A supercritical carbon dioxide Brayton combined cycle solar power generation system

Abstract

The present invention discloses a supercritical carbon dioxide Brayton cycle combined cycle solar power generation system, relating to the field of power generation technology. In the combined cycle solar power generation system, the outlet of a tower solar thermal collector system is connected to a first inlet of a heat storage system; the first outlet of the heat storage system is connected to an inlet of a supercritical carbon dioxide Brayton cycle power generation system; the outlet of the supercritical carbon dioxide Brayton cycle power generation system is connected to an inlet of a Rankine cycle power generation system; the outlet of the Rankine cycle power generation system is connected to a second inlet of the heat storage system; and the second outlet of the heat storage system is connected to an inlet of the tower solar thermal collector system. The heat storage system is used to store solar energy collected by the tower solar thermal collector system to drive the operation of the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system. The present invention can increase the temperature difference between the hot storage tank and the cold storage tank, thereby effectively improving the maximum heat storage capacity of the heat storage system, the system power generation, and the solar energy utilization rate.

Description

Technical Field

[0001] The present invention relates to the technical field of power generation, and in particular to a supercritical carbon dioxide Brayton combined cycle solar power generation system. Background Art

[0002] Currently, countries are beginning to adjust their energy structures, reducing dependence on fossil fuels and increasing the proportion and utilization of renewable energy. Solar energy is the most abundant and widely distributed clean energy on Earth. Among various solar power generation technologies, tower solar power generation technology offers high efficiency, large single-unit capacity, and high operating temperature.

[0003] When temperatures exceed 700°C, steam corrosion of metals becomes a serious issue, rendering the traditional steam Rankine cycle unable to demonstrate the advantages of tower solar power generation technology. Carbon dioxide, as an inert gas, possesses excellent thermal stability. When the maximum cycle temperature exceeds 600°C, the supercritical CO2 Brayton cycle achieves higher thermal efficiency than the steam Rankine cycle, and the advantages of the supercritical CO2 Brayton cycle become more pronounced as the maximum temperature increases.

[0004] To ensure smooth system operation, tower solar power generation systems are generally equipped with heat storage devices. Currently, the maximum operating temperature of new heat storage fluids exceeds 800°C and can be used to heat supercritical carbon dioxide. However, supercritical carbon dioxide Brayton cycle solar power generation systems with heat storage also face some problems. The heat absorption inlet temperature of the supercritical carbon dioxide Brayton cycle is too high (superheated fluid exceeds 450°C, and reheated fluid exceeds 500°C), resulting in excessively high temperatures of the heat storage fluid in the cold storage tank and a small temperature difference between the cold and hot storage tanks. Under conditions of equal amounts of heat storage fluid, the maximum heat storage capacity of the supercritical carbon dioxide Brayton cycle is far less than that of the steam Rankine cycle, resulting in shortened power generation time, reduced power generation, and low solar energy utilization. In summary, for supercritical carbon dioxide Brayton cycle solar power generation systems, increasing the temperature difference between the hot and cold storage tanks and increasing the maximum heat storage capacity of the heat storage system are imperative. Summary of the Invention

[0005] Based on this, an embodiment of the present invention provides a supercritical carbon dioxide Brayton combined cycle solar power generation system to increase the temperature difference between the hot storage tank and the cold storage tank, thereby effectively improving the maximum heat storage capacity, system power generation and solar energy utilization rate of the heat storage system.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A supercritical carbon dioxide Brayton combined cycle solar power generation system, comprising: a tower solar thermal collection system, a heat storage system, a supercritical carbon dioxide Brayton cycle power generation system and a Rankine cycle power generation system;

[0008] The outlet of the tower solar thermal collection system is connected to the first inlet of the heat storage system; the first outlet of the heat storage system is connected to the inlet of the supercritical carbon dioxide Brayton cycle power generation system; the outlet of the supercritical carbon dioxide Brayton cycle power generation system is connected to the inlet of the Rankine cycle power generation system; the outlet of the Rankine cycle power generation system is connected to the second inlet of the heat storage system; the second outlet of the heat storage system is connected to the inlet of the tower solar thermal collection system; the heat storage system is used to store solar energy collected by the tower solar thermal collection system to drive the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system to operate.

[0009] Optionally, the heat storage system specifically includes: a hot storage tank and a cold storage tank;

[0010] The inlet of the heat storage tank is connected to the outlet of the tower solar thermal collection system; the outlet of the heat storage tank is connected to the inlet of the supercritical carbon dioxide Brayton cycle power generation system;

[0011] The inlet of the cold storage tank is communicated with the outlet of the Rankine cycle power generation system; the outlet of the cold storage tank is communicated with the inlet of the tower solar thermal collection system.

[0012] Optionally, the supercritical carbon dioxide Brayton cycle power generation system specifically includes:

[0013] a first superheater, a second superheater, a first reheater, a second reheater, a first turbine, a second turbine, and a heat recovery recompression system;

[0014] The outlet of the heat storage tank is connected to the heat storage working fluid side inlet of the first reheater; the heat storage working fluid side outlet of the first reheater is connected to the heat storage working fluid side inlet of the second reheater and the heat storage working fluid side inlet of the first superheater respectively; the heat storage working fluid side outlet of the second reheater and the heat storage working fluid side outlet of the first superheater are both connected to the heat storage working fluid side inlet of the second superheater; the heat storage working fluid side outlet of the second superheater is connected to the inlet of the Rankine cycle power generation system.

[0015] Optionally, the heat recovery and recompression system specifically includes: a first heat regenerator, a second heat regenerator, a cooler, a first compressor, and a second compressor;

[0016] The high-pressure side outlet of the first reheater is communicated with the carbon dioxide side inlet of the second superheater; the carbon dioxide side outlet of the second superheater is communicated with the carbon dioxide side inlet of the first superheater; the carbon dioxide side outlet of the first superheater is communicated with the inlet of the first turbine; the outlet of the first turbine is communicated with the carbon dioxide side inlet of the second reheater; the carbon dioxide side outlet of the second reheater is communicated with the carbon dioxide side inlet of the first reheater; the carbon dioxide side outlet of the first reheater is communicated with the inlet of the second turbine; and the outlet of the second turbine is communicated with the low-pressure side inlet of the first reheater;

[0017] The low-pressure side outlet of the first regenerator is connected to the low-pressure side inlet of the second regenerator; the low-pressure side outlet of the second regenerator is connected to the carbon dioxide side inlet of the cooler and the inlet of the second compressor respectively; the carbon dioxide side outlet of the cooler is connected to the inlet of the first compressor; the outlet of the first compressor is connected to the high-pressure side inlet of the second regenerator; the high-pressure side outlet of the second regenerator is connected to the high-pressure side inlet of the first regenerator; the outlet of the second compressor is connected to the high-pressure side inlet of the first regenerator.

[0018] Optionally, the Rankine cycle power generation system specifically includes: a heater, a third turbine, a condenser and a pump;

[0019] The heat storage medium side inlet of the heater is connected to the outlet of the supercritical carbon dioxide Brayton cycle power generation system; the heat storage medium side outlet of the heater is connected to the inlet of the cold storage tank;

[0020] The generator working medium side outlet of the heater is sequentially connected in series with the third turbine, the condenser and the pump; the outlet of the pump is communicated with the generator working medium side inlet of the heater.

[0021] Optionally, the heat storage system further includes: a first valve and a second valve;

[0022] The first valve is provided on the connecting pipe between the outlet of the heat storage tank and the inlet of the supercritical carbon dioxide Brayton cycle power generation system;

[0023] The second valve is provided on the connecting pipeline between the outlet of the cold storage tank and the inlet of the tower-type solar thermal collection system.

[0024] Optionally, the heat storage medium in the heat storage system is chloride salt, carbonate, liquid metal, solid particles, air or supercritical carbon dioxide.

[0025] Optionally, the power generation medium in the Rankine cycle power generation system is organic matter or water.

[0026] Optionally, the tower-type solar thermal collection system specifically comprises: a heliostat and a receiver;

[0027] The heliostat is used to reflect solar energy into the receiver; the outlet of the receiver is connected to the first inlet of the heat storage system; and the inlet of the receiver is connected to the second outlet of the heat storage system.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] An embodiment of the present invention proposes a supercritical carbon dioxide Brayton cycle combined solar power generation system that incorporates a Rankine cycle power generation system. The inlet of the Rankine cycle power generation system is connected to the outlet of the supercritical carbon dioxide Brayton cycle power generation system, which in turn is connected to the inlet of a heat storage system. The heat storage fluid passing through the supercritical carbon dioxide Brayton cycle power generation system continues to serve as a heat source to drive the Rankine cycle power generation system. The presence of the Rankine cycle power generation system effectively reduces the temperature of the heat storage fluid in the cold storage tank of the heat storage system and increases the temperature difference between the cold storage tank and the hot storage tank of the heat storage system. This increases the maximum heat storage capacity of the heat storage system and utilizes more solar energy. This invention can effectively improve the maximum heat storage capacity of the heat storage system, the system's power generation, and the solar energy utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A structural diagram of a supercritical carbon dioxide Brayton combined cycle solar power generation system provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the specific structure of a supercritical carbon dioxide Brayton combined cycle solar power generation system provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the specific structure of a conventional supercritical carbon dioxide Brayton cycle power generation system with heat storage provided in an embodiment of the present invention.

[0034] Explanation of symbols: 1-heliostat; 2-receiver; 3-hot storage tank; 4-cold storage tank; 5-second valve; 6-second superheater; 7-first superheater; 8-second reheater; 9-first reheater; 10-first turbine; 11-second turbine; 12-first reheater; 13-second reheater; 14-cooler; 15-first compressor; 16-second compressor; 17-heater; 18-third turbine; 19-condenser; 20-pump; 21-first valve; 22-superheater; 23-reheater. DETAILED DESCRIPTION

[0035] 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 the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Figure 1 This is a schematic diagram of the structure of a supercritical carbon dioxide Brayton combined cycle solar power generation system provided by an embodiment of the present invention. Figure 1 The supercritical carbon dioxide Brayton combined cycle solar power generation system of this embodiment includes: a tower solar thermal collection system, a heat storage system, a supercritical carbon dioxide Brayton cycle power generation system and a Rankine cycle power generation system.

[0038] The outlet of the tower solar thermal collection system is connected to the first inlet of the heat storage system; the first outlet of the heat storage system is connected to the inlet of the supercritical carbon dioxide Brayton cycle power generation system; the outlet of the supercritical carbon dioxide Brayton cycle power generation system is connected to the inlet of the Rankine cycle power generation system; the outlet of the Rankine cycle power generation system is connected to the second inlet of the heat storage system; the second outlet of the heat storage system is connected to the inlet of the tower solar thermal collection system; the heat storage system is used to store solar energy collected by the tower solar thermal collection system to drive the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system to operate.

[0039] In this embodiment of the supercritical CO2 Brayton cycle combined solar power generation system, a tower-type solar thermal collector system collects solar energy and stores the heat in the thermal storage system via a thermal storage medium. The thermal storage system serves as a heat source for both the supercritical CO2 Brayton cycle power generation system and the Rankine cycle power generation system, providing heat for both. This embodiment incorporates a Rankine cycle power generation system. The thermal storage medium, which has passed through the supercritical CO2 Brayton cycle power generation system, continues to serve as a heat source to drive the Rankine cycle power generation system. The presence of the Rankine cycle power generation system effectively reduces the temperature of the thermal storage medium in the cold storage tank of the thermal storage system, increasing the temperature difference between the cold storage tank and the hot storage tank of the thermal storage system. This increases the maximum heat storage capacity of the thermal storage system, allowing for greater utilization of solar energy, effectively improving the maximum heat storage capacity of the thermal storage system, the system's power generation output, and the solar energy utilization rate.

[0040] As an optional implementation, see Figure 2 The heat storage system specifically includes: a hot storage tank 3 and a cold storage tank 4; the inlet of the hot storage tank 3 serves as the first inlet of the heat storage system, and the inlet of the hot storage tank 3 is connected to the outlet of the tower solar thermal collection system; the outlet of the hot storage tank 3 serves as the first outlet of the heat storage system, and the outlet of the hot storage tank 3 is connected to the inlet of the supercritical carbon dioxide Brayton cycle power generation system; the inlet of the cold storage tank 4 serves as the second inlet of the heat storage system, and the inlet of the cold storage tank 4 is connected to the outlet of the Rankine cycle power generation system; the outlet of the cold storage tank 4 serves as the second outlet of the heat storage system, and the outlet of the cold storage tank 4 is connected to the inlet of the tower solar thermal collection system.

[0041] As an optional implementation, please refer to Figure 2 The supercritical carbon dioxide Brayton cycle power generation system specifically includes: a first superheater 7, a second superheater 6, a first reheater 9, a second reheater 8, a first turbine 10, a second turbine 11 and a heat recovery recompression system.

[0042] The outlet of the heat storage tank 3 is connected to the heat storage working fluid side inlet of the first reheater 9; the heat storage working fluid side outlet of the first reheater 9 is connected to the heat storage working fluid side inlet of the second reheater 8 and the heat storage working fluid side inlet of the first superheater 7 respectively; the heat storage working fluid side outlet of the second reheater 8 and the heat storage working fluid side outlet of the first superheater 7 are both connected to the heat storage working fluid side inlet of the second superheater 6; the heat storage working fluid side outlet of the second superheater 6 is connected to the inlet of the Rankine cycle power generation system.

[0043] Compared to conventional supercritical CO2 Brayton cycle solar power generation systems with thermal storage, the supercritical CO2 Brayton cycle combined cycle solar power generation system in this embodiment includes a second superheater 6, a first superheater 7, a second reheater 8, and a first reheater 9 to achieve better temperature matching. The CO2 side temperature of the first superheater 7 and the second reheater 8 are the same, effectively reducing the outlet temperature of the thermal storage medium.

[0044] As an optional implementation, please refer to Figure 2 The heat recovery and recompression system specifically includes: a first heat regenerator 12, a second heat regenerator 13, a cooler 14, a first compressor 15 and a second compressor 16.

[0045] The high-pressure side outlet of the first reheater 12 is connected to the carbon dioxide side inlet of the second superheater 6; the carbon dioxide side outlet of the second superheater 6 is connected to the carbon dioxide side inlet of the first superheater 7; the carbon dioxide side outlet of the first superheater 7 is connected to the inlet of the first turbine 10; the outlet of the first turbine 10 is connected to the carbon dioxide side inlet of the second reheater 8; the carbon dioxide side outlet of the second reheater 8 is connected to the carbon dioxide side inlet of the first reheater 9; the carbon dioxide side outlet of the first reheater 9 is connected to the inlet of the second turbine 11; the outlet of the second turbine 11 is connected to the low-pressure side inlet of the first reheater 12.

[0046] The low-pressure side outlet of the first reheater 12 is connected to the low-pressure side inlet of the second reheater 13; the low-pressure side outlet of the second reheater 13 is connected to the carbon dioxide side inlet of the cooler 14 and the inlet of the second compressor 16 respectively; the carbon dioxide side outlet of the cooler 14 is connected to the inlet of the first compressor 15; the outlet of the first compressor 15 is connected to the high-pressure side inlet of the second reheater 13; the high-pressure side outlet of the second reheater 13 is connected to the high-pressure side inlet of the first reheater 12; the outlet of the second compressor 16 is connected to the high-pressure side inlet of the first reheater 12.

[0047] As an optional implementation, please refer to Figure 2 The Rankine cycle power generation system specifically includes: a heater 17, a third turbine 18, a condenser 19 and a pump 20.

[0048] The heat storage working fluid side inlet of the heater 17 is connected to the outlet of the supercritical carbon dioxide Brayton cycle power generation system; the heat storage working fluid side outlet of the heater 17 is connected to the inlet of the cold storage tank 4. The power generation working fluid side outlet of the heater 17 is connected in series with the third turbine 18, the condenser 19, and the pump 20; the outlet of the pump 20 is connected to the power generation working fluid side inlet of the heater 17.

[0049] As an optional implementation, please refer to Figure 2 The heat storage system further includes a first valve 21 and a second valve 5. The first valve 21 is provided on the connecting pipe between the outlet of the hot storage tank 3 and the inlet of the supercritical carbon dioxide Brayton cycle power generation system. The second valve 5 is provided on the connecting pipe between the outlet of the cold storage tank 4 and the inlet of the tower solar thermal collection system.

[0050] As an optional implementation, please refer to Figure 2 The tower-type solar thermal collection system specifically includes: a heliostat 1 and a receiver 2.

[0051] The heliostat 1 is used to reflect solar energy into the receiver 2 ; the outlet of the receiver 2 is connected to the first inlet of the heat storage system; and the inlet of the receiver 2 is connected to the second outlet of the heat storage system.

[0052] As an optional embodiment, the first superheater 7 is a high-temperature superheater; the second superheater 6 is a low-temperature superheater; the first reheater 9 is a high-temperature reheater, and the second reheater 8 is a low-temperature reheater; the first turbine 10 is a high-pressure turbine; the second turbine 11 is a low-pressure turbine; the first regenerator 12 is a high-temperature regenerator; the second regenerator 13 is a low-temperature regenerator; the first compressor 15 serves as the main compressor; and the second compressor 16 serves as the auxiliary compressor. The low-temperature superheater, high-temperature superheater, low-temperature reheater, and high-temperature reheater are all shell-and-tube heat exchangers; the high-pressure turbine and low-pressure turbine are both axial-flow turbines; and the high-temperature regenerator and low-temperature regenerator are both printed circuit board heat exchangers. The inlet temperature range of the low-temperature superheater and low-temperature reheater is 450~550℃; the inlet temperature range of the high-temperature superheater and high-temperature reheater is 550~600℃; the inlet pressure range of the high-pressure turbine is 20~30MPa; the inlet pressure range of the low-pressure turbine is 15~20MPa; the operating temperature range of the high-temperature regenerator is 200~550℃; the operating temperature range of the low-temperature regenerator is 80~200℃.

[0053] As an optional embodiment, when the reserve of the heat storage medium in the heat storage tank 3 is greater than a certain value, the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system operate simultaneously, thereby increasing the power generation of the entire system.

[0054] As an optional implementation, the heat storage medium in the heat storage system is chloride salt, carbonate, liquid metal, solid particles, air or supercritical carbon dioxide.

[0055] As an optional implementation, the power generation medium in the Rankine cycle power generation system is organic matter or water.

[0056] As an optional embodiment, the cycle arrangement of the supercritical carbon dioxide Brayton cycle power generation system can be a simple cycle, a regenerative cycle, a recompression cycle or an intercooling cycle.

[0057] The following describes a specific connection relationship and specific working scenario of the supercritical carbon dioxide Brayton combined cycle solar power generation system in practical application in the above embodiment.

[0058] See also Figure 2 The tower solar thermal collection system includes a heliostat 1 and a receiver 2. The heliostat 1 reflects solar energy into the receiver 2, the receiver inlet is connected to the outlet of the second valve 5, and the outlet of the receiver 2 is connected to the inlet of the heat storage tank 3.

[0059] The heat storage system includes a hot storage tank 3, a cold storage tank 4, a first valve 21, and a second valve 5. The outlet of the hot storage tank 3 is connected in series with the first valve 21 and the heat storage working medium inlet of the first reheater 9. The heat storage working medium outlet of the first reheater 9 is divided into two paths, connecting to the heat storage working medium inlet of the second reheater 8 and the heat storage working medium inlet of the first superheater 7 respectively. The heat storage working medium outlet of the second reheater 8 and the heat storage working medium outlet of the first superheater 7 then merge and are connected in series with the heat storage working medium side of the second superheater 6, the heat storage working medium side of the heater 17, the cold storage tank 4, and the second valve 5.

[0060] The supercritical CO2 Brayton cycle power generation system includes a second superheater 6, a first superheater 7, a second reheater 8, a first reheater 9, a first turbine 10, a second turbine 11, a first reheater 12, a second reheater 13, a cooler 14, a first compressor 15, and a second compressor 16. The high-pressure outlet of the first reheater 12 is connected in series with the CO2 side of the second superheater 6, the CO2 side of the first superheater 7, the first turbine 10, the CO2 side of the second reheater 8, the CO2 side of the first reheater 9, the second turbine 11, the low-pressure side of the first reheater 12, and the low-pressure side of the second reheater 13. The low-pressure outlet of the second reheater 13 splits into two paths: one path connects in series with the CO2 side of the cooler 14, the first compressor 15, and the high-pressure side of the second reheater 13, while the other path connects to the second compressor 16. The outlet of the second compressor 16 merges with the high-pressure outlet of the second reheater 13 and then connects to the high-pressure inlet of the first reheater 12.

[0061] The Rankine cycle power generation system includes a heater 17, a third turbine 18, a condenser 19, and a pump 20. In the Rankine cycle power generation system, the power generation working medium side of the heater 17, the third turbine 18, the working medium side of the condenser 19, and the pump 20 are sequentially connected in series to form a loop.

[0062] The specific working scenarios are as follows:

[0063] In a tower solar thermal collection system, when there is solar radiation, the heliostat 1 reflects the solar energy to the receiver 2, and the heat storage medium enters the receiver 2 to absorb the solar heat.

[0064] In the heat storage system, the heat release process is as follows: when the amount of heat storage fluid in hot tank 3 exceeds a certain value, the heat storage fluid in hot tank 3 acts as a heat source to drive the supercritical carbon dioxide Brayton cycle power generation system to generate electricity. After releasing heat, the heat storage fluid continues to serve as a heat source to drive the Rankine cycle power generation system and is stored in cold tank 4. By adjusting the opening of first valve 21, the flow rate of the heat storage fluid at the outlet of hot tank 3 is changed, thereby controlling the temperature of the heat storage fluid at the inlet of cold tank 4.

[0065] In the thermal storage system, the heat storage process is as follows: when the cold tank 4 contains thermal fluid, it enters the receiver 2 to absorb heat. The first thermal fluid exiting the receiver 2 is stored in the hot tank 3. By adjusting the opening of the first valve 5, the flow rate of the thermal fluid at the outlet of the cold tank 4 is changed, thereby controlling the temperature of the thermal fluid at the inlet of the hot tank 3. Furthermore, when the hot tank 3 is full, the angle of the heliostat 1 is adjusted to discard excess solar energy.

[0066] In a supercritical CO2 Brayton cycle power generation system, CO2 exiting the high-pressure outlet of the first reheater 12 sequentially enters the second superheater 6 and the first superheater 7 to absorb heat before entering the first turbine 10 to expand and produce work. The CO2, having produced work, then enters the second reheater 8 and the first reheater 9 to absorb heat before entering the second turbine 11 to expand and produce work. The CO2, having produced work, flows sequentially through the first reheater 12 and the second reheater 13 to release heat. The CO2 exiting the low-pressure outlet of the second reheater 13 is split into two streams. One stream enters the cooler 14 to release heat. The cooled CO2 enters the first compressor 15 for compression before entering the second reheater 13 to absorb heat. The other stream enters the second compressor 16 for compression. These two streams merge at the high-pressure inlet of the first reheater 12 and then enter the first reheater 12 together to absorb heat.

[0067] In the Rankine cycle power generation system, the working fluid at the outlet of the pump 20 enters the heater 17 to absorb heat, then enters the turbine 18 to expand and do work. After doing work, the working fluid enters the condenser 19 to release heat, and then enters the pump 20 to be pressurized, thus completing a cycle.

[0068] The supercritical carbon dioxide Brayton combined cycle solar power generation system of this embodiment has the following advantages:

[0069] 1) This invention proposes a supercritical CO2 Brayton cycle solar power generation system with heat storage. Compared to conventional supercritical CO2 Brayton cycle solar power generation systems with heat storage, this invention incorporates a second superheater 6, a first superheater 7, a second reheater 8, and a first reheater 9 to achieve better temperature matching. The CO2 side of the first superheater 7 and the second reheater 8 have the same temperature, effectively reducing the outlet temperature of the heat storage medium.

[0070] 2) Compared to conventional supercritical CO2 Brayton cycle solar power generation systems with heat storage, the present invention incorporates a Rankine cycle power generation system. The stored heat fluid at the outlet of the second superheater 6 continues to serve as a heat source to drive the Rankine cycle power generation system. The presence of the Rankine cycle power generation system effectively lowers the temperature of the stored heat fluid in the cold storage tank 4, increasing the temperature difference between it and the hot storage tank 3. Consequently, the maximum heat storage capacity of the heat storage system is increased, allowing for greater utilization of solar energy.

[0071] 3) The working mode of the present invention is innovative. When the amount of heat storage medium in the heat storage tank 3 exceeds a certain value, the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system operate simultaneously, increasing the power generation of the entire system.

[0072] In order to more intuitively demonstrate the effect of the supercritical carbon dioxide Brayton combined cycle solar power generation system in the above embodiment, a specific verification case is given below.

[0073] The supercritical carbon dioxide Brayton combined cycle solar power generation system with heat storage and Figure 2 The conventional supercritical carbon dioxide Brayton cycle power generation system with heat storage is calculated for a full year. Figure 3 The intermediate heat storage tank 3 is connected to the heat storage medium inlet of the reheater 23 and the heat storage medium inlet of the superheater 22 via a first valve 21. The heat storage medium outlets of the reheater 23 and the superheater 22 are both connected to the inlet of the cold storage tank 4. The Rankine cycle uses water as the working fluid and chloride salt (NaCl-KCl-ZnCl2) as the heat storage medium. The location is Jiuquan, China. Specific parameters and simulation results are shown in Table 1.

[0074] Table 1 Parameters and simulation results

[0075]

[0076] As shown in Table 1, compared with a conventional supercritical CO2 Brayton cycle power generation system with heat storage, the supercritical CO2 Brayton combined cycle solar power generation system with heat storage proposed in this invention increases its maximum heat storage capacity by 141.92 MWh, its annual power generation by 13.25 GWh, and its annual solar energy utilization rate by 3%. Therefore, this invention can effectively improve the maximum heat storage capacity, system power generation, and solar energy utilization rate of the thermal storage system.

[0077] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0078] This document uses specific examples to illustrate the principles and implementations of the present invention. The above examples are only intended to help understand the system and core concepts of the present invention. At the same time, those skilled in the art will appreciate that variations in the specific implementations and scope of application are possible based on the concepts of the present invention. In summary, this specification should not be construed as limiting the present invention.

Claims

1. A supercritical carbon dioxide Brayton combined cycle solar power generation system, characterized in that: include: Tower solar thermal collection system, heat storage system, supercritical carbon dioxide Brayton cycle power generation system and Rankine cycle power generation system; The outlet of the tower solar thermal collection system is communicated with the first inlet of the heat storage system; the first outlet of the heat storage system is communicated with the inlet of the supercritical carbon dioxide Brayton cycle power generation system; the outlet of the supercritical carbon dioxide Brayton cycle power generation system is communicated with the inlet of the Rankine cycle power generation system; the outlet of the Rankine cycle power generation system is communicated with the second inlet of the heat storage system; the second outlet of the heat storage system is communicated with the inlet of the tower solar thermal collection system; the heat storage system is used to store solar energy collected by the tower solar thermal collection system to drive the supercritical carbon dioxide Brayton cycle power generation system and the Rankine cycle power generation system to operate; The heat storage system specifically includes: a hot storage tank and a cold storage tank; The inlet of the heat storage tank is connected to the outlet of the tower solar thermal collection system; the outlet of the heat storage tank is connected to the inlet of the supercritical carbon dioxide Brayton cycle power generation system; The inlet of the cold storage tank is connected to the outlet of the Rankine cycle power generation system; the outlet of the cold storage tank is connected to the inlet of the tower solar thermal collection system; The supercritical carbon dioxide Brayton cycle power generation system specifically includes: a first superheater, a second superheater, a first reheater, a second reheater, a first turbine, a second turbine, and a heat recovery recompression system; The outlet of the heat storage tank is in communication with the heat storage working fluid side inlet of the first reheater; the heat storage working fluid side outlet of the first reheater is in communication with the heat storage working fluid side inlet of the second reheater and the heat storage working fluid side inlet of the first superheater respectively; the heat storage working fluid side outlet of the second reheater and the heat storage working fluid side outlet of the first superheater are both in communication with the heat storage working fluid side inlet of the second superheater; the heat storage working fluid side outlet of the second superheater is in communication with the inlet of the Rankine cycle power generation system; The heat recovery and recompression system specifically includes: a first heat regenerator, a second heat regenerator, a cooler, a first compressor and a second compressor; The high-pressure side outlet of the first reheater is communicated with the carbon dioxide side inlet of the second superheater; the carbon dioxide side outlet of the second superheater is communicated with the carbon dioxide side inlet of the first superheater; the carbon dioxide side outlet of the first superheater is communicated with the inlet of the first turbine; the outlet of the first turbine is communicated with the carbon dioxide side inlet of the second reheater; the carbon dioxide side outlet of the second reheater is communicated with the carbon dioxide side inlet of the first reheater; the carbon dioxide side outlet of the first reheater is communicated with the inlet of the second turbine; and the outlet of the second turbine is communicated with the low-pressure side inlet of the first reheater; The low-pressure side outlet of the first regenerator is communicated with the low-pressure side inlet of the second regenerator; the low-pressure side outlet of the second regenerator is communicated with the carbon dioxide side inlet of the cooler and the inlet of the second compressor respectively; the carbon dioxide side outlet of the cooler is communicated with the inlet of the first compressor; the outlet of the first compressor is communicated with the high-pressure side inlet of the second regenerator; the high-pressure side outlet of the second regenerator is communicated with the high-pressure side inlet of the first regenerator; and the outlet of the second compressor is communicated with the high-pressure side inlet of the first regenerator; The heat storage medium in the heat storage system is chloride salt, carbonate, liquid metal, solid particles, air or supercritical carbon dioxide.

2. The supercritical carbon dioxide Brayton combined cycle solar power generation system according to claim 1, characterized in that: The Rankine cycle power generation system specifically includes: a heater, a third turbine, a condenser and a pump; The heat storage medium side inlet of the heater is connected to the outlet of the supercritical carbon dioxide Brayton cycle power generation system; the heat storage medium side outlet of the heater is connected to the inlet of the cold storage tank; The generator working medium side outlet of the heater is sequentially connected in series with the third turbine, the condenser and the pump; the outlet of the pump is communicated with the generator working medium side inlet of the heater.

3. The supercritical carbon dioxide Brayton combined cycle solar power generation system according to claim 1, characterized in that: The heat storage system further includes: a first valve and a second valve; The first valve is provided on the connecting pipe between the outlet of the heat storage tank and the inlet of the supercritical carbon dioxide Brayton cycle power generation system; The second valve is provided on the connecting pipeline between the outlet of the cold storage tank and the inlet of the tower-type solar thermal collection system.

4. The supercritical carbon dioxide Brayton combined cycle solar power generation system according to claim 1, characterized in that: The power generation medium in the Rankine cycle power generation system is organic matter or water.

5. The supercritical carbon dioxide Brayton combined cycle solar power generation system according to claim 1, characterized in that: The tower-type solar thermal collection system specifically includes: a heliostat and a receiver; The heliostat is used to reflect solar energy into the receiver; the outlet of the receiver is connected to the first inlet of the heat storage system; and the inlet of the receiver is connected to the second outlet of the heat storage system.

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