Compressed air-fused salt combined energy storage photo-thermal-fuel backup complementary power generation system

Abstract

A compressed air-fused salt combined energy storage photo-thermal-fuel backup complementary power generation system mainly comprises a compressed air energy storage system, a cooling water system, a photo-thermal energy storage system, a combustion energy storage backup system and an energy storage power generation system. The compressed air energy storage system compresses air through a multi-stage isothermal compressor and stores the compressed air in a compressed air storage tank. The cooling water system is used for cooling heat generated by the compressor. The photo-thermal energy storage system utilizes a photo-thermal tower and a heliostat field to convert solar energy into fused salt heat energy. When photo-thermal energy storage is insufficient, the combustion energy storage backup system can heat fused salt through the combustion furnace to supplement energy. The energy storage power generation system heats compressed air through heat energy of high-temperature fused salt, a multi-stage isothermal expansion machine is driven to generate power, and meanwhile a heat recovery device recovers heat energy and is used for preheating the compressed air. According to the system, efficient and stable energy supply is achieved through combined energy storage and complementary power generation, and a new thought and a technical path are provided for development and utilization of renewable energy sources.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology, and in particular relates to a compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system. Background Art

[0002] In the context of the current global energy structure transformation towards clean and renewable energy, the large-scale application of renewable energy such as solar thermal has become an inevitable trend. However, the inherent instability and uncertainty of these renewable energy sources have affected the continuity and stability of energy supply, and posed challenges to the safe operation of the power grid. Although our unit has successfully developed a hydraulically balanced isothermal cycle energy storage power generation system (application number: 2024108305209) and a coal-fired energy storage power generation system (application number: 2024214667166), which have solved the instability and uncertainty of renewable energy to a certain extent, these technologies mainly rely on the electricity obtained from photovoltaic and wind power conversion in terms of green energy utilization, while ignoring the direct utilization of other renewable energy such as solar thermal. At the same time, there are still certain limitations in terms of backup energy, which is limited to providing stable energy support when the supply of renewable energy is insufficient or interrupted, and cannot achieve a backup power supply effect completely similar to that of a diesel generator.

[0003] To this end, this application proposes a compressed air-molten salt combined energy storage solar thermal power generation mode, which aims to achieve stable direct utilization of renewable energy, further improve energy utilization efficiency, and ensure the continuity and stability of energy supply. Through the design of backup energy, a backup effect similar to that of a diesel generator can be achieved. This invention will provide strong support for the transformation of the global energy structure and promote the widespread application of renewable energy, which has important practical significance and broad market prospects. Summary of the invention

[0004] The present invention provides a power generation system with a combined compressed air-molten salt energy storage, solar thermal-fuel backup complementarity, which integrates compressed air energy storage, molten salt energy storage, solar thermal power generation and combustion power generation technologies, realizes the organic combination of energy storage power generation system and backup energy system, and forms a new energy supply mode. This mode can not only realize the "peak shifting and valley filling" of electric energy, but also solve the instability and uncertainty of renewable energy, and realize the efficient utilization and optimal configuration of energy.

[0005] The specific description is as follows: A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system, including a compressed air energy storage system, a cooling water system, a solar thermal energy storage system, a combustion energy storage backup system and an energy storage power generation system; The compressed air energy storage system comprises a multi-stage cooler, a multi-stage isothermal compressor, a compressed air storage tank, a water reservoir, a hydraulic generator and connecting pipes therebetween; the multi-stage isothermal compressor has a plurality of compression stages, and the multi-stage cooler has a plurality of coolers; the inlet / outlet of the cooler air medium channel of the multi-stage cooler is respectively connected to the working medium outlet of the previous compression stage / the working medium inlet of the next compression stage of the multi-stage isothermal compressor; The working fluid inlet of the first compression stage of the multi-stage isothermal compressor is directly connected to the environment, and the working fluid outlet of the last compression stage is connected to the inlet of the working fluid channel of the compressed air storage tank; the hydraulic generator is connected between the bottom of the compressed air storage tank and the bottom end of the water reservoir; The cooling water system includes a cooling tower, a cooling water pump, a multi-stage cooler and connecting pipes therebetween; the cooling water channel of the multi-stage cooler, the cooling water pump and the cooling tower are connected by pipes to form a cooling water circulation system; The solar thermal energy storage system includes a high-temperature molten salt tank, a low-temperature molten salt tank, a solar thermal tower, a heliostat field, a first molten salt pump, and connecting pipes therebetween; the first molten salt pump is connected between the low-temperature molten salt storage tank and the solar thermal tower, and the high-temperature molten salt storage tank is directly connected to the solar thermal tower; The combustion energy storage backup system includes a high-temperature molten salt tank, a low-temperature molten salt tank, a combustion furnace, a molten salt coil, a first molten salt pump and connecting pipes therebetween; the molten salt coil is evenly arranged in the combustion furnace, one end of the molten salt coil is connected to the outlet of the first molten salt pump, the inlet of the first molten salt pump is connected to the low-temperature molten salt storage tank, and the other end of the molten salt coil is connected to the high-temperature molten salt storage tank; The energy storage power generation system includes a heat recovery device, a compressed air storage tank, a water reservoir, a multi-stage isothermal expander, a multi-stage countercurrent heat exchanger, a high-temperature molten salt tank, a low-temperature molten salt tank, a second molten salt pump, a booster pump, a generator and connecting pipes therebetween; the multi-stage isothermal expander has multiple expansion stages, and the multi-stage countercurrent heat exchanger has multiple countercurrent heat exchangers corresponding to the expansion stages of the multi-stage isothermal expander one by one; the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is installed on the expansion working medium pipeline between every two expansion stages of the multi-stage isothermal expander or on the working medium pipeline between the heat recovery device and the first-stage isothermal expander of the multi-stage isothermal expander; the molten salt medium inlet of each stage of the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is connected to the outlet of the second molten salt pump, the inlet of the second molten salt pump is connected to the high-temperature molten salt storage tank, and the outlet of each stage of the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is connected to the low-temperature molten salt storage tank; The compressed air storage tank is connected to the working medium channel inlet of the heat recovery device through a pipeline, and the outlet of the working medium channel of the heat recovery device is respectively connected to the working medium inlet of the first-stage countercurrent heat exchanger of the multi-stage countercurrent heat exchanger; the tail gas channel inlet of the heat recovery device is connected to the tail gas outlet of the last expansion stage of the multi-stage isothermal expander, and the tail gas channel outlet of the heat recovery device is connected to the environment; The booster pump is connected between the bottom of the compressed air storage tank and the bottom end of the water reservoir.

[0006] Furthermore, it also includes a clutch, which is connected between the multi-stage isothermal compressor and the multi-stage isothermal expander.

[0007] Furthermore, the multi-stage isothermal compressor, the multi-stage isothermal expander, and the generator are installed on the same rotating shaft, and the multi-stage isothermal expander drives the generator to generate electricity.

[0008] Furthermore, the first-stage countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is installed on the working fluid pipeline between the working fluid channel of the heat recovery device and the first-stage expansion stage of the multi-stage isothermal expander; the inlet / outlet of the remaining countercurrent heat exchangers of the multi-stage countercurrent heat exchanger except the first-stage countercurrent heat exchanger is respectively connected to the working fluid outlet of the previous expansion stage / the working fluid inlet of the next expansion stage of the multi-stage isothermal expander.

[0009] Furthermore, it includes a multi-stage combustion chamber, which has multiple combustion chambers corresponding one by one to the expansion stages of the multi-stage isothermal expander; the combustion chambers of the multi-stage combustion chamber are installed on the expansion working fluid pipeline between every two expansion stages of the multi-stage isothermal expander or on the working fluid pipeline between the heat recovery device and the first-stage isothermal expander of the multi-stage isothermal expander.

[0010] Furthermore, the working fluid inlet of the first-stage combustion chamber of the multi-stage combustion chamber is connected to the outlet of the working fluid channel of the heat recovery device; the inlet / outlet of the combustion chamber other than the first-stage combustion chamber of the multi-stage combustion chamber is respectively connected to the working fluid outlet of the previous expansion stage / the working fluid inlet of the next expansion stage of the multi-stage isothermal expander.

[0011] Furthermore, the fuel in the multi-stage combustion chamber is one of coal gas, natural gas, hydrogen and liquid fuel.

[0012] Furthermore, the fuel in the combustion furnace is a mixture of one or more of coal, coal powder, biomass, coal gas, natural gas, hydrogen, and liquid fuel.

[0013] Furthermore, the heat recovery device is a countercurrent heat exchanger.

[0014] In addressing the challenge of complementary power generation of renewable energy and fuel backup, the present invention exhibits the following four significant advantages: 1) Efficient energy utilization and storage: Through the cleverly designed solar thermal and compressed air energy storage power generation combination strategy, the system can efficiently utilize solar thermal energy for high-temperature, high-density, and long-term heat storage in molten salt during sunny daytime, providing a stable and reliable energy foundation for the subsequent power generation process. At the same time, the system uses electricity directly generated from low-cost or renewable energy to store compressed air energy, further improving energy utilization efficiency; 2) Flexible scheduling and response: During peak hours of electricity consumption, the system drives the expander to generate electricity through heat exchange between compressed air and molten salt, achieving efficient and flexible energy utilization. This scheduling method can adjust the power generation in real time according to the needs of the power grid, effectively respond to fluctuations in the power market, and improve the flexibility and response speed of the energy system; 3) Backup energy system enhances reliability: In particular, the present invention is also equipped with a backup energy system that generates electricity by mixing compressed air and fuel for combustion and expansion. This design can quickly start and provide stable and reliable energy support in emergency situations where the solar thermal energy storage supply is insufficient or interrupted, and there is a lack of sufficient stored energy, ensuring the continuity and stability of energy supply. This backup mechanism greatly enhances the safety and reliability of the energy system and reduces the risks caused by energy shortages or interruptions.

[0015] 4) Comprehensive solution improves overall efficiency: This comprehensive solution not only improves energy efficiency, but also effectively enhances the safety and reliability of the energy system. Through the organic combination of multiple technologies such as solar thermal energy storage, compressed air energy storage, and fuel backup power generation, the system achieves efficient, stable, and reliable energy supply, providing a new solution for the complementary joint power generation of renewable energy and fuel backup, and promoting innovative development in the energy field. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. 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 creative work.

[0017] Attached Figure 1 It is a schematic diagram of the structure of the compressed air-molten salt combined energy storage solar thermal power generation system of the present invention.

[0018] Attached Figure 2 It is a schematic diagram of the structure of the power generation system with fuel backup complementation of the present invention.

[0019] Attached Figure 3 It is a schematic diagram of the energy storage process structure of the present invention.

[0020] Attached Figure 4 It is a schematic diagram of the structure of the power generation process of the present invention.

[0021] Attached Figure 5 This is a schematic diagram of the fuel backup power generation process structure of the present invention Figure 1 .

[0022] Attached Figure 6 This is a schematic diagram of the fuel backup power generation process structure of the present invention Figure 2 .

[0023] The meanings of the serial numbers in the above figure are as follows: 1. Cooling tower; 21. Cooling water pump; 22. Booster pump; 3. Multi-stage cooler; 4. Multi-stage isothermal compressor; 5. Heat recovery device; 6. Compressed air storage tank; 7. Water reservoir; 8. Multi-stage combustion chamber; 9. Multi-stage isothermal expander; 10. Multi-stage countercurrent heat exchanger; 111. High-temperature molten salt tank; 112. Low-temperature molten salt tank; 12. Solar thermal tower; 13. Heliostat field; 14. Clutch; 151. Hydraulic generator; 152. Generator; 161. First molten salt pump; 162. Second molten salt pump; 171~1711. Valves; 18. Combustion furnace; 19. Molten salt coil. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below.

[0025] Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments.

[0026] Based on the embodiments of the present invention, all other implementations obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. To make the embodiments easier to understand, the following provides a variety of embodiments or implementation methods to illustrate the relevant devices, modules, and functions of the present invention.

[0027] In order to enable the readers of this embodiment to quickly understand the implementation mode of the present invention, the working principle expressed is explained here.

[0028] As attached Figure 1 and Figure 2 As shown, a compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system includes a compressed air energy storage system, a cooling water system, a solar thermal energy storage system, a combustion energy storage backup system and an energy storage power generation system; As attached Figure 1As shown, the compressed air energy storage system includes a multi-stage cooler 3, a multi-stage isothermal compressor 4, a compressed air storage tank 6, a water reservoir 7, a hydraulic generator 151 and connecting pipes between them. The multi-stage isothermal compressor 4 has n (n≥2) compression stages, which are respectively the first compression stage 41, the secondary compression stage 42, ..., and the final compression stage 4n. The multi-stage cooler 3 has n-1 coolers, which are respectively the first cooler 31, the secondary cooler 32, ..., and the final cooler 3n-1. Each cooler is installed on the compressed working fluid pipeline between every two compression stages of the multi-stage isothermal compressor 4, that is, the inlet / outlet of the cooler air medium channel of the multi-stage cooler 3 is respectively connected to the working fluid outlet of the previous compression stage / the working fluid inlet of the next compression stage of the multi-stage isothermal compressor 4.

[0029] The working medium inlet of the first compression stage 41 of the multi-stage isothermal compressor 4 is directly connected to the environment, and the working medium outlet of the last compression stage 4n is connected to the inlet of the working medium channel of the compressed air storage tank 6; the hydraulic generator 151 and the valve 177 are connected in series between the bottom of the compressed air storage tank 6 and the bottom end of the water reservoir 7. The function of the hydraulic generator 151 is to stabilize the pressure of the compressed air entering the compressed air storage tank 6 and recover part of the energy of the compressed air; in this process, high-pressure compressed air enters the compressed air storage tank 6, and the water in the compressed air storage tank 6 is pressed outward under the action of high-pressure gas, and the discharged high-pressure water drives the hydraulic generator 151 to operate and generate electricity. The function of the compressed air storage tank 6 is to store / release the compressed air medium that has been compressed by multi-stage isothermal compression.

[0030] The cooling water system includes a cooling tower 1, a cooling water pump 21, a multi-stage cooler 3 and connecting pipes therebetween. The cooling water channel of the multi-stage cooler 3, the cooling water pump 21 and the cooling tower 1 are connected by pipes to form a cooling water circulation system. The cooling water dissipates the heat generated by each compression stage of the multi-stage isothermal compressor 4 to the outside through the cooler of the multi-stage cooler 3, so that the compression process is kept at a lower temperature, achieving approximate "isothermal compression".

[0031] The solar thermal energy storage system includes a high-temperature molten salt tank 111, a low-temperature molten salt tank 112, a solar thermal tower 12, a heliostat field 13, a first molten salt pump 161, and connecting pipes therebetween. The first molten salt pump 161 is connected between the low-temperature molten salt storage tank 112 and the solar thermal tower 12, and the high-temperature molten salt storage tank 111 is directly connected to the solar thermal tower 12, so that the first molten salt pump 161 transports the low-temperature molten salt in the low-temperature molten salt storage tank 112 after heat exchange to the heat absorber of the solar thermal tower 12, and the solar thermal tower 12 receives the sunlight reflected by the heliostats in the heliostat field 13 to heat the low-temperature molten salt into high-temperature molten salt, which is then stored in the high-temperature molten salt storage tank 111.

[0032] like Figure 2As shown, the combustion energy storage backup system includes a high-temperature molten salt tank 111, a low-temperature molten salt tank 112, a combustion furnace, a molten salt coil, a first molten salt pump 161, and connecting pipes therebetween; the molten salt coil 19 is evenly arranged in the combustion furnace 18, one end of the molten salt coil 19 is connected to the outlet of the first molten salt pump 161 through a valve 1710, the inlet of the first molten salt pump 161 is connected to the low-temperature molten salt storage tank 112, and the other end of the molten salt coil 19 is connected to the high-temperature molten salt storage tank 111 through a valve 1211. In this way, the first molten salt pump 161 transports the low-temperature molten salt in the low-temperature molten salt storage tank 112 to the molten salt coil 19 in the combustion furnace 18, and at the same time, the fuel is sent into the combustion furnace 18 for full combustion, and the low-temperature molten salt in the molten salt coil 19 in the combustion furnace 18 is heated to high-temperature molten salt, and then stored in the high-temperature molten salt storage tank 111. The fuel in the combustion furnace 18 is coal, coal powder, biomass, coal gas, natural gas, hydrogen, liquid fuel, etc.

[0033] like Figure 4 As shown, the energy storage power generation system includes a heat recovery device 5, a compressed air storage tank 6, a water reservoir 7, a multi-stage isothermal expander 9, a multi-stage countercurrent heat exchanger 10, a high-temperature molten salt tank 111, a low-temperature molten salt tank 112, a second molten salt pump 162, a booster pump 22, a generator 152, and connecting pipes therebetween. The multi-stage isothermal expander 9 has m (m≥2) expansion stages, which are respectively a first-stage expansion stage 91, a secondary expansion stage 92, ..., and a final expansion stage 9m. The multi-stage countercurrent heat exchanger 10 has m countercurrent heat exchangers corresponding to the expansion stages of the multi-stage isothermal expander 9, which are respectively a first-stage countercurrent heat exchanger 101, a secondary countercurrent heat exchanger 102, a tertiary countercurrent heat exchanger 103, ..., and a final countercurrent heat exchanger 10m. The countercurrent heat exchanger of the multi-stage countercurrent heat exchanger 10 is installed on the expansion working fluid pipeline between every two expansion stages of the multi-stage isothermal expander 9 or on the working fluid pipeline between the heat recovery device 5 and the first-stage isothermal expander 91 of the multi-stage isothermal expander 9, that is, the first-stage countercurrent heat exchanger 101 is installed on the working fluid pipeline between the working fluid channel of the heat recovery device 5 and the first-stage expansion stage 91 of the multi-stage isothermal expander 9; the inlet / outlet of the remaining countercurrent heat exchangers of the multi-stage countercurrent heat exchanger 10 except the first-stage countercurrent heat exchanger 101 are respectively connected to the working fluid pipeline between the working fluid outlet of the previous expansion stage / the working fluid inlet of the next expansion stage of the multi-stage isothermal expander 9. The molten salt medium inlet of each stage of the multi-stage counterflow heat exchanger 10 is connected to the outlet of the second molten salt pump 162, the inlet of the second molten salt pump 162 is connected to the high-temperature molten salt storage tank 111, and the outlet of each stage of the multi-stage counterflow heat exchanger 10 is connected to the low-temperature molten salt storage tank 112.

[0034] The compressed air storage tank 6 is connected to the working fluid channel inlet of the heat recovery device 5 through a pipeline, and the outlet of the working fluid channel of the heat recovery device 5 is respectively connected to the working fluid inlet of the first-stage countercurrent heat exchanger 101 of the multi-stage countercurrent heat exchanger 10; the exhaust gas channel inlet of the heat recovery device 5 is connected to the exhaust gas outlet of the last expansion stage 9m of the multi-stage isothermal expander 9, and the exhaust gas channel outlet of the heat recovery device 5 is connected to the environment.

[0035] The booster pump 22 and the valve 176 are connected in series between the bottom of the compressed air storage tank 6 and the bottom end of the water reservoir 7. The booster pump 22 injects water into the compressed air storage tank 6, and the water compresses the air in the compressed air storage tank 6 to enter the heat recovery device 5.

[0036] like Figure 1 As shown, the compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system of the present invention includes a clutch 14, and the clutch 14 is connected between the multi-stage isothermal compressor 4 and the multi-stage isothermal expander 9 to achieve the disconnection of the rotational connection between the multi-stage isothermal compressor 4 and the multi-stage isothermal expander 9.

[0037] The multi-stage isothermal compressor 4, the multi-stage isothermal expander 9, and the generator 152 are installed on the same rotating shaft; the generator 152 is an AC generator, and the multi-stage isothermal expander 9 drives the AC generator 152 to generate electricity; like Figure 6 As shown, a compressed air-molten salt combined energy storage light-heat-fuel backup complementary power generation system includes a multi-stage combustion chamber 8, and the multi-stage combustion chamber 8 has m combustion chambers corresponding to the expansion stages of the multi-stage isothermal expander 9, which are respectively the first-stage combustion chamber 81, the secondary combustion chamber 82, the third-stage combustion chamber 83, ..., and the final combustion chamber 8m. The combustion chamber of the multi-stage combustion chamber 8 is installed on the expansion working medium pipeline between every two expansion stages of the multi-stage isothermal expander 9 or on the working medium pipeline between the heat recovery device 5 and the first-stage isothermal expander 91 of the multi-stage isothermal expander 9, that is, the first-stage combustion chamber 81 is installed on the working medium pipeline between the working medium channel of the heat recovery device 5 and the first-stage expansion stage 91; the inlet / outlet of the remaining combustion chambers of the multi-stage combustion chamber 8 except the first-stage combustion chamber 81 are respectively connected to the working medium outlet of the previous expansion stage / the working medium inlet of the next expansion stage of the multi-stage isothermal expander 9.

[0038] The function of the heat recovery device 5 is to recover the heat of the high-temperature exhaust gas that has passed through the final expansion stage 9m of the multi-stage isothermal expansion stage 9, and use the recovered heat to preheat the compressed air before doing work; that is, the high-pressure and low-temperature compressed air exchanges heat with the exhaust gas discharged from the final expansion stage 9m in the heat recovery device 5, the high-pressure and low-temperature compressed air absorbs the heat of the exhaust gas, is preheated once, and then enters the first-stage countercurrent heat exchanger 101 or the first-stage combustion chamber 81.

[0039] Each combustion chamber of the multi-stage combustion chamber 5 is quantitatively injected with fuel and mixed with the circulating working medium air entering the combustion chamber and then fully burned to produce tail gas. Each expansion stage of the multi-stage isothermal expander 9 is connected to a combustion chamber in front of it, which is driven by the tail gas produced by the combustion chamber and generates power for electricity generation.

[0040] The fuel in the combustion chamber 5 is coal gas, natural gas, hydrogen, liquid fuel, etc.

[0041] The power generation system of the present invention has three working cycle processes, namely, energy storage process, power generation process and fuel backup power generation process.

[0042] Please refer to Figure 3 As shown, the energy storage process includes two parts. The first is compressed air energy storage, which uses valley electricity and clean energy (such as solar energy and wind energy) to drive the multi-stage isothermal compressor 4 to compress and store air, thus realizing the "peak shifting and valley filling" of current electricity. The second is the solar thermal energy storage of the tower solar thermal system during the day when solar energy is abundant.

[0043] The working cycle of compressed air energy storage is as follows: low-cost electric energy drives the multi-stage isothermal compressor 4 to start working. The first compression stage 41 of the multi-stage isothermal compressor 4 inhales working air from the atmosphere and performs preliminary compression, so that the temperature and pressure of the working air are increased. In order to avoid excessive increase in the working air temperature, the working air compressed by the first compression stage 41 directly enters the first cooler 31 of the multi-stage cooler 3 for cooling. The cooled working air then enters the secondary compression stage 42 for secondary pressurization, and the working air after the secondary pressurization enters the secondary cooler 32 for cooling again. This process continues until the working air is compressed to a predetermined pressure value in the final compression stage 4n. After completing all compression and cooling steps, the working air directly enters the compressed air storage tank 6 for storage. In the compressed air storage tank 6, the high-pressure gas drives the water therein to be discharged, and the water then drives the hydraulic generator 151 to operate and generate electricity. The water output from the outlet of the hydraulic generator 151 eventually flows into the water storage tank 7, thereby completing the entire energy storage process. During this process, the cooling tower 1 provides a steady supply of cooling water to each stage of the multi-stage cooler 3 through the cooling water pump 21 to ensure that the heat generated by each compression stage of the multi-stage isothermal compressor 4 can be effectively dissipated to the external environment, thereby keeping the entire compression process at a lower temperature and achieving approximate "isothermal compression".

[0044] The working cycle of the solar thermal energy storage in the tower solar thermal system: The molten salt in the low-temperature molten salt storage tank 112 is stably transported to the heat absorber at the top of the solar thermal tower 12 under the drive of the first molten salt pump 161. At the same time, the heliostat field 13 accurately focuses the sunlight onto the heat absorber, and the heat absorber efficiently converts the focused light energy into heat energy, thereby heating the molten salt to a high temperature state. After the heating is completed, the high-temperature molten salt is continuously driven by the first molten salt pump 161 and smoothly enters the high-temperature molten salt storage tank 111 for storage for subsequent use.

[0045] Energy storage power generation process: The whole power generation cycle process is as follows Figure 4 As shown. First, the booster pump 22 injects water into the compressed air storage tank 6 to compress the air in the storage tank to reflux, thereby increasing the pressure of the compressed air. Subsequently, the compressed air directly enters the heat recovery device 5, and performs heat exchange with the high-temperature final tail gas discharged from the final expansion stage 9m of the multi-stage isothermal expander 9, and the compressed air is preheated and absorbs heat. After completing the heat exchange, the compressed air enters the compressed air channel of the first-stage countercurrent heat exchanger 101 of the multi-stage countercurrent heat exchanger 10. At the same time, the second molten salt pump 162 sends the high-temperature molten salt in the high-temperature molten salt storage tank 111 into the molten salt medium channel of the first-stage countercurrent heat exchanger 101, and the high-temperature molten salt transfers heat to the compressed air. After absorbing heat, the temperature of the compressed air rises, and the pressure remains unchanged, and then the first-stage expansion stage 91 of the multi-stage isothermal expander 9 is driven to work. The compressed air discharged from the first-stage expansion stage 91 after working enters the secondary countercurrent heat exchanger 102 of the multi-stage countercurrent heat exchanger 10. Here, the compressed air again exchanges heat with the high-temperature molten salt coming out of the high-temperature molten salt storage tank 111, and the heated compressed air then drives the secondary expansion stage 92 of the multi-stage isothermal expander 9 to do work and generate power. This heating-work process is repeated before each expansion stage of the multi-stage isothermal expander 9. Each time before driving each expansion stage of the multi-stage isothermal expander 9, the power generation cycle working fluid (i.e., compressed air) will first undergo a heating process to ensure that there is enough energy to drive the expansion stage to do work and generate electricity. Until the last expansion stage 9m of the multi-stage isothermal expander 9, the exhaust gas discharged from this stage directly enters the heat recovery device 5 for heat recovery. The exhaust gas after heat recovery is finally discharged into the atmosphere. In this way, the repetitive operation completes the entire cycle of compressed air energy storage and power generation.

[0046] In this process, in order to achieve approximate isothermal expansion, before entering each expansion stage of the multi-stage isothermal expander 9, the compressed air first enters the countercurrent heat exchanger connected in front of each expansion stage to exchange heat with the high-temperature molten salt coming out of the high-temperature molten salt storage tank 111, and absorbs the heat of the high-temperature molten salt to drive the corresponding expansion stage of the multi-stage isothermal expander 9 to do work. Fuel backup power generation process 1, such as Figure 5 As shown: First, the first molten salt pump 161 transports the low-temperature molten salt in the low-temperature molten salt storage tank 112 to the molten salt coil 19 in the combustion furnace 18, and at the same time, the fuel is sent into the combustion furnace 18 for full combustion, and the low-temperature molten salt in the molten salt coil 19 in the combustion furnace 18 is heated to high-temperature molten salt, and then stored in the high-temperature molten salt storage tank 111 to complete the molten salt heat storage.

[0047] Secondly, the first compression stage 41 of the multi-stage isothermal compressor 4 inhales working medium air from the atmosphere for compression, and the temperature and pressure of the working medium air both rise; in order to prevent the working medium temperature from rising too much, the working medium air that has been pressurized once by the first compression stage 41 directly enters the first cooler 31 of the multi-stage cooler 3 for cooling, and the working medium air that has been pressurized once after cooling enters the secondary compression stage 42 for secondary pressurization, and the working medium air that has been pressurized twice enters the secondary cooler 32 for cooling, and this continues until it is compressed to a predetermined pressure in the final compression stage 4n. The compressed working medium air directly enters the heat recovery device 5, exchanges heat with the high-temperature final tail gas discharged from the final expansion stage 9m of the multi-stage isothermal expander 9 in the heat recovery device 5, and then enters the compressed air channel of the first-stage countercurrent heat exchanger 101 of the multi-stage countercurrent heat exchanger 10. At the same time, under the action of the second molten salt pump 162, the high-temperature molten salt in the high-temperature molten salt storage tank 111 is sent to the molten salt medium channel of the first-stage countercurrent heat exchanger 101, and the heat of the high-temperature molten salt is transferred to the compressed air. After the compressed air absorbs the heat of the high-temperature molten salt, it drives the multi-stage isothermal expansion. The first expansion stage 91 of the multistage isothermal expander 9 performs work, and the compressed air after the work is cooled and depressurized; the cooled and depressurized compressed air discharged from the first expansion stage 91 of the multistage isothermal expander 9 enters the secondary countercurrent heat exchanger 102 of the multistage countercurrent heat exchanger 10, and the cooled and depressurized compressed air discharged from the first expansion stage 91 is heated by the high-temperature molten salt from the high-temperature molten salt storage tank 111 in the secondary countercurrent heat exchanger 102, and then the heated compressed air drives the secondary expansion stage 92 of the multistage isothermal expander 9 to generate power and perform work, and then the temperature and pressure are reduced again; in this way, the power generation cycle working fluid is cooled and depressurized each time Before driving each expansion stage of the multi-stage isothermal expander 9, it first undergoes a temperature rise process (i.e., the high-temperature molten salt from the high-temperature molten salt storage tank 111 is heated in the corresponding countercurrent heat exchanger). The heated power generation cycle medium drives the corresponding expansion stage of the multi-stage isothermal expander 9 to generate power for power generation until the last expansion stage 9m of the multi-stage isothermal expander 9. The tail gas discharged from the last expansion stage 9m of the multi-stage isothermal expander 9 directly enters the heat recovery device 5 for heat recovery, and the tail gas discharged from the heat recovery device 5 directly enters the air. This repetitive operation completes the continuous backup power generation process.

[0048] Fuel backup power generation process II, such as Figure 6 As shown: The first compression stage 41 of the multi-stage isothermal compressor 4 inhales working air from the atmosphere for compression, and the temperature and pressure of the working air both rise; in order to prevent the working temperature from rising too much, the working air that has been pressurized once by the first compression stage 41 directly enters the first cooler 31 of the multi-stage cooler 3 for cooling, and after cooling, the working air that has been pressurized once enters the secondary compression stage 42 for secondary pressurization, and the working air that has been pressurized twice enters the secondary cooler 32 for cooling, and so on until it is compressed to a predetermined pressure in the final compression stage 4n, and then directly enters the heat recovery device 5, and in the heat recovery device 5, heat is exchanged with the high-temperature final exhaust gas discharged from the final expansion stage 9m of the multi-stage isothermal expander 9, and the compressed air absorbs the heat of the high-temperature final exhaust gas, and then enters the first combustion chamber 81 of the multi-stage combustion chamber 8, and at the same time, the first combustion chamber 81 is injected with fuel and mixed with the compressed air entering the combustion chamber. The first expansion stage 91 of the multi-stage isothermal expander 9 is connected to the first combustion chamber 81 of the multi-stage combustion chamber 8, and the first expansion stage 91 of the multi-stage isothermal expander 9 is driven by the incoming primary exhaust gas to generate power and primary exhaust gas that is cooled and reduced in pressure after doing work; the cooled and reduced-pressure primary exhaust gas discharged from the first expansion stage 91 of the multi-stage isothermal expander 9 enters the secondary combustion chamber 81 of the multi-stage combustion chamber 8, is mixed with the injected fuel and is fully burned again to generate secondary exhaust gas, and then the secondary exhaust gas enters the secondary expansion stage 92 of the multi-stage isothermal expander 9, and the secondary expansion stage 92 is driven to generate power and secondary exhaust gas that is cooled and reduced in pressure after doing work; until the last expansion stage 9m of the multi-stage isothermal expander 9, the last expansion stage 9m is driven to generate power and the last exhaust gas that is cooled and reduced in pressure after doing work; the last exhaust gas is not directly discharged into the air, but directly enters the heat recovery device 5 for heat recovery. The temperature of the last exhaust gas discharged from the heat recovery device 5 is close to the ambient temperature and is directly discharged into the environment, thus completing the fuel backup power generation cycle process.

[0049] As described above, during energy storage power generation, the multistage isothermal expander 9 drives the AC generator 152 to generate electricity. During backup power generation, a starting power supply is first provided to the multistage isothermal compressor 4, and then the multistage isothermal expander 9 drives the AC generator 152 and the multistage isothermal compressor 4 simultaneously.

[0050] The present invention realizes efficient, stable and reliable energy supply through the organic combination of multiple technologies such as solar thermal energy storage, compressed air energy storage and fuel backup power generation. It provides a new solution for the complementary joint power generation of renewable energy and fuel backup, improves energy utilization efficiency, and effectively enhances the safety and reliability of the energy system, thus promoting innovative development in the energy field.

Claims

1. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system, characterized in that: Including compressed air energy storage system, cooling water system, solar thermal energy storage system, combustion energy storage backup system and energy storage power generation system; The compressed air energy storage system comprises a multi-stage cooler, a multi-stage isothermal compressor, a compressed air storage tank, a water reservoir, a hydraulic generator and connecting pipes therebetween; the multi-stage isothermal compressor has a plurality of compression stages, and the multi-stage cooler has a plurality of coolers; the inlet / outlet of the cooler air medium channel of the multi-stage cooler is respectively connected to the working medium outlet of the previous compression stage / the working medium inlet of the next compression stage of the multi-stage isothermal compressor; The working fluid inlet of the first compression stage of the multi-stage isothermal compressor is directly connected to the environment, and the working fluid outlet of the last compression stage is connected to the inlet of the working fluid channel of the compressed air storage tank; the hydraulic generator is connected between the bottom of the compressed air storage tank and the bottom end of the water reservoir; The cooling water system includes a cooling tower, a cooling water pump, a multi-stage cooler and connecting pipes therebetween; the cooling water channel of the multi-stage cooler, the cooling water pump and the cooling tower are connected by pipes to form a cooling water circulation system; The solar thermal energy storage system includes a high-temperature molten salt tank, a low-temperature molten salt tank, a solar thermal tower, a heliostat field, a first molten salt pump, and connecting pipes therebetween; the first molten salt pump is connected between the low-temperature molten salt storage tank and the solar thermal tower, and the high-temperature molten salt storage tank is directly connected to the solar thermal tower; The combustion energy storage backup system includes a high-temperature molten salt tank, a low-temperature molten salt tank, a combustion furnace, a molten salt coil, a first molten salt pump and connecting pipes therebetween; the molten salt coil is evenly arranged in the combustion furnace, one end of the molten salt coil is connected to the outlet of the first molten salt pump, the inlet of the first molten salt pump is connected to the low-temperature molten salt storage tank, and the other end of the molten salt coil is connected to the high-temperature molten salt storage tank; The energy storage power generation system includes a heat recovery device, a compressed air storage tank, a water reservoir, a multi-stage isothermal expander, a multi-stage countercurrent heat exchanger, a high-temperature molten salt tank, a low-temperature molten salt tank, a second molten salt pump, a booster pump, a generator and connecting pipes therebetween; the multi-stage isothermal expander has multiple expansion stages, and the multi-stage countercurrent heat exchanger has multiple countercurrent heat exchangers corresponding to the expansion stages of the multi-stage isothermal expander one by one; the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is installed on the expansion working medium pipeline between every two expansion stages of the multi-stage isothermal expander or on the working medium pipeline between the heat recovery device and the first-stage isothermal expander of the multi-stage isothermal expander; the molten salt medium inlet of each stage of the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is connected to the outlet of the second molten salt pump, the inlet of the second molten salt pump is connected to the high-temperature molten salt storage tank, and the outlet of each stage of the countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is connected to the low-temperature molten salt storage tank; The compressed air storage tank is connected to the working medium channel inlet of the heat recovery device through a pipeline, and the outlet of the working medium channel of the heat recovery device is respectively connected to the working medium inlet of the first-stage countercurrent heat exchanger of the multi-stage countercurrent heat exchanger; the tail gas channel inlet of the heat recovery device is connected to the tail gas outlet of the last expansion stage of the multi-stage isothermal expander, and the tail gas channel outlet of the heat recovery device is connected to the environment; The booster pump is connected between the bottom of the compressed air storage tank and the bottom end of the water reservoir.

2. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: Also included is a clutch connected between the multi-stage isothermal compressor and the multi-stage isothermal expander.

3. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: The multi-stage isothermal compressor, the multi-stage isothermal expander and the generator are installed on the same rotating shaft, and the multi-stage isothermal expander drives the generator to generate electricity.

4. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: The first-stage countercurrent heat exchanger of the multi-stage countercurrent heat exchanger is installed on the working medium pipeline between the working medium channel of the heat recovery device and the first-stage expansion stage of the multi-stage isothermal expander; the inlet / outlet of the remaining countercurrent heat exchangers of the multi-stage countercurrent heat exchanger except the first-stage countercurrent heat exchanger is respectively connected to the working medium outlet of the previous expansion stage / the working medium inlet of the next expansion stage of the multi-stage isothermal expander.

5. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: It comprises a multi-stage combustion chamber, which has a plurality of combustion chambers corresponding one by one to the expansion stages of the multi-stage isothermal expander; the combustion chambers of the multi-stage combustion chamber are installed on the expansion working fluid pipeline between every two expansion stages of the multi-stage isothermal expander or on the working fluid pipeline between the heat recovery device and the first-stage isothermal expander of the multi-stage isothermal expander.

6. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 5, characterized in that: The working fluid inlet of the first-stage combustion chamber of the multi-stage combustion chamber is connected to the outlet of the working fluid channel of the heat recovery device; the inlet / outlet of the combustion chamber other than the first-stage combustion chamber of the multi-stage combustion chamber is respectively connected to the working fluid outlet of the previous expansion stage / the working fluid inlet of the next expansion stage of the multi-stage isothermal expander.

7. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 5, characterized in that: The fuel in the multi-stage combustion chamber is one of coal gas, natural gas, hydrogen and liquid fuel.

8. A compressed air-molten salt combined energy storage photovoltaic-photothermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: The fuel in the combustion furnace is a mixture of one or more of coal, coal powder, biomass, coal gas, natural gas, hydrogen and liquid fuel.

9. A compressed air-molten salt combined energy storage solar thermal-fuel backup complementary power generation system as claimed in claim 1, characterized in that: The heat recovery device is a counter-flow heat exchanger.

Images