Supercritical carbon dioxide-based combined cycle system and method

Abstract

The invention discloses a combined cycle system and method based on supercritical carbon dioxide, and relates to the technical field of thermodynamics. The system comprises a heat source, the outlet end of the heat source is connected with a first heat source working medium heat exchanger and a second heat source working medium heat exchanger, so that fluid in the heat source enters the first heat source working medium heat exchanger and the second heat source working medium heat exchanger; the outlet end of the first heat source working medium heat exchanger is connected with a first turbine and a first re-compressor; the outlet end of the first re-compressor is connected with the inlet end of the first heat source working medium heat exchanger; the outlet end of the second heat source working medium heat exchanger is sequentially connected with a second turbine, a third turbine and a second re-compressor, the outlet end of the second re-compressor is connected with a second high-temperature heat regenerator, and the outlet end of the second high-temperature heat regenerator is connected with the inlet end of the second heat source working medium heat exchanger. The thermal performance and economical efficiency of the system are optimized, the adaptability and operation stability of the system are enhanced, the overall energy conversion efficiency is improved, and the system adapts to various heat source conditions.

Description

Technical Field

[0001] The present application relates to the technical field of thermodynamics, and in particular to a combined cycle system and method based on supercritical carbon dioxide. Background Art

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

[0003] Among some related technologies, the supercritical carbon dioxide Brayton cycle system has been widely used in the energy field, especially in nuclear and solar power generation in recent years due to its high efficiency, compact structure and low environmental impact. However, the existing supercritical carbon dioxide cycle system has the disadvantages of complex structure and high operating cost, and some cooling cycle systems are insufficient in thermodynamic efficiency. Summary of the invention

[0004] In order to solve at least one of the problems mentioned in the above background technology, the present application provides a combined cycle system and method based on supercritical carbon dioxide. By combining the reheat and recompression type with the partial cooling type cycle system, the thermal performance and economy of the system are optimized, the adaptability and operation stability of the system are enhanced, thereby improving the overall energy conversion efficiency and adapting to a variety of heat source conditions.

[0005] The specific technical solutions provided by the embodiments of this application are as follows:

[0006] In a first aspect, a combined cycle system based on supercritical carbon dioxide is provided, the system comprising a heat source, wherein an outlet end of the heat source is respectively connected to a first heat source working fluid heat exchanger and a second heat source working fluid heat exchanger, so that a 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 medium heat exchanger is connected to the first turbine, the first high temperature regenerator, the first low temperature regenerator, the first pre-compressor and the first re-compressor in sequence, and the outlet end of the first re-compressor is connected to the inlet end of the first heat source working medium heat exchanger;

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

[0009] In a 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 a specific embodiment, the first low-temperature regenerator is further connected to a first precooler, and the first precooler is used to cool the fluid in the first low-temperature regenerator to a preset temperature.

[0011] In a 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 a specific embodiment, it also includes a second regulating valve, which 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, and the outlet end of the second regulating valve is connected to the first high-temperature regenerator.

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

[0014] In a specific embodiment, the other outlet port of the third regulating valve is connected to the second re-compressor.

[0015] In a specific embodiment, it also includes a fourth regulating valve, which 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, and the outlet end of the fourth regulating valve is connected to the second high-temperature regenerator.

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

[0017] In a second aspect, a combined cycle method based on supercritical carbon dioxide is provided, wherein the method is applied to the combined cycle system based on supercritical carbon dioxide as described above.

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

[0019] 1. The combined cycle system provided in the embodiment of the present application is configured to respectively connect a first heat source working fluid heat exchanger and a second heat source working fluid heat exchanger at 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 circulation systems, so as to achieve expansion, cooling, compression and heating of the supercritical carbon dioxide fluid flowing into the two parallel circulation systems at the same time, so as to improve the circulation efficiency and power generation efficiency of the combined system.

[0020] 2. At the same time, the flow rate of supercritical carbon dioxide allocated to the first heat source working fluid heat exchanger and the second heat source working fluid heat exchanger is adjusted according to the temperature of the heat source and the thermodynamic parameter requirements. The heat distribution of the two circuits is used to control the flow rate of supercritical carbon dioxide working fluid entering the two circuits to improve the working capacity of the supercritical carbon dioxide working fluid, and at the same time, flexible response to changes in external design requirements is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0023] Figure 2 A schematic diagram showing the effect of the minimum cycle temperature on the thermal efficiency and specific work of the system according to the present application;

[0024] Figure 3 The minimum temperature of the cycle according to this application is shown Schematic diagram of the impact of efficiency and total cost rate;

[0025] Figure 4 A schematic diagram showing the effect of the minimum cycle pressure on the thermal efficiency and specific work of the system according to the present application;

[0026] Figure 5 Shows the minimum pressure of the cycle according to this application Schematic diagram of the impact of efficiency and total cost rate;

[0027] Figure 6 A schematic diagram showing the effect of the maximum cycle temperature on the thermal efficiency and specific work of the system according to the present application;

[0028] Figure 7 The maximum temperature of the cycle according to this application is shown Schematic diagram of the impact of efficiency and total cost rate;

[0029] Figure 8 A schematic diagram showing the influence of the circulation pressure ratio on the performance evaluation index of the circulation system according to the present application;

[0030] Fig. 9 A schematic diagram showing the effect of the isentropic efficiency of the compressor on the thermal efficiency and specific work of the system according to the present application;

[0031] Fig.10 The effect of compressor isentropic efficiency on system performance according to the present application is shown. Schematic diagram of the impact of efficiency and total cost rate;

[0032] Fig.11 A schematic diagram showing the effect of the turbine equal entropy efficiency on the system thermal efficiency and specific work according to the present application;

[0033] Fig.12 The effect of the transmission equal entropy efficiency on the system is shown in the present application. Schematic diagram of the impact of efficiency and total cost rate;

[0034] In the figure, 1, heat source; 2, heat exchanger for the first heat source working fluid; 3, heat exchanger for the second heat source working fluid; 4, first regulating valve; 5, first turbine; 6, first high-temperature regenerator; 7, first low-temperature regenerator; 8, first precooler; 9, first precompressor; 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 DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work 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 may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0038] Embodiment 1

[0039] Provide a combined cycle system based on supercritical carbon dioxide, such as Figure 1 As shown, the system includes a heat source 1, and the outlet end of the heat source 1 is respectively 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, and 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, wherein the circulation loop associated with the first heat source working fluid heat exchanger 2 is configured as a supercritical CO 2 The reheat and recompression circulation loop, the circulation loop associated with the second heat source working medium heat exchanger 3 is configured as supercritical CO 2 The partially cooled circulation loop simultaneously expands, cools, compresses and heats the supercritical carbon dioxide fluid flowing into it through the above two systems, so as to make the circulation efficiency and power generation efficiency of the combined system higher.

[0040] It should be noted that the first heat source working medium heat exchanger 2 and the second heat source working medium heat exchanger 3 in this embodiment are configured as CO 2 -Heat source medium-CO 2 Heat exchanger.

[0041] Furthermore, a first regulating valve 4 is connected to the outlet end of the heat source 1, and the first regulating valve 4 is selected to be a three-way valve, wherein the first regulating valve 4 includes two outlet ends and one inlet end, and 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 adjust the proportion of the fluid in the 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 connected to the first turbine 5, the first high-temperature reheater 6, the first low-temperature reheater 7 and the first precooler 8 in sequence, and the outlet end of the first precooler 8 is also connected to the first precompressor 9 and the first recompressor 10 in sequence, the outlet end of the first recompressor 10 is connected to the inlet end of the first heat source working fluid heat exchanger 2, and the outlet end of the first precompressor 9 is divided into two fluids, that is, the outlet end of the first precompressor 9 is connected to the first recompressor 10 and the intermediate cooler 25 respectively, the outlet end of the intermediate cooler 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 reheater 7.

[0043] When the system starts to operate, 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 completing the work, the working fluid enters the first high-temperature regenerator 6 and the first low-temperature regenerator 7 in sequence to recover the heat, 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 a critical state of carbon dioxide fluid, it enters the first precompressor 9 and is divided into two streams at the outlet of the first precompressor 9. The first stream of fluid flows into the first main compressor 26 after passing through the intercooler 25, and after completing the supercharging process through 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] Further, the system further comprises a second regulating valve 11, which is selected as a three-way valve, and comprises two inlet ends and one outlet end, and 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, and the outlet end of the second regulating valve 11 is connected to the first high-temperature regenerator 6, so that the second fluid directly flows into the first recompressor 10, and after the supercharging process is completed by the first recompressor 10, it is mixed with the first 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 enters the working fluid heat exchanger of the first heat source 1 again to continue to absorb heat, completing a cycle.

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

[0046] Furthermore, a third regulating valve 18 is connected to the outlet end of the second low-temperature regenerator 16, and the third regulating valve 18 is configured as a three-way valve. The third regulating valve 18 includes an inlet end and two outlet ends, one of which is connected to the second precooler 19 and the second main compressor 20 in sequence, the outlet end of the second main compressor 20 is connected to the second low-temperature regenerator 16, and 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, wherein 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] Combined with the third regulating valve 18 and the fourth regulating valve 21, the working fluid is divided into two parts of fluid 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, flows into the second main compressor 20, and enters the second low-temperature regenerator 16 to absorb heat after being pressurized; 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, and is mixed in the fourth regulating valve 21. The mixed carbon dioxide fluid is heated again in the second high-temperature regenerator 15, and after being heated to a preset temperature, enters the second heat source working fluid heat exchanger 3 to continue absorbing heat for the next cycle.

[0049] In a 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 the fifth regulating valve 27 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 end 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 pipeline to realize the merging of the heat source working fluids that complete heat exchange in the two heat exchangers, and then the merged heat source working fluids enter the reheater 13 to use waste heat to reheat the medium-pressure and medium-temperature supercritical carbon dioxide coming out of the third turbine 14, and 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, 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 allocated 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 the heat source 1 and the thermodynamic parameter requirements. The heat of the two circuits is distributed to control the flow rate of supercritical carbon dioxide entering the two circuits to improve the working capacity of the supercritical carbon dioxide working fluid, while achieving flexible response to changes in external design requirements.

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

[0053] like Figure 2 and Figure 3 As shown in Figure 2, the influence of the minimum circulation temperature of the circulation system on the main performance parameters of the circulation system is controlled, among which the influence of the minimum circulation temperature on the thermal efficiency and specific work of the system is shown in Figure 2. Figure 2 and Figure 3 As shown, it can be seen that the circulation loop associated with the first heat source working medium heat exchanger 2 is configured as supercritical CO 2 In the reheat-recompression cycle, as the minimum cycle temperature increases, the cycle thermal efficiency, The efficiency and specific work both show a downward trend with a gradually decreasing rate of decline. The circulation loop associated with the second heat source working medium heat exchanger 3 is configured as a supercritical CO 2 In a partially cooled circulation loop, as the minimum temperature of the circulation increases, the circulation thermal efficiency, The efficiency shows an upward trend with a gradually slowing slope, while the specific work of the system will be significantly suppressed. The performance of the multi-component combined cycle system is affected by the above two basic cycle systems at the same time, and mainly depends on the distribution of heat in the two basic cycle systems. Under the heat distribution set in this implementation, the multi-component combined cycle system shows more characteristics of a reheat and recompression cycle loop.

[0054] like Figure 4 and Figure 5 As shown in the figure, in the reheat-recompression cycle system, as the minimum cycle pressure increases, the cycle thermal efficiency, The efficiency and specific work have been significantly improved. For some cooling cycle systems, as the minimum cycle pressure increases, the cycle thermal efficiency, The efficiency and total cost rate are both reduced, while the specific work of the system is improved. The performance of the multi-component combined cycle system is affected by the above two basic cycle systems at the same time, and mainly depends on the distribution of heat in the two basic cycle systems. Under the heat distribution set in this implementation, the performance of the multi-component combined cycle system is more inclined to the partial cooling cycle system, and its various performance evaluation indicators are still more average among the three cycle systems. Increasing the minimum pressure of the cycle system operation has a great impact on the thermal efficiency, The impact on efficiency is relatively weak, but it promotes the specific power and economy of the multi-component combined cycle system.

[0055] like Figure 6 and Figure 7 As shown in the figure, with the increase of the maximum cycle temperature, the specific work of the reheat recompression, partial cooling and multi-component combined cycle system, the cycle The efficiency and cycle thermal efficiency have been significantly improved. High turbine inlet temperature is conducive to improving the thermal performance and economic performance of the basic cycle system and the multi-component combined cycle system.

[0056] like Figure 8 As shown in Figure 2, with the increase of cycle pressure ratio, the cycle thermal efficiency and The efficiency first rises and then falls, and the specific power and total cost rate rise with the increase. The efficiency shows an obvious trend of increasing and then decreasing.

[0057] like Fig. 9 and Fig.10 As shown in Figure 2, with the increase of the isentropic efficiency of the compressor, the thermal efficiency and The efficiency has been significantly improved. At the same time, it also has a significant promoting effect on the specific work of the circulation system, but it can be seen that the rate of increase of the specific work of the circulation system continues to decrease as the isentropic efficiency of the compressor increases.

[0058] like Fig.11 and Fig.12 As shown, the specific work and thermal efficiency of the cycle system, The various thermodynamic performances of efficiency show an increasing trend under the influence of the continuous increase of turbine equal entropy efficiency, among which the rate of increase of specific power is slightly lower than that of system thermal efficiency, The rate at which efficiency increases. As the efficiency of the turbine and entropy increases, the total cost of the system also increases.

[0059] Embodiment 2

[0060] Corresponding to the above-mentioned embodiment, the present application provides a combined cycle method based on supercritical carbon dioxide, and the method is applied to the combined cycle system based on supercritical carbon dioxide as described above.

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

[0062] In a specific embodiment, the combined cycle system based on supercritical carbon dioxide includes a heat source 1, the outlet end of the heat source 1 is respectively 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 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, 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;

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

[0064] In a specific embodiment, the outlet end of the heat source 1 is connected to the first regulating valve 4, the first regulating valve 4 is a three-way valve, and 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 a specific embodiment, the first low-temperature regenerator 7 is further connected to a first precooler 8, and the first precooler 8 is used to cool the fluid in the first low-temperature regenerator 7 to a preset temperature.

[0066] In a 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 a specific embodiment, it also includes a second regulating valve 11, which 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, and the outlet end of the second regulating valve 11 is connected to the first high-temperature regenerator 6.

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

[0069] In a specific embodiment, the other outlet end of the third regulating valve 18 is connected to the second re-compressor 17 .

[0070] In a specific embodiment, it also includes a fourth regulating valve 21, which 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, and the outlet end of the fourth regulating valve 21 is connected to the second high-temperature regenerator 15.

[0071] In a specific embodiment, the first turbine 5 is connected to the first engine 22, the second turbine 12 is connected to the second engine 23, 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.

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

Claims

1. A combined cycle system based on supercritical carbon dioxide, characterized in that: The system comprises a heat source (1), wherein an outlet end of the heat source (1) is respectively 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 outlet end of the first heat source working medium heat exchanger (2) is connected in sequence 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 medium heat exchanger (2); The outlet end of the second heat source working fluid heat exchanger (3) is connected in sequence to the second turbine (12), the reheater (13), the third turbine (14), the second high-temperature reheater (15), the second low-temperature reheater (16) and the second recompressor (17); the outlet end of the second recompressor (17) is connected to the second high-temperature reheater (15); and the outlet end of the second high-temperature reheater (15) is connected to the inlet end of the second heat source working fluid heat exchanger (3).

2. The combined cycle system based on supercritical carbon dioxide according to claim 1, characterized in that: The outlet end of the heat source (1) is connected to a first regulating valve (4), the first regulating valve (4) being a three-way valve, and 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).

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

4. The combined cycle system based on supercritical carbon dioxide according to claim 1 or 2, characterized in that: The outlet end of the first pre-compressor (9) is respectively connected to the first re-compressor (10) and the intermediate cooler (25), the outlet end of the intermediate cooler (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).

5. The combined cycle system based on supercritical carbon dioxide according to claim 4, characterized in that: The second regulating valve (11) is a three-way valve, and 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), and the outlet end of the second regulating valve (11) is connected to the first high-temperature regenerator (6).

6. The combined cycle system based on supercritical carbon dioxide according to claim 1 or 2, characterized in that: The outlet end of the second low-temperature regenerator (16) is connected to a third regulating valve (18), and the third regulating valve (18) is a three-way valve. At least one outlet end of the third regulating valve (18) is connected to a second precooler (19) and a second main compressor (20) in sequence, and the outlet end of the second main compressor (20) is connected to the second low-temperature regenerator (16).

7. The combined cycle system based on supercritical carbon dioxide according to claim 6, characterized in that: The other outlet end of the third regulating valve (18) is connected to the second re-compressor (17).

8. The combined cycle system based on supercritical carbon dioxide according to claim 1 or 2, characterized in that: The fourth regulating valve (21) is a three-way valve, and 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).

9. The combined cycle system based on supercritical carbon dioxide according to claim 1 or 2, characterized in that: The first turbine (5) is connected to a first engine (22), the second turbine (12) is connected to a second engine (23), the third turbine (14) is connected to a third engine (24), and the first turbine (5), the second turbine (12) and the third turbine (14) are not coaxial.

10. A combined cycle method based on supercritical carbon dioxide, characterized in that: The method is applied to the combined cycle system based on supercritical carbon dioxide as described in any one of claims 1 to 9.

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