Compressed gas energy storage system capable of constant-pressure gas storage

Abstract

Disclosed in the present invention is a compressed gas energy storage system capable of constant-pressure gas storage. The compressed gas energy storage system comprises a high-pressure gas storage unit, a pressure transmission unit, a compressor pipeline, a turbine pipeline, an energy storage loop and several low-pressure gas storage units, wherein one end of each low-pressure gas storage unit is in communication with one end of the high-pressure gas storage unit via the pressure transmission unit, the other end of each low-pressure gas storage unit is in communication 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 in communication with the other end of the turbine pipeline and the other end of the compressor pipeline, and the compressor pipeline is in communication with the turbine pipeline by means of the energy storage loop. The system can realize constant pressure during inflation and deflation.

Description

A compressed gas energy storage system with constant pressure gas storage Technical Field

[0001] The present invention belongs to the technical field of energy storage, and relates to a compressed gas energy storage system for constant-pressure gas storage. Background Art

[0002] Compressed gas energy storage (CGS) is a technology that converts electricity into the potential energy of compressed gas, storing it and releasing it to generate electricity when needed. This technology leverages the elastic properties of gas and the energy conversion during the compression-expansion process to store and recycle energy. CGS technology enables large-scale electricity storage, offering advantages such as flexibility and environmental friendliness. With the rapid development of renewable energy and the increasing demand for energy storage, CGS technology holds broad application prospects.

[0003] Compressed gas energy storage typically stores compressed gas in a fixed-volume space, such as underground salt caverns, gas storage tanks, and pipe banks. When high-pressure gas is released, the mass of gas in the storage space decreases. At the same time, because the volume remains unchanged, the stored gas pressure gradually decreases. As the pressure decreases, the work capacity of the stored gas decreases. Furthermore, during the inflation process, the gas pressure in the storage space gradually increases, requiring the compressor's exhaust pressure to increase, causing the compressor's operating state to deviate from its optimal operating point and resulting in a decrease in system efficiency. This contradiction between the compression-expansion characteristics of gas 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 constant pressure in the storage space during inflation and deflation, the cycle efficiency of compressed gas energy storage will be significantly improved to over 74%, which will greatly enhance the competitiveness of compressed gas energy storage technology. Some scholars have proposed using flexible airbags to store compressed gas and placing the airbags at a certain depth underwater, using water pressure to maintain constant pressure during inflation and deflation. However, this solution has high requirements for geological and hydrological conditions. For example, to store 7.5MPa and 25MPa gas, the airbags would need to be placed underwater at depths of approximately 750m and 2500m, respectively, making the feasibility of the solution questionable.

[0005] Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings of the above-mentioned prior art and provide a compressed gas energy storage system with constant pressure gas storage, which can achieve constant pressure during the inflation and deflation processes.

[0007] To achieve the above-mentioned object, the present invention discloses a compressed gas energy storage system with constant pressure gas storage, comprising a high-pressure gas storage unit, a pressure transmission unit, a compressor pipeline, a turbine pipeline, an energy storage circuit and a plurality of low-pressure gas storage units;

[0008] 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, 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, and the compressor pipeline and the turbine pipeline are connected through the energy storage circuit.

[0009] The pressure transmission unit includes a pressure transmission pipe and a pressure transmission fluid disposed in the pressure transmission pipe.

[0010] The low-pressure gas storage unit includes a low-pressure gas storage chamber and a low-pressure piston connecting rod;

[0011] A low-pressure piston and a low-pressure airbag are provided in the low-pressure air storage chamber. The low-pressure airbag 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 a low-pressure transmission piston is provided. The opening on the low-pressure airbag is connected to the turbine pipeline and the compressor pipeline through the low-pressure air storage chamber valve.

[0012] The high-pressure gas storage unit includes a high-pressure gas storage chamber and a high-pressure piston connecting rod;

[0013] A high-pressure piston and a high-pressure airbag are provided in the high-pressure air storage chamber, wherein the high-pressure airbag 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, and the other end of the high-pressure piston connecting rod is inserted into the pressure transmission tube along the other end of the pressure transmission tube and a high-pressure transmission piston is provided. The opening on the high-pressure airbag is connected to the turbine pipeline and the compressor pipeline through the high-pressure air storage chamber valve.

[0014] The turbine pipeline includes a turbine outlet valve, a cooler, a turbine, a second heat exchanger and a turbine inlet valve;

[0015] The opening on the low-pressure airbag is connected to the opening on the high-pressure airbag through 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.

[0016] The turbine pipeline includes a compressor inlet valve, a compressor, a first heat exchanger and a compressor outlet valve;

[0017] The opening on the low-pressure airbag is connected to the opening on the high-pressure airbag through 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.

[0018] The outlet of the cold storage tank is connected to the inlet of the heat storage tank via the cold side of the first heat exchanger, and the outlet of the heat storage tank is connected to the inlet of the cold storage tank via the hot side of the second heat exchanger.

[0019] The high-pressure airbag and the low-pressure airbag are flexible airbags.

[0020] The piston surface area of ​​the low-pressure piston is S times the piston surface area of ​​the high-pressure piston, corresponding to the gas pressure in the high-pressure airbag being S times the gas pressure in the low-pressure airbag.

[0021] The sum of the piston face areas of the high-pressure transmission pistons is equal to the sum of the piston face areas of the low-pressure transmission pistons.

[0022] The present invention has the following beneficial effects:

[0023] During specific operation, the compressed gas energy storage system with constant pressure gas storage described in the present invention connects the high-pressure airbag and the low-pressure airbag through a piston mechanism and a transmission fluid. The pistons of the high-pressure airbag and the low-pressure airbag adopt 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 processes, reducing pressure loss during the inflation and deflation processes, and thus greatly improving the cycle efficiency of the compressed gas energy storage.

[0024] Furthermore, the present invention can adjust the ratio of the gas pressures 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, and the operation is convenient and flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG1 is a structural diagram of the present invention.

[0026] 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 DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only embodiments of a part of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts disclosed in the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should fall within the scope of protection of the present invention.

[0028] The accompanying drawings illustrate schematic diagrams of the structures of the disclosed embodiments of the present invention. These figures are not drawn to scale; for the purpose of clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0029] Referring to Figure 1, the compressed gas energy storage system with constant pressure gas storage described in 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, 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, and the compressor pipeline and the turbine pipeline are connected through the energy storage circuit.

[0030] The high-pressure gas storage unit includes a high-pressure airbag 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.

[0031] 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 bag 12 and a low-pressure gas storage chamber valve 13.

[0032] The pressure transmission unit includes a pressure transmission tube 6 and a pressure transmission fluid 7 .

[0033] The compressor pipeline includes a compressor inlet valve 14 , a compressor 15 , a first heat exchanger 16 and a compressor outlet valve 17 .

[0034] 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 .

[0035] The energy storage circuit includes a cold storage tank 19 and a heat storage tank 20 .

[0036] A low-pressure piston 10 and a low-pressure airbag 12 are provided in the low-pressure air storage chamber 11, and 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, and the other end of the low-pressure piston connecting rod 9 is inserted into the pressure transmission tube 6 along one end of the pressure transmission tube 6, and then a low-pressure transmission piston 8 is provided; a high-pressure piston 2 and a high-pressure airbag 1 are provided in the high-pressure air storage chamber 4, wherein 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, and the other end of the high-pressure piston connecting rod 3 is inserted into the pressure transmission tube 6 along the other end of the pressure transmission tube 6, and then a high-pressure transmission piston 5 is provided, wherein a pressure transmission fluid 7 is provided in the pressure transmission tube 6, wherein the pressure transmission fluid 7 is located between the high-pressure transmission piston 5 and the low-pressure transmission piston 8.

[0037] 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 through the compressor inlet valve 14, the compressor 15, the hot side of the first heat exchanger 16 and the compressor outlet valve 17 in sequence. The other path is connected to one end of the high-pressure air storage chamber valve 18 through the turbine outlet valve 25, the cooler 24, the turbine 23, the cold side of the second heat exchanger 22 and the turbine inlet valve 21 in sequence. The other end of the high-pressure air storage chamber valve 18 is connected to the opening on the high-pressure airbag 1.

[0038] 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 .

[0039] 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.

[0040] In this embodiment, the piston surface area of ​​the low-pressure piston 10 is S times the piston surface area of ​​the high-pressure piston 2 , corresponding to the gas pressure in the high-pressure airbag 1 being S times the gas pressure in the low-pressure airbag 12 .

[0041] In this embodiment, one high-pressure gas storage unit can be simultaneously connected to multiple low-pressure storage units through the pressure transmission unit.

[0042] In this embodiment, the sum of the piston surface areas of the high-pressure transmission pistons 5 is equal to the sum of the piston surface areas of the low-pressure transmission pistons 8 .

[0043] In this embodiment, the first heat exchanger 16 and the second heat exchanger 22 are both thermal storage heat exchangers.

[0044] In this embodiment, the compressor pipeline includes a multi-stage compressor 15, and the turbine pipeline includes a multi-stage turbine 23.

[0045] In this embodiment, the gas working medium used is air, carbon dioxide, nitrogen, helium and the like.

[0046] In this embodiment, the heat storage medium in the energy storage pipeline can be molten salt, thermal oil, water, etc.

[0047] The working process of the present invention is:

[0048] During energy storage, the low-pressure air storage chamber valve 13, high-pressure air storage chamber valve 18, compressor inlet valve 14, and compressor outlet valve 17 are opened, while the turbine inlet valve 21 and turbine outlet valve 25 are closed. Compressor 15 is driven by grid or renewable energy, causing the gas in the low-pressure airbag 12 to enter compressor 15, where it is heated and pressurized. The gas then enters the first heat exchanger 16, where it releases heat. The high-pressure gas, after releasing heat, enters the high-pressure airbag 1. As the gas in the high-pressure airbag 1 increases, the high-pressure airbag 1 pushes the high-pressure piston 2 downward to maintain a constant gas pressure within the airbag 1. Simultaneously, the high-pressure piston 2 pushes the high-pressure transmission piston 5 downward 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 upward via the pressure-transmitting fluid 7. The upward movement of the low-pressure transmission piston 8 pushes the low-pressure piston 10 upward via the low-pressure piston connecting rod 9. The upward movement of the low-pressure piston 10 reduces the volume of the low-pressure airbag 12, maintaining a constant gas pressure within the low-pressure airbag 12. At the same time, the heat storage fluid in the cold storage tank 19 enters the first heat exchanger 16 to absorb compression heat, and then enters the heat storage tank 20 to store heat.

[0049] During energy release, the low-pressure air reservoir valve 13, high-pressure air reservoir valve 18, turbine inlet valve 21, and turbine outlet valve 25 are opened, while the compressor inlet valve 14 and compressor outlet valve 17 are closed. The high-pressure gas in the high-pressure airbag 1 enters the second heat exchanger 22, where it absorbs heat released by the heat storage medium and increases in temperature. The high-pressure gas then enters the turbine 23 to perform work. The exhaust gas from the turbine 23 is cooled by the cooler 24, becoming a lower-temperature gas before entering the low-pressure airbag 12. As the volume of gas in the low-pressure airbag 12 increases, its pressure rises, pushing the low-pressure piston 10 downward. The downward movement of the low-pressure piston 10 pushes the low-pressure transmission piston 8 downward 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 upward via the pressure-transmitting fluid 7. The upward movement of the high-pressure transmission piston 5 pushes the high-pressure piston 2 upward via the high-pressure piston connecting rod 3. The upward movement of the high-pressure piston 2 causes the volume of the high-pressure airbag 1 to decrease, maintaining a constant gas pressure within the high-pressure airbag 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.

[0050] 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, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by 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, 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, 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, and the compressor pipeline and the turbine pipeline are connected through the energy storage circuit.

2. The compressed gas energy storage system with constant pressure gas storage according to claim 1, characterized in that: The pressure transmission unit comprises a pressure transmission tube (6) and a pressure transmission fluid (7) arranged in the pressure transmission tube (6).

3. The compressed gas energy storage system with constant pressure gas storage according to claim 2, characterized in that: The low-pressure gas storage unit comprises a low-pressure gas storage chamber (11) and a low-pressure piston connecting rod (9); A low-pressure piston (10) and a low-pressure airbag (12) are provided in the low-pressure air storage chamber (11). The low-pressure airbag (12) is located on one side of the low-pressure piston (10). One end of a 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 of the pressure transmission pipe (6) and then a low-pressure transmission piston (8) is provided. The opening on the low-pressure airbag (12) is connected to the turbine pipeline and the compressor pipeline through the low-pressure air storage chamber valve (13).

4. The compressed gas energy storage system with constant pressure gas storage according to claim 3, characterized in that: The high-pressure gas storage unit comprises a high-pressure gas storage chamber (4) and a high-pressure piston connecting rod (3); The high-pressure gas storage chamber (4) is provided with a high-pressure piston (2) and a high-pressure airbag (1), wherein 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), and the other end of the high-pressure piston connecting rod (3) is connected along the pressure transmission line. The other end of the tube (6) is inserted into the pressure transmission tube (6) and a high-pressure transmission piston (5) is provided. The opening on the high-pressure air bag (1) is connected to the turbine pipeline and the compressor pipeline through the high-pressure air storage chamber valve (18).

5. The compressed gas energy storage system with constant pressure gas storage according to claim 4, 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) through the low-pressure air storage 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 storage chamber valve (18).

6. The compressed gas energy storage system with constant pressure gas storage according to claim 5, 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) through 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) in sequence.

7. The compressed gas energy storage system with constant pressure gas storage according to claim 6, characterized in that: The energy storage circuit comprises 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).

8. The compressed gas energy storage system with constant pressure gas storage according to claim 6, characterized in that: The high-pressure airbag (1) and the low-pressure airbag (12) are flexible airbags.

9. The compressed gas energy storage system with constant pressure gas storage according to claim 6, characterized in that: The piston surface area of ​​the low-pressure piston (10) is S times the piston surface area of ​​the high-pressure piston (2), corresponding to the gas pressure in the high-pressure airbag (1) being S times the gas pressure in the low-pressure airbag (12).

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

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