A compressed gas energy storage system with constant pressure gas storage

Abstract

The application discloses a compressed gas energy storage system with constant pressure, which comprises a high-pressure gas storage unit, a pressure transmission unit, a compressor pipeline, a turbine pipeline, an energy storage loop and a plurality of low-pressure gas storage units. One end of each low-pressure gas storage unit is connected with one end of the high-pressure gas storage unit through the pressure transmission unit, the other end of each low-pressure gas storage unit is connected with one end of the turbine pipeline and one end of the compressor pipeline, the other end of the high-pressure gas storage unit is connected with the other end of the turbine pipeline and the other end of the compressor pipeline, and the compressor pipeline and the turbine pipeline are connected through the energy storage loop. The system can realize constant pressure in the process of gas charging and discharging.

Description

Technical Field

[0001] This invention belongs to the field of energy storage technology and relates to a compressed gas energy storage system with constant pressure gas storage. Background Technology

[0002] Compressed gas energy storage (CGS) is a technology that stores energy by converting electricity into the compressive potential energy of a gas, and then releases the compressed gas to generate electricity when needed. This technology utilizes the elastic properties of gases and the energy conversion during compression and expansion to achieve energy storage and recovery. CGS technology enables large-scale electricity storage and offers advantages such as flexibility and environmental friendliness. With the rapid development of renewable energy and the increasing demand for energy storage, CGS technology has broad application prospects.

[0003] Compressed gas energy storage typically involves storing compressed gas in a space with a fixed volume, such as underground salt caverns, gas tanks, and pipelines. When the high-pressure gas is released, the mass of the gas in the storage space decreases, and since the volume remains constant, the pressure of the stored gas gradually decreases. This pressure reduction decreases the gas's ability to perform work. Furthermore, during the filling process, the gas pressure in the storage space gradually increases, requiring a higher discharge pressure from the compressor. This causes the compressor to deviate from its optimal operating point, further reducing system efficiency. This contradiction between the gas's compression-expansion characteristics and the constant storage volume is one of the main factors contributing to the low efficiency of compressed gas energy storage technology.

[0004] If compressed gas energy storage technology can maintain a constant pressure in the storage space during inflation and deflation, the cycle efficiency of compressed gas energy storage will significantly increase to over 74%, greatly enhancing its competitiveness. Some scholars have proposed using flexible gas storage bladders placed at a certain depth underwater, utilizing water pressure to maintain a constant pressure during inflation and deflation. However, this approach has high requirements for geological and hydrological conditions; for example, storing 7.5 MPa and 25 MPa gases would require placing the gas storage bladders at depths of approximately 750 m and 2500 m underwater, respectively, raising questions about the feasibility of this approach. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a constant-pressure compressed gas energy storage system that can achieve constant pressure during the filling and defilling processes.

[0006] To achieve the above objectives, the present invention discloses a constant-pressure compressed gas energy storage system, comprising a high-pressure gas storage unit, a pressure transmission unit, a compressor pipeline, a turbine pipeline, an energy storage circuit, and several low-pressure gas storage units.

[0007] One end of each low-pressure gas storage unit is connected to one end of the high-pressure gas storage unit via a pressure transmission unit. The other end of each low-pressure gas storage unit is connected to one end of the turbine pipeline and one end of the compressor pipeline. The other end of the high-pressure gas storage unit is connected to the other end of the turbine pipeline and the other end of the compressor pipeline. The compressor pipeline and the turbine pipeline are connected through an energy storage circuit.

[0008] The pressure transmission unit includes a pressure transmission pipe and a pressure transmission fluid disposed within the pressure transmission pipe.

[0009] The low-pressure gas storage unit includes a low-pressure gas storage chamber and a low-pressure piston connecting rod;

[0010] The low-pressure gas storage chamber is equipped with a low-pressure piston and a low-pressure air bag. The low-pressure air bag is located on one side of the low-pressure piston. One end of the low-pressure piston connecting rod is connected to the other end of the low-pressure piston. The other end of the low-pressure piston connecting rod is inserted into the pressure transmission pipe along one end of the pressure transmission pipe and then a low-pressure transmission piston is installed. The opening on the low-pressure air bag is connected to the turbine pipeline and the compressor pipeline through the low-pressure gas storage chamber valve.

[0011] The high-pressure gas storage unit includes a high-pressure gas storage chamber and a high-pressure piston connecting rod.

[0012] The high-pressure gas storage chamber is equipped with a high-pressure piston and a high-pressure gas bag. The high-pressure gas bag is located on one side of the high-pressure piston. One end of the high-pressure piston connecting rod is connected to the other side of the high-pressure piston. The other end of the high-pressure piston connecting rod is inserted into the pressure transmission pipe along the other end of the pressure transmission pipe and then a high-pressure transmission piston is installed. The opening on the high-pressure gas bag is connected to the turbine pipeline and the compressor pipeline through the high-pressure gas storage chamber valve.

[0013] The turbine pipeline includes a turbine outlet valve, a cooler, a turbine, a second heat exchanger, and a turbine inlet valve;

[0014] The opening on the low-pressure airbag is connected to the opening on the high-pressure airbag via the low-pressure air storage chamber valve, the turbine outlet valve, the cooler, the turbine, the cold side of the second heat exchanger, the turbine inlet valve, and the high-pressure air storage chamber valve.

[0015] The turbine pipeline includes a compressor inlet valve, a compressor, a first heat exchanger, and a compressor outlet valve;

[0016] The opening on the low-pressure airbag is connected in sequence to the opening on the high-pressure airbag via the low-pressure air storage chamber valve, the compressor inlet valve, the compressor, the hot side of the first heat exchanger, the compressor outlet valve, and the high-pressure air storage chamber valve.

[0017] The outlet of the cold storage tank is connected to the inlet of the hot storage tank via the cold side of the first heat exchanger, and the outlet of the hot storage tank is connected to the inlet of the cold storage tank via the hot side of the second heat exchanger.

[0018] Both the high-pressure and low-pressure airbags are flexible airbags.

[0019] The piston surface area of ​​the low-pressure piston is S times that of the high-pressure piston, corresponding to the gas pressure in the high-pressure airbag being S times that of the low-pressure airbag.

[0020] The sum of the piston surface areas of the high-pressure drive pistons is equal to the sum of the piston surface areas of the low-pressure drive pistons.

[0021] The present invention has the following beneficial effects:

[0022] In specific operation, the constant-pressure compressed gas energy storage system of the present invention connects the high-pressure gas bladder and the low-pressure gas bladder through a piston mechanism and a transmission fluid. The pistons of the high-pressure gas bladder and the low-pressure gas bladder have different cross-sectional areas to realize the linkage between the high-pressure gas storage space and the low-pressure gas storage space, thereby achieving constant pressure during the inflation and deflation process, reducing pressure loss during the inflation and deflation process, and thus greatly improving the cycle efficiency of compressed gas energy storage.

[0023] Furthermore, the present invention can adjust the ratio of gas pressure in the high-pressure airbag and the low-pressure airbag by adjusting the ratio of the piston surface area of ​​the low-pressure piston to the piston surface area of ​​the high-pressure piston, which is convenient and flexible to operate. Attached Figure Description

[0024] Figure 1 This is a structural diagram of the present invention.

[0025] Among them, 1 is the high-pressure airbag, 2 is the high-pressure piston, 3 is the high-pressure piston connecting rod, 4 is the high-pressure air storage chamber, 5 is the high-pressure transmission piston, 6 is the pressure transmission pipe, 7 is the pressure transmission fluid, 8 is the low-pressure transmission piston, 9 is the low-pressure piston connecting rod, 10 is the low-pressure piston, 11 is the low-pressure air storage chamber, 12 is the low-pressure airbag, 13 is the low-pressure air storage chamber valve, 14 is the compressor inlet valve, 15 is the compressor, 16 is the first heat exchanger, 17 is the compressor outlet valve, 18 is the high-pressure air storage chamber valve, 19 is the cold storage tank, 20 is the heat storage tank, 21 is the turbine inlet valve, 22 is the second heat exchanger, 23 is the turbine, 24 is the cooler, and 25 is the turbine outlet valve. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0027] The accompanying drawings show structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not drawn to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] refer to Figure 1 The constant-pressure compressed gas energy storage system of the present invention includes a high-pressure gas storage unit, a pressure transmission unit, a compressor pipeline, a turbine pipeline, an energy storage circuit, and several low-pressure gas storage units; one end of each low-pressure gas storage unit is connected to one end of the high-pressure gas storage unit via the pressure transmission unit, and the other end of each low-pressure gas storage unit is connected to one end of the turbine pipeline and one end of the compressor pipeline, and the other end of the high-pressure gas storage unit is connected to the other end of the turbine pipeline and the other end of the compressor pipeline, and the compressor pipeline and the turbine pipeline are connected through the energy storage circuit.

[0029] The high-pressure gas storage unit includes a high-pressure gas bag 1, a high-pressure piston 2, a high-pressure piston connecting rod 3, a high-pressure gas storage chamber 4, a high-pressure transmission piston 5, and a high-pressure gas storage chamber valve 18.

[0030] The low-pressure gas storage unit includes a low-pressure transmission piston 8, a low-pressure piston connecting rod 9, a low-pressure piston 10, a low-pressure gas storage chamber 11, a low-pressure air bladder 12, and a low-pressure gas storage chamber valve 13.

[0031] The pressure transmission unit includes a pressure transmission pipe 6 and a pressure transmission fluid 7.

[0032] The compressor pipeline includes a compressor inlet valve 14, a compressor 15, a first heat exchanger 16, and a compressor outlet valve 17.

[0033] The turbine pipeline includes a turbine inlet valve 21, a second heat exchanger 22, a turbine 23, a cooler 24, and a turbine outlet valve 25.

[0034] The energy storage circuit includes a cold storage tank 19 and a heat storage tank 20.

[0035] The low-pressure gas storage chamber 11 is equipped with a low-pressure piston 10 and a low-pressure airbag 12. The low-pressure airbag 12 is located on one side of the low-pressure piston 10. One end of the low-pressure piston connecting rod 9 is connected to the other end of the low-pressure piston 10. The other end of the low-pressure piston connecting rod 9 is inserted into the pressure transmission pipe 6 along one end and then a low-pressure transmission piston 8 is installed. The high-pressure gas storage chamber 4 is equipped with a high-pressure piston 2 and a high-pressure airbag 1. The high-pressure airbag 1 is located on one side of the high-pressure piston 2. One end of the high-pressure piston connecting rod 3 is connected to the other side of the high-pressure piston 2. The other end of the high-pressure piston connecting rod 3 is inserted into the pressure transmission pipe 6 along the other end and then a high-pressure transmission piston 5 is installed. The pressure transmission pipe 6 is equipped with a pressure transmission fluid 7, which is located between the high-pressure transmission piston 5 and the low-pressure transmission piston 8.

[0036] The opening on the low-pressure airbag 12 is divided into two paths after passing through the low-pressure air storage chamber valve 13. One path is connected to one end of the high-pressure air storage chamber valve 18 via the compressor inlet valve 14, compressor 15, the hot side of the first heat exchanger 16 and the compressor outlet valve 17. The other path is connected to one end of the high-pressure air storage chamber valve 18 via the turbine outlet valve 25, cooler 24, turbine 23, the cold side of the second heat exchanger 22 and the turbine inlet valve 21. The other end of the high-pressure air storage chamber valve 18 is connected to the opening on the high-pressure airbag 1.

[0037] The outlet of the cold storage tank 19 is connected to the inlet of the heat storage tank 20 via the cold side of the first heat exchanger 16, and the outlet of the heat storage tank 20 is connected to the inlet of the cold storage tank 19 via the hot side of the second heat exchanger 22.

[0038] In this embodiment, the high-pressure airbag 1 and the low-pressure airbag 12 are flexible airbags, and the pressure of the gas is mainly borne by the gas storage chamber.

[0039] In this embodiment, the piston surface area of ​​the low-pressure piston 10 is S times that of the piston surface area of ​​the high-pressure piston 2, corresponding to the gas pressure in the high-pressure airbag 1 being S times that of the gas pressure in the low-pressure airbag 12.

[0040] In this embodiment, one high-pressure gas storage unit can be connected to multiple low-pressure storage units simultaneously through a pressure transmission unit.

[0041] In this embodiment, the sum of the piston surface areas of the high-pressure transmission piston 5 is equal to the sum of the piston surface areas of the low-pressure transmission piston 8.

[0042] In this embodiment, both the first heat exchanger 16 and the second heat exchanger 22 are regenerative heat exchangers.

[0043] In this embodiment, the compressor pipeline includes a multi-stage compressor 15, and the turbine pipeline includes a multi-stage turbine 23.

[0044] In this embodiment, the working gas used is air, carbon dioxide, nitrogen, helium, etc.

[0045] In this embodiment, the heat storage medium in the energy storage pipeline can be molten salt, heat transfer oil, water, etc.

[0046] The working process of this invention is as follows:

[0047] During energy storage, the low-pressure gas storage chamber valve 13, the high-pressure gas storage chamber valve 18, the compressor inlet valve 14, and the compressor outlet valve 17 are opened, while the turbine inlet valve 21 and the turbine outlet valve 25 are closed. The compressor 15 is driven by electricity from the power grid or renewable energy sources, causing the gas in the low-pressure gas bag 12 to enter the compressor 15, where it is heated and pressurized. The gas then enters the first heat exchanger 16 to release heat, and the high-pressure gas after heat release enters the high-pressure gas bag 1. As the gas volume in the high-pressure gas bag 1 increases, it pushes the high-pressure piston 2 downwards to maintain a constant gas pressure within the high-pressure gas bag 1. Simultaneously, the high-pressure piston 2 pushes the high-pressure transmission piston 5 downwards via the high-pressure piston connecting rod 3. The downward movement of the high-pressure transmission piston 5 pushes the low-pressure transmission piston 8 upwards via the pressure-transmitting fluid 7, and the upward movement of the low-pressure transmission piston 8 pushes the low-pressure piston 10 upwards via the low-pressure piston connecting rod 9. The upward movement of the low-pressure piston 10 reduces the volume of the low-pressure gas bag 12 to maintain a constant gas pressure within it. At the same time, the heat storage fluid in the cold storage tank 19 enters the first heat exchanger 16 to absorb the heat of compression, and then enters the heat storage tank 20 to store the heat.

[0048] During energy release, the low-pressure gas storage chamber valve 13, the high-pressure gas storage chamber valve 18, the turbine inlet valve 21, and the turbine outlet valve 25 are opened, while the compressor inlet valve 14 and the compressor outlet valve 17 are closed. The high-pressure gas in the high-pressure gas bag 1 enters the second heat exchanger 22 to absorb heat released by the heat storage medium and heats up. It then enters the turbine 23 to perform work. The exhaust gas from the turbine 23 is cooled by the cooler 24 and becomes lower-temperature gas before entering the low-pressure gas bag 12. Due to the increased gas volume in the low-pressure gas bag 12, its pressure rises, causing the low-pressure gas bag 12 to push the low-pressure piston 10 downwards. The downward movement of the low-pressure piston 10 pushes the low-pressure transmission piston 8 downwards via the low-pressure piston connecting rod 9. The downward movement of the low-pressure transmission piston 8 pushes the high-pressure transmission piston 5 upwards via the pressure transmission fluid 7. The upward movement of the high-pressure transmission piston 5 pushes the high-pressure piston 2 upwards via the high-pressure piston connecting rod 3. The upward movement of the high-pressure piston 2 causes the volume of the high-pressure gas bag 1 to decrease, maintaining a constant gas pressure within the high-pressure gas bag 1. At the same time, the heat medium in the heat storage tank 20 enters the second heat exchanger 22 to release heat to the working medium, and the heat storage medium after releasing heat enters the cold storage tank 19.

[0049] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A compressed gas energy storage system with constant pressure gas storage, characterized in that, It includes a high-pressure gas storage unit, a pressure transmission unit, compressor piping, turbine piping, energy storage circuit, and several low-pressure gas storage units; One end of each low-pressure gas storage unit is connected to one end of the high-pressure gas storage unit via a pressure transmission unit. The other end of each low-pressure gas storage unit is connected to one end of the turbine pipeline and one end of the compressor pipeline. The other end of the high-pressure gas storage unit is connected to the other end of the turbine pipeline and the other end of the compressor pipeline. The compressor pipeline and the turbine pipeline are connected through an energy storage circuit. The pressure transmission unit includes a pressure transmission pipe (6) and a pressure transmission fluid (7) disposed within the pressure transmission pipe (6). The low-pressure gas storage unit includes a low-pressure gas storage chamber (11) and a low-pressure piston connecting rod (9). The low-pressure gas storage chamber (11) is equipped with a low-pressure piston (10) and a low-pressure air bag (12). The low-pressure air bag (12) is located on one side of the low-pressure piston (10). One end of the low-pressure piston connecting rod (9) is connected to the other end of the low-pressure piston (10). The other end of the low-pressure piston connecting rod (9) is inserted into the pressure transmission pipe (6) along one end and then a low-pressure transmission piston (8) is provided. The opening on the low-pressure air bag (12) is connected to the turbine pipeline and the compressor pipeline through the low-pressure gas storage chamber valve (13). The high-pressure gas storage unit includes a high-pressure gas storage chamber (4) and a high-pressure piston connecting rod (3). The high-pressure gas storage chamber (4) is equipped with a high-pressure piston (2) and a high-pressure air bag (1). The high-pressure air bag (1) is located on one side of the high-pressure piston (2). One end of the high-pressure piston connecting rod (3) is connected to the other side of the high-pressure piston (2). The other end of the high-pressure piston connecting rod (3) is inserted into the pressure transmission pipe (6) along the other end of the pressure transmission pipe (6) and then a high-pressure transmission piston (5) is installed. The opening on the high-pressure air bag (1) is connected to the turbine pipeline and the compressor pipeline through the high-pressure gas storage chamber valve (18). The piston surface area of ​​the low-pressure piston (10) is S times that of the piston surface area of ​​the high-pressure piston (2), corresponding to the gas pressure in the high-pressure airbag (1) being S times that of the gas pressure in the low-pressure airbag (12).

2. The constant-pressure compressed gas energy storage system according to claim 1, characterized in that, The turbine pipeline includes a turbine outlet valve (25), a cooler (24), a turbine (23), a second heat exchanger (22), and a turbine inlet valve (21). The opening on the low-pressure airbag (12) is connected to the opening on the high-pressure airbag (1) via the low-pressure air chamber valve (13), the turbine outlet valve (25), the cooler (24), the turbine (23), the cold side of the second heat exchanger (22), the turbine inlet valve (21), and the high-pressure air chamber valve (18).

3. The constant-pressure compressed gas energy storage system according to claim 2, characterized in that, The turbine pipeline includes a compressor inlet valve (14), a compressor (15), a first heat exchanger (16), and a compressor outlet valve (17). The opening on the low-pressure airbag (12) is connected to the opening on the high-pressure airbag (1) in sequence via the low-pressure air storage chamber valve (13), the compressor inlet valve (14), the compressor (15), the hot side of the first heat exchanger (16), the compressor outlet valve (17), and the high-pressure air storage chamber valve (18).

4. The constant-pressure compressed gas energy storage system according to claim 3, characterized in that, The energy storage circuit includes a cold storage tank (19) and a heat storage tank (20); the outlet of the cold storage tank (19) is connected to the inlet of the heat storage tank (20) via the cold side of the first heat exchanger (16), and the outlet of the heat storage tank (20) is connected to the inlet of the cold storage tank (19) via the hot side of the second heat exchanger (22).

5. The constant-pressure compressed gas energy storage system according to claim 3, characterized in that, The high-pressure airbag (1) and the low-pressure airbag (12) are flexible airbags.

6. The constant-pressure compressed gas energy storage system according to claim 3, characterized in that, The sum of the piston surface areas of the high-pressure transmission piston (5) is equal to the sum of the piston surface areas of the low-pressure transmission piston (8).

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