After-combustion carbon capture coal-fired power generation system capable of utilizing waste heat and waste pressure

Abstract

The invention discloses an after-combustion carbon capture coal-fired power generation system capable of utilizing waste heat and waste pressure. The system comprises a regeneration tower, a reboiler, a lean and rich liquid heat exchanger, an absorption tower, a medium-pressure cylinder, a low-pressure cylinder, a small back pressure machine, a circulating cooler and a heat regeneration system. The barren liquor outlet of the regeneration tower is communicated with the barren liquor inlet of the absorption tower through the shell side of the reboiler and the shell side of the barren and rich liquor heat exchanger; an outlet of the medium-pressure cylinder is divided into two paths, one path is communicated with an inlet of the low-pressure cylinder, the other path is divided into two paths after passing through the pipe side of the small back pressure machine and the pipe side of the reboiler, one path is communicated with an outlet of the small back pressure machine, and the other path is communicated with the heat regeneration system through the circulation cooler. And the energy loss is low.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of coal-fired power plant decarbonization, and relates to a post-combustion carbon capture coal-fired power generation system utilizing waste heat and pressure. BACKGROUND

[0002] Global warming has seriously affected the sustainable development of human society, and coal-fired power generation still dominates the world power generation field. The emission of CO2 by coal-fired power generation is one of the main causes of global warming. Therefore, it is very important to reduce the CO2 emission of coal-fired power plants.

[0003] The energy penalty of the traditional post-combustion carbon capture process based on MEA is significant due to the need to extract a large amount of steam from the steam turbine, the mismatch between the extraction parameters and the parameters of the reboiler, and the unreasonable operation of the decarbonization unit. Integrating carbon dioxide capture technology into coal-fired power plants is considered a practical and effective measure to reduce carbon dioxide emissions from coal-fired power plants and mitigate global temperature increases. Post-combustion decarbonization is more commonly used in coal-fired power plants. In post-combustion decarbonization technology, the chemical absorption method based on monoethanolamine (MEA) is widely considered to be the most promising carbon capture technology due to its fast reaction rate and relatively high CO2 separation selectivity. In the conventional MEA decarbonization process, the heat for MEA solvent regeneration is supplied by the reboiler, and the heat of the reboiler comes from the extraction steam at the connection pipe of the low-pressure cylinder of the steam turbine. The heat of the reboiler is provided by the extraction steam at the connection pipe of the low-pressure cylinder of the steam turbine. Due to the mismatch between the extraction parameters and the parameters of the reboiler, a large amount of energy is lost. SUMMARY

[0004] The present application aims to overcome the shortcomings of the prior art and provides a post-combustion carbon capture coal-fired power generation system utilizing waste heat and pressure, which can overcome the problem of mismatch between extraction parameters and reboiler parameters and has low energy loss.

[0005] To achieve the above-mentioned purpose, the present application discloses a post-combustion carbon capture coal-fired power generation system utilizing waste heat and pressure, which comprises a regeneration tower, a reboiler, a lean-rich liquid heat exchanger, an absorption tower, a medium-pressure cylinder, a low-pressure cylinder, a small back pressure machine, a circulating cooler, and a heat recovery system.

[0006] The lean liquid outlet of the regeneration tower is connected to the lean liquid inlet of the absorption tower through the shell side of the reboiler and the shell side of the lean-rich liquid heat exchanger. The outlet of the medium-pressure cylinder is connected to the inlet of the low-pressure cylinder, and the other outlet is connected to the outlet of the small back pressure machine after passing through the tube side of the reboiler, and the other outlet is connected to the heat recovery system through the circulating cooler.

[0007] The post-combustion carbon capture coal-fired power generation system utilizing waste heat and pressure of the present application is further improved in that:

[0008] Further, the lean liquid outlet of the regeneration tower is communicated with the lean liquid inlet of the absorption tower through the shell side of the reboiler, the lean liquid pump, the shell side of the lean- rich liquid heat exchanger and the lean liquid cooler.

[0009] Further, the boiler is further included, and a flue gas outlet of the boiler is communicated with a flue gas inlet of the absorption tower.

[0010] Further, the flue gas outlet of the boiler is communicated with the flue gas inlet of the absorption tower through a selective catalytic reduction device, an electrostatic precipitator, an induced draft fan, a desulfurization tower, a cooler and a compressor in sequence.

[0011] Further, the high-pressure cylinder is further included, a main steam outlet of the boiler is communicated with an inlet of the high-pressure cylinder, an outlet of the high-pressure cylinder is communicated with a reheating side inlet of the boiler through a heat recovery system, and a reheating side outlet of the boiler is communicated with an inlet of the medium-pressure cylinder.

[0012] Further, an outlet of the low-pressure cylinder is communicated with the heat recovery system through a condenser.

[0013] Further, an outlet of a slurry pool at the bottom of the absorption tower is communicated with an inlet of the regeneration tower through a rich liquid pump and a pipe side of the lean-rich liquid heat exchanger.

[0014] Further, a carbon dioxide outlet of the regeneration tower is communicated with an inlet of a gas-liquid separator through a CO2 cooler, and a gas outlet of the gas-liquid separator is communicated with a carbon dioxide output pipeline through a CO2 multi-stage compressor.

[0015] Further, the high-pressure cylinder, the medium-pressure cylinder, the low-pressure cylinder and the generator are coaxially arranged.

[0016] The application discloses a post-combustion carbon capture coal-fired power generation system utilizing waste heat and waste pressure.

[0017] The lean liquid outlet of the regeneration tower is communicated with the lean liquid inlet of the absorption tower through the shell side of the reboiler and the shell side of the lean-rich liquid heat exchanger; the outlet of the medium-pressure cylinder is divided into two routes, one of which is communicated with the inlet of the low-pressure cylinder, and the other is divided into two routes after passing through the small back pressure machine and the pipe side of the reboiler, one of which is communicated with the outlet of the small back pressure machine, and the other is communicated with the heat recovery system through the circulating cooler;

[0018] The outlet of the slurry pool at the bottom of the absorption tower is communicated with the inlet of the regeneration tower through the rich liquid pump and the pipe side of the lean-rich liquid heat exchanger.

[0019] The carbon dioxide outlet of the regeneration tower is communicated with the inlet of the gas-liquid separator through the CO2 cooler, and the gas outlet of the gas-liquid separator is communicated with the carbon dioxide output pipeline through the CO2 multi-stage compressor.

[0020] The application has the following beneficial effects:

[0021] The post-combustion carbon capture coal-fired power generation system with waste heat and pressure utilization according to the present application, in the specific operation, the heat of the reboiler is provided by the extraction steam at the connection pipe between the medium-pressure cylinder and the low-pressure cylinder, which is circulated through the small back pressure turbine and the drain pump, wherein the extraction steam is introduced into the small back pressure turbine, the extraction steam pressure can be recovered, and the small back pressure turbine can generate part of electricity, and the heat in the extraction steam is recovered through the drain pump circulation, so as to realize the extraction steam waste heat and pressure utilization, achieve the energy saving purpose, overcome the problem of the mismatch between the extraction steam parameters and the reboiler parameters, and reduce the energy loss. BRIEF DESCRIPTION OF DRAWINGS

[0022] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the improper limitation of the accompanying drawings. In the drawings:

[0023] Figure 1 The structural diagram of the present application.

[0024] In the drawings, 1 is a boiler, 2 is a high-pressure cylinder, 3 is a medium-pressure cylinder, 4 is a low-pressure cylinder, 5 is a generator, 6 is a condenser, 7 is a heat recovery system, 8 is a selective catalytic reduction device, 9 is an electrostatic precipitator, 10 is an induced draft fan, 11 is a desulfurization tower, 12 is a cooler, 13 is a compressor, 14 is an absorption tower, 15 is a rich liquid pump, 16 is a lean-rich liquid heat exchanger, 17 is a lean liquid pump, 18 is a reboiler, 19 is a small back pressure turbine, 20 is a circulating cooler, 21 is a regeneration tower, 22 is a lean liquid cooler, 23 is a CO2 cooler, 24 is a CO2 multi-stage compressor, and 25 is a gas-liquid separator. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0026] In the description of the present application, it should be understood that the terms “comprise” and “include” indicate the presence of described features, whole, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, whole, steps, operations, elements, components and / or sets thereof.

[0027] It should also be understood that the terms used in the specification of the present application are only for the purpose of describing specific embodiments and are not intended to limit the present application. As used in the specification and the appended claims of the present application, unless otherwise clearly indicated by the context, the singular forms “a”, “an” and “the” are intended to include the plural forms.

[0028] It should be further understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items, and that the term "and / or" as used herein allows for the inclusion of only a single item, when the term "and / or" has the exclusionary sense, as when the term is used in the context of "one of only A and / or B" to exclude the other item (i.e., C). Additionally, the character " / " as used herein, generally indicates an "or" relationship of the associated objects before and after the " / ".

[0029] It should be understood that, although the terms first, second, third, etc. can be used herein to describe various ranges or elements, these ranges or elements should not be limited by these terms. These terms are only used to distinguish one range or element from another. For example, a first range could be termed a second range without departing from the scope of the example embodiments. Similarly, it will be understood that, when an element is referred to as being "on" another element, it can be directly on the element, or it can be indirectly on the element with one or more intervening elements interposed therebetween.

[0030] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]."

[0031] In order to make the purposes, technical solutions and advantages of the example embodiments of the present application clearer, the technical solutions in the example embodiments of the present application will be described clearly and completely below with reference to the drawings in the example embodiments of the present application. Obviously, the described example embodiments are some but not all of the example embodiments of the present application. The components of the example embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the example embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed application, but merely represents selected example embodiments of the present application. Based on the example embodiments in the present application, all other example embodiments obtained by a person of ordinary skill in the art without creative effort are within the scope of the present application.

[0032] Various structural schematic diagrams according to the disclosed example embodiments of the present application are shown in the drawings. These diagrams are not drawn to scale, in which some details are exaggerated for the purpose of clarity, and some details can be omitted. The shapes of various regions, layers and the relative size and positional relationship therebetween shown in the drawings are only exemplary, and in actuality, there can be deviations due to manufacturing tolerances or technical limitations, and a person skilled in the art can additionally design regions / layers with different shapes, sizes and relative positions according to actual needs.

[0033] A regeneration tower is a device used in the chemical industry to desorb absorbed or adsorbed substances to restore the performance of solvents or adsorbents. Its functions include: Desorbing absorbed substances: In processes such as natural gas dehydration, desulfurization, and decarbonization, the regeneration tower heats the rich solution (e.g., amine solution that has absorbed specific substances like H2S and carbon monoxide) to decompose acidic gases, which are then discharged from the top of the tower, thus restoring the performance of the solvent or adsorbent. Achieving recycling: After desulfurizing agents are regenerated through the regeneration tower, the lean solution (low H2S and CO content) discharged from the bottom can be recycled, reducing production costs and resource consumption. Maintaining system operation: Through continuous desorption and regeneration processes, the regeneration tower maintains the efficient operation of the entire absorption-regeneration system, ensuring the stability and reliability of the process.

[0034] Absorption towers are key equipment in the chemical and environmental protection fields, used to separate or purify specific components in gases through gas-liquid contact. Their core principle is based on physical absorption (such as dissolution) or chemical absorption (such as reaction) processes, transferring target pollutants (such as SO2, CO2, H2S) from the gas phase to the liquid phase, thereby achieving gas purification or solvent regeneration.

[0035] A reboiler is a heat exchanger at the bottom or side stream of a distillation column. It is used to vaporize a portion of the liquid product and return it to the column as vapor reflux, allowing mass transfer between the vapor and liquid phases within the column. It also provides the heat required for the distillation process. A detailed description follows:

[0036] Vertical thermosiphon reboiler: Utilizes the density difference between the single-phase liquid at the bottom of the tower and the vapor-liquid mixture inside the heat exchanger tubes to create the driving force for circulation. It has the advantages of compact structure, small footprint, and high heat transfer coefficient, but the tube length is usually limited by the tower skirt height and heat transfer area, making maintenance and cleaning difficult. Suitable for medium pressure, medium temperature difference, and low static head applications.

[0037] Horizontal thermosiphon reboiler: Also relies on density difference to generate driving force, but the tube bundle is arranged horizontally. It has the advantages of moderate heat transfer coefficient and convenient maintenance and cleaning, but it occupies a large area. For large thermosiphon reboilers, multiple inlets and connecting fittings are required to ensure uniform flow distribution, increasing costs. It is widely used in the oil refining industry.

[0038] Forced circulation reboilers rely on the mechanical work input by a pump to circulate the fluid. The circulation speed is easy to control and adjust, the material residence time is short, and both heat transfer and pressure drop can be achieved through forced convection. They are suitable for high-viscosity, heat-sensitive materials, systems with small amounts of solid suspension, long sensible heat sections, and high-resistance systems with low evaporation ratios. However, the circulation rate is controlled by the pump, and the cost of pump power consumption must be considered.

[0039] Kettle-type reboiler: composed of a shell with a gas-liquid separation space and an extractable tube bundle, the end of which has an overflow weir to ensure that the tube bundle is effectively immersed in the liquid. It has the advantages of reliable performance, little influence from water dynamics, and good operation under high vacuum conditions, but the shell is large, the cost is high, and it is the most prone to fouling among all reboilers.

[0040] Built-in reboiler: the tube bundle is directly inserted into the tower bottom liquid pool of the distillation tower, eliminating the shell and connecting pipeline, and having a simple structure and low cost. However, the tower content is limited, the heat transfer area is small, and the liquid circulation is poor, which is not suitable for viscous liquids.

[0041] Vertical shell side thermosyphon reboiler: the boiling process occurs on the shell side, which is equipped with baffles to make the fluid flow longitudinally. It is suitable for special occasions, such as heating fluids that are corrosive, thus requiring special metal materials, at which time it is more appropriate for the heating medium to pass through the tube.

[0042] Membrane ring reboiler: two-thirds of the steam generators of reboilers have variable cross-section annular channels, and the two-phase fluid generates upward flow, while one-third of the tubes have liquid descending in a film shape and sinking into the space below the tube, implementing closed circulation. The heat transfer process can be greatly enhanced.

[0043] External circulation inert gas distillation reboiler: inert gas is introduced into the vertical tube flow boiling system to significantly enhance heat transfer.

[0044] Example 1

[0045] Reference Figure 1 The waste heat and pressure utilization post-combustion carbon capture coal-fired power generation system comprises a regenerator 21, a reboiler 18, a lean-rich liquid heat exchanger 16, an absorption tower 14, a medium-pressure cylinder 3, a low-pressure cylinder 4, a small back pressure machine 19, a circulating cooler 20, and a regenerative system 7. The lean liquid outlet of the regenerator 21 is connected in communication with the lean liquid inlet of the absorption tower 14 through the shell side of the reboiler 18 and the shell side of the lean-rich liquid heat exchanger 16. The outlet of the medium-pressure cylinder 3 is divided into two routes, one of which is connected in communication with the inlet of the low-pressure cylinder 4, and the other is connected in communication with the outlet of the small back pressure machine 19 after passing through the small back pressure machine 19 and the tube side of the reboiler 18, and then divided into two routes, one of which is connected in communication with the outlet of the small back pressure machine 19, and the other is connected in communication with the regenerative system 7 through the circulating cooler 20. The outlet of the slurry pool at the bottom of the absorption tower 14 is connected in communication with the inlet of the regenerator 21 through the rich liquid pump 15 and the tube side of the lean-rich liquid heat exchanger 16. The carbon dioxide outlet of the regenerator 21 is connected in communication with the gas-liquid separator 25 through the CO2 cooler 23, and the gas outlet of the gas-liquid separator 25 is connected in communication with the carbon dioxide output pipeline through the CO2 multi-stage compressor 24.

[0046] Example 2

[0047] Reference Figure 1For further improving the application, the waste heat and pressure utilization post-combustion carbon capture coal-fired power generation system comprises a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a heat recovery system 7, a selective catalytic reduction device 8, an electrostatic precipitator 9, an induced draft fan 10, a desulfurization tower 11, a cooler 12, a compressor 13, an absorption tower 14, a rich liquid pump 15, a lean-rich liquid heat exchanger 16, a lean liquid pump 17, a reboiler 18, a small back pressure machine 19, a circulating cooler 20, a regeneration tower 21, a lean liquid cooler 22, a CO2 cooler 23, a CO2 multi-stage compressor 24 and a gas-liquid separator 25.

[0048] The flue gas outlet of the boiler 1 is sequentially connected with the flue gas inlet of the absorption tower 14 through the selective catalytic reduction device 8, the electrostatic precipitator 9, the induced draft fan 10, the desulfurization tower 11, the cooler 12 and the compressor 13, the main steam outlet of the boiler 1 is connected with the inlet of the high-pressure cylinder 2, the outlet of the high-pressure cylinder 2 is connected with the reheat side inlet of the boiler 1 through the heat recovery system 7, the reheat side outlet of the boiler 1 is connected with the inlet of the medium-pressure cylinder 3, the outlet of the medium-pressure cylinder 3 is divided into two paths, one of which is connected with the inlet of the low-pressure cylinder 4, and the other is connected with the outlet of the small back pressure machine 19 and the pipe side of the reboiler 18 after being divided into two paths, one of which is connected with the outlet of the small back pressure machine 19, and the other is connected with the heat recovery system 7 through the circulating cooler 20, and the outlet of the low-pressure cylinder 4 is connected with the heat recovery system 7 through the condenser 6.

[0049] The outlet of the slurry pool at the bottom of the absorption tower 14 is connected with the inlet of the regeneration tower 21 through the rich liquid pump 15 and the pipe side of the lean-rich liquid heat exchanger 16, the lean liquid outlet of the regeneration tower 21 is connected with the lean liquid inlet of the absorption tower 14 through the shell side of the reboiler 18, the lean liquid pump 17, the shell side of the lean-rich liquid heat exchanger 16 and the lean liquid cooler 22, the carbon dioxide outlet of the regeneration tower 21 is connected with the inlet of the gas-liquid separator 25 through the CO2 cooler 23, and the gas outlet of the gas-liquid separator 25 is connected with the carbon dioxide output pipeline through the CO2 multi-stage compressor 24.

[0050] The high-pressure cylinder 2, the medium-pressure cylinder 3, the low-pressure cylinder 4 and the generator 5 are coaxially arranged.

[0051] Example three

[0052] The embodiment provides a combustion after-capture carbon coal-fired power generation method of waste heat and pressure utilization, and the combustion after-capture carbon coal-fired power generation method of waste heat and pressure utilization is realized based on a combustion after-capture carbon coal-fired power generation system of waste heat and pressure utilization, and the combustion after-capture carbon coal-fired power generation system of waste heat and pressure utilization comprises a boiler 1, a high-pressure cylinder 2, a medium-pressure cylinder 3, a low-pressure cylinder 4, a generator 5, a condenser 6, a heat recovery system 7, a selective catalytic reduction device 8, an electrostatic precipitator 9, an induced draft fan 10, a desulfurization tower 11, a cooler 12, a compressor 13, an absorption tower 14, a rich-liquid pump 15, a lean-rich-liquid heat exchanger 16, a lean-liquid pump 17, a reboiler 18, a small back pressure turbine 19, a circulating cooler 20, a regeneration tower 21, a lean-liquid cooler 22, a CO2 cooler 23, a CO2 multi-stage compressor 24 and a gas-liquid separator 25, and the specific connection mode is as shown in the second embodiment.

[0053] Specifically, the combustion after-capture carbon coal-fired power generation method of waste heat and pressure utilization comprises the following steps.

[0054] In the boiler 1, flue gas generated after coal combustion enters the absorption tower 14 after being sequentially cooled and pressurized by the selective catalytic reduction device 8, the electrostatic precipitator 9, the induced draft fan 10, the desulfurization tower 11, the cooler 12 and the compressor 13. In the absorption tower 14, 30wt% MEA solution absorbs CO2 in the flue gas from the boiler 1, and the purified flue gas is discharged from the upper part of the absorption tower 14, and the MEA solution rich in CO2 enters the regeneration tower 21 after passing through the rich-liquid pump 15 to regenerate the MEA solution. The lean liquid and the rich liquid exchange heat in the lean-rich-liquid heat exchanger 16, the rich liquid is heated and then enters the regeneration tower 21 to react. In the regeneration tower 21, the reboiler 18 provides heat for the regeneration of the MEA solution, the regenerated MEA solution passes through the lean-liquid pump 17, is cooled in the lean-rich-liquid heat exchanger 16, then passes through the lean-liquid cooler 22 and enters the absorption tower 14 to be recycled, and the captured CO2 is discharged from the upper part of the regeneration tower 21 and is stored by compression of the CO2 multi-stage compressor 24. The heat of the reboiler 18 is provided by circulating the steam extracted from the connection pipe between the medium-pressure cylinder 3 and the low-pressure cylinder 4 through the small back pressure turbine 19 and the drain pump, the steam is introduced into the small back pressure turbine 19, the steam pressure can be recovered, and the small back pressure turbine 19 generates part of the electricity, and then the heat in the steam is recovered by circulating the drain pump, so that the waste heat and pressure of the extracted steam are utilized, and the energy-saving purpose is achieved.

[0055] The application is based on the coupling of the coal-fired power plant using waste heat and pressure and the chemical absorption method of decarburization based on monoethanolamine (MEA), which can overcome the problem of mismatching of steam extraction parameters and reboiler 18 parameters, realize efficient and energy-saving decarburization of the decarburization coal-fired power generation system, specifically, the steam extraction at the connecting pipe of the low-pressure cylinder 4 of the steam turbine is introduced into the small back pressure turbine 19, the waste pressure of the steam extraction is recovered, the waste pressure is used to do work and generate electricity, and the energy efficiency penalty is reduced. The reboiler 18 is used to circulate the drain, the waste heat in the drain is used to compensate the steam, thereby saving a part of the steam extraction at the connecting pipe of the low-pressure cylinder 4 of the steam turbine, and the power generation efficiency is improved.

[0056] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the application being indicated by the following claims.

[0057] It should be understood that the application is not limited to the precise construction and method described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the application is limited only by the claims that follow.

[0058] The above description is only the preferred embodiment of the present application, not any limitation to the present application, any simple modification, change and equivalent structure change according to the technical essence of the present application to the above embodiment are still within the protection scope of the technical scheme of the present application.

Claims

1. A coal-fired power generation system with carbon capture by combustion afterburning and utilization of waste heat and pressure, characterized in that, The system further comprises a regenerator (21), a reboiler (18), a lean-rich liquid heat exchanger (16), an absorber (14), a medium-pressure cylinder (3), a low-pressure cylinder (4), a small back pressure turbine (19), a circulating cooler (20) and a regenerative system (7). The lean liquid outlet of the regenerator (21) is connected to the lean liquid inlet of the absorber (14) through the shell side of the reboiler (18) and the shell side of the lean-rich liquid heat exchanger (16); the outlet of the medium-pressure cylinder (3) is divided into two paths, one of which is connected to the inlet of the low-pressure cylinder (4), and the other is divided into two paths after passing through the small back pressure turbine (19) and the tube side of the reboiler (18), one of which is connected to the outlet of the small back pressure turbine (19), and the other is connected to the regenerative system (7) through the circulating cooler (20).

2. The system according to claim 1, wherein the system is characterized by: The lean liquid outlet of the regenerator (21) is connected to the lean liquid inlet of the absorber (14) through the shell side of the reboiler (18), the lean liquid pump (17), the shell side of the lean-rich liquid heat exchanger (16) and the lean liquid cooler (22).

3. The system according to claim 1, wherein the system is characterized by: The system further comprises a boiler (1), and the flue gas outlet of the boiler (1) is connected to the flue gas inlet of the absorber (14).

4. The system according to claim 3, wherein the system is characterized by: The flue gas outlet of the boiler (1) is connected to the flue gas inlet of the absorber (14) in sequence through a selective catalytic reduction device (8), an electrostatic precipitator (9), an induced draft fan (10), a desulfurization tower (11), a cooler (12) and a compressor (13).

5. The system according to claim 4, wherein the system is characterized by: The system further comprises a high-pressure cylinder (2), the main steam outlet of the boiler (1) is connected to the inlet of the high-pressure cylinder (2), the outlet of the high-pressure cylinder (2) is connected to the reheated side inlet of the boiler (1) through the regenerative system (7), and the reheated side outlet of the boiler (1) is connected to the inlet of the medium-pressure cylinder (3).

6. The system according to claim 5, wherein the system is characterized by: The outlet of the low-pressure cylinder (4) is connected to the regenerative system (7) through a condenser (6).

7. The system according to claim 1, wherein the system is characterized by: The outlet of the slurry pool at the bottom of the absorber (14) is connected to the inlet of the regenerator (21) through a rich liquid pump (15) and the tube side of the lean-rich liquid heat exchanger (16).

8. The system according to claim 1, wherein the system is characterized by: The carbon dioxide outlet of the regenerator (21) is connected to the inlet of a gas-liquid separator (25) through a CO2 cooler (23), and the gas outlet of the gas-liquid separator (25) is connected to a carbon dioxide output pipeline through a CO2 multi-stage compressor (24).

9. The system according to claim 1, wherein the system is characterized by: The high-pressure cylinder (2), the medium-pressure cylinder (3), the low-pressure cylinder (4) and a generator (5) are coaxially arranged.

10. A coal-fired power generation system with carbon capture by combustion afterburning and utilization of waste heat and pressure, characterized by, The system further comprises a regenerator (21), a reboiler (18), a lean-rich liquid heat exchanger (16), an absorber (14), a medium-pressure cylinder (3), a low-pressure cylinder (4), a small back pressure turbine (19), a circulating cooler (20) and a regenerative system (7). The lean liquid outlet of the regenerator (21) is connected to the lean liquid inlet of the absorber (14) through the shell side of the reboiler (18) and the shell side of the lean-rich liquid heat exchanger (16); the outlet of the medium-pressure cylinder (3) is divided into two paths, one of which is connected to the inlet of the low-pressure cylinder (4), and the other is divided into two paths after passing through the small back pressure turbine (19) and the tube side of the reboiler (18), one of which is connected to the outlet of the small back pressure turbine (19), and the other is connected to the regenerative system (7) through the circulating cooler (20); The outlet of the slurry pool at the bottom of the absorption tower (14) is connected to the inlet of the regeneration tower (21) through a rich liquid pump (15) and the tube side of a lean-rich liquid heat exchanger (16); The carbon dioxide outlet of the regeneration tower (21) is connected to the inlet of a gas-liquid separator (25) through a CO2 cooler (23), and the gas outlet of the gas-liquid separator (25) is connected to a carbon dioxide output pipeline through a CO2 multi-stage compressor (24).

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