Compressed air energy storage system

Abstract

The utility model discloses a compressed air energy storage system, which relates to the technical field of novel energy storage and comprises a compressor unit, the compressor unit comprises at least two stages of compressors, and an air storage air inlet heat exchanger is arranged at an outlet of the last stage of compressor; a hot side inlet of the gas storage gas inlet heat exchanger is communicated with an outlet of the final-stage compressor, a hot side outlet of the gas storage gas inlet heat exchanger is communicated with a gas storage inlet, and a cold source is arranged on the cold side of the gas storage gas inlet heat exchanger. The compressed air energy storage system provided by the utility model solves the technical problem that the influence of increasing the pressure of the compressed air and the volume of the air storage on increasing the discharge duration of the system is not obvious in practical engineering application.

Description

TECHNICAL FIELD

[0001] The utility model relates to novel energy storage technology field especially, relates to a compressed air energy storage system. BACKGROUND

[0002] The compressed air energy storage system is one kind of electric power energy storage system, which stores electric energy by compressing air. At present, the compressed air energy storage technology is the second largest technology considered to be suitable for GW-level large-scale electric power energy storage after pumped storage. The basic principle of compressed air energy storage is to use the electric energy in the low valley period of power grid load to drive the compressor unit to compress air into the air storage device to store electric energy. In the peak period of power grid load, the compressed air is released to drive the expander to generate electricity and release energy.

[0003] Long-time large-scale energy storage technology is the key to energy transformation and the improvement of power system flexibility, and they will play an increasingly important role in future energy systems. Long-time large-scale energy storage refers to long time scale and large energy storage capacity. In the compressed air energy storage, to achieve long-time large-scale energy storage, those skilled in the art can easily think of increasing the number of compressors in series in the compression stage to increase the pressure of compressed air, and increasing the volume of the air storage to achieve it. However, in actual engineering applications, increasing the pressure of compressed air and the volume of the air storage has little effect on increasing the discharge time of the system, and it is difficult to achieve long-time large-scale compressed air energy storage by only the above means. SUMMARY

[0004] The purpose of the utility model is to provide a long-time large-scale compressed air energy storage system.

[0005] To achieve this purpose, on the one hand, a compressed air energy storage system is provided, which includes a compressor unit, the compressor unit includes at least two stages of compressors, and an air storage inlet heat exchanger is arranged at the outlet of the last stage of compressors; the hot side inlet of the air storage inlet heat exchanger is in communication with the outlet of the last stage of compressors, the hot side outlet of the air storage inlet heat exchanger is in communication with the air storage inlet, and the cold side of the air storage inlet heat exchanger has a cold source.

[0006] Further, it further includes a heat storage unit, the heat storage unit includes a hot water tank and at least one heat recovery heat exchanger, one of the heat recovery heat exchangers is arranged at the outlet side of each stage of compressors from the outlet side of the first stage of compressors to the last stage of compressors, and the compression heat is recovered into the hot water tank through the heat recovery heat exchanger; the hot side inlet of the heat recovery heat exchanger is in communication with the outlet of the compressor, the hot side outlet of the heat recovery heat exchanger is in communication with the inlet of the next stage of compressors, the cold side inlet of the heat recovery heat exchanger is in communication with the outlet of the cold water tank, and the cold side outlet of the heat recovery heat exchanger is in communication with the inlet of the hot water tank.

[0007] Further, the heat storage unit further comprises a cold water tank and at least one reheating heat exchanger, through which the temperature of the inlet compressed air of the expander is raised by using the heat in the hot water tank.

[0008] Further, the cold source uses one of a condenser, a water chiller and a cooling tower.

[0009] Further, the cold source uses an open cooling tower.

[0010] Further, an intermediate cooling heat exchanger is further included, a hot side of the intermediate cooling heat exchanger forms a closed loop with a cold side of the gas storage intake heat exchanger, and a cold side of the intermediate cooling heat exchanger forms a closed loop with the open cooling tower.

[0011] Further, a water supplementing port is further provided on a pipeline between a hot side outlet of the intermediate cooling heat exchanger and a cold side inlet of the gas storage intake heat exchanger, and a pressure stabilizing device is arranged on the water supplementing port.

[0012] Further, the cold source uses a closed cooling tower.

[0013] Further, a water supplementing port is further provided on a pipeline between a hot side outlet of the intermediate cooling heat exchanger and a cold side inlet of the gas storage intake heat exchanger, and a pressure stabilizing device is arranged on the water supplementing port.

[0014] In another aspect, a compressed air energy storage system is provided, which comprises a compressor set including at least two stages of compressors, a gas storage intake heat exchanger is arranged at an outlet of the last stage of compressors, a hot side inlet of the gas storage intake heat exchanger is communicated with the outlet of the last stage of compressors, a hot side outlet of the gas storage intake heat exchanger is communicated with a gas storage inlet, and a cold source is arranged at a cold side of the gas storage intake heat exchanger.

[0015] One of the above technical solutions has the following advantages or beneficial effects:

[0016] The compressor set of the compressed air energy storage system in the present solution includes at least two stages of compressors, a gas storage intake heat exchanger is arranged at an outlet of the last stage of compressors, a hot side inlet of the gas storage intake heat exchanger is communicated with the outlet of the last stage of compressors, a hot side outlet of the gas storage intake heat exchanger is communicated with a gas storage inlet, and a cold source is arranged at a cold side of the gas storage intake heat exchanger.

[0017] Since the cold quantity of the cold source is controllable, the cold quantity of the cold source can be set to be large enough. The temperature and pressure of the outlet of the final-stage compressor are high, when the compressed air at the outlet of the final-stage compressor enters or exits the heat side of the air reservoir inlet heat exchanger, in the air reservoir inlet heat exchanger, the temperature of the high-pressure air can be rapidly reduced by adjusting the cold quantity of the cold source, so that the temperature of the compressed air entering the air reservoir can be low enough. Therefore, the compressed air energy storage system of the scheme can not reduce the actual volume of the air reservoir, because the temperature of the compressed air entering the air reservoir is low enough. Therefore, the compressed air energy storage system of the scheme can realize long-time large-scale energy storage by increasing the air storage pressure and the air reservoir volume. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a compressed air energy storage system of the embodiment;

[0019] Figure 2 is another compressed air energy storage system of the embodiment.

[0020] In the figure: 110-first stage compressor; 120-second stage compressor; 130-third stage compressor; 210-cooling tower; 220-intermediate cooling heat exchanger; 221-buffer water tank; 231-water supplement inlet; 232-pressure stabilizing tank; 233-water supplement pump; 234-pressure stabilizing water tank; 310-air reservoir inlet heat exchanger; 320-recuperation heat exchanger; 330-cold water tank; 340-hot water tank; 350-reheating heat exchanger; 222, 331, 332-circulating pump; 400-component cooling heat exchanger; 500-expander; 600-air reservoir. DETAILED DESCRIPTION

[0021] In order to make the technical problems solved by the utility model, the technical scheme adopted and the technical effects achieved more clear, the technical scheme of the embodiment of the utility model will be further described in detail below in combination with the drawings. Obviously, the described embodiment is only a part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor belong to the protection scope of the utility model. It should be noted that the following embodiments and the features in the embodiments can be combined with each other without conflict.

[0022] The inventors found that the most direct means to increase the compressed air pressure is to increase the number of compressors in series in the compression stage. However, as the number of compressors increases, the pressure and temperature of the compressed air at the outlet of the later-stage compressors will increase, which will cause the temperature of the compressed air entering the gas reservoir to increase, causing the pressure and temperature in the gas reservoir to increase, thereby causing the gas density in the gas reservoir to decrease. The decrease in the gas density in the gas reservoir will cause the density difference per unit of gas storage volume to decrease, resulting in the actual gas storage capacity in the gas reservoir being less than the rated gas storage capacity. The actual gas storage capacity in the gas reservoir being less than the rated gas storage capacity will directly cause the output power of the system to decrease when energy is released, resulting in a decrease in the amount of electricity released by the system. Therefore, even if the pressure of the compressed air and the volume of the gas reservoir are increased, the energy storage efficiency of the system is difficult to significantly improve.

[0023] As shown in Figures 1-2 The embodiment provides a compressed air energy storage system, which comprises a compressor set, the compressor set comprising at least two compressors, a gas reservoir inlet heat exchanger 310 being arranged at the outlet of the last-stage compressor, the hot side inlet of the gas reservoir inlet heat exchanger 310 being in communication with the outlet of the last-stage compressor, and the hot side outlet of the gas reservoir inlet heat exchanger 310 being in communication with the gas reservoir inlet. The cold side of the gas reservoir inlet heat exchanger 310 has a cold source. Since the cold capacity of the cold source is controllable, the cold capacity of the cold source can be set to be large enough. The last-stage compressor refers to the last-stage compressor in the compressor set, and the compressed air at the outlet of the last-stage compressor will be stored in the gas reservoir. The temperature and pressure at the outlet of the last-stage compressor are very high, and when the compressed air at the outlet of the last-stage compressor enters and exits the hot side of the gas reservoir inlet heat exchanger 310, the temperature of the high-pressure air can be rapidly reduced in the gas reservoir inlet heat exchanger 310 by adjusting the cold capacity of the cold source, so that the temperature of the compressed air entering the gas reservoir can be sufficiently low, thereby avoiding an increase in the temperature in the gas reservoir, so that the actual volume of the gas reservoir will not decrease. Therefore, the compressed air energy storage system of the embodiment can realize long-term large-scale energy storage by increasing the gas storage pressure and the volume of the gas reservoir.

[0024] As described above, the temperature of the compressed air entering the air storage tank is reduced by installing an air storage tank inlet heat exchanger 310 at the outlet of the final stage compressor. If the compressed air energy storage system has many stages, and the pressure and temperature at the outlets of the last few stage compressors are relatively high, then an air storage tank inlet heat exchanger 310 is installed at the outlet of each of the last few stage compressors. In this case, the hot-side inlet of the air storage tank inlet heat exchanger at the outlet of the last stage compressor is connected to the outlet of the last stage compressor, and the hot-side outlet of the air storage tank inlet heat exchanger is connected to the inlet of the air storage tank; the cold side of the air storage tank inlet heat exchanger has a cold source. The hot-side inlets of the air storage tank inlet heat exchangers at the outlets of the last few stage compressors (excluding the last stage compressor) are connected to the outlet of their respective stage compressors, and the hot-side outlets of the air storage tank inlet heat exchangers are connected to the inlet of the next stage compressor. The cold side of all the air storage tank inlet heat exchangers is connected to a cold source. That is, the hot-side outlet of the last stage air storage tank heat exchanger is connected to the air storage tank, and the hot-side outlets of the remaining air storage tank heat exchangers are connected to the next stage compressor. For example, when the outlets of the last two compressor stages are equipped with gas storage inlet heat exchangers, the hot-side outlet of the gas storage inlet heat exchanger on the outlet side of the penultimate compressor is connected to the inlet of the last compressor stage, and the hot-side outlet of the gas storage inlet heat exchanger on the outlet side of the last compressor stage is connected to the inlet of the gas storage.

[0025] like Figures 1-2 As shown, this embodiment provides a compressed air energy storage system including a heat storage unit. The heat storage unit recovers the heat of compression from the compressed air and uses this heat for energy release. Specifically, the heat storage unit includes a regenerative heat exchanger 320, a hot water tank 340, and a cold water tank 330. In this embodiment, water is used as the heat storage medium. Preferably, demineralized water is used. The hot water tank 340 stores a high-temperature heat storage medium, and the cold water tank 330 stores a low-temperature heat storage medium. A circulation pump 331 is installed on the outlet pipe of the cold water tank 330, and a circulation pump 332 is installed on the outlet pipe of the hot water tank 340.

[0026] The regenerative heat exchanger 320 is located on the outlet side of the primary compressor. The outlet of the primary compressor is connected to the hot-side inlet of the regenerative heat exchanger 320, and the hot-side outlet of the regenerative heat exchanger 320 is connected to the inlet of the next-stage compressor. The cold-side inlet of the regenerative heat exchanger 320 is connected to the outlet of the cold water tank 330, and the cold-side outlet of the regenerative heat exchanger 320 is connected to the inlet of the hot water tank 340, thus recovering the heat of compression into the hot water tank 340 through the regenerative heat exchanger 320.

[0027] like Figures 1-2As shown above, the heat storage unit recovers the heat of compression by installing a regenerative heat exchanger 320 at the outlet of the first-stage compressor, and uses the aforementioned heat of compression in the energy release process. If the compressed air energy storage system has a large number of stages, a regenerative heat exchanger 320 can be installed at the outlet of each of the first few compressor stages, and the connection method between each regenerative heat exchanger 320 and the hot water tank 340 and the cold water tank 330 is as described above.

[0028] like Figures 1-2 As shown, the heat storage unit also includes a reheat heat exchanger 350. During energy release, the compressed air in the gas storage tank 600 is at a low temperature, and its direct entry into the expander would affect the expander's work capacity. In this embodiment, the reheat heat exchanger 350 utilizes the heat from the hot water tank 340 to heat the compressed air entering the expander. Specifically, the outlet of the gas storage tank 600 is connected to the cold-side inlet of the reheat heat exchanger 350, the cold-side outlet of the reheat heat exchanger 350 is connected to the inlet of the primary expander, the hot-side inlet of the reheat heat exchanger 350 is connected to the outlet of the hot water tank 340, and the hot-side outlet of the reheat heat exchanger 350 is connected to the inlet of the cold water tank 330. The heat from the hot water tank 340 is used to increase the temperature of the compressed air entering the expander, thereby achieving energy recovery and improving the system efficiency of the compressed air energy storage system.

[0029] like Figures 1-2 As shown, the expander 350 can have multiple stages. The inlet of the first-stage expander is connected to the outlet of the gas storage tank 600. The inlet of each subsequent expander is connected to the outlet of the previous expander. The air pressure at the outlet of the final stage compressor is extremely low and is directly discharged into the atmosphere. Each expander inlet is equipped with a reheat heat exchanger 350 to improve the system's power generation efficiency.

[0030] Figures 1-2The diagram illustrates an implementation of a compressor unit comprising three compressor stages. A regenerative heat exchanger 320 is installed at the outlets of the first-stage compressor 110 and the second-stage compressor 120, respectively, and a storage tank inlet heat exchanger 310 is installed at the outlet of the third-stage compressor 130. Currently, in long-term, large-scale compressed air energy storage systems, compressor units typically include at least six compressor stages. In such cases, the starting point for installing the storage tank inlet heat exchanger 310 can be determined based on the compressor outlet temperature. For example, a regenerative heat exchanger 320 is installed at the outlet of the first five compressor stages to recover compression heat, and starting from the sixth compressor outlet, a storage tank inlet heat exchanger 310 is installed at the outlet of each compressor stage. Therefore, the compressed air energy storage system of this embodiment recovers sufficient compression heat while ensuring that the temperature of the compressed air entering the storage tank 600 is sufficiently low, allowing the storage capacity within the storage tank 600 to approach its rated value. Therefore, the compressed air energy storage system of this embodiment can improve the energy release time and power generation of compressed air energy storage by providing compressed air pressure and a storage tank volume of 600. It can realize charge and discharge cycles across days, months and even seasons to meet the long-term stability requirements of the power system and can be used for long-term large-scale energy storage systems.

[0031] The cold source on the cold side of the 600 inlet heat exchanger in the gas storage facility can be a cold source that can be a cooling system commonly used in existing industrial settings, such as air-cooled condensers, water-cooled condensers, screw chillers, centrifugal chillers, absorption chillers, liquid nitrogen cooling systems, ground source heat pump cooling systems, and microchannel heat exchangers.

[0032] like Figures 1-2 As shown, in this embodiment, the aforementioned cold source uses a cooling tower, which maintains the system's low-temperature state by dissipating heat. Cooling towers are classified into open-type and closed-type cooling towers. The cooling principles of open-type and closed-type cooling towers differ. Open-type cooling towers cool by directly spraying circulating water onto the tower packing material, allowing heat exchange between the water and air. A fan then drives the airflow within the tower, carrying away the heated air after heat exchange with the water, thus achieving cooling. Closed-type cooling towers consist of two circulation systems: an internal circulation and an external circulation. They lack packing material, and the main core component is a copper tube surface cooler. The internal circulation is connected to the target equipment, forming a closed-loop system (the circulation medium is soft water). The external circulation cools the cooling tower itself within the tower, without direct contact with the internal circulation water; heat exchange occurs only through the copper tube surface cooler within the tower. Figure 1 This embodiment illustrates an implementation where a closed-loop cooling tower is used as the cold source for the gas storage inlet heat exchanger 310 within the compression unit. Figure 2 This embodiment illustrates an implementation where the cold source for the gas storage inlet heat exchanger 310 within the compression unit is an open cooling tower.

[0033] Furthermore, it also includes component cooling heat exchangers 400. If a cooling tower is used as the cold source, and the cooling tower has a large cooling capacity, it can also be used to provide cooling for other components in the system, such as compressor oil stations, expander oil stations, compressor motors, expander motors, etc. There can be multiple component cooling heat exchangers 400, each corresponding to one device to be cooled. The component cooling heat exchangers 400 are connected in parallel with the gas storage tank inlet heat exchanger 310, and both are connected between the liquid inlet and liquid outlet of the cooling tower.

[0034] like Figure 1 As shown, when a closed-loop cooling tower is used, the outlet of the closed-loop cooling tower is connected to the cold-side inlet of the air inlet heat exchanger 310 of the gas storage tank, and the cold-side outlet of the air inlet heat exchanger 310 is connected to the return outlet of the closed-loop cooling tower. Since low-temperature cooling water flows through the pipe connecting the outlet of the closed-loop cooling tower to the cold-side inlet of the air inlet heat exchanger 310, while high-temperature cooling water flows through the pipe connecting the cold-side outlet of the air inlet heat exchanger 310 to the return outlet of the closed-loop cooling tower, this can lead to an imbalance in pressure within the pipe as the cooling water flows from the outlet of the closed-loop cooling tower, passes through the air inlet heat exchanger 310, and returns to the closed-loop cooling tower. This imbalance can easily cause accidents. Therefore, in this embodiment, when a closed-loop cooling tower is used, a pressure stabilizing unit is installed on the outlet pipe of the closed-loop cooling tower to adjust the water pressure within the pipe.

[0035] like Figure 1 As shown, one structure of the pressure stabilizing unit is as follows: a water inlet 231 is opened on the liquid outlet pipeline of the closed cooling tower, and one end of the monitoring pipeline of the pressure stabilizing tank 232 is connected to the water inlet. The pressure stabilizing tank 232 includes an air chamber and a water chamber, which are separated by a rubber diaphragm. The other end of the monitoring pipeline of the pressure stabilizing tank is connected to the water chamber. The set pressure is adjusted by adjusting the air volume of the air chamber. The pressure stabilizing tank 232 is used to drive the start and stop of the water supply pump 233. The pressure stabilizing water tank 234 is also connected to the water inlet through a pipeline. The water supply pump 233 is used to open or close the pipeline between the pressure stabilizing water tank and the water inlet. When the pressure in the pipeline where the water inlet is located is less than the set pressure, the pressure stabilizing tank starts the water supply pump to replenish the water inlet with liquid from the pressure stabilizing water tank. When the pressure stabilizing tank detects that the pressure has reached the set value, it shuts off the water supply pump. When the pressure in the pipeline where the water inlet is located is greater than the set pressure, it starts the water supply pump to release water, putting the excess water into the pressure stabilizing water tank. Furthermore, the pressure-stabilizing water tank is connected to the pipeline network. When the liquid level in the pressure-stabilizing water tank is low, liquid from the pipeline network enters the pressure-stabilizing water tank to replenish it. Furthermore, the pressure-stabilizing water tank contains demineralized water, which has the advantage of being less prone to scaling.

[0036] like Figure 2As shown, when using an open cooling tower, the inner bottom of the open cooling tower is a cold water pool, and the outlet of the open cooling tower is connected to the cold water pool. The inlet of the open cooling tower is located in the upper middle part of the cooling tower 210. A buffer water tank 221 is installed on the outlet pipe of the open cooling tower. When the cold water pool is full, there is no need to stop the operation of the cooling tower 210; the excess coolant can be stored in the buffer water tank 221.

[0037] like Figure 2 As shown, when using an open cooling tower, the system also includes an intermediate cooling heat exchanger 220. The hot side of the intermediate cooling heat exchanger 220 is connected to the cold side of the air inlet heat exchanger 310 of the air storage tank via a pipeline, forming a closed loop. The cold side of the intermediate cooling heat exchanger 220 is connected to the cooling tower 210. Since open cooling towers are prone to accumulating dirt and deposits, requiring frequent cleaning and maintenance, this can affect the continuous operating time of the compressed air energy storage system. Therefore, the compressed air energy storage system in this embodiment is equipped with an intermediate cooling heat exchanger 220. The hot side of the intermediate cooling heat exchanger 220 is connected to the cold side of the air inlet heat exchanger 310 of the air storage tank via a pipeline, and the cold side is connected to the cooling tower 210, separating the cooling tower 210 from the system interior. Even if the cooling tower 210 is an open cooling tower and scale forms inside the system, it will not affect the hot side pipeline of the intermediate cooling heat exchanger 220.

[0038] like Figure 2 As shown, a second circulating medium circulates in the closed loop formed by the hot side of the intermediate cooling heat exchanger 220 and the cold side of the gas storage inlet heat exchanger 310. The second circulating medium can be a medium with extremely low impurity content, such as demineralized water with extremely low impurity content.

[0039] like Figure 2 As shown, when an open cooling tower is used, there is also a water inlet 231 on the pipeline between the hot side outlet of the intermediate cooling heat exchanger 220 and the cold side inlet of the air storage tank inlet heat exchanger 310. A pressure stabilizing device is installed on the water inlet, and the connection method of the pressure stabilizing device here is the same as that of the pressure stabilizing device at the liquid outlet of the closed cooling tower.

[0040] Furthermore, a circulating pump 222 is installed on the pipeline between the hot-side outlet of the intercooling heat exchanger 220 and the cold-side inlet of the gas storage inlet heat exchanger 310 to provide power for the circulation of this closed loop. The circulating pump 222 is located at the outlet of the water inlet 231, which reduces pump power consumption, improves pump efficiency, and improves system efficiency.

[0041] Furthermore, in this embodiment, all the gas storage tank inlet heat exchangers, regenerator heat exchangers, reheat heat exchangers, intermediate cooling heat exchangers, and component cooling heat exchangers can use existing heat exchangers, such as plate heat exchangers.

[0042] In the description of the utility model, unless another definite provision and limitation, the term "link", "connection", "fix" should do broad sense understanding, for example, can be fixed connection, also can be detachable connection, or be integrated;Can be mechanical connection, also can be electrical connection;Can be directly connected, also can pass through the indirect connection of intermediate medium, can be two element internal communication or two element mutual action relation. For ordinary skilled person in the art, the specific meaning of the above-mentioned terms in the utility model can be understood according to specific circumstances.

[0043] In the utility model, unless another definite provision and limitation, the first feature is "on" or "under" the second feature can include the direct contact of the first and second features, also can include the contact of the first and second features not direct but through the additional feature between them.And, the first feature is "on", "above" and "on" the second feature includes the first feature is directly above and obliquely above the second feature, or just indicates that the horizontal height of the first feature is higher than the second feature.The first feature is "under", "below" and "under" the second feature includes the first feature is directly below and obliquely below the second feature, or just indicates that the horizontal height of the first feature is less than the second feature.

[0044] Obviously, the above embodiment of the utility model is only for clear illustration of the utility model, and is not the limitation of the embodiment of the utility model.For ordinary skilled person in the art, on the basis of the above-mentioned description, other different forms of changes or variations can be made.The need for all the embodiments is not exhausted here.The any modification, equivalent replacement and improvement, etc. made in the spirit and principle of the utility model should be included in the protection scope of the utility model claims.

Claims

1. A compressed air energy storage system, characterized in that, The compressor unit includes at least two compressor stages, and a gas storage inlet heat exchanger is provided at the outlet of the final compressor stage. The hot side inlet of the gas storage heat exchanger is connected to the outlet of the final stage compressor, the hot side outlet of the gas storage heat exchanger is connected to the gas storage inlet, and the cold side of the gas storage heat exchanger has a cold source. The cold source uses a cooling tower; it also includes an intermediate cooling heat exchanger, the hot side of which forms a closed loop with the cold side of the gas storage tank inlet heat exchanger; the cold side of which forms a closed loop with the cooling tower.

2. The compressed air energy storage system according to claim 1, characterized in that, It also includes a heat storage unit, which includes a hot water tank and at least one heat recovery heat exchanger. One heat recovery heat exchanger is provided on the outlet side of each stage compressor from the outlet side of the first stage compressor to the outlet side of the last stage compressor, and the heat of compression is recovered into the hot water tank through the heat recovery heat exchanger. The hot-side inlet of the regenerative heat exchanger is connected to the outlet of the compressor, the hot-side outlet of the regenerative heat exchanger is connected to the inlet of the next stage compressor, the cold-side inlet of the regenerative heat exchanger is connected to the outlet of the cold water tank, and the cold-side outlet of the regenerative heat exchanger is connected to the inlet of the hot water tank.

3. The compressed air energy storage system according to claim 2, characterized in that, The heat storage unit also includes a cold water tank and at least one reheat heat exchanger, through which the heat in the hot water tank is used to increase the temperature of the inlet compressed air entering the expander.

4. The compressed air energy storage system according to claim 1, characterized in that, The cooling tower can be replaced by either a condenser or a chiller unit.

5. The compressed air energy storage system according to claim 1, characterized in that, The cold source is an open cooling tower.

6. The compressed air energy storage system according to claim 5, characterized in that, It also includes an intermediate cooling heat exchanger, the hot side of which forms a closed loop with the cold side of the gas storage tank inlet heat exchanger; the cold side of the intermediate cooling heat exchanger forms a closed loop with the open cooling tower.

7. The compressed air energy storage system according to claim 6, characterized in that, There is also a water inlet on the pipeline between the hot side outlet of the intermediate cooling heat exchanger and the cold side inlet of the gas storage tank inlet heat exchanger, and a pressure stabilizing device is installed on the water inlet.

8. The compressed air energy storage system according to claim 1, characterized in that, The cold source uses a closed cooling tower.

9. The compressed air energy storage system according to claim 8, characterized in that, The closed cooling tower has a water inlet on its liquid outlet pipe, and a pressure stabilizing device is installed at the water inlet.

10. A compressed air energy storage system, characterized in that, The system includes a compressor unit, which includes at least two stages of compressors; and a gas storage inlet heat exchanger is installed at the outlet of each of the last few stages of compressors. The hot side inlet of the gas storage tank heat exchanger at the outlet of the last stage compressor is connected to the outlet of the last stage compressor, the hot side outlet of the gas storage tank heat exchanger is connected to the gas storage tank inlet, and the cold side of the gas storage tank heat exchanger has a cold source. Except for the last stage compressor, the hot-side inlet of the gas storage inlet heat exchanger at the outlet of the last few stages of compressors is connected to the outlet of the compressor of the same stage, and the hot-side outlet of the gas storage inlet heat exchanger is connected to the inlet of the next stage compressor; all the gas storage inlet heat exchangers are connected to a cold source on the cold side.

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