A CO2 capture and desorption process integrating multi-stage spray cross distribution and waste heat cascade recovery optimization

Abstract

The application discloses a CO2 capture and desorption process integrating multistage spray cross distribution and waste heat gradient recovery optimization, and the system comprises an absorption tower and a desorption tower, wherein the absorption tower comprises a flue gas pretreatment section, a filtering and cleaning section, a spray-foaming section, a flue gas defoaming section, a filler section and a liquid storage section; and the desorption tower comprises a desorption section and a waste heat recovery section. The system improves the absorption tower and the desorption tower structure, provides an absorbent capable of significantly reducing the corrosion of the tower body and the filler, improves the capture performance of the absorbent, integrates the spray-foaming, the filler and the liquid storage tank into one, improves the regeneration efficiency and reduces the regeneration energy consumption, and solves the problems of low absorption efficiency, high energy consumption, large occupation area, uneven spraying, easy blocking of the foaming device and the like.

Description

Technical Field

[0001] This invention relates to the field of capture and desorption technology, and in particular to a CO2 capture and desorption process that integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization. Background Technology

[0002] CO2 capture technology, as an important means of reducing atmospheric CO2 concentration, has been widely researched and applied. Chemical absorption CO2 capture technology, with its advantages of high maturity, wide application, and easy integration with existing industrial processes, is particularly suitable for large-scale emission scenarios such as coal-fired power plants. This technology relies on the gas-liquid mass transfer mechanism, utilizing amine liquid to absorb and desorb CO2 from flue gas in a two-step process of absorption and regeneration to purify CO2. Traditional packed towers use a spray method to allow the absorbent to fall from the top of the tower and come into countercurrent contact with the flue gas entering from the bottom. However, due to the short gas-liquid contact time and small reaction interface, the absorption rate of CO2 by the amine liquid is limited, resulting in low efficiency, high energy consumption, and large footprint, which restricts its industrial-scale promotion. Furthermore, this technology still faces challenges such as high regeneration energy consumption, easy degradation of the absorbent leading to equipment corrosion and operational stability issues, and increased operating costs due to absorbent recycling losses. Therefore, it is urgent to overcome these technical bottlenecks through the development of new absorbents and process innovation. Based on this, researchers are developing new absorbents, optimizing process flows, and integrating energy recovery to overcome existing technical limitations.

[0003] The absorption tower integrates spraying-foaming, packing, and storage tanks, significantly reducing the floor space required and saving land resources. The absorbent is atomized into small droplets through nozzles, increasing the gas-liquid contact area and improving absorption efficiency. However, due to limitations imposed by nozzle design, spray pressure, and angle, the spray range cannot fully cover the cross-section of the absorption tower, resulting in insufficient spraying in some areas, uneven gas-liquid contact, and affecting CO2 absorption efficiency. The atomized droplets generate bubbles through the foaming mesh, further increasing the gas-liquid contact area and thus improving absorption efficiency. However, the foaming mesh is sensitive to liquid conditions; if the liquid contains impurities or solid particles, they can easily accumulate at the mesh openings, causing blockage. Therefore, it is necessary to optimize the equipment structure to improve the absorbent's absorption performance.

[0004] Traditional desorption units typically rely on steam as the primary heat source for the reboiler. This approach leads to significant steam consumption during absorbent regeneration, resulting in high overall energy consumption. Furthermore, under high-temperature steam conditions, some absorbent may undergo thermal degradation or incomplete regeneration, reducing its recycling efficiency and negatively impacting subsequent CO2 absorption performance. The generation of waste heat during desorption, if not recovered, leads to thermal energy loss and increased energy consumption. Therefore, further improvements to the internal structure of the desorption tower are needed to reduce energy consumption during the desorption process.

[0005] Patent application CN119345855A discloses a desorption tower bottom liquid waste heat recovery system based on the principle of absorption heat pump. The bottom liquid circulation loop includes a first material pipe leading from the desorption tower bottom as a high-grade heat source for heating, connected to a waste heat recovery device. The waste heat recovery device then flows out and connects to the tower bottom via a second material pipe, forming a closed loop. The lean amine liquid circulation loop includes a lean liquid pipeline pumping material from the desorption tower bottom to the top of the absorption tower. The lean liquid pipeline includes a third material pipe entering the waste heat recovery device and a fourth material pipe exiting the waste heat recovery device. This invention, the desorption tower bottom liquid waste heat recovery system, recovers waste heat from the lean amine liquid, reducing the amount of circulating water used. Furthermore, it recovers and utilizes the low-grade heat source in the lean amine liquid to heat the material in the desorption tower bottom. By using the waste heat recovery device to replace the high-temperature heat source of the reboiler at the bottom of the tower with low-grade waste heat, the system reduces the process steam consumption of the desorption tower reboiler, significantly saving steam. The existing technical defects are as follows: 1. The atomized droplets in the atomization-foaming section of the absorption tower do not contact the gas evenly, which affects the absorption efficiency of the absorbent; 2. The gas after treatment by the absorption tower may carry foam, which affects the stability of the equipment; 3. The regeneration process of the desorption tower requires a large amount of steam, resulting in high overall energy consumption. In addition, it leads to a decrease in the regeneration efficiency of the absorbent, which affects the subsequent absorption effect.

[0006] Therefore, in response to the common problems of low absorption efficiency, high energy consumption, large footprint, uneven spraying, and easy clogging of foaming devices in existing CO2 chemical absorption towers in industrial applications, there is an urgent need for a new tower structure and absorbent to solve the above problems. Summary of the Invention

[0007] To address the aforementioned problems, this invention provides a CO2 capture and desorption process that integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization. The aim is to improve the structure of the absorption and desorption towers and to provide an absorbent that significantly reduces corrosion to the tower body and packing, thereby enhancing the capture performance of the absorbent. This process integrates spray-foaming, packing, and storage tank into one unit, improving regeneration efficiency and reducing regeneration energy consumption. It solves problems such as low absorption efficiency, high energy consumption, large footprint, uneven spraying, and easy clogging of the foaming device.

[0008] To address the problems in the existing technology, the technical solution adopted by this invention is as follows:

[0009] A CO2 capture and desorption process optimized by multi-stage spray cross-distribution and waste heat cascade recovery includes an absorption tower and a desorption tower. The absorption tower includes a flue gas pretreatment section, a filtration and cleaning section, a spray-foaming section, a flue gas defoaming section, a packing section, and a liquid storage section. The desorption tower includes a desorption section and a waste heat recovery section.

[0010] The flue gas pretreatment section includes a pressure sensor, a flue gas filter, and a pulse backflushing device; the flue gas filter is equipped with a pressure sensor at both the inlet and outlet ends, and the outlet end is equipped with the pulse backflushing device, and the outlet end is connected to the bottom of the packing section.

[0011] The packing section includes a gas lift-up pipe, a liquid distributor, packing, and a rich liquid outlet valve; the liquid distributor is installed at the top of the packing section, the packing is installed below the liquid distributor, and the bottom of the packing section is connected to the desorption tower through a rich liquid delivery pipeline; the inlet end of the gas lift-up pipe is connected to the top of the packing section, and the outlet end extends into the interior of the spray-foaming section.

[0012] The liquid storage section includes a liquid storage tank, a pump, a liquid lift-up pipe, a switch valve, and a lean liquid inlet valve; the liquid storage tank is used to store absorbent, and a switch valve is provided at the bottom. The switch valve is connected to two liquid lift-up pipes through the pump.

[0013] The filtration and cleaning section includes a filter, a pressure sensor, an automatic backwash valve, and a waste liquid tank. The filter is located at the top of the absorption tower, and its top is connected to the bottom of the storage tank via a liquid lift pipe for conveying. An automatic backwash valve is provided at the bottom of the filter, and the automatic backwash valve is connected to the bottom of the storage tank via another liquid lift pipe for backwashing. A waste liquid tank is connected to the top of the filter.

[0014] The spray-foaming section includes a sprayer, a gas distributor, a multi-stage foaming net, and a liquid outlet; the sprayer consists of multiple nozzles, which are distributed in a cross-multi-stage manner with the gas distributor; the sprayer is connected to the filtration and cleaning section, and the gas distributor is connected to the gas lift pipe; a multi-stage foaming net is installed at the bottom of the spray-foaming section, and the liquid outlet is installed on one side of the bottom of the spray-foaming section;

[0015] The flue gas defoaming section includes a foam sensor, a multi-band ultrasonic generator, and a defoaming device; the multi-band ultrasonic generator and the foam sensor are installed at the bottom of each stage of the foaming net; a defoaming device is provided on one side of the flue gas defoaming section, and the flue gas is discharged after being treated by the defoaming device;

[0016] The desorption section includes a tray, a rich liquid inlet valve, a steam inlet valve, a reboiler, a steam heat pipe, a steam outlet valve, a tubular distributor, and a second gas lift pipe. The rich liquid outlet valve is connected to a rich liquid delivery pipeline that is connected to the top of the desorption section. A tubular distributor is provided at the end of the rich liquid delivery pipeline, and the rich liquid flows through the tray. The reboiler is equipped with a second gas lift pipe. Steam enters the interior of each tray through the second gas lift pipe, and the steam after heat exchange is circulated back to the reboiler through the steam heat pipe.

[0017] The waste heat recovery section includes a CO2 heat pipe, a heat exchanger, a CO2 outlet valve, a lean liquid outlet valve, a heat exchanger, a switching valve, and a CO2 storage device. One end of the CO2 heat pipe is connected to the desorption section, and the other end is connected to the CO2 storage device. The CO2 heat pipe exchanges heat with the rich liquid delivery pipeline via the heat exchanger. The lean liquid outlet valve is located at the bottom of the desorption section and is connected to the lean liquid delivery pipeline. It also exchanges heat with the rich liquid delivery pipeline via the heat exchanger. The other end of the lean liquid delivery pipeline is connected to the storage tank.

[0018] Furthermore, the flue gas filter adopts a multi-stage filtration structure, including a first-stage cyclone separator, a second-stage metal fiber filter, and a third-stage molecular sieve adsorption-desorption device installed in sequence.

[0019] Furthermore, the filter is a wedge-shaped wire structure filter.

[0020] Furthermore, the multi-level foamed net is divided into three levels of structure, wherein the first-level foamed net adopts a honeycomb directional pore structure, the second-level foamed net adopts a multi-level pore gradient structure, and the third-level foamed net also adopts a multi-level pore gradient structure.

[0021] The magnetic field distributor is installed on both sides of the primary foaming net to induce the foaming agent to oriented and form pore channels perpendicular to the gas flow direction.

[0022] Furthermore, the desorption section is coupled with photocatalytic assisted desorption, and a light source is installed below the tubular distributor and the tray; the tray is provided with multiple isolation plates, and the porous support is located on the isolation plates for loading the catalyst.

[0023] Furthermore, an overflow weir and a downcomer are installed at the free end of the tray. When the rich liquid level is higher than the overflow weir, the rich liquid flows into the next tray along the downcomer.

[0024] Furthermore, the heat exchanger includes a rich liquid channel and a CO2 channel for heat exchange between the rich liquid and CO2.

[0025] Furthermore, the spray-foaming section also includes a turbulence generator, which is mounted on a multi-band ultrasonic generator to enhance the ultrasonic wave propagation efficiency of the multi-band ultrasonic generator.

[0026] Furthermore, the waste heat recovery section also includes a smart sensor and a microfluidic regulating valve. The smart sensor is used to monitor operating parameters in real time and control the valve opening. The microfluidic regulating valve is used to dynamically adjust the fluid flow distribution to achieve closed-loop control of heat exchange efficiency.

[0027] Another object of the present invention is to provide an absorbent, wherein the absorbent is a MEA-PZ-AEO-9 absorbent, the components of which include MEA, PZ, deionized water and AEO-9, and the mass percentages of each component are as follows: deionized water 70%, AEO-9 0.1%~0.5%, PZ 5.9%~14.95%, and MEA 14.75%~23.92%.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) The absorption section of this invention adopts a multi-stage spray layer, which is distributed in a cross-stage manner with the gas distributor, so that the droplets in the spray-foaming section are in uniform contact with the gas, enhancing the absorption performance, optimizing the nozzle arrangement and spray parameters, improving the spray uniformity of the cross section of the absorption tower, and improving the gas-liquid mass transfer effect; at the same time, through the synergistic effect of the atomizing nozzle and the foaming net, the gas-liquid contact area is significantly increased, improving the CO2 absorption efficiency. Compared with traditional absorbents, the absorption efficiency is as high as 92.91%;

[0030] (2) A wedge wire structure filter is used to filter impurities and prevent blockage of the absorption tower. An automatic cleaning device is also provided to clean the filter.

[0031] (3) The primary foaming net adopts a honeycomb directional pore structure, combined with a magnetic field emitter, and the foaming agent is oriented to form a pore channel perpendicular to the gas flow direction through magnetic field, which shortens the diffusion path. During the foaming process, a gradient electric field is applied to make the pores grow directionally along the electric field direction, so as to achieve uniform gas-liquid contact.

[0032] (4) Multi-stage defoaming treatment is adopted. First, defoaming pretreatment is carried out by combining foam sensor and multi-frequency ultrasonic wave. Then, defoaming treatment is carried out by coupling physical and chemical methods through defoaming device to achieve efficient defoaming effect.

[0033] (5) A multi-stage waste heat recovery device is adopted. The waste heat of desorbed CO2 is used to perform primary heating pretreatment on the rich liquid entering the desorption tower. Then, the desorbed lean liquid is used to perform secondary heating pretreatment on the rich liquid entering the desorption tower. At the same time, the steam after heating is completed is recovered to achieve high efficiency and energy saving.

[0034] (6) In order to solve the problems of incomplete desorption of rich liquid and high regeneration energy consumption in traditional desorption towers, the desorption section adopts a tray structure combined with gradient gas distribution to make the desorption temperature uniform, reduce heat loss of the tower body, improve desorption efficiency, avoid the phenomenon of incomplete desorption, and perform desorption treatment by uniformly heating the rich liquid with steam.

[0035] (7) Photocatalytic assisted desorption system: an ultraviolet LED light source and a porous carrier loaded with catalyst are set below the tray and distributor to accelerate the release of CO2 in the rich liquid while reducing regeneration energy consumption;

[0036] (8) In order to reduce the corrosion of the tower body and its equipment by the absorbent, a new absorbent MEA-PZ-AEO-9 is proposed. MEA is used as the absorbent, PZ is used as the corrosion inhibitor and AEO-9 is used as the surfactant. Compared with the traditional absorbent, the inhibition efficiency is as high as 31%, which can significantly reduce the corrosion of the tower body and packing, and at the same time improve the CO2 capture performance.

[0037] (9) In the waste heat recovery section, the rich liquid is preheated in two stages through CO2 heat pipe, steam heat pipe and heat exchanger to fully recover the waste heat of desorbed CO2 gas and lean liquid, so as to realize the efficient reuse of energy.

[0038] The accompanying drawings and brief descriptions thereof.

[0039] Figure 1 This is a schematic diagram of the absorption-desorption CO2 capture system of Embodiment 1 of the present invention;

[0040] Figure 2 This is a schematic diagram of the defoaming device structure in Embodiment 1 of the present invention;

[0041] Figure 3 This is a schematic diagram of the liquid distributor according to Embodiment 1 of the present invention;

[0042] Figure 4 This is a schematic diagram of the gas distributor according to Embodiment 1 of the present invention;

[0043] Figure 5 This is a schematic diagram of the structure of the flue gas filter according to Embodiment 1 of the present invention;

[0044] Figure 6 This is a schematic diagram of the structure of the heat exchanger in Embodiment 1 of the present invention;

[0045] Figure 7 This is a schematic diagram comparing the corrosion rate of the absorbent in Example 2 of the present invention with that of a conventional MEA absorbent.

[0046] Figure 8 This is a schematic diagram comparing the absorption rates of the absorbent in Example 2 of the present invention with those of a traditional MEA absorbent, where the absorption rate refers to the amount of CO2 absorbed per unit time.

[0047] Figure 9 This is a schematic diagram comparing the absorption efficiency of the absorbent in Example 2 of the present invention with that of a traditional MEA absorbent, where the absorption efficiency refers to the CO2 removal efficiency per unit time.

[0048] Figure 10 This is a schematic diagram comparing the maximum absorption efficiency of the absorbent in Example 2 of the present invention with that of a conventional MEA absorbent;

[0049] Figure 11 This is a schematic diagram comparing the absorption capacity of the absorbent in Example 2 of the present invention with that of a conventional MEA absorbent over time.

[0050] Figure 12 This is a schematic diagram comparing the absorption load of the absorbent in Example 2 of the present invention with that of a conventional MEA absorbent;

[0051] Among them, 1-waste liquid tank; 2-drain valve; 3-pressure sensor one; 4-pressure sensor two; 5-wedge wire structure filter; 6-gas lifting pipe one; 7-sprayer; 8-automatic backwash valve; 9-gas distributor; 10-magnetic field distributor; 11-primary foaming net; 12-secondary foaming net; 13-Three-stage foaming net; 14-Foam sensor; 15-Multi-band ultrasonic generator; 16-Defoaming device; 17-Flue gas outlet valve; 18-Liquid outlet; 19-Liquid distributor; 20-Packaging; 21-Pressure sensor three; 22-Pressure sensor four; 23-Flue gas filter; 24-Pulse backflushing device; 25-Storage tank; 26-Rich liquid outlet valve; 27-Lean liquid inlet valve; 28-On / off valve; 29-Pump; 30-CO2 storage device; 31-Heat exchanger; 31-1: Rich liquid channel; 31-2: CO2 channel; 32-Plate-fin heat exchanger; 33-CO2 outlet valve; 34-Steam outlet valve; 35-Steam heat pipe; 36-Steam 37-Steam inlet valve; 38-Reboiler; 39-Lean liquid outlet valve; 40-Rich liquid inlet valve; 41-Tube distributor; 42-UV LED lamp; 43-Isolation plate; 44-Overflow weir; 45-Downflow plate; 46-Intelligent controller; 47-Filter cleaning section; 48-Spray-foaming section; 49-Packing section; 50-Flue gas pretreatment section; 51-Waste heat recovery section; 52-Storage section; 53-Desorption section; 54-Flue gas defoaming section; 55-Turbulence generator; 56-Liquid riser pipe; 57-Train tray; 58-Gas riser pipe II; 59-CO2 heat pipe; 60-Intelligent sensor; 61-Microfluidic regulating valve; 62-Switch valve I; 63-Switch valve II. Detailed Implementation

[0052] 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.

[0053] For experiments not specifically described in the examples, conventional experimental procedures or conditions as described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0054] Example 1

[0055] like Figure 1 As shown, a CO2 capture and desorption system integrating multi-stage spray cross-distribution and waste heat cascade recovery optimization is presented. The system consists of an absorption tower and a desorption tower. The absorption tower includes a flue gas pretreatment section 49, a filtration and cleaning section 46, a spray-foaming section 47, a flue gas defoaming section 53, a packing section 48, and a liquid storage section 51; the desorption tower includes a desorption section 52 and a waste heat recovery section 50. Wherein:

[0056] The flue gas pretreatment section 49 includes pressure sensor 3 21, pressure sensor 4 22, flue gas filter 23, pulse backflushing device 24, and intelligent controller 45. Pressure sensor 3 21 and pressure sensor 4 22 are installed at the inlet and outlet of flue gas filter 23, respectively. The flue gas first passes through flue gas filter 23 for pretreatment. Flue gas filter 23 adopts a three-stage synergistic filtration structure. The first-stage cyclone separator removes large particles, reducing the load on subsequent filtration. The second-stage metal fiber filter achieves high-efficiency interception by adjusting the pore size. The third-stage molecular sieve adsorption-desorption device adsorbs volatile organic compounds (VOCs), dioxins, and other trace pollutants, achieving a highly efficient pretreatment filtration effect. To prevent filter clogging, a pulse backflushing device 24 is installed at the outlet of flue gas filter 23. The filter element is backflushed periodically by the pulse backflushing device 24 to reduce particulate matter adhesion. The intelligent controller is installed on the outside of the flue gas filter and is used to control and monitor data. The intelligent controller is embedded with a blockchain chip to monitor and record key parameters of the device (such as filtration efficiency and energy consumption) and upload them to the cloud, realizing full life-cycle data traceability. After pretreatment, the flue gas flows upward sequentially through the packing section and the spray-foaming section.

[0057] The packing section 48 includes a gas riser pipe 6, a liquid distributor 19, packing material 20, and a rich liquid outlet valve 26. One end of the gas riser pipe 6 is connected to the packing section, and the other end is installed inside the absorption tower. A gas distributor 9 is installed at the outlet end. The flue gas undergoes primary absorption in the packing section, and then enters the absorption tower from the top through the gas riser pipe 6 for secondary absorption. The absorbed rich liquid flows out from the outlet into the packing material 20, passes through the liquid distributor 19, flows through the packing material, and finally flows out from the rich liquid outlet valve.

[0058] The packing materials include corrugated plate structured packing, plastic structured packing, and some ceramic bulk packing, with stainless steel structured packing being the preferred material. The packing's function is to increase the specific surface area, providing more contact interfaces for gas and liquid, thereby improving mass transfer efficiency. Its rational structure helps improve fluid distribution, prevent short-circuiting and channeling, reduce system pressure drop, and decrease energy consumption. Simultaneously, it enhances gas absorption and desorption rates, particularly excelling in CO2 capture, and provides stable support for internal tower components, improving overall operational reliability. The absorbent is transported from the storage tank to the filtration and cleaning section via a liquid riser pipe, then enters the spray-foaming section. After capture and absorption, the liquid (absorbent) enters the packing section from the outlet, and is then transported to the desorption section.

[0059] The filtration and cleaning section 46 includes a wedge wire structure filter 5, pressure sensor 3, pressure sensor 4, automatic backwash valve 8, drain valve 2, and waste liquid tank 1. The wedge wire structure filter 5 is located at the top of the absorption tower and is used to pre-treat the absorbent before it enters the tower, preventing blockage. Combined with pressure sensors 3 and 4 installed at the top and bottom of the filter 5 respectively, the pressure difference is monitored in real time. When the pressure difference reaches a set value, it indicates that the filter screen is blocked. The automatic backwash valve 8 is opened, the switch valve 62 is closed, and the drain valve 2 is opened to clean the wedge wire structure filter 5. The cleaned waste liquid is then discharged into the waste liquid tank 1.

[0060] The spray-foaming section 47 includes a sprayer 7, a gas distributor 9, a primary foaming net 11, a secondary foaming net 12, a tertiary foaming net 13, a liquid outlet 18, and a magnetic field distributor 10. The sprayer 7 consists of multiple nozzles, distributed in a multi-level, intersecting pattern with the gas distributor 9, ensuring more thorough contact between the flue gas and the absorbent, thus improving the absorbent's capture performance. The magnetic field distributor 10 is installed on both sides of the primary foaming net to induce the foaming agent to oriented, forming pore channels perpendicular to the gas flow direction, shortening the diffusion path, and causing the pores to grow directionally along the electric field direction, achieving uniform gas-liquid contact. The foaming net has a multi-level structure, divided into three levels: primary, secondary, and tertiary. The primary foaming net uses a honeycomb-type oriented pore structure, the secondary foaming net uses a multi-level pore gradient structure, and the tertiary foaming net also adopts a multi-level pore gradient structure. This multi-level distributed structure is beneficial for foaming, thereby increasing the contact area between CO2 and the absorbent and improving absorption efficiency.

[0061] The flue gas defoaming section 53 includes a foam sensor 14, a multi-band ultrasonic generator 15, a turbulence generator 54, a defoaming device 16, and a flue gas outlet valve 17. The multi-band ultrasonic generator 15, turbulence generator 54, and foam sensor 14 are installed in the middle section between the upper and lower foaming nets. The multi-band ultrasonic generator 15 and turbulence generator 54 are installed on one side, and the foam sensor 14 is installed on the other side. They monitor the foam size and characteristics in real time, establishing a correlation model between foam generation and operating parameters. When the foam is too large or excessive, the multi-band ultrasonic generator is activated, and the ultrasonic power and frequency are automatically adjusted in conjunction with the multi-band ultrasonic generator 15 to achieve preliminary defoaming treatment. Simultaneously, the turbulence generator 54 enhances the ultrasonic propagation efficiency of the multi-band ultrasonic generator 15, reducing energy consumption per unit of defoaming volume. The cleaned flue gas is then defoamed using defoaming device 16. This device employs a physical-chemical coupling method. A biomimetic fish gill structure defoamer serves as the primary defoamer, mimicking the layered structure of fish gills to create a defoaming membrane with microchannels. This achieves mechanical trapping of foam and fluid shearing. A superhydrophilic coating is introduced onto the membrane surface to prevent membrane fouling and extend its service life. A chemical defoamer serves as the secondary defoamer, using two layers of defoamer particles with density differences. Through temperature response, the defoamer is released in a gradient, balancing rapid defoaming with sustained suppression for highly efficient defoaming. The cleaned flue gas, after defoaming treatment, is discharged through the flue gas outlet valve.

[0062] The storage section 51 includes a storage tank 25, a pump 29, a liquid riser pipe 55, a switch valve 28, and a lean liquid inlet valve 27. The liquid riser pipe 55 has two sections: one end connects from the bottom of the storage tank 25 to the automatic backwash valve 8 in the automatic backwashing device at the bottom of the filtration and cleaning section; the other end connects from the bottom of the storage tank 25 to the top of the filtration and cleaning section. The automatic backwashing device includes the automatic backwash valve 8 installed at the bottom of the filtration and cleaning section and the switch valve 62 installed at the top of the filtration and cleaning section. The valve 8 at the bottom of the filtration and cleaning section is used to flush the wedge wire structure filter 5, while the switch valve 62 at the top is closed during flushing to prevent backflow. The valve 62 at the top of the filtration and cleaning section is used to pre-treat the fresh amine solution for impurities before it is introduced into the absorption tower. The fresh amine solution is stored in the storage tank 25 and, with the flow rate controlled by the pump, enters the absorption tower through the liquid riser pipe 55. A lean liquid inlet valve 27 is also provided, through which the rich solution, after desorption treatment, becomes lean liquid and enters the storage tank 25, forming a complete circulation system.

[0063] The desorption section 52 includes trays 56, a rich liquor inlet valve 39, a steam inlet valve 36, a reboiler 37, a steam heat pipe 35, a steam outlet valve 34, an ultraviolet LED lamp 41, an overflow weir 43, a downcomer 44, a baffle plate 42, a tubular distributor 40, and a gas lift pipe 57. The rich liquor enters the desorption tower after being preheated twice by the heat exchanger 31 and the plate-fin heat exchanger 32. The flow rate is regulated by the rich liquor inlet valve 39, and the liquor flows through the tubular distributor 40. Then, the rich liquor passes through trays 56. When the rich liquor level is higher than the overflow weir 43, it flows down the downcomer into the next tray 56. Steam flows from inside trays 56 through the steam inlet valve 36, heating the rich liquor for desorption. A stepped distribution is used to avoid temperature differences in the steam, which could lead to incomplete desorption. The steam after heat exchange is then output through the steam outlet valve 34 and circulated back to the reboiler 37 via the steam heat pipe 35.

[0064] Simultaneously, photocatalytic-assisted desorption is coupled to accelerate rich-liquid desorption and save energy. Ultraviolet LEDs are installed below the tubular distributor and tray 56 to provide a light source for the catalyst, while the porous support is located on the separator plate to load the catalyst and assist in rich-liquid desorption.

[0065] The waste heat recovery section 50 includes a CO2 heat pipe 58, a heat exchanger 31, a CO2 outlet valve 33, a lean liquor outlet valve 38, a smart sensor 59, a microfluidic regulating valve 60, a plate-fin heat exchanger 32, a switch valve 61, and a CO2 storage device 30. The heat exchanger 31 includes a rich liquor channel 31-1 and a CO2 channel 31-2. The CO2 generated by desorption has a certain temperature and enters the heat exchanger 31 through the CO2 outlet valve to preheat the rich liquor before it enters the desorption tower. Simultaneously, a smart sensor monitors operating parameters in real time, and the valve opening is controlled based on a PID algorithm. Combined with the microfluidic regulating valve, the fluid flow distribution is dynamically adjusted to achieve closed-loop control of heat exchange efficiency, realizing the first-stage heating pretreatment of the rich liquor. Additionally, opening the switch valve 61 stores the CO2 in the CO2 storage device 30. The rich liquor that has been desorbed and becomes lean liquor has a certain residual heat. This residual heat is recovered by using a plate-fin heat exchanger 32 to perform secondary heating pretreatment on the rich liquor that is about to enter the desorption tower. Then, the liquor flows into the storage tank 25. The lean liquor inlet valve 27 regulates the flow rate of the lean liquor, thereby achieving efficient utilization of residual heat and energy saving.

[0066] Example 2

[0067] Example 1 describes a CO2 capture and desorption system that integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization. An absorbent is added to the amine solution stored in the storage tank 25. The absorbent is a novel MEA-PZ-AEO-9 absorbent, with MEA as the amine absorbent, PZ as the corrosion inhibitor, and AEO-9 as the surfactant. The total content of the absorbent solution is 50.05g, with MEA content of 12g, PZ content of 3g, deionized water of 35g, and AEO-9 content of 0.05g.

[0068] like Figures 7-12 As shown, the novel MEA-PZ-AEO-9 absorbent provided in this embodiment, compared with the traditional MEA absorbent, can reduce corrosion of the tower body and packing, while improving CO2 capture performance, with an absorption efficiency of up to 92.91%, and improving the absorption capacity and absorption load performance of the absorbent.

[0069] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A CO2 capture and desorption process that integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization, characterized in that, A CO2 capture and desorption system optimized by multi-stage spray cross-distribution and waste heat cascade recovery is adopted. The system includes an absorption tower and a desorption tower. The absorption tower includes a flue gas pretreatment section, a filtration and cleaning section, a spray-foaming section, a flue gas defoaming section, a packing section, and a liquid storage section. The desorption tower includes a desorption section and a waste heat recovery section. The packing section includes a gas lift-up pipe, a liquid distributor, packing, and a rich liquid outlet valve; the liquid distributor is installed at the top of the packing section, the packing is installed below the liquid distributor, and the bottom of the packing section is connected to the desorption tower through a rich liquid delivery pipeline; the inlet end of the gas lift-up pipe is connected to the top of the packing section, and the outlet end extends into the interior of the spray-foaming section. The liquid storage section includes a liquid storage tank, a pump, a liquid lift-up pipe, a switch valve, and a lean liquid inlet valve; the liquid storage tank is used to store absorbent, and a switch valve is provided at the bottom of the liquid storage tank. The switch valve is connected to two liquid lift-up pipes through the pump. The absorbent is a MEA-PZ-AEO-9 absorbent, which consists of MEA, PZ, deionized water and AEO-9. The mass percentages of each component are as follows: deionized water 70%, AEO-9 0.1%~0.5%, PZ 5.9%~14.95%, and MEA 14.75%~23.92%. The spray-foaming section includes a sprayer, a gas distributor, a multi-stage foaming net, and a liquid outlet; the sprayer consists of multiple nozzles, which are distributed in a cross-multi-stage manner with the gas distributor; the sprayer is connected to the filtration and cleaning section, and the gas distributor is connected to the gas lift pipe; a multi-stage foaming net is installed at the bottom of the spray-foaming section, and the liquid outlet is installed on one side of the bottom of the spray-foaming section; The flue gas defoaming section includes a foam sensor, a multi-band ultrasonic generator, and a defoaming device; the multi-band ultrasonic generator and the foam sensor are installed at the bottom of each stage of the foaming net; a defoaming device is provided on one side of the flue gas defoaming section, and the flue gas is discharged after being treated by the defoaming device; The desorption section includes a tray, a rich liquid inlet valve, a steam inlet valve, a reboiler, a steam heat pipe, a steam outlet valve, a tubular distributor, and a second gas lift pipe. The rich liquid outlet valve is connected to a rich liquid delivery pipeline that is connected to the top of the desorption section. A tubular distributor is provided at the end of the rich liquid delivery pipeline, and the rich liquid flows through the tray. The reboiler is equipped with a second gas lift pipe. Steam enters the interior of each tray through the second gas lift pipe, and the steam after heat exchange is circulated back to the reboiler through the steam heat pipe. The multi-level foamed net is divided into three levels of structure. The first level of foamed net adopts a honeycomb directional pore structure, the second level of foamed net adopts a multi-level pore gradient structure, and the third level of foamed net also adopts a multi-level pore gradient structure. The magnetic field distributor is installed on both sides of the primary foaming net to induce the foaming agent to oriented and form pore channels perpendicular to the gas flow direction; The spray-foaming section also includes a turbulence generator, which is installed on a multi-band ultrasonic generator to enhance the ultrasonic wave propagation efficiency of the multi-band ultrasonic generator.

2. The CO2 capture and desorption process optimized by multi-stage spray cross-distribution and waste heat cascade recovery according to claim 1, characterized in that, The waste heat recovery section includes a CO2 heat pipe, a heat exchanger, a CO2 outlet valve, a lean liquid outlet valve, a heat exchanger, a switching valve, and a CO2 storage device. One end of the CO2 heat pipe is connected to the desorption section, and the other end is connected to the CO2 storage device. The CO2 heat pipe exchanges heat with the rich liquid delivery pipeline via the heat exchanger. The lean liquid outlet valve is located at the bottom of the desorption section and is connected to the lean liquid delivery pipeline. It also exchanges heat with the rich liquid delivery pipeline via the heat exchanger. The other end of the lean liquid delivery pipeline is connected to the storage tank. The waste heat recovery section also includes intelligent sensors and microfluidic regulating valves. The intelligent sensors are used to monitor operating parameters in real time and control the valve opening. The microfluidic regulating valves are used to dynamically adjust the fluid flow distribution to achieve closed-loop control of heat exchange efficiency. The flue gas pretreatment section includes a pressure sensor, a flue gas filter, and a pulse backflushing device; the flue gas filter is equipped with a pressure sensor at both the inlet and outlet ends, and the outlet end is equipped with the pulse backflushing device, and the outlet end is connected to the bottom of the packing section. The filtration and cleaning section includes a filter, a pressure sensor, an automatic backwash valve, and a waste liquid tank. The filter is located at the top of the absorption tower, and its top is connected to the bottom of the storage tank via a liquid lift pipe for conveying. An automatic backwash valve is provided at the bottom of the filter, and the automatic backwash valve is connected to the bottom of the storage tank via another liquid lift pipe for backwashing. A waste liquid tank is connected to the top of the filter.

3. The CO2 capture and desorption process optimized by multi-stage spray cross-distribution and waste heat cascade recovery according to claim 2, characterized in that, The flue gas filter adopts a multi-stage filtration structure, including a first-stage cyclone separator, a second-stage metal fiber filter, and a third-stage molecular sieve adsorption-desorption device installed in sequence.

4. The CO2 capture and desorption process optimized by multi-stage spray cross-distribution and waste heat cascade recovery according to claim 2, characterized in that, The filter is a wedge-shaped wire structure filter.

5. The CO2 capture and desorption process according to claim 2, which integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization, is characterized in that... The desorption section is coupled with photocatalytic assisted desorption, and a light source is installed below the tubular distributor and the tray; multiple isolation plates are provided on the tray, and a porous support is located on the isolation plates for loading the catalyst.

6. The CO2 capture and desorption process according to claim 5, which integrates multi-stage spray cross-distribution and waste heat cascade recovery optimization, is characterized in that... The free end of the tray is equipped with an overflow weir and a downcomer. When the rich liquid level is higher than the overflow weir, the rich liquid flows into the next tray along the downcomer.

7. The CO2 capture and desorption process optimized by multi-stage spray cross-distribution and waste heat cascade recovery according to claim 2, characterized in that, The heat exchanger includes a rich liquid channel and a CO2 channel for heat exchange between the rich liquid and CO2.

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