Expansion section of compressed air energy storage system coupled with flue gas waste heat

Abstract

The utility model provides an expansion section of a compressed air energy storage system coupled with flue gas waste heat. The expansion section at least comprises a first-section expansion machine, a second-section expansion machine, a third-section expansion machine and a fourth-section expansion machine which are cascaded in sequence, wherein the first-section expansion machine is further connected with a gas storage, and the fourth-section expansion machine is further connected with a power generator; the air inlet of the first-section expansion machine is also connected with a first heat exchanger; an air inlet of the second-section expansion machine is further connected with a second heat exchanger, an air inlet of the third-section expansion machine is further connected with a third heat exchanger, and an air inlet of the fourth-section expansion machine is further connected with a fourth heat exchanger; the first heat exchanger is further connected with a flue of a coal power unit of a thermal power station outside the compressed air energy storage system. And the second heat exchanger, the third heat exchanger and the fourth heat exchanger are respectively connected with a high-temperature liquid storage tank and a low-temperature liquid storage tank in the compressed air energy storage system. Therefore, flue gas waste heat discharged during production of a thermal power station outside the system can be effectively recycled and utilized, and expansion energy release is well achieved.

Description

Technical Field

[0001] This specification relates to the technical field of compressed air energy storage, and particularly to an expansion section of a compressed air energy storage system coupled with flue gas waste heat. Background Art

[0002] Compressed air energy storage is an important energy storage method. Compared with other energy storage technologies, it has the advantages of short construction period, flexible site selection, diverse gas storage methods, large installed capacity, and long service life. It is a beneficial supplement to pumped hydro energy storage and mainly undertakes tasks such as peak shaving, valley filling, energy storage, frequency modulation and phase modulation, and emergency standby in the power system. Compressed air energy storage technology was initially mainly based on the supplementary combustion technology. In recent years, the non-supplementary combustion compressed air energy storage technology has developed rapidly. Common technical routes include advanced adiabatic compressed air energy storage, isothermal compressed air energy storage, supercritical compressed air energy storage, etc. Among them, advanced adiabatic compressed air energy storage is the current mainstream technical route and has been verified through relevant experimental demonstration projects.

[0003] Currently, the promoted compressed air energy storage projects are mainly of the 300MW level. The advanced adiabatic compressed air energy storage technology is subdivided into a medium-temperature technical route and a high-temperature technical route according to the heat storage temperature. The heat storage medium of the high-temperature technical route generally uses heat-conducting oil (or molten salt) and water. Limited by the manufacturing process of the compressor and the exhaust temperature, the heat storage temperature is about 300°C. However, due to the large initial investment and the lack of a suitable revenue mechanism for compressed air energy storage at present, the development of the high-temperature technical route is restricted. The heat storage medium of the medium-temperature technical route uses pressurized water, and the overall heat storage temperature is about 180 - 230°C, which is currently the most technically and economically optimal solution.

[0004] Specifically, the above-mentioned compressed air energy storage usually includes two processes: a compression energy storage process and an expansion energy release process. Usually, during the low-load period of the power grid, the compression section of the compressed air energy storage system can be used to store energy by compressing, using electrical energy to compress gas and store it in the gas storage reservoir; during the high-load period of the power grid, the expansion section of the compressed air energy storage system can be used to release energy by expansion, releasing the compressed gas in the gas storage reservoir to drive the air turbine to generate electricity and obtain the corresponding electrical energy. During the specific process of expanding and releasing energy, the heat energy collected and stored during compressed air energy storage is usually used to preheat the gas input into the expander to increase the temperature of the input gas. However, based on the relatively limited heat energy collected during compressed air energy storage by the existing system equipment, and some heat energy will be lost when the above heat energy is stored in the heat storage structure, resulting in relatively less heat energy that can be actually utilized during the expansion energy release process, unable to achieve the desired preheating effect, and thus affecting the work effect of the expansion energy release.

[0005] Regarding the above problems, the existing technology cannot effectively solve them. Content of the Utility Model

[0006] The purpose of the embodiment of the present application is to provide an expansion section of a compressed air energy storage system coupled with flue gas waste heat, which can effectively recover and utilize the flue gas waste heat discharged during the production of a thermal power station outside the compressed air energy storage system, and assist in preheating the gas input into the expander during the expansion and energy release process to achieve a better preheating effect, thereby being able to better realize the expansion and energy release and improve the overall energy utilization rate.

[0007] This specification provides an expansion section of a compressed air energy storage system coupled with flue gas waste heat, which at least includes a first-stage expander, a second-stage expander, a third-stage expander, and a fourth-stage expander cascaded in sequence;

[0008] Among them, the first-stage expander is also connected to a gas storage reservoir, and the fourth-stage expander is also connected to a generator;

[0009] The air inlet of the first-stage expander is also connected to a first heat exchanger; the air inlet of the second-stage expander is also connected to a second heat exchanger, the air inlet of the third-stage expander is also connected to a third heat exchanger, and the air inlet of the fourth-stage expander is also connected to a fourth heat exchanger;

[0010] The first heat exchanger is connected to the flue gas duct of the coal-fired power generation unit of the thermal power station outside the compressed air energy storage system; the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are respectively connected to the high-temperature liquid storage tank and the low-temperature liquid storage tank inside the compressed air energy storage system.

[0011] In one embodiment, the first heat exchanger is a composite phase change heat exchanger.

[0012] In one embodiment, the second heat exchanger is a hairpin heat exchanger.

[0013] In one embodiment, the third heat exchanger and the fourth heat exchanger are cross-flow heat exchangers.

[0014] In one embodiment, a flue gas collector is provided on the flue gas duct of the coal-fired power generation unit of the thermal power station, and the flue gas collector is connected to the first heat exchanger through a pipeline.

[0015] In one embodiment, a first regulating valve is provided on the pipeline between the flue gas collector and the first heat exchanger.

[0016] In one embodiment, a temperature sensor is also provided at the flue gas collector.

[0017] In one embodiment, corresponding high-temperature regulating valves are respectively provided on the pipelines between the first heat exchanger and the high-temperature liquid storage tank, between the second heat exchanger and the high-temperature liquid storage tank, and between the third heat exchanger and the high-temperature liquid storage tank.

[0018] In one embodiment, corresponding low-temperature regulating valves are respectively arranged on the pipelines between the first heat exchanger and the low-temperature liquid storage tank, between the second heat exchanger and the low-temperature liquid storage tank, and between the third heat exchanger and the low-temperature liquid storage tank.

[0019] In one embodiment, the gas storage reservoir is further connected with a compression section; wherein, the compression section at least includes a first-stage compressor, a second-stage compressor, a third-stage compressor, and a fourth-stage compressor cascaded in sequence.

[0020] Based on the expansion section of the compressed air energy storage system with coupled flue gas waste heat provided in this specification, it at least includes a first-stage expander, a second-stage expander, a third-stage expander, and a fourth-stage expander cascaded in sequence; wherein, the first-stage expander is further connected with the gas storage reservoir, and the fourth-stage expander is further connected with the generator; the air inlet of the first-stage expander is further connected with a first heat exchanger; the air inlet of the second-stage expander is further connected with a second heat exchanger, the air inlet of the third-stage expander is further connected with a third heat exchanger, and the air inlet of the fourth-stage expander is further connected with a fourth heat exchanger; the first heat exchanger can be connected with the flue of the coal-fired power generation unit of the thermal power station outside the compressed air energy storage system for collecting and utilizing the waste heat of the flue gas discharged by the thermal power station; the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are respectively connected with the high-temperature liquid storage tank and the low-temperature liquid storage tank inside the compressed air energy storage system. Based on the expansion section with the above structure, it can effectively recover and utilize the waste heat of the flue gas discharged during the production of the thermal power station outside the compressed air energy storage system, and assist in preheating the gas input into the expander during the expansion energy release process to obtain a better preheating effect, thereby being able to better realize the expansion energy release, improve the overall energy utilization rate, and the overall efficiency of the compressed air energy storage system. Description of the Drawings

[0021] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 It shows a schematic structural composition diagram of an expansion section of a compressed air energy storage system with coupled flue gas waste heat provided in this specification;

[0023] Figure 2 It shows a schematic structural composition diagram of a compressed air energy storage system based on an expansion section of a compressed air energy storage system with coupled flue gas waste heat provided in this specification. Detailed Embodiments

[0024] To enable those skilled in the art to better understand the technical solutions in this application, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in this application without creative efforts shall fall within the scope of protection of this application.

[0025] Considering that the advanced adiabatic compressed air energy storage technology based on the medium-temperature solution mostly adopts the four-stage compression and three-stage expansion solution. Based on the above solution, since the exhaust temperature of the last-stage compressor is relatively low, heat recovery is generally not considered, or the heat of this part is recovered by a heat exchanger and used for preheating the air of the compressor and the inlet air of the expander. According to the theoretical energy storage efficiency of compressed air energy storage, the system efficiency is related to the efficiency of equipment such as compressors and expanders on the one hand, and is also related to the configuration of the compression process and the expansion process on the other hand. According to calculations, there is an optimal stage ratio (the ratio of the number of expansion stages to the number of compression stages) for the compressed air energy storage system, and the optimal stage ratio is 1. Therefore, when the stage ratio decreases, the system's theoretical energy storage efficiency drops rapidly; when the stage ratio increases, the system's energy storage efficiency also shows a downward trend, but gradually flattens out.

[0026] Based on the above considerations, the present utility model particularly designs a compressed air energy storage system that can utilize external industrial waste heat (for example, the flue gas waste heat of a thermal power station), which can fully recover and utilize the heat of the external industrial waste heat, and increase the temperature of the corresponding expander inlet through a matching heat exchanger; at the same time, on the basis of the four-stage compression and three-stage expansion solution, one more stage of expansion is added, that is, four-stage compression and four-stage expansion, so that the stage ratio of the compressed air energy storage system is 1, reaching the optimal stage ratio and improving the overall system efficiency.

[0027] Refer to Figure 1 As shown, this specification provides an expansion section of a compressed air energy storage system coupled with flue gas waste heat, which may at least include a first-stage expander, a second-stage expander, a third-stage expander, and a fourth-stage expander cascaded in sequence;

[0028] Among them, the first-stage expander is also connected to the gas storage reservoir, and the fourth-stage expander is also connected to the generator;

[0029] The inlet of the first-stage expander is also connected to a first heat exchanger; the inlet of the second-stage expander is also connected to a second heat exchanger, the inlet of the third-stage expander is also connected to a third heat exchanger, and the inlet of the fourth-stage expander is also connected to a fourth heat exchanger;

[0030] The first heat exchanger is connected to the flue of the coal-fired power unit of the thermal power station outside the compressed air energy storage system; the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are respectively connected to the high-temperature liquid storage tank and the low-temperature liquid storage tank inside the compressed air energy storage system.

[0031] The above-mentioned gas storage reservoir can be specifically used to store compressed gas (or high-pressure gas).

[0032] The compressed gas may be air, carbon dioxide, or other suitable types of gas. The specific type of the compressed gas is not limited in this specification.

[0033] The high temperature liquid storage tank can be used to store high temperature heat storage medium. The low temperature liquid storage tank can be used to store low temperature heat storage medium.

[0034] The heat storage medium may specifically include one or more combinations of the following: water, heat transfer oil, molten salt, etc. In specific implementation, a suitable type of heat storage medium may also be selected according to the temperature requirements in the actual working scene.

[0035] Specifically, the compressed air energy storage system may further include a compression section.

[0036] Specifically, during the compression energy storage process, the compression section compresses the gas by running the compressor, converting electrical energy into the potential energy of the compressed gas; and storing the compressed gas in the gas storage reservoir; at the same time, the compression section also collects the heat energy during the compression energy storage process through the corresponding structure, and stores it in a high-temperature liquid storage tank so that it can be used by the expansion section during the expansion energy release process.

[0037] Specifically, the thermal power station can be located outside the compressed air energy storage system. The thermal power station can use coal-fired power units to generate thermal power and feed the generated electric energy into the power grid.

[0038] The applicant has found through long-term practical research that in thermal power plants, coal-fired power units often play a major role in the stable operation of the power system. However, the heat loss of coal-fired power units in existing thermal power plants accounts for more than 65% of the heat loss of the boiler. It can be seen that a large amount of thermal energy is contained in the flue gas emitted by the coal-fired power units in thermal power plants. However, based on the existing system equipment, most of the flue gas is directly discharged into the atmosphere, and the thermal energy cannot be effectively utilized, resulting in energy waste.

[0039] Furthermore, the applicant considered that the heat energy in the flue gas emitted by the coal-fired power units of thermal power plants could be recovered and utilized to assist the high-temperature liquid storage tank in the compressed air energy storage system to preheat the air input to the expander, so as to ensure that the air input to the expander inlet can reach the desired temperature and obtain a better preheating effect, so as to better achieve the subsequent expansion work.

[0040] Specifically, considering that the air temperature directly accessed by the first expander in the expansion section is the lowest among other expanders and the demand for thermal energy is relatively the highest; at the same time, the thermal energy in the flue gas discharged from the coal-fired power generation unit of the thermal power station is often considerable and can better meet the thermal energy demand of the first expander.

[0041] Therefore, the first heat exchanger disposed at a position adjacent to the air inlet of the first expander can be connected to the flue duct of the coal-fired power generation unit of the thermal power station outside the compressed air energy storage system; wherein, the air inlet of the first heat exchanger is connected to the gas storage reservoir through a pipeline.

[0042] In Figure 1 it, the solid line with an arrow represents the gas flow path, and the dashed line with an arrow represents the heat storage medium flow path.

[0043] In this way, based on the expansion section with the above structure, during the process of expansion and energy release, when the compressed gas output from the gas storage reservoir passes through the first heat exchanger, it can be preheated by using the thermal energy recovered from the flue gas discharged from the coal-fired power generation unit of the thermal power station outside the compressed air energy storage system to reach the desired temperature; then it is input into the first expander for expansion work; the gases output from the first expander, the second expander, and the third expander can respectively pass through the corresponding second heat exchanger, the third heat exchanger, and the fourth heat exchanger, and are preprocessed by using the thermal energy collected and stored in the high-temperature liquid storage tank from the compression section inside the compressed air energy storage system to reach the desired temperature, and then are input into the next-stage expander for expansion work. Thus, the waste heat of the flue gas discharged during the production of the thermal power station outside the system can be effectively recovered and utilized to supplement the thermal energy collected by the compressed air energy storage system, and the gas input into the expander can be assisted in preheating in a targeted manner during the expansion and energy release process. On the one hand, the expansion and energy release can be better realized, and on the other hand, the overall energy utilization rate is improved, and the waste of the thermal energy of the flue gas discharged from the coal-fired power generation unit of the thermal power station is reduced.

[0044] In some embodiments, the first heat exchanger can specifically be a composite phase change heat exchanger.

[0045] Among them, based on the above composite phase change heat exchanger, heat transfer can be carried out by using the latent heat of phase change of water in the closed tube bundle component. After water is heated at the lower end face of the heat pipe and becomes saturated steam, it moves to the upper end of the heat tank. After the steam releases heat and condenses into saturated water, the saturated water enters the heated section again for heating and vaporization after steam-water separation.

[0046] Based on the above embodiments, by introducing and using the composite phase change heat exchanger as the first heat exchanger, the waste heat in the flue gas can be more effectively recovered and utilized.

[0047] In some embodiments, the first heat exchanger may also be connected to a high-temperature liquid storage tank and a low-temperature liquid storage tank through an auxiliary pipeline; wherein, a switching valve is provided on the auxiliary pipeline.

[0048] Under normal circumstances, the switching valve is default in an open state, and correspondingly, the auxiliary pipeline is disconnected. At this time, the waste heat of the flue gas discharged from the thermal power station outside the compressed air energy storage system is mainly recycled to preheat the gas input to the first-stage expansion joint machine.

[0049] When, due to special reasons, the waste heat of the flue gas discharged from the thermal power station cannot be used temporarily (for example, the thermal power station is under maintenance and not in production), the switching valve can be closed, and correspondingly, the auxiliary pipeline is conducted. At this time, the heat energy stored in the high-temperature liquid storage tank inside the compressed air energy storage system can be used through the auxiliary pipeline to preheat the gas input to the first-stage expansion joint machine.

[0050] In some embodiments, the second heat exchanger may specifically be a hairpin heat exchanger.

[0051] Specifically, this is because the gas discharged from the first-stage expander still has a relatively large pressure and a relatively larger temperature difference compared to other expanders.

[0052] Therefore, using a hairpin heat exchanger as the second heat exchanger here can better adapt to the above scenario and more effectively utilize the heat energy in the high-temperature liquid storage tank to preheat the gas to be input to the second-stage expander, so as to obtain a relatively better expansion energy release effect.

[0053] In some embodiments, the third heat exchanger and the fourth heat exchanger may specifically be cross-flow heat exchangers.

[0054] Specifically, this is because the gas flow discharged from the second-stage expander or the third-stage expander is relatively large and the requirement for pressure drop is relatively high.

[0055] Therefore, using a cross-flow heat exchanger as the third heat exchanger or the fourth heat exchanger here can better adapt to the above scenario and more effectively utilize the heat energy in the high-temperature liquid storage tank to preheat the gas to be input to the third-stage expander or the fourth-stage expander, so as to obtain a relatively better expansion energy release effect.

[0056] In some embodiments, during specific implementation, a flue gas collector may also be provided on the flue of the coal-fired power generation unit of the thermal power station, wherein the flue gas collector is connected to the first heat exchanger through a pipeline.

[0057] During specific implementation, refer to Figure 1As shown, the flue gas discharged from the coal-fired power generation unit of a power station can be effectively collected by a flue gas collector and transported through relevant pipelines to the first heat exchanger for heat exchange; the flue gas after heat exchange is then discharged into the atmosphere. Thus, the heat energy in the above flue gas can be effectively recovered and utilized, reducing the waste of heat energy.

[0058] In some embodiments, a pipeline regulating valve is provided on the pipeline between the flue gas collector and the first heat exchanger.

[0059] During specific implementation, according to specific situations and treatment requirements, by adjusting the pipeline regulating valve, the flow rate of the actually recovered and utilized flue gas can be finely adjusted, and then the temperature of the compressed gas to be input into the first-stage expander can be adjusted relatively more precisely.

[0060] In some embodiments, a temperature sensor is also provided at the flue gas collector.

[0061] During specific implementation, the above temperature sensor can monitor and display the actual temperature of the flue gas directly discharged from the coal-fired power generation unit of the power station.

[0062] Correspondingly, according to the temperature of the flue gas, the pipeline regulating valve can be adjusted targeted and accurately.

[0063] For example, when the temperature of the flue gas is high, higher than the preset reference temperature threshold, the pipeline regulating valve can be adjusted targeted to appropriately reduce the flow rate of the flue gas transported through the pipeline to the first heat exchanger.

[0064] Also for example, when the temperature of the flue gas is low, lower than the preset reference temperature threshold, the pipeline regulating valve can be adjusted targeted to appropriately increase the flow rate of the flue gas transported through the pipeline to the first heat exchanger.

[0065] Thus, the waste heat of the flue gas can be recovered and utilized relatively more precisely, making the preheating of the gas to be input into the first-stage expander relatively more stable and always meeting the requirements.

[0066] In some embodiments, corresponding high-temperature regulating valves are respectively provided on the pipelines between the first heat exchanger and the high-temperature liquid storage tank, between the second heat exchanger and the high-temperature liquid storage tank, and between the third heat exchanger and the high-temperature liquid storage tank.

[0067] Based on the above embodiments, the corresponding high-temperature regulating valves can be used to preheat the corresponding gas with the heat energy inside the compressed air energy storage system relatively more precisely.

[0068] In some embodiments, corresponding low-temperature regulating valves are respectively provided on the pipelines between the first heat exchanger and the low-temperature liquid storage tank, between the second heat exchanger and the low-temperature liquid storage tank, and between the third heat exchanger and the low-temperature liquid storage tank.

[0069] Based on the above embodiments, a corresponding low-temperature regulating valve can be used to preheat the corresponding gas with the thermal energy inside the compressed air energy storage system relatively more precisely.

[0070] In some embodiments, referring to Figure 2 as shown, the gas storage reservoir may also be connected to a compression section; wherein, the compression section at least includes a first-stage compressor, a second-stage compressor, a third-stage compressor, and a fourth-stage compressor cascaded in sequence.

[0071] Among them, the above-mentioned first-stage compressor, second-stage compressor, third-stage compressor, and fourth-stage compressor may also be respectively associated with the high-temperature liquid storage tank.

[0072] Based on the above embodiments, the compression section in the compressed air energy storage system can be effectively utilized. During the compression energy storage process, the compressed gas containing a large amount of potential energy is stored in the gas storage reservoir for subsequent use in the expansion section; and, the internal thermal energy is collected and stored in the high-temperature liquid storage tank for subsequent use in the expansion section.

[0073] In some embodiments, the above-mentioned second heat exchanger may also be connected to the third-stage compression to be used as a heat exchanger in the compression section during the compression energy storage process.

[0074] In addition, the above-mentioned third heat exchanger and fourth heat exchanger may also be respectively connected to the first-stage compressor and the second-stage compressor to be used as the corresponding heat exchangers in the compression section during the compression energy storage process.

[0075] Thus, the equipment structure in the compressed air energy storage system can be effectively utilized, the construction cost of the system can be reduced, and the utilization rate of the equipment in the system can be improved.

[0076] In some embodiments, corresponding temperature sensors may be respectively arranged at positions adjacent to the air inlets of the first-stage expander, the second-stage expander, the third-stage expander, and the fourth-stage expander.

[0077] Correspondingly, during specific implementation, the regulating valve of the corresponding heat exchanger can be adjusted targeted according to the gas temperature measured by the temperature sensor at the position adjacent to the air inlet of the expander, so that the temperature of the gas input to the expander can accurately reach the desired temperature.

[0078] In some embodiments, the above-mentioned expansion section may further include a processor. Among them, the above-mentioned processor may be electrically connected to the first-stage expander, the second-stage expander, the third-stage expander, the fourth-stage expander, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, and the related regulating valves respectively.

[0079] In specific implementation, the above-mentioned processor can, according to the corresponding instruction program, realize automatic expansion energy release by intelligently controlling the first-stage expander, the second-stage expander, the third-stage expander, the fourth-stage expander, the first heat exchanger, the second heat exchanger, the third heat exchanger, the fourth heat exchanger, and the relevant regulating valves.

[0080] In summary, based on the expansion section of the compressed air energy storage system coupled with flue gas waste heat provided in this specification, it at least includes a first-stage expander, a second-stage expander, a third-stage expander, and a fourth-stage expander cascaded in sequence; wherein, the first-stage expander is also connected to the gas storage reservoir, and the fourth-stage expander is also connected to the generator; the air inlet of the first-stage expander is also connected to a first heat exchanger; the air inlet of the second-stage expander is also connected to a second heat exchanger, the air inlet of the third-stage expander is also connected to a third heat exchanger, and the air inlet of the fourth-stage expander is also connected to a fourth heat exchanger; the first heat exchanger is connected to the flue gas duct of the coal-fired power generation unit of the thermal power station outside the compressed air energy storage system; the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are respectively connected to the high-temperature liquid storage tank and the low-temperature liquid storage tank inside the compressed air energy storage system. Thus, it can effectively recover and utilize the flue gas waste heat discharged during the production of the thermal power station outside the system, and better realize expansion energy release. Based on the expansion section with the above structure, it can effectively recover and utilize the flue gas waste heat discharged during the production of the thermal power station outside the system, assist in preheating the gas input into the expander during the expansion energy release process, obtain a better preheating effect, and then can better realize expansion energy release and improve the overall energy utilization rate.

[0081] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key points of each embodiment are the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the relevant embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the relevant embodiment. In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of this specification. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0082] The above are only examples of the embodiments of this specification and are not used to limit the embodiments of this specification. For those skilled in the art, various modifications and variations can be made to the embodiments of this specification. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of this specification shall be included within the scope of the claims of the embodiments of this specification.

Claims

1. An expansion section of a compressed air energy storage system coupled with flue gas waste heat, characterized in that: At least comprising a first-stage expander, a second-stage expander, a third-stage expander, and a fourth-stage expander connected in cascade order; Wherein, the first-stage expander is also connected to a gas storage reservoir, and the fourth-stage expander is also connected to a generator; The air inlet of the first-stage expander is also connected to the first heat exchanger; the air inlet of the second-stage expander is also connected to the second heat exchanger, the air inlet of the third-stage expander is also connected to the third heat exchanger, and the air inlet of the fourth-stage expander is also connected to the fourth heat exchanger; The first heat exchanger is connected to the flue of the coal-fired power unit of the thermal power station outside the compressed air energy storage system; the second heat exchanger, the third heat exchanger, and the fourth heat exchanger are respectively connected to the high-temperature liquid storage tank and the low-temperature liquid storage tank inside the compressed air energy storage system.

2. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1 is characterized in that: The first heat exchanger is a composite phase change heat exchanger.

3. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1 is characterized in that: The second heat exchanger is a hairpin heat exchanger.

4. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1 is characterized in that: The third heat exchanger and the fourth heat exchanger are cross-flow heat exchangers.

5. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1, characterized in that: A flue gas collector is arranged on the flue of the coal-fired power unit of the thermal power station, and the flue gas collector is connected to the first heat exchanger through a pipeline.

6. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 5, characterized in that: A pipeline regulating valve is arranged on the pipeline between the flue gas collector and the first heat exchanger.

7. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 5, characterized in that: A temperature sensor is also arranged at the smoke collector.

8. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1, characterized in that: Corresponding high-temperature regulating valves are respectively arranged on the pipeline between the first heat exchanger and the high-temperature liquid storage tank, the pipeline between the second heat exchanger and the high-temperature liquid storage tank, and the pipeline between the third heat exchanger and the high-temperature liquid storage tank.

9. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1, characterized in that: Corresponding low-temperature regulating valves are respectively arranged on the pipeline between the first heat exchanger and the low-temperature liquid storage tank, the pipeline between the second heat exchanger and the low-temperature liquid storage tank, and the pipeline between the third heat exchanger and the low-temperature liquid storage tank.

10. The expansion section of the compressed air energy storage system coupled with flue gas waste heat according to claim 1, characterized in that: The gas storage is also connected to a compression section; wherein the compression section at least includes a first-stage compressor, a second-stage compressor, a third-stage compressor, and a fourth-stage compressor which are cascaded in sequence.

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