Compact air compression system for energy storage, power supply system and air compression method for energy storage

Abstract

The present invention relates to a compact air compression system for energy storage, a power supply system, and an air compression method for energy storage, and relates to the field of energy storage technology. The compact air compression system for energy storage comprises a compressor system, a coupled gas storage device, and an air expansion system, wherein the coupled gas storage device comprises a first gas storage device and a second gas storage device. The first gas storage device comprises a tower casing of the wind turbine. The second gas storage device is provided underground, underwater, or suspended in water. A center axis of the compressor system and a center axis of the air expansion system are arranged coaxially with each other, and an input shaft of the compressor system and an output shaft of the air expansion system are detachably connected to a three-in-one electric machine.The present invention can solve the problems of existing air compression energy storage systems: the gas storage devices are limited by geographical conditions, the construction costs are high, the electromechanical devices are distributed, the structure is complex, and the number of equipment and costs are high. The air compression system has the following advantages: it is independent of geographical conditions, has a compact design, and saves space and costs in terms of construction and equipment.

Description

Compact compressed air energy storage system, power system and compressed air energy storage method Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a compact compressed air energy storage system, a power system and a compressed air energy storage method. Background Art

[0002] Large-scale compressed air energy storage technology is a key technology to solve the problems of wind and solar power curtailment, significantly improve the level of new energy consumption, promote the replacement of main energy from fossil energy to renewable energy, and realize distributed energy systems, regional smart microgrids, and friendly source-grid-load-storage.

[0003] Wind conditions on land and at sea vary widely, including steady, gusty, and gradually changing winds. Wind turbine power generation is affected by these wind conditions, resulting in intermittent, fluctuating, and uncontrollable wind power. Fluctuations in wind power grid connection can impact the power grid. Therefore, compressed air energy storage devices are currently used to mitigate grid instability and reduce peak loads. Conventional compressed air energy storage coupled with wind power technology encompasses both onshore and offshore applications, both of which are indirectly connected through the main power grid.

[0004] For the gas storage devices of onshore compressed air energy storage systems, a low-cost method in the existing technology is to use abandoned underground spaces for compressed air energy storage. Flexible airtight polymer films are laid on the inner walls of the underground spaces to store high-pressure air. Specifically, abandoned underground spaces include underground caves, including salt caverns, underground aquifers, hard rock caverns, natural salt caverns, abandoned natural gas, and oil gas storage chambers. However, these abandoned underground spaces are not only restricted by geographical conditions, but also require the laying of long transmission pipelines, which is costly to build.

[0005] Regarding the gas storage devices of offshore compressed air energy storage systems, in the existing technology, the first solution is to build sea-level gas storage devices, which faces problems such as large-scale expropriation of near and far sea areas; the second solution is to build coastal ground gas storage devices, which faces problems such as expensive land expropriation near the coastline.

[0006] In the existing technology, the compressed air energy storage system includes a compression subsystem and an expansion subsystem. Both the compression subsystem and the expansion subsystem need to be connected to mechanical equipment and electrical equipment. However, the mechanical equipment and electrical equipment are scattered and numerous, resulting in high costs for electromechanical equipment.

[0007] Summary of the Invention

[0008] The technical problem to be solved by the present invention is to overcome the defects of compressed air energy storage in the prior art, such as being restricted by geographical conditions, having high costs and complex structures of energy storage systems, thereby providing a compact compressed air energy storage system, a power system and a compressed air energy storage method.

[0009] In order to solve the above problems, the present invention provides a compact compressed air energy storage system, including an air compression system, a combined air storage device, and an air expansion system; the output end of the air compression system is connected to the input end of the combined air storage device, and the output end of the combined air storage device is connected to the input end of the air expansion system; wherein the combined air storage device includes a first air storage device and / or a second air storage device. The first air storage device includes a wind turbine tower, which is provided with a first air storage cavity; the second air storage device is located underground, underwater, or suspended in water, and is provided with a second air storage cavity, and the first air storage cavity and the second air storage cavity are connected; the central axis of the air compression system and the central axis of the air expansion system are coaxially arranged, and the input shaft of the air compression system and the output shaft of the air expansion system are detachably connected to the three-in-one motor.

[0010] Optionally, the tower includes a plurality of tower sections that are axially separated; and the first air storage cavity is provided in one or more tower sections.

[0011] Optionally, the tower includes an outer cylinder and an inner cylinder that are radially sleeved; the annular gap between the outer cylinder and the inner cylinder constitutes a first air storage cavity.

[0012] Optionally, the second gas storage device includes an artificial chamber, the cavity of the artificial chamber constitutes the second gas storage cavity, the artificial chamber is arranged below the tower, and the first gas storage cavity and the second gas storage cavity are connected through or through a pipeline.

[0013] Optionally, the combined gas storage device includes a storage tank fixed on the seabed, the inner cavity of the storage tank constitutes a second gas storage cavity, the storage tank is arranged below the tower, and the first gas storage cavity and the second gas storage cavity are connected through or through a pipeline.

[0014] Optionally, the combined air storage device includes an air bag suspended in water, the inner cavity of the air bag constitutes a second air storage cavity, the first air storage cavity of the tower is provided with an interface, and the air nozzle of the air bag and the interface are connected by a pipeline.

[0015] Optionally, the air compression system includes a multi-stage compressor connected in series, and the central axes of the multi-stage compressors are coaxially arranged; the air expansion system includes a multi-stage gas expander connected in series, and the central axes of the multi-stage gas expander are coaxially arranged; the central axis of the compressor located at the end of the air compression system and the central axis of the gas expander located at the end of the air expansion system are connected through a switching device.

[0016] Optionally, the switching device includes a first clutch detachably connected to the central shaft of the air compression system and a second clutch detachably connected to the central shaft of the air expansion system.

[0017] Optionally, a common heat exchange device is provided between the air compression system and the air expansion system, and the common heat exchange device includes a first heat exchange channel, a second heat exchange channel and a third heat exchange channel; the input end of the first heat exchange channel is connected to the heat output end of the air compression system, and the output end of the first heat exchange channel is connected to the input end of the combined gas storage device; the input end of the second heat exchange channel is connected to the output end of the combined gas storage device, and the output end of the second heat exchange channel is connected to the heat input end of the air expansion system; the third heat exchange channel circulates heat exchange medium.

[0018] A second aspect of the present invention provides an electric power system comprising a power grid, a wind turbine generator set, and a compact compressed air energy storage system described in any one of the above technical solutions, wherein the air compression system is electrically connected to the power grid, or the air compression system is electrically connected to the wind turbine generator set, and the air expansion system is electrically connected to the power grid.

[0019] The third aspect of the present invention provides a compressed air energy storage method, which uses the compact compressed air energy storage system described in any one of the above technical solutions to store air energy, including the following steps: during the energy storage process, the three-in-one motor and the input shaft of the air compression system are connected, the air is compressed and cooled, and the compressed air is stored in a combined air storage device; during the energy release process, the three-in-one motor and the output shaft of the air expansion system are connected, the compressed air stored in the combined air storage device is heated and then injected into the air expansion system for expansion and work output; wherein, "storing the compressed air in the combined air storage device" includes storing the compressed air in the first air storage device and / or the second air storage device.

[0020] Optionally, the heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; and the cold energy generated by compressed air expansion during the energy release process is used to cool the air during the energy storage process.

[0021] Optionally, during the energy storage process, the air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in a combined air storage device.

[0022] The present invention has the following advantages:

[0023] 1. Utilizing the technical solution of the present invention and utilizing the compressed air combined energy storage system or compressed air combined gas storage method provided by the present invention, during energy storage, air is compressed by the air compression system and stored in the combined gas storage device. During energy release, the compressed air in the combined gas storage device is released and output to the air expansion system, where it generates electricity through expansion. The central axis of the air compression system and the central axis of the air expansion system are coaxially arranged, and the input shaft of the air compression system and the output shaft of the air expansion system are detachably connected to the three-in-one motor. This makes the compressed air combined energy storage system more compact and can significantly reduce the cost of mechanical and electrical equipment.

[0024] By setting up a combined gas storage device, wherein a first gas storage cavity is set on the tower, the space of the tower itself can be used as a part of the energy storage space, and a second gas storage device is set up, and the second gas storage device is set up with a second gas storage cavity, and the first gas storage cavity and the second gas storage cavity are connected, so that the second gas storage device and the tower can jointly store gas, which can expand the energy storage space of compressed air. When used on land, the second gas storage device is set underground. Compared with the existing technology of utilizing the underground space of waste gas, the present invention is not restricted by geographical conditions. The second gas storage device can be set close to the tower, shortening the gas transmission pipeline and reducing the construction cost of the energy storage device; when used at sea, the second gas storage device is set underwater or suspended in water. Compared with the existing technology of constructing underground space along the coast, there is no need to occupy expensive land space along the coast, and the length of the gas transmission pipeline is shortened, reducing construction costs;

[0025] The energy storage capacity of the first and second gas storage cavities can be flexibly allocated according to the actual energy storage requirements such as the site selection wind farm, geological conditions, and deep-sea conditions;

[0026] When used at sea, the second air storage device is installed underwater or suspended in water, and the static pressure of the water is used to maintain the constant pressure operation of the compressed air combined energy storage system at sea, avoiding the air compression system and air expansion system from deviating from the design operating conditions and operating inefficiently due to pressure changes, thereby improving the energy conversion efficiency of the system.

[0027] 2. One or more tower sections are arranged axially on the tower, and the first gas storage cavity is arranged in one or more tower sections, or the tower is provided with an outer cylinder and an inner cylinder, and the annular gap between the two constitutes the first gas storage cavity. The setting mode of the first gas storage cavity can be flexibly selected according to the actual situation of the tower. Since the tower itself is a pipeline steel storage tank structure, the internal space structure of the tower can be optimized and utilized to replace the existing underground gas storage space, thereby reducing the construction cost of underground or ground gas storage space.

[0028] 3. By installing a common heat exchanger, the heat energy generated by air compression during the energy storage process can be used to heat the compressed air during the energy release process; the cold energy generated by the expansion of the compressed air during the energy release process can be used to cool the air during the energy storage process. The common heat exchanger is shared by both the energy storage and energy release processes. During energy storage, the air is compressed and cooled, and the pressure potential energy and temperature thermal energy are stored in the combined gas storage device and the common heat exchanger, respectively. During energy release, the high-pressure air in the combined gas storage device is heated by the common heat exchanger, becoming high-pressure, high-temperature air, which is then injected into the gas expander to expand and perform work. Installing a common heat exchanger can not only improve the system's thermal energy utilization rate and enhance system operating efficiency, but also simplify the system structure, reduce occupied space, and reduce construction and operation and maintenance costs, achieving the effect of reducing costs and increasing efficiency.

[0029] 4. By setting up an electromechanical coaxial device, the three-in-one motor, clutch, and impeller machinery of the compression / expansion system are compactly integrated. When storing energy, the three-in-one motor is connected to the input shaft of the air compression system as an electric motor, driving the central shaft of the compressor unit to rotate to achieve air compression and energy conversion. When releasing energy, the three-in-one motor is connected to the output shaft of the air expansion system as a generator, driven by the central shaft of the expansion unit to achieve air expansion and external output. At the same time, the three-in-one motor can be used in the power system as a phase regulator, increasing reactive output when the grid voltage drops, absorbing reactive power when the grid voltage rises, maintaining the grid voltage, improving system stability, and improving the system power supply quality. Setting up an electromechanical coaxial device can, on the one hand, reduce the electromechanical conversion loss caused by multi-axis connection and improve energy conversion efficiency. On the other hand, it is conducive to improving the system integration level and space utilization, saving construction and operation and maintenance costs, and achieving the effect of reducing costs and increasing efficiency.

[0030] 5. The air compression system and air expansion system can compress air to a supercritical state, which can significantly improve system efficiency and reduce the space occupied by gas storage. It can also compress air to a non-supercritical state. The specific gas storage state of the compact compressed air energy storage system can be flexibly selected according to the power and duration of electrical energy required to store electricity during off-peak hours of the wind farm or grid.

[0031] 6. By utilizing the power system of the present invention and directly coupling the compressed air combined energy storage system with an offshore wind farm with relatively high and stable wind speeds, distributed energy storage and regional microgrids can be realized, close to coastal load centers, reducing transmission and distribution costs.

[0032] 7. In the power system, when used at sea, except for the combined gas storage device, the rest can be arranged at sea, which can shorten the gas transmission pipeline. It can also be distributed on land, replacing long-distance gas transmission with long-distance power transmission, which can make full use of compression heat, reduce energy waste, and improve system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] FIG1 shows a schematic structural diagram of a compressed air combined energy storage system provided by an embodiment of the present invention;

[0035] FIG2 shows a schematic structural diagram of a first embodiment of a combined gas storage device in a compressed air combined energy storage system provided by an embodiment of the present invention;

[0036] FIG3 shows a schematic structural diagram of a second embodiment of a combined gas storage device in a compressed air combined energy storage system provided in an embodiment of the present invention;

[0037] FIG4 shows a schematic structural diagram of a third embodiment of the first air storage device in the compressed air combined energy storage system provided by the present invention;

[0038] FIG5 shows a schematic structural diagram of a first embodiment of a first air storage device in a compressed air combined energy storage system provided by the present invention;

[0039] FIG6 shows a schematic structural diagram of a second embodiment of the first air storage device in the compressed air combined energy storage system provided by the present invention;

[0040] FIG7 shows a schematic structural diagram of a common heat exchange device located on the low-pressure side in the compressed air combined energy storage system provided by the present invention;

[0041] FIG8 shows a schematic structural diagram of a compressed air combined energy storage system provided by the present invention in which a common heat exchange device is located on the high-pressure side.

[0042] Explanation of the accompanying symbols: 1. Air compression system; 11. Compressor; 12. Cooler; 2. Combined gas storage device; 21. Tower; 211. Tower section; 212. Outer cylinder; 213. Inner cylinder; 214. First gas storage cavity; 215. Manhole; 216. Connecting pipe; 22. Second gas storage device; 221. Storage tank; 222. Air bag; 223. Second gas storage cavity; 224. Artificial chamber; 3. Air expansion system; 31. Gas expander ; 4. Pressure reducing device; 41. Liquid expansion machine; 5. Pressurizing device; 51. Cryogenic pump; 6. Cold storage heat exchanger; 7. Common heat exchange device; 71. First heat exchange channel; 72. Second heat exchange channel; 73. Third heat exchange channel; 8. Three-in-one motor; 9. Switching device; 91. First clutch; 92. Second clutch; 100. Compact compressed air energy storage system; 300. Wind turbine; 400. First gas storage device. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0044] Example 1

[0045] A compressed air combined energy storage system, referring to Figures 1 to 8, includes an air compression system 1, a combined air storage device 2, and an air expansion system 3. The output end of the air compression system 1 is connected to the input end of the combined air storage device 2, and the output end of the combined air storage device 2 is connected to the input end of the air expansion system 3. The combined air storage device 2 includes a first air storage device 400 and / or a second air storage device 22. The first air storage device 400 includes a wind turbine tower 21, which is provided with a first air storage cavity 214. The second air storage device 22 is located underground, underwater, or suspended in water, and is provided with a second air storage cavity 223. The first air storage cavity 214 and the second air storage cavity 223 are connected. The central axis of the air compression system 1 and the central axis of the air expansion system 3 are coaxially arranged, and the input shaft of the air compression system 1 and the output shaft of the air expansion system 3 are detachably connected to the three-in-one motor 8.

[0046] Utilizing the technical solution of the present invention and the compressed air combined energy storage system or compressed air combined gas storage method provided by the present invention, during energy storage, air is compressed by the air compression system 1 and stored in the combined gas storage device 2. During energy release, the compressed air in the combined gas storage device 2 is released and output to the air expansion system 3, where it generates electricity through expansion. The central axis of the air compression system 1 and the central axis of the air expansion system 3 are coaxially arranged, and the input shaft of the air compression system 1 and the output shaft of the air expansion system 3 are detachably connected to the three-in-one motor 8. This makes the compressed air combined energy storage system structure more compact, significantly reducing the cost of mechanical and electrical equipment.

[0047] By setting up a combined gas storage device 2, wherein the tower 21 is provided with a first gas storage cavity 214, the space of the tower 21 itself can be used as a part of the energy storage space, and a second gas storage device 22 is provided, and the second gas storage device 22 is provided with a second gas storage cavity 223. The first gas storage cavity 214 and the second gas storage cavity 223 are communicated, so that the second gas storage device 22 and the tower 21 can jointly store gas, which can expand the energy storage space of compressed air. When used on land, the second gas storage device 22 is arranged underground. Compared with the prior art that utilizes the underground space of waste gas, the present invention is not restricted by geographical conditions. The second gas storage device 22 can be arranged close to the tower 21, shortening the gas transmission pipeline and reducing the construction cost of the energy storage device. When used at sea, the second gas storage device 22 is arranged underwater or suspended in water. Compared with the prior art that constructs underground space along the coast, there is no need to occupy expensive land space along the coast, and the length of the gas transmission pipeline is shortened, reducing the construction cost.

[0048] The energy storage capacity of the first gas storage cavity 214 and the second gas storage cavity 223 can be flexibly allocated according to the actual energy storage requirements such as the site selection wind farm, geological conditions, deep-sea conditions, etc.;

[0049] When used at sea, the second air storage device 22 is installed underwater or suspended in water, and the static pressure of the water is used to maintain the constant pressure operation of the compressed air combined energy storage system at sea, thereby avoiding the air compression system 1 and the air expansion system 3 from deviating from the design working conditions and operating inefficiently due to pressure changes, thereby improving the energy conversion efficiency of the system.

[0050] Specifically, the output end of the air compression system 1 refers to the port through which the air compression system 1 outputs gas, also known as the air outlet. The input end of the combined air storage device 2 refers to the port through which the combined air storage device 2 inputs compressed air, also known as the air inlet. The output end of the combined air storage device 2 refers to the port through which compressed air is output, also known as the air outlet. The input end of the air expansion system 3 refers to the port through which compressed air is input into the air expansion system 3, also known as the air inlet.

[0051] Optionally, the three-in-one motor 8 integrates a generator, an electric motor, and a phase regulator. When the three-in-one motor 8 is connected to the input shaft of the air compression system 1, it can act as a motor to drive the central axis of the air compression system 1 to rotate, thereby achieving air compression. When the three-in-one motor 8 is connected to the output shaft of the air expansion system 3, it can act as a generator, causing the air to expand and generate electricity. When the three-in-one motor 8 is used as a phase regulator, the phase regulator is a synchronous phase regulator, which is a synchronous motor. When applied to a power system, it can automatically increase reactive power output when the grid voltage drops and absorb reactive power when the grid voltage rises, according to the needs of the system, to maintain voltage, improve the stability of the power system, and improve the power supply quality of the system.

[0052] Optionally, referring to Figure 1, the air compression system 1 includes a multi-stage compressor 11 connected in series, and the central axes of the multi-stage compressor 11 are coaxially arranged; the air expansion system 3 includes a multi-stage gas expander 31 connected in series, and the central axes of the multi-stage gas expander 31 are coaxially arranged; the central axis of the compressor 11 located at the end of the air compression system 1 and the central axis of the gas expander 31 located at the end of the air expansion system 3 are connected through a switching device 9.

[0053] Optionally, the switching device 9 includes a first clutch 91 detachably connected to the central axis of the air compression system 1 and a second clutch 92 detachably connected to the central axis of the air expansion system 3. During energy storage, one output end of the three-in-one motor 8 is connected to the central axis of the air compression system 1 via the first clutch 91, while the second clutch 92 is disconnected. During energy release, the other output end of the three-in-one motor 8 is connected to the central axis of the air expansion system 3 via the second clutch 92, while the first clutch 91 is disconnected.

[0054] Optionally, FIG5 provides a schematic structural diagram of a first embodiment of a tower 21, wherein the tower 21 includes a plurality of tower sections 211 arranged in an axially separated manner; a first gas storage cavity 214 is provided in one or more tower sections 211. Specifically, along the axial direction of the tower 21, a flange is provided at the connecting end of the tower section 211, and two adjacent tower sections 211 are connected by bolts. From bottom to top, the inner diameter of the tower section 211 gradually decreases, and therefore, the capacity of the first gas storage cavity 214 in the plurality of tower sections 211 also decreases from bottom to top. Optionally, a gas storage barrel is provided in the tower section 211, and the inner cavity of the gas storage barrel constitutes the first gas storage cavity 214.

[0055] Optionally, a manhole 215 is provided on the tower section 211 to facilitate entry into the tower 21 for maintenance.

[0056] Alternatively, Figure 6 provides a schematic structural diagram of a second embodiment of a tower 21. Tower 21 includes an outer cylinder 212 and an inner cylinder 213 radially sleeved together. The annular gap between outer cylinder 212 and inner cylinder 213 forms a first air storage cavity 214. Optionally, the length of inner cylinder 213 is equal to that of outer cylinder 212, and the annular gap between inner cylinder 213 and outer cylinder 212 forms the first air storage cavity 214.

[0057] Designers can flexibly select the above two implementation methods of the first gas storage cavity 214 according to the actual situation of the tower 21 and energy storage requirements, so as to fully utilize the internal space of the tower 21.

[0058] When used at sea, referring to Figure 2, the second gas storage device 22 includes a storage tank 221 fixed to the seabed. The inner cavity of the storage tank 221 constitutes a second gas storage cavity 223. The storage tank 221 is arranged below the tower 21, and the bottom of the tower 21 is connected to the storage tank 221. That is, the storage tank 221 can serve as the foundation of the bottom of the tower 21. The bottom of the tower 21 is connected to the storage tank 221, then, the inner cavity of the tower 21 and the inner cavity of the storage tank 221 are directly connected.

[0059] Optionally, referring to Figure 3, the second air storage device 22 includes an airbag 222 suspended in water, the inner cavity of the airbag 222 constitutes a second air storage cavity 223, the tower 21 is provided with an interface, and the air nozzle of the airbag 222 and the interface of the tower 21 are connected by a pipeline to connect the first air storage cavity 214 and the second air storage cavity 223.

[0060] The use of the airbag 222 can realize a compact compressed air energy storage system 100 floating at sea, which can break through the near-shore limitations and avoid multi-functional interference. It is suitable for large-scale floating offshore wind turbines 300 and meets the development needs of the continuously increasing single-unit capacity of offshore wind turbines 300.

[0061] When used at sea, the air compression system 1 and the air expansion system 3 of the compact compressed air energy storage system are arranged coaxially. Due to differences in wind farm resources at sea and on land, the current maximum single-unit capacity of offshore wind turbines 300 has reached 18MW, while the maximum single-unit capacity of onshore wind turbines 300 is about 8MW. Under the same wind farm capacity, the requirements for requisitioned land area are different, and offshore wind turbines 300 have more advantages. In addition, the cost of requisitioning land in the sea is higher and the demand is more urgent. The compact coaxial arrangement can better reflect its value and has the application prospect of integrating a distributed small-capacity compressed air energy storage system into a large offshore wind turbine cabin. When used on land, referring to Figure 4, the second air storage device 22 includes an artificial chamber 224. The cavity of the artificial chamber 224 constitutes a second air storage cavity 223. The artificial chamber 224 is located below the tower 21. The first air storage cavity 214 and the second air storage cavity 223 are connected through or through a pipeline.

[0062] Optionally, the first gas storage cavity 214 and the second gas storage cavity 223 are connected through a connecting pipe 216 .

[0063] Optionally, a pressure reducing device 4 is provided between the air compression system 1 and the combined air storage device 2; the output end of the air compression system 1 is connected to the input end of the pressure reducing device 4, and the output end of the pressure reducing device 4 is connected to the input end of the combined air storage device 2; a pressurizing device 5 is provided between the combined air storage device 2 and the air expansion system 3, the input end of the pressurizing device 5 is connected to the output end of the combined air storage device 2, and the output end of the pressurizing device 5 is connected to the input end of the air expansion system 3.

[0064] The storage states of compressed air include gaseous and non-gaseous states, and the non-gaseous states include liquid and supercritical states.

[0065] As a first embodiment of the compact compressed air energy storage system 100, referring to FIG1 , the air compression system 1 includes a multi-stage compressor 11 connected in series, with a cooler 12 connected to the back of each stage compressor 11; specifically, the cooler 12 includes an intercooler provided between the two compressors 11 and an aftercooler provided downstream of the terminal compressor 11. The air expansion system 3 includes a multi-stage gas expander 31 connected in series, with a reheater connected to the front of each stage gas expander 31; a cold storage heat exchanger 6 is connected between the air compression system 1 and the combined gas storage device 2, and between the air expansion system 3 and the combined gas storage device 2; the output end of the air compression system 1 is connected to the first input end of the cold storage heat exchanger 6, and the first output end of the cold storage heat exchanger 6 is connected to the input end of the combined gas storage device 2; the output end of the combined gas storage device 2 is connected to the second input end of the cold storage heat exchanger 6, and the second output end of the cold storage heat exchanger 6 is connected to the air expansion system 3.

[0066] Working principle: When storing energy, the multi-stage compressor 11 and the interstage cooler 12 can perform multi-stage compression and cooling on the air, compress the air, and store it in the combined gas storage device 2. The storage state of the compressed air is gaseous; when releasing energy, the compressed air is injected into the gas expander 31, and after multi-stage heating and expansion, it is output to the outside as work.

[0067] As a second embodiment of the compact compressed air energy storage system 100, a cold storage heat exchanger 6 is provided between the air compression system 1 and the combined gas storage device 2. The air compression system 1 includes a pressure reduction device 4 provided between the cold storage heat exchanger 6 and the combined gas storage device 2. The cold storage heat exchanger 6 has a first inlet, a first outlet, a second inlet, and a second outlet. The output end of the compressor 11 is connected to the first inlet of the cold storage heat exchanger 6, the first outlet of the cold storage heat exchanger 6 is connected to the input end of the pressure reduction device 4, and the output end of the pressure reduction device 4 is connected to the input end of the combined gas storage device 2. During energy storage, the high-pressure gas is compressed and cooled by the multi-stage compressor 11 and the interstage cooler 12, heat exchanged by the cold storage heat exchanger 6, cooled again, and stored at normal pressure in the combined gas storage device 2 after being reduced in pressure by the pressure reduction device 4. The storage state of the compressed air is non-gaseous. Optionally, the pressure reduction device 4 includes a liquid expander 41 or a throttle valve.

[0068] Optionally, the air expansion system 3 includes a pressurizing device 5, the input of which is connected to the output of the combined gas storage device 2, the output of which is connected to the second inlet of the cold storage heat exchanger 6, and the second outlet of the cold storage heat exchanger 6 is connected to the input of the gas expander 31. During energy release, the compressed air in the combined gas storage device 2 is pressurized by the pressurizing device 5, then heated to room temperature by the cold storage heat exchanger 6, and finally heated and expanded by the multi-stage gas expander 31 and the pre-stage reheater before being output. Optionally, the pressurizing device 5 includes a cryogenic pump 51.

[0069] For the heat exchange devices of compressed air energy storage systems on land and at sea, the existing technology requires the arrangement of multiple heat exchange devices, hot and cold storage tanks and pumping devices on each side of the air compression system 1 and the air expansion system 3, and the heat exchange pipelines are complicated, which inevitably leads to large pressure loss and heat dissipation along the way.

[0070] In order to solve the above problems, optionally, a common heat exchange device 7 is provided between the air compression system 1 and the air expansion system 3. The common heat exchange device 7 is connected to the air compression system 1 and is used to cool the gas during the air compression process. The common heat exchange device 7 is connected to the air expansion system 3 and is used to heat the gas during the air expansion process.

[0071] Specifically, the compressed air combined energy storage system includes a common heat exchange device 7, which includes a first heat exchange channel 71, a second heat exchange channel 72 and a third heat exchange channel 73. The input end of the first heat exchange channel 71 is connected to the heat output end of the air compression system 1, and the output end of the first heat exchange channel 71 is connected to the input end of the combined gas storage device 2; the input end of the second heat exchange channel 72 is connected to the output end of the combined gas storage device 2, and the output end of the second heat exchange channel 72 is connected to the heat input end of the air expansion system 3, and the third heat exchange channel 73 circulates the heat exchange medium.

[0072] Specifically, during the air compression process, the compression heat generated enters the first heat exchange channel 71 and exchanges heat with the heat exchange medium in the third heat exchange channel 73. The air in the first heat exchange channel 71 is cooled, and the heat is stored in the heat exchange medium in the third heat exchange channel 73. During the air expansion process, the heat exchange medium in the third heat exchange channel 73 exchanges heat with the air in the second heat exchange channel 72, heating the air for air expansion work. At the same time, the heat exchange medium in the third heat exchange channel 73 is cooled and can be used to cool the air in the next round of air compression, thereby achieving the goal of sharing the common heat exchange device 7 with the air compression system 1 and the air expansion system 3. By providing a common heat exchanger 7, the heat energy generated by air compression during the energy storage process can be used to heat the compressed air during the energy release process, and the cold energy generated by air expansion during the energy release process can be used to cool the compressed air during the energy storage process. The common heat exchanger 7 is shared by both the energy storage and energy release processes. During energy storage, the air is compressed and cooled, and the pressure potential energy and temperature thermal energy are stored in the combined gas storage device 2 and the common heat exchanger 7, respectively. During energy release, the high-pressure air in the combined gas storage device 2 is heated by the common heat exchanger 7, becoming high-pressure, high-temperature air, which is then injected into the gas expander 31 to expand and perform work. The provision of the common heat exchanger 7 can, on the one hand, simplify the piping layout, reduce pressure loss and heat dissipation along the way, improve the system's thermal energy utilization rate, and enhance system operating efficiency. On the other hand, it is conducive to improving the system's integration level and space utilization, saving construction costs, and achieving the effect of reducing costs and increasing efficiency.

[0073] In this embodiment, since the air compression system 1 and the air expansion system 3 share the common heat exchange device 7, the common heat exchange device 7 serves as a reheater.

[0074] Air compression system 1 and air expansion system 3 share a common heat exchange device 7. During energy storage, first heat exchange channel 71 of common heat exchange device 7 operates to cool the air. During energy release, second heat exchange channel 72 of common heat exchange device 7 operates to heat the air. First and second heat exchange channels 71, 72 operate independently, allowing a single common heat exchange device 7 to perform both energy storage and energy release functions.

[0075] Optionally, the air compression system 1 has a first pressure side and a second pressure side, where the pressure on the second pressure side is greater than that on the first pressure side; the air compression system 1 includes at least two compressors 11 connected in series, with the multiple compressors 11 being disposed on the first pressure side and the second pressure side; and the air expansion system 3 includes at least two gas expanders 31 connected in series, with the multiple gas expanders 31 being disposed on the first pressure side and the second pressure side. Specifically, the first pressure side is the low-pressure side, and the second pressure side is the high-pressure side.

[0076] As the first embodiment of the shared common heat exchange device 7, on the low-pressure side, the first heat exchange channel 71 of the common heat exchange device 7 is connected between adjacent compressors 11, and the second heat exchange channel 72 of the common heat exchange device 7 is connected between adjacent gas expanders 31, as shown in Figure 7. In this embodiment, the temperature parameters of the common heat exchange device 7 on the low-pressure side are similar. Since the pressure difference is small, sharing the common heat exchange device 7 can reduce the number and tonnage of heat exchange equipment.

[0077] As a second embodiment of the shared common heat exchange device 7, on the high-pressure side, the first heat exchange channel 71 of the common heat exchange device 7 is connected between adjacent compressors 11, and the second heat exchange channel 72 of the common heat exchange device 7 is connected between adjacent gas expanders 31, as shown in Figure 8. In this embodiment, the temperature parameters of the common heat exchange device 7 on the high-pressure side are similar. Due to the large pressure difference, the pressure change needs to be considered when the first heat exchange channel 71 and the second heat exchange channel 72 are switched. After sharing the common heat exchange device 7, the number and tonnage of heat exchange equipment can be significantly reduced.

[0078] As a third implementation method of the shared common heat exchange device 7, on the low-pressure side and the high-pressure side, the first heat exchange channel 71 of the common heat exchange device 7 is connected between adjacent compressors 11, and the second heat exchange channel 72 of the common heat exchange device 7 is connected between adjacent gas expanders 31, as shown in Figure 1.

[0079] Since the air compression system 1 and the air expansion system 3 share the common heat exchange device 7, the investment and construction cost of the heat exchange system is reduced.

[0080] Working principle:

[0081] When storing energy, the multi-stage compressor 11 and the cooler 12 can perform multi-stage compression and cooling on the air, and after the high-pressure air is heat exchanged and depressurized, it is stored in a supercritical state or liquid state; when releasing energy, the supercritical state or liquid air is pressurized and heat exchanged, and then multi-stage heated and expanded to output work to the outside. The air compression system 1 and the air expansion system 3 can compress the air to a supercritical state, which can significantly improve the efficiency of the system. They can also compress the air to a liquid state, and flexibly select the specific gas storage state of the energy storage system according to the power and duration required to store electrical energy during off-peak electricity of the wind farm or the grid. For example, when energy storage is lower than demand due to other factors such as peak electricity consumption or low wind speed, because air in a supercritical state occupies less space than air in a non-supercritical state, the air can be compressed to a supercritical state to increase the volume of the existing combined gas storage device 2 to meet the actual energy storage demand.

[0082] Example 2

[0083] For onshore and offshore compressed air energy storage coupled with wind power systems, the current application is to regulate unstable power sources on the grid side. The grid connection of compressed air energy storage systems and source-side power sources such as wind power requires the laying of long transmission and distribution lines, which is costly.

[0084] Referring to FIG1 , a power system includes a power grid, a wind turbine 300, and the compact compressed air energy storage system 100 of Example 1. The air compression system 1 is electrically connected to the power grid, or to the wind turbine 300, and the air expansion system 3 is electrically connected to the power grid. The compact compressed air energy storage system 100 is coupled to the power grid and the wind turbine 300. The driving power for the compact compressed air energy storage system 100 can be provided by either the power grid or the wind turbine 300.

[0085] By utilizing the power system of the present invention, the compact compressed air energy storage system 100 is directly coupled to the source-side wind farm power supply nearby, thereby realizing distributed energy storage and regional microgrids. When coupled with the offshore wind turbine generator set 300, it is close to the coastal load center, thereby reducing the transmission and distribution costs.

[0086] In the power system, when coupled with an offshore wind turbine generator set 300, except for the combined gas storage device 2 arranged at sea, the rest can be arranged at sea, which can shorten the gas transmission pipeline. It can also be distributed on land, replacing long-distance gas transmission with long-distance power transmission, which can make full use of compression heat, reduce energy waste, and improve system efficiency.

[0087] Working principle:

[0088] Since the air storage state can be selected according to the power and duration of the stored electrical energy, the following uses the supercritical state as an example for explanation.

[0089] During energy storage, the wind turbine 300 or excess electricity from the grid during off-peak hours is used to drive the multi-stage compressor 11, compressing the low-pressure air to a supercritical state. After being cooled to room temperature by the multi-stage cooler, the air is isobarically cooled and liquefied using the cold energy stored in the cold storage heat exchanger 6. After being depressurized by the depressurization device 4, the air is stored at normal pressure in the combined gas storage device 2. Simultaneously, the heat of air compression is recovered and stored in the common heat exchanger 7.

[0090] When releasing energy, the supercritical air in the combined gas storage device 2 is pressurized by the pressurizing device 5, heated to room temperature by the cold storage heat exchanger 6, passes through the multi-stage reheater, and absorbs the compression heat in the common heat exchange device 7, and finally expands and works through the multi-stage gas expander 31 and outputs it to the outside. At the same time, the air expansion cold is recovered and stored in the common heat exchange device 7.

[0091] When the power system provided in this embodiment is used at sea, the combined gas storage device can use the static pressure of water to maintain the system's constant pressure operation, thereby preventing the air compression system 1 and the air expansion system 3 from deviating from the designed operating conditions and operating inefficiently due to pressure changes, thereby improving the system's energy conversion efficiency.

[0092] For the power system obtained by coupling onshore and offshore compressed air energy storage systems and wind power, the compressed air energy storage system with a coaxial compact layout is easy to integrate into the nacelle of large-capacity offshore wind turbines, with larger space conditions and better application prospects.

[0093] Example 3

[0094] A compressed air energy storage method utilizes the compact compressed air energy storage system 100 described in Example 1 to store air energy, comprising the following steps: an energy storage process, connecting the three-in-one motor 8 and the input shaft of the air compression system 1, compressing and cooling the air, and storing the compressed air in the combined air storage device 2; an energy release process, connecting the three-in-one motor 8 and the output shaft of the air expansion system 3, heating the compressed air stored in the combined air storage device 2 and injecting it into the air expansion system 3 for expansion and work output; wherein, "storing the compressed air in the combined air storage device 2" includes storing the compressed air in the first air storage device 400 and / or the second air storage device 22.

[0095] Optionally, the heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; and the cold energy generated by compressed air expansion during the energy release process is used to cool the air during the energy storage process.

[0096] Optionally, during the energy storage process, the air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in the combined air storage device 2 .

[0097] The compressed air energy storage method provided in this embodiment has all the beneficial effects of Example 1, which will not be repeated here.

[0098] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A compact compressed air energy storage system, characterized in that: The invention comprises an air compression system (1), a combined air storage device (2) and an air expansion system (3); the output end of the air compression system (1) is connected to the input end of the combined air storage device (2), and the output end of the combined air storage device (2) is connected to the input end of the air expansion system (3); wherein the combined air storage device (2) comprises: A first gas storage device (400), the first gas storage device (400) comprising a wind turbine tower (21), the wind turbine tower (21) being provided with a first gas storage cavity (214); A second gas storage device (22), the second gas storage device (22) being arranged underground, underwater or suspended in water, the second gas storage device (22) being provided with a second gas storage cavity (223), the first gas storage cavity (214) being in communication with the second gas storage cavity (223); The central axis of the air compression system (1) and the central axis of the air expansion system (3) are coaxially arranged, and the input shaft of the air compression system (1) and the output shaft of the air expansion system (3) are detachably connected to the three-in-one motor (8).

2. The compact compressed air energy storage system according to claim 1, characterized in that: The tower (21) comprises a plurality of tower sections (211) which are separately arranged along the axial direction; the first air storage cavity (214) is arranged in one or more of the tower sections (211); Alternatively, the tower (21) comprises an outer cylinder (212) and an inner cylinder (213) which are sleeved in a radial direction; an annular gap between the outer cylinder (212) and the inner cylinder (213) constitutes the first gas storage cavity (214).

3. The compact compressed air energy storage system according to claim 1 or 2, characterized in that: The second gas storage device (22) comprises an artificial chamber (224), the cavity of the artificial chamber (224) constitutes the second gas storage cavity (223), the artificial chamber (224) is arranged below the tower (21), and the first gas storage cavity (214) and the second gas storage cavity (223) are connected through or through a pipeline; Alternatively, the combined gas storage device (2) comprises a storage tank (221) fixedly arranged on the seabed, the inner cavity of the storage tank (221) constituting the second gas storage cavity (223), the storage tank (221) being arranged below the tower (21), and the first gas storage cavity (214) and the second gas storage cavity (223) being connected through or through a pipeline; Alternatively, the combined air storage device (2) comprises an air bag (222) suspended in water, the inner cavity of the air bag (222) constitutes the second air storage cavity (223), the first air storage cavity (214) of the tower (21) is provided with an interface, and the air nozzle of the air bag (222) and the interface are connected via a pipeline.

4. The compact compressed air energy storage system according to claim 1 or 2, characterized in that: The air compression system (1) comprises a multi-stage compressor (11) connected in series, wherein the central axes of the multi-stage compressors (11) are coaxially arranged; the air expansion system (3) comprises a multi-stage gas expansion machine (31) connected in series, wherein the central axes of the multi-stage gas expansion machine (31) are coaxially arranged; the central axis of the compressor (11) located at the input end of the air compression system (1) and the central axis of the gas expansion machine (31) located at the output end of the air expansion system (3) are connected to the three-in-one motor (8) via a switching device (9).

5. The compact compressed air energy storage system according to claim 4, characterized in that: The switching device (9) comprises a first clutch (91) detachably connected to the central axis of the air compression system (1) and a second clutch (92) detachably connected to the central axis of the air expansion system (3).

6. The compact compressed air energy storage system according to claim 1 or 2, characterized in that: A common heat exchange device (7) is provided between the air compression system (1) and the air expansion system (3), the common heat exchange device (7) comprising a first heat exchange channel (71), a second heat exchange channel (72) and a third heat exchange channel (73), the input end of the first heat exchange channel (71) being connected to the heat output end of the air compression system (1), the output end of the first heat exchange channel (71) being connected to the input end of the combined gas storage device (2); the input end of the second heat exchange channel (72) being connected to the output end of the combined gas storage device (2), the output end of the second heat exchange channel (72) being connected to the heat input end of the air expansion system (3); and a heat exchange medium flowing through the third heat exchange channel (73).

7. A power system, characterized in that: The invention comprises a power grid, a wind turbine (300) and a compact compressed air energy storage system according to any one of claims 1 to 6, wherein the air compression system (1) is electrically connected to the power grid, or the air compression system (1) is electrically connected to the wind turbine (300), and the air expansion system (3) is electrically connected to the power grid.

8. A compressed air energy storage method, characterized in that: Using the compact compressed air energy storage system according to any one of claims 1 to 6 to store air energy comprises the following steps: Energy storage process: connecting the three-in-one motor (8) to the input shaft of the air compression system (1), compressing and cooling the air, and storing the compressed air in the combined air storage device (2); Energy release process: the three-in-one motor (8) is connected to the output shaft of the air expansion system (3), and the compressed air stored in the combined air storage device (2) is heated and then injected into the air expansion system (3) to perform expansion and work output; Wherein, storing the compressed air in the combined air storage device (2) includes storing the compressed air in the first air storage device (400) and / or the second air storage device (22).

9. The compressed air energy storage method according to claim 8, characterized in that: The heat energy generated by air compression during the energy storage process is used to heat the compressed air during the energy release process; the cold energy generated by the expansion of compressed air during the energy release process is used to cool the air during the energy storage process.

10. The compressed air energy storage method according to claim 8 or 9, characterized in that: During the energy storage process, air is compressed to a supercritical state, and the compressed air in the supercritical state is stored in the combined air storage device (2).

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