A system and method for capturing carbon dioxide coupled with desulfurization wastewater concentration in a thermal power plant

Abstract

The application discloses a kind of carbon dioxide capture coupling desulfurization wastewater concentration system and method of thermal power plant, the system includes: desulfurization absorption tower, flue gas heat exchanger, carbon dioxide capture / calcining device, primary cooler, secondary cooler and wastewater concentration tower.Desulfurization clean flue gas enters carbon dioxide capture / calcining device through flue gas heat exchanger;According to different operation mode, the carbon dioxide-containing gas generated by decarburization flue gas or calcining is subjected to corresponding heat exchange, separation and cooling treatment.Desulfurization wastewater flows through secondary cooler and primary cooler in turn to absorb gas heat, and after being heated, enters wastewater concentration tower for concentration.The application couples the gas cooling requirement in carbon dioxide capture and calcining process with the heating requirement in desulfurization wastewater concentration process, improves heat utilization efficiency and reduces wastewater concentration energy consumption.

Description

Technical Field

[0001] This invention relates to the field of flue gas treatment and desulfurization wastewater treatment in thermal power plants, and particularly to a carbon dioxide capture coupled with desulfurization wastewater concentration system and method for thermal power plants. Background Technology

[0002] Flue gas from thermal power plant boilers contains a significant amount of carbon dioxide. To reduce carbon dioxide emissions, calcium-based solid adsorbents can be used to capture the carbon dioxide in the flue gas. The calcium-based carbon dioxide capture process typically includes two steps: carbon dioxide capture and adsorbent calcination and regeneration. In this process, calcium oxide reacts with carbon dioxide in the flue gas to form calcium carbonate. The calcium carbonate is then calcined at high temperatures to release carbon dioxide and regenerate into calcium oxide, thus achieving adsorbent recycling. During this process, the captured decarbonized flue gas and the carbon dioxide-containing gas produced by calcination are both at high temperatures and typically require cooling before entering subsequent flue gas emission or carbon dioxide purification, compression, and utilization stages. Existing carbon dioxide capture systems primarily aim to meet the temperature requirements of subsequent processes when cooling these high-temperature gases, resulting in insufficient utilization of the heat released during cooling and potential heat loss.

[0003] On the other hand, limestone-gypsum wet desulfurization systems generate desulfurization wastewater during operation. This wastewater typically contains high concentrations of salt, suspended solids, and other impurities. To reduce wastewater discharge and facilitate subsequent treatment, it needs to be concentrated. This concentration process requires the evaporation of some water, thus consuming heat. Existing desulfurization wastewater concentration systems that use steam, electricity, or other external heat sources to provide the heat required for concentration increase the energy consumption and operating costs of thermal power plants.

[0004] In existing technologies, carbon dioxide capture and treatment and desulfurization wastewater concentration treatment typically operate relatively independently. There is a lack of effective coordination between the cooling requirements of the high-temperature gases during carbon dioxide capture and calcination and the heating requirements during desulfurization wastewater concentration. On the one hand, the heat carried by the high-temperature gases is not fully utilized; on the other hand, desulfurization wastewater concentration still requires additional energy. Therefore, existing thermal power plant carbon dioxide capture and desulfurization wastewater treatment processes suffer from insufficient synergy in heat utilization between different treatment processes and low overall system energy efficiency. Summary of the Invention

[0005] The purpose of this invention is to provide a carbon dioxide capture coupled with desulfurization wastewater concentration system and method for thermal power plants, which couples the cooling requirements of high-temperature gas during carbon dioxide capture and calcination with the heating requirements during desulfurization wastewater concentration. This allows the desulfurization wastewater to absorb heat from the high-temperature gas while cooling it, and utilize the absorbed heat for subsequent concentration, thereby improving the utilization of high-temperature gas heat and reducing the additional energy consumption of the desulfurization wastewater concentration process.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] In a first aspect, the present invention provides a carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants, comprising: a desulfurization absorption tower, a flue gas heat exchanger, a carbon dioxide capture / calcination device, a primary cooler, a secondary cooler, a particle separation component, a desulfurization wastewater filtration tank, a wastewater transfer pump, and a wastewater concentration tower.

[0008] The clean flue gas outlet of the desulfurization absorption tower is connected to the carbon dioxide capture / calcination device via the low-temperature side of the flue gas heat exchanger. The carbon dioxide capture / calcination device has a carbon dioxide capture mode and a calcination mode.

[0009] The gas outlet of the carbon dioxide capture / calcination device is connected to the gas inlet of the primary cooler. In the carbon dioxide capture mode, the gas outlet of the primary cooler is connected to the high-temperature side inlet of the flue gas heat exchanger, and the high-temperature side outlet of the flue gas heat exchanger is connected to the desulfurization absorption tower, so that the decarbonized flue gas output from the carbon dioxide capture / calcination device is cooled by the primary cooler, and then exchanges heat with the desulfurized clean flue gas output from the desulfurization absorption tower in the flue gas heat exchanger, and returns to the desulfurization absorption tower after heat exchange. In the calcination mode, the gas outlet of the primary cooler is connected to the gas inlet of the secondary cooler through the particle separation component, so as to separate and cool the carbon dioxide-containing gas generated during calcination.

[0010] The desulfurization absorption tower is connected to the desulfurization wastewater filtration tank. The desulfurization wastewater filtration tank is connected to the cooling medium inlet of the secondary cooler via the wastewater transfer pump. The cooling medium outlet of the secondary cooler is connected to the cooling medium inlet of the primary cooler. The cooling medium outlet of the primary cooler is connected to the wastewater concentration tower, so that the desulfurization wastewater flows sequentially through the secondary cooler and the primary cooler for heat exchange and temperature increase before entering the wastewater concentration tower for concentration.

[0011] Optionally, the system includes at least two sets of carbon dioxide capture / calcination devices and a primary cooler corresponding to each set of carbon dioxide capture / calcination devices. The gas outlet of each set of carbon dioxide capture / calcination devices is connected to the gas inlet of the corresponding primary cooler, so that each set of carbon dioxide capture / calcination devices and its corresponding primary cooler form independent gas processing branches.

[0012] Each group of carbon dioxide capture / calcination devices is used to alternate between the carbon dioxide capture mode and the calcination mode, so that different groups of carbon dioxide capture / calcination devices can perform carbon dioxide capture and calcination regeneration respectively.

[0013] Optionally, the carbon dioxide capture / calcination device is equipped with a heating resistor, which is used to heat the reactants in the carbon dioxide capture / calcination device to adjust the reaction temperature of the carbon dioxide capture / calcination device.

[0014] Optionally, the carbon dioxide capture coupled desulfurization wastewater concentration system for thermal power plants further includes a switching valve located on the gas outlet side of the primary cooler. The switching valve is used to selectively connect the gas outlet of the primary cooler to one of the high-temperature side inlet of the flue gas heat exchanger and the gas inlet of the particle separation component, depending on the operating mode of the carbon dioxide capture / calcination device.

[0015] Optionally, the particle separation assembly includes a cyclone separator and a bag filter connected in sequence;

[0016] The secondary cooler, impurity filter, carbon dioxide compressor, moisture absorption tower, carbon dioxide liquefaction unit, carbon dioxide purification tower, and carbon dioxide storage tank are connected in sequence.

[0017] Optionally, the carbon dioxide capture coupled desulfurization wastewater concentration system for thermal power plants further includes a chiller. The chiller, the carbon dioxide liquefier, and the carbon dioxide purification tower are sequentially connected to form a cooling medium circulation loop. The cooling medium output from the chiller flows sequentially through the carbon dioxide liquefier and the carbon dioxide purification tower before returning to the chiller.

[0018] Optionally, the wastewater thickening tower includes a gas distribution disk, a packing layer, a spray layer, and a demister arranged from bottom to top;

[0019] The gas distribution disk is connected to the air fan so as to evenly distribute the air delivered by the air fan and then send it into the packing layer;

[0020] The spray layer is connected to the cooling medium outlet of the primary cooler so that the desulfurization wastewater after absorbing heat is atomized by the spray layer and enters the packing layer, and comes into countercurrent contact with the air entering the packing layer.

[0021] The demister is used to remove wastewater droplets entrained in the air. The gas outlet of the wastewater concentration tower is connected to the desulfurization absorption tower so as to transport the air treated by the demister to the desulfurization absorption tower.

[0022] Optionally, the bottom of the wastewater thickening tower is connected to the inlet of the concentrated water transfer pump, and the outlet of the concentrated water transfer pump is connected to the spray layer, so as to transport the concentrated desulfurization wastewater at the bottom of the wastewater thickening tower to the spray layer for circulating spraying and circulating concentration; the bottom of the wastewater thickening tower is also provided with a concentrated wastewater discharge port for discharging the concentrated desulfurization wastewater.

[0023] Secondly, the present invention provides a method for concentrating carbon dioxide capture coupled with desulfurization wastewater from a thermal power plant, comprising:

[0024] The desulfurized flue gas discharged from the desulfurization absorption tower is transported to the carbon dioxide capture / calcination unit via the low-temperature side of the flue gas heat exchanger.

[0025] In the carbon dioxide capture mode, carbon dioxide in the desulfurized flue gas is captured by the carbon dioxide capture / calcination device, and the decarbonized flue gas output from the carbon dioxide capture / calcination device flows sequentially through the high-temperature side of the primary cooler and the flue gas heat exchanger. After the decarbonized flue gas is cooled by heat exchange in the primary cooler, it exchanges heat with the desulfurized flue gas in the flue gas heat exchanger and returns to the desulfurization absorption tower after heat exchange.

[0026] In the calcination mode, the reactants in the carbon dioxide capture / calcination device are calcined and regenerated, and the carbon dioxide-containing gas generated by calcination flows sequentially through the primary cooler, the particle separation component and the secondary cooler to perform heat exchange, cooling, particle separation and further cooling of the carbon dioxide-containing gas.

[0027] The desulfurization wastewater discharged from the desulfurization absorption tower is sent to the desulfurization wastewater filtration tank for filtration, and then sequentially transported by the wastewater transfer pump to the secondary cooler and the primary cooler, so that the desulfurization wastewater absorbs the heat of the gas flowing through the secondary cooler and the primary cooler respectively, and the desulfurization wastewater after heat exchange and temperature increase is transported to the wastewater concentration tower.

[0028] Outside air is evenly distributed through a gas distribution disc by an air fan and then sent into the packing layer. The desulfurization wastewater, after heat exchange and heating, is atomized and sprayed into the packing layer through a spray layer, so that the outside air and the desulfurization wastewater come into countercurrent contact in the packing layer. This allows some of the water in the desulfurization wastewater to evaporate and enter the outside air. The air that has come into contact with the desulfurization wastewater is then demisted by a demister and sent to the desulfurization absorption tower. The concentrated desulfurization wastewater at the bottom of the wastewater concentration tower is returned to the spray layer by a concentrate transfer pump for circulating spraying and concentration. After the concentrated desulfurization wastewater meets the preset concentration conditions, at least a portion of the concentrated desulfurization wastewater is discharged through the concentrated wastewater discharge port.

[0029] Optionally, at least two sets of the carbon dioxide capture / calcination devices are provided, and each set of the carbon dioxide capture / calcination devices is equipped with a corresponding primary cooler;

[0030] At least one set of the carbon dioxide capture / calcination devices is operated in the carbon dioxide capture mode, while at least another set of the carbon dioxide capture / calcination devices is operated in the calcination mode, and the operating modes of each set of the carbon dioxide capture / calcination devices are alternately switched.

[0031] According to the operating mode of each group of carbon dioxide capture / calcination devices, by using the switching valve set on the gas outlet side of the corresponding primary cooler, the primary cooler corresponding to the carbon dioxide capture / calcination device in the carbon dioxide capture mode is connected to the high-temperature side inlet of the flue gas heat exchanger, and the primary cooler corresponding to the carbon dioxide capture / calcination device in the calcination mode is connected to the gas inlet of the particle separation component.

[0032] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0033] The present invention provides a carbon dioxide capture coupled with desulfurization wastewater concentration system and method for thermal power plants. By sequentially passing the desulfurization wastewater through a secondary cooler and a primary cooler, heat exchange is performed between the carbon dioxide-containing gas generated during calcination and the high-temperature gas output from the carbon dioxide capture / calcination device. This satisfies the cooling requirements of the aforementioned gases while simultaneously allowing the desulfurization wastewater to absorb the heat it carries and increase its temperature. The heated desulfurization wastewater is then transported to a wastewater concentration tower for concentration. This heat coupling between the gas cooling stage of the carbon dioxide capture and calcination process and the heating stage of the desulfurization wastewater concentration process reduces heat loss during high-temperature gas cooling and lowers the need for additional heat sources for desulfurization wastewater concentration. Simultaneously, in carbon dioxide capture mode, the decarbonized flue gas cooled by the primary cooler further exchanges heat with the clean desulfurized flue gas to be treated in a flue gas heat exchanger, further utilizing the remaining heat in the decarbonized flue gas. Therefore, the present invention can improve the synergy of heat utilization between carbon dioxide capture treatment and desulfurization wastewater concentration treatment, thereby improving the overall energy efficiency of the system. Attached Figure Description

[0034] Figure 1 The diagram shown is a schematic representation of a carbon dioxide capture coupled with desulfurization wastewater concentration system in a thermal power plant, according to one embodiment of the present invention.

[0035] In the diagram: 1. Desulfurization absorption tower; 2. Flue gas heat exchanger; 3. Flue gas booster fan; 4. Carbon dioxide capture / calcination device; 401. Heating resistor; 5. Primary cooler; 6. Switching valve; 7. Cyclone separator; 8. Bag filter; 9. Secondary cooler; 10. Impurity filter; 11. Carbon dioxide compressor; 12. Moisture absorption tower; 13. Carbon dioxide liquefaction unit; 14. Carbon dioxide purification tower; 15. Carbon dioxide storage tank; 16. Desulfurization wastewater filtration pond; 17. Wastewater transfer pump; 18. Air fan; 19. Wastewater concentration tower; 1901. Demister; 1902. Spray layer; 1903. Packing layer; 1904. Gas distribution disc; 1905. Concentrated wastewater discharge outlet; 20. Refrigeration unit; 21. Concentrated water transfer pump. Detailed Implementation

[0036] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0037] Example 1

[0038] like Figure 1As shown, this embodiment provides a carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants. This system can be installed in thermal power generating units that use wet desulfurization and are equipped with carbon dioxide capture devices. It is used to capture carbon dioxide from the desulfurized flue gas discharged from the desulfurization absorption tower 1, and at the same time, use the heat carried by the gas during the carbon dioxide capture and adsorbent calcination and regeneration process to heat the desulfurization wastewater, and use the heated desulfurization wastewater for concentration treatment.

[0039] In this embodiment, the system includes a desulfurization absorption tower 1, a flue gas heat exchanger 2, a flue gas booster fan 3, a carbon dioxide capture / calcination device 4, a primary cooler 5, a switching valve 6, a cyclone separator 7, a bag filter 8, a secondary cooler 9, an impurity filter 10, a carbon dioxide compressor 11, a moisture absorption tower 12, a carbon dioxide liquefaction unit 13, a carbon dioxide purification tower 14, a carbon dioxide storage tank 15, a desulfurization wastewater filtration pool 16, a wastewater transfer pump 17, an air fan 18, a wastewater concentration tower 19, a chiller 20, and a concentrated water transfer pump 21.

[0040] The carbon dioxide capture / calcination device 4 has a carbon dioxide capture mode and a calcination mode. The carbon dioxide capture mode is used to capture carbon dioxide in the flue gas using the reactants; the calcination mode is used to heat the reactants after carbon dioxide capture, so that they release carbon dioxide and regenerate the reactants.

[0041] In one specific embodiment, the reactants can be calcium-based reactants. For example, in carbon dioxide capture mode, calcium oxide reacts with carbon dioxide in flue gas to generate calcium carbonate, thereby reducing the carbon dioxide content in the flue gas; in calcination mode, the generated calcium carbonate is calcined at high temperature, causing the calcium carbonate to decompose, release carbon dioxide, and regenerate calcium oxide, thus realizing the recycling of calcium-based reactants.

[0042] like Figure 1 As shown, the clean flue gas outlet of the desulfurization absorption tower 1 is connected to the low-temperature side inlet of the flue gas heat exchanger 2, and the low-temperature side outlet of the flue gas heat exchanger 2 is connected to the carbon dioxide capture / calcination device 4 via the flue gas booster fan 3.

[0043] During the operation of the thermal power unit, the flue gas to be treated first undergoes desulfurization treatment in the desulfurization absorption tower 1. The desulfurized flue gas discharged from the desulfurization absorption tower 1 enters the low-temperature side of the flue gas heat exchanger 2. After absorbing the heat carried by the high-temperature side gas in the flue gas heat exchanger 2, the desulfurized flue gas is pressurized by the flue gas booster fan 3 and transported to the carbon dioxide capture / calcination device 4.

[0044] The flue gas booster fan 3 can be used to overcome the flow resistance generated by the flue gas heat exchanger 2, pipelines and carbon dioxide capture / calcination device 4, so that the desulfurized flue gas entering the carbon dioxide capture / calcination device 4 maintains a predetermined flow rate and pressure.

[0045] The gas outlet of the carbon dioxide capture / calcination device 4 is connected to the gas inlet of the primary cooler 5. The primary cooler 5 has a gas side and a cooling medium side for mutual heat exchange. The gas side is used to receive the gas output from the carbon dioxide capture / calcination device 4, and the cooling medium side is used to supply the desulfurization wastewater. Therefore, the primary cooler 5 is not only used to reduce the temperature of the gas output from the carbon dioxide capture / calcination device 4, but also to transfer the heat carried by the gas to the desulfurization wastewater.

[0046] Specifically, in the carbon dioxide capture mode, the desulfurized flue gas entering the carbon dioxide capture / calcination device 4 comes into contact with the calcium-based reactants, and at least part of the carbon dioxide in the flue gas is captured by the reactants, forming decarbonized flue gas after capture treatment.

[0047] The decarbonized flue gas enters the primary cooler 5 through the gas outlet of the carbon dioxide capture / calcination device 4, where it exchanges heat with the desulfurization wastewater flowing through the cooling medium side of the primary cooler 5. The temperature of the decarbonized flue gas decreases after releasing at least some of the heat, while the temperature of the desulfurization wastewater increases further after absorbing this heat.

[0048] In carbon dioxide capture mode, switching valve 6 switches the gas outlet of primary cooler 5 to connect with the high-temperature inlet of flue gas heat exchanger 2. Therefore, the decarbonized flue gas, after being initially cooled by primary cooler 5, further enters the high-temperature side of flue gas heat exchanger 2.

[0049] In the flue gas heat exchanger 2, the decarbonized flue gas exchanges heat with the desulfurized clean flue gas discharged from the desulfurization absorption tower 1 on the low-temperature side. The decarbonized flue gas further releases its remaining heat, while the desulfurized clean flue gas, awaiting entry into the carbon dioxide capture / calcination device 4, absorbs this heat and heats up. After heat exchange, the decarbonized flue gas returns to the desulfurization absorption tower 1 from the high-temperature side outlet of the flue gas heat exchanger 2 and is discharged through the exhaust passage of the desulfurization absorption tower 1.

[0050] Therefore, in the carbon dioxide capture mode, the heat carried by the decarbonized flue gas is utilized in two stages: firstly, the heat is transferred to the desulfurization wastewater through the primary cooler 5, providing heat for subsequent desulfurization wastewater concentration; secondly, the residual heat of the decarbonized flue gas is used by the flue gas heat exchanger 2 to heat the purified desulfurization flue gas to be entering the carbon dioxide capture / calcination device 4. Compared to directly cooling and discharging the decarbonized flue gas, the utilization rate of the heat from the decarbonized flue gas can be improved.

[0051] In calcination mode, the carbon dioxide capture / calcination device 4 does not capture carbon dioxide from the desulfurized flue gas, but instead calcines and regenerates the reactants in which carbon dioxide has already been captured. When multiple sets of carbon dioxide capture / calcination devices 4 are installed, the desulfurized flue gas to be treated can be transported to other carbon dioxide capture / calcination devices 4 in carbon dioxide capture mode, thereby enabling the carbon dioxide capture process and the reactant regeneration process to proceed in parallel.

[0052] In this embodiment, a heating resistor 401 is installed inside the carbon dioxide capture / calcination device 4. When energized, the heating resistor 401 generates heat, which heats the reactants inside the device to bring them to the temperature required for calcination and regeneration. In one specific embodiment, the calcination temperature can be set to approximately 950°C.

[0053] By installing a heating resistor 401 inside the carbon dioxide capture / calcination device 4, the reactants can be actively heated according to the different temperature requirements of the capture mode and the calcination mode. This allows the device to reach the calcination conditions more quickly when adsorbent regeneration is required, and facilitates the adjustment of the calcination temperature, which is beneficial for switching between the carbon dioxide capture mode and the calcination mode.

[0054] During calcination, calcium carbonate decomposes and releases high-temperature gas containing a high concentration of carbon dioxide, which is then regenerated into calcium oxide that can be used for carbon dioxide capture. The carbon dioxide-containing gas generated during calcination first enters the primary cooler 5 through the carbon dioxide capture / calcination device 4. The primary cooler 5 exchanges heat with the desulfurization wastewater, causing the high-temperature carbon dioxide-containing gas to release heat and initially cool down, while the desulfurization wastewater absorbs heat.

[0055] Under a specific operating condition, the carbon dioxide-containing gas produced by calcination enters the primary cooler 5 at a relatively high temperature. After heat exchange with the desulfurization wastewater in the primary cooler 5, its temperature can be reduced to approximately 120°C. The carbon dioxide-containing gas, after initial cooling in the primary cooler 5, then passes through the cyclone separator 7 and the bag filter 8 for particle separation, and enters the secondary cooler 9 for further cooling.

[0056] At this time, switching valve 6 switches the gas outlet of primary cooler 5 from the gas path of flue gas heat exchanger 2 to the gas path of particle separation component, so that the gas outlet of primary cooler 5 is connected to the gas inlet of cyclone separator 7.

[0057] Therefore, by setting the switching valve 6, the corresponding gas treatment path can be selected according to the actual operating mode of the carbon dioxide capture / calcination device 4. The decarbonized flue gas generated in the capture mode is guided to the flue gas heat exchanger 2 to further recover its heat; the carbon dioxide-containing gas generated in the calcination mode is guided to the particle separation and carbon dioxide post-treatment path. This avoids two gases with different properties entering incompatible treatment processes, and allows the gases generated in different modes to be treated according to their respective subsequent treatment requirements.

[0058] In this embodiment, the particle separation component includes a cyclone separator 7 and a bag filter 8 connected in sequence.

[0059] The carbon dioxide-containing gas output from the primary cooler 5 first enters the cyclone separator 7. Since some calcium-based solid particles may flow out with the gas during the calcination process, the cyclone separator 7 can separate the relatively large solid particles in the gas. After preliminary separation by the cyclone separator 7, the carbon dioxide-containing gas further enters the bag filter 8 for further filtration of the finer particles entrained therein.

[0060] By using a cyclone separator 7 and a bag filter 8 for graded particle separation, the content of solid particles in the subsequent airflow can be reduced, and the amount of solid particles entering subsequent equipment such as the secondary cooler 9 and the carbon dioxide compressor 11 can be reduced, which helps to improve the operational stability of subsequent carbon dioxide treatment equipment.

[0061] The carbon dioxide-containing gas, after being treated by the bag filter 8, enters the secondary cooler 9. The secondary cooler 9 also has a gas side and a cooling medium side, wherein the gas side is used for the carbon dioxide-containing gas after particle separation, and the cooling medium side is used for the desulfurization wastewater after filtration.

[0062] In one embodiment, the carbon dioxide-containing gas, after initial cooling and particle separation by the primary cooler 5, enters the secondary cooler 9 at approximately 120°C. After heat exchange with the desulfurization wastewater in the secondary cooler 9, it can be further cooled to approximately 40°C. The desulfurization wastewater used for heat exchange is filtered by the desulfurization wastewater filter pond 16 and retained for a certain period of time, so its temperature before entering the secondary cooler 9 can be, for example, approximately 35°C to 40°C.

[0063] The heat exchange process can be adjusted based on the flow rate of carbon dioxide-containing gas, the flow rate of desulfurization wastewater, and the heat exchange capacity of the secondary cooler 9, so that the carbon dioxide-containing gas reaches the temperature required for subsequent treatment without the introduction of additional cooling water. In actual operation, the above temperature parameters can be adaptively adjusted according to the system operating conditions.

[0064] After being further cooled by the secondary cooler 9, the carbon dioxide-containing gas sequentially enters the impurity filter 10, the carbon dioxide compressor 11, the moisture absorption tower 12, the carbon dioxide liquefaction unit 13, the carbon dioxide purification tower 14, and the carbon dioxide storage tank 15.

[0065] The impurity filter 10 is used to further remove impurities from the carbon dioxide-containing gas; the carbon dioxide compressor 11 is used to compress the gas and increase the carbon dioxide gas pressure; the moisture absorption tower 12 is used to remove moisture from the gas; the carbon dioxide liquefaction unit 13 is used to bring the compressed and dehydrated carbon dioxide to the temperature required for liquefaction; the carbon dioxide purification tower 14 is used to further remove non-target components from the carbon dioxide; and the processed carbon dioxide is finally stored in the carbon dioxide storage tank 15.

[0066] Through the above-mentioned particle separation, impurity filtration, compression, dehydration, liquefaction and purification processes, the impact of particles, moisture and other impurities in the calcination gas on subsequent processing can be reduced, and carbon dioxide that is easy to store and utilize can be obtained.

[0067] Furthermore, such as Figure 1 As shown, this embodiment also includes an ice chiller 20. A cooling medium circulation loop is formed between the ice chiller 20, the carbon dioxide liquefaction unit 13, and the carbon dioxide purification tower 14.

[0068] Specifically, the cooling medium cooled by the ice machine 20 is first transported to the carbon dioxide liquefaction unit 13 to provide cooling for the carbon dioxide liquefaction process; the cooling medium flowing out of the carbon dioxide liquefaction unit 13 further enters the carbon dioxide purification tower 14 to provide the required low temperature conditions for the carbon dioxide purification process, and then returns to the ice machine 20 for cooling, thus forming a cycle of "ice machine 20 → carbon dioxide liquefaction unit 13 → carbon dioxide purification tower 14 → ice machine 20".

[0069] In one specific embodiment, the cooling medium can be a modified diol. By setting up the above-mentioned circulating cooling loop, the same cooling medium can be circulated among the ice machine 20, the carbon dioxide liquefaction unit 13, and the carbon dioxide purification tower 14, reducing the need for continuous replenishment of the cooling medium. At the same time, the ice machine 20 uniformly restores the low temperature state of the cooling medium, which is beneficial to maintaining the stability of the cooling conditions required for the carbon dioxide liquefaction and purification process.

[0070] The treatment pathway for desulfurization wastewater is explained further below.

[0071] like Figure 1As shown, the desulfurization absorption tower 1 is connected to the desulfurization wastewater filtration tank 16. The desulfurization wastewater generated during the operation of the desulfurization absorption tower 1 is discharged into the desulfurization wastewater filtration tank 16. The desulfurization wastewater filtration tank 16 is used to remove some suspended impurities and larger particles from the desulfurization wastewater to reduce the possibility of blockage in subsequent conveying pipelines and heat exchange equipment.

[0072] The desulfurization wastewater, after being filtered by the desulfurization wastewater filtration tank 16, is pressurized and transported by the wastewater transfer pump 17. According to the process path determined in this embodiment, the desulfurization wastewater first enters the cooling medium side of the secondary cooler 9, then enters the cooling medium side of the primary cooler 5 from the secondary cooler 9, and finally is transported to the wastewater concentration tower 19 from the primary cooler 5.

[0073] In the secondary cooler 9, the relatively low-temperature desulfurization wastewater first exchanges heat with the carbon dioxide-containing gas after particle separation. After absorbing the heat released by the carbon dioxide-containing gas, the temperature of the desulfurization wastewater rises. For example, the temperature of the desulfurization wastewater before entering the secondary cooler 9 may be approximately 35℃ to 40℃, which can rise to approximately 50℃ to 60℃ after heat exchange.

[0074] After the first stage of heating is completed, the desulfurization wastewater continues to enter the first stage cooler 5, where it exchanges heat with the gas with a higher temperature output from the carbon dioxide capture / calcination device 4, allowing the desulfurization wastewater to further absorb heat from the high-temperature gas and increase its temperature.

[0075] Under specific operating conditions, depending on the operating mode of the carbon dioxide capture / calcination device 4, the temperature of the gas processed by the primary cooler 5 can also vary, for example, ranging from approximately 650°C to 950°C. After the desulfurization wastewater undergoes preliminary heat exchange and temperature increase in the secondary cooler 9, it then enters the primary cooler 5 to absorb heat from the high-temperature gas, further raising the temperature of the desulfurization wastewater to approximately 60°C to 100°C or higher. The total heat absorbed by the desulfurization wastewater during the two-stage heat exchange process can, for example, reach approximately 200kW to 300kW.

[0076] Therefore, under a specific operating condition, the desulfurization wastewater can enter the secondary cooler 9 at approximately 35°C to 40°C, where it exchanges heat with carbon dioxide-containing gas to reach approximately 50°C to 60°C. It then enters the primary cooler 5 to further absorb heat from the high-temperature gas output from the carbon dioxide capture / calcination device 4, further raising its temperature to approximately 60°C to 100°C or higher. Through this stepped heat exchange method, the heat carried by gases at different temperature levels can be sequentially transferred to the desulfurization wastewater.

[0077] It should be noted that the above-mentioned temperatures and heat exchange rates are used to illustrate a specific operating condition and do not constitute a limitation of the present invention. In actual operation, the corresponding operating parameters can be adjusted according to the flue gas volume, the flow rate of carbon dioxide-containing gas, the flow rate of desulfurization wastewater, and the temperature required for wastewater concentration.

[0078] By having the desulfurization wastewater first absorb heat from the relatively low-temperature carbon dioxide-containing gas in the secondary cooler 9, and then further absorb heat from the high-temperature gas in the primary cooler 5, a tiered heat exchange path matching heat sources of different temperature levels can be formed. This satisfies the cooling requirements of both the carbon dioxide-containing gas and the high-temperature flue gas, while simultaneously increasing the temperature of the desulfurization wastewater step by step. This transfers the waste heat from the gases that would otherwise need to be released to the desulfurization wastewater, providing heat for subsequent concentration and reducing the need for additional heat sources during wastewater concentration.

[0079] After further heat exchange and temperature increase in the primary cooler 5, the desulfurized wastewater enters the wastewater concentration tower 19.

[0080] like Figure 1 As shown, the wastewater concentration tower 19 is provided with a gas distribution disk 1904, a packing layer 1903, a spray layer 1902 and a demister 1901 arranged sequentially from bottom to top inside.

[0081] Air blower 18 is connected to gas distribution disk 1904 at the bottom of wastewater thickening tower 19. During operation, air blower 18 delivers outside air to gas distribution disk 1904, which distributes the air entering wastewater thickening tower 19 along the cross-section of the tower body, causing the air to flow upward into the packing layer 1903.

[0082] The spray layer 1902 is located above the packing layer 1903 and is connected to the cooling medium outlet of the primary cooler 5. The desulfurization wastewater, after being absorbed by the secondary cooler 9 and the primary cooler 5 in stages, enters the spray layer 1902, where it is dispersed and atomized to form droplets that then flow downwards into the packing layer 1903.

[0083] Therefore, in the packing layer 1903, the air generally flows from bottom to top, while the desulfurization wastewater flows from top to bottom, forming a countercurrent contact. The packing layer 1903 can increase the gas-liquid contact area and contact time, allowing the air and the heated desulfurization wastewater to fully exchange heat and mass.

[0084] Since the desulfurization wastewater entering the wastewater concentration tower 19 has absorbed the heat carried by the high-temperature gas through the secondary cooler 9 and the primary cooler 5, it has a high temperature. When the desulfurization wastewater comes into contact with air, some of the water evaporates and enters the air, reducing the water content in the desulfurization wastewater while increasing the concentration of non-volatile components such as salts, thereby achieving the concentration of the desulfurization wastewater.

[0085] Under specific operating conditions, the ambient air temperature supplied to the wastewater concentration tower 19 by the air fan 18 can be approximately 25°C, and the relative humidity can be approximately 60%. After being evenly distributed by the gas distribution disk 1904, the air comes into countercurrent contact with the heated desulfurization wastewater. During the gas-liquid heat and mass transfer process, the air temperature and moisture content gradually increase. The gas temperature inside the wastewater concentration tower 19 can reach, for example, approximately 40°C to 50°C, and the relative humidity can reach over 90%, thereby promoting the transfer of moisture from the desulfurization wastewater into the air.

[0086] By setting up the gas distribution disk 1904, the distribution of air entering the packing layer 1903 on the cross-section of the tower can be improved, local airflow concentration can be reduced, and the air can have more sufficient contact with the desulfurization wastewater sprayed down. By setting up the packing layer 1903, the effective gas-liquid contact area can be further increased, thereby improving the efficiency of water transfer from the desulfurization wastewater to the air.

[0087] After contacting the desulfurization wastewater, the air continues to flow towards the top of the wastewater concentration tower 19. During the airflow, some fine desulfurization wastewater droplets may be entrained. Therefore, a demister 1901 is installed at the top of the wastewater concentration tower 19.

[0088] The demister 1901 intercepts droplets entrained in the rising air, causing the intercepted droplets to fall back into the wastewater concentration tower 19, thereby reducing the amount of wastewater droplets carried out with the air.

[0089] The air treated by the demister 1901 is transported from the gas outlet of the wastewater concentration tower 19 to the desulfurization absorption tower 1, and discharged through the exhaust passage of the desulfurization absorption tower 1.

[0090] In this way, on the one hand, the demister 1901 can reduce the amount of concentrated wastewater droplets carried into the desulfurization absorption tower 1 by the airflow, and on the other hand, the humid air generated by the wastewater concentration tower 19 can be uniformly sent back to the flue gas treatment system where the desulfurization absorption tower 1 is located, without the need to set up a separate concentrated tail gas emission path, which is conducive to the integration of system processes.

[0091] Furthermore, a storage area for collecting concentrated desulfurization wastewater is formed at the bottom of the wastewater thickening tower 19. The bottom of the wastewater thickening tower 19 is connected to the inlet of the concentrate transfer pump 21, and the outlet of the concentrate transfer pump 21 is connected to the spray layer 1902 via the thickening tower header.

[0092] The concentrated desulfurization wastewater at the bottom of the wastewater concentration tower 19 is transported again to the spray layer 1902 by the concentrated water transfer pump 21, and after being atomized again by the spray layer 1902, it enters the packing layer 1903 and comes into countercurrent contact with the air entering from the gas distribution disk 1904.

[0093] Through the above cycle, the same part of desulfurization wastewater can repeatedly undergo the processes of spraying, gas-liquid contact and water evaporation, thereby extending the effective concentration time of the desulfurization wastewater in the wastewater concentration tower 19 and gradually increasing the concentration of non-volatile components.

[0094] The main pipe of the thickening tower connected to the concentrated water transfer pump 21 is specifically connected to the spray layer 1902, and the bottom of the wastewater thickening tower 19 is also provided with a concentrated wastewater discharge port 1905.

[0095] In this embodiment, the preset concentration conditions can be determined based on the salt content and / or volume reduction of the concentrated desulfurization wastewater. For example, a salt content threshold and / or a volume reduction threshold can be preset, wherein the salt content threshold can be set to a value within the range of 80,000 mg / L to 120,000 mg / L according to actual treatment requirements, and the volume reduction threshold can be set to a value within the range of 50% to 70%. When the salt content of the concentrated desulfurization wastewater reaches the corresponding salt content threshold, and / or the volume reduction of the desulfurization wastewater reaches the corresponding volume reduction threshold, it can be determined that the concentrated desulfurization wastewater meets the preset concentration conditions. The above thresholds can be adjusted according to the requirements of subsequent crystallization, solid-liquid separation, or other treatment processes.

[0096] When the concentrated desulfurization wastewater at the bottom of the wastewater concentration tower 19 has not yet met the preset concentration conditions, it can continue to be sent back to the spray layer 1902 for circulation concentration by the concentrated water transfer pump 21; when the concentrated desulfurization wastewater meets the preset concentration conditions, at least part of the concentrated desulfurization wastewater can be discharged through the concentrated wastewater discharge port 1905 for subsequent utilization, crystallization or other treatment.

[0097] Therefore, the circulating spray path formed by the concentrated water transfer pump 21 can concentrate the desulfurization wastewater in the tower multiple times without continuously increasing the flow rate of fresh wastewater, thereby improving the degree of wastewater concentration; at the same time, the concentrated wastewater after reaching the concentration requirements can be discharged through the concentrated wastewater discharge port 1905, so that the circulating concentration and the finished product discharge can be carried out in a coordinated manner.

[0098] Furthermore, it should be noted that, Figure 1 This mainly illustrates the connection relationship between the single-unit carbon dioxide capture / calcination unit 4 and its corresponding primary cooler 5, clearly showing the process connections between the various devices. In practical applications, it can be followed... Figure 1 The connection shown indicates that at least two sets of carbon dioxide capture / calcination devices 4 are installed, and each set of carbon dioxide capture / calcination devices 4 is equipped with a corresponding primary cooler 5. Each set of carbon dioxide capture / calcination devices 4 and its corresponding primary cooler 5 form an independent gas processing branch.

[0099] When multiple sets of primary coolers 5 are set up, the gas side of each primary cooler 5 belongs to the corresponding gas processing branch, and the cooling medium side of each primary cooler 5 can be connected to the desulfurization wastewater heat exchange circuit so as to use the high temperature gas in the corresponding gas processing branch to heat the desulfurization wastewater.

[0100] Taking the setting of two sets of carbon dioxide capture / calcination devices 4 as an example, in the first operation stage, the first set of carbon dioxide capture / calcination devices 4 can be put into carbon dioxide capture mode, while the second set of carbon dioxide capture / calcination devices 4 can be put into calcination mode.

[0101] The first set of carbon dioxide capture / calcination devices 4 uses the regenerated reaction materials to capture carbon dioxide in the desulfurized flue gas. The decarbonized flue gas output is cooled by the first-stage cooler 5 corresponding to the first set of devices, and then enters the high-temperature side of the flue gas heat exchanger 2 through the corresponding switching valve 6.

[0102] Meanwhile, the second carbon dioxide capture / calcination device 4 uses a heating resistor 401 to calcine and regenerate the reactants that have already captured carbon dioxide. The carbon dioxide-containing gas produced is cooled by the first-stage cooler 5 corresponding to the second device and then enters the cyclone separator 7 through the corresponding switching valve 6 to continue subsequent particle separation, cooling, purification and carbon dioxide recovery.

[0103] When the reactants in the first set of carbon dioxide capture / calcination devices 4 reach the state requiring regeneration, and the second set of carbon dioxide capture / calcination devices 4 completes the regeneration of the reactants, the operating modes of the two sets of devices can be switched, so that the first set of devices enters the calcination mode and the second set of devices enters the carbon dioxide capture mode.

[0104] By alternating the operation of two or more sets of carbon dioxide capture / calcination devices 4, carbon dioxide capture can continue while one set is calcining and regenerating the reactants. This reduces interruptions in the carbon dioxide capture process caused by adsorbent regeneration and improves the system's continuous operation capability. Simultaneously, each set of devices is equipped with an independent primary cooler 5 and a gas processing branch, allowing gases generated in different operating modes to enter their respective gas processing paths during switching, reducing the possibility of cross-flow between different gases.

[0105] Example 2

[0106] Based on the carbon dioxide capture coupled with desulfurization wastewater concentration system of thermal power plant described in Example 1, this embodiment also provides a method for carbon dioxide capture coupled with desulfurization wastewater concentration in thermal power plant, which may include the following process.

[0107] First, the desulfurized flue gas discharged from the desulfurization absorption tower 1 is transported to the low-temperature side of the flue gas heat exchanger 2. After absorbing the heat of the decarbonized flue gas on the high-temperature side in the flue gas heat exchanger 2, it is transported to the carbon dioxide capture / calcination device 4, which is in carbon dioxide capture mode, by the flue gas booster fan 3.

[0108] In the carbon dioxide capture mode, carbon dioxide in the desulfurized flue gas is captured by the reactants in the carbon dioxide capture / calcination device 4. The resulting decarbonized flue gas enters the primary cooler 5 and exchanges heat with the desulfurization wastewater flowing through the primary cooler 5. The decarbonized flue gas, cooled by the primary cooler 5, then enters the high-temperature side of the flue gas heat exchanger 2 and exchanges heat with the newly entering low-temperature desulfurized flue gas. After completing the heat exchange, it returns to the desulfurization absorption tower 1.

[0109] In calcination mode, the reactants in the carbon dioxide capture / calcination device 4 are heated by heating resistor 401 to regenerate them through calcination. The high-temperature carbon dioxide-containing gas generated during calcination enters the primary cooler 5 for initial heat exchange and cooling. After passing through the switching valve 6, it is guided to the cyclone separator 7 and bag filter 8 for particle separation. Then, it enters the secondary cooler 9 for further heat exchange and cooling. Subsequently, it passes through the impurity filter 10, carbon dioxide compressor 11, moisture absorption tower 12, carbon dioxide liquefaction unit 13, carbon dioxide purification tower 14, and carbon dioxide storage tank 15 for appropriate processing.

[0110] Meanwhile, the desulfurization wastewater discharged from the desulfurization absorption tower 1 is sent to the desulfurization wastewater filtration pond 16 for filtration, and then the wastewater is first sent to the secondary cooler 9 by the wastewater transfer pump 17, so that the desulfurization wastewater absorbs the heat released by the carbon dioxide-containing gas after particle separation; then the desulfurization wastewater is sent to the primary cooler 5, so that the desulfurization wastewater further absorbs the heat of the high-temperature gas output by the carbon dioxide capture / calcination device 4.

[0111] After being heated through the above-mentioned staged heat exchange, the desulfurization wastewater enters the wastewater concentration tower 19 and is sprayed by the spray layer 1902. The air fan 18 transports outside air through the gas distribution disk 1904 to the packing layer 1903, so that the air flows from bottom to top and comes into countercurrent contact with the desulfurization wastewater flowing from top to bottom, causing some of the water in the desulfurization wastewater to evaporate and enter the air.

[0112] After contact, the air is returned to the desulfurization absorption tower 1 after the demister 1901 removes any entrained droplets. The concentrated desulfurization wastewater collected at the bottom of the wastewater concentration tower 19 is then pumped back to the spray layer 1902 by the concentrate transfer pump 21 for circulating spraying and concentration. After meeting the preset concentration conditions, it is discharged through the concentrated wastewater discharge port 1905. The preset concentration conditions can be determined based on the salt content and / or volume reduction of the concentrated desulfurization wastewater, as detailed in the relevant description in Example 1.

[0113] Furthermore, when the system is equipped with at least two sets of carbon dioxide capture / calcination devices 4, at least one set of devices can operate in carbon dioxide capture mode while at least another set of devices operates in calcination mode, and the operating modes can be switched alternately according to the operating status of each set of devices. For the device in carbon dioxide capture mode, the gas outlet of the corresponding primary cooler 5 is switched to the flue gas heat exchanger 2 by switching valve 6; for the device in calcination mode, the gas outlet of the corresponding primary cooler 5 is switched to the particle separation processing path where the cyclone separator 7 is located by switching valve 6.

[0114] By adopting the above method, on the one hand, multiple sets of carbon dioxide capture / calcination devices 4 can be operated alternately, so that the carbon dioxide capture process and the reactant regeneration process can be carried out in parallel, reducing the impact of the regeneration of a single device on the overall capture continuity; on the other hand, the generated gas can be introduced into the corresponding treatment path according to different operating modes, and the heat released by the gas at different temperature levels can be transferred to the desulfurization wastewater in sequence, so that carbon dioxide capture, adsorbent regeneration, gas cooling and desulfurization wastewater concentration form an interconnected process flow.

[0115] In summary, this embodiment does not use a separate external heat source to heat the desulfurization wastewater. Instead, the desulfurization wastewater participates in the cooling process of carbon dioxide capture and calcination gas. The heat that would otherwise need to be discharged is absorbed step by step through the secondary cooler 9 and the primary cooler 5. The desulfurization wastewater after absorbing this heat is then used for evaporation and concentration, thereby achieving the coupling between the gas cooling demand and the wastewater concentration heat demand. At the same time, the residual heat of the decarbonization flue gas in the capture mode is further utilized through the flue gas heat exchanger 2, thereby improving the heat utilization synergy between the carbon dioxide capture treatment and the desulfurization wastewater concentration treatment in the thermal power plant and reducing the additional energy consumption of the entire treatment process.

[0116] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants, characterized in that, include: Desulfurization absorption tower, flue gas heat exchanger, carbon dioxide capture / calcination device, primary cooler, secondary cooler, particle separation component, desulfurization wastewater filtration tank, wastewater transfer pump and wastewater concentration tower; The clean flue gas outlet of the desulfurization absorption tower is connected to the carbon dioxide capture / calcination device via the low-temperature side of the flue gas heat exchanger. The carbon dioxide capture / calcination device has a carbon dioxide capture mode and a calcination mode. The gas outlet of the carbon dioxide capture / calcination device is connected to the gas inlet of the primary cooler. In the carbon dioxide capture mode, the gas outlet of the primary cooler is connected to the high-temperature side inlet of the flue gas heat exchanger, and the high-temperature side outlet of the flue gas heat exchanger is connected to the desulfurization absorption tower, so that the decarbonized flue gas output from the carbon dioxide capture / calcination device is cooled by the primary cooler, and then exchanges heat with the desulfurized clean flue gas output from the desulfurization absorption tower in the flue gas heat exchanger, and returns to the desulfurization absorption tower after heat exchange. In the calcination mode, the gas outlet of the primary cooler is connected to the gas inlet of the secondary cooler through the particle separation component, so as to separate and cool the carbon dioxide-containing gas generated during calcination. The desulfurization absorption tower is connected to the desulfurization wastewater filtration tank. The desulfurization wastewater filtration tank is connected to the cooling medium inlet of the secondary cooler via the wastewater transfer pump. The cooling medium outlet of the secondary cooler is connected to the cooling medium inlet of the primary cooler. The cooling medium outlet of the primary cooler is connected to the wastewater concentration tower, so that the desulfurization wastewater flows sequentially through the secondary cooler and the primary cooler for heat exchange and temperature increase before entering the wastewater concentration tower for concentration.

2. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 1, characterized in that, The system includes at least two sets of carbon dioxide capture / calcination devices and a primary cooler corresponding to each set of carbon dioxide capture / calcination devices. The gas outlet of each set of carbon dioxide capture / calcination devices is connected to the gas inlet of the corresponding primary cooler, so that each set of carbon dioxide capture / calcination devices and its corresponding primary cooler form independent gas processing branches. Each group of carbon dioxide capture / calcination devices is used to alternate between the carbon dioxide capture mode and the calcination mode, so that different groups of carbon dioxide capture / calcination devices can perform carbon dioxide capture and calcination regeneration respectively.

3. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 1, characterized in that, The carbon dioxide capture / calcination device is equipped with a heating resistor, which is used to heat the reactants in the carbon dioxide capture / calcination device to adjust the reaction temperature of the carbon dioxide capture / calcination device.

4. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 1, characterized in that, It also includes a switching valve located on the gas outlet side of the primary cooler, the switching valve being used to selectively connect the gas outlet of the primary cooler to one of the high-temperature side inlet of the flue gas heat exchanger and the gas inlet of the particulate separation component, depending on the operating mode of the carbon dioxide capture / calcination device.

5. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 1, characterized in that, The particle separation assembly includes a cyclone separator and a bag filter connected in sequence. The secondary cooler, impurity filter, carbon dioxide compressor, moisture absorption tower, carbon dioxide liquefaction unit, carbon dioxide purification tower, and carbon dioxide storage tank are connected in sequence.

6. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 5, characterized in that, It also includes a chiller, wherein the chiller, the carbon dioxide liquefaction unit and the carbon dioxide purification tower are connected in sequence to form a cooling medium circulation loop, and the cooling medium output by the chiller flows through the carbon dioxide liquefaction unit and the carbon dioxide purification tower in sequence before returning to the chiller.

7. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 1, characterized in that, The wastewater concentration tower includes a gas distribution disk, a packing layer, a spray layer, and a demister arranged from bottom to top; The gas distribution disk is connected to the air fan so as to evenly distribute the air delivered by the air fan and then send it into the packing layer; The spray layer is connected to the cooling medium outlet of the primary cooler so that the desulfurization wastewater after absorbing heat is atomized by the spray layer and enters the packing layer, and comes into countercurrent contact with the air entering the packing layer. The demister is used to remove wastewater droplets entrained in the air. The gas outlet of the wastewater concentration tower is connected to the desulfurization absorption tower so as to transport the air treated by the demister to the desulfurization absorption tower.

8. The carbon dioxide capture coupled with desulfurization wastewater concentration system for thermal power plants according to claim 7, characterized in that, The bottom of the wastewater thickening tower is connected to the inlet of the concentrated water transfer pump, and the outlet of the concentrated water transfer pump is connected to the spray layer, so as to transport the concentrated desulfurization wastewater at the bottom of the wastewater thickening tower to the spray layer for circulating spraying and circulating concentration; the bottom of the wastewater thickening tower is also provided with a concentrated wastewater discharge port for discharging the concentrated desulfurization wastewater.

9. A method for concentrating desulfurization wastewater coupled with carbon dioxide capture in a thermal power plant, characterized in that, include: The desulfurized flue gas discharged from the desulfurization absorption tower is transported to the carbon dioxide capture / calcination unit via the low-temperature side of the flue gas heat exchanger. In the carbon dioxide capture mode, carbon dioxide in the desulfurized flue gas is captured by the carbon dioxide capture / calcination device, and the decarbonized flue gas output from the carbon dioxide capture / calcination device flows sequentially through the high-temperature side of the primary cooler and the flue gas heat exchanger. After the decarbonized flue gas is cooled by heat exchange in the primary cooler, it exchanges heat with the desulfurized flue gas in the flue gas heat exchanger and returns to the desulfurization absorption tower after heat exchange. In the calcination mode, the reactants in the carbon dioxide capture / calcination device are calcined and regenerated, and the carbon dioxide-containing gas generated by calcination flows sequentially through the primary cooler, the particle separation component and the secondary cooler to perform heat exchange, cooling, particle separation and further cooling of the carbon dioxide-containing gas. The desulfurization wastewater discharged from the desulfurization absorption tower is sent to the desulfurization wastewater filtration tank for filtration, and then sequentially transported by the wastewater transfer pump to the secondary cooler and the primary cooler, so that the desulfurization wastewater absorbs the heat of the gas flowing through the secondary cooler and the primary cooler respectively, and the desulfurization wastewater after heat exchange and temperature increase is transported to the wastewater concentration tower. Outside air is evenly distributed by a gas distribution disc through an air fan and then sent into the packing layer. The desulfurization wastewater, after heat exchange and heating, is atomized by a spray layer and sprayed into the packing layer, so that the outside air and the desulfurization wastewater come into countercurrent contact in the packing layer. This allows some of the water in the desulfurization wastewater to evaporate and enter the outside air. The air that has come into contact with the desulfurization wastewater is then demisted by a demister and sent to the desulfurization absorption tower. The concentrated desulfurization wastewater at the bottom of the wastewater concentration tower is returned to the spray layer via a concentrated water transfer pump for circulating spraying and circulating concentration. After the concentrated desulfurization wastewater meets the preset concentration conditions, at least a portion of the concentrated desulfurization wastewater is discharged through the concentrated wastewater discharge outlet.

10. The method for concentrating carbon dioxide capture coupled with desulfurization wastewater from a thermal power plant according to claim 9, characterized in that, At least two sets of the carbon dioxide capture / calcination devices are provided, and each set of the carbon dioxide capture / calcination devices is equipped with a corresponding primary cooler; At least one set of the carbon dioxide capture / calcination devices is operated in the carbon dioxide capture mode, while at least another set of the carbon dioxide capture / calcination devices is operated in the calcination mode, and the operating modes of each set of the carbon dioxide capture / calcination devices are alternately switched. According to the operating mode of each group of carbon dioxide capture / calcination devices, by using the switching valve set on the gas outlet side of the corresponding primary cooler, the primary cooler corresponding to the carbon dioxide capture / calcination device in the carbon dioxide capture mode is connected to the high-temperature side inlet of the flue gas heat exchanger, and the primary cooler corresponding to the carbon dioxide capture / calcination device in the calcination mode is connected to the gas inlet of the particle separation component.

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