A combined cycle system and method based on supercritical carbon dioxide

Abstract

This application discloses a combined cycle system and method based on supercritical carbon dioxide, relating to the technical field of thermodynamics. The system includes a heat source, with its outlet connected to a first heat source working fluid heat exchanger and a second heat source working fluid heat exchanger, allowing fluid from the heat source to enter both heat source working fluid heat exchangers. The outlet of the first heat source working fluid heat exchanger is connected to a first turbine and a first re-compressor, with the outlet of the first re-compressor connected to the inlet of the first heat source working fluid heat exchanger. The outlet of the second heat source working fluid heat exchanger is sequentially connected to a second turbine, a third turbine, and a second re-compressor, with the outlet of the second re-compressor connected to a second high-temperature regenerator, and the outlet of the second high-temperature regenerator connected to the inlet of the second heat source working fluid heat exchanger. This application optimizes the system's thermodynamic performance and economy, enhances its adaptability and operational stability, improves overall energy conversion efficiency, and adapts to various heat source conditions.

Description

Technical Field

[0001] This application relates to the technical field of thermodynamics, specifically to a combined cycle system and method based on supercritical carbon dioxide. Background Technology

[0002] Carbon dioxide, as a working fluid in the cycle, has a low critical parameter (304.13K / 7.37MPa), and it easily reaches the supercritical state. Its chemical reaction rate with metallic materials is lower than that of water vapor, which makes the working fluid of the supercritical carbon dioxide Brayton cycle a non-toxic, non-flammable, colorless and odorless natural working fluid.

[0003] Among related technologies, supercritical carbon dioxide Brayton cycle systems have been widely used in the energy sector, especially in nuclear and solar power generation, in recent years due to their high efficiency, compact structure, and low environmental impact. However, existing supercritical carbon dioxide cycle systems suffer from drawbacks such as complex structure, high operating costs, and insufficient thermodynamic efficiency in some cooled cycle systems. Summary of the Invention

[0004] To address at least one of the problems mentioned in the background art, this application provides a combined cycle system and method based on supercritical carbon dioxide. By combining a reheat-recompression cycle system with a partially cooled cycle system, the thermodynamic performance and economy of the system are optimized, the adaptability and operational stability of the system are enhanced, thereby improving the overall energy conversion efficiency and adapting to various heat source conditions.

[0005] The specific technical solutions provided in this application are as follows:

[0006] In a first aspect, a combined cycle system based on supercritical carbon dioxide is provided, the system including a heat source, the outlet of which is respectively connected to a first heat source working fluid heat exchanger and a second heat source working fluid heat exchanger, so that the fluid in the heat source enters the first heat source working fluid heat exchanger and the second heat source working fluid heat exchanger respectively.

[0007] The outlet end of the first heat source working fluid heat exchanger is sequentially connected to the first turbine, the first high-temperature regenerator, the first low-temperature regenerator, the first pre-compressor, and the first re-compressor. The outlet end of the first re-compressor is connected to the inlet end of the first heat source working fluid heat exchanger.

[0008] The outlet end of the second heat source working fluid heat exchanger is sequentially connected to the second turbine, reheater, third turbine, second high-temperature regenerator, second low-temperature regenerator and second re-compressor. The outlet end of the second re-compressor is connected to the second high-temperature regenerator, and the outlet end of the second high-temperature regenerator is connected to the inlet end of the second heat source working fluid heat exchanger.

[0009] In one specific embodiment, the outlet end of the heat source is connected to a first regulating valve, which is a three-way valve, and at least two outlet ends of the first regulating valve are respectively connected to the inlet ends of the first heat source working fluid heat exchanger and the second heat source working fluid heat exchanger.

[0010] In one specific embodiment, the first low-temperature regenerator is also connected to a first precooler, which is used to cool the fluid in the first low-temperature regenerator to a preset temperature.

[0011] In one specific embodiment, the outlet end of the first pre-compressor is connected to the first re-compressor and the intercooler, respectively. The outlet end of the intercooler is connected to the first main compressor, and the outlet end of the first main compressor is connected to the first low-temperature regenerator.

[0012] In one specific embodiment, a second regulating valve is also included. The second regulating valve is a three-way valve. The two inlet ends of the second regulating valve are respectively connected to the outlet end of the first low-temperature regenerator and the outlet end of the first recompressor. The outlet end of the second regulating valve is connected to the first high-temperature regenerator.

[0013] In one specific embodiment, the outlet end of the second low-temperature regenerator is connected to a third regulating valve, which is a three-way valve. At least one outlet end of the third regulating valve is sequentially connected to a second precooler and a second main compressor, and the outlet end of the second main compressor is connected to the second low-temperature regenerator.

[0014] In one specific embodiment, the other outlet end of the third regulating valve is connected to the second recompressor.

[0015] In one specific embodiment, a fourth regulating valve is also included. The fourth regulating valve is a three-way valve. At least two inlet ends of the fourth regulating valve are respectively connected to the outlet end of the second low-temperature regenerator and the outlet end of the second recompressor. The outlet end of the fourth regulating valve is connected to the second high-temperature regenerator.

[0016] In one specific embodiment, the first turbine is connected to the first engine, the second turbine is connected to the second engine, and the third turbine is connected to the third engine, wherein the first turbine, the second turbine, and the third turbine are not coaxial.

[0017] Secondly, a combined cycle method based on supercritical carbon dioxide is provided, which is applied to the supercritical carbon dioxide-based combined cycle system described above.

[0018] The embodiments of this application have the following beneficial effects:

[0019] 1. The combined cycle system provided in this application connects a first heat source working fluid heat exchanger and a second heat source working fluid heat exchanger to the outlet end of the heat source, wherein the first heat source working fluid heat exchanger and the second heat source working fluid heat exchanger are respectively associated with two loop cycle systems, so as to realize the expansion, cooling, compression and heating of the supercritical carbon dioxide fluid flowing into it through two parallel cycle systems, so as to improve the cycle efficiency and power generation efficiency of the combined system.

[0020] 2. Simultaneously, the flow rate of supercritical carbon dioxide distributed to the first and second heat source working fluid heat exchangers is adjusted according to the temperature of the heat source and the requirements of thermodynamic parameters. By distributing heat in the two loops, the flow rate of supercritical carbon dioxide working fluid entering the two loops is controlled to improve the work capacity of the supercritical carbon dioxide working fluid, while achieving flexible response to changes in external design requirements. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A schematic diagram of a combined cycle system based on supercritical carbon dioxide according to this application is shown;

[0023] Figure 2 A schematic diagram showing the effect of the lowest cycling temperature on the system's thermal efficiency and specific work according to this application is provided.

[0024] Figure 3 This illustrates the system based on the lowest cyclic temperature described in this application. A diagram illustrating the impact of efficiency and total cost ratio;

[0025] Figure 4 A schematic diagram showing the effect of the minimum cyclic pressure on the system thermal efficiency and specific work according to this application is shown.

[0026] Figure 5 This illustrates the system based on the minimum cyclic pressure in this application. A diagram illustrating the impact of efficiency and total cost ratio;

[0027] Figure 6 A schematic diagram showing the effect of the highest circulating temperature on the system's thermal efficiency and specific work according to this application is provided.

[0028] Figure 7 This shows the system based on the highest cyclic temperature in this application. A diagram illustrating the impact of efficiency and total cost ratio;

[0029] Figure 8 This diagram illustrates the influence of the circulating pressure ratio on the performance evaluation index of the circulating system according to this application.

[0030] Figure 9 This diagram illustrates the effect of the compressor's isentropic efficiency on the system's thermal efficiency and specific work, according to this application.

[0031] Figure 10 This illustrates the effect of the compressor's isentropic efficiency on the system according to the present application. A diagram illustrating the impact of efficiency and total cost ratio;

[0032] Figure 11 This diagram illustrates the influence of the entropy efficiency of the through-hole system on the thermal efficiency and specific work of the system according to this application.

[0033] Figure 12 This application illustrates the entropy efficiency of the system based on the permeability and entropy efficiency described herein. A diagram illustrating the impact of efficiency and total cost ratio;

[0034] In the diagram, 1. Heat source; 2. First heat source working fluid heat exchanger; 3. Second heat source working fluid heat exchanger; 4. First regulating valve; 5. First turbine; 6. First high-temperature regenerator; 7. First low-temperature regenerator; 8. First precooler; 9. First pre-compressor; 10. First recompressor; 11. Second regulating valve; 12. Second turbine; 13. Reheater; 14. Third turbine; 15. Second high-temperature regenerator; 16. Second low-temperature regenerator; 17. Second recompressor; 18. Third regulating valve; 19. Second precooler; 20. Second main compressor; 21. Fourth regulating valve; 22. First engine; 23. Second engine; 24. Third engine; 25. Intercooler; 26. First main compressor; 27. Fifth regulating valve. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0038] Example 1

[0039] Provides a combined cycle system based on supercritical carbon dioxide, such as Figure 1 As shown, the system includes a heat source 1, the outlet of which is connected to a first heat source working fluid heat exchanger 2 and a second heat source working fluid heat exchanger 3, so that the fluid in the heat source 1 enters the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3 respectively. The heat source 1 is coupled through the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3. The circulation loop associated with the first heat source working fluid heat exchanger 2 is configured as a supercritical CO2 reheat and recompression circulation loop, and the circulation loop associated with the second heat source working fluid heat exchanger 3 is configured as a supercritical CO2 partial cooling circulation loop. This allows the supercritical carbon dioxide fluid flowing into the system to be expanded, cooled, compressed, and heated simultaneously through the two systems, thereby increasing the circulation efficiency and power generation efficiency of the combined system.

[0040] It should be noted that in this embodiment, the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3 are configured as CO2-heat source working fluid-CO2 heat exchangers.

[0041] Furthermore, a first regulating valve 4 is connected to the outlet end of heat source 1. The first regulating valve 4 is selected as a three-way valve, wherein the first regulating valve 4 includes two outlet ends and one inlet end. The two outlet ends of the first regulating valve 4 are respectively connected to the inlet ends of the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3, so as to realize the adjustment of the proportion of fluid in heat source 1 entering the two systems through the first regulating valve 4.

[0042] like Figure 1As shown, in this embodiment, the outlet end of the first heat source working fluid heat exchanger 2 is sequentially connected to the first turbine 5, the first high-temperature regenerator 6, the first low-temperature regenerator 7, and the first precooler 8. The outlet end of the first precooler 8 is also sequentially connected to the first pre-compressor 9 and the first re-compressor 10. The outlet end of the first re-compressor 10 is connected to the inlet end of the first heat source working fluid heat exchanger 2. The outlet end of the first pre-compressor 9 is divided into two fluid streams, namely, the outlet end of the first pre-compressor 9 is connected to the first re-compressor 10 and the intercooler 25 respectively. The outlet end of the intercooler 25 is connected to the first main compressor 26. The outlet end of the first main compressor 26 is connected to the first low-temperature regenerator 7.

[0043] When the system starts running, the working fluid is heated by the first heat source working fluid heat exchanger 2, expands in the first turbine 5 to generate electricity, and after the working fluid has completed its work, it sequentially enters the first high-temperature regenerator 6 and the first low-temperature regenerator 7 to recover and utilize the heat. It is discharged from the outlet of the first low-temperature regenerator 7 and flows into the first precooler 8 for cooling. After the working fluid is cooled to the critical state of carbon dioxide fluid, it enters the first pre-compressor 9, and is divided into two streams at the outlet of the first pre-compressor 9. The first stream of fluid flows into the first main compressor 26 after passing through the intercooler 25. After completing the pressurization process in the first main compressor 26, this part of the fluid enters the first low-temperature regenerator 7 to absorb the heat released by the high-temperature heat flow.

[0044] Furthermore, the system also includes a second regulating valve 11, which is selected as a three-way valve. The second regulating valve 11 includes two inlet ends and one outlet end. The two inlet ends of the second regulating valve 11 are respectively connected to the outlet end of the first low-temperature regenerator 7 and the outlet end of the first re-compressor 10. The outlet end of the second regulating valve 11 is connected to the first high-temperature regenerator 6, so that the second stream of fluid flows directly into the first re-compressor 10. After the first re-compressor 10 completes the pressurization process, it mixes with the first stream of fluid heated by the first main compressor 26 and the first low-temperature regenerator 7 in the second regulating valve 11. The mixed fluid flows through the first high-temperature regenerator 6 to absorb heat, and then re-enters the working fluid heat exchanger of the first heat source 1 to continue absorbing heat, completing one cycle.

[0045] like Figure 1As shown, in this embodiment, the outlet end of the second heat source working fluid heat exchanger 3 is sequentially connected to the second turbine 12, reheater 13, third turbine 14, second high-temperature regenerator 15, second low-temperature regenerator 16, and second recompressor 17. The outlet end of the second recompressor 17 is connected to the second high-temperature regenerator 15, and the outlet end of the second high-temperature regenerator 15 is connected to the inlet end of the second heat source working fluid heat exchanger 1. When the system starts running, the working fluid is heated by the second heat source working fluid heat exchanger 3 and then enters the second turbine 12 to expand and generate electricity. After expansion, the working fluid enters the reheater 13 again for heating and then enters the third turbine 14 to expand and generate electricity. After completing the work, the working fluid sequentially enters the second high-temperature regenerator 15 and the second low-temperature regenerator 16 to release heat.

[0046] Furthermore, a third regulating valve 18 is connected to the outlet end of the second low-temperature regenerator 16. The third regulating valve 18 is configured as a three-way valve and includes an inlet end and two outlet ends. One outlet end is connected in sequence to the second precooler 19 and the second main compressor 20. The outlet end of the second main compressor 20 is connected to the second low-temperature regenerator 16. The other outlet end of the third regulating valve 18 is connected to the second re-compressor 17.

[0047] like Figure 1 As shown, the system also includes a fourth regulating valve 21, which is configured as a three-way valve. The fourth regulating valve 21 includes two inlet ends and one outlet end. The two inlet ends of the fourth regulating valve 21 are respectively connected to the outlet end of the second low-temperature regenerator 16 and the outlet end of the second recompressor 17, and the outlet end of the fourth regulating valve 21 is connected to the second high-temperature regenerator 15.

[0048] By combining the third regulating valve 18 and the fourth regulating valve 21, the working fluid is divided into two parts after passing through the third regulating valve 18 at the outlet of the second low-temperature regenerator 16. The first part of the fluid is cooled by the second precooler 19 and flows into the second main compressor 20. After being pressurized, it enters the second low-temperature regenerator 16 to absorb heat. The second part of the fluid directly enters the second re-compressor 17 for pressurization and enters the fourth regulating valve 21 at the same time as the high-pressure fluid heated by the second main compressor 20 and the second low-temperature regenerator 16. The mixture is then mixed in the fourth regulating valve 21. The mixed carbon dioxide fluid is reheated in the second high-temperature regenerator 15 and, after being heated to the preset temperature, enters the second heat source working fluid heat exchanger 3 to continue absorbing heat for the next cycle.

[0049] In one specific embodiment, a fifth regulating valve 27 is connected to the outlet ends of the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3. The fifth regulating valve 27 is a three-way valve, and it includes two inlet ends and one outlet end. That is, the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3 are connected to the inlet ends of the fifth regulating valve 27, and the outlet end of the fifth regulating valve 27 is connected to the reheater 13. One end of the reheater 13 is connected to the heat source 1 through a pipe to realize the merging of the heat source working fluids that have completed heat exchange in the two heat exchangers. Then, the merged heat source working fluid enters the reheater 13 to reheat the medium-pressure, medium-temperature supercritical carbon dioxide coming out of the third turbine 14 using residual heat. Finally, the heat source working fluid returns to the heat source 1 for heating.

[0050] It should be noted that in this embodiment, the first turbine 5 is connected to the first engine 22, the second turbine 12 is connected to the second engine 23, and the third turbine 14 is connected to the third engine 24, and the first turbine 5, the second turbine 12, and the third turbine 14 are not coaxial; in this embodiment, the various components are connected by pipes to ensure that two adjacent components are in a connected state.

[0051] In this embodiment, the flow rate of supercritical carbon dioxide distributed to the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3 is adjusted according to the temperature of heat source 1 and the thermodynamic parameter requirements. By distributing heat between the two loops, the flow rate of supercritical carbon dioxide working fluid entering the two loops is controlled to improve the work capacity of supercritical carbon dioxide working fluid, while achieving flexible response to changes in external design requirements.

[0052] Furthermore, relevant tests were conducted on the combined cycle system based on supercritical carbon dioxide in this embodiment, specifically including:

[0053] like Figure 2 and Figure 3 As shown, the effect of controlling the minimum circulating temperature on the main performance parameters of the circulating system is illustrated, including the impact of the minimum circulating temperature on the system's thermal efficiency and specific work. Figure 2 and Figure 3 As shown, it can be seen that in the supercritical CO2 reheat and recompression loop configuration associated with the first heat source working fluid heat exchanger 2, the system's cycle thermal efficiency decreases with increasing minimum cycle temperature. Both efficiency and specific work exhibit a decreasing trend with a gradually decreasing rate of decline. The circulation loop associated with the second heat source working fluid heat exchanger 3 is configured as a supercritical CO2 partially cooled circulation loop. As the minimum circulation temperature increases, the circulation thermal efficiency... Efficiency exhibits an upward trend with a gradually decreasing slope, while the specific work of the system is significantly suppressed. The performance of the multi-element combined cycle system is simultaneously affected by the two basic cycle systems mentioned above, mainly depending on the distribution of heat in the two basic cycle systems. Under the heat distribution settings in this embodiment, the multi-element combined cycle system exhibits more characteristics of reheat-recompression cycle loops.

[0054] like Figure 4 and Figure 5 As shown, in a reheat-recompression cycle system, the system's cycle thermal efficiency decreases with increasing minimum cycle pressure. Both efficiency and specific work are significantly improved. For some cooling cycle systems, as the minimum circulation pressure increases, the cycle thermal efficiency and specific work are also significantly improved. Both efficiency and total cost ratio decreased, while the system's specific work increased. The performance of the multi-cycle combined system is influenced by both basic circulation systems mentioned above, primarily depending on the heat distribution within them. Under the heat distribution settings of this embodiment, the performance of the multi-cycle combined system tends to favor the partially cooled circulation system, and its performance evaluation indicators are still more evenly distributed across the three circulation systems. Increasing the minimum operating pressure of the circulation system has an impact on the thermal efficiency of the multi-cycle combined system. While its impact on efficiency is relatively weak, it does promote the specific work and economy of multi-element combined circulation systems.

[0055] like Figure 6 and Figure 7 As shown, with the increase of the maximum cycle temperature, the specific work and cycle of the reheat-recompression, partial cooling, and multi-element combined cycle systems increase. Both efficiency and cycle thermal efficiency are significantly improved. The high turbine inlet temperature is beneficial to improving the thermodynamic and economic performance of the basic cycle system and the multi-element combined cycle system.

[0056] like Figure 8 As shown, with the increase of the circulating pressure ratio, the system's circulating thermal efficiency and Efficiency initially increases and then decreases, while specific work and total cost ratio continue to rise. Among these, thermal efficiency and... Efficiency showed a clear trend of increasing and then decreasing.

[0057] like Figure 9 and Figure 10 As shown, with the increase of the isentropic efficiency of the compressor, the thermal efficiency in both the basic cycle system and the multi-stage combined cycle system increases. Efficiency was significantly improved. Simultaneously, it also significantly promoted the specific work of the circulating system, but it can be seen that the rate of increase in the specific work of the circulating system continuously decreases as the isentropic efficiency of the compressor increases.

[0058] like Figure 11 and Figure 12 As shown, the specific work and thermal efficiency of the circulating system As the entropy efficiency of the power system increases, all thermodynamic properties show an increasing trend, with the specific work increasing at a slightly lower rate than the system's thermal efficiency. The rate of increase in efficiency. As the entropy efficiency of the through circuit increases, the total cost of the system also increases.

[0059] Example 2

[0060] Corresponding to the above embodiments, this application provides a combined cycle method based on supercritical carbon dioxide, which is applied to the supercritical carbon dioxide-based combined cycle system described above.

[0061] In this embodiment, the supercritical carbon dioxide-based combined cycle system includes a temperature detection component and a pressure detection component. The temperature detection component includes, but is not limited to, a temperature sensor. The temperature detection component is used to detect the minimum circulating temperature, the maximum circulating temperature, and the minimum circulating pressure in the cycle system. When the system is running, if the detected minimum circulating temperature exceeds a first preset threshold, the first regulating valve is adjusted to increase the fluid distribution ratio to the first heat source working fluid heat exchanger 2. If the detected maximum circulating temperature exceeds a second preset threshold, the flow rate from heat source 1 to the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3 is directly increased. If the detected minimum circulating pressure exceeds a third preset threshold, the first regulating valve is adjusted to increase the fluid distribution ratio to the second heat source working fluid heat exchanger 3.

[0062] In one specific embodiment, the supercritical carbon dioxide-based combined cycle system includes a heat source 1. The outlet end of the heat source 1 is connected to a first heat source working fluid heat exchanger 2 and a second heat source working fluid heat exchanger 3, respectively, so that the fluid in the heat source 1 enters the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3, respectively. The outlet end of the first heat source working fluid heat exchanger 2 is sequentially connected to a first turbine 5, a first high-temperature regenerator 6, a first low-temperature regenerator 7, a first pre-compressor 9, and a first re-compressor 10. The outlet end of the first re-compressor 10 is connected to the inlet end of the first heat source working fluid heat exchanger 2.

[0063] The outlet end of the second heat source working fluid heat exchanger 3 is sequentially connected to the second turbine 12, reheater 13, third turbine 14, second high-temperature regenerator 15, second low-temperature regenerator 16 and second re-compressor 17. The outlet end of the second re-compressor 17 is connected to the second high-temperature regenerator 15, and the outlet end of the second high-temperature regenerator 15 is connected to the inlet end of the second heat source working fluid heat exchanger 3.

[0064] In one specific embodiment, the outlet end of the heat source 1 is connected to a first regulating valve 4, which is a three-way valve. At least two outlet ends of the first regulating valve 4 are respectively connected to the inlet ends of the first heat source working fluid heat exchanger 2 and the second heat source working fluid heat exchanger 3.

[0065] In one specific embodiment, the first low-temperature regenerator 7 is also connected to a first precooler 8, which is used to cool the fluid in the first low-temperature regenerator 7 to a preset temperature.

[0066] In one specific embodiment, the outlet end of the first pre-compressor 9 is connected to the first re-compressor 10 and the intercooler 25, respectively. The outlet end of the intercooler 25 is connected to the first main compressor 26, and the outlet end of the first main compressor 26 is connected to the first low-temperature regenerator 7.

[0067] In one specific embodiment, a second regulating valve 11 is also included. The second regulating valve 11 is a three-way valve. The two inlet ends of the second regulating valve 11 are respectively connected to the outlet end of the first low-temperature regenerator 7 and the outlet end of the first recompressor 10. The outlet end of the second regulating valve 11 is connected to the first high-temperature regenerator 6.

[0068] In one specific embodiment, the outlet end of the second low-temperature regenerator 16 is connected to a third regulating valve 18, which is a three-way valve. At least one outlet end of the third regulating valve 18 is sequentially connected to a second precooler 19 and a second main compressor 20. The outlet end of the second main compressor 20 is connected to the second low-temperature regenerator 16.

[0069] In one specific embodiment, the other outlet end of the third regulating valve 18 is connected to the second recompressor 17.

[0070] In one specific embodiment, a fourth regulating valve 21 is also included. The fourth regulating valve 21 is a three-way valve. At least two inlet ends of the fourth regulating valve 21 are respectively connected to the outlet end of the second low-temperature regenerator 16 and the outlet end of the second recompressor 17. The outlet end of the fourth regulating valve 21 is connected to the second high-temperature regenerator 15.

[0071] In one specific embodiment, the first turbine 5 is connected to the first engine 22, the second turbine 12 is connected to the second engine 23, and the third turbine 14 is connected to the third engine 24, wherein the first turbine 5, the second turbine 12, and the third turbine 14 are not coaxial.

[0072] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A combined cycle system based on supercritical carbon dioxide, characterized in that, The system includes a heat source (1), the outlet of which is connected to a first heat source working fluid heat exchanger (2) and a second heat source working fluid heat exchanger (3) respectively, so that the fluid in the heat source (1) enters the first heat source working fluid heat exchanger (2) and the second heat source working fluid heat exchanger (3) respectively. The first heat source working fluid heat exchanger (2) and the second heat source working fluid heat exchanger (3) are configured as CO2-heat source working fluid-CO2 heat exchangers. The outlet end of the heat source (1) is connected to a first regulating valve (4), which is a three-way valve. The two outlet ends of the first regulating valve (4) are respectively connected to the inlet ends of the first heat source working fluid heat exchanger (2) and the second heat source working fluid heat exchanger (3). The proportion of fluid in the heat source (1) entering the two systems is adjusted by the first regulating valve (4). When the system is running, if the lowest circulating temperature in the system exceeds a first preset threshold, the first regulating valve (4) is adjusted to increase the fluid distribution ratio to the first heat source working fluid heat exchanger (2). If the highest circulating temperature in the system exceeds a second preset threshold, the flow rate of the heat source (1) to the first heat source working fluid heat exchanger (2) and the second heat source working fluid heat exchanger (3) is increased. If the lowest circulating pressure in the system exceeds a third preset threshold, the first regulating valve (4) is adjusted to increase the fluid distribution ratio to the second heat source working fluid heat exchanger (3). The outlet end of the first heat source working fluid heat exchanger (2) is sequentially connected to the first turbine (5), the first high-temperature regenerator (6), the first low-temperature regenerator (7), the first pre-compressor (9), and the first re-compressor (10), and the outlet end of the first re-compressor (10) is connected to the inlet end of the first heat source working fluid heat exchanger (2). The outlet end of the second heat source working fluid heat exchanger (3) is sequentially connected to the second turbine (12), reheater (13), third turbine (14), second high-temperature regenerator (15), second low-temperature regenerator (16) and second re-compressor (17). The outlet end of the second re-compressor (17) is connected to the second high-temperature regenerator (15), and the outlet end of the second high-temperature regenerator (15) is connected to the inlet end of the second heat source working fluid heat exchanger (3). The outlet end of the first pre-compressor (9) is connected to the first re-compressor (10) and the intercooler (25) respectively. The outlet end of the intercooler (25) is connected to the first main compressor (26). The outlet end of the first main compressor (26) is connected to the first low-temperature regenerator (7). The system also includes a second regulating valve (11), the two inlet ends of which are respectively connected to the outlet end of the first low-temperature regenerator (7) and the outlet end of the first recompressor (10), and the outlet end of the second regulating valve (11) is connected to the first high-temperature regenerator (6). The outlet end of the second low-temperature regenerator (16) is connected to the third regulating valve (18), and at least one outlet end of the third regulating valve (18) is sequentially connected to the second precooler (19) and the second main compressor (20). The outlet end of the second main compressor (20) is connected to the second low-temperature regenerator (16); the other outlet end of the third regulating valve (18) is connected to the second re-compressor (17). The system also includes a fourth regulating valve (21), the two inlet ends of which are connected to the outlet end of the second low-temperature regenerator (16) and the outlet end of the second recompressor (17), respectively, and the outlet end of the fourth regulating valve (21) is connected to the second high-temperature regenerator (15).

2. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that, The first low-temperature regenerator (7) is also connected to a first precooler (8), which is used to cool the fluid in the first low-temperature regenerator (7) to a preset temperature.

3. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that, The second regulating valve (11) is a three-way valve.

4. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that, The third regulating valve (18) is a three-way valve.

5. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that, The fourth regulating valve (21) is a three-way valve.

6. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that, The first turbine (5) is connected to the first engine (22), the second turbine (12) is connected to the second engine (23), and the third turbine (14) is connected to the third engine (24), and the first turbine (5), the second turbine (12) and the third turbine (14) are not coaxial.

7. A combined cycle method based on supercritical carbon dioxide, characterized in that, The method is applied to the supercritical carbon dioxide-based combined cycle system as described in any one of claims 1 to 6.

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