Flue gas carbon capture system and method

Abstract

The invention relates to the technical field of flue gas carbon capture, and discloses a flue gas carbon capture system and method.The flue gas carbon capture system comprises a desulfurization tower, an absorption tower, a first condenser, a barren liquor and rich liquor heat exchanger, a desorption tower, a separator, a second condenser, a compressor, a reboiler, a barren liquor storage tank, a rich liquor storage tank, a first valve and a second valve; in the peak period of power demand, the system preferentially utilizes liquid in the barren liquor storage tank to absorb CO2, continuous and efficient operation of the absorption tower is ensured, the rich liquor storage tank allows the system to temporarily store the liquid when the absorption tower generates rich liquor, treatment is performed when the demand is low, and energy utilization is effectively balanced. When the liquid level of the barren liquor storage tank is lower than a preset value, the system is automatically switched to the desorption tower, CO2 in the rich liquor is released in a low-demand period, the absorption capacity is recovered, and the energy consumption is minimized.

Description

Technical Field

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

[0002] Global warming is a global problem that cannot be ignored. It is changing our climate patterns at an unprecedented rate, causing profound impacts on ecosystems and the environment. As the earth's temperature rises, extreme weather events become more frequent, sea levels rise, glaciers melt, and biodiversity is threatened. These changes pose serious challenges to human society and economic activities. Among the many greenhouse gases, carbon dioxide CO 2 Because of its high concentration and long life in the atmosphere, its impact on global warming is particularly significant.

[0003] However, considering the continued growth of global energy demand and the limitations of renewable energy, large-scale CO reduction may not be achieved in a short period of time by simply improving energy efficiency and developing renewable energy. 2 Therefore, carbon capture technology is considered to be an effective supplementary means. Carbon capture technology can capture CO in the flue gas emitted by coal-fired power plants. 2 , which is then transported and safely stored, thereby reducing greenhouse gas concentrations in the atmosphere. This technology not only helps reduce CO2 emissions from coal-fired power plants, 2 It has contributed to addressing climate change, reduced emissions, and promoted the transformation of the global energy structure and sustainable economic development.

[0004] Chemical absorption is a technology widely used in capturing carbon dioxide from industrial flue gas. It uses alcohol amine chemical solvents (lean liquid) to achieve CO 2 In this process, the flue gas is first pre-treated to remove impurities and then comes into contact with the sprayed alcohol amine solvent in the absorption tower. 2 The CO2-rich 2 The solvent (rich liquid) is sent to the regeneration tower, where CO is released under heating and depressurization conditions. 2 , while the solvent is regenerated and recycled. Thus, CO2 is captured. This method is relatively mature in industrial application, but it may face the problems of high energy consumption and solvent degradation.

[0005] Since the existing carbon capture system has fixed energy consumption and captures CO 2 The energy consumption generated during the operation accounts for a part of the generated power, which results in the power plant being limited in terms of the upper and lower limits of net output power. 2The amount of electricity generated cannot be adjusted flexibly, but is affected by the total power output. During peak electricity demand, the energy consumption of carbon capture increases due to the need to process a large amount of carbon-containing flue gas, thereby reducing the net output of the power plant, which is in conflict with electricity demand; while during low electricity demand, carbon emissions are less, resulting in a waste of energy and resources. Summary of the invention

[0006] In view of the above problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the present invention aims to provide a flue gas carbon capture system, the purpose of which is to:

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions: a flue gas carbon capture system, comprising a desulfurization tower, an absorption tower, a first condenser, a lean and rich liquid heat exchanger, a desorption tower, a separator, a second condenser, a compressor, a reboiler, a lean liquid storage tank, a rich liquid storage tank, a first valve and a second valve;

[0009] Among them, the output end of the desulfurization tower is connected to the input end of the absorption tower, the top of the absorption tower is provided with a decarbonized flue gas exhaust outlet, the absorption tower is connected to the lean-rich liquid heat exchanger, the lean-rich liquid heat exchanger is connected to the analysis tower, and the lean-rich liquid heat exchanger is connected to the reboiler.

[0010] As a preferred solution of the flue gas carbon capture system of the present invention, the output end of the first condenser is connected to the lean liquid input end of the absorption tower, and the first condenser is used for cooling, recovering and supplying the lean liquid into the absorption tower.

[0011] As a preferred embodiment of the flue gas carbon capture system of the present invention, the analytical tower is connected to the separator, the separator is connected to the second condenser, the second condenser is connected to the compressor, and the separator and the second condenser are used to analyze the CO 2 Separation and cooling are performed, and the CO 2 To liquefy.

[0012] As a preferred solution of the flue gas carbon capture system of the present invention, the reboiler is connected to the decomposition tower, and the reboiler provides steam for the decomposition tower.

[0013] As a preferred solution of the flue gas carbon capture system of the present invention, the lean liquid storage tank is connected between the first condenser and the lean liquid input end of the absorption tower through the first valve.

[0014] As a preferred solution of the flue gas carbon capture system of the present invention, the rich liquid storage tank is connected between the lean-rich liquid heat exchanger and the rich liquid output end of the absorption tower through the second valve.

[0015] As a preferred solution of the flue gas carbon capture system of the present invention, the other end of the first condenser is connected to the liquid supply through a mixer, the lean liquid output end of the lean-rich liquid heat exchanger is connected to the mixer, and the mixer is used to mix the lean liquid output from the lean-rich liquid heat exchanger with supplementary water and supplementary absorbent;

[0016] The flue gas input end of the absorption tower is located at the lower end of the outer side of the absorption tower, and the lean liquid input end of the absorption tower is located at the upper end of the outer side of the absorption tower, so as to realize the countercurrent contact between the carbon-containing flue gas and the lean liquid.

[0017] As a preferred solution of the flue gas carbon capture system of the present invention, wherein: the lean-rich liquid heat exchanger is a plate structure or a shell-and-tube structure, specifically a plate heat exchanger or a shell-and-tube heat exchanger, and the lean-rich liquid heat exchanger is used to realize heat exchange between lean liquid and rich liquid;

[0018] Among them, the rich liquid output end of the absorption tower is connected to the rich liquid input end of the lean-rich liquid heat exchanger, the lean liquid output end of the analysis tower is connected to the lean liquid input end of the lean-rich liquid heat exchanger, and the rich liquid output end of the lean-rich liquid heat exchanger is connected to the rich liquid input end of the analysis tower.

[0019] The invention also provides a flue gas carbon capture method.

[0020] As a preferred embodiment of the flue gas carbon capture method of the present invention, a flue gas carbon capture method is applied to the flue gas carbon capture system, and the method comprises the following steps:

[0021] The steps for normal cycle operation:

[0022] Close the valves of the lean liquid storage tank and the rich liquid storage tank. After the flue gas is treated in the desulfurization tower, it enters the absorption tower from below;

[0023] In the absorber, water is mixed with the absorbent and then processed through a condenser;

[0024] The absorption liquid after condensation is returned to the absorption tower from above;

[0025] The mixed liquid is mixed with the flue gas, and the decarbonized flue gas is discharged from the upper outlet of the absorption tower;

[0026] Absorbent absorbs CO 2 After that, it becomes rich liquid and flows into the heat exchanger;

[0027] The rich liquid exchanges heat with the lean liquid at the liquid phase outlet of the reboiler;

[0028] The high-temperature rich liquid enters the analytical tower, and the steam from the reboiler heats the rich liquid;

[0029] CO in rich solution 2 Released in the analytical tower and separated from water;

[0030] The separated water returns to the analytical tower, and CO 2 Processing and collecting through a second condenser and the compressor;

[0031] Rich liquid releases CO 2 It then becomes lean liquid and enters the reboiler for heat exchange and absorbent replenishment before returning to the absorption tower.

[0032] As a preferred embodiment of the flue gas carbon capture method of the present invention, when the power plant is at its peak, based on the method steps of normal cycle operation,

[0033] Open the valve of the lean liquid storage tank and give priority to using the lean liquid in the lean liquid storage tank to supply the absorption tower;

[0034] The rich liquid in the absorption tower is first stored in the rich liquid storage tank;

[0035] After the rich liquid storage tank is full, close the valve of the rich liquid storage tank to prepare for the next use;

[0036] The rich liquid that is not stored in the remaining rich liquid storage tank enters the analysis tower to participate in the circulation;

[0037] When the power plant is in the off-peak period, based on the method steps of normal cycle operation,

[0038] Open the rich liquid storage tank valve. The rich liquid in the analysis tower comes from the rich liquid storage tank and the absorption tower.

[0039] The rich liquid completely releases CO in the desorption tower 2 , and produce lean solution;

[0040] The generated lean liquid is first stored in the lean liquid storage tank 10;

[0041] After the lean liquid storage tank is full, close the lean liquid storage tank valve to prepare for next use;

[0042] The remaining lean liquid that is not stored in the lean liquid storage tank enters the absorption tower to participate in the circulation.

[0043] Beneficial effects of the present invention:

[0044] During peak electricity consumption periods, the lean liquid in the lean liquid storage tank is used first to carry out CO 2The rich liquid storage tank allows the system to temporarily store the rich liquid produced by the absorber instead of immediately analyzing it, so that it can be processed when demand is lower, further balancing energy use. When the liquid level in the lean liquid storage tank drops to the preset minimum point, the system automatically switches to the analysis tower, which runs during periods of low energy demand to release CO in the rich liquid. 2 , restoring the absorption capacity of the solution and minimizing energy consumption.

[0045] During off-peak hours, the extra steam generated by the power plant is introduced into the reboiler to desorb the rich liquid, which improves energy efficiency. Part of the rich liquid in the desorption tower comes directly from the absorption tower, and the other part comes from the previously stored rich liquid storage tank. This design enables the system to flexibly handle rich liquid from different sources. Part of the lean liquid after desorption is directly returned to the absorption tower to start a new round of CO 2 The other part is stored in the lean liquid storage tank for use during peak hours. This not only ensures the continuity and efficiency of the carbon capture process, but also significantly improves the operational flexibility of the power plant boiler, enabling it to adjust its operating mode according to the real-time needs of the power grid. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0047] Figure 1 It is a schematic diagram of the overall process of the present invention. DETAILED DESCRIPTION

[0048] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0049] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0050] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0051] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0052] Example 1

[0053] Reference Figure 1 , which is the first embodiment of the present invention, provides a flue gas carbon capture system, the device includes a desulfurization tower 1, an absorption tower 2, a first condenser 3, a lean and rich liquid heat exchanger 4, a desorption tower 5, a separator 6, a second condenser 7, a compressor 8, a reboiler 9, a lean liquid storage tank 10, a rich liquid storage tank 11, a first valve 12 and a second valve 13;

[0054] Among them, the output end of the desulfurization tower 1 is connected to the input end of the absorption tower 2, a decarbonized flue gas outlet is provided at the top of the absorption tower 2, the absorption tower 2 is connected to the lean-rich liquid heat exchanger 4, the lean-rich liquid heat exchanger 4 is connected to the analysis tower 5, and the lean-rich liquid heat exchanger 4 is connected to the reboiler 9.

[0055] Specifically, the output end of the first condenser 3 is connected to the lean liquid input end of the absorption tower 2 , and the first condenser 3 is used for cooling, recovering and supplying the lean liquid into the absorption tower 2 .

[0056] Furthermore, the analytical tower 5 is connected to the separator 6, the separator 6 is connected to the second condenser 7, the second condenser 7 is connected to the compressor 8, and the separator 6 and the second condenser 7 are used to analyze the CO 2 After separation and cooling, the CO 2 To liquefy.

[0057] Furthermore, the reboiler 9 is connected to the decomposition tower 5 , and the reboiler 9 provides steam for the decomposition tower 5 .

[0058] Preferably, the lean liquid storage tank 10 is connected between the first condenser 3 and the lean liquid input end of the absorption tower 2 through a first valve 12 .

[0059] It should be noted that the rich liquid storage tank 11 is connected between the lean-rich liquid heat exchanger 4 and the rich liquid output end of the absorption tower 2 through the second valve 13 .

[0060] Preferably, the other end of the first condenser 3 is connected to the liquid supply through a mixer, and the lean liquid output end of the lean-rich liquid heat exchanger 4 is connected to the mixer, and the mixer is used to mix the lean liquid output from the lean-rich liquid heat exchanger 4 with supplementary water and supplementary absorbent.

[0061] Preferably, the flue gas input end of the absorption tower 2 is located at the lower end of the outer side of the absorption tower 2, and the lean liquid input end of the absorption tower 2 is located at the upper end of the outer side of the absorption tower 2, so as to achieve countercurrent contact between the carbon-containing flue gas and the lean liquid.

[0062] Preferably, the lean and rich liquid heat exchanger 4 is a plate structure or a shell and tube structure, specifically a plate heat exchanger or a shell and tube heat exchanger, and the lean and rich liquid heat exchanger 4 is used to realize heat exchange between lean liquid and rich liquid.

[0063] Preferably, the rich liquid output end of the absorption tower 2 is connected to the rich liquid input end of the lean-rich liquid heat exchanger 4, the lean liquid output end of the analysis tower 5 is connected to the lean liquid input end of the lean-rich liquid heat exchanger 4, and the rich liquid output end of the lean-rich liquid heat exchanger 4 is connected to the rich liquid input end of the analysis tower 5.

[0064] First, the flue gas enters the desulfurization tower 1 and enters the desulfurization treatment. The flue gas will enter the absorption tower 2 through the flue gas inlet at the lower end of the outer side of the absorption tower 2. At this time, the lean liquid will be sprayed downward from the lean liquid input end at the upper end of the outer side of the absorption tower 2 through the first condenser 3 to achieve CO in the flue gas. 2 Countercurrent contact with the sprayed lean liquid increases the lean liquid's ability to absorb CO in the flue gas. 2 After the decarbonization reaction occurs, the decarbonized flue gas is discharged from the decarbonized flue gas outlet at the top of the absorption tower 2, and the lean liquid absorbs the CO in the flue gas. 2 The rich liquid is heated to 90-100°C from the rich liquid output end of the absorption tower 2 through the lean-rich liquid heat exchanger 4, and then enters the interior of the analysis tower 5 through the rich liquid input end of the analysis tower 5. During the flow, CO in the rich liquid 2 The reaction product is thermally decomposed in the tower to obtain CO 2 The lean solution after analysis will return to the mixer and mix with make-up water and make-up absorbent, while CO 2 It is discharged from the top of the analytical tower 5 and passes through the separator 6 and the second condenser 7 respectively. The CO 2 Go to compressor 8 to get liquid CO 2 .

[0065] During peak electricity consumption, the lean liquid in the lean liquid storage tank 10 is used first in the absorption tower 2, while the rich liquid from the absorption tower 2 is temporarily stored in the rich liquid storage tank 11. The lean liquid in the lean liquid storage tank 10 is used first during peak electricity consumption mainly because the solution in the lean liquid storage tank 10 must be consumed first before the lean liquid output from the subsequent analysis tower 5 and the supplementary lean liquid enter. During peak periods, the rich liquid is temporarily stored in the rich liquid storage tank 11. The decomposition of the analysis tower 5 requires the consumption of steam heat through the reboiler 9. During peak periods, the net output of the power plant must be guaranteed first, so the steam supply to the analysis tower 5 is required to ensure that all steam is used for power generation.

[0066] During peak electricity consumption periods, excess steam in the power generation cycle is pumped to the reboiler to decompose the rich liquid to consume the rich liquid in the rich liquid storage tank. At this time, the decomposition tower is equivalent to not only decomposing the rich liquid under normal operation, but also the rich liquid stored during peak periods. This can not only ensure sufficient power output while avoiding waste caused by excessive power output, but also utilize excess steam to improve the overall power of the capture system.

[0067] The flow rate is controlled by the lean liquid pump. When the lean liquid flow rate at the outlet of the analysis tower 5 is greater than the lean liquid flow rate at the inlet of the absorption tower 2 , the excess lean liquid is recovered into the lean liquid storage tank 10 .

[0068] Example 2

[0069] Reference Figure 1 , which is the second embodiment of the present invention, and this embodiment is different from the first embodiment in that:

[0070] Absorption tower 2 and analytical tower 5 are independent of each other and separate CO 2 Absorption process and solution regeneration process. If the rich liquid outflow from the absorption tower 2 is less than the rich liquid inflow into the analysis tower 5, a portion of the rich liquid stored in the rich liquid storage tank 11 will flow into the analysis tower 5 together with the rich liquid flowing out of the absorption tower 2; if the rich liquid outflow from the absorption tower 2 is greater than the rich liquid inflow into the analysis tower 5, part of the rich liquid flowing out of the absorption tower 2 will be directly stored in the rich liquid storage tank 11. This can effectively avoid the situation in the prior art where the working efficiency of the absorption tower 2 and the analysis tower 5 are not exactly the same, the entire system is in an unbalanced state, resulting in unbalanced energy utilization, insufficient or wasted absorption liquid. In this way, through the design of the rich liquid storage tank 11, it can be ensured that the entire system is in a balanced state, energy utilization is balanced, and stable operation is maintained.

[0071] Example 3

[0072] Reference Figure 1 , which is the third embodiment of the present invention, and this embodiment is different from the second embodiment in that:

[0073] Due to the fixed energy consumption of the existing carbon capture system and the capture of CO 2The capture energy consumption generated during operation occupies a part of the power generation, so the upper and lower limits of the net output power of the power plant are reduced. 2 The amount is affected by the total power output and cannot be adjusted flexibly. During peak load periods, the electricity load demand is large, and the carbon-containing flue gas generated is large, which will generate a lot of carbon capture energy consumption, thereby reducing the net output of the power plant, thus conflicting with the load demand; during low load periods, the electricity load demand is small, the carbon emissions generated are small, and energy and resources are wasted.

[0074] The system can flexibly adjust the load peaks and low peaks. During the peak load period, the captured CO 2 This part does not need to be captured, reducing the power of the carbon capture system, fully outputting electricity, and increasing the net output power of the power plant; during the low load period, the CO stored in the rich liquid storage tank during the peak load period 2 It is released and captured to increase the power of the carbon capture system and reduce the net output power of the power plant.

[0075] Example 4

[0076] Reference Figure 1 , which is the second embodiment of the present invention, and this embodiment is different from the first embodiment in that:

[0077] A flue gas carbon capture method is applied to the flue gas carbon capture system, and the method comprises the following steps:

[0078] The steps for normal cycle operation:

[0079] Close the valves of the lean liquid storage tank and the rich liquid storage tank. After the flue gas is treated in the desulfurization tower, it enters the absorption tower from below;

[0080] In the absorber, water is mixed with the absorbent and then processed through a condenser;

[0081] The absorption liquid after condensation is returned to the absorption tower from above;

[0082] The mixed liquid is mixed with the flue gas, and the decarbonized flue gas is discharged from the upper outlet of the absorption tower;

[0083] Absorbent absorbs CO 2 After that, it becomes rich liquid and flows into the heat exchanger;

[0084] The rich liquid exchanges heat with the lean liquid at the liquid phase outlet of the reboiler;

[0085] The high-temperature rich liquid enters the analytical tower, and the steam from the reboiler heats the rich liquid;

[0086] CO in rich solution 2 Released in the analytical tower and separated from water;

[0087] The separated water returns to the analytical tower, and CO 2 Processing and collection through a second condenser and a compressor;

[0088] Rich liquid releases CO 2 It then becomes lean liquid and enters the reboiler for heat exchange and absorbent replenishment before returning to the absorption tower.

[0089] Preferably, when the power plant is at its peak, based on the method steps of normal cycle operation,

[0090] Open the valve of the lean liquid storage tank and give priority to using the lean liquid in the lean liquid storage tank to supply the absorption tower;

[0091] The rich liquid in the absorption tower is first stored in the rich liquid storage tank;

[0092] After the rich liquid storage tank is full, close the valve of the rich liquid storage tank to prepare for the next use;

[0093] The rich liquid that is not stored in the remaining rich liquid storage tank enters the analysis tower to participate in the circulation;

[0094] When the power plant is in the off-peak period, based on the method steps of normal cycle operation,

[0095] Open the rich liquid storage tank valve. The rich liquid in the analysis tower comes from the rich liquid storage tank and the absorption tower.

[0096] The rich liquid completely releases CO in the desorption tower 2 , and produce lean solution;

[0097] The generated lean liquid is first stored in the lean liquid storage tank;

[0098] After the lean liquid storage tank is full, close the lean liquid storage tank valve to prepare for next use;

[0099] The remaining lean liquid that is not stored in the lean liquid storage tank enters the absorption tower to participate in the circulation

[0100] In summary, during peak load periods, the captured CO2 is stored in a rich liquid storage tank. 2 , reducing the load on the carbon capture system to increase the net output of the power plant; during the off-load period, the CO in the storage tank is released and processed 2 , increasing the load on the carbon capture system and correspondingly reducing the net output power of the power plant.

[0101] Importantly, it should be noted that the construction and arrangement of the present application shown in a plurality of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), installation arrangement, use of materials, color, directional changes, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, the element shown as integrally formed can be composed of multiple parts or elements, the position of the element can be inverted or otherwise changed, and the nature or number or position of the discrete element can be changed or changed. Therefore, all such modifications are intended to be included in the scope of the present invention. The order or sequence of any process or method steps can be changed or reordered according to alternative embodiments. In the claims, any "device plus function" clause is intended to cover the structure of performing the function described herein, and is not only structurally equivalent but also equivalent structure. Without departing from the scope of the present invention, other replacements, modifications, changes and omissions can be made in the design, operating conditions and arrangement of the exemplary embodiments. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0102] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those that are not relevant to implementing the invention) may not be described.

[0103] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A flue gas carbon capture system, characterized in that: It comprises a desulfurization tower (1), an absorption tower (2), a first condenser (3), a lean and rich liquid heat exchanger (4), a desorption tower (5), a separator (6), a second condenser (7), a compressor (8), a reboiler (9), a lean liquid storage tank (10), a rich liquid storage tank (11), a first valve (12) and a second valve (13); The output end of the desulfurization tower (1) is connected to the input end of the absorption tower (2), a decarbonized flue gas outlet is provided at the top of the absorption tower (2), the absorption tower (2) is connected to the lean-rich liquid heat exchanger (4), the lean-rich liquid heat exchanger (4) is connected to the analysis tower (5), and the lean-rich liquid heat exchanger (4) is connected to the reboiler (9).

2. The flue gas carbon capture system according to claim 1, characterized in that: The output end of the first condenser (3) is connected to the lean liquid input end of the absorption tower (2), and the first condenser (3) is used to cool the lean liquid that is recovered and supplied to the inside of the absorption tower (2).

3. The flue gas carbon capture system according to claim 1 or 2, characterized in that: The analysis tower (5) is connected to the separator (6), the separator (6) is connected to the second condenser (7), the second condenser (7) is connected to the compressor (8), and the separator (6) and the second condenser (7) are used to separate and cool the analyzed CO2, and liquefy the CO2 through the compressor (8).

4. The flue gas carbon capture system according to claim 3, characterized in that: The reboiler (9) is connected to the analysis tower (5), and the reboiler (9) provides steam for the analysis tower (5).

5. The flue gas carbon capture system according to claim 4, characterized in that: The lean liquid storage tank (10) is connected between the first condenser (3) and the lean liquid input end of the absorption tower (2) via the first valve (12).

6. The flue gas carbon capture system according to claim 5, characterized in that: The rich liquid storage tank (11) is connected between the lean-rich liquid heat exchanger (4) and the rich liquid output end of the absorption tower (2) via the second valve (13).

7. The flue gas carbon capture system according to claim 6, characterized in that: The other end of the first condenser (3) is connected to the liquid supply through a mixer, and the lean liquid output end of the lean-rich liquid heat exchanger (4) is connected to the mixer, and the mixer is used to mix the lean liquid output from the lean-rich liquid heat exchanger (4) with supplementary water and supplementary absorbent; The flue gas input end of the absorption tower (2) is located at the lower end of the outer side of the absorption tower (2), and the lean liquid input end of the absorption tower (2) is located at the upper end of the outer side of the absorption tower (2), so as to achieve countercurrent contact between the carbon-containing flue gas and the lean liquid.

8. The flue gas carbon capture system according to claim 6 or 7, characterized in that: The lean and rich liquid heat exchanger (4) is a plate structure or a shell and tube structure, specifically a plate heat exchanger or a shell and tube heat exchanger, and the lean and rich liquid heat exchanger (4) is used to achieve heat exchange between lean liquid and rich liquid; The rich liquid output end of the absorption tower (2) is connected to the rich liquid input end of the lean-rich liquid heat exchanger (4), the lean liquid output end of the analysis tower (5) is connected to the lean liquid input end of the lean-rich liquid heat exchanger (4), and the rich liquid output end of the lean-rich liquid heat exchanger (4) is connected to the rich liquid input end of the analysis tower (5).

9. A flue gas carbon capture method, characterized in that: Applied to the flue gas carbon capture system according to any one of claims 1 to 8, the method comprises the following steps: The steps for normal cycle operation: Close the valves of the lean liquid storage tank and the rich liquid storage tank. After the flue gas is treated in the desulfurization tower, it enters the absorption tower from below; In the absorber, water is mixed with the absorbent and then processed through a condenser; The absorption liquid after condensation is returned to the absorption tower from above; The mixed liquid is mixed with the flue gas, and the decarbonized flue gas is discharged from the upper outlet of the absorption tower; After the absorbent absorbs CO2, it becomes rich liquid and flows into the heat exchanger; The rich liquid exchanges heat with the lean liquid at the liquid phase outlet of the reboiler; The high-temperature rich liquid enters the analytical tower, and the steam from the reboiler heats the rich liquid; The CO2 in the rich liquid is released in the analysis tower and separated from the water; The separated water returns to the analytical tower, and the CO2 is processed and collected through the second condenser and compressor; After releasing CO2, the rich liquid becomes lean liquid and enters the reboiler for heat exchange and absorbent replenishment before returning to the absorption tower.

10. The flue gas carbon capture method according to claim 9, characterized in that: When the power plant is at peak period, based on the method steps of normal cycle operation, Open the valve of the lean liquid storage tank and give priority to using the lean liquid in the lean liquid storage tank to supply the absorption tower; The rich liquid in the absorption tower is first stored in the rich liquid storage tank; After the rich liquid storage tank is full, close the valve of the rich liquid storage tank to prepare for the next use; The rich liquid that is not stored in the remaining rich liquid storage tank enters the analysis tower to participate in the circulation; When the power plant is in the off-peak period, based on the method steps of normal cycle operation, Open the rich liquid storage tank valve. The rich liquid in the analysis tower comes from the rich liquid storage tank and the absorption tower. The rich liquid completely releases CO2 in the analysis tower and produces lean liquid; The generated lean liquid is first stored in the lean liquid storage tank; After the lean liquid storage tank is full, close the lean liquid storage tank valve to prepare for next use; The remaining lean liquid that is not stored in the lean liquid storage tank enters the absorption tower to participate in the circulation.

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