Catalytic desorption apparatus and carbon dioxide capture system

Abstract

The present application relates to carbon dioxide capture and amine absorbent regeneration technical field, disclose a kind of catalytic desorption device and carbon dioxide capture system, wherein, absorption tower is used to form rich CO2 amine liquid;Catalytic desorption tower is used to catalytic desorption regeneration to rich CO2 amine liquid, tower is sequentially provided with upper fixed bed catalytic packing layer, upper fluidized bed catalytic reaction zone, lower fixed bed catalytic packing layer and lower fluidized bed catalytic reaction zone along the flow direction of rich amine liquid, first inlet is opened in catalytic desorption tower, located in upper fixed bed catalytic packing layer above, and second inlet is located in upper fluidized bed catalytic reaction zone position;Shunt mechanism is used to shunt the rich CO2 amine liquid formed by absorption tower into two ways respectively into the first inlet and second inlet of catalytic desorption tower, the present application is realized by subarea arrangement rich amine liquid staged catalytic regeneration, improve CO2 desorption efficiency, reduce reboiling load, and enhance system continuous operation stability.

Description

Technical Field

[0001] This invention relates to the field of carbon dioxide capture and amine absorbent regeneration technology, and in particular to a catalytic desorption device and a carbon dioxide capture system. Background Technology

[0002] Amine-based carbon capture is a mature technology used in the fields of coal-fired flue gas, natural gas purification, and industrial tail gas CO2 capture. This method utilizes the reaction of an alkanolamine solution with CO2 within an absorption tower to form CO2-rich species such as carbamates and bicarbonates. The amine-rich solution is then regenerated by heating in a desorption tower and reboiler. Due to the strong chemical bond between CO2 and amine molecules, traditional thermal regeneration processes typically require high desorption temperatures and large reboiling loads, leading to high system energy consumption and an increased risk of solvothermal degradation.

[0003] To reduce regeneration energy consumption, existing technologies have proposed solutions such as phase change absorbents, composite amine absorbents, solid acid catalytic desorption, and membrane catalytic regeneration. Among these, catalytic desorption technology can promote proton migration and carbamate decomposition through Bronsted acid sites, Lewis acid sites, or pore-confined structures, thereby reducing the regeneration temperature of amine-rich solutions and increasing the CO2 desorption rate per unit time. However, existing catalytic desorption technologies suffer from a lack of catalyst utilization methods and insufficient reactor-catalyst matching, failing to fully utilize the catalyst's activity.

[0004] In existing technologies, fixed-bed systems facilitate catalyst fixation and recovery, but limited liquid-solid contact within the bed can lead to flow deviation, increased pressure drop, or localized deactivation during long-term operation. Fluidized-bed catalysts offer higher mass and heat transfer efficiencies, but severe absorbent mixing occurs in the fluidized state, and desorbed CO2 is difficult to release, causing absorbent foaming and, in severe cases, emulsification. This results in low absorbent regeneration efficiency and low CO2 capture efficiency. Existing solutions often design fixed-bed, fluidized-bed, or packed tower systems as independent structures, which suffers from drawbacks such as large equipment footprint, complex processes, and significant heat loss.

[0005] To address the aforementioned issues, it is necessary to develop a catalytic desorption system for carbon dioxide capture that integrates fluidized and fixed beds within the same tower. Summary of the Invention

[0006] The purpose of this invention is to provide a catalytic desorption device and a carbon dioxide capture system, which aims to solve or improve at least one of the above-mentioned technical problems. By zoning the arrangement, the rich amine liquid is regenerated in stages, so that the fluidized bed zone undertakes the functions of enhanced heat and mass transfer and deep desorption, and the fixed bed zone undertakes the functions of stable catalysis and extended residence time, thereby improving CO2 desorption efficiency, reducing reboiling load, and enhancing the continuous operation stability of the system.

[0007] To achieve the above objectives, the present invention provides the following solution: The present invention provides a catalytic desorption device and a carbon dioxide capture system, comprising: An absorption tower is used to bring CO2-containing flue gas into contact with a lean amine absorbent to form a CO2-rich amine solution. A catalytic desorption tower is used for catalytic desorption and regeneration of the CO2-rich amine solution. The catalytic desorption tower has a vertical tower structure. Inside the tower, along the flow direction of the amine-rich solution, there are sequentially arranged an upper fixed-bed catalytic packing layer, an upper fluidized-bed catalytic reaction zone, a lower fixed-bed catalytic packing layer, and a lower fluidized-bed catalytic reaction zone. The catalytic desorption tower has a first inlet located above the upper fixed-bed catalytic packing layer and a second inlet located in the upper fluidized-bed catalytic reaction zone. The diversion mechanism is used to split the CO2-rich amine liquid formed in the absorption tower into two streams, which are respectively sent to the first inlet and the second inlet of the catalytic desorption tower.

[0008] Optionally, a reboiler is also included, which is connected to the lower fluidized bed catalytic reaction zone.

[0009] Optionally, a jet pump is also included, which is connected to the lower fluidized bed catalytic reaction zone.

[0010] Optionally, the diversion mechanism includes: The diversion regulating valve has one inlet and two outlets. The inlet of the diversion regulating valve is connected to the bottom CO2-rich amine liquid outlet of the absorption tower through a rich liquid transfer pump and pipeline. One of the outlets of the diversion regulating valve is connected to the first inlet of the catalytic desorption tower through an upper rich liquid inlet pipeline. The lean-rich liquid heat exchanger is connected to the other outlet of the diversion regulating valve through a heat exchange preheating inlet pipeline, and the lean-rich liquid heat exchanger is connected to the second inlet of the catalytic desorption tower through a pipeline.

[0011] Optionally, it also includes a lean liquid transfer pump, a storage tank, and a lean liquid circulation pump. The lean liquid transfer pump connects the bottom outlet of the catalytic desorption tower to the lean-rich liquid heat exchanger via a pipeline. The storage tank is connected to the lean-rich liquid heat exchanger via a pipeline. The lean liquid circulation pump connects the storage tank to the liquid inlet at the top of the absorption tower via a pipeline.

[0012] Optionally, the absorption tower is provided with a flue gas inlet at the bottom and a decarbonized flue gas outlet at the top, and the liquid inlet at the top of the absorption tower is located between the flue gas inlet and the decarbonized flue gas outlet.

[0013] Optionally, it also includes a CO2 storage tank connected to the gas outlet of the catalytic desorption tower.

[0014] Optionally, the catalytic packing material in the upper fixed-bed catalytic packing layer and the lower fixed-bed catalytic packing layer is a structured packing material loaded with catalytically active components.

[0015] Optionally, the structured packing is composed of stainless steel corrugated plates loaded with shaped catalyst, and the stainless steel corrugated plates are fixedly installed inside the catalytic desorption tower.

[0016] Optionally, the upper fluidized bed catalytic reaction zone and the lower fluidized bed catalytic reaction zone are provided with scattered particulate catalysts.

[0017] The present invention discloses the following technical effects: This invention integrates the fluidized bed catalytic reaction zone and the fixed bed catalytic packing layer into the same catalytic desorption tower, reducing the process complexity, increased equipment footprint, and heat loss caused by connecting independent reactors.

[0018] The fluidized bed catalytic reaction zone of this invention can enhance the mixing between the amine-rich liquid, the catalyst and the desorbed gas, improve the liquid-solid contact efficiency and the gas-liquid-solid three-phase mass transfer efficiency, which is beneficial to accelerating the decomposition of CO2-rich species such as carbamates and bicarbonates.

[0019] The upper fixed-bed catalytic packing layer of this invention can recover gas-liquid heat and initially desorb CO2; the lower fixed-bed catalytic packing layer can catalytically desorb CO2 and accelerate the release of CO2 gas.

[0020] This invention achieves graded regeneration of rich amine solution and cascaded utilization of heat by combining rich liquid diversion and fixed bed / fluidized bed partitioned catalysis, which can reduce reboiler load and system regeneration energy consumption.

[0021] This invention can be modified based on existing absorption towers, desorption towers and reboiler processes, replacing the original single packing section with a combination structure of fixed bed catalytic packing layer and fluidized bed catalytic reaction zone, which has good engineering adaptability and continuous operation stability. Attached Figure Description

[0022] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a schematic diagram of the structure of the present invention.

[0023] In the diagram: 1. Flue gas inlet; 2. Absorber; 3. Decarbonized flue gas outlet; 4. Rich liquor transfer pump; 5. Diversion regulating valve; 6. Upper rich liquor inlet pipeline; 7. Upper fixed bed catalytic packing layer; 8. Heat exchange preheating inlet pipeline; 9. Upper fluidized bed catalytic reaction zone; 10. Lower fixed bed catalytic packing layer; 11. Lower fluidized bed catalytic reaction zone; 12. Jet pump; 13a. Lean / rich liquor heat exchanger; 13b. Reboiler; 14. Lean liquor transfer pump; 15. Storage tank; 16. Lean liquor circulation pump; 17. CO2 storage tank. Detailed Implementation

[0024] 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.

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] Reference Figure 1 This invention provides a catalytic desorption device and a carbon dioxide capture system, comprising: Absorption tower 2 is used to contact CO2-containing flue gas with lean amine absorbent to form CO2-rich amine solution; A catalytic desorption tower is used for catalytic desorption and regeneration of CO2-rich amine liquid. The catalytic desorption tower has a vertical tower structure. Inside the tower, along the flow direction of the amine-rich liquid, there are sequentially arranged an upper fixed-bed catalytic packing layer 7, an upper fluidized-bed catalytic reaction zone 9, a lower fixed-bed catalytic packing layer 10, and a lower fluidized-bed catalytic reaction zone 11. The catalytic desorption tower has a first inlet located above the upper fixed-bed catalytic packing layer 7 and a second inlet located in the upper fluidized-bed catalytic reaction zone 9. The diversion mechanism is used to split the CO2-rich amine liquid formed in the absorption tower 2 into two streams, which are then sent to the first inlet and the second inlet of the catalytic desorption tower, respectively.

[0027] In this embodiment, a reboiler 13b is also included, which is connected to the lower fluidized bed catalytic reaction zone 11. The reboiler 13b provides heat for the catalytic desorption process. After being heated by the reboiler 13b, the liquid at the bottom of the catalytic desorption tower is returned to the lower fluidized bed catalytic reaction zone 11 at the bottom of the tower in the form of hot liquid, steam, or a gas-liquid mixture.

[0028] In this embodiment, a jet pump 12 is also included, which is connected to the lower fluidized bed catalytic reaction zone 11. The jet pump 12 is used to inject the high-temperature liquid from the outlet of the reboiler 13b into the lower fluidized bed catalytic reaction zone 11 to provide fluidization power.

[0029] In this embodiment, the diversion mechanism includes: The diversion regulating valve 5 has one inlet and two outlets. The inlet of the diversion regulating valve 5 is connected to the bottom CO2-rich amine liquid outlet of the absorption tower 2 through the rich liquid transfer pump 4 and pipeline. One of the outlets of the diversion regulating valve 5 is connected to the first inlet of the catalytic desorption tower through the upper rich liquid inlet pipeline 6. The lean and rich liquid heat exchanger 13a is connected to the other outlet of the diversion regulating valve 5 through the heat exchange preheating inlet pipeline 8, and the lean and rich liquid heat exchanger 13a is connected to the second inlet of the catalytic desorption tower through the pipeline.

[0030] The amine-rich solution after CO2 absorption is discharged from the bottom of absorption tower 2, pressurized by rich solution transfer pump 4, and then enters the diversion regulating valve 5, where it is split into two streams. One outlet is connected to the first inlet of the catalytic desorption tower via the upper rich solution inlet pipeline 6, directly sending a stream of low-temperature amine-rich solution to the top of the catalytic desorption tower. The other outlet is connected to the rich solution inlet of the lean-rich solution heat exchanger 13a via the heat exchange preheating inlet pipeline 8. After the amine-rich solution exchanges heat with the high-temperature lean solution in the lean-rich solution heat exchanger 13a and is heated, it is then connected to the second inlet of the catalytic desorption tower via a pipeline.

[0031] In this embodiment, the system also includes a lean liquid transfer pump 14, a storage tank 15, and a lean liquid circulation pump 16. The lean liquid transfer pump 14 connects the bottom outlet of the catalytic desorption tower to the lean-rich liquid heat exchanger 13a via a pipeline. The storage tank 15 is connected to the lean-rich liquid heat exchanger 13a via a pipeline. The lean liquid circulation pump 16 connects the storage tank 15 to the liquid inlet at the top of the absorption tower 2 via a pipeline.

[0032] In this embodiment, the absorption tower 2 is a conventional packed tower or plate tower. The absorption tower 2 is provided with a flue gas inlet 1 at the bottom and a decarbonized flue gas outlet 3 at the top. The liquid inlet at the top of the absorption tower 2 is located between the flue gas inlet 1 and the decarbonized flue gas outlet 3. The flue gas containing CO2 enters the lower part of the absorption tower 2 through the flue gas inlet 1, and the lean amine liquid enters the tower through the liquid inlet at the top of the absorption tower 2. The flue gas and the lean amine liquid come into countercurrent contact in the tower. After the lean amine liquid absorbs the CO2 in the flue gas, it forms a CO2-rich amine liquid. The decarbonized flue gas is discharged from the decarbonized flue gas outlet 3 at the top of the tower.

[0033] In this embodiment, a CO2 storage tank 17 is also included, which is connected to the gas outlet of the catalytic desorption tower. The CO2 gas generated by desorption carries water vapor and flows upward along the tower body. After gas-liquid separation by the upper fixed bed catalytic packing layer 7 and other conventional tower internals, it enters the CO2 storage tank 17 from the gas outlet at the top of the tower.

[0034] In this embodiment, the catalytic packing material in the upper fixed-bed catalytic packing layer 7 and the lower fixed-bed catalytic packing layer 10 is a structured packing material loaded with catalytically active components. The structured packing material is composed of stainless steel corrugated plates loaded with shaped catalysts, and the stainless steel corrugated plates are fixedly installed inside the catalytic desorption tower.

[0035] Industrial desorption towers are typically equipped with monolithic packing to enhance gas-liquid mass transfer. This invention features an upper fixed-bed catalytic packing layer 7 and a lower fixed-bed catalytic packing layer 10 within the catalytic desorption tower. This arrangement effectively reduces the risk of solid catalyst particle settling and pipeline blockage, thereby extending the system's stable operating life. Furthermore, this structural design significantly extends the effective residence time of the absorbent-rich solution within the catalytic desorption tower and substantially enhances the mass transfer efficiency between the gas and liquid phases. In addition, the monolithic packing can adapt to a wide range of liquid and gas load fluctuations, ensuring operational flexibility. Its geometric structure also helps eliminate emulsification caused by gas-liquid entrainment and provides excellent defoaming properties.

[0036] When the fixed-bed catalytic packing is loaded with active components that have metal ion adsorption or complexation functions, it can also simultaneously remove metal impurities such as Fe²⁺ and Fe³⁺ from the amine solution, thereby reducing the promoting effect of metal ions on the oxidative degradation of the amine solution.

[0037] In this embodiment, the upper fluidized bed catalytic reaction zone 9 and the lower fluidized bed catalytic reaction zone 11 are equipped with scattered particulate catalysts.

[0038] The catalyst is arranged in the form of scattered particles in the upper fluidized bed catalytic reaction zone and the lower fluidized bed catalytic reaction zone. The catalyst exists only in the catalytic desorption tower and does not enter the absorption tower for circulation with the absorbent.

[0039] The fluidization power of the fluidized bed catalytic reaction zone comes from the jet source: the jet source for the upper fluidized bed catalytic reaction zone 9 is the liquid from the outlet of the upper fixed bed catalytic packing layer 7 and the rich liquid preheated by the lean-rich liquid heat exchanger 13a. The liquid is injected into the upper fluidized bed catalytic reaction zone 9 from the middle of the catalytic desorption tower; the jet source for the lower fluidized bed catalytic reaction zone 11 is the high-temperature liquid from the outlet of the reboiler 13b. The high-temperature liquid is injected into the lower fluidized bed catalytic reaction zone via a jet pump. The fluidized reaction mode can realize solid-liquid disturbance, enhance the mass transfer effect between the gas-liquid-solid three phases, and thus improve the catalytic desorption efficiency.

[0040] Working principle: CO2-containing flue gas enters the lower part of the absorption tower 2 through flue gas inlet 1, and comes into countercurrent contact with the lean amine liquid entering from the top of the tower. The decarbonized flue gas is discharged from the decarbonized flue gas outlet 3. The CO2-absorbed rich amine liquid is discharged from the bottom of the absorption tower 2, pressurized by the rich liquid transfer pump 4, and enters the diversion regulating valve 5, where it is divided into two streams: one stream of low-temperature rich amine liquid enters the upper part of the desorption tower through the upper rich liquid inlet pipeline 6, flows through the upper fixed bed catalytic packing layer 7, exchanges heat with the rising CO2-water vapor mixture, and initially releases CO2 under the thermal effect and catalytic action; the other stream of rich amine liquid enters the lean-rich liquid heat exchanger 13a through the heat exchange preheating inlet pipeline 8, exchanges heat with the high-temperature lean liquid, and then enters the upper fluidized bed catalytic reaction zone 9 in the form of a jet. The jet power comes from the rich liquid transfer pump 4, and the absorbent rapidly releases CO2 under the action of the fluidized catalyst. The two streams of absorbent converge in the upper fluidized bed catalytic reaction zone 9 and come into full contact with the fluidized particulate catalyst. The absorbent then flows sequentially through the lower fixed-bed catalytic packing layer 10 and the lower fluidized-bed catalytic reaction zone 11. The lower fixed-bed catalytic packing layer 10 is used to prolong the liquid residence time, enhance catalytic desorption, and promote gas-liquid separation; the lower fluidized-bed catalytic reaction zone 11, under the disturbance provided by the jet pump 12, enhances the mixing of particulate catalyst and absorbent, achieving deep CO2 desorption. The reboiler 13b provides heat for the catalytic desorption process, and the liquid at the bottom of the desorption tower returns to the lower part of the tower in the form of hot liquid, steam, or a gas-liquid mixture after passing through the reboiler 13b. The CO2 gas generated by desorption carries water vapor and flows upward along the tower, undergoes gas-liquid separation through the upper fixed-bed catalytic packing layer and other conventional tower internals, and then enters the CO2 storage tank 17 from the top of the tower. The regenerated high-temperature lean liquid enters the lean-rich liquid heat exchanger 13a via the lean liquid transfer pump 14, exchanges heat with the low-temperature rich amine liquid, cools down, enters the storage tank 15, and is then transported to the top of the absorption tower 2 by the lean liquid circulation pump 16, completing the absorbent circulation.

[0041] This invention is applicable to CO2 capture and absorbent regeneration using single amines such as MEA, AMP, MDEA, and PZ, as well as complex amine solutions, as chemical absorbents. It is also applicable to absorbent catalytic regeneration systems that use solid acid mesoporous materials such as metal oxides and molecular sieves, or composite catalytic materials to promote CO2 desorption.

[0042] The operating temperature range of the catalytic desorption tower is typically 80-150℃, and the operating pressure is atmospheric pressure to 0.5MPa. The heat source for reboiler 13b can be low-pressure steam or heat transfer oil, with a heat source temperature typically between 120-200℃. Those skilled in the art can adjust the above operating parameters appropriately according to the specific amine solution system, CO2 load, and throughput.

[0043] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0044] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A catalytic desorption device and a carbon dioxide capture system, characterized in that, include: Absorption tower (2) is used to contact CO2-containing flue gas with lean amine liquid absorbent to form CO2-rich amine liquid; A catalytic desorption tower is used to catalytically desorb and regenerate the CO2-rich amine liquid. The catalytic desorption tower has a vertical tower structure. Inside the tower, along the flow direction of the amine-rich liquid, there are an upper fixed bed catalytic packing layer (7), an upper fluidized bed catalytic reaction zone (9), a lower fixed bed catalytic packing layer (10), and a lower fluidized bed catalytic reaction zone (11). The catalytic desorption tower has a first inlet located above the upper fixed bed catalytic packing layer (7) and a second inlet located at the position of the upper fluidized bed catalytic reaction zone (9). The diversion mechanism is used to divert the CO2-rich amine liquid formed by the absorption tower (2) into two streams, which are respectively sent to the first inlet and the second inlet of the catalytic desorption tower.

2. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, It also includes a reboiler (13b) connected to the lower fluidized bed catalytic reaction zone (11).

3. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, It also includes a jet pump (12) connected to the lower fluidized bed catalytic reaction zone (11).

4. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, The diversion mechanism includes: The diversion regulating valve (5) has one inlet and two outlets. The inlet of the diversion regulating valve (5) is connected to the bottom CO2-rich amine liquid outlet of the absorption tower (2) through a rich liquid transfer pump (4) and a pipeline. One of the outlets of the diversion regulating valve (5) is connected to the first inlet of the catalytic desorption tower through the upper rich liquid inlet pipeline (6). The lean and rich liquid heat exchanger (13a) is connected to the other outlet of the diversion regulating valve (5) through the heat exchange preheating inlet pipeline (8), and the lean and rich liquid heat exchanger (13a) is connected to the second inlet of the catalytic desorption tower through the pipeline.

5. The catalytic desorption device and carbon dioxide capture system according to claim 4, characterized in that, It also includes a lean liquid transfer pump (14), a storage tank (15), and a lean liquid circulation pump (16). The lean liquid transfer pump (14) connects the bottom outlet of the catalytic desorption tower to the lean-rich liquid heat exchanger (13a) through a pipeline. The storage tank (15) is connected to the lean-rich liquid heat exchanger (13a) through a pipeline. The lean liquid circulation pump (16) connects the storage tank (15) to the liquid inlet at the top of the absorption tower (2) through a pipeline.

6. The catalytic desorption device and carbon dioxide capture system according to claim 5, characterized in that, The absorption tower (2) is provided with a flue gas inlet (1) at the bottom and a decarbonized flue gas outlet (3) at the top. The liquid inlet at the top of the absorption tower (2) is located between the flue gas inlet (1) and the decarbonized flue gas outlet (3).

7. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, It also includes a CO2 storage tank (17) connected to the gas outlet of the catalytic desorption tower.

8. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, The catalytic packing in the upper fixed-bed catalytic packing layer (7) and the lower fixed-bed catalytic packing layer (10) are integrally structured packings loaded with catalytically active components.

9. The catalytic desorption device and carbon dioxide capture system according to claim 8, characterized in that, The structured packing is composed of stainless steel corrugated plates loaded with shaped catalyst, and the stainless steel corrugated plates are fixedly installed inside the catalytic desorption tower.

10. The catalytic desorption device and carbon dioxide capture system according to claim 1, characterized in that, Scattered particulate catalysts are arranged in the upper fluidized bed catalytic reaction zone (9) and the lower fluidized bed catalytic reaction zone (11).

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