Underwater compressed air energy storage device and energy storage system

Abstract

The invention relates to the technical field of energy storage, and discloses an underwater compressed air energy storage device and an energy storage system, and the underwater compressed air energy storage device comprises a rigid housing which is provided with a cavity and a water passing port; the ventilation nozzle at one end of the flexible air bag is arranged at the other end of the rigid shell; the plug slides in the cavity and is located between the water passing opening and the flexible air bag. A water passing hole is formed in the plug; gas is introduced into the flexible air bag through the ventilation nozzle, the flexible air bag expands to the inner wall of the rigid shell, the plug is pushed to slide to the water passing opening, and water is discharged through the water passing hole and the water passing opening; the flexible air bag is deflated through the ventilation nozzle, the plug slides under water pressure to push the flexible air bag to be compressed, and water flows to the position between the flexible air bag and the rigid shell through the water passing opening and the water passing hole so as to continue to compress the flexible air bag. The flexible air bag is limited through the rigid shell, and air storage exceeding water depth static pressure is achieved; and air is completely deflated through water pressure, no bottom air exists, and the energy storage efficiency and density are both improved.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to an underwater compressed air energy storage device and an energy storage system. Background Art

[0002] Compressed air energy storage systems can be divided into constant volume compressed air energy storage systems and constant pressure compressed air energy storage systems according to the form of gas storage. For constant volume compressed air energy storage systems, they generally include: gas storage reservoirs; the gas storage volume of the gas storage reservoir is fixed, and during the process of energy storage and energy release, as the amount of air inside the gas storage reservoir changes, the temperature and pressure inside the gas storage reservoir also change continuously.

[0003] In the process of using a constant volume compressed air energy storage system to release energy and generate electricity, the gas storage reservoir is generally connected to an expander, and the pressure in the gas storage reservoir continues to decrease as the air is continuously released. When the pressure in the gas storage reservoir drops to the design intake pressure of the expander, the pressure in the gas storage reservoir continues to decrease as the air is continuously released, and the constant volume compressed air energy storage system is difficult to continue to maintain the design intake pressure to meet the full power operation of the expander. Summary of the invention

[0004] In view of this, the present invention provides an underwater compressed air energy storage device to solve the problem that in the process of using a constant volume compressed air energy storage system to release energy and generate electricity, the gas storage reservoir is generally connected to an expander, and the pressure in the gas storage reservoir continues to decrease as the air is continuously released. When the pressure in the gas storage reservoir drops to the designed intake pressure of the expander, the pressure in the gas storage reservoir continues to decrease as the air is continuously released, and the constant volume compressed air energy storage system is difficult to continue to maintain the designed intake pressure to meet the problem of full power operation of the expander.

[0005] In a first aspect, the present invention provides an underwater compressed air energy storage device, comprising: A rigid shell having a cavity, wherein a water outlet connecting the cavity with an external water environment is provided at one end of the rigid shell; A flexible airbag is located in the cavity, and a venting nozzle provided at one end of the flexible airbag is arranged on a through hole at the other end of the rigid shell; A plug is slidable in the cavity, the plug is located between the water outlet and the flexible airbag; and a water hole is provided on the plug; The underwater compressed air energy storage device has an energy storage state in which gas is introduced into the flexible airbag through the vent nozzle, the flexible airbag expands to fit the inner wall of the rigid shell, and the flexible airbag pushes the plug to slide to the water outlet, and at the same time, water between the flexible airbag and the inner wall of the rigid shell is discharged to the external water environment through the water outlet and the water outlet; and an energy release state in which the flexible airbag releases gas to the outside through the vent nozzle, the plug slides under the pressure of the external water environment, and pushes the flexible airbag to compress its volume, and at the same time, water in the external water environment flows through the water outlet and the water hole to between the flexible airbag and the inner wall of the rigid shell to continue to compress the flexible airbag. Beneficial effects: This application adopts the above technical solution, and utilizes the natural constant temperature and constant pressure advantage underwater to stabilize the working pressure of the expander, so that it always works near the designed intake pressure point, and maintains the pressure at the inlet of the expander stable to meet the full power operation of the expander; through the restriction of the flexible airbag by the rigid shell, high-pressure gas storage exceeding the static pressure of the water depth can be achieved, and deep water is not required, that is, it is arranged in shallow water areas, and a larger pressure can be achieved; it can also be completely deflated by the constant pressure of the water environment to meet the constant pressure equal to the designed intake pressure of the expander, and the gas can be completely released by the water pressure of the water environment, without cushioning the bottom gas, and the gas storage volume is fully utilized, and the energy storage efficiency and energy storage density are improved. Different from the constant volume compressed air energy storage system, in the water environment, after the flexible airbag deflates the gas, there is no pressure difference inside and outside the entire underwater compressed air energy storage device; no special geological structure and high-pressure storage tank are required to bear the high-pressure air, which significantly reduces the storage cost, and the cost is greatly reduced at the same gas storage pressure. In addition, the flexible airbag can automatically adjust its shape according to the change of internal air pressure during the process of filling and deflation to achieve the effect of stabilizing the internal pressure.

[0006] Optionally, the other end of the flexible airbag is connected to the plug. Beneficial effects: The present application adopts the above technical solution to ensure that the setting of the airbag is stable and reliable.

[0007] Optionally, the water holes are multiple and evenly arranged on the edge of the plug; the other end of the flexible airbag is connected to the center of the plug. Beneficial effect: The present application adopts the above technical solution, and by setting multiple evenly distributed water holes, the water flow is uniform and stable; and by using multiple water holes with smaller diameters, the channel of the water outlet can be split. When the air pressure in the flexible airbag is higher than the water pressure, the pressure in the flexible airbag can be dispersed, effectively protecting the flexible airbag and preventing the flexible airbag from being damaged at the water outlet.

[0008] Optionally, the rigid shell is cylindrical in shape.

[0009] Optionally, the inner side of the water outlet is a conical expansion structure, and the plug is provided with a conical surface structure that matches the shape of the conical expansion structure. Beneficial effect: The present application adopts the above technical solution to ensure that the plug can stably and reliably block the water outlet.

[0010] In a second aspect, the present invention further provides an energy storage system, comprising: the underwater compressed air energy storage device described above.

[0011] Optionally, it also includes: A compressor unit connected to the vent of the flexible airbag via a first valve; an expansion unit connected to the vent of the flexible airbag via a second valve; The energy storage system has a first state in which the compressor unit is started, the first valve is opened, the second valve is closed, and the compressor unit introduces gas to the flexible airbag; and a second state in which the expansion unit is started, the first valve is closed, the second valve is opened, and the flexible airbag provides air intake for the expansion unit. Beneficial effects: The present application adopts the above technical scheme. In the process of inflating and storing energy in the underwater compressed air energy storage device, it is a process of first constant pressure and then variable pressure, which reduces the variable operating range of the compressor unit, and the compressor unit basically operates in the high-efficiency area, which significantly improves the working efficiency of the compressor unit; in the process of deflation and energy release of the underwater compressed air energy storage device, it is a process of first variable pressure and then constant pressure, and the variable operating range of the expansion unit is small. The expansion unit basically operates in the high-efficiency area, which significantly improves the working efficiency of the expansion unit; so that the operating efficiency of the energy storage system of the present application under the full working conditions of energy storage and energy release is significantly improved.

[0012] Optionally, it also includes: A first heat exchanger assembly is arranged at the output port of the compressor unit, and the first heat exchanger assembly is suitable for collecting compression heat energy generated by the compressor unit; a first heat storage structure connected to the first heat exchanger assembly, the first heat exchanger assembly being adapted to transfer compressed heat energy to the first heat storage structure for storage; A second heat exchanger assembly is arranged at the input port of the expansion unit, and the second heat exchanger assembly is connected to the first heat storage structure, and the second heat exchanger assembly is suitable for heating the intake air of the expansion unit by using the compression heat energy transmitted by the second heat exchanger assembly; The second heat storage structure is connected to the second heat exchanger assembly and the first heat exchanger assembly. The second heat storage structure is suitable for storing the heat storage medium after heat exchange by the second heat exchanger assembly, and circulating the heat storage medium to the first heat exchanger assembly. Beneficial effect: The present application adopts the above technical solution to fully utilize the compression heat of the compressor to heat the intake air of the expander, which can not only utilize the compression waste heat, but also improve the efficiency of the expander, further reduce costs, and improve efficiency.

[0013] Optionally, the heat storage medium is water, and a cold water pump and a third valve are provided on the pipeline connecting the first heat exchanger assembly and the second heat storage structure; a hot water pump and a fourth valve are provided on the pipeline connecting the first heat storage structure and the first heat exchanger assembly.

[0014] Optionally, the first heat exchanger assembly comprises: at least two coolers connected and arranged; The compressor unit comprises: at least two compressors connected and arranged, and each cooler is arranged at the exhaust port of different compressors; The second heat exchanger assembly includes: at least two reheaters connected and arranged; The expansion machine group comprises: at least two expansion machines which are connected to each other, and each reheater is respectively arranged at the air inlet of different expansion machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 A schematic diagram of the three-dimensional structure of an underwater compressed air energy storage device provided in an embodiment of the present invention; Figure 2 A schematic cross-sectional view of an underwater compressed air energy storage device provided in an embodiment of the present invention; Figure 3 A partial cross-sectional view of the underwater compressed air energy storage device provided in an embodiment of the present invention Figure 1 ; Figure 4 A partial cross-sectional view of the underwater compressed air energy storage device provided in an embodiment of the present invention Figure 2 ; Figure 5 A partial front view structural schematic diagram of an underwater compressed air energy storage device provided in an embodiment of the present invention; Figure 6 A schematic cross-sectional view of a plug provided in an embodiment of the present invention; Figure 7 This is a schematic diagram of the main structure of the plug provided in an embodiment of the present invention; Figure 8 It is a left-side structural schematic diagram of a plug provided in an embodiment of the present invention; Fig. 9 It is a right side structural schematic diagram of the plug provided in an embodiment of the present invention; Fig.10 A cross-sectional schematic diagram of a flexible airbag when it is filled with gas provided in an embodiment of the present invention; Fig.11 A cross-sectional schematic diagram of a flexible airbag provided in an embodiment of the present invention when half of the gas is released; Fig.12 A cross-sectional schematic diagram of the flexible airbag provided in an embodiment of the present invention when the gas is fully released; Fig.13 A connection diagram of an energy storage system provided in an embodiment of the present invention.

[0017] Description of reference numerals: 1. Rigid shell; 2. Plug; 3. Flexible airbag; 4. Vent; 5. Water outlet; 6. Water hole; 7. First valve; 8. Second valve; 9. First heat storage structure; 10. Second heat storage structure; 11. Cold water pump; 12. Third valve; 13. Hot water pump; 14. Fourth valve; 15. Cooler; 16. Compressor; 17. Reheater; 18. Expander; 19. Horizontal plane. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0019] For constant volume compressed air energy storage systems, if the pressure in the gas storage reservoir is increased, caves with special geological structures and high-cost artificial chambers are required to store high-pressure gas; however, caves or artificial chambers cannot be completely depressurized, otherwise there will be a risk of collapse, and there is a lot of bottom gas and low energy storage density. For constant pressure compressed air energy storage systems, underwater flexible gas storage can be used. With the help of the hydrostatic pressure of water, constant pressure energy storage and energy release can be achieved, thereby improving the efficiency and energy storage density of the constant pressure compressed air energy storage system; however, the above-mentioned constant pressure compressed air energy storage system located underwater requires the use of very deep water to achieve a gas storage pressure of 7MPa to 10MPa. At present, offshore wind power is basically in shallow waters within 100 meters, there are few deep water environments, and the construction cost of deep water areas is high. It is also due to the above reasons that the present application proposes an underwater compressed air energy storage device.

[0020] like Figures 1 to 12A specific embodiment of the underwater compressed air energy storage device shown includes: a rigid shell 1, a flexible air bag 3 and a plug 2. The underwater compressed air energy storage device described in the present application is very suitable for the needs of building large-scale long-term energy storage in low-pressure shallow water areas.

[0021] like Figures 1 to 4 As shown, the rigid shell 1 has a cavity, and a water outlet 5 connecting the cavity with the external water environment is provided at one end of the rigid shell 1; specifically, the rigid shell 1 is cylindrical. The rigid shell 1 described in the present application is an open structure and can be made of composite materials. The flexible airbag 3 is located in the cavity, and the ventilation nozzle 4 provided at one end of the flexible airbag 3 is arranged on the through hole at the other end of the rigid shell 1; the ventilation nozzle 4 can be fixed on the through hole. The flexible airbag 3 described in the present application is a closed structure, and can be an inner liner made of composite materials. As shown in FIG. Figures 5 to 8 As shown, the plug 2 slides in the cavity, and the plug 2 is located between the water outlet 5 and the flexible airbag 3; and a water hole 6 is provided on the plug 2. Specifically, as Figure 8 As shown, the water holes 6 are multiple and evenly distributed on the edge of the plug 2, and the number of the water holes 6 can be eight and evenly distributed at intervals.

[0022] like Figures 10 to 12 As shown, the underwater compressed air energy storage device has an energy storage state in which gas is introduced into the flexible airbag 3 through the vent nozzle 4, the flexible airbag 3 expands to fit the inner wall of the rigid shell 1, and the flexible airbag 3 pushes the plug 2 to slide to the water outlet 5. At the same time, the water between the flexible airbag 3 and the inner wall of the rigid shell 1 is discharged to the external water environment through the water hole 6 and the water outlet 5; and an energy release state in which the flexible airbag 3 releases gas to the outside through the vent nozzle 4, the plug 2 slides under the pressure of the external water environment to push the flexible airbag 3 to compress the volume, and at the same time, the water in the external water environment flows through the water outlet 5 and the water hole 6 to the space between the flexible airbag 3 and the inner wall of the rigid shell 1 to continue to compress the flexible airbag 3. Reference Fig.13 The vent nozzle 4 of the present application is suitable for connecting to the expander 18. Specifically, the gas can be air. In the process of charging and storing energy, the pressure is first constant and then variable, and in the process of deflation and releasing energy, the pressure is first variable and then constant.

[0023] Further, such as Fig.12 As shown, the other end of the flexible airbag 3 is connected to the plug 2 ; specifically, the other end of the flexible airbag 3 is connected to the center of the plug 2 .

[0024] Further, such as Figure 3 As shown, the inner side of the water outlet 5 is a conical expansion structure, and the plug 2 is provided with a conical surface structure that matches the shape of the conical expansion structure.

[0025] The underwater compressed air energy storage device described in the present application can be used in areas where the external water environment is a shallow water area to reduce costs; the depth of the shallow water area is generally not more than 100 meters. In the energy storage state, the ultimate pressure reached in the flexible airbag 3 can be no less than 10MPa, or can be below 10MPa.

[0026] like Figures 10 to 12 As shown, the underwater compressed air energy storage device described in the present application is in a water environment of a certain depth for a long time, and is subjected to water pressure from the external water environment. When air of a certain pressure is filled into the flexible airbag 3, the flexible airbag 3 expands and pushes the plug 2 to slide. At the same time, the water inside the rigid shell 1 is discharged from the rigid shell 1 as the space occupied by the flexible airbag 3 increases, until the flexible airbag 3 is completely filled, and the plug 2 blocks the water outlet 5 of the rigid shell 1. When the flexible airbag 3 continues to be inflated, the rigid shell 1 is pressed. The rigid shell 1 only needs to withstand the pressure difference between the water pressure and the air pressure, thereby reducing the thickness of the rigid shell 1 and reducing the cost; when deflation, the air pressure in the flexible airbag 3 is first reduced. When it reaches the same pressure as the water pressure, the water pushes the plug 2 to slide, and the water enters one side of the flexible airbag 3 through the water hole 6 on the plug 2 to supplement the internal space increased by deflation. Under the natural constant temperature and pressure conditions of water, the flexible airbag 3 deflates outward, the output gas pressure is constant, and there is no pressure difference between the inside and the outside after the gas is emptied. Under the same gas storage pressure, the cost is lower.

[0027] like Fig.13 As shown, the present invention further provides an energy storage system, including: the underwater compressed air energy storage device. All parts of the energy storage system described in this application except the underwater compressed air energy storage device are located above the horizontal plane 19, that is, not located in the external water environment.

[0028] like Fig.13 As shown, the energy storage system described in the present application also includes: a compressor unit and an expansion unit. The compressor unit is connected to the vent 4 of the flexible airbag 3 through a first valve 7; the expansion unit is connected to the vent 4 of the flexible airbag 3 through a second valve 8. The energy storage system has a first state in which the compressor unit is started, the first valve 7 is opened, the second valve 8 is closed, and the compressor unit passes gas to the flexible airbag 3; and a second state in which the expansion unit is started, the first valve 7 is closed, the second valve 8 is opened, and the flexible airbag 3 provides air intake for the expansion unit. Specifically, the first valve 7 is a switch valve, and the second valve 8 is a regulating valve. Among them, Fig.13 The arrows in the figure indicate the direction of gas flow. The arrow on the upper left side indicates air intake, and the arrow on the lower left side indicates exhaust.

[0029] like Fig.13As shown, the energy storage system described in the present application also includes: a first heat exchanger assembly, a first heat storage structure 9, a second heat exchanger assembly and a second heat storage structure 10. The first heat exchanger assembly is arranged at the output port of the compressor unit, and the first heat exchanger assembly is suitable for collecting the compression heat energy generated by the compressor unit by heat exchange. The first heat storage structure 9 is connected to the first heat exchanger assembly, and the first heat exchanger assembly is suitable for transporting the compression heat energy to the first heat storage structure 9 for storage. The second heat exchanger assembly is arranged at the input port of the expansion unit, and the second heat exchanger assembly is connected to the first heat storage structure 9, and the second heat exchanger assembly is suitable for heating the intake air of the expansion unit by heat exchange using the compression heat energy transmitted by the second heat exchanger assembly. The second heat storage structure 10 is connected to both the second heat exchanger assembly and the first heat exchanger assembly, and the second heat storage structure 10 is suitable for storing the heat storage medium after heat exchange by the second heat exchange assembly, and circulating the heat storage medium to the first heat exchanger assembly.

[0030] Specifically, Fig.13 As shown, the heat storage medium is water, and a cold water pump 11 and a third valve 12 are provided on the pipeline connecting the first heat exchanger assembly and the second heat storage structure 10; a hot water pump 13 and a fourth valve 14 are provided on the pipeline connecting the first heat storage structure 9 and the first heat exchanger assembly.

[0031] Specifically, Fig.13 As shown, the first heat exchanger assembly includes: two coolers 15 connected together; the compressor unit includes: two compressors 16 connected together, and the two coolers 15 are respectively arranged at the exhaust ports of the two compressors 16. The second heat exchanger assembly includes: two reheaters 17 connected together; the expander unit includes: two expanders 18 connected together, and the two reheaters 17 are respectively arranged at the air inlets of the two expanders 18.

[0032] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations are all within the scope defined by the appended claims.

Claims

1. An underwater compressed air energy storage device, characterized in that: include: A rigid shell (1) having a cavity, wherein a water outlet (5) connecting the cavity with an external water environment is provided at one end of the rigid shell (1); A flexible airbag (3) is located in the cavity, and a vent (4) provided at one end of the flexible airbag (3) is arranged on a through hole at the other end of the rigid shell (1); A plug (2) is slidable in the cavity, the plug (2) is located between the water outlet (5) and the flexible airbag (3); and a water hole (6) is provided on the plug (2); The underwater compressed air energy storage device has an energy storage state in which gas is introduced into the flexible airbag (3) through the vent nozzle (4), the flexible airbag (3) expands to fit the inner wall of the rigid shell (1), and the flexible airbag (3) pushes the plug (2) to slide to the water outlet (5), and at the same time, water between the flexible airbag (3) and the inner wall of the rigid shell (1) is discharged to the external water environment through the water outlet (6) and the water outlet (5); and an energy release state in which the flexible airbag (3) releases gas to the outside through the vent nozzle (4), the plug (2) slides under the pressure of the external water environment to push the flexible airbag (3) to compress the volume, and at the same time, water in the external water environment flows to the space between the flexible airbag (3) and the inner wall of the rigid shell (1) through the water outlet (5) and the water outlet (6) to continue to compress the flexible airbag (3).

2. The underwater compressed air energy storage device according to claim 1, characterized in that: The other end of the flexible airbag (3) is connected to the plug (2).

3. The underwater compressed air energy storage device according to claim 2, characterized in that: The water holes (6) are multiple and evenly distributed on the edge of the plug (2); the other end of the flexible airbag (3) is connected to the center of the plug (2).

4. The underwater compressed air energy storage device according to any one of claims 1 to 3, characterized in that: The rigid shell (1) is in a cylindrical shape.

5. The underwater compressed air energy storage device according to any one of claims 1 to 3, characterized in that: The inner side of the water outlet (5) is a conical surface expansion structure, and the plug (2) is provided with a conical surface structure that matches the shape of the conical surface expansion structure.

6. An energy storage system, characterized in that: include: An underwater compressed air energy storage device as claimed in any one of claims 1 to 5.

7. The energy storage system according to claim 6, characterized in that: Also includes: A compressor unit connected to the vent (4) of the flexible airbag (3) via a first valve (7); An expansion unit connected to the vent nozzle (4) of the flexible airbag (3) via a second valve (8); The energy storage system has a first state in which the compressor unit is started, the first valve (7) is opened, the second valve (8) is closed, and the compressor unit introduces gas to the flexible airbag (3); and a second state in which the expander unit is started, the first valve (7) is closed, the second valve (8) is opened, and the flexible airbag (3) provides air intake for the expander.

8. The energy storage system according to claim 7, characterized in that: Also includes: A first heat exchanger assembly is arranged at the output port of the compressor unit, and the first heat exchanger assembly is suitable for collecting compression heat energy generated by the compressor unit; A first heat storage structure (9) connected to the first heat exchanger assembly, the first heat exchanger assembly being suitable for transmitting compressed heat energy to the first heat storage structure (9) for storage; a second heat exchanger assembly, arranged at the input port of the expansion unit, and connected to the first heat storage structure (9), the second heat exchanger assembly being suitable for heating the intake air of the expansion unit by utilizing the compression heat energy transmitted by the second heat exchanger assembly; The second heat storage structure (10) is connected to both the second heat exchanger assembly and the first heat exchanger assembly, and the second heat storage structure (10) is suitable for storing the heat storage medium after heat exchange in the second heat exchange assembly, and circulating the heat storage medium into the first heat exchanger assembly.

9. The energy storage system according to claim 8, characterized in that: The heat storage medium is water, and a cold water pump (11) and a third valve (12) are provided on a pipeline connecting the first heat exchanger assembly and the second heat storage structure (10); and a hot water pump (13) and a fourth valve (14) are provided on a pipeline connecting the first heat storage structure (9) and the first heat exchanger assembly.

10. The energy storage system according to claim 8 or 9, characterized in that: The first heat exchanger assembly comprises: at least two coolers (15) connected and arranged; The compressor unit comprises: at least two compressors (16) connected to each other, and each cooler (15) is respectively arranged at the exhaust port of a different compressor (16); The second heat exchanger assembly comprises: at least two reheaters (17) connected and arranged; The expansion machine group comprises: at least two expansion machines (18) which are connected to each other, and each reheater (17) is respectively arranged at the air inlet of a different expansion machine (18).

Images