High stability carbon dioxide capture system and method based on multi-stage flash process

Abstract

This invention discloses a highly stable carbon dioxide capture system and method based on a multi-stage flash evaporation process, relating to the field of gas separation and emission reduction technology. The system includes a carbon dioxide absorption tower, an intermediate buffer tower, a low-pressure flash evaporation tower, a carbon dioxide desorption tower, a flash tank, a compressor, and a vortex tube, all connected sequentially by pipelines. After CO2 is captured in the absorption tower, the rich liquid enters the intermediate buffer tower. The top gas phase undergoes low-pressure flash evaporation to obtain high-purity CO2 product, while the bottom semi-lean liquid is partially recirculated for absorption and partially regenerated through desorption. The regenerated hot lean liquid undergoes secondary flash evaporation in the flash tank, and its gas phase is compressed and energy-separated by the vortex tube. The hot and cold streams are reused for absorption cooling and desorption heating, respectively. This invention achieves efficient CO2 capture, absorbent stability, and significant energy savings through a unique multi-stage flash evaporation-regeneration process and a flash-compression composite vortex tube high-efficiency energy mode.

Description

Technical Field

[0001] This invention relates to the field of gas separation and emission reduction technology, specifically to a highly stable carbon dioxide capture system and method based on a multi-stage flash evaporation process. Background Technology

[0002] In the global context of addressing climate change, carbon dioxide capture technology has received widespread attention as a key pathway to achieving carbon neutrality. Among these technologies, amine-based chemical absorption has become the most widely used industrial approach due to its high maturity and capture efficiency. However, this approach has long faced two interconnected core challenges: the enormous operating costs caused by excessive energy consumption in the regeneration process, and solvent loss and equipment corrosion caused by the chemical degradation of the absorbent under complex operating conditions. These bottlenecks severely restrict the large-scale commercialization of carbon capture technology.

[0003] To reduce regeneration energy consumption, existing technologies have explored various directions, but often introduce new challenges while solving one problem. For example, patent document CN06120116551130A discloses a carbon dioxide recovery system and method. Its core innovation lies in setting up a complex separation device between the absorption tower and the regeneration tower, designed to separate the insufficiently reacted lean amine solution from the saturated rich amine solution, sending only the latter into the regeneration tower. Theoretically, this design can reduce the processing load of the regeneration tower, thereby reducing energy consumption. However, this solution has significant drawbacks in practical applications: its separation system relies on multiple physical separation units such as a rate-reducing tank, a baffle tank, and a sedimentation tank, and requires a control system equipped with sophisticated concentration sensors, electric valves, and automatic dispensing plates. This not only significantly increases the equipment footprint and initial investment cost, but also puts the reliability and stability of the entire system to the test. The complex fluid paths and mechanical components increase the risk of blockage and failure, resulting in high maintenance costs, and its economic viability in long-term continuous operation is questionable.

[0004] Another technical approach focuses on optimizing the energy utilization rate of the regeneration process itself. For example, the "multi-stage diversion regeneration" process developed by Huaneng Clean Energy Research Institute divides the rich liquid into multiple streams, each fed to a different height within the regeneration tower, attempting to achieve cascaded utilization of heat within the tower. This method has indeed demonstrated good energy-saving potential under laboratory conditions. However, its industrial application faces severe control challenges: to achieve the expected energy-saving effect, extremely precise coordinated control of the flow rate and temperature of three or more rich liquid streams, as well as the temperature distribution in multiple sections within the regeneration tower, is required. This high degree of complexity reduces the system's adaptability to fluctuations in feed conditions (i.e., operational flexibility), placing extremely high demands on the automatic control system. Furthermore, the optimization effect of this technology is closely coupled with the desorption kinetics of specific types of amine absorbents. When changing the absorbent or treating flue gas with different components, the original optimized operating range may no longer be applicable, limiting the technology's universality and potential for widespread adoption.

[0005] Besides energy consumption, the chemical stability of the absorbent is another key weakness. Patent document CN06120112168647A discloses a technical approach different from traditional liquid absorption, employing a "rapid temperature-changing adsorption rotor" loaded with an amine-functionalized solid absorbent to directly capture CO2 from the air. This technology achieves a continuous process and avoids the volatilization problem of liquid absorbents. However, solid amine absorbents face severe oxidative and thermal degradation challenges in real-world environments, especially under conditions containing oxygen and water vapor. During repeated heating and regeneration cycles, amine groups react with oxygen to generate degradation products, leading to an irreversible and continuous decrease in adsorption capacity. This not only shortens the absorbent's lifespan and increases replacement costs, but the degradation products may also cause secondary pollution to the environment. Furthermore, while this process uses water vapor as a regeneration medium and achieves good desorption, it requires a large amount of water vapor to be condensed and separated from the CO2 product gas, a process that consumes significant energy and increases the complexity of the system units.

[0006] In summary, existing carbon dioxide capture technologies often fall into a dilemma of "sacrificing one for the other" in their pursuit of low energy consumption and high stability. They may sacrifice system simplicity and robustness for energy conservation, rely on overly precise and complex controls with narrow applicability to improve efficiency, or face challenges such as insufficient material stability and increased energy consumption in the pursuit of continuous operation. Therefore, there is an urgent need for a technological solution that can fundamentally and synergistically address these problems. Summary of the Invention

[0007] Existing carbon dioxide capture systems suffer from high regeneration energy consumption and increased operating costs due to the easy degradation of absorbents in high-temperature, oxygen-rich environments. This invention aims to provide a highly stable carbon dioxide capture system and method based on a multi-stage flash evaporation process. The system consists of a carbon dioxide absorption tower, an intermediate buffer tower, a low-pressure flash tower, a carbon dioxide desorption tower, a flash tank, a compressor, and a vortex tube, connected sequentially by pipelines. After CO2 is captured in the absorption tower, the rich liquid enters the intermediate buffer tower. The top gas phase undergoes low-pressure flash evaporation to obtain high-purity CO2. The bottom semi-lean liquid is partially recirculated for absorption and partially regenerated through desorption. The regenerated hot lean liquid undergoes secondary flash evaporation in the flash tank, and its gas phase is compressed and separated from the energy in the vortex tube. The hot and cold streams are reused for absorption cooling and desorption heating, respectively. This invention achieves efficient CO2 capture, absorbent stability, and significant energy savings through a unique dual-tower flash evaporation and vortex tube energy recovery process.

[0008] This invention is achieved through the following technical solution: In a first aspect, this application provides a highly stable carbon dioxide capture system based on a multi-stage flash evaporation process, including a carbon dioxide absorption tower. The bottom of the carbon dioxide absorption tower is connected to an intermediate buffer tower via an amine-rich liquid delivery pipe. The bottom of the intermediate buffer tower is connected to a semi-lean liquid delivery pipe. The semi-lean liquid delivery pipe is connected to a first semi-lean liquid delivery pipe and a second semi-lean liquid delivery pipe via a tee connector. The first semi-lean liquid delivery pipe is connected to a carbon dioxide desorption tower, and the second semi-lean liquid delivery pipe is connected to the top of the carbon dioxide absorption tower.

[0009] The intermediate buffer tower is equipped with 3 to 5 sieve plates or packing materials to achieve preliminary gas-liquid separation and buffering, and to serve as a receiver for the reflux liquid at the top of the desorption tower.

[0010] Furthermore, a flash tank is connected to the bottom of the carbon dioxide desorption tower via a hot lean liquid delivery pipeline.

[0011] Furthermore, the bottom of the flash tank is connected to a liquid phase delivery pipe that is connected to the top of the carbon dioxide absorption tower, and a lean liquid pump and a heat exchanger are connected to the liquid phase delivery pipe.

[0012] Furthermore, a steam discharge pipe is connected to the top of the flash tank, a vortex tube is connected to the steam discharge pipe, a hot gas pipe leading to the bottom of the carbon dioxide desorption tower is connected to the vortex tube, and a cold gas pipe leading to the top of the carbon dioxide absorption tower is connected to the vortex tube.

[0013] Furthermore, a compressor is connected to the steam discharge pipe. The compressor has an outlet pressure of 0.8 MPa to 1.2 MPa.

[0014] Furthermore, the carbon dioxide desorption tower is connected to a reboiler.

[0015] Furthermore, a low-pressure flash evaporator is connected to the top of the intermediate buffer tower via a gas pipe.

[0016] The low-pressure flash evaporator operates at a pressure of 0.1 MPa to 0.5 MPa and is used to directly obtain carbon dioxide product gas with a purity of ≥99%.

[0017] Secondly, this application provides a highly stable carbon dioxide capture method based on a multi-stage flash evaporation process, employing the aforementioned carbon dioxide capture system, and the specific capture method is as follows: (1) Absorption process: The raw flue gas enters from the bottom of the carbon dioxide absorption tower and comes into countercurrent contact with the lean amine liquid entering from the top of the tower. The carbon dioxide in the flue gas is absorbed, and the purified fuel gas is discharged from the top of the tower. The carbon dioxide concentration drops to about 0.1%, and the carbon dioxide-enriched amine liquid is discharged from the bottom of the tower and enters the intermediate buffer tower.

[0018] (2) Gas-liquid separation and first-stage flash evaporation: In the intermediate buffer tower, the amine-rich liquid undergoes preliminary gas-liquid separation; the gas phase rich in carbon dioxide at the top of the tower enters the low-pressure flash evaporator for flash evaporation, and high-purity carbon dioxide gas product is obtained at the top of the tower, while the liquid phase at the bottom of the tower returns to the intermediate buffer tower; the semi-lean liquid at the bottom of the tower is divided into two streams.

[0019] (3) Desorption and regeneration: The semi-lean liquid coming out from the bottom of the intermediate buffer tower is first returned to the carbon dioxide absorption tower as absorbent; the second liquid is preheated by the heat exchanger and enters the upper part of the carbon dioxide desorption tower; inside the desorption tower, the solution is heated by the reboiler, CO2 is desorbed and returned from the top of the tower to the lower part of the intermediate buffer tower; the regenerated hot lean liquid is discharged from the bottom of the desorption tower.

[0020] (4) Secondary flash evaporation and energy recovery: The hot lean liquid obtained in step (3) enters the flash tank for further flash evaporation. The liquid phase at the bottom of the flash tank is cooled by the heat exchanger and returned to the top of the carbon dioxide absorption tower as supplementary lean liquid. The gas phase flashed out from the top of the flash tank is pressurized by the compressor and then enters the vortex tube for energy separation.

[0021] (5) Comprehensive energy utilization: The high-temperature and high-pressure gas flowing out from the hot end outlet of the vortex tube returns to the bottom of the carbon dioxide desorption tower to provide part of the regeneration heat energy; the low-temperature gas flowing out from the cold end outlet of the vortex tube returns to the top of the carbon dioxide absorption tower for cooling of the absorption process.

[0022] Furthermore, the pressure inside the carbon dioxide absorption tower is controlled at 0.1MPa~2.5MPa, and the temperature is controlled at 40℃~60℃.

[0023] Furthermore, the pressure inside the carbon dioxide desorption tower is controlled at 0.15MPa~0.25MPa, and the temperature is controlled at 90℃~130℃.

[0024] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The system of the present invention includes a multi-stage flash regeneration process and a flash compression composite vortex tube high-efficiency energy mode, which solves the problems of high energy consumption and easy degradation of absorbent in traditional carbon dioxide capture systems.

[0025] (2) The present invention constructs a complete system including an absorption unit, a regeneration unit and an energy recovery unit. The absorption unit achieves efficient capture of carbon dioxide through an absorption tower. The regeneration unit significantly reduces energy consumption by combining flash evaporation and desorption. The energy recovery unit realizes the recycling of energy within the system through heat exchange between lean and rich liquids and energy separation by vortex tubes. Ultimately, the carbon dioxide capture process achieves high efficiency, energy saving and long-term stable operation.

[0026] (3) The absorption unit of the present invention consists of a carbon dioxide absorption tower and an intermediate buffer tower. The high-efficiency packed tower structure ensures that the absorbent and flue gas are in full contact. The regeneration unit includes a low-pressure flash tower and a carbon dioxide desorption tower. By connecting a reboiler with zoned temperature control, the heat of the desorption process is utilized in stages. The energy recovery unit consists of a lean and rich liquid heat exchanger, a compressor and a vortex tube energy separation device, forming a multi-level heat recovery network.

[0027] (4) The carbon dioxide capture system of the present invention adopts an absorption-flash evaporation-regeneration-flash evaporation structure, wherein the low-pressure flash evaporation tower directly produces high-purity carbon dioxide products, significantly reducing the regeneration load of the desorption tower. The system achieves gas-liquid separation and material distribution by setting an intermediate buffer tower. The gas phase at the top of the tower enters the low-pressure flash evaporation tower to obtain carbon dioxide products, and the semi-lean liquid at the bottom of the tower is divided into two paths. One path returns to the absorption tower for recycling, and the other path enters the regeneration system. This multi-stage separation design greatly improves the system's operational flexibility and energy utilization efficiency.

[0028] (5) The energy recovery unit configured in the system of the present invention, wherein the vortex tube effectively separates the energy of the flash steam into two streams of hot and cold fluids, which are respectively used for heating at the bottom of the desorption tower and cooling at the top of the absorption tower, forming an energy recycling mode inside the system. The lean and rich liquid heat exchanger realizes the heat exchange between the cold and hot streams, further reducing the external energy input of the system. This multi-level energy recovery design reduces the system energy consumption by 25% to 35% compared with the traditional method.

[0029] (6) Compared with the traditional carbon capture system, the carbon dioxide capture system of the present invention achieves a dual reduction in system energy consumption and operating cost through the synergistic effect of flash evaporation structure and energy recovery network. Compared with the traditional single-stage regeneration, the flash evaporation structure in the present invention reduces regeneration energy consumption by more than 30%; compared with the traditional simple heat exchange, the energy recovery network improves the system thermal efficiency by more than 25%; compared with the traditional amine carbon capture system, the operating cost is reduced by 35%~40%, realizing the unity of high efficiency, stability and economy in the carbon capture process.

[0030] (7) The carbon dioxide capture system of the present invention is applicable to various industrial applications such as coal-fired power plants, gas-fired power plants, steel plants, and cement plants. The system operates stably, is precisely controlled, and has significant energy-saving effects. It can handle flue gas of different concentrations and flow rates, achieve optimal operating conditions, and has strong adaptability. It can be used for the treatment of various carbon emission sources. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of a highly stable carbon dioxide capture system based on a multi-stage flash evaporation process according to the present invention.

[0033] Figure label: 01-Carbon dioxide absorption tower, 02-Rich amine liquid conveying pipe, 03-Intermediate buffer tower, 04-Semi-lean liquid conveying pipe, 05-Second semi-lean liquid conveying pipe, 06-First semi-lean liquid conveying pipe, 07-Flash tank, 08-Hot lean liquid conveying pipe, 09-Liquid phase conveying pipe, 10-Heat exchanger, 11-Lean liquid pump, 12-Steam discharge pipe, 13-Compressor, 14-Vortex tube, 15-Cold flow tube, 16-Hot flow gas tube, 17-Carbon dioxide desorption tower, 18-Reboiler, 19-Low-pressure flash tower. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The illustrative embodiments and descriptions of this invention are only used to explain this invention and are not intended to limit this invention.

[0035] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that these specific details are not necessary to practice the invention. In other embodiments, well-known materials or methods have not been specifically described in order to avoid obscuring the invention.

[0036] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "an embodiment," "an example," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described herein, as well as the features of those different embodiments or examples.

[0037] In this application, unless otherwise stated, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "middle," "vertical," "horizontal," "lateral," and "longitudinal," etc., generally refer to the directions shown in the drawings or describe the relative positional relationships of the components in a vertical, perpendicular, or gravitational direction. They are used only to describe the relative positional relationships between the components or constituent parts and do not specifically limit the specific installation orientation of each component or constituent part. "Inner" and "outer" generally refer to the interior or exterior of the cavity relative to the chamber or the radial interior or exterior relative to the center of a circle. The above directional terms are defined for ease of understanding of the present invention and therefore do not constitute a limitation on the scope of protection of the present invention.

[0038] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0039] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0040] Furthermore, the structures, proportions, sizes, etc., drawn in the accompanying drawings of this application are only used to complement the content disclosed in the specification for those skilled in the art to understand and read, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modification to the structure, change in the proportional relationship, or adjustment of the size, without affecting the effects and purposes that this application can produce, should still fall within the scope of the technical content disclosed in this application. Example

[0041] like Figure 1 As shown, this embodiment provides a highly stable carbon dioxide capture system based on a multi-stage flash evaporation process, including a carbon dioxide absorption tower 01. The bottom of the carbon dioxide absorption tower 01 is connected to an intermediate buffer tower 03 via an amine-rich liquid delivery pipe 02. The bottom of the intermediate buffer tower 03 is connected to a semi-lean liquid delivery pipe 04. The semi-lean liquid delivery pipe 04 is connected to a first semi-lean liquid delivery pipe 06 and a second semi-lean liquid delivery pipe 05 via a tee connector. The first semi-lean liquid delivery pipe 06 is connected to a carbon dioxide desorption tower 17, and the second semi-lean liquid delivery pipe 05 is connected to the top of the carbon dioxide absorption tower 01.

[0042] The intermediate buffer tower 03 is equipped with 3 to 5 sieve plates or packing materials to achieve preliminary separation and buffering of gas and liquid, and to serve as a receiver for the reflux liquid at the top of the desorption tower.

[0043] Specifically, a flash tank 07 is connected to the bottom of the carbon dioxide desorption tower 17 via a hot lean solution delivery pipe 08. A liquid phase delivery pipe 09, which connects to the top of the carbon dioxide absorption tower 01, is connected to the bottom of the flash tank 07. A lean solution pump 11 and a heat exchanger 10 are connected to the liquid phase delivery pipe 09. A steam discharge pipe 12 is connected to the top of the flash tank 07. A vortex tube 14 and a compressor 13 are connected to the steam discharge pipe 12. The vortex tube 14 is connected to a hot gas pipe 16 leading to the bottom of the carbon dioxide desorption tower 17 and a cold gas pipe 15 leading to the top of the carbon dioxide absorption tower 01. The outlet pressure of the compressor 13 is 0.8 MPa to 1.2 MPa.

[0044] The hot lean liquid discharged from the bottom of the carbon dioxide desorption tower 17 enters the flash tank 07 for secondary flash evaporation. The liquid phase at the bottom of the flash tank 07 is cooled by the lean and rich liquid heat exchanger 10 and then returns to the top of the carbon dioxide absorption tower 01. The flash vapor generated at the top of the flash tank 07 is pressurized by the compressor 13 and then enters the vortex tube 14. The vortex tube 14 separates the flash vapor into hot and cold fluids. The hot end fluid returns to the bottom of the carbon dioxide desorption tower 17 to provide an auxiliary heat source, while the cold end fluid is used to cool the top of the carbon dioxide absorption tower 01.

[0045] Specifically, the carbon dioxide desorption tower 17 is connected to a reboiler 18. The semi-lean liquor from the intermediate buffer tower 03 is preheated by the lean-rich liquor heat exchanger 10 and then enters the upper part of the carbon dioxide desorption tower 17. Under the action of the heat energy provided by the reboiler 18, carbon dioxide is desorbed from the amine liquor, and the fully regenerated lean amine liquor is discharged from the bottom of the tower into the flash tank 07.

[0046] Specifically, the top of the intermediate buffer tower 03 is connected to a low-pressure flash tower 19 via a gas pipe. The low-pressure flash tower 19 operates at a pressure of 0.1MPa to 0.5MPa and is used to directly obtain carbon dioxide product gas with a purity of ≥99%.

[0047] The specific method for using the above-mentioned carbon dioxide capture system is as follows: (1) Absorption process: The raw flue gas enters from the bottom of the carbon dioxide absorption tower 01 and comes into countercurrent contact with the lean amine liquid entering from the top of the tower. The carbon dioxide in the flue gas is absorbed, and the purified fuel gas is discharged from the top of the tower. The carbon dioxide concentration drops to about 0.1%, and the carbon dioxide-enriched amine liquid is discharged from the bottom of the tower and enters the intermediate buffer tower 03.

[0048] (2) Gas-liquid separation and first-stage flash evaporation: In the intermediate buffer tower 03, the amine-rich liquid undergoes preliminary gas-liquid separation; the gas phase rich in carbon dioxide at the top of the tower enters the low-pressure flash tower 19 for flash evaporation, and a high-purity carbon dioxide gas product is obtained at the top of the tower, while the liquid phase at the bottom of the tower returns to the intermediate buffer tower 03; the semi-lean liquid at the bottom of the tower is divided into two streams.

[0049] (3) Desorption and regeneration: The semi-lean liquid coming out from the bottom of the intermediate buffer tower 03 first returns to the carbon dioxide absorption tower 01 as the absorbent; the second liquid is preheated by the heat exchanger 10 and enters the upper part of the carbon dioxide desorption tower 17; inside the desorption tower, the solution is heated by the reboiler 18, CO2 is desorbed and returned from the top of the tower to the lower part of the intermediate buffer tower 03; the regenerated hot lean liquid is discharged from the bottom of the desorption tower.

[0050] (4) Secondary flash evaporation and energy recovery: The hot lean liquid obtained in step (3) enters the flash tank 07 for further flash evaporation. The liquid phase at the bottom of the flash tank 07 is cooled by the heat exchanger 10 and returned to the top of the carbon dioxide absorption tower 01 as supplementary lean liquid. The gas phase flashed out from the top of the flash tank 07 is pressurized by the compressor 13 and then enters the vortex tube 14 for energy separation.

[0051] (5) Comprehensive energy utilization: The high-temperature and high-pressure gas flowing out from the hot end outlet of the vortex tube 14 returns to the bottom of the carbon dioxide desorption tower 17 to provide part of the regeneration heat energy; the low-temperature gas flowing out from the cold end outlet of the vortex tube 14 returns to the top of the carbon dioxide absorption tower 01 for cooling of the absorption process.

[0052] In step (1), the operating pressure of the carbon dioxide absorption tower 01 is 0.1 MPa to 2.5 MPa, and the operating temperature is 40℃ to 60℃; in step (2), the operating pressure of the low-pressure flash tower 19 is 0.1 MPa to 0.5 MPa. The operating pressure of the carbon dioxide desorption tower 17 is 0.15 MPa to 0.25 MPa, and the temperature of the reboiler 18 is 90℃ to 130℃; in step (4), the outlet pressure of the compressor 13 is 0.8 MPa to 1.2 MPa.

[0053] The carbon dioxide capture system of this invention incorporates a multi-stage flash regeneration process and a flash-compression composite vortex tube high-efficiency energy mode, solving the problems of high energy consumption and easy degradation of absorbent in traditional carbon dioxide capture systems. By constructing a complete system including an absorption unit, a regeneration unit, and an energy recovery unit, the absorption unit achieves efficient carbon dioxide capture through an absorption tower. The regeneration unit significantly reduces energy consumption by combining flash evaporation and desorption. The energy recovery unit achieves energy recycling within the system through lean-rich liquid heat exchange and energy separation via vortex tube 14, ultimately achieving high efficiency, energy saving, and long-term stable operation of the carbon dioxide capture process. The absorption unit consists of a carbon dioxide absorption tower 01 and an intermediate buffer tower 03, employing a high-efficiency packed tower structure to ensure sufficient contact between the absorbent and flue gas. The regeneration unit includes a low-pressure flash tower 19 and a carbon dioxide desorption tower 17, connected to a zone-controlled reboiler 18 to achieve cascaded utilization of heat from the desorption process. The energy recovery unit consists of a lean-rich liquid heat exchanger 10, a compressor 13, and an energy separation device via vortex tube 14, forming a multi-layered heat recovery network. The system employs an absorption-flash-regeneration-re-flash structure, where the low-pressure flash tower 19 directly produces high-purity carbon dioxide, significantly reducing the regeneration load on the desorption tower. The system utilizes an intermediate buffer tower 03 for gas-liquid separation and material distribution. The gaseous phase at the top of the buffer tower enters the low-pressure flash tower 19 to obtain carbon dioxide, while the semi-lean liquid at the bottom is divided into two paths: one returns to the absorption tower for recycling, and the other enters the regeneration system. This multi-stage separation design greatly improves the system's operational flexibility and energy utilization efficiency. The system's energy recovery unit, with its vortex tube 14, effectively separates the energy of the flash steam into hot and cold fluids, which are respectively reused for heating the bottom of the desorption tower and cooling the top of the absorption tower, forming an internal energy recycling mode. The lean-rich liquid heat exchanger 10 enables heat exchange between the hot and cold streams, further reducing external energy input. This multi-level energy recovery design reduces system energy consumption by 25% to 35% compared to traditional methods. Compared to traditional carbon capture systems, this invention achieves a dual reduction in system energy consumption and operating costs through the synergistic effect of a flash evaporation structure and an energy recovery network. The flash evaporation structure in this invention reduces regeneration energy consumption by more than 30% compared to traditional single-stage regeneration; the energy recovery network improves system thermal efficiency by more than 25% compared to traditional simple heat exchange; and compared to traditional amine-based carbon capture systems, operating costs are reduced by 35% to 40%, achieving a balance between high efficiency, stability, and economy in the carbon capture process. This carbon dioxide capture system is suitable for various industrial applications such as coal-fired power plants, gas-fired power plants, steel plants, and cement plants. The system operates stably, with precise control, significant energy-saving effects, and can handle flue gas of different concentrations and flow rates, achieving optimal operating conditions. The system is highly adaptable and can be used for the treatment of various carbon emission sources.

[0054] Experimental Example 1 The high-efficiency, low-energy carbon dioxide capture system of this invention is used. It can process flue gas with a flow rate of 50 Nm³. 3 The CO2 concentration in the flue gas is 12% per hour. The absorbent used is a mixed amine solution of 30% MDEA and 5% piperazine. System operating parameters: absorber pressure 0.8 MPa, bottom temperature 55℃; desorption tower pressure 0.2 MPa, reboiler temperature 120℃; low-pressure flash tower pressure 0.3 MPa, vortex tube hot fluid temperature 122℃, vortex tube hot fluid temperature 42℃. Under these conditions, the system achieves a CO2 capture rate of 90% and a regeneration energy consumption of 2.8 GJ / tCO2. Compared with traditional amine-based systems, operating costs are reduced by 35%.

[0055] Compared to traditional carbon capture systems, this high-efficiency, low-energy carbon dioxide capture system achieves a comprehensive improvement in system performance through the synergistic effect of multi-stage flash evaporation and an energy recovery network. The multi-stage flash evaporation design reduces regeneration energy consumption by more than 30% compared to traditional single-stage regeneration; the energy recovery network improves system thermal efficiency by more than 25% compared to traditional simple heat exchange.

[0056] Experiment Example 2 The high-efficiency, low-energy carbon dioxide capture system of this invention has the same configuration as in Example 1. Parameters were adjusted to suit the characteristics of low-concentration flue gas: the flue gas flow rate was 50 Nm³ / h, and the CO2 concentration was 8%. The absorbent used was a mixed solution of 25% MDEA and 8% piperazine amine. Operating parameters were adjusted as follows: absorber pressure 1.8 MPa, absorber bottom temperature 60°C; desorption tower pressure 0.18 MPa, reboiler temperature 115°C, vortex tube hot fluid temperature 118°C, and vortex tube hot fluid temperature 42°C. Operating results show that the system maintains an 85% CO2 capture rate even under low concentration conditions, with a regeneration energy consumption of 3.0 GJ / CO2.

[0057] Experimental Example 3 The high-efficiency, low-energy carbon dioxide capture system of this invention has the same configuration as in Example 1. Parameters were adjusted to suit the low-concentration flue gas: the flue gas flow rate was 50 Nm³ / h, and the CO2 concentration was 5%. The absorbent was a mixed solution of 5% MEA, 25% MDEA, and 8% piperazine amine. Operating parameters were adjusted as follows: absorber pressure 1.2 MPa, absorber bottom temperature 58°C; desorption tower pressure 0.13 MPa, reboiler temperature 105°C, vortex tube hot fluid temperature 108°C, and vortex tube hot fluid temperature 42°C. Operating results show that the system maintains a 90% CO2 capture rate even under low concentration conditions, with a regeneration energy consumption of 2.8 GJ / CO2. To assess the long-term stability of the system, continuous operation was conducted under the conditions of Experiment Example 3. The fluctuation range of the operating parameters of each unit of the system was as follows: temperature control accuracy ±1℃, pressure control accuracy ±0.02MPa, and flow control accuracy ±1.5%. After 200 hours of continuous operation, the fluctuation range of the system performance indicators was within ±3%, the retention rate of the effective components of the absorbent was >97.5%, and the regeneration energy consumption was 2.8-3.0 GJ / CO2, demonstrating that the system has the ability to operate stably for a long period of time.

[0058] The application of this invention's high-efficiency, low-energy carbon dioxide capture system is unrestricted. The system operates stably, achieves significant energy savings, and is environmentally friendly and efficient. This carbon capture system can be used not only in coal-fired and natural gas power plants, but also, by adjusting process parameters, in various industrial emission sources such as steel mills, cement plants, and chemical plants. The system has a wide range of applications and can be used in carbon reduction projects of various scales.

[0059] Finally, it should be noted that the specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention. For those skilled in the art, it is obvious that this application is not limited to the details of the above exemplary embodiments, and that the present application can be implemented in other specific forms without departing from the spirit or basic characteristics of the present application. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe various possible combinations separately. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this application is defined by the appended claims rather than the foregoing description, and therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be included within this application.

Claims

1. A highly stable carbon dioxide capture system based on a multi-stage flash evaporation process, characterized in that, The system includes a carbon dioxide absorption tower (01), the bottom of which is connected to an intermediate buffer tower (03) via an amine-rich liquid delivery pipe (02). The bottom of the intermediate buffer tower (03) is connected to a semi-lean liquid delivery pipe (04), which is connected to a first semi-lean liquid delivery pipe (06) and a second semi-lean liquid delivery pipe (05) via a tee connector. The first semi-lean liquid delivery pipe (06) is connected to a carbon dioxide desorption tower (17), and the second semi-lean liquid delivery pipe (05) is connected to the top of the carbon dioxide absorption tower (01).

2. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 1, characterized in that, The bottom of the carbon dioxide desorption tower (17) is connected to a flash tank (07) via a hot lean liquid delivery pipe (08).

3. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 2, characterized in that, The bottom of the flash tank (07) is connected to a liquid phase delivery pipe (09) that is connected to the top of the carbon dioxide absorption tower (01). A lean liquid pump (11) and a heat exchanger (10) are connected to the liquid phase delivery pipe (09).

4. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 2, characterized in that, The top of the flash tank (07) is connected to a steam discharge pipe (12), and a vortex pipe (14) is connected to the steam discharge pipe (12). The vortex pipe (14) is connected to a hot gas pipe (16) leading to the bottom of the carbon dioxide desorption tower (17), and the vortex pipe (14) is connected to a cold gas pipe (15) leading to the top of the carbon dioxide absorption tower (01).

5. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 4, characterized in that, A compressor (13) is connected to the steam discharge pipe (12).

6. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 1, characterized in that, The carbon dioxide desorption tower (17) is connected to a reboiler (18).

7. The high-stability carbon dioxide capture system based on a multi-stage flash evaporation process according to claim 1, characterized in that, The top of the intermediate buffer tower (03) is connected to a low-pressure flash tower (19) via a gas pipe.

8. A highly stable carbon dioxide capture method based on a multi-stage flash evaporation process, characterized in that, The carbon dioxide capture system according to any one of claims 1 to 7 is specifically used for the capture method as follows: (1) Absorption process: The raw flue gas enters from the bottom of the carbon dioxide absorption tower (01) and comes into countercurrent contact with the lean amine liquid entering from the top of the tower. The carbon dioxide in the flue gas is absorbed, the purified fuel gas is discharged from the top of the tower, and the carbon dioxide-rich amine liquid is discharged from the bottom of the tower and enters the intermediate buffer tower (03). (2) Gas-liquid separation and first-stage flash evaporation: In the intermediate buffer tower (03), the amine-rich liquid undergoes preliminary gas-liquid separation; the gas phase rich in carbon dioxide at the top of the tower enters the low-pressure flash tower (19) for flash evaporation, and high-purity carbon dioxide gas product is obtained at the top of the tower, while the liquid phase at the bottom of the tower returns to the intermediate buffer tower (03); the semi-lean liquid at the bottom of the tower is divided into two streams. (3) Desorption and regeneration: The semi-lean liquid coming out from the bottom of the intermediate buffer tower (03) first returns to the carbon dioxide absorption tower (01) as the absorbent; the second liquid is preheated by the heat exchanger (10) and enters the upper part of the carbon dioxide desorption tower; inside the desorption tower, the solution is heated by the reboiler (18), CO2 is desorbed and returned from the top of the tower to the lower part of the intermediate buffer tower (03); the regenerated hot lean liquid is discharged from the bottom of the desorption tower. (4) Secondary flash evaporation and energy recovery: The hot lean liquid obtained in step (3) enters the flash tank (07) for further flash evaporation. The liquid phase at the bottom of the flash tank (07) is cooled by the heat exchanger (10) and returned to the top of the carbon dioxide absorption tower (01) as supplementary lean liquid. The gas phase flashed out from the top of the flash tank (07) is pressurized by the compressor (13) and enters the vortex tube (14) for energy separation. (5) Comprehensive energy utilization: The high-temperature and high-pressure gas flowing out from the hot end outlet of the vortex tube (14) returns to the bottom of the carbon dioxide desorption tower (17) to provide part of the regeneration heat energy; the low-temperature gas flowing out from the cold end outlet of the vortex tube (14) returns to the top of the carbon dioxide absorption tower (01) for cooling of the absorption process.

9. A highly stable carbon dioxide capture method based on a multi-stage flash evaporation process according to claim 8, characterized in that, The pressure inside the carbon dioxide absorption tower (01) is controlled at 0.1MPa~2.5MPa, and the temperature is controlled at 40℃~60℃.

10. A highly stable carbon dioxide capture method based on a multi-stage flash evaporation process according to claim 8, characterized in that, The pressure inside the carbon dioxide desorption tower (17) is controlled at 0.15MPa~0.25MPa, and the temperature is controlled at 90℃~130℃.

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