System and method for coupling air compression energy storage to flexible peak shaving of coal power base

Abstract

The application discloses a system and method for air compression energy storage coupled flexible peak regulation of coal power base, and belongs to the technical field of thermal power generation. The system comprises a motor, a multistage compressor, a high-low temperature molten salt storage tank, a mine injection-production well group, a compressed air heat exchanger, a multistage turbine and a generator, and a supporting thermal power unit. The redundant new energy and the redundant power of the unit load reduction preferentially drive the compressor to compress air, and the balance is used to heat the low-temperature molten salt. The low-temperature molten salt is used for cooling between compressor stages. The air storage is constructed by relying on the abandoned mine of the coal power, and the compressed air is stored by injection wells. In the energy release stage, the air storage is drawn out from the extraction well, is heated and warmed by the heat exchanger first, the heat source preferentially uses the high-temperature molten salt, the molten salt heat is insufficient, the thermal power unit is extracted to divert the high-temperature flue gas of the smoke chamber for heat supplement, the flue gas after heat exchange and temperature reduction flows back to the end of the flue gas; the warmed compressed air drives the turbine to drive the generator to be connected to the grid to generate electricity, so that the coal power deep peak regulation and the new energy consumption are coordinated.

Description

Technical Field

[0001] This invention belongs to the field of thermal power generation technology, specifically relating to a system and method for flexible peak shaving of coal-fired power bases coupled with air compression energy storage. Background Technology

[0002] Currently, the installed capacity of new energy sources such as wind power and photovoltaics has officially surpassed that of coal power. However, the intermittency and volatility of renewable energy have led to a surge in grid peak-shaving pressure. Traditional coal-fired power units need to transform from primary power sources to regulating power sources, facing problems such as frequent start-ups and shutdowns, decreased efficiency, shortened lifespan, and increased pollutant emissions due to low-load operation. Against this backdrop, deep integration of compressed air energy storage (CAES) with coal-fired power bases has become a key path to overcome the bottleneck of flexible transformation of coal-fired power plants.

[0003] Compressed air energy storage technology, with its advantages of large storage capacity, fast response speed, and long life (30-50 years), can optimize the power grid supply and demand balance through peak shaving and valley filling. Its core principle is to utilize surplus electricity during off-peak hours to compress air and store it in underground spaces such as salt caverns, while simultaneously recovering the heat of compression; during peak hours, the high-pressure air is released to drive turbines to generate electricity, achieving a "spatiotemporal transfer" of electrical energy. Coal-fired power plants, due to coal mining, often have abandoned coal mines that not only damage the environment but also cannot be effectively utilized. However, these abandoned coal mines can be modified to serve as compressed air storage tanks for compressed air energy storage systems, significantly reducing construction costs. Summary of the Invention

[0004] This invention provides a system and method for flexible peak shaving of coal-fired power bases coupled with compressed air energy storage, aiming to overcome the problems faced by traditional coal-fired power units, such as frequent start-stop, low-load operation leading to decreased efficiency, shortened lifespan, and increased pollutant emissions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: The system for flexible peak shaving of coal-fired power bases is composed of air compression energy storage, including electric motors, multi-stage compressors, low-temperature molten salt storage tanks, high-temperature molten salt storage tanks, air compression storage injection wells, air compression storage extraction wells, compressed air heat exchangers, multi-stage turbo expanders, generators, and thermal power units. The outlet of the electric motor is connected to the inlet of the multi-stage compressor, and the outlet of the multi-stage compressor is connected to the air compression chamber injection well. The cryogenic molten salt storage tank is interconnected with the multi-stage compressor, using the flow of molten salt to cool the interstage coolers within the multi-stage compressor. The outlet of the air compression chamber extraction well is connected to the compressed air heat exchanger, allowing compressed air to enter the heat exchanger. The cryogenic molten salt storage tank is connected to the high-temperature molten salt storage tank. The high-temperature molten salt storage tank is connected to the compressed air heat exchanger, and then to the cryogenic molten salt storage tank. The thermal power unit is connected to the compressed air heat exchanger, using high-temperature flue gas to preheat the compressed air in the heat exchanger. After preheating in the heat exchanger, the compressed air is fed into the multi-stage turboexpander to perform work, driving the generator to generate electricity, and finally venting the compressed air that has performed work.

[0006] A further improvement of this invention is that the redundant power generation of new energy power generation and thermal power units when the load is reduced is used to feed into the low-temperature molten salt storage tank for heating the low-temperature molten salt.

[0007] A further improvement of the present invention is that the generator produces electricity for connection to the power grid.

[0008] A further improvement of the present invention is that the multi-stage compressor is used to compress air and inject it underground through the air compression chamber injection well, while the low-temperature molten salt is interconnected with the multi-stage compressor and the flow of molten salt is used to cool the interstage cooler in the multi-stage compressor.

[0009] A further improvement of the present invention is that the high-temperature and high-pressure air from the compressed air heat exchanger enters the multi-stage turboexpander to do work, and then generates electricity through a generator and connects to the power grid.

[0010] A further improvement of the present invention is that the temperature range of the molten salt in the low-temperature molten salt storage tank is 250℃~400℃.

[0011] A further improvement of the present invention is that the temperature of the molten salt in the high-temperature molten salt storage tank is in the range of 300℃ to 600℃.

[0012] A method for flexible peak shaving of coal-fired power plants coupled with compressed air energy storage, the method being based on the aforementioned system for flexible peak shaving of coal-fired power plants coupled with compressed air energy storage, comprising: The redundant power generation of new energy power generation and thermal power unit when the load is reduced is fed into the motor and the low temperature molten salt storage tank, respectively. The motor drives the multi-stage compressor to do work, and the low temperature molten salt in the low temperature molten salt storage tank is used to exchange heat and cool down its interstage cooler. Redundant power generation is first fed into the electric motor, and then fed into the cryogenic molten salt storage tank for cryogenic molten salt heating; The abandoned mine shafts of the coal-fired power plant base were used as air compressor storage facilities, and air compressor storage injection wells and air compressor storage extraction wells were set up. Cooled compressed air is introduced into the air compressor storage through the air compressor storage injection well. When work is required, it is extracted through the air compressor storage extraction well and introduced into the compressed air heat exchanger for heating. The heat stored in the high-temperature molten salt storage tank is used to heat the compressed air in the compressed air heat exchanger. If the heat is insufficient, it is heated by the high-temperature flue gas in the thermal power unit. High-temperature flue gas in thermal power units is drawn from the horizontal flue section and turned into the flue chamber. The flue gas temperature is reduced after being heated by compressed air and then introduced into the end of the horizontal flue section. The preheated compressed air in the compressed air heat exchanger is fed into a multi-stage turbo expander to do work, which in turn drives a generator to generate electricity, and finally the compressed air is discharged.

[0013] A further improvement of the present invention is that the temperature range of the molten salt in the low-temperature molten salt storage tank is 250℃~400℃.

[0014] A further improvement of the present invention is that the temperature of the molten salt in the high-temperature molten salt storage tank is in the range of 300℃ to 600℃.

[0015] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention provides a system and method for flexible peak shaving in coal-fired power plants using compressed air and molten salt composite energy storage. Surplus electricity from new energy sources and redundant electricity generated during load reduction are stored in the energy storage. During peak electricity demand, the stored energy releases power to replace the increased output of the generating units, achieving deep load reduction and peak shaving for thermal power units. This addresses the pain points of traditional coal-fired units, such as limited load increase / decrease rates, high energy consumption for deep peak shaving, and poor economic efficiency. It smooths fluctuations in unit output power and meets the grid's peak shaving needs under large-scale grid connection of new energy sources. The compressed air preheating adopts a tiered heating logic that prioritizes molten salt heat storage and supplements with high-temperature flue gas from the generating units. Only when the molten salt heat is insufficient is high-temperature flue gas from the horizontal flue of the thermal power unit used for diversion. The cooled flue gas is then returned to the end of the flue, allowing for tiered reuse of flue gas heat. This avoids excessive extraction of high-temperature flue gas, which could interfere with the boiler's thermal operation, and minimizes the negative impact of the supplementary heating process on the power generation efficiency of the thermal power unit.

[0016] This invention abandons the traditional model of excavating gas storage caves and constructing pressure vessels for compressed air energy storage. Instead, it reuses abandoned mines in coal-fired power bases as underground air compressors, and completes the gas storage structure by constructing injection wells and extraction wells.

[0017] In the compression stage, low-temperature molten salt is used to circulate heat exchange in the interstage cooler of the multi-stage compressor. The heat of compression is recovered by the low-temperature molten salt and stored in the high-temperature molten salt storage tank. In the expansion and energy release stage, the high-temperature molten salt releases heat to preheat the compressed air, forming a closed molten salt heat exchange cycle of compression waste heat recovery, heat storage and expansion heat release. Combined with the supplement of waste heat from thermal power plant flue gas, the two types of low-grade waste heat resources, namely compression waste heat and thermal power plant flue gas waste heat, are recovered and utilized, improving the closed-loop utilization rate of heat in the whole system and overcoming the inherent defects of single compressed air energy storage where compression heat is lost and single molten salt energy storage where the heat source is insufficient. Attached Figure Description

[0018] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the system of the present invention.

[0020] Explanation of reference numerals in the attached figures: 1-Electric motor, 2-Multi-stage compressor, 3-Low-temperature molten salt storage tank, 4-High-temperature molten salt storage tank, 5-Air compressor injection well, 6-Air compressor extraction well, 7-Compressed air heat exchanger, 8-Multi-stage turbine expander, 9-Generator, 10-Thermal power unit. Detailed Implementation

[0021] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit or scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0022] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0023] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0026] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0027] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0028] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes such combinations.

[0029] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0030] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1 like Figure 1 As shown, the air compression energy storage coupled coal-fired power base flexible peak shaving system provided by the present invention includes an electric motor 1, a multi-stage compressor 2, a low-temperature molten salt storage tank 3, a high-temperature molten salt storage tank 4, an air compression reservoir injection well 5, an air compression reservoir extraction well 6, a compressed air heat exchanger 7, a multi-stage turbine expander 8, a generator 9, and a thermal power unit 10.

[0032] The air compression energy storage coupled coal-fired power plant flexible peak-shaving system of the present invention has the following connection method: The outlet of electric motor 1 is connected to the inlet of multi-stage compressor 2, and the outlet of multi-stage compressor 2 is connected to air compressor injection well 5. The cryogenic molten salt storage tank 3 is interconnected with multi-stage compressor 2, using the flow of molten salt to cool the interstage cooler within multi-stage compressor 2. The outlet of air compressor extraction well 6 is connected to compressed air heat exchanger 7, allowing compressed air to enter the compressed air heat exchanger 7. The cryogenic molten salt storage tank 3 is connected to high-temperature molten salt storage tank 4; the high-temperature molten salt storage tank 4 is connected to compressed air heat exchanger 7, and then to cryogenic molten salt storage tank 3. Thermal power unit 10 is connected to compressed air heat exchanger 7, using high-temperature flue gas to preheat the compressed air in compressed air heat exchanger 7. After preheating in compressed air heat exchanger 7, the compressed air is fed into multi-stage turboexpander 8 to perform work, driving generator 9 to generate electricity, and finally, the compressed air that has performed work is discharged.

[0033] Example 2 like Figure 1As shown, the air compression energy storage coupled with flexible peak shaving system for coal-fired power plants provided by this invention includes an electric motor 1, a multi-stage compressor 2, a low-temperature molten salt storage tank 3, a high-temperature molten salt storage tank 4, an air compression reservoir injection well 5, an air compression reservoir extraction well 6, a compressed air heat exchanger 7, a multi-stage turboexpander 8, a generator 9, and a thermal power unit 10; the outlet of the electric motor 1 is connected to the inlet of the multi-stage compressor 2, and the outlet of the multi-stage compressor 2 is connected to the air compression reservoir injection well 5; wherein, the low-temperature molten salt storage tank 3 is interconnected with the multi-stage compressor 2, utilizing the flow of molten salt to provide interstage cooling within the multi-stage compressor 2. Cooler; the outlet of the air compressor extraction well 6 is connected to the compressed air heat exchanger 7, and compressed air is introduced into the compressed air heat exchanger 7; the low temperature molten salt storage tank 3 is connected to the high temperature molten salt storage tank 4; the high temperature molten salt storage tank 4 is connected to the compressed air heat exchanger 7, and then connected to the low temperature molten salt storage tank 3; the thermal power unit 10 is connected to the compressed air heat exchanger 7, and the high temperature flue gas is used to preheat the compressed air in the compressed air heat exchanger 7; after being preheated in the compressed air heat exchanger 7, the compressed air is introduced into the multi-stage turbine expander 8 to do work, drive the generator 9 to generate electricity, and finally complete the work of the compressed air being discharged.

[0034] In this embodiment, the redundant power generation of new energy power generation and thermal power unit when the load is reduced is used to feed into the low temperature molten salt storage tank 3 for low temperature molten salt heating.

[0035] In this embodiment, the power generated by generator 9 is used to connect to the power grid.

[0036] In this embodiment, the multi-stage compressor 2 is used to compress air and inject it underground through the air compression chamber injection well 5. The low-temperature molten salt is interconnected with the multi-stage compressor 2 and is used to cool the interstage cooler in the multi-stage compressor 2 by the flow of molten salt.

[0037] In this embodiment, the high-temperature and high-pressure air from the compressed air heat exchanger 7 enters the multi-stage turboexpander 8 to do work, and then generates electricity through the generator 9 and connects to the power grid.

[0038] In this embodiment, the temperature range of the molten salt in the low-temperature molten salt storage tank 3 is 250℃~400℃.

[0039] In this embodiment, the temperature range of the molten salt in the high-temperature molten salt storage tank 4 is 300℃~600℃.

[0040] Example 3 like Figure 1 As shown, the method for flexible peak shaving of coal-fired power plants coupled with air compression energy storage provided by the present invention has the following operation steps: 1) The redundant power generation of new energy power generation and thermal power unit when the load is reduced is fed into motor 1 and low temperature molten salt storage tank 3 respectively. Motor 1 drives multi-stage compressor 2 to do work and uses the low temperature molten salt in low temperature molten salt storage tank 3 to exchange heat and cool its interstage cooler. 2) Redundant power generation is first fed into motor 1, and then fed into low-temperature molten salt storage tank 3 for low-temperature molten salt heating; 3) Utilize abandoned mine shafts in the coal-fired power plant base as air compressor storage facilities, and set up air compressor storage injection well 5 and air compressor storage extraction well 6; 4) The cooled compressed air is introduced into the air compressor through the air compressor injection well 5. When work is required, it is extracted through the air compressor extraction well 6 and introduced into the compressed air heat exchanger 7 for heating. 5) The heat stored in the high-temperature molten salt storage tank 4 is used first to heat the compressed air in the compressed air heat exchanger 7. If the heat is insufficient, the high-temperature flue gas in the thermal power unit 10 is used to heat it. 6) The high-temperature flue gas in the thermal power unit 10 is drawn from the horizontal flue section to the flue chamber. The flue gas temperature is reduced after being heated by compressed air and then introduced into the end of the horizontal flue section. 7) The preheated compressed air in the compressed air heat exchanger 7 is fed into the multi-stage turbo expander 8 to do work, which in turn drives the generator 9 to generate electricity, and finally exhausts the air.

[0041] This invention effectively addresses the problems of low peak-shaving rate, large fluctuations, and poor economic efficiency of deep peak-shaving in traditional thermal power units through a composite coupling architecture of compressed air energy storage and molten salt energy storage. This invention prioritizes the use of redundant electricity to store compressed air, supplemented by molten salt thermal energy storage in a cascaded energy storage system, significantly improving system energy storage efficiency and reducing equipment construction costs. Simultaneously, it reuses abandoned mines in coal-fired power bases as gas storage facilities, realizing the resource utilization of waste resources, reducing civil engineering excavation costs, and improving the mining area environment. This invention eliminates the traditional compressed air energy storage combustion chamber, relying on molten salt thermal energy storage and cascaded preheating of compressed air using waste heat from thermal power flue gas, significantly reducing system carbon emissions and operating energy consumption, and minimizing the impact on the power generation efficiency of thermal power units. This invention can effectively smooth out fluctuations in thermal power output, improve the unit's load increase / decrease rate and peak-shaving flexibility, facilitate the local consumption of surplus renewable energy, and adapt to the flexible peak-shaving and low-carbon operation requirements of new power systems.

[0042] The key points of this invention are as follows: A system and method for flexible peak shaving in coal-fired power bases using compressed air energy storage, including electric motors, multi-stage compressors, cryogenic molten salt storage tanks, high-temperature molten salt storage tanks, air compressor injection wells, air compressor extraction wells, compressed air heat exchangers, multi-stage turboexpanders, generators, and thermal power units.

[0043] The key point of this invention is that, through an energy storage system composed of compressed air energy storage and molten salt energy storage, flexible peak shaving of thermal power units can be achieved, and the power of thermal power units during flexible peak shaving can be smoothed and the load increase and decrease rate of thermal power units can be improved.

[0044] The key point of this invention is that by using abandoned mines in coal-fired power plants as air compressor storage tanks for air compression energy storage systems, waste utilization and environmental management can be achieved in a way that is appropriate to local conditions.

[0045] The key point of this invention is that redundant electricity is first fed into the compressed air energy storage system for storage, and then fed into the molten salt energy storage system, which can improve the energy storage efficiency of the energy storage system and reduce construction costs.

[0046] The key point of this invention is that it prioritizes the use of the heat storage of the molten salt energy storage system to provide heat energy for the compressed air heat exchanger, and secondly uses high-temperature flue gas preheating, which can improve the thermal efficiency of the system and reduce the impact on the power generation efficiency of thermal power units.

[0047] The key point of this invention is that it reduces the gas combustion chamber of traditional compressed air energy storage, and uses a molten salt energy storage system and high-temperature flue gas to preheat the compressed air, thereby reducing the carbon emissions of the compressed air system and the industrial production cost.

[0048] The key point of this invention is that it makes full use of the energy storage system composed of compressed air energy storage and molten salt energy storage, thereby reducing the carbon emissions of the system's power generation and improving the efficiency of industrial production.

[0049] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the scope of the invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0050] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A system for flexible peak shaving in coal-fired power plants coupled with compressed air energy storage, characterized in that: This includes electric motors, multi-stage compressors, cryogenic molten salt storage tanks, high-temperature molten salt storage tanks, air compressor injection wells, air compressor extraction wells, compressed air heat exchangers, multi-stage turboexpanders, generators, and thermal power units; The outlet of the electric motor is connected to the inlet of the multi-stage compressor, and the outlet of the multi-stage compressor is connected to the air compression chamber injection well. The cryogenic molten salt storage tank is interconnected with the multi-stage compressor, using the flow of molten salt to cool the interstage coolers within the multi-stage compressor. The outlet of the air compression chamber extraction well is connected to the compressed air heat exchanger, allowing compressed air to enter the heat exchanger. The cryogenic molten salt storage tank is connected to the high-temperature molten salt storage tank. The high-temperature molten salt storage tank is connected to the compressed air heat exchanger, and then to the cryogenic molten salt storage tank. The thermal power unit is connected to the compressed air heat exchanger, using high-temperature flue gas to preheat the compressed air in the heat exchanger. After preheating in the heat exchanger, the compressed air is fed into the multi-stage turboexpander to perform work, driving the generator to generate electricity, and finally venting the compressed air that has performed work.

2. The air compression energy storage coupled coal-fired power plant flexible peak-shaving system according to claim 1, characterized in that, The redundant power generation of new energy power generation and thermal power units when the load is reduced is used to feed into the low-temperature molten salt storage tank for heating the low-temperature molten salt.

3. The air compression energy storage coupled coal-fired power plant flexible peak shaving system according to claim 1, characterized in that, The generator produces electricity to power the grid.

4. The air compression energy storage coupled coal-fired power plant flexible peak-shaving system according to claim 1, characterized in that, The multistage compressor is used to compress air and inject it underground through an air compression chamber injection well. The low-temperature molten salt is connected to the multistage compressor and uses the flow of molten salt to cool the interstage cooler in the multistage compressor.

5. The air compression energy storage coupled coal-fired power plant flexible peak shaving system according to claim 1, characterized in that, The high-temperature, high-pressure air from the compressed air heat exchanger enters the multi-stage turboexpander to perform work, which is then used to generate electricity and connect to the power grid.

6. The air compression energy storage coupled coal-fired power plant flexible peak-shaving system according to claim 1, characterized in that, The temperature range of molten salt in low-temperature molten salt storage tanks is 250℃~400℃.

7. The air compression energy storage coupled coal-fired power plant flexible peak shaving system according to claim 1, characterized in that, The temperature range of molten salt in high-temperature molten salt storage tanks is 300℃~600℃.

8. A method for flexible peak shaving in coal-fired power plants coupled with compressed air energy storage, characterized in that: This method, based on the air compression energy storage coupled coal-fired power plant flexible peak-shaving system described in claim 1, includes: The redundant power generation of new energy power generation and thermal power unit when the load is reduced is fed into the motor and the low temperature molten salt storage tank, respectively. The motor drives the multi-stage compressor to do work, and the low temperature molten salt in the low temperature molten salt storage tank is used to exchange heat and cool down its interstage cooler. Redundant power generation is first fed into the electric motor, and then fed into the cryogenic molten salt storage tank for cryogenic molten salt heating; The abandoned mine shafts of the coal-fired power plant base were used as air compressor storage facilities, and air compressor storage injection wells and air compressor storage extraction wells were set up. Cooled compressed air is introduced into the air compressor storage through the air compressor storage injection well. When work is required, it is extracted through the air compressor storage extraction well and introduced into the compressed air heat exchanger for heating. The heat stored in the high-temperature molten salt storage tank is used to heat the compressed air in the compressed air heat exchanger. If the heat is insufficient, it is heated by the high-temperature flue gas in the thermal power unit. High-temperature flue gas in thermal power units is drawn from the horizontal flue section and turned into the flue chamber. The flue gas temperature is reduced after being heated by compressed air and then introduced into the end of the horizontal flue section. The preheated compressed air in the compressed air heat exchanger is fed into a multi-stage turbo expander to do work, which in turn drives a generator to generate electricity, and finally the compressed air is discharged.

9. The method for flexible peak shaving of coal-fired power plants coupled with air compression energy storage according to claim 8, characterized in that, The temperature range of molten salt in low-temperature molten salt storage tanks is 250℃~400℃.

10. The method for flexible peak shaving of a coal-fired power plant coupled with air compression energy storage according to claim 8, characterized in that, The temperature range of molten salt in high-temperature molten salt storage tanks is 300℃~600℃.

Images