Compressed air energy storage system

Abstract

The utility model provides a compressed air energy storage system, and relates to the technical field of electric power energy storage, the compressed air energy storage system starts from a first-stage compression unit, and an air outlet of at least one-stage compression unit is respectively provided with a group of separated water heat exchangers and a group of air-water separators; an air outlet of the compression unit is communicated with a hot side inlet of the separated water heat exchanger, a hot side outlet of the compression unit is communicated with an inlet of the gas-water separator, and condensate water separated out from compressed air is separated out through the gas-water separator; inlets in the cold sides of the bleeding heat exchangers are communicated with an outlet of the cold storage tank, outlets in the cold sides of the bleeding heat exchangers are communicated with an inlet of the cold storage tank, and cooling equipment is arranged between the outlets in the cold sides and the inlet of the cold storage tank, so that the temperature of a medium entering the cold storage tank is reduced. According to the scheme, the technical problem that a large amount of condensate water can appear in the compression unit when the compressed air energy storage system in the prior art stores energy is solved, and the technical effect that the condensate water cannot be generated in the compression unit in the compression process is achieved.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of electric power energy storage, especially relates to a compressed air energy storage system. BACKGROUND

[0002] The compressed air energy storage technology is a kind of technology using compressed air to store energy, and it is considered by the industry as one of the technologies suitable for GW-level large-scale electric power energy storage, and its main use is electric power frequency modulation, voltage regulation, peak regulation, load balancing, static reserve and power grid black start etc.The working principle of compressed air energy storage technology is that during the off-peak period of electricity, air is compressed to high pressure using electric energy and stored in pressure vessel, i.e.the electric energy is converted into the internal energy of air and stored up.In the peak period of electricity, high-pressure air is released from the gas storage chamber and drives the expander to work to generate electricity.

[0003] In the process of realizing the utility model, the inventor finds that in the prior art, at least the following problems exist: during energy storage, a large amount of condensed water will appear in the compression unit, the condensed water will corrode the pipeline and pneumatic equipment, which will shorten the service life of the equipment, and there is also a safety hazard. UTILITY MODEL CONTENTS

[0004] The utility model aims at providing a compressed air energy storage system without condensed water in the compression unit during compression.

[0005] To achieve this purpose, a compressed air energy storage system is provided, which comprises at least one compression unit, a group of water separation heat exchangers and a group of gas-water separators are respectively arranged at the gas outlets of the at least one compression unit from the first compression unit; the water separation heat exchanger comprises one hot side and at least two cold sides; the gas outlet of the compression unit is in communication with the hot side inlet of the water separation heat exchanger, the hot side outlet of the water separation heat exchanger is in communication with the inlet of the gas-water separator, and the condensed water separated out by the gas-water separator from the compressed air; the inlets of the cold sides of the water separation heat exchanger are in communication with the outlet of the cold storage tank, and the outlets of the cold sides of the water separation heat exchanger are in communication with the inlet of the cold storage tank, and a cooling device is arranged between the outlet of the cold side of the water separation heat exchanger and the inlet of the cold storage tank to reduce the temperature of the medium entering the cold storage tank.

[0006] Further, a part of the cold side outlet of the water separation heat exchanger is in communication with the inlet of the cold storage tank, and the outlet of the other part of the cold side of the water separation heat exchanger is in communication with the inlet of the heat storage tank.

[0007] Further, the water separation heat exchanger comprises one hot side and two cold sides.

[0008] Further, the water separation heat exchanger uses a three-stream heat exchanger.

[0009] Further, the cooling device uses a cooling tower.

[0010] Further, an intermediate cooling heat exchanger is further included to separate the passage between the water separation heat exchanger and the cold storage tank from the cooling tower.

[0011] Further, the hot side inlet of the intermediate cooling heat exchanger is communicated with the cold side of the water separation heat exchanger, the hot side outlet of the intermediate cooling heat exchanger is communicated with the inlet of the cold storage tank, the cold side inlet of the intermediate cooling heat exchanger is communicated with the liquid outlet of the cooling tower, and the cold side outlet of the intermediate cooling heat exchanger is communicated with the liquid return port of the cooling tower.

[0012] Further, a buffer pool is arranged on the pipeline of the liquid outlet of the cooling tower to store cooling water.

[0013] Further, a cooling pump is arranged on the pipeline of the outlet end of the buffer pool.

[0014] Further, the outlet gas of the gas-water separator is communicated with the gas inlet of the next stage compression unit, and the gas outlet of the next stage compression unit is provided with a regenerative heat exchanger; the hot side inlet of the regenerative heat exchanger is communicated with the gas outlet of the compression unit, the hot side outlet of the regenerative heat exchanger is communicated with the gas inlet of the next stage compression unit or the inlet of the gas storage, the cold side inlet of the regenerative heat exchanger is communicated with the cold storage tank, and the cold side outlet of the regenerative heat exchanger is communicated with the inlet of the cold storage tank.

[0015] One of the above technical solutions has the following advantages or beneficial effects: starting from the first stage compression unit, a set of water separation heat exchangers and a set of gas-water separators are arranged at the gas outlet of at least one stage compression unit. The water separation heat exchanger includes a hot side and at least two cold sides. The gas outlet of the compression unit is communicated with the hot side inlet of the water separation heat exchanger, and the inlets of the cold sides of the water separation heat exchanger are all communicated with the outlet of the cold storage tank. The low-temperature medium in the cold storage tank is used to cool the compressed air of the hot side of the water separation heat exchanger, and a large amount of condensed water is separated out after the air is compressed and cooled by the compression unit. The hot side outlet of the water separation heat exchanger is communicated with the inlet of the gas-water separator, and the condensed water separated out by the compressed air is separated out by the gas-water separator, and the dry compressed air enters the next stage compression unit. The outlet of the cold side of the water separation heat exchanger is communicated with the inlet of the cold storage tank, and a cooling device is arranged between the outlet of the cold side of the water separation heat exchanger and the inlet of the cold storage tank to reduce the temperature of the medium entering the cold storage tank, so as to ensure that the medium in the cold storage tank always maintains a low temperature.

[0016] Therefore, the above-mentioned compressed air energy storage system separates the condensed water in the air in the first few stages of compression units by arranging the water separation heat exchanger and the gas-water separator, so as to ensure that the compressed air entering the compression unit in the medium and high pressure area is dry compressed air, and the condensed water does not appear in the compressor set during energy storage. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a compressed air energy storage system of an embodiment;

[0018] Figure 2 is another compressed air energy storage system of an embodiment;

[0019] Figure 3 is a connection diagram of a water separation heat exchanger and system in an embodiment.

[0020] In the figure: 11-first stage compression unit; 12-second stage compression unit; 21-water separation heat exchanger; 211-first cold side of the water separation heat exchanger; 212-second cold side of the water separation heat exchanger; 213-hot side of the water separation heat exchanger; 14-gas-water separator; 22-intermediate cooling heat exchanger; 30-cooling tower; 31-buffer pool; 32-cooling pump; 41-cold storage tank; 411-first outlet of the cold storage tank; 412-second outlet of the cold storage tank; 413-first inlet of the cold storage tank; 42-heat storage tank; 43-recuperation heat exchanger; 44-reheating heat exchanger; 51-expansion unit; 71-first pump; 72-second pump; 73-third pump; 74-fourth pump; 80-gas storage; 91-electric motor; 92-generator. DETAILED DESCRIPTION

[0021] In order to make the technical problems solved by the utility model, the technical scheme adopted and the technical effects reached more clear, the technical scheme of the embodiments of the utility model will be further described in detail below in combination with the drawings. Obviously, the described embodiments are only part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all the other embodiments obtained by the person skilled in the art without making creative labor belong to the protection scope of the utility model. It should be explained that the following embodiments and the features in the embodiments can be combined with each other in the case of no conflict.

[0022] The compressed air energy storage system comprises an energy storage subsystem and an energy release subsystem. The energy storage subsystem comprises at least one compression unit, all of which are connected in series, and the input shaft of the first compression unit is powered by an electric motor. The energy storage process is accompanied by a heat storage process, which is realized by a cold storage and heat storage subsystem comprising a cold storage tank and a heat storage tank. In the heat storage process, the low-temperature medium in the cold storage tank passes through the cold side of the regenerative heat exchanger, exchanges the heat in the hot side of the regenerative heat exchanger, and saves the heat in the heat storage tank. Since the energy storage medium of the compressed air energy storage system is air, the air has a relative humidity, and the air humidity is different in different regions. Even in the same region, the relative humidity of the air will be very different in different seasons and different climate conditions. For example, the air humidity in northern China is large in summer and small in winter. Therefore, when the relative humidity of the air is large, the compressed air energy storage system will have a large amount of condensed water when storing energy after the air is compressed by the compression unit and then cooled by the regenerative heat exchanger.

[0023] The compressed air energy storage system provided in the embodiment is provided with a set of water separation heat exchangers and a set of gas-water separators at the outlet of each compression unit from the first compression unit. The water separation heat exchanger 21 comprises a hot side and at least two cold sides, and the inlets of all the cold sides are in communication with the cold storage tank, i.e., the cold side of the water separation heat exchanger 21 is cooled by the cold storage tank. However, the outlet of one part of the cold side is in communication with the heat storage tank to save the compression heat in the heat storage tank, and the outlet of the other part of the cold side is cooled by an external cold source and then returned to the cold storage tank. The hot side of the water separation heat exchanger 21 is in communication with the compressed air. After the compressed air passes through the water separation heat exchanger 21, the cold energy of the cold side of the water separation heat exchanger 21 rapidly cools the compressed air, and the condensed water in the compressed air is quickly separated out. The condensed water is separated from the compressed air by the gas-water separator, and the relatively dry compressed air enters the next compression unit. If the water content of the compressed air at the outlet of the second compression unit is still high, a water separation heat exchanger 21 can be further provided at the outlet of the second compression unit. The number of water separation heat exchangers that need to be started in the compressed air energy storage system can be determined according to the air humidity and the compression parameters of the compression unit. Therefore, the compressed air energy storage system provided in the embodiment separates the condensed water in the air in the compression unit by providing the water separation heat exchanger and the gas-water separator, so as to ensure that the compressed air entering the high-pressure compression unit is dry compressed air, so that there is no condensed water in the compressor set during energy storage, and the air entering the air storage tank is also dry compressed air.

[0024] Figures 1-3 The embodiment shows that a set of water separation heat exchangers are provided from the first compression unit. If a second set of water separation heat exchangers are provided at the outlet of the second compression unit, the connection mode of the water separation heat exchangers is the same as that of the water separation heat exchangers at the outlet of the first compression unit. The water separation heat exchanger in the embodiment has two cold sides, and the connection mode of the water separation heat exchangers at the outlet of the second compression unit is the same as that of the water separation heat exchangers at the outlet of the first compression unit. Figures 1-3As shown, a three-flow heat exchanger can be used in the water separation heat exchanger to reduce gas lock resistance. Figure 3 A schematic diagram showing the connection between the water separation heat exchanger and the system is provided. Figure 3 As shown, the water-separating heat exchanger 21 includes one hot side and two cold sides. The hot-side inlet of the water-separating heat exchanger 21 is connected to the outlet of the first-stage compression unit, and a gas-liquid separator 14 is installed at the hot-side outlet of the water-separating heat exchanger 21. The outlet of the gas-liquid separator 14 is connected to the inlet of the second-stage compression unit, and the outlet of the gas-liquid separator 14 is connected to the system's drainage pipeline. The inlet of the first cold side 211 of the water-separating heat exchanger is connected to the first outlet 411 of the cold storage tank, and the outlet of the first cold side 211 of the water-separating heat exchanger is connected to the inlet of the heat storage tank 42. The compression heat is recovered to the heat storage tank through the first cold side 211 of the water-separating heat exchanger. The inlet of the second cold side 212 of the water separation heat exchanger is connected to the second outlet 412 of the cold storage tank. A cooling device is installed on the outlet pipe of the second cold side 212 of the water separation heat exchanger to cool the high-temperature medium in the outlet pipe of the second cold side 212. The cooled medium enters the first inlet 413 of the cold storage tank through the outlet pipe of the second cold side 212 for the next cycle of the system.

[0025] like Figure 1 A cooling device, such as a cooling tower 30, can be installed on the outlet pipe of the second cold side 212 of the water-exchange heat exchanger. A cooling tower is a device that cools water by utilizing the contact (direct or indirect) between air and water. When the medium in the cold storage tank is the same as the medium in the cooling tower, the cooling tower can be directly connected to the outlet pipe of the second cold side 212 of the water-exchange heat exchanger. Further, as... Figures 2-3 The system also includes an intermediate cooling heat exchanger 22. One side of the intermediate cooling heat exchanger 22 is connected to the passage between the outlet of the second cold side 212 of the water separation heat exchanger and the cold storage tank, while the other side of the intermediate cooling heat exchanger 22 is connected to the cooling tower circuit. The intermediate cooling heat exchanger 22 separates the passage between the second cold side 212 of the water separation heat exchanger and the cold storage tank from the cooling tower passage. The intermediate cooling heat exchanger 22 is used when the media in the cold storage tank and the media in the cooling tower are different, including cases where the media are of the same type but have different impurity levels. Typically, the impurity content of the media in the cold storage tank is low, while the impurity content of the media in the cooling tower is high.

[0026] like Figure 2The hot side inlet of the intermediate cooling heat exchanger 22 is communicated with the second cold side of the water separation heat exchanger, and the hot side outlet of the intermediate cooling heat exchanger 22 is communicated with the first inlet 413 of the cold storage tank. The cold side inlet of the intermediate cooling heat exchanger 22 is communicated with the liquid outlet of the cooling tower 30, and the cold side outlet of the intermediate cooling heat exchanger 22 is communicated with the liquid return port of the cooling tower. A buffer pool 31 is arranged on the pipeline of the liquid outlet of the cooling tower, for storing cooling water. A cooling pump 32 is arranged on the pipeline of the outlet end of the buffer pool, for pumping the cooling water into the cold side inlet of the intermediate cooling heat exchanger 22.

[0027] As shown in FIG. 1, the system comprises a compressor unit, a cold storage tank 41, a heat storage tank 42, a water separation heat exchanger, a reheat heat exchanger 44, and a cooling tower 30. Figures 1-2 The outlet side of the first N-stage compression unit in the compressor unit of the system is provided with the water separation heat exchanger, and the outlet of the N+1-stage compression unit is provided with the reheat heat exchanger 43. The hot side inlet of the reheat heat exchanger 43 is communicated with the gas outlet of the compression unit, the hot side outlet of the reheat heat exchanger is communicated with the gas inlet of the next stage compression unit, or with the inlet of the gas storage. The cold side inlet of the reheat heat exchanger 43 is communicated with the first outlet 411 of the cold storage tank, and the cold side outlet of the reheat heat exchanger 43 is communicated with the inlet of the heat storage tank 42. Correspondingly, a pump for driving the circulation of the pipeline between the first outlet 411 of the cold storage tank and the cold side inlet of each reheat heat exchanger 43 is arranged on the pipeline, such as the third pump 73 shown in FIG. 1. The reheat heat exchanger is only used to recover the compression heat in the compressed air. Figure 1 The reheat heat exchanger is only used to recover the compression heat in the compressed air.

[0028] As shown in FIG. 1, the system comprises a compressor unit, a cold storage tank 41, a heat storage tank 42, a water separation heat exchanger, a reheat heat exchanger 44, and a cooling tower 30. Figures 1-2 The energy release subsystem comprises at least one expansion unit 51, and the at least one expansion unit 51 is connected in series. Figure 1 Taking the case that the energy release subsystem comprises two-stage expansion units as an example, the energy release process is described. When electricity is needed, the gas outlet valve of the gas storage is opened, the compressed air in the gas storage first enters the cold side of the reheat heat exchanger 44, the hot side of the reheat heat exchanger 44 is communicated with the heat storage tank, and in the reheat heat exchanger 44, the heat of the heat storage tank is used to heat the compressed air. The cold side outlet of the reheat heat exchanger 44 is communicated with the inlet of the expansion unit, the compressed air with increased temperature enters the gas inlet of the expansion unit 51, and after expansion, the driving shaft of the expansion unit is connected with the generator to drive the generator to generate electricity. The hot side outlet of the reheat heat exchanger 44 is communicated with the second inlet of the cold storage tank, and the cold energy in the compressed air is stored in the cold storage tank. Correspondingly, the fourth pump 74 is arranged on the pipeline of the outlet of the heat storage tank 42, the hot side of the reheat heat exchanger 44, and the second inlet of the cold storage tank 41, and the fourth pump 74 is used to provide power for the above-mentioned pipeline.

[0029] The compressed air energy storage system of the embodiment is provided with the water separation heat exchanger 21 and the gas-water separator 14 at the air outlet of the compression unit of the previous stage or stages, the high-temperature compressed air at the air outlet of the compression unit is rapidly cooled down under the action of two cold sides of the water separation heat exchanger, the water in the compressed air is condensed in the form of liquid water, the condensed water is separated out through the gas-water separator 14, and the dry compressed air enters the air inlet of the compression unit of the next stage. The air flowing out of the air outlet of the water separation heat exchanger 21 and the gas-water separator 14 of the last stage is compressed air with extremely low relative humidity, and no condensed water is generated when the air is introduced into the subsequent compression unit, thereby avoiding corrosion of the equipment and prolonging the service life of the system. In addition, the cooling equipment is arranged between the outlet of one of the cold sides of the water separation heat exchanger and the cold storage tank, so that the temperature of the medium entering the cold storage tank is low enough. Furthermore, the intermediate cooling heat exchanger 22 separates the passage between the water separation heat exchanger and the cold storage tank and the passage of the cooling tower, thereby avoiding the influence of the cooling equipment on the stable operation of the compressed air energy storage system.

[0030] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrated; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication between two elements or the interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0031] In the present application, unless otherwise explicitly specified and limited, the first feature "on" or "below" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0032] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not a limitation on the embodiments of the present application. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to enumerate all the embodiments. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A compressed air energy storage system, characterized in that, The at least one compression unit is provided with a set of water separation heat exchangers and a set of water separation separators at the outlet of the at least one compression unit; The water separation heat exchanger comprises a hot side and at least two cold sides; The outlet of the compression unit is connected to the inlet of the hot side of the water separation heat exchanger, the outlet of the hot side of the water separation heat exchanger is connected to the inlet of the water separation separator, and the condensed water separated from the compressed air is separated by the water separation separator; The inlets of the cold sides of the water separation heat exchanger are connected to the outlets of the cold storage tanks, and the outlets of the cold sides of the water separation heat exchanger are connected to the inlets of the cold storage tanks, and a cooling device is arranged between the outlet of the cold side of the water separation heat exchanger and the inlet of the cold storage tank to reduce the temperature of the medium entering the cold storage tank.

2. The compressed air energy storage system of claim 1, wherein, Part of the outlet of the cold side of the water separation heat exchanger is connected to the inlet of the cold storage tank, and the other part of the outlet of the cold side of the water separation heat exchanger is connected to the inlet of the heat storage tank.

3. The compressed air energy storage system of claim 1, wherein, The water separation heat exchanger comprises a hot side and two cold sides.

4. The compressed air energy storage system of claim 1, wherein, The water separation heat exchanger uses a three-stream heat exchanger.

5. The compressed air energy storage system of claim 1, wherein, The cooling device uses a cooling tower.

6. The compressed air energy storage system of claim 5, wherein, An intermediate cooling heat exchanger is further arranged to separate the passage between the water separation heat exchanger and the cold storage tank from the cooling tower.

7. The compressed air energy storage system of claim 6, wherein, The hot side inlet of the intermediate cooling heat exchanger is connected to the cold side of the water separation heat exchanger, the hot side outlet of the intermediate cooling heat exchanger is connected to the inlet of the cold storage tank, the cold side inlet of the intermediate cooling heat exchanger is connected to the liquid outlet of the cooling tower, and the cold side outlet of the intermediate cooling heat exchanger is connected to the liquid return port of the cooling tower.

8. The compressed air energy storage system of claim 6, wherein, A buffer tank is arranged on the pipeline of the liquid outlet of the cooling tower to store cooling water.

9. The compressed air energy storage system of claim 8, wherein, A cooling pump is arranged on the pipeline of the outlet end of the buffer tank.

10. The compressed air energy storage system of claim 1, wherein, The outlet of the water separation separator is connected to the inlet of the next stage compression unit, and the outlet of the next stage compression unit is provided with a regenerative heat exchanger; The hot side inlet of the regenerative heat exchanger is connected to the outlet of the compression unit, the hot side outlet of the regenerative heat exchanger is connected to the inlet of the next stage compression unit, or is connected to the inlet of the gas storage; The cold side inlet of the regenerative heat exchanger is connected to the cold storage tank, and the cold side outlet of the regenerative heat exchanger is connected to the inlet of the heat storage tank.

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