Compressed air and water coupled multi-energy co-production energy storage system and method thereof

Abstract

The invention belongs to the technical field of energy storage, and relates to a compressed air and water coupled multi-energy co-production energy storage system and method, comprising an air compressor, a first heat exchanger, a second heat exchanger, an air turbine and a cooling module; a circulating medium of the first circulating loop is fused salt; the circulating medium of the second circulating loop is water, and the second circulating loop comprises a low-temperature water tank, a first booster pump, a second heat exchanger, a high-temperature water tank, a flash tank, a third heat exchanger, a steam turbine high-pressure cylinder and a heating module which are sequentially communicated end to end. Compression heat generated by compressed air can be stored in fused salt and water, special geographical conditions needed for storing high-pressure air are avoided, meanwhile, in the energy release stage, the stored water is used for flash evaporation and fused salt heating and then enters a steam Rankine cycle to do work, combined heat and power generation can be achieved in winter, combined cooling and power generation can be achieved in summer, and the energy-saving effect is achieved. Therefore, combined supply of different kinds of energy in different seasons is achieved, and the energy supply efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a multi-energy co-production energy storage system and method coupling compressed air and water. Background Art

[0002] With the large-scale grid connection of renewable energy and the rapid development of smart grids, energy storage technology has become the core support for improving the regulation ability of power systems and ensuring the stable operation of power grids. As a key hub of the energy Internet, energy storage systems play an irreplaceable role in peak shaving and valley filling and promoting the consumption of new energy.

[0003] In existing energy storage technologies, pumped hydro storage and compressed air are often used for energy storage. Among them, pumped hydro storage and compressed air energy storage have the advantages of large capacity and long life. However, the above energy storage technologies also have defects to varying degrees. One is that the construction of pumped hydro storage and compressed air energy storage is limited by special geographical conditions and is difficult to be used widely. The other is that existing energy storage systems generally adopt a single energy output mode, only focusing on the storage and release of electric energy, and the energy supply efficiency is low. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-energy co-production energy storage system and method coupling compressed air and water, which can reduce the demand for special geographical environments while supplying multiple types of energy and improve the energy utilization efficiency.

[0005] To achieve the above purpose, the technical solutions provided by the present invention are as follows: A multi-energy co-production energy storage system coupling compressed air and water, comprising an air compressor, a first heat exchanger, a second heat exchanger and an air turbine connected in sequence. The air compressor is used to compress the introduced air. The air turbine is coaxially arranged with the air compressor, and the power generated by its expansion work is used to drive the air compressor. At the same time, the cold generated by the expansion work is used to supply cold to users through a cooling module. It further includes: A first circulation loop with molten salt as the circulating medium, including a low-temperature molten salt tank, a first heat exchanger, a high-temperature molten salt tank and a third heat exchanger connected in sequence at the head and tail. The first heat exchanger is used to realize the heat exchange between molten salt and air; A second circulation loop with water as the circulating medium, including a low-temperature water tank, a first booster pump, a second heat exchanger, a high-temperature water tank, a flash tank, a third heat exchanger and a high-pressure cylinder of a steam turbine connected in sequence at the head and tail. The first booster pump is used to pressurize the water. The second heat exchanger is used to realize the heat exchange between water and air. The flash tank is used to flash the water stored in the high-temperature water tank to obtain steam. The third heat exchanger is used to realize the heat exchange between molten salt and steam to increase the temperature of the steam. The power generated by the expansion work of the high-pressure cylinder of the steam turbine is used to drive a generator to generate electricity. At the same time, the waste heat of the steam is used to supply heat to users through a heating module.

[0006] The features of the present invention also lie in that: The cooling module includes: A refrigeration heat exchanger, the first inlet of which is connected to the outlet of the air turbine, the first outlet of the refrigeration heat exchanger is connected to the atmosphere, the second inlet of the refrigeration heat exchanger is connected to the second outlet with a cooling cycle circuit, and the circulating medium in the cooling cycle circuit enters the refrigeration heat exchanger for heat exchange and temperature reduction and then supplies cooling to users.

[0007] The heating module includes: A heating heat exchanger, the first inlet of which is connected to the first outlet of the high-pressure cylinder of the steam turbine, the first outlet of the heating heat exchanger is connected to the first inlet of the low-temperature water tank, the second inlet of the heating heat exchanger is connected to the second outlet with a heating cycle circuit, and the circulating medium in the heating cycle circuit enters the heating heat exchanger for heat exchange and temperature increase and then supplies heating to users.

[0008] The third inlet of the heating heat exchanger is connected to the flash tank through a first throttle valve.

[0009] The second outlet of the high-pressure cylinder of the steam turbine is connected to the inlet of the low-pressure cylinder of the steam turbine. The low-pressure cylinder of the steam turbine is used to expand the steam after the high-pressure cylinder of the steam turbine expands and does work again to generate power to drive the generator to generate electricity. The outlet of the low-pressure cylinder of the steam turbine is connected to the second inlet of the low-temperature water tank. A condenser and a second booster pump are arranged between the low-pressure cylinder of the steam turbine and the low-temperature water tank. The inlet of the condenser is connected to the outlet of the low-pressure cylinder of the steam turbine, the outlet of the condenser is connected to the inlet of the second booster pump, and the outlet of the second booster pump is connected to the second inlet of the low-temperature water tank.

[0010] A reheater is arranged between the high-pressure cylinder of the steam turbine and the low-pressure cylinder of the steam turbine. The second outlet of the high-pressure cylinder of the steam turbine is connected to the first inlet of the reheater, the first outlet of the reheater is connected to the inlet of the low-pressure cylinder of the steam turbine, the second inlet of the reheater is connected to the flash tank, a medium-temperature water tank is arranged between the reheater and the first booster pump, the inlet of the medium-temperature water tank is connected to the second outlet of the reheater, and the outlet of the medium-temperature water tank is connected to the inlet of the first booster pump through a second throttle valve.

[0011] A cooler is arranged between the medium-temperature water tank and the second throttle valve. The first inlet of the cooler is connected to the outlet of the medium-temperature water tank, the first outlet of the medium-temperature water tank is connected to the second throttle valve. The inlet of the air compressor is connected to the first outlet of the preheater. The first inlet of the preheater is connected to the atmosphere, the second inlet of the preheater is connected to the second outlet of the cooler, the second outlet of the preheater is connected to the second inlet of the cooler, and the third inlet of the preheater is connected to a waste heat source.

[0012] A method for a multi-energy combined production energy storage system coupling compressed air and water includes the following steps: At normal temperature and pressure, air enters the preheater and is preheated to medium-temperature air at normal pressure. The medium-temperature air at normal pressure enters the air compressor and is compressed into high-temperature and high-pressure air. The high-temperature and high-pressure air successively enters the first heat exchanger, the second heat exchanger, and the air turbine. The low-temperature molten salt enters the first heat exchanger for heat exchange and becomes high-temperature molten salt, which is stored in the high-temperature molten salt tank. The low-temperature water is pressurized by the first booster pump and then enters the second heat exchanger for heat exchange to become medium-high temperature and high-pressure water, which is stored in the high-temperature water tank to complete energy storage. The high-temperature and high-pressure air expands and does work in the air turbine after two heat exchanges and becomes low-temperature air at normal pressure. At the same time, the power generated by the expansion work is transmitted to the air compressor; The medium-high temperature and high-pressure water enter the flash tank for flashing, generating medium-temperature saturated steam and medium-temperature saturated water. The medium-temperature saturated steam enters the third heat exchanger and exchanges heat with the high-temperature molten salt to increase the temperature, and then enters the high-pressure cylinder of the steam turbine to expand and do work to drive the generator to generate electricity; The steam that has expanded and done work in the high-pressure cylinder of the steam turbine enters the reheater, exchanges heat with the medium-temperature saturated water generated by the flash tank to increase the temperature, and then enters the low-pressure cylinder of the steam turbine to expand and do work to drive the generator to generate electricity. At the same time, when providing cooling, the low-temperature air at normal pressure after the air turbine expands and does work enters the refrigeration heat exchanger to provide cooling to users; When heating, the steam that has expanded and done work in the high-pressure cylinder of the steam turbine and the medium-temperature saturated water in the flash tank enter the heating heat exchanger to provide heating to users.

[0013] Among them, the temperature of the medium-temperature air at normal pressure is 140°C - 160°C, the pressure is 101.3 kPa; the temperature of the high-temperature and high-pressure air is 300°C - 350°C, the pressure is 300 kPa - 400 kPa; the temperature of the low-temperature air at normal pressure is -15°C - 10°C, the pressure is 101.3 kPa; the temperature of the low-temperature water is 25°C - 30°C; the temperature of the medium-high temperature and high-pressure water is 210°C - 250°C, the pressure is 3.5 MPa - 4.0 MPa; the temperature of the low-temperature molten salt is 200°C - 240°C; the temperature of the high-temperature molten salt is 290°C - 340°C; the temperature of the medium-temperature saturated steam is 190°C - 210°C, the pressure is 1.3 MPa - 1.9 MPa; the temperature of the medium-temperature saturated water is 190°C - 210°C, the pressure is 1.3 MPa - 1.9 MPa; the temperature of the high-temperature medium-pressure steam is 280°C - 330°C, the pressure is 1.3 MPa - 1.9 MPa; the temperature of the medium-temperature steam at normal pressure is 100°C - 110°C, the pressure is 101.3 kPa; the temperature of the medium-temperature water is 190°C - 210°C.

[0014] A compressed air and water coupled multi-energy co-production energy storage system and method of the present invention have the following advantages: Through the cooperation of an air compressor, an air turbine, a first heat exchanger, a second heat exchanger, a first circulation loop, a second circulation loop, a cooling module and a heating module, the present invention can store the compression heat generated by compressed air in molten salt and water, avoiding the special geographical conditions required for storing high-pressure air. At the same time, during the energy release stage, the stored water is used for flash evaporation and molten salt heating and then enters the steam Rankine cycle to do work, and it can achieve combined heat and power generation in winter and combined cooling and power generation in summer. The working mode of the steam turbine is switched between back-pressure type and condensing type according to the season, thereby realizing the combined supply of different types of energy in different seasons, improving the energy supply efficiency. At the same time, by coaxially arranging the air turbine and the air compressor, the power generated by the expansion work of the air turbine can be used to drive the air compressor, offsetting part of the power consumption of the air compressor and reducing the energy consumption. Description of the Drawings

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0016] Figure 2 It is a schematic diagram of the overall process of the present invention.

[0017] Reference Signs: 1, preheater; 2, air compressor; 3, first heat exchanger; 4, second heat exchanger; 5, air turbine; 6, refrigeration heat exchanger; 7, low-temperature water tank; 8, first booster pump; 9, high-temperature water tank; 10, low-temperature molten salt tank; 11, high-temperature molten salt tank; 12, flash tank; 13, third heat exchanger; 14, high-pressure cylinder of steam turbine; 15, heating heat exchanger; 16, first throttle valve; 17, reheater; 18, low-pressure cylinder of steam turbine; 19, condenser; 20, second booster pump; 21, medium-temperature water tank; 22, cooler; 23, second throttle valve; 101, first control valve; 102, second control valve; 103, third control valve; 104, fourth control valve; 105, fifth control valve; 106, sixth control valve; 107, seventh control valve; 108, eighth control valve; 109, ninth control valve; 110, tenth control valve. Detailed Embodiments

[0018] The technical solutions in the present invention will be clearly and exhaustively described below in conjunction with the accompanying drawings. Among them, in the description of the embodiments of the present invention, unless otherwise specified, " / " means "or". For example, A / B may mean A or B. The "and / or" in the text is only a description of the association relationship of the associated objects, indicating that there can be three relationships. For example, A and / or B may mean: A exists alone, A and B exist simultaneously, and B exists alone. In addition, in the description of the embodiments of the present invention, "a plurality of" means two or more than two. The following terms "first" and "second" are only used for descriptive purposes and cannot be construed as implying or suggesting relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features.

[0019] As Figure 1 shown, the present invention provides a multi-energy combined production energy storage system coupled with compressed air and water, including an air compressor 2, an air turbine 5, a first heat exchanger 3, a second heat exchanger 4, a first circulation loop and a second circulation loop. The air compressor 2 is used to compress the introduced air. The air turbine 5 is coaxially arranged with the air compressor 2. The power generated by its expansion work is used to drive the air compressor 2, and at the same time, the cold generated by the expansion work is used to supply cold to users through the cold supply module. The circulating medium of the first circulation loop is molten salt. The first circulation loop includes a low-temperature molten salt tank 10, a first heat exchanger 3, a high-temperature molten salt tank 11 and a third heat exchanger 13 connected in series at the head and tail. The first heat exchanger 3 is used to realize the heat exchange between the molten salt and the air. The circulating medium of the second circulation loop is water. The second circulation loop includes a low-temperature water tank 7, a first booster pump 8, a second heat exchanger 4, a high-temperature water tank 9, a flash tank 12, a third heat exchanger 13 and a high-pressure cylinder 14 of a steam turbine connected in series at the head and tail. The first booster pump 8 is used to pressurize the water. The second heat exchanger 4 is used to realize the heat exchange between the water and the air, so that the water coming out of the low-temperature water tank 7 becomes high-pressure water. The flash tank 12 is used to flash the water stored in the high-temperature water tank 9 to obtain steam. The third heat exchanger 13 is used to realize the heat exchange between the molten salt and the steam to increase the temperature of the steam. The power generated by the expansion work of the high-pressure cylinder 14 of the steam turbine is used to drive the generator to generate electricity, and at the same time, the waste heat of the steam is used to supply heat to users through the heating module. Through the cooperation of the air compressor 2, the air turbine 5, the first heat exchanger 3, the second heat exchanger 4, the first circulation loop and the second circulation loop, the present invention can store the compression heat generated by the compressed air in the molten salt and water, avoiding the special geographical conditions required for storing high-pressure air. At the same time, in the energy release stage, the stored water is used for flashing and then enters the steam Rankine cycle to do work after being heated by the molten salt, and it can realize combined heat and power production in winter and combined cooling and power production in summer, and switch the working mode of the steam turbine between the back-pressure type and the condensing type according to the season, so as to realize the combined supply of different types of energy in different seasons and improve the energy supply efficiency.

[0020] As Figure 1 shown, the outlet of the low-temperature molten salt tank 10 is connected to the first inlet of the first heat exchanger 3. The low-temperature molten salt is stored in the low-temperature molten salt tank 10. The inlet of the high-temperature molten salt tank 11 is connected to the first outlet of the first heat exchanger 3. The low-temperature water is stored in the low-temperature water tank 7. The inlet of the first booster pump 8 is connected to the outlet of the low-temperature water tank 7. The outlet of the first booster pump 8 is connected to the first inlet of the second heat exchanger 4. The first booster pump 8 is used to pressurize the water. The inlet of the high-temperature water tank 9 is connected to the first outlet of the second heat exchanger 4. The inlet of the flash tank 12 is connected to the outlet of the high-temperature water tank 9. The first inlet of the third heat exchanger 13 is connected to the first outlet of the flash tank 12. The first outlet of the third heat exchanger 13 is connected to the steam power generation module. The second inlet of the third heat exchanger 13 is connected to the outlet of the high-temperature molten salt tank 11. The second outlet of the third heat exchanger 13 is connected to the inlet of the low-temperature molten salt tank 10.

[0021] As Figure 1 shown, the cooling module includes a refrigeration heat exchanger 6. The first inlet of the refrigeration heat exchanger 6 is connected to the outlet of the air turbine 5. The first outlet of the refrigeration heat exchanger 6 is connected to the atmosphere. The second inlet and the second outlet of the refrigeration heat exchanger 6 are connected with a cooling circulation loop. The circulating medium in the cooling circulation loop enters the refrigeration heat exchanger 6 for heat exchange and cooling, and then supplies cooling to users.

[0022] As Figure 1 shown, the heating module includes: a heating heat exchanger 15. The first inlet of the heating heat exchanger 15 is connected to the first outlet of the high-pressure cylinder 14 of the steam turbine. The first outlet of the heating heat exchanger 15 is connected to the first inlet of the low-temperature water tank 7. The second inlet and the second outlet of the heating heat exchanger 15 are connected with a heating circulation loop. The circulating medium in the heating circulation loop enters the heating heat exchanger 15 for heat exchange and heating, and then supplies heating to users.

[0023] As Figure 1 shown, the third inlet of the heating heat exchanger 15 is connected to the flash tank 12 through a first throttle valve 16, that is, the second outlet of the flash tank 12 is connected to the inlet of the first throttle valve 16, and the outlet of the first throttle valve 16 is connected to the third inlet of the heating heat exchanger 15.

[0024] As Figure 1 shown, the low-pressure cylinder 18 of the steam turbine is used to use the steam after the high-pressure cylinder 14 of the steam turbine expands and does work to expand and do work again to generate power to drive the generator to generate electricity. The outlet of the low-pressure cylinder 18 of the steam turbine is connected to the second inlet of the low-temperature water tank 7. A condenser 19 and a second booster pump 20 are arranged between the low-pressure cylinder 18 of the steam turbine and the low-temperature water tank 7. The inlet of the condenser 19 is connected to the outlet of the low-pressure cylinder 18 of the steam turbine. The outlet of the condenser 19 is connected to the inlet of the second booster pump 20. The outlet of the second booster pump 20 is connected to the second inlet of the low-temperature water tank 7.

[0025] As Figure 1 shown, a reheater 17 is arranged between the high-pressure cylinder 14 and the low-pressure cylinder 18 of the steam turbine. The second outlet of the high-pressure cylinder 14 of the steam turbine is connected to the first inlet of the reheater 17, the first outlet of the reheater 17 is connected to the inlet of the low-pressure cylinder 18 of the steam turbine, and the second inlet of the reheater 17 is connected to the flash tank 12, that is, the second inlet of the reheater 17 is connected to the third outlet of the flash tank 12. A medium-temperature water tank 21 is arranged between the reheater 17 and the first booster pump 8. The inlet of the medium-temperature water tank 21 is connected to the second outlet of the reheater 17, and the outlet of the medium-temperature water tank 21 is connected to the inlet of the first booster pump 8 through a second throttle valve 23.

[0026] As Figure 1 shown, a cooler 22 is arranged between the medium-temperature water tank 21 and the second throttle valve 23. The first inlet of the cooler 22 is connected to the outlet of the medium-temperature water tank 21, the first outlet of the medium-temperature water tank 21 is connected to the second throttle valve 23. The inlet of the air compressor 2 is connected to the first outlet of the preheater 1. The first inlet of the preheater 1 is connected to the atmosphere, the second inlet of the preheater 1 is connected to the second outlet of the cooler 22, the second outlet of the preheater 1 is connected to the second inlet of the cooler 22, and the third inlet of the preheater 1 is connected to a waste heat source.

[0027] Preferably, the waste heat source is the waste heat of a chemical plant or a thermal power plant as medium-low temperature waste heat. By introducing the medium-low temperature waste heat and the heat in the cooler 22 into the preheater 1 to heat the air, the inlet temperature of the air compressor 2 is increased, thereby improving the overall performance of the system.

[0028] As Figure 1 shown, a first control valve 101 is arranged at the inlet of the preheater 1, a second control valve 102 is arranged at the outlet of the low-temperature water tank 7, a third control valve 103 is arranged at the outlet of the low-temperature molten salt tank 10, a fourth control valve 104 is arranged at the outlet of the high-temperature water tank 9, a fifth control valve 105 is arranged at the outlet of the high-temperature molten salt tank 11, a sixth control valve 106 is arranged at the first outlet of the high-pressure cylinder 14 of the steam turbine, a seventh control valve 107 is arranged at the second outlet of the flash tank 12, an eighth control valve 108 is arranged at the second outlet of the high-pressure cylinder 14 of the steam turbine, a ninth control valve 109 is arranged at the third outlet of the flash tank 12, and a tenth control valve 110 is arranged at the outlet of the medium-temperature water tank 21.

[0029] As Figure 1 shown, the input shaft of the air compressor 2 is connected to a motor, which is convenient for using the electric energy during the low valley period to supply power to the motor to drive the air compressor 2 for compressed air energy storage. The input shaft of the air compressor 2 is connected to the output shaft of the air turbine 5, which is convenient for the air turbine 5 to drive the air compressor 2 to rotate and offset part of the power consumption of the air compressor 2.

[0030] As Figure 2As shown in the figure, the present invention also provides a method for a multi-energy combined production energy storage system coupling compressed air and water, comprising the following steps: At normal temperature and pressure, air enters the preheater 1 and is preheated to medium-temperature and normal-pressure air. The medium-temperature and normal-pressure air enters the air compressor 2 and is compressed into high-temperature and high-pressure air. The high-temperature and high-pressure air sequentially enters the first heat exchanger 3, the second heat exchanger 4, and the air turbine 5. Low-temperature molten salt enters the first heat exchanger 3 for heat exchange to become high-temperature molten salt and is stored in the high-temperature molten salt tank 11. Low-temperature water is pressurized by the first booster pump 8 and then enters the second heat exchanger 4 for heat exchange to become medium-high temperature and high-pressure water, which is stored in the high-temperature water tank 9 to complete energy storage. After two heat exchanges, the high-temperature and high-pressure air expands and does work in the air turbine 5 and becomes low-temperature and normal-pressure air. At the same time, the power generated by the expansion work is transmitted to the air compressor 2.

[0031] The medium-high temperature and high-pressure water enter the flash tank 12 for flashing to generate medium-temperature saturated steam and medium-temperature saturated water. The medium-temperature saturated steam enters the third heat exchanger 13 for heat exchange with the high-temperature molten salt to increase the temperature, and then enters the high-pressure cylinder 14 of the steam turbine to expand and do work to drive the generator to generate electricity.

[0032] The steam that has expanded and done work in the high-pressure cylinder 14 of the steam turbine enters the reheater 17, exchanges heat with the medium-temperature saturated water generated by the flash tank 12 to increase the temperature, and then enters the low-pressure cylinder 18 of the steam turbine to expand and do work to drive the generator to generate electricity. At the same time, when providing cooling, the low-temperature and normal-pressure air after the air turbine 5 expands and does work enters the refrigeration heat exchanger 6 to provide cooling to users.

[0033] When heating, the steam that has expanded and done work in the high-pressure cylinder 14 of the steam turbine and the medium-temperature saturated water in the flash tank 12 enter the heating heat exchanger 15 to provide heating to users.

[0034] Among them, the temperature of the medium-temperature and normal-pressure air is 140°C to 160°C, and the pressure is 101.3 kPa; the temperature of the high-temperature and high-pressure air is 300°C to 350°C, and the pressure is 300 kPa to 400 kPa; the temperature of the low-temperature and normal-pressure air is -15°C to 10°C, and the pressure is 101.3 kPa; the temperature of the low-temperature water is 25°C to 30°C; the temperature of the medium-high temperature and high-pressure water is 210°C to 250°C, and the pressure is 3.5 MPa to 4.0 MPa; the temperature of the low-temperature molten salt is 200°C to 240°C; the temperature of the high-temperature molten salt is 290°C to 340°C; the temperature of the medium-temperature saturated steam is 190°C to 210°C, and the pressure is 1.3 MPa to 1.9 MPa; the temperature of the medium-temperature saturated water is 190°C to 210°C, and the pressure is 1.3 MPa to 1.9 MPa; the temperature of the high-temperature medium-pressure steam is 280°C to 330°C, and the pressure is 1.3 MPa to 1.9 MPa; the temperature of the medium-temperature and normal-pressure steam is 100°C to 110°C, and the pressure is 101.3 kPa; the temperature of the medium-temperature water is 190°C to 210°C.

[0035] Working principle: In the initial state, all ten control valves are closed.

[0036] When storing energy in winter, the first control valve 101, the second control valve 102, and the third control valve 103 are opened, and the fourth control valve 104, the fifth control valve 105, the sixth control valve 106, the seventh control valve 107, the eighth control valve 108, the ninth control valve 109, and the tenth control valve 110 are closed. Normal temperature and pressure air enters the preheater 1 successively, exchanges heat with medium and low temperature waste heat (provided by the waste heat of factories or thermal power plants) to medium temperature, and then enters the air compressor 2 to be compressed into high temperature and high pressure air. The high temperature and high pressure air enters the first heat exchanger 3, the second heat exchanger 4, and the air turbine 5 in sequence. The low temperature molten salt enters the first heat exchanger 3 for heat exchange to become high temperature molten salt and is stored in the high temperature molten salt tank 11. The low temperature water is pressurized by the first booster pump 8 and then enters the second heat exchanger 4 for heat exchange to become medium high temperature and high pressure water and is stored in the high temperature water tank 9, completing energy storage in winter. The high temperature and high pressure air expands and does work in the air turbine 5 after two heat exchanges and then becomes low temperature and normal pressure air. At the same time, the power generated by the expansion work is transmitted to the air compressor 2 to offset part of the power consumption of the air compressor 2.

[0037] When storing energy in summer, the first control valve 101, the second control valve 102, the third control valve 103, and the tenth control valve 110 are opened, and the fourth control valve 104, the fifth control valve 105, the sixth control valve 106, the seventh control valve 107, the eighth control valve 108, and the ninth control valve 109 are closed. Normal temperature and pressure air enters the preheater 1 for heat exchange to medium temperature (the heat in the preheater 1 is provided by the medium temperature water stored in the medium temperature tank 21), and then enters the air compressor 2 to be compressed into high temperature and high pressure air. The high temperature and high pressure air enters the first heat exchanger 3, the second heat exchanger 4, and the air turbine 5 in sequence. The low temperature molten salt enters the first heat exchanger 3 for heat exchange to become high temperature molten salt and is stored in the high temperature molten salt tank 11. The low temperature water is pressurized by the first booster pump 8 and then enters the second heat exchanger 4 for heat exchange to become medium high temperature and high pressure water and is stored in the high temperature water tank 9, completing energy storage. The high temperature and high pressure air expands and does work in the air turbine 5 after two heat exchanges and then becomes low temperature and normal pressure air. The second conveying component conveys the circulating working medium into the refrigeration heat exchanger 6 for heat exchange with the low temperature and normal pressure air, and conveys the refrigerated circulating working medium to users for cooling. The low temperature and normal pressure air absorbs heat and is discharged into the atmosphere. At the same time, the power generated by the expansion work is transmitted to the air compressor 2 to offset part of the power consumption of the air compressor 2.

[0038] When the winter system releases energy, the first control valve 101, the second control valve 102, the third control valve 103, the eighth control valve 108, the ninth control valve 109, and the tenth control valve 110 are closed, and the fourth control valve 104, the fifth control valve 105, the sixth control valve 106, and the seventh control valve 107 are opened. The medium-high temperature and high-pressure water in the high-temperature water tank 9 enters the flash tank 12 for flashing to generate medium-temperature saturated steam and saturated water. The medium-temperature and medium-pressure steam enters the third heat exchanger 13 to exchange heat with the high-temperature molten salt flowing out of the high-temperature molten salt tank 11 and then becomes high-temperature and medium-pressure steam, and then enters the high-pressure cylinder 14 of the steam turbine to expand and do work to drive the generator to generate electricity. The medium-temperature saturated water generated by the flash tank passes through the first throttle valve and enters the heating heat exchanger 15 together with the medium-temperature and normal-pressure steam after expansion in the high-pressure cylinder 14 of the steam turbine. After heat exchange to low-temperature and normal-pressure water, it enters the low-temperature water tank 7 for storage. The first conveying component conveys the circulating working medium into the heating heat exchanger 15 for heat exchange, and conveys the heated circulating working medium to users for heating. The high-temperature molten salt releases heat in the third heat exchanger 13 and then enters the low-temperature molten salt tank 10 for storage.

[0039] When the summer system releases energy, the first control valve 101, the second control valve 102, the third control valve 103, the sixth control valve 106, the seventh control valve 107, and the tenth control valve 110 are closed, and the fourth control valve 104, the fifth control valve 105, the eighth control valve 108, and the ninth control valve 109 are opened. The medium-high temperature and high-pressure water in the high-temperature water tank 9 enters the flash tank 12 for flashing to generate medium-temperature saturated steam and saturated water. The medium-temperature and medium-pressure steam enters the third heat exchanger 13 to exchange heat with the high-temperature molten salt flowing out of the high-temperature molten salt tank 11 and then becomes high-temperature and medium-pressure steam, and then enters the high-pressure cylinder 14 of the steam turbine to expand and do work to drive the generator to generate electricity. The expanded steam enters the reheater 17, exchanges heat with the medium-temperature saturated water at the outlet of the flash tank 12 to increase the temperature, and then enters the low-pressure steam turbine 18 to further expand and do work to drive the generator to generate electricity. Finally, the steam expanded to low pressure is condensed into saturated liquid by the condenser 19, pressurized to normal pressure by the second water pump 20, and enters the low-temperature water tank 7 for storage. The high-temperature molten salt releases heat in the third heat exchanger 13 and then enters the low-temperature molten salt tank 10 for storage. The medium-temperature saturated water at the outlet of the flash tank 12 becomes medium-temperature water after releasing heat in the reheater 17 and enters the medium-temperature water tank 21 for storage. The medium-temperature water stored in the medium-temperature water tank 21 releases heat and cools down in the cooler 22, which is used to heat the air in the preheater 1, and then forms low-temperature water after depressurization through the second throttle valve 23, mixes with the low-temperature water in the low-temperature water tank, and enters the next cycle, thus completing the summer energy release process.

[0040] Other advantages of a multi-energy combined production energy storage system and method coupling compressed air and water according to the present invention are as follows: First, the present invention uses air and water as working fluids, which are cheap, easily available, clean and pollution-free. At the same time, equipment such as steam turbines, condensers, and water pumps can directly utilize the existing equipment in thermal power plants, saving costs.

[0041] Second, in the energy release stage, the present invention sets up a flash tank to generate medium-temperature and medium-pressure steam in a flash manner from medium- and high-quality compressed heat as the energy release working medium, avoiding the traditional steam Rankine cycle from generating working steam by absorbing a large amount of latent heat and improving the system energy conversion efficiency.

[0042] Third, the present invention does not require storing high-pressure air, reducing the floor area of the system and enhancing the layout flexibility.

[0043] Fourth, the present invention uses two-stage heat exchangers to recover the heat of high-pressure air, and also uses multiple heat exchangers to utilize the heat, realizing the cascaded utilization of energy and improving the energy utilization rate.

[0044] It can be understood that the present invention is described through some embodiments. Those skilled in the art know that without departing from the spirit and scope of the present invention, various changes or equivalent replacements can be made to these features and embodiments. Additionally, under the teaching of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention belong to the scope protected by the present invention.

Claims

1. A multi-energy co-production energy storage system coupling compressed air and water, characterized in that, It includes an air compressor (2), a first heat exchanger (3), a second heat exchanger (4) and an air turbine (5) which are connected in sequence. The air compressor (2) is used to compress the introduced air. The air turbine (5) is coaxially arranged with the air compressor (2). The power generated by its expansion work is used to drive the air compressor (2), and at the same time, the cold quantity generated by the expansion work is used to supply cold to users through a cold supply module. It also includes: A first circulation loop with molten salt as the circulating medium, which includes a low-temperature molten salt tank (10), a first heat exchanger (3), a high-temperature molten salt tank (11) and a third heat exchanger (13) connected in sequence at the head and tail. The first heat exchanger (3) is used to realize the heat exchange between molten salt and air; A second circulation loop with water as the circulating medium, which includes a low-temperature water tank (7), a first booster pump (8), a second heat exchanger (4), a high-temperature water tank (9), a flash tank (12), a third heat exchanger (13) and a high-pressure cylinder of a steam turbine (14) connected in sequence at the head and tail. The first booster pump (8) is used to pressurize water. The second heat exchanger (4) is used to realize the heat exchange between water and air. The flash tank (12) is used to flash the water stored in the high-temperature water tank (9) to obtain steam. The third heat exchanger (13) is used to realize the heat exchange between molten salt and steam to increase the temperature of the steam. The power generated by the expansion work of the high-pressure cylinder of the steam turbine (14) is used to drive a generator to generate electricity, and at the same time, the waste heat of the steam is used to supply heat to users through a heating module.

2. The multi - energy combined production energy storage system coupled with compressed air and water according to claim 1, wherein, The cold supply module includes: A refrigeration heat exchanger (6), the first inlet of which is connected to the outlet of the air turbine (5). The first outlet of the refrigeration heat exchanger (6) is connected to the atmosphere. A cold supply circulation loop is connected between the second inlet and the second outlet of the refrigeration heat exchanger (6). The circulating medium in the cold supply circulation loop enters the refrigeration heat exchanger (6) to exchange heat and cool down, and then supplies cold to users.

3. A multi-energy combined production energy storage system coupling compressed air and water according to claim 2, characterized in that, The heating module includes: A heating heat exchanger (15), the first inlet of which is connected to the first outlet of the high-pressure cylinder of the steam turbine (14). The first outlet of the heating heat exchanger (15) is connected to the first inlet of the low-temperature water tank (7). A heating circulation loop is connected between the second inlet and the second outlet of the heating heat exchanger (15). The circulating medium in the heating circulation loop enters the heating heat exchanger (15) to exchange heat and warm up, and then supplies heat to users.

4. A multi-energy combined production energy storage system coupling compressed air and water according to claim 3, characterized in that, The third inlet of the heating heat exchanger (15) is connected to the flash tank (12) through a first throttle valve (16).

5. A multi-energy co-production energy storage system coupled with compressed air and water according to claim 3, characterized in that, The second outlet of the high-pressure cylinder (14) of the steam turbine is connected to the inlet of the low-pressure cylinder (18) of the steam turbine. The low-pressure cylinder (18) of the steam turbine is used to expand the steam after the high-pressure cylinder (14) of the steam turbine expands and does work again to generate power to drive the generator to generate electricity. The outlet of the low-pressure cylinder (18) of the steam turbine is connected to the second inlet of the low-temperature water tank (7). A condenser (19) and a second booster pump (20) are arranged between the low-pressure cylinder (18) of the steam turbine and the low-temperature water tank (7). The inlet of the condenser (19) is connected to the outlet of the low-pressure cylinder (18) of the steam turbine. The outlet of the condenser (19) is connected to the inlet of the second booster pump (20). The outlet of the second booster pump (20) is connected to the second inlet of the low-temperature water tank (7).

6. The multi - energy combined production energy storage system coupling compressed air and water according to claim 4, characterized in that, A reheater (17) is arranged between the high-pressure cylinder (14) and the low-pressure cylinder (18) of the steam turbine. The second outlet of the high-pressure cylinder (14) of the steam turbine is connected to the first inlet of the reheater (17). The first outlet of the reheater (17) is connected to the inlet of the low-pressure cylinder (18) of the steam turbine. The second inlet of the reheater (17) is connected to the flash tank (12). A medium-temperature water tank (21) is arranged between the reheater (17) and the first booster pump (8). The inlet of the medium-temperature water tank (21) is connected to the second outlet of the reheater (17). The outlet of the medium-temperature water tank (21) is connected to the inlet of the first booster pump (8) through a second throttle valve (23).

7. A multi-energy combined production energy storage system coupling compressed air and water according to claim 6, characterized in that, A cooler (22) is arranged between the medium-temperature water tank (21) and the second throttle valve (23). The first inlet of the cooler (22) is connected to the outlet of the medium-temperature water tank (21). The first outlet of the medium-temperature water tank (21) is connected to the second throttle valve (23). The inlet of the air compressor (2) is connected to the first outlet of the preheater (1). The first inlet of the preheater (1) is connected to the atmosphere. The second inlet of the preheater (1) is connected to the second outlet of the cooler (22). The second outlet of the preheater (1) is connected to the second inlet of the cooler (22). The third inlet of the preheater (1) is connected to a waste heat source.

8. A method for a multi-energy combined production energy storage system coupling compressed air and water, characterized in that, Adopting the system as described in claim 5, comprising the following steps: Normal temperature and pressure air enters the preheater (1) and is preheated to become medium-temperature and pressure air. The medium-temperature and pressure air enters the air compressor (2) and is compressed to become high-temperature and high-pressure air. The high-temperature and high-pressure air sequentially enters the first heat exchanger (3), the second heat exchanger (4), and the air turbine (5). Low-temperature molten salt enters the first heat exchanger (3) for heat exchange to become high-temperature molten salt and is stored in the high-temperature molten salt tank (11). Low-temperature water is pressurized by the first booster pump (8) and then enters the second heat exchanger (4) for heat exchange to become medium-high temperature and high-pressure water and is stored in the high-temperature water tank (9) to complete energy storage. The high-temperature and high-pressure air expands and does work in the air turbine (5) after two heat exchanges and becomes low-temperature and normal-pressure air. At the same time, the power generated by the expansion and work is transmitted to the air compressor (2); Medium and high temperature and high pressure water enters the flash tank (12) for flashing, generating medium temperature saturated steam and medium temperature saturated water. The medium temperature saturated steam enters the third heat exchanger (13) to exchange heat with high temperature molten salt for temperature rise, and then enters the high pressure cylinder (14) of the steam turbine to expand and do work to drive the generator to generate electricity; The steam that has expanded and done work in the high pressure cylinder (14) of the steam turbine enters the reheater (17), exchanges heat with the medium temperature saturated water generated by the flash tank (12) for temperature rise, and then enters the low pressure cylinder (18) of the steam turbine to expand and do work to drive the generator to generate electricity. At the same time, when providing cooling, the low temperature normal pressure air after expanding and doing work by the air turbine (5) enters the refrigeration heat exchanger (6) to provide cooling to users; When heating, the steam that has expanded and done work in the high pressure cylinder (14) of the steam turbine and the medium temperature saturated water in the flash tank (12) enter the heating heat exchanger (15) to provide heating to users.

9. A method for a multi-energy combined production energy storage system with compressed air and water coupling, characterized in that, The temperature of the medium temperature normal pressure air is 140°C to 160°C, the pressure is 101.3 kPa; the temperature of the high temperature and high pressure air is 300°C to 350°C, the pressure is 300 kPa to 400 kPa; the temperature of the low temperature normal pressure air is -15°C to 10°C, the pressure is 101.3 kPa; the temperature of the low temperature water is 25°C to 30°C; the temperature of the medium and high temperature and high pressure water is 210°C to 250°C, the pressure is 3.5 MPa to 4.0 MPa; the temperature of the low temperature molten salt is 200°C to 240°C; the temperature of the high temperature molten salt is 290°C to 340°C; the temperature of the medium temperature saturated steam is 190°C to 210°C, the pressure is 1.3 MPa to 1.9 MPa; the temperature of the medium temperature saturated water is 190°C to 210°C, the pressure is 1.3 MPa to 1.9 MPa; the temperature of the high temperature medium pressure steam is 280°C to 330°C, the pressure is 1.3 MPa to 1.9 MPa; the temperature of the medium temperature normal pressure steam is 100°C to 110°C, the pressure is 101.3 kPa; the temperature of the medium temperature water is 190°C to 210°C.

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