A compressed air energy storage system and control method

Abstract

The application belongs to the technical field of compressed air energy storage, and discloses a compressed air energy storage system and a control method, the compressed air energy storage system comprising an air compressor unit, a buffer tank, a heat exchanger group, a power generation module, an auxiliary module and a circulation loop, wherein the air compressor unit is connected with a circuit; the buffer tank is connected with the air compressor unit and is used for storing compressed air output by the air compressor unit; the heat exchanger group is arranged downstream of the buffer tank and is used for adjusting the temperature of the compressed air; the auxiliary module is connected with the power generation module, the power generation module comprises an expander, the auxiliary module is connected with a turbine, the expander and the turbine are selectively communicated with the heat exchanger group, and the power generation module is connected with the circuit; the input end of the circulation loop is connected with the power generation module and the auxiliary module, and the output end of the circulation loop is connected with the buffer tank. In this way, the surplus electric energy can be fully utilized, and the energy storage efficiency of the compressed air energy storage system is improved.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a compressed air energy storage system and control method. Background Technology

[0002] Compressed air energy storage systems can use electricity to compress air into high-pressure air and store it in underground salt caverns, rock caves, or special pressure vessels during periods of low electricity demand or when there is a surplus of new energy power generation such as wind power and photovoltaic power. During peak electricity demand, the high-pressure air is released and drives an expander to drive a generator to generate electricity, thus realizing the storage and reuse of electrical energy.

[0003] In related technologies, compressed air energy storage systems include air compressors, air tanks, expanders, and auxiliary modules. The air compressor converts electrical energy into compressed air energy, the air tank stores compressed air, the expander converts the stored compressed air into mechanical energy and generates electricity through a generator, and the auxiliary modules manage the flow of fluids such as circulating water, lubricating oil, and heat storage media within the system, as well as the opening of valves, ensuring the normal operation of the compressed air energy storage system.

[0004] However, in order to make the auxiliary modules work, it is usually necessary to install auxiliary motors, frequency converters, cables and other devices. The power distribution room is large and it is difficult to maintain the stable operation of the system under extreme conditions. In addition, the utilization rate of surplus power is low and it is difficult to directly use it for the auxiliary modules, which makes the energy storage efficiency of the compressed air energy storage system low. Summary of the Invention

[0005] The purpose of this invention is to provide a compressed air energy storage system and control method to solve the problem of low energy storage efficiency in compressed air energy storage systems.

[0006] To achieve this objective, the present invention adopts the following technical solution: In a first aspect, a compressed air energy storage system includes: an air compressor unit connected to an electrical circuit; a buffer tank connected to the air compressor unit for storing compressed air output by the air compressor unit; a heat exchanger group disposed downstream of the buffer tank for adjusting the temperature of the compressed air; a power generation module and an auxiliary module connected to the power generation module, the power generation module including an expander, the auxiliary module being connected to a turbine, the expander and the turbine being selectively connected to the heat exchanger group, the power generation module being connected to the electrical circuit; and a circulation loop, the input end of the circulation loop being connected to the power generation module and the auxiliary module, and the output end of the circulation loop being connected to the buffer tank.

[0007] Preferably, multiple auxiliary modules are arranged in parallel, and each turbine corresponds to one of the auxiliary modules.

[0008] Preferably, the compressed air energy storage system further includes a filter disposed at the output end of the heat exchanger assembly; and / or, the filter is disposed at the input end of the circulation loop.

[0009] Preferably, the compressed air energy storage system further includes a pressure storage tank group, the input end of which is selectively connected to the output end of the buffer tank, and the output end of which is selectively connected to the input end of the heat exchanger group.

[0010] Preferably, the pressure tank group includes multiple pressure tanks, and the pressure levels of the pressure tanks increase or decrease along the arrangement direction of the pressure tanks.

[0011] Preferably, the heat exchanger assembly is provided with a selection valve, which is located between the pressure tank assembly and the heat exchanger assembly.

[0012] Preferably, the circulation loop includes a first path and a second path, the input end of the first path is connected to the output end of the expander, the input end of the second path is connected to the output end of the turbine, and the output ends of the first path and the second path are selectively connected to the buffer tank.

[0013] Preferably, the input terminals of the first channel and the second channel are connected in parallel.

[0014] Preferably, the loop further includes a third path, the input of which is connected to the output of the first path and the output of the second path, and the output of which is connected to the buffer tank.

[0015] Secondly, a control method is applied to the compressed air energy storage system described above, the control method comprising: S1. The air compressor unit converts surplus electrical energy into compressed air and delivers the compressed air to the buffer tank for storage. S2. After the compressed air in the buffer tank enters the heat exchanger group for heat exchange, it enters the turbine and the expander respectively, converting the compressed air energy into mechanical energy and driving the power generation module and the auxiliary module to operate, realizing the operation of the compressed air energy storage system and converting mechanical energy into electrical energy. S3. The air after the work is done is circulated through the circulation loop to the buffer tank for continued storage.

[0016] The beneficial effects of this invention are: A compressed air energy storage system includes an air compressor unit, a buffer tank, a heat exchanger group, a power generation module, an auxiliary module, and a circulation loop. The air compressor unit is connected to an electrical circuit. The buffer tank is connected to the air compressor unit and is used to store the compressed air output by the air compressor unit. The heat exchanger group is located downstream of the buffer tank and is used to adjust the temperature of the compressed air. The auxiliary module is connected to the power generation module, and the power generation module includes an expander. The auxiliary module is connected to a turbine, and the expander and turbine are selectively connected to the heat exchanger group. The power generation module is connected to an electrical circuit. The input end of the circulation loop is connected to the power generation module and the auxiliary module, and the output end of the circulation loop is connected to the buffer tank.

[0017] In this way, the surplus electrical energy generated by solar and wind energy can be converted into compressed air energy by air compressor units and stored in buffer tanks. The compressed air energy can be converted into mechanical energy by turbines and used to drive the auxiliary system. This saves on the layout of auxiliary motors, frequency converters, and cables, reduces the size of the power distribution room, reduces the number of energy conversions, and improves the utilization rate of surplus electrical energy. The circulation loop can recover the air after it has passed through the expander and turbine to the buffer tank, realizing the recycling of compressed air and improving the absorption efficiency of solar and wind energy as well as the energy storage efficiency of the compressed air energy storage system. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a compressed air energy storage system according to an embodiment of the present invention.

[0019] In the picture: 1. Circuit; 2. Air compressor unit; 3. Buffer tank; 4. Heat exchanger unit; 41. Selector valve; 5. Power generation module; 51. Expander; 6. Auxiliary module; 61. Turbine; 7. Circulation loop; 71. First path; 72. Second path; 73. Third path; 8. Pressure tank group; 81. Pressure tank; 9. Filter. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0023] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0024] See Figure 1 This invention provides a compressed air energy storage system, including an air compressor unit 2, a buffer tank 3, a heat exchanger group 4, a power generation module 5, an auxiliary module 6, and a circulation loop 7. The air compressor unit 2 is connected to a circuit 1; the buffer tank 3 is connected to the air compressor unit 2 and is used to store the compressed air output by the air compressor unit 2; the heat exchanger group 4 is located downstream of the buffer tank 3 and is used to adjust the temperature of the compressed air; the auxiliary module 6 is connected to the power generation module 5, the power generation module 5 includes an expander 51, the auxiliary module 6 is connected to a turbine 61, and both the expander 51 and the turbine 61 are selectively connected to the heat exchanger group 4; the power generation module 5 is connected to the circuit 1; the input end of the circulation loop 7 is connected to the power generation module 5 and the auxiliary module 6, and the output end of the circulation loop 7 is connected to the buffer tank 3.

[0025] In this embodiment, the air compressor unit 2 includes multiple air compressors. The surplus electrical energy converted from solar and wind energy is transmitted to the air compressors through circuit 1, enabling the air compressors to convert electrical energy into compressed air energy. The compressed air is then transported through pipelines to the buffer tank 3 for storage. The heat exchanger group 4 is a tower heat exchanger, which can heat the compressed air output from the buffer tank 3 as needed and deliver the compressed air to the corresponding power generation module 5 or auxiliary module 6. The expander 51 can convert compressed air energy into mechanical energy and generate electricity through a generator (not shown in the figure), transmitting the electrical energy back to circuit 1 to meet the electricity demand during peak periods. The turbine 61 can convert compressed air energy into mechanical energy to enable the auxiliary module 6 to operate, thereby assisting the operation of the compressed air energy storage system. The circulation loop 7 is connected to both the expander 51 and the turbine 61, recovering the air after it has done work back to the buffer tank 3.

[0026] In this way, the compressed air energy is converted into mechanical energy by the turbine 61 to drive the operation of the auxiliary system. This can save on the layout of auxiliary motors, frequency converters and cables, reduce the size of the power distribution room, reduce the number of energy conversions, and improve the utilization rate of surplus electrical energy. The circulation loop 7 recovers the air after it has been worked by the expander 51 and the turbine 61 to the buffer tank 3, which can realize the recycling of compressed air, avoid energy waste, and is conducive to the absorption of energy such as solar and wind energy, and improve the energy storage efficiency of the compressed air energy storage system.

[0027] See Figure 1 In some embodiments, multiple auxiliary modules 6 are arranged in parallel, and the turbine 61 is arranged in a one-to-one correspondence with the auxiliary modules 6.

[0028] In this embodiment, three auxiliary modules 6 are provided, and correspondingly, three turbines 61 are provided. All three turbines 61 are provided between the heat exchanger group 4 and the corresponding auxiliary module 6, and are used to convert compressed air into mechanical energy and drive the auxiliary module 6 to operate.

[0029] In this way, each turbine 61 can drive the corresponding auxiliary module 6 to operate independently. According to the needs of each auxiliary module 6, the compressed air can be heated to the required temperature through the heat exchanger group 4 and distributed, so that each auxiliary module 6 can obtain the appropriate driving force, improving the stability and reliability of the operation of the auxiliary module 6. This helps the power generation module 5 to output electrical energy stably when the power demand is high, improving the continuity of the operation of the compressed air energy storage system. Under extreme conditions, there is no need to introduce electrical energy. The operation of the compressed air energy storage system can be realized by releasing compressed air to do work, thereby improving the energy storage efficiency and safety of the compressed air energy storage system.

[0030] It is understandable that the auxiliary module 6 can be a circulating water pump module, a lubricating oil circulation module, a heat storage medium circulation module, a valve actuation module, or other modules used to ensure the continuous and normal operation of the compressed air energy storage system. The type of auxiliary module 6 can be adjusted according to actual needs, as long as it can be driven by compressed air energy.

[0031] It should be noted that the operation of the turbine 61 drive auxiliary module 6 is existing technology and will not be elaborated here.

[0032] See Figure 1 In some embodiments, the compressed air energy storage system further includes a filter 9, which is disposed at the output end of the heat exchanger group 4 and the input end of the circulation loop 7. That is, a filter 9 is disposed upstream and downstream of each turbine 61, and a filter 9 is disposed upstream and downstream of each expander 51.

[0033] Thus, the filter 9 located upstream of turbine 61 and expander 51 can filter solid particles, oil stains and other impurities in the compressed air output from heat exchanger group 4, preventing impurities from entering expander 51 and turbine 61 and affecting the efficiency of compressed air energy conversion to mechanical energy. The filter 9 located downstream of turbine 61 and expander 51 can filter the air after work is done, preventing impurities from accumulating in buffer tank 3 and contaminating the compressed air in subsequent circulation, thereby protecting the air compressor group 2, heat exchanger group 4 and other structures, reducing energy loss caused by impurities and system efficiency decline, and improving the energy storage efficiency of the compressed air energy storage system.

[0034] Understandably, the number and location of filters 9 can be adjusted according to actual needs, and will not be listed in detail here.

[0035] See Figure 1 In some embodiments, the compressed air energy storage system further includes a pressure tank group 8, the input end of which is selectively connected to the output end of the buffer tank 3, and the output end of the pressure tank group 8 is selectively connected to the input end of the heat exchanger group 4.

[0036] In this embodiment, a valve (not shown in the figure) is provided between the buffer tank 3 and the pressure tank group 8 to allow compressed air at a certain pressure to enter the pressure tank group 8 and be distributed to the heat exchanger group 4.

[0037] Thus, by setting up the pressure storage tank group 8, the storage space for compressed air can be increased, allowing surplus electrical energy to be fully converted into compressed air energy. The pressure storage tank group 8 is selectively connected to the buffer tank 3 via valves, and temporarily stores and pressure-balances the compressed air output from the buffer tank 3, achieving stable pressure storage of the compressed air. This ensures that the compressed air pressure delivered to the heat exchanger group 4 is stable, and the compressed air entering the turbine 61 or expander 51 has suitable temperature and pressure, improving the energy storage efficiency of the compressed air energy storage system. (See reference...) Figure 1 In some embodiments, the pressure tank group 8 includes a plurality of pressure tanks 81, and the pressure levels of the pressure tanks 81 increase or decrease along the arrangement direction of the pressure tanks 81. Further, the heat exchanger group 4 is provided with a selection valve 41, which is located between the pressure tank group 8 and the heat exchanger group 4.

[0038] In this embodiment, four pressure tanks 81 are provided. Along the direction close to the heat exchanger group 4, the pressure level of the pressure tanks 81 increases. The selection valve 41 is provided one-to-one with the pressure tanks 81 and is connected to the heat exchanger group 4, so that the compressed air in each pressure tank 81 can be selectively delivered to the heat exchanger group 4 to adapt to the pressure required by the power generation module 5 and the auxiliary module 6.

[0039] In this way, the compressed air output from the buffer tank 3 can be stored in stages to form a gradient pressure reserve. Combined with the selector valve 41, the compressed air is delivered to the turbine 61 and the expander 51 at the required pressure, which improves the energy conversion efficiency. The storage tanks 81 of different pressure levels can be flexibly adjusted to store or supply energy according to the power consumption, thereby reducing energy waste and improving the energy storage efficiency of the compressed air energy storage system.

[0040] It is understandable that the number of pressure tanks 81 can also be two, six, or eight. The number of pressure tanks 81 can be adjusted according to actual needs. Pressure tank group 8 can also be connected to pressure sensors to monitor the pressure of compressed air stored in each pressure tank 81.

[0041] It should be noted that the gas pressure required by the lubricating oil circulation module, the power generation module 5, the valve actuation module, the heat storage medium circulation module, and the circulating water pump module decreases in that order. The gas pressure required by the power generation module 5 and the auxiliary module 6 can be adjusted according to actual needs, and will not be listed in detail here.

[0042] See Figure 1 In some embodiments, the circulation loop 7 includes a first path 71 and a second path 72. The input end of the first path 71 is connected to the output end of the expander 51, and the input end of the second path 72 is connected to the output end of the turbine 61. The output ends of the first path 71 and the second path 72 are selectively connected to the buffer tank 3.

[0043] In this embodiment, the first path 71 is configured to correspond to the expander 51, and the second path 72 is configured to correspond one-to-one with the turbine 61. The first path 71 and the second path 72 are connected in parallel to circulate and recover the air after it has been powered by the turbine 61 or the expander 51 back to the buffer tank 3 and participate in air compression again.

[0044] In this way, the air after the expander 51 has done work and the air after the turbine 61 has done work can be independently recovered, so that the air recovered into the buffer tank 3 can maintain a suitable pressure and temperature. The on and off of the corresponding circuits can be independently controlled according to the operating conditions of the expander 51 and the turbine 61, thereby improving the recovery efficiency of compressed air, fully absorbing solar and wind energy, and thus improving the energy storage efficiency of the compressed air energy storage system.

[0045] See Figure 1 In some embodiments, the input terminals of the first channel 71 and the second channel 72 are connected in parallel.

[0046] In this embodiment, the second path 72 includes three branches (not shown in the figure). The input terminals of the three branches are respectively connected to the three auxiliary modules 6, and the output terminals of the three branches are combined and connected to the second path 72. The three branches are connected in parallel.

[0047] This reduces interference between the auxiliary module 6 and the power generation module 5, allowing compressed air to circulate stably to the buffer tank 3 and utilize surplus electrical energy in a timely manner, absorbing solar and wind energy. It also facilitates the independent delivery of compressed air to the auxiliary module 6 and the power generation module 5, enabling the compressed air energy storage system to operate normally even under extreme conditions and improving the energy storage efficiency of the compressed air energy storage system.

[0048] See Figure 1 In some embodiments, the loop 7 further includes a third path 73, the input of the third path 73 is connected to the output of the first path 71 and the output of the second path 72, and the output of the third path 73 is connected to the buffer tank 3.

[0049] In this way, the air recovered by the first channel 71 and the second channel 72 after the work is done is combined and transported to the buffer tank 3 through the third channel 73, which can improve the recovery efficiency, so that the air entering the buffer tank 3 is recompressed and distributed to the pressure tank group 8, reducing energy loss and improving the energy storage efficiency of the compressed air energy storage system.

[0050] It is understandable that the first path 71 and the second path 72 can also be connected to the buffer tank 3 respectively. In this embodiment, the first path 71 and the second path 72 are combined and connected to the third path 73 in order to improve the recycling efficiency and facilitate the recycling of compressed air.

[0051] It should be noted that buffer tank 3 and pressure tank group 8, as well as pressure tank group 8 and heat exchanger group 4, are connected by pipelines. Valves for controlling gas flow can also be installed on the pipelines to achieve directional flow of compressed air, which will not be elaborated here.

[0052] The present invention also provides a control method applied to a compressed air energy storage system, the control method comprising: S1, Air compressor unit 2 converts surplus electrical energy into compressed air and delivers the compressed air to buffer tank 3 for storage; S2. After the compressed air in the buffer tank 3 enters the heat exchanger group 4 for heat exchange, it enters the turbine 61 and the expander 51 respectively, converting the compressed air energy into mechanical energy and driving the power generation module 5 and the auxiliary module 6 to operate, realizing the operation of the compressed air energy storage system and converting mechanical energy into electrical energy. S3. The air after the work is done is circulated through the circulation loop 7 to the buffer tank 3 for further storage.

[0053] In this embodiment, S1 also includes the process of accumulating a certain amount of compressed air in the buffer tank 3 and then transporting it to the pressure storage tank group 8 so that the pressure storage tank 81 stores compressed air of different pressure levels.

[0054] S2 also includes outputting compressed air from the pressure tank 81 of the corresponding pressure level according to the needs of the power generation module 5 and the auxiliary module 6.

[0055] In this way, surplus electrical energy can be fully utilized and converted into compressed air energy for storage. When the demand for electricity increases, the compressed air energy is converted into mechanical energy and directly drives the auxiliary module 6 to operate, reducing the layout of auxiliary motors, frequency converters, and cables, realizing the closed-loop recycling of compressed air, reducing energy waste. The pressure tank group 8 stores compressed air of different pressure levels, and a heat exchanger group 4 is set downstream of the pressure tank group 8, which enables the compressed air to enter the turbine 61 or expander 51 at a suitable temperature and pressure to match different pressure requirements and improve the energy storage efficiency of the compressed air energy storage system.

[0056] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A compressed air energy storage system, characterized in that, include: An air compressor unit (2) is connected to a circuit (1); A buffer tank (3) is connected to the air compressor unit (2) and is used to store the compressed air output by the air compressor unit (2); A heat exchanger assembly (4) is located downstream of the buffer tank (3) and is used to adjust the temperature of the compressed air. A power generation module (5) and an auxiliary module (6) are provided. The auxiliary module (6) is connected to the power generation module (5). The power generation module (5) includes an expander (51). The auxiliary module (6) is connected to a turbine (61). The expander (51) and the turbine (61) are selectively connected to the heat exchanger group (4). The power generation module (5) is connected to the circuit (1). The loop (7) is connected to the power generation module (5) and the auxiliary module (6) at its input end, and to the buffer tank (3) at its output end.

2. The compressed air energy storage system according to claim 1, characterized in that, Multiple auxiliary modules (6) are connected in parallel, and the turbine (61) is connected in a one-to-one correspondence with the auxiliary modules (6).

3. The compressed air energy storage system according to claim 1, characterized in that, The compressed air energy storage system further includes a filter (9) disposed at the output end of the heat exchanger group (4); and / or, the filter (9) disposed at the input end of the circulation loop (7).

4. The compressed air energy storage system according to claim 1, characterized in that, The compressed air energy storage system also includes a pressure tank group (8), the input end of which is selectively connected to the output end of the buffer tank (3), and the output end of which is selectively connected to the input end of the heat exchanger group (4).

5. The compressed air energy storage system according to claim 4, characterized in that, The pressure tank group (8) includes multiple pressure tanks (81), and the pressure levels of the pressure tanks (81) increase or decrease along the arrangement direction of the pressure tanks (81).

6. The compressed air energy storage system according to claim 4, characterized in that, The heat exchanger assembly (4) is equipped with a selection valve (41), which is located between the pressure tank assembly (8) and the heat exchanger assembly (4).

7. The compressed air energy storage system according to any one of claims 1-6, characterized in that, The circulation loop (7) includes a first path (71) and a second path (72). The input end of the first path (71) is connected to the output end of the expander (51), and the input end of the second path (72) is connected to the output end of the turbine (61). The output ends of the first path (71) and the second path (72) are selectively connected to the buffer tank (3).

8. The compressed air energy storage system according to claim 7, characterized in that, The input terminals of the first channel (71) and the second channel (72) are connected in parallel.

9. The compressed air energy storage system according to claim 7, characterized in that, The loop (7) further includes a third path (73), the input of which is connected to the output of the first path (71) and the output of the second path (72), and the output of which is connected to the buffer tank (3).

10. A control method, characterized in that, The control method, applied to the compressed air energy storage system as described in any one of claims 1-9, comprises: S1. The air compressor unit (2) converts surplus electrical energy into compressed air and delivers the compressed air to the buffer tank (3) for storage. S2. After the compressed air in the buffer tank (3) enters the heat exchanger group (4) for heat exchange, it enters the turbine (61) and the expander (51) respectively, converting the compressed air energy into mechanical energy and driving the power generation module (5) and the auxiliary module (6) to operate, realizing the operation of the compressed air energy storage system and converting mechanical energy into electrical energy. S3. The air after the work is done is circulated through the circulation loop (7) to the buffer tank (3) for continued storage.

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