An atomization-foaming-filler integrated flue gas CO2 capture system

Abstract

The present invention discloses an atomization-foaming-filler integrated flue gas CO2 capture system, including a CO2 absorption system located in an absorption tower and a foam separation system located in a gas-liquid separation tower. The CO2 absorption system includes an atomization unit, a droplet recovery device, a foaming unit and a filler unit. The atomization unit includes a nozzle, a pump and a gas distributor. The pump cooperates with the nozzle to spray absorption liquid, and the gas distributor provides CO2 gas for preliminary absorption in the atomization area; the foaming unit includes a multi-layer foaming net to foam the absorption liquid, so as to facilitate the lower-level filler to reabsorb CO2. The foam separation unit includes an ultrasonic defoamer, a cyclone separator and a wire mesh demister. The ultrasonic separator includes four annularly evenly distributed ultrasonic generators. The cyclone separator is a spiral blade structure, and a spiral guide groove is provided along its outer edge, and a downcomer is provided below the guide groove. The wire mesh demister is located at the upper level of the cyclone separator. This system can efficiently capture CO2 and completely separate gas and liquid.

Description

Technical Field

[0001] The present invention relates to the technical field of CO2 capture, and in particular to an atomization-foaming-filler integrated flue gas CO2 capture system. Background Art

[0002] CO2 capture and storage (CCS) technology can effectively mitigate CO2 emissions. Among the many carbon capture technologies, the chemical absorption method based on amine liquid has the advantages of high separation purity, high capture rate and wide application range. It is currently the flue gas CO2 capture method with the most commercial development prospects. This technology is based on the principle of gas-liquid mass transfer. Through the absorption and dissociation of amine-based substances and CO2 in flue gas, CO2 is first absorbed in the absorption tower, and then the absorbent is decarbonized and regenerated, thereby purifying CO2 in the flue gas.

[0003] Traditional absorption towers are mainly packed towers. The absorbent flows down from the top by spraying and countercurrently contacts the flue gas entering from the bottom of the tower to react with it. The disadvantages of traditional packed towers are that the absorption rate of amine liquid for CO2 is low due to the short contact time between the gas and liquid phases and the small gas-liquid reaction area.

[0004] Traditional absorption towers also include spray towers, which are also used as CO2 absorption reactors due to their simple structure, higher capacity, and lower gas-side pressure drop. They do not contain internal fillers, so they are highly corrosion-resistant and can use high-concentration MEA solutions. Since the spray tower atomizes the absorbent into tiny droplets through a nozzle, the gas-liquid contact area is greatly increased, thereby promoting the absorption of CO2. The disadvantage of traditional spray towers is that the solvent utilization rate is insufficient due to uneven droplet size and wall flow phenomenon, resulting in low CO2 absorption efficiency. Summary of the invention

[0005] In order to overcome the defects in the prior art, the present invention provides an atomization-foaming-filler integrated flue gas CO2 capture system, which can increase the contact area between CO2 and absorbent, thereby improving the CO2 absorption efficiency and absorption rate.

[0006] The technical solution adopted by the present invention is: an atomization-foaming-filler integrated flue gas CO2 capture system, including a CO2 absorption system and a foam separation system;

[0007] The CO2 absorption system is located in the absorption tower, and the foam separation system is located in the gas-liquid separation tower; the absorption tower and the gas-liquid separation tower are connected through a gas pipeline, and the bottoms of the absorption tower and the gas-liquid separation tower are both connected to a liquid storage tank;

[0008] The CO2 absorption system comprises a CO2 atomization unit, a foaming unit and a packing unit arranged in sequence from top to bottom in the absorption tower, wherein the CO2 atomization unit comprises a pump, a nozzle and a gas distributor; the pump is used to cooperate with the nozzle to spray the absorption liquid, and the gas distributor is used to provide CO2 gas and contact the sprayed liquid droplets;

[0009] The foaming unit is composed of a multi-layer foaming net and is used to convert the absorption droplets into foam;

[0010] The CO2 absorption system also includes a droplet recovery device, which is located at the bottom of the CO2 atomization unit. The droplet recovery device is an annular body fixed to the inner wall of the absorption tower. The annular body is provided with an inwardly inclined drainage surface to guide the absorption liquid on the tower wall of the absorption tower in the atomization zone into the foaming unit;

[0011] The foam separation system includes an ultrasonic defoamer and a cyclone separator which are arranged in sequence from bottom to top in a gas-liquid separation tower, wherein the top of the gas-liquid separation tower is a gas outlet and the bottom is an absorption liquid outlet; a plurality of ultrasonic generators are evenly distributed along a ring in the ultrasonic defoamer to cause foam rupture; the cyclone separator is a spiral blade which is fixedly connected to the inner wall of the gas-liquid separation tower, a spiral guide groove is provided on the outer edge of the spiral blade, the bottom of the guide groove is connected to the downcomer, and the absorption liquid is discharged from the absorption liquid outlet into the liquid storage tank.

[0012] As a further improvement of the present invention, the foaming unit includes a top foaming net, a middle foaming net and a bottom foaming net arranged from top to bottom, the three foaming nets are all three-dimensional network structures, and the pore density of the three foaming nets increases from top to bottom.

[0013] As a further improvement of the present invention, the cyclone separator includes a primary cyclone separator and a secondary cyclone separator which are arranged in sequence from bottom to top.

[0014] As a further improvement of the present invention, the foam separation system further comprises a wire mesh demister, wherein the wire mesh demister is located between the secondary cyclone separator and the gas outlet at the top of the tower.

[0015] The beneficial effects of the present invention are:

[0016] (1) During the spraying process of the nozzle, the spray tower will produce wall flow. The liquid flowing along the wall cannot pass through the foaming net to form bubbles, resulting in liquid waste and affecting the absorption efficiency. The present invention sets a droplet recovery device on the wall of the spray tower, extending along the horizontal direction of the tower body and tilting downward. The device realizes efficient recovery and utilization of droplets through the synergistic effect of the protruding structure and the contact-type guide structure. The design of these structures not only reduces the loss of absorbent, but also improves the operating efficiency of the entire system, while reducing environmental impact;

[0017] (2) The foaming structure adopts a multi-layered three-dimensional structure. From the top layer to the bottom layer, the density and pore size of each layer are different to adapt to different flow rates and liquid characteristics. The top layer has a lower density and is used to initially evenly distribute the liquid. The density of the middle layer gradually increases to form a stable liquid film between the pores of the screen. The bottom layer has the highest density and is used to collect and discharge the bubbles formed by the liquid film being swept by the incoming flow. This gradient design allows each layer to adjust its performance according to the characteristics of the fluid (such as flow rate, pressure, and viscosity of the liquid);

[0018] (3) The present invention adopts a foam flow mode (rather than a liquid film flow mode) in the packing unit, which can significantly increase the gas-liquid contact area; the three-dimensional structure of the foaming net introduces more micro-turbulence, improves the mass transfer efficiency, and the foam flow reduces the problems of uneven liquid film thickness and uneven flow, thereby improving the uniformity of gas-liquid contact;

[0019] (4) The gas outlet of the absorption tower is prone to entrained foam. The present invention adopts a foam separation system, and installs an ultrasonic defoamer, a multi-stage cyclone separator and a wire mesh demister in sequence at the gas outlet. The multi-stage cyclone separator converts the high-speed airflow in the absorption tower into a pressure cyclone, and uses centrifugal force to break up the entrained foam and throw it to the periphery, thereby effectively reducing the volume of foam entrained at the gas outlet. Each stage of the multi-stage cyclone separation device can increase the rotation speed of the airflow and gradually reduce the foam content in the airflow.

[0020] (5) A spiral guide groove is set in the cyclone separator to collect the liquid separated from the gas and liquid under centrifugal force. A downcomer is set at the lowest point of the groove, which is connected to the next-stage cyclone separation device. The structure of the guide groove simplifies the liquid discharge process, allowing the liquid to be discharged from the system more smoothly, reducing the retention time of the liquid in the separator, thereby improving the processing capacity and stability of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] Figure 1 It is a structural schematic diagram of the atomization-foaming-filler integrated CO2 capture system of the present invention;

[0023] Figure 2 It is a schematic structural diagram of a droplet recovery device of the present invention;

[0024] Figure 3 It is a schematic diagram of the three-dimensional network structure of the foaming net of the foaming unit of the present invention;

[0025] Figure 4 It is a schematic diagram of the ultrasonic defoaming structure of the present invention;

[0026] Figure 5It is a schematic structural diagram of a cyclone separator of the present invention;

[0027] Figure 6 It is a schematic diagram of the structure of the spiral guide groove in the cyclone separator of the present invention;

[0028] In the figure, 1-pump; 2-nozzle; 3-gas distributor; 4-droplet recovery device; 4-1-cylinder; 4-2-annular drainage surface; 5-top foaming net; 6-middle foaming net; 7-bottom foaming net; 8-filler; 9-air pipe; 10-liquid outlet; 11-liquid storage tank; 12-liquid reflux port; 13-ultrasonic defoamer; 13-1-annular fixing frame, 13-2-ultrasonic generator; 14-first-stage cyclone separator; 14-1-spiral blade; 14-2-guiding groove; 15-downcomer; 16-second-stage cyclone separator; 17-wire mesh demister; 18-gas outlet;

[0029] a-absorption tower, b-gas-liquid separation tower. DETAILED DESCRIPTION

[0030] like Figure 1 As shown, an atomization-foaming-filling integrated flue gas CO2 capture system includes a CO2 absorption system and a foam separation system, wherein the CO2 absorption system is arranged in the absorption tower a, and the foam separation system is arranged in the gas-liquid separation tower b. A gas channel, i.e., a gas pipe 9, is arranged between the two towers. The CO2 absorption system includes an atomization unit, a foaming unit and a filler unit, wherein the atomization unit is located in the absorption zone of the absorption tower a, the foaming unit is located in the foaming zone of the absorption tower a, and the filler unit is located in the filler zone of the absorption tower a. The foam separation system includes an ultrasonic defoamer 13, a cyclone separator and a wire mesh demister 17. The processes of CO2 absorption in the absorption tower a are droplet absorption in the spray zone, bubble absorption in the foaming zone, and liquid film absorption in the filler zone.

[0031] Specifically, in the CO2 absorption system, the atomization unit includes a pump 1, a nozzle 2 and a gas distributor 3, wherein the pump 1 is used to cooperate with the nozzle 2 to forcefully spray the CO2 absorption liquid, which is an amine liquid. The gas distributor 3 is used to provide a mixture of CO2 gas and air. The gas distributor 3 outputs air and CO2 gas, which contact with the small droplets of the absorption liquid sprayed from the nozzle 2 for preliminary absorption. The concentration of air and CO2 gas is proportioned by a flow meter.

[0032] like Figure 2 As shown, a droplet recovery device 4 is provided between the atomizing unit and the foaming unit. The droplet recovery device 4 is an annular body, including a cylinder 4-1 and an annular drainage surface 4-2 installed in the middle of the inner side of the cylinder. The annular drainage surface 4-2 is inclined inward.

[0033] The liquid droplets on the wall of the absorption tower where the atomization unit is located are drained to the middle of the annular body to prevent them from continuing to flow along the tower wall. The drained liquid droplets enter the foaming unit of the next level to prevent them from corroding the tower wall.

[0034] like Figure 3 As shown, the foaming unit is located below the atomizing unit and is a multi-layer structure, specifically including a top foaming net 5, a middle foaming net 6 and a bottom foaming net 7. The three foaming nets are all three-dimensional structures, and the pore density in the three foaming nets increases step by step from top to bottom, which can form smaller foams from large to small, so that each layer can adjust its performance according to the characteristics of the fluid (such as flow rate, pressure and viscosity of the liquid).

[0035] The packing unit is located below the foaming unit and includes a packing 8. The absorbent continues to absorb the CO2 that has not fully reacted in the atomization and foaming units through the flow of liquid film on the packing.

[0036] In the foaming unit, the foaming unit emits microbubbles, which can increase the gas-liquid contact area and thus increase the absorption efficiency. At the same time, the bubbles that flow out of the foaming area without breaking can flow in the packing section, replacing part of the liquid film flow on the packing. The bubbles flow slower than the liquid film, which increases the residence time of the liquid in the packing section, thereby increasing the gas-liquid reaction efficiency.

[0037] A liquid outlet 10 is provided at the bottom of the absorption tower a for the absorption liquid after the reaction to flow into a liquid storage tank 11 .

[0038] After the CO2 mixed gas enters the absorption tower a from the gas distributor 3, its flow path is from the top of the tower to the tower, that is, the gas channel position between the absorption tower and the gas-liquid separation tower. In this process, it passes through the atomization area of ​​the atomization unit, the foaming area of ​​the foaming unit and the packing area of ​​the packing unit. The above-mentioned areas will contact with the absorption liquid to absorb CO2. The radius of the tower body in the atomization area is slightly larger, which can reduce the wall flow phenomenon during atomization. The foaming unit is used to foam the droplets to increase the gas-liquid contact area. At the same time, the bubbles that have not been broken out of the foaming tower can flow in the packing section, replacing the liquid film flow on a part of the packing. The bubbles flow slower than the liquid film, which increases the residence time of the liquid in the packing section, thereby increasing the gas-liquid reaction efficiency.

[0039] After the above absorption process, the CO2 gas enters the foam separation unit through the gas channel. Because the CO2 gas at this time contains foam and liquid, further gas-liquid separation is required to completely separate the pure gas.

[0040] like Figure 4As shown, the ultrasonic defoamer 13 in the foam separation unit includes an annular fixing frame 13-1 and four annularly arranged ultrasonic generators 13-2 installed inside the annular fixing frame 13-1. The high-frequency sound waves generated by the ultrasonic generator 13-2 can generate pressure fluctuations on the foam surface, causing the foam to burst. Ultrasonic defoaming has high efficiency, short time, and low device cost, and can quickly break large bubbles flowing out of the packing tower a into small bubbles.

[0041] like Figure 5 and Figure 6 As shown, the cyclone separator is divided into two stages, namely, a primary cyclone separator 14 and a secondary cyclone separator 16, and the structures of the two are the same, and the secondary cyclone separator 16 is located above the primary cyclone separator 14. Taking the primary cyclone separator 14 as an example, it includes a spiral blade 14-1 and a guide groove 14-2, the spiral blade 14-1 is fixed on the tower wall of the gas-liquid separation tower b, and the guide groove 14-2 is located at the connection between the outer edge of the spiral blade 14-1 and the tower wall, which is also a spiral structure. The spiral blade 14-1 is used to guide the incoming gas to rise along the spiral path to form a vortex. When the gas containing liquid passes through the spiral blade, the gas is forced to form a spiral rising state, and at the same time, due to the action of centrifugal force, the small bubbles in the gas and the droplets released by the bubbles are thrown to the inner wall of the cyclone separator, that is, in the guide groove 14-2. After the small bubbles and droplets hit the inner wall, they flow downward along the spiral groove and finally converge to the lowest end of the groove. The collected liquid passes through the downcomer 15 connected to the guide groove 14-2 and then is discharged downward, thereby achieving gas-liquid separation. The structure of the guide groove 14-2 simplifies the liquid discharge process, allowing the liquid to be discharged from the system more smoothly, reducing the retention time of the liquid in the separator, thereby improving the processing capacity and stability of the entire system.

[0042] A wire mesh demister 21 is arranged above the secondary cyclone separator 16 to ensure that the foam and the gas are completely separated. Then the gas flows out from the top outlet of the cyclone separator, and the separated liquid droplets flow from the downcomer 19 into the liquid storage tank 13.

[0043] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Various changes that can be made within the knowledge scope of technicians in the relevant technical field without departing from the spirit of the present invention are all within the protection scope of the claims of the present invention.

Claims

1. An atomization-foaming-filler integrated flue gas CO2 capture system, characterized in that: Including CO2 absorption system and foam separation system; in The CO2 absorption system is located in the absorption tower, and the foam separation system is located in the gas-liquid separation tower; the absorption tower and the gas-liquid separation tower are connected through a gas pipeline, and the bottoms of the absorption tower and the gas-liquid separation tower are both connected to a liquid storage tank; The CO2 absorption system comprises a CO2 atomization unit, a foaming unit and a packing unit arranged in sequence from top to bottom in the absorption tower, wherein the CO2 atomization unit comprises a pump, a nozzle and a gas distributor; the pump is used to cooperate with the nozzle to spray the absorption liquid, and the gas distributor is used to provide CO2 gas and contact the sprayed liquid droplets; The foaming unit is composed of a multi-layer foaming net, which is a three-dimensional network structure, and the pore density of the multi-layer foaming net increases from top to bottom, which is used to convert the absorption droplets into foam, and the bubbles that flow out of the foaming area without breaking can flow in the packing section; The CO2 absorption system also includes a droplet recovery device, which is located at the bottom of the CO2 atomization unit. The droplet recovery device includes a cylinder and a drainage surface. The cylinder is fixed to the inner wall of the absorption tower, and the drainage surface is fixed to the middle of the cylinder to guide the absorption liquid on the tower wall of the absorption tower in the atomization zone into the foaming unit. The foam separation system includes an ultrasonic defoamer and a cyclone separator which are arranged in sequence from bottom to top in a gas-liquid separation tower. The cyclone separator guides the incoming gas to rise along a spiral path to form a cyclone. The top of the gas-liquid separation tower is a gas outlet, and the bottom is a liquid reflux port. A plurality of ultrasonic generators are evenly distributed along a ring in the ultrasonic defoamer to cause foam rupture. The cyclone separator is a spiral blade, which is fixedly connected to the inner wall of the gas-liquid separation tower. A spiral guide groove is provided on the outer edge of the spiral blade. The bottom of the guide groove is connected to the downcomer to discharge the absorption liquid from the absorption liquid outlet into the liquid storage tank.

2. The atomization-foaming-filler integrated flue gas CO2 capture system according to claim 1 is characterized in that: The foaming unit includes a top foaming net, a middle foaming net and a bottom foaming net arranged in sequence from top to bottom. The three foaming nets are all three-dimensional network structures, and the pore density of the three foaming nets increases in sequence from top to bottom.

3. The atomization-foaming-filler integrated flue gas CO2 capture system according to claim 1 is characterized in that: The cyclone separator comprises a primary cyclone separator and a secondary cyclone separator of the same structure.

4. The atomization-foaming-filler integrated flue gas CO2 capture system according to claim 3 is characterized in that: The foam separation system also includes a wire mesh demister, which is located between the secondary cyclone separator and the gas outlet at the top of the tower.

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