Liquid air energy storage and thermal coupling with thermal power unit and energy cascade utilization system

Abstract

The application discloses a kind of liquid air energy storage and thermal coupling and energy cascade utilization system of thermal power generating unit, comprising: thermal power generating unit system;In air compression system, second steam turbine is configured to drive air compressor set operation using the extraction steam of first steam turbine, air compressor set includes multiple air compressors connected in turn, and the outlet of air compressor is all connected with first heat exchanger in series;In compressed heat recovery system, first heat storage tank is arranged in recovery pipeline, and first heat exchanger is connected in series in recovery pipeline;Cold box, expansion refrigerator and gas-liquid separator in liquid air energy storage system are connected in turn, cold box is connected with the outlet of air compressor set, and liquid storage tank is connected with the liquid outlet of gas-liquid separator.The liquid air energy storage and thermal coupling and energy cascade utilization system of thermal power generating unit according to the application can make the redundant thermal energy of thermal power generating unit be fully recovered, so that the overall energy efficiency of the system is well improved and the operation cost is reduced.

Description

Technical Field

[0001] This invention relates to the field of energy storage and thermal power generation technology, and in particular to a liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization. Background Technology

[0002] With the integration of a high proportion of renewable energy into the new power system, the volatility and uncertainty of power load have significantly increased, highlighting the growing demand for regulation and flexibility on the power supply side. Coal-fired power units, as baseload power sources, continue to play an irreplaceable role in ensuring the safe and stable operation of the power grid. However, traditional coal-fired power units suffer from insufficient peak-shaving capacity, limited minimum output, and significant equipment wear and tear due to frequent start-ups and shutdowns, severely restricting their role in flexible regulation.

[0003] In related technologies, thermal power units are combined with liquid air energy storage for collaborative operation. This allows thermal power units to 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 thermal power units, resulting in low utilization rate, low overall energy efficiency of the cogeneration system, and high operating costs. Summary of the Invention

[0004] This invention is based on the inventors' findings regarding the following facts and problems:

[0005] Thermal power units in power systems have a large amount of redundant thermal energy during low load or off-grid standby periods, such as steam extraction from the intermediate-pressure cylinder of the steam turbine. In related technologies, when thermal power units are coupled with liquid air energy storage, the energy recovery and utilization of the extracted steam is insufficient, resulting in low overall energy efficiency and high operating costs for the coupled system.

[0006] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system. This system can fully recover redundant heat energy, thereby significantly improving the overall energy efficiency of the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system and reducing operating costs.

[0007] The liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization according to the present invention includes: a thermal power unit system, the thermal power unit system including a first steam turbine; an air compression system including: a second steam turbine and an air compressor unit, the second steam turbine being configured to drive the air compressor unit to operate using the extracted steam from the first steam turbine, the air compressor unit including a plurality of air compressors connected in sequence, the outlet of each air compressor being equipped with a first heat exchanger in series; and a compression heat recovery system including: a first heat storage tank and a recovery pipeline, the first heat storage tank being located in the recovery pipeline. The first heat exchanger is connected in series with the recovery pipeline to exchange heat between the fluid in the recovery pipeline and the compressed air. The first heat storage box is located downstream of the plurality of first heat exchangers in the fluid flow direction in the recovery pipeline. The first heat storage box 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. 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.

[0008] According to the liquid air energy storage and 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 set up. The air compression system is equipped with an air compressor unit, which is equipped with air compressors connected in sequence. The compression heat recovery system is equipped with a recovery pipeline that recovers the heat of the compressed air discharged after compression by each air compressor through a first heat exchanger and stores 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. The redundant heat energy of the thermal power unit system during low-load operation can be extracted to the second steam turbine. With the coordinated operation of the air compression system, the compression heat recovery system, and the liquid air energy storage system, it is stored in the first heat storage tank and the liquid storage tank in the form of heat energy and cold energy, respectively. This allows the redundant heat energy of the thermal power unit to be fully recovered and utilized more flexibly, thereby greatly improving the overall energy efficiency of the liquid air energy storage and thermal coupling and energy cascade utilization system and reducing operating costs.

[0009] In some embodiments of the present invention, the air compressor unit includes a primary compressor, a secondary compressor, and a tertiary compressor connected in sequence. The air compression system further includes a first connecting pipe, which includes a first connecting pipe, a second connecting pipe, and a third connecting pipe. The first connecting pipe is connected to the outlet of the primary compressor and the inlet of the secondary compressor. The second connecting pipe is connected to the outlet of the secondary compressor and the inlet of the tertiary compressor. The third connecting pipe is connected to the outlet of the tertiary compressor and the cold box. The first heat exchanger is connected in series on the first connecting pipe, the second connecting pipe, and the third connecting pipe.

[0010] 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 with 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 expander unit and a generator, the air expander unit being connected in series with the second connecting pipeline and located downstream of the second heat exchanger in the direction of fluid flow in the second connecting pipeline, the air expander unit including a plurality of air expanders connected sequentially along the direction of fluid flow in the second connecting pipeline, the air expander unit being drivenly connected to the generator, and a heater being connected in series at the inlet of each air expander; 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, and a heater being connected in series with the heating pipeline to heat the fluid in the second connecting pipeline with the fluid in the heating pipeline.

[0011] In one embodiment of the present invention, the air expander unit includes at least a primary expander, a secondary expander, and a tertiary expander connected in sequence. 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 primary expander. The fifth connecting pipe is connected to the outlet of the primary expander and the inlet of the secondary expander. The sixth connecting pipe is connected to the outlet of the secondary expander and the inlet of the tertiary expander. 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 plurality of heaters are all connected in series to the heating pipeline. The second heat exchange channels of the plurality of heaters are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe, and the sixth connecting pipe.

[0012] In one embodiment of the present invention, the heating pipeline includes a main heating pipe and a plurality of 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 pipes are respectively connected to the main heating pipe, and the heater is connected in series on the branch pipes.

[0013] In one embodiment of the present invention, the second heat exchanger has a first heat exchange channel and a second heat exchange channel that exchange heat with each other. The second heat exchange channel is connected in series with the second connecting pipe. The liquid air energy storage system further includes a first heat exchange pipe and a cold storage box. The first heat exchange pipe 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 pipe. The cold storage box is configured to provide cold energy to the cold box.

[0014] 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 that exchange heat with each other. The air compression system further includes a first connecting pipe, which is connected in series with a plurality of air compressors. The fourth heat exchange channel is connected in series with the first connecting pipe, and the fifth heat exchange channel is connected in series with the first heat exchange pipe. The air compression system further includes a return pipe, which is connected to the outlet of the gas-liquid separator and the air inlet of the air compressor unit. The third heat exchange channel is connected in series with the return pipe.

[0015] In one embodiment of the present invention, the thermal power unit system further includes a boiler, the boiler being provided with a flue gas exhaust pipe, and the liquid air energy storage and thermal coupling and energy cascade utilization system for the thermal power unit further includes a flue gas waste heat utilization system, the flue gas waste heat utilization system including: a second heat storage tank, the second heat storage tank being disposed in the flue gas exhaust pipe; a second heat exchange pipe and a three-way valve, the second heat exchange pipe being switchably connected to the first heat storage tank and the second heat storage tank through the three-way valve, the second heat exchanger having a second heat exchange channel and a third heat exchange channel for mutual heat exchange, the second heat exchange channel being connected in series with the second connecting pipe, and the third heat exchange channel being connected in series with the second heat exchange pipe.

[0016] In one embodiment of the present invention, the liquid air energy storage system further includes a pressurizing pump, which is disposed on the second connecting pipe and located between the liquid storage tank and the second heat exchanger.

[0017] 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.

[0018] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization according to an embodiment of the present invention.

[0020] Figure label:

[0021] 11. First steam turbine; 111. High-pressure cylinder; 112. Intermediate-pressure cylinder; 113. Low-pressure cylinder;

[0022] 12. Boiler; 121. Flue gas piping; 13. Condenser;

[0023] 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;

[0024] 30. Compression heat recovery system; 31. Recovery pipeline; 32. First heat storage tank;

[0025] 401. Second connecting pipe; 402. Heating pipe; 403. First heat exchange pipe; 404. Return gas pipe;

[0026] 41. Cold box; 42. Expansion refrigeration unit; 43. Gas-liquid separator; 44. Liquid storage tank; 45. Second heat exchanger;

[0027] 46. ​​Air expander unit; 461. Primary expander; 462. Secondary expander; 463. Tertiary expander;

[0028] 47. Heater; 48. Cold storage tank; 49. Pressure pump;

[0029] 50. Flue gas waste heat utilization system; 51. Second heat exchange pipeline; 52. Second heat storage box; 53. Three-way valve;

[0030] 100. Liquid air energy storage and thermal coupling with thermal power units and energy cascade utilization system. Detailed Implementation

[0031] Embodiments of the present invention are described in detail below. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0032] The following is for reference. Figure 1A liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization according to an embodiment of the present invention is described.

[0033] like Figure 1 As shown, the liquid air energy storage and 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.

[0034] 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, wherein the second steam turbine 21 is configured to drive the air compressor unit 22 using the extracted steam from the first steam turbine 11, and the air compressor unit 22 includes a first connecting pipe 23 and multiple air compressors connected in sequence, with a first heat exchanger 24 connected in series at the outlet of each air compressor; the compression heat recovery system 30 includes a first heat storage tank 32 and a recovery pipe 31, wherein the first heat storage tank 32 is located on the recovery pipe 31, and the first heat exchanger 24 is connected in series on the recovery pipe. 31, so that the fluid in the recovery pipeline 31 exchanges heat with the compressed air, the first heat storage box 32 is located downstream of the multiple first heat exchangers 24 in the direction of fluid flow in the recovery pipeline 31, and the first heat storage box 32 is provided with heat storage components; 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, and the cold box 41 is configured to cool the compressed air.

[0035] In this embodiment, the liquid air energy storage and 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, turning the water into steam to drive a steam turbine, which in turn drives a generator to generate electricity, thus meeting the usage requirements of the liquid air energy storage and thermal coupling and energy cascade utilization system 100. For 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 feedwater pump, a high-pressure heater 47, and a first steam turbine 11, etc., to meet the operation requirements 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, enabling the thermal power unit to operate and generate electricity efficiently.

[0036] In this embodiment, the liquid air energy storage and 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 equipped with a second steam turbine 21 and an air compressor unit 22. The second steam turbine 21 uses the extracted steam from the first steam turbine 11 to drive the air compressor unit 22 to operate, so that the air compressor unit 22 compresses air under the drive of the second steam turbine 21. The air compressor unit 22 includes multiple air compressors connected in sequence. That is, the multiple 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 further compression. In this way, the air is compressed step by step, which can make the air compressor unit 22 compress the air efficiently, and make the air compression system operate more efficiently and stably.

[0037] In this embodiment, a first heat exchanger 24 is connected in series at the outlet of the air compressor. Exemplarily, the number of first heat exchangers 24 can be the same as the number of air compressors. For example, if the air compressor unit 22 has three air compressors, the number of first heat exchangers 24 can also be three. The compression heat recovery system 30 includes a first heat storage tank 32 and a recovery pipeline 31. Multiple first heat exchangers 24 are connected in series on the recovery pipeline 31 so that the fluid in the recovery pipeline 31 exchanges heat with the compressed air formed after the air compressor compresses the air. The first heat storage tank 32 is located downstream of the multiple first heat exchangers 24 in the direction of fluid flow in the recovery pipeline 31. Exemplarily, the fluid in the recovery pipeline 31 can be a heat transfer fluid such as heat transfer oil. When the air compression system is operating, the air enters the air compressor, is compressed, and its temperature rises. The compressed air flows through the first heat exchanger... Heat exchanger 24 exchanges heat with heat exchange fluid in recovery pipeline 31, so that the heat in the compressed air is transferred to the heat exchange fluid in recovery pipeline 31. After the compressed air is cooled down by heat exchange, it enters the next stage air compressor for compression again. The compressed air then passes through another first heat exchanger 24 for heat exchange. In this way, the heat of compression in the compressed air compressed by multiple air compressors is transferred to the heat exchange fluid in recovery pipeline 31. The heat exchange fluid exchanges heat with heat storage components in the first heat storage box 32, so that the heat of compression generated when the air compression system is running is more fully recovered and stored.

[0038] In this embodiment, the air compressor unit 22 is configured as a multi-stage compression unit, and a first heat exchanger 24 is provided at the outlet of each air compressor. This allows the compressed air to be cooled by heat exchange in the first heat exchanger 24 before entering the next stage air compressor. This reduces energy loss during the operation of the air compressor, resulting in higher overall compression efficiency and lower energy consumption for the air compressor unit 22. This also increases the operating efficiency of the second steam turbine 21. Furthermore, the heat generated during the operation of the air compressor unit 22 is recovered stage by stage through the cooperation of multiple first heat exchangers 24 and the compression heat recovery system 30, making heat recovery more thorough. This allows the air compression system to work with the compression heat recovery system 30 to more fully recover the energy extracted from the first steam turbine 11.

[0039] When the thermal power unit system is operating at low load, the redundant steam in the first steam turbine 11 can be extracted to the second steam turbine 21 to drive the second steam turbine 21. Thus, the heat and kinetic energy of 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. This allows the excess extracted steam energy during the operation of the thermal power unit system to be fully recovered. The heat energy stored in the first heat storage tank 32 can be flexibly utilized in the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 as needed, which significantly improves the overall energy efficiency of the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100.

[0040] In this embodiment, the liquid air energy storage system includes a cold box 41, an expansion compressor 42, and a gas-liquid separator 43 connected in sequence. The cold box 41 is connected to the outlet of an air compressor unit 22. Air is compressed by the air compressor unit 22 and cooled by multiple first heat exchangers 24 before flowing into the cold box 41. The cold box 41 further cools the compressed air, lowering its temperature so that the compressed air can be more stably liquefied into liquid air after entering the expansion compressor 42, resulting in less gaseous air in the fluid flowing out of the expansion compressor 42. The gas-liquid separator 43 separates the gaseous air from the liquid air. The liquid air flows out from the outlet of the gas-liquid separator 43 and into a storage tank 44 for storage, allowing the compressed air to store cold energy in the form of liquid air. This results in high energy storage density. For example, the stored cold energy can... The system can be used to provide a cold source for the cooling operation of the cold box 41 or for other cooling needs. Liquid air can be heated and vaporized by the compression heat stored in the first heat storage box 32 and then used for power generation and other purposes. For example, after being heated and pressurized, liquid air can be used to drive the operation of an air expander, which in turn drives a generator to generate electricity. During the operation of the liquid air energy storage and 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 work together to fully recover and flexibly utilize the redundant heat energy generated by the thermal power unit system. This can well meet the energy storage and reuse needs in the peak shaving scenario of the thermal power unit system, making the overall energy efficiency of the liquid air energy storage and thermal coupling and energy cascade utilization system 100 higher and the operating cost lower.

[0041] According to an embodiment of the present invention, a liquid air energy storage and thermal coupling system 100 for thermal power units and energy cascade utilization comprises an air compression system, a compression heat recovery system 30, and a liquid air energy storage system. The air compression system includes an air compressor unit 22, which consists of sequentially connected air compressors. The compression heat recovery system 30 uses a recovery pipeline 31 to recover and store the heat from the compressed air discharged after compression by each air compressor in stages through a first heat exchanger 24 in a first heat storage tank 32. The liquid air energy storage system... After being liquefied, the gas is stored in the liquid storage tank 44. This allows the redundant thermal energy of the thermal power unit system to be extracted to the second steam turbine 21. With the cooperation of the air compression system, the compression heat recovery system 30, and the liquid air energy storage system, the redundant thermal energy of the thermal power unit is stored as heat energy in the first heat storage tank 32 and the liquid storage tank 44, respectively. This allows the redundant thermal energy of the thermal power unit to be fully recovered and utilized more flexibly. As a result, the overall energy efficiency of the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 is greatly improved and the operating cost is reduced.

[0042] In some embodiments of the present invention, such as Figure 1As shown, the air compressor unit 22 may include 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 pipe 23, which includes a first connecting pipe, a second connecting pipe, and a third connecting pipe. The first connecting pipe is connected to the outlet of the first-stage compressor 221 and the inlet of the second-stage compressor 222. The second connecting pipe is connected to the outlet of the second-stage compressor 222 and the inlet of the third-stage compressor 223. The third connecting pipe is connected to the outlet of the third-stage compressor 223 and the cold box 41. A first heat exchanger 24 is connected in series on the first connecting pipe, the second connecting pipe, and the third connecting pipe, respectively.

[0043] 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 connecting the outlet of the third-stage compressor 223 and the cold box 41. The structure is simple and can well meet the flow requirements of air compression 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 perform stepwise recovery of the compression heat of the air compressor unit 22 during operation through the first heat exchanger 24 on the first connecting pipe, the second connecting pipe, and the third connecting pipe. This allows the compression heat of the air compressor unit 22 during operation to be recovered more fully, so that the redundant heat energy of the thermal power unit system during low-load operation can be fully recovered and utilized.

[0044] Optionally, the air flow direction in the first connecting pipe 23 is opposite to the flow direction of the heat exchange fluid in the recovery pipe 31. This can improve the heat exchange efficiency of the first heat exchanger 24, allowing the recovery pipe 31 to more fully recover the heat of compression in the compressed air, and making the temperature of the compressed air discharged from the air compressor unit 22 lower. This allows the liquid air energy storage system to operate and store energy more efficiently, thereby making the overall energy efficiency of the liquid air energy storage and thermal coupling and energy cascade utilization system 100 higher.

[0045] In some embodiments of the present invention, such as Figure 1As shown, the liquid air energy storage system may further include: a second heat exchanger 45 and a second connecting pipe 401, an air expander unit 46, a generator, and a heating pipe 402. The second connecting pipe 401 is connected to the liquid storage tank 44. The second heat exchanger 45 is connected in series with the second connecting pipe 401 and is configured to heat the fluid in the second connecting pipe 401 to vaporize the liquid air. The air expander unit 46 is connected in series with the second connecting pipe 401 and is located downstream of the second heat exchanger 45 in the direction of fluid flow in the second connecting pipe 401. The unit 46 includes multiple air expanders connected in sequence along the fluid flow direction in the second connecting pipe 401. The air expander unit 46 is driven connected to the generator. The inlet of each air expander is connected in series with a heater 47. There is a heating pipe 402. One end of the heating pipe 402 is connected to the exhaust port of the second steam turbine 21. The thermal power unit system also includes a condenser 13. The other end of the heating pipe 402 is connected to the condenser 13. The heater 47 is connected in series with the heating pipe 402 so that the fluid in the heating pipe 402 heats the fluid in the second connecting pipe 401.

[0046] In this embodiment, the liquid air energy storage system also includes a second heat exchanger 45 and a second connecting pipe 401. The second heat exchanger 45 and the air expander unit 46 are connected in series on the second connecting pipe 401. The second connecting pipe 401 is connected to the liquid storage tank 44. The second heat exchanger 45 heats the fluid in the second connecting pipe 401 to vaporize the liquid air. The generator is connected to the air expander unit 46 for transmission. When the air expander unit 46 is running, the liquid air in the liquid storage tank 44 can be heated and vaporized by heat exchange through the second heat exchanger 45 along the second connecting pipe 401. After being heated by the heater 47, it enters the air expander, thereby driving the air expander to run and thus driving the generator to generate electricity.

[0047] In this embodiment, the heater 47 is connected in series between the heating pipe 402 and the second connecting pipe 401. One end of the heating pipe 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. This allows the air in the second connecting pipe 401 of the air expander unit 46 to be heated using the waste heat from the exhaust of the second steam turbine 21. This reduces the need for additional heat sources and allows for further recovery and utilization of the extracted steam heat energy from the thermal power unit. As a result, when the thermal power unit system is operating at low loads, redundant heat energy can be more fully recovered and utilized, resulting in higher overall energy efficiency when the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 is in operation.

[0048] The electrical energy generated by the generator driven by the air expander unit 46 can be supplied to other equipment as needed or stored to increase the output power of the thermal power unit system when it is operating at high load, so as to more stably meet the power generation demand.

[0049] In this embodiment, the air expander unit 46 includes multiple air expanders connected in sequence. These air expanders are connected sequentially along the flow direction of the fluid in the second connecting pipe 401. Each air expander has a heater 47 connected in series at its inlet. When the air expander unit 46 is operating, the liquid air is heated and vaporized by the second heat exchanger 45 and then flows into the heater 47 for further heating. This allows the air entering the air expander to drive it to operate efficiently. The air exiting the air expander is heated again by another heater 47 along the second connecting pipe 401 before entering the next stage air expander. This allows the multiple air expanders to be arranged in stages according to the temperature and pressure of the evaporating air in the second connecting pipe 401, thereby adapting to the temperature and pressure of the evaporating air. The expansion curve enables phased expansion for power generation, allowing each air expander to operate efficiently, improving the efficiency of heat energy to electrical energy conversion. Furthermore, the exhaust steam from the second turbine 21 releases latent heat through heat exchange with multiple heaters 47, gradually heating the air and thus achieving full heat energy recovery. Finally, the exhaust steam from the second turbine 21 flows into the condenser 13 of the thermal power unit system. This allows the extracted steam to circulate among the thermal power unit system, air compression system, compression heat recovery system 30, and liquid air energy storage system. This strengthens the coupling between the liquid air energy storage system and the thermal coupling and energy cascade utilization system 100, resulting in more efficient and stable collaborative operation and maximizing the conversion and recovery of extracted steam energy.

[0050] In one embodiment of the present invention, such as Figure 1 As shown, the air expander unit 46 includes at least a primary expander 461, a secondary expander 462, and a tertiary expander 463 connected in sequence. The second connecting pipe 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 primary expander 461. The fifth connecting pipe is connected to the outlet of the primary expander 461 and the inlet of the secondary expander 462. The sixth connecting pipe is connected to the outlet of the secondary expander 462 and the inlet of the tertiary expander 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 multiple heaters 47 are all connected in series to the heating pipe 402, and the second heat exchange channels of multiple heaters 47 are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe, and the sixth connecting pipe.

[0051] In this embodiment, the air expander unit 46 includes at least a primary expander 461, a secondary expander 462, and a tertiary expander 463 connected in sequence. That is, the air expander unit 46 is provided with at least three air expanders. The air expander unit 46 can be provided with four, five, or other numbers of air expanders as needed. The number of heaters 47 can be the same as the number of air expanders.

[0052] 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 to the liquid storage tank 44. The fifth connecting pipe connects the first-stage expander 461 to the second-stage expander 462. The sixth connecting pipe connects the second-stage expander 462 to the third-stage expander 463. The structure is simple and can meet the flow requirements of air in the air expander unit 46.

[0053] 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 with the heating pipe 402, and the second heat exchange channel is connected in series with the second connecting pipe 401. The structure is simple and can well meet the heat exchange needs between the air in the second connecting pipe 401 and the exhaust steam in the heating pipe 402.

[0054] In one embodiment of the present invention, such as Figure 1 As shown, the heating pipe 402 may include a main heating pipe and multiple branch pipes. The two ends of the main heating pipe are connected to the exhaust port of the second steam turbine 21 and the condenser 13, respectively. The two ends of the branch pipes are connected to the main heating pipe, and heaters 47 are connected in series on the branch pipes.

[0055] In this embodiment, the heating pipe 402 is provided with a main heating pipe. The two ends of the main heating pipe are connected to the exhaust port of the second steam turbine 21 and the condenser 13, respectively. The branch pipe is connected in series with the heater 47 and its two ends are connected to the main heating pipe. The first heat exchange channel of the heater 47 is connected in series on the branch pipe. When the second steam turbine 21 exhausts steam, the exhaust steam of the second steam turbine 21 can flow along the main heating pipe sequentially through the first heat exchange channel on multiple branch pipes to heat the air in the second connecting pipe at multiple heaters 47 as needed. 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, so that the operation of the liquid air energy storage and thermal coupling and energy cascade utilization system 100 is more flexible.

[0056] For example, during the operation of the liquid air energy storage and thermal coupling and energy cascade utilization system 100, when the air compression system and the liquid energy storage system cooperate to recover and store the heat of compression and store liquid air in the liquid storage tank 44, the air expander unit 46 can operate or remain on standby as needed. When the air expander unit 46 is running, the exhaust steam of the second turbine 21 flows through the branch pipe to provide a heat source. When the air expander unit 46 is on standby, the exhaust steam of the second turbine 21 can flow directly back to the condenser 13 along the main heating pipe, 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, thereby playing a certain heating role for the condensate in the condenser 13, so that the thermal power unit system can operate more efficiently.

[0057] In one embodiment of the present invention, such as Figure 1 As shown, the second heat exchanger 45 may have a first heat exchange channel and a second heat exchange channel that exchange heat with each other. The second heat exchange channel is connected in series to the second connecting pipe 401. The liquid air energy storage system also includes a first heat exchange pipe 403 and a cold storage box 48. The first heat exchange pipe 403 is connected in series with a 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 direction of fluid flow in the first heat exchange pipe 403. The cold storage box 48 is configured to provide cold energy to the cold box 41.

[0058] 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 storage 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, the cold storage box 48 may be equipped with a cold storage component. 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 exchange with the second connecting pipeline 401 at the second heat exchanger 45. The liquid air in the system exchanges heat with the compressed air in the first heat exchange pipe 403, allowing the liquid air to cool the heat exchange fluid in the first heat exchange pipe 403. The cooled heat exchange fluid then flows to the cold box 41 to exchange heat with the compressed air in the first connecting pipe 23, thereby cooling the compressed air. After heat exchange in the cold box 41, the temperature of the heat exchange fluid increases and it 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 need for an additional cold source and improving the energy utilization efficiency of the air compression system and the liquid air energy storage system. In this embodiment, a cold storage box 48 is connected in series with the first heat exchange pipe 403. When there is a large amount of cold energy in the first heat exchange pipe 403, it can be stored in the cold storage box 48, or when there is a small amount of cold energy in the first heat exchange pipe 403, it can be released. This makes the cold energy utilization of the liquid air energy storage system more flexible and the operation more stable, resulting in higher overall efficiency. Consequently, the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is higher.

[0059] In some examples of the present invention, such as Figure 1 As shown, the cold box 41 may 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 pipe 23, which is connected in series with multiple air compressors. The fourth heat exchange channel is connected in series with the first connecting pipe 23, and the fifth heat exchange channel is connected in series with the first heat exchange pipe 403. The air compression system also includes a return pipe 404, which is connected to the 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 with the return pipe 404.

[0060] In this embodiment, the cold box 41 has a third heat exchange channel, a fourth heat exchange channel and a fifth heat exchange channel. The first heat exchange channel is connected in series with the first connecting pipe 23, and the fifth heat exchange channel is connected in series with 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.

[0061] In this embodiment, the air compression system is also provided with a return pipe 404, which is connected to the 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 on the return 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 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. This can work together with the heat exchange fluid in the first heat exchange tube to cool the compressed air, making the cooling effect of the cold box 41 better and more efficient. At the same time, the cold box 41 uses the gaseous air flowing out of the gas-liquid separator 43 for cooling, 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 the overall energy efficiency of the liquid air energy storage and thermal coupling and energy cascade utilization system 100 during operation higher.

[0062] 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 mix with the air entering the air compressor unit 22 before entering the air compressor unit 22. This results in a lower temperature of the air entering the air compressor unit 22, which further improves the operating efficiency of the air compressor unit 22 to a certain extent. It also allows for more efficient utilization of the cold energy of the air in the return pipe, thereby improving the overall energy efficiency of the liquid air energy storage and thermal coupling and energy cascade utilization system 100.

[0063] In one embodiment of the present invention, such as Figure 1 As shown, the thermal power unit system may also include a boiler 12, which is equipped with a flue gas pipeline 121. The liquid air energy storage and thermal coupling and energy cascade utilization system 100 also includes a flue gas waste heat utilization system 50, which includes a second heat storage box 52, a second heat exchange pipeline 51 and a three-way valve 53.

[0064] Specifically, the second heat storage box 52 is located in the flue gas pipe 121; the second heat exchange pipe 51 is switchably connected to the first heat storage box 32 and the second heat storage box 52 through a three-way valve 53; the second heat exchanger 45 has a second heat exchange channel and a third heat exchange channel that exchange heat with each other; the second heat exchange channel is connected in series to the second connecting pipe 401, and the third heat exchange channel is connected in series to the second heat exchange pipe 51.

[0065] 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, and the flue gas waste heat utilization system 50 is equipped with a second heat storage box 52. The second heat storage box 52 is located in the flue gas exhaust pipe 121, with a simple structure. The second heat storage box 52 can recover and store the heat in the flue gas of the boiler 12, thereby reducing heat energy waste and making the energy utilization rate of the thermal power unit system higher. The second heat exchange pipe 51 is switchably connected to the first heat storage box 32 and the second heat storage box 52 through a three-way valve 53. The third heat exchange channel of the second heat exchanger 45 is connected in series to the second heat exchange pipe 51. When the liquid air energy storage and thermal coupling and energy cascade utilization system 100 of the thermal power unit is operating, the second heat exchange pipe 51 can be connected to the first heat storage box 32 or the second heat storage box 52 as needed.

[0066] For example, when the second heat exchange pipe 51 is connected to the first heat storage tank 32, the heat exchange fluid in the second heat exchange pipe 51, after being heated by heat exchange in the first heat storage tank 32, flows along the second heat exchange pipe 51 to the third heat exchange channel of the second heat exchanger 45, thereby heating the liquid air in the second heat exchange channel. This allows the first heat storage tank 32 to utilize the recovered and stored compression heat to provide a heat source for heating the liquid air. When the second heat exchange pipe 51 is connected to the second heat storage tank 52, the second heat storage tank 52 can utilize the recovered and stored exhaust waste heat to provide a heat source for heating the liquid air, thus enabling the first heat storage tank 32 and the second heat storage tank 45 to... The utilization of the recovered and stored thermal energy in 52 is more flexible. For example, the three-way valve 53 can dynamically adjust the heat supply path from 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 box 32 and the second heat storage box 52, or the load adjustment requirements of the thermal power unit system. This allows the compression heat in the first heat storage box 32 and the exhaust waste heat in the second heat storage box 52 to complement each other for heat supply, 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.

[0067] In one embodiment of the present invention, such as Figure 1 As shown, the liquid air energy storage system may also include a pressurization pump 49, which is located on the second connecting pipe and between the liquid storage tank 44 and the second heat exchanger 45.

[0068] In this embodiment, a pressurizing pump 49 is provided on the second connecting pipe. The pressurizing pump 49 is located between the liquid storage tank 44 and the second heat exchanger 45. It has a simple structure and can pressurize the liquid air and drive the liquid air to flow to the second heat exchanger 45. This ensures that the liquid air has sufficient air pressure after heating and vaporization, allowing the air expander to operate efficiently, thereby making the liquid air energy storage system operate more efficiently. Optionally, the pressurizing pump 49 is a cryogenic pump.

[0069] In some embodiments of the present invention, such as Figure 1 As shown, the first steam turbine 11 may include an intermediate pressure cylinder 112, which is provided with an extraction port. The second steam turbine 21 is connected to the extraction port, and the extraction pressure of the extraction port is greater than or equal to 1 MPa and less than or equal to 3.5 MPa.

[0070] In this embodiment, the intermediate-pressure dry section of the first steam turbine 11 is provided with an extraction port, and the second steam turbine 21 is connected to the extraction port to meet the operating requirements of the air compression system. The extraction pressure of the extraction port refers to the steam pressure extracted from the extraction port. The extraction pressure is set to be greater than or equal to 1 MPa and less than or equal to 3.5 MPa. For example, the extraction pressure of the extraction port can be 1 MPa, 1.2 MPa, 1.5 MPa, 2 MPa, 2.5 MPa, 2.7 MPa, 3 MPa, etc.

[0071] In this embodiment, the extraction steam pressure at the extraction port is set to be greater than or equal to 1 MPa and less than or equal to 3.5 MPa, which makes the steam pressure entering the second steam turbine 21 more suitable, allowing the second steam turbine 21 to operate efficiently. For example, the air compression system may be equipped with an extraction steam pipe connected to the extraction steam 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 according to the load of the air compressor unit 22, so as to ensure the stable operation of the first steam turbine 11 in the thermal power unit system.

[0072] The following will refer to Figure 1 A liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization according to a specific embodiment of the present invention is described.

[0073] like Figure 1 As shown, the liquid air energy storage and 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.

[0074] 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 feedwater pump, and a high-pressure heater 47. The boiler 12 is equipped with a flue gas pipeline 121. The condenser 13, condensate pump, low-pressure heater 47, deaerator, feedwater pump, and high-pressure heater 47 are sequentially arranged 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 equipped with an extraction port.

[0075] The air compression system includes a second steam turbine 21, an air compressor unit 22, a first heat exchanger 24, and a first connecting pipe 23. The second steam turbine 21 is connected to the extraction port of the intermediate pressure cylinder 112 through an extraction pipe. The second steam turbine 21 is drivenly 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 pipe 23. There are three first heat exchangers 24, which are connected in series in the first connecting pipe 23 and located at the outlet of each air compressor.

[0076] 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 three first heat exchangers 24 for heat exchange. The first heat storage tank 32 is equipped with a heat storage element. The first heat storage tank 32 is connected in series with the recovery pipeline 31 and is located downstream of the flow direction of the heat exchange fluid in the three first heat exchangers 24 in the recovery pipeline 31. A circulation pump is provided on the recovery pipeline 31 to drive the heat exchange fluid to flow in the recovery pipeline 31.

[0077] The liquid air energy storage system includes a cold box 41, an expansion chiller 42, a gas-liquid separator 43, a liquid storage tank 44, a return gas pipe 404, a second heat exchanger 45, a second connecting pipe 401, an air expander unit 46, a generator, a heater 47, a heating pipe 402, a first heat exchange pipe 403, a cold storage tank 48, and a pressurizing pump 49. The cold box 41 is connected in series with the first connecting pipe 23, the return gas pipe 404, and the first heat exchange pipe 403. The expansion chiller 42 is connected in series with the first connecting pipe 23 and is located downstream of the cold box 41. The first connecting pipe 23 is connected to the gas-liquid separator 43. The two ends of the return gas pipe 404 are connected to the air inlet of the first-stage compressor 221 and the air outlet of the gas-liquid separator 43, respectively. The liquid storage tank 44 is connected to the liquid outlet of the gas-liquid separator 43 through a pipe.

[0078] 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 expander unit 46 includes a first-stage expander 461, a second-stage expander 462 and a third-stage expander 463 connected in sequence through the second connecting pipeline 401. There are three heaters 47, which are connected in series at the inlets of the first-stage expander 461, the second-stage expander 462 and the third-stage expander 463 respectively. 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 in the heating pipeline 402.

[0079] The cold storage tank 48 is connected in series to the first heat exchange pipeline 403. A circulation 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 pressurizing pump 49 is a cryogenic pump. The pressurizing pump 49 is located in the second connecting pipeline 401 and between the second heat exchanger 45 and the liquid storage tank 44. The generator is connected to the air expander unit 46 for transmission.

[0080] The flue gas waste heat utilization system 50 includes a second heat storage box 52, a second heat exchange pipeline 51, and a three-way valve 53. The second heat storage box 52 is located in the flue gas pipeline 121 and connected in series with the second heat exchange pipeline 51. The first heat storage box 32 is connected in series with 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 box 32, the second pipe is connected in series with the second heat storage box 52, and the main pipe is connected in series with the second heat exchanger 45. A flue gas heat exchange pump may be installed on the flue gas pipeline 121 to drive the flue gas to the second heat storage box 52.

[0081] In this embodiment, 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 are set up. The second steam turbine 21 of the air compression system operates by extracting steam from the first steam turbine 11 in the thermal power unit system. The liquid air energy storage system uses the exhaust heat of the second steam turbine 21 to heat the liquid air so that the air drives the expander unit to operate. The flue gas waste heat utilization system 50 uses 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, so that the thermal power unit system, the air compression system, and the compression heat recovery system 30 can work together. The liquid air energy storage system and the flue gas waste heat utilization system 50 are closely coupled, which makes the overall integration of the liquid air energy storage and the thermal coupling and energy cascade utilization system 100 of the thermal power unit better. When the power system load is low, the thermal power unit system operates at low load. The air compression system, together with the compression heat recovery system 30, the liquid air energy storage system and the flue gas waste heat utilization system 50, stores the redundant thermal energy of the thermal power unit system in the first heat storage box 32, the second heat storage box 52 and the liquid storage box 44 and the cold storage box 48 in various energy forms. When the grid load is high, the generator can be driven by the operation of the expander unit to generate electricity and thus utilize the recovered stored energy.

[0082] For example, when the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is in a low grid load period or the thermal power unit has excess output, the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 can enter the energy storage stage. The steam extracted from the steam extraction port of the intermediate pressure cylinder 112 drives the second steam turbine 21 to operate, which drives 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. The recovered compression heat is stored in the first heat storage box 32. The compressed air is liquefied under the action of the cold box 41 and the expansion refrigeration unit 42. The liquefied air is stored in the liquid storage tank 44. The cooling capacity is stored in the cold storage box 48 through the first heat exchange pipeline 403 and the second heat exchanger 45. The exhaust waste heat in the exhaust pipeline 121 is stored in the second heat storage box 52.

[0083] When the grid load or electricity price increases, the liquid air energy storage and thermal coupling system 100 for thermal power units and energy cascade utilization can enter the energy release stage. After being pressurized by a cryogenic pump, the liquid air 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. Then, in the heater 47, it is heated and evaporated into high-pressure gas using the exhaust steam from the second steam turbine 21. The high-pressure gas then expands and performs work through multiple air expanders, releasing energy. Multiple heaters 47 heat the low-enthalpy steam after each air expander has performed work, thus forming a three-stage heat source combined heating mechanism. The three-way valve 53 is open. By switching between the first thermal storage tank 32 and the second thermal storage tank 52 to heat the liquid air, the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 can flexibly respond to changes in different loads, electricity prices, and operating states, ensuring the continuity and adaptability of the heat source of the second heat exchanger 45. Thus, the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 in 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 integration 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.

[0084] This embodiment utilizes the extraction steam from the intermediate-pressure cylinder 112 to drive the second steam turbine 21, allowing the recovered compression heat and exhaust waste heat to be alternately used for evaporative heating of liquid air. Furthermore, multi-stage compression by the air compressor unit 22 enables cascade recovery of compression heat, while multi-stage expansion by the expander unit performs work. The exhaust steam from the second steam turbine 21 and multiple heaters 47 facilitate multi-stage waste heat utilization. During compressed air liquefaction, the liquid air and the gaseous air discharged from the gas-liquid separator 43 are reused as a cold source. This ensures the full recovery and utilization of redundant thermal energy in the thermal power unit system, forming a complete energy closed loop. This significantly reduces reliance on external electrical energy, resulting in a deep coupling relationship between the thermal power unit system, the air compression system, the compression heat recovery system 30, the liquid air thermal storage system, and the flue gas waste heat utilization system 50 in terms of power drive, heat source supply, and cold energy recovery and utilization within the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100. This leads to higher overall operating efficiency and more flexible adjustment of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100, resulting in higher overall energy efficiency and lower operating costs. The liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 of this application operates flexibly. By dynamically adjusting the heat source path of the second heat exchanger 45 through the three-way valve 53, the liquid air energy storage system can better adapt to different operating conditions, better meeting the needs of peak-shaving scenarios in thermal power plants.

[0085] This embodiment constructs a coupling mechanism of compression heat recovery, flue gas waste heat recovery, extraction steam drive and exhaust steam waste heat cascade release, enabling the thermal power unit to operate efficiently in coordination with the air compression system, compression heat recovery system 30, etc., without reducing output, and enabling the liquid air energy storage and thermal power unit thermodynamic coupling and energy cascade utilization system 100 to operate more efficiently.

[0086] This embodiment sets up an air compression system, a compression heat recovery system 30, and a liquid air energy storage system. The air compression system is equipped with an air compressor unit 22, which consists of air compressors connected in sequence. The compression heat recovery system 30 is equipped with a recovery pipeline 31 that recovers the heat of the compressed air discharged after compression by each air compressor through a first heat exchanger 24 and stores it in a first heat storage tank 32. The liquid air energy storage system liquefies the compressed air and stores it in a liquid storage tank 44. This allows the redundant heat energy of the thermal power unit system during low-load operation to be extracted to the second steam turbine 21. With 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 fully recovered and utilized more flexibly. As a result, the overall energy efficiency of the liquid air energy storage and thermal power unit thermal coupling and energy cascade utilization system 100 is greatly improved and the operating cost is reduced.

[0087] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0088] 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 technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0089] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a communication connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0090] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0091] Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A liquid air energy storage and thermal coupling system for thermal power units, characterized in that, include: A thermal power unit system, the thermal power unit system including a first steam turbine (11); An air compression system includes a second steam turbine (21) and an air compressor unit (22), wherein the second steam turbine (21) is configured to drive the air compressor unit (22) to operate using the extracted steam from the first steam turbine (11), the air compressor unit (22) includes a plurality of air compressors connected in sequence, and each air compressor outlet is provided with a first heat exchanger (24) in series. A compression heat recovery system (30) includes: a first heat storage tank (32) and a recovery pipeline (31). The first heat storage tank (32) is located in the recovery pipeline (31). A first heat exchanger (24) is connected in series in the recovery pipeline (31) so that the fluid in the recovery pipeline (31) exchanges heat with compressed air. 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). A heat storage element is provided in the first heat storage tank (32). A liquid air energy storage system includes: a cold box (41), an expansion chiller (42), a gas-liquid separator (43), and a liquid storage tank (44). The cold box (41), the expansion chiller (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 compressed air. A second heat exchanger (45) and a second connecting pipe (401) are also included. The second connecting pipe (401) is connected to the liquid storage tank (44). The second heat exchanger (45) is connected in series with the second connecting pipe (401) and is configured to heat the fluid in the second connecting pipe (401) to vaporize the liquid air. An air expander unit (46) and a generator are also included. (46) is connected in series to the second connecting pipe (401) and is located downstream of the second heat exchanger (45) in the fluid flow direction in the second connecting pipe (401). The air expander unit (46) includes a plurality of air expanders connected in sequence along the fluid flow direction in the second connecting pipe (401). The air expander unit (46) is driven connected to the generator. The inlet of each air expander is connected in series with a heater (47). Heating pipe (402) is connected at one end to the exhaust port of the second steam turbine (21). The thermal power unit system also includes a condenser (13). The other end of the heating pipe (402) is connected to the condenser (13). The heater (47) is connected in series to the heating pipe (402) so that the fluid in the heating pipe (402) heats the fluid in the second connecting pipe (401).

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

3. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 1, characterized in that, The air expander unit (46) includes at least a first-stage expander (461), a second-stage expander (462), and a third-stage expander (463) connected in sequence. The second connecting pipe (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 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). The sixth connecting pipe is connected to the outlet of the second-stage expander (462) and the inlet of the third-stage expander (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 multiple heaters (47) are connected in series to the heating pipe (402). The second heat exchange channels of multiple heaters (47) are respectively connected in series to the fourth connecting pipe, the fifth connecting pipe, and the sixth connecting pipe.

4. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 1, 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 connected to the exhaust port of the second steam turbine (21) and the condenser (13) respectively. The two ends of the branch pipes are connected to the main heating pipe respectively. The heater (47) is connected in series on the branch pipe.

5. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 1, characterized in that, The second heat exchanger (45) has a first heat exchange channel and a second heat exchange channel that exchange heat with each other. The second heat exchange channel is connected in series with the second connecting pipe (401). The liquid air energy storage system also includes a first heat exchange pipe (403) and a cold storage box (48). The first heat exchange pipe (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 direction of fluid flow in the first heat exchange pipe (403). The cold storage box (48) is configured to provide cold energy to the cold box (41).

6. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 5, 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 pipe (23), which is connected in series with multiple air compressors. The fourth heat exchange channel is connected in series with the first connecting pipe (23), and the fifth heat exchange channel is connected in series with the first heat exchange pipe (403). The air compression system also includes a return pipe (404), which is connected to the 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 with the return pipe (404).

7. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 1, characterized in that, The thermal power unit system also includes a boiler (12), which is provided with a flue gas exhaust pipe (121). 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 (50), which includes: The second heat storage box (52) is located in the exhaust pipe (121); The second heat exchange pipeline (51) and the three-way valve (53) are connected in a switchable manner 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 channel and a third heat exchange channel that exchange heat with each other. The second heat exchange channel is connected in series to the second connecting pipeline (401), and the third heat exchange channel is connected in series to the second heat exchange pipeline (51).

8. The liquid air energy storage and thermal coupling system for thermal power units and the energy cascade utilization system according to claim 1, characterized in that, The liquid air energy storage system also includes a pressurizing pump (49), which is located on the second connecting pipe and between the liquid storage tank (44) and the second heat exchanger (45).

9. The liquid air energy storage and thermal coupling system for thermal power units and energy cascade utilization according to any one of claims 1-8, characterized in that, The first steam turbine (11) includes an intermediate pressure cylinder (112), which 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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