Solar thermo - solar - assisted compressed air energy storage system and method coupled with ORC

Abstract

The present invention discloses a solar thermal heat-supplemented compressed air energy storage system and method coupled with ORC, which includes a compressed air energy storage system, a gas-water heater, an air high-temperature heater, an air turbine unit, a generator, a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, an ORC low-temperature power generation system, and a solar thermal system; the air outlet of the compressed air energy storage system is sequentially connected to the gas-water heater, the air high-temperature heater, and the air turbine unit; the air turbine unit is connected to the generator; the compressed air energy storage system includes a multi-stage compressor, and a cooler group is arranged between two-stage compressors; the cooler group is respectively connected to the high-temperature heat storage system and the first water heat storage system; the ORC low-temperature power generation system is connected to the second water heat storage system; the second water heat storage system supplies heat to the ORC low-temperature power generation system, and the solar thermal system is connected to the high-temperature heat storage system; by using solar thermal heat supplementation, the inlet temperature of each stage of the turbine is raised, and the overall efficiency of the system is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a solar thermal supplementary heating compressed air energy storage system coupled with ORC. Background Art

[0002] In order to achieve carbon emission reduction, focus on building a clean, low-carbon, safe and efficient energy system, improve the level of clean energy utilization and the operation efficiency of the power system, the power industry proposes that specific measures for the complementary development of multiple energy sources in electricity should give full play to the flexible regulation role on the power supply side or reasonably configure energy storage. Compressed air energy storage power stations have many advantages such as large scale, high efficiency, low cost, long life, short construction period, clean and pollution-free, etc., and can also replace thermal power units to provide inertia for the power system. It is a new emerging power energy storage technology suitable for large-scale application. However, traditional compressed air systems require fossil energy for supplementary combustion. The energy consumption for supplementary heating of traditional fossil energy is large and the pollution is heavy. Moreover, the heat grade released at the outlet of the last stage of the compressor is relatively low and cannot participate in the discharge process, resulting in waste. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides an ORC-coupled supplementary heating tower-type solar thermal compressed air energy storage system, which combines a traditional non-supplementary combustion compressed air energy storage power station, a solar thermal supplementary heating system and ORC technology to construct a new low-carbon and environmentally friendly supplementary combustion compressed air energy storage system. It not only improves the comprehensive utilization efficiency of compressed air energy storage, solves the disadvantages of large energy consumption and heavy pollution in the supplementary heating of traditional fossil energy, but also provides a new solution for realizing large-scale electrical energy storage and "peak shaving and valley filling" in the construction of a new power system by compressed air energy storage, which will strongly promote the large-scale consumption of new energy, and uses the relatively low-grade heat that cannot be utilized by the original compressed air system for power generation. By combining compressed air energy storage with solar thermal supplementary heating technology and ORC low-temperature power generation technology, zero-carbon operation can be achieved.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: A solar thermal heat-supplemented compressed air energy storage system coupled with ORC, comprising a compressed air energy storage system, a gas-water heater, an air high-temperature heater, an air turbine unit, a generator, a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, an ORC low-temperature power generation system, and a solar thermal system; the air outlet of the air storage chamber of the compressed air energy storage system is sequentially connected to the gas-water heater, the air high-temperature heater, and the air turbine unit; the air turbine unit is connected to the generator; the compressed air energy storage system includes multiple-stage compressors, and a cooler group is arranged between two-stage compressors; the cooler group is respectively connected to the high-temperature heat storage system and the first water heat storage system; the hot side of the gas-water heater is connected to the first water heat storage system, the hot side of the air high-temperature heater is connected to the high-temperature heat storage system, and the heating medium inlet and outlet of the ORC low-temperature power generation system are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system provides heat sources for the ORC low-temperature power generation system; the solar thermal system is connected to the high-temperature heat storage system to supplement heat for the high-temperature heat storage system.

[0005] The solar thermal system adopts a tower-type concentrating solar collector system, a trough-type concentrating solar collector system, or a Fresnel-type solar collector system.

[0006] The heat exchanger group between adjacent two-stage compressors includes a heat exchanger and a gas-water cooler, and the cold side of the heat exchanger is connected to the high-temperature heat storage system; the cold side of the gas-water cooler is connected to the first water heat storage system.

[0007] The high-temperature heat storage system includes a hot medium tank, a buffer medium tank, and a cold medium tank. The outlet of the hot medium tank is connected to the hot side inlet of the air high-temperature heater, the outlets of the buffer medium tank and the inlet of the hot medium tank are respectively connected to the inlet and outlet of the heat absorption tower, and the inlet of the cold medium tank is connected to the hot side outlet of the air high-temperature heater; the cold side outlet of the heat exchanger is connected to the inlet of the hot medium tank, and the cold side inlet of the heat exchanger is connected to the outlet of the cold medium tank.

[0008] The first water heat storage system includes a hot water tank and a cold water tank. The outlet of the hot water tank is connected to the hot side inlet of the gas-water heater, and the inlet of the cold water tank is connected to the hot side outlet of the gas-water heater; the cold side inlet and outlet of the gas-water cooler are respectively connected to the inlet of the hot water tank and the outlet of the cold water tank.

[0009] The heat storage medium of the high-temperature heat storage system adopts molten salt, heat-conducting oil, sand, or heat storage particles.

[0010] A low-temperature heat exchanger is arranged at the outlet of the highest-stage compressor, and the low-temperature heat exchanger is connected to the second water heat storage system and provides heat for the second water heat storage system. The inlet and outlet of the second water heat storage system are respectively connected to the heating medium inlet and outlet of the ORC low-temperature power generation system.

[0011] The air turbine unit is provided with multiple stages of turbines. An air-water heater and an air high-temperature heater are sequentially arranged at the inlet of each stage of turbine along the medium flow direction, and a regulating valve is arranged at the outlet of the compressed air energy storage system.

[0012] A self-cleaning filter is arranged at the inlet of the compressed air energy storage system.

[0013] In the operation method of the solar thermal heat-supplemented compressed air energy storage system coupled with ORC of the present invention, air is compressed and stored through the compressed air energy storage system. The compressed air sequentially passes through the air-water heater and the air high-temperature heater, exchanges heat in the high-temperature heat storage system and the first water heat storage system respectively, and then enters the air turbine unit to do work, so that the air turbine unit drives a generator to generate electricity. Among them, the cooler group absorbs the heat during the process of compressing air, and at the same time stores the heat into the first water heat storage system, the second water heat storage system and the high-temperature heat storage system through water and molten salt respectively. The solar thermal system further supplements heat to the high-temperature heat storage system to increase the temperature of the heat storage medium. The first water heat storage system and the high-temperature heat storage system use the heat to heat the compressed air, and the second water heat storage system supplies heat to the ORC low-temperature power generation system.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] The system of the present invention uses solar thermal heat supplementation, thereby raising the inlet temperature of each stage of the turbine and improving the overall efficiency of the system, overcoming the disadvantages of large energy consumption, heavy pollution, and low cycle efficiency of the conventional combustion-supplemented compressed air system. At the same time, the ORC low-temperature waste heat power generation technology is used to couple with the compressed air energy storage system to recover and utilize the waste heat of the compressed air and improve the overall power generation efficiency. According to calculations, the electric-electric conversion efficiency of this system can reach more than 70%, and the highest efficiency can reach more than 80%, which is higher than that of the conventional compressed air unit. Specifically as follows:

[0016] 1) The solar thermal system is used to heat the heat storage medium, increase the temperature of the heat storage medium, and then use the heat storage medium to heat the air, raising the inlet temperature of each stage of the turbine and improving the overall efficiency of the system.

[0017] 2) The solar thermal system is adopted in this system, and the solar thermal system converts solar energy into the thermal energy of the heat storage medium and stores it in the high-temperature heat storage system.

[0018] 3) When the system is in the process of compressed energy storage, the ORC low-temperature power generation system can absorb the low-grade waste heat of air compression, improving the total energy efficiency of the system, reducing the additional investment in cooling equipment, and reducing the power consumption in the factory. Brief Description of the Drawings

[0019] Figure 1 It is a schematic diagram of a compressed air energy storage system supplemented by a tower-type concentrating solar collector system;

[0020] Figure 2 It is a schematic diagram of a compressed air energy storage system for supplementary heating of a trough-type concentrating solar collector system;

[0021] In the figure: 1. Self-cleaning filter, 2. Compressor, 3. Heat exchanger, 4. Air-water cooler, 41. Low-temperature heat exchanger, 5. Gas storage chamber, 6. Air-water heater, 7. Air high-temperature heater, 8. Air turbine, 9. Generator, 10. Thermal medium tank, 11. Buffer medium tank, 12. Cold medium tank, 13. Hot water tank, 14. Cold water tank, 15. ORC low-temperature power generation system, 16. Heliostat, 17. Receiver tower, 18. Collector, 19 - Mirror array, 20 - Collector tube. Specific embodiments

[0022] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0023] For the heat exchange in the high-temperature section of compressed air, either molten salt and water heat exchange or heat transfer oil and water can be used as the heat storage medium, and it is specifically selected according to the temperature situation. Here, molten salt is taken as an example for description.

[0024] Reference Figure 1 , the present invention provides a solar thermal supplementary heating type compressed air energy storage system coupled with ORC, including a compressed air energy storage system, an air-water heater 6, an air high-temperature heater 7, an air turbine unit, a generator 9, a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, an ORC low-temperature power generation system 15, and a solar thermal system; the air outlet of the gas storage chamber of the compressed air energy storage system is sequentially connected to the air-water heater 6, the air high-temperature heater 7, and the air turbine unit; the air turbine unit is connected to the generator 9; the compressed air energy storage system includes a multi-stage compressor, and a cooler group is arranged between two-stage compressors; the cooler group is respectively connected to the high-temperature heat storage system and the first water heat storage system; the hot side of the air-water heater 6 is connected to the first water heat storage system, the hot side of the air high-temperature heater 7 is connected to the high-temperature heat storage system, and the heating medium inlet and outlet of the ORC low-temperature power generation system 15 are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system provides heat source for the ORC low-temperature power generation system 15; the solar thermal system is connected to the high-temperature heat storage system to supplement heat for the high-temperature heat storage system; the high-temperature heat storage system refers to that the temperature of the heat storage medium is higher than that of the first water heat storage system and the second water heat storage system.

[0025] Taking the tower-type concentrating solar collector system as an example, the tower-type concentrating solar collector system includes a heliostat 16, a receiver tower 17, and a collector 18; the collector 18 is located at the top of the receiver tower 17, the reflecting surface of the heliostat 16 faces the collector 18, and the inlet and outlet of the receiver tower 17 are connected to the high-temperature heat storage system.

[0026] The heat storage medium of the tower-type solar thermal heat supplement system can be heat-conducting oil or molten salt. Specifically, the high-temperature heat storage system includes a heat medium tank 10, a buffer medium tank 11, and a cold medium tank 12. The outlet of the heat medium tank 10 is connected to the hot-side inlet of the air high-temperature heater 7. The outlets of the buffer medium tank 11 and the inlet of the heat medium tank 10 are respectively connected to the inlet and outlet of the solar tower 17. The inlet of the cold medium tank 11 is connected to the hot-side outlet of the air high-temperature heater 7.

[0027] Taking molten salt and heat-conducting oil as examples, the high-temperature heat storage system includes a hot salt tank, a buffer salt tank, and a cold salt tank. The outlet of the hot salt tank is connected to the hot-side inlet of the air high-temperature heater 7. The outlets of the buffer salt tank and the inlet of the hot salt tank are respectively connected to the inlet and outlet of the solar tower 17. The inlet of the cold salt tank is connected to the hot-side outlet of the air high-temperature heater 7; or the high-temperature heat storage system includes a hot oil tank, a buffer oil tank, and a cold oil tank. The outlet of the hot oil tank is connected to the hot-side inlet of the air high-temperature heater 7. The outlets of the buffer oil tank and the inlet of the hot oil tank are respectively connected to the inlet and outlet of the solar tower 17. The inlet of the cold oil tank is connected to the hot-side outlet of the air high-temperature heater 7.

[0028] The heat exchanger group between two adjacent stages of compressors includes a heat exchanger 3 and an air-water cooler 4. The cold side of the heat exchanger 3 is connected to the high-temperature heat storage system; the cold-side outlet of the heat exchanger 3 is connected to the inlet of the heat medium tank 10, and the cold-side inlet of the heat exchanger 3 is connected to the outlet of the cold medium tank 12; the cold side of the air-water cooler 4 is connected to the first water heat storage system, and the cold-side inlet and outlet of the air-water cooler 4 are respectively connected to the inlet of the hot water tank 13 and the outlet of the cold water tank 14.

[0029] If the heat storage medium of the high-temperature heat storage system is molten salt, heat-conducting oil, sand, heat storage particles, or water, the heat exchanger 3 adopts a heat exchanger suitable for the corresponding heat storage medium, such as an air-molten salt heat exchanger, an air-heat-conducting oil heat exchanger, a sand-heat-conducting oil heat exchanger, a heat storage particle-heat-conducting oil heat exchanger, or an air-water heat exchanger.

[0030] The water heat storage system includes a hot water tank 13 and a cold water tank 14. The outlet of the hot water tank 12 is connected to the hot-side inlet of the air-water heater 6, and the inlet of the cold water tank 14 is connected to the hot-side outlet of the air-water heater 6.

[0031] A low-temperature heat exchanger 41 is arranged at the outlet of the highest-stage compressor. The low-temperature heat exchanger 41 is connected to the second water heat storage system and provides heat for the second water heat storage system. The inlet and outlet of the second water heat storage system are respectively connected to the inlet and outlet of the heating working medium of the ORC low-temperature power generation system 15.

[0032] The air turbine unit is provided with multiple stages of air turbines. The inlet of each stage of air turbine 8 is sequentially provided with an air-water heater 6 and an air high-temperature heater 7 along the medium flow direction. A regulating valve is arranged at the outlet of the compressed air energy storage system.

[0033] A self-cleaning filter 1 is provided at the inlet of the compressed air energy storage system. Taking the high-temperature heat storage system and the solar thermal system using molten salt as the heat storage medium as an example for illustration.

[0034] The first part, as Figure 1 shown in the ORC-coupled tower type concentrating solar collector heat-supplemented compressed air energy storage system: During the compression energy storage process, the compressed air subsystem generally adopts a multi-stage compression and inter-stage cooling method. The air enters the compressor 2 after passing through the self-cleaning filter 1. The air at the outlet of each stage of the compressor enters the air-molten salt cooler for heat exchange in the high-temperature section, heating the low-temperature molten salt in the cold molten salt tank and storing it in the buffer molten salt tank; then it passes through the air-water cooler 4 for heat exchange in the low-temperature section, heating the cold water into high-temperature hot water and storing it in the hot water tank 13; a low-temperature heat exchanger 41 is provided at the last stage. The high-pressure normal-temperature air after compression and cooling is stored in the high-pressure gas storage 5.

[0035] In the energy release power generation project, the high-pressure air in the gas storage 5 drives a multi-stage air turbine and then drives the generator to complete power generation. This process adopts a multi-stage expansion process with multiple reheats. To maintain the stable operation of the turbine and improve the work capacity of the air, the high-pressure air in the gas storage 5 first enters the air-water heater 6, using the hot water in the hot water tank 13 to heat the air, and the cooled cold water is stored in the cold water tank 14; then it enters the air high-temperature heater 7, using the molten salt in the hot salt tank to heat the air, and the cooled molten salt is stored in the cold molten salt tank. The heated high-temperature and high-pressure hot air enters the turbine 8 to drive the generator 9 to do work. When the air expands to a certain extent, the temperature and pressure both decrease. Subsequently, the air enters the next-stage air-water heat exchanger 6 and air high-temperature heater 7, using the heat of water and molten salt to complete a reheat, and then enters the next-stage turbine to do work.

[0036] The heat released by cooling the high-temperature air at the outlets of the previous stages of the compressor can meet the heat required for preheating the air at the turbine inlet and inter-stage reheating. The heat released at the outlet of the last stage of the compressor does not participate in the expansion turbine power generation process. A separate water tank system is set up. During the energy release and power generation process, an ORC low-temperature power generation system 15 is synchronously set up to utilize the heat generated by the last stage of the compressor.

[0037] As an optional embodiment, the solar thermal system adopts a tower type concentrating solar collector system. The tower type concentrating solar collector system reflects solar radiation onto the solar collector 18 placed at the top of the collector tower 17 through a certain number of mirror arrays 16. The molten salt in the buffer molten salt tank enters the collector tower, is further heated and raised in temperature, breaking through the limit of the compressor exhaust temperature, and converting solar energy into the thermal energy of the molten salt working medium. The heat-exchanged molten salt is stored in the high-temperature molten salt tank 10 for system circulation use.

[0038] Reference Figure 2, when a trough-type concentrating solar heat collection system is adopted, the trough-type concentrating solar heat collection system focuses sunlight onto the heat collection pipe 20 through the reflector array 19 of the trough-shaped paraboloid of the heat collection trough to heat the heat transfer working fluid. The molten salt in the buffer molten salt tank enters the heat collection pipe, converting solar energy into the thermal energy of the working fluid and further increasing the temperature of the molten salt that has already absorbed the compression heat. The molten salt after heat exchange is stored in the high-temperature molten salt tank for system recycling.

[0039] In summary, the present invention uses solar thermal technology to supplement heat to the hot salt tank of the compressed air energy storage project, thereby raising the inlet temperature of each stage of the turbine, improving the overall efficiency of the system, overcoming the disadvantages of large energy consumption, heavy pollution, and low cycle efficiency of the conventional fuel heat-supplemented compressed air system, and achieving zero-carbon operation. According to calculations, the electrical efficiency of the compressed air energy storage with solar thermal heat supplementation is much greater than that without heat supplementation, and the efficiency can reach more than 80% at most; moreover, it broadens the application scenarios, promotes the demonstration of related equipment and the development of technologies; in areas with relatively good solar energy resources, it has high economic and social benefits and engineering practical value.

Claims

1. A solar thermal supplementary heating compressed air energy storage system coupled with ORC, characterized in that It includes a compressed air energy storage system, a gas-water heater (6), an air high-temperature heater (7), an air turbine unit, a generator (9), a high-temperature heat storage system, a first water heat storage system, a second water heat storage system, an ORC low-temperature power generation system (15), and a solar thermal system; the air outlet of the air storage chamber of the compressed air energy storage system is sequentially connected to the gas-water heater (6), the air high-temperature heater (7), and the air turbine unit; the air turbine unit is connected to the generator (9); the compressed air energy storage system includes multiple-stage compressors, and a cooler group is arranged between two-stage compressors; the cooler group is respectively connected to the high-temperature heat storage system and the first water heat storage system; the hot side of the gas-water heater (6) is connected to the first water heat storage system, the hot side of the air high-temperature heater (7) is connected to the high-temperature heat storage system, the inlet and outlet of the heating working medium of the ORC low-temperature power generation system (15) are connected to the inlet and outlet of the second water heat storage system; the second water heat storage system provides heat source for heat supply of the ORC low-temperature power generation system (15); the solar thermal system is connected to the high-temperature heat storage system to supplement heat for the high-temperature heat storage system; a low-temperature heat exchanger (41) is arranged at the outlet of the highest-stage compressor, the low-temperature heat exchanger (41) is connected to the second water heat storage system and provides heat for the second water heat storage system, and the inlet and outlet of the second water heat storage system are respectively connected to the inlet and outlet of the heating working medium of the ORC low-temperature power generation system (15).

2. The solar thermal heat-supplemented compressed air energy storage system coupled with ORC according to claim 1, wherein The solar thermal system adopts a tower-type concentrating solar collector system, a trough-type concentrating solar collector system, or a Fresnel-type solar collector system.

3. The solar thermal supplementary heat type compressed air energy storage system coupled with ORC according to claim 1, wherein The heat exchanger group between two adjacent stages of compressors includes a heat exchanger (3) and a gas-water cooler (4), the cold side of the heat exchanger (3) is connected to the high-temperature heat storage system; the cold side of the gas-water cooler (4) is connected to the first water heat storage system.

4. The solar thermal supplementary heating compressed air energy storage system coupled with ORC according to claim 2, wherein The high-temperature heat storage system includes a heat medium tank (10), a buffer medium tank (11), and a cold medium tank (12), the outlet of the heat medium tank (10) is connected to the hot side inlet of the air high-temperature heater (7), the outlets of the buffer medium tank (11) and the inlet of the heat medium tank (10) are respectively connected to the inlet and outlet of the heat absorption tower (17), and the inlet of the cold medium tank (12) is connected to the hot side outlet of the air high-temperature heater (7); the cold side outlet of the heat exchanger (3) is connected to the inlet of the buffer medium tank (11), and the cold side inlet of the heat exchanger (3) is connected to the outlet of the cold medium tank (12).

5. The solar thermal supplementary heating compressed air energy storage system coupled with ORC according to claim 1, wherein The first water heat storage system includes a hot water tank (13) and a cold water tank (14), the outlet of the hot water tank (13) is connected to the hot side inlet of the gas-water heater (6), and the inlet of the cold water tank (14) is connected to the hot side outlet of the gas-water heater (6); the cold side inlet and outlet of the gas-water cooler (4) are respectively connected to the inlet of the hot water tank (13) and the outlet of the cold water tank (14).

6. The solar thermal heat-supplemented compressed air energy storage system coupled with ORC according to claim 1, wherein, The heat storage medium of the high-temperature heat storage system adopts molten salt, heat-conducting oil, sand, or heat storage particles.

7. The solar thermal supplementary heat type compressed air energy storage system coupled with ORC according to claim 1, characterized in that, The air turbine unit is provided with multiple-stage turbines (8), the inlet of each stage of turbine (8) is sequentially provided with a gas-water heater (6) and an air high-temperature heater (7) along the medium flow direction, and a regulating valve is arranged at the outlet of the compressed air energy storage system.

8. The solar thermal supplementary heating compressed air energy storage system coupled with ORC according to claim 1, characterized in that, A self-cleaning filter (1) is arranged at the inlet of the compressed air energy storage system.

9. The operating method of the solar thermal supplementary heat compression air energy storage system coupled with ORC according to any one of claims 1 to 8, characterized in that, Air is compressed and stored in a compressed air energy storage system. The compressed air successively passes through an air-water heater (6) and an air high-temperature heater (7), exchanges heat in a high-temperature heat storage system and a first water heat storage system respectively, and then enters an air turbine unit to do work, causing the air turbine unit to drive a generator (9) to generate electricity. Among them, the cooler group absorbs the heat during the compression of the compressed air, and at the same time stores the heat in the first water heat storage system, the second water heat storage system and the high-temperature heat storage system through water and molten salt respectively. The solar thermal system further supplements heat to the high-temperature heat storage system to increase the temperature of the heat storage medium. The first water heat storage system and the high-temperature heat storage system use heat to heat the compressed air, and the second water heat storage system supplies heat to an ORC low-temperature power generation system (15).

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