CO2 is discharged from the bottom of the reboiler 17 and exits through the top of the regeneration centrifuge 2. After desorption, the rich liquor becomes lean liquor (90–115°C) and is discharged from the bottom of the reboiler 17. The steam supplied to the reboiler 17 is partly generated from the waste heat of the ship's exhaust gas, and partly provided by a steam boiler or steam generator. The amount of steam generated from waste heat accounts for 10%–50% of the total steam volume, depending on the exhaust gas flow rate, temperature, and the energy consumption requirements of the carbon capture system regeneration.

[0065] The regenerated gas is mainly composed of CO2, containing water vapor and a small amount of amine liquid. The high-temperature regenerated gas enters a multi-stage cooling process, passing sequentially through a rich liquid preheater 15 and a regenerated gas cooler 18. The cooling medium in the rich liquid preheater 15 is the rich liquid to be heated, while the cooling medium in the regenerated gas cooler 18 is seawater or cooling water. The cooled regenerated gas passes through a regenerated gas-liquid separator 25, where a small amount of amine absorbent and water are discharged from the bottom of the separator and enter a solution buffer tank 6. The regenerated CO2 gas is discharged from the top of the separator and enters the CO2 compression and liquefaction process. When the liquid level in the solution buffer tank 6 reaches a certain point, it is returned to the regeneration centrifuge 2 via the absorbent pump 11 to maintain the system's water balance.

[0066] The lean solution (absorbent after CO2 removal, 90–115°C) is discharged from the bottom of reboiler 17 and cooled sequentially through a lean-rich solution heat exchanger 14 and a lean solution cooler 19. The cooling medium in the lean-rich solution heat exchanger 14 is the rich solution to be heated, and the cooling medium in the lean solution cooler 19 is seawater or cooling water. The lean solution portion cooled by the lean-rich solution heat exchanger 14 passes through a lean solution filter 24 for impurity removal and solution purification. Based on monitoring the properties of the lean solution and system operation experience, fresh absorbent is periodically replenished through the absorbent replenishment system 7 to maintain the efficiency of the absorbent. The purified lean solution, the cooled lean solution, and the newly added absorbent are mixed and then enter the absorption centrifuge 1 for CO2 absorption, thus achieving absorbent circulation.

[0067] Through the above process, the present invention achieves efficient capture and recovery of CO2 in ship exhaust gas. At the same time, by utilizing interstage cooling and cascade heat recovery processes, energy consumption is significantly reduced and the energy efficiency of the system is improved.

[0068] Example 3:

[0069] This embodiment, based on Embodiment 2, further elaborates on the absorption process with interstage cooling in the supergravity absorption unit.

[0070] Reference Figure 3 In chemical absorption carbon capture systems, the reaction between CO2 and the chemical absorbent is exothermic. Due to the small size of the centrifugal absorption equipment and the tendency for heat to accumulate, the internal temperature gradually rises, deviating from the optimal absorption temperature. At high temperatures, the reaction equilibrium shifts in the reverse direction, reducing the absorbent's CO2 loading capacity and negatively impacting the energy consumption of the carbon capture system. To address this issue, the absorption process is designed as a four-step centrifugal absorption process with interstage cooling, incorporating a lean solution cooling filtration process, as detailed below:

[0071] In step 1: After being cooled by the lean-rich liquid heat exchanger 14, the lean liquid flows sequentially through the lean liquid cooler 19 and the lean liquid filter module 27 to remove fine particulate impurities. To ensure absorption efficiency, the absorbent replenishment system 7 replenishes the absorbent periodically based on its performance changes, ensuring that the temperature of the lean liquid entering the absorption supergravity machine 1 is controlled within the range of 30–50°C, while the concentration of the absorbent is adjusted to meet the requirements for absorbing CO2 from the flue gas. In the lean liquid cooling branch, the lean liquid cooler 19 and the lean liquid filter module 27 can be arranged in two ways: ① the lean liquid is diverted and flows sequentially through the lean liquid cooler 19 and the lean liquid filter module 27 before being paralleled; ② the lean liquid first passes through the lean liquid cooler 19 and then is connected in series to the lean liquid filter module 27.

[0072] Step 2: The washed flue gas enters the absorption centrifuge 1, where it comes into full contact with the lean liquid sprayed from the top. As the carbon capture, absorption, and desorption process continues to cycle, the temperature of the rich liquid and inside the absorption centrifuge 1 gradually increases. At this point, the temperature in the middle and lower sections of the absorption centrifuge 1 will be higher than that in the upper section.

[0073] Step 3: The absorbent liquid, after absorbing CO2, becomes rich liquid and then flows into the rich liquid transfer tank 26. The rich liquid is pressurized by the rich liquid transfer pump 28, and its total flow rate is marked as Q1. During this process, the rich liquid Q12 branch enters the rich liquid cascade heat exchange process flow.

[0074] Step 4: The rich solution Q13 is cooled by the rich solution cooler 20, using seawater or cooling water as the cold source. After cooling, the temperature of the rich solution can be reduced to below 35°C, and then it is transported to the middle and lower sections of the absorption centrifuge 1. This helps to enhance the CO2 absorption process and effectively cools the interior of the absorption centrifuge 1. By reducing the internal temperature of the absorption equipment, the absorption efficiency can be further improved, and the stability of the absorption process can be avoided due to the rise in the internal temperature of the absorption centrifuge 1, thus ensuring the efficient and stable operation of the entire carbon capture system.

[0075] Example 4:

[0076] This embodiment, based on Embodiment 3, further elaborates on the process flow of rich liquid cascade heat exchange.

[0077] Reference Figure 4In the staged heat recovery process for carbon-rich liquid heating, the rich liquid first enters the cylinder liner water waste heat utilization unit. This unit transfers the waste heat from the ship's engine cylinder liner water to the rich liquid through a heat exchanger, achieving primary heating of the rich liquid. This process effectively utilizes waste heat generated during ship operation, reducing the need for additional energy. Subsequently, the rich liquid is divided into two streams for staged heating. The first stream enters the lean-rich liquid heat exchanger, where it exchanges heat with the high-temperature lean liquid (approximately 90–115°C) from the desorption tower, using the heat from the high-temperature lean liquid (the absorbent after CO2 removal) to heat the rich liquid. Because the total circulation volume of lean and rich liquid remains the same, while the rich liquid is split here, the flow rate of the rich liquid in the lean-rich liquid heat exchanger is less than the flow rate of the lean liquid. This design ensures that the heat from the lean liquid is fully transferred to the rich liquid, raising its temperature to 90–110°C. This process utilizes the internal thermal energy circulation of the system, improving heat utilization efficiency. Simultaneously, the second stream passes through a regenerated gas cooler and a condensate heat exchanger. In the regenerated gas cooler, the heat of the regenerated gas is used to heat the second stream of rich liquid in the first stage, raising its temperature to 60-80℃. In the condensate heat exchanger, the rich liquid exchanges heat with the superheated steam coming out of the reboiler, using the latent heat of the steam to further heat the rich liquid, thus achieving efficient conversion and utilization of thermal energy.

[0078] The flow ratio of the first and second streams is controlled between 1:1 and 6:1. Based on heat source monitoring data, the system intelligently adjusts the flow rates of the two streams to ensure optimal heating of the rich liquid. This intelligent adjustment mechanism greatly enhances the system's flexibility and adaptability, enabling it to optimize heat recovery efficiency in real time according to changes in actual operating conditions. The heated rich liquid converges and mixes in the rich liquid mixer, forming a uniformly heated rich liquid flow. The mixed rich liquid then sequentially enters the desorption centrifuge and reboiler for further heating and desorption. In the desorption centrifuge, the rich liquid decomposes upon heating, releasing CO2. This process requires a large amount of heat. The reboiler is responsible for providing the necessary heating and reaction heat for the desorption process. The steam supplied is partly derived from the waste heat of ship exhaust gas, and the other part is supplemented by a steam boiler or steam generator. In the reboiler's steam supply, the amount of steam generated from waste heat accounts for 10% to 50% of the total steam volume, fully demonstrating the system's deep exploitation and efficient utilization of waste heat resources.

[0079] Example 5:

[0080] This embodiment, based on embodiment 4, further elaborates on the cylinder liner water heat exchange process.

[0081] Reference Figure 5The heat exchange process of the cylinder liner water used in the carbon capture system utilizes the waste heat from the ship's main engine cylinder liner water. The outlet temperature of the main engine cylinder liner water is 70–85°C, while the return inlet temperature is 60–75°C, resulting in a temperature difference of approximately 10°C. The heat contained in this temperature difference can be cleverly used for the rich solution heating process of the carbon capture system. By monitoring the temperature and flow rate of the cylinder liner water, the system can intelligently adjust the flow rate of the rich solution, thereby controlling the temperature of the rich solution after heating to 50–65°C. This intelligent adjustment mechanism not only ensures that the rich solution reaches the ideal temperature before entering the next stage of treatment but also maximizes the utilization of waste heat generated during ship operation, reducing additional energy consumption.

[0082] Example 6:

[0083] This embodiment, based on embodiment 4, further elaborates on the source and utilization process of heat energy.

[0084] Reference Figure 6 The waste heat recovery and steam system for the carbon capture system further expands the sources and utilization of heat energy. Ship exhaust gas is used to generate steam through equipment such as the exhaust gas waste heat boiler. This steam is mixed with steam provided by the system's steam generation and supply system and used to heat the rich liquid in the reboiler and supply reaction heat. During this process, CO2 is fully desorbed from the absorbent, achieving the core objective of carbon capture. The steam temperature after heat utilization is approximately 105–115°C. The remaining heat is not wasted but used for secondary heating of the second stream of rich liquid in the solution heat exchanger, further tapping the steam's utilization potential. Finally, the condensate is redirected back to the steam generation facility and the exhaust gas waste heat boiler as a source of water for generating new steam. This recycling design not only reduces the additional energy requirements of the steam generation facility but also effectively utilizes the condensate temperature of 75–100°C, demonstrating the high integration and energy efficiency of the system design. Furthermore, flow sensors can be installed on the two branches respectively and interlocked with the regulating valves on the branches. The control system calculates and distributes the steam generated by the exhaust heat and the amount of steam required under the rated capture rate of the carbon capture system. Then, the flow of steam and condensate in the two branches is controlled by regulating the opening of the regulating valves to ensure the efficiency and stability of the entire heat recovery and utilization process.

[0085] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A marine supergravity carbon capture system with interstage cooling and cascade heat recovery, characterized in that, include: The exhaust gas pretreatment unit is used to remove dust, denitrify, and desulfurize ship exhaust gas. An exhaust gas cooling unit is connected to the exhaust gas pretreatment unit and is used to cool the treated exhaust gas to a preset temperature. A supergravity absorption unit with interstage cooling is connected to the exhaust gas cooling unit and is used to absorb carbon dioxide in the exhaust gas by chemical absorption. The rich liquid cascade heat exchange unit is connected to the supergravity absorption unit with interstage cooling, and is used to perform cascade heat exchange on the rich liquid using multiple heat sources. The supergravity desorption unit is connected to the rich liquid stepped heat exchange unit and is used to desorb carbon dioxide from the heated rich liquid. The regenerated gas condensation and dehydration unit is connected to the ultragravity desorption unit and is used to condense and dehydrate the regenerated gas generated during the desorption process. The rich liquid staged heat exchange unit utilizes the waste heat of the main engine cylinder liner water, the waste heat of the exhaust gas, the sensible heat of the lean liquid, and the waste heat of the steam condensate to gradually raise the temperature of the rich liquid. The regenerated gas condensation and dehydration unit includes two-stage cooling devices, which are used for heat exchange with the rich liquid and cooling water, respectively, to achieve multi-stage cooling treatment of the regenerated gas.

2. A marine supergravity carbon capture system with interstage cooling and cascade heat recovery, characterized in that, It includes an exhaust gas cooling device, an absorption device, a rich liquid treatment device, a heat recovery network, and an intelligent adjustment module; the exhaust gas cooling device is used to receive ship exhaust gas and gradually reduce the exhaust gas temperature through a water washing process; the absorption device includes a supergravity absorber with an internal interstage cooling structure, which locally cools the middle and lower sections of the supergravity absorber through the cooled rich liquid to maintain a suitable absorption temperature inside the equipment. The heat recovery network includes a multi-stage heat exchange device for stepwise heating of the rich liquid, wherein: the waste heat of the cylinder liner water of the ship engine is used to preheat the rich liquid; the rich liquid is divided into at least two streams, which are further heated by a combination of a lean and rich liquid heat exchanger (14) and a regenerated gas cooler (18)-condensate heat exchanger (16), with a flow ratio of 1:1 to 6:

1. The mixed rich liquid enters the desorption supergravity machine (30) and the reboiler (17) in sequence for CO2 desorption; The intelligent adjustment module is used to optimize heat recovery efficiency in real time based on heat source monitoring data, including adjusting the flow ratio of the rich liquid stream and the steam distribution ratio.

3. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 2, characterized in that, The exhaust gas cooling device includes a water washing tower (22) and a washing liquid cooler (12). The water washing tower (22) has a cooling washing liquid inlet at the top and an outlet washing liquid at the bottom. The washing liquid exiting the tower is cooled by the washing liquid cooler (12) using a cold source and then returns to the top of the water washing tower (22) to form a cycle, ensuring stable cooling of the exhaust gas.

4. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 3, characterized in that, The top of the absorption device is sprayed with lean liquid, which flows sequentially through the lean and rich liquid heat exchanger (14), the lean liquid cooler (19) and the lean liquid filtration module (27) to remove impurities and control the lean liquid temperature, while adjusting the concentration of the absorbent to meet the CO2 absorption requirements. The lean liquid cooler (19) and the lean liquid filtration module (27) can be arranged in two ways: split flow and parallel flow or series connection.

5. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 4, characterized in that, The rich liquid treatment device includes a rich liquid buffer tank (5), a rich liquid pump (9), and a rich liquid cooler (20). The rich liquid after absorbing CO2 flows into the rich liquid buffer tank (5), and after being pressurized by the rich liquid pump (9), it is divided into two paths. One path is cooled by the rich liquid cooler (20) using a cold source and then transported to the lower section of the absorption device for interstage cooling. The other path enters the cylinder liner water heat exchanger (21) for preliminary heating.

6. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 5, characterized in that, The lean and rich liquid heat exchanger (14) in the heat recovery network uses the heat of the high-temperature lean liquid to heat the rich liquid; the regeneration gas cooler (18) uses the heat of the regeneration gas to heat the second stream of rich liquid in the first stage; and the condensate heat exchanger (16) uses the latent heat of the superheated steam coming out of the reboiler (17) to further heat the rich liquid.

7. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 6, characterized in that, The desorption centrifuge (30) and the reboiler (17) work together to achieve the heating and desorption of the rich liquid. The desorbed CO2 is discharged from the bottom of the reboiler (17). The high-temperature lean liquid is discharged from the bottom of the reboiler (17) and then cooled by passing through the lean and rich liquid heat exchanger (14) and the lean liquid cooler (19) in sequence. The cooled lean liquid is then filtered through the lean liquid filter (24) to remove impurities and purify the solution.

8. The marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 7, characterized in that, It also includes an absorbent replenishment system (7) for regularly replenishing fresh absorbent to maintain the efficiency of the absorbent; the purified lean liquid, the cooled lean liquid and the newly added absorbent are mixed and then enter the absorption supergravity machine (1) for CO2 absorption to realize the circulation of absorbent.

9. A marine supergravity carbon capture system with interstage cooling and cascade heat recovery according to claim 8, characterized in that, It also includes the regenerated gas cooler (18) and the regenerated gas gas-liquid separator (25). The main component of the regenerated gas is CO2, which contains water vapor and a small amount of amine liquid. After being processed by the regenerated gas cooler (18) and the regenerated gas gas-liquid separator (25), a small amount of amine absorbent and water are discharged from the bottom of the regenerated gas gas-liquid separator (25) and enter the solution buffer tank (6). The regenerated CO2 gas is discharged from the top of the regenerated gas gas-liquid separator (25) and enters the CO2 compression liquefaction process.

10. A method for using the interstage cooling and cascade heat recovery marine supergravity carbon capture system as described in claim 9, characterized in that, Includes the following steps: The ship's exhaust gas is introduced into the water washing tower (22) to gradually reduce the temperature; The cooled exhaust gas is pressurized using a pressurizing fan (3); The pressurized exhaust gas is sent into the absorption supergravity machine (1) and fully contacts the lean liquid sprayed from the top, so that the CO2 in the exhaust gas reacts with the absorption liquid to form a rich liquid. The rich liquid after absorbing CO2 flows into the rich liquid buffer tank (5); The rich liquid is fed into the rich liquid cooler (20), and then the cooled rich liquid is transported to the middle and lower section of the absorption supergravity machine (1) to locally cool the inside of the equipment and maintain a suitable absorption temperature. The waste heat of the cylinder liner water of the ship engine is used to preheat another rich liquid. The preheated rich liquid is divided into two streams. The first stream passes through the lean and rich liquid heat exchanger (14) and is further heated by the heat of the high-temperature lean liquid. The second stream passes through the regeneration gas cooler (18) and the condensate heat exchanger (16) in sequence and is heated by the heat of the regeneration gas and the heat of the steam condensate, respectively. The flow ratio of the first stream and the second stream is adjusted to 1:1 to 6:1 and the two streams are mixed to form a rich liquid stream with a uniform temperature. The heated rich liquid is sequentially fed into the desorption centrifuge (30) and the reboiler (17), and the rich liquid is heated and decomposed to release CO2 by the heat of water vapor. The steam supplied in the reboiler (17) is partly generated from the waste heat of the ship's exhaust gas, and the other part is provided by a steam boiler or steam generator. The amount of steam generated from the waste heat accounts for 10% to 50% of the total steam. The high-temperature regenerated gas is cooled in multiple stages by passing through the rich liquid preheater (15) and the regenerated gas cooler (18). A small amount of amine absorbent and water are separated by the regenerated gas-liquid separator (25), and finally regenerated CO2 gas is obtained. After the lean liquor is discharged from the bottom of the reboiler (17), it is cooled sequentially by the lean and rich liquor heat exchanger (14) and the lean liquor cooler (19). Part of the lean liquor is filtered through the lean liquor filter (24) to remove impurities and purify the solution.

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