A co-current CO2 low-resistivity high-efficiency absorption device and method

Abstract

The application belongs to the technical field of CO2 capture, and discloses a concurrent flow type CO2 low-resistance high-efficiency absorption device and method. The device comprises an absorption chamber and a water washing and demisting chamber. The top of the absorption chamber is provided with a flue gas inlet. The flue gas inlet is provided with a gas distributor. A plurality of spray layers are arranged below the gas distributor. A filler layer is arranged below each spray layer. Each spray layer is provided with an atomizing nozzle with an upward opening. The bottom flue gas inlet of the water washing and demisting chamber is communicated with the absorption chamber. The CO2 absorption device adopts a gas-liquid concurrent flow contact mode, can avoid flooding, and has a total pressure drop of less than 500 Pa, is not sensitive to gas-liquid ratio fluctuations, is suitable for large-flow flue gas scenes, and is stable in operation. The CO2 absorption device integrates a water washing and demisting function, has a compact structure, occupies a small area, and can also reduce independent equipment investment.

Description

Technical Field

[0001] This application belongs to the field of CO2 capture technology, and specifically relates to a co-current CO2 low-resistance high-efficiency absorption device and method. Background Technology

[0002] Carbon dioxide, as one of the major greenhouse gases, has become a key focus of global climate change research. CO2 capture technology (CCS) is considered a crucial means to mitigate climate change and reduce CO2 emissions. Chemical absorption CO2 capture technology is widely used due to its mature technology and high capture efficiency at low CO2 concentrations. The absorption tower is the core separation tower in the CO2 capture process, generally employing a gas-liquid countercurrent contact method. The absorbent enters from the top of the tower, and the gas enters from the bottom, resulting in a large contact area and mass transfer driving force between the two phases within the tower. When gas or liquid velocities fluctuate, this contact method is prone to instability phenomena such as increased gas pressure drop and flooding. Furthermore, if operating parameters such as the gas-liquid ratio deviate significantly from their optimal values, the absorption effect of countercurrent contact may be significantly affected, resulting in relatively limited operational flexibility. Moreover, liquid countercurrent contact absorption towers typically require specially designed packing or tray structures to ensure sufficient and stable countercurrent flow of gas and liquid, leading to increased equipment manufacturing costs and complexity.

[0003] Under conditions of high flue gas velocity, high pressure drop requirements, and limited equipment investment, counter-current CO2 absorbers struggle to meet the demands for low-resistance, high-efficiency carbon capture, necessitating the development of novel CO2 absorbers suitable for this scenario. Co-current CO2 absorbers offer a new solution for addressing high flue gas velocity, low pressure drop, and high stability. Co-current absorbers have a relatively simple structure and high operational flexibility, making them suitable for handling high-velocity, high-volume flue gas. However, as the gas and liquid flow downwards within the tower, the enriched components continuously transfer from one phase to another, leading to a gradual decrease in the driving force between the gas and liquid. At the outlet, the gas and liquid may have reached near equilibrium, resulting in a significant decrease in the mass transfer rate. This is a problem that co-current CO2 absorbers urgently need to address.

[0004] Therefore, it is necessary to provide a co-current CO2 low-resistance high-efficiency absorption device and method. Summary of the Invention

[0005] To address the aforementioned problems, this application discloses a co-current CO2 low-resistance high-efficiency absorption device, comprising an absorption chamber and a water-washing and demisting chamber. A flue gas inlet is located at the top of the absorption chamber, and a gas distributor is installed at the flue gas inlet. Multiple spray layers are arranged below the gas distributor, and a packing layer is arranged below each spray layer. Each spray layer is equipped with upward-opening atomizing nozzles. The inlets of the atomizing nozzles are connected to absorbent addition pipes. A solution tank is located at the bottom of the absorption chamber, and the solution tank has multiple outlets. The bottom flue gas inlet of the water washing and demisting chamber is connected to the absorption chamber. The connection point is located above the solution pool and below all the packing layers.

[0006] Furthermore, each packing layer is equipped with an ultrasonic unit.

[0007] Furthermore, the ultrasonic unit operates at a frequency of 20kHz-300kHz and has a sound power density of 0.1-5W / cm². 3 .

[0008] Furthermore, the atomizing nozzle is an atomizing charged nozzle.

[0009] Furthermore, the operating voltage range of the atomizing charged nozzle is 5-30kV, and the droplet size of the spray is 80–180μm.

[0010] Furthermore, the inlet of each atomizing nozzle is connected in sequence to the absorbent circulation pump and any one of the outlets of the solution pool via pipes.

[0011] Furthermore, each section of the packing layer uses corrugated angled regularized packing.

[0012] Furthermore, the corrugated angle of the corrugated structured packing ranges from 15° to 45°. From top to bottom, the corrugation angle of the regular packing decreases sequentially.

[0013] Furthermore, a flue gas outlet is provided at the top of the water washing demister chamber. Below the flue gas outlet, from top to bottom, a demister, a washing water inlet pipe, a liquid distributor, a water washing packing layer, and a liquid collection tray are arranged in sequence. The liquid collection tray is connected in sequence to a washing water storage tank, a washing water circulation pump, and a washing water inlet pipe.

[0014] This application also discloses a co-current CO2 low-resistance high-efficiency absorption method, which uses the above-mentioned device to absorb CO2.

[0015] The technical effects and advantages of this application are as follows: 1. The CO2 absorption device of this application adopts a gas-liquid co-current contact method, which can avoid flooding. The total pressure drop of the device is less than 500Pa, and it is not sensitive to gas-liquid ratio fluctuations. It is suitable for high-flow flue gas scenarios and operates stably.

[0016] 2. The absorption device of this application adopts an alternating arrangement of multiple spray layers and packing layers, which can improve the gas-liquid contact area and liquid uniformity.

[0017] 3. The absorption device of this application uses an atomizing charged nozzle, which can make the droplets uniformly charged, greatly reducing the risk of flooding and external carryover.

[0018] 4. The absorption device of this application is equipped with an ultrasonic unit in each packing layer. Ultrasonic assistance is used to avoid flow stagnation and extreme pressure drop, thereby effectively improving the local mass transfer rate.

[0019] 5. The absorption device of this application integrates water washing and demisting functions, has a compact structure, occupies a small area, and can reduce investment in independent equipment.

[0020] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of a co-current CO2 low-resistance high-efficiency absorption device according to an embodiment of this application is shown.

[0023] Reference numerals: 1. Flue gas inlet; 2. Flue gas outlet; 3. Gas distributor; 4. First-stage spray layer; 5. First-stage packing layer; 6. Second-stage spray layer; 7. Second-stage packing layer; 8. Third-stage spray layer; 9. Third-stage packing layer; 10. Solution tank; 11. Absorbent circulation pump; 12. Liquid collection tray; 13. Water washing packing layer; 14. Liquid distributor; 15. Washing water inlet pipe; 16. Demister; 17. Washing water storage tank; 18. Washing water circulation pump; 19. First-stage ultrasonic unit; 20. Second-stage ultrasonic unit; 21. Third-stage ultrasonic unit. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] To meet the production requirements of high flue gas velocity, high pressure drop, and limited equipment investment, this application discloses a co-current CO2 low-resistance high-efficiency absorption device, such as... Figure 1As shown, the device includes an absorption chamber and a water-washing demister chamber. A flue gas inlet 1 is located at the top of the absorption chamber, and a gas distributor 3 is installed at the flue gas inlet 1. Multiple spray layers are arranged below the gas distributor 3, and a packing layer is arranged below each spray layer. Each spray layer is equipped with an upward-opening atomizing nozzle. The inlet of the atomizing nozzle is connected to an absorbent addition pipe. A solution tank 10 is located at the bottom of the absorption chamber, and the solution tank 10 has multiple outlets. The flue gas inlet at the bottom of the water-washing demister chamber is connected to the absorption chamber, with the connection point located above the solution tank 10 and below all the packing layers. This application improves initial mass transfer by placing the flue gas inlet 1 at the top of the absorption chamber and the upward-opening atomizing nozzle, allowing the absorbent to contact the flue gas in a counter-current manner before entering the packing layer. Then, the flue gas and absorbent flow downwards within the absorption chamber, and the gas and liquid contact in a co-current manner, continuously transferring enriched components from the flue gas to the absorbent. This application also provides multiple spray layers and packing layers arranged sequentially from top to bottom in the absorption chamber, enabling continuous mass transfer between the gas and liquid layers. Each spray layer ensures liquid redistribution and avoids a decrease in mass transfer efficiency caused by the deviation of the liquid flow path.

[0026] In some embodiments of this application, each filler layer is provided with an ultrasonic unit, the ultrasonic unit having an operating frequency of 20kHz-300kHz and a sound power density of 0.1-5W / cm². 3 By introducing ultrasonic units into each section of the packing material, acoustic vibrations disrupt the liquid film boundary layer, inducing micro-turbulence or generating micro-cavitation. This increases the refresh frequency of the mass transfer interface from the gas phase CO2 to the liquid phase, thereby reducing the local liquid film thickness, avoiding flow stagnation and extreme pressure drops, and improving the local mass transfer rate.

[0027] In some embodiments of this application, the atomizing nozzle is an atomizing charged nozzle with an operating voltage range of 5-30kV and a droplet size of 80-180μm. The absorbent is sprayed through multiple atomizing nozzles, and the droplet size is controlled at 100-200μm, which can effectively avoid flooding. In addition, using the atomizing charged nozzle to apply an electrostatic field to the sprayed droplets causes the sprayed droplets to repel each other after being charged, which can improve droplet dispersion, reduce agglomeration, and improve the liquid distribution and liquid film uniformity in the absorption chamber.

[0028] In some embodiments of this application, the inlet of each atomizing nozzle is also connected in sequence to either the absorbent circulation pump 11 or the outlet of the solution tank 10 via a pipe. After being collected in the solution tank 10, the absorbent is returned to the spray layer by the absorbent circulation pump 11, which prolongs the liquid residence time, improves the solubility and absorption efficiency of CO2, and alleviates the problem of insufficient liquid utilization in co-current operation.

[0029] In some embodiments of this application, each packing layer uses corrugated angled structured packing with a corrugated angle ranging from 15° to 45°, decreasing sequentially from top to bottom. Within the absorption chamber, from top to bottom, small droplets gradually increase in size due to collision, aggregation, and confluence. Furthermore, the multi-layer spray arrangement increases the flow rate of the absorbent per unit space. The same packing size and structure no longer meet the requirements for low-resistance flow and efficient CO2 capture during actual operation. Therefore, corrugated plate structured packing with different angles is used in each packing layer to match the local gas velocity with the liquid film thickness. The corrugated angle is 15° to 45°. In the upper packing layer with low liquid load, a large angle packing is used to increase the gas-liquid contact area and enhance mass transfer; in the middle packing layer with medium liquid load, a medium angle packing is used to balance flow resistance and mass transfer efficiency; and in the bottom packing layer with high liquid load, a small angle packing is used to maintain a low pressure drop.

[0030] In some embodiments of this application, a flue gas outlet is provided at the top of the water washing demister. Below the flue gas outlet, from top to bottom, a demister, a washing water inlet channel, a liquid distributor, a water washing packing layer, and a liquid collection tray are arranged sequentially. The liquid collection tray is connected in sequence to a washing water storage tank, a washing water circulation pump, and a washing water inlet pipe. By providing a water washing demister on the side of the absorption chamber, the flue gas undergoes secondary purification after absorption, removing entrained droplets and residual absorbent, and is finally discharged through the demister, avoiding secondary pollution to subsequent equipment and the environment. This integrated design eliminates the need for a separate water washing tower, saving on equipment footprint and investment.

[0031] This application also discloses a co-current CO2 low-resistance high-efficiency absorption method, which uses the above-mentioned device to absorb CO2.

[0032] To better illustrate this solution, the following embodiments are provided. The co-current CO2 low-resistance high-efficiency absorption device in the following embodiments includes an absorption chamber and a water washing and demisting chamber. A flue gas inlet 1 is provided at the top of the absorption chamber. A gas distributor 3 is installed at the flue gas inlet 1. Below the gas distributor 3, a first-stage spray layer 4, a second-stage spray layer 6, and a third-stage spray layer 8 are arranged in sequence. Below each spray layer, a first-stage packing layer 5, a second-stage packing layer 7, and a third-stage packing layer 9 are arranged respectively. Each spray layer is provided with an upward-opening atomizing charged nozzle. Each packing layer is provided with a first-stage ultrasonic unit 19, a second-stage ultrasonic unit 20, and a third-stage ultrasonic unit 21. A solution pool 10 is provided at the bottom of the absorption chamber. The solution pool 10 is provided with multiple outlets. The inlets of the atomizing nozzles are connected to the absorbent circulation pump 11 and any one outlet of the solution pool 10 in sequence through pipes. The bottom flue gas inlet of the water washing demister is connected to the absorption chamber. The connection point is located above the solution pool 10 and below all the packing layers. The top of the water washing demister is provided with a flue gas outlet 2. Below the flue gas outlet 2, from top to bottom, are arranged a demister 16, a washing water inlet pipe 15, a liquid distributor 14, a water washing packing layer 13, and a liquid collection tray 12. The liquid collection tray 12 is connected in sequence to a washing water storage tank 17, a washing water circulation pump 18, and a washing water inlet pipe 15.

[0033] Example 1 The aforementioned co-current CO2 low-resistance high-efficiency absorption device is installed at the tail end of a coal-fired power plant unit. The flue gas flow rate is 100,000 Nm³ / h, and the CO2 concentration is approximately 12 vol%. The flue gas enters the absorption chamber through flue gas inlet 1 and is evenly distributed through gas distributor 3.

[0034] The absorbent used is a 30wt% MEA solution. The atomizing charged nozzle has a charging voltage of 15kV, the droplet size is controlled at 120-150μm, and the spraying pressure is 0.35–0.45MPa. The first-stage packing layer 5 uses corrugated, structured packing with a 45° inclination angle and a height of 1.5m. The first-stage ultrasonic unit 19 has a power density of 0.2W / cm³. 3 The second-stage packing layer 7 uses corrugated, structured packing with a 38° inclination angle and a height of 1.5m. The second-stage ultrasonic unit 20 has a power density of 1.2W / cm³. 3 The three-section packing layer uses corrugated, structured packing with a 32° inclination angle and a height of 1.5m. The three-section ultrasonic unit has a power density of 2.4W / cm³. 3 .

[0035] The flue gas velocity in the empty tower is controlled at 2.0 m / s, and the total pressure drop is 450 Pa. The absorbent is collected in solution tank 10 and then returned to the spray layer via absorbent circulation pump 11 at a circulation ratio of 4:1. After treatment in the absorption chamber and water washing demister chamber, the CO2 concentration in the flue gas at outlet 2 is reduced to approximately 1 vol%, and the capture rate reaches 92%. Compared with a traditional counter-current tower, the energy consumption per unit of flue gas treated is reduced by 18%.

[0036] Example 2 The aforementioned co-current CO2 low-resistance high-efficiency absorption device is installed after the blast furnace gas purification device in a steel plant. The flue gas flow rate is 50,000 Nm³ / h, and the CO2 concentration is approximately 20 vol%. The flue gas enters the absorption chamber through flue gas inlet 1 and is evenly distributed through gas distributor 3.

[0037] The absorbent used is a 30wt% MEA solution. The atomizing charged nozzle is charged at 20kV, the droplet size is controlled at 150μm, and the spraying pressure is 0.45-0.5MPa. The packing layer uses structured plastic packing, with each section 1.2m high and a total packing height of 3.6m. One section of packing layer 5 uses corrugated structured packing with a 35° inclination angle, and one section of ultrasonic unit 19 has a power density of 0.5W / cm³. 3 The second-stage packing layer 7 uses corrugated, structured packing with a 30° inclination angle, and the second-stage ultrasonic unit 20 has a power density of 1.5 W / cm³. 3 The three-section packing layer uses corrugated, structured packing with a 25° inclination angle, and the three-section ultrasonic unit has a power density of 3.0 W / cm³. 3 .

[0038] The flue gas velocity in the empty tower is controlled at 1.8 m / s, and the total pressure drop is 480 Pa. During operation, the absorbent is refluxed via a circulation pump, extending the liquid residence time by more than 30%. The CO2 concentration in the flue gas at outlet 2 is reduced to below 2 vol%, with a capture rate of over 90%.

[0039] Example 3 The aforementioned co-current CO2 low-resistance high-efficiency absorption device is installed in the exhaust section of a bulk carrier engine. The flue gas flow rate is 80,000 Nm³ / h, and the CO2 concentration is approximately 4.5 vol%. The flue gas enters the absorption chamber through flue gas inlet 1 and is evenly distributed through gas distributor 3.

[0040] The absorbent used is a 30wt% MEA solution. The atomizing charged nozzle is charged at 20kV, the droplet size is controlled at 100-200μm, and the spraying pressure is 0.3-0.4MPa. The packing layer uses structured plastic packing, with each section 0.8m high and a total packing height of 2.8m. One section of packing layer 5 uses corrugated structured packing with a 48° inclination angle, and one section of ultrasonic unit 19 has a power density of 0.1W / cm³. 3 The second-stage packing layer 7 uses corrugated, structured packing with a 42° inclination angle, and the second-stage ultrasonic unit 20 has a power density of 0.8 W / cm³. 3 The three-section packing layer uses corrugated, structured packing with a 35° inclination angle, and the three-section ultrasonic unit has a power density of 1.6 W / cm³. 3 .

[0041] The flue gas velocity in the empty tower was controlled at 2.5 m / s, and the total pressure drop was 400 Pa. Through continuous operation testing, the device maintained good performance under the carbon capture conditions of ship engine exhaust, with a CO2 capture rate of 91%. Compared with conventional counter-current towers, the system pressure drop was reduced by more than 25%.

[0042] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A co-current type low-resistance high-efficiency CO2 absorption device, characterized in that, The device includes an absorption chamber and a water washing and demisting chamber. A flue gas inlet is located at the top of the absorption chamber, and a gas distributor is installed at the flue gas inlet. Below the gas distributor are multiple spray layers, and below each spray layer is a packing layer. Each spray layer has upward-opening atomizing nozzles. The inlets of the atomizing nozzles are connected to absorbent addition pipes. A solution tank with multiple outlets is located at the bottom of the absorption chamber. The bottom flue gas inlet of the water washing and demisting chamber is connected to the absorption chamber, and the connection point is located above the solution pool and below all the packing layers.

2. The apparatus according to claim 1, characterized in that, Each of the aforementioned filler layers is equipped with an ultrasonic unit.

3. The apparatus according to claim 2, characterized in that, The ultrasonic unit operates at a frequency of 20kHz-300kHz and has a sound power density of 0.1-5W / cm². 3 .

4. The apparatus according to claim 1, characterized in that, The atomizing nozzle is an atomizing charged nozzle.

5. The apparatus according to claim 4, characterized in that, The operating voltage range of the atomizing charged nozzle is 5-30kV, and the droplet size of the spray is 80-180μm.

6. The apparatus according to claim 1, characterized in that, The inlet of each atomizing nozzle is also connected in sequence to an absorbent circulation pump and any one of the outlets of the solution pool via pipes.

7. The apparatus according to claim 1, characterized in that, The packing layers in each section use corrugated angled packing.

8. The apparatus according to claim 7, characterized in that, The corrugated angle of the corrugated structured packing ranges from 15° to 45°. From top to bottom, the corrugation angle of the corrugated packing decreases sequentially in each section.

9. The apparatus according to claim 1, characterized in that, The top of the water washing demister is provided with a flue gas outlet. Below the flue gas outlet, from top to bottom, there are a demister, a washing water inlet pipe, a liquid distributor, a water washing packing layer and a liquid collection tray. The liquid collection tray is connected in sequence to a washing water storage tank, a washing water circulation pump and a washing water inlet pipe.

10. A co-current, low-resistivity, high-efficiency CO2 absorption method, characterized in that, CO2 is absorbed using the device according to any one of claims 1-9.

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