System and method for regenerating CO2 chemical absorbent by enhanced membrane separation method

Abstract

The invention provides a system for regenerating a CO2 chemical absorbent by a reinforced membrane separation method and a method for regenerating the CO2 chemical absorbent by the reinforced membrane separation method by using the system. The system comprises a membrane reactor, a microwave heater, an ultrasonic generator and an ultrasonic probe, the membrane reactor is provided with a CO2 absorption liquid rich liquid inlet, a CO2 absorption liquid barren liquid outlet, a gas inlet and a gas outlet, and the microwave heater is adjacent to the membrane reactor, so that generated microwaves are spread into the membrane reactor; and the ultrasonic probe is connected with the ultrasonic generator and is arranged on the inner surface or the outer surface of the membrane reactor. According to the system, microwave regeneration and ultrasonic regeneration are coupled at the same time, so that the regeneration effect of the CO2 chemical absorbent is improved, the CO2 cyclic trapping performance of the absorbent is improved, and carbon emission is effectively reduced.

Description

Technical Field

[0001] This invention pertains to separation technology, specifically to a system and method for regenerating CO2 chemical absorbents using enhanced membrane separation. Background Technology

[0002] Chemical absorption is a technology that selectively separates CO2 gas from flue gas using a chemical reaction between CO2 and a chemical absorbent. This technology is a continuous cyclical process involving two steps: CO2 absorption and desorption. In this process, the absorbent selectively absorbs CO2 from the flue gas at a relatively low temperature in the absorption tower, forming a CO2-rich solution. Subsequently, the CO2-rich solution releases the absorbed CO2 at a higher temperature in the desorption tower, thus regenerating the absorbent. Currently, CO2 chemical absorbents mainly employ thermal regeneration, using heating to release the CO2 from the absorbent. Furthermore, membrane separation-based CO2 absorbent regeneration efficiency is low, and residual CO2 in the absorbent reduces its cyclic capture performance. Therefore, a novel regeneration technology is urgently needed to enhance the regeneration performance of membrane-based CO2 chemical absorbents.

[0003] CN115253608A proposes a method for capturing CO2 from the flue gas of a coal-fired power plant. The CO2 capture method mentioned in this method is the traditional CO2 chemical absorption technology, which uses a conventional reactor to regenerate the amine absorbent, resulting in low regeneration efficiency.

[0004] CN114515496A proposes a system and method for capturing CO2 from the air using renewable energy coupled with a driving force. This method employs microwave technology to regenerate the CO2 chemical absorbent; however, using microwave technology alone to regenerate the absorbent results in low regeneration efficiency.

[0005] Microwave regeneration is developed from thermal regeneration. Microwave regeneration also uses heating to alter the capture properties of the absorbent, thereby achieving CO2 desorption and regeneration of the absorbent. Because microwave heating differs from conventional heating in its molecular temperature rise characteristics, microwave regeneration technology has advantages such as low energy consumption, short heating time, high regeneration efficiency, and better recovery of the capture properties of the regenerated absorbent.

[0006] Ultrasonic technology is widely used in equipment cleaning, water treatment, and other fields. Based on the cavitation effect of ultrasound, it can achieve deformation of solids and liquids, thereby completing reactions, mixing, and mass transfer. Since the viscosity of liquid-liquid two-phase systems is relatively high compared to that of ordinary aqueous absorbents, ultrasonic technology can accelerate fluid turbulence and the renewal rate of the interphase surface, thus enhancing the mass transfer efficiency of the liquid phase. Summary of the Invention

[0007] The main objective of this application is to provide a system and method for regenerating CO2 chemical absorbents using enhanced membrane separation. In the method for regenerating CO2 chemical absorbents using enhanced membrane separation according to the present invention, microwave regeneration and ultrasonic regeneration are simultaneously coupled. Microwave regeneration accelerates the heat transfer rate of the absorbent within the membrane reactor, while ultrasonic regeneration enhances the mass transfer rate of the absorbent within the membrane reactor. This increases the regeneration effect of the CO2 chemical absorbent, overcomes the shortcomings of poor regeneration efficiency in membrane-based CO2 chemical absorbent regeneration technology, improves the CO2 recycling and capture performance of the absorbent, and effectively reduces carbon emissions.

[0008] According to a first aspect of the present invention, a system for regenerating a CO2 chemical absorbent using an enhanced membrane separation method is provided, comprising:

[0009] Membrane reactor, microwave heater, ultrasonic generator and ultrasonic probe,

[0010] The membrane reactor is equipped with a CO2 absorbent rich liquid inlet, a CO2 absorbent lean liquid outlet, a gas inlet, and a gas outlet. A microwave heater is installed adjacent to the membrane reactor so that the generated microwaves can propagate into the interior of the membrane reactor. An ultrasonic probe is connected to the ultrasonic generator and is installed on the inner or outer surface of the membrane reactor.

[0011] Preferably, the system includes multiple ultrasonic probes, each positioned at a different location within the membrane reactor. By placing multiple ultrasonic probes at different locations within the membrane reactor, the ultrasonic waves within the reactor are made more uniform.

[0012] Preferably, the system includes multiple microwave generators. By using multiple microwave generators, the microwaves in the membrane reactor become more uniform.

[0013] According to a second aspect of the present invention, a method for regenerating a CO2 chemical absorbent using an enhanced membrane separation method is provided, comprising the following steps:

[0014] The rich CO2 absorbent from the CO2 absorption tower is fed into the membrane reactor of the CO2 chemical absorbent regeneration system according to the present invention using enhanced membrane separation. Then, under the action of microwaves and ultrasound, it is discharged from the lean CO2 absorbent outlet. The desorbed CO2 is discharged through the gas outlet by vacuuming.

[0015] Microwaves generated by the microwave heater propagate into the membrane reactor, enhancing heat transfer and regeneration of the CO2 absorbent. Ultrasonic waves generated by the ultrasonic generator propagate into the membrane reactor through an ultrasonic probe. Inside the membrane reactor, CO2 molecules are released from the absorbent in the tube side, pass through the membrane micropores into the shell side of the membrane reactor, and are then evacuated out of the shell side.

[0016] Preferably, the ultrasonic power of the ultrasonic generator is 500-2000W, more preferably 600-1000W.

[0017] Preferably, the power of the microwave heater is 500-3000W, more preferably 800-2000W.

[0018] Preferably, the CO2 chemical absorbent is an aqueous solution of ethanolamine, an aqueous solution of N-methyldiethanolamine, or an aqueous solution of 2-amino-2-methyl-1-propanol; more preferably, its concentration is 20 wt% to 30 wt%.

[0019] Preferably, the desorption temperature of the CO2 absorbent rich solution is 40–120°C.

[0020] Preferably, the CO2 absorbent rich liquid flow rate is 1 m³ / s. 3 / h and below.

[0021] Preferably, the regeneration pressure is 30–150 kPa.

[0022] Beneficial effects

[0023] By simultaneously coupling microwave regeneration and ultrasonic regeneration, microwave regeneration accelerates the heat transfer rate of the absorbent in the membrane reactor, while ultrasonic regeneration enhances the mass transfer rate of the absorbent in the membrane reactor. This increases the regeneration effect of the CO2 chemical absorbent, compensates for the poor regeneration efficiency of membrane-based CO2 chemical absorbent regeneration technology, improves the CO2 recycling and capture performance of the absorbent, and effectively reduces carbon emissions. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a system for regenerating CO2 chemical absorbent using an enhanced membrane separation method according to an embodiment of the present invention. Detailed Implementation

[0025] Figure 1 This is a schematic diagram of a system for regenerating CO2 chemical absorbent using an enhanced membrane separation method according to an embodiment of the present invention.

[0026] According to one embodiment of the present invention, a system for regenerating CO2 chemical absorbent by enhanced membrane separation includes a membrane reactor 1, an ultrasonic generator 3, a microwave generator 4, and an ultrasonic probe 2.

[0027] Ultrasonic probe 2 is connected to ultrasonic generator 3 to transmit the ultrasonic waves generated by the ultrasonic generator. As an example, Figure 1Only two ultrasonic probes 2 are shown, but multiple ultrasonic probes 2 can also be used. The ultrasonic probes 2 are located inside the membrane reactor 1. For example, two ultrasonic probes 3 are respectively located on opposite sides of the inner surface of the membrane reactor 1, thereby making the ultrasonic waves in the membrane reactor 1 more uniform. The ultrasonic generator 3 is connected to the ultrasonic probes 2 via wires.

[0028] The microwave generator 4 is disposed adjacent to the membrane reactor 1, for example, disposed on the side of the membrane reactor 1, and as close to the membrane reactor 1 as possible to minimize microwave attenuation due to distance.

[0029] The membrane reactor is equipped with a rich CO2 absorbent inlet, a lean CO2 absorbent outlet, a gas inlet (standby, normally closed), and a gas outlet.

[0030] The process of regenerating CO2 chemical absorbent by enhanced membrane separation is as follows: the rich liquid of CO2 absorbent from the CO2 absorption tower enters the membrane reactor 1 through a booster pump. Under the coupling effect of microwave and ultrasonic waves, CO2 molecules are released from the absorbent in the tube side inside the membrane reactor 1, pass through the membrane micropores into the shell side of the membrane reactor 1, are evacuated and discharged from the gas outlet of the membrane reactor 1.

[0031] The present invention will be explained in detail below with reference to the embodiments. It should be noted that the following embodiments are only used to explain the present invention and are not intended to limit the scope of the present invention.

[0032] Example 1

[0033] The rich solution of CO2 absorbent from the CO2 absorber is used Figure 1 The system shown illustrates the enhanced membrane separation method for regenerating CO2 chemical absorbents. The absorbent enters a hollow fiber membrane reactor for regeneration. The CO2 chemical absorbent is a 30 wt% aqueous solution of ethanolamine. The desorption temperature is 70°C, the shell-side pressure is 50 kPa, and the flow rate of the rich CO2 absorbent is 0.3 m³ / s. 3 The ultrasonic generator has an ultrasonic power of 600W, and the microwave heater has a power of 900W. After regeneration of the CO2 absorbent, the desorption rate reaches 58%.

[0034] Desorption rate calculation formula:

[0035] Desorption rate = (CO2 content in the rich absorbent solution - CO2 content in the poor absorbent solution) / CO2 content in the rich absorbent solution

[0036] Example 2

[0037] The rich solution of CO2 absorbent from the CO2 absorber is used Figure 1The system shown illustrates the enhanced membrane separation method for regenerating CO2 chemical absorbent. The CO2 chemical absorbent enters a hollow fiber membrane reactor for regeneration. The CO2 chemical absorbent is a 20 wt% aqueous solution of N-methyldiethanolamine. The desorption temperature is 80°C, the shell-side pressure is 60 kPa, and the rich liquid flow rate of the CO2 absorbent is 0.5 m³ / s. 3 The ultrasonic generator has an ultrasonic power of 800W, and the microwave heater has a power of 1800W. After regeneration of the CO2 absorbent, the desorption rate reaches 65%.

[0038] Example 3

[0039] The rich solution of CO2 absorbent from the CO2 absorber is used Figure 1 The system shown illustrates the enhanced membrane separation method for regenerating the CO2 chemical absorbent. The absorbent enters a hollow fiber membrane reactor for regeneration. The CO2 chemical absorbent is a 20 wt% aqueous solution of N-methyldiethanolamine. The desorption temperature is 60 °C, the shell-side pressure is 40 kPa, and the rich solution flow rate is 0.4 m³ / s. 3 The ultrasonic generator has an ultrasonic power of 600W, and the microwave heater has a power of 900W. After regeneration of the CO2 absorbent, the desorption rate reaches 55%.

[0040] Comparative Example 1

[0041] The absorbent was regenerated using a separate hollow fiber membrane reactor; that is, no microwave heater or ultrasonic generator was used. The CO2 chemical absorbent was a 30 wt% aqueous solution of ethanolamine, the desorption temperature was 50 °C, the shell-side pressure was 50 kPa, and the rich liquid flow rate of the CO2 absorbent was 0.3 m³ / s. 3 / h. After regeneration of the CO2 absorbent rich solution, the desorption rate is 45%.

[0042] By comparing the desorption rates of the 30 wt% ethanolamine aqueous solution in Example 1 and Comparative Example 1, it can be seen that the method of regenerating CO2 chemical absorbent using the microwave-ultrasound synergistic enhanced membrane separation method of the present invention has an enhanced absorbent regeneration effect.

Claims

1. A system for regenerating a CO 2 chemical absorbent by a reinforced membrane separation method, comprising: a membrane reactor, a microwave heater, an ultrasonic generator and an ultrasonic probe, wherein the membrane reactor is provided with a CO 2 absorbent rich liquid inlet, a CO 2 absorbent lean liquid outlet, a gas inlet and a gas outlet, the microwave heater is arranged adjacent to the membrane reactor so that the generated microwaves propagate into the interior of the membrane reactor, and the ultrasonic probe is connected to the ultrasonic generator and arranged on the inner or outer surface of the membrane reactor. The system comprises a plurality of ultrasonic probes arranged at different positions of the membrane reactor.

2. The system for regenerating a CO2 chemical absorbent of an enhanced membrane separation process according to claim 1, wherein, The system comprises a plurality of microwave generators.

3. The system for regenerating a CO2 chemical absorbent of an enhanced membrane separation process according to claim 1 or 2, wherein, 4.A method for regenerating a CO 2 chemical absorbent by a reinforced membrane separation method, comprising the following steps: feeding a CO 2 absorbent rich liquid from a CO 2 absorption tower into the membrane reactor of the system according to any one of claims 1 to 3, and then discharging the CO 2 absorbent lean liquid from the CO 2 absorbent lean liquid outlet under the action of microwaves and ultrasonic waves, and discharging the desorbed CO 2 through the gas outlet by vacuumizing. The ultrasonic generator has an ultrasonic power of 500 to 2000 W, preferably 600 to 1000 W.

5. The method of regenerating a CO2 chemical absorbent by a membrane separation process according to claim 4, wherein, The microwave heater has a power of 500 to 3000 W, preferably 800 to 2000 W.

6. The method of regenerating a CO2 chemical absorbent by a strengthened membrane separation process according to claim 4, wherein, The CO 2 chemical absorbent is an aqueous solution of ethanolamine, an aqueous solution of N-methyldiethanolamine or an aqueous solution of 2-amino-2-methyl-1-propanol; preferably, it has a concentration of 20 wt% to 30 wt%.

7. The process of claim 4, wherein the process is operated at a temperature of from 40°C to 60°C. The desorption temperature of the CO 2 absorbent rich liquid is 40 to 120℃.

8. The method of regenerating a CO2 chemical absorbent by a strengthened membrane separation process according to claim 4, wherein, The regeneration pressure is 30 to 150 kPa.

9. The method of regenerating a CO2 chemical absorbent by a strengthened membrane separation process according to claim 4, wherein, The flow rate of the CO2 absorption liquid rich liquid is 1 m 3 / h or less.

10. The method of regenerating a CO2 chemical absorbent by a membrane separation process according to claim 4, wherein, ​

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