An underwater compressed air energy storage device and an energy storage system

Abstract

The present invention relates to the technical field of energy storage, and discloses an underwater compressed air energy storage device and an energy storage system. The underwater compressed air energy storage device includes: a rigid outer shell having a cavity and a water inlet; a flexible airbag is located in the cavity, and an air vent of one end is provided at the other end of the rigid outer shell; a plug slides in the cavity and is located between the water inlet and the flexible airbag; the plug is provided with a water passing hole; by introducing gas into the flexible airbag through the air vent, the flexible airbag expands to the inner wall of the rigid outer shell, pushing the plug to slide to the water inlet, and water is discharged through the water passing hole and the water inlet; the flexible airbag discharges gas through the air vent, and the plug slides under the water pressure to push the flexible airbag to compress, and water flows through the water inlet and the water passing hole to the space between the flexible airbag and the rigid outer shell to continue compressing the flexible airbag. In this application, the rigid outer shell restricts the flexible airbag to achieve gas storage exceeding the hydrostatic pressure of the water depth; through complete deflation by water pressure, there is no bottom cushion gas, and both the energy storage efficiency and density are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage, and particularly relates 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 gas storage form. For a constant-volume compressed air energy storage system, it generally includes: a gas storage chamber; the gas storage volume of the gas storage chamber is fixed and unchanged. During the energy storage and energy release processes, as the amount of air inside the gas storage chamber changes, the temperature and pressure inside the gas storage chamber also continuously change.

[0003] During the process of using a constant-volume compressed air energy storage system for energy release and power generation, the gas storage chamber is generally connected to an expander. The pressure inside the gas storage chamber continuously decreases as the air is continuously released. When the pressure inside the gas storage chamber decreases to the designed intake pressure of the expander, the pressure inside the gas storage chamber continues to decrease as the air is continuously released, so it is difficult for the constant-volume compressed air energy storage system to continue to maintain the designed 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 during the process of using a constant-volume compressed air energy storage system for energy release and power generation, the gas storage chamber is generally connected to an expander, and the pressure inside the gas storage chamber continuously decreases as the air is continuously released. When the pressure inside the gas storage chamber decreases to the designed intake pressure of the expander, the pressure inside the gas storage chamber continues to decrease as the air is continuously released, so it is difficult for the constant-volume compressed air energy storage system to continue to maintain the designed intake pressure to meet the full-power operation of the expander.

[0005] In a first aspect, the present invention provides an underwater compressed air energy storage device, including:

[0006] A rigid outer shell having a cavity, and a water inlet for communicating the cavity with the external water environment is provided at one end of the rigid outer shell;

[0007] A flexible airbag located inside the cavity, and an air vent provided at one end of the flexible airbag is arranged on a through hole at the other end of the rigid outer shell;

[0008] A plug sliding inside the cavity, the plug being located between the water inlet and the flexible airbag; and a water passing hole is provided on the plug;

[0009] The underwater compressed air energy storage device has a state of energy storage in which gas is introduced into the flexible airbag through an air vent, the flexible airbag expands to fit the inner wall of the rigid outer shell, and the flexible airbag pushes the plug to slide to the water passing port. At the same time, the water between the flexible airbag and the inner wall of the rigid outer shell is discharged to the external water environment through the water passing holes and the water passing port; and it has a state of energy release in which the flexible airbag releases gas outward through the air vent, the plug slides under the pressure of the external water environment to push the flexible airbag to compress its volume. At the same time, the water in the external water environment flows through the water passing port and the water passing holes to the space between the flexible airbag and the inner wall of the rigid outer shell to further compress the flexible airbag. Beneficial effects: By adopting the above technical solutions, the present application utilizes the natural constant temperature and constant pressure advantage underwater to stabilize the working pressure of the expander, enabling it to always operate near the designed intake pressure point, maintaining the stability of the pressure at the inlet of the expander to meet the full-power operation of the expander; through the restriction of the rigid outer shell on the flexible airbag, high-pressure gas storage exceeding the hydrostatic pressure of the water depth can be achieved without the need for very deep water, that is, it can be arranged in shallow water areas to reach a relatively high pressure; it can also achieve constant-pressure full gas release equal to the designed intake pressure of the expander through the constant pressure of the water environment, and the gas can be completely released through the water pressure of the water environment without bottom cushion gas, making full use of the gas storage volume, and both the energy storage efficiency and the energy storage density are improved. Different from the constant-volume compressed air energy storage system, in the water environment, after the flexible airbag releases gas, there is no pressure difference inside and outside the entire underwater compressed air energy storage device; there is no need for special geological structures and high-pressure storage tanks to bear the high-pressure air, significantly reducing 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 the internal air pressure during the process of charging and discharging gas to achieve the effect of stabilizing the internal pressure.

[0010] Optionally, the other end of the flexible airbag is connected to the plug. Beneficial effects: By adopting the above technical solutions, the present application ensures the stable and reliable setting of the airbag.

[0011] Optionally, the water passing holes are multiple and evenly distributed on the edge of the plug; the other end of the flexible airbag is connected to the center of the plug. Beneficial effects: By adopting the above technical solutions, through the arrangement of multiple evenly distributed water passing holes, the water flow is uniform and stable; moreover, by using multiple water passing holes with a smaller diameter, the purpose of splitting the channel of the water passing port can be achieved. 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 passing port.

[0012] Optionally, the rigid outer shell is in a cylindrical shape.

[0013] Optionally, the inner side of the water passing port is a conical surface flaring structure, and the plug is provided with a conical surface structure adapted to the shape of the conical surface flaring structure. Beneficial effect: By adopting the above technical solution in the present application, it is ensured that the plug can stably and reliably block the water passing port.

[0014] In a second aspect, the present invention further provides an energy storage system, including: the underwater compressed air energy storage device described above.

[0015] Optionally, it further includes:

[0016] A compressor unit, connected to the air vent of the flexible airbag through a first valve;

[0017] An expander unit, connected to the air vent of the flexible airbag through a second valve;

[0018] 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 injects gas into the flexible airbag; and a second state in which the expander unit is started, the first valve is closed, the second valve is opened, and the flexible airbag provides intake air for the expander. Beneficial effect: By adopting the above technical solution in the present application, during the process of charging and storing energy for the underwater compressed air energy storage device, it is a process of constant pressure first and then variable pressure, reducing the variable operating range of the compressor unit. The compressor unit basically operates in the high-efficiency area, significantly improving the working efficiency of the compressor unit; during the process of discharging and releasing energy for the underwater compressed air energy storage device, it is a process of variable pressure first and then constant pressure, and the variable operating range of the expander unit is small. The expander unit basically operates in the high-efficiency area, significantly improving the working efficiency of the expander unit; enabling the operating efficiency of the energy storage system in the present application to be significantly improved under all operating conditions of energy storage and energy release.

[0019] Optionally, it further includes:

[0020] A first heat exchanger assembly, arranged at the output port of the compressor unit, and the first heat exchanger assembly is adapted to collect the compressed heat energy generated by the compressor unit;

[0021] A first heat storage structure, connected to the first heat exchanger assembly, and the first heat exchanger assembly is adapted to transport the compressed heat energy to the first heat storage structure for storage;

[0022] A second heat exchanger assembly, arranged at the input port of the expander unit, and the second heat exchanger assembly is connected to the first heat storage structure. The second heat exchanger assembly is adapted to heat the intake air of the expander unit by using the compressed heat energy transmitted by the second heat exchanger assembly;

[0023] The second heat storage structure is connected to both the second heat exchanger assembly and the first heat exchanger assembly. The second heat storage structure is adapted to store the heat storage medium after heat exchange by the second heat exchange assembly and circulate and transport the heat storage medium into the first heat exchanger assembly. Beneficial effects: By adopting the above technical solution, the present application makes full use of 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 work efficiency of the expander, further reduce costs, and improve the efficiency.

[0024] Optionally, the heat storage medium is water. 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.

[0025] Optionally, the first heat exchanger assembly includes at least two coolers connected together;

[0026] The compressor unit includes at least two compressors connected together, and each cooler is respectively arranged at the exhaust port of a different compressor;

[0027] The second heat exchanger assembly includes at least two reheaters connected together;

[0028] The expander unit includes at least two expanders connected together, and each reheater is respectively arranged at the intake port of a different expander. Description of the Drawings

[0029] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a three-dimensional structural schematic diagram of the underwater compressed air energy storage device provided in the embodiment of the present invention;

[0031] Figure 2 It is a sectional structural schematic diagram of the underwater compressed air energy storage device provided in the embodiment of the present invention;

[0032] Figure 3 It is a partial sectional structural schematic diagram of the underwater compressed air energy storage device provided in the embodiment of the present invention Figure 1 ;

[0033] Figure 4 It is a partial sectional structural schematic diagram of the underwater compressed air energy storage device provided in the embodiment of the present invention Figure 2 ;

[0034] Figure 5 Schematic diagram of the partial front view structure of the underwater compressed air energy storage device provided in the embodiment of the present invention;

[0035] Figure 6 Schematic diagram of the sectional view structure of the plug provided in the embodiment of the present invention;

[0036] Figure 7 Schematic diagram of the front view structure of the plug provided in the embodiment of the present invention;

[0037] Figure 8 Schematic diagram of the left view structure of the plug provided in the embodiment of the present invention;

[0038] Figure 9 Schematic diagram of the right view structure of the plug provided in the embodiment of the present invention;

[0039] Figure 10 Schematic diagram of the sectional view when the flexible airbag is filled with gas provided in the embodiment of the present invention;

[0040] Figure 11 Schematic diagram of the sectional view when half of the gas is released from the flexible airbag provided in the embodiment of the present invention;

[0041] Figure 12 Schematic diagram of the sectional view when all the gas is released from the flexible airbag provided in the embodiment of the present invention;

[0042] Figure 13 Schematic diagram of the connection of the energy storage system provided in the embodiment of the present invention.

[0043] Explanation of reference numerals:

[0044] 1, rigid outer shell; 2, plug; 3, flexible airbag; 4, air vent; 5, water inlet; 6, water passing 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, water level. Detailed implementation manners

[0045] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] For a constant-volume compressed air energy storage system, if the pressure in the gas storage reservoir is increased, special geological structure caves and high-cost artificial chambers need to be used to store high-pressure gas; however, the caves or artificial chambers cannot be completely depressurized, otherwise there will be a risk of collapse, and there is a large amount of cushion gas and low energy storage density. For a constant-pressure compressed air energy storage system, an underwater flexible gas storage method can be adopted. 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 very deep water to store gas with a pressure of 7 MPa to 10 MPa. Currently, most of the offshore wind power is in the shallow water area within 100 meters of water depth, with few deep-water environments and high construction costs in deep-water areas. For the above reasons, this application proposes an underwater compressed air energy storage device.

[0047] As Figures 1 to 12 shown in a specific embodiment of the underwater compressed air energy storage device, it includes: a rigid outer shell 1, a flexible airbag 3, and a plug 2. The underwater compressed air energy storage device described in this application is very suitable for the demand of building large-scale long-term energy storage in low-pressure medium-shallow water areas.

[0048] As Figures 1 to 4 shown, the rigid outer shell 1 has a cavity, and a water inlet 5 communicating the cavity with the external water environment is provided at one end of the rigid outer shell 1; specifically, the rigid outer shell 1 is in a cylindrical shape. The rigid outer shell 1 described in this application is an open structure and can be made of composite materials. The flexible airbag 3 is located in the cavity, and an air vent 4 provided at one end of the flexible airbag 3 is arranged on a through hole at the other end of the rigid outer shell 1; it can be that the air vent 4 is fixed on the through hole. The flexible airbag 3 described in this application is a closed structure and can be an inner bladder made of composite materials. As Figures 5 to 8 shown, the plug 2 slides in the cavity, and the plug 2 is located between the water inlet 5 and the flexible airbag 3; and a water passing hole 6 is provided on the plug 2. Specifically, as Figure 8 shown, the water passing holes 6 are a plurality of evenly distributed on the edge of the plug 2, and the number of the water passing holes 6 can be eight evenly spaced.

[0049] As Figures 10 to 12As shown, the underwater compressed air energy storage device has a process of introducing gas into the flexible airbag 3 through the air vent 4, causing the flexible airbag 3 to expand and fit against the inner wall of the rigid outer shell 1, and the flexible airbag 3 pushing the plug 2 to slide to the water passing port 5. At the same time, the water between the flexible airbag 3 and the inner wall of the rigid outer shell 1 is discharged to the external water environment through the water passing holes 6 and the water passing port 5, which is the energy storage state; and it has a process of the flexible airbag 3 discharging gas outward through the air vent 4, and the plug 2 sliding under the pressure of the external water environment to push the flexible airbag 3 to compress its volume. At the same time, the water in the external water environment flows through the water passing port 5 and the water passing holes 6 to the space between the flexible airbag 3 and the inner wall of the rigid outer shell 1 to further compress the flexible airbag 3, which is the energy release state. Refer to Figure 13 , the air vent 4 of the present application is adapted to be connected to the expander 18. Specifically, the gas can be air. During the process of charging and energy storage, it is first at a constant pressure and then at a variable pressure. During the process of discharging and energy release, it is first at a variable pressure and then at a constant pressure.

[0050] Furthermore, as Figure 12 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.

[0051] Furthermore, as Figure 3 shown, the inner side of the water passing port 5 is a conical surface flared structure, and the plug 2 is provided with a conical surface structure that is shape-matched with the conical surface flared structure.

[0052] The underwater compressed air energy storage device of 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 inside the flexible airbag 3 can be not less than 10 MPa, or it can also be below 10 MPa.

[0053] As Figures 10 to 12As shown in the figure, the underwater compressed air energy storage device described in the present application is in the water environment at a certain depth for a long time and bears the water pressure from the external water environment. When a certain pressure of air 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 outer shell 1 is discharged from the rigid outer shell 1 as the space occupied by the flexible airbag 3 increases until the flexible airbag 3 is completely filled. The plug 2 blocks the water inlet 5 of the rigid outer shell 1. When continuing to inflate the flexible airbag 3, the rigid outer shell 1 bears the pressure. The rigid outer shell 1 only needs to bear the pressure difference between the water pressure and the air pressure, thereby reducing the thickness of the rigid outer shell 1 and reducing the cost. When deflating, the air pressure inside the flexible airbag 3 first decreases. When it reaches the same as the water pressure, the water pushes the plug 2 to slide. The water enters one side of the flexible airbag 3 through the water passing hole 6 on the plug 2 to supplement the increased internal space due to deflation. Under the natural constant temperature and constant pressure condition of water, the flexible airbag 3 deflates outward, and the output gas pressure is constant. And there is no pressure difference inside and outside after the gas is emptied. Under the same gas storage pressure, the cost is lower.

[0054] As Figure 13 shown in the figure, the present invention also provides an energy storage system, including: the underwater compressed air energy storage device described above. The parts of the energy storage system described in the present application other than the underwater compressed air energy storage device are all above the horizontal plane 19, that is, not located in the external water environment.

[0055] As Figure 13 shown in the figure, the energy storage system described in the present application further includes: a compressor unit and an expander unit. The compressor unit is connected to the air vent 4 of the flexible airbag 3 through a first valve 7; the expander unit is connected to the air vent 4 of the flexible airbag 3 through a second valve 8. The energy storage system has a first state of starting the compressor unit, opening the first valve 7, closing the second valve 8, and the compressor unit introducing gas into the flexible airbag 3; and a second state of starting the expander unit, closing the first valve 7, opening the second valve 8, and the flexible airbag 3 providing intake air for the expander. Specifically, the first valve 7 is a switch valve, and the second valve 8 is a regulating valve. Among them, Figure 13 the arrows in the figure indicate the flow direction of the gas. The arrow at the uppermost left end indicates intake air, and the arrow at the lowermost left end indicates exhaust air.

[0056] As Figure 13As shown in the figure, the energy storage system described in this application further 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 adapted to collect the compressed heat energy generated by the compressor unit through heat exchange. The first heat storage structure 9 is connected to the first heat exchanger assembly, and the first heat exchanger assembly is adapted to transport the compressed 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. The second heat exchanger assembly is adapted to heat the intake air of the expansion unit through heat exchange by using the compressed 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. The second heat storage structure 10 is adapted to store the heat storage medium after heat exchange of the second heat exchange component and circulate the heat storage medium to the inside of the first heat exchanger assembly.

[0057] Specifically, as Figure 13 shown, the heat storage medium is water. 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.

[0058] Specifically, as Figure 13 shown, the first heat exchanger assembly includes: two coolers 15 connected and arranged; the compressor unit includes: two compressors 16 connected and arranged, 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 and arranged; the expansion unit includes: two expanders 18 connected and arranged, and the two reheaters 17 are respectively arranged at the intake ports of the two expanders 18.

[0059] Although the embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations fall within the scope defined by the appended claims.

Claims

1. An underwater compressed air energy storage device, characterized in that, Comprising: A rigid outer shell (1) having a cavity, and a water inlet (5) communicating the cavity with the external water environment is provided at one end of the rigid outer shell (1); A flexible airbag (3) located within the cavity, and an air vent (4) provided at one end of the flexible airbag (3) is disposed on a through hole at the other end of the rigid outer shell (1); A plug (2) sliding within the cavity, the plug (2) being located between the water inlet (5) and the flexible airbag (3); and a water passage hole (6) is provided on the plug (2); The underwater compressed air energy storage device has a state of storing energy by introducing gas into the flexible airbag (3) through the air vent (4), the flexible airbag (3) expanding to fit against the inner wall of the rigid outer shell (1), and the flexible airbag (3) pushing the plug (2) to slide to the water inlet (5). At the same time, the water between the flexible airbag (3) and the inner wall of the rigid outer shell (1) is discharged to the external water environment through the water passage hole (6) and the water inlet (5); and has a state of releasing energy in which the flexible airbag (3) releases gas outward through the air vent (4), the plug (2) slides under the pressure of the external water environment to push the flexible airbag (3) to compress its volume. At the same time, the water in the external water environment flows through the water inlet (5) and the water passage hole (6) to between the flexible airbag (3) and the inner wall of the rigid outer shell (1) to continue compressing the flexible airbag (3); The other end of the flexible airbag (3) is connected to the plug (2); The water passage 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).

2. The underwater compressed air energy storage device according to claim 1, wherein The rigid outer shell (1) is in the shape of a cylinder.

3. The underwater compressed air energy storage device according to claim 1, characterized in that, The inner side of the water inlet (5) is a conical surface flared structure, and the plug (2) is provided with a conical surface structure adapted to the shape of the conical surface flared structure.

4. An energy storage system, characterized in that, Comprising: The underwater compressed air energy storage device according to any one of claims 1-3.

5. The energy storage system according to claim 4, wherein Further comprising: A compressor unit connected to the air vent (4) of the flexible airbag (3) through a first valve (7); An expander unit connected to the air vent (4) of the flexible airbag (3) through a second valve (8); The energy storage system has a first state of starting the compressor unit, opening the first valve (7), closing the second valve (8), and the compressor unit introducing gas into the flexible airbag (3); and has a second state of starting the expander unit, closing the first valve (7), opening the second valve (8), and the flexible airbag (3) providing intake air for the expander.

6. The energy storage system according to claim 5, characterized in that, Further comprising: A first heat exchanger assembly provided at the output of the compressor unit, and the first heat exchanger assembly is adapted to collect the compressed heat energy generated by the compressor unit; A first heat storage structure (9) connected to the first heat exchanger assembly, and the first heat exchanger assembly is adapted to transfer the compressed heat energy to the first heat storage structure (9) for storage; A second heat exchanger assembly provided at the input of the expander unit, and the second heat exchanger assembly is connected to the first heat storage structure (9), and the second heat exchanger assembly is adapted to heat the intake air of the expander unit using the compressed 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. The second heat storage structure (10) is adapted to store the heat storage medium after heat exchange by the second heat exchange component and circulate and transport the heat storage medium into the first heat exchanger assembly.

7. The energy storage system according to claim 6, wherein The heat storage medium is water. 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.

8. The energy storage system according to claim 6 or 7, wherein The first heat exchanger assembly includes at least two coolers (15) connected and arranged; The compressor unit includes at least two compressors (16) connected and arranged, and each cooler (15) is respectively arranged at the exhaust port of a different compressor (16); The second heat exchanger assembly includes at least two reheaters (17) connected and arranged; The expansion unit includes at least two expanders (18) connected and arranged, and each reheater (17) is respectively arranged at the intake port of a different expander (18).

Images