Flue gas carbon dioxide trapping and purifying system and operation method

Abstract

The invention relates to a flue gas carbon dioxide trapping and purifying system and an operation method. The flue gas carbon dioxide trapping and purifying system comprises a flue gas pretreatment unit, a carbon dioxide absorption unit, a carbon dioxide regeneration unit and a carbon dioxide post-treatment unit which are connected in sequence, the carbon dioxide regeneration unit comprises a decarburization device, and a first heating module, a second heating module and a third heating module which are connected with the decarburization device, wherein the first heating module is started when the in-plant wastewater zero discharge system runs; the second heating module is started when the in-plant wastewater zero discharge system stops running and is not in the off-peak electricity period; and the third heating module is started when the in-plant wastewater zero discharge system is shut down and the off-peak electricity period. According to the system, the three heating modules can be flexibly switched according to different time periods so that the optimal heating mode can be used in any time period, high-cost electric energy consumption can be greatly reduced, the operation cost of the system can be reduced, flue gas waste heat possibly wasted originally in the thermal power plant can be used for system operation, and the energy utilization rate of the thermal power plant is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of flue gas treatment, and in particular to a flue gas carbon dioxide capture and purification system and an operation method. Background Art

[0002] At present, carbon dioxide is one of the main components of greenhouse gases that cause global warming, and its impact on the greenhouse effect is as high as 55%. Coal-fired power plants are the largest industry emitting carbon dioxide. How to effectively capture carbon dioxide in flue gas from thermal power plants is an urgent problem to be solved. Flue gas carbon dioxide capture technologies mainly include chemical absorption, physical adsorption, membrane separation, etc. Among them, chemical absorption has the characteristics of low operating pressure and high capture efficiency and is widely used. In the traditional process of chemical absorption, the outlet flue gas is first pre-treated and cooled before entering the absorption tower to contact with the absorption liquid. The carbon dioxide in the outlet flue gas is absorbed by the absorption liquid to form a rich liquid that flows out from the bottom of the absorption tower. The decarbonized flue gas is discharged into the chimney from the top of the absorption tower. The rich liquid is heated by the heat exchanger through the pipeline and enters the top of the regeneration tower. After being heated with the regeneration tower, desorption is completed. The carbon dioxide gas obtained by desorption is collected, and the lean liquid separated by desorption is transported back to the absorption tower for reuse after recovering heat through the heat exchanger.

[0003] However, in the above-mentioned traditional chemical process, the desorption of carbon dioxide in the regeneration tower is a heat-driven process. Usually, a decarbonization device such as a reboiler is installed at the bottom of the desorption tower to heat the rich liquid output from the regeneration tower. The decarbonization device often consumes a large amount of electrical energy during operation, resulting in a significant increase in the system's operating energy consumption and operating costs. Summary of the invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a flue gas carbon dioxide capture and purification system and an operating method, which can connect the flue gas carbon dioxide capture and purification system with the wastewater zero emission system in a thermal power plant, so that the system can flexibly switch the heating mode according to different time periods to minimize the system operation cost. The use of flue gas heat exchange instead of electric energy heating can not only greatly reduce the high-cost electricity consumption required for system operation, but also realize the recycling and reuse of waste resources.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A flue gas carbon dioxide capture and purification system, connected to the factory wastewater zero discharge system and the boiler denitration device, includes a flue gas pretreatment unit, a carbon dioxide absorption unit, a carbon dioxide regeneration unit and a carbon dioxide post-treatment unit connected in sequence;

[0007] The absorption liquid of the carbon dioxide absorption unit absorbs carbon dioxide in the flue gas to form a rich liquid;

[0008] The carbon dioxide regeneration unit is used to heat the rich liquid and desorb the carbon dioxide to be discharged into the carbon dioxide post-processing unit; the carbon dioxide regeneration unit includes a decarbonization device and three heating modules connected to the decarbonization device, and the heating modules include a first heating module, a second heating module and a third heating module;

[0009] The first heating module uses the outlet flue gas output from the wastewater bypass evaporation tower of the in-plant wastewater zero discharge system to heat the decarbonization device, and the first heating module is turned on when the in-plant wastewater zero discharge system is in operation;

[0010] The second heating module extracts high-temperature flue gas from the outlet of the denitration device of the boiler in the plant to heat the decarbonization device, and the second heating module is turned on when the zero discharge system of wastewater in the plant is shut down and it is not off-peak electricity period;

[0011] The third heating module uses valley electricity to heat the decarbonization device, and the third heating module is turned on during the valley electricity period when the wastewater zero discharge system in the factory is shut down.

[0012] Furthermore, the first heating module includes a first pipe and a second pipe that can be switched on and off, the inlet end of the first pipe is connected to the outlet end of the boiler denitration device in the plant, the outlet end of the first pipe is connected to the inlet end of the wastewater bypass evaporation tower in the plant, the inlet end of the second pipe is connected to the outlet end of the wastewater bypass evaporation tower in the plant, and the outlet end of the second pipe is connected to the decarbonization device;

[0013] The second pipeline is provided with a dust removal device.

[0014] Furthermore, the second heating module includes a third pipe that can be switched on and off, the inlet end of the third pipe is connected to the outlet end of the boiler denitration device in the plant, and the outlet end of the third pipe is connected to the decarbonization device;

[0015] The third pipeline is provided with a dust removal device.

[0016] Furthermore, the decarbonization device comprises a lean liquid output end, through which the lean liquid generated by the decarbonization device heating the rich liquid is discharged, and a lean liquid thermometer is provided on the lean liquid output end to detect whether the lean liquid temperature is between set values, and the first heating module and the second heating module are both connected to a shunt pipe;

[0017] When the temperature of the lean solution is lower than a set value, the second heating module is turned on to assist in heating the decarbonization device, and when the temperature of the lean solution is higher than a set value, the diversion pipeline is opened.

[0018] Furthermore, the carbon dioxide post-processing unit includes at least two dehydration towers, which are used to switch and use to continuously dehydrate the carbon dioxide from the carbon dioxide post-processing unit, and the bottom of the dehydration tower is connected to a heating component, and the heating component is used to provide hot gas to heat the dehydration tower after one of the dehydration towers is saturated with water, so as to desorb water and regenerate;

[0019] The heating assembly comprises an air preheater and a first heating assembly and a second heating assembly connected to the air preheater;

[0020] The first heating component heats the air in the air preheater by heating the flue gas exhausted after heating the decarbonization device, and the first heating component is turned on when the first heating module and / or the second heating module are in operation;

[0021] The second heating assembly heats the air preheater using valley electricity.

[0022] Furthermore, a hot air thermometer is provided on the pipeline connecting the air preheater and the dehydration tower, which is used to detect whether the temperature of the hot air output from the air preheater is between the set values, and the air preheater is also connected to a valley power storage device;

[0023] When the hot air temperature is lower than a set value, the valley power storage device is turned on to assist in heating the air preheater;

[0024] When the hot air temperature is higher than a set value, the flow rate of the first heating component is reduced.

[0025] Further, the flue gas pretreatment unit includes a pretreatment tower, the inlet end of the pretreatment tower is connected to the flue gas outlet of the desulfurization tower in the plant, the pretreatment tower includes an alkali liquid input end, an alkali liquid output end, a first spray end and a first industrial water input end, and the first spray end includes a first demister and a first nozzle;

[0026] The alkali solution output end is connected to the first circulation pump, the alkali solution input end, the first heat exchanger and the first nozzle in sequence to form an alkali solution conveying path;

[0027] The pretreatment tower is also provided with a pH meter to monitor in real time whether the pH value in the pretreatment tower is at a preset value. The alkali liquid input end is connected to the alkali liquid tank to replenish the alkali liquid when the pH value in the pretreatment tower is lower than the preset value.

[0028] The pretreatment tower is also provided with a liquid level meter to monitor in real time whether the water level in the pretreatment tower is at a preset value. The first industrial water input end is connected to an industrial water pool to replenish industrial water when the water level in the pretreatment tower is lower than the set value.

[0029] Furthermore, the carbon dioxide absorption unit comprises an absorption tower and a scrubber, the absorption tower is connected to the scrubber, an absorption liquid is arranged inside the absorption tower for absorbing carbon dioxide in the flue gas to form a rich liquid and decarbonized flue gas, and the scrubber is used to remove the absorption liquid carried on the surface of the decarbonized flue gas from the absorption tower;

[0030] The scrubber tower comprises a second industrial water input end, a first industrial water output end, a second spray end, a low-concentration absorption liquid output end and a decarbonized flue gas output end, wherein the second spray end comprises a second demister and a second nozzle;

[0031] The second industrial water input end is connected to the industrial water pool;

[0032] The second industrial water input end is connected to the second nozzle, the second industrial water output end, the second circulation pump and the second nozzle in sequence to form an industrial water washing path;

[0033] The low-concentration absorption liquid output end is connected to the absorption tower for recycling the low-concentration absorption liquid;

[0034] The decarbonized flue gas output end is connected to the chimney.

[0035] In order to achieve the above object, the present invention also adopts the following technical solutions:

[0036] An operating method of a flue gas carbon dioxide capture and purification system, applicable to any one of the flue gas carbon dioxide capture and purification systems, comprises the following steps:

[0037] Step S1, after the flue gas is subjected to the removal of acidic gas and cooling in the flue gas pretreatment unit, the flue gas enters the carbon dioxide absorption unit to countercurrently contact with the absorption liquid for adsorption to form a rich liquid, and the rich liquid enters the decarbonization device after heat exchange;

[0038] Step S2, determining whether the zero wastewater discharge system in the factory is running during this time period;

[0039] If running, switching the first heating module to heat the decarbonization device;

[0040] If not running, determine whether this time period is a valley power time period;

[0041] If yes, switching the third heating module to heat the decarburization device;

[0042] If not, switching the second heating module to heat the decarbonization device;

[0043] Step S3, the rich liquid is heated and desorbed to obtain carbon dioxide and lean liquid, the carbon dioxide is compressed and enters the carbon dioxide post-processing unit for dehydration and impurity absorption to obtain high-purity carbon dioxide, and the lean liquid is returned to the carbon dioxide absorption unit for reuse.

[0044] In summary, compared with the prior art, the present invention has at least the following beneficial effects:

[0045] The present invention relates to a flue gas carbon dioxide capture and purification system and an operation method. The present invention is connected with a zero-discharge system for wastewater in a plant and a boiler denitration device, and comprises a flue gas pretreatment unit, a carbon dioxide absorption unit, a carbon dioxide regeneration unit and a carbon dioxide post-treatment unit which are connected in sequence; the absorption liquid of the carbon dioxide absorption unit absorbs carbon dioxide in the flue gas to form a rich liquid; the carbon dioxide regeneration unit is used to heat the rich liquid and desorb carbon dioxide and discharge it into the carbon dioxide post-treatment unit; the carbon dioxide regeneration unit comprises a decarbonization device and three heating modules connected with the decarbonization device, and the heating modules comprise a first heating module, a second heating module and a third heating module; the first heating module uses the outlet flue gas outputted from the wastewater bypass evaporation tower of the zero-discharge system for wastewater in the plant to heat the decarbonization device, and the first heating module is turned on when the zero-discharge system for wastewater in the plant is in operation; the second heating module extracts the high-temperature flue gas at the outlet of the boiler denitration device in the plant to heat the decarbonization device, and the second heating module is turned on when the zero-discharge system for wastewater in the plant is stopped and during a non-off-peak electricity period; the third heating module uses off-peak electricity to heat the decarbonization device, and the third heating module is turned on when the zero-discharge system for wastewater in the plant is stopped and during an off-peak electricity period. By linking the flue gas carbon dioxide capture and purification system with the wastewater zero emission system in the thermal power plant, the system can flexibly switch the operation of the three heating modules according to different time periods, use waste flue gas heat exchange or use valley electricity heating, so that the system can use the heating method that minimizes the system operating cost in the current time period to heat the decarbonization device in any time period. This can not only greatly reduce the high-cost electricity consumption required for system operation and reduce the system operating cost, but also realize the effective utilization of resources in the thermal power plant, and use the flue gas waste heat that might have been wasted in the thermal power plant for heating in the carbon dioxide regeneration process, reducing the consumption of electricity and improving the energy utilization rate of the thermal power plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0047] Figure 1 It is a schematic structural diagram of a flue gas carbon dioxide capture and purification system provided in one embodiment of the present invention.

[0048] Figure 2It is a schematic structural diagram of a carbon dioxide regeneration unit provided in one embodiment of the present invention.

[0049] Figure 3 It is a schematic structural diagram of a carbon dioxide post-processing unit provided in one embodiment of the present invention.

[0050] Figure 4 It is a schematic structural diagram of a flue gas pretreatment unit provided in one embodiment of the present invention.

[0051] Figure 5 This is a schematic structural diagram of a carbon dioxide absorption unit provided in one embodiment of the present invention.

[0052] Description of reference numerals:

[0053] 1. Flue gas pretreatment unit; 11. Pretreatment tower; 111. Alkali liquid input end; 112. Alkali liquid output end; 113. First industrial water input end; 114. First demister; 115. First nozzle; 116. First circulation pump; 117. pH meter; 118. Flue gas outlet end; 12. First heat exchanger; 13. Alkali liquid tank; 131. Alkali liquid pump; 14. Liquid level meter;

[0054] 2. Carbon dioxide absorption unit; 21. Absorption tower; 211. Flue gas inlet; 212. Rich liquid output; 213. Absorption liquid output; 214. Decarbonized flue gas outlet; 215. Third demister; 216. Third nozzle; 217. Second circulation pump; 22. Scrubber; 221. Second industrial water inlet; 222. First industrial water output; 223. Low-concentration absorption liquid output; 224. Decarbonized flue gas output; 225. Second demister; 226. Second nozzle; 23. Second heat exchanger; 24. Third heat exchanger;

[0055] 3. Carbon dioxide regeneration unit; 31. Decarbonization device; 311. Lean liquid output end; 3111. Lean liquid thermometer; 32. First heating module; 321. First pipeline; 322. Second pipeline; 33. Second heating module; 331. Third pipeline; 34. Ash removal device; 35. Diversion pipeline; 36. Regeneration tower; 361. Rich liquid input end; 362. Rich liquid outlet end; 363. Third carbon dioxide input end; 364. Third carbon dioxide output end; 37. Compressor;

[0056] 4. CO2 post-processing unit; 41. Dehydration tower; 411. First CO2 input terminal; 412. Filler; 413. First CO2 output terminal; 414. Exhaust port; 42. Heating assembly; 421. Air preheater; 422. First heating assembly; 4221. Fourth pipeline; 423. Air booster fan; 43. Hot air thermometer; 44. Valley power storage device; 45. Adsorption tower; 451. Second CO2 input terminal; 452. Second CO2 output terminal;

[0057] 5. Zero discharge system of wastewater in the factory; 51. Denitrification device; 52. Wastewater bypass evaporation tower;

[0058] 6. Industrial water pool. DETAILED DESCRIPTION

[0059] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0060] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0061] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0062] In the operation of thermal power plants, there are usually many types of systems working together. Due to environmental protection policy requirements, it has become an inevitable trend to achieve zero wastewater discharge in the plant. The process with better application effect is the bypass evaporation crystallization process. This system extracts high-temperature flue gas (flue gas temperature 350-380℃) from the outlet of the denitrification device and contacts it with the atomized high-salt wastewater in the bypass evaporation tower in countercurrent. With the help of high-temperature flue gas, the wastewater evaporates and crystallizes inside the bypass evaporation tower. The flue gas temperature at the outlet of the wastewater bypass evaporation tower is 180-220℃. The waste heat flue gas generally directly enters the dust removal system for treatment and then is discharged. It cannot effectively realize the waste heat utilization of this part of the flue gas, which increases the energy loss of the thermal power plant and is not conducive to the improvement of the overall benefits of the thermal power plant. Therefore, the present invention combines the carbon dioxide capture and purification system in the thermal power plant with the zero wastewater discharge system in the plant, effectively utilizes the flue gas temperature of the zero wastewater discharge system, and reduces the energy loss and operating cost of the flue gas carbon dioxide capture and purification system.

[0063] As attached Figure 1As shown, the present invention provides a flue gas carbon dioxide capture and purification system, comprising a flue gas pretreatment unit 1, a carbon dioxide absorption unit 2, a carbon dioxide regeneration unit 3 and a carbon dioxide post-treatment unit 4 connected in sequence, wherein the flue gas pretreatment unit 1 is connected to the flue gas exhaust port of the on-site desulfurization tower outlet, and is used to remove acidic gases in the flue gas, and also plays a role in reducing the flue gas temperature; the pretreated flue gas enters the interior of the carbon dioxide absorption unit 2 from the bottom thereof and countercurrently contacts with the absorption liquid stored at the bottom thereof, and the absorption liquid that absorbs the carbon dioxide in the flue gas enters the carbon dioxide regeneration unit 3 as a rich liquid; the carbon dioxide regeneration unit 3 is used to heat the rich liquid and desorb the carbon dioxide in the rich liquid, and discharge it into the carbon dioxide post-treatment unit 4, and the rich liquid that desorbs the carbon dioxide forms a lean liquid that is transported back to the carbon dioxide absorption unit 2 for reuse. The carbon dioxide regeneration unit 3 includes a decarbonization device 31 and three heating modules connected to the decarbonization device 31, and the heating modules include a first heating module 32, a second heating module 33 and a third heating module; the first heating module 32 is turned on when the in-plant wastewater zero discharge system 5 is in operation, at which time the wastewater bypass evaporation tower 52 is in normal operation, and the first heating module 32 uses the outlet flue gas output by the wastewater bypass evaporation tower 52 to heat the decarbonization device 31; the second heating module 33 is turned on when the in-plant wastewater zero discharge system 5 is shut down and it is not an off-peak electricity period, at which time the wastewater bypass evaporation tower 52 is in a shutdown period, the boiler's denitrification device 51 is still in operation, and the second heating module 33 is turned on when the in-plant wastewater zero discharge system 5 is shut down and it is not an off-peak electricity period. The high-temperature flue gas at the outlet of the denitrification device 51 of the boiler in the extraction plant is heated to the decarbonization device 31. It is worth mentioning that, considering that the flue gas extraction process is inevitably accompanied by a certain amount of energy consumption, the flue gas carbon dioxide capture and purification system will give priority to activating the first heating module 32 to meet the heating needs, so the second heating module 33 is started when the first heating module 32 cannot provide a heat source and during the non-off-peak power period; the third heating module is started when the zero discharge system of wastewater in the plant is shut down and during the off-peak power period. The third heating module uses off-peak electricity to heat the decarbonization device 31, making full use of low-cost off-peak electricity resources, greatly reducing heating costs, and improving the economy of the entire flue gas carbon dioxide capture and purification system. By flexibly switching the operation of the three heating modules according to different time periods, using waste flue gas for heat exchange or valley electricity for heating, the system can use the heating method that minimizes the system operation cost in the current time period to heat the decarbonization device 31 in any time period to desorb the rich liquid to form carbon dioxide. This can not only greatly reduce the high-cost electricity consumption required for system operation and reduce system operation costs, but also achieve effective utilization of resources in the thermal power plant, and use the flue gas waste heat that might have been wasted in the thermal power plant for heating in the carbon dioxide regeneration process, thereby reducing electricity consumption and improving the energy utilization rate of the thermal power plant.

[0064] It is worth noting that some thermal power plants do not have a zero-discharge system for wastewater 5, but a denitrification device 51 must be installed in the plant. These thermal power plants can use the second heating module 33 of this system to extract the high-temperature flue gas in the outlet flue of the denitrification device 51 to heat the decarbonization device 31 during the off-peak period, and still use the third heating module for heating during the off-peak period. The two heating modes are switched to reduce the energy loss and operating cost of the flue gas carbon dioxide capture and purification system.

[0065] In certain embodiments of the present invention, as shown in the attached Figure 2 As shown, the first heating module 32 includes a first pipe 321 and a second pipe 322 that can be switched on and off. The inlet end of the first pipe 321 is connected to the outlet end of the boiler denitration device 51 in the plant, and the outlet end of the first pipe 321 is connected to the inlet end of the wastewater bypass evaporation tower 52 in the plant. The first pipe 321 is used to guide the high-temperature flue gas in the outlet flue of the denitration device 51 to the wastewater bypass evaporation tower 52, and use the high-temperature flue gas to promote the evaporation and crystallization of the wastewater in the evaporation tower, so as to achieve preliminary treatment of the wastewater and resource recycling. The inlet end of the second pipe 322 is connected to the outlet end of the wastewater bypass evaporation tower 52 in the plant, and the outlet end of the second pipe 322 is connected to the decarbonization device 31. The second pipe 322 is used to introduce the outlet flue gas flowing out of the wastewater bypass evaporation tower 52 into the decarbonization device 31, and after heating the decarbonization device 31, it is discharged to the subsequent flue gas treatment system of the wastewater zero emission system 5 through the decarbonization device 31. Furthermore, since the outlet flue gas discharged from the wastewater bypass evaporation tower 52 is untreated, impurities such as dust may exist in the outlet flue gas. In order to prevent the impurities from damaging the internal components of the decarbonization device 31 or clogging the pipeline, a dust removal device 34 is provided on the second pipeline 322 to intercept dust and ensure the reliability of system operation.

[0066] In certain embodiments of the present invention, the second heating module 33 includes a third pipe 331 that can be switched on and off. The inlet end of the third pipe 331 is connected to the outlet end of the denitration device 51 in the plant, and the outlet end of the third pipe 331 is connected to the decarbonization device 31. When the first heating module 32 cannot provide a heat source and is in a non-off-peak power period, or when the thermal power plant does not have a wastewater zero discharge system and is in a non-off-peak power period, the third pipe 331 will be opened, so that the high-temperature flue gas at the outlet of the denitration device 51 can be directly transmitted to the decarbonization device 31 through the third pipe 331, and after heating the decarbonization device 31, it is discharged to the subsequent flue gas treatment system of the wastewater zero discharge system 5 through the decarbonization device 31. Similarly, a dust removal device 34 is provided on the third pipe 331 to intercept dust to prevent impurities from damaging the internal components of the decarbonization device 31 or clogging the pipe.

[0067] It is worth mentioning that the second pipeline 322 of the first heating module 32 and the third pipeline 331 of the second heating module 33 have certain flexibility in layout. The rear ends of the two can be merged, and the ash removal device 34 is arranged at the merged part to save space and facilitate system installation; it is also possible to choose not to merge, each independently leads to the decarbonization device 31, and the ash removal device 34 is respectively arranged on the second pipeline 322 and the third pipeline 331 to remove ash according to the flue gas temperature in different pipelines.

[0068] In certain embodiments of the present invention, the decarbonization device 31 includes a lean liquid output terminal 311. During its operation, the lean liquid formed after the decarbonization device 31 heats the rich liquid will be transported to the carbon dioxide absorption unit 2 for reuse via the lean liquid output terminal 311. In this reuse process, the lean liquid will first pass through the second heat exchanger 23, where it will exchange heat with the rich liquid output from the carbon dioxide absorption unit 2, so that the rich liquid can absorb the heat carried by the lean liquid and thus increase its own temperature before entering the carbon dioxide regeneration unit 3, thereby reducing the energy loss and heating time used by the decarbonization device 31 to heat the rich liquid. Therefore, in order to accurately control the output temperature of the lean liquid, a lean liquid thermometer 3111 is provided on the lean liquid output terminal 311 to detect whether the lean liquid temperature is between the set value of 130-140°C.

[0069] Specifically, when the lean liquid temperature detected by the lean liquid thermometer 3111 is less than the set range of 130-140°C, this situation may occur when the first heating module 32 is used for heating. Since the temperature does not meet the standard, it will affect the efficiency of heat exchange between the lean liquid and the rich liquid in the carbon dioxide absorption unit 2 and the stability of the system. At this time, the second heating module 33 can be turned on to assist in heating the decarbonization device 31 until the lean liquid temperature is equal to the set value of 130-140°C, and then the second heating module 33 can be turned off to ensure that the lean liquid temperature is appropriate while avoiding energy loss caused by excessive extraction of high-temperature flue gas at the outlet of the denitrification device 51. In addition, the first heating module 32 and the second heating module 33 are both connected to the shunt pipe 35. When the lean liquid temperature detected by the lean liquid thermometer 3111 is greater than the set value of 130-140°C, this situation may occur when the first heating module 32 or the second heating module 33 is used for heating. At this time, the shunt pipe 35 can be opened to shunt the flue gas and discharge it to the subsequent flue gas treatment system of the wastewater zero discharge system to reduce the lean liquid temperature to the set range.

[0070] In certain embodiments of the present invention, the carbon dioxide regeneration unit 3 also includes a regeneration tower 36, which includes a rich liquid input end 361, a fourth spray end, a rich liquid outlet end 362, a third carbon dioxide input end 363 and a third carbon dioxide output end 364. The rich liquid input end 361 is connected to the carbon dioxide absorption unit 2, and the rich liquid outlet end 362 is connected to the decarbonization device 31 to input rich liquid for desorption. The desorbed carbon dioxide is transported to the third carbon dioxide input end 363 through the decarbonization device 31, and enters the carbon dioxide post-processing unit 4 from the third carbon dioxide output end 364 after heat exchange and compression by the compressor 37.

[0071] In certain embodiments of the present invention, since the carbon dioxide outputted from the regeneration tower 36 is obtained by high-temperature desorption of the rich liquid by the decarbonization device 31, the obtained carbon dioxide itself will carry a certain amount of water vapor, therefore, the carbon dioxide post-processing unit 4 is provided with a dehydration tower 41 to dry the carbon dioxide. The dehydration tower 41 includes a first carbon dioxide input end 411 arranged at the bottom, a filler 412 arranged inside, a first carbon dioxide output end 413 arranged at the top, and an exhaust port 414 connected to the atmosphere, which is used to discharge water when the filler 412 is heated, and the first carbon dioxide input end 411 is sequentially connected to the filler 412 and the first carbon dioxide output end 413 to form a carbon dioxide dehydration path. In addition, the carbon dioxide post-processing unit 4 includes at least two dehydration towers 41, which are used to switch and use to dehydrate carbon dioxide uninterruptedly, and the bottom of the dehydration tower 41 is connected to the heating component 42, and the heating component 42 is used to provide hot gas to heat the filler 412 inside one of the dehydration towers 41 after it is saturated with water, so as to desorb water and regenerate. When the interior of one of the dehydration towers 41 is saturated with water, the switching process is as follows: first, stop the carbon dioxide from continuing to enter the dehydration tower 41 that is currently saturated with water, and instead introduce the carbon dioxide into the standby dehydration tower 41', then turn on the heating component 42 to heat the dehydration tower 41 that is currently stopped. Under the heating effect, the water originally absorbed by the filler 412 is gradually converted into water vapor and discharged from the exhaust port 414. As the water is removed, the dehydration tower 41 is regenerated and its water absorption capacity is restored, so that it can be put into use again; when the standby dehydration tower 41' has been running for a period of time and the internal filler 412' is also saturated with water, repeat the above steps to heat and regenerate the dehydration tower 41'. At least two dehydration towers are switched to operate and used, and the cycle repeats. By using at least two dehydration towers and following this uninterrupted switching operation mode, it is effectively avoided that the operation of other units in the system needs to be suspended when the dehydration tower 41 is saturated and regenerated, which effectively improves the operating efficiency of the system and ensures that the entire carbon dioxide capture and purification system can operate stably for a long time.

[0072] Furthermore, the heating component 42 includes an air preheater 421 and a first heating component 422 and a second heating component connected to the air preheater 421. The air preheater 421 introduces air through the air booster fan 423, and heats the air through the first heating component 422 or the second heating component. The hot air enters the dehydration tower 41 through the bottom of the dehydration tower 41 to regenerate the dehydration tower 41. Among them, the first heating component 422 uses the flue gas discharged after heating the decarbonization device 31 to heat the air in the air preheater 421. The first heating component 422 includes a fourth pipe 4221 that can be switched on and off. The fourth pipe 4221 is a branch on the pipeline between the decarbonization device 31 and the subsequent flue gas treatment system of the wastewater zero discharge system 5. When the first heating module 32 and / or the second heating module 33 are in operation, the first heating component 422 is turned on, so that the flue gas discharged from the decarbonization device 31, which still has a high temperature, can flow into the air preheater 421 through the fourth pipe 4221, and the temperature of the air is increased by the waste heat of the flue gas, further realizing the effective utilization of waste heat resources and improving the energy efficiency of the entire system. The second heating component uses valley electricity to heat the air preheater 421 when the third heating module is in operation. This heating method that is flexibly switched according to the operation time period of different heating modules, combined with the operation mode of the carbon dioxide regeneration unit 3 during the operation of the system, can meet the heat required for the regeneration of the dehydration tower 41 while minimizing the operating cost and energy loss of the system.

[0073] In certain embodiments of the present invention, since the filler 412 in the dehydration tower itself has a suitable regeneration temperature range, once the hot air temperature is too high, the filler 412 may be deformed, aged, etc., thereby affecting the performance or life of the filler 412. If the hot air temperature is too low, the moisture in the filler 412 cannot be completely precipitated, resulting in poor regeneration effect. In order to keep the filler 412 at a suitable temperature at all times, it is necessary to accurately control the temperature of the hot air entering the dehydration tower 41. Therefore, a hot air thermometer 43 is provided on the pipe connecting the air preheater 421 and the dehydration tower 41, which is used to detect whether the temperature of the hot air output from the air preheater 421 is between the set value of 120-150°C.

[0074] Specifically, the air preheater 421 is also connected to a valley power storage device 44. When the hot air temperature detected by the hot air thermometer 43 is lower than the set value range of 120-150°C, this situation may occur when the first heating component 422 is used for heating. At this time, it is a non-valley power time period. The valley power storage device 44 is turned on to assist in heating the air preheater 421 until the hot air is equal to the set value of 120-150°C, and the valley power storage device 44 is turned off. While ensuring that the hot air temperature is appropriate, it is avoided that the energy loss caused by overheating the hot air in the air preheater 421 and the use performance of the filler 412 is affected by the excessively high hot air temperature. When the hot air temperature detected by the hot air thermometer 43 is higher than the set value range of 120-150°C, this situation may also occur when the first heating component 422 is used for heating. At this time, the flue gas flow entering the first heating component 422 can be reduced or the pipeline between the decarbonization device 31 and the subsequent flue gas treatment system of the wastewater zero discharge system 5 can be opened to realize flue gas diversion, so as to reduce the hot air temperature to the set range.

[0075] In certain embodiments of the present invention, in order to further remove impurities from the dehydrated carbon dioxide to obtain high-purity carbon dioxide, the carbon dioxide post-processing unit 4 also includes an adsorption tower 45, which is connected to the dehydration tower 41. The adsorption tower 45 includes a second carbon dioxide input terminal 451 arranged at the bottom, an adsorption material arranged inside, and a second carbon dioxide output terminal 452 arranged at the top. The second carbon dioxide input terminal 451 is connected to the first carbon dioxide output terminal 413 to receive the dehydrated carbon dioxide. The second carbon dioxide input terminal 451 is sequentially connected to the adsorption material and the second carbon dioxide output terminal 452 to form a carbon dioxide removal path. The carbon dioxide discharged through the second carbon dioxide output terminal 452 is high-purity carbon dioxide, which can be used in subsequent application scenarios such as chemical production and food processing that have high requirements for carbon dioxide purity.

[0076] In certain embodiments of the present invention, the flue gas pretreatment unit 1 includes a pretreatment tower 11, the inlet end of the pretreatment tower 11 is connected to the flue gas outlet of the desulfurization tower in the factory, the pretreatment tower 11 includes an alkali liquid input end 111, an alkali liquid output end 112, a first spray end, a first industrial water input end 113 and a flue gas outlet end 118, and the flue gas outlet end 118 is connected to the bottom of the carbon dioxide absorption unit 2. The flue gas enters the pretreatment tower 11, and the alkali liquid is used to remove the acidic gas in the flue gas and cool it down. The pretreated flue gas enters the carbon dioxide absorption unit 2 through the flue gas outlet end 118 and contacts with the absorption liquid in countercurrent. The first spray end includes a first demister 114 and a first nozzle 115, wherein the first demister 114 is used to remove the droplets carried by the flue gas after the treatment process such as alkali liquid spraying, so as to prevent the droplets from affecting the subsequent flue gas treatment effect or causing damage to the subsequent equipment. The alkali solution output end 112 is connected to the first circulation pump 116, the alkali solution input end 111, the first heat exchanger 12 and the first nozzle 115 in sequence to form an alkali solution conveying path, so that the alkali solution circulates continuously to enhance the mass transfer effect between the alkali solution and the flue gas, so as to more effectively remove the acidic gas in the flue gas.

[0077] Furthermore, the pretreatment tower 11 is also provided with a pH meter 117 to monitor in real time whether the pH value in the pretreatment tower 11 is at a preset value of pH=8-9. The alkali liquid input end 111 is connected to the alkali liquid tank 13. When the pH value of the alkali liquid in the pretreatment tower 11 detected by the pH meter 117 is less than 8-9, the ability to absorb the acidic gas in the flue gas will be affected due to insufficient alkalinity. At this time, the alkali liquid pump 131 is opened to extract the alkali liquid in the alkali liquid tank 13 to the pretreatment tower 11 to replenish the alkali liquid so that the pH value of the alkali liquid returns to a suitable range. As the alkali liquid is continuously consumed, the liquid level of the alkali liquid will drop. When the liquid level is too low, the mass transfer and reaction effect between the alkali liquid and the flue gas will be unsatisfactory, and the contact between the alkali liquid and the flue gas will be insufficient, which will further cause the acidic gas in the flue gas to be unable to be effectively removed, affecting the effect of the pretreatment step. Therefore, the pretreatment tower 11 is also provided with a liquid level meter to monitor in real time whether the water level value in the pretreatment tower 11 is within the preset value range. The first industrial water input end 113 of the pretreatment tower 11 is connected to the industrial water pool 6. When the liquid level meter 14 detects that the liquid level is too low, industrial water is added to the pretreatment tower 11 to always keep the liquid level in the pretreatment tower 11 stable and ensure the normal operation of the pretreatment tower 11.

[0078] In certain embodiments of the present invention, the carbon dioxide absorption unit 2 includes an absorption tower 21, and the absorption tower 21 includes a flue gas inlet end 211, a rich liquid output end 212, an absorption liquid output end 213, a third spray end, and a decarbonized flue gas outlet end 214 arranged at the bottom. The flue gas inlet end 211 is connected to the flue gas outlet end 118 of the pretreatment tower 11, and the rich liquid output end 212 is connected to the carbon dioxide regeneration unit 3. The pretreated flue gas enters the absorption tower 21 through the flue gas inlet end 211, and contacts with the absorption liquid in the absorption tower 21 in countercurrent. The absorption liquid absorbs the carbon dioxide in the flue gas and is discharged from the rich liquid output end 212 as a rich liquid, and sequentially passes through the third heat exchanger 24 and the high-temperature carbon dioxide and the second heat exchanger 23 and the high-temperature lean liquid to exchange heat, and then enters the regeneration tower 36, and the flue gas with carbon dioxide removed is discharged through the decarbonized flue gas outlet end 214 at the top of the absorption tower 21. Preferably, the absorption tower 21 is provided with a second circulation pump 217. The third spray end includes a third demister 215 and a third nozzle 216, wherein the third demister 215 is used to reduce the absorption liquid content carried on the surface of the decarbonized flue gas and reduce the waste of the absorption liquid. The absorption liquid output end 213 is connected to the second circulation pump 217 and the third nozzle 216 in sequence to form an absorption liquid mass transfer path, enhance the mass transfer effect between the absorption liquid and carbon dioxide, improve the absorption rate of carbon dioxide, and also help to improve the treatment efficiency of the absorption tower 21.

[0079] In certain embodiments of the present invention, the amount of absorption liquid carried by the decarbonized flue gas cannot be completely removed by relying solely on the third demister 215. Therefore, the carbon dioxide absorption unit 2 of the present system is further provided with a scrubbing tower 22 for further removing the absorption liquid on the surface of the decarbonized flue gas. The scrubbing tower 22 is connected to the decarbonized flue gas outlet 214 of the absorption tower 21. The scrubbing tower 22 includes a second industrial water input end 221, a first industrial water output end 222, a second spray end, a low-concentration absorption liquid output end 223 and a decarbonized flue gas output end 224. The second spray end includes a second demister 225 and a second nozzle 226. The second industrial water input end 221 is connected to the industrial water pool 6. The absorption liquid is further removed by spraying and scrubbing with industrial water. The second industrial water input end 221 is connected in sequence to the second nozzle 226, the first industrial water output end 222, the second circulation pump 217 and the second nozzle 226 to form a circulation, thereby forming an industrial water scrubbing path. In addition, the washed absorption liquid is mixed with the industrial water at the bottom of the scrubber 22 to form a low-concentration absorption liquid, and the low-concentration absorption liquid output end 223 is connected to the absorption liquid mass transfer path of the absorption tower 21, so that the low-concentration absorption liquid can be recycled into the absorption tower 21, effectively reducing operating costs and losses. The decarbonized flue gas outlet end 214 is connected to the chimney, and the decarbonized flue gas that has been completely cleared of the absorption liquid is discharged from the top of the scrubber 22 to the chimney of the thermal power plant.

[0080] In addition to the above-mentioned flue gas carbon dioxide capture and purification system, the present invention also provides an operating method applicable to the above-mentioned flue gas carbon dioxide capture and purification system. The operating method of the flue gas carbon dioxide capture and purification system and the above-mentioned flue gas carbon dioxide capture and purification system can be referenced to each other.

[0081] A method for operating a flue gas carbon dioxide capture and purification system comprises the following steps:

[0082] Step S1, after the flue gas is subjected to the flue gas pretreatment unit 1 to remove acidic gases and cool down, the flue gas enters the carbon dioxide absorption unit 2 to countercurrently contact with the absorption liquid for adsorption to form a rich liquid, and the rich liquid enters the decarbonization device 31 after heat exchange;

[0083] Step S2, determining whether the factory wastewater zero discharge system 5 is running during this time period;

[0084] If running, switch the first heating module 32 to heat the decarbonization device 31;

[0085] If not running, determine whether this time period is a valley power time period;

[0086] If yes, switch the third heating module to heat the decarburization device 31;

[0087] If not, switch the second heating module 33 to heat the decarbonization device 31;

[0088] Step S3, the rich liquid is heated and desorbed to obtain carbon dioxide and lean liquid, the carbon dioxide is compressed and enters the carbon dioxide post-processing unit 4 for dehydration and impurity absorption to obtain high-purity carbon dioxide, and the lean liquid returns to the carbon dioxide absorption unit 2 for reuse.

[0089] It is worth noting that if some thermal power plants do not have a wastewater zero discharge system 5, they can flexibly adjust step S2 to reduce the energy loss and operating cost of the flue gas carbon dioxide capture and purification system. In this case, step S2 is: determining whether this time period is a valley power time period;

[0090] If yes, switch the third heating module to heat the decarburization device 31;

[0091] If not, the second heating module 33 is switched to heat the decarbonization device 31 .

[0092] As attached Figure 1-5As shown, the specific operation mode of all embodiments of the flue gas carbon dioxide capture and purification system applied in combination with the present invention is as follows: first, the flue gas is discharged through the flue gas outlet of the desulfurization tower in the factory and enters the pretreatment tower 11, and the acidic gas and the temperature are removed by the alkali solution in the pretreatment tower 11. This process requires continuous balancing of the pH value and liquid level of the alkali solution in the tower. The treated flue gas is discharged into the absorption tower 21 through the pretreatment tower 11, and the decarbonized flue gas with carbon dioxide removed is input from the absorption tower 21 to the scrubbing tower 22 to remove the absorption liquid on the surface of the decarbonized flue gas. The decarbonized flue gas after scrubbing is discharged into the chimney in the factory, and the low-concentration absorption liquid washed off is reused in the absorption tower 21. The absorption liquid absorbs the carbon dioxide in the flue gas and is discharged from the absorption tower 21 as a rich liquid, and is input into the regeneration tower 36 after heat exchange, and is transported to the decarbonization device 31 by the regeneration tower 36, and different heating modules are switched for heating according to different time periods. The decarbonization device 31, that is, switching the first heating module 32 for heating during the operation period of the in-plant wastewater zero discharge system 5, switching the second heating module 33 for heating during the shutdown period of the in-plant wastewater zero discharge system 5 and the off-peak period, switching the third heating module for heating during the shutdown period of the in-plant wastewater zero discharge system 5 and the off-peak period, the rich liquid is desorbed after being heated by the decarbonization device 31 to obtain the desorbed carbon dioxide and the lean liquid from which the carbon dioxide is removed, the high-temperature lean liquid is transported back to the absorption tower 21 through the decarbonization device 31 for reuse, and heat is exchanged with the undesorbed rich liquid during the transportation process; the carbon dioxide is transported back to the regeneration tower 36 through the decarbonization device 31 and discharged through the regeneration tower 36, and after heat exchange and compression with the undesorbed rich liquid, enters the dehydration tower 41 to remove water vapor, and the dehydrated carbon dioxide enters the adsorption tower 45 for further impurity removal to obtain high-purity carbon dioxide. This operation method can continuously capture and purify high-purity carbon dioxide, always operate the system in a manner with minimal operating cost and minimal energy loss, and resources in each link can be recycled, effectively reducing operating costs.

[0093] In addition, the dehydration tower 41 regeneration step is also included: first, the carbon dioxide is stopped from continuing to enter the dehydration tower 41 that is currently saturated with water, and the carbon dioxide is instead introduced into the spare dehydration tower 41', and then the heating component 42 is turned on to heat the dehydration tower 41 that is currently stopped. Under the heating effect, the water absorbed by the filler 412 is gradually converted into water vapor and discharged. As the water is removed, the dehydration tower 41 is regenerated and its water absorption capacity is restored, so that it can be put into use again; when the spare dehydration tower 41' has been running for a period of time and the internal filler 412' is also saturated with water, the above steps are repeated to heat and regenerate the dehydration tower 41', and at least two dehydration towers are switched for operation and use, and the cycle is repeated to avoid the situation where other units in the system need to be suspended when the dehydration tower 41 is saturated and regenerated, thereby effectively improving the operating efficiency of the system and ensuring that the entire carbon dioxide capture and purification system can operate stably for a long time.

[0094] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A flue gas carbon dioxide capture and purification system, connected to the factory wastewater zero discharge system and the factory denitrification device, characterized in that: It includes a flue gas pre-treatment unit, a carbon dioxide absorption unit, a carbon dioxide regeneration unit and a carbon dioxide post-treatment unit connected in sequence; The absorption liquid of the carbon dioxide absorption unit absorbs carbon dioxide in the flue gas to form a rich liquid; The carbon dioxide regeneration unit is used to heat the rich liquid and desorb the carbon dioxide to be discharged into the carbon dioxide post-processing unit; the carbon dioxide regeneration unit includes a decarbonization device and three heating modules connected to the decarbonization device, and the heating modules include a first heating module, a second heating module and a third heating module; The first heating module uses the outlet flue gas output from the wastewater bypass evaporation tower of the in-plant wastewater zero discharge system to heat the decarbonization device, and the first heating module is turned on when the in-plant wastewater zero discharge system is in operation; The second heating module extracts high-temperature flue gas from the outlet of the denitration device of the boiler in the plant to heat the decarbonization device, and the second heating module is turned on when the zero discharge system of wastewater in the plant is shut down and it is not off-peak electricity period; The third heating module uses valley electricity to heat the decarbonization device, and the third heating module is turned on during the valley electricity period when the wastewater zero discharge system in the factory is shut down.

2. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The first heating module includes a first pipeline and a second pipeline that can be switched on and off, the inlet end of the first pipeline is connected to the outlet end of the boiler denitration device in the plant, the outlet end of the first pipeline is connected to the inlet end of the wastewater bypass evaporation tower in the plant, the inlet end of the second pipeline is connected to the outlet end of the wastewater bypass evaporation tower in the plant, and the outlet end of the second pipeline is connected to the decarbonization device; The second pipeline is provided with a dust removal device.

3. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The second heating module comprises a third pipe which can be switched on and off, the inlet end of the third pipe is connected to the outlet end of the boiler denitration device in the plant, and the outlet end of the third pipe is connected to the decarbonization device; The third pipeline is provided with a dust removal device.

4. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The decarbonization device comprises a lean liquid output end, through which the lean liquid generated by the decarbonization device heating the rich liquid is discharged, and a lean liquid thermometer is provided on the lean liquid output end to detect whether the lean liquid temperature is between set values, and the first heating module and the second heating module are both connected to a shunt pipe; When the temperature of the lean solution is lower than a set value, the second heating module is turned on to assist in heating the decarbonization device, and when the temperature of the lean solution is higher than a set value, the diversion pipeline is opened.

5. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The carbon dioxide post-processing unit comprises at least two dehydration towers, which are used to switch and use to continuously dehydrate the carbon dioxide from the carbon dioxide post-processing unit. The bottom of the dehydration tower is connected to a heating component, and the heating component is used to provide hot gas to heat the dehydration tower after one of the dehydration towers is saturated with water, so as to desorb water and regenerate the dehydration tower; The heating assembly comprises an air preheater and a first heating assembly and a second heating assembly connected to the air preheater; The first heating component heats the air in the air preheater by heating the flue gas exhausted after heating the decarbonization device, and the first heating component is turned on when the first heating module and / or the second heating module are in operation; The second heating assembly heats the air preheater using valley electricity.

6. The flue gas carbon dioxide capture and purification system according to claim 5, characterized in that: A hot air thermometer is provided on the pipeline connecting the air preheater and the dehydration tower, which is used to detect whether the temperature of the hot air output from the air preheater is between the set values, and the air preheater is also connected to a valley power storage device; When the hot air temperature is lower than a set value, the valley power storage device is turned on to assist in heating the air preheater; When the hot air temperature is higher than a set value, the flow rate of the first heating component is reduced.

7. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The flue gas pretreatment unit comprises a pretreatment tower, the inlet end of the pretreatment tower is connected to the flue gas outlet of the desulfurization tower in the plant, the pretreatment tower comprises an alkali liquid input end, an alkali liquid output end, a first spray end and a first industrial water input end, and the first spray end comprises a first demister and a first nozzle; The alkali solution output end is connected to the first circulation pump, the alkali solution input end, the first heat exchanger and the first nozzle in sequence to form an alkali solution conveying path; The pretreatment tower is also provided with a pH meter to monitor in real time whether the pH value in the pretreatment tower is at a preset value. The alkali liquid input end is connected to the alkali liquid tank to replenish the alkali liquid when the pH value in the pretreatment tower is lower than the preset value. The pretreatment tower is also provided with a liquid level meter to monitor in real time whether the water level in the pretreatment tower is at a preset value. The first industrial water input end is connected to an industrial water pool to replenish industrial water when the water level in the pretreatment tower is lower than the set value.

8. The flue gas carbon dioxide capture and purification system according to claim 1, characterized in that: The carbon dioxide absorption unit comprises an absorption tower and a scrubber, wherein the absorption tower is connected to the scrubber, an absorption liquid is arranged inside the absorption tower for absorbing carbon dioxide in the flue gas to form a rich liquid and decarbonized flue gas, and the scrubber is used to remove the absorption liquid carried on the surface of the decarbonized flue gas from the absorption tower; The scrubber tower comprises a second industrial water input end, a first industrial water output end, a second spray end, a low-concentration absorption liquid output end and a decarbonized flue gas output end, wherein the second spray end comprises a second demister and a second nozzle; The second industrial water input end is connected to the industrial water pool; The second industrial water input end is connected to the second nozzle, the first industrial water output end, the second circulation pump and the second nozzle in sequence to form an industrial water washing path; The low-concentration absorption liquid output end is connected to the absorption tower for recycling the low-concentration absorption liquid; The decarbonized flue gas output end is connected to the chimney.

9. An operating method of a flue gas carbon dioxide capture and purification system, applicable to the flue gas carbon dioxide capture and purification system according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step S1, after the flue gas is subjected to the removal of acidic gas and cooling in the flue gas pretreatment unit, the flue gas enters the carbon dioxide absorption unit to countercurrently contact with the absorption liquid for adsorption to form a rich liquid, and the rich liquid enters the decarbonization device after heat exchange; Step S2, determining whether the zero wastewater discharge system in the factory is running during this time period; If running, switching the first heating module to heat the decarbonization device; If not running, determine whether this time period is a valley power time period; If yes, switching the third heating module to heat the decarburization device; If not, switching the second heating module to heat the decarbonization device; Step S3, the rich liquid is heated and desorbed to obtain carbon dioxide and lean liquid, the carbon dioxide is compressed and enters the carbon dioxide post-processing unit for dehydration and impurity absorption to obtain high-purity carbon dioxide, and the lean liquid is returned to the carbon dioxide absorption unit for reuse.

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