Photo-thermal direct-heating supercritical carbon dioxide power generation system

Abstract

The invention provides a photo-thermal direct-heating supercritical carbon dioxide power generation system, belongs to the technical field of supercritical carbon dioxide power generation, and can at least partially solve the problems that the highest temperature of existing fused salt heat storage is about 560 DEG C, the temperature of a heat storage system is low, and the power generation efficiency of supercritical carbon dioxide circulation is limited. The system comprises a photo-thermal conversion module, a pipeline module, a fused salt energy storage module, a water energy storage module and a power generation module, and is provided with a photo-thermal collector, so that the power generation module is directly heated by photo-thermal, the temperature of a working medium in the daytime heat collection period can be directly increased, the efficiency of a supercritical carbon dioxide circulating system is improved, and meanwhile, the heat storage function is taken into account; a more reasonable power generation mode is achieved, and the overall economical efficiency of the system can be improved.

Description

Technical Field

[0001] This invention belongs to the field of supercritical carbon dioxide power generation technology, specifically relating to a direct-heating supercritical carbon dioxide power generation system. Background Technology

[0002] Supercritical carbon dioxide power generation is one of the most commonly used power cycles. The combination of solar thermal power and supercritical carbon dioxide power cycle can maximize the advantages of supercritical carbon dioxide cycle and provide efficient, clean and green energy.

[0003] Current solar thermal power generation mainly uses molten salt for heat storage. The most mature binary potassium salt can store heat at a maximum temperature of about 560℃. The low temperature of the heat storage system severely limits the power generation efficiency of supercritical carbon dioxide cycle. To address this, we propose a solar thermal direct-heating supercritical carbon dioxide power generation system. Summary of the Invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art, and to provide a direct-heating supercritical carbon dioxide power generation system.

[0005] This invention provides a direct-heating supercritical carbon dioxide power generation system, comprising: The solar thermal conversion module includes multiple sets of solar thermal collectors to concentrate solar radiation during operation and directly heat the carbon dioxide working fluid in the power generation module. The pipeline module includes a heat collection pipeline connected to the solar thermal collector, a heat storage pipeline connected to the heat collection pipeline, and a heat release pipeline connected to the cold side outlet of the regenerator of the power generation module. The molten salt energy storage module includes a molten salt heat exchanger connected to the heat storage pipeline and a first molten salt storage tank and a second molten salt storage tank connected to the molten salt heat exchanger. The water energy storage module includes a water heat exchanger connected to the heat storage pipeline and a first water storage tank and a second water storage tank connected to the water heat exchanger; and The power generation module includes the regenerator and a compressor connected to the regenerator via piping.

[0006] Furthermore, multiple sets of regulating valves are provided on the heat collection pipeline, the heat storage pipeline, and the heat release pipeline.

[0007] Specifically, the molten salt energy storage module further includes a molten salt heat exchanger disposed between the first molten salt tank and the second molten salt tank and connected to the first molten salt tank and the second molten salt tank respectively.

[0008] Specifically, the molten salt exothermic heat exchanger is connected to the exothermic pipeline to heat the carbon dioxide working fluid in the exothermic pipeline during operation and deliver it to the turbine of the power generation module.

[0009] Preferably, the water energy storage module further includes a water heat exchanger disposed between the first water tank and the second water tank and connected to the first water tank and the second water tank respectively.

[0010] Specifically, the water heat exchanger is connected to the heat exchange pipeline to preheat the carbon dioxide working fluid in the heat exchange pipeline during operation and then deliver it to the molten salt heat exchanger.

[0011] Furthermore, the power generation module is a supercritical carbon dioxide power generation module.

[0012] Furthermore, the power generation module also includes a cooler connected to the regenerator piping, a turbine connected to the compressor piping, and a generator connected to the turbine.

[0013] Furthermore, the working carbon dioxide is supercritical carbon dioxide.

[0014] Specifically, the solar thermal collector is a butterfly collector, which includes multiple disc-shaped concentrating units connected in parallel.

[0015] The beneficial effects of this invention are as follows: Equipped with a solar thermal collector, the power generation module is directly heated by solar thermal energy, which can directly increase the working fluid temperature during the daytime heat collection period, improve the efficiency of the supercritical carbon dioxide cycle system, and at the same time take into account the heat storage function, realizing a more reasonable power generation mode and improving the overall economic efficiency of the system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the connection of a direct-heating supercritical carbon dioxide power generation system according to a specific embodiment of the present invention.

[0017] Among them, 1 is a solar thermal collector, 2 is a first molten salt storage tank, 3 is a second molten salt storage tank, 4 is a first water storage tank, 5 is a second water storage tank, 6 is a molten salt heat storage heat exchanger, 7 is a water heat storage heat exchanger, 8 is a molten salt heat release heat exchanger, 9 is a water heat release heat exchanger, 10 is a heat collection pipeline, 11 is a heat release pipeline, 12 is a heat storage pipeline, and 13 is a power generation module. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0019] like Figure 1As shown in the figure, a direct-heating supercritical carbon dioxide power generation system provided by a specific embodiment of the present invention includes: The solar thermal conversion module includes multiple sets of solar thermal collectors 1 for concentrating solar radiation during operation and directly heating the carbon dioxide working fluid in the power generation module 13; the piping module includes a heat collection pipe 10 connected to the solar thermal collectors 1, a heat storage pipe 12 connected to the heat collection pipe 10, and a heat release pipe 11 connected to the cold side outlet of the regenerator of the power generation module 13; the molten salt energy storage module includes a molten salt heat storage heat exchanger 6 connected to the heat storage pipe 12 and a first molten salt storage tank 2 and a second molten salt storage tank 3 connected to the molten salt heat storage heat exchanger 6; the water energy storage module includes a water heat storage heat exchanger 7 connected to the heat storage pipe 12 and a first water storage tank 4 and a second water storage tank 5 connected to the water heat storage heat exchanger 7; and the power generation module 13 includes a regenerator and a compressor connected to the regenerator piping.

[0020] Specifically, the solar thermal conversion module concentrates solar radiation onto the focal point of the collector, directly heating the circulating carbon dioxide working fluid to a high temperature and pressure (approaching or exceeding the critical point of the carbon dioxide working fluid).

[0021] Furthermore, during the day, the molten salt energy storage module transfers heat from the heat collector side to the molten salt through the molten salt heat exchanger 6, thereby heating the molten salt in the second molten salt storage tank 3 and storing it in the first molten salt storage tank 2.

[0022] Furthermore, the water storage module works similarly to molten salt, but it mainly plays a preheating role in the heat release stage. It first heats the relatively cold carbon dioxide to a medium temperature, and then the molten salt heat exchanger 8 raises the temperature to the turbine inlet requirement. This can reduce the temperature difference impact on the molten salt side and improve the overall heat exchange efficiency.

[0023] Based on the above basic implementation method, multiple sets of regulating valves are provided on the heat collection pipeline 10, the heat storage pipeline 12 and the heat release pipeline 11.

[0024] Specifically, the pipeline module determines the flow direction and heat exchange path of the working fluid through multiple sets of regulating valves, thereby flexibly switching between different operating conditions and achieving precise control of temperature, pressure and flow.

[0025] In one specific embodiment, the molten salt energy storage module further includes a molten salt heat exchanger 8 disposed between the first molten salt tank 2 and the second molten salt tank 3 and connected to the first molten salt tank 2 and the second molten salt tank 3 respectively; the solar thermal collector 1 is a butterfly collector, which includes multiple disc concentrating units connected in parallel.

[0026] In this embodiment, the molten salt exothermic heat exchanger 8 is connected to the exothermic pipeline 11 to heat the carbon dioxide working fluid in the exothermic pipeline 11 during operation and deliver it to the turbine of the power generation module 13.

[0027] Furthermore, when there is no sunlight or insufficient sunlight, the hot salt releases heat to the carbon dioxide in the heat release pipe 11 through the molten salt heat exchanger 8, providing the main heating source for the turbine.

[0028] In another specific embodiment, the water energy storage module further includes a water heat exchanger 9 disposed between the first water tank 4 and the second water tank 5 and connected to the first water tank 4 and the second water tank 5 respectively.

[0029] Specifically, the water heat exchanger 9 is connected to the heat exchange pipeline 11 to preheat the carbon dioxide working medium in the heat exchange pipeline 11 during operation and transport it to the molten salt heat exchanger 8.

[0030] In one specific implementation, the power generation module 13 is a supercritical carbon dioxide power generation module, and the carbon dioxide working medium is supercritical carbon dioxide.

[0031] In this embodiment, the power generation module 13 further includes a cooler connected to the regenerator pipeline, a turbine connected to the compressor pipeline, and a generator connected to the turbine.

[0032] Specifically, the power generation module 13 adopts a supercritical carbon dioxide Brayton cycle. The working fluid exiting the cold end is pressurized by the compressor and enters the regenerator, where it is self-heated by the waste heat from the turbine exhaust, and then enters the main heating section. The heat source for the main heating section can be direct heating from solar radiation, or preheating water plus molten salt for main heating during the energy storage discharge stage. The heated high-temperature and high-pressure working fluid drives the turbine to do work and drives the generator to output electrical energy. Subsequently, the waste heat is recovered to the cold end fluid in the regenerator, and finally, after being cooled by the cooler, it returns to the compressor inlet in a closed loop.

[0033] In another specific embodiment, the system operates as follows: During periods of ample sunshine, the system prioritizes direct heat collection to drive the turbine, while storing some heat in two heat tanks via molten salt and water heat exchangers as needed. During periods of fluctuating sunshine, the system supplements direct heating with the operation of exothermic heat exchangers for water and molten salt, maintaining a stable turbine inlet temperature through a cascaded preheating and main heating method.

[0034] Furthermore, at night or on cloudy days, the system shuts off the direct heating path, relying entirely on water preheating and molten salt main heating to complete the heating process and ensure continuous power generation. During start-up, shutdown, or low-load phases, the system typically first activates water-side preheating to gradually raise the working fluid temperature to a suitable range before introducing molten salt heating to reduce thermal stress and protect equipment materials.

[0035] Furthermore, the regenerator prioritizes recovering turbine exhaust heat to reduce the burden on the main heating section and improve cycle efficiency; the water heat exchanger 9 performs preheating in the heat release pipeline 11; the molten salt heat exchanger 8 determines the target temperature at the turbine inlet; and the regulating valve group achieves stable output, rapid response, and smooth switching between multiple operating conditions by proportioning the flow rates of the direct heating, heat storage, and heat release branches. The advantages of the overall design are reflected in high thermal efficiency, strong dispatchability, material friendliness, and engineering expansion flexibility.

[0036] To aid in a better understanding of the present invention, a more comprehensive and specific embodiment is described. In this embodiment, the present invention provides a direct-heating supercritical carbon dioxide power generation system, comprising: a solar thermal conversion module, including multiple sets of solar thermal collectors 1 for concentrating solar radiation during operation and directly heating the carbon dioxide working fluid in the power generation module 13; a piping module, including a heat collection pipe 10 connected to the solar thermal collectors 1, a heat storage pipe 12 connected to the heat collection pipe 10, and a heat release pipe 11 connected to the cold-side outlet of the regenerator of the power generation module 13; a molten salt energy storage module, including a molten salt heat storage heat exchanger 6 connected to the heat storage pipe 12 and a first molten salt storage tank 2 and a second molten salt storage tank 3 connected to the molten salt heat storage heat exchanger 6; a water energy storage module, including a water heat storage heat exchanger 7 connected to the heat storage pipe 12 and a first water storage tank 4 and a second water storage tank 5 connected to the water heat storage heat exchanger 7; and a power generation module 13, including a regenerator and a compressor connected to the regenerator piping.

[0037] In this embodiment, multiple sets of regulating valves are provided on the heat collection pipeline 10, the heat storage pipeline 12, and the heat release pipeline 11; the molten salt energy storage module also includes a molten salt heat release heat exchanger 8 disposed between the first molten salt tank 2 and the second molten salt tank 3 and connected to the first molten salt tank 2 and the second molten salt tank 3 respectively; the molten salt heat release heat exchanger 8 is connected to the heat release pipeline 11 to heat the carbon dioxide working medium in the heat release pipeline 11 during operation and transport it to the turbine of the power generation module 13; the water energy storage module also includes a water heat release heat exchanger 9 disposed between the first water tank 4 and the second water tank 5 and connected to the first water tank 4 and the second water tank 5 respectively; the water heat release heat exchanger 9 is connected to the heat release pipeline 11 to preheat the carbon dioxide working medium in the heat release pipeline 11 during operation and transport it to the molten salt heat release heat exchanger 8.

[0038] Furthermore, the power generation module 13 is a supercritical carbon dioxide power generation module; the power generation module 13 also includes a cooler connected to the regenerator pipeline, a turbine connected to the compressor pipeline, and a generator connected to the turbine; the carbon dioxide working fluid is supercritical carbon dioxide; the solar thermal collector 1 is a disc collector, which includes multiple disc concentrating units connected in parallel.

[0039] In summary, the embodiments disclosed herein have at least the following technical effects: This system utilizes the coupling of dish-type concentrating direct heating and supercritical carbon dioxide Brayton cycle to reduce one heat exchange stage, lower heat transfer losses, and improve the conversion efficiency from solar radiation to mechanical and electrical energy. Supercritical carbon dioxide has high density and a high heat transfer coefficient, enabling the core equipment to be smaller, with lower compression work and higher regenerative efficiency, thus simultaneously improving overall thermal efficiency and unit installed power density. This system utilizes a two-stage energy storage system, combining molten salt and water, to distribute heat from the high-temperature and medium-to-low-temperature stages to the most suitable media. This improves temperature difference matching and heat exchange reversibility, enhancing the overall efficiency of the storage and discharge circuit. Furthermore, during the heat release phase, preheating is performed on the water side followed by primary heating on the molten salt side, significantly reducing temperature shock and thermal stress in the molten salt heat exchanger, mitigating material fatigue and corrosion, extending the service life of key components, and reducing maintenance costs. The system has the ability to flexibly switch between multiple operating conditions. When there is sufficient sunshine, it can generate electricity directly and charge two types of energy storage simultaneously; when sunshine fluctuates, it uses water preheating combined with molten salt main heating for power compensation, stabilizing the turbine inlet temperature and unit output; at night or on cloudy days, it relies entirely on energy storage discharge for continuous heating, achieving continuous power generation. This improves the unit's dispatchability and equivalent utilization hours, reduces the curtailment rate, and improves the levelized cost of electricity (LCOE). The system's valve and piping layout allows for precise control of heat source, flow rate, and temperature, enabling rapid ramp-up and load reduction. It also possesses the ability to smooth power fluctuations and perform grid frequency regulation and peak shaving, enhancing its adaptability to weak grids and high-proportion renewable energy scenarios. Due to the good scalability of the direct-heating branch and parallel system structure, capacity expansion and segmented maintenance are more convenient, further reducing engineering implementation and lifecycle management costs.

[0040] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A direct-heating supercritical carbon dioxide power generation system, characterized in that, include: The solar thermal conversion module includes multiple sets of solar thermal collectors to concentrate solar radiation during operation and directly heat the carbon dioxide working fluid in the power generation module. The pipeline module includes a heat collection pipeline connected to the solar thermal collector, a heat storage pipeline connected to the heat collection pipeline, and a heat release pipeline connected to the cold side outlet of the regenerator of the power generation module. The molten salt energy storage module includes a molten salt heat exchanger connected to the heat storage pipeline and a first molten salt storage tank and a second molten salt storage tank connected to the molten salt heat exchanger. The water energy storage module includes a water heat exchanger connected to the heat storage pipeline and a first water storage tank and a second water storage tank connected to the water heat exchanger; and The power generation module includes the regenerator and a compressor connected to the regenerator via piping.

2. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 1, characterized in that, Multiple sets of regulating valves are installed on the heat collection pipeline, the heat storage pipeline, and the heat release pipeline.

3. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 1, characterized in that, The molten salt energy storage module also includes a molten salt exothermic heat exchanger disposed between the first molten salt tank and the second molten salt tank and connected to the first molten salt tank and the second molten salt tank respectively.

4. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 3, characterized in that, The molten salt exothermic heat exchanger is connected to the exothermic pipeline to heat the carbon dioxide working fluid in the exothermic pipeline during operation and deliver it to the turbine of the power generation system.

5. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 4, characterized in that, The water energy storage module also includes a water heat exchanger disposed between the first water tank and the second water tank and connected to the first water tank and the second water tank respectively.

6. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 5, characterized in that, The water heat exchanger is connected to the heat-exchange pipeline to preheat the carbon dioxide working fluid in the heat-exchange pipeline during operation and then deliver it to the molten salt heat exchanger.

7. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 1, characterized in that, The power generation module is a supercritical carbon dioxide power generation module.

8. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 7, characterized in that, The power generation module also includes a cooler connected to the regenerator piping, a turbine connected to the compressor piping, and a generator connected to the turbine.

9. The solar thermal direct-heating supercritical carbon dioxide power generation system according to claim 8, characterized in that, The working medium for carbon dioxide is supercritical carbon dioxide.

10. The solar thermal direct-heating supercritical carbon dioxide power generation system according to any one of claims 1 to 9, characterized in that, The solar thermal collector is a butterfly collector, which includes multiple disc-shaped concentrating units connected in parallel.

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