Compressed air energy storage system and method

Abstract

The present invention relates to the field of energy storage technology, and in particular to a compressed air energy storage system and method, including an air cavity and a charging and discharging air pipe port, wherein a piston that can move up and down is provided in the air cavity, and the piston separates the air cavity into an upper low-pressure chamber and a lower high-pressure chamber, wherein the low-pressure chamber is provided with a low-pressure connecting port that can be connected to the outside, and the piston is provided with a high-pressure connecting port that can connect the low-pressure chamber and the high-pressure chamber, wherein the charging and discharging air pipe port is connected to the bottom of the high-pressure chamber, and the charging and discharging air pipe port is respectively connected to a cooling compression device for charging and a heating expansion device for discharging. A compressed air energy storage system and method of the present invention can solve the problems of unstable intake pressure and throttling loss of the expander in the compressed air energy storage system.

Description

Technical Field

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

[0002] Energy storage, especially the storage of electric energy, is of great significance to the optimization of energy structure and the regulation of power grid operation. Compressed air energy storage system is a new type of energy storage technology. In 1978, Germany built the world's first demonstration compressed air energy storage power station, followed by the United States, Japan and Israel. The working principle of the compressed air energy storage power generation system is similar to that of pumped storage. When the power consumption of the power system is at a low point, the system stores energy, and uses the surplus electricity in the system. The compressor drives the air compressor to compress the air and stores the energy in the form of compressed air in the gas storage device; when the power load of the power system reaches the peak and the power generation is insufficient, the system releases energy, and the gas storage device releases the compressed air in the gas storage space, expands in the turbine expander to do work and drive the generator to generate electricity; according to the above principle, the compressed air energy storage system can complete the conversion of electric energy-air potential energy-electric energy.

[0003] Compressed air energy storage gas storage devices are generally closed rigid pressure vessels with limited volume. Therefore, during the deflation process, as the high-pressure air is discharged, the amount of air in the gas storage device decreases and the air pressure decreases. For air expanders, in order to ensure stable output, the air flow, temperature and pressure at the inlet should also remain stable. Correspondingly, the exhaust flow and pressure of the gas storage device are required to be stable. In order to ensure the stable intake of the air expander, a throttling and pressure-reducing device is generally set at the outlet of the gas storage device. At the cost of losing part of the pressure potential energy, the gas storage device exhaust is throttled to a stable pressure for external output; however, when the pressure of the gas storage device drops to the outlet pressure set by the throttling and pressure-stabilizing device, the gas storage device can no longer continue to output compressed air to the outside, and has to stop supplying air to the outside. The remaining low-pressure gas remains in the gas supply device and cannot be used, resulting in low gas storage utilization. Therefore, conventional compressed air energy storage systems face the problems of throttling losses and low gas storage utilization. Summary of the invention

[0004] The present invention provides a compressed air energy storage system and method, which can solve the problems of unstable intake pressure of an expander and throttling loss existing in the compressed air energy storage system.

[0005] A compressed air energy storage system comprises an air cavity and a charging and discharging air pipe port, wherein a piston capable of moving up and down is arranged in the air cavity, the piston separates the air cavity into an upper low-pressure cavity and a lower high-pressure cavity, the low-pressure cavity is provided with a low-pressure connecting port capable of connecting to the outside, the piston is provided with a high-pressure connecting port capable of connecting the low-pressure cavity with the high-pressure cavity, the charging and discharging air pipe port is connected to the bottom of the high-pressure cavity, and the charging and discharging air pipe port is respectively connected to a cooling compression device for charging and a heating expansion device for discharging.

[0006] According to a compressed air energy storage system provided by the present invention, the cooling and compression device includes an air compression pipeline connected to the charging and discharging air pipe port, an air compression unit and an air cooling unit. The air compression pipeline connects the high-temperature side of the air compression unit and the air cooling unit. The outside air entering the air compression pipeline is compressed by the air compression unit and cooled by the air cooling unit before entering the charging and discharging air pipe port.

[0007] According to a compressed air energy storage system provided by the present invention, the heating and expansion device includes an air expansion pipeline connected to the charging and discharging air pipe port, an air expansion unit and an air heating unit, the air expansion pipeline connects the low-temperature side of the air expansion unit and the air heating unit, and the high-pressure air entering the air expansion pipeline from the high-pressure chamber is heated by the air heating unit and expanded by the air expansion unit before being output to the outside.

[0008] A compressed air energy storage system provided according to the present invention also includes a cold accumulator and a heat accumulator, a heat storage pipeline is connected between the cold accumulator and the heat accumulator, the heat storage pipeline is connected to the low-temperature side of the air cooling unit, and a heat recovery pipeline is also connected between the cold accumulator and the heat accumulator, and the heat recovery pipeline is connected to the high-temperature side of the air heating unit.

[0009] According to a compressed air energy storage system provided by the present invention,

[0010] The low-temperature heat storage medium is output from the cold storage device, flows through the low-temperature side of the air cooling unit through the heat storage pipeline, undergoes heat exchange and heats up, becomes a high-temperature heat storage medium, and flows back to the heat storage device through the heat storage pipeline;

[0011] The high-temperature heat storage medium is output from the heat accumulator, flows through the high-temperature side of the air heating unit through the heat recovery pipeline, undergoes heat exchange and cooling, becomes a low-temperature heat storage medium, and flows back to the cold accumulator through the heat recovery pipeline.

[0012] According to a compressed air energy storage system provided by the present invention, a low-temperature heat storage medium output port of the cold accumulator is provided with a low-temperature pump, and a high-temperature heat storage medium output port of the heat accumulator is provided with a high-temperature pump.

[0013] According to a compressed air energy storage system provided by the present invention, the air cooling unit includes a primary cooler and a secondary cooler, the air compression unit includes a primary compressor and a secondary compressor, the charging and discharging air pipe port is sequentially connected in series with the secondary cooler, the secondary compressor, the primary cooler, and the primary compressor; the number of the heat storage pipelines is two, and the two heat storage pipelines are connected in parallel and are respectively connected in series with the low-temperature sides of the primary cooler and the secondary cooler;

[0014] The low-temperature heat storage medium flows through the low-temperature sides of the primary cooler and the secondary cooler through two parallel heat storage pipelines to undergo heat exchange and heat increase, becoming a high-temperature heat storage medium, and then flows back to the heat storage devices.

[0015] According to a compressed air energy storage system provided by the present invention,

[0016] The air heating unit includes a primary heater and a secondary heater, the air expansion unit includes a primary expander and a secondary expander, the gas charging and discharging pipe ports are connected in series with the primary heater, the primary expander, the secondary heater, and the secondary expander in sequence; the number of the heat recovery pipelines is two, and the two heat recovery pipelines are connected in parallel and are respectively connected in series with the high-temperature sides of the primary heater and the secondary heater;

[0017] The high-temperature heat storage medium flows through the high-temperature sides of the primary heater and the secondary heater through two parallel heat recovery pipes to undergo heat exchange and cooling, becomes a low-temperature heat storage medium, and flows back to the cold storage device.

[0018] At the same time, the present invention also discloses a compressed air energy storage method, which includes the above-mentioned compressed air energy storage system, before inflation or deflation or after inflation or deflation is completed, the cooling compression device, the heating expansion device, the inflation and deflation pipe port, the low-pressure connecting port, the high-pressure connecting port, the air compression pipeline, the air expansion pipeline, the heat storage pipeline and the heat recovery pipeline are in a closed state by default;

[0019] When inflation is required:

[0020] S1, opening the high-pressure connecting port to connect the low-pressure chamber to the high-pressure chamber;

[0021] S2, controlling the piston to rise to the top position of the air chamber through an external driving mechanism, and controlling the piston to be stationary through a braking mechanism;

[0022] S3, closing the high-pressure connecting port, opening the air charging and discharging port and the air compression pipeline, starting the primary compressor and the secondary compressor, and continuously compressing the external air from the air compression pipeline into the high-pressure chamber by the primary compressor and the secondary compressor, so that the air pressure in the high-pressure chamber continuously rises;

[0023] S4, while performing step S3, opening the heat storage pipeline and starting the low-temperature pump, driving the low-temperature heat storage medium in the cold storage device to flow in the heat storage pipeline, driving the low-temperature heat storage medium to flow through the low-temperature sides of the primary cooler and the secondary cooler respectively, and then exchanging heat with the air in the air compression pipeline to become a high-temperature heat storage medium, and then flowing back to the heat storage device;

[0024] S5: After the inflation is completed, the cooling and compression device, the inflation and discharge pipe port, the high-pressure connecting port, the air compression pipeline, the heat storage pipeline and the cryogenic pump are closed, and the brake mechanism is released, so that the piston remains freely suspended under the support of the high air pressure in the high-pressure chamber, in preparation for deflation;

[0025] When deflation is required:

[0026] S1, opening the low-pressure connecting port to allow the low-pressure chamber to connect to the external air pressure;

[0027] S2: Open the air charging and discharging pipe and the air expansion pipeline, start the first-stage expander and the second-stage expander, and the high-pressure air in the high-pressure chamber enters the air expansion pipeline and is expanded by the first-stage expander and the second-stage expander before being output to the outside;

[0028] S3, while performing step S2, opening the heat recovery pipeline and starting the high-temperature pump, driving the high-temperature heat storage medium in the heat accumulator to flow in the heat recovery pipeline, driving the high-temperature heat storage medium to flow through the high-temperature sides of the primary heater and the secondary heater respectively, and then exchanging heat with the air in the air expansion pipeline to become a low-temperature heat storage medium, and then flowing back to the cold accumulator;

[0029] S4; During the deflation process, the air pressure in the high-pressure chamber continues to decrease, so that the piston gradually moves downward due to its own weight. When the piston moves down to the bottom of the high-pressure chamber, the deflation is ended, and the cooling compression device, heating expansion device, charging and discharging pipe port, low-pressure connecting port, air expansion pipeline, heat recovery pipeline and high-temperature pump are closed.

[0030] In addition, the present invention further discloses a compressed air energy storage method, which includes the above-mentioned compressed air energy storage system, including the compressed air energy storage system described in claim 1 to 2, before inflation or deflation or after inflation or deflation, the cooling compression device, the heating expansion device, the inflation and deflation pipe port, the low-pressure connecting port, the high-pressure connecting port, the air compression pipeline, the air expansion pipeline, the heat storage pipeline and the heat recovery pipeline are in a closed state by default;

[0031] When inflation is required:

[0032] S1, opening the low-pressure connecting port, the air charging and discharging pipe port and the air compression pipeline;

[0033] S2, starting the primary compressor and the secondary compressor, and the external air is continuously compressed by the primary compressor and the secondary compressor during the process of entering the high-pressure chamber from the air compression pipeline, so that the air pressure in the high-pressure chamber continues to rise and pushes the piston to move upward;

[0034] S3, while performing step S2, opening the heat storage pipeline and starting the low-temperature pump, driving the low-temperature heat storage medium in the cold storage device to flow in the heat storage pipeline, driving the low-temperature heat storage medium to flow through the low-temperature sides of the primary cooler and the secondary cooler respectively, and then exchanging heat with the air in the air compression pipeline to become a high-temperature heat storage medium, and then flowing back to the heat storage device;

[0035] S4: After the inflation is completed, the cooling and compression device, the inflation and discharge pipe port, the low-pressure connecting port, the air compression pipeline, the heat storage pipeline and the cryogenic pump are closed, so that the piston remains freely suspended under the support of the high air pressure in the high-pressure chamber in preparation for deflation;

[0036] When deflation is required:

[0037] S1, opening the low-pressure connecting port to allow the low-pressure chamber to connect to the external air pressure;

[0038] S2: Open the air charging and discharging pipe and the air expansion pipeline, start the first-stage expander and the second-stage expander, and the high-pressure air in the high-pressure chamber enters the air expansion pipeline and is expanded by the first-stage expander and the second-stage expander before being output to the outside;

[0039] S3, while performing step S2, opening the heat recovery pipeline and starting the high-temperature pump, driving the high-temperature heat storage medium in the heat accumulator to flow in the heat recovery pipeline, driving the high-temperature heat storage medium to flow through the high-temperature sides of the primary heater and the secondary heater respectively, and then exchanging heat with the air in the air expansion pipeline to become a low-temperature heat storage medium, and then flowing back to the cold accumulator;

[0040] S4; During the deflation process, the air pressure in the high-pressure chamber continues to decrease, so that the piston gradually moves downward due to its own weight. When the piston moves down to the bottom of the high-pressure chamber, the deflation is ended, and the cooling compression device, heating expansion device, charging and discharging pipe port, low-pressure connecting port, air expansion pipeline, heat recovery pipeline and high-temperature pump are closed.

[0041] A compressed air energy storage system provided by the present invention is combined with a compressed air energy storage method provided by the present invention. When inflation is required, the external air is compressed and cooled by a cooling and compression device, and then enters and is stored in a high-pressure chamber through a charging and discharging air pipe port in a low-temperature and high-pressure state. Before inflation is required, the high-pressure connecting port is opened in advance to connect the low-pressure chamber to the high-pressure chamber, so that the low-pressure chamber is connected to the high-pressure chamber, so that the combined force of the high-pressure chamber and the low-pressure chamber on the piston is zero, and the external driving device only needs to overcome the gravity of the piston to lift the piston to the highest position of the air chamber. The mechanical loss in this process is significantly less than the energy loss in the air compression process; at the same time, after the piston is lifted to the highest position of the air chamber, the high-pressure chamber is inflated. The air compression system does not need to overcome the gravity of the piston to inflate the high-pressure chamber. At the beginning of the inflation process, the pressure in the high-pressure chamber is much lower than the pressure generated by the piston at the rated air storage pressure. Therefore, the back pressure of the air compression system is increased from the low pressure to the rated air storage pressure during the inflation process, rather than always working with the rated air storage pressure as the back pressure, so that the overall power consumption of the air compressor unit is relatively small.

[0042] When deflation is required, the high-pressure air from the high-pressure chamber and output from the charging and discharging pipe port is heated and expanded by the heating and expansion device before being output to the outside. Before deflation is required, the low-pressure chamber is connected to the external environment by opening the low-pressure connecting port in advance, so that the internal pressure of the low-pressure chamber is always equal to the ambient pressure. At this time, the pressure in the high-pressure chamber is always equal to the sum of the gravity of the upper piston and the external ambient air pressure. Therefore, during the deflation process, the pressure on the air expander connected to the high-pressure chamber through the charging and discharging pipe port is also always equal to the sum of the gravity of the piston and the external ambient air pressure. Therefore, the stability of the air intake pressure of the air expander can be guaranteed, and the stable exhaust of the high-pressure chamber can be achieved. At the same time, since the stability of the deflation pressure of the high-pressure chamber during the deflation process is achieved, there is no need to set an additional throttling device in the deflation system, and during the continuous deflation of the high-pressure chamber, the piston can use its own gravity to automatically drop to the lowest position at the bottom in the high-pressure chamber, so that almost all the air in the high-pressure chamber can be discharged, and the system does not have the problems of throttling loss and low gas storage utilization rate.

[0043] Therefore, the compressed air energy storage system and method of the present invention can solve the problems of unstable expander intake pressure and throttling loss in the compressed air energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the 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 creative work.

[0045] Figure 1It is a schematic diagram of the overall structure of the present invention.

[0046] Reference numerals:

[0047] 1 air cavity, 2 charging and discharging pipe port, 3 piston, 4 low-pressure cavity, 5 high-pressure cavity, 6 low-pressure connecting port, 7 high-pressure connecting port, 8 air compression pipeline, 9 air expansion pipeline, 10 cold storage device, 11 heat storage device, 12 low-temperature pump, 13 high-temperature pump, 14 primary cooler, 15 secondary cooler, 16 primary compressor, 17 secondary compressor, 18 primary heater, 19 secondary heater, 20 primary expander, 21 secondary expander, 100 heat storage pipeline, 101 heat recovery pipeline. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the drawings of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0049] Embodiment 1

[0050] Combine the following Figure 1A compressed air energy storage system of the present invention is described, which includes an air chamber 1 and a charging and discharging air pipe port 2. A piston 3 that can move up and down is installed in the air chamber 1. The piston 3 is sealed and well lubricated with the inner wall of the air chamber 1 and can move up and down freely. The piston 3 separates the air chamber 1 into an upper low-pressure chamber 4 and a lower high-pressure chamber 5. When the piston 3 moves up and down, the volumes of the high-pressure chamber 5 and the low-pressure chamber 4 will be expanded or reduced accordingly. The low-pressure chamber 4 is provided with a low-pressure connecting port 6 that can be connected to the outside world. When the low-pressure connecting port 6 is opened, the low-pressure chamber 4 is connected to the external environment and the pressure is balanced. A high-pressure connecting port 7 that can connect the low-pressure chamber 4 and the high-pressure chamber 5 is provided on the piston 3. When the high-pressure connecting port 7 is opened, the high-pressure chamber 5 is connected to the low-pressure chamber 4 and the pressure is balanced. The charging and discharging air pipe port 2 is connected to the bottom of the high-pressure chamber 5. When the charging and discharging air is discharged, the piston 3 When the nozzle 2 is opened, high-pressure air can enter or discharge the high-pressure chamber 5, close the high-pressure connecting port 7, and the resultant force generated by the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 4 acts on the piston 3. If the resultant force is less than the weight of the piston 3, the piston 3 will move downward due to its own weight and compress the volume of the high-pressure chamber 5 until the resultant force generated by the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 4 is equal to the weight of the piston 3, and the piston 3 is balanced and suspended in the air; on the contrary, if the resultant force generated by the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 4 is greater than the weight of the piston 3, the piston 3 moves upward and compresses the volume of the low-pressure chamber 4 until the resultant force generated by the pressure difference between the high-pressure chamber 5 and the low-pressure chamber 4 is equal to the weight of the piston 3, and the piston 3 is balanced and suspended in the air; the piston 3 can also be forced to move up and down under the action of an external driving mechanism, or forced to be stationary under the action of a braking mechanism. In addition, the charging and discharging nozzles 2 are respectively connected to a cooling and compression device for charging and a heating and expansion device for deflation.

[0051] When inflation is required, the outside air is compressed and cooled by the cooling and compression device, and then enters and is stored in the high-pressure chamber 5 through the charging and discharging pipe port 2 in a low-temperature and high-pressure state. Before inflation is required, the high-pressure connecting port 7 is opened in advance to connect the low-pressure chamber 4 to the high-pressure chamber 5, so that the low-pressure chamber 4 is connected to the high-pressure chamber 5, so that the combined force of the high-pressure chamber 5 and the low-pressure chamber 4 on the piston 3 is zero. The external driving device only needs to overcome the gravity of the piston 3 to lift the piston 3 to the highest position of the air chamber 1. The mechanical loss in this process is significantly less than the energy loss in the air compression process. At the same time, after the piston 3 is lifted to the highest position of the air chamber 1, the high-pressure chamber 5 is inflated. The air compression system does not need to overcome the gravity of the piston 3 to inflate the high-pressure chamber 5. At the beginning of the inflation process, the pressure in the high-pressure chamber 5 is much lower than the pressure generated by the piston 3 at the rated gas storage pressure. Therefore, the back pressure of the air compression system is increased from the low pressure to the rated gas storage pressure during the inflation process, rather than always working with the rated gas storage pressure as the back pressure, so that the overall power consumption of the air compressor unit is small.

[0052] When deflation is required, the high-pressure air from the high-pressure chamber 5 and output from the gas charging and discharging pipe port 2 is heated and expanded by the heating and expansion device before being output to the outside. Before deflation is required, the low-pressure chamber 4 is connected to the external environment by opening the low-pressure connecting port 6 in advance, so that the internal pressure of the low-pressure chamber 4 is always equal to the ambient pressure. At this time, the pressure in the high-pressure chamber 5 is always equal to the sum of the gravity of the upper piston 3 and the external ambient air pressure. Therefore, during the deflation process, the pressure received by the air expander connected to the high-pressure chamber 5 through the gas charging and discharging pipe port 2 is also always equal to the sum of the gravity of the piston 3 and the external ambient air pressure. Therefore, the stability of the air intake pressure of the air expander can be guaranteed, and the stable exhaust of the high-pressure chamber 5 is achieved. At the same time, since the stability of the deflation pressure of the high-pressure chamber 5 during the deflation process is achieved, there is no need to set an additional throttling device in the deflation system, and during the continuous deflation of the high-pressure chamber 5, the piston 3 can use its own gravity to automatically drop to the lowest position at the bottom in the high-pressure chamber 5, so that almost all the air in the high-pressure chamber 5 can be discharged, and the system does not have the problems of throttling loss and low gas storage utilization rate. Therefore, the present invention can solve the problems of unstable expander intake pressure and throttling loss in the compressed air energy storage system.

[0053] Specifically, the cooling and compression device includes an air compression pipeline 8 connected to the air charging and discharging pipe port 2, an air compression unit and an air cooling unit. The air compression pipeline 8 connects the high-temperature side of the air compression unit and the air cooling unit. The outside air entering the air compression pipeline 8 is compressed by the air compression unit and cooled by the air cooling unit before entering the air charging and discharging pipe port 2. During inflation, the outside air is continuously pressurized by the air compression unit in the air compression pipeline 8. The high-temperature heat generated during the pressurization process can be cooled by the air cooling unit to avoid excessive temperature, so that the air can be stored in the high-pressure chamber 5 in a high-pressure and low-temperature state, achieving a good preservation effect.

[0054] The heating and expansion device includes an air expansion pipeline 9 connected to the gas charging and discharging pipe port 2, an air expansion unit and an air heating unit. The air expansion pipeline 9 connects the low-temperature side of the air expansion unit and the air heating unit. The high-pressure air entering the air expansion pipeline 9 from the high-pressure chamber 5 is heated by the air heating unit and expanded by the air expansion unit before being output to the outside. When deflated, the high-pressure air in the high-pressure chamber 5 enters the air expansion pipeline 9 from the gas charging and discharging pipe port 2, and then after being heated by the air heating unit and expanded by the air expansion unit, the high-pressure air gradually expands and releases, and can be discharged and output to the outside more stably.

[0055] As a further supplement and improvement to this embodiment, a cold accumulator 10 and a heat accumulator 11 are also included. A heat storage pipeline 100 is connected between the cold accumulator 10 and the heat accumulator 11, and the heat storage pipeline 100 is connected to the low-temperature side of the air cooling unit. A heat recovery pipeline 101 is also connected between the cold accumulator 10 and the heat accumulator 11, and the heat recovery pipeline 101 is connected to the high-temperature side of the air heating unit. The low-temperature heat storage medium is output from the cold storage device 10, and flows through the low-temperature side of the air cooling unit through the heat storage pipeline 100 to heat exchange and heat up to become a high-temperature heat storage medium, and flows back to the heat storage device 11 through the heat storage pipeline 100, and the high-temperature heat storage medium with a higher temperature is recovered into the heat storage device 11, realizing heat recovery, and it will be reused when it is subsequently deflated; when it is necessary to deflate, the high-temperature heat storage medium stored in the heat storage device 11 is output from the heat storage device 11, and flows through the high-temperature side of the air heating unit through the heat recovery pipeline 101 to heat exchange and cool down to become a low-temperature heat storage medium again, and flows back to the cold storage device 10 through the heat recovery pipeline 101, and the low-temperature heat storage medium with a lower temperature is recovered into the cold storage device 10, realizing the recovery of residual cold, and it will be reused when it is subsequently charged. Thus, the recycling of heat is realized.

[0056] As a further supplement and improvement to this embodiment, a low-temperature heat storage medium outlet of the cold accumulator 10 is installed with a low-temperature pump 12, through which the low-temperature heat storage medium can be driven to be output from the cold accumulator 10 and flow in the heat storage pipeline 100; similarly, a high-temperature heat storage medium outlet of the heat accumulator 11 is installed with a high-temperature pump 13, through which the high-temperature heat storage medium can be driven to be output from the heat accumulator 11 and flow in the heat recovery pipeline 101.

[0057] Specifically, the air cooling unit includes a primary cooler 14 and a secondary cooler 15, the air compression unit includes a primary compressor 16 and a secondary compressor 17, and the charge and discharge air pipe port 2 is connected in series with the secondary cooler 15, the secondary compressor 17, the primary cooler 14, and the primary compressor 16 in sequence; the number of the heat storage pipelines 100 is two, and the two heat storage pipelines are connected in parallel and are respectively connected in series with the low temperature sides of the primary cooler 14 and the secondary cooler 15;

[0058] The low-temperature heat storage medium flows through the low-temperature sides of the primary cooler 14 and the secondary cooler 15 through two parallel heat storage pipelines 100 to undergo heat exchange and heat increase, becoming a high-temperature heat storage medium, and then flows back to the heat storage device 11 .

[0059] The air heating unit includes a primary heater 18 and a secondary heater 19, and the air expansion unit includes a primary expander 20 and a secondary expander 21. The charge and discharge air pipe port 2 is connected in series with the primary heater 18, the primary expander 20, the secondary heater 19, and the secondary expander 21 in sequence; the number of the heat recovery pipelines 101 is two, and the two heat recovery pipelines are connected in parallel and are respectively connected in series with the high temperature sides of the primary heater 18 and the secondary heater 19;

[0060] The high-temperature heat storage medium flows through the high-temperature sides of the primary heater 18 and the secondary heater 19 through two parallel heat recovery pipes 101 for heat exchange and cooling, becomes a low-temperature heat storage medium, and flows back to the cold storage device 10 respectively.

[0061] The operating method of the compressed air energy storage system in the above embodiment is as follows:

[0062] like Figure 1 As shown, before inflation or deflation or after inflation or deflation is completed, the cooling compression device, the heating expansion device, the inflation and deflation pipe port 2, the low-pressure connecting port 6, the high-pressure connecting port 7, the air compression pipeline 8, the air expansion pipeline 9, the heat storage pipeline 100 and the heat recovery pipeline 101 are in a closed state by default. When the low-pressure connecting port 6 is opened, the pressure required by the high-pressure chamber 5 to make the piston 3 freely suspended in the air is P1;

[0063] When inflation is required, the following steps are included:

[0064] S1, open the high-pressure connecting port 7, so that the low-pressure chamber 4 is connected to the high-pressure chamber 5, so that the pressures in the high-pressure chamber 5 and the low-pressure chamber 4 are balanced, and the balanced pressure P2 is less than P1;

[0065] S2, controlling the piston 3 to rise to the top position of the air chamber 1 through an external driving mechanism, and controlling the piston 3 to be stationary through a braking mechanism;

[0066] S3, close the high-pressure connecting port 7, open the gas charging and discharging port 2 and the air compression pipeline 8, start the primary compressor 16 and the secondary compressor 17, and when the resistance loss along the way is ignored, the initial back pressure of the secondary compressor 17 is P2, and the power consumption of the air compressor group is W2;

[0067] When the outside air enters the high-pressure chamber 5 from the air compression pipeline 8, it is continuously compressed by the primary compressor 16 and the secondary compressor 17, so that the air pressure of the high-pressure chamber 5 continues to rise. As the inflation process proceeds, the air volume in the high-pressure chamber 5 gradually increases, the pressure gradually rises, the back pressure of the secondary compressor 17 gradually increases, and the power consumption gradually increases;

[0068] S4, while performing step S3, opening the heat storage pipeline 100 and starting the cryogenic pump 12, driving the low-temperature heat storage medium in the cold storage device 10 to flow in the heat storage pipeline 100, driving the low-temperature heat storage medium to flow through the low-temperature sides of the primary cooler 14 and the secondary cooler 15 respectively, and then exchanging heat with the air in the air compression pipeline 8 to become a high-temperature heat storage medium, and then flowing back to the heat storage device 11;

[0069] S5; when the back pressure of the secondary compressor 17 rises to P1, the power consumption of the air compressor unit rises to the maximum W1, and the inflation is completed, the cooling compression device, the gas charging and discharging pipe port 2, the high-pressure connecting port 7, the air compression pipeline 8, the heat storage pipeline 100 and the cryogenic pump 12 are closed, and the brake mechanism is released, so that the piston 3 remains freely suspended under the support of the high air pressure in the high-pressure chamber 5, in preparation for deflation;

[0070] When deflation is required, the following steps are included:

[0071] S1, open the low-pressure connecting port 6 to connect the low-pressure chamber 4 to the external air pressure. At this time, the piston 3 is balanced and the pressure in the high-pressure chamber 5 is P1;

[0072] S2; open the gas charging and discharging port 2 and the air expansion pipeline 9, start the primary expander 20 and the secondary expander 21, the high-pressure air in the high-pressure chamber 5 enters the air expansion pipeline 9 and is expanded by the primary expander 20 and the secondary expander 21 before being output;

[0073] At the moment when the gas charging and discharging pipe port 2 starts to exhaust gas outward, the gas volume in the high-pressure chamber 5 decreases and the pressure decreases. The force balance of the trend piston 3 is broken and moves downward to maintain the pressure of the high-pressure chamber 5 at P1. Since the pipeline resistance characteristics from the gas charging and discharging pipe port 2 to the outlet of the secondary expander 21 remain unchanged, the piston 3 moves downward at a constant speed during the entire deflation process, and the pressure in the high-pressure chamber 5 is stabilized at P1. Therefore, the exhaust pressure of the gas charging and discharging pipe port 2 is stabilized at P1, so that both the primary expander 20 and the secondary expander 21 work under stable pressure conditions, ensuring stable output pressure;

[0074] S3, while performing step S2, opening the heat recovery pipeline 101 and starting the high-temperature pump 13, driving the high-temperature heat storage medium in the heat storage device 11 to flow in the heat recovery pipeline 101, driving the high-temperature heat storage medium to flow through the high-temperature sides of the primary heater 18 and the secondary heater 19 respectively, and then exchanging heat with the air in the air expansion pipeline 9 to become a low-temperature heat storage medium, and then flowing back to the cold storage device 10;

[0075] S4; During the deflation process, the air pressure in the high-pressure chamber 5 continues to decrease, so that the piston 3 gradually moves downward due to its own weight. When the piston 3 moves down to the bottom of the high-pressure chamber 5 and cannot move further downward, the air in the high-pressure chamber 5 is completely discharged, and the deflation is ended. The cooling compression device, the heating expansion device, the charging and discharging pipe port 2, the low-pressure connecting port 6, the air expansion pipeline 9, the heat recovery pipeline 101 and the high-temperature pump 13 are closed to prepare for the next inflation process.

[0076] During the inflation process of this embodiment, when the piston 3 does not move to the minimum volume state of the low-pressure chamber 4 or when the piston 3 does not move to the minimum volume state of the high-pressure chamber 5 during the deflation process, if the compressed air energy storage system fails or receives an external stop operation command, the inflation process or the deflation process ends.

[0077] Embodiment 2

[0078] This embodiment is similar to the first embodiment, except that the inflation method in the operation method is different, as follows:

[0079] S1, using a braking mechanism to control the piston 3 to be stationary;

[0080] S2, open the high-pressure connecting port 7, so that the low-pressure chamber 4 is connected to the high-pressure chamber 5, so that the pressures in the high-pressure chamber 5 and the low-pressure chamber 4 are balanced, and the balanced pressure P2 is less than P1;

[0081] S3, open the air charging and discharging pipe port 2 and the air compression pipeline 8, start the primary compressor 16 and the secondary compressor 17, and when the resistance loss along the way is ignored, the initial back pressure of the secondary compressor 17 is P2, and the power consumption of the air compressor group is W2;

[0082] When the outside air enters the high-pressure chamber 5 from the air compression pipeline 8, it is continuously compressed by the primary compressor 16 and the secondary compressor 17, so that the air pressure of the high-pressure chamber 5 continues to rise. As the inflation process proceeds, the air volume in the high-pressure chamber 5 gradually increases, the pressure gradually rises, the back pressure of the secondary compressor 17 gradually increases, and the power consumption gradually increases;

[0083] S4, while performing step S3, opening the heat storage pipeline 100 and starting the cryogenic pump 12, driving the low-temperature heat storage medium in the cold storage device 10 to flow in the heat storage pipeline 100, driving the low-temperature heat storage medium to flow through the low-temperature sides of the primary cooler 14 and the secondary cooler 15 respectively, and then exchanging heat with the air in the air compression pipeline 8 to become a high-temperature heat storage medium, and then flowing back to the heat storage device 11;

[0084] S5, when the back pressure of the secondary compressor 17 rises to P1, the power consumption of the air compressor unit rises to the maximum W1, and the charging is completed, and the cooling compression device, the charging and discharging pipe port 2, the high-pressure connecting port 7, the air compression pipeline 8, the heat storage pipeline 100 and the cryogenic pump 12 are closed;

[0085] S6, the brake mechanism releases the piston 3 and at the same time uses an external drive mechanism to lift the piston 3 to the highest position of the air chamber 1, and then stops the piston 3 through the brake mechanism, and finally closes the high-pressure connecting port 7 to keep the piston 3 freely suspended under the support of the high air pressure in the high-pressure chamber 5, in preparation for deflation.

[0086] The deflation process is the same as that of the first embodiment.

[0087] Embodiment 3

[0088] This embodiment is similar to the first embodiment, except that the inflation method in the operation method is different, as follows:

[0089] When inflation is required, the following steps are included:

[0090] S1, open the low-pressure connecting port 6, the air charging and discharging port 2 and the air compression pipeline 8 to balance the pressure in the high-pressure chamber 5 and the low-pressure chamber 4, and the balanced pressure P2<P1;

[0091] S2, start the primary compressor 16 and the secondary compressor 17. When the outside air enters the high-pressure chamber 5 from the air compression pipeline 8, it is continuously compressed by the primary compressor 16 and the secondary compressor 17, so that the air pressure in the high-pressure chamber 5 continues to rise and pushes the piston 3 to move upward. The initial back pressure of the secondary compressor 17 is P2;

[0092] S3, while performing step S2, opening the heat storage pipeline 100 and starting the cryogenic pump 12, driving the low-temperature heat storage medium in the cold storage device 10 to flow in the heat storage pipeline 100, driving the low-temperature heat storage medium to flow through the low-temperature sides of the primary cooler 14 and the secondary cooler 15 respectively, and then exchanging heat with the air in the air compression pipeline 8 to become a high-temperature heat storage medium, and then flowing back to the heat storage device 11;

[0093] S5; when the back pressure of the secondary compressor 17 rises to P1, the inflation is completed, and the cooling compression device, the charging and discharging pipe port 2, the low-pressure connecting port 6, the air compression pipeline 8, the heat storage pipeline 100 and the cryogenic pump 12 are closed, so that the piston 3 remains freely suspended under the support of the high air pressure in the high-pressure chamber 5, in preparation for deflation.

[0094] The deflation process is the same as that of the first embodiment.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A compressed air energy storage system, comprising an air cavity (1) and a charging and discharging air pipe port (2), characterized in that: A piston (3) capable of moving up and down is arranged in the air chamber (1), and the piston (3) separates the air chamber (1) into an upper low-pressure chamber (4) and a lower high-pressure chamber (5). The low-pressure chamber (4) is provided with a low-pressure connecting port (6) capable of connecting to the outside, and a high-pressure connecting port (7) capable of connecting the low-pressure chamber (4) and the high-pressure chamber (5) is arranged on the piston (3). The charging and discharging pipe port (2) is connected to the bottom of the high-pressure chamber (5), and the charging and discharging pipe port (2) is respectively connected to a cooling and compression device for charging and a heating and expansion device for discharging. The cooling and compression device comprises an air compression pipeline (8) connected to the air charging and discharging pipe port (2), an air compression unit and an air cooling unit. The air compression pipeline (8) connects the high-temperature side of the air compression unit and the air cooling unit. The outside air entering the air compression pipeline (8) is compressed by the air compression unit and cooled by the air cooling unit before entering the air charging and discharging pipe port (2). The heating and expansion device comprises an air expansion pipeline (9) connected to the air charging and discharging pipe port (2), an air expansion unit and an air heating unit. The air expansion pipeline (9) connects the low-temperature side of the air expansion unit and the air heating unit. The high-pressure air entering the air expansion pipeline (9) from the high-pressure chamber (5) is heated by the air heating unit and expanded by the air expansion unit before being output to the outside. It also comprises a cold storage device (10) and a heat storage device (11), wherein a heat storage pipeline (100) is connected between the cold storage device (10) and the heat storage device (11), and the heat storage pipeline (100) is connected to the low-temperature side of the air cooling unit; and a heat recovery pipeline (101) is also connected between the cold storage device (10) and the heat storage device (11), and the heat recovery pipeline (101) is connected to the high-temperature side of the air heating unit; The air cooling unit comprises a primary cooler (14) and a secondary cooler (15); the air compression unit comprises a primary compressor (16) and a secondary compressor (17); the air charging and discharging pipe port (2) is connected in series with the secondary cooler (15), the secondary compressor (17), the primary cooler (14), and the primary compressor (16) in sequence; the number of the heat storage pipelines (100) is two, and the two heat storage pipelines are connected in parallel and are respectively connected in series with the low-temperature sides of the primary cooler (14) and the secondary cooler (15); The low-temperature heat storage medium flows through the low-temperature sides of the primary cooler (14) and the secondary cooler (15) through two parallel heat storage pipelines (100) to undergo heat exchange and heat increase, becoming a high-temperature heat storage medium, and then flows back to the heat storage device (11). The air heating unit comprises a primary heater (18) and a secondary heater (19); the air expansion unit comprises a primary expander (20) and a secondary expander (21); the gas charging and discharging pipe port (2) is connected in series with the primary heater (18), the primary expander (20), the secondary heater (19), and the secondary expander (21) in sequence; the number of the heat recovery pipelines (101) is two, and the two heat recovery pipelines are connected in parallel and are respectively connected in series with the high-temperature sides of the primary heater (18) and the secondary heater (19); The high-temperature heat storage medium flows through the high-temperature sides of the primary heater (18) and the secondary heater (19) through two parallel heat recovery pipes (101) to undergo heat exchange and cooling, becoming a low-temperature heat storage medium, and then flows back to the cold storage device (10).

2. The compressed air energy storage system according to claim 1, characterized in that: The low-temperature heat storage medium is output from the cold storage device (10), flows through the low-temperature side of the air cooling unit through the heat storage pipeline (100), undergoes heat exchange and is heated to become a high-temperature heat storage medium, and flows back to the heat storage device (11) through the heat storage pipeline (100); The high-temperature heat storage medium is output from the heat storage device (11), flows through the high-temperature side of the air heating unit through the heat recovery pipeline (101), undergoes heat exchange and is cooled to become a low-temperature heat storage medium, and flows back to the cold storage device (10) through the heat recovery pipeline (101).

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