Supercritical Brayton cycle power generation system and control method thereof

Abstract

The invention discloses a supercritical Brayton cycle power generation system and a control method thereof.The supercritical Brayton cycle power generation system comprises a carbon-water heat exchanger, a coal-fired power generation system and a Brayton cycle power generation system, and the Brayton cycle power generation system is connected with the coal-fired power generation system through the carbon-water heat exchanger. Safe and stable operation of the system is guaranteed, and economical efficiency is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power generation and relates to a supercritical Brayton cycle power generation system and a control method thereof. BACKGROUND

[0002] With the rapid development of social economy, the demand for electricity is growing, and the power grid is facing great pressure for peak regulation and frequency modulation. The traditional thermal power unit has limited peak regulation and frequency modulation capacity, while the new energy power generation is intermittent and volatile, which is difficult to meet the requirements of peak regulation and frequency modulation of the power grid. Therefore, it is urgent to develop a new type of power generation technology that is efficient, flexible and environmentally friendly to meet the growing demand for electricity and the requirements of peak regulation and frequency modulation of the power grid.

[0003] The supercritical Brayton cycle power generation technology has the advantages of high efficiency, flexibility and environmental protection, and is a new type of power generation technology with great development prospects. The supercritical Brayton cycle power generation system uses carbon dioxide as the working medium and operates in a supercritical state, which can fully utilize low-grade heat sources and achieve efficient power generation. At the same time, the supercritical Brayton cycle power generation system can flexibly adjust the load and quickly respond to the demand for peak regulation and frequency modulation of the power grid, which is an important means to realize the safe and stable operation of the power grid.

[0004] However, the supercritical Brayton cycle power generation system still has some challenges in peak regulation and frequency modulation. First, the start-up time of the supercritical Brayton cycle power generation system is relatively long, which makes it difficult to quickly respond to the demand for peak regulation and frequency modulation of the power grid. Second, when the load of the supercritical Brayton cycle power generation system changes, the system parameters will fluctuate greatly, affecting the safe and stable operation of the system. Third, during the process of peak regulation and frequency modulation, the thermal efficiency of the supercritical Brayton cycle power generation system will decrease, affecting the economy of the system. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art and provide a supercritical Brayton cycle power generation system and a control method thereof, which meet the demand for quick response to peak regulation and frequency modulation of the power grid, ensure the safe and stable operation of the system, and have good economy.

[0006] To achieve the above-mentioned purpose, the present application discloses a supercritical Brayton cycle power generation system, which comprises a carbon-water heat exchanger, a coal-fired power generation system and a Brayton cycle power generation system, and the Brayton cycle power generation system is connected with the coal-fired power generation system through the carbon-water heat exchanger.

[0007] The further improvement of the supercritical Brayton cycle power generation system according to the present application is that:

[0008] Further, the coal-fired power generation system comprises a first boiler, a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder, a high-pressure regenerative heater, a medium-pressure regenerative heater and a low-pressure regenerative heater.

[0009] The main steam outlet of the first boiler is connected to the inlet of the high-pressure cylinder, the outlet of the high-pressure cylinder is connected to the inlet of the reheat side of the first boiler, the reheat side outlet of the first boiler is connected to the inlet of the intermediate-pressure cylinder, the outlet of the intermediate-pressure cylinder is connected to the inlet of the low-pressure cylinder, the outlet of the low-pressure cylinder is connected to the inlet of the condenser, the outlet of the condenser is connected to the tube side of the carbon-water heat exchanger and the tube side inlet of the low-pressure regenerative heater, the tube side outlet of the low-pressure regenerative heater is connected to the feed water inlet of the boiler through the tube side of the intermediate-pressure regenerative heater and the tube side of the high-pressure regenerative heater in sequence, the steam extraction port of the high-pressure cylinder is connected to the shell side of the high-pressure regenerative heater, the steam extraction port of the intermediate-pressure cylinder is connected to the shell side of the intermediate-pressure regenerative heater, and the steam extraction port of the low-pressure cylinder is connected to the shell side of the low-pressure regenerative heater.

[0010] Furthermore, the Brayton cycle power generation system includes a second boiler, a high-pressure turbine, a low-pressure turbine and a carbon dioxide compressor; the outlet of the second boiler is connected to the inlet of the high-pressure turbine, the outlet of the high-pressure turbine is connected to the inlet of the reheat side of the second boiler, the reheat side outlet of the second boiler is connected to the inlet of the low-pressure turbine, the outlet of the low-pressure turbine is connected to the inlet of the carbon dioxide compressor via the shell side of the carbon-water heat exchanger, and the outlet of the carbon dioxide compressor is connected to the inlet of the second boiler.

[0011] Furthermore, a first air preheater is provided in the tail flue of the first boiler.

[0012] Furthermore, a second air preheater is provided in the tail flue of the second boiler.

[0013] The present invention discloses a control method for a supercritical Brayton cycle power generation system, comprising:

[0014] When the grid load increases, the coal supply to the second boiler is increased;

[0015] When the grid load decreases, the coal supply to the second boiler is reduced.

[0016] The control method of the supercritical Brayton cycle power generation system of the present invention is further improved in that:

[0017] Furthermore, when the grid load increases, the coal supply to the second boiler is increased. At this time, the steam extraction volume of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder is reduced, and the output of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder is increased.

[0018] Furthermore, when the grid load decreases, the coal supply to the second boiler is reduced. At this time, the steam extraction volume of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder increases, and the output of the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder decreases.

[0019] Furthermore, a first air preheater is provided in the tail flue of the first boiler.

[0020] Furthermore, a second air preheater is provided in the tail flue of the second boiler.

[0021] The present invention has the following beneficial effects:

[0022] During specific operation of the supercritical Brayton cycle power generation system and control method thereof described in the present invention, the Brayton cycle power generation system and the coal-fired power generation system are connected via a carbon-water heat exchanger, i.e., the Brayton cycle power generation system and the coal-fired power generation system are coupled via the carbon-water heat exchanger. When the load changes, it is only necessary to adjust the coal feed rate of the second boiler to meet the needs of rapid response to the peak and frequency regulation of the power grid. In addition, by coupling the two high-efficiency cycles, the thermal efficiency and economy of the overall system can be greatly improved, ensuring the safe and stable operation of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which constitute part of the present invention, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 It is a structural diagram of the present invention.

[0025] Among them, 1 is the first boiler, 2 is the high-pressure cylinder, 3 is the medium-pressure cylinder, 4 is the low-pressure cylinder, 5 is the low-pressure regenerative heater, 6 is the medium-pressure regenerative heater, 7 is the high-pressure regenerative heater, 8 is the condenser, 9 is the second boiler, 10 is the high-pressure turbine, 11 is the low-pressure turbine, 12 is the carbon-water heat exchanger, 13 is the carbon dioxide compressor, 14 is the first air preheater, and 15 is the second air preheater. DETAILED DESCRIPTION

[0026] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0027] In the description of the present invention, it is to be understood that the terms “include” and “comprise” indicate the presence of the described features, wholes, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components and / or collections thereof.

[0028] It should also be understood that the terms used in the specification and the following claims are for the purpose of describing particular embodiments and are not intended to be limiting, as the specific scope of the application is disclosed in the appended claims. As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0029] It should also be further understood that the term "and / or" as used in the specification and in the claims, means and includes any and all combinations of one or more of the associated listed items and all possible combinations, for example, A and / or B, can mean: existence of A alone, existence of both A and B, and existence of B alone. In addition, the character " / " in the present application generally represents an "or" relationship between the objects before and after it.

[0030] It should be understood that, although the terms first, second, third, etc. can be employed in describing the pre-set ranges, etc., the pre-set ranges should not be limited to these terms. These terms are only used to distinguish one pre-set range from another. For example, a first pre-set range can be termed a second pre-set range, and, similarly, a second pre-set range can be termed a first pre-set range, without departing from the scope of the embodiments of the present application.

[0031] Depending on the context, the word "if" as used herein can be interpreted to mean "when" or "while" or "in response to determining" or "in response to detecting." Similarly, the phrase "if it is determined" or "if [a stated condition or event] is detected" can be interpreted to mean "upon determining" or "in response to determining" or "upon detecting [the stated condition or event]" or "in response to detecting [the stated condition or event]."

[0032] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described herein and shown in the accompanying drawings can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is only intended to represent the selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative work based on the embodiments of the present application fall within the scope of protection of the present application.

[0033] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0034] Example 1

[0035] refer to Figure 1 The supercritical Brayton cycle power generation system of the present invention includes a carbon-water heat exchanger 12, a coal-fired power generation system, and a Brayton cycle power generation system, wherein the coal-fired power generation system includes a first boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a high-pressure regenerative heater 7, an intermediate-pressure regenerative heater 6, and a low-pressure regenerative heater 5; the Brayton cycle power generation system includes a second boiler 9, a high-pressure turbine 10, a low-pressure turbine 11, and a carbon dioxide compressor 13;

[0036] The main steam outlet of the first boiler 1 is connected to the inlet of the high-pressure cylinder 2, the outlet of the high-pressure cylinder 2 is connected to the reheat side inlet of the first boiler 1, the reheat side outlet of the first boiler 1 is connected to the inlet of the intermediate-pressure cylinder 3, the outlet of the intermediate-pressure cylinder 3 is connected to the inlet of the low-pressure cylinder 4, the outlet of the low-pressure cylinder 4 is connected to the inlet of the condenser 8, the outlet of the condenser 8 is connected to the tube side of the carbon-water heat exchanger 12 and the tube side inlet of the low-pressure regenerative heater 5, the tube side outlet of the low-pressure regenerative heater 5 is connected to the feed water inlet of the boiler via the tube side of the intermediate-pressure regenerative heater 6 and the tube side of the high-pressure regenerative heater 7 in sequence, the steam extraction port of the high-pressure cylinder 2 is connected to the shell side of the high-pressure regenerative heater 7, the steam extraction port of the intermediate-pressure cylinder 3 is connected to the shell side of the intermediate-pressure regenerative heater 6, and the steam extraction port of the low-pressure cylinder 4 is connected to the shell side of the low-pressure regenerative heater 5.

[0037] The outlet of the second boiler 9 is connected to the inlet of the high-pressure turbine 10, the outlet of the high-pressure turbine 10 is connected to the inlet of the reheat side of the second boiler 9, the reheat side outlet of the second boiler 9 is connected to the inlet of the low-pressure turbine 11, the outlet of the low-pressure turbine 11 is connected to the inlet of the carbon dioxide compressor 13 via the shell side of the carbon-water heat exchanger 12, and the outlet of the carbon dioxide compressor 13 is connected to the inlet of the second boiler 9.

[0038] In addition, in this embodiment, a first air preheater 14 is provided in the tail flue of the first boiler 1 , and a second air preheater 15 is provided in the tail flue of the second boiler 9 .

[0039] Example 2

[0040] refer to Figure 1The control method of the supercritical Brayton cycle power generation system of the present invention includes a carbon-water heat exchanger 12, a coal-fired power generation system, and a Brayton cycle power generation system, wherein the coal-fired power generation system includes a first boiler 1, a high-pressure cylinder 2, an intermediate-pressure cylinder 3, a low-pressure cylinder 4, a high-pressure regenerative heater 7, an intermediate-pressure regenerative heater 6, and a low-pressure regenerative heater 5; and the Brayton cycle power generation system includes a second boiler 9, a high-pressure turbine 10, a low-pressure turbine 11, and a carbon dioxide compressor 13.

[0041] Specifically, the control method of the supercritical Brayton cycle power generation system includes the following steps:

[0042] When the grid load increases, the coal feed to the second boiler 9 is increased. At this time, the steam extraction amount of the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 is reduced, and the output of the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 is increased; when the grid load decreases, the coal feed to the second boiler 9 is reduced. At this time, the steam extraction amount of the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 is increased, and the output of the high-pressure cylinder 2, the medium-pressure cylinder 3 and the low-pressure cylinder 4 is reduced.

[0043] In the present invention, the steam at the inlet of the high-pressure cylinder 2 is in a supercritical state, and its parameters are 600°C / 28.5MPa.

[0044] In the present invention, the temperature of the carbon dioxide at the inlet of the high-pressure turbine 10 ranges from 200° C. to 600° C., and the pressure of the carbon dioxide at the inlet of the high-pressure turbine 10 ranges from 10 MPa to 28.5 MPa.

[0045] It should be noted that the present invention has the following characteristics:

[0046] High flexibility and strong adaptability to grid load fluctuations. This invention utilizes two boilers to provide heat sources for the steam Rankine cycle and the carbon dioxide Brayton cycle, respectively. When the grid load increases, the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 increases simply by increasing the coal feed to the second boiler 9. When the grid load decreases, the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 decreases simply by reducing the coal feed to the second boiler 9. Independently adjusting the coal feed to the second boiler 9 allows for flexible adaptation to grid load fluctuations, enhancing system flexibility.

[0047] High thermal efficiency and low energy consumption. The coupling of two high-efficiency cycles can significantly improve the thermal efficiency of the entire system, reducing coal consumption and carbon dioxide emissions.

[0048] The invention has a compact structure and high equipment utilization rate. The invention cleverly couples the steam Rankine cycle and the carbon dioxide Brayton cycle together to achieve equipment sharing and cascade utilization.

[0049] Example 3

[0050] A computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the steps of the control method of the supercritical Brayton cycle power generation system are implemented, for example, including: when the grid load increases, the coal feed of the second boiler 9 is increased, at which time the steam extraction of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is reduced, and the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is increased; when the grid load decreases, the coal feed of the second boiler 9 is reduced, at which time the steam extraction of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is increased, and the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is reduced. The memory may include a memory, such as a high-speed random access memory, and may also include a non-volatile memory, such as at least one disk storage device. The processor, the network interface, and the memory are interconnected via an internal bus. The internal bus may be an industrial standard architecture bus, a peripheral component interconnect standard bus, an extended industrial standard architecture bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. The memory is used to store programs. Specifically, the programs may include program codes, and the program codes include computer operation instructions. The memory may include internal memory and non-volatile memory, and provides instructions and data to the processor.

[0051] Example 4

[0052] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the steps of the control method of the supercritical Brayton cycle power generation system, for example, including: when the grid load increases, the coal feed of the second boiler 9 is increased, at which time the steam extraction of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is reduced, and the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is increased; when the grid load decreases, the coal feed of the second boiler 9 is reduced, at which time the steam extraction of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is increased, and the output of the high-pressure cylinder 2, the intermediate-pressure cylinder 3, and the low-pressure cylinder 4 is reduced. Specifically, the computer-readable storage medium includes, but is not limited to, volatile memory and / or non-volatile memory. The volatile memory may include random access memory (RAM) and / or cache memory, etc. The non-volatile memory may include read-only memory (ROM), hard disk, flash memory, optical disk, magnetic disk, etc.

[0053] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0054] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0057] Those skilled in the art will readily identify other embodiments of the present invention after considering the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the present invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

[0058] It should be understood that the present invention is not limited to the exact construction described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

[0059] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A supercritical Brayton cycle power generation system, characterized in that: It comprises a carbon-water heat exchanger (12), a coal-fired power generation system and a Brayton cycle power generation system, wherein the Brayton cycle power generation system and the coal-fired power generation system are connected via the carbon-water heat exchanger (12).

2. The supercritical Brayton cycle power generation system according to claim 1, characterized in that: The coal-fired power generation system comprises a first boiler (1), a high-pressure cylinder (2), a medium-pressure cylinder (3), a low-pressure cylinder (4), a high-pressure regenerative heater (7), a medium-pressure regenerative heater (6) and a low-pressure regenerative heater (5); The main steam outlet of the first boiler (1) is connected to the inlet of the high-pressure cylinder (2), the outlet of the high-pressure cylinder (2) is connected to the reheat side inlet of the first boiler (1), the reheat side outlet of the first boiler (1) is connected to the inlet of the medium-pressure cylinder (3), the outlet of the medium-pressure cylinder (3) is connected to the inlet of the low-pressure cylinder (4), the outlet of the low-pressure cylinder (4) is connected to the inlet of the condenser (8), the outlet of the condenser (8) is connected to the tube side of the carbon-water heat exchanger (12) and the low-pressure reheating heater (13). The tube side inlet of the heat exchanger (5) is connected, the tube side outlet of the low-pressure heat exchanger (5) is connected to the feed water inlet of the boiler through the tube side of the medium-pressure heat exchanger (6) and the tube side of the high-pressure heat exchanger (7) in sequence, the steam extraction port of the high-pressure cylinder (2) is connected to the shell side of the high-pressure heat exchanger (7), the steam extraction port of the medium-pressure cylinder (3) is connected to the shell side of the medium-pressure heat exchanger (6), and the steam extraction port of the low-pressure cylinder (4) is connected to the shell side of the low-pressure heat exchanger (5).

3. The supercritical Brayton cycle power generation system according to claim 2, characterized in that: The Brayton cycle power generation system comprises a second boiler (9), a high-pressure turbine (10), a low-pressure turbine (11) and a carbon dioxide compressor (13); the outlet of the second boiler (9) is connected to the inlet of the high-pressure turbine (10), the outlet of the high-pressure turbine (10) is connected to the inlet of the reheat side of the second boiler (9), the outlet of the reheat side of the second boiler (9) is connected to the inlet of the low-pressure turbine (11), the outlet of the low-pressure turbine (11) is connected to the inlet of the carbon dioxide compressor (13) via the shell side of the carbon-water heat exchanger (12), and the outlet of the carbon dioxide compressor (13) is connected to the inlet of the second boiler (9).

4. The supercritical Brayton cycle power generation system according to claim 3, characterized in that: A first air preheater (14) is provided in the tail flue of the first boiler (1).

5. The supercritical Brayton cycle power generation system according to claim 3, characterized in that: A second air preheater (15) is provided in the tail flue of the second boiler (9).

6. A control method for the supercritical Brayton cycle power generation system according to claim 3, characterized in that: include: When the load on the power grid increases, the coal supply to the second boiler (9) is increased; When the load on the power grid decreases, the coal supply to the second boiler (9) is reduced.

7. The control method of the supercritical Brayton cycle power generation system according to claim 6, characterized in that: When the load on the power grid increases, the coal supply to the second boiler (9) is increased. At this time, the steam extraction amount of the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) is reduced, and the output of the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) is increased.

8. The control method of the supercritical Brayton cycle power generation system according to claim 6, characterized in that: When the load on the power grid decreases, the coal supply to the second boiler (9) is reduced. At this time, the steam extraction volume of the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) increases, and the output of the high-pressure cylinder (2), the medium-pressure cylinder (3) and the low-pressure cylinder (4) decreases.

9. The control method of the supercritical Brayton cycle power generation system according to claim 6, characterized in that: A first air preheater (14) is provided in the tail flue of the first boiler (1).

10. The control method of the supercritical Brayton cycle power generation system according to claim 6, characterized in that: A second air preheater (15) is provided in the tail flue of the second boiler (9).

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