Underwater compressed air energy storage system

Abstract

The invention discloses an underwater compressed air energy storage system which comprises an air bag arranged in natural water sources such as ocean, an anchoring system arranged in water and connected with the air bag, the air bag fixed in the water through the anchoring system, an input system connected with the air bag and capable of inflating air into the air bag, and a power generation system connected with the air bag. The air bag releases air which can be used for power generation of a power generation system. The internal and external pressure difference of the gas storage device is small, the requirement for the pressure bearing capacity of the pressure container is remarkably reduced, the investment cost of the gas storage device is reduced, seawater or lake water is directly used for providing external water pressure so as to adapt to different geographical conditions and energy requirements, an environment chamber does not need to be arranged, and the system complexity and cost are reduced.

Description

Technical Field

[0001] The invention relates to an underwater compressed air energy storage system, belonging to the technical field of energy storage systems. Background Art

[0002] my country's offshore wind power and photovoltaic installed capacity is developing rapidly, and corresponding energy storage systems are needed. Pumped storage has a long construction period and is restricted by site selection; traditional compressed air energy storage systems, such as underground salt caverns, are also restricted by geological conditions.

[0003] In the prior art, there is a technology that uses water pressure to store compressed air energy. For example, the patent name is a method for generating electricity by constant pressure using an underwater flexible compressed air energy storage airbag (patent number: CN202310200070.0), which discloses the use of a water-filled environmental chamber and an underwater flexible airbag to store air energy. However, this system requires the construction of equipment such as an environmental chamber, which has high equipment costs, cannot effectively utilize natural resources, and has high system complexity.

[0004] In recent years, my country has made continuous breakthroughs in compressor and turboexpander equipment manufacturing technology, making compressed air energy storage systems no longer restricted by equipment manufacturing. Based on this, we make full use of the marine environment and underwater pressure to propose an underwater compressed air energy storage system. Summary of the invention

[0005] The purpose of the present invention is to provide an underwater compressed air energy storage system. The present invention does not require the installation of an environmental chamber, thereby reducing system complexity and cost, and can be flexibly arranged in the ocean to adapt to different geographical conditions and energy requirements.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solution: an underwater compressed air energy storage system, comprising:

[0007] An airbag, the airbag is placed in water, and a valve switch is provided at the air outlet of the airbag. The airbag is used to store gas. The airbag is placed in a natural water source such as the ocean. The high water pressure enables the airbag to store higher pressure gas.

[0008] An anchoring system, the anchoring system is placed in the water and connected to the airbag, and the airbag is fixed in the water by the anchoring system;

[0009] An input system, wherein the input system is connected to the airbag and can fill the airbag with gas. When the power consumption is low, the input system uses redundant power to fill the airbag with gas, thereby achieving the purpose of storing power;

[0010] The power generation system is connected to the airbag, and the gas released by the airbag can be used for power generation by the power generation system. During peak power consumption, the airbag releases gas to the power generation system to drive the power generation system to generate electricity and feed back electrical energy to the power grid.

[0011] In the aforementioned underwater compressed air energy storage system, the airbag is of capsule type and is made of polyvinyl chloride coated fabric. A reinforcement belt is arranged at the upper part of the side wall of the airbag, and the reinforcement belt is made of multi-layer polyvinyl chloride coated fabric.

[0012] The aforementioned underwater compressed air energy storage system also includes a limiting frame, the airbag is placed inside the limiting frame, the reinforcement belt is connected to the limiting frame by a fixed rope, and an adjusting float is arranged on the top of the limiting frame. The adjusting float ensures that the position of the airbag and the limiting frame will not drop significantly under the minimum pressure of the airbag, and during the initial inflation process, the airbag is not fully expanded and oscillates with the sea water.

[0013] In the aforementioned underwater compressed air energy storage system, the limit frame is made of fiberglass, the surface of which is coated with anti-corrosion paint and is cylindrical in shape to reduce the impact of water flow impact.

[0014] The aforementioned underwater compressed air energy storage system, the anchoring system includes a concrete caisson and a rope, the concrete caisson is connected to one end of the rope, one end of the rope is connected to the bottom of the limiting frame, and the length of the rope is adjustable, which is convenient for adjusting the buried depth of the airbag and then adjusting the initial external pressure.

[0015] In the aforementioned underwater compressed air energy storage system, the concrete caisson is cylindrical and is impregnated with silane for corrosion protection to avoid uneven seawater scouring.

[0016] In the aforementioned underwater compressed air energy storage system, the airbag is connected to a pressure gauge, the pressure gauge is connected to a control system, and the control system is connected to an input system, a power generation system and an airbag valve switch.

[0017] The aforementioned underwater compressed air energy storage system, wherein the input system includes an electric motor, the electric motor is connected to a power grid, the electric motor is connected to a compressor, the output end of the compressor is connected to a gas pipeline, and the other end of the gas pipeline is immersed in the water and connected to an air bag.

[0018] In the aforementioned underwater compressed air energy storage system, the power generation system includes an expander, the input end of the expander is connected to the gas pipeline, the expander is connected to a generator, and the generator is connected to the power grid and the power supply system.

[0019] In the aforementioned underwater compressed air energy storage system, the compression heat exchanger of the compressor and the expansion heat exchanger of the expander are connected to a heat storage unit.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects:

[0021] (1) The gas storage device of the present invention has a small internal and external pressure difference, which significantly reduces the pressure bearing capacity requirements of the pressure vessel and reduces the investment cost of the gas storage device;

[0022] (2) The air storage device of the present invention is made of flexible material and can be retracted and extended, which is convenient for replacement, displacement and recovery. In addition, the airbag itself is made of coated fabric and has the advantages of good sealing and corrosion resistance.

[0023] (3) The present invention can be flexibly deployed in the ocean, directly using seawater or lake water to provide external water pressure to adapt to different geographical conditions and energy requirements, and does not require the installation of an environmental chamber, thereby reducing system complexity and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 is a system schematic diagram of the present invention;

[0025] Figure 2 It is a schematic diagram of the anchoring system and airbag installation structure of the present invention;

[0026] Figure 3 It is a schematic diagram of the airbag and the limiting frame structure of the present invention.

[0027] Figure numerals: 1-airbag, 2-anchoring system, 3-input system, 4-power generation system, 5-limiting frame, 6-reinforcement belt, 7-adjusting float, 8-concrete caisson, 9-rope, 10-pressure gauge, 11-control system, 12-motor, 13-compressor, 14-gas pipeline, 15-expander, 16-generator, 17-compression heat exchanger, 18-expansion heat exchanger, 19-heat storage unit.

[0028] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. DETAILED DESCRIPTION

[0029] Embodiment 1 of the present invention: An underwater compressed air energy storage system, comprising: an airbag 1, wherein the airbag 1 is placed in water, and a valve switch is provided at the air outlet of the airbag 1, the airbag 1 is used to store gas, and the airbag 1 is placed in a natural water source such as the ocean, and the high water pressure enables the airbag 1 to store higher-pressure gas; an anchoring system 2, wherein the anchoring system 2 is placed in water and connected to the airbag 1, and the airbag 1 is fixed in the water through the anchoring system 2; an input system 3, wherein the input system 3 is connected to the airbag 1 and can fill the airbag 1 with gas, and when electricity consumption is low, the input system 3 uses redundant electric energy to fill the airbag 1 with gas, so as to achieve the purpose of storing electric energy; a power generation system 4, wherein the power generation system 4 is connected to the airbag 1, and the gas released by the airbag 1 can be used for power generation by the power generation system 4, and when electricity consumption is peak, the airbag 1 releases gas to the power generation system 4, driving the power generation system 4 to generate electricity and feed back electric energy to the power grid.

[0030] Embodiment 2 of the present invention: An underwater compressed air energy storage system, comprising: an airbag 1, the airbag 1 is placed in water, and a valve switch is provided at the air outlet of the airbag 1, the airbag 1 is used to store gas, the airbag 1 is placed in a natural water source such as the ocean, and the high water pressure enables the airbag 1 to store higher pressure gas; the airbag 1 is capsule-shaped, and the airbag 1 is composed of polyvinyl chloride coated fabric, the tensile strength of the polyvinyl chloride coated fabric is 35-56MPa, the elongation is 2%-40%, and it has certain flexibility, and the thermal conductivity is low, about 4187×10 -5 W / (m·K), the thermal insulation performance of polyvinyl chloride coated fabric is good, and the specific heat capacity is 4.2×10 3 J / (kg·K), thermal expansion coefficient is 10 -5 / ℃, PVC coated fabric has good dimensional stability under temperature changes and high heat resistance. The continuous use temperature can reach 5 ~ 18.5℃, which is suitable for use in a wide temperature range.

[0031] Among them, the airbag 1 is placed inside the limiting frame 5, and a reinforcement belt 6 is arranged on the upper position of the side wall of the airbag 1. The reinforcement belt 6 is connected to the limiting frame 5 through a fixed rope. The limiting frame 5 is made of fiberglass and is cylindrical to reduce the impact of water flow. An adjusting float 7 is arranged on the top of the limiting frame 5. The buoyancy of the adjusting float 7 is preferably the total gravity of the deadweight of the limiting frame 5 and the deadweight of the airbag 1 minus the buoyancy caused by the preset pressure of the airbag 1. The adjusting float 7 ensures that the position of the airbag 1 and the limiting frame 5 will not fall significantly under the minimum pressure of the airbag 1, and that during the initial inflation process, the airbag 1 is not fully expanded and oscillates with the sea water.

[0032] Anchoring system 2, the anchoring system 2 is placed in water and connected to the airbag 1, and the airbag 1 is fixed in the water through the anchoring system 2; input system 3, the input system 3 is connected to the airbag 1 and can fill the airbag 1 with gas, when the power consumption is low, the input system 3 uses redundant power to fill the airbag 1 with gas, so as to achieve the purpose of storing power; power generation system 4, the power generation system 4 is connected to the airbag 1, the gas released by the airbag 1 can be used for power generation system 4 to generate electricity, and when the power consumption is peak, the airbag 1 releases gas to the power generation system 4, which drives the power generation system 4 to generate electricity and feeds power back to the power grid.

[0033] Embodiment 3 of the present invention: An underwater compressed air energy storage system, comprising: an airbag 1, the airbag 1 is placed in water, and a valve switch is provided at the air outlet of the airbag 1, the airbag 1 is used to store gas, the airbag 1 is placed in a natural water source such as the ocean, and the high water pressure enables the airbag 1 to store higher pressure gas; the airbag 1 is capsule-shaped, and the airbag 1 is composed of polyvinyl chloride coated fabric, the tensile strength of the polyvinyl chloride coated fabric is 35-56MPa, the elongation is 2%-40%, and it has a certain flexibility, and the thermal conductivity is low, about 4187×10 -5W / (m·K), the thermal insulation performance of polyvinyl chloride coated fabric is good, and the specific heat capacity is 4.2×10 3 J / (kg·K), thermal expansion coefficient is 10 -5 / ℃, PVC coated fabric has good dimensional stability under temperature changes and high heat resistance. The continuous use temperature can reach 5 ~ 18.5℃, which is suitable for use in a wide temperature range.

[0034] Among them, the airbag 1 is placed inside the limiting frame 5, and a reinforcement belt 6 is arranged on the upper position of the side wall of the airbag 1. The reinforcement belt 6 is connected to the limiting frame 5 through a fixed rope. The limiting frame 5 is made of fiberglass and is cylindrical to reduce the impact of water flow. An adjusting float 7 is arranged on the top of the limiting frame 5. The buoyancy of the adjusting float 7 is preferably the total gravity of the deadweight of the limiting frame 5 and the deadweight of the airbag 1 minus the buoyancy caused by the preset pressure of the airbag 1. The adjusting float 7 ensures that the position of the airbag 1 and the limiting frame 5 will not fall significantly under the minimum pressure of the airbag 1, and that during the initial inflation process, the airbag 1 is not fully expanded and oscillates with the sea water.

[0035] Anchoring system 2, the anchoring system 2 is placed in the water and connected to the airbag 1, and the airbag 1 is fixed in the water through the anchoring system 2; the anchoring system 2 includes a concrete caisson 8 and a rope 9, the concrete caisson 8 is connected to one end of the rope 9, one end of the rope 9 is connected to the bottom of the limiting frame 5, and the length of the rope 9 is adjustable, which is convenient for adjusting the burial depth of the airbag 1, and then adjusting the initial external pressure. The concrete caisson 8 is cylindrical to avoid uneven seawater scouring.

[0036] An input system 3, wherein the input system 3 is connected to the airbag 1 and can fill the airbag 1 with gas. When electricity consumption is low, the input system 3 uses redundant electric energy to fill the airbag 1 with gas, thereby achieving the purpose of storing electric energy; a power generation system 4, wherein the power generation system 4 is connected to the airbag 1, and the gas released by the airbag 1 can be used for power generation by the power generation system 4. When electricity consumption is peak, the airbag 1 releases gas to the power generation system 4, thereby driving the power generation system 4 to generate electricity and feed electric energy back to the power grid.

[0037] Embodiment 4 of the present invention: An underwater compressed air energy storage system, comprising: an airbag 1, the airbag 1 is placed in water, and a valve switch is provided at the air outlet of the airbag 1, the airbag 1 is used to store gas, the airbag 1 is placed in a natural water source such as the ocean, and the high water pressure enables the airbag 1 to store higher pressure gas; the airbag 1 is capsule-shaped, and the airbag 1 is composed of polyvinyl chloride coated fabric, the tensile strength of the polyvinyl chloride coated fabric is 35-56MPa, the elongation is 2%-40%, and it has certain flexibility, and the thermal conductivity is low, about 4187×10 -5 W / (m·K), the thermal insulation performance of polyvinyl chloride coated fabric is good, and the specific heat capacity is 4.2×10 3 J / (kg·K), thermal expansion coefficient is 10-5 / ℃, PVC coated fabric has good dimensional stability under temperature changes and high heat resistance. The continuous use temperature can reach 5 ~ 18.5℃, which is suitable for use in a wide temperature range.

[0038] Among them, the airbag 1 is placed inside the limiting frame 5, and a reinforcement belt 6 is arranged on the upper position of the side wall of the airbag 1. The reinforcement belt 6 is connected to the limiting frame 5 through a fixed rope. The limiting frame 5 is made of fiberglass and is cylindrical to reduce the impact of water flow. An adjusting float 7 is arranged on the top of the limiting frame 5. The buoyancy of the adjusting float 7 is preferably the total gravity of the deadweight of the limiting frame 5 and the deadweight of the airbag 1 minus the buoyancy caused by the preset pressure of the airbag 1. The adjusting float 7 ensures that the position of the airbag 1 and the limiting frame 5 will not fall significantly under the minimum pressure of the airbag 1, and that during the initial inflation process, the airbag 1 is not fully expanded and oscillates with the sea water.

[0039] Anchoring system 2, the anchoring system 2 is placed in the water and connected to the airbag 1, and the airbag 1 is fixed in the water through the anchoring system 2; the anchoring system 2 includes a concrete caisson 8 and a rope 9, the concrete caisson 8 is connected to one end of the rope 9, one end of the rope 9 is connected to the bottom of the limiting frame 5, and the length of the rope 9 is adjustable, which is convenient for adjusting the burial depth of the airbag 1, and then adjusting the initial external pressure. The concrete caisson 8 is cylindrical to avoid uneven seawater scouring.

[0040] The input system 3 is connected to the airbag 1 and can fill the airbag 1 with gas. When the electricity consumption is low, the input system 3 uses the redundant electric energy to fill the airbag 1 with gas, so as to achieve the purpose of storing electric energy. The input system 3 includes an electric motor 12, which is connected to the power grid. The electric motor 12 is connected to a compressor 13. The output end of the compressor 13 is connected to a gas pipeline 14. The other end of the gas pipeline 14 is immersed in the water and connected to the airbag 1.

[0041] The power generation system 4 is connected to the airbag 1. The gas released by the airbag 1 can be used for the power generation system 4 to generate electricity. During peak electricity consumption, the airbag 1 releases gas to the power generation system 4 to drive the power generation system 4 to generate electricity and feed back electric energy to the power grid. The power generation system 4 includes an expander 15. The input end of the expander 15 is connected to the gas pipeline 14. The expander 15 is connected to a generator 16. The generator 16 is connected to the power grid and the power supply system, and the compression heat exchanger 17 of the compressor 13 and the expansion heat exchanger 18 of the expander 15 are connected to a heat storage unit 19.

[0042] The airbag 1 is connected to a pressure gauge 10, and the pressure gauge 10 is connected to a control system 11. The control system 11 is connected to the input system 3, the power generation system 4 and the valve switch of the airbag 1. The control system 11 is used to control the operation of the entire system.

[0043] Working principle of an embodiment of the present invention: When the present invention is in use, in the initial state: the airbag 1 is preset with a certain pressure value, and the pressure value is not 0, to ensure that the airbag 1 is not over-compressed. During low electricity consumption: the surplus electricity of offshore wind power, floating photovoltaic and other power generation systems is used to drive the compressor 13, and the air is transported to the airbag 1 through the gas pipeline 14. The airbag 1 expands until the storage pressure is reached, and the pressure gauge 10 triggers the control system 11 to stop storing air; during peak electricity consumption: the valve switch provided at the air outlet of the airbag 1 is opened to release air, and the airbag 1 is compressed under the external pressure of seawater, and the compressed air in the airbag 1 flows out through the gas pipeline 14, driving the turbine expander 15 to generate electricity until the airbag 1 drops to the preset pressure, and the pressure gauge 10 triggers the control system 11 to stop generating electricity.

[0044] The seabed temperature is relatively low. For example, at 1000m underwater in the South China Sea, the seawater temperature is only 4.4°, which is nearly 10°C lower than the sea surface temperature of 15°C. When the volume of the airbag 1 is large and the charging and discharging rate is slow, combined with the heat exchange performance of the low-temperature seawater around the airbag 1, the gas pipeline 14 is in direct contact with the seawater for sufficient heat transfer, and the thermodynamic process of the air in the airbag 1 can be approximated to an isothermal process.

Claims

1. An underwater compressed air energy storage system, characterized in that: include: An air bag (1), the air bag (1) is placed in water, and a valve switch is provided at the air outlet of the air bag (1); An anchoring system (2), the anchoring system (2) is placed in the water and connected to the airbag (1), and the airbag (1) is fixed in the water by the anchoring system (2); An input system (3), the input system (3) being connected to the airbag (1) and capable of filling the airbag (1) with gas; A power generation system (4) is connected to the air bag (1), and the gas released by the air bag (1) can be used by the power generation system (4) to generate electricity.

2. An underwater compressed air energy storage system according to claim 1, characterized in that: The airbag (1) is of capsule type and is made of polyvinyl chloride coated fabric. A reinforcing belt (6) is arranged at the upper part of the side wall of the airbag (1), and the reinforcing belt (6) is made of multi-layer polyvinyl chloride coated fabric.

3. An underwater compressed air energy storage system according to claim 2, characterized in that: It also comprises a limiting frame (5), the airbag (1) is placed inside the limiting frame (5), the reinforcing belt (6) is connected to the limiting frame (5) via a fixing rope, and an adjusting float (7) is arranged on the top of the limiting frame (5).

4. An underwater compressed air energy storage system according to claim 3, characterized in that: The limiting frame (5) is made of glass fiber reinforced plastic, and the surface of the limiting frame (5) is coated with anti-corrosion paint.

5. The underwater compressed air energy storage system according to claim 3, characterized in that: The anchoring system (2) comprises a concrete caisson (8) and a rope (9), wherein the concrete caisson (8) is connected to one end of the rope (9), one end of the rope (9) is connected to the bottom of the limiting frame (5), and the length of the rope (9) is adjustable.

6. An underwater compressed air energy storage system according to claim 5, characterized in that: The concrete caisson (8) is cylindrical and is impregnated with silane for corrosion protection.

7. The underwater compressed air energy storage system according to claim 1, characterized in that: The airbag (1) is connected to a pressure gauge (10), the pressure gauge (10) is connected to a control system (11), and the control system (11) is connected to an input system (3), a power generation system (4) and a valve switch of the airbag (1).

8. An underwater compressed air energy storage system according to claim 7, characterized in that: The input system (3) comprises an electric motor (12), the electric motor (12) is connected to a power grid, the electric motor (12) is connected to a compressor (13), the output end of the compressor (13) is connected to a gas pipeline (14), and the other end of the gas pipeline (14) is immersed in water and connected to the air bag (1).

9. An underwater compressed air energy storage system according to claim 8, characterized in that: The power generation system (4) comprises an expander (15), the input end of the expander (15) is connected to the gas pipeline (14), the expander (15) is connected to a generator (16), and the generator (16) is connected to a power grid and a power supply system.

10. An underwater compressed air energy storage system according to claim 9, characterized in that: The compression heat exchanger (17) of the compressor (13) and the expansion heat exchanger (18) of the expander (15) are connected to a heat storage unit (19).

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