A solar energy conversion system and method of operation thereof

Abstract

The application discloses a solar energy conversion system and an operation method thereof, and belongs to the technical field of renewable energy utilization. The system comprises a hydrogen and oxygen preparation and storage unit, a combustion and power generation unit and a flue gas treatment unit. A solar light condensation high-temperature heat collector supplies heat for a hydrogen preparation device to decompose water to prepare hydrogen and oxygen, the hydrogen and oxygen are stored after being cooled and compressed, and are sent into a combustion chamber to be mixed with circulating carbon dioxide to realize oxygen-rich combustion, supercritical carbon dioxide-water vapor flue gas is generated to drive a gas turbine to generate power, the flue gas is subjected to waste heat recovery and condensation separation, water is returned to the hydrogen preparation in a closed loop, and the pressurized carbon dioxide is branched to control the temperature of the combustion chamber and the gas turbine, so that full circulation of the working medium and cascade heat exchange are realized. The solar hydrogen preparation and supercritical carbon dioxide circulation are deeply integrated, energy utilization rate is high, and operation is stable. The application can solve problems of intermittency of solar energy, low efficiency of a traditional system, large thermal pollution and the like, is energy-saving and environment-friendly, and is good in economy.

Description

Technical Field

[0001] This invention belongs to the field of renewable energy utilization technology, specifically relating to an energy conversion system and its operation method that deeply integrates solar hydrogen production, oxygen-enriched combustion and supercritical carbon dioxide Brayton cycle. Background Technology

[0002] Against the backdrop of a global energy structure shift towards cleaner and more efficient energy sources, solar energy, as the most abundant renewable energy source, has become a core direction for replacing fossil fuels. Traditional solar power generation is mainly divided into two categories: photovoltaic (PV) power generation and concentrated solar power (CSP) power generation. PV power generation is significantly affected by the intermittency of sunlight and temperature sensitivity. For every 1°C increase above 25°C, the conversion efficiency decreases by 0.4-0.5%, and its energy form is singular, with a system utilization rate of less than 20%. Conventional CSP power generation mostly uses a steam Rankine cycle, relying on a "boiling water - steam doing work" mode. This results in problems such as multiple heat exchange stages, large energy losses, and a theoretical upper limit of approximately 42% for thermoelectric conversion efficiency. At the same time, the waste heat emissions from the system easily cause environmental thermal pollution.

[0003] Hydrogen energy, as a clean secondary energy source, can convert renewable energy into chemical energy through solar-powered hydrogen production, providing a long-term energy storage pathway for the stable utilization of solar energy. Oxygen-enriched combustion and supercritical carbon dioxide Brayton cycle technology have become a research hotspot for next-generation high-efficiency thermal power generation due to their excellent working fluid thermophysical properties, high cycle efficiency, small equipment size, and ease of carbon dioxide capture.

[0004] However, existing technologies generally suffer from insufficient integration: solar thermal utilization and hydrogen production systems are not tightly coupled, resulting in poor matching of heat energy grades; the high-temperature flue gas from hydrogen-oxygen-enriched combustion is not efficiently coordinated with the supercritical carbon dioxide cycle, and the working fluid cycle, waste heat recovery, and temperature control are independent of each other, leading to low overall energy utilization, high consumption of cooling water and carbon dioxide working fluid, and difficulty in balancing operational economy and environmental protection. In addition, traditional systems lack precise temperature control mechanisms for core components such as the combustion chamber and gas turbine, making high-temperature components prone to aging and lacking operational stability. The waste heat from flue gas and the cooling heat from the working fluid are not in a closed-loop cycle, further exacerbating energy loss and thermal pollution. Summary of the Invention

[0005] To address the problems of low integration, insufficient cascade utilization of thermal energy, poor temperature control accuracy of core components, high working fluid consumption, and low overall energy utilization rate in existing solar hydrogen production and power generation coupling systems, there is an urgent need to develop an energy conversion system that deeply integrates solar thermal collection, hydrogen production, oxygen-enriched combustion, supercritical carbon dioxide work, and working fluid recycling. This system would achieve efficient cascade utilization of thermal energy throughout the entire process, closed-loop circulation of the working fluid, and active temperature control, thereby overcoming the limitations of low efficiency, high thermal pollution, and poor operational stability of traditional solar power generation and improving the economic and environmental protection levels of renewable energy power generation.

[0006] To achieve the above-mentioned technical features, the objective of this invention is as follows: The first aspect of the present invention provides a solar energy conversion system, including a hydrogen and oxygen production and storage unit, a combustion power generation unit, and a flue gas treatment unit; The hydrogen and oxygen production and storage unit is used to decompose water using solar energy to produce hydrogen and oxygen, and to cool, compress and cool the hydrogen and oxygen and store them. The combustion power generation unit is connected to the hydrogen and oxygen production and storage unit and the flue gas treatment unit, respectively, and is used to mix and burn hydrogen, oxygen and circulating carbon dioxide to generate supercritical carbon dioxide-water vapor mixed flue gas, which drives the gas turbine to drive the generator to generate electricity. The flue gas treatment unit is connected to the combustion power generation unit and is used to cool and separate water vapor from the flue gas discharged from the gas turbine. The separated water is returned to the hydrogen and oxygen production and storage unit as a circulating working fluid, and the separated carbon dioxide is returned to the combustion power generation unit as a circulating working fluid for combustion dilution and core component temperature control.

[0007] Preferably, the hydrogen and oxygen production and storage unit includes a solar concentrator high-temperature collector, a hydrogen production device, a first cooling module, a second cooling module, an oxygen compressor, a hydrogen compressor, an oxygen storage tank, and a hydrogen storage tank. The heat output end of the solar concentrator high-temperature collector is connected to the heating end of the hydrogen production device. The oxygen outlet of the hydrogen production device is connected to the inlet of the oxygen compressor via the first cooling module, and the outlet of the oxygen compressor is connected to the oxygen storage tank. The hydrogen outlet of the hydrogen production device is connected to the inlet of the hydrogen compressor via the second cooling module, and the outlet of the hydrogen compressor is connected to the hydrogen storage tank.

[0008] Preferably, the first cooling module includes heat exchanger one and heat exchanger three, and the second cooling module includes heat exchanger two and heat exchanger four; The oxygen outlet of the hydrogen production unit is connected to the oxygen storage tank via the first heat side of the heat exchanger, the oxygen compressor, and the third heat side of the heat exchanger in sequence. The hydrogen outlet of the hydrogen production unit is connected to the hydrogen storage tank via the second heat exchanger, the hydrogen compressor, and the fourth heat exchanger in sequence. The cold side outlet of heat exchanger 2 is connected to the water inlet of the hydrogen production unit.

[0009] Preferably, the combustion power generation unit includes a first flow regulating valve, a second flow regulating valve, a first preheating heat exchanger, a second preheating heat exchanger, a combustion chamber, a gas turbine, a generator, and a flue gas waste heat exchanger; The outlet of the oxygen storage tank is connected to the hot side inlet of the first preheating heat exchanger via a first flow regulating valve, and the outlet of the hydrogen storage tank is connected to the hot side inlet of the second preheating heat exchanger via a second flow regulating valve. The hot-side outlets of both the first and second preheating heat exchangers are connected to the inlet of the combustion chamber. The outlet of the combustion chamber is connected to the inlet of the gas turbine. The gas turbine is coaxially connected to the generator. The exhaust port of the gas turbine is connected to the hot-side inlet of the flue gas waste heat exchanger.

[0010] Preferably, the flue gas treatment unit includes a first condenser, a gas-liquid separator, a third valve, a fourth valve, a carbon dioxide storage tank, a fifth valve, a carbon dioxide compressor, a second condenser, and a circulation pump; The hot-side outlet of the flue gas waste heat exchanger is connected to the inlet of condenser one, and the outlet of condenser one is connected to the inlet of the gas-liquid separator. The liquid phase outlet of the gas-liquid separator is connected to the cold side inlets of heat exchangers three and four via a third valve, and the gas phase outlet of the gas-liquid separator is connected to the inlet of the carbon dioxide storage tank via a fourth valve. The outlet of the carbon dioxide storage tank passes through the fifth valve, the carbon dioxide compressor, and the condenser in sequence, connecting to the inlet of the circulating pump. The outlet of the circulating pump is divided into two paths: one path connects to the temperature control inlet of the combustion chamber, and the other path connects to the temperature control inlet of the gas turbine via the cold side of the flue gas waste heat exchanger.

[0011] Preferably, the cold-side outlet of the flue gas waste heat exchanger is also connected to the cold-side inlet of the first preheating heat exchanger and the second preheating heat exchanger, and the cold-side outlets of the first preheating heat exchanger and the second preheating heat exchanger are both connected to the inlet of the condenser.

[0012] Preferably, the system also includes a controller, which is electrically connected to a first flow regulating valve, a second flow regulating valve, a carbon dioxide compressor, and a circulating pump, respectively, and is used to regulate the flow rates of hydrogen, oxygen, and carbon dioxide according to the light intensity and power generation load.

[0013] Another aspect of the present invention provides a method for operating a solar energy conversion system, wherein the method is implemented using the solar energy conversion system, and is characterized by comprising the following steps: S1, Solar Hydrogen Production and Storage: The high-temperature heat collected by the solar concentrator is used to drive the hydrogen production device to decompose water and produce hydrogen and oxygen. The hydrogen and oxygen are then cooled, compressed, and cooled again before being stored. S2, oxygen-enriched combustion power generation: Stored hydrogen and oxygen are quantitatively fed into the combustion chamber, while circulating carbon dioxide is introduced for dilution. The mixture is burned to generate supercritical carbon dioxide-water vapor mixed flue gas. The flue gas enters the gas turbine to expand and do work, driving the generator to generate electricity. S3, Flue Gas Treatment and Separation: The flue gas discharged from the gas turbine is subjected to waste heat recovery and cooling, followed by water vapor separation to obtain liquid condensate and carbon dioxide gas; S4, working fluid closed-loop circulation: condensate is sent to a heat exchanger to cool the compressed hydrogen and oxygen, and the heated condensate is returned to the hydrogen production unit to continue producing hydrogen; carbon dioxide is pressurized and cooled, part of which is injected into the combustion chamber to control the combustion temperature, and the other part is injected into the gas turbine after being preheated by flue gas to control the turbine temperature, thus realizing the recycling of the working fluid.

[0014] Preferably, in step S1, during the hydrogen production process of the hydrogen production device, the outlet temperature of the solar concentrator high-temperature collector is 930-980℃; after hydrogen and oxygen are cooled in two stages, they are stored at 55℃ and 35℃ respectively, and at a pressure of 10-15MPa.

[0015] Preferably, in step S2, the molar ratio of hydrogen to oxygen is 2:1, and the molar ratio of carbon dioxide to hydrogen is 3-5:1; by adjusting the amount of carbon dioxide injected, the combustion chamber outlet temperature is controlled at 1200-1300℃, and the gas turbine inlet temperature is controlled at 500-600℃.

[0016] Preferably, in step S3, the exhaust gas from the gas turbine first enters the flue gas waste heat exchanger, which transfers heat to the circulating carbon dioxide and the hydrogen and oxygen to be burned. After the heat exchange, the temperature of the flue gas drops to 200-300°C, and then it is cooled to 30-40°C by the condenser before entering the gas-liquid separator.

[0017] Preferably, in step S4, the carbon dioxide is pressurized to 7-8 MPa by a carbon dioxide compressor, cooled to 15-20°C by a second condenser to become liquid carbon dioxide, and then pressurized to 20-30 MPa by a circulating pump before being diverted.

[0018] Preferably, when the light intensity is higher than 120% of the rated value, the hydrogen production of the hydrogen production device is increased, and the excess hydrogen is stored in the hydrogen storage tank; when the light intensity is lower than 80% of the rated value, the hydrogen production of the hydrogen production device is reduced, and the output of the hydrogen storage tank is increased to maintain a stable power generation load.

[0019] Preferably, when the combustion chamber temperature exceeds 1300°C or the gas turbine temperature exceeds 600°C, the amount of carbon dioxide injected is automatically increased while the amount of hydrogen and oxygen input is reduced until the temperature returns to the normal range.

[0020] Preferably, when the system is started, external carbon dioxide is first introduced to establish a circulation. After the system stabilizes, the external carbon dioxide source is turned off to achieve a complete closed-loop circulation of carbon dioxide.

[0021] The present invention has the following beneficial effects: 1. This invention deeply integrates solar hydrogen production with supercritical carbon dioxide Brayton cycle, realizing the full-process cascade utilization of solar thermal energy from high-temperature hydrogen production, medium-temperature preheating, and low-temperature waste heat recovery, effectively improving the overall energy utilization rate of the system.

[0022] 2. This invention uses recycled carbon dioxide as a diluent and coolant, which is injected into the combustion chamber and the gas turbine in two separate streams. This achieves precise temperature control of the core components, stabilizing the combustion chamber temperature at 1200-1300℃ and the gas turbine temperature at 500-600℃, thus avoiding high-temperature erosion and extending the lifespan of the core components.

[0023] 3. This invention achieves a complete closed-loop circulation of water and carbon dioxide, effectively reducing cooling water consumption. The carbon dioxide working medium only needs to be replenished once when the system starts up, and no additional addition is required during operation, which greatly reduces operating costs.

[0024] 4. This invention achieves long-term solar energy storage by storing hydrogen and oxygen, and can flexibly adjust the system's operating status according to the light intensity and power generation load to ensure the stability of power generation output.

[0025] 5. The system of this invention does not burn fossil fuels and emits no pollutants, while avoiding the environmental thermal pollution caused by the large amount of waste heat emitted by traditional systems. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0027] Figure 1 This is a system structure diagram of the present invention.

[0028] In the diagram: 1. Solar concentrator high-temperature collector; 2. Hydrogen production unit; 3. Heat exchanger one; 4. Heat exchanger two; 5. Oxygen compressor; 6. Hydrogen compressor; 7. Heat exchanger three; 8. Heat exchanger four; 9. Oxygen storage tank; 10. Hydrogen storage tank; 11. First flow regulating valve; 12. Second flow regulating valve; 13. First preheating heat exchanger; 14. Second preheating heat exchanger; 15. Combustion chamber; 16. Gas turbine; 17. Generator; 18. Flue gas waste heat exchanger; 19. Condenser one; 20. Gas-liquid separator; 21. Third valve; 22. Fourth valve; 23. Carbon dioxide storage tank; 24. Fifth valve; 25. Carbon dioxide compressor; 26. Condenser two; 27. Circulation pump. Detailed Implementation

[0029] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. This example is implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0030] Example 1: like Figure 1As shown, this embodiment provides a solar energy conversion system with a modular design, including a hydrogen and oxygen production and storage unit, a combustion power generation unit, and a flue gas treatment unit. These units cooperate to sequentially complete the energy conversion from solar energy to chemical energy to electrical energy, while simultaneously achieving closed-loop circulation of the working fluid and coordinated temperature control.

[0031] To convert solar energy into stable chemical energy and overcome the intermittent nature of solar energy, the system is equipped with a hydrogen and oxygen production and storage unit.

[0032] The hydrogen and oxygen production and storage unit includes a solar concentrator high-temperature collector 1, a hydrogen production device 2, a heat exchanger 1 3, a heat exchanger 2 4, an oxygen compressor 5, a hydrogen compressor 6, a heat exchanger 3 7, a heat exchanger 4 8, an oxygen storage tank 9, and a hydrogen storage tank 10.

[0033] The solar concentrating high-temperature collector 1 adopts a dish-type concentrating collector, whose heat output end is connected to the heating end of the hydrogen production device 2. It can concentrate solar energy to form a high-temperature heat source, continuously provide the required heat for the hydrogen production reaction, and ensure the stable operation of the hydrogen production process.

[0034] The inlet of hydrogen production unit 2 is connected to the cold side outlet of heat exchanger 4. It uses circulating return water as the raw material for hydrogen production, which can fully recover the waste heat of the system, reduce the consumption of external water replenishment, and improve the overall energy utilization efficiency.

[0035] The oxygen outlet of hydrogen production unit 2 is connected to the hot-side inlet of heat exchanger 3, the hot-side outlet of heat exchanger 3 is connected to the inlet of oxygen compressor 5, the outlet of oxygen compressor 5 is connected to the hot-side inlet of heat exchanger 7, and the hot-side outlet of heat exchanger 7 is connected to oxygen storage tank 9. Oxygen undergoes two stages of heat exchange cooling and one stage of compression, achieving rapid cooling and pressurization, and is ultimately stored in oxygen storage tank 9 at room temperature and high pressure, ensuring high storage safety and good output stability.

[0036] The hydrogen outlet of hydrogen production unit 2 is connected to the hot-side inlet of heat exchanger 4, the hot-side outlet of heat exchanger 4 is connected to the inlet of hydrogen compressor 6, the outlet of hydrogen compressor 6 is connected to the hot-side inlet of heat exchanger 8, and the hot-side outlet of heat exchanger 8 is connected to hydrogen storage tank 10. Hydrogen is processed using a process symmetrical to that of oxygen, achieving gas-oxygen separation, cooling, and independent compression and storage. This avoids the safety hazards caused by hydrogen-oxygen mixing and improves the reliability of system operation.

[0037] To efficiently convert stored hydrogen energy into electrical energy, the system is equipped with a combustion power generation unit.

[0038] The combustion power generation unit includes a first flow regulating valve 11, a second flow regulating valve 12, a first preheating heat exchanger 13, a second preheating heat exchanger 14, a combustion chamber 15, a gas turbine 16, a generator 17, and a flue gas waste heat exchanger 18.

[0039] The outlet of oxygen storage tank 9 is connected to the hot-side inlet of the first preheating heat exchanger 13 via the first flow regulating valve 11, and the outlet of hydrogen storage tank 10 is connected to the hot-side inlet of the second preheating heat exchanger 14 via the second flow regulating valve 12. By regulating the output flow of hydrogen and oxygen through valves and cooperating with the heat exchangers to preheat hydrogen and oxygen, the proportion of reactants entering the combustion chamber can be precisely controlled, thereby improving combustion efficiency and operational stability.

[0040] The hot-side outlets of the first preheating heat exchanger 13 and the second preheating heat exchanger 14 are both connected to the inlet of the combustion chamber 15. The outlet of the combustion chamber 15 is connected to the inlet of the gas turbine 16. The gas turbine 16 is coaxially connected to the generator 17. The exhaust port of the gas turbine 16 is connected to the hot-side inlet of the flue gas waste heat exchanger 18. The hydrogen-oxygen mixture is mixed and burned in the combustion chamber 15 to generate high-temperature, high-pressure flue gas. This flue gas enters the gas turbine 16, expands, and performs work to drive the generator 17 to generate electricity. The flue gas after performing work enters the flue gas waste heat exchanger 18 to achieve high-temperature waste heat recovery.

[0041] To achieve separation of flue gas and working fluid, deep recovery and recycling of waste heat, the system is equipped with a flue gas treatment unit.

[0042] The flue gas treatment unit includes a condenser 19, a gas-liquid separator 20, a third valve 21, a fourth valve 22, a carbon dioxide storage tank 23, a fifth valve 24, a carbon dioxide compressor 25, a second condenser 26, and a circulation pump 27.

[0043] The hot-side outlet of the flue gas waste heat exchanger 18 is connected to the inlet of condenser 19, and the outlet of condenser 19 is connected to the inlet of gas-liquid separator 20. After waste heat recovery, the flue gas enters condenser 19 for cooling and condensation, and then passes through gas-liquid separator 20 to achieve efficient separation of liquid water and gas carbon dioxide, laying the foundation for subsequent working fluid circulation.

[0044] The liquid phase outlet of gas-liquid separator 20 is connected via third valve 21 to the cold side inlets of heat exchangers 7 and 8 (three and four), respectively. The cold side outlets of heat exchangers 7 and 8 (four and eight) are both connected to the cold side inlet of heat exchanger 3 (one), and the cold side outlet of heat exchanger 3 (one) is connected to the cold side inlet of heat exchanger 4 (two). The separated condensate sequentially cools oxygen and hydrogen, and after its own temperature rises step by step, it returns to hydrogen production unit 2, forming a closed loop of water resources and achieving zero cooling water consumption.

[0045] The gas phase outlet of the gas-liquid separator 20 is connected to the inlet of the carbon dioxide storage tank 23 via the fourth valve 22. The outlet of the carbon dioxide storage tank 23 is connected to the inlet of the carbon dioxide compressor 25 via the fifth valve 24. The outlet of the carbon dioxide compressor 25 is connected to the inlet of the second condenser 26. The outlet of the second condenser 26 is connected to the inlet of the circulating pump 27. The separated carbon dioxide is stored, compressed, and condensed to form a high-pressure liquid working fluid, which is pressurized and output by the circulating pump 27 to meet the system's circulation and temperature control requirements.

[0046] The outlet of the circulating pump 27 is divided into two paths: one path is directly connected to the temperature control inlet of the combustion chamber 15, and the other path is connected to the cold-side inlet of the flue gas waste heat exchanger 18. The cold-side outlet of the flue gas waste heat exchanger 18 is connected to the cold-side inlets of the first preheating heat exchanger 13 and the second preheating heat exchanger 14, respectively. The cold-side outlets of the first preheating heat exchanger 13 and the second preheating heat exchanger 14 are both connected to the inlet of the condenser 19. Liquid high-pressure carbon dioxide is divided into two paths to regulate the temperature of the combustion chamber 15 and the gas turbine 16, respectively, while also participating in flue gas waste heat recovery and hydrogen-oxygen preheating, realizing cascade utilization of heat and protection of core components, thereby improving the system's operating life and stability.

[0047] The operating principle of this system: The solar concentrator high-temperature collector 1 collects heat and provides it to the hydrogen production unit 2. In the hydrogen production unit 2, the three cyclic processes react after reaching a certain temperature. The generated oxygen and hydrogen are then stored in the oxygen storage tank 9 and hydrogen storage tank 10, respectively, after passing through a heat exchanger, compressor, and a cooling and compression process. When the hydrogen reaches a certain quantity, the second flow regulating valve 12 opens, sending the hydrogen to the second preheating heat exchanger 14. The second preheating heat exchanger 14 preheats the hydrogen before sending it into the combustion chamber 15. When the oxygen reaches a certain quantity, the first flow regulating valve 11 opens, sending the oxygen to the first preheating heat exchanger 13. The first preheating heat exchanger 13 preheats the oxygen before sending it into the combustion chamber 15.

[0048] In combustion chamber 15, hydrogen, oxygen, and carbon dioxide are mixed and burned. The resulting flue gas enters gas turbine 16, expands, and performs work, driving generator 17 to generate electricity. The expanded flue gas and carbon dioxide gas stream exchange heat in flue gas waste heat exchanger 18, and then enter condenser 19 for condensation. The condensate and high-purity carbon dioxide gas at the outlet of condenser 19 enter gas-liquid separator 20 to separate the water and carbon dioxide.

[0049] The carbon dioxide from the outlet of the gas-liquid separator 20 enters the carbon dioxide compressor 25 and is pressurized to near the critical pressure. Then, it is condensed into liquid by the condenser 26. The liquid carbon dioxide is pressurized by the circulating pump 27. The pressurized carbon dioxide stream passes through the flue gas waste heat exchanger 18 for heat exchange and is then directly sent to the gas turbine 16 to regulate its temperature. Another stream enters the combustion chamber 15 to control its temperature.

[0050] The water separated by the gas-liquid separator 20 is sent to heat exchangers 7 and 8 to cool oxygen and hydrogen respectively; the water in heat exchanger 4 is sent to the hydrogen production unit 2 to provide water for the reaction therein. The fifth valve 24 controls the flow rate of carbon dioxide entering the carbon dioxide compressor 25.

[0051] Example 2 The difference between this embodiment and Embodiment 1 is that the system also includes a light sensor and a controller. The light sensor is located on the surface of the solar concentrator high-temperature collector 1, and the controller is electrically connected to the first flow regulating valve 11, the second flow regulating valve 12, the fifth valve 24, the carbon dioxide compressor 25, and the circulating pump 27.

[0052] During system operation, the light sensor collects light intensity data in real time and transmits it to the controller: When the light intensity is higher than 120% of the rated value, the controller controls the hydrogen production device 2 to increase the water inlet flow, increase the oxygen and hydrogen production, and store the excess oxygen and hydrogen in the oxygen storage tank 9 and the hydrogen storage tank 10 to maintain a stable power generation load. When the light intensity is in the range of 80%-120% of the rated value, the system operates under rated conditions, and the hydrogen production and combustion consumption maintain a dynamic balance. When the light intensity is lower than 80% of the rated value, the controller reduces the hydrogen production of the hydrogen production device 2, and at the same time opens the first flow regulating valve 11 and the second flow regulating valve 12 to increase the output flow of the oxygen storage tank 9 and the hydrogen storage tank 10, so as to ensure that the power generation does not fluctuate. In the absence of sunlight, the system relies entirely on stored hydrogen and oxygen to generate electricity continuously and maintain a stable power supply.

[0053] Example 3 The difference between this embodiment and Embodiment 1 is that the system adds a deep waste heat recovery structure to further improve energy utilization.

[0054] The flue gas waste heat exchanger 18 recovers high-temperature waste heat from the flue gas, the first preheating heat exchanger 13 and the second preheating heat exchanger 14 recover medium-temperature waste heat, and the low-temperature waste heat from the condenser 19 is recovered for preheating system makeup water.

[0055] The exhaust gas from the gas turbine 16 first enters the flue gas waste heat exchanger 18 to heat the circulating carbon dioxide, then enters the first preheating heat exchanger 13 and the second preheating heat exchanger 14 to preheat the oxygen and hydrogen, and then enters the condenser 19 to cool to 30-40℃.

[0056] The condensate separated by the gas-liquid separator 20 passes through heat exchangers 3-7, 4-8, 1-3, and 2-4 in sequence for heat exchange and temperature increase, and finally returns to the hydrogen production unit 2, achieving zero water consumption and full heat recovery.

[0057] After the cascade heat exchange, the overall energy utilization rate of the system is further improved, and the cooling water consumption is reduced by more than 80%.

[0058] Example 4 The difference between this embodiment and Embodiment 1 is that the system adds an active protection mode for the combustion chamber and gas turbine to achieve automatic over-temperature control.

[0059] When the temperature in combustion chamber 15 exceeds 1300℃, or the temperature in gas turbine 16 exceeds 600℃, the controller will activate immediately. Increase the opening of the fifth valve 24 to increase the output of the carbon dioxide compressor 25 and the circulating pump 27, thereby increasing the amount of circulating carbon dioxide injected. At the same time, the first flow regulating valve 11 and the second flow regulating valve 12 are closed to reduce the supply of oxygen and hydrogen, thereby rapidly reducing the combustion intensity.

[0060] The circulating carbon dioxide enters the combustion chamber 15 in one direction to suppress the high temperature, and then enters the gas turbine 16 after being preheated by the flue gas waste heat exchanger 18 to protect the turbine components, so that the temperature drops rapidly to a safe range.

[0061] During the system startup phase, external carbon dioxide is first introduced to establish a cycle. Once stable, the external source is shut off to achieve a 100% closed-loop carbon dioxide cycle with no leakage or emission of the working fluid.

[0062] Example 5 The operation method of the solar energy conversion system described in this embodiment includes the following steps: S1, a solar concentrator high-temperature collector 1 collects solar energy and heats the heat source to 980℃, providing reaction heat for the hydrogen production unit 2. The hydrogen production unit 2 uses water as raw material and undergoes a multi-step reaction to produce hydrogen and oxygen. The oxygen, at 100℃, is cooled to 65℃ by heat exchanger 3 and then enters oxygen compressor 5, where it is pressurized to 12MPa. After being cooled to 35℃ by heat exchanger 7, it is stored in oxygen storage tank 9. The hydrogen, at 300℃, is cooled to 100℃ by heat exchanger 4 and then enters hydrogen compressor 6, where it is pressurized to 12MPa. After being cooled to 55℃ by heat exchanger 8, it is stored in hydrogen storage tank 10.

[0063] S2, when power generation is required, the first flow regulating valve 11 and the second flow regulating valve 12 are opened, and oxygen and hydrogen are fed into the first preheating heat exchanger 13 and the second preheating heat exchanger 14 at a molar ratio of 2:1. After preheating to 250~300℃, they enter the combustion chamber 15. At the same time, the circulating pump 27 pressurizes liquid carbon dioxide to 20~30MPa, of which 40% is directly injected into the combustion chamber 15 to mix and burn with hydrogen and oxygen, controlling the combustion temperature below 1300℃, generating supercritical carbon dioxide-water vapor mixed flue gas with a pressure of 20~30MPa and a temperature of 500~600℃. The flue gas enters the gas turbine 16, expands and does work, driving the generator 17 to generate electricity. The exhaust temperature of the gas turbine is 400~500℃ and the pressure is 7.5~9MPa.

[0064] S3, the exhaust gas from the gas turbine enters the flue gas waste heat exchanger 18, which transfers heat to the circulating carbon dioxide and the hydrogen and oxygen to be burned. After the heat exchange, the temperature of the flue gas drops to below 250°C, and then it is cooled to 35°C by the condenser 19 before entering the gas-liquid separator 20, where liquid condensate and carbon dioxide gas with a purity of 99.8% are separated.

[0065] S4, the condensate is sent to heat exchangers 7 and 8 via the third valve 21 to cool the compressed oxygen and hydrogen. After being heated to 50°C, it enters heat exchanger 3 to cool the oxygen output from the hydrogen production unit. After being heated to 83.5°C, it enters heat exchanger 4 to cool the hydrogen output from the hydrogen production unit. Finally, after being heated to 95°C, it returns to hydrogen production unit 2 to continue producing hydrogen.

[0066] Carbon dioxide gas enters the carbon dioxide storage tank 23 through the fourth valve 22, and then enters the carbon dioxide compressor 25 through the fifth valve 24, where it is pressurized to 7-8 MPa. After being cooled to 25°C by the second condenser 26, it becomes liquid carbon dioxide and enters the circulation pump 27. The circulation pump 27 pressurizes the carbon dioxide to 20-30 MPa. Of the carbon dioxide output from the circulation pump 27, 55%~70% of the variable flow rate is preheated to 400~450°C by the flue gas waste heat exchanger 18 before being injected into the gas turbine 16. The remaining 30%~45% of the variable flow rate is sent to the combustion chamber 15 to control stable combustion with the highest temperature inside the combustion chamber below 1300°C. Simultaneously, it achieves a turbine inlet temperature of 500~600°C, realizing temperature protection for core components and efficient supercritical carbon dioxide expansion work output.

[0067] Although the present invention has been described in detail through the foregoing embodiments, those skilled in the art can make changes and modifications to the implementation methods without departing from the core spirit of the invention. All such changes and modifications fall within the scope of protection defined by the appended claims.

Claims

1. A solar energy conversion system, characterized in that, It includes a hydrogen and oxygen production and storage unit, a combustion power generation unit, and a flue gas treatment unit; The hydrogen and oxygen production and storage unit is used to decompose water using solar energy to produce hydrogen and oxygen, and to cool, compress and cool the hydrogen and oxygen and store them. The combustion power generation unit is connected to the hydrogen and oxygen production and storage unit and the flue gas treatment unit, respectively, and is used to mix and burn hydrogen, oxygen and circulating carbon dioxide to generate supercritical carbon dioxide-water vapor mixed flue gas, which drives the gas turbine to drive the generator to generate electricity. The flue gas treatment unit is connected to the combustion power generation unit and is used to cool and separate water vapor from the flue gas discharged from the gas turbine. The separated water is returned to the hydrogen and oxygen production and storage unit as a circulating working fluid, and the separated carbon dioxide is returned to the combustion power generation unit as a circulating working fluid for combustion dilution and core component temperature control.

2. The solar energy conversion system according to claim 1, characterized in that, The hydrogen and oxygen production and storage unit includes a solar concentrator high-temperature collector (1), a hydrogen production device (2), a first cooling module, a second cooling module, an oxygen compressor (5), a hydrogen compressor (6), an oxygen storage tank (9), and a hydrogen storage tank (10). The heat output end of the solar concentrator (1) is connected to the heating end of the hydrogen production device (2). The oxygen outlet of the hydrogen production device (2) is connected to the inlet of the oxygen compressor (5) via the first cooling module. The outlet of the oxygen compressor (5) is connected to the oxygen storage tank (9). The hydrogen outlet of the hydrogen production device (2) is connected to the inlet of the hydrogen compressor (6) via the second cooling module. The outlet of the hydrogen compressor (6) is connected to the hydrogen storage tank (10).

3. The solar energy conversion system according to claim 2, characterized in that, The first cooling module includes heat exchanger one (3) and heat exchanger three (7), and the second cooling module includes heat exchanger two (4) and heat exchanger four (8). The oxygen outlet of the hydrogen production unit (2) is connected to the oxygen storage tank (9) via the hot side of heat exchanger one (3), oxygen compressor (5), and the hot side of heat exchanger three (7) in sequence. The hydrogen outlet of the hydrogen production unit (2) is connected to the hydrogen storage tank (10) via the hot side of heat exchanger two (4), hydrogen compressor (6), and the hot side of heat exchanger four (8) in sequence. The cold side outlet of heat exchanger 2 (4) is connected to the water inlet of hydrogen production unit (2).

4. The solar energy conversion system according to claim 1, characterized in that, The combustion power generation unit includes a first flow regulating valve (11), a second flow regulating valve (12), a first preheating heat exchanger (13), a second preheating heat exchanger (14), a combustion chamber (15), a gas turbine (16), a generator (17), and a flue gas waste heat exchanger (18). The outlet of the oxygen storage tank (9) is connected to the hot side inlet of the first preheating heat exchanger (13) via the first flow regulating valve (11), and the outlet of the hydrogen storage tank (10) is connected to the hot side inlet of the second preheating heat exchanger (14) via the second flow regulating valve (12). The hot-side outlets of the first preheating heat exchanger (13) and the second preheating heat exchanger (14) are both connected to the inlet of the combustion chamber (15). The outlet of the combustion chamber (15) is connected to the inlet of the gas turbine (16). The gas turbine (16) is coaxially connected to the generator (17). The exhaust port of the gas turbine (16) is connected to the hot-side inlet of the flue gas waste heat exchanger (18).

5. The solar energy conversion system according to claim 1, characterized in that, The flue gas treatment unit includes a condenser (19), a gas-liquid separator (20), a third valve (21), a fourth valve (22), a carbon dioxide storage tank (23), a fifth valve (24), a carbon dioxide compressor (25), a second condenser (26), and a circulation pump (27). The hot side outlet of the flue gas waste heat exchanger (18) is connected to the inlet of condenser one (19), and the outlet of condenser one (19) is connected to the inlet of gas-liquid separator (20). The liquid phase outlet of the gas-liquid separator (20) is connected to the cold side inlets of heat exchanger three (7) and heat exchanger four (8) respectively via the third valve (21), and the gas phase outlet of the gas-liquid separator (20) is connected to the inlet of carbon dioxide storage tank (23) via the fourth valve (22). The outlet of the carbon dioxide storage tank (23) is connected to the inlet of the circulating pump (27) via the fifth valve (24), the carbon dioxide compressor (25), and the second condenser (26). The outlet of the circulating pump (27) is divided into two paths: one path is connected to the temperature control inlet of the combustion chamber (15), and the other path is connected to the temperature control inlet of the gas turbine (16) via the cold side of the flue gas waste heat exchanger (18).

6. The solar energy conversion system according to claim 5, characterized in that, The cold side outlet of the flue gas waste heat exchanger (18) is also connected to the cold side inlet of the first preheating heat exchanger (13) and the second preheating heat exchanger (14), respectively. The cold side outlets of the first preheating heat exchanger (13) and the second preheating heat exchanger (14) are both connected to the inlet of the condenser (19).

7. The solar energy conversion system according to claim 5, characterized in that, It also includes a controller, which is electrically connected to a first flow regulating valve (11), a second flow regulating valve (12), a carbon dioxide compressor (25), and a circulating pump (27), respectively, for adjusting the flow rates of hydrogen, oxygen, and carbon dioxide according to the light intensity and power generation load.

8. A method for operating a solar energy conversion system, wherein the method is implemented using the solar energy conversion system according to any one of claims 1-7, characterized in that, Includes the following steps: S1, Solar Hydrogen Production and Storage: The high-temperature heat collected by the solar concentrator is used to drive the hydrogen production device to decompose water and produce hydrogen and oxygen. The hydrogen and oxygen are then cooled, compressed, and cooled again before being stored. S2, oxygen-enriched combustion power generation: Stored hydrogen and oxygen are quantitatively fed into the combustion chamber, while circulating carbon dioxide is introduced for dilution. The mixture is burned to generate supercritical carbon dioxide-water vapor mixed flue gas. The flue gas enters the gas turbine to expand and do work, driving the generator to generate electricity. S3, Flue Gas Treatment and Separation: The flue gas discharged from the gas turbine is subjected to waste heat recovery and cooling, followed by water vapor separation to obtain liquid condensate and carbon dioxide gas; S4, working fluid closed-loop circulation: condensate is sent to a heat exchanger to cool the compressed hydrogen and oxygen, and the heated condensate is returned to the hydrogen production unit to continue producing hydrogen; carbon dioxide is pressurized and cooled, part of which is injected into the combustion chamber to control the combustion temperature, and the other part is injected into the gas turbine after being preheated by flue gas to control the turbine temperature, thus realizing the recycling of the working fluid.

9. The operating method according to claim 8, characterized in that, In step S1, during the hydrogen production process of the hydrogen production device, the outlet temperature of the solar concentrator high-temperature collector is 930-980℃; after hydrogen and oxygen are cooled in two stages, they are stored at 55℃ and 35℃ respectively, and at a pressure of 10-15MPa.

10. The operating method according to claim 8, characterized in that, In step S2, the molar ratio of hydrogen to oxygen is 2:1, and the molar ratio of carbon dioxide to hydrogen is 3-5:

1. By adjusting the amount of carbon dioxide injected, the combustion chamber outlet temperature is controlled at 1200-1300℃, and the gas turbine inlet temperature is controlled at 500-600℃.

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