Multi-working-condition adaptive compressed air energy storage system and operation method thereof

Abstract

The application discloses a compressed air energy storage system suitable for multiple working conditions and a running method thereof, comprising an isothermal compression system, a gas storage system, an expansion work system, a molten salt heat storage system and an air-flue gas heat exchange system; during a low electricity consumption valley, low-valley electricity is utilized to drive the isothermal compression system to compress air, and the compressed air is stored in an underground salt cavern; during an electricity consumption peak period, compressed air in the salt cavern is released through an electromagnetic valve, and is divided into two work routes: one route is provided with supplementary combustion, and the compressed air is expanded to work twice; the other route is not provided with supplementary combustion, and the compressed air is expanded to work once. The application stores compressed air by utilizing low-valley electricity, and releases energy to generate electricity during the electricity consumption peak period. The system is flexible and efficient, is an effective supplement to an existing energy storage system, and has high practical value.

Description

Technical Field

[0001] This invention relates to an energy storage system, specifically to a multi-condition adaptable compressed air energy storage system and its operation method. Background Technology

[0002] Traditional energy storage technologies include pumped hydro storage, electrochemical energy storage, flywheel energy storage, and molten salt thermal energy storage. However, due to factors such as energy storage density, geographical location, and lifespan, new energy storage technologies need to be developed to fill the gap in total energy storage capacity. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention aims to provide a multi-condition adaptable compressed air energy storage system and its operation method. The system uses off-peak electricity to store air and releases energy to generate electricity during peak electricity demand, so as to achieve the purpose of clean and efficient energy utilization.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A multi-condition adaptable compressed air energy storage system, the system is divided into an energy storage section and an energy release section. The energy storage section includes an isothermal compression system and an air storage system, and the energy release section includes an expansion work system, a molten salt thermal storage system and an air-flue gas heat exchange system.

[0006] The isothermal compression system includes an air compressor 1, a first compression well 2, a second compression well 3, a water pump 4, and a water storage tank 5. The outlet of the air compressor 1 is connected to the air inlets of the first compression well 2 and the second compression well 3. The air outlets of the first compression well 2 and the second compression well 3 are connected to the inlet of the first solenoid valve 23. The cooling water inlets of the first compression well 2 and the second compression well 3 are connected to the cooling water outlet of the water storage tank 5 through the water pump 4. The cooling water outlets of the first compression well 2 and the second compression well 3 are connected to the cooling water return inlet of the water storage tank 5. One of the first compression well 2 and the second compression well 3 is a standby compression well.

[0007] The gas storage system includes a salt cavern 6 and a first solenoid valve 23 and a second solenoid valve 24 inside the salt cavern 6. The air inlet and outlet of the salt cavern 6 are respectively connected to the outlet of the first solenoid valve 23 and the inlet of the second solenoid valve 24.

[0008] The energy release section includes a low-temperature high-pressure air expander 7, a first generator 8, an air-cooled heat exchanger 9, a low-temperature air-flue gas heat exchanger 10, a high-temperature air-flue gas heat exchanger 11, a combustion chamber 12, a high-temperature flue gas expander 13, a second generator 14, a flue gas-molten salt heat exchanger 15, a low-temperature molten salt storage tank 16, a high-temperature molten salt storage tank 17, a high-pressure air expander 18, a third generator 19, an air-molten salt heat exchanger 20, an air-flue gas heat exchanger 21, a flue gas mixer 22, a third solenoid valve 25, a fourth solenoid valve 26, a fifth solenoid valve 27, and a sixth solenoid valve 28. The specific connection method of the energy release section is as follows: the compressed air at the outlet of the salt cavern 6 is divided into two paths, one of which passes through the second solenoid valve inside the salt cavern 6. Solenoid valve 24 is connected to the inlet of the third solenoid valve 25, and another path is connected to the inlet of solenoid valve V426 through the second solenoid valve 24 inside the salt cavern SC6; the outlet of the third solenoid valve 25 is connected to the inlet of the low-temperature high-pressure air expander 7, which drives the first generator 8; the outlet of the low-temperature high-pressure air expander 7 is connected to the high-temperature fluid inlet of the air-cooled heat exchanger 9; the high-temperature fluid outlet of the air-cooled heat exchanger 9 is connected to the low-temperature fluid inlet of the low-temperature air-flue gas heat exchanger 10; the low-temperature fluid outlet of the low-temperature air-flue gas heat exchanger 10 is connected to the low-temperature fluid inlet of the high-temperature air-flue gas heat exchanger 11; the low-temperature fluid outlet of the high-temperature air-flue gas heat exchanger 11 is connected to the inlet of the combustion chamber 12; and the outlet of the combustion chamber 12 is connected to the high-temperature flue gas... The inlet of expander 13 is connected to the high-temperature flue gas expander 13, which drives the second generator 14. The outlet of high-temperature flue gas expander 13 is connected to the flue gas inlet of flue gas-molten salt heat exchanger 15. The flue gas outlet of flue gas-molten salt heat exchanger 15 is connected to the inlets of the fifth solenoid valve 27 and the sixth solenoid valve 28. The molten salt inlet and outlet of flue gas-molten salt heat exchanger 15 are connected to the outlet of low-temperature molten salt storage tank S116 and the inlet of high-temperature molten salt storage tank S217, respectively. The outlet of solenoid valve V527 is connected to the high-temperature fluid inlet of high-temperature air-flue gas heat exchanger H311. The high-temperature fluid outlet of high-temperature air-flue gas heat exchanger H311 is connected to the high-temperature fluid inlet of low-temperature air-flue gas heat exchanger 10. The outlet is connected to the flue gas inlet of the flue gas mixer 22; the outlet of the fourth solenoid valve 26 is connected to the low-temperature fluid inlet of the air-flue gas heat exchanger 21; the high-temperature fluid inlet of the air-flue gas heat exchanger 21 is connected to the outlet of the sixth solenoid valve 28; the high-temperature fluid outlet of the air-flue gas heat exchanger 21 is connected to the flue gas inlet of the flue gas mixer 22; the low-temperature fluid outlet of the air-flue gas heat exchanger 21 is connected to the air inlet of the air-molten salt heat exchanger 20; the molten salt inlet and outlet of the air-molten salt heat exchanger 20 are respectively connected to the outlet of the high-temperature molten salt storage tank 17 and the inlet of the low-temperature molten salt storage tank 16; the air outlet of the air-molten salt heat exchanger 20 is connected to the inlet of the high-pressure air expander 18; and the high-pressure air expander 18 drives the third generator 19.

[0009] The low-temperature high-pressure air expander 7, the first generator 8, the combustion chamber 12, the high-temperature flue gas expander 13, the second generator 14, the high-pressure air expander 18, and the third generator 19 together form the expansion and power-generating system.

[0010] The flue gas-molten salt heat exchanger 15, the low-temperature molten salt storage tank 16, the high-temperature molten salt storage tank 17, and the air-molten salt heat exchanger 20 together constitute the molten salt heat storage system.

[0011] The air-cooled heat exchanger 9, the low-temperature air-flue gas heat exchanger 10, the high-temperature air-flue gas heat exchanger 11, the fifth solenoid valve 27, the sixth solenoid valve 28, the air-flue gas heat exchanger 21, and the flue gas mixer 22 together constitute the air-flue gas heat exchange system.

[0012] The operation method of the multi-condition adaptable compressed air energy storage system is as follows: During off-peak electricity demand, the backup second compression well 3 is not working, while the first compression well 2 is working. The air compressor 1 uses surplus electricity to compress air, and the water storage tank 5 uses the water pump 4 to supply room temperature water to the first compression well 2. To ensure that the compression process is isothermal, the compressed air needs to be cooled by water in the first compression well 2 before entering the salt cavern 6 for storage. The first solenoid valve 23 connected to the first compression well 2 in the salt cavern 6 is closed, and the second solenoid valve 24 is open, and the resulting compressed air is stored in the salt cavern 6. When the compressed air in the salt cavern 6 is full, the first solenoid valve 23 is open, and the compressed air is stored at a constant temperature in the salt cavern 6. During peak electricity demand, the second solenoid valve 24 is closed, the salt cavern is released, and the compressed air expands and does work in the system after the salt cavern 6. If the first compression well 2 fails, the backup second compression well 3 is working, and the first compression well 2 is not working. The remaining parts of the system follow the same operating procedure.

[0013] During peak electricity consumption, the second solenoid valve 24 closes, releasing air from the salt cavern. Compressed air expands and performs work in the system after the salt cavern 6. The third solenoid valve 25 and the fourth solenoid valve 26 close, splitting the compressed air into two paths. One path enters the low-temperature high-pressure expander 7 to expand and perform work, driving the first generator 8 to generate electricity. After being heated in stages by the air-cooled heat exchanger 9, the low-temperature air-flue gas heat exchanger 10, and the high-temperature air-flue gas heat exchanger 11, it enters the combustion chamber 12 for supplemental combustion and then enters the high-temperature flue gas expander 13 to expand and perform work, driving the second generator 14 to generate electricity. The flue gas after expanding and performing work in the high-temperature flue gas expander 13, as well as the low-temperature molten salt in the low-temperature molten salt storage tank 16, also simultaneously enter the flue gas-molten salt heat exchanger. 15. The flue gas releases heat and the molten salt absorbs heat. Then, the high-temperature molten salt after absorbing heat enters the high-temperature molten salt storage tank 17 for storage. The flue gas after releasing heat is divided into two paths. One path flows through the high-temperature air-flue gas heat exchanger 11, the low-temperature air-flue gas heat exchanger 10, and the flue gas mixer 22. The other path flows through the air-flue gas heat exchanger 21 and the flue gas mixer 22, respectively, to heat two streams of compressed air at lower temperatures. Finally, the two streams of flue gas are discharged into the atmosphere from the flue gas mixer 22. The other stream of compressed air is heated by the air-flue gas heat exchanger 21 and the air-molten salt heat exchanger 20 and then enters the high-pressure air expander 18 to expand and do work, driving the third generator 19 to generate electricity. The expanded air is then discharged into the atmosphere.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. This invention provides a multi-condition adaptable compressed air energy storage system and its operation method. The system combines a novel energy storage method, uses off-peak electricity to store compressed air, and releases energy to generate electricity during peak electricity consumption periods. The system is flexible and efficient, and is an effective supplement to existing energy storage systems, with high practical value.

[0016] 2. Since the system of the present invention has a low-temperature high-pressure air expander 7 and an air-cooled heat exchanger 9, the system can reduce the temperature of the air entering the air compressor 1 while generating electricity using high-pressure low-temperature air, thereby increasing the power consumption of the system during energy storage and saving costs.

[0017] 3. Since the system of the present invention has a low-temperature air-flue gas heat exchanger 10 and a high-temperature air-flue gas heat exchanger 11, the system can not only increase the temperature of the compressed air entering the combustion chamber 12 and reduce the amount of fuel, but also achieve the cascade utilization of the high-temperature flue gas energy discharged from the high-temperature flue gas expander 13, which is environmentally friendly and energy-saving.

[0018] 4. Because the system of the present invention has a combustion chamber 12, the temperature of the flue gas entering the high-temperature flue gas expander 13 is further increased, which greatly improves the power generation efficiency of the high-temperature flue gas expander 13.

[0019] 5. Because the system of the present invention includes a flue gas-molten salt heat exchanger 15, a low temperature molten salt storage tank 16, a high temperature molten salt storage tank 17, and an air-molten salt heat exchanger 20, the system can flexibly adjust the system output according to the grid demand, which can effectively improve the flexible peak-shaving capability of the existing power system. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a multi-condition adaptable compressed air energy storage system according to the present invention. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0022] Traditional energy storage technologies include pumped hydro storage, electrochemical energy storage, flywheel energy storage, and molten salt thermal energy storage. However, due to factors such as energy storage density, geographical location, and service life, new energy storage technologies need to be developed to fill the gap in total energy storage capacity. Compressed air energy storage systems have advantages such as relatively high energy storage density, environmental friendliness, efficient and flexible operation, and low initial investment, making them a worthwhile area of ​​research in energy storage.

[0023] like Figure 1 As shown, this invention discloses a multi-condition adaptable compressed air energy storage system. The system comprises an air compressor 1, a first compression well 2, a second compression well 3, a water pump 4, a water storage tank 5, a salt cavern 6, a low-temperature high-pressure air expander 7, a first generator 8, an air-cooled heat exchanger 9, a low-temperature air-flue gas heat exchanger 10, a high-temperature air-flue gas heat exchanger 11, a combustion chamber 12, a high-temperature flue gas expander 13, a second generator 14, a flue gas-molten salt heat exchanger 15, a low-temperature molten salt storage tank 16, a high-temperature molten salt storage tank 17, a high-pressure air expander 18, a third generator 19, an air-molten salt heat exchanger 20, an air-flue gas heat exchanger 21, a flue gas mixer 22, a first solenoid valve 23, a second solenoid valve 24, a third solenoid valve 25, a fourth solenoid valve 26, a fifth solenoid valve 27, and a sixth solenoid valve 28. These components together form an isothermal compression system, an air storage system, an expansion and work system, a molten salt heat storage system, and an air-flue gas heat exchange system.

[0024] The system's workflow is as follows: During off-peak hours, the backup second compression well 3 is not in operation, while the first compression well 2 is in operation. The air compressor 1 uses surplus electricity to compress air, and the water storage tank 5 uses the water pump 4 to supply room temperature water to the first compression well 2. To ensure that the compression process is isothermal, the compressed air needs to be cooled by water in the first compression well 2 before entering the salt cavern 6 for storage. The first solenoid valve 23 connected to the first compression well 2 in the salt cavern 6 is closed, and the second solenoid valve 24 is open, so the resulting compressed air is stored in the salt cavern 6. When the salt cavern 6 is full of compressed air, the first solenoid valve 23 is opened, and the compressed air is stored at a constant temperature in the salt cavern 6. During peak hours, the second solenoid valve 24 is closed, the salt cavern is released, and the compressed air expands and does work in the system after the salt cavern 6. If the first compression well 2 fails, the backup second compression well 3 is in operation, and the first compression well 2 is not in operation. The workflow of the rest of the system is the same.

[0025] During peak electricity consumption, the second solenoid valve 24 closes, releasing air from the salt cavern. Compressed air expands and performs work in the system after the salt cavern 6. The first solenoid valve 25 and the fourth solenoid valve 26 close, splitting the compressed air into two paths. One path enters the low-temperature high-pressure expander 7 to expand and perform work, driving the first generator 8 to generate electricity. After being heated step-by-step by the air-cooled heat exchanger 9, the low-temperature air-flue gas heat exchanger 10, and the high-temperature air-flue gas heat exchanger 11, the compressed air enters the combustion chamber 12 for supplementary combustion and then enters the high-temperature flue gas expander 13 to expand and perform work, driving the second generator 14 to generate electricity. The flue gas after expansion and work done by the high-temperature flue gas expander 13 and the low-temperature molten salt in the low-temperature molten salt storage tank 16 also enter the flue gas-molten salt heat exchanger 15 at the same time. The flue gas releases heat and the molten salt absorbs heat. Then, the high-temperature molten salt that has absorbed heat enters the high-temperature molten salt storage tank for storage. The flue gas that has released heat is divided into two paths. One path flows through the high-temperature air-flue gas heat exchanger 11, the low-temperature air-flue gas heat exchanger 10 and the flue gas mixer 22. The other path flows through the air-flue gas heat exchanger 21 and the flue gas mixer 22, respectively, to heat two streams of compressed air at lower temperatures. Finally, the two streams of flue gas are discharged into the atmosphere in the flue gas mixer 22.

[0026] Another path of compressed air is heated by the air-flue gas heat exchanger 21 and the air-molten salt heat exchanger 20 before entering the high-pressure air expander 18 to expand and do work, driving the third generator 19 to generate electricity. The expanded air is then discharged into the atmosphere.

[0027] The above is the complete workflow of the multi-condition adaptable compressed air energy storage system and its operation method of the present invention.

Claims

1. A multi-condition adaptable compressed air energy storage system, characterized in that: The system is divided into an energy storage section and an energy release section. The energy storage section includes an isothermal compression system and a gas storage system, while the energy release section includes an expansion work system, a molten salt thermal storage system, and an air-flue gas heat exchange system. The isothermal compression system includes an air compressor (1), a first compression well (2), a second compression well (3), a water pump (4), and a water storage tank (5). The outlet of the air compressor (1) is connected to the air inlets of the first compression well (2) and the second compression well (3). The air outlets of the first compression well (2) and the second compression well (3) are connected to the inlet of the first solenoid valve (23). The cooling water inlets of the first compression well (2) and the second compression well (3) are connected to the cooling water outlet of the water storage tank (5) via the water pump (4). The cooling water outlets of the first compression well (2) and the second compression well (3) are connected to the cooling water return inlet of the water storage tank (5). One of the first compression well (2) and the second compression well (3) is a spare compression well. The gas storage system includes a salt cavern (6) and a first solenoid valve (23) and a second solenoid valve (24) inside the salt cavern (6). The air inlet and outlet of the salt cavern (6) are respectively connected to the outlet of the first solenoid valve (23) and the inlet of the second solenoid valve (24). The energy release section includes a low-temperature high-pressure air expander (7), a first generator (8), an air-cooled heat exchanger (9), a low-temperature air-flue gas heat exchanger (10), a high-temperature air-flue gas heat exchanger (11), a combustion chamber (12), a high-temperature flue gas expander (13), a second generator (14), a flue gas-molten salt heat exchanger (15), a low-temperature molten salt storage tank (16), a high-temperature molten salt storage tank (17), a high-pressure air expander (18), a third generator (19), an air-molten salt heat exchanger (20), an air-flue gas heat exchanger (21), a flue gas mixer (22), a third solenoid valve (25), and a fourth solenoid valve (26). 26) The specific connection method of the energy release part of the fifth solenoid valve (27) and the sixth solenoid valve (28) is as follows: The compressed air at the outlet of the salt cavern (6) is divided into two paths. One path is connected to the inlet of the third solenoid valve (25) through the second solenoid valve (24) in the salt cavern (6), and the other path is connected to the inlet of the solenoid valve V4 (26) through the second solenoid valve (24) in the salt cavern SC (6). The outlet of the third solenoid valve (25) is connected to the inlet of the low temperature high pressure air expander (7). The low temperature high pressure air expander (7) drives the first generator (8). The outlet of the low temperature high pressure air expander (7) is connected to the high temperature fluid inlet of the air-cooled heat exchanger (9). The outlet of the air-cooled heat exchanger (9) is connected to the inlet of the low-temperature air-flue gas heat exchanger (10). The outlet of the low-temperature air-flue gas heat exchanger (10) is connected to the inlet of the high-temperature air-flue gas heat exchanger (11). The outlet of the high-temperature air-flue gas heat exchanger (11) is connected to the inlet of the combustion chamber (12). The outlet of the combustion chamber (12) is connected to the inlet of the high-temperature flue gas expander (13). The high-temperature flue gas expander (13) drives the second generator (14). The outlet of the high-temperature flue gas expander (13) is connected to the flue gas inlet of the flue gas-molten salt heat exchanger (15). The flue gas outlet of heat exchanger (15) is connected to the inlet of the fifth solenoid valve (27) and the sixth solenoid valve (28). The molten salt inlet and outlet of flue gas-molten salt heat exchanger (15) are connected to the outlet of low temperature molten salt storage tank S1 (16) and the inlet of high temperature molten salt storage tank S2 (17), respectively. The outlet of solenoid valve V5 (27) is connected to the high temperature fluid inlet of high temperature air-flue gas heat exchanger (11). The high temperature fluid outlet of high temperature air-flue gas heat exchanger (11) is connected to the high temperature fluid inlet of low temperature air-flue gas heat exchanger (10). The high temperature fluid outlet of low temperature air-flue gas heat exchanger (10) is connected to the flue gas inlet of flue gas mixer (22).The outlet of the fourth solenoid valve (26) is connected to the low-temperature fluid inlet of the air-fluid heat exchanger (21), the high-temperature fluid inlet of the air-fluid heat exchanger (21) is connected to the outlet of the sixth solenoid valve (28), the high-temperature fluid outlet of the air-fluid heat exchanger (21) is connected to the flue gas inlet of the flue gas mixer (22), the low-temperature fluid outlet of the air-fluid heat exchanger (21) is connected to the air inlet of the air-molten salt heat exchanger (20), the molten salt inlet and outlet of the air-molten salt heat exchanger (20) are connected to the outlet of the high-temperature molten salt storage tank (17) and the inlet of the low-temperature molten salt storage tank (16) respectively, and the air outlet of the air-molten salt heat exchanger (20) is connected to the inlet of the high-pressure air expander (18). The high-pressure air expander (18) drives the third generator (19). Among them, the low temperature high pressure air expander (7), the first generator (8), the combustion chamber (12), the high temperature flue gas expander (13), the second generator (14), the high pressure air expander (18) and the third generator (19) together form the expansion power system; Among them, the flue gas-molten salt heat exchanger (15), the low temperature molten salt storage tank (16), the high temperature molten salt storage tank (17) and the air-molten salt heat exchanger (20) together form a molten salt heat storage system; The air-cooled heat exchanger (9), the low-temperature air-flue gas heat exchanger (10), the high-temperature air-flue gas heat exchanger (11), the fifth solenoid valve (27), the sixth solenoid valve (28), the air-flue gas heat exchanger (21), and the flue gas mixer (22) together form the air-flue gas heat exchange system.

2. The operation method of a multi-condition adaptable compressed air energy storage system as described in claim 1, characterized in that: During periods of low electricity demand, the backup second compression well (3) is not in operation, while the first compression well (2) is in operation. The air compressor (1) uses the surplus electricity to compress air, and the water storage tank (5) uses the water pump (4) to supply room temperature water to the first compression well (2). To ensure that the compression process is isothermal, the compressed air needs to be cooled by water in the first compression well (2) before entering the salt cavern (6) for storage. The first solenoid valve (23) connected to the first compression well (2) in the salt cavern (6) is closed, and the second solenoid valve (24) is open. The resulting compressed air is stored in the salt cavern (6). When the compressed air in the salt cavern (6) is full, the first solenoid valve (23) is open, and the compressed air is stored at a constant temperature in the salt cavern (6). During periods of high electricity demand, the second solenoid valve (24) is closed, the salt cavern is released, and the compressed air expands and does work in the system after the salt cavern (6). If the first compression well (2) fails, the backup second compression well (3) is in operation, while the first compression well (2) is not in operation. The workflow of the rest of the system is the same. During peak electricity consumption, the second solenoid valve (24) closes, the salt cavern releases gas, and the compressed air expands and does work in the system after the salt cavern (6); the third solenoid valve (25) and the fourth solenoid valve (26) close, and the compressed air is divided into two paths. One path enters the low-temperature high-pressure air expander (7) to expand and do work, driving the first generator (8) to generate electricity. After being heated step by step by the air-cooled heat exchanger (9), the low-temperature air-flue gas heat exchanger (10), and the high-temperature air-flue gas heat exchanger (11), it enters the combustion chamber (12) for supplementary combustion and then enters the high-temperature flue gas expander (13) to expand and do work, driving the second generator (14) to generate electricity; the flue gas after expanding and doing work in the high-temperature flue gas expander (13) and the low-temperature molten salt in the low-temperature molten salt storage tank (16) also enter the flue gas-molten salt system at the same time. In the heat exchanger (15), the flue gas releases heat and the molten salt absorbs heat. Then, the high-temperature molten salt after absorbing heat enters the high-temperature molten salt storage tank (17) for storage. The flue gas after releasing heat is divided into two paths. One path flows through the high-temperature air-flue gas heat exchanger (11), the low-temperature air-flue gas heat exchanger (10), and the flue gas mixer (22). The other path flows through the air-flue gas heat exchanger (21) and the flue gas mixer (22), respectively used to heat two streams of compressed air at lower temperatures. Finally, the two streams of flue gas are discharged into the atmosphere from the flue gas mixer (22). The other stream of compressed air is heated by the air-flue gas heat exchanger (21) and the air-molten salt heat exchanger (20) and then enters the high-pressure air expander (18) to expand and do work, driving the third generator (19) to generate electricity. The expanded air is discharged into the atmosphere.

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