Offshore compressed gas energy storage method and device

Abstract

The method comprises the steps that a movable or fixed ocean platform is established on the sea, a power motor, an air compressor and an expansion machine are installed on the ocean platform, the expansion machine is in transmission connection with a power generation motor, and a gas storage tank with an upward opening is fixed to the seabed; a piston pulled by a power motor is installed in an air storage tank, an air inlet and an air outlet of the air storage tank are connected with an air compressor and an expansion machine pipeline respectively, in the initial state, the piston is located at the bottom of the air storage tank, the power motor is electrically driven to pull the piston to rise during energy storage, and micro negative pressure is formed in the air storage tank; meanwhile, the air compressor presses air into the air storage tank, electric energy is converted into air compression energy to be stored, during energy release, the piston is released, high-pressure air is pressed out, the high-pressure air is expanded through the expansion machine and then pushes the impeller to rotate, the power generation motor rotates to generate power, and the air compression energy is converted into electric energy; and electric energy storage of the compressed air is realized through energy storage and release circulation.

Description

Technical Field

[0001] The invention relates to offshore air compression energy storage technology, in particular to a method and device for storing compressed gas energy at sea. Background Art

[0002] With the advancement of energy structure reform, the proportion of new energy power generation such as solar energy, wind energy, and tidal energy has increased rapidly. Both wind power generation and photovoltaic power generation have significant intermittency and volatility. Energy storage technology is a key technology to improve the stability and absorption level of new energy power generation systems. Among them, compressed air energy storage technology is one of the most promising physical energy storage technologies. When there is surplus electricity, excess electricity is stored through compressed air. When electricity is needed, compressed air is released to drive the expander to generate electricity. Conventional compressed air is mostly stored in caves, abandoned mines or solid gas tanks on land. Caves and mines are very limited by natural geographical conditions, especially offshore wind farms far away from land. It is difficult to find caves and mines. In addition, since the volume of the storage space remains unchanged, the air pressure continues to increase during the conventional compressed air energy storage process, and the air pressure continues to decrease during the energy release process. The compressor and expander need to work within a wide pressure range, resulting in a decrease in the system's power generation efficiency. Summary of the invention

[0003] In order to overcome the deficiencies of the prior art, the present invention provides a method and device for storing compressed gas energy at sea.

[0004] The technical solution adopted by the present invention to solve the technical problem is: A method for storing compressed gas energy at sea, the method comprising: establishing a mobile or fixed marine platform at sea, installing a power motor, an air compressor, and an expander on the marine platform, the expander being transmission-connected to a generator motor, fixing an air storage tank with an upward opening on the seabed, installing a piston pulled by the power motor in the air storage tank, an air inlet of the air storage tank being connected to a pipeline of the air compressor, and an exhaust port of the air storage tank being connected to a pipeline of the expander, the piston being located at the bottom of the air storage tank in an initial state, and during energy storage, the power motor is electrically driven to pull the piston upward, so that a slight negative pressure is formed in the air storage tank, and at the same time, the air compressor compresses air into the air storage tank, converts electrical energy into air compression energy and stores it, and during energy release, the piston is released, and the high-pressure gas in the air storage tank is pressed out, and after being expanded by the expander, the high-pressure gas pushes the expander impeller to rotate, thereby driving the generator motor to rotate and generate electricity, converting air compression energy into electrical energy, and realizing electrical energy storage of compressed air through energy storage and release cycles.

[0005] A device for storing compressed gas energy at sea, wherein a mobile or fixed marine platform is established at sea, and the marine platform is equipped with a power motor, an air compressor, and an expander. The expander is transmission-connected to a generator motor, and an air storage tank with an upward opening is fixed on the seabed. A piston pulled by the power motor is installed in the air storage tank, the air inlet of the air storage tank is connected to the air compressor pipeline, and the exhaust port of the air storage tank is connected to the expander pipeline.

[0006] A pulley block and a winch drum driven by the power motor are installed on the offshore platform. A transmission cable is passed through the pulley block. One end of the transmission cable is wound around the winch drum, and the other end is fixed to the piston.

[0007] The offshore platform is provided with a first through hole for passing the transmission cable, a first wire pressing guide wheel group is installed on the side wall of the first through hole, and the transmission cable is passed through the first wire pressing guide wheel group.

[0008] A second wire pressing guide wheel group is installed at the upper end of the gas storage tank, and the transmission cable is passed through the second wire pressing guide wheel group.

[0009] A limiting ring is arranged at the upper end of the gas storage tank. When energy storage is completed, the top edge of the piston abuts against the bottom surface of the limiting ring.

[0010] Flexible sealing rings are provided on the bottom surface of the limiting ring and the edge of the top surface of the piston. When energy storage is completed, the flexible sealing rings are squeezed and deformed to seal the gas storage tank.

[0011] A sealing ring is arranged between the outer side of the piston and the gas storage tank.

[0012] The air outlet end of the air compressor is connected to an air inlet valve, and the air inlet end of the air compressor is connected to a gas filter.

[0013] The air inlet end of the expander is connected to a gas dryer, and the air inlet end of the gas dryer is connected to an air outlet valve.

[0014] The beneficial effects of the present invention are: When releasing energy, the piston moves downward, the air storage space gradually decreases, the air pressure fluctuation decreases, and the air exhaust rate increases, thereby improving the working efficiency of the expander and the power generation efficiency of the system.

[0015] The gas tank is installed on the seabed at a fixed depth. The pressure inside and outside the gas tank is relatively balanced, which can reduce the wall thickness of the gas tank to a certain extent and help stabilize the compressed air pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 is a schematic diagram of the present invention; Figure 2 yes Figure 1 A is an enlarged view of the middle image. DETAILED DESCRIPTION

[0018] To make the purpose, technical solution and advantages of the present invention more clear, the present invention is further described in detail below in combination with specific implementations and with reference to the accompanying drawings. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0019] It is to be understood that these descriptions are exemplary only and are not intended to limit the scope of the invention.

[0020] Some embodiments of the present invention are described below in conjunction with the accompanying drawings.

[0021] Reference Figure 1-2 , a method for storing compressed gas energy at sea, the method comprises: establishing a mobile or fixed marine platform at sea, installing a power motor, an air compressor, and an expander on the marine platform, the expander being connected to a generator motor in a transmission manner, fixing an air storage tank with an upward opening on the seabed, and installing a piston pulled by the power motor in the air storage tank, the air inlet of the air storage tank being connected to the air compressor pipeline, and the exhaust port of the air storage tank being connected to the expander pipeline, in an initial state, the piston is located at the bottom of the air storage tank, during energy storage, the power motor is driven by electricity to pull the piston upward, so that a slight negative pressure is formed in the air storage tank, and at the same time, the air compressor compresses air into the air storage tank, converts electrical energy into air compression energy and stores it, during energy release, the piston is released, and the high-pressure gas in the air storage tank is pressed out, and after being expanded by the expander, the impeller of the expander is driven to rotate, thereby driving the generator motor to rotate and generate electricity, converting air compression energy into electrical energy, and realizing electrical energy storage of compressed air through energy storage and release cycles.

[0022] A device for storing compressed gas energy at sea, wherein a mobile or fixed marine platform 1 is established at sea, wherein the marine platform 1 is equipped with a power motor 2, an air compressor 3, and an expander 4, wherein the expander 4 is transmission-connected to a generator motor 5, and an air storage tank 6 with an opening upward is fixed on the seabed, wherein a piston 7 pulled by the power motor 2 is installed in the air storage tank 6, wherein an air inlet of the air storage tank 6 is connected to a pipeline of the air compressor 3, and an exhaust port of the air storage tank 6 is connected to a pipeline of the expander 4.

[0023] When the gas tank 6 is installed on the seabed at a depth of 100 meters (the fixing of the gas tank 6 is the prior art), the seawater pressure it is subjected to is 10 atmospheres, that is, when the pressure of the compressed air in the gas tank 6 is also 10 atmospheres, after it is released, after passing through the expander 4, one unit of compressed air will be expanded into 10 units of ordinary air. At the same time, as the compressed air in the gas tank 6 decreases, the piston will gradually move downward, reducing the actual usable space in the gas tank 6, reducing air pressure fluctuations, and contributing to the stability of the compressed air pressure. At the same time, the exhaust rate of the air is increased, thereby improving the working efficiency of the expander and the power generation efficiency of the system.

[0024] The marine platform 1 can be a fixed platform on the seawater, such as a booster tank of offshore wind power, an oil drilling platform, etc., or a floating body on the sea, such as a large ship. It has little impact on the inland environment, will not occupy farmland or land, and will not affect the surrounding transportation and production and living environment. The vast sea area provides sufficient space and there is no need to worry about occupation issues. There is no need to build high towers or dig deep wells like energy storage projects such as solid gravity potential energy storage. Only the characteristics of the ocean depth can be used to easily solve the space problem of rising and falling heavy objects, which is more suitable for large-scale engineering construction.

[0025] The marine platform 1 is provided with a pulley block 8 and a winch drum 9 driven by the power motor 2, a transmission cable 10 is passed through the pulley block 8, one end of the transmission cable 10 is wound around the winch drum 9, and the other end is fixed to the piston 7. When storing energy, since the seabed has a certain depth, the existing air compressor cannot quickly press the air into the air tank 6. Therefore, the present application uses the power motor 2, the pulley block 8, etc. to pull the piston 7, so that the piston 7 is easier to move up. In actual use, the power motor 2 first pulls the piston 7 a short distance to form a slightly negative pressure state in the air tank 6, so that the air compressor 3 can more easily press the air into the air tank 6.

[0026] The length of the transmission cable 10 is long enough. Even if the piston 7 descends to the lowest point, a certain length is still wound on the winch drum 9. In addition, the end of the transmission cable 10 is fixed on the marine platform 1 to avoid the situation where the mobile marine platform drifts away from the original position (i.e., directly above the gas tank 6). Even if the transmission cable on the winch drum 9 is completely released, the two ends of the transmission cable 10 are still connected to the marine platform 1 and the piston 7 respectively, to avoid the situation where the marine platform and the gas tank are completely separated.

[0027] The marine platform 1 is provided with a first through hole 11 for passing the transmission cable 10, and a first wire-pressing guide wheel group 12 is installed on the side wall of the first through hole 11, and the transmission cable 10 is passed through the first wire-pressing guide wheel group 12, and a second wire-pressing guide wheel group 13 is installed on the upper end of the gas storage tank 6, and the transmission cable 10 is passed through the second wire-pressing guide wheel group 13. The functions of the first wire-pressing guide wheel group 12 and the second wire-pressing guide wheel group 13 are to make the two ends of the transmission cable 10 parallel to the running directions of the pulley group 8 and the piston 7 to avoid the occurrence of an angle and a component force, which requires additional work to overcome part of the component force, thereby reducing the efficiency of energy storage. Before formal energy storage, the mobile marine platform 1 needs to be moved to the top of the gas storage tank 6.

[0028] A limiting ring 14 is provided at the upper end of the gas storage tank 6. When energy storage is completed, the top edge of the piston 7 is in contact with the bottom surface of the limiting ring 14. The bottom surface of the limiting ring 14 and the top edge of the piston 7 are both provided with a flexible sealing ring 15. When energy storage is completed, the flexible sealing ring 15 is squeezed and deformed to seal the gas storage tank 6. After compressed air is stored in the gas storage tank 6, since the pressure inside and outside the gas storage tank 6 is the same, theoretically, the seawater outside and the air inside will not flow with each other. However, in reality, due to the activity of molecules, seawater will still enter the gas storage tank 6. Therefore, the present application adds a flexible sealing ring 15 to reduce the amount of seawater in the gas storage tank 6. At the same time, since the pressure inside and outside the gas storage tank 6 is the same, the tube wall of the gas storage tank 6 will not be subjected to pressure. Only during the energy storage stage, the gas storage tank 6 will be in a slightly negative pressure state. Theoretically, the tube wall of the gas storage tank 6 only needs to meet the strength requirement under the slightly negative pressure state, but in practice it needs to meet a certain safety factor, and the wall thickness of the gas storage tank can also be reduced to a certain extent.

[0029] In addition, when energy storage begins, since the gas tank 6 is in a state of slight negative pressure, external seawater will penetrate into the gas tank 6 from the gap between the piston 7 and the gas tank 6 (since the pressure difference between the inside and outside of the gas tank 6 is not too large, the amount of seawater that penetrates will not be particularly large, and the space in the gas tank 6 is mostly filled with compressed gas). When energy is released, the compressed air in the gas tank 6 will carry some seawater when it is discharged. Therefore, the air inlet end of the expander 4 is connected to a gas dryer 18, and the air inlet end of the gas dryer 18 is connected to an air outlet valve 19 to prevent seawater from entering the expander 4 and corroding such electrical equipment, thereby reducing its service life. At the same time, a sealing ring is provided between the outer side of the piston 7 and the gas tank 6 to reduce the amount of seawater that penetrates.

[0030] The piston 7 has sufficient strength and a certain thickness. A plurality of sealing rings may be installed on the piston 7. In addition, a water-absorbing and swelling material may be inserted in the center of the sealing ring. When seawater penetrates, the material absorbs water and swells, further increasing the sealing performance of the sealing ring.

[0031] The air outlet end of the air compressor 3 is connected to an air inlet valve 16 , and the air inlet end of the air compressor 3 is connected to a gas filter 17 .

[0032] In the present invention, the term "plurality" means two or more than two, unless otherwise clearly defined. The term "and / or" used herein includes any and all combinations of one or more of the related listed items. The terms "install", "connect", "connect", "fix" and the like should be understood in a broad sense. For example, "connect" can be a fixed connection, a detachable connection, or an integral connection; "connect" can be a direct connection or an indirect connection through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0033] It should be noted that when an element is referred to as being "assembled on", "installed on", "fixed on" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0034] In the description of this specification, the description of the terms "one embodiment", "some embodiments", "specific embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0035] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for storing compressed gas energy at sea, characterized in that The method is to establish a mobile or fixed marine platform at sea, and install a power motor, an air compressor, and an expander on the marine platform. The expander is connected to a generator motor in a transmission manner. An air storage tank with an opening upward is fixed on the seabed. A piston pulled by the power motor is installed in the air storage tank. The air inlet of the air storage tank is connected to the air compressor pipeline, and the exhaust port of the air storage tank is connected to the expander pipeline. In the initial state, the piston is located at the bottom of the air storage tank. When storing energy, the power motor is driven by electricity to pull the piston up, so that a slight negative pressure is formed in the air storage tank. At the same time, the air compressor compresses air into the air storage tank, converts electrical energy into air compression energy and stores it. When releasing energy, the piston is released, and the high-pressure gas in the air storage tank is pressed out. After being expanded by the expander, the impeller of the expander is driven to rotate, thereby driving the generator motor to rotate and generate electricity, converting air compression energy into electrical energy, and realizing electrical energy storage of compressed air through energy storage and release cycles.

2. A device for storing compressed gas energy at sea, characterized in that A mobile or fixed marine platform (1) is established at sea. The marine platform (1) is equipped with a power motor (2), an air compressor (3), and an expander (4). The expander (4) is connected to a generator motor (5) in a transmission manner. An air storage tank (6) with an opening facing upward is fixed on the seabed. A piston (7) pulled by the power motor (2) is installed in the air storage tank (6). The air inlet of the air storage tank (6) is connected to a pipeline of the air compressor (3), and the air outlet of the air storage tank (6) is connected to a pipeline of the expander (4).

3. The device for storing compressed gas energy at sea according to claim 2, characterized in that The offshore platform (1) is provided with a pulley block (8) and a winch drum (9) driven by the power motor (2); a transmission cable (10) is passed through the pulley block (8); one end of the transmission cable (10) is wound around the winch drum (9) and the other end is fixed to the piston (7).

4. The device for storing compressed gas energy at sea according to claim 3, characterized in that The offshore platform (1) is provided with a first through hole (11) for passing the transmission cable (10), a first wire pressing guide wheel group (12) is installed on the side wall of the first through hole (11), and the transmission cable (10) is passed through the first wire pressing guide wheel group (12).

5. The device for storing compressed gas energy at sea according to claim 3, characterized in that A second wire pressing guide wheel assembly (13) is mounted on the upper end of the gas storage tank (6), and the transmission cable (10) is passed through the second wire pressing guide wheel assembly (13).

6. The device for storing compressed gas energy at sea according to claim 2, characterized in that A limiting ring (14) is provided at the upper end of the gas storage tank (6), and when energy storage is completed, the edge of the top surface of the piston (7) abuts against the bottom surface of the limiting ring (14).

7. The device for storing compressed gas energy at sea according to claim 6, characterized in that A flexible sealing ring (15) is provided on the bottom surface of the limiting ring (14) and the edge of the top surface of the piston (7). When energy storage is completed, the flexible sealing ring (15) is squeezed and deformed to seal the gas storage tank (6).

8. The device for storing compressed gas energy at sea according to claim 2, characterized in that A sealing ring is provided between the outer side of the piston (7) and the gas storage tank (6).

9. The device for storing compressed gas energy at sea according to claim 2, characterized in that The air outlet end of the air compressor (3) is connected to an air inlet valve (16), and the air inlet end of the air compressor (3) is connected to a gas filter (17).

10. The device for storing compressed gas energy at sea according to claim 2, characterized in that The air inlet end of the expander (4) is connected to a gas dryer (18), and the air inlet end of the gas dryer (18) is connected to an air outlet valve (19).

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