A new energy multi-energy coupling complementary energy storage system

Abstract

The present invention relates to a new energy multi-energy coupling and complementary energy storage system, which mainly includes a photovoltaic power generation system, a wind power generation system, a solar thermal collector system, a compressed air energy storage system, and a molten salt heat storage system; the compressed air energy storage system includes a three-stage air compressor, an air storage tank, and a two-stage turbine expander; the molten salt heat storage system includes a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchange system, an evaporation system, and a steam turbine generator. The beneficial effects of the present invention are as follows: By adopting segmented temperature control, the overall heat exchange efficiency of the system can be improved; by combining compressed air energy storage with molten salt heat storage, the integrated regulation ability of the source-network-load-storage integration can be significantly improved.

Description

Technical Field

[0001] The present invention relates to the integrated technology of wind, light and energy storage, and particularly to a new energy multi-energy coupling and complementary energy storage system. Background Art

[0002] With the continuous growth of global energy production and consumption, fossil energy is becoming increasingly depleted, and the energy crisis has become a common problem faced worldwide. Therefore, in recent years, new energy technologies have rapidly emerged, especially renewable energy sources such as solar energy and wind energy. However, due to the volatility and discontinuity of new energy power generation such as wind power and light energy, its large-scale grid connection will bring many challenges to the safe and stable operation of the power grid, and energy storage technology has thus emerged.

[0003] Energy storage technology can effectively realize demand-side management, play a role in peak shaving and valley filling, improve the daily load rate of the power system, and improve the overall operation efficiency of the power grid. According to different energy storage methods, energy storage methods are divided into mechanical, electrical, electrochemical, thermal, and chemical methods. At present, pumped-storage energy storage, compressed air energy storage, molten salt energy storage, etc. are more widely used in various types of energy storage methods.

[0004] Among them, compressed air energy storage refers to a method of storing energy by compressing air with electric energy during the low-load period of the power grid and sealing the high-pressure air in a gas storage container, and releasing the compressed air to drive a steam turbine generator to generate electricity during the high-load period of the power grid. In a traditional compressed air energy storage system, the compression heat during the compression process is discarded, resulting in most of the energy loss, and the system cycle efficiency is relatively low. At the same time, natural gas and other fuels are also required for supplementary combustion heating of compressed air during the energy release expansion process.

[0005] Molten salt energy storage technology refers to the use of the temperature difference of molten salt during heating or cooling to achieve heat energy storage, and the heat storage material always remains in a liquid state within the entire working temperature range.

[0006] In order to solve the problem of low cycle efficiency of traditional compressed air energy storage systems, a compressed air energy storage system with heat storage has emerged, enabling it to no longer require burning fossil fuels when generating electricity from compressed air. The theoretical efficiency of the compressed air energy storage system has been increased to about 70%. The main reason for the inability to further improve the efficiency is that the heat collection and heat exchange processes of the compression heat are relatively rough and not refined for different temperatures; at the same time, existing energy storage systems also have problems such as high cost, low equipment utilization rate, and poor flexibility. Summary of the Invention

[0007] In order to solve the above technical problems and provide a system that can be coupled with a variety of new energy sources and has flexible and high-efficiency energy storage methods, the present invention provides the following technical solutions:

[0008] A new energy multi-energy coupling and complementary energy storage system mainly includes a photovoltaic power generation system, a wind power generation system, a solar thermal collection system, a compressed air energy storage system, and a molten salt energy storage system; the compressed air energy storage system includes a three-stage air compressor, a gas storage tank, and a two-stage turbine expander; the molten salt energy storage system includes a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchange system, an evaporation system, and a steam turbine generator.

[0009] The compression ratio of each stage of the air compressor is different, and the generated compression heat is also different. Therefore, a medium-temperature molten salt tank is added on the basis of the traditional double-tank molten salt energy storage system to perform segmented temperature control on each stage of the air compressor and the turbine expander. At the same time, the molten salt energy storage system is used to supply heat to each device of the evaporation system in stages, thereby improving the overall heat exchange efficiency.

[0010] Part of the electricity generated by the photovoltaic power generation system, the wind power generation system, and the steam turbine generator is connected to the power grid through a power conditioning device, and part is used to supply power to the three-stage air compressor.

[0011] The three-stage air compressor includes Air Compressor One, Air Compressor Two, and Air Compressor Three.

[0012] The two-stage turbine expander includes Turbine Expander One and Turbine Expander Two.

[0013] The molten salt heat exchange system includes Heat Exchanger One, Heat Exchanger Two, Heat Exchanger Three, and Heat Exchanger Four, all of which include an air inlet, an air outlet, a molten salt inlet, and a molten salt outlet.

[0014] The evaporation system includes a preheater, an evaporator, and a superheater connected in sequence; the superheater is connected to the steam turbine generator.

[0015] The low-temperature molten salt tank, Heat Exchanger One, medium-temperature molten salt tank, and evaporator are connected in sequence and end to end to form a first molten salt cycle.

[0016] The medium-temperature molten salt tank, Heat Exchanger Two, high-temperature molten salt tank, and superheater are connected in sequence and end to end to form a second molten salt cycle.

[0017] The air inlet of Heat Exchanger One is connected to the outlet of Air Compressor One, and the air outlet is connected to the air inlet of Air Compressor Two; the molten salt inlet is connected to the low-temperature molten salt tank, and the molten salt outlet is connected to the medium-temperature molten salt tank.

[0018] The air outlet of Heat Exchanger Two is connected to the air inlet of Air Compressor Three; the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the high-temperature molten salt tank.

[0019] The air outlet of Air Compressor Three is connected to the inlet of the gas storage tank; the outlet of the gas storage tank is connected to the air inlet of Heat Exchanger Three.

[0020] The air outlet of the third heat exchanger is connected to the inlet of the first turbine expander, the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank;

[0021] The air inlet of the fourth heat exchanger is connected to the outlet of the first turbine expander, the air outlet is connected to the inlet of the second turbine expander, the molten salt inlet is connected to the high-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank;

[0022] Furthermore, molten salt pumps are provided at the outlets of the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank for forced convection of the molten salt in the molten salt tanks.

[0023] Furthermore, electric heaters are provided inside the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank, and the electric heaters are powered by one of the abandoned electricity of the photovoltaic power generation system, the wind power generation system, or the valley electricity.

[0024] The beneficial effects of the present invention are as follows:

[0025] (1) By adopting segmented temperature control, the overall heat exchange efficiency of the system can be improved;

[0026] (2) By combining compressed air energy storage and molten salt heat storage, the integrated regulation ability of the source-network-load-storage integration can be significantly improved.

[0027] (3) By sharing the molten salt heat storage system with multiple new energy sources, the heat storage cost can be evenly distributed and the investment cost can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The system schematic diagram of the present invention.

[0029] In the figure: 1. The first heat exchanger; 2. The second heat exchanger; 3. The third heat exchanger; 4. The fourth heat exchanger. DETAILED DESCRIPTION OF THE INVENTION

[0030] The following combines the drawings and embodiments to further describe in detail the specific implementation manners of the present invention. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0031] Embodiment 1

[0032] As Figure 1 shown, a new energy multi-energy coupling and complementary joint energy storage system mainly includes a photovoltaic power generation system, a wind power generation system, a solar thermal collection system, a compressed air energy storage system, and a molten salt heat storage system; the compressed air energy storage system includes the first air compressor, the second air compressor, the third air compressor, the gas storage tank, the first turbine expander, and the second turbine expander; the molten salt heat storage system includes a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchange system, an evaporation system, and a steam turbine generator;

[0033] Part of the electricity generated by the photovoltaic power generation system, wind power generation system, and steam turbine generator is connected to the power grid through a power conditioning device, and part is used to supply power to the three-stage air compressor;

[0034] The molten salt heat exchange system includes heat exchanger 1, heat exchanger 2, heat exchanger 3, and heat exchanger 4, all of which include an air inlet, an air outlet, a molten salt inlet, and a molten salt outlet;

[0035] The evaporation system includes a preheater, an evaporator, and a superheater connected in sequence; the superheater is connected to the steam turbine generator;

[0036] The low-temperature molten salt tank, heat exchanger 1, medium-temperature molten salt tank, and evaporator are connected in sequence and end to end to form a first molten salt cycle; the medium-temperature molten salt tank, heat exchanger 2, high-temperature molten salt tank, and superheater are connected in sequence and end to end to form a second molten salt cycle;

[0037] The air inlet of heat exchanger 1 is connected to the outlet of air compressor 1, and the air outlet is connected to the air inlet of air compressor 2; the molten salt inlet is connected to the low-temperature molten salt tank, and the molten salt outlet is connected to the medium-temperature molten salt tank;

[0038] The air outlet of heat exchanger 2 is connected to the air inlet of air compressor 3; the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the high-temperature molten salt tank;

[0039] The air outlet of air compressor 3 is connected to the inlet of the gas storage tank; the outlet of the gas storage tank is connected to the air inlet of heat exchanger 3;

[0040] The air outlet of heat exchanger 3 is connected to the inlet of turboexpander 1, the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank;

[0041] The air inlet of heat exchanger 4 is connected to the outlet of turboexpander 1, the air outlet is connected to the inlet of turboexpander 2, the molten salt inlet is connected to the high-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank;

[0042] Molten salt pumps are provided at the outlets of the high-temperature molten salt tank, medium-temperature molten salt tank, and low-temperature molten salt tank, and electric heaters are provided inside. The electric heaters are powered by one of the abandoned electricity of the photovoltaic power generation system and wind power generation system, or off-peak electricity.

[0043] Both the compressed air energy storage system and the molten salt heat storage system of the present invention have two modes of energy storage and energy release, mainly:

[0044] (1) Compressed air energy storage system energy storage mode: Use abandoned wind and photovoltaic power to supply power to the air compressor, compress the air and store it in the gas storage tank; the compression heat generated during the energy storage process is exchanged with the molten salt step by step, and the compression heat is stored in the medium- and high-temperature molten salts; Compressed air energy storage can also be powered by off-peak electricity according to actual needs.

[0045] (2) Energy release mode of the compressed air energy storage system: During the peak period of power grid load, the compressed air in the gas storage tank is used to generate electricity through a turbine expander; during the energy release process, medium- and high-temperature molten salts are used to gradually heat the compressed air.

[0046] (3) Energy storage mode of the molten salt thermal energy storage system: The surplus heat energy of the solar thermal collector system and the compression heat are used to heat the low-temperature molten salt, and the heat is stored in the medium- and high-temperature molten salts.

[0047] (4) Energy release mode of the molten salt thermal energy storage system: During the peak period of power grid load, on the one hand, the thermal energy of the molten salt is used to heat the compressed air in the gas storage tank, and on the other hand, it is used for heating the evaporation system to generate high-temperature steam for power generation by a steam turbine generator.

[0048] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A new energy multi - energy coupling and complementary joint energy storage system, characterized in that: It mainly includes a photovoltaic power generation system, a wind power generation system, a solar thermal collector system, a compressed air energy storage system, and a molten salt energy storage system; the compressed air energy storage system includes a three-stage air compressor, an air storage tank, and a two-stage turbine expander; the molten salt energy storage system includes a high-temperature molten salt tank, a medium-temperature molten salt tank, a low-temperature molten salt tank, a molten salt heat exchange system, an evaporation system, and a steam turbine generator; Part of the electricity generated by the photovoltaic power generation system, the wind power generation system, and the steam turbine generator is connected to the power grid through a power conditioning device, and part is used to supply power to the three-stage air compressor; The three-stage air compressor includes an air compressor one, an air compressor two, and an air compressor three; The two-stage turbine expander includes a turbine expander one and a turbine expander two; The molten salt heat exchange system includes a heat exchanger one, a heat exchanger two, a heat exchanger three, and a heat exchanger four, all of which include an air inlet, an air outlet, a molten salt inlet, and a molten salt outlet; The evaporation system includes a preheater, an evaporator, and a superheater connected in sequence; the superheater is connected to the steam turbine generator; The low-temperature molten salt tank, the heat exchanger one, the medium-temperature molten salt tank, and the evaporator are connected in sequence and end to end to form a first molten salt cycle; The medium-temperature molten salt tank, the heat exchanger two, the high-temperature molten salt tank, and the superheater are connected in sequence and end to end to form a second molten salt cycle; The air inlet of the heat exchanger one is connected to the outlet of the air compressor one, and the air outlet is connected to the air inlet of the air compressor two; the molten salt inlet is connected to the low-temperature molten salt tank, and the molten salt outlet is connected to the medium-temperature molten salt tank; The air outlet of the heat exchanger two is connected to the air inlet of the air compressor three; the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the high-temperature molten salt tank; The air outlet of the air compressor three is connected to the inlet of the air storage tank; the outlet of the air storage tank is connected to the air inlet of the heat exchanger three; The air outlet of the heat exchanger three is connected to the inlet of the turbine expander one, the molten salt inlet is connected to the medium-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank; The air inlet of the heat exchanger four is connected to the outlet of the turbine expander one, the air outlet is connected to the inlet of the turbine expander two, the molten salt inlet is connected to the high-temperature molten salt tank, and the molten salt outlet is connected to the low-temperature molten salt tank.

2. The new energy multi-energy coupling complementary joint energy storage system according to claim 1, characterized in that: Molten salt pumps are provided at the outlets of the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank.

3. A new energy multi-energy coupling complementary energy storage system according to claim 1, characterized in that: Electric heaters are provided inside the high-temperature molten salt tank, the medium-temperature molten salt tank, and the low-temperature molten salt tank, and the electric heaters are powered by one of the abandoned electricity or low-valley electricity of the photovoltaic power generation system and the wind power generation system.

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