A coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization

Abstract

This invention proposes a coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization. The system includes a coal-fired boiler, a steam turbine, a condenser, a regenerative heater, a heat exchanger, and a carbon capture assembly. The boiler has a flue gas outlet and a steam outlet. The steam turbine is connected to the steam outlet, and the condensate outlet is connected to the condenser. The regenerative heater is connected between the condenser and the economizer. The heat exchanger is connected to the regenerative heater to heat the condensate within it. The carbon capture assembly is connected to the flue gas outlet and has a heat source outlet connected to the hot-side inlet of the heat exchanger. The heat source discharged from the outlet is used for heat exchange with the organic working fluid within the heat exchanger. This coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization has the advantage of high energy efficiency.

Description

Technical Field

[0001] This invention belongs to the technical field of carbon capture waste heat utilization, specifically, it relates to a coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization. Background Technology

[0002] Carbon capture and storage (CCS) technology is considered one of the most direct and effective technological pathways to significantly reduce carbon dioxide emissions from coal-fired power plants. However, this technology, especially post-combustion capture processes based on chemical absorption, has a significant bottleneck: its core processes (such as absorbent regeneration) require a large amount of medium- and low-temperature thermal energy, typically necessitating the extraction of high-quality steam from the power plant's main steam cycle. This leads to a significant decrease in power plant output, reduced overall energy efficiency, and high carbon capture costs, severely hindering the large-scale commercial application of this technology.

[0003] In related technologies, combining the Mechanical Rankine Cycle (ORC) system with coal-fired power plants or carbon capture processes aims to recover and utilize various types of waste heat. However, existing integration schemes are often quite simple, typically treating the ORC as an independent waste heat power generation unit. The recovered heat source is singular, and the generated electricity is directly exported, resulting in insufficient coupling depth with the main power generation system and carbon capture process. This model fails to fully achieve system-level energy optimization and closed-loop utilization. The low-temperature waste heat emitted by the ORC system itself is often directly discarded, and the energy loss caused by the carbon capture process and the energy gain brought by the ORC fail to form an effective internal compensation, limiting the overall potential for energy saving and efficiency improvement. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization, which has the advantage of high energy utilization rate.

[0006] The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to embodiments of the present invention includes:

[0007] A coal-fired boiler, wherein the coal-fired boiler has a flue gas outlet and a steam outlet; A steam turbine and a condenser, wherein the steam turbine has a steam inlet, a condensate outlet and a first outlet, the steam inlet is connected to the steam outlet and the condensate outlet is connected to the condenser; The boiler includes a regenerative heater and a heat exchanger. The regenerative heater has a condensate inlet and a condensate outlet. The condensate inlet is connected to the condenser, and the condensate outlet is connected to the economizer. The economizer is located inside the coal-fired boiler and upstream of the flue gas outlet. The regenerative heater is connected to the heat exchanger so that the organic working fluid circulates between the regenerative heater and the heat exchanger, and the organic working fluid flowing from the heat exchanger to the regenerative heater is used to preheat the condensate in the regenerative heater. The regenerative heater is connected to the first outlet, and the steam discharged from the first outlet is used to heat the condensate in the regenerative heater. A carbon capture assembly is connected to the flue gas outlet. The carbon capture assembly has a heat source outlet connected to the hot-side inlet of the heat exchanger. The heat source discharged from the heat source outlet is used to exchange heat with the organic working fluid in the heat exchanger.

[0008] The coal-fired power generation system based on waste heat recovery and cascade utilization of carbon capture in this embodiment of the invention utilizes the waste heat generated during the carbon capture process to drive the internal circulation of the system. The heat generated by this circulation is directly used to compensate for the loss of the main system's preheating capacity due to carbon capture, directly mitigating the negative impact of carbon capture on net power generation output. This achieves cascade and closed-loop utilization of energy, eliminates the waste of low-temperature waste heat, and deeply integrates the recovered energy into the main thermal process, thereby improving the overall system efficiency.

[0009] In some embodiments, the turbine further has a second outlet, and the regeneration tower of the carbon capture assembly has a heat source inlet and a heat source outlet, the second outlet being connected to the heat source inlet.

[0010] In some embodiments, the first outlet is located in the intermediate-pressure cylinder or the low-pressure cylinder of the steam turbine, and the second outlet is located in the intermediate-pressure cylinder of the steam turbine.

[0011] In some embodiments, the hot-side outlet of the heat exchanger is connected to the condenser so that the steam discharged from the heat exchanger is introduced into the condenser.

[0012] In some embodiments, the coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization of the present invention further includes an expander, which is disposed between the heat exchanger and the regenerative heater, and the cold side outlet of the heat exchanger is connected to the expander.

[0013] In some embodiments, the coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization of the present invention further includes a pump, which is located between the heat exchanger and the regenerating heater. The pump is connected to the cold-side inlet of the heat exchanger to drive the organic working fluid to circulate between the heat exchanger and the regenerating heater.

[0014] In some embodiments, the regenerative heater has a preheating inlet and a heating inlet, the preheating inlet being connected to the expander and the heating inlet being connected to the first outlet.

[0015] In some embodiments, the preheating inlet is located upstream of the heating inlet in the direction of condensate flow in the regenerating heater.

[0016] In some embodiments, the temperature of the organic working fluid vapor at the outlet of the expander is 80°C to 110°C.

[0017] In some embodiments, the condensate flowing out of the condenser has a temperature of 30°C to 50°C, and the condensate flowing out of the regenerator to the economizer has a temperature of 270°C to 300°C. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization, according to an embodiment of the present invention.

[0019] Figure label: 1. Coal-fired boiler; 11. Flue gas outlet; 12. Steam outlet; 13. Economizer. 2. Steam turbine; 21. Steam inlet; 22. Condensate outlet; 23. First outlet; 24. Second outlet. 3. Condenser, 4. Regenerator; 41. Condensate inlet; 42. Condensate outlet; 43. Preheating inlet; 44. Heating inlet. 5. Heat exchanger 6. Carbon capture unit, 7. Expander 8. Pumps. Detailed Implementation

[0020] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0021] like Figure 1 As shown, the coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization according to an embodiment of the present invention includes: a coal-fired boiler 1, a steam turbine 2, a condenser 3, a regenerative heater 4, a heat exchanger 5, and a carbon capture assembly 6. The coal-fired boiler 1 has a flue gas outlet 11 and a steam outlet 12. The steam turbine 2 has a steam inlet 21, a condensate outlet 22, and a first outlet 23. The steam inlet 21 is connected to the steam outlet 12, and the condensate outlet 22 is connected to the condenser 3. The regenerative heater 4 has a condensate inlet 41 and a condensate outlet 42. The condensate inlet 41 is connected to the condenser 3, and the condensate outlet 42 is connected to the economizer 13. The economizer 13 is located within the coal-fired boiler 1 and upstream of the flue gas outlet 11. The regenerative heater 4 is connected to a heat exchanger 5 to allow the organic working fluid to circulate between the regenerative heater 4 and the heat exchanger 5. The organic working fluid flowing from the heat exchanger 5 to the regenerative heater 4 is used to preheat the condensate within the regenerative heater 4. The regenerative heater 4 is connected to the first outlet 23, and the steam discharged from the first outlet 23 is used to heat the condensate within the regenerative heater 4. The carbon capture assembly 6 is connected to the flue gas outlet 11. The carbon capture assembly 6 has a heat source outlet, which is connected to the hot side inlet of the heat exchanger 5. The heat source discharged from the heat source outlet is used to exchange heat with the organic working fluid in the heat exchanger 5.

[0022] Specifically, such as Figure 1 As shown, the coal-fired boiler 1 generates high-temperature flue gas and high-pressure steam. Its steam outlet 12 is connected to the steam inlet 21 of the steam turbine 2, forming the main power generation process. The exhaust steam from the steam turbine 2 after performing work enters the condenser 3 for condensation through its condensate outlet 22. The generated condensate enters the equipment through the condensate inlet 41 of the regenerator heater 4.

[0023] After being preheated in the regenerator 4, the condensate is sent to the economizer 13 in the boiler through its condensate outlet 42, and finally returns to the boiler, completing the cycle. The economizer 13 is located upstream of the boiler flue gas outlet 11, and can further utilize the heat of the flue gas.

[0024] The flue gas outlet 11 of the coal-fired boiler 1 is connected to the inlet of the carbon capture assembly 6, where the flue gas undergoes decarbonization treatment. The medium- and low-temperature waste heat generated by the carbon capture assembly 6 (especially in its absorbent regeneration stage) is output to the heat exchanger 5 through the heat source outlet. That is, the heat source outlet of the carbon capture assembly 6 is directly connected to the hot-side inlet of the heat exchanger 5 to introduce the waste heat generated by the carbon capture assembly 6 into the heat exchanger 5.

[0025] Heat exchanger 5 and regenerator 4 are connected by pipes, forming a closed organic working fluid heat cycle between them. The organic working fluid, heated by waste heat from carbon capture in heat exchanger 5, is then transported to the regenerator 4. Inside the regenerator 4, the heat from the organic working fluid is used to preheat the main system condensate from condenser 3. Simultaneously, the regenerator 4 is also connected to the first outlet 23 of turbine 2 via another interface, receiving a portion of the extracted steam from turbine 2, which is also used to heat the condensate.

[0026] Understandably, the connection between the heat source outlet of the carbon capture assembly 6 and the hot-side inlet of the heat exchanger 5 ensures that the medium- and low-temperature waste heat generated during the carbon capture process, which would otherwise be discarded or difficult to utilize, is collected and introduced into the heat exchanger 5 for the purpose of waste heat recovery and recycling. This provides a source and possibility for using waste heat to compensate for the energy loss caused by the carbon capture process itself.

[0027] The organic working fluid circulates between the regenerator 4 and the heat exchanger 5 and is used to preheat the condensate, ensuring that the recovered heat is not released to the outside but flows directionally within the system. Specifically, heat flows out from the carbon capture unit, exchanges heat with the organic working fluid in the heat exchanger 5, and then the organic working fluid ultimately injects heat back into the regenerator 4. This achieves direct internal feedback of the recovered heat to the main system and forms a complete closed loop from waste heat generation to waste heat utilization, preventing energy loss outside the system boundary.

[0028] The regenerative heater 4 is simultaneously connected to the organic working fluid cycle and the first outlet 23 of the turbine 2, making it a heat integration point with multiple heat sources. In other words, when carbon capture operation and steam extraction from the main system result in insufficient preheating heat, the heat provided by the waste heat recovery cycle can supplement this gap. Conversely, it can primarily rely on extracted steam, ensuring that the regenerative heater 4 has a heat compensation mechanism.

[0029] Therefore, the coal-fired power generation system based on waste heat recovery and cascade utilization of carbon capture in this embodiment of the invention utilizes the waste heat generated by the carbon capture process itself to drive the internal circulation of the system, and directly uses the heat generated by this circulation to compensate for the loss of the main system's preheating capacity due to carbon capture, directly reducing the negative impact of carbon capture on net power generation output, realizing cascade and closed-loop utilization of energy, eliminating the waste of low-temperature waste heat, and deeply integrating the recovered energy into the main thermal process, thereby improving the efficiency of the entire system.

[0030] In some embodiments, the turbine 2 also has a second outlet 24, and the regeneration tower of the carbon capture assembly 6 has a heat source inlet and a heat source outlet, with the second outlet 24 connected to the heat source inlet.

[0031] Specifically, such as Figure 1 As shown, the second outlet 24 of the steam turbine 2 (which can be the extraction port of the intermediate pressure cylinder) is directly connected to the heat source inlet of the regeneration tower of the carbon capture assembly 6. The heat source outlet of the regeneration tower is connected to the hot side inlet of the pipeline heat exchanger 5.

[0032] Understandably, the steam discharged from the second outlet 24 of turbine 2 provides a direct heat source for the regeneration tower. That is, the steam from the second outlet 24 of turbine 2 can be directly used to drive the regeneration process of the absorbent, ensuring the stability and reliability of the carbon capture assembly 6.

[0033] It should be noted that the steam discharged from the second outlet 24 passes through the regeneration tower and then enters the heat exchanger 5, as well as the subsequent reheating of the organic working fluid, thus realizing a series of heat utilization in a cascade manner.

[0034] The first stage of utilization involves drawing high-quality steam from the second outlet 24 of turbine 2, which is then heated and regenerated in the regeneration tower to regenerate the absorbent. During this process, some of the steam's heat is consumed, and its temperature decreases. The second stage utilizes the reduced-temperature waste heat discharged from the heat source outlet of the regeneration tower, which is then introduced into heat exchanger 5 to heat the organic working fluid. The third stage utilizes the heated organic working fluid, which subsequently releases heat in the regenerator 4 to preheat the condensate of the main system. Therefore, the heat energy extracted from turbine 2 is sequentially used in the regeneration tower, organic working fluid circulation, and main system regeneration, achieving three stages of energy utilization and improving the overall efficiency of single-stream heat energy utilization.

[0035] In some embodiments, the first outlet 23 is provided in the intermediate pressure cylinder or the low pressure cylinder of the steam turbine 2, and the second outlet 24 is provided in the intermediate pressure cylinder of the steam turbine 2.

[0036] Understandably, the steam parameters (pressure and temperature) of the low-pressure cylinder are relatively low. Extracting this steam and directly introducing it into the regenerator 4 for preheating condensate achieves a proper heat matching. The preheating process of condensate itself requires medium-to-low temperature heat. That is, when turbine 2 enters a stable power generation operation state, some steam from the medium-pressure cylinder can be extracted, or steam can be directly extracted from the low-pressure cylinder to meet the preheating requirement, avoiding the energy waste caused by extracting high-quality steam from a higher-pressure cylinder for low-temperature operations.

[0037] Carbon capture and regeneration towers typically require medium-temperature, medium-pressure steam (e.g., temperatures between 150°C and 250°C) to provide regeneration heat; therefore, the extracted steam must meet this minimum parameter requirement. Furthermore, the specific design location of the extraction port of the medium-pressure cylinder determines the precise parameters of the extracted steam. This location needs to be determined based on actual operating conditions and corresponding calculations to ensure that, under typical operating loads, the steam parameters at the extraction point can cover the regeneration tower's requirements.

[0038] It should be noted that extracting steam from the turbine's second cylinder alters the steam flow rate and expansion process within the cylinder. The extraction rate must be controlled within the design limits to ensure that critical parameters such as the turbine's second rotor's axial thrust and blade stress remain within safe limits, thus avoiding any impact on unit safety. Steam extraction reduces the steam flow rate and work capacity of the subsequent low-pressure cylinder, thereby decreasing the total power generation output of the turbine. Therefore, the extraction rate needs to be optimized between meeting carbon capture heat requirements and minimizing power generation losses. Of course, the extraction rate will be adjusted based on the real-time load of the carbon capture assembly 6.

[0039] In some embodiments, the hot-side outlet of the heat exchanger 5 is connected to the condenser 3 so that the steam discharged from the heat exchanger 5 is fed into the condenser 3.

[0040] Specifically, such as Figure 1 As shown, the waste heat generated by the carbon capture and regeneration tower is discharged from its heat source outlet and enters the hot side inlet of heat exchanger 5. In heat exchanger 5, this heat is transferred to the organic working fluid circulation. After the heat exchange is completed, the medium, whose temperature has been significantly reduced (e.g., becoming low-temperature steam or condensate), is discharged from the hot side outlet of heat exchanger 5 and guided to condenser 3.

[0041] The waste heat medium (steam) generated during the carbon capture process, after exchanging heat with the organic working fluid, is not directly discharged or discarded, but is instead transported to condenser 3. This achieves complete in-system recovery of the waste heat medium, avoiding additional water or steam losses and meeting the economic and environmental requirements of power plant operation.

[0042] In some embodiments, the coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization of the present invention further includes an expander 7, which is located between the heat exchanger 5 and the regenerating heater 4, and the cold side outlet of the heat exchanger 5 is connected to the expander 7.

[0043] An expander 7 is a device that converts thermal energy into mechanical energy or electrical energy. In this system, its function is to expand a high-temperature, high-pressure organic working fluid to do work, thereby outputting useful work (such as driving a generator to generate electricity or directly driving equipment such as pumps).

[0044] Understandably, the expander 7 is positioned on the organic working fluid circulation path between the heat exchanger 5 and the regenerating heater 4. Specifically, the organic working fluid (typically in a high-temperature, high-pressure state) that flows out from the cold side outlet of the heat exchanger 5 and has been heated by carbon capture waste heat first enters the expander 7 and then flows to the regenerating heater 4.

[0045] In other words, after the expander 7 performs work, the pressure and temperature of the organic working fluid will decrease. At this time, the temperature difference between the organic working fluid entering the regenerator 4 and the low-temperature condensate that needs to be preheated is more reasonable, which helps to achieve a smoother and more efficient heat exchange in the regenerator 4, reduce irreversible losses in the heat exchange process, and further optimize the thermal economy of the preheating process.

[0046] In some embodiments, the coal-fired power generation system based on carbon capture waste heat recovery and cascade utilization of the present invention further includes a pump 8, which is located between the heat exchanger 5 and the regenerating heater 4. The pump 8 is connected to the cold side inlet of the heat exchanger 5 to drive the organic working fluid to circulate between the heat exchanger 5 and the regenerating heater 4.

[0047] Pump 8 provides the necessary pressure boost to the circulating working fluid, which can overcome the flow resistance of the system pipeline, heat exchanger 5 and other equipment, and ensure that the working fluid can flow stably through heat exchanger 5 (heat absorption) and regenerator 4 (heat release) at the required flow rate and pressure.

[0048] Understandably, pump 8, as a fluid drive device, is integrated into the organic working fluid circulation loop. Specifically, pump 8 is located upstream of the cold side inlet of heat exchanger 5 (i.e., before the working fluid flows into heat exchanger 5). The low-temperature, low-pressure organic working fluid that has completed heat release and flows out from regenerating heater 4 first enters pump 8.

[0049] In other words, without the forced driving force provided by pump 8, relying solely on natural convection or density difference, it is difficult for the organic working fluid to achieve stable and sufficient circulation in a complex loop containing multiple heat exchange devices, bends, and resistance. Furthermore, by providing an adjustable head, pump 8 enables the system to precisely control the circulation flow rate of the organic working fluid according to changes in the carbon capture waste heat load, thereby matching varying heat absorption and release demands and ensuring stable and efficient system operation under any conditions.

[0050] In some embodiments, the regenerator 4 has a preheating inlet 43 and a heating inlet 44, the preheating inlet 43 being connected to the expander 7 and the heating inlet 44 being connected to the first outlet 23.

[0051] Specifically, such as Figure 1 As shown, preheating inlet 43 is used to receive the organic working fluid from the outlet of expander 7. This means the organic working fluid has already done work in expander 7, its temperature and pressure have decreased, and it carries the residual heat recovered from carbon capture waste heat and partially utilized (for power generation). Heating inlet 44 is used to receive steam (typically low-pressure cylinder extraction steam) from the first outlet 23 of turbine 2. This steam comes from the main power generation system itself and is a conventional heat source for preheating condensate. These two independent inlets on the regenerator 4 structurally physically separate the recovered waste heat from the extraction steam heat of the main system itself, clearly defining their different paths into the regenerator 4.

[0052] It is understandable that the organic working fluid from expander 7 and the steam (gaseous) from turbine 2 may have significant differences in their physical properties (such as specific heat capacity and heat transfer coefficient), temperature range, and flow characteristics. Providing a separate inlet for the regenerator 4 allows for the design of optimal heat exchange channels or regions (e.g., different tube bundle arrangements and heat exchange area distribution) for these two media within the regenerator 4. This avoids premature mixing or interference between the two media at the inlet, thereby improving the overall heat exchange efficiency of the regenerator 4 and reducing unnecessary heat exchange losses.

[0053] Preferably, in the direction of condensate flow in the regenerator 4, the preheating inlet 43 is located upstream of the heating inlet 44.

[0054] Understandably, condensate enters the regenerator 4 from condensate inlet 41, flows through the internal heat exchange zone, and finally exits from condensate outlet 42, heading towards the economizer 13. In this flow path, the condensate first flows through the heat exchange zone connected to the preheating inlet 43, and then through the heat exchange zone connected to the heating inlet 44. The condensate is sequentially heated by the organic working fluid (recovered waste heat) from the expander 7 and the extracted steam (main system heat source) from the turbine 2.

[0055] In other words, the organic working fluid from preheating inlet 43 derives its heat from waste heat from carbon capture and has already done work in expander 7, therefore its temperature is relatively low. The extracted steam from heating inlet 44 comes directly from the main steam cycle and has a relatively high temperature.

[0056] In other words, the low-temperature condensate is first preheated using low-temperature recovered waste heat. Once its temperature rises, it is then finally heated using high-temperature steam extracted from the main system to reach the target temperature. This avoids the waste of high-grade steam heat in the low-temperature preheating stage, ensuring that the use of heat matches its temperature potential, reducing unnecessary energy degradation losses, and improving the thermal economy of the entire preheating process.

[0057] In some embodiments, the temperature of the organic working fluid vapor at the outlet of the expander 7 is 80°C to 110°C.

[0058] Understandably, controlling the outlet temperature of expander 7 at 80℃~110℃ allows the system to capture waste heat from carbon and convert it into two parts: one part is high-grade power / electricity; the other part is low-temperature heat with a grade just suitable for preheating requirements. This avoids the huge waste caused by directly using high-grade heat for low-temperature tasks and achieves the corresponding use of heat.

[0059] As mentioned earlier, the preheating inlet 43 is located upstream of the condensate flow channel. The initial temperature of the condensate is typically low (e.g., 30°C-50°C). The temperature difference between the organic working fluid steam (80°C-110°C) and the low-temperature condensate is moderate. This moderate temperature difference is beneficial for efficient and stable heat exchange during the preheating stage.

[0060] If the outlet temperature of expander 7 is too high (e.g., exceeding 150°C), the condensate may be heated to near or above the temperature required for extraction steam at the subsequent heating inlet 44 during the preheating stage. This would disrupt the cascade heating logic and may result in ineffective utilization of the extracted steam heat or the need for additional cooling. Therefore, a temperature range of 80°C to 110°C ensures that the recovered waste heat can effectively and reasonably raise the condensate temperature during the preheating stage, reserving appropriate temperature rise space for the subsequent extraction steam heating stage, making the entire preheating process smooth and thermodynamically sound.

[0061] In some embodiments, the condensate temperature flowing out of the condenser 3 is 30°C to 50°C, and the condensate temperature flowing out of the regenerator 4 to the economizer 13 is 270°C to 300°C.

[0062] Understandably, the outlet temperature of condenser 3 is the initial temperature of the condensate after condensation in condenser 3, while the outlet temperature of the organic working fluid in expander 7 is 80℃~110℃. There is a temperature difference of approximately 30℃~60℃ between the two. This temperature difference range is effective, allowing the recovered waste heat from expander 7 to serve as a first-stage heat source for preliminary and efficient preheating of the low-temperature condensate. The lower initial temperature means that the condensate has a greater potential for temperature increase, requiring multi-stage heating.

[0063] The outlet temperature of the regenerator 4 is the final temperature of the condensate after preheating in the regenerator 4 before entering the economizer 13. The economizer 13 utilizes the waste heat from the boiler flue gas to further heat the feedwater. A higher feedwater temperature (270℃~300℃) can improve the heat exchange efficiency of the economizer 13 and prevent internal problems in the heat exchanger 5 caused by low-temperature feedwater. A higher feedwater temperature reduces the energy required for the boiler to heat the water to boiling, thus improving the overall thermal efficiency of the main steam cycle.

[0064] In other words, the total heat required to heat condensate from 30℃~50℃ to 270℃~300℃ is enormous. The recovered waste heat, through preheating inlet 43, handles a portion of the lower-temperature stage (e.g., heating from 30℃ to 100℃), directly reducing the amount of high-temperature steam that needs to be extracted from turbine 2. This reduced steam extraction quantifies the compensation effect of carbon capture waste heat recovery on the main system's energy losses. Clearly defined start and end temperatures provide a clear target for the control system. The control system needs to coordinate preheating inlet 43 (organic working fluid flow rate) and heating inlet 44 (steam extraction flow rate) to ensure that regardless of fluctuations in the initial condensate temperature, the target value of 270℃~300℃ is consistently achieved.

[0065] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0066] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0067] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0068] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0069] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0070] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization, characterized in that, include: A coal-fired boiler, wherein the coal-fired boiler has a flue gas outlet and a steam outlet; A steam turbine and a condenser, wherein the steam turbine has a steam inlet, a condensate outlet and a first outlet, the steam inlet is connected to the steam outlet and the condensate outlet is connected to the condenser; The boiler includes a regenerative heater and a heat exchanger. The regenerative heater has a condensate inlet and a condensate outlet. The condensate inlet is connected to the condenser, and the condensate outlet is connected to the economizer. The economizer is located inside the coal-fired boiler and upstream of the flue gas outlet. The regenerative heater is connected to the heat exchanger so that the organic working fluid circulates between the regenerative heater and the heat exchanger, and the organic working fluid flowing from the heat exchanger to the regenerative heater is used to preheat the condensate in the regenerative heater. The regenerative heater is connected to the first outlet, and the steam discharged from the first outlet is used to heat the condensate in the regenerative heater. A carbon capture assembly is connected to the flue gas outlet. The carbon capture assembly has a heat source outlet connected to the hot-side inlet of the heat exchanger. The heat source discharged from the heat source outlet is used to exchange heat with the organic working fluid in the heat exchanger.

2. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 1, characterized in that, The steam turbine also has a second outlet, and the regeneration tower of the carbon capture assembly has a heat source inlet and a heat source outlet, with the second outlet connected to the heat source inlet.

3. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 2, characterized in that, The first outlet is located in the intermediate pressure cylinder or the low pressure cylinder of the steam turbine, and the second outlet is located in the intermediate pressure cylinder of the steam turbine.

4. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 3, characterized in that, The hot-side outlet of the heat exchanger is connected to the condenser so that the steam discharged from the heat exchanger can be introduced into the condenser.

5. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 1, characterized in that, It also includes an expander, which is located between the heat exchanger and the regenerating heater, and the cold-side outlet of the heat exchanger is connected to the expander.

6. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 5, characterized in that, It also includes a pump located between the heat exchanger and the regenerating heater, the pump being connected to the cold-side inlet of the heat exchanger to drive the organic working fluid to circulate between the heat exchanger and the regenerating heater.

7. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 6, characterized in that, The regenerative heater has a preheating inlet and a heating inlet. The preheating inlet is connected to the expander, and the heating inlet is connected to the first outlet.

8. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 7, characterized in that, In the direction of condensate flow in the regenerating heater, the preheating inlet is located upstream of the heating inlet.

9. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to any one of claims 5-8, characterized in that, The temperature of the organic working fluid vapor at the outlet of the expander is 80℃~110℃.

10. The coal-fired power generation system based on carbon capture, waste heat recovery, and cascade utilization according to claim 1, characterized in that, The condensate flowing out of the condenser has a temperature of 30℃~50℃, and the condensate flowing out of the regenerator to the economizer has a temperature of 270℃~300℃.

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