Cold and heat electric energy storage system based on compressed air

Abstract

The utility model provides a cold and hot electric energy storage system based on compressed air, which comprises a motor generator, a compressor, an expansion machine, an energy storage loop and an energy release loop, the motor generator, the compressor and the expansion machine are sequentially connected, and the energy storage loop and the energy release loop are formed by the motor generator, the compressor and the expansion machine. An inlet of the medium-temperature heat exchanger is communicated with an exhaust port of the compressor, the energy release loop comprises a heat regenerator first inlet, a high-temperature heat exchanger, the expansion machine, a heat regenerator second inlet and the medium-temperature heat exchanger which are communicated in sequence, the second low-temperature heat exchanger provides a heat exchange medium for the cooler, and a heat exchange medium of the high-temperature heat exchanger is fused salt. And an electric heating device is arranged in the fused salt storage tank. The defects that in the prior art, compressed air storage limitation is large, and the flywheel energy storage capacity is relatively small can be overcome.

Description

Technical Field

[0001] The utility model relates to the technical field of compressed air energy storage, and in particular to a cold, hot and electric energy storage system based on compressed air. Background Art

[0002] Under the background of "dual carbon", "three highs" enterprises are facing the dual pressure of energy consumption policies and operating costs. They are in urgent need of a technology that can solve the current dilemma to improve and promote the high-quality development of enterprises. In the context of building a new power system, a high proportion of unstable new energy sources connected to the power system will cause frequent changes in the operating parameters of the power grid, causing hidden dangers to the operation safety of the power grid system, and further aggravating the difficulty of power grid dispatch. Therefore, power load management on the user side is an effective technical means to promote power grid dispatch and ensure the safe and stable operation of the power grid. Under the current power policy, the rational use of peak and valley flat electricity prices can effectively reduce the electricity costs of enterprises and thus reduce the operating pressure of enterprises.

[0003] On the user side, available energy storage technologies include electrochemical energy storage, compressed air energy storage, and flywheel energy storage. Electrochemical energy storage uses chemical batteries to store electrical energy, offering advantages such as fast response times, high efficiency, and high energy density. Compressed air energy storage, second only to pumped-storage hydroelectric power stations, is a large-scale, long-duration physical energy storage method characterized by safety, reliability, high efficiency, and a long lifespan. Flywheel energy storage relies on the rotational momentum of a flywheel and is typically smaller in scale.

[0004] When electrochemical energy storage systems store energy on the user side, due to the poor safety and stability of chemical batteries, improper management during use can easily lead to safety accidents, and the battery life is short, and the current application cost is also high. Compressed air energy storage technology currently has demonstration projects of hundreds of megawatts in the industry. Its design efficiency is relatively high, but its application requires the storage of high-pressure air, which requires the geological conditions for the construction of gas storage devices or the renovation of existing chambers. When applied on the user side, these conditions often limit the selection of appropriate gas storage devices. In addition, small-scale compressed air energy storage devices are relatively expensive, making them difficult to be widely used on the user side. Flywheel energy storage capacity is relatively small and is often used in grid frequency regulation. Due to its small energy storage capacity, it is not used for user-side power balance. Utility Model Content

[0005] Therefore, the present invention provides a cold, hot and electric energy storage system based on compressed air, which can overcome the defects of the prior art such as many restrictions on compressed air storage and relatively small flywheel energy storage capacity.

[0006] In order to solve the above problems, the utility model provides a cold and hot electric energy storage system based on compressed air, including an electric generator, a compressor, an expander connected in sequence, and an energy storage circuit and an energy release circuit formed by them, the energy storage circuit includes a medium-temperature heat exchanger, a cooler, the expander, a first low-temperature heat exchanger and a second low-temperature heat exchanger connected in sequence, the inlet of the medium-temperature heat exchanger is connected to the compressor exhaust port, the energy release circuit includes a first inlet of a regenerator, a high-temperature heat exchanger, the expander, a second inlet of the regenerator and a medium-temperature heat exchanger connected in sequence, the second low-temperature heat exchanger provides a heat exchange medium for the cooler, the heat exchange medium of the high-temperature heat exchanger is molten salt, and an electric heating device is provided in the molten salt storage tank.

[0007] In some embodiments, the heat exchange medium in the medium-temperature heat exchanger is water.

[0008] In some embodiments, when the system stores energy in the electricity valley section, after the air is compressed by the compressor, the compressed gas flows through the medium-temperature heat exchanger, the cooler, the expander, the first low-temperature heat exchanger and the second low-temperature heat exchanger in sequence, and the gas after heat exchange is finally discharged into the atmosphere. At the same time, the electric heating device is energized to heat the molten salt in the molten salt storage tank. At this time, the electric generator is an electric motor.

[0009] In some embodiments, when the system releases energy during the peak period of the power grid, after the air is compressed by the compressor, the compressed gas flows through the regenerator, the high-temperature heat exchanger, the expander in sequence, flows through the regenerator again, and finally flows through the medium-temperature heat exchanger. Finally, the gas is discharged into the atmosphere after heat exchange. At this time, the electric generator is a generator.

[0010] The utility model provides a cold, heat and electricity energy storage system based on compressed air. By connecting a compressor and an expander in series, the air is compressed by the compressor, expanded and then released into the atmosphere. During this period, energy is stored through multiple heat exchanges. This makes it possible to build a system without the need for a gas storage device, and to get rid of the geological conditions that limit the application of compressed air energy storage systems on the user side. At the same time, the equipment and equipment units used in this system all adopt mature and reliable technologies, which are easier to implement and the system operation is more stable. Compared with electrochemical energy storage, this system is safer and has a longer system life. Since this system can jointly generate cold, heat, electricity and other energy, the overall efficiency of the system is higher. The system input uses off-peak electricity, which can effectively reduce the company's electricity costs and operating costs. In particular, it can promote the absorption capacity of new energy power generation in enterprise parks, make the internal power load of the enterprise have a certain degree of flexibility, promote the dynamic balance of the internal power load of the enterprise, and provide guarantees for carbon emission reduction and high-quality development of the enterprise. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1This is a schematic diagram of the working process of the compressed air-based cold, hot and electric energy storage system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0012] See also Figure 1 As shown, according to an embodiment of the present invention, a compressed air-based cold and heat electric energy storage system is provided, comprising a sequentially connected electric generator, a compressor, and an expander, and an energy storage circuit and an energy release circuit formed thereby. The energy storage circuit comprises a sequentially connected medium-temperature heat exchanger, a cooler, the expander, a first low-temperature heat exchanger, and a second low-temperature heat exchanger. The inlet of the medium-temperature heat exchanger is connected to the compressor exhaust port. The energy release circuit comprises a sequentially connected first inlet of a regenerator, a high-temperature heat exchanger, the expander, a second inlet of the regenerator, and a medium-temperature heat exchanger. The second low-temperature heat exchanger provides heat exchange medium for the cooler. The heat exchange medium of the high-temperature heat exchanger is molten salt, and an electric heating device is installed in the molten salt storage tank. By arranging the compressor and expander in series, air is compressed by the compressor, then expanded, and released into the atmosphere, where energy is stored through multiple heat exchanges. This system eliminates the need for air storage devices, thus eliminating the geological limitations of compressed air energy storage systems for user-side applications. Furthermore, the equipment and equipment units used in this system utilize mature and reliable technologies, making it easier to implement and more stable. Compared to electrochemical energy storage, this system is safer and has a longer lifespan. Because it can jointly generate cooling, heat, and electricity, it offers higher overall efficiency. Its input uses off-peak electricity, effectively reducing a company's electricity and operating costs. In particular, it can boost the capacity of enterprise parks to absorb renewable energy generation, allowing for a certain degree of flexibility in internal power loads and promoting dynamic balance within the enterprise, thus safeguarding carbon emission reduction and high-quality development.

[0013] In a specific embodiment, the heat exchange medium in the medium-temperature heat exchanger is water.

[0014] In a specific embodiment, when the system stores energy in the electricity valley section, after the air is compressed by the compressor, the compressed gas flows through the medium-temperature heat exchanger, the cooler, the expander, the first low-temperature heat exchanger and the second low-temperature heat exchanger in sequence, and finally the gas after heat exchange is discharged into the atmosphere. At the same time, the electric heating device is energized to heat the molten salt in the molten salt storage tank. At this time, the electric generator is an electric motor.

[0015] In a specific embodiment, when the system releases energy during the peak period of the power grid, after the air is compressed by the compressor, the compressed gas flows through the regenerator, the high-temperature heat exchanger, the expander in sequence, flows through the regenerator again, and finally flows through the medium-temperature heat exchanger. Finally, the gas is discharged into the atmosphere after heat exchange. At this time, the electric generator is a generator.

[0016] Working principle:

[0017] During off-peak hours, ambient air is filtered and then compressed by the compressor, raising both the exhaust pressure and temperature. The high-temperature air then passes through an intermediate-temperature heat exchanger, where it exchanges heat with water from a low-temperature hot water storage tank. The heat in the high-pressure air is transferred to the hot water, which is then stored in the intermediate-temperature hot water tank for industrial use. The high-temperature, high-pressure air is cooled in the intermediate-temperature heat exchanger and then continues to cool in the cooler, converting it to high-pressure, ambient-temperature air. The high-pressure, ambient-temperature air then enters the expander, where it expands and generates work, producing ambient-pressure, low-temperature air. This air then enters the first low-temperature heat exchanger for heat exchange, where ambient-temperature water in the ambient-temperature storage tank exchanges heat with the air, storing the resulting cold in the low-temperature tank for industrial or domestic use. The ambient-pressure air then enters the second low-temperature heat exchanger for a second heat exchange. This cold air then provides cooling energy to the cooler, cooling the high-pressure, high-temperature air before entering the expander, creating a closed-loop cooling system that requires no additional energy. The expander's output power is then connected to a motor-generator via a connecting shaft to drive the air compressor. Simultaneously, an electric heating device is installed in the high-temperature molten salt storage tank, directly heating the molten salt with off-peak electricity or renewable energy for energy storage. This energy storage process allows the electrical energy to be stored as hot water and high-temperature molten salt, while simultaneously producing medium-temperature hot water and low-temperature chilled water.

[0018] During peak power periods, filtered ambient air enters the compressor. Compressed air increases in pressure and temperature. The high-temperature air then passes through a regenerator for heat exchange before entering a high-temperature heat exchanger, where it exchanges heat with molten salt from a high-temperature molten salt storage tank, further increasing its temperature. The molten salt enters a low-temperature molten salt storage tank. The heated, high-pressure, high-temperature air then flows directly into the expander, performing work while simultaneously driving the compressor and electric generator to generate electricity. The expanded, low-pressure air continues through the regenerator. Since the air temperature at the expander outlet is still higher than that at the compressor outlet, the heat can be fully utilized. The low-pressure, high-temperature air, after heat exchange in the regenerator, then enters a medium-temperature heat exchanger for further heat recovery before being discharged into the atmosphere through an exhaust tower. The medium-temperature hot water and low-temperature chilled water stored in the system can be used according to actual production and living needs. The entire process eliminates the need to store high-pressure compressed air, resulting in a simple structure and lower construction costs.

[0019] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. Such improvements and variations shall also be considered within the scope of protection of the present invention.

Claims

1. A cold and hot electric energy storage system based on compressed air, characterized in that: It includes an electric generator, a compressor, an expander connected in sequence, and an energy storage circuit and an energy release circuit formed by them. The energy storage circuit includes a medium-temperature heat exchanger, a cooler, the expander, a first low-temperature heat exchanger and a second low-temperature heat exchanger connected in sequence. The inlet of the medium-temperature heat exchanger is connected to the exhaust port of the compressor. The energy release circuit includes a first inlet of the regenerator, a high-temperature heat exchanger, the expander, a second inlet of the regenerator and a medium-temperature heat exchanger connected in sequence. The second low-temperature heat exchanger provides heat exchange medium for the cooler. The heat exchange medium of the high-temperature heat exchanger is molten salt, and an electric heating device is provided in the molten salt storage tank.

2. The compressed air-based cold and hot electric energy storage system according to claim 1, characterized in that: The heat exchange medium in the medium-temperature heat exchanger is water.

3. The compressed air-based cold and hot electric energy storage system according to claim 1, characterized in that: When the system stores energy in the electricity valley section, after the air is compressed by the compressor, the compressed gas flows through the medium-temperature heat exchanger, the cooler, the expander, the first low-temperature heat exchanger and the second low-temperature heat exchanger in sequence, and finally the gas after heat exchange is discharged into the atmosphere. At the same time, the electric heating device is energized to heat the molten salt in the molten salt storage tank. At this time, the electric generator is an electric motor.

4. The compressed air-based cold and hot electric energy storage system according to claim 1, characterized in that: When the system releases energy during the peak period of the power grid, after the air is compressed by the compressor, the compressed gas flows through the regenerator, the high-temperature heat exchanger, the expander in sequence, flows through the regenerator again, and finally flows through the medium-temperature heat exchanger. Finally, the gas is discharged into the atmosphere after heat exchange. At this time, the electric generator is a generator.

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