Liquid air energy storage and thermal power generating unit thermal coupling and energy gradient utilization system

Abstract

The invention discloses a liquid air energy storage and thermal power generating unit thermal coupling and energy gradient utilization system which comprises a thermal power generating unit system. In the air compression system, a second steam turbine is configured to drive an air compressor set to operate through steam extraction of a first steam turbine, the air compressor set comprises a plurality of air compressors connected in sequence, and outlets of the air compressors are each provided with a first heat exchanger in series; in the compression heat recovery system, a first heat storage box is arranged on a recovery pipeline, and a first heat exchanger is connected to the recovery pipeline in series; a cold box, an expansion refrigerator and a gas-liquid separator in the liquid air energy storage system are sequentially connected, the cold box is connected with an outlet of an air compressor unit, and a liquid storage box is communicated with a liquid outlet of the gas-liquid separator. According to the liquid air energy storage and thermal power generating unit thermal coupling and energy gradient utilization system, redundant heat energy of a thermal power generating unit can be fully recycled, the overall energy efficiency of the system is well improved, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage and thermal power coupled power generation, and in particular to a system for thermal coupling of liquid air energy storage and thermal power units and cascade energy utilization. Background Art

[0002] With the integration of a high proportion of renewable energy into new power systems, the volatility and uncertainty of power loads have significantly increased, and the demand for regulation and flexibility on the power supply side has become increasingly prominent. Coal-fired power plants, as the foundational power source, continue to play an irreplaceable role in ensuring the safe and stable operation of the power grid. However, traditional thermal power plants suffer from insufficient peak-shaving capacity, limited minimum output, and high equipment losses from frequent starts and stops, which seriously restrict their role in flexible regulation.

[0003] In related technologies, thermal power units are combined with liquid air energy storage to work together, so that the thermal power units can store energy through the liquid air energy storage system when operating at low load and release energy when needed, thereby improving the flexibility of power system operation. However, the liquid air energy storage system does not fully recover the redundant heat energy generated during the operation of the thermal power units, and the utilization rate is low, which makes the overall energy efficiency of the thermal power system low and the operating cost high. Summary of the Invention

[0004] The present invention is based on the findings of the inventors of this application regarding the following facts and problems: Thermal power units in power systems generate a large amount of redundant heat energy during low load or off-grid standby periods, such as steam extraction from the intermediate-pressure cylinders of steam turbines. In related technologies, the energy recovery and utilization of the extracted steam is insufficient when thermal power units are coupled with liquid air energy storage, resulting in low overall energy efficiency and high operating costs for the coupled system.

[0005] The present invention aims to address at least one of the technical problems existing in the prior art. To this end, the present invention proposes a system for thermally coupling liquid air energy storage with a thermal power unit and utilizing energy in a cascaded manner. This system can fully recover redundant thermal energy from the system, significantly improving the overall energy efficiency of the system and reducing operating costs.

[0006] According to the present invention, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system includes: a thermal power unit system, the thermal power unit system includes a first steam turbine; an air compression system, including: a second steam turbine and an air compressor unit, the second steam turbine is configured to use the extraction steam of the first steam turbine to drive the air compressor unit to operate, the air compressor unit includes a plurality of air compressors connected in sequence, and the outlets of the air compressors are all connected in series with a first heat exchanger; a compression heat recovery system, including: a first heat storage tank and a recovery pipeline, the first heat storage tank is arranged on the recovery pipeline, The first heat exchanger is connected in series to the recovery pipeline so that the fluid in the recovery pipeline exchanges heat with the compressed air. The first heat storage tank is located downstream of the first heat exchangers in the fluid flow direction of the recovery pipeline. The first heat storage tank is provided with a heat storage element. The liquid air energy storage system includes: a cold box, an expansion refrigerator, a gas-liquid separator and a liquid storage tank. The cold box, the expansion refrigerator and the gas-liquid separator are connected in sequence. The cold box is connected to the outlet of the air compressor unit, and the liquid storage tank is connected to the liquid outlet of the gas-liquid separator. The cold box is configured to cool the compressed air.

[0007] According to the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system of the present invention, an air compression system, a compression heat recovery system and a liquid air energy storage system are provided. The air compression system is provided with an air compressor unit, and the air compressor unit is provided with air compressors connected in sequence. The compression heat recovery system is provided with a recovery pipeline to recover the heat of the compressed air discharged after compression by each air compressor step by step through a first heat exchanger and store it in a first heat storage tank. The liquid air energy storage system liquefies the compressed air and stores it in a liquid storage tank, so that the redundant heat energy of the thermal power unit system during low-load operation can be extracted to the second steam turbine. Under the coordinated operation of the air compression system, the compression heat recovery system and the liquid air energy storage system, the redundant heat energy of the thermal power unit is stored in the first heat storage tank and the liquid storage tank in the form of heat energy and cold energy, respectively. The redundant heat energy of the thermal power unit is fully recovered and utilized more flexibly, thereby greatly improving the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system and reducing the operating cost.

[0008] In some embodiments of the present invention, the air compressor group includes a first-stage compressor, a second-stage compressor and a third-stage compressor connected in sequence, and the air compression system also includes a first connecting pipeline, the first connecting pipeline includes a first connecting pipe, a second connecting pipe and a third connecting pipe, the first connecting pipe is connected to the air outlet of the first-stage compressor and the air inlet of the second-stage compressor, the second connecting pipe is connected to the air outlet of the second-stage compressor and the air inlet of the third-stage compressor, the third connecting pipe is connected to the air outlet of the third-stage compressor and the cold box, and the first heat exchanger is respectively connected in series to the first connecting pipe, the second connecting pipe and the third connecting pipe.

[0009] In some embodiments of the present invention, the liquid air energy storage system further includes: a second heat exchanger and a second connecting pipeline, the second connecting pipeline being connected to the liquid storage tank, the second heat exchanger being connected in series to the second connecting pipeline, the second heat exchanger being configured to heat the fluid in the second connecting pipeline to vaporize the liquid air; an air expansion unit and a generator, the air expansion unit being connected in series to the second connecting pipeline and being located downstream of the second heat exchanger in the direction of fluid flow in the second connecting pipeline, the air expansion unit including a plurality of air expanders connected in sequence along the direction of fluid flow in the second connecting pipeline, the air expansion unit being transmission-connected to the generator, and a heater being connected in series to the inlet of each of the air expanders; a heating pipeline, one end of the heating pipeline being connected to the exhaust port of the second steam turbine, the thermal power unit system further including a condenser, the other end of the heating pipeline being connected to the condenser, the heater being connected in series to the heating pipeline so that the fluid in the heating pipeline heats the fluid in the second connecting pipeline.

[0010] In one embodiment of the present invention, the air expansion unit includes at least a first-stage expander, a second-stage expander and a third-stage expander connected in sequence, and the second connecting pipeline includes: a fourth connecting pipe, a fifth connecting pipe and a sixth connecting pipe, the fourth connecting pipe is connected to the liquid storage tank and the inlet of the first-stage expander, the fifth connecting pipe is connected to the outlet of the first-stage expander and the inlet of the second-stage expander, and the sixth connecting pipe is connected to the outlet of the second-stage expander and the inlet of the third-stage expander, wherein the heater has a first heat exchange channel and a second heat exchange channel for mutual heat exchange, the first heat exchange channels of the multiple heaters are all connected in series to the heating pipeline, and the second heat exchange channels of the multiple heaters are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe and the sixth connecting pipe.

[0011] In one embodiment of the present invention, the heating pipeline includes: a main heating pipe and multiple branch pipes, the two ends of the main heating pipe are respectively connected to the exhaust port of the second steam turbine and the condenser, the two ends of the branch pipe are respectively connected to the main heating pipe, and the heater is connected in series to the branch pipe.

[0012] In one embodiment of the present invention, the second heat exchanger has a first heat exchange channel and a second heat exchange channel for mutual heat exchange, and the second heat exchange channel is connected in series to the second connecting pipeline. The liquid air energy storage system also includes a first heat exchange pipeline and a cold storage box. The first heat exchange pipeline is connected in series with the cold box, the first heat exchange channel and the cold storage box. The cold storage box is located downstream of the first heat exchange channel in the direction of fluid flow in the first heat exchange pipeline, and the cold storage box is configured to provide cold energy to the cold box.

[0013] In some examples of the present invention, the cold box has a third heat exchange channel, a fourth heat exchange channel and a fifth heat exchange channel for mutual heat exchange, the air compression system also includes a first connecting pipeline, the first connecting pipeline is connected in series with multiple air compressors in sequence, the fourth heat exchange channel is connected in series with the first connecting pipeline, the fifth heat exchange channel is connected in series with the first heat exchange pipeline, the air compression system also includes a return air pipe, the return air pipe is connected to the air outlet of the gas-liquid separator and the air inlet of the air compressor group, and the third heat exchange channel is connected in series with the return air pipe.

[0014] In one embodiment of the present invention, the thermal power unit system also includes a boiler, which is provided with a smoke exhaust pipeline. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system also includes a flue gas waste heat utilization system, which includes: a second heat storage tank, which is provided in the smoke exhaust pipeline; a second heat exchange pipeline and a three-way valve, the second heat exchange pipeline is switchably connected to the first heat storage tank and the second heat storage tank through the three-way valve, the second heat exchanger has a second heat exchange flow channel and a third heat exchange flow channel for mutual heat exchange, the second heat exchange flow channel is serially connected to the second connecting pipeline, and the third heat exchange flow channel is serially connected to the second heat exchange pipeline.

[0015] In one embodiment of the present invention, the liquid air energy storage system further includes a pressure pump, which is provided in the second connecting pipe and located between the liquid storage tank and the second heat exchanger.

[0016] In some embodiments of the present invention, the first steam turbine includes an intermediate pressure cylinder, the intermediate pressure cylinder is provided with a steam extraction port, the second steam turbine is connected to the steam extraction port, and the steam extraction pressure of the steam extraction port is greater than or equal to 1 MPa and less than or equal to 3.5 MPa.

[0017] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of a system for thermal coupling of liquid air energy storage and thermal power generation units and cascade energy utilization according to an embodiment of the present invention.

[0019] Reference numerals: 11. First steam turbine; 111. High-pressure cylinder; 112. Intermediate-pressure cylinder; 113. Low-pressure cylinder; 12. Boiler; 121. Exhaust pipe; 13. Condenser; 21. Second steam turbine; 22. Air compressor unit; 221. First-stage compressor; 222. Second-stage compressor; 223. Third-stage compressor; 23. First connecting pipeline; 24. First heat exchanger; 30. Compression heat recovery system; 31. Recovery pipeline; 32. First heat storage tank; 401, second connecting pipeline; 402, heating pipeline; 403, first heat exchange pipeline; 404, return air pipe; 41. Cold box; 42. Expansion refrigerator; 43. Gas-liquid separator; 44. Liquid storage tank; 45. Second heat exchanger; 46. ​​Air expansion unit; 461. First-stage expander; 462. Second-stage expander; 463. Third-stage expander; 47. Heater; 48. Cold storage box; 49. Pressure pump; 50. Flue gas waste heat utilization system; 51. Second heat exchange pipeline; 52. Second heat storage tank; 53. Three-way valve; 100. Liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system. DETAILED DESCRIPTION

[0020] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but are not to be construed as limiting the present invention.

[0021] Reference below Figure 1 A system 100 for thermal coupling of liquid air energy storage and thermal power generation units and cascade energy utilization according to an embodiment of the present invention is described.

[0022] like Figure 1As shown, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 according to an embodiment of the present invention includes: a thermal power unit system, an air compression system, a compression heat recovery system 30 and a liquid air energy storage system.

[0023] Specifically, the thermal power unit system includes a first steam turbine 11; the air compression system includes: a second steam turbine 21 and an air compressor unit 22, the second steam turbine 21 is configured to use the extraction steam of the first steam turbine 11 to drive the air compressor unit 22 to operate, the air compressor unit 22 includes a first connecting pipeline 23 and a plurality of air compressors connected in sequence, and the outlets of the air compressors are all connected in series with a first heat exchanger 24; the compression heat recovery system 30 includes: a first heat storage tank 32 and a recovery pipeline 31, the first heat storage tank 32 is provided in the recovery pipeline 31, and the first heat exchanger 24 is connected in series with the recovery pipeline 31, so that the fluid in the recovery pipeline 31 exchanges heat with the compressed air. The first heat storage tank 32 is located downstream of the multiple first heat exchangers 24 in the fluid flow direction in the recovery pipeline 31, and the first heat storage tank 32 is provided with a heat storage element. The liquid air energy storage system includes: a cold box 41, an expansion refrigerator 42, a gas-liquid separator 43 and a liquid storage tank 44. The cold box 41, the expansion refrigerator 42 and the gas-liquid separator 43 are connected in sequence. The cold box 41 is connected to the outlet of the air compressor unit 22, and the liquid storage tank 44 is connected to the liquid outlet of the gas-liquid separator 43. The cold box 41 is configured to cool the compressed air.

[0024] In this embodiment, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 includes a thermal power unit system. The thermal power unit system heats water by burning fossil fuels in a boiler 12, so that the water is heated into steam and then drives the steam turbine to operate, thereby driving the generator to generate electricity, thereby meeting the use requirements of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100. By way of example, the thermal power unit system may include a boiler 12, a condenser 13, a condensate pump, a low-pressure heater 47, a deaerator, a feed water pump, a high-pressure heater 47 and a first steam turbine 11 and other devices to meet the operation needs of the thermal power unit system. The first steam turbine 11 may include a high-pressure cylinder 111, a medium-pressure cylinder 112 and a low-pressure cylinder 113 to efficiently utilize steam to drive the generator to operate, so that the thermal power unit can operate efficiently to generate electricity.

[0025] In this embodiment, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 also includes an air compression system and a compression heat recovery system 30. The air compression system is provided with a second steam turbine 21 and an air compressor unit 22. The second steam turbine 21 utilizes the extraction steam of the first steam turbine 11 to drive the air compressor unit 22 to operate, so that the air compressor unit 22 performs air compression operations under the drive of the second steam turbine 21. The air compressor unit 22 includes a plurality of air compressors connected in sequence, that is, the plurality of air compressors of the air compressor unit 22 cooperate with each other to compress the air step by step. For example, along the air flow direction in the air compressor unit 22, the air is compressed in the first air compressor and then flows into the next air compressor for re-compression, so that the air is compressed step by step, so that the air compressor unit 22 can efficiently compress the air, making the operation efficiency of the air compression system higher and more stable.

[0026] In this embodiment, a first heat exchanger 24 is provided in series at the outlet of the air compressor. For example, the number of the first heat exchangers 24 can be the same as the number of the air compressors. For example, when three air compressors are provided in the air compressor group 22, the number of the first heat exchangers 24 can also be three. The compression heat recovery system 30 is provided with a first heat storage tank 32 and a recovery pipeline 31. A plurality of first heat exchangers 24 are connected in series to the recovery pipeline 31 so that the fluid in the recovery pipeline 31 exchanges heat with the compressed air formed after the air is compressed by the air compressor. The first heat storage tank 32 is located downstream of the plurality of first heat exchangers 24 in the fluid flow direction in the recovery pipeline 31. For example, the fluid in the recovery pipeline 31 can be a heat exchange fluid such as heat transfer oil. When the air compression system is running, the temperature of the air rises after entering the air compressor and is compressed. The compressed air flows through the first heat exchanger 32. The heat exchanger 24 exchanges heat with the heat exchange fluid in the recovery pipeline 31, so that the heat in the compressed air is transferred to the heat exchange fluid in the recovery pipeline 31. After the compressed air is cooled by heat exchange, it enters the next-stage air compressor for recompression. The re-compressed air passes through another first heat exchanger 24 for heat exchange. In this way, the compression heat in the compressed air compressed by multiple air compressors is transferred to the heat exchange fluid in the recovery pipeline 31. The heat exchange fluid exchanges heat with the heat storage element in the first heat storage tank 32, so that the compression heat generated during the operation of the air compression system can be more fully recovered and stored.

[0027] In this embodiment, the air compressor unit 22 is configured to be in the form of multi-stage compression, and a first heat exchanger 24 is provided at the outlet of each air compressor, so that the compressed air can first pass through the first heat exchanger 24 for heat exchange and cooling before entering the air compressor of the next stage. This can reduce the energy loss during the operation of the air compressor, so that the overall compression efficiency of the air compressor unit 22 is higher and the energy consumption is lower during the operation, and the operation efficiency of the second steam turbine 21 is higher. The compression heat during the operation of the air compressor unit 22 is recovered step by step through multiple first heat exchangers 24 and the compression heat recovery system 30, so that the heat recovery is more sufficient, so that the air compression system can cooperate with the compression heat recovery system 30 to more fully recover the energy of the extracted steam from the first steam turbine 11.

[0028] When the thermal power unit system is operating at a low load, the redundant steam in the first steam turbine 11 can be extracted to the second steam turbine 21 to drive the operation of the second steam turbine 21, so that the thermal energy and kinetic energy in the extracted steam can be transferred to the first heat storage tank 32 through the air compression system and the compression heat recovery system 30, so that the excess extracted steam energy during the operation of the thermal power unit system can be fully recovered. The thermal energy stored in the first heat storage tank 32 can be flexibly utilized in the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 as needed, so that the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is significantly improved.

[0029] In this embodiment, the liquid air energy storage system includes a cold box 41, an expansion refrigerator 42 and a gas-liquid separator 43 connected in sequence. The cold box 41 is connected to the outlet of the air compressor unit 22. The air is compressed by the air compressor unit 22 and flows into the cold box 41 after heat exchange and cooling through multiple first heat exchangers 24. The cold box 41 further cools the compressed air to reduce the temperature of the compressed air, so that the compressed air can be more stably liquefied to form liquid air after entering the expansion refrigerator 42, so that there is less gaseous air in the fluid flowing out of the expansion refrigerator 42. The gas-liquid separator 43 separates the gaseous air and liquid air therein, and the liquid air flows out from the liquid outlet of the gas-liquid separator 43 and flows into the liquid storage tank 44 for storage, so that the compressed air stores cold energy in the form of liquid air, and the energy storage density is high. For example, the stored cold energy can be To provide a cold source for the cooling operation of the cold box 41 or other cooling needs, the liquid air can be heated and vaporized using the compression heat stored in the first heat storage tank 32 and used for power generation and other purposes. For example, the liquid air can be pressurized after heating and can be used to drive the air expander to operate, so that the air expander can drive the generator to generate electricity, so that during the operation of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100, the air compression system, the compression heat recovery system 30 and the liquid air energy storage system can cooperate to fully recover and flexibly utilize the redundant heat energy generated by the thermal power unit system, which can well meet the energy storage and reuse needs in the peak-shaving scenario of the thermal power unit system, so that the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is higher and the operating cost is lower.

[0030] According to the embodiment of the present invention, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is provided with an air compression system, a compression heat recovery system 30 and a liquid air energy storage system. The air compression system is provided with an air compressor unit 22, and the air compressor unit 22 is provided with air compressors connected in sequence. The compression heat recovery system 30 is provided with a recovery pipeline 31 to recover the heat of the compressed air discharged after compression by each air compressor through the first heat exchanger 24 step by step and store it in the first heat storage tank 32. The liquid air energy storage system compresses the air. After being liquefied, the gas is stored in the liquid storage tank 44, so that the redundant heat energy of the thermal power unit system during low-load operation can be extracted to the second steam turbine 21, and stored in the first heat storage tank 32 and the liquid storage tank 44 in the form of heat energy and cold energy under the coordinated operation of the air compression system, the compression heat recovery system 30 and the liquid air energy storage system, so that the redundant heat energy of the thermal power unit can be fully recovered and used more flexibly, thereby greatly improving the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 and reducing the operating costs.

[0031] In some embodiments of the present invention, Figure 1As shown, the air compressor group 22 may include a first-stage compressor 221, a second-stage compressor 222 and a third-stage compressor 223 connected in sequence, and the air compression system also includes a first connecting pipeline 23, the first connecting pipeline 23 includes a first connecting pipe, a second connecting pipe and a third connecting pipe, the first connecting pipe is connected to the air outlet of the first-stage compressor 221 and the air inlet of the second-stage compressor 222, the second connecting pipe is connected to the air outlet of the second-stage compressor 222 and the air inlet of the third-stage compressor 223, the third connecting pipe is connected to the air outlet of the third-stage compressor 223 and the cold box 41, and the first heat exchanger 24 is respectively connected in series to the first connecting pipe, the second connecting pipe and the third connecting pipe.

[0032] In this embodiment, the air compressor unit 22 is provided with a first-stage compressor 221, a second-stage compressor 222 and a third-stage compressor 223 connected in sequence. The first connecting pipe 23 is provided with a first connecting pipe connecting the first-stage compressor 221 and the second-stage compressor 222, a second connecting pipe connecting the second-stage compressor 222 and the third-stage compressor 223, and a third connecting pipe connected to the air outlet of the third-stage compressor 223 and the cold box 41. The structure is simple and can well meet the flow requirements of the air compressed step by step in the air compressor unit 22. The first connecting pipe, the second connecting pipe and the third connecting pipe are respectively connected in series with the first heat exchanger 24, so that the recovery pipe 31 can recover the compression heat during the operation of the air compressor unit 22 in a cascade manner through the first connecting pipe, the second connecting pipe and the first heat exchanger 24 on the third connecting pipe, so that the compression heat during the operation of the air compressor unit 22 can be more fully recovered, thereby enabling the redundant heat energy of the thermal power unit system to be fully recovered and utilized during low-load operation.

[0033] Optionally, the flow direction of the air in the first connecting pipeline 23 is opposite to the flow direction of the heat exchange fluid in the recovery pipeline 31. This can improve the heat exchange efficiency of the first heat exchanger 24, enable the recovery pipeline 31 to more fully recover the compression heat in the compressed air, and make the temperature of the compressed air discharged from the air compressor unit 22 lower, so that the liquid air energy storage system can operate and store energy more efficiently, thereby making the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 higher.

[0034] In some embodiments of the present invention, Figure 1As shown, the liquid air energy storage system may further include: a second heat exchanger 45 and a second connecting pipeline 401, an air expansion unit 46, a generator and a heating pipeline 402, the second connecting pipeline 401 is connected to the liquid storage tank 44, the second heat exchanger 45 is connected in series to the second connecting pipeline 401, and the second heat exchanger 45 is configured to heat the fluid in the second connecting pipeline 401 to gasify the liquid air; the air expansion unit 46 is connected in series to the second connecting pipeline 401 and is located downstream of the second heat exchanger 45 in the direction of fluid flow in the second connecting pipeline 401, and the air expansion unit 46 is connected in series to the second connecting pipeline 401. The unit 46 includes a plurality of air expanders connected in sequence along the direction of fluid flow in the second connecting pipeline 401. The air expansion unit 46 is connected to the generator in a transmission manner, and a heater 47 is connected in series to the inlet of each air expander; a heating pipeline 402, one end of the heating pipeline 402 is connected to the exhaust port of the second steam turbine 21, and the thermal power unit system also includes a condenser 13. The other end of the heating pipeline 402 is connected to the condenser 13. The heater 47 is connected in series to the heating pipeline 402 so that the fluid in the heating pipeline 402 heats the fluid in the second connecting pipeline 401.

[0035] In this embodiment, the liquid air energy storage system also includes a second heat exchanger 45 and a second connecting pipeline 401. The second heat exchanger 45 and the air expansion unit 46 are connected in series to the second connecting pipeline 401. The second connecting pipeline 401 is connected to the liquid storage tank 44. The second heat exchanger 45 heats the fluid in the second connecting pipeline 401 to vaporize the liquid air. The generator is connected to the air expansion unit 46 in a transmission connection. When the air expansion unit 46 is operating, the liquid air in the liquid storage tank 44 can be heated and vaporized after passing through the second heat exchanger 45 along the second connecting pipeline 401, and then enter the air expander after being heated by the heater 47, thereby driving the air expander to operate and then driving the generator to generate electricity.

[0036] The heater 47 in this embodiment is connected in series between the heating pipeline 402 and the second connecting pipeline 401. One end of the heating pipeline 402 is connected to the exhaust port of the second steam turbine 21 and the other end is connected to the condenser 13 of the thermal power unit, so that the air in the second connecting pipeline 401 in the air expansion unit 46 can be heated by utilizing the exhaust waste heat of the second steam turbine 21. This can reduce the arrangement of additional heat sources and further recover and utilize the extraction heat energy from the thermal power unit, so that when the thermal power unit system is operating at low load, the redundant heat energy can be more fully recovered and utilized, so that the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is higher during operation.

[0037] The electric energy generated by the air expansion unit 46 driving the generator can be used to provide electric energy to other equipment as needed or stored to increase the output power when the thermal power unit system is operating at high load to more stably meet the power generation demand.

[0038] In this embodiment, the air expansion unit 46 includes a plurality of air expansion machines connected in sequence. The plurality of air expansion machines are connected in sequence along the flow direction of the fluid in the second connecting pipeline 401. The inlet of each air expansion machine is connected in series with a heater 47. When the air expansion unit 46 is in operation, the liquid air is heated and vaporized by the second heat exchanger 45 and then flows into the heater 47 for further heating, so that the air can drive the air expansion machine to operate efficiently after entering the air expansion machine. The air flowing out of the air expansion machine passes through another heater 47 along the second connecting pipeline 401 and is further heated before entering the next stage of the air expansion machine. In this way, the plurality of air expansion machines can be arranged in stages according to the temperature and pressure of the evaporating air in the second connecting pipeline 401, thereby adapting to the evaporating air temperature. The degree curve is used to realize expansion and power generation in stages, so that each air expander can operate efficiently, improve the efficiency of converting thermal energy into electrical energy, and enable the exhaust steam of the second steam turbine 21 to release latent heat in the process of gradually heating the air through heat exchange of multiple heaters 47, thereby fully recovering thermal energy. Finally, the exhaust steam of the second steam turbine 21 flows into the condenser 13 of the thermal power unit system, so that the extraction steam can circulate among the thermal power unit system, the air compression system, the compression heat recovery system 30 and the liquid air energy storage system, so that the liquid air energy storage and the thermal coupling of the thermal power unit and the various systems in the energy cascade utilization system 100 are more tightly coupled, the coordinated operation is more efficient and stable, and the extraction steam energy is maximized.

[0039] In one embodiment of the present invention, Figure 1 As shown, the air expansion unit 46 includes at least a first-stage expander 461, a second-stage expander 462 and a third-stage expander 463 connected in sequence, and the second connecting pipeline 401 may include: a fourth connecting pipe, a fifth connecting pipe and a sixth connecting pipe, the fourth connecting pipe is connected to the liquid storage tank 44 and the inlet of the first-stage expander 461, the fifth connecting pipe is connected to the outlet of the first-stage expander 461 and the inlet of the second-stage expander 462, and the sixth connecting pipe is connected to the outlet of the second-stage expander 462 and the inlet of the tertiary expander 463, wherein the heater 47 has a first heat exchange channel and a second heat exchange channel for mutual heat exchange, the first heat exchange channels of the multiple heaters 47 are all connected in series to the heating pipeline 402, and the second heat exchange channels of the multiple heaters 47 are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe and the sixth connecting pipe.

[0040] In this embodiment, the air expansion unit 46 includes at least a first-stage expansion machine 461, a second-stage expansion machine 462 and a third-stage expansion machine 463 connected in sequence. That is, the air expansion unit 46 is provided with at least three air expansion machines. The air expansion unit 46 can be provided with four, five, etc. air expansion machines as needed, and the number of heaters 47 can be the same as the number of air expansion machines.

[0041] The second connecting pipe 401 includes a fourth connecting pipe, a fifth connecting pipe and a sixth connecting pipe. The fourth connecting pipe connects the inlet of the first-stage expander 461 and the liquid storage tank 44, the fifth connecting pipe connects the first-stage expander 461 and the second-stage expander 462, and the sixth connecting pipe connects the second-stage expander 462 and the third-stage expander 463. The structure is simple and can meet the flow needs of air in the air expansion unit 46.

[0042] The heater 47 is provided with a first heat exchange channel and a second heat exchange channel for mutual heat exchange. The first heat exchange channel is connected in series to the heating pipeline 402, and the second heat exchange channel is connected in series to the second connecting pipeline 401. The structure is simple and can well meet the heat exchange needs of the air in the second connecting pipeline 401 and the exhaust steam in the heating pipeline 402.

[0043] In one embodiment of the present invention, Figure 1 As shown, the heating pipeline 402 may include: a main heating pipe and multiple branch pipes, the two ends of the main heating pipe are respectively connected to the exhaust port of the second steam turbine 21 and the condenser 13, the two ends of the branch pipe are respectively connected to the main heating pipe, and the heater 47 is connected in series on the branch pipe.

[0044] In this embodiment, the heating pipeline 402 is provided with a main heating pipe, and the two ends of the main heating pipe are respectively connected to the exhaust port of the second steam turbine 21 and the condenser 13. The branch pipe is connected in series with the heater 47 and the two ends are respectively connected to the main heating pipe. The first heat exchange channel of the heater 47 is connected in series to the branch pipe. When the second steam turbine 21 is exhausted, the exhaust steam of the second steam turbine 21 can flow along the main heating pipe in sequence through the first heat exchange channels on multiple branch pipes as needed to heat the air in the second connecting pipe at multiple heaters 47. After the exhaust steam heats the air, it flows back to the condenser 13 of the thermal power unit system along the main heating pipe. The exhaust steam of the second steam turbine 21 can also flow directly back to the condenser 13 along the main heating pipe, thereby making the operation of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 more flexible.

[0045] For example, during the operation of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100, when the air compression system and the liquid energy storage system cooperate to recover and store compression heat and store liquid air in the liquid storage tank 44, the air expansion unit 46 can be operated or kept on standby as needed. When the air expansion unit 46 is running, the exhaust steam of the second steam turbine 21 flows through the branch pipe to provide a heat source. When the air expansion unit 46 is on standby, the exhaust steam of the second steam turbine 21 can flow directly along the main heating pipe back to the condenser 13, so that the heater 47 can maintain a stable structural state, and the exhaust steam flowing to the condenser 13 can have a higher temperature, which can play a certain heating role on the condensate in the condenser 13, so that the thermal power unit system can operate more efficiently.

[0046] In one embodiment of the present invention, Figure 1 As shown, the second heat exchanger 45 can have a first heat exchange channel and a second heat exchange channel for mutual heat exchange, and the second heat exchange channel is connected in series to the second connecting pipeline 401. The liquid air energy storage system also includes a first heat exchange pipeline 403 and a cold storage box 48. The first heat exchange pipeline 403 is connected in series with the cold box 41, the first heat exchange channel and the cold storage box 48. The cold storage box 48 is located downstream of the first heat exchange channel in the first heat exchange pipeline 403 in the direction of fluid flow, and the cold storage box 48 is configured to provide cold energy to the cold box 41.

[0047] In this embodiment, the second heat exchanger 45 has a first heat exchange channel and a second heat exchange channel for mutual heat exchange. The liquid air energy storage system also includes a first heat exchange pipeline 403 and a cold storage box 48. The cold box 41, the first heat exchange channel and the cold storage box 48 are connected in series on the first heat exchange pipeline 403. Specifically, a cold storage component can be provided in the cold storage box 48. The second heat exchange channel is connected in series on the second connecting pipeline 401, so that the heat exchange fluid in the first heat exchange pipeline 403 can be connected to the second connecting pipeline 401 at the second heat exchanger 45. The liquid air in the first heat exchange pipe 403 is heat exchanged, so that the liquid air can cool the heat exchange fluid in the first heat exchange pipe 403. The cooled heat exchange fluid can flow to the cold box 41 to exchange heat with the compressed air in the first connecting pipe 23, thereby cooling the compressed air. After the heat exchange fluid passes through the cold box 41, the temperature rises and flows to the second heat exchanger 45. In this way, the liquid air can provide a cold source for the cold box 41, avoiding the setting of an additional cold source, making the energy utilization efficiency of the air compression system and the liquid air energy storage system higher during operation. In this embodiment, the first heat exchange pipe 403 is connected in series with the cold storage box 48. When the cold amount in the first heat exchange pipe 403 is large, it can be stored in the cold storage box 48, or when the cold amount in the first heat exchange pipe 403 is insufficient, the cold amount can be released, thereby making the cold energy utilization of the liquid air energy storage system more flexible and the operation more stable during operation, and the overall efficiency higher, thereby making the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 higher during operation.

[0048] In some examples of the present invention, Figure 1 As shown, the cold box 41 can have a third heat exchange channel, a fourth heat exchange channel and a fifth heat exchange channel for mutual heat exchange, the air compression system also includes a first connecting pipeline 23, the first connecting pipeline 23 is connected in series with multiple air compressors in sequence, the fourth heat exchange channel is connected in series to the first connecting pipeline 23, the fifth heat exchange channel is connected in series to the first heat exchange pipeline 403, the air compression system also includes a return air pipe 404, the return air pipe 404 is connected to the air outlet of the gas-liquid separator 43 and the air inlet of the air compressor group 22, and the third heat exchange channel is connected in series to the return air pipe 404.

[0049] In this embodiment, the cold box 41 has a third heat exchange channel, a fourth heat exchange channel and a fifth heat exchange channel for heat exchange. The first heat exchange channel is connected in series to the first connecting pipe 23, and the fifth heat exchange channel is connected in series to the first heat exchange pipe 403. The structure is simple and can well meet the cooling needs of the cold box 41 for compressed air.

[0050] In this embodiment, the air compression system is also provided with a return air pipe 404, which is connected to the air outlet of the gas-liquid separator 43 and the air inlet of the air compressor unit 22. The third heat exchange channel is connected in series to the return air pipe 404. The gaseous air separated by the gas-liquid separator 43 can flow through the cold box 41 along the return pipe. Since the temperature of the gaseous air flowing out of the gas-liquid separator 43 is relatively low, the air in the return pipe can be used as a cold source for the cold box 41 to cool the compressed air in the fourth heat exchange channel, thereby cooperating with the heat exchange fluid in the first heat exchange pipe to cool the compressed air, so that the cooling effect of the cold box 41 is better and the efficiency is higher. At the same time, the cold box 41 uses the gaseous air flowing out of the gas-liquid separator 43 for cooling operations, so that the cold energy can be more fully recovered and utilized, thereby making the energy utilization efficiency of the liquid air energy storage system higher, and making the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 higher during operation.

[0051] The return air pipe 404 is connected to the air inlet of the air compressor unit 22, so that the gaseous air flowing out of the gas-liquid separator 43 can be mixed with the air entering the air compressor unit 22 and then enter the air compressor unit 22, thereby making the temperature of the air entering the air compressor unit 22 lower, thereby further improving the operating efficiency of the air compressor unit 22 to a certain extent, and making more full use of the cold energy of the air in the return pipe, thereby better improving the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100.

[0052] In one embodiment of the present invention, Figure 1 As shown, the thermal power unit system can also include a boiler 12, which is provided with a smoke exhaust pipeline 121. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 also includes a flue gas waste heat utilization system 50, which includes: a second heat storage tank 52, a second heat exchange pipeline 51 and a three-way valve 53.

[0053] Specifically, the second heat storage tank 52 is provided in the smoke exhaust pipeline 121; the second heat exchange pipeline 51 is switchably connected to the first heat storage tank 32 and the second heat storage tank 52 through a three-way valve 53, and the second heat exchanger 45 has a second heat exchange flow channel and a third heat exchange flow channel for mutual heat exchange, the second heat exchange flow channel is connected in series to the second connecting pipeline 401, and the third heat exchange flow channel is connected in series to the second heat exchange pipeline 51.

[0054] In this embodiment, the thermal power unit system is equipped with a boiler 12 to meet the operational needs of the thermal power unit. The boiler 12 is equipped with a flue gas exhaust pipe 121. The flue gas waste heat utilization system 50 is equipped with a second heat storage tank 52. The second heat storage tank 52 is located in the flue gas exhaust pipe 121. The second heat storage tank 52 has a simple structure and can recover and store heat from the boiler 12 exhaust, thereby reducing heat energy waste and improving the energy utilization efficiency of the thermal power unit system. The second heat exchange pipe 51 is switchably connected to the first heat storage tank 32 and the second heat storage tank 52 via a three-way valve 53. The third heat exchange channel of the second heat exchanger 45 is connected in series with the second heat exchange pipe 51. When the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 are in operation, the second heat exchange pipe 51 can be connected to the first heat storage tank 32 or the second heat storage tank 52 as needed.

[0055] For example, when the second heat exchange pipeline 51 is connected to the first heat storage tank 32, the heat exchange fluid in the second heat exchange pipeline 51 flows along the second heat exchange pipeline 51 to the third heat exchange channel of the second heat exchanger 45 after the heat exchange in the first heat storage tank 32 is heated, thereby heating the liquid air in the second heat exchange channel, so that the first heat storage tank 32 can use the recovered and stored compression heat to provide a heat source for heating the liquid air. When the second heat exchange pipeline 51 is connected to the second heat storage tank 52, the second heat storage tank 52 can use the recovered and stored exhaust heat to provide a heat source for heating the liquid air, thereby making the first heat storage tank 32 and the second heat storage tank The utilization of the recovered and stored heat energy in 52 is more flexible. For example, the three-way valve 53 can dynamically adjust the heat supply path of the second heat exchange pipeline 51 to the second heat exchanger 45 according to the operating status of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100, the heat storage status in the first heat storage tank 32 and the second heat storage tank 52, or the load regulation requirements of the thermal power unit system, so that the compression heat in the first heat storage tank 32 and the exhaust heat in the second heat storage tank 52 can complement each other to provide heat, thereby making the operation of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 more flexible and efficient.

[0056] In one embodiment of the present invention, Figure 1 As shown, the liquid air energy storage system may further include a pressure pump 49 , which is disposed in the second connecting pipe and located between the liquid storage tank 44 and the second heat exchanger 45 .

[0057] In this embodiment, a pressure pump 49 is provided on the second connecting pipe. Positioned between the liquid storage tank 44 and the second heat exchanger 45, the pressure pump 49 has a simple structure. It pressurizes the liquid air and drives it toward the second heat exchanger 45. This ensures that the heated and vaporized liquid air has sufficient pressure, enabling the air expander to operate efficiently, thereby increasing the efficiency of the liquid air energy storage system. Optionally, the pressure pump 49 is a cryogenic pump.

[0058] In some embodiments of the present invention, Figure 1 As shown, the first steam turbine 11 may include an intermediate pressure cylinder 112, the intermediate pressure cylinder 112 is provided with a steam extraction port, the second steam turbine 21 is connected to the steam extraction port, and the steam extraction pressure of the steam extraction port is greater than or equal to 1 MPa and less than or equal to 3.5 MPa.

[0059] In this embodiment, the medium-pressure dry of the first steam turbine 11 is provided with a steam extraction port, and the second steam turbine 21 is connected to the steam extraction port to meet the operation needs of the air compression system. The steam extraction pressure of the steam extraction port refers to the steam pressure extracted from the steam extraction port. The steam extraction pressure is set to be greater than or equal to 1Mpa and less than or equal to 3.5Mpa. For example, the steam extraction pressure of the steam extraction port can be 1Mpa, 1.2Mpa, 1.5Mpa, 2Mpa, 2.5Mpa, 2.7Mpa, 3Mpa, etc.

[0060] In this embodiment, the steam extraction pressure at the steam extraction port is set to be greater than or equal to 1 MPa and less than or equal to 3.5 MPa. This ensures that the steam pressure entering the second steam turbine 21 is more suitable, allowing the second steam turbine 21 to operate efficiently. For example, the air compression system can be equipped with a steam extraction pipe connected to the steam extraction port and the steam inlet of the second steam turbine 21. The amount of steam extracted from the first steam turbine 11 to the second steam turbine 21 can be automatically adjusted based on the load of the air compressor unit 22, thereby ensuring stable operation of the first steam turbine 11 of the thermal power system.

[0061] The following will refer to Figure 1 A liquid air energy storage and thermal power generation unit thermal coupling and energy cascade utilization system 100 according to a specific embodiment of the present invention is described.

[0062] like Figure 1 As shown, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 includes a thermal power unit system, an air compression system, a compression heat recovery system 30, a liquid air energy storage system and a flue gas waste heat utilization system 50.

[0063] The thermal power unit system includes a boiler 12, a first steam turbine 11, a condenser 13, a condensate pump, a low-pressure heater 47, a deaerator, a feed water pump and a high-pressure heater 47. The boiler 12 is provided with a smoke exhaust pipeline 121. The condenser 13 and the condensate pump, the low-pressure heater 47, the deaerator, the feed water pump and the high-pressure heater 47 are arranged in sequence on the condensate pipeline. The condensate pipeline is connected to the exhaust port of the first steam turbine 11. The first steam turbine 11 includes a high-pressure cylinder 111, an intermediate-pressure cylinder 112 and a low-pressure cylinder 113. The intermediate-pressure cylinder 112 is provided with a steam extraction port.

[0064] The air compression system includes a second steam turbine 21, an air compressor unit 22, a first heat exchanger 24 and a first connecting pipeline 23. The second steam turbine 21 is connected to the steam extraction port of the intermediate pressure cylinder 112 through a steam extraction pipe. The second steam turbine 21 is transmission-connected to the air compressor unit 22. The air compressor unit 22 includes a first-stage compressor 221, a second-stage compressor 222 and a third-stage compressor 223 connected in sequence through the first connecting pipeline 23. There are three first heat exchangers 24. The three first heat exchangers 24 are respectively connected in series to the first connecting pipeline 23 and are located at the outlet of each air compressor.

[0065] The compression heat recovery system 30 includes a first heat storage tank 32 and a recovery pipeline 31. The recovery pipeline 31 is connected in series with the three first heat exchangers 24 for heat exchange. The first heat storage tank 32 is provided with a heat storage element. The first heat storage tank 32 is connected in series to the recovery pipeline 31 and is located downstream of the three first heat exchangers 24 in the flow direction of the heat exchange fluid in the recovery pipeline 31. The recovery pipeline 31 is provided with a circulation pump to drive the heat exchange fluid to flow in the recovery pipeline 31.

[0066] The liquid air energy storage system includes a cold box 41, an expansion refrigerator 42, a gas-liquid separator 43, a liquid storage tank 44, a return air pipe 404, a second heat exchanger 45, a second connecting pipeline 401, an air expansion unit 46, a generator, a heater 47, a heating pipeline 402, a first heat exchange pipeline 403, a cold storage box 48 and a booster pump 49. The cold box 41 is connected in series to the first connecting pipeline 23, the return air pipe 404 and the first heat exchange pipeline 403. The expansion refrigerator 42 is connected in series to the first connecting pipeline 23 and is located downstream of the cold box 41. The first connecting pipeline 23 is connected to the gas-liquid separator 43. The two ends of the return air pipe 404 are respectively connected to the air inlet of the first-stage compressor 221 and the air outlet of the gas-liquid separator 43. The liquid storage tank 44 is connected to the liquid outlet of the gas-liquid separator 43 through a pipeline.

[0067] The second heat exchanger 45 is connected in series to the first heat exchange pipeline 403 and the second connecting pipeline 401. The second connecting pipeline 401 is connected to the liquid storage tank 44. The air expansion unit 46 includes a first-stage expander 461, a second-stage expander 462 and a third-stage expander 463 which are connected in sequence through the second connecting pipeline 401. There are three heaters 47 and they are respectively connected in series to the inlets of the first-stage expander 461, the second-stage expander 462 and the third-stage expander 463. One end of the heating pipeline 402 is connected to the exhaust port of the second steam turbine 21 and the other end is connected to the condenser 13. The three heaters 47 are connected in series to the heating pipeline 402.

[0068] The cold storage tank 48 is connected in series to the first heat exchange pipeline 403. A circulating pump is provided on the first heat exchange pipeline 403 to drive the heat exchange fluid to circulate in the first heat exchange pipeline 403. The booster pump 49 is a cryogenic pump. The booster pump 49 is provided in the second connecting pipeline 401 and is located between the second heat exchanger 45 and the liquid storage tank 44. The generator is connected to the air expansion unit 46 by transmission.

[0069] The flue gas waste heat utilization system 50 includes a second heat storage tank 52, a second heat exchange pipeline 51 and a three-way valve 53. The second heat storage tank 52 is arranged in the exhaust pipeline 121 and is connected in series to the second heat exchange pipeline 51. The first heat storage tank 32 is connected in series to the second heat exchange pipeline 51. Specifically, the second heat exchange pipeline 51 may include a first pipe, a second pipe and a main pipe. The first pipe, the second pipe and the main pipe are connected through the three-way valve 53. The first pipe is connected in series with the first heat storage tank 32, the second pipe is connected in series with the second heat storage tank 52, and the main pipe is connected in series with the second heat exchanger 45. The exhaust pipeline 121 may be provided with a flue gas heat exchange pump to drive the flue gas to be discharged to the second heat storage tank 52.

[0070] In this embodiment, a thermal power generation unit system, an air compression system, a compression heat recovery system 30, a liquid air energy storage system and a flue gas waste heat utilization system 50 are provided. The second steam turbine 21 of the air compression system utilizes the extraction steam of the first steam turbine 11 in the thermal power generation unit system to operate. The liquid air energy storage system utilizes the exhaust steam waste heat of the second steam turbine 21 to heat the liquid air so that the air drives the expansion unit to operate. The flue gas waste heat utilization system 50 utilizes the compression heat and exhaust waste heat stored in the first heat storage tank 32 and the second heat storage tank 52 to heat the liquid air as needed. , the liquid air energy storage system and the flue gas waste heat utilization system 50 are tightly coupled, so that the thermal coupling of the liquid air energy storage and the thermal power unit and the energy cascade utilization system 100 are better integrated. When the power system load is low, the thermal power unit system operates at low load, and the air compression system cooperates with the compression heat recovery system 30, the liquid air energy storage system and the flue gas waste heat utilization system 50 to store the redundant heat energy of the thermal power unit system in the first heat storage tank 32, the second heat storage tank 52, the liquid storage tank 44 and the cold storage tank 48 in the form of multiple energy sources. When the power grid load is peak, the operation of the expansion unit can be used to drive the generator to generate electricity, thereby utilizing the recovered stored energy.

[0071] For example, when the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is in a low load valley of the power grid or an excess output stage of the thermal power unit, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 can enter the energy storage stage, and the steam extracted from the steam extraction port of the intermediate pressure cylinder 112 drives the second steam turbine 21 to operate, driving the multi-stage air compressor to compress the air step by step. At the same time, the outlet of each air compressor recovers the compression heat step by step through the first heat exchanger 24 and the recovery pipeline 31, and the recovered compression heat is stored in the first heat storage tank 32. The compressed air is liquefied under the action of the cold box 41 and the expansion refrigerator 42, and the liquefied air is stored in the liquid storage tank 44. The cold energy is stored in the cold storage tank 48 through the first heat exchange pipeline 403 and the second heat exchanger 45, and the exhaust waste heat in the exhaust pipeline 121 is stored in the second heat storage tank 52.

[0072] When the load on the power grid increases or the electricity price increases, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 can enter the energy release stage. After the liquid air is pressurized by the cryogenic pump, it is heated in the second heat exchanger 45 using the heat energy stored in the first heat storage tank 32 or the second heat storage tank 52, and then heated in the heater 47 using the exhaust steam of the second steam turbine 21 to evaporate into high-pressure gas. The high-pressure gas is expanded and works in sequence through the multi-stage air expander to realize energy release. Multiple heaters 47 heat the low-enthalpy steam after each air expander works, thereby forming a three-stage heat source combined heating mechanism. The three-way valve 53 is opened. By switching the first heat storage tank 32 and the second heat storage tank 52 to heat the liquid air, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 can flexibly respond to changes in different loads, electricity prices and operating conditions, so that the heat source continuity and adaptability of the second heat exchanger 45 are well guaranteed. Therefore, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 of this embodiment adopts the method of low-valley steam extraction to drive compression and peak-peak expansion to generate electricity and release energy to achieve the integrated fusion of energy storage, power generation and flexible peak-shaving functions of thermal power, thereby improving the grid regulation capability and the operating efficiency of the thermal power unit system.

[0073] In this embodiment, the extraction steam from the intermediate pressure cylinder 112 is used to drive the second steam turbine 21, and the recovered compression heat and exhaust gas waste heat are alternately used for evaporation heating of liquid air. The compression heat is recovered in stages through the multi-stage compression of the air compressor unit 22, and the multi-stage air expanders of the expansion unit are used to sequentially expand and perform work. The exhaust steam of the second steam turbine 21 and multiple heaters 47 are used for multi-stage waste heat utilization. The liquid air in the process of compressed air liquefaction and the gaseous air discharged from the gas-liquid separator 43 are reused as cold sources, so that the redundant heat energy of the thermal power unit system is fully recovered and utilized, forming a complete energy closed loop. The dependence on external electric energy is effectively reduced, so that in the thermal coupling and energy cascade utilization system 100 of liquid air energy storage and thermal power units, the thermal power unit system and the air compression system, the compression heat recovery system 30, the liquid air heat storage system and the flue gas waste heat utilization system 50 form a deep coupling relationship in terms of power drive, heat source supply and cold energy recovery and utilization, so that the overall efficiency of the operation of the thermal coupling and energy cascade utilization system 100 of liquid air energy storage and thermal power units is higher and the adjustment is more flexible, so that the overall energy efficiency of the operation of the thermal coupling and energy cascade utilization system 100 of liquid air energy storage and thermal power units is higher and the operating cost is lower. The thermal coupling and energy cascade utilization system 100 of liquid air energy storage and thermal power units of the present application is flexible in operation. The heat source path of the second heat exchanger 45 is dynamically adjusted by the three-way valve 53, so that the liquid air energy storage system can better adapt to different operating states, so that the thermal coupling and energy cascade utilization system 100 of liquid air energy storage and thermal power units can better meet the use needs of thermal power peak regulation scenarios.

[0074] This embodiment constructs a coupling mechanism for compression heat recovery, exhaust heat recovery, steam extraction drive and exhaust heat cascade release, so that the thermal power unit can operate efficiently in coordination with the air compression system, compression heat recovery system 30, etc. without reducing the output, so that the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 can operate more efficiently.

[0075] In this embodiment, an air compression system, a compression heat recovery system 30, and a liquid air energy storage system are provided. The air compression system is provided with an air compressor unit 22, and the air compressor unit 22 is provided with air compressors connected in sequence. The compression heat recovery system 30 is provided with a recovery pipeline 31 to recover the heat of the compressed air discharged after compression by each air compressor through the first heat exchanger 24 step by step and store it in the first heat storage tank 32. The liquid air energy storage system liquefies the compressed air and stores it in the liquid storage tank 44. The redundant heat energy of the thermal power unit system during low-load operation can be extracted to the second steam turbine 21. Under the coordinated operation of the air compression system, the compression heat recovery system 30, and the liquid air energy storage system, the redundant heat energy of the thermal power unit is stored in the first heat storage tank 32 and the liquid storage tank 44 in the form of heat energy and cold energy, respectively. The redundant heat energy of the thermal power unit is fully recovered and used more flexibly, thereby greatly improving the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 and reducing the operating cost.

[0076] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0077] 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 the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0078] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0079] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations 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 any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0080] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to the embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the claims and their equivalents.

Claims

1. A system for thermal coupling of liquid air energy storage and thermal power generation units and energy cascade utilization, characterized in that: include: A thermal power generation unit system, the thermal power generation unit system comprising a first steam turbine (11); An air compression system comprises: a second steam turbine (21) and an air compressor unit (22), wherein the second steam turbine (21) is configured to utilize extraction steam from the first steam turbine (11) to drive the air compressor unit (22) to operate, wherein the air compressor unit (22) comprises a plurality of air compressors connected in sequence, and outlets of the air compressors are each connected in series with a first heat exchanger (24); A compression heat recovery system (30) comprises: a first heat storage tank (32) and a recovery pipeline (31); the first heat storage tank (32) is arranged in the recovery pipeline (31); the first heat exchanger (24) is connected in series to the recovery pipeline (31) so that the fluid in the recovery pipeline (31) exchanges heat with the compressed air; the first heat storage tank (32) is located downstream of the first heat exchangers (24) in the fluid flow direction in the recovery pipeline (31); and a heat storage element is provided in the first heat storage tank (32); A liquid air energy storage system comprises: a cold box (41), an expansion refrigerator (42), a gas-liquid separator (43) and a liquid storage tank (44); the cold box (41), the expansion refrigerator (42) and the gas-liquid separator (43) are connected in sequence; the cold box (41) is connected to the outlet of the air compressor unit (22); the liquid storage tank (44) is connected to the liquid outlet of the gas-liquid separator (43); and the cold box (41) is configured to cool compressed air.

2. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 1 is characterized in that: The air compressor group (22) includes a first-stage compressor (221), a second-stage compressor (222), and a third-stage compressor (223) connected in sequence. The air compression system also includes a first connecting pipeline (23). The first connecting pipeline (23) includes a first connecting pipe, a second connecting pipe, and a third connecting pipe. The first connecting pipe is connected to the air outlet of the first-stage compressor (221) and the air inlet of the second-stage compressor (222). The second connecting pipe is connected to the air outlet of the second-stage compressor (222) and the air inlet of the third-stage compressor (223). The third connecting pipe is connected to the air outlet of the third-stage compressor (223) and the cold box (41). The first connecting pipe, the second connecting pipe, and the third connecting pipe are respectively connected in series with the first heat exchanger (24).

3. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 1 is characterized in that: The liquid air energy storage system further includes: a second heat exchanger (45) and a second connecting pipeline (401), wherein the second connecting pipeline (401) is connected to the liquid storage tank (44), the second heat exchanger (45) is connected in series to the second connecting pipeline (401), and the second heat exchanger (45) is configured to heat the fluid in the second connecting pipeline (401) to gasify the liquid air; An air expansion unit (46) and a generator, wherein the air expansion unit (46) is connected in series to the second connecting pipeline (401) and is located downstream of the second heat exchanger (45) in the direction of fluid flow in the second connecting pipeline (401), the air expansion unit (46) comprising a plurality of air expanders connected in sequence along the direction of fluid flow in the second connecting pipeline (401), the air expansion unit (46) being transmission-connected to the generator, and the inlets of the air expanders are all connected in series with heaters (47); A heating pipeline (402), one end of which is connected to the exhaust port of the second steam turbine (21), the thermal power unit system further comprising a condenser (13), the other end of which is connected to the condenser (13), the heater (47) being connected in series to the heating pipeline (402) so that the fluid in the heating pipeline (402) heats the fluid in the second connecting pipeline (401).

4. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 3 is characterized in that: The air expansion unit (46) includes at least a first-stage expansion machine (461), a second-stage expansion machine (462), and a third-stage expansion machine (463) connected in sequence. The second connecting pipeline (401) includes: a fourth connecting pipe, a fifth connecting pipe, and a sixth connecting pipe. The fourth connecting pipe is connected to the liquid storage tank (44) and the inlet of the first-stage expansion machine (461). The fifth connecting pipe is connected to the outlet of the first-stage expansion machine (461) and the inlet of the second-stage expansion machine (462). The sixth connecting pipe is connected to the outlet of the second-stage expansion machine (462) and the inlet of the third-stage expansion machine (463). The heater (47) has a first heat exchange channel and a second heat exchange channel for mutual heat exchange. The first heat exchange channels of the plurality of heaters (47) are all connected in series to the heating pipeline (402). The second heat exchange channels of the plurality of heaters (47) are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe, and the sixth connecting pipe.

5. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 3 is characterized in that: The heating pipeline (402) includes: a main heating pipe and multiple branch pipes, the two ends of the main heating pipe are respectively connected to the exhaust port of the second steam turbine (21) and the condenser (13), the two ends of the branch pipes are respectively connected to the main heating pipe, and the heater (47) is connected in series to the branch pipes.

6. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 3 is characterized in that: The second heat exchanger (45) has a first heat exchange channel and a second heat exchange channel for mutual heat exchange, the second heat exchange channel is connected in series to the second connecting pipeline (401), the liquid air energy storage system further comprises a first heat exchange pipeline (403) and a cold storage tank (48), the first heat exchange pipeline (403) is connected in series to the cold box (41), the first heat exchange channel and the cold storage tank (48), the cold storage tank (48) is located downstream of the first heat exchange channel in the direction of fluid flow in the first heat exchange pipeline (403), and the cold storage tank (48) is configured to provide cold energy to the cold box (41).

7. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 6 is characterized in that: The cold box (41) has a third heat exchange channel, a fourth heat exchange channel and a fifth heat exchange channel for mutual heat exchange. The air compression system also includes a first connecting pipeline (23), the first connecting pipeline (23) is serially connected to multiple air compressors, the fourth heat exchange channel is serially connected to the first connecting pipeline (23), and the fifth heat exchange channel is serially connected to the first heat exchange pipeline (403). The air compression system also includes a return air pipe (404), the return air pipe (404) is connected to the air outlet of the gas-liquid separator (43) and the air inlet of the air compressor unit (22), and the third heat exchange channel is serially connected to the return air pipe (404).

8. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 3 is characterized in that: The thermal power unit system further comprises a boiler (12), wherein the boiler (12) is provided with a smoke exhaust pipe (121), and the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system further comprises a flue gas waste heat utilization system (50), wherein the flue gas waste heat utilization system (50) comprises: A second heat storage tank (52), the second heat storage tank (52) being arranged on the smoke exhaust pipeline (121); A second heat exchange pipeline (51) and a three-way valve (53); the second heat exchange pipeline (51) is switchably connected to the first heat storage tank (32) and the second heat storage tank (52) through the three-way valve (53); the second heat exchanger (45) has a second heat exchange flow channel and a third heat exchange flow channel for mutual heat exchange; the second heat exchange flow channel is serially connected to the second connecting pipeline (401); and the third heat exchange flow channel is serially connected to the second heat exchange pipeline (51).

9. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to claim 3 is characterized in that: The liquid air energy storage system further comprises a pressure pump (49), which is provided in the second connecting pipe and is located between the liquid storage tank (44) and the second heat exchanger (45).

10. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system according to any one of claims 1 to 8, characterized in that: The first steam turbine (11) includes an intermediate pressure cylinder (112), the intermediate pressure cylinder (112) is provided with a steam extraction port, the second steam turbine (21) is connected to the steam extraction port, and the steam extraction pressure of the steam extraction port is greater than or equal to 1 MPa and less than or equal to 3.5 MPa.

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