A system and method for capturing low concentration carbon dioxide

Abstract

The present invention belongs to the technical field of carbon dioxide capture, and specifically relates to a system and method for capturing low-concentration carbon dioxide, including: a pretreatment tower: the pretreatment tower is used to cool and remove impurities from flue gas; an absorption tower: the absorption tower is used to absorb carbon dioxide in flue gas; a desorption tower: the desorption tower is used to parse carbon dioxide from rich liquid; a cooler: the cooler is used to convert carbon dioxide into dry ice for fixation; a heating device: the heating device is used to heat the desorption tower; the pretreatment tower, the absorption tower, the desorption tower, the heating device and the cooler are connected in sequence; the absorption tower includes: a demister: the demister is composed of a plurality of corrugated plates, and a liquid baffle is provided on the top of the corrugated plate. This solution solves the problem of gas-liquid entrainment when the absorption tower discharges gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of carbon dioxide capture, and in particular relates to a system and method for capturing low-concentration carbon dioxide. Background Art

[0002] As the world warms, it has caused great troubles to human production and life, especially CO2, which is the main culprit for rising temperatures. Therefore, in industrial production, the treatment of CO2 before exhaust gas emission is crucial. Cement production is one of the main sources of global carbon dioxide (CO2) emissions. Faced with increasingly stringent environmental regulations and carbon reduction pressure, the cement industry has begun to explore and adopt CO2 capture technology. These technologies include chemical absorption, physical adsorption, membrane separation, etc., which aim to capture CO2 from the flue gas of cement kilns and then seal or reuse it.

[0003] At present, the existing carbon dioxide capture device with announcement number CN118142308A includes an absorption tower with an air inlet, an exhaust port, an absorption liquid inlet and an absorption liquid outlet; a heat exchanger with a connected flue gas inlet, a flue gas outlet and a condensation outlet, and the flue gas outlet is connected to the air inlet; a cooling component includes a condensation water tank and a cooling pipe, the cooling pipe is passed from the outside of the absorption tower to the inside of the absorption tower and passes through the absorption tower, the condensation water tank has a condensation inlet, a water outlet and a first water return port, the condensation outlet is connected to the condensation inlet, the cooling pipe has a cooling inlet and a cooling outlet, the water outlet is connected to the cooling inlet, and the cooling outlet is connected to the first water return port. This application can solve the problem in the related art that the temperature difference between the upper and lower parts of the absorption tower is large and the absorption reaction cannot be carried out efficiently.

[0004] However, there is also a problem: when the device's absorption tower discharges gas, there will be a problem of gas-liquid entrainment, which will cause the absorbent to be discharged, pollute the environment, and cause absorbent loss, requiring frequent replenishment of the absorbent. Summary of the invention

[0005] The present invention provides a low-concentration carbon dioxide capture system to solve the problem of gas-liquid entrainment when the gas is discharged from an absorption tower.

[0006] The present invention provides a system for capturing low-concentration carbon dioxide, comprising: a pretreatment tower: the pretreatment tower is used to cool and remove impurities from flue gas; an absorption tower: the absorption tower is used to absorb carbon dioxide in flue gas; a desorption tower: the desorption tower is used to desorb carbon dioxide from rich liquid; a cooler: the cooler is used to convert carbon dioxide into dry ice for fixation; a heating device: the heating device is used to heat the desorption tower; the pretreatment tower, the absorption tower, the desorption tower, the heating device and the cooler are connected in sequence; the absorption tower comprises: a demister: the demister is composed of a plurality of corrugated plates, and a liquid baffle is provided on the top of the corrugated plates.

[0007] The principle of this scheme is that the original flue gas enters the pretreatment tower, contacts with the coolant and cools down to the optimal CO2 absorption temperature; then enters the absorption tower, contacts with the absorbent in reverse, CO2 is captured by the absorbent, and when the flue gas passes through the demister of the absorption tower, the flue gas will hit the corrugated plate, and the liquid will adhere to the corrugated plate, but some liquid will still flow out with the flue gas. At this time, the liquid baffle will block it again, so that the remaining liquid is also blocked and falls back into the tower with gravity. The rich absorption liquid enters the desorption tower to achieve rich liquid regeneration; the heating device heats and decomposes the rich liquid; the lean liquid after regeneration in the desorption tower is cooled from the bottom of the desorption tower and sent to the absorption tower to achieve the reuse of the absorbent; the carbon dioxide gas coming out of the desorption tower is cooled by a cooler to obtain solid carbon dioxide, completing the carbon dioxide capture.

[0008] Beneficial effects: 1. The chemical absorption method adopted in this scheme captures carbon dioxide. The chemical absorption method can effectively and quickly react chemically with CO2, thereby removing it from the flue gas. Especially when using amine absorbents, the CO2 capture efficiency of this method can reach more than 90%. Moreover, the chemical absorption method is suitable for low-concentration CO2 diluted in the atmosphere. 2. The corrugated plate increases the contact area of ​​the fluid through its unique corrugated shape, thereby increasing the collision chance of particles or gases in the fluid, which is beneficial to the transfer and reaction of substances. The liquid baffle plate performs secondary liquid blocking to further separate the gas and liquid, and the liquid baffle plate is less likely to be blocked than the corrugated plate. When the liquid baffle plate adheres, the adhered material will be affected by gravity, and the adhered material is not easy to fall off due to the need for undulation of the corrugated plate. In this way, the number of undulations of the corrugated plate can be reduced, reducing the risk of clogging of the corrugated plate.

[0009] Furthermore, it also includes an adjustment mechanism, which includes a rubber bag and a push rod, the rubber bag is arranged on both sides of the corrugated plate, the rubber bag is slidably connected to the corrugated plate, the liquid baffle plate includes a steel cable, a sliding block and two sub-plates, one end of the steel cable is fixedly connected to the corrugated plate, and the other end is fixedly connected to the sliding block, the sliding block is slidably connected to the corrugated plate, the sliding block is hinged to the two sub-plates, one end of the push rod is fixedly connected to the rubber bag, and the other end is rotatably connected to the two sub-plates.

[0010] The distance between the corrugated plates plays a critical role in gas-liquid separation. If the distance between the plates is too large, the flow rate will decrease and the solid-liquid separation efficiency will be low. If the distance between the plates is too small, the flow rate will be too fast, and the liquid removal effect will be poor. In reality, the corrugated plates often adhere to solid impurities, causing the distance between the plates to become smaller. When this solution is not running, the two sub-plates of the liquid baffle block most of the space. When the corrugated plates begin to exhaust, the airflow will lift the liquid baffle, and the liquid baffle moves up, causing the rubber bag to move up as well, straightening the wrinkled rubber bag and increasing the distance between the plates. At the same time, because the wrinkled parts are straightened, the impurities adhering to them will also fall off due to the deformation of the rubber bag. Then the liquid retaining plate moves up, which drives the sliding block to move up. The sliding block drives the steel cable to straighten. After the two sub-plates reach the set height, the steel cable pulls the sliding block to move down. The two sub-plates rotate, making the airflow through the space larger. The liquid retaining plate falls down again under the action of gravity. When the sliding block hits the corrugated plate, the two sub-plates return to the initial state under the support of the sliding block, and the rubber bag returns to the wrinkled state. By repeating this movement, the mechanism can not only change the distance between the plates according to the airflow, but also keep the surface of the corrugated plate in a changing state to prevent impurities from adhering.

[0011] Furthermore, a liquid distributor is provided in the absorption tower, and the liquid distributor adopts a trough-type liquid distributor. The liquid distributor can evenly distribute the absorbent on the packing layer, so that the gas-liquid mixing is more comprehensive.

[0012] Furthermore, a steam heating pipe is provided in the analysis tower, and the steam heating pipe passes through the tower plate from bottom to top, and the steam heating pipe is connected to the heating device. When the analysis tower is working, the heating device will heat the water until it is vaporized, and then the water is transported to the inside of the analysis tower by the steam heating pipe, so that the rich liquid inside is fully heated, thereby improving the conversion efficiency.

[0013] The present invention also provides a method for capturing low-concentration carbon dioxide, comprising the following steps:

[0014] Step S10: The original flue gas enters the pretreatment tower and contacts with the coolant to cool down to the optimal CO2 absorption temperature;

[0015] Step S20: Then it enters the absorption tower and contacts with the absorbent in reverse direction, CO2 is captured by the absorbent, and the flue gas is discharged after passing through the demister of the absorption tower;

[0016] Step S30: the rich liquid of the absorption liquid enters the desorption tower to realize the regeneration of the rich liquid; the heating device heats and decomposes the rich liquid;

[0017] Step S40: the lean liquid after regeneration of the desorption tower is cooled from the bottom of the desorption tower and then sent to the absorption tower to achieve the reuse of the absorbent;

[0018] Step S50: The carbon dioxide gas from the desorption tower is cooled by a cooler to obtain solid carbon dioxide, thus completing the capture of carbon dioxide. The method is simple in process, has little loss of absorbent, and can be recycled for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a low-concentration carbon dioxide capture system.

[0020] Figure 2 This is a structural diagram of an absorption tower for a low-concentration carbon dioxide capture system.

[0021] Figure 3 This is a state diagram of the corrugated plate flow rate becoming faster for a low concentration carbon dioxide capture system.

[0022] Figure 4 A state diagram for a corrugated plate flow rate recovery to normal for a low concentration carbon dioxide capture system;

[0023] Figure 5 Schematic diagram of a liquid distributor for a low concentration carbon dioxide capture system.

[0024] The figure marks in the specification include: 1. pretreatment tower; 2. absorption tower; 3. cooler; 4. analysis tower; 5. steam heating pipe; 6. outlet pipe; 7. demister; 8. liquid distributor; 9. packing layer; 10. tower body; 11. air inlet pipe; 12. base; 13. rubber bag; 14. push rod; 15. liquid baffle plate; 16. corrugated plate; 17. liquid outlet pipe; 18. sliding block; 19. guide rail; 20. steel cable; 21. second gear; 22. ratchet bar; 23. first gear; 24. spring tooth. DETAILED DESCRIPTION

[0025] Basically as attached Figure 1 As shown:

[0026] This solution provides a system for capturing low-concentration carbon dioxide, including a pretreatment tower 1, an absorption tower 2, a desorption tower 4, a cooler 3 and a heating device. The pretreatment tower 1, the absorption tower 2, the desorption tower 4, the heating device and the cooler 3 are connected in sequence; the pretreatment tower 1 is used to cool and remove impurities from the flue gas; the absorption tower 2 is used to absorb the carbon dioxide in the flue gas; the desorption tower 4 is used to parse carbon dioxide from the rich liquid, and a steam heating pipe 5 is provided in the desorption tower 4. The steam heating pipe 5 passes through the tower plate from bottom to top, and the steam heating pipe 5 is connected to the heating device. When the desorption tower 4 is working, the heating device will heat the water until it is vaporized, and then it will be transported to the inside of the desorption tower 4 by the steam heating pipe 5, so that the internal rich liquid is fully heated to improve the conversion efficiency. The cooler 3 is used to convert carbon dioxide into dry ice fixation; the heating device is used to heat the desorption tower 4.

[0027] As attached Figure 2 As shown:

[0028] The absorption tower 2 includes a liquid distributor 8, a packing layer 9, a demister 7 and a tower body 10. The liquid distributor 8 adopts a trough-type liquid distributor 8. The liquid distributor 8 can evenly distribute the absorbent on the packing layer 9, so that the gas-liquid mixing is more comprehensive. The tower body 10 includes an air inlet pipe 11, an air outlet pipe 6, a liquid inlet pipe and a liquid outlet pipe 17. The tower body 10 is fixed on the ground through a base 12. The absorbent enters the liquid distributor 8 from the liquid inlet pipe, and the liquid is distributed, and then evenly falls on the packing layer 9. The bottom air inlet pipe 11 enters the flue gas, and the flue gas and the absorbent are mixed with gas and liquid at the packing layer 9. Finally, the absorbent becomes a rich liquid and is discharged from the liquid outlet, entering the analytical tower 4, and the gas removed from the carbon dioxide passes through the demister 7 and is discharged from the top. The demister 7 is composed of a plurality of corrugated plates 16, and a liquid baffle 15 is provided on the top of the corrugated plate 16.

[0029] As attached Figure 3 , Figure 4 As shown:

[0030] It also includes an adjustment mechanism, which includes a rubber bag 13 and a push rod 14. The rubber bag 13 is arranged on both sides of the corrugated plate 16, and the rubber bag 13 is slidably connected to the corrugated plate 16. The liquid retaining plate 15 includes a steel cable 20, a sliding block 18 and two sub-plates. One end of the steel cable 20 is fixedly connected to the corrugated plate 16, and the other end is fixedly connected to the sliding block 18. The sliding block 18 is slidably connected to the guide rail 19 on the corrugated plate 16. The sliding block is hinged to the two sub-plates, and the two sub-plates are respectively arranged on the left and right sides of the sliding block. One end of the push rod 14 is fixedly connected to the rubber bag 13, and the other end is rotatably connected to the two sub-plates. The spacing between the corrugated plates 16 plays a key role in gas-liquid separation. If the distance between the plates is too large, the flow rate will decrease, and the solid-liquid separation efficiency will be low. If the distance between the plates is too small, the flow rate will be too fast, and the liquid removal effect will be poor. In reality, solid impurities often adhere to the corrugated plate 16, resulting in a smaller distance between the plates. When the present solution is not in operation, the two sub-plates of the liquid baffle plate 15 block most of the space. When the corrugated plate 16 begins to exhaust, the airflow will lift the liquid baffle plate 15, and the liquid baffle plate 15 will move upward, causing the rubber bag 13 to move upward as well, straightening the wrinkled rubber bag 13 and increasing the distance between the plates. At the same time, since the wrinkled parts are straightened, the impurities adhered thereto will also fall off due to the deformation of the rubber bag 13. Then the upward movement of the liquid retaining plate 15 will drive the sliding block 18 upward, and the sliding block 18 will drive the steel cable 20 to straighten. After the two split plates reach the set height, the steel cable 20 pulls the sliding block 18, so that the sliding block 18 moves up and down on the guide rail 19. The two split plates rotate, so that the airflow passing space becomes larger, and the liquid retaining plate 15 will fall again under the action of gravity. When the sliding block 18 hits the folding plate 16, the two split plates return to the initial state under the support force of the sliding block 18, and the rubber bag 13 returns to the wrinkled state. By repeatedly moving in this way, the mechanism can not only change the distance between the plates according to the airflow, but also keep the surface of the folding plate 16 in a changing state to prevent impurities from adhering.

[0031] The liquid distributor 8 is also provided with a rotation adjustment mechanism, which includes a first gear 23, a second gear 21, a spring and a ratchet bar 22. The liquid distributor 8 is slidably connected to the tower body 10, one end of the spring is fixedly connected to the liquid distributor 8, and the other end is fixedly connected to the tower body 10. The first gear 23 is fixedly connected to the liquid distributor 8, the ratchet bar 22 is fixedly connected to the tower body 10, the ratchet bar 22 is meshed with the second gear 21, and the ratchet bar 22 is provided with a spring tooth 24. The spring tooth 24 will not shrink when the second gear 21 moves downward. When the second gear 21 moves upward, the spring tooth 24 shrinks and will not mesh with the second gear 21. The second gear 21 is meshed with the first gear 23. The second gear 21 is rotationally connected to the liquid distributor 8. When the absorption tower starts to work, When the liquid distributor 8 enters the absorbent, the liquid distributor 8 will move downward under the gravity of the liquid, and will move downward with the first gear 23 and the second gear 21. The second gear 21 rotates under the action of the ratchet bar 22. The rotation of the second gear 21 will drive the first gear 23 to rotate. The first gear 23 drives the liquid distributor 8 to rotate the set angle. This embodiment uses 10 degrees. The angle setting can be selected according to those skilled in the art. When it stops using, the liquid in the liquid distributor 8 will be drained. At this time, the liquid distributor 8 moves up under the action of the spring, and drives the first gear 23 and the second gear 21 to move up at the same time. Since the ratchet bar 22 does not mesh when the second gear 21 moves up, the liquid distributor 8 does not rotate when it moves up. Some places of the packing layer have been impacted due to the problem of the liquid distributor. The packing layer is subjected to the impact of the solution for a long time, which is easy to deform, resulting in poor effect. When the present mechanism is used, the liquid distributor 8 moves down and rotates an angle, which changes the liquid distribution position, so that some places of the packing layer that are not used for a long time can also be used, thereby increasing the service life of the packing layer.

[0032] As attached Figure 1-5 As shown:

[0033] The principle of this scheme is:

[0034] The original flue gas enters the pretreatment tower 1, contacts with the coolant and is cooled to the optimal CO2 absorption temperature; then it enters the absorption tower 2, contacts with the absorbent in reverse, and the CO2 is captured by the absorbent. When the flue gas passes through the demister 7 of the absorption tower 2, the flue gas will hit the corrugated plate 16, and the liquid will adhere to the corrugated plate 16. However, some liquid will still flow out with the flue gas. At this time, the liquid baffle plate 15 will block it again, so that the remaining liquid is also blocked and falls back into the tower with gravity.

[0035] When the corrugated plate 16 begins to exhaust, the airflow will lift the liquid retaining plate 15, and the liquid retaining plate 15 moves upward, so that the rubber bag 13 also moves upward, so that the wrinkled rubber bag 13 is straightened, and the distance between the plates is increased. At the same time, because the wrinkled part is straightened, the impurities adhering to it will also be detached due to the deformation of the rubber bag 13. Then the liquid retaining plate 15 moves upward and drives the sliding block 18 to move upward, and the sliding block 18 drives the steel cable 20 to straighten. After the two sub-plates reach the set height, the steel cable 20 pulls the sliding block 18, so that the sliding block 18 moves up and down on the guide rail 19, and the two sub-plates rotate, so that the airflow passing space becomes larger, and the liquid retaining plate 15 will fall again under the action of gravity. When the sliding block 18 hits the corrugated plate 16, the two sub-plates return to the initial state under the support force of the sliding block 18, and the rubber bag 13 returns to the wrinkled state. By repeatedly moving in this way, the present mechanism can not only change the distance between the plates according to the airflow, but also make the surface of the corrugated plate 16 always in a changing state to prevent impurities from adhering. The rich liquid of the absorption liquid enters the desorption tower to achieve rich liquid regeneration; at this time, the heating device will heat the water until it vaporizes, and then it will be transported to the inside of the desorption tower 4 by the steam heating pipe 5, so that the rich liquid inside can be fully heated to improve the conversion efficiency. The lean liquid after regeneration in the desorption tower 4 is cooled from the bottom of the desorption tower and sent to the absorption tower 2 to achieve the reuse of the absorbent; the carbon dioxide gas coming out of the desorption tower 4 is cooled by the cooler 3 to obtain carbon dioxide solid, completing the carbon dioxide capture.

[0036] The beneficial effects of this solution are: 1. The corrugated plate 16 increases the contact area of ​​the fluid through its unique corrugated shape, thereby increasing the collision chance of particles or gases in the fluid, which is beneficial to the transfer and reaction of substances. The liquid baffle plate 15 performs secondary liquid blocking to further separate the gas and liquid, and the liquid baffle plate 15 will not be blocked, so the number of twists and turns of the corrugated plate 16 can be reduced, reducing the risk of blockage of the corrugated plate 16. 2. The rubber bag 13, as the surface of the corrugated plate 16, can not only change the distance between the plates according to the size of the airflow, but also remove impurities by deformation when impurities adhere to the corrugated plate 16.

[0037] The present invention also provides a method for capturing low-concentration carbon dioxide, comprising the following steps:

[0038] Step S10: The original flue gas enters the pretreatment tower 1 and contacts with the coolant to cool down to the optimal CO2 absorption temperature;

[0039] Step S20: Then it enters the absorption tower 2, contacts with the absorbent in reverse, CO2 is captured by the absorbent, and the flue gas is discharged after passing through the demister 7 of the absorption tower 2;

[0040] Step S30: the rich liquid of the absorption liquid enters the desorption tower to realize the regeneration of the rich liquid; the heating device heats and decomposes the rich liquid;

[0041] Step S40: the lean liquid after regeneration of the desorption tower 4 is cooled from the bottom of the desorption tower and then sent to the absorption tower 2 to achieve the reuse of the absorbent;

[0042] Step S50: The carbon dioxide gas from the analytical tower 4 is cooled by the cooler 3 to obtain solid carbon dioxide, thus completing the carbon dioxide capture. The method is simple in process, has little loss of absorbent, and can be recycled for a long time.

[0043] The above is only an embodiment of the present invention, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the present invention, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A system for capturing low-concentration carbon dioxide, comprising: Pretreatment tower (1): the pretreatment tower (1) is used to cool and remove impurities from flue gas; Absorption tower (2): the absorption tower (2) is used to absorb carbon dioxide in the flue gas; Desorption tower (4): the desorption tower (4) is used to desorb carbon dioxide from the rich liquid; Cooler (3): The cooler (3) is used to convert carbon dioxide into dry ice for fixation; Heating device: the heating device is used to heat the analytical tower (4); The pretreatment tower (1), the absorption tower (2), the analytical tower (4), the heating device and the cooler (3) are connected in sequence; Features: The absorption tower (2) comprises: Demister (7): the demister (7) is composed of a plurality of corrugated plates (16), and a liquid baffle (15) is provided on the top of the corrugated plates (16); The invention also comprises an adjustment mechanism, the adjustment mechanism comprising a rubber bag (13) and a push rod (14), the rubber bag (13) being arranged on both sides of the corrugated plate (16), the rubber bag (13) being slidably connected to the corrugated plate (16), the liquid retaining plate (15) comprising a steel cable (20), a sliding block (18) and two split plates, one end of the steel cable (20) being fixedly connected to the corrugated plate (16), and the other end being fixedly connected to the sliding block (18), the sliding block (18) being slidably connected to the corrugated plate (16), the sliding block (18) being hinged to the two split plates, and one end of the push rod (14) being fixedly connected to the rubber bag (13), and the other end being rotatably connected to the two split plates.

2. A system for capturing low-concentration carbon dioxide according to claim 1, characterized in that: A liquid distributor (8) is provided in the absorption tower (2), and the liquid distributor (8) is a trough-type liquid distributor (8).

3. A system for capturing low-concentration carbon dioxide according to claim 1, characterized in that: A steam heating pipe (5) is provided in the analysis tower (4), the steam heating pipe (5) passes through the tower plate from bottom to top, and the steam heating pipe (5) is connected to a heating device.

4. A method for capturing low-concentration carbon dioxide, comprising applying a system for capturing low-concentration carbon dioxide as claimed in any one of claims 1 to 3, characterized in that: The following steps are involved: step S10: The original flue gas enters the pretreatment tower (1) and is cooled to the optimal CO2 absorption temperature by contacting with the coolant; Step S20: the flue gas then enters the absorption tower (2) and contacts with the absorbent in reverse direction, CO2 is captured by the absorbent, and the flue gas is discharged after passing through the demister (7) of the absorption tower (2); Step S30: the rich liquid of the absorption liquid enters the desorption tower to realize the regeneration of the rich liquid; the heating device heats and decomposes the rich liquid; Step S40: the lean liquid after regeneration from the desorption tower (4) is cooled from the bottom of the desorption tower and then sent to the absorption tower (2) to achieve the reuse of the absorbent; Step S50: The carbon dioxide gas coming out of the analysis tower (4) is cooled by the cooler (3) to obtain carbon dioxide solid, thus completing the carbon dioxide capture.

Images